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51.
John R Payne 《Journal of applied physiology》2002,92(4):1775-6; author reply 1776-7
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A simple modification of nuclear staining after acid hydrolysis has been made which provides easy identification of quail nuclear markings in a chick-quail chimera. This method also improves the histologic detail normally seen with hematoxylin and eosin when compared to the more commonly used Feulgen reaction. Embryonic tissues can be fixed in Zenker's or Helly's solution and the sections obtained are hydrolyzed in acid (3.5 N HCl at 37 C for 40-50 min). After acid hydrolysis the sections are stained with hematoxylin and eosin rather than Schiff reagent and fast green. The interphase nuclei of chick cells show homogeneous or mottled purplish blue staining, while quail nuclei contain a dark blue spot. This staining corresponds to the reddish purple staining of the quail's heterochromatin seen adjacent to the nucleolus in the standard Feulgen stain. This new technique facilitates identification of quail cell types in the chick host and provides superior histology of the chick tissues by demonstrating cytoplasmic detail. 相似文献
54.
John Williams 《BMJ (Clinical research ed.)》2002,325(7371):1016-1017
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The accumulation of several hundred proteins during the nuclear division cycle of Physarum polycephalum was measured by digital image processing of silver-stained two-dimensional (2D) polyacrylamide gels. In contrast to previous studies, we have used an organism with a naturally synchronous cell cycle, so there are no uncertainties concerning synchronization artifacts or cell-sorting artifacts, and we have measured the specific amounts of each protein rather than the rate of synthesis. Since one-dimensional SDS-PAGE shows no significant fluctuations in the most abundant plasmodial proteins, we have loaded 2D gels so that proteins of low-to-moderate abundance appear in the linear range of the silver stain standard curve. Only five proteins showed reproducible, measureable fluctuations during the cell cycle. One of these proteins was tubulin. Full quantitative information was obtained by analysing the digital images of silver-stained gels by a general image processing system. 相似文献
56.
John Llewelyn Benjamin L. Phillips Ross A. Alford Lin Schwarzkopf Richard Shine 《Oecologia》2010,162(2):343-348
Cane toads (Bufo marinus) are now moving about 5 times faster through tropical Australia than they did a half-century ago, during the early phases of toad invasion. Radio-tracking has revealed higher daily rates of displacement by toads at the invasion front compared to those from long-colonised areas: toads from frontal populations follow straighter paths, move more often, and move further per displacement than do toads from older (long-established) populations. Are these higher movement rates of invasion-front toads associated with modified locomotor performance (e.g. speed, endurance)? In an outdoor raceway, toads collected from the invasion front had similar speeds, but threefold greater endurance, compared to conspecifics collected from a long-established population. Thus, increased daily displacement in invasion-front toads does not appear to be driven by changes in locomotor speed. Instead, increased dispersal is associated with higher endurance, suggesting that invasion-front toads tend to spend more time moving than do their less dispersive conspecifics. Whether this increased endurance is a cause or consequence of behavioural shifts associated with rapid dispersal is unclear. Nonetheless, shifts in endurance between frontal and core populations of this invasive species point to the complex panoply of traits affected by selection for increased dispersal ability on expanding population fronts. 相似文献
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Ruth Duncan Pavla Rejmanova Jindrich Kopeček John B. Lloyd 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(1):143-150
Synthetic 125I-labelled N-(2-hydroxypropyl)methacrylamide copolymers containing four different, potentially degradable peptidyl side chains were incubated with rat visceral yolk sacs cultured in vitro. All copolymers were captured by fluid-phase pinocytosis and three of the side chains were susceptible to lysosomal hydrolysis, resulting in release of [125I]iodotyrosine back into the culture medium. Uptake and degradation was completely inhibited by 2,4-dinitrophenol. The thiol-proteinase inhibitor leupeptin did not affect the rate of pinocytosis, but caused different degrees of inhibition of hydrolysis depending on side chain composition. 相似文献
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John P. Alao Pim J. Huis in 't Veld Frederike Buhse Per Sunnerhagen 《Molecular microbiology》2010,77(1):143-157
The DNA damage and stress response pathways interact to regulate cellular responses to genotoxins and environmental stresses. How these pathways interact in Schizosaccharomyces pombe is not well understood. We demonstrate that osmotic stress suppresses the DNA damage sensitivity of checkpoint mutants, and that this occurs through three distinct cell cycle delays. A delay in G2/M is dependent on Srk1. Progression through mitosis is halted by the Mad2‐dependent spindle checkpoint. Finally, cytokinesis is impaired by modulating Cdc25 expression. These three delays, imposed by osmotic stress, together compensate for the loss of checkpoint signalling. 相似文献
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