Genetics & Molecular Biology

Prions first made their notorious media debut in the mid-1980’s when British cattle contracted Mad Cow disease. As a result, over 150 people in Europe were infected and died from the human form known as Creutzfeldt-Jakob disease—a fatal neurological disorder with similar symptoms as Mad Cow.

Although prions are infectious agents with a bad reputation, research suggests that prions also play a role in epigenetic regulation.  Recently, a Nature Cell Biology study conducted by molecular biologists at the University of Illinois at Chicago, discovered a new prion in yeast that raises further questions about the biological role of prions in gene regulation.
Insects such as honeybees and bumble bees are predictable in the way they move among flowers, typically moving directly from one flower to an adjacent cluster of flowers in the same row of plants. The bees' flight paths have a direct affect on their ability to hunt for pollen and generate "gene flow", fertilization and seed production that results when pollen moves from one plant to another. The study of gene flow has experienced more attention in part due to the recent introduction of genetically modified organisms (GMOs) into the environment.

We’re all aware of the severe genetic and unpleasant physical consequences that result from reproducing with a closely related relative.  Aside from unfortunate aesthetics, inbreeding can also lead to the extinction of small organismal populations.  This decrease of reproductive success is referred to as “inbreeding depression” and mechanisms that cause it are still being debated by biologists. 


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.
Mystique from X-MenRecently, 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