Magnesium’s Importance Far Greater Than Previously Imagined

Calcium deficiency is a common nutritional concern, but how many folks consider the vital importance of magnesium in human health and disease?  

New research published in the journal BMC Bioinformatics indicates that magnesium’s role in Continue reading

A New Genetic Fingerprint Lives in your Belly

Our bodies contain far more microbial genes than human genes. And a new study suggests that just as human DNA varies from person to person, so too does the massive collection of microbial DNA in the intestine. Continue reading

Are Humans Devolving? Research Suggests Humans Loosing Intellectual, Emotional Abilities

Have you ever wondered – and maybe even said out loud – why so many people seem downright dumb? According to a hypothesis just published in the Cell Press journal Trends in Genetics, maybe humans are becoming less intelligent. Continue reading

A STAR Scientist Discovers how to Combat Hospital-Acquired Infections, Deadly Food Poisoning and Bioterrorism Toxins

This study paves the way for developing toxin antidotes to safeguard public health and national security.

A team of scientists from A*STAR’s Institute of Molecular and Cell Biology (IMCB) has discovered the secret recipe for ‘antidotes’ that could neutralize the deadly plant toxin Ricin, widely feared for its bioterrorism potential, as well as the Pseudomonas exotoxin (PE) responsible for the tens of thousands of hospital-acquired infections in immune-compromised patients all over the world. The results of this first ever genome-wide study to understand how the Ricin and PE toxins attack cells may also be useful for designing more effective antidotes against Diphtheria and Shiga-like toxins secreted by infectious strains of E. coli bacteria, such as those responsible for the recent food poisoning Continue reading

Milk from ‘Spider Goats’ Could Produce Ligament Replacement Material

What’s stronger than Kevlar, stretchier than nylon, and a natural material that has long intrigued scientists and engineers because of its potential medical applications? The strongest of the six types of spider silk, referred to as “dragline” silk, is used for outer circles of a web, or for repelling from ceiling to floor.

In the early ‘90s molecular biologist Randolph Lewis and his colleagues at University of Wyoming in Laramie identified the two proteins that make up the strong silk, but the large size of the proteins made the attempts to mass-produce the silk from spiders unsuccessful. Cannibalistic spiders also aren’t the ideal animal to farm commercially for the quantities needed, so the researchers have experimented with inserting the silk-producing genes into the genome of animals including cows, hamsters, and most recently, goats. Continue reading

Banana Plantations Threatened by Fungal Disease

About four million tons of bananas are imported into the EU each year. A fungal disease is now threatening banana plantations, and plant breeders have not yet succeeded in developing resistant cultivars. Many hope that genetic engineering can offer a solution. At this point, such projects are still only in the greenhouse.

Monocultures offer the perfect conditions for the spreading of pests and diseases. In this respect, bananas are no different from any other crop.

Back in the 50s, the most common banana variety, Gros Michel, was completely wiped-out by what was known as Panama disease. This disease was caused by the fungus Fusarium oxysporum, also called fusarium wilt. Gros Michel was replaced by a resistant southern Chinese variety called Cavendish. Continue reading

Penguin DNA May Reset the Molecular Clock

(SYDNEY) – Scientists use the “molecular clock”—an estimated rate of DNA mutation—to date key events such as migrations and the divergence of species. But just how accurately the clock keeps time has long been debated. A new study of living and ancient Antarctic penguins, like those on Ross Island at left, suggests that DNA mutates six times faster than predicted. That could mean that some species—such as chimps and humans—could have split off from each other much more recently in time than previously thought. The finding should help improve the dating of relatively recent events, including when people domesticated various crops and animals, and when major human migrations occurred.

To use the molecular clock, scientists estimate the rate of mutation in DNA, estimating that the mutations occur in a steady, clocklike manner. For example, if a gene accumulates changes at a rate of five every 1 million years, 25 mutations in a genetic sequence would mean that the sequences had diverged 5 million years ago. The technique has been used to estimate when humans separated from the other great apes, to estimate the arrival of people in the Americas, and to create evolutionary trees for many species. Molecular clocks are usually calibrated by using the age of a known species from the fossil record. But scientists disagree about the speed or rate at which mutations occur and under what circumstances the rate is influenced by natural selection or other factors.

To see just how accurate molecular dating is, David Lambert, an evolutionary biologist at Griffith University in Queensland, Australia, and colleagues looked at Adélie penguins. These Antarctic birds may be the best species yet for building an accurate clock, the team argues, because scientists can study the genetic sequences of both living and ancient members of the species. The penguins generally return each year to the same nesting ground; thus, each rookery can have layers of bones dating far back in time. Indeed, the birds have nested at some rookeries for 44,000 years. “You can take blood samples from the living penguins and then literally collect the bones of their ancestors” in the ground below, says Lambert, because the penguins usually return to their natal colony to mate. Other studies usually can only compare genes from organisms separated in time by millions of years.

Using modern blood and ancient bone samples, the researchers extracted the entire mitochondrial genome from 12 modern and eight ancient penguins, including two that were dated to 44,000 years ago using radiocarbon methods. They then compared the mitochondrial DNA of the living penguins with the ancient ones to determine the number of mutations that had occurred. Because they had radiocarbon dates for the ages of the ancient penguins, the scientists could accurately measure the bird’s average mutation rate, ultimately calculating that its mitochondrial genome had evolved at a rate two-to-six times faster than previously estimated.

The team’s findings, reported in this month’s issue of Trends in Genetics, support similar results for faster clocks in mitochondrial sequences in cattle. But in this new study, the researchers succeeded in calculating the rate of mutation within almost the entire mitochondrial genome, providing “more conclusive evidence,” for a rapidly ticking clock, says Dee Denver, an evolutionary biologist at Oregon State University in Corvallis and one of the paper’s co-authors. They also focused on a region of the genome that is known to not be influenced by natural selection, they write in the paper. Thus, they say that the resulting clock is not merely a reflection of penguin evolutionary history and can be applied to other species.

“It’s novel and groundbreaking work,” says Mark Hauber, an evolutionary biologist at Hunter College in New York City, who was not affiliated with the study. “It’s a significant discovery,” adds Elizabeth Matisoo-Smith, a biological anthropologist at Otago School of Medical Sciences in Dunedin, New Zealand, who expects it will help resolve several discrepancies between genetic data and the archaeological record, such as the peopling of the Pacific Islands and the Americas. However, the penguins’ rapid clock “should be confirmed on a wide diversity of species” before being adopted as the new standard, says Robert Wayne, an evolutionary geneticist at the University of California, Los Angeles.

Scientists Watch Evolution Unfold In a Bottle

DETROIT  – Scientists now have physical proof of how species evolve and the fittest survive, after a 21-year study in which they documented the evolution of single-celled E. coli bacteria over 40,000 generations.

Richard Lenski, Hannah professor of microbial ecology at Michigan State University (MSU), said: “It’s extra nice now to be able to show precisely how selection has changed the genomes of these bacteria, step by step over tens of thousands of generations.”

 

Lenski’s team periodically froze bacteria for later study, and technology has since developed to allow complete genetic sequencing. By the 20,000-generation midpoint, researchers discovered 45 mutations among surviving cells in the bottled bacteria.

Those mutations, according to Darwin’s theory, should have conferred some advantage, and that’s exactly what the researchers found.

The results “beautifully emphasise the succession of mutational events that allowed these organisms to climb toward higher and higher efficiency in their environment”, noted Dominique Schneider, molecular geneticist at the Universit Joseph Fourier in Grenoble, France.

Lenski’s long-running experiment itself is uniquely suited to answer some critical questions — such as whether rates of change in a bacteria’s genome move in tandem with its fitness to survive.

A mutation involved in DNA metabolism arose around generation 26,000, causing the mutation rate everywhere else in the genome to increase dramatically.

The number of mutations jumped to 653 by generation 40,000, but researchers surmise that most of the late-evolving mutations were not helpful to the bacteria, said an MSU release.

Gene mutations involved in human DNA replication are involved in some cancers. Many of the patterns observed in the experiment also occur in certain microbial infections, “and cancer progression is a fundamentally similar evolutionary process”, observed collaborator Jeffrey Barrick.

“So what we learn here can help us better understand the course of these diseases.”

The paper involved collaboration with scientists from South Korea as well as France and MSU.

The findings were published in Nature.