Genetics & Molecular Biology

Biologists have struggled for many years to explain how it is possible that some people who carry a mutated gene don't express the trait or condition associated with the mutation. This common but poorly understood phenomenon, known as incomplete penetrance,  may be partially due to environmental factors and the influence of other genes, but scientists say other forces are likely at work here as well.

The authors of a new study in Nature say that some cases of incomplete penetrance may be controlled by random fluctuations in gene expression.

In a study of intestinal development of C. elegans, a small worm, the team was able to pinpoint specific fluctuations that appear to determine whether the mutant trait is expressed or not.
DNA analysis of royal mummies suggest that malaria and bone abnormalities may have contributed to the death of Egyptian pharaoh King Tutankhamun, with other results appearing to identify members of the royal family, including King Tut’s father and mother, according to a new study published in the Journal of The American Medical Association. The findings may lead to a new way of researching the molecular genealogy and pathogen paleogenomics of the Pharaonic era, perhaps even a new field called 'molecular Egyptology.'
Research published simultaneously in PNAS and Nature details how scientists have successfully transplanted most of the "nose" of the mosquito that spreads malaria into frog eggs and fruit flies and are employing these surrogates to combat the spread of the deadly disease that afflicts 500 million people worldwide. The mosquito's "nose" is centered in its antennae, which are filled with nerve cells covered with special "odorant receptors" that react to different chemical compounds. The insect ORs are comparable to analogous receptors in the human nose and taste buds on the tongue.
Human cells contain 46 strands of DNA that code for all our genes. Certain chemicals and UV light can break these strands into pieces, a process that typically leads to cell death or diseases such as cancer if the damage is not repaired quickly. But new research, published in PNAS, shows for the first time that stem cells will intentionally cut and then repair their own DNA as a mechanism of activating genes that promote the development of new tissues.

The discovery could help researchers develop better ways to activate stem cells, so that they can produce new tissues for therapeutic purposes. It also suggests that DNA mutations, which can contribute to a variety of diseases, may initially occur as a result of a normal cellular process.
Researchers from the University of Illinois say they know how to exploit an unusual chemical reaction mechanism that allows malaria parasites and many disease-causing bacteria to survive. The findings, detailed in PNAS, could eventually lead to new anti-malarial and antibacterial drugs.

The new study focused on an essential chemical pathway that occurs in malaria parasites and in most bacteria but not in humans or other animals, making it an ideal drug target. Several teams of researchers have spent nearly a decade trying to understand an important player in this cascade of chemical reactions, an enzyme known as IspH. This enzyme promotes the synthesis of a class of compounds, called isoprenoids, which are essential to life.
Previously unrelated disorders which all cause complex defects in brain development and function are linked by a common underlying mechanism. Rett syndrome (RTT), Cornelia de Lange syndrome (CdLS), Alpha-Thalassemia mental Retardation, and X-linked syndrome (ATR-X) have each been linked with distinct abnormalities in chromatin, the spools of proteins and DNA that make up chromosomes and control how genetic information is read in a cell.

The new research, appearing in Developmental Cell, helps to explain why these different chromatin abnormalities all interfere with proper gene expression patterns necessary for normal development and mature brain function.
When asked to justify the research I do, I always struggle a little to explain my dissatisfaction with the traditional descriptive, non-quantitative explanations of molecular biological systems. As a glance at a classic molecular cell biology textbook will easily demonstrate, molecular biologists have been tremendously successful with verbal or semi-quantitative explanations of what goes on inside the cell. And in any case, the complexity of the cell is extremely daunting for the would-be theoretical biologist.
Researchers from the University of California, San Diego have discovered the origin of strains of the human immunodeficiency virus (HIV) among men who have sex with men. The team says the results are important because knowing the mechanisms by which HIV uses human sex to spread is essential to stopping the HIV epidemic.

It is known that most HIV infections worldwide result from exposure to the HIV virus in semen, made up of seminal cells and the fluid around these calls, called seminal plasma. HIV virus particles contain RNA and exist in the plasma, while infected seminal cells contain HIV DNA.
Arizona State University researchers have developed the first versatile DNA reader that can discriminate between DNA's four core chemical components, the key to unlocking the vital code behind human heredity and health. If the process can be perfected, DNA sequencing could be performed much faster than current technology, and at a fraction of the cost.
There is an apocryphal story about a graduate mathematics student at the University of Virginia studying the properties of certain mathematical objects. In his fifth year some killjoy bastard elsewhere published a paper proving that there are no such mathematical objects. He dropped out of the program, and I never did hear where he is today. He's probably making my cappuccino right now.