Monday, 9 July 2012
Biology stuff from the week 2-8/7/12
'Antarctic moss found able to survive due to ancient penguin colony guano'
The tonnes and tonnes of guano left by Adelie penguin populations, thousands of years ago, that are actually visible from outer space, provide the nitrogen necessary to support vast areas of moss.
And because the moss lives there, other small organisms can live amongst it. What the researchers don't yet know, is how the moss survives being freeze-dried by the Antarctic winters.
'Mass extinctions reset the long-term pace of evolution'
Rates of evolution (the pace at which new permutations, classifiable as a 'different' species) fall in tandem with populations, consequent to extinction events.
Presumably this is just a matter of statistics -- the larger your population, the higher your chance of evolving a new and beneficial characteristic.
'Hormones dictate when youngsters fly the nest'
Manx shearwaters feed their chicks less and less, tailing off to nothing after 60 days. But lack of food does not determine how soon they leave the nest.
The birds' hormones determine when they fly the nest -- they'll leave early if corticosteroids peak early, and will not hang around for extra food if they receive surrogate parents mid-childhood.
Another study, this time in sheep, has found that adolescent hormonal fluctuations are responsible for emotional reaction to stressful situations.
With sex-related hormones blocked, female sheep showed no difference, and a greater emotional response, but males showed a lower emotional response when their sex hormones weren't blocked.
Flies, which have been around for 260 million years, have evolved advanced olfactory mechanisms (sense of smell), enabling it to sense a wide variety of air-borne chemicals.
A much wider range than can the hermit crab, which spends much of its life near the shore, but is limited to smells that are easier to detect in higher humidity (or underwater!)
'Humidity increases odour perception in terrestrial hermit crabs'
'The sensation of cold is shut down by inflammation'
When compounds, such as histamine, are released, during inflammation, a Gq protein is activated, which in turn de-activates the TRPM8 protein, which, when active, causes the feeling of coolness.
In cold weather, this protein is usually activated; also, the menthol in chewing gum, minty sweets, etc, activates the TRPM8 protein, which is how menthol tricks us into feeling cool, when actually we're not.
But because Gq deactivates TRPM8, inflammation decreases feelings of coldness. This knowledge empowers us to produce things that can inhibit the TRPM8 deactivation, thereby preserving sensitivity to the cold, even while suffering inflammation.
'Rusty memories rejuvenated in elderly mice'
By injecting a virus that increases the presence of an enzyme called DNA methyltransferase in mice hippocampuses, researchers have managed to improve their memory function to that of 3-month youngsters.
In another application of viruses, a bacteriophage has been used to save corals, in the Red Sea, with no apparent negative effects, on other wildlife.