共查询到20条相似文献,搜索用时 15 毫秒
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Weber I 《European journal of cell biology》2006,85(9-10):915-924
The concept of pilot pseudopodia is reconsidered 30 years after its inauguration (Gerisch, G., Hülser, D., Malchow, D., Wick, U., 1975. Cell communication by periodic cyclic-AMP pulses. Phil. Trans. R. Soc. Lond. B 272, 181-192). The original hypothesis stated that protruding pseudopodia serve as dynamic sensory organelles that aid a cell in perceiving variations of chemoattractant concentration and, consequently, in navigation during chemotaxis. This influential idea is reevaluated in the light of recent findings about the mechanisms governing chemotactic cell motility, morphology and dynamics of pseudopodia, and about molecular constituents and regulators of pseudopod extension and retraction. It is proposed that stimulation by a chemoattractant modulates speed of pseudopod protrusion and thereby increases cell elongation. Elongation further enhances chemotactic sensitivity of the cell to shallow chemoattractant gradients, reinforces cell polarization, and finally leads to suppression of lateral pseudopodia and continuation of cell migration in the gradient direction. 相似文献
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Lee JA 《Biologist (London, England)》2002,49(2):92
Have you ever wondered why professionals have so many complicated names for things? Two reasons come to mind: efficient communication, but also 'show'. Connecting with a wider audience means learning to tread the fine line between perfect accuracy and being understood. 相似文献
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Bowman DD 《Trends in parasitology》2005,21(6):267-269
The names of organisms have major impacts on the geopolitical world. The current state of flux in the taxonomy of the genera Cryptosporidium and Giardia illustrates the effects that names can have on environmental and governmental policy. Taxonomy remains a vital science that is very much alive in the application of modern methods for describing morphologically cryptic species. 相似文献
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The complete sequence of rice centromere 8 reveals a small amount of centromere-specific satellite sequence in blocks interrupted by retrotransposons and other repetitive DNA, in an arrangement that is strikingly similar in overall size and content to other centromeres of multicellular eukaryotes. 相似文献
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Wagner PD 《Journal of applied physiology (Bethesda, Md. : 1985)》2011,111(4):951-953
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We have characterized a whole-arm translocation involving chromosomes 1 and 19 by traditional cytogenetic methods and fluorescence in situ hybridization with chromosome-specific -satellite and whole-chromosome painting probes, and different satellite III DNA probes. We have identified a break in the -satellite DNA region of chromosome 1, with division of this material into two a-satellite DNA blocks. This leaves one translocation chromosome with truncated -satellite DNA from chromosome 1 and the other trranslocation chromosome with all the -satellite DNA from chromosome 19 and truncated -satellite DNA from chromosome 1. We speculate whether the recombination event observed has taken place in tetraplex structures of satellite III DNA interspersed between -satellite DNA. 相似文献
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Jitka Klimešová Ondřej Mudrák Jiři Doležal Michal Hájek Martin Dančák Leoš Klimeš 《Folia Geobotanica》2013,48(3):373-391
The species richness of grasslands generally cannot be fully restored after changes in management. Some species with small statures and basal leaf rosettes can be lost forever. The same species, however, seem to possess the traits necessary for successful re-colonization – they produce small, easily dispersable seeds, numerous seedlings and have lasting seed banks. We tested the hypothesis that plants in species-rich grasslands can be characterized by a negative correlation between their competitive ability and potential for generative regeneration, i.e. by a competition-colonization trade-off. An analysis of the traits of 95 grassland species supported this hypothesis. We then conducted a manipulative experiment in three different meadow communities in the Bílé Karpaty Mts. The experiment involved characterizing species traits during periods of different grassland management regimes in the years 1997–2000 and comparing these with the original management regime, which was restored between 2000 and 2003. We found out that the hypothesis only holds true for the pooled dataset for all three communities. When the individual meadow communities were analyzed separately, plant traits other than those responsible for the competition-colonization trade-off appear to be characteristic of responsive species, e.g. shoot lifespan or phenology. Our results imply that despite the general trade-offs found in large comparative studies, the plant response in a specific community is constrained by the local species pool. 相似文献
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