Genes controlling insulin ‘alter’ body clock

Washington, Sept 18 (ANI): Scientists at University of California, San Diego have identified certain insulin-regulating genes that can also alter the timing of the body clock.

They said that the findings can lead to new approaches to treating disorders such as metabolic syndrome that can result, at least in part, from chronic disruption of the sleep-wake cycle.

“People knew that the clock regulates many different processes, but what they didn’t realize what that when you tweak those processes, it feeds back and alters the clock,” said Steve Kay, Dean of the Division of Biological Sciences at the University of California, San Diego, who led the study along with John Hogenesch of the University of Pennsylvania.

A molecular clock controls daily physiological rhythms in many types of cells, even cells grown in culture.

By engineering cultured cells to glow yellow when a particular clock gene switched on, the team made the cycle visible. They then interfered with every human gene to see which would shift the clock. They found that hundreds altered the timing.

“We just suddenly discovered 350 new genes that affect the clock that weren’t known before,” Kay said.

However, subsequent screening to confirm the genes’ effect on a second clock gene narrowed the list to 200.

Seven genes involved in insulin control also influenced the rhythms of the clock.

“What came out very strongly was this close relationship between circadian regulation and insulin signalling. There’s a reciprocal relationship between circadian dysfunction and metabolic dysfunction,” said Kay.

The researchers suggest that genetically altered mice with malfunctioning clocks become obese and develop diet-induced diabetes.Understanding this close relationship between circadian regulation and metabolic homeostasis should provide novel ways of identifying new therapies for metabolic disease,” Kay added.

The study appears in journal Cell. (ANI)

Seagrass habitat helped seahorses evolve their upright posture 25 mln yrs ago

Sydney, May 6 (ANI): In a new research, scientists have found that seahorses evolved their upright posture some 25 million years ago, thanks in part to an expansion of vertical seagrass habitat.

The research was carried out by Associate Professor Luciano Beheregaray of Flinders University and Dr Peter Teske of Macquarie University.

Seahorses are unique fish with a horse-shaped head and a habit of swimming upright.

According to Beheregaray, it has been hard for scientists to work out when exactly seahorses evolved to swim upright.

This is because there are only two known fossils of seahorses – the oldest dating back to 13 million years – and no link between these and horizontally-swimming fish had been found.

“When you look back in time, you don’t see intermediate seahorse-like fish,” said Beheregaray.

But, he says, there are fish alive today that look like horizontally-swimming seahorses and these could provide clues as to when seahorses evolved to be upright.

Beheregaray and Teske compared the DNA of seahorses and other species from the same family to find out which was the closest living relative to seahorses.

“The pygmy pipehorses are by far the most seahorse-like fish on earth. They do look like the seahorses, but they swim horizontally,” said Beheregaray.

He and Teske used molecular dating techniques, which relies on the accumulation of differences in the DNA between the two species to work out when they diverged.

The researchers used the two existing fossil seahorses to calibrate the rate of evolution of DNA in their molecular clock.

They discovered that the last common ancestor of seahorses and pygmy pipehorses lived around 25 to 28 million years ago.

According to Beheregaray, the time that seahorses arose during the Oligocene epoch coincided with the formation of vast areas of shallow water and expansion of seagrass in Australasia, where Teske has previously showed seahorses first evolved.

“Seagrass was the perfect habitat for an upright-swimming seahorse, which could camouflage itself in the vertical seagrass blades,” he said.

The horizontal-swimming pygmy pipehorses, by contrast, thrived in large algae on reefs and didn’t have the need to evolve the upright posture.

“The two groups split in a period when there were conditions favouring that split,” said Beheregaray.

“It’s like us. We started walking upright when we moved to the savannahs. On the other hand, the seahorses invaded the new vast areas of seagrass,” he added. (ANI)

Primate ancestors of HIV could be younger than previously believed

Washington, May 1 (ANI): In a surprising discovery, scientists have found that the ancestors of the simian immunodeficiency viruses (SIVs) that jumped from chimpanzees and monkeys, and ignited the HIV/AIDS pandemic in humans, originated just a few centuries ago.

The new study from The University of Arizona in Tucson revealed that these ages are substantially younger than previous estimates.

SIV has crossed over from chimpanzees and sooty mangabeys to humans at least eleven times, giving rise to several HIV lineages.

While HIV is a virulent pathogen in humans, SIV rarely causes disease in these species or the dozens of other African primate species it naturally infects.

And because these non-human primates typically remain unaffected after virus exposure, scientists had hypothesised that there had been millions of years of coevolution between SIVs and their primate hosts.

But, in the new study, researchers, Joel Wertheim and Dr. Michael Worobey, estimated a rate of virus evolution using viral genetic sequences that had been isolated from infected humans, chimpanzees, and sooty mangabeys between 1975 and 2005.

And their analysis revealed that the viruses currently circulating in sooty mangabeys and in chimpanzees evolved from ancestors dating to 1809 and 1492, respectively.

To their surprise, they found that the independently estimated ‘molecular clock’ of the monkey viruses was virtually identical to the famously swift rate at which mutations accumulate in HIV genomes.

The authors pointed out that unaccounted-for biases could be masking a deeper age of SIV.

They suggested that presence of these biases indicates a need for investigation because they might also affect the ability to properly estimate the age of HIV and other viruses.

The study is published in the open-access journal PLoS Computational Biology. (ANI)