Our Brains Make Men And Women See Things Differently

According to a new study, published in BioMed Central's open access journalBiology of Sex Differences, men and women have different ways of using the visual centers of their brains. Experts suggest that while females are better at distinguishing colors, males are more sensitive to fine detail and rapidly moving stimuli. There are high concentrations of the male sex hormone (androgen) receptors throughout the cerebral cortex in the brain, particularly in the visual cortex, which is in charge of processing images. Guys have 25% more neurons in the visual cortex than females because, during embryogenesis, androgens are responsible for controlling the development of those neurons. The vision of men and women was compared by a team of researchers from Brooklyn and Hunter Colleges of the City University of New York. The experts observed people over the age of 16 from both college and high school, including students and faculty. Both sexes needed to have normal color vision and 20/20 sight (with glasses or contacts was considered fine), in order to participate. Scientists learned that the color vision of men was shifted, after they asked the volunteers to describe colors shown to them across the visual spectrum. It also became clear that male subjects needed a slightly longer wavelength to experience the same hue as the female subjects. It was not as easy for men to discriminate between colors as it was for women, meaning that the males had a broader ranger in the center of the spectrum. In order to measure contrast-sensitivity functions (CSF) of vision, the researchers used an image of light and dark bars that were either horizontal...

Genetic Clue Discovered For Why Women Outlive Men

A new study of mitochondrial DNA in fruit flies offers a number of clues that might explain why females tend to outlive males across much of the animal kingdom, including humans. Researchers from Monash University in Australia and Lancaster University in the UK, write about their work in the 2 August online issue of Current Biology. They found male fruit flies appear to have mutations in their mitochondrial DNA that affect how fast they age and how long they live. Scientists use fruit flies as models for studies in genes and aging because their biological processes are remarkably similar to that of other animals, such as humans, and with a lifespan of about a month, it doesn't take too long to investigate generational effects. Senior author Damian Dowling, a research fellow in the Monash School of Biological Sciences, told the press: "All animals possess mitochondria, and the tendency for females to outlive males is common to many different species. Our results therefore suggest that the mitochondrial mutations we have uncovered will generally cause faster male aging across the animal kingdom." "Intriguingly, these same mutations have no effects on patterns of aging in females. They only affect males," he added. Mitochondria are special subunits of cells, about the same size as bacteria, that provide the energy for life. They combine sugar and oxygen into adenosine triphosphate or ATP, molecular packets of energy that are usable by cells. Mitochondria have their own DNA that is quite separate from the cellular DNA in the nucleus of the cell. And, unlike cellular DNA, which is inherited from the sperm and egg that fuse to make the new...

Scientists Isolate Hormone That Triggers Health Benefits Of Exercise

An international team of scientists has isolated a natural hormone or chemical messenger in muscle cells that triggers some of the important health benefits of exercise. They have named it "irisin", after the Greek messenger goddess, and believe it is a promising candidate for developing drugs to treat diabetes, obesity and maybe even cancer. Senior author Dr Bruce Spiegelman, from the Dana-Farber Cancer Institute, in Boston, Massachusetts, and colleagues, write about their findings in the 11 January online issue ofNature. Spiegelman is also professor of cell biology at Harvard Medical School in Boston. Spiegelman said for a while researchers have had a notion that exercise "talks to various tissues in the body", but the question was "How?" First author Dr Pontus Bostrom, a postdoctoral fellow who works with Spiegelman in his lab, told the press: "It's exciting to find a natural substance connected to exercise that has such clear therapeutic potential." He and his co-authors believe finding irisin is the start of understanding how physical exercise benefits the body biologically, not only to keep people healthy but also to prevent and treat disease. They came across irisin when they were looking at the effect of exercise on a master metabolic regulator gene called PGC1-alpha, which Spiegelman's group had already identified in previous work. When exercise switches on this gene, it in turn regulates a cluster of genes and proteins. A search for these other genes and proteins turned up irisin. They found it in the outer membranes of muscle cells, and not in the nucleus, as other scientists had predicted. For this study, the researchers used lab cultures and mice to show that...

Tumors Continue Growing Even When Cells Get Old

Based on the knowledge that cancer cells grow indefinitely, the general belief is that senescence could act as a barrier againsttumor growth and has the potential of being used as a cancer treatment. According to findings published in the 19th January issue of the open-access journal PLoS Computational Biology, a collaboration between a cancer biologist from the University of Milano, Italy, and two physicists, from the National Research Council of Italy and from Cornell University, has shown that although cell senescence occurs spontaneously in melanoma cells, it does not stop their growth, which is sustained by a small population of cancer stem cells. The study examines the association between melanoma and senescence, which is the normal process in which cells decline and eventually stop duplicating after reaching maturity. The researchers observed the long-term evolution of melanoma cell populations by monitoring the number of senescent cells, and discovered a slowing in growth with the majority of the cells turning senescent after three months. However, growth did not stop and was eventually resumed at its initial rate until the senescent cells had nearly disappeared. The researchers applied a mathematical model of the experimental data using the cancer stem cell hypothesis, in which a sub-group of cancer cells multiply indefinitely, and therefore remain unaffected by senescence. These cancer stem cells produce a larger population of cancer cells, which are only able to replicate a certain number of times. The results of the model achieved an indirect confirmation that cancer stem cells are present in melanoma, an issue that remains to be controversial in the cancer research community. The researchers conclude that even though a large percentage of cancer cells...
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