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Archive - Jan 31, 2014

Tau-Induced Neurodegeneration Associated with Global Relaxation of Tightly-Wound DNA in Alzheimer’s Disease

In a study published online on January 26, 2014 in Nature Neuroscience, Bess Frost, Ph.D., from the Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, and co-authors, identify abnormal expression of genes, resulting from DNA relaxation, that can be detected in the brain and blood of Alzheimer's patients. The protein tau (image) is involved in a number of neurodegenerative disorders, including Alzheimer's disease. Previous studies have implicated DNA damage as a cause of neuron, or cell, death in Alzheimer's patients. Given that DNA damage can change the structure of DNA within cells, the researchers examined changes in DNA structure in tau-induced neurodegeneration. They used transgenic flies and mice expressing human tau to show that DNA is more relaxed in tauopathy. They then identified that the relaxation of tightly wound DNA and resulting abnormal gene expression are central events that cause neurons to die in Alzheimer's disease. The authors write, "Our work suggests that drugs that modify DNA structure may be beneficial for treating Alzheimer's Disease." The authors recommend, "A greater understanding of the pathway of DNA relaxation in tauopathies will allow us to identify the optimal target and explore the therapeutic potential of epigenetic-based drugs." The title of their article is, “Tau Promotes Neurodegeneration through Global Chromatin Relaxation.” [Press release] [Nature Neuroscience abstract]

Single Gene in Honeybees Influences Pollen-Basket Formation on Workers’ Hind Legs

A research team led by scientists from Wayne State University in Detroit, in collaboration with scientists from Michigan State University (MSU), has identified a single gene in honeybees that separates the queens from the workers. The scientists unraveled the gene's inner workings and published the results in the January 2014 issue of Biology Letters. The gene, which is responsible for leg and wing development, plays a crucial role in the evolution of bees' ability to carry pollen. "The gene — Ultrabithorax, or Ubx — is responsible for making hind legs different from fore legs so they can carry pollen" said Dr. Aleksandar Popadic, associate professor of biological sciences in Wayne State University's College of Liberal Arts and Science and principal investigator of the study. "In some groups, like crickets, Ubx is responsible for creating a 'jumping' hind leg. In others, such as bees, it makes a pollen basket — a 'naked,' bristle-free leg region that creates a space for packing pollen." "Other studies have shed some light on this gene's role in this realm, but our team examined in great detail how the modifications take place," added Dr. Zachary Huang, an MSU entomologist. Ubx represses the development of bristles on bees' hind legs, creating a smooth surface that can be used for packing pollen. This important discovery can be used as a foray into more commercial studies focused on providing means to enhance a bee's pollination ability – the bigger the pollen basket, the more pollen that can be packed in it and transported back to the hive. While workers have these distinct features, queens do not. The team confirmed this by isolating and silencing Ubx. This made the pollen baskets completely disappear, altered the growth of the pollen comb, and reduced the size of the pollen press.

Centrosome-Related Signaling Problem Can Cause Autosomal Recessive Primary Microcephaly

Professor Erich Nigg and his research group at the Biozentrum of the University of Basel in Switzerland have discovered an amino acid signal essential for error-free cell division. This signal regulates the number of centrosomes in the cell, and its absence results in the development of pathologically altered cells. Remarkably, such altered cells are found in people with a neurodevelopmental disorder called autosomal recessive primary microcephaly. The results of these investigations have been published online on January 30, 2014 in Current Biology. Cell division is the basis of all life. Of central importance is the error-free segregation of genetic material, the chromosomes. A flawless division process is a prerequisite for the development of healthy, new cells, whilst errors in cell division can cause illnesses such as cancer. The centrosome, a tiny cell organelle, plays a decisive role in this process. Professor Nigg’s research group at the Biozentrum of the University of Basel has investigated an important step in cell division: the duplication of the centrosome and its role in the correct segregation of the chromosomes into two daughter cells. The protein STIL has an essential function in this process. It ensures that centrosome duplicate before one half of the genetic material is transported into each of the two daughter cells. During cell division, the protein STIL is degraded. If this does not occur, the protein accumulates in the cell, which then causes an overproduction of centrosomes. As a consequence, mis-segregated chromosomes are incorporated into the daughter cells, which then represent cells with faulty genetic material.

Gastric Bypass and Mysterious Recovery from Type 2 Diabetes

The majority of gastric bypass patients mysteriously recover from their type 2 diabetes within days, before any weight loss has taken place. A study at Lund University Diabetes Centre in Sweden has now shown that the insulin-producing beta cells increase in number and performance after the surgery. "We have suspected this for a while, but there have not previously been any models to prove it," says Dr Nils Wierup, who led the research. The small study involved gastric bypass surgery on just four pigs, but is the only study of its kind and therefore unique. The results confirm that neither weight loss nor reduced food intake are required in order for the procedure to raise the number of beta cells, as the pigs had identical body weight and ate exactly the same amount of food. Type 2 diabetes develops when the body's insulin-producing beta cells stop working, or when the body is not able to use the insulin that the cells produce. The majority of people who suffer from obesity and undergo a gastric bypass operation recover from their diabetes within days of the procedure. The operation involves altering the connection between the stomach and the intestines so that food bypasses the stomach and parts of the small intestine and instead goes straight into the small intestine. Until now, it has been a mystery why patients' blood sugar levels normalize. The group at Lund University Diabetes Centre found that the pigs' beta cells improve their insulin secretion. The researchers also studied tissue from the pigs' pancreas, the organ where the beta cells are located, something that is almost impossible to do in humans. They found that the number of beta cells increased after the operation. The group have previously studied the effects of gastric bypass on humans.

Wolves Are Better Imitators of Conspecifics Than Dogs, Learning More Effectively

Although wolves and dogs are closely related, they show some striking differences. Scientists from the Messerli Research Institute at the University of Veterinary Medicine, Vienna have undertaken experiments that suggest that wolves observe one another more closely than dogs and so are better at learning from one another. The scientists believe that cooperation among wolves is the basis of the understanding between dogs and humans. Their findings have been published online on January 29, 2014 in an open-access article in PLOS ONE. Wolves were domesticated more than 15,000 years ago and it is widely assumed that the ability of domestic dogs to form close relationships with humans stems from changes during the domestication process. But the effects of domestication on the interactions between the animals have not received much attention. The point has been addressed by Dr. Friederike Range and Dr. Zsófia Virányi, two members of the University of Veterinary Medicine, Vienna (Vetmeduni Vienna) who work at the Wolf Science Center (WSC) in Ernstbrunn, Niederösterreich. The scientists found that wolves are considerably better than dogs at opening a container, providing they have previously watched another animal do so. Their study involved 14 wolves and 15 mongrel dogs, all about six months old, hand-reared and kept in packs. Each animal was allowed to observe one of two situations in which a trained dog opened a wooden box, either with its mouth or with its paw, to gain access to a food reward. Surprisingly, all of the wolves managed to open the box after watching a dog solve the puzzle, while only four of the dogs managed to do so. Wolves more frequently opened the box using the method they had observed, whereas the dogs appeared to choose randomly whether to use their mouth or their paw.