Genetics & Molecular Biology

The enzyme calcineurin is critical to normal development and function of heart cells, and loss of the protein leads to heart problems and death in genetically modified mice, according to researchers at Cincinnati Children's Hospital Medical Center

Their new study, published in the Journal of Biological Chemistry, demonstrates that calcineurin in hearts of mice is directly linked to proper cardiac muscle contraction, rhythm and maintenance of heart activity. The near total absence of calcineurin in mice leads to heart arrhythmia, failure and death, according to the research team.
Writing in Cell, a team of biologists say they have unraveled the biochemistry of how bacteria so precisely time cell division, a key element in understanding how all organisms from bacteria to humans use their biological clocks to control basic cellular functions. The discovery provides important clues to how the biological clocks of bacteria and other "prokaryotic" cells—which lack cell nuclei—evolved differently from that of "eukaryotic" cells with nuclei that comprise most other forms of life, from fungi to plants and animals.
A recent study in the American Journal of Human Genetics has revealed how human genes interact with their environment to boost disease risk. The authors say the findings shed light on why the search for specific gene variants linked to human diseases can only partly explain common disorders.
Scientists have known that newly acquired, short-term memories are often fleeting, but a new study of Drosophila in Cell suggests that there is a good reason for that kind of forgetfulness. An active process of erasing memories may be as important as the ability to lay down new memories.

"Learning activates the biochemical formation of memory," says Yi Zhong of Tsinghua University and Cold Spring Harbor Laboratory. "But you need to remove memories for new information to come in. We've found that forgetting is an active process to remove memory."
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.