If you are curious about Earth's periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits.

But a new study suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions during the past 500 million years.[1]

"The expansions and contractions of those environments have pretty profound effects on life on Earth," says Shanan Peters, a University of Wisconsin-Madison assistant professor of geology and geophysics and the author of the new Nature report.

Overweight men are not more likely to be infertile, as past research has shown to be true in obese women, according to a new study. The results will be presented at The Endocrine Society’s 90th Annual Meeting in San Francisco.

Findings of the study, performed in New York in nearly 300 very overweight men, were unexpected, said coauthor Nanette Santoro, MD, an Albert Einstein College of Medicine obstetrician-gynecologist who is trained in reproductive endocrinology.

Santoro and her colleagues studied 292 men who gave semen samples at fertility clinics. The men were ages 18 to 50 and, on average, had a body mass index (BMI) of 28, which is considered nearly obese. The authors found that greater body weight was not associated with worse sperm production or sperm motility. Impaired sperm production is the cause of infertility in 90 percent of infertile men, according to Santoro. About 6 percent of reproductive-age men are infertile, she said.

One of the nation’s leading joint specialists, Javad Parvizi, M.D., Ph.D., of the Rothman Institute at Thomas Jefferson University Hospital, says you should believe your grandmother, friend or co-worker when they tell you it’s going to rain — even if it’s simply because their aching knees, hips, hands or shoulders “say so.”

Dr. Parvizi, who is also director of clinical research at the Rothman Institute at Jefferson, and associate professor of Orthopaedic Surgery at Jefferson Medical College of Thomas Jefferson University in Philadelphia, explains that even though individuals can experience pain fluctuations with the slightest change in barometric pressure, most patients report significant increases in pain before and during severe changes in weather, like summer downpours and thunderstorms.

Why would humans evolve allergy problems? A team from the Randall Division of Cell & Molecular Biophysics, King's College London are working on a molecule vital to the chicken's immune system which represents the evolutionary ancestor of the human antibodies that cause allergic reactions.

Crucially, they have discovered that the chicken molecule behaves quite differently from its human counterpart, which throws light on the origin and cause of allergic reactions in humans and gives hope for new strategies for treatment.

The chicken molecule, an antibody called IgY, looks remarkably similar to the human antibody IgE. IgE is known to be involved in allergic reactions and humans also have a counterpart antibody called IgG that helps to destroy invading viruses and bacteria. Scientists know that both IgE and IgG were present in mammals around 160 million years ago because the corresponding genes are found in the recently published platypus genome. However, in chickens there is no equivalent to IgG and so IgY performs both functions.

Every year, about 500 million people worldwide are infected with the parasite that causes dysentery, a global medical burden that among infectious diseases is second only to malaria. In a new study appearing in the June 15 issue of Genes and Development, Johns Hopkins researchers may have found a way to ease this burden by discovering a new enzyme that may help the dysentery-causing amoeba evade the immune system.

"This is the first enzyme to be identified that looks like it could mediate immune system evasion," says Sin Urban, Ph.D., an assistant professor of molecular biology and genetics at Hopkins.

The EhROM1 enzyme, it turns out, is part of an ancient group of enzymes—they are found in every branch of life from bacteria to man—known as rhomboid enzymes. In most animals, rhomboid enzymes seem to play a role in cell-to-cell communication, but a couple of years ago Urban found that malaria parasites use rhomboid enzymes for a more sinister purpose: to enter host cells uninvited.

As a science site, one thing we understand is physics and how it can be exculpatory - no snowflake in an avalance ever has to take the blame.

The American Beverage Association(ABA) knows this too. They are the trade association representing the broad spectrum of companies that manufacture and distribute non-alcoholic beverages in the United States - that means soda and juice but also water and things that are basically good for you. Dr. Maureen Storey is their senior vice president for science policy and former director of the University of Maryland's Center for Food, Nutrition, and Agriculture Policy.

The ABA recognizes there is a lot of talk about childhood obesity and the link to sugary drinks. Since no snowflake in an avalanche takes the blame, that means obesity should be Doritos or it can be bread or it can be bad parents who buy their kids sugary drinks but the one thing that cannot definitively be linked to obesity are sugary drinks or the advertising departments at sugary drink companies. To prove this, Storey and colleagues did a meta-analysis (see notes) of 12 recent studies and published it in the June issue of the American Journal of Clinical Nutrition.

Well, I have previously started an "Open Evolution" series here and now I am starting an "Open Metagenomics" series. I know, I have gotten grief from some out there (yes, you Rob Edwards - see comments here) about my support for somewhat non-open things in metagenomics, so I am going to try and make up for that as much as possible. In the first installment, I am pointing people to a new paper on PLoS Genetics "Trends in Selenium Utilization in Marine Microbial World Revealed through the Analysis of the Global Ocean Sampling (GOS) Project" by Yan Zhang, Vadim N. Gladyshev (hat tip to Katie Pollard for pointing out this paper).

It's an urban legend we've all read - you meet some nice girl in Thailand and you black out and wake up in a bathtub without a kidney.

Kidneys, and other replaceable organs, have value because the wait list is long and someone has to die to donate them.

Arthur Matas, Professor of Surgery at the University of Minnesota, writing in this week's BMJ says a regulated system of compensation for living donors may be the solution to the growing shortage of kidneys for transplantation.

But Jeremy Chapman, from the Centre for Transplant and Renal Research in Sydney, argues that this could reduce the supply of all organs. He believes that the idea of the regulated market is a myth, which could have devastating consequences on the less easily regulated environments of Asia and Africa.

New evidence that chemical contaminants are finding their way into the deep-sea food web has been found in deep-sea squids and octopods, including the strange-looking "vampire squid". These species are food for deep-diving toothed whales and other predators.

In a study to be published in the journal Marine Pollution Bulletin, Michael Vecchione of NOAA Fisheries' National Systematics Laboratory and colleagues Michael Unger, Ellen Harvey and George Vadas at the Virginia Institute of Marine Science of The College of William and Mary report finding a variety of chemical contaminants in nine species of cephalopods, a class of organisms that includes octopods, squids, cuttlefishes and nautiluses.

Cephalopods are important to the diet of cetaceans, a class of marine mammals which includes whales, dolphins and porpoises. Cephalopods are the primary food for 28 species of odontocetes, the sub-order of cetaceans that have teeth and include beaked, sperm, killer and beluga whales and narwhals as well as dolphins and porpoises.

Fragile X syndrome (FXS) robs the brain of a protein that plays a major role in the way neurons communicate and that is essential for brain development, learning and memory.

A team of scientists has discovered new information about how FXS interferes with signaling between the nucleus of neurons and the synapse, the outer reaches of the neuron where two neurons communicate via chemical and electrical signals. The discovery should help lead the way to the development of new treatments for FXS, the most common form of inherited mental retardation and also a genetic contributor to some types of autism and epilepsy.

Translation of an organism's genetic information begins in the nucleus of a cell, where the DNA sequence (gene) is copied into an mRNA molecule, then exported into the cell's cytoplasm and translated into protein molecules.