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H. V. Carey H. J. Cooke P. R. Nemeth D. H. Zafirov J. D. Wood 《Cellular and molecular life sciences : CMLS》1985,41(9):1156-1158
Summary The effects of forskolin on myenteric neuronal activity and mucosal function were examined in guinea pig ileum. Forskolin increased the excitability of myenteric neurons, and increased mucosal chloride secretion by stimulating enteric neurons as well as by acting directly on enterocytes.Acknowledgment. The authors thank E. Martens, S. Bowen for technical assistance and N. Schaad for secretarial assistance. This work was supported by National Institutes of Health Grants, F32-AM07301, K-104-AM1004, RO1-AM29699, RO1-AM26742 and an Eloise Gerry Fellowship. 相似文献
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The trophic fingerprint of marine fisheries 总被引:3,自引:0,他引:3
Branch TA Watson R Fulton EA Jennings S McGilliard CR Pablico GT Ricard D Tracey SR 《Nature》2010,468(7322):431-435
Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse ("fishing down marine food webs") and when low-trophic-level fisheries expand ("fishing through marine food webs"). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing. 相似文献
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Stewart SA Ben-Porath I Carey VJ O'Connor BF Hahn WC Weinberg RA 《Nature genetics》2003,33(4):492-496
Cultured primary human cells inevitably enter a state of replicative senescence for which the specific molecular trigger is unknown. We show that the single-strand telomeric overhang, a key component of telomere structure, is eroded at senescence. Expression of telomerase prevents overhang loss, suggesting that this enzyme prevents senescence by maintaining proper telomere structure. In contrast, progressive overhang loss occurs in cells that avoid senescence through the inactivation of p53 and Rb, indicating that overhang erosion is the result of continuous cell division and not a consequence of senescence. We thus provide evidence for a specific molecular alteration in telomere structure at senescence and suggest that this change, rather than overall telomere length, serves to trigger this state. 相似文献
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Chromosome-wide distribution of haplotype blocks and the role of recombination hot spots 总被引:19,自引:0,他引:19
Phillips MS Lawrence R Sachidanandam R Morris AP Balding DJ Donaldson MA Studebaker JF Ankener WM Alfisi SV Kuo FS Camisa AL Pazorov V Scott KE Carey BJ Faith J Katari G Bhatti HA Cyr JM Derohannessian V Elosua C Forman AM Grecco NM Hock CR Kuebler JM Lathrop JA Mockler MA Nachtman EP Restine SL Varde SA Hozza MJ Gelfand CA Broxholme J Abecasis GR Boyce-Jacino MT Cardon LR 《Nature genetics》2003,33(3):382-387
Recent studies of human populations suggest that the genome consists of chromosome segments that are ancestrally conserved ('haplotype blocks'; refs. 1-3) and have discrete boundaries defined by recombination hot spots. Using publicly available genetic markers, we have constructed a first-generation haplotype map of chromosome 19. As expected for this marker density, approximately one-third of the chromosome is encompassed within haplotype blocks. Evolutionary modeling of the data indicates that recombination hot spots are not required to explain most of the observed blocks, providing that marker ascertainment and the observed marker spacing are considered. In contrast, several long blocks are inconsistent with our evolutionary models, and different mechanisms could explain their origins. 相似文献
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The effects of forskolin on myenteric neuronal activity and mucosal function were examined in guinea pig ileum. Forskolin increased the excitability of myenteric neurons, and increased mucosal chloride secretion by stimulating enteric neurons as well as by acting directly on enterocytes. 相似文献