****************************************************NATURE************************************************(http://www.nature.com/nature)
[1] Acid-loving microbes yield underground secrets
DOI: 10.1038/nature02340 (http://dx.doi.org/10.1038/nature02340)
Researchers have sequenced the genomes of microbes that dwell in acid flowing through a pyrite ore mine in California. The study — the first to involve sequencing of uncultured microorganisms from environmental samples — shows the value of using genomics to study organisms that have not been cultured in the laboratory.
The mine's microbial community, called a biofilm, contains both bacteria and archaea — a distinct microbial group that includes many organisms able to tolerate extreme conditions — report Jillian F. Banfield and her colleagues in a study published online this week by Nature. The researchers sequenced complete genomes for the bacterium Leptospirillum and the archaean Ferroplasma, and found that they possess pathways for carbon and nitrogen fixation, and for energy generation.
The authors collected samples from Richmond mine, hundreds of feet below Iron Mountain in California. The study was helped by the fact that the biofilm contains only a handful of species with few genomic rearrangements, they add. Most variation within the species is in the form of single-letter changes to the DNA sequence.
***********************************************NATURE MEDICINE****************************************(http://www.nature.com/naturemedicine)
[2] Anti-obesity drugs could increase risk of colorectal cancer
DOI: 10.1038/nm993 (http://dx.doi.org/10.1038/nm993)
Compounds being developed into drugs to treat atherosclerosis and obesity may put patients at risk for colorectal cancer, according to a report in the March issue of Nature Medicine.
Peroxisome proliferator"activated receptor-g (PPAR-g) is a transcription factor that activates genes involved in a number of important pathways in the body. Drugs that enhance the effects of PPAR-g are therefore being considered for use in treating certain diseases. But Raymond Dubois and colleagues found that activating PPAR-d increases the number and size of polyps--precancerous growths--in mice that are genetically predisposed to developing intestinal polyps.
Because larger polyps have a higher chance of progressing to a cancerous state, the authors caution that patients with pre-existing polyps may be at increased risk of developing colorectal cancer if they take drugs that enhance PPAR-g.
Other papers from Nature Medicine to be published online at the same time and with the same embargo:
[3] Role of teichoic acids in Staphylococcus aureus nasal colonization, a major risk factor in nosocomial infections (DOI: 10.1038/nm991) (http://dx.doi.org/10.1038/nm991)
**********************************************NATURE GENETICS****************************************(http://www.nature.com/naturegenetics)
[4] Down syndrome gene helps brain cells connect
DOI: 10.1038/ng1299 (http://dx.doi.org/10.1038/ng1299)
Every one of the trillion cells in the brain may have a unique identity, according to a study in the March issue of Nature Genetics. This identity may be assigned by a gene called Dscam that works to label the developing brain. The gene is remarkable because it could be expressed in 38,016 different ways in flies, and the same gene in humans has been implicated in Down syndrome.
Andrew Chess and colleagues show that different kinds of cells within the fly nervous system make different types of Dscam protein. The same cell may have more than one form giving each cell a unique identity, helping to ensure that it finds its correct place within the brain. As humans with Down syndrome carry an additional copy of the gene, it is possible that the increased amounts of Dscam could interfere with the formation of connections between brain cells, and so contribute to learning difficulties.
Other papers from Nature Genetics to be published online at the same time and with the same embargo:
[5] Mutant P450-oxidoreductase causes disordered steroidogenesis with and without Antley-Bixler syndrome(DOI: 10.1038/ng1300) (http://dx.doi.org/10.1038/ng1300)
[6] Evolutionary innovation of the excretory system in Caenorhabditis elegans(DOI: 10.1038/ng1301) (http://dx.doi.org/10.1038/ng1301)
[7] The hyh mutation uncovers roles for alphaSnap in apical protein localization and control of neural cell fate (DOI: 10.1038/ng1302) (http://dx.doi.org/10.1038/ng1302)
*********************************************NATURE NEUROSCIENCE*********************************(http://www.nature.com/natureneuroscience)
[8] Bringing nerve cells together
DOI: 10.1038/nn1191 (http://dx.doi.org/10.1038/nn1191)
The initial formation of the synaptic connections that enable neurons to communicate with each other is a complex process. The incoming axons of one group of neurons must be targeted to the dendrites of a receiving neuron--no easy task given that the dendritic 'tree' is also growing at the same time. These processes are intimately related, suggests a report in the March issue of Nature Neuroscience, with newly formed synapses helping to direct how a dendrite will grow.
Stephen Smith and colleagues imaged growing dendrites in living zebrafish larvae over the course of several days, while simultaneously looking for developing synapses using a protein label. They found that most synapses form first on a newly extended dendrite-like projection called a filopodium. Only a small number of these new synapses are maintained, but those that remain are able to stabilize the filopodium, which in turn matures into a bona fide dendrite. The process then continues, with new synapses leading to more dendritic branches. Such a model of coordinated synapse and dendrite development may help to explain how nerve cells are able to form highly specific connections.
Other papers from Nature Neuroscience to be published online at the same time and with the same embargo:
[9] Encoding of emotional memories depends on amygdala and hippocampus and their interactions (DOI: 10.1038/nn1190) (http://dx.doi.org/10.1038/nn1190)
*********************************************NATURE IMMUNOLOGY************************************(http://www.nature.com/natureimmunology)
[10] Protecting baby
DOI: 10.1038/ni1037 (http://dx.doi.org/10.1038/ni1037)
Expectant mothers do not typically reject their babies by mounting an immune response. A systemic change occurs in the immune systems of pregnant women that lessens the possibility of fetal rejection as well as other potentially harmful autoimmune reactions. In the March issue of Nature Immunology, British researchers show that pregnancy induces an immune-tolerant state by increasing the number of particular immune cells known as CD4+CD25+ regulatory T cells.
Regulatory T cells act to control other T cells, thereby preventing attack on tissues that might be perceived as foreign by the immune system. Alexander Betz and colleagues found that pregnant mice had two to three times the number of circulating regulatory T cells of nonpregnant age-matched female mice. These increases occurred soon after conception, but waned after birth. When the regulatory T cells were depleted in the pregnant mice, spontaneous rejection of their fetuses occurred. These results suggest that the regulatory T cells might be the principal means by which pregnant mothers tolerate their developing embryos. This research might lead to diagnostic tests for infertile couples who experience recurrent pregnancy losses.
Other papers from Nature Immunology to be published online at the same time and with the same embargo:
[11] B cell receptor signal strength determines B cell fate(DOI: 10.1038/ni1036) (http://dx.doi.org/10.1038/ni1036)
[12] ERM proteins regulate cytoskeleton relaxation promoting T cell-APC conjugation(DOI: 10.1038/ni1039) (http://dx.doi.org/10.1038/ni1039)
***************************************************************************************************************Items from other Nature journals to be published online at the same time and with the same embargo:
NATURE BIOTECHNOLOGY (http://www.nature.com/naturebiotechnology)
[13] Rational siRNA design for RNA interference (DOI: 10.1038/nbt936) (http://dx.doi.org/10.1038/nbt936)
NATURE STRUCTURAL & MOLECULAR BIOLOGY (http://www.nature.com/natstructmolbiol)
[14] A DNA enzyme that mimics the first step of RNA splicing (DOI: 10.1038/nsmb727) (http://dx.doi.org/10.1038/nsmb727) [15] Crystal structure of Dcp1p and its functional implications in mRNA decapping (DOI: 10.1038/nsmb730) (http://dx.doi.org/10.1038/nmsb730)
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GEOGRAPHICAL LISTING OF AUTHORS
The following list of places refers to the whereabouts of authors on the papers numbered in this release. The listing may be for an author's main affiliation, or for a place where they are working temporarily. Please see the PDF of the paper for full details.
AUSTRALIARandwick: 5
BRAZILSao Paulo: 5
FRANCEParis: 12
GERMANYCologne: 11Munich: 11Tuebingen: 3
JAPANAsahikawa: 5Sapporo: 5
SINGAPORESingapore: 15
UNITED KINGDOMCambridge: 10London: 9, 12
UNITED STATES OF AMERICA
Arizona Tucson: 15California Berkeley: 1 San Francisco: 5 Stanford: 8 Walnut Creek: 1Colorado Lafayette: 13Illinois Urbana: 14Maryland Baltimore: 5 Bethesda: 12 Gaithersburg: 3Massachusetts Boston: 7, 11 Cambridge: 4Missouri St Louis: 7Ohio Columbus: 6Tennessee Nashville: 2
Nature Publishing Group is a division of Macmillan Publishers Ltd.
Macmillan is an international publisher serving the information and education community as well as publishing fiction and non-fiction.
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