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isms could be sufficient to explain the large accumulations of phosphorite observed in many parts of the world's oceans.

Exercise, Oxygen Metabolism, and Health

Human epidemiological studies have suggested that low aerobic capacity is a strong predictor of mortality. Wisloff et al. (p. 418;see the news story by Marx) compared two lines of rats produced by 11 generations of genetic selection for high or low scores in endurance running. Rats with low aerobic capacity had many of the risk factors that define metabolic syndrome, including high blood pressure, elevated levels of plasma triglycerides, and impaired glucose tolerance. Preliminary expression data were consistent with a decline in mitochondrial function in the unfit rats.

Motility in a Mollicute

Mollicutes (Mycoplasma, Acholeplasma, and Spiroplasma) are small prokaryotic cells that have distinct morphologies and that are motile despite their lack of cell walls or appendages such as flagella. Recent studies have identified a fibril protein that forms a cytoskeletal ribbon likely involved in promoting motility. Kurner et al. (p. 436) have used cryo-electron tomography to visualize the three-dimensional structure of the whole cell for the spiral-shaped mollicute Spiroplasma mel-liferum. The cytoskeletal structure consists of two outer ribbons, comprising five thick filaments each, joined by an inner ribbon comprising nine thin filaments. The thick filaments are polymers of fibril protein and the thin filaments are polymers of the actin-like protein MreB. Cell motility could be promoted by coordinated length changes of the cytoskeletal ribbons.

An Insulin Mimic Secreted by Visceral Fat

Excessive amounts of abdominal visceral fat, sometimes referred to as "bad fat," significantly increase an individual's risk of developing insulin resistance and other metabolic disorders. These adverse health effects may be mediated in part by fat-derived cytokines that circulate in the blood. Fukuhara et al. (p. 426, published online 16 December 2004;see the Perspective by Hug and Lodish) characterized "visfatin," a cytokine that is highly expressed in visceral fat and whose blood levels correlate with obesity. Surprisingly, functional analyses in mice revealed that visfatin has beneficial, insulinlike activity, causing a lowering of blood glucose levels. Even more surprisingly, visfatin was shown to bind to the insulin receptor and activate the insulin signal transduction pathway. While the precise physiological role of visfatin remains to be established, the discovery of this natural insulin mimetic could open exciting new avenues in diabetes research and therapy.

Transcription Factors and Helper T Cell Lineage Determination

In helper T (Th) cells, cell fate is primarily determined by the transcription factors GATA3, which directs Th2 type cells and T-bet, which regulates Th1 lineage choice. Hwang et al. (p. 430) found that during the early stages of a T helper precursor's decision to become a Th1 cell, T-bet has an unusual means of repressing the Th2-promoting effects of GATA3. After T cell stimulation and under the right polarizing conditions for Th1 cells, T-bet 3 becomes phosphorylated by the tyrosine kinase, ITK, which allows it to bind GATA3. s This process prevents it from interacting with its Th2 cytokine target genes. This study 1 reveals a further means by which transcription factors may directly cross-regulate one | another in specifying cell lineage fate.

What can Science SAGE KE give me?

Supplements For Diabetics

Supplements For Diabetics

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