The prevailing wisdom has been that women have a finite number of eggs, that gradually diminish in number and quality until the menopause.

But British experts said the findings, published in the journal Nature Medicine, “re-write the rule book” on this point and amounted to “a potentially landmark piece of research”.

The academics, led by Dr Jonathan Tilly of Massachusetts General Hospital, managed to identify and extract human stem cells that can go on to become immature eggs, because all carry a unique protein called DDX4.

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The rogue proteins behind variant CJD, the human form of mad cow disease, have revealed their benign side. Prions, it seems, lie at the heart of a newly discovered form of near-instant evolution that provides life with a third way to adapt to potentially lethal environments. Crucially, it involves neither genetic nor epigenetic changes to DNA.

The conventional view is that new traits can only evolve if DNA itself changes in some way. The classic way to do this is by mutating the genetic code itself. More recently, researchers have discovered that molecules can clamp onto DNA and prevent some parts of the sequence from being read, leading to genetic changes through a process that is known as epigenetics.

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neurosciencestuff:

February 23rd, 2012

Researchers at the RIKEN-MIT Center for Neural Circuit Genetics have discovered an answer to the long-standing mystery of how brain cells can both remember new memories while also maintaining older ones.

They found that specific neurons in a brain region called the dentate…

“A tiny piece of RNA plays a key role in determining when muscle stem cells from mice activate and start to divide, according to researchers at the Stanford University School of Medicine. The finding may help scientists learn how to prepare human muscle stem cells for use in therapies for conditions such as muscular dystrophy and aging by controlling their activation state.”

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Scientists have developed a new community resource that may act as a Rosetta Stone for revealing the genetic basis of traits and disease.

“One of the grand challenges of biology is to understand how genetic variants and environmental factors interact to produce variation in complex phenotypes such as height, behaviors, and disease susceptibility within populations. This effort has been stymied by the lack of knowledge of all genetic variants in a population of a genetically tractable model organism. The DGRP sequences provide such a resource,” Mackay noted.”

“A study of rhesus macaque monkeys found that while male DNA was lost at first, the rate of reduction tailed off.

Researchers said they hoped their findings would put an end to theories that the Y chromosome was dying out after claims that its 1,400 genes had fallen in number to just 45 in the last three hundred million years.

The belief was named the “rotting Y theory” and was based on an assumption that the Y chromosome would carry on losing genes until it disappeared.”

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“Scientists have known for some time that a low-calorie diet is a recipe for longer life. Rats and mice reared on restricted amounts of food increase their lifespan by up to 40%. A similar effect has been noted in humans. But Mattson and his team have taken this notion further. They argue that starving yourself occasionally can stave off not just ill-health and early death but delay the onset of conditions affecting the brain, including strokes. “Our animal experiments clearly suggest this,” said Mattson.

He and his colleagues have also worked out a specific mechanism by which the growth of neurones in the brain could be affected by reduced energy intakes. Amounts of two cellular messaging chemicals are boosted when calorie intake is sharply reduced, said Mattson. These chemical messengers play an important role in boosting the growth of neurones in the brain, a process that would counteract the impact of Alzheimer’s and Parkinson’s.

“The cells of the brain are put under mild stress that is analogous to the effects of exercise on muscle cells,” said Mattson. “The overall effect is beneficial.”