Why some people get very old and others die at an early age have puzzled us for a long time. We try all sorts of things to slow down the ageing process and increase our longevity. But how do we know what works and what doesn’t? Ageing can be considered as a progressive failure in the ability to maintain tissue homeostasis, leading to health decline and the emergence of age-related disease. In the words of Wong 2001; Kirkwood 2005; Schmidt et al. 2005 – “The process of aging is regarded as a progressive functional decline, which can be observed in cells, tissues and organisms, and which results in an increased vulnerability to environmental challenge and a growing risk to suffer disease and to die.”
The history of the ageing theory
In 1908 Rubner published his famous work noting the duration of animal lifespan and its relationship to energy expenditure. The free radical, nowadays called the oxidative stress or the rate of living theory of ageing, took Rubners ideas further and was proposed some 60 years ago. It suggests that a lower metabolic rate means longer life span and higher metabolic rate means a shorter life span, i.e. “live fast, die young”.
Larger animals in general have a low metabolic rate and tend to live longer than smaller animals with a corresponding higher metabolic rate. One explanation for the difference in metabolism is that all species lose heat through the skin and since small animals have more skin surface in relation to their body size, they lose more heat than larger animals. Because of this they need a higher metabolism to produce the heat needed to keep a body temperature of 36-38 degrees Celsius, since this temperature is optimum for protein performance.
A good example is an elephant. It can live up to 80 years and since it has a slow metabolism, the elephant heart beats roughly the same number of beats as the heart of a mouse. The mouse however, with a much faster metabolism, “uses up” it’s heart beats in only 2-3 years.
A number of studies have shown that calorie constriction leads to increased life span, which seems to confirm the oxidative stress theory of ageing, since calorie restriction reduces the metabolism. However, it may also be that these animals that are put on restricted diets are just surviving, but not thriving. Like a bear hibernating, it has very low metabolism, but doesn’t really get much done.
A factor speaking against the theory, or atleast indicating that it is incomplete, is that there are several exceptions. For example birds live longer than their similar sized mammals. Or the fact that physical exercise, which increases metabolism, doesn’t lead to shorter life span.
Below are three more interesting connections in regards to ageing:
1. Carbon dioxide increase fat burning and antioxidant activity through the peroxisomes
The peroxisome is an organelle working very closely with the mitochondria. When the carbon dioxide levels are low, there is less activity in the peroxisomes. The peroxisomes do a lot of important activities, but these are the three major functions:
Control mitochondrial biogenesis (size and number of mitochondria) through the peroxisome PGC-1? pathway. When PGC-1? is activated it stimulates mitochondrial growth. In this cancer-study: Transcutaneous Application of Carbon Dioxide (CO2) Induces Mitochondrial Apoptosis(Ref 1), rats had cancer-cells injected. In one group the rats were exposed to CO2 through the skin. 100% CO2 was administered into a bag that covered the tumor, for 10 minutes twice per week for two weeks. In total 40 minutes, which is not a lot. Despite the tiny CO2 exposure, the tumor volume was reduced by 48% compared to the control group. The researchers concluded that CO2 activated the PGC-1? pathway and hence increased the mitochondrial activity, which in turn made the mitochondria induce apoptosis.
Convert long fatty acids to Acetyl-CoA, so that the Acetyl-CoA can be fed to the mitochondria for conversion to ATP, heat, water, CO2 and free radicals. In contrast to normal length fatty acids, these long fatty acids can’t be burnt directly in the mitochondria, but instead needs to pass through the peroxisomes for conversion first.
Neutralize free radicals. The conversion-process from fat to Acetyl-CoA generates the free radical hydrogen peroxide (H2O2). Consequently, the peroxisomes contain the enzyme catalase, one of the fastest enzymes in our body. Catalase can convert millions of hydrogen peroxide into water and oxygen per second. In other words, catalase is a powerful antioxidant that can neutralize large amounts of free radicals.
In conclusion, the information above means that low CO2 not only lead to reduced mitochondria, as the PGC-1? pathway is downregulated in low CO2, but low CO2 also reduces the size and number of peroxisomes, and thereby decreased ability to burn fat and reduced antioxidant activity, which in turn contributes to increased oxidative stress and a shorter life span.
From one perspective cancer could be viewed mainly as an ageing disease (although some young people also get cancer). Since cancer is very much associated with a) poor mitochondrial function, b) high sugar metabolism and c) oxidative stress, the link between low CO2, peroxisome and mitochondria dysfunction is indeed interesting.
2. Carbon dioxide deficiency may reduce heat production
Another interesting aspect of ageing is uncoupling, which is the ability for the mitochondria to switch to produce more heat instead of ATP-energy. Uncoupling seems to produce fewer free radicals even when metabolism is higher.
So, for example if we over breathe or over eat, more oxygen and/or more nutrients than needed in order to meet the metabolic demand, may reach the cell. The mitochondria can then uncouple and produce heat instead of ATP energy. However, if our ability to uncouple is diminished, the mitochondria will be flooded with oxygen and/or nutrients in overeating / over breathing, and it will leak more free radicals.
Here is an interesting article on the subject: Body size, energy metabolism and lifespan:(Ref 2) – “However, smaller individuals with higher rates of metabolism live longer than their slower, larger conspecifics. An addition to these confused observations has been the recent suggestion that under some circumstances we might expect mitochondria to produce fewer free radicals when metabolism is higher–particularly when they are uncoupled. These new ideas concerning the manner in which mitochondria generate free radicals as a function of metabolism shed some light on the complexity of observations linking body size, metabolism and lifespan.”
A factor that increase the ability to uncouple is the circulation to the skin. If the circulation is good, the extra heat produced in uncoupling can escape through the skin. However, if the blood circulation to the skin is not so good, which is the case when CO2 is low, it may lead to problems with uncoupling. Below we discuss heat production and circulation to the skin in relation to thyroid function.
3. Membrane fatty acid composition correlates with maximum lifespan
The organelles in our cells (mitochondria, nucleus, peroxisomes etc.) are highly specialized and can be likened to rooms in a house – kitchen, bedroom, toilet, living room etc. Just as the house have outer walls to protect the house from the weather and unwelcome guests and inner walls to separate the rooms from each other, the cell has an outer wall, the cell membrane, to protect the cell from virus, bacteria and unwanted substances and the organelles have walls as well, mitochondrial membrane etc, to separate the organelles from each other.
The cellular and organelle membranes are made up of fatty acids. The correlation between membrane composition and longevity is called the membrane pacemaker theory of ageing and the lipid peroxidation index. The theory states that in general polyunsaturated fatty acids (PUFA) are more susceptible to oxidative stress than saturated and monounsaturated fatty acids. It also seems evident that the more omega 6 polyunsaturated fatty acids (in relation to omega 3), the shorter the lifespan. For humans, omega 6 is to be found in junk food. Here are some interesting articles on the subject:
Explaining longevity of different animals: is membrane fatty acid composition the missing link?:(Ref 3) “Saturated and monounsaturated fatty acids are very resistant to peroxidative damage, while the more polyunsaturated a fatty acid, the more susceptible it is to peroxidation. Membrane fatty acid composition is correlated with the maximum lifespans of mammals and birds. Exceptionally long-living mammal species and birds have a more peroxidation-resistant membrane composition compared to shorter-living similar-sized mammals. Membrane fatty acid composition is little appreciated but important correlate to the rate of aging of animals and the determination of their longevity.”
The importance of the ratio of omega-6/omega-3 essential fatty acids:(Ref 4) “Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in Western diets the ratio is 15/1-16.7/1. Western diets are deficient in omega-3 fatty acids, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved and their genetic patterns were established. Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today’s Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) exert suppressive effects.”
Oxidative Stress and Lipid Peroxidation Products in Cancer Progression and Therapy:(Ref 5) “The lipid peroxidation and the breakage of lipids with the formation of reactive compounds can lead to changes in the permeability and fluidity of the membrane lipid bilayer and can dramatically alter cell integrity.”
We can’t live without oxygen
The reason why we only survive a few minutes without breathing is because of energy deficiency. The oxygen that we inhale is needed in order to produce energy efficiently. With the aid of oxygen we can extract up to 100% of the available energy in the food we eat, while only 6% of the energy can be extracted without oxygen.
This says a lot about how important oxygen is for our survival. But even though we are so extremely dependent of oxygen we store very little of it at any given time. At rest we consume about 250 ml of oxygen per minute, so even if we were able to use up all of the approx. 1,6 liter of oxygen that we store (for a 70 kg person), which we probably can’t, it will still only last for about 6-7 minutes (Ref 6).
So why do we have so little oxygen? In comparison to the approx. 120 liter of carbon dioxide that we store, the amount of oxygen is 75 times less. It is because oxygen is so reactive and too much of it is dangerous and toxic (leads to oxidative stress), so we can only allow some of the oxygen to reach the mitochondria at any given time.
The vast majority of our energy, 90%, is produced in the mitochondria in the cells. The mitochondria are often likened to an incinerator and it is easy to understand the danger of oxygen if we think of spraying it on a normal fire. When the oxygen hits the fire, the reaction will be very explosive. That’s why the energy production in the mitochondria is divided into several steps, so that there won’t be any “oxygen explosions”.
Carbon dioxide paves the way for oxygen
The major function of breathing is to inhale oxygen and exhale the carbon dioxide produced in the metabolism process. And it is easy to think of oxygen as the lifesaver and CO2 as the waste product. But it is actually the other way around.
It is carbon dioxide that paves the way for oxygen, all the way from initiating the inhale of air (through the phrenic nerve that signals to the diaphragm to move downwards), to kicking off the oxygen from the blood at the cellular level.
Inhale: CO2 tells the brain stem, by lowering the pH to the level where the breathing center is triggered to start an inhalation.
Airways: CO2 makes the smooth muscles in the airways relax so that they can open up and let the air into the lungs.
Blood: CO2 makes the smooth muscles in the blood vessels relax so that they open up and circulation can occur easily.
Cells: According to the Bohr-effect CO2 lowers pH, which reduces hemoglobin affinity for oxygen and the O2 is released from the blood to the cells.
In conclusion, an optimum carbon dioxide pressure is needed in order to oxygenate our body in the most efficient way.
Too many free radicals equals oxidative stress
For every cycle that the electron transport chain runs in the mitochondria, in order to produce the energy we need to survive and thrive, it will also produce free oxygen radicals. Free radicals are not bad per se, instead they make up an important signal pathway that are involved in for example cell division and angiogenesis (the process where the capillary network increases, so that the cell can get more blood, oxygen and nutrients and remove waste).
This is logical, since if we exercise, the metabolism increases, and more free radicals are formed, which leads to increased cell division and angiogenesis that is needed in order to meet the increased demand from the cell.
The problem arises when we have an excess of free radicals, either because too many are formed or because the antioxidant system that is supposed to neutralize the free radicals, is compromised. Too many free radicals is also called oxidative stress.
Reduced thyroid function when carbon dioxide is low
So in conclusion oxygen is a double edged sword, where too little leads to death and too much increases free radicals and oxidative stress.When we over breathe the carbon dioxide pressure in our body decreases, which have a negative impact on circulation since CO2 widens the blood vessels. In poor circulation our body prioritizes blood flow to the most important organs – kidneys, lungs, heart and brain. The first organ to receive less blood is the skin, followed by our muscles.
In thyroid problems it is common that the skin is dry, irritated and coarse, which indicates that the blood circulation to the skin isn’t optimum. When this happens, two important negative effects happen. The first is that it is harder to tolerate heat. Since our skin is responsible for controlling our body temperature, poor blood flow to the skin creates problems with heat regulation.
So if the body gets too hot it can’t get rid of the excess heat through the skin and our core temperature increases. The only way for the body to compensate for this is by reducing the activity in the thyroid, as the thyroid is responsible for body metabolism and thereby also heat production. So an important reason for an underactive thyroid is to compensate for poor circulation to the skin, which occur because of over breathing that lowers the CO2 pressure, which in turn makes the blood vessels constrict.
Increased soda consumption to increase carbon dioxide
The consumption of carbonated beverages in our society is very big. Why do we like to drink carbonated beverages? A main reason is because they contain CO2, and the increased consumption can be viewed as a result of our body simply recognizing the low levels of CO2 and that they need to be refilled.
And the reason why we prefer a cold soda or beer over a warm one, is because warm drinks lose their CO2 to the atmosphere faster. So when the carbonated drink is warm it contains less CO2 and therefore doesn’t taste as good. The reason we don’t find the taste as appealing is probably because our body doesn’t get the CO2 it is looking for.
Another reason for the big consumption is also breathing related and have to do with our energy production. When we produce energy we can do it in two ways, with our without oxygen. Energy production with oxygen is a complex and fairly slow process, but on the other hand up to 100% of the available energy can be extracted from the nutrients we ingest. Energy production without oxygen, on the other hand, is indeed simple and fast, but only 6% of the available energy is extracted.
When the CO2 pressure is lower the oxygenation is impaired, which forces us to produce more of the energy without oxygen and in the long term use simpler and simpler sources of energy. It is possible that the more often we choose energy sources that are simple for our body to convert to energy, the “simpler” we will over time become as a person. WE need a balance between complexity and simplicity.
Fungi produces carbon dioxide and may increase when the CO2 levels are low
Fungi and their spores are everywhere. They are present in air, so with every breath we inhale hundreds of fungi spores. Although, with nasal breathing we can probably stop most of them from entering the lungs. They are also in the soil forming mykorrhiza – an amazing symbiotic relationship between microscopic fungi spores growing into the roots of trees and plants, heping each other to take up nutrients.
The fungi spores can even be found in rocks. For millions of years they have done an important job in tearing up rocks into smaller and smaller rock crystals until eventually soil has been formed.
Fungi produce carbon dioxide. An effect of over breathing (and inactivity) that decreases the CO2-pressure in our body, could then be that more fungi is formed in order to “try to maintain a normal CO2 pressure and pH”, for example in the skin and gut. A few examples:
Skin infections. The pH of the skin is normally between 4-5. Poor circulation to the skin, because of low CO2, may raise skin pH (as CO2 is acidic), hence provide a favorable environment for fungi and diseases like athlete’s foot, ringworm and other fungal infections of the skin may develop.
Candida. The gut microbiome consists of enormous amounts of bacteria and other micro organisms, and one of these inhabitants is the family of yeast fungi called candida. When the candida get the opportunity they will start to multiply rapidly (the fungi is opportunistic). Candida infections can occur in the mouth, throat, gut and the vagina, and also in the blood.
Cryptococcus gattii. This yeast is primarily responsible for cryptococcosis, a fungal disease that occurs in about one million HIV/AIDS patients, causing over 600,000 deaths annually.
High carbon dioxide levels in social insect colonies
CO2 concentration ranges from 1 to 2 percent in ant colonies, 0.8–5.2 percent in termite colonies and 0.2–9.9 percent in honey bee (Apis mellifera L.) colonies. Even though there is a considerable variation, it by far exceeds the normal levels in the atmosphere of 0,04%. The high CO2-levels could explain why the queen live far longer than her colony workers. Since the queen is in the colony all the time, she is constantly exposed to these high CO2 levels.
THE BEE QUEEN A bee queen could be three to four years old, compared to a normal bee worker that only live for two to three months, she lives ten to twelve times longer.
Scientists Explore Queen Bee Longevity:(Ref 7) “The queen honey bee is genetically identical to the workers in her hive, but she lives 10 times longer. Many times the way organisms achieve longevity is via a tradeoff with reproduction,” said entomology professor Gene Robinson, principal investigator on the study. “In general, life forms that postpone reproduction until later in life live longer. But the queen bee has her cake and eats it too. She’s an egg-laying machine. She lays 2,000 eggs a day and yet lives 10 times longer than individuals that stem from the same genome and yet do not reproduce.”
Extended longevity of queen honey bees compared to workers is associated with peroxidation-resistant membranes:(Ref 8) “Assuming the same slope of the relationship between membrane peroxidation index and maximum lifespan as previously observed for mammal and bird species, we propose that the 3-fold difference in peroxidation index of phospholipids of queens and workers is large enough to account for the order-of-magnitude difference in their longevity.”
THE TERMITE QUEEN Termites are among the most successful groups of insects on Earth, colonising all landmasses except Antarctica. The Termite Queen has a long life span. She can live up to 50 years, the longest for any insect. In comparison, termite workers normally live only ont to two years.
Termites have a very organized society – workers are responsible for building the nest and collect dead wood, plants and leaves, soldiers defending the colony, and a queen and king are responsible for reproduction. Termite species in Africa and Asia have been cultivating fungi for consumption for tens of millions of years. And they do it well as the harvest of a colony retain the same high yield level for up to several decades. As mentioned above, the interesting thing is that fungi give off carbon dioxide.
An Efficient Antioxidant System in a Long-Lived Termite Queen:(Ref 9) “These long-lived queens have a significantly lower level of oxidative damage, including oxidative DNA damage, than workers, soldiers and nymphs. The lower levels of damage appear to be due to increased catalase, an enzyme that protects against oxidative stress.”
Sociobiology and Natural Adaptation of Termite and Termitomyces in Different Forest Division of Gorakhpur Region:(Ref 10) “Some species of Termite practice fungi culture. They maintain a garden of specialized fungi Termitomyces, which are nourished by the excrement of the insect. When the fungi are eaten, their spores pass undamaged through the intestine of the termite to complete the cycle by germinating in the fresh faecal pellets. The termites cultivate the fungus on special structures within the nest called fungus combs. These fungus combs are continuously provided with externally derived plant material (e.g. wood, dry grass, leaf litter), while the older parts, consisting of partially degraded plant material and fungal mycelium and nodules (asexual fruit bodies covered with conidia) are consumed . All species in the genus Termitomyces are completely dependent on the termites since they have never been found free-living and they are rapidly overgrown by other fungi, when removed from the termite nest.”
Why exceptionally fertile termite queens have long lives:(Ref 11) “Usually the rule in the animal kingdom is that a lot of progeny means a short life – if you are less fertile, you live longer. ‘Macrotermes queens are the most reproductively successful terrestrial animals,’ says Freiburg biologist Prof. Dr. Judith Korb. Termite queens lay continuously about 20,000 eggs daily. And yet they reach ages of up to 20 years. Workers from this species have the same genome as the queen, but are infertile and only live for a few months.”
The architecture of termite mounds: a result of a trade-off between thermoregulation and gas exchange?:(Ref 12) “Although termites can, at least for some time, survive under high concentrations of CO2, a colony, with up to 6 million individuals (Lüscher, 1961) and its cultivated fungi, needs a sufficient gas exchange. Lüscher (1961) measured CO2 concentrations of up to 2.8% in the center of M. bellicosus nests, and Matsumoto (1978) recorded concentrations of up to 5.2% in the center of other Macrotermitinae nests.”
Termite World | Life In The Undergrowth | Richard Attenborough: “The fungus-growing termite is the most common and widely distributed member of all Macrotermes in southern Africa. They live in nests that are kept at a constant temperature by a remarkable piece of engineering, a spiralled mound consisting of a network of vents and tunnels set around one central chimney. As their names suggests these termites actually cultivate fungus to digest the food which they are unable to do so themselves.”
THE ANT QUEEN The ant queen can live for up to 30 years, but workers live only one to three years. Apart from humans, ants are the most successful species in spreading around the globe. The tunnel system and space under the visible nest could reach 5-6 meters below ground and have an area as big as a tennis court. Just as termites they have an organized society and many species also cultivate fungus, which give off CO2.
Longevity of harvester ant colonies in southern Idaho:(Ref 13) “In the ant species, pogonomyrmex owyheei, the queen ant has a maximum estimated longevity of 30 years, while worker ants live only one or two years.”
Carbon dioxide concentrations and nest ventilation in nests of the leaf-cutting ant Atta vollenweideri:(Ref 14) “Gas exchange between nest and environment is essential. Due to colony respiration considerable amounts of O2 are consumed and CO2 produced. In closed dwellings this leads to hypoxic (low oxygen) and hypercapnic (high carbon dioxide) conditions.”
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Other land animals with high tolerance for carbon dioxide
One aspect in relation to ageing is the breathing frequency. We know that dogs, cats and mice have a high respiration rate and live a markedly shorter period of time, compared to a giant tortoise that only takes about four to five breaths per minute and can live up to 200 years and an elephant only takes four to six breaths per minute and can become up to 80 years old.
NAKED MOLE RAT This fascinating little creature can be up to 30 years old, which is 10-15 times longer than their similar sized cousin, the mouse. The naked mole rat lives about a meter below ground, where the oxygen levels are low and the CO2 levels are high. They have a slow respiration, can survive up to 18 minutes without oxygen and suffer from very little oxidative stress.
Weird: Naked Mole Rats Don’t Die of Old Age:(Ref 15) “ ’The chance of a mole rat dying at one year of age or dying at 25 years of age is the same. We really don’t know what’s killing them at this point.’ Buffenstein told Live Science. It would be like if humans were equally likely to die at 30 as at 90, she said.”
The Naked Mole-Rat Response to Oxidative Stress: Just Deal with It:(Ref 16) “Strikingly, these animals are very resistant to cancer, with no case ever reported in our large colony maintained for over 30 years. This is in sharp contrast to data based upon laboratory rodents. For example, >70% of C57Bl/6 mice die of cancer in the laboratory setting. Not only are naked mole-rats resistant to cancers, but they also appear to resist many of the age-associated diseases. We have found that unlike mice, naked mole-rats show a markedly slower age-related change in diastolic function with approximately a 25% decline over 20 years, whereas the change in diastolic function over a similar proportion of lifespan in C57Bl/6 mice is more than a 50% decline.”
BATS Bats can live up to 40 years. An important factor why they get so old, despite being so small, is probably because they live in the caves where their own excrement is rich in ammonia. The ammonia escapes into the air and gives rise to the smell characteristic for bat populated caves. Ammonia is alkaline and when inhaling it the bats get alkaline, hence they retain carbon dioxide, which is acidic, in order to cope with the high levels of CO2.
Ageing studies on bats: a review:(Ref 17) “Bat biologists have long known about the exceptional longevity of bats (Order: Chiroptera), which is unusual for mammals of such a small size and a high metabolic rate.”
Ammonia Tolerance of the California Leaf-Nosed Bat:(Ref 18) “Investigators have often mentioned the extremely unpleasant working conditions in the ammoniated atmosphere of caves and mines frequented by large number of bats…Since this condition occurs in the normal habitat of these animals, interest was aroused regarding their unusual tolerance to ammonia.”
Carbon Dioxide Retention: A Mechanism of Ammonia Tolerance in Mammals:(Ref 19) “Passive carbon dioxide retention is clearly related to ammonia tolerance in these mammals.”
Elevated Carbon Dioxide Levels in Bayliss Cave, Australia: Implications for the Evolution of Obligate Cave Species:(Ref 20) “The downward-sloping cave acts as a trap for CO2 , because CO2 is 1.5 times heavier than air. Between The Wall and The Duckunder is a zone of mixing in which the CO2 concentration increased nearly five times (from 0.6 to 2.8 volume %). Beyond The Wall the CO2 increased dramatically to a maximum of 5.9%.”
ECHIDNA The echidna is a mammal, although it lays eggs. It could be up to 50 years old which is very old for an animal of this size (it’s weight is only about 3-4 kg).
Control of breathing in the echidna during hibernation:(Ref 21) “Resting non-hibernating echidnas are characterised by low metabolic rates, but also have a very low respiratory frequency and a variable respiratory minute volume, often resulting in low levels of arterial O(2) and high CO(2).”
Respiration by buried echidnas Tachyglossus aculeatus:(Ref 22) “It is clear that echidnas are frequently exposed, at least for short periods, to increased hypoxia and hypercapnia, either when digging into soil or within their burrows (Augee et al., 1971). Previous studies have demonstrated that echidnas are physiologically well suited for burrowing. Augee et al. (Augee et al., 1971) covered echidnas with soil to simulate natural conditions and found them to be very tolerant of high carbon dioxide (CO2) and low oxygen (O2) under these conditions.”
The exceptional longevity of an egg-laying mammal, the short-beaked echidna is associated with peroxidation-resistant membrane composition:(Ref 23) “These findings support the membrane pacemaker theory of aging and emphasise the potential importance of membrane fatty acid composition in aging and in the determination of maximum longevity.”
Other sea animals with high tolerance for carbon dioxide
Creatures that swim the ocean depths are notoriously difficult to observe in their natural habitat, so there is still much to be learned about many species.
Water contains about 50 times higher levels of CO2 than the atmosphere, which may contribute to the long life of many water living species. And cold waters contains even more CO2.
BOWHEAD WHALE The Bowhead whale can grow 14 to 18 m in length and weigh from 75 to 100 tonnes and they can live over 200 years. They live in the Arctic waters, which has a fairly constant temperature near the freezing point. From a carbon dioxide perspective this is very interesting, as colder water contains more CO2. And this could be an explanation to why the whale lives to such an old age.
Insights into the Evolution of Longevity from the Bowhead Whale Genome:(Ref 24) “It is remarkable that a warm-blooded species such as the bowhead whale (Balaena mysticetus) has not only been estimated to live over 200 years (estimated age of one specimen 211 SE 35 years), suggesting it is the longest-lived mammal, but also exhibits very low disease incidence until an advanced age compared to humans.”
GREENLAND SHARK Just like the Bowhead whale, the Greenland sharks are native to the Arctic (and North Atlantic). It can grow to be up to 7 meters long and weigh up to 1,200 kilo. One study showed that they live up to 300-500 years.
Eye lens radiocarbon reveals centuries of longevity in the Greenland shark:(Ref 25) “The Greenland shark (Somniosus microcephalus), an iconic species of the Arctic Seas, grows slowly and reaches >500 centimeters (cm) in total length, suggesting a life span well beyond those of other vertebrates. Radiocarbon dating of eye lens nuclei from 28 female Greenland sharks (81 to 502 cm in total length) revealed a life span of at least 272 years. Our results show that the Greenland shark is the longest-lived vertebrate known.”
Longest-lived vertebrate is Greenland shark: Lifespan of 400 years:(Ref 26) “Their analysis suggests an average lifespan of at least 272 years. The two largest sharks in this study, at 493 cm and 502 cm in length, were estimated to be roughly 335 and 392 years old, respectively. Based on these results, the Greenland shark is now the oldest-known vertebrate to roam the Earth.”
ANTARCTICA ISLANDICA The Antarctica islandica, also called the ocean quahog clam, shows exceptional longevity. One specimen called “Ming” was estimated to live up to 507 years in the wild. The clam has a slow respiration and can tolerate very low levels of oxygen and high levels of carbon dioxide. The shell traps the CO2 inside, similar to the high CO2 levels in a beehive.
The extreme longevity of Arctica islandica is associated with increased peroxidation resistance in mitochondrial membranes:(Ref 27) “The deleterious reactive carbonyls released upon oxidation of polyunsaturated fatty acids in biological membranes are believed to foster cellular aging. Comparative studies in mammals and birds have shown that the susceptibility to peroxidation of membrane lipids peroxidation index (PI) is negatively correlated with longevity. These results clearly demonstrate that the PI also decreases with increasing longevity in marine bivalves and that it decreases faster in the mitochondrial membrane than in other membranes in general. Furthermore, the particularly low PI values for A. islandica can partly explain this species’ extreme longevity.”
Extreme Longevity Is Associated With Increased Resistance to Oxidative Stress in Arctica islandica, the Longest-Living Non-Colonial Animal:(Ref 28) “Our findings demonstrate an association between longevity and resistance to oxidative stress–induced cell death in A islandica, consistent with the oxidative stress hypothesis of aging and provide justification for detailed evaluation of pathways involving repair of free radical–mediated macromolecular damage and regulation of apoptosis in the world’s longest-living non-colonial animal.”
A metabolic model for the ocean quahog Arctica islandica – Effects of animal mass and age, temperature, salinity and geography on respiration rate:(Ref 29) “Respiration of Arctica islandica is significantly below the average of 59 bivalve species when compared at the same temperature and animal mass.”
Metabolic and physiological responses in tissues of the long-lived bivalve Arctica islandica to oxygen deficiency:(Ref 30) “In Arctica islandica, a long lifespan is associated with low metabolic activity, and with a pronounced tolerance to low environmental oxygen.”
Breathe less and live longer
A reason why humans tend to live longer and longer could probably to some extent be attributed to a) increased CO2 levels in the atmosphere, where it has increased by 60% in the last 270 years, from 0,025% CO2 in 1750, before industrialization, to 0,041% in 2019 and b) people spending more time indoors where the CO2 levels in general are higher than outdoors.
The common denominator for the species listed above, all well known for their extreme longevity, is that they have slow respiration and/or high tolerance for carbon dioxide, i.e. suggesting that the carbon dioxide tolerance theory may be the most important factor determining longevity.
For example, the fundamental difference between someone in a state of panic and someone in deep relaxation isn’t first and foremost a question of the quality of their sleep, food, exercise, relationships etc. The fundamental difference is carbon dioxide tolerance. The person with a panic attack has a fast and shallow breathing with a corresponding low CO2 tolerance, while the person in deep relaxation breathe low and slow and have a high tolerance for carbon dioxide.
There are two main ways to increase the levels of carbon dioxide in your body – reduce the outflow and increase the production. When you slow down your breathing less CO2 is lost via exhalation and when you do physical activity, more CO2 is produced as the metabolism increases. A great way is to combine the two, low intense physical activity while only breathing through your nose. Over time the carbon dioxide tolerance training will reset the breathing center in your brain stem and make you tolerate higher and higher levels of CO2, which in turn may help you to live a healthier and longer life.
1. Transcutaneous Application of Carbon Dioxide (CO2) Induces Mitochondrial Apoptosis in Human Malignant Fibrous Histiocytoma In Vivo
Transcutaneous Application of Carbon Dioxide (CO2) Induces Mitochondrial Apoptosis in Human Malignant Fibrous Histiocytoma In Vivo – Reference, Full text
PLoS ONE 7(11): e49189. Published: November 15, 2012
Mitochondria play an essential role in cellular energy metabolism and apoptosis. Previous studies have demonstrated that decreased mitochondrial biogenesis is associated with cancer progression. In mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) regulates the activities of multiple nuclear receptors and transcription factors involved in mitochondrial proliferation. Previously, we showed that overexpression of PGC-1α leads to mitochondrial proliferation and induces apoptosis in human malignant fibrous histiocytoma (MFH) cells in vitro. We also demonstrated that transcutaneous application of carbon dioxide (CO2) to rat skeletal muscle induces PGC-1α expression and causes an increase in mitochondrial proliferation. In this study, we utilized a murine model of human MFH to determine the effect of transcutaneous CO2 exposure on PGC-1α expression, mitochondrial proliferation and cellular apoptosis.
PGC-1α expression was evaluated by quantitative real-time PCR, while mitochondrial proliferation was assessed by immunofluorescence staining and the relative copy number of mitochondrial DNA (mtDNA) was assessed by real-time PCR. Immunofluorescence staining and DNA fragmentation assays were used to examine mitochondrial apoptosis. We also evaluated the expression of mitochondrial apoptosis related proteins, such as caspases, cytochorome c and Bax, by immunoblot analysis. We show that transcutaneous application of CO2 induces PGC-1α expression, and increases mitochondrial proliferation and apoptosis of tumor cells, significantly reducing tumor volume. Proteins involved in the mitochondrial apoptotic cascade, including caspase 3 and caspase 9, were elevated in CO2 treated tumors compared to control. We also observed an enrichment of cytochrome c in the cytoplasmic fraction and Bax protein in the mitochondrial fraction of CO2 treated tumors, highlighting the involvement of mitochondria in apoptosis. These data indicate that transcutaneous application of CO2 may represent a novel therapeutic tool in the treatment of human MFH.
2. Body size, energy metabolism and lifespan
Body size, energy metabolism and lifespan – Reference
J Exp Biol. 2005 May;208(Pt 9):1717-30.
Bigger animals live longer. The scaling exponent for the relationship between lifespan and body mass is between 0.15 and 0.3. Bigger animals also expend more energy, and the scaling exponent for the relationship of resting metabolic rate (RMR) to body mass lies somewhere between 0.66 and 0.8. Mass-specific RMR therefore scales with a corresponding exponent between -0.2 and -0.33. Because the exponents for mass-specific RMR are close to the exponents for lifespan, but have opposite signs, their product (the mass-specific expenditure of energy per lifespan) is independent of body mass (exponent between -0.08 and 0.08). This means that across species a gram of tissue on average expends about the same amount of energy before it dies regardless of whether that tissue is located in a shrew, a cow, an elephant or a whale. This fact led to the notion that ageing and lifespan are processes regulated by energy metabolism rates and that elevating metabolism will be associated with premature mortality–the rate of living theory. The free-radical theory of ageing provides a potential mechanism that links metabolism to ageing phenomena, since oxygen free radicals are formed as a by-product of oxidative phosphorylation.
Despite this potential synergy in these theoretical approaches, the free-radical theory has grown in stature while the rate of living theory has fallen into disrepute. This is primarily because comparisons made across classes (for example, between birds and mammals) do not conform to the expectations, and even within classes there is substantial interspecific variability in the mass-specific expenditure of energy per lifespan. Using interspecific data to test the rate of living hypothesis is, however, confused by several major problems. For example, appeals that the resultant lifetime expenditure of energy per gram of tissue is ‘too variable’ depend on the biological significance rather than the statistical significance of the variation observed. Moreover, maximum lifespan is not a good marker of ageing and RMR is not a good measure of total energy metabolism. Analysis of residual lifespan against residual RMR reveals no significant relationship. However, this is still based on RMR. A novel comparison using daily energy expenditure (DEE), rather than BMR, suggests that lifetime expenditure of energy per gram of tissue is NOT independent of body mass, and that tissue in smaller animals expends more energy before expiring than tissue in larger animals.
Some of the residual variation in this relationship in mammals is explained by ambient temperature. In addition there is a significant negative relationship between residual lifespan and residual daily energy expenditure in mammals. A potentially much better model to explore the links of body size, metabolism and ageing is to examine the intraspecific links. These studies have generated some data that support the original rate of living theory and other data that conflict. In particular several studies have shown that manipulating animals to expend more or less energy generate the expected effects on lifespan (particularly when the subjects are ectotherms). However, smaller individuals with higher rates of metabolism live longer than their slower, larger conspecifics. An addition to these confused observations has been the recent suggestion that under some circumstances we might expect mitochondria to produce fewer free radicals when metabolism is higher–particularly when they are uncoupled. These new ideas concerning the manner in which mitochondria generate free radicals as a function of metabolism shed some light on the complexity of observations linking body size, metabolism and lifespan.
3. Explaining longevity of different animals: is membrane fatty acid composition the missing link?
Explaining longevity of different animals: is membrane fatty acid composition the missing link? – Reference, Full text
Age (Dordr). 2008 Sep; 30(2-3): 89–97.
A. J. Hulbert
Saturated and monounsaturated fatty acids are very resistant to peroxidative damage, while the more polyunsaturated a fatty acid, the more susceptible it is to peroxidation. Furthermore, the products of lipid peroxidation can oxidatively damage other important molecules. Membrane fatty acid composition is correlated with the maximum lifespans of mammals and birds. Exceptionally long-living mammal species and birds have a more peroxidation-resistant membrane composition compared to shorter-living similar-sized mammals. Within species, there are also situations in which extended longevity is associated with peroxidation-resistant membrane composition. For example, caloric restriction is associated more peroxidation-resistant membrane composition; long-living queens have more peroxidation-resistant membranes than shorter-living worker honeybees. In humans, the offspring of nonagenarians have peroxidation-resistant erythrocyte membrane composition compared to controls. Membrane fatty acid composition is a little appreciated but important correlate of the rate of aging of animals and the determination of their longevity.
4. The importance of the ratio of omega-6/omega-3 essential fatty acids
The importance of the ratio of omega-6/omega-3 essential fatty acids – Reference
Biomed Pharmacother. 2002 Oct;56(8):365-79
Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in Western diets the ratio is 15/1-16.7/1. Western diets are deficient in omega-3 fatty acids, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved and their genetic patterns were established. Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today’s Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) exert suppressive effects.
In the secondary prevention of cardiovascular disease, a ratio of 4/1 was associated with a 70% decrease in total mortality. A ratio of 2.5/1 reduced rectal cell proliferation in patients with colorectal cancer, whereas a ratio of 4/1 with the same amount of omega-3 PUFA had no effect. The lower omega-6/omega-3 ratio in women with breast cancer was associated with decreased risk. A ratio of 2-3/1 suppressed inflammation in patients with rheumatoid arthritis, and a ratio of 5/1 had a beneficial effect on patients with asthma, whereas a ratio of 10/1 had adverse consequences. These studies indicate that the optimal ratio may vary with the disease under consideration. This is consistent with the fact that chronic diseases are multigenic and multifactorial. Therefore, it is quite possible that the therapeutic dose of omega-3 fatty acids will depend on the degree of severity of disease resulting from the genetic predisposition. A lower ratio of omega-6/omega-3 fatty acids is more desirable in reducing the risk of many of the chronic diseases of high prevalence in Western societies, as well as in the developing countries, that are being exported to the rest of the world.
5. Oxidative stress and lipid peroxidation products in cancer progression and therapy
Oxidative stress and lipid peroxidation products in cancer progression and therapy – Reference, Full text
ISRN Oncol. 2012;2012:137289. doi: 10.5402/2012/137289. Epub 2012 Oct 17
The generation of reactive oxygen species (ROS) and an altered redox status are common biochemical aspects in cancer cells. ROS can react with the polyunsaturated fatty acids of lipid membranes and induce lipid peroxidation. The end products of lipid peroxidation, 4-hydroxynonenal (HNE), have been considered to be a second messenger of oxidative stress. Beyond ROS involvement in carcinogenesis, increased ROS level can inhibit tumor cell growth. Indeed, in tumors in advanced stages, a further increase of oxidative stress, such as that occurs when using several anticancer drugs and radiation therapy, can overcome the antioxidant defenses of cancer cells and drive them to apoptosis. High concentrations of HNE can also induce apoptosis in cancer cells. However, some cells escape the apoptosis induced by chemical or radiation therapy through the adaptation to intrinsic oxidative stress which confers drug resistance. This paper is focused on recent advances in the studies of the relation between oxidative stress, lipid peroxidation products, and cancer progression with particular attention to the pro-oxidant anticancer agents and the drug-resistant mechanisms, which could be modulated to obtain a better response to cancer therapy.
6. Comparative respiratory physiology: the fundamental mechanisms and the functional designs of the gas exchangers
Comparative respiratory physiology: the fundamental mechanisms and the functional designs of the gas exchangers – Full text
Dove Press, 10 December 2014 Volume 2014:6 Pages 53—66
Acquisition of molecular oxygen (O2) from the external fluid media (water and air) and the discharge of carbon dioxide (CO2) into the same milieu is the primary role of respiration. The functional designs of gas exchangers have been considerably determined by the laws of physics which govern the properties and the flux of gases and the physicochemical properties of the respiratory fluid media (water or air and blood). Although the morphologies of gas exchangers differ greatly, certain shared structural and functional features exist. For example, in all cases, the transfer of O2 and CO2 across the water/air–blood (tissue) barriers occurs entirely by passive diffusion along concentration gradients.
In the multicellular organisms, gas exchangers have developed either by evagination or invagination. The arrangement, shape, and geometries of the airways and the blood vessels determine the transport and exposure of the respiratory media and, consequently, gas exchange. The thickness of the water/air–blood (tissue) barrier, the respiratory surface area, and volume of pulmonary capillary blood are the foremost structural parameters which determine the diffusing capacity of a gas exchanger for O2. In fish, stratified design of the gills and internal subdivision of the lungs increase the respiratory surface area: the same adaptive property is realized by different means. A surface active phospholipid substance (surfactant) lines the respiratory surface. Adaptive specializations of gas exchangers have developed to meet individual survival needs.
The queen honey bee is genetically identical to the workers in her hive, but she lives 10 times longer and – unlike her sterile sisters – remains reproductively viable throughout life. A study from the University of Illinois sheds new light on the molecular mechanisms that account for this divergence.
8. Extended longevity of queen honey bees compared to workers is associated with peroxidation-resistant membranes
Extended longevity of queen honey bees compared to workers is associated with peroxidation-resistant membranes – Reference
Exp Gerontol. 2007 Jul;42(7):601-9. Epub 2007 Mar 3
Haddad LS, Kelbert L, Hulbert AJ
In the honey bee (Apis mellifera), depending on what they are fed, female eggs become either workers or queens. Although queens and workers share a common genome, the maximum lifespan of queens is an order-of-magnitude longer than workers. The mechanistic basis of this longevity difference is unknown. In order to test if differences in membrane composition could be involved we have compared the fatty acid composition of phospholipids of queen and worker honey bees. The cell membranes of both young and old honey bee queens are highly monounsaturated with very low content of polyunsaturates. Newly emerged workers have a similar membrane fatty acid composition to queens but within the first week of hive life, they increase the polyunsaturate content and decrease the monounsaturate content of their membranes, probably as a result of pollen consumption. This means their membranes likely become more susceptible to lipid peroxidation in this first week of hive life.
The results support the suggestion that membrane composition might be an important factor in the determination of maximum lifespan. Assuming the same slope of the relationship between membrane peroxidation index and maximum lifespan as previously observed for mammal and bird species, we propose that the 3-fold difference in peroxidation index of phospholipids of queens and workers is large enough to account for the order-of-magnitude difference in their longevity.
9. An Efficient Antioxidant System in a Long-Lived Termite Queen
PLoS One. 2017 Jan 11;12(1):e0167412. doi: 10.1371/journal.pone.0167412. eCollection 2017
Tasaki E, Kobayashi K, Matsuura K, Iuchi Y
The trade-off between reproduction and longevity is known in wide variety of animals. Social insect queens are rare organisms that can achieve a long lifespan without sacrificing fecundity. The extended longevity of social insect queens, which contradicts the trade-off, has attracted much attention because it implies the existence of an extraordinary anti-aging mechanism. Here, we show that queens of the termite Reticulitermes speratus incur significantly lower oxidative damage to DNA, protein and lipid and have higher activity of antioxidant enzymes than non-reproductive individuals (workers and soldiers).
The levels of 8-hydroxy-2′-deoxyguanosine (oxidative damage marker of DNA) were lower in queens than in workers after UV irradiation. Queens also showed lower levels of protein carbonyls and malondialdehyde (oxidative damage markers of protein and lipid, respectively). The antioxidant enzymes of insects are generally composed of catalase (CAT) and peroxiredoxin (Prx). Queens showed more than two times higher CAT activity and more than seven times higher expression levels of the CAT gene RsCAT1 than workers. The CAT activity of termite queens was also markedly higher in comparison with other solitary insects and the queens of eusocial Hymenoptera. In addition, queens showed higher expression levels of the Prx gene RsPRX6. These results suggested that this efficient antioxidant system can partly explain why termite queens achieve long life. This study provides important insights into the evolutionary linkage of reproductive division of labor and the development of queens’ oxidative stress resistance in social insects.
10. Sociobiology and Natural Adaptation of Termite and Termitomyces in Different Forest Division of Gorakhpur Region
Sociobiology and Natural Adaptation of Termite and Termitomyces in Different Forest Division of Gorakhpur Region – Full text (pdf)
Bull. Env. Pharmacol. Life Sci. Volume 2 December 2012: 32- 36
Bobby Srivastava, A.K.Dwivedi and V.N.Pandey
Termite commonly known as termatorium. Different forest ranges of Gorakhpur and Maharajganj district were explored in the rainy season for environmental adaptation of Termite and Termitomyces species and collect data of seasonal variability in relation to temperature, heat, relative humidity, carbon dioxide and oxygen concentration in and around the termatorium. The results indicated that the Termite are most sensitive to their environment especially temperature, heat, humidity and CO2 concentration. Termitomyces is very sensitive fungus growing in rainy season on the brain like comb of Termite insect. When heavy rainfalls occur with thundering in atmosphere, the humidity increase and other environmental factors are favourable for growth, development and differentiation of fungal mycelium within the termatorium and resulted in the production of biofunctional fruiting body of Termitomyces.
11. Why exceptionally fertile termite queens have long lives
Why exceptionally fertile termite queens have long lives – Full text
Phys.org May 8, 2018
Albert Ludwigs, University of Freiburg
Usually the rule in the animal kingdom is that a lot of progeny means a short life – if you are less fertile, you live longer. However, it seems that social insects can escape this fate. How they do this has been revealed by a research team from the Institute of Zoology at the University of Freiburg, taking the termite species Macrotermes bellicosus as its model.
“Macrotermes queens are the most reproductively successful terrestrial animals,” says Freiburg biologist Prof. Dr. Judith Korb. Termite queens lay continuously about 20,000 eggs daily. And yet they reach ages of up to 20 years. Workers from this species have the same genome as the queen, but are infertile and only live for a few months. Judith Korb, together with her Ph.D. student Daniel Elsner and Dr. Karen Meusemann, has found a clue to why the queen and king – unlike the workers – practically do not age. The team has published its results in the scientific journal Proceedings of the National Academy of Sciences (PNAS).
12. The architecture of termite mounds: a result of a trade-off between thermoregulation and gas exchange?
The architecture of termite mounds: a result of a trade-off between thermoregulation and gas exchange? – Full text
Behavioral Ecology, Volume 10, Issue 3, May 1999, Pages 312–316
Judith Korb, Karl Eduard Linsenmair
We examined the influence of gas exchange on the architecture of termite mounds. In Comoé National Park (Côte d’Ivoire), Macrotermes bellicosus builds, as an adaptation to ambient temperature conditions, differently shaped mounds in the shrub savanna and the gallery forest. Previous studies suggested that there might be a constraint that limits the degree of thermal insulation of the interior (i.e., nest) of the mounds in environments with relatively low ambient temperatures. This factor causes, in proximate terms, suboptimal low nest temperatures and ultimately leads to reduced reproductive success in the gallery forest. In this study, we examined whether the necessity for gas exchange might constrain mound architecture. We measured CO2 concentrations in the air channels of mounds in different habitats and under manipulated temperature regimes.
During both the dry and the rainy season we found higher CO2 concentrations in mounds of the gallery forest than in mounds of the savanna. Additional measurements in forest mounds, architecturally resembling those of the savanna due to an experimental increase in ambient temperatures, revealed lower CO2 concentrations than unmanipulated mounds in this habitat. Generally, concentrations were higher during the rainy season compared to the dry season and lower during day than during night. Summarizing these results we present a model that illustrates this trade-off between thermoregulation and gas exchange under different temperature regimes. Both factors together result in different mound architectures under different environmental temperatures and may finally limit the distribution of this species.
13. Longevity of harvester ant colonies in southern Idaho
Harvester ant colonies (Pogonomyrmex owyheel Cole) in southern Idaho were monitored periodically for 9 years. Mortality rates indicate that established colonies live 14-30 years. Mounds were commonly reactivated after the death of an old colony; consequently, some may be utilized for many decades. Clearings with active mounds showed almost no change after 9 years of observations while those without active mounds were rapidly filled by annual herbs and then gradually by perennial shrubs. Harvester ants are clearly 8 very persistent component of cold desert shrub communities.
14. Carbon dioxide concentrations and nest ventilation in nests of the leaf-cutting ant Atta vollenweideri
Carbon dioxide concentrations and nest ventilation in nests of the leaf-cutting ant Atta vollenweideri – Reference, Full text (pdf)
Insectes Sociaux, August 2000, Volume 47, Issue 3, pp 241–248
C. KleineidamF. Roces
Microclimatic conditions in the giant nests of the leaf-cutting ant Atta vollenweideri were experimentally examined to address the question whether increasing concentrations of the respiratory gases affect colony respiration. Measurements of CO2 concentrations of less than 2.8% at different depths inside mature field nests indicated good ventilation, even at 2 m depth. Passive ventilation was driven by wind and promoted by the shape of the nest. It did not influence nest temperature nor relative humidity. During rain and flooding, small colonies closed all nest openings to protect the nest from excessive water influx and damage.
Measurements in a small nest indicated that, as a consequence of closure, the Co2 concentration increased rapidly. This situation was simulated in the laboratory, using a small colony of Atta sexdens as a model system. Colony respiration rates were shown to be reduced as a function of increasing CO2 concentration. Based on literature data on ant respiration, it is suggested that the respiration of the symbiotic fungus was reduced, and not that of the ants. Since the brood of leaf-cutting ants feeds exclusively on the fungus, reduced nest ventilation and its effects on respiration rates may compromise colony growth. While mature nests provide the colony with good microclimate under all weather conditions during summer, developing colonies are confronted with a tradeoff between minimizing the risk of inundation and assuring adequate gas exchange inside their nests.
15. Weird: Naked Mole Rats Don’t Die of Old Age
Weird: Naked Mole Rats Don’t Die of Old Age – Reference
Live Science, January 30, 2018
y Stephanie Pappas
Just when it seemed the naked mole rat couldn’t get any weirder, it turns out the buck-toothed, bare-skinned rodents don’t even age. Unlike literally every other mammal, naked mole rats don’t become more likely to die as they get up there in years. In humans, for example, with all else being equal besides age, a person’s risk of dying doubles every 8 years after age 40. For naked mole rats (Heterocephalus glaber), there is no increase in the risk of death even when the rats are 25 times older than the onset of sexual maturity. “It doesn’t matter how old you are,” said Rochelle Buffenstein, a senior principal investigator at Calico Life Sciences LLC, a research company in San Francisco. “Your death is random.”
16. The Naked Mole-Rat Response to Oxidative Stress: Just Deal with It
Antioxid Redox Signal. 2013 Oct 20;19(12):1388-99. doi: 10.1089/ars.2012.4911. Epub 2012 Dec 7
Lewis KN, Andziak B, Yang T, Buffenstein R.
SIGNIFICANCE: The oxidative stress theory of aging has been the most widely accepted theory of aging providing insights into why we age and die for over 50 years, despite mounting evidence from a multitude of species indicating that there is no direct relationship between reactive oxygen species (ROS) and longevity. Here we explore how different species, including the longest lived rodent, the naked mole-rat, have defied the most predominant aging theory.RECENT ADVANCES: In the case of extremely long-lived naked mole-rat, levels of ROS production are found to be similar to mice, antioxidant defenses unexceptional, and even under constitutive conditions, naked mole-rats combine a pro-oxidant intracellular milieu with high, steady state levels of oxidative damage. Clearly, naked mole-rats can tolerate this level of oxidative stress and must have mechanisms in place to prevent its translation into potentially lethal diseases.
CRITICAL ISSUES: In addition to the naked mole-rat, other species from across the phylogenetic spectrum and even certain mouse strains do not support this theory. Moreover, overexpressing or knocking down antioxidant levels alters levels of oxidative damage and even cancer incidence, but does not modulate lifespan.
FUTURE DIRECTIONS: Perhaps, it is not oxidative stress that modulates healthspan and longevity, but other cytoprotective mechanisms that allow animals to deal with high levels of oxidative damage and stress, and nevertheless live long, relatively healthy lifespans. Studying these mechanisms in uniquely long-lived species, like the naked mole-rat, may help us tease out the key contributors to aging and longevity.
Bat biologists have long known about the exceptional longevity of bats (Order: Chiroptera), which is unusual for mammals of such a small size and a high metabolic rate. Yet relatively few mechanistic studies have focused on this longevity. On average, species of Chiroptera live three times longer than predicted by their body size. In addition, bats have other life history traits that are characteristic of large, long-lived mammals such as few and large offspring and slow growth rates. Bats fit the evolutionary theory of ageing, as their extended longevity is predicted by their ability to escape extrinsic mortality through flight and, in some species, hibernation. They also show tradeoffs between longevity and reproduction, as predicted by the disposable soma theory of ageing. From a physiological perspective, bat longevity reportedly correlates with replicative longevity, low brain calpain activity, and reduced reactive oxygen species production. As long-lived and physiologically interesting organisms, bats may prove to be an informative model system for ageing research.
18. Ammonia Tolerance of the California Leaf-Nosed Bat
Ammonia Tolerance of the California Leaf-Nosed Bat – Reference
Journal of Mammalogy, Volume 44, Issue 4, 13 December 1963, Pages 543–551
Henry A. Mitchell
A series of 59 California leaf-nosed bats, Macrotus californicus, was exposed to varying concentrations of anhydrous ammonia. Physiologic responses noted in the bat were compared to the same responses as recorded in the literature for man and other experimental animals. Recordings were made for the following: cardiac and respiratory rates, blood non-protein nitrogen, urine urea and ammonia and animal and gassing chamber temperatures. An elevation of non-protein nitrogen over the mean normal was evident but no significant elevation of urine urea and ammonia was noted. Resistance to the gas was demonstrated by decreases in respiratory and cardiac rates. Toxic manifestations attributable to ammonia were noted in distinct visceral damage, corrosion of the skin and mucous membranes and pulmonary edema. Maximum sublethal concentration tolerated for an exposure time of 9 hours was 3,000 ppm.
19. Carbon Dioxide Retention: A Mechanism of Ammonia Tolerance in Mammals
Carbon Dioxide Retention: A Mechanism of Ammonia Tolerance in Mammals – Reference
Ecology Society of America, Volume50, Issue3, May 1969, Pages 492-494
Eugene M. Studier, A. A. Fresquez
When guano bats, Tadarida brasiliensis, inhale ammonia in air mixtures, carbon dioxide is passively retained in sufficient amounts to neutralize alkali excess resulting from increased blood ammonia levels. There is no change in blood carbon dioxide levels in house mice, Mus musculus. Little brown bats, Myotis lucifugus, are intermediate in this respect. Passive carbon dioxide retention is clearly related to ammonia tolerance in these mammals.
20. Elevated Carbon Dioxide Levels in Bayliss Cave, Australia: Implications for the Evolution of Obligate Cave Species!
Elevated Carbon Dioxide Levels in Bayliss Cave, Australia: Implications for the Evolution of Obligate Cave Species! – Full text (pdf)
Pacific Science (1990), vol. 44, no. 3: 207-218
Francis G. Howarth, Fred D. Stone
In May and June 1985, the deeper passages of Bayliss Cave, North Queensland, Australia, contained up to 200 times the ambient atmospheric level of carbon dioxide and a water-saturated atmosphere, yet supported the most diverse community of highly modified, obligate, terrestrial cave species yet known. The obligate and facultative cave species were mostly segregated by the environment, with the 24 obligate cave-adapted species being largely restricted to the “bad-air” zone. The discovery of this previously unknown “bad-air,” obligate cave community corroborates other behavioral and distributional studies that suggest that cave-adapted animals are specialized to exploit resources within the smaller underground ‘voids, where fluctuating carbon dioxide concentrations are theoretically intolerable to most surface and facultative cave species.
21. Control of breathing in the echidna (Tachyglossus aculeatus) during hibernation
Control of breathing in the echidna (Tachyglossus aculeatus) during hibernation – Reference
Comp Biochem Physiol A Mol Integr Physiol. 2003 Dec;136(4):917-25
Nicol S, Andersen NA
Resting non-hibernating echidnas are characterised by low metabolic rates, but also have a very low respiratory frequency and a variable respiratory minute volume, often resulting in low levels of arterial O(2) and high CO(2). As the echidna lies at one physiological extreme among the hibernators, in terms of its large size and low metabolism and ventilatory requirement when not hibernating, a study of control of breathing during hibernation in echidnas should provide a useful test of the generality of various models. We used non-invasive techniques to study breathing patterns and the control of ventilation in 6 echidnas. Hibernating echidnas (T(b) range 7-10 degrees C) showed episodic breathing with bursts of breaths (average 36+/-16 breaths in 24+/-5 min) followed by a period of apnea (76+/-17 min) then a series (8+/-4) of slow breaths at 14+/-1 min intervals leading up to the next burst. Increasing CO(2) levels in the inspired air increased the number of breaths in a burst, eventually leading to continuous breathing. Inter burst breaths were controlled by O(2): hypoxia increased inter burst breaths, and decreased burst length, while hyperoxia abolished inter burst breaths and increased the apneic period. Overall, while CO(2) was a strong respiratory stimulus in hibernating echidnas, O(2) had little effect on total ventilation, but did have a strong effect on the breathing pattern.
22. Respiration by buried echidnas Tachyglossus aculeatus
Short-beaked echidnas have an impressive ability to submerge completely into soil or sand and remain there, cryptic, for long periods. This poses questions about how they manage their respiration, cut off from a free flow of gases. We measured the gradient in oxygen partial pressure (PO2) away from the snouts of buried echidnas and oxygen consumption (VO2) in five individuals under similar conditions, in two substrates with different air-filled porosities (fa). A theoretical diffusion model indicated that diffusion alone was insufficient to account for the flux of oxygen required to meet measured rates of VO2. However, it was noticed that echidnas often showed periodic movements of the anterior part of the body, as if such movements were a deliberate effort to flush the tidal air space surrounding their nostrils. These ;flushing movements’ were subsequently found to temporarily increase the levels of interstitial oxygen in the soil around the head region. Flushing movements were more frequent while VO2 was higher during the burrowing process, and also in substrate with lower fa. We conclude that oxygen supply to buried echidnas is maintained by diffusion through the soil augmented by periodic flushing movements, which ventilate the tidal airspace that surrounds the nostrils.
23. The exceptional longevity of an egg-laying mammal, the short-beaked echidna (Tachyglossus aculeatus) is associated with peroxidation-resistant membrane composition
The exceptional longevity of an egg-laying mammal, the short-beaked echidna (Tachyglossus aculeatus) is associated with peroxidation-resistant membrane composition – Reference
Exp Gerontol. 2008 Aug;43(8):729-33. doi: 10.1016/j.exger.2008.05.015. Epub 2008 Jun 11
Hulbert AJ, Beard LA, Grigg GC
The echidna Tachyglossus aculeatus is a monotreme mammal from Australia that is exceptionally long-living. Its documented maximum lifespan of 50 years is 3.7 times that predicted from its body mass. Other exceptionally long-living mammals (naked mole-rats and humans) are known to have peroxidation-resistant membrane composition, raising the question about echidnas. Phospholipids were extracted from skeletal muscle, liver and liver mitochondria of echidnas and fatty acid composition measured. As with other exceptionally long-living mammals, membrane lipids of echidna tissues were found to have a lower content of polyunsaturates and a higher content of monounsaturates than predicted for their body size. The peroxidation index (=peroxidation susceptibility) calculated from this membrane composition was lower-than-expected for their body size, indicating that the cellular membranes of echidnas would be peroxidation-resistant. Additionally when the calculated peroxidation index was plotted against maximum lifespan, the echidna values conformed to the relationship for mammals in general. These findings support the membrane pacemaker theory of aging and emphasise the potential importance of membrane fatty acid composition in aging and in the determination of maximum longevity.
24. Insights into the Evolution of Longevity from the Bowhead Whale Genome
Insights into the Evolution of Longevity from the Bowhead Whale Genome – Reference, Full text
Cell Rep. 2015 Jan 6;10(1):112-22. doi: 10.1016/j.celrep.2014.12.008
Keane M, de Magalhães JP et al.
The bowhead whale (Balaena mysticetus) is estimated to live over 200 years and is possibly the longest-living mammal. These animals should possess protective molecular adaptations relevant to age-related diseases, particularly cancer. Here, we report the sequencing and comparative analysis of the bowhead whale genome and two transcriptomes from different populations. Our analysis identifies genes under positive selection and bowhead-specific mutations in genes linked to cancer and aging. In addition, we identify gene gain and loss involving genes associated with DNA repair, cell-cycle regulation, cancer, and aging. Our results expand our understanding of the evolution of mammalian longevity and suggest possible players involved in adaptive genetic changes conferring cancer resistance. We also found potentially relevant changes in genes related to additional processes, including thermoregulation, sensory perception, dietary adaptations, and immune response. Our data are made available online (http://www.bowhead-whale.org) to facilitate research in this long-lived species.
25. Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus)
Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus) – Reference
Science. 2016 Aug 12;353(6300):702-4. doi: 10.1126/science.aaf1703. Epub 2016 Aug 11
The Greenland shark (Somniosus microcephalus), an iconic species of the Arctic Seas, grows slowly and reaches >500 centimeters (cm) in total length, suggesting a life span well beyond those of other vertebrates. Radiocarbon dating of eye lens nuclei from 28 female Greenland sharks (81 to 502 cm in total length) revealed a life span of at least 272 years. Only the smallest sharks (220 cm or less) showed signs of the radiocarbon bomb pulse, a time marker of the early 1960s. The age ranges of prebomb sharks (reported as midpoint and extent of the 95.4% probability range) revealed the age at sexual maturity to be at least 156 ± 22 years, and the largest animal (502 cm) to be 392 ± 120 years old. Our results show that the Greenland shark is the longest-lived vertebrate known, and they raise concerns about species conservation.
26. Longest-lived vertebrate is Greenland shark: Lifespan of 400 years
Longest-lived vertebrate is Greenland shark: Lifespan of 400 years – Reference
ScienceDaily, August 11, 2016
American Association for the Advancement of Science
Greenland sharks live at least as long as 400 years, and they reach sexual maturity at the age of about 150, a new study reports. The results place Greenland sharks as the longest-lived vertebrates on Earth. The Greenland shark (Somniosus microcephalus) is widely distributed across the North Atlantic, with adults reaching lengths of 400 to 500 centimeters (13 to 16 feet). The biology of the Greenland shark is poorly understood, yet their extremely slow growth rates, at about 1 cm per year, hint that these fish benefit from exceptional longevity.
27. The extreme longevity of Arctica islandica is associated with increased peroxidation resistance in mitochondrial membranes
The extreme longevity of Arctica islandica is associated with increased peroxidation resistance in mitochondrial membranes – Reference, Full text
The deleterious reactive carbonyls released upon oxidation of polyunsaturated fatty acids in biological membranes are believed to foster cellular aging. Comparative studies in mammals and birds have shown that the susceptibility to peroxidation of membrane lipids peroxidation index (PI) is negatively correlated with longevity. Long-living marine molluscs are increasingly studied as longevity models, and the presence of different types of lipids in the membranes of these organisms raises questions on the existence of a PI-longevity relationship. We address this question by comparing the longest living metazoan species, the mud clam Arctica islandica (maximum reported longevity = 507 year) to four other sympatric bivalve molluscs greatly differing in longevity (28, 37, 92, and 106 year). We contrasted the acyl and alkenyl chain composition of phospholipids from the mitochondrial membranes of these species.
The analysis was reproduced in parallel for a mix of other cell membranes to investigate whether a different PI-longevity relationship would be found. The mitochondrial membrane PI was found to have an exponential decrease with increasing longevity among species and is significantly lower for A. islandica. The PI of other cell membranes showed a linear decrease with increasing longevity among species and was also significantly lower for A. islandica. These results clearly demonstrate that the PI also decreases with increasing longevity in marine bivalves and that it decreases faster in the mitochondrial membrane than in other membranes in general. Furthermore, the particularly low PI values for A. islandica can partly explain this species’ extreme longevity.
28. Extreme Longevity Is Associated With Increased Resistance to Oxidative Stress in Arctica islandica, the Longest-Living Non-Colonial Animal
Extreme Longevity Is Associated With Increased Resistance to Oxidative Stress in Arctica islandica, the Longest-Living Non-Colonial Animal – Reference, Full text
J Gerontol A Biol Sci Med Sci. 2011 Jul;66(7):741-50. doi: 10.1093/gerona/glr044. Epub 2011 Apr 12
Ungvari Z, Csiszar A et al.
We assess whether reactive oxygen species production and resistance to oxidative stress might be causally involved in the exceptional longevity exhibited by the ocean quahog Arctica islandica. We tested this hypothesis by comparing reactive oxygen species production, resistance to oxidative stress, antioxidant defenses, and protein damage elimination processes in long-lived A islandica with the shorter-lived hard clam, Mercenaria mercenaria. We compared baseline biochemical profiles, age-related changes, and responses to exposure to the oxidative stressor tert-butyl hydroperoxide (TBHP). Our data support the premise that extreme longevity in A islandica is associated with an attenuated cellular reactive oxygen species production.
The observation of reduced protein carbonyl concentration in A islandica gill tissue compared with M mercenaria suggests that reduced reactive oxygen species production in long-living bivalves is associated with lower levels of accumulated macromolecular damage, suggesting cellular redox homeostasis may determine life span. Resistance to aging at the organismal level is often reflected in resistance to oxidative stressors at the cellular level. Following TBHP exposure, we observed not only an association between longevity and resistance to oxidative stress-induced mortality but also marked resistance to oxidative stress-induced cell death in the longer-living bivalves. Contrary to some expectations from the oxidative stress hypothesis, we observed that A islandica exhibited neither greater antioxidant capacities nor specific activities than in M mercenaria nor a more pronounced homeostatic antioxidant response following TBHP exposure.
The study also failed to provide support for the exceptional longevity of A islandica being associated with enhanced protein recycling. Our findings demonstrate an association between longevity and resistance to oxidative stress-induced cell death in A islandica, consistent with the oxidative stress hypothesis of aging and provide justification for detailed evaluation of pathways involving repair of free radical-mediated macromolecular damage and regulation of apoptosis in the world’s longest-living non-colonial animal.
29. A metabolic model for the Ocean Quahog Arctica islandica — Effects of animal mass and age, temperature, salinity and geography on respiration rate
A metabolic model for the Ocean Quahog Arctica islandica — Effects of animal mass and age, temperature, salinity and geography on respiration rate – Full text (pdf)
Journal of Shellfish Research, Vol. 28, No. 3, 533–539, 2009
S. Begum, D. Abele et al.
Owing to its extraordinary lifespan and wide geographical distribution along the continental margins of the North Atlantic Ocean, the ocean quahog Arctica islandica may become an important indicator species in environmental change research. To test for applicability and ‘‘calibrate’’ the Arctica-indicator, metabolic properties of A. islandica specimens were compared across different climatic and oceanographic regions. Fully saline populations from Iceland to the North Sea as well as animals from polyhaline and low salinity, environments, the White Sea and the Baltic were included in the study.
This calibration centrally includes recordings of growth-age relationships in different populations. Shells were used as age recorders by counting annual growth bands. As a result of this study, we propose a general respiration model that links individual metabolic rates of A. islandica from five populations: Norwegian coast, Kattegat, Kiel Bay (Baltic Sea), White Sea and German Bight (North Sea), to body mass, water temperature and site. Temperature exerts distinct site specific effects on respiration rate, which is indicated by Q10 values ranging from 4.48 for German Bight to 1.15 for Kiel Bay animals. Individual age, occurrence of apneal respiratory gaps, parasite infestation and salinity do not affect respiration rate. Respiration of Arctica islandica is significantly below the average of 59 bivalve species when compared at the same temperature and animal mass. This respiration model principally enables the coupling of A. islandica life history and population dynamics to regional oceanographic temperature models.
30. Metabolic and physiological responses in tissues of the long-lived bivalve Arctica islandica to oxygen deficiency
Metabolic and physiological responses in tissues of the long-lived bivalve Arctica islandica to oxygen deficiency – Reference
Comp Biochem Physiol A Mol Integr Physiol. 2011 Apr;158(4):513-9. doi: 10.1016/j.cbpa.2010.12.015. Epub 2010 Dec 22
Strahl J, Dringen R, Schmidt MM, Hardenberg S, Abele D.
In Arctica islandica, a long lifespan is associated with low metabolic activity, and with a pronounced tolerance to low environmental oxygen. In order to study metabolic and physiological responses to low oxygen conditions vs. no oxygen in mantle, gill, adductor muscle and hemocytes of the ocean quahog, specimens from the German Bight were maintained for 3.5 days under normoxia (21 kPa=controls), hypoxia (2 kPa) or anoxia (0 kPa). Tissue levels of anaerobic metabolites octopine, lactate and succinate as well as specific activities of octopine dehydrogenase (ODH) and lactate dehydrogenase (LDH) were unaffected by hypoxic incubation, suggesting that the metabolism of A. islandica remains fully aerobic down to environmental oxygen levels of 2 kPa. PO(2)-dependent respiration rates of isolated gills indicated the onset of metabolic rate depression (MRD) below 5 kPa in A. islandica, while anaerobiosis was switched on in bivalve tissues only at anoxia.
Tissue-specific levels of glutathione (GSH), a scavenger of reactive oxygen species (ROS), indicate no anticipatory antioxidant response takes place under experimental hypoxia and anoxia exposure. Highest specific ODH activity and a mean ODH/LDH ratio of 95 in the adductor muscle contrasted with maximal specific LDH activity and a mean ODH/LDH ratio of 0.3 in hemocytes. These differences in anaerobic enzyme activity patterns indicate that LDH and ODH play specific roles in different tissues of A. islandica which are likely to economize metabolism during anoxia and reoxygenation.
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Anders Olsson is a lecturer, teacher and founder of the Conscious Breathing concept and the author of Conscious Breathing. After living most of his life with a ”hurricane of thoughts” bouncing back and forth in is head, Anders was fortunate enough to come across tools that have helped him relax and find his inner calm. The most powerful of these tools has undoubtedly been to improve his breathing habits, which made Anders decide to become the worlds most prominent expert in breathing. This is now more than 10 years ago and since then he has helped tens of thousands of people to a better health and improved quality of life.