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Archive - Jan 2014

January 3rd

Dogs Sense Small Variations in the Earth’s Magnetic Field

Researchers analyzed the body orientation of 70 dogs of different breeds, while the dogs relieved themselves in the open country and without being on the leash. The statistical analyses of the more than 7,000 observations (recorded together with the currently prevailing environmental conditions of the location, time of day, and other important parameters such as the familiarity of the terrain for each dog) was frustrating. In contrast to grazing cows, hunting foxes, and landing waterfowl (previous studies of the research collective), the dogs showed no clear preference for a particular body alignment while doing number one or number two. But then the researchers around Dr. Vlastimil Hart and Prof. Dr. Hynek Burda made a striking discovery. They sorted the collected data according to the small variations of the geomagnetic field during the period of data collection. These irregular, tiny changes in the intensity and declination of the magnetic field lines are recorded by magnetic observatories and freely accessible online. The emerging picture of the analysis of the categorized data is as clear as it is astounding: dogs prefer a body-alignment along the magnetic north-south axis, but only during periods of calm magnetic field conditions. After taking into account all other factors, the researchers concluded that with this discovery they provide clear indication of a magnetic sense in our four-legged friends. To many dog owners who know about the good navigation abilities of their protégés, the findings might not come as a surprise – but rather as an explanation for the "supernatural" abilities, although it is not clear to the researchers what the dogs might use their magnetic sense for.

Japanese Team Shows Jumping DNA in the Brain May Be a Cause of Schizophrenia

Stretches of DNA called retrotransposons, often dubbed “junk DNA,” might play an important role in schizophrenia. In a study published online on January 2, 2013 in the journal Neuron, a Japanese team revealed that LINE-1 retrotransposons are abnormally abundant in the schizophrenia brain, modify the expression of genes related to schizophrenia during brain development, and may be one of the causes of schizophrenia. Retrotransposons are short sequences of DNA that autonomously amplify and move around the genome. One class of retrotransposons named Long Interspersed Nuclear Elements (LINEs) make up a large part of the eukaryotic genome and it is believed that they may contribute to a number of disorders and diseases, such as cancer. LINE-1 retrotranspons have been shown to be more abundant in brain cells than in other cells in the body in adults, providing evidence for enhanced activity of LINE-1s in the human brain. However, the role played by LINE-1s in mental disorders, and in particular schizophrenia, has remained unclear. The team led by Dr. Kazuya Iwamoto from the University of Tokyo and Dr. Tadafumi Kato from the RIKEN Brain Science Institute demonstrated that the number of LINE-1 copies is elevated in the post-mortem brains of patients with schizophrenia. They show, using mouse and macaque models for schizophrenia and induced pluripotent stem (iPS) cells, that exposure to environmental risk factors during development, as well as the presence of genetic risk factors for schizophrenia, can lead to increased levels of LINE-1 copies in neurons. Employing whole genome analysis, the authors reveal that in schizophrenia patients LINE-1 reinserts into genes involved in synaptic function or schizophrenia and may result in disruptions in their normal functions.

Scientists Uncover Most Detailed Picture Yet of Muscular Dystrophy Defect, Then Design Targeted New Drug Candidates

Scientists from The Scripps Research Institute (TRSI) have revealed an atomic-level view of a genetic defect that causes a form of muscular dystrophy, myotonic dystrophy type 2, and have used this information to design drug candidates with potential to counter those defects—and reverse the disease. “This the first time the structure of the RNA defect that causes this disease has been determined,” said TSRI Associate Professor Matthew Disney, who led the study. “Based on these results, we designed compounds that, even in small amounts, significantly improve disease-associated defects in treated cells.” Myotonic dystrophy type 2 is a relatively rare form of muscular dystrophy that is somewhat milder than myotonic dystrophy type 1, the most common adult-onset form of the disease. Both types of myotonic dystrophy are inherited disorders that involve progressive muscle wasting and weakness, and both are caused by a type of genetic defect known as an “RNA repeat expansion,” a series of nucleotides repeated more times than normal in an individual’s genetic code. The repeat binds to the protein MBNL1, rendering it inactive and resulting in RNA splicing abnormalities—which lead to the disease. Many other researchers had tried to find the atomic-level structure of the myotonic dystrophy 2 repeat, but had run into technical difficulties. In a technique called X-ray crystallography, which is used to find detailed structural information, scientists manipulate a molecule so that a crystal forms. This crystal is then placed in a beam of X-rays, which diffract when they strike the atoms in the crystal. Based on the pattern of diffraction, scientists can then reconstruct the shape of the original molecule.

January 2nd

Pacific Plant Has Absorbed Six “Foreign” Genomes into Its Mitochondria

Amborella trichopoda, a sprawling shrub that grows on just a single island in the remote South Pacific, is the only plant in its family and genus. It is also one of the oldest flowering plants, having branched off from others about 200 million years ago. Now, researchers from Indiana University, with the U.S. Department of Energy Joint Genome Institute (DOE JGI), Penn State University, and the Institute of Research for Development in New Caledonia, have determined a remarkable expansion of the genome of the plant's critical energy-generating structures. Its mitochondria, the plant's energy-producing organelles, in an epic demonstration of horizontal gene transfer, have acquired six genome equivalents of foreign DNA -- one from a moss, three from green algae, and two from other flowering plants. It is the first time that an organelle has captured entire "foreign" genomes, those from other organisms, and the first description of a land plant acquiring genes from green algae. "It swallowed whole genomes from other plants and algae as well as retained them in remarkably whole forms for eons," said Indiana's Dr. Palmer, the senior author of the findings published December 20, 2013 in the journal Science. This work reports on the extent of Amborella's genomic gluttony. The work n the mitochondrial genome is accompanied by a report of the Amborella trichopooda nuclear genome by the Amborella Genome Project, the establishment of a high-quality Amborella trichopoda genome sequence by another group, and a Perspective piece linking the reports together. The DOE JGI Plant Program focuses on fundamental biology of photosynthesis, the conversion of solar to chemical energy, and the role of terrestrial plants and oceanic phytoplankton in global carbon cycling.

More Evidence Suggests Type 2 Diabetes Is an Inflammatory Disease

As people's waistlines increase, so does the incidence of type 2 diabetes. Now scientists have a better understanding of exactly what happens in the body that leads up to type 2 diabetes, and what likely causes some of the complications related to the disease. Specifically, scientists from Denmark have found that in mice, macrophages (see image of isolated macrophage), a specific type of immune cell, invade the diabetic pancreatic tissue during the early stages of the disease. Then, these inflammatory cells produce a large amount of pro-inflammatory proteins, called cytokines, which directly contribute to the elimination of insulin-producing beta cells in the pancreas, resulting in diabetes. This discovery was published in the January 2014 issue of the Journal of Leukocyte Biology. "The study may provide novel insights allowing development of tailor-made anti-inflammatory based therapies reducing the burden of type 2 patients," said Alexander Rosendahl, Ph.D., a researcher involved in the work from the Department of Diabetes Complication Biology at Novo Nordisk A/S, in Malov, Denmark. "These novel treatments may prove to complement existing therapies such as insulin and GLP-1 analogues." To make their discovery scientists compared obese mice that spontaneously developed diabetes to healthy mice. The mice were followed from a young age when the obese mice only showed early diabetes, to an age where they displayed systemic complication in multiple organs. Presence of macrophages around the beta cells in the pancreas and in the spleen was evaluated by state-of-the-art flow cytometric technology allowing evaluation on a single cell level. At both the early and late stages, the diabetic mice showed significant modulations compared to healthy mice.

December 31st

Molecular Evolution of Genetic Sex-Determination Switch in Honey Bees

It's taken nearly 200 years, but scientists in Arizona and Europe have finally teased out how the molecular switch for sex gradually and adaptively evolved in the honey bee. The first genetic mechanism for sex determination was proposed in the mid-1800s by a Silesian monk named Johann Dzierson, according to the study's co-author and Arizona State University (ASU) Provost Robert E. Page Jr. Dzierson was trying to understand how males and females were produced in honey bee colonies. He knew that the difference between queen and worker bees – both females – emerged from the different quality and quantity of food. But, what about the males, he asked. Dzierson posited that males were haploid – possessing one set of chromosomes, which was confirmed in the 1900s with the advent of the microscope. Under the magnifying lens, researchers could see that eggs that gave rise to drones were not penetrated by sperm. However, how this system of haplodiploid sex determination ultimately evolved at a molecular level has remained one of the most important questions in developmental genetics. In the December 5, 2013 issue of Current Biology, Dr. Page and Dr. Martin Beye, lead author and professor with the Institute of Evolutionary Genetics in the University of Duesseldorf, Germany, and their collaborators laid out the final pieces of how these systems evolved in their article "Gradual molecular evolution of a sex determination switch in honey bees through incomplete penetrance of femaleness." The authors studied 14 natural sequence variants of the complementary sex determining switch (csd gene), for 76 genotypes of honey bees. While complex, the researchers had several tools at hand that their predecessors lacked to solve this sexual determination puzzle.