machinery
Infinitesimal particles of gold have enabled neurobiologists to track down key molecules in the machinery of ''entry points'' in neurons -- offering clues to the organization of a region that has thus far remained largely unknown neuronal territory. The researchers used electron microscopy to locate molecules tagged with targeted antibodies attached to gold particles -- rendering the molecules' precise location visible.
The flinch is a critically important protective mechanism by which animals and humans instantly protect themselves against threats ranging from an attacking predator to an incoming golf ball. Researchers have shed new light on the neural machinery that controls flinching by dialing the response up or down using drugs. Their studies concentrated on a region of the motor cortex they have dubbed the polysensory zone, which previous study had shown could be induced to trigger flinching by electrical stimulation.
Up to 95 percent of a person's DNA is believed to be junk DNA. In order to prevent these relics of evolution from rearranging chromosomes and causing disease, natural mechanisms exist to silence them, according to contemporary theories of chromosome biology. The RNA silencing machinery silences gene expression, by destroying RNA, a molecule that carries out DNA's instructions. Two years ago, components of the RNA silencing machinery were shown to be absolutely required for forming heterochromatin, a chromatin state that silences DNA, suggesting a new rule in biology. But researchers from Texas A&M University and the University of Oregon disagree.
A butterfly's wing is a uniquely visual exhibition, not only of the aesthetics of nature, but of the machinery of evolution. Biologists have long appreciated that butterfly wing patterns dramatically exemplify the intricate interplay between genes and the environment -- as the patterns evolve to give butterflies advantages in evading predators and attracting mates.
Two papers in the July 8, 2004, issue of Neuron shed light on how a mutant form of a normally protective protein in the cells of sufferers of amyotrophic lateral sclerosis targets the ''power plants'' of motor neurons, killing the neurons and ultimately resulting in paralysis and death. The culprit is a mutant form of the enzyme superoxide dismutase (SOD1), which normally protects cells from harmful reactive oxygen species. However, about 3% of people with ALS have a mutant form of the enzyme.
Lasers, already used for everything from price scanning at the supermarket to eye surgery, now are likely to dramatically change the construction, large-scale manufacturing, remote sensing and defense industries. A new National Institute of Standards and Technology (NIST) report* predicts ''tremendous'' applications for laser scanning devices, also known as LADARs (for Laser Detection and Ranging) and argues for a vigorous effort to create next-generation LADAR---a coffee-cup-size device with millimeter accuracy. The results, says study director William C. Stone, ''could be comparable to the advances achieved when computers were first matched with machinery.''
Researchers have produced vast libraries of short segments of ribonucleic acid (RNA) that can be used to turn off individual human and mouse genes to study their function. The libraries will be made widely available to laboratories studying human biology and disease. The researchers are optimistic that the libraries will become a powerful research tool for gene analysis and discovery.
A subtle structural change that may play a role in the molecular machinery for making HIV-1 (the virus that causes AIDS) has been identified by scientists. If confirmed in living cells, the mechanism might provide a new target for antiviral drugs. The finding is among several to emerge recently from efforts to develop and validate sensitive tools for rapidly detecting and quantifying ribonucleic acid (RNA) interactions. RNA provides the genetic blueprint for retroviruses such as HIV-1. Scientists created a model system for tracking changes in an RNA structural element involved in forming HIV-1 viral particles.
Mayo Clinic researchers have identified a naturally occurring "good guy" for patients infected with HIV. It is a helpful gene mutation that impairs the HIV virus' cell-killing machinery, thus preserving immune system function. Moreover, Mayo's experiments in mice suggest that the presence or absence of this mutation in the gene known as Vpr may play a central role in determining which HIV-infected patients develop full-blown, fatal AIDS.
A protein defective in two types of muscular dystrophy also appears to be important in repairing damaged muscle, according to Howard Hughes Medical Institute researchers at the University of Iowa College of Medicine. The discovery reveals the first known component of the machinery that repairs the damaged membrane in a muscle fiber. Further studies of this and related proteins could lead to a better understanding of disorders that affect cardiac and skeletal muscles.
Yards of DNA are packed into cells by wrapping the DNA around proteins called nucleosomes. But that tight packing makes it hard for the cell's machinery to get at the DNA code to read, copy or repair it. Now researchers at the University of California, Davis, have shown how two proteins form a molecular machine that shuffles the nucleosomes out of the way to expose the DNA double helix.
Using a laser beam scalpel so fine it could inscribe words on the surface of a fly egg, researchers have snipped their way to a new understanding of a key process in a fruit fly's embryonic development. The process, called dorsal closure, is the complex mechanism by which the embryonic skin of the fruit fly Drosophila knits itself together to protect its innards from the outside world. Understanding this seemingly arcane process is important because dorsal closure uses molecular and cellular mechanisms very similar to those involved in wound-healing as well as those that can go awry in humans to produce the spinal malformation spina bifida.
Most of the time, most of the estimated 35,000 genes in the human genome are silent, securely stored away in the tightly coiled structure of chromatin, which makes up chromosomes. Inside chromatin, the DNA is wound around small proteins called histones, making it unavailable to the cellular machinery that would otherwise read its coded genetic information. Specific cell and tissue types are characterized by the carefully controlled activation of selected sets of signature genes. Now, a team of researchers at The Wistar Institute reports discovery of a family of molecular complexes involved in the repression of extensive sets of tissue-specific genes throughout the body. Additionally, one member of the family involved in repressing brain-specific genes in other types of tissues has been found to include a gene thought to be responsible for X-linked mental retardation when mutated. Other components of these complexes have been associated with certain forms of leukemia.
A Montreal researcher has discovered that nerve cells can bypass the body's normal protein-making machinery in the same way that viruses do when they infect a cell. Why would they? To produce large quantities of a particular protein under certain physiological conditions.
New molecular technologies are exposing unexpectedly high levels of DNA folding and complex protein-rich assemblages within the nucleus of cells that researchers say seriously challenge the textbook models. "What we are seeing suggests that there may be machinery, not yet identified, that controls the folding and the movements of enzymes that turn genes on and off," noted one expert at the recent meeting of the American Association for the Advancement of Science.
