Genetics & Molecular Biology
Bell curves are everywhere. Pick 100 random people and measure them: measure their height, their weight, their blood pressure, their time to run a mile, or to sprint 50 yards, and their IQ, and you find that most of us fall in the middle of the spectrum, while there are always some people on either extreme. Why?
The puzzle grows deeper when you think about genetics. If a trait like height is controlled largely by genes, how is it that height falls into a bell-curve pattern? Bell-curves seem completely at odds with what we learn about the discrete genetics of Mendel's round and wrinkled peas in high school biology.
It turns out that the solution to this puzzle is fairly simple (although the details get messy). In fact, Darwin's cousin hit on the right answer (long before he or anyone else knew about Mendel's genetics), with what he called the "Supreme Law of Unreason": a bell curve is exactly what you expect when you toss together "a large sample of chaotic elements." In other words, genetics is like one big game of The Price Is Right.
I have always held a fascination for transposons
, or jumping genes as they are sometimes called. Part of this interest may be due to my background in Drosophila
genetics, where a transposon
called a P element
has been used extensively for genetic manipulation of flies for years.
It makes sense that ecological changes caused by humans affect natural biodiversity and, in some cases, can even cause permanent displacement of a species.
Unless science revives it.
Researchers from Eawag and from two German universities (Frankfurt and Konstanz), analyzed genetic material from Daphnia eggs up to 100 years old and say the eutrophication of Greifensee and Lake Constance in the 1970s and 1980s led to genetic changes in a species of water flea which was ultimately displaced. Despite the fact that water quality has since been significantly improved, this species has not been re-established. Naturally, anyway.Daphnia Galeata. Photo: Eaweg University
Polymorphisms are variations in genes which can result in changes in the way a particular gene functions and thus may be associated with susceptibility to common diseases.
In a new study in Psychological Science, psychologist Tina B. Lonsdorf and her colleagues from the Karolinska Institutet in Sweden and the University of Greifswald in Germany examined the effect of specific polymorphisms on how fear is learned and how that fear is subsequently overcome.
You might think that predicting eye color is easy because we all learned in high school about recessive genes and eye color is a great example of those. But it isn't easy. In fact, human eye color, which is determined by the extent and type of pigmentation on the eye's iris, is what geneticists call a 'complex trait, meaning that several genes control which color the eyes will ultimately have. Over the past decades a number of such 'eye-color genes' have been identified, and people with different eye color, will have a different DNA sequence at certain points in these genes.
Researchers have discovered that a long-defunct gene was resurrected during the course of human evolution. This is believed to be the first evidence of a doomed gene – infection-fighting human IRGM – making a comeback in the human/great ape lineage.
The truncated IRGM gene is one of only two genes of its type remaining in humans. The genes are Immune-Related GTPases, a kind of gene that helps mammals resist germs like tuberculosis and salmonella that try to invade cells. Unlike humans, most other mammals have several genes of this type. Mice, for example, have 21 Immune-Related GTPases. Medical interest in this gene ignited recently, when scientists associated specific IRGM mutations with the risk of Crohn's disease, an inflammatory digestive disorder.
Recently, The Frogger and I were watching X-Men: The Last Stand
(aka X-Men 3: Mutants Doing Ridiculous Wire-Work Stunts
), which should get you thinking about what mutant powers you would like to have. Unfortunately, I'd already thought this through in some detail (control of gravity, take a minute to think through the relativistic implications and tremble Homo sapiens
). So, I had time to ponder grander thoughts, like how the hell do they get those mutant powers? Actua
A female moth selects a mate based on the scent of his pheromones. An analysis of the pheromones used by the European Corn Borer (ECB, Ostrinia nubilalis) shows that females can discern a male's ancestry, age and possibly reproductive fitness from the chemical cocktail he exudes.
Jean-Marc Lassance and Christer Löfstedt from Lund University, Sweden, studied the influence of pheromones on mating preferences and carried out an analysis of the composition of the scent and genetic makeup of the animals involved. In addition, they compared the odor bouquet used by males with the scent used by females to attract potential mates.
Women can take pride that they are more efficient than men in many ways, including one that is not so great; storing fat.
It's a paradox women have discussed for generations – their apparent ability to store fat more efficiently than men, despite eating proportionally fewer calories. While it has long been suspected that female sex hormones are responsible, a University of New South Wales (UNSW) research review has for the first time drawn a link between one hormone – estrogen – and its impact on fat storage for childbearing.
Teams of scientists from Australia and the United States have used yeast and mammalian cells to discover a connection between genetic and environmental causes of Parkinson's disease.
Yeasts are single cell organisms, used widely in biological research because their structure resembles that of cells found in animals and humans. Yeasts share many genes, or their functional equivalents, with humans and offer the ability to screen or test thousands of genes and analysing their effects.