Reviewing Membrane Composition and Species Longevity
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Mitochondria are important in aging, and in particular their relationship to aging appears to be somewhat mediated by how resistant their membranes are to oxidative damage - the evidence and theorizing around this is known as the membrane pacemaker hypothesis. You'll recall that mitochondria are effectively the cell's power plants, generating chemical energy stores for use in many cellular processes. In the course of their operation they generate a continued flow of reactive free radicals that can cause oxidative damage - they themselves are the most likely target for that damage, but because they occupy such an important position in the cell there are ways in which their damage can lead to worse outcomes for the cell as a whole, and also for surrounding tissue. This process is one of the causes of aging, and it is why the development of mitochondrial repair technologies is important.

Here is an open access paper that reviews what is known about the link between membrane composition and longevity in various species. In general I view this as supporting evidence for the need for mitochondrial repair: I don't expect that anything of practical use in the near term can result from trying to change the composition of our mitochondrial membranes.

The appearance of oxygen in the terrestrial atmosphere represented an important selective pressure for ancestral living organisms and contributed toward setting up the pace of evolutionary changes in structural and functional systems. The evolution of using oxygen for efficient energy production served as a driving force for the evolution of complex organisms. The redox reactions associated with its use were, however, responsible for the production of reactive species (derived from oxygen and lipids) with damaging effects due to oxidative chemical modifications of essential cellular components.

Consequently, aerobic life required the emergence and selection of antioxidant defense systems. As a result, a high diversity in molecular and structural antioxidant defenses evolved. In the following paragraphs, we analyze the adaptation of biological membranes as a dynamic structural defense against reactive species evolved by animals. In particular, our goal is to describe the physiological mechanisms underlying the structural adaptation of cellular membranes to oxidative stress and to explain the meaning of this adaptive mechanism, and to review the state of the art about the link between membrane composition and longevity of animal species.

Link: http://www.frontiersin.org/Journal/10.3389/fphys.2013.00372/full

Comments

If damage generation is dropped low enough existing quality control maintenance mechanisms may be able to preserve homeostatic balance indefinitely, imho.

For example, primate lifespan is said to differ by about an order of magnitude depending on species. Bonobos are said to have a lifespan of about 40 years, they're said by some to be our closest relative. Humans have triple the lifespan yet over 98% genome similarity iirc.

What was the main change(s) done to triple lifespan between species? how can we know that similar change(s) won't result in further extension, or even indefinite extension?

It is said that the membrane composition changes, in clams it becomes exponentially more resistant with increasing longevity especially in the mitochondria. It may be that this is one of if not the principal change that leads to agelessness.

Another interesting snippet, is that it is said that membrane composition changes adversely with age becoming less resistant to damage which should increase damage load on the organism and increase the probability of failure to maintain homeostasis.

Posted by: Darian Smith at February 22, 2014 12:23 AM
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