Abstract
CELL BIOLOGY Cells encounter many different forms of stress and have evolved a variety of methods to deal with them. They tackle relatively minor stresses, such as excessive heat or insufficient oxygen (hypoxia), by forming cytoplasmic stress granules, which prevent the accumulation of defective proteins that can irreparably damage the cell. However, some stresses, including x-rays and DNA-damaging agents, are insurmountable, and the cell acknowledges defeat by killing itself in a process called apoptosis. This is triggered via the intracellular signaling cascades known as the stress-activated p38 and JNK MAPK (SAPK) pathways. Whether and how these two mechanisms of stress management are connected was unknown. Arimoto et al. find that the formation of stress granules in response to minor stresses specifically inhibits the SAPK-mediated cell death response, indicating a connection between the two pathways. They found that the signaling scaffold protein RACK1 is required for the apoptotic response by binding directly to a protein in the SAPK pathway. However, during minor stresses RACK1 becomes sequestered within the cytoplasmic stress granules, thereby inhibiting apoptosis. The authors also showed that when cells are exposed to both types of stresses simultaneously, SAPK-mediated apoptosis is blocked. This mechanism of cross talk between two stress-management pathways could explain in part why cancer cells, which live under the constant minor stress of hypoxia, are resistant to apoptosis induced by radiotherapy and chemotherapy. — HP [*][1] Nat. Cell Biol. , 10.1038/ncb1791 (2008). [1]: #fn-1
Highlights
During the implantation or insertion of medical devices such as catheters, pathogenic microbes may be introduced into the patient
By tuning the hydrolysis rate of the coating, it should be possible to adapt it to a range of applications in implantable medical devices. — JFU
The decline of Columbia River salmon may be one sign of the human impact on fisheries, and it has been argued that some of the Columbia River dams should be removed in order to reduce the hazards encountered by salmon smolts as they make their way from the spawning grounds to the sea
Summary
During the implantation or insertion of medical devices such as catheters, pathogenic microbes may be introduced into the patient. Microbes may attach to the surface of the device to form a biofilm, a common cause of device failure To overcome these problems, several strategies have been used to create coatings that are either antimicrobial or nonfouling. Based on the principle of reflection and trapping within the cavity, but using diffraction from crystallographic planes of silicon, Chen et al have developed a Fabry-Perot type of cavity for x-rays They demonstrate the ability to maintain coherence and form standing waves within the cavity, obtaining promising results toward the goal of obtaining a high-brightness source of quasicoherent x-ray pulses for probing the dynamics of structural and electronic transitions. In order to assess migration losses in the Thompson-Fraser (which is not dammed) and the Snake-Columbia (which is) river systems in North America, Welch et al measured the survival rate of Chinook and steelhead smolts with implanted acoustic tags. Not all parrotfish were the same: Princess parrotfish preferred the mat-forming seaweeds, and redbands grazed the taller species
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