Sequencing of frog genome may offer new insights into human diseases

Washington, May 7 (ANI): An international team of researchers has cracked the genetic code of an amphibian, the African clawed frog Xenopus tropicali – the latest research aimed at understanding how genes work for potential applications in human health.

The genome of Xenopus tropicalis has been analysed by an international consortium of scientists from 24 institutions, and joins a list of sequenced model organisms including the mouse, zebrafish, nematode and fruit fly.

What’s most surprising, researchers say, is how closely the amphibian’s genome resembles that of the mouse, the chicken and the human, with large swathes of frog DNA on several chromosomes having genes arranged in the same order as in these mammals.

“A lot of furry animals have been sequenced, but far fewer other vertebrates,” said co-author Richard Harland, University of California, Berkeley, professor of molecular and cell biology.

“Having a complete catalog of the genes in Xenopus, along with those of humans, rats, mice and chickens, will help us reassemble the full complement of ancestral vertebrate genes.”

The researchers found that nearly 80 per cent of all human genes associated with genetic diseases have counterparts in the western-clawed frog, Xenopus tropicalis.

This discovery could lead to a better understanding of the genetic and chemical basis for many of the human diseases.

The research, published this week in the journal Science, was led by the Department of Energy’s Joint Genome Institute (JGI) and the University of California, Berkeley. (ANI)

Human and frogs share the ‘kissing cousin’ bond

Washington, April 30 (ANI): An international team of researchers has cracked the genetic code of an amphibian, the African clawed frog Xenopus tropicali – the latest research aimed at understanding how genes work for potential applications in human health.

The genome of Xenopus tropicalis has been analysed by an international consortium of scientists from 24 institutions, and joins a list of sequenced model organisms including the mouse, zebrafish, nematode and fruit fly.

What”s most surprising, researchers say, is how closely the amphibian”s genome resembles that of the mouse, the chicken and the human, with large swathes of frog DNA on several chromosomes having genes arranged in the same order as in these mammals.

“A lot of furry animals have been sequenced, but far fewer other vertebrates,” said co-author Richard Harland, University of California, Berkeley, professor of molecular and cell biology.

“Having a complete catalog of the genes in Xenopus, along with those of humans, rats, mice and chickens, will help us reassemble the full complement of ancestral vertebrate genes.”

The researchers found that nearly 80 per cent of all human genes associated with genetic diseases have counterparts in the western-clawed frog, Xenopus tropicalis.

This discovery could lead to a better understanding of the genetic and chemical basis for many of the human diseases.

The research, published this week in the journal Science, was led by the Department of Energy”s Joint Genome Institute (JGI) and the University of California, Berkeley. (ANI)

How specific odours alter an organism’s lifespan

Washington, Apr 21 (ANI): Specific odours that represent food or indicate danger trigger a small number of highly specialized sensory neurons that can alter an animal”s lifespan and physiological profile, according to researchers at the University of Michigan, University of Houston, and Baylor College of Medicine.

Recent research in model organisms and in humans has shown that sensory experiences can impact a wide range of health-related characteristics including athletic performance, type II diabetes, and aging.

Nematode worms and fruit flies that were robbed of their ability to smell or taste, for example, lived substantially longer.

However, the specific odours and sensory receptors that control this effect on aging were unknown.

The researchers used molecular genetics in combination with behavioural and environmental manipulations, and successfully identified carbon dioxide (CO2) as the first well-defined odorant capable of altering physiology and affecting aging.

Flies incapable of smelling CO2 live longer than flies with normal olfactory capabilities.

They are also resistant to stress and have increased body fat. To many insects, including fruit flies, CO2 represents an ecologically important odour cue that indicates the presence of food (e.g. rotting fruit or animal blood) or neighbours in distress (it has been implicated as a stress pheromone).

The researchers previously showed that merely sensing one”s normal food source is capable of reversing the health and longevity benefits that are associated with a low calorie diet.

They now establish that CO2 is responsible for this effect.

“We are working hard to understand how sensory perception affects health, and our new result really narrows the playing field. Somehow these 50 or so neurons, whose primary job it is to sense CO2, are capable of instigating changes that accelerate aging throughout the organism,” said Scott Pletcher.

Sensory perception has been shown to impact aging in species that are separated by millions of years of evolution, suggesting that similar effects may be seen in humans.

“For us, it may not be the smell of yeast, for example, or the sensing of CO2 that affects how long we live, but it may be the perception of food or danger,” said Pletcher.

If so, a clever program of controlled perceptual experience might form the basis of a simple yet powerful program of disease prevention and healthy aging.

The study has been published in the online, open-access journal PLoS Biology. (ANI)

Yeast cells decide whether to have sex with each other within 2mins of meeting

London, April 19 (ANI): Yeast cells can decide to mate within two minutes of meeting each other, a new research has found.

According to one of the authors of the study, from Imperial College London, the findings of the study could be helpful for researchers looking at how cancer cells and stem cells develop.

Yeasts are single-celled microbes that scientists often use as model organisms, to understand how cells work.

Yeasts usually reproduce asexually, by a process called budding, where a part of the cell is pinched off and becomes a new cell, identical to the original.

However, there are times when yeast cells reproduce sexually, by mating.

The mating process involves one cell of each sex joining together, then mixing their DNA and splitting apart again.

To do this, the cells each have to produce a nodule that they can join together, called a shmoo. The process of shmooing takes around two hours.

For the new study, researchers from Imperial College London, Université de Montréal, McGill University and the University of Edinburgh determined that a yeast cell”s decision to mate is controlled by a chemical change on a single protein.

This change takes place two minutes after the cell detects a pheromone produced by the opposite sex.

The study team also found that in order for the mating process to be switched on, the pheromone must reach a critical concentration in the environment around the yeast cell.

Below this concentration, the yeast cell continues to reproduce asexually.

Dr Vahid Shahrezaei, one of the authors of the study from the Department of Mathematics at Imperial College London, said: “Shmooing is a very energy-intensive process for yeast cells. We think this switching process at a certain pheromone concentration may have evolved to make sure the cells only get prepared for sexual reproduction if a mate is sufficiently close enough and able to mate.”

The researchers used a highly complex mathematical model to find what switches the mating process on and off, factoring in experimental data about the concentration of pheromones around the cell, the concentrations of different proteins relevant to mating inside the cell and how strongly these proteins bind together.

Dr Shahrezaei said: “Yeast cells live in a very noisy environment – they are surrounded by different chemicals, including pheromones and food, and their own machinery inside the cell produces lots of biomolecules that interact with each other. We wanted to see how cells make sense of this noisy environment and work out what is happening, at a molecular level, to make a important decision like mating.

“By combining experiments and mathematical modelling that take lots of different factors into consideration, we have been able to show exactly what is happening inside a yeast cell to make it decide whether to mate with another cell. We also showed that the mechanism that leads the cells to make their decision is very robust, meaning it is not affected by molecular noise in the environment.”

Senior author Dr Stephen Michnick, a Université de Montréal biochemistry professor and Canada Research Chair in Integrative Genomics, said: “Although yeast is dramatically different from people, at a molecular and cellular level we have a lot in common.

“The same molecules that create the switching decision in yeast are found in very similar forms in human cells. Similar switching decisions to those made by yeast are made by stem cells during embryonic development and become dysfunctional in cancers.”

The study has appeared in the journal Nature. (ANI)

Yeast cells decide whether to have sex with each other within 2mins of meeting

London, April 19 (ANI): Yeast cells can decide to mate within two minutes of meeting each other, a new research has found.

According to one of the authors of the study, from Imperial College London, the findings of the study could be helpful for researchers looking at how cancer cells and stem cells develop.

Yeasts are single-celled microbes that scientists often use as model organisms, to understand how cells work.

Yeasts usually reproduce asexually, by a process called budding, where a part of the cell is pinched off and becomes a new cell, identical to the original.

However, there are times when yeast cells reproduce sexually, by mating.

The mating process involves one cell of each sex joining together, then mixing their DNA and splitting apart again.

To do this, the cells each have to produce a nodule that they can join together, called a shmoo. The process of shmooing takes around two hours.

For the new study, researchers from Imperial College London, Université de Montréal, McGill University and the University of Edinburgh determined that a yeast cell”s decision to mate is controlled by a chemical change on a single protein.

This change takes place two minutes after the cell detects a pheromone produced by the opposite sex.

The study team also found that in order for the mating process to be switched on, the pheromone must reach a critical concentration in the environment around the yeast cell.

Below this concentration, the yeast cell continues to reproduce asexually.

Dr Vahid Shahrezaei, one of the authors of the study from the Department of Mathematics at Imperial College London, said: “Shmooing is a very energy-intensive process for yeast cells. We think this switching process at a certain pheromone concentration may have evolved to make sure the cells only get prepared for sexual reproduction if a mate is sufficiently close enough and able to mate.”

The researchers used a highly complex mathematical model to find what switches the mating process on and off, factoring in experimental data about the concentration of pheromones around the cell, the concentrations of different proteins relevant to mating inside the cell and how strongly these proteins bind together.

Dr Shahrezaei said: “Yeast cells live in a very noisy environment – they are surrounded by different chemicals, including pheromones and food, and their own machinery inside the cell produces lots of biomolecules that interact with each other. We wanted to see how cells make sense of this noisy environment and work out what is happening, at a molecular level, to make a important decision like mating.

“By combining experiments and mathematical modelling that take lots of different factors into consideration, we have been able to show exactly what is happening inside a yeast cell to make it decide whether to mate with another cell. We also showed that the mechanism that leads the cells to make their decision is very robust, meaning it is not affected by molecular noise in the environment.”

Senior author Dr Stephen Michnick, a Université de Montréal biochemistry professor and Canada Research Chair in Integrative Genomics, said: “Although yeast is dramatically different from people, at a molecular and cellular level we have a lot in common.

“The same molecules that create the switching decision in yeast are found in very similar forms in human cells. Similar switching decisions to those made by yeast are made by stem cells during embryonic development and become dysfunctional in cancers.”

The study has appeared in the journal Nature. (ANI)

Global warming threatens existence of tropical species

Washington, August 26 (ANI): A new research has determined that global warming threatens the existence of tropical species, the ecosystem and its by-products.

The research was done by herpetologist Laurie Vitt, curator of reptiles and George Lynn Cross Research Professor at the University of Oklahoma’s Sam Noble Museum of Natural History.

Vitt has studied the ecology of lizards in rain forests around the world and, for the past 20 years, as part of a biodiversity project in the Amazon.

As a fellow researcher on a study funded by the National Science Foundation, Vitt investigated the affects of global warming on tropical lizards and the diversity of the ecosystem.

“We depend on these tropical lizards and other species of animals and plants for food, materials, and pharmaceuticals, but we are losing these species as a result of global warming,” Vitt said.

Tropical species are affected more by the very narrow temperature range of their typically warm climate than are ectotherms living where the temperatures fluctuate in greater degrees.

Even the smallest change in the tropics makes a difference to the tropical species most susceptible to climate change.

“Climatic shifts are part of our natural history, but years of research indicate global warming has increased the rate at which climate change is taking place,” said Vitt.

As populations grow around the world, so does consumption. In the densest areas of the world, the elimination of animals that feed on disease vectors, such as mosquitoes and flies, adds to our growing human health problem.

“The loss of these predators, like tropical species, upset the natural biodiversity of the ecosystem,” said Vitt. “The effects may not be so obvious in the short term, but the long-term effects will be irreversible,” he added.

“Our ability to connect with nature and better understand tropical lizards is important because these animals serve as model organisms for detecting the effects of global warming,” Vitt summarized.

“Ecosystems are complex and interdependent. When one species becomes extinct, the entire system is affected. The long-term effects on human health can be dramatic,” he said. (ANI)

‘Happy hour’ gene may help boozers stay away from alcohol

Washington, May 22 (ANI): A newly identified gene, dubbed happyhour, controls fruit flies’ response to booze. Researchers now claim that drugs mimicking the effects of the gene may offer a new treatment against alcohol addiction.

Animals with a mutant version of the gene grow increasingly resistant to alcohol’s sedative effects, the research shows.

The researchers report further evidence that the gene normally does its work by blocking the so-called Epidermal Growth Factor (EGF) pathway. That EGF pathway is best known for its role in cancer, and drugs designed to inhibit the EGF receptor, including erlotinib (trade name Tarceva) and gefitinib (trade name Iressa), are FDA-approved for the treatment of non-small cell lung cancer.

Now, the researchers show that flies and mice treated with erlotinib also grow more sensitive to alcohol. What’s more, rats given the cancer-fighting drug spontaneously consumed less alcohol when it was freely available to them. Their taste for another rewarding beverage-sugar water-was unaffected.

“This is a very powerful example of how simple model organisms-and the little fruit fly in particular-can be used to move quickly from an unknown gene to a potential therapy for drug addiction,” said Ulrike Heberlein of the University of California, San Francisco, noting that erlotinib and gefitinib, along with other EGFR inhibitors, not only cross the blood-brain barrier in humans, but they are also well-tolerated in general.

Heberlein’s team explained, genes and pathways involved in the acute response to alcohol can yield insight into the genetic factors contributing to the more complex process of addiction.

In the study, researchers screened mutant flies for those less sensitive to ethanol. That screen led them to happyhour, a gene closely related to mammalian enzymes known as the Ste20-family kinases of the GCK-1 subfamily.

Heberlein said they still don’t know exactly how alcohol exerts its influence on the EGFR pathway or how that leads to the telltale changes in behavior that come with alcohol intoxication. (ANI)