“Communication problems in the brain - Science Centric” plus 1 more

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Communication problems in the brain - Science Centric Posted: 21 Jan 2010 10:10 AM PST For brain cells to communicate, the contacts to each other must function. The protein molecule neuroligin-1 plays an important role in this as it stimulates the necessary maturation processes at the contact sites (synapses) of the nerves. A synaptic maturation disorder is possibly involved in the development of autism. Dr Thomas Dresbach and his team from the Institute for Anatomy and Cell Biology at the University of Heidelberg, in cooperation with the study group led by Professor Dr Thomas Kuner at the same institute and Professor Dr Nils Brose, Max Planck Institute for Experimental Medicine in Goettingen, have published their results in the prestigious international journal PNAS (Proceedings of the National Academy of Sciences). One hundred billion nerve cells make our brain a thinking machine. Each of these nerve fibres produces a long extension, the axon, which terminates in numerous small knobs. Transmitters are released here that transfer information to the next nerve cell. The contact site between nerve ending and adjacent nerve cell is called a synapse. The number and location of active synapses determine which areas of the brain are especially active at a given time. The synapses of young nerve cells must mature before they can release their neurotransmitters to the full extent. Researchers were able to show using genetically modified nerve cells from mice that the postsynaptic nerve cell, the receptor, must form a sufficient amount of a certain protein molecule, neuroligin-1, to allow this maturation process to take place. In addition, the nerve endings from where information is sent must release slight amounts of neurotransmitters to stimulate the neuroligin in the postsynaptic nerve cell. 'A fully functioning contact can develop only if both sides, transmitter and receptor of information, are involved in the maturation process,' explained Dr Dresbach. If no neuroligin-1 is formed, the nerve endings remain at an immature stage and release fewer neurotransmitters; the flow of information is interrupted. The nerve endings can only whisper, so to speak. 'The results are significant for actual concepts about how autism develops,' says Professor Dr Joachim Kirsch, director of the Institute for Anatomy and Cell Biology. Symptoms of autism are first noticed in early childhood as an information processing disorder. The symptoms may be more or less pronounced, but all patients display weaknesses in social contacts and communication. 'There are many indications that malfunctions of synaptic molecules are involved in the development of this illness. It has thus far been unclear exactly what these malfunctions are, but we now know what to look for,' says Professor Kirsch. The study was funded by the FRONTIER program of the excellence initiative at the University of Heidelberg. Source: University Hospital Heidelberg Five Filters featured article: Chilcot Inquiry. Available tools: PDF Newspaper, Full Text RSS, Term Extraction.

Gene study puts men on fast track with the Y factor - Washington Times Posted: 18 Jan 2010 10:56 AM PST By Seth Borenstein ASSOCIATED PRESS Women may think of men as primitive, but new research indicates that the Y chromosome — the thing that makes a man male — is evolving far faster than the rest of the human genetic code. A new study comparing the Y chromosomes from humans and chimpanzees, our nearest living relatives, show they are about 30 percent different. That is far greater than the 2 percent difference between the rest of the human genetic code and that of the chimp's, according to a study released in the journal Nature. These changes occurred in the last 6 million years or so, relatively recently when it comes to evolution. "The Y chromosome appears to be the most rapidly evolving of the human chromosomes," said study co-author Dr. David Page, director of the prestigious Whitehead Institute in Cambridge, Mass., and a professor of biology at MIT. "It's an almost ongoing churning of gene reconstruction. It's like a house that's constantly being rebuilt." Before men get too impressed with themselves, lead author Jennifer Hughes offers some words of caution: Just because the Y chromosome, which determines gender, is evolving at a speedy rate doesn't necessarily mean men themselves are more evolved. Researchers took the most detailed examination of the Y chromosome, which females do not have, of both humans and chimps and found entire sections dramatically different. There were even entire genes on the human Y chromosome that weren't on the chimp, said Ms. Hughes, also of the Whitehead Institute. The two-year research took twice as long as expected because of the evolutionary changes found, she added. There is a bit of a proviso to the comparison with other chromosomes. While all human and chimp chromosomes have been mapped, only two chimp chromosomes have been examined in great detail: Y and chromosome 21. Yet, there's still enough known to make the claim that the Y is the speediest evolver, the researchers said. Until recently, the Y chromosome was considered the no-respect Rodney Dangerfield of genetics, especially because it had fewer genes than other chromosomes. A few years ago, some researchers even suggested that the Y chromosome was shrinking so that in 50,000 years it would just disappear — and so would men. "The story is not as cut and dried as many would have liked to predict," Ms. Hughes said. "It's kind of fun to say that men are going to die out, but the science is proving — now that we've got data — that that's not true at all." Mr. Page agreed. "The Y chromosome has many more tricks up its sleeve than it was given credit for," he said. There are a couple of reasons the two researchers cite for the Y chromosome being such an evolutionary powerhouse. One is that it stands alone and isn't part of a pair, like 44 other chromosomes. So when there are mutations, there's no matching chromosome to recombine and essentially cover up the change, Ms. Hughes said. Because women have two X chromosomes, the X chromosome is not in the same evolutionary boat. Another reason has to do with the nature of mating. When female chimps are in heat, they mate frequently and with many partners, so there is evolutionary pressure on the male to produce the most and best sperm to propagate his genes, Mr. Page said. To test this out, Ms. Hughes said she hopes to soon examine the Y chromosomes of a rhesus macaque, which is fairly promiscuous, and the marmoset, which is more monogamous than early humans probably were. Outside scientists praised the study. R. Scott Hawley, a genetics researcher at the Stowers Institute in Kansas City, Mo., called the result "astounding." "The Y chromosome clearly has the strength and tenacity to fight back," said Mr. Hawley, who was not part of the research. "I certainly think the Y chromosome has taken a bad rap for a long time with people doing maps showing areas for channel surfing." Five Filters featured article: Chilcot Inquiry. Available tools: PDF Newspaper, Full Text RSS, Term Extraction.

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