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Modeling studies are now a significant part of mainstream research in motor control. Novel and classical modeling techniques used in recent work on small and large motor systems illustrate the different roles that models play in furthering our understanding of motor systems. The models presented reveal single neuron short-term memory, unexpected effects of reciprocal inhibition and methods for decoding activity in large populations of neurons. 相似文献
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Nucleologenesis: Composition and fate of prenucleolar bodies 总被引:21,自引:0,他引:21
Robert L. Ochs Michael A. Lischwe Eve Shen Robert E. Carroll Harris Busch 《Chromosoma》1985,92(5):330-336
A time course study was conducted on nucleologenesis after release from a mitotic block in the presence and absence of actinomycin D to determine the composition and fate of prenucleolar bodies (PNBs). Prenucleolar bodies, whether naturally occurring or induced by actinomycin D treatment, stain with silver and contain phosphoproteins B23 and C23, two of the major proteins of the interphase nucleolus as determined by double label immunofluorescence with specific antibodies. The nucleolus is formed by fusion of PNBs, which subsequently reorganize and form internal fibrillar and peripheral granular regions. Actinomycin D prevents fusion of PNBs, which are then randomly dispersed throughout the nucleus but they still contain proteins B23 and C23. These results demonstrate that the nucleolus is formed by fusion of prenucleolar structures whose biochemical composition resembles the mature nucleolus, since PNBs contain at least two of the major nucleolar proteins. 相似文献
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Comparison of cyclopropene, 1-methylcyclopropene, and 3,3-dimethylcyclopropene as ethylene antagonists in plants 总被引:5,自引:0,他引:5
A comparison has been made of cyclopropene (CP), 1-methylcyclopropene (1-MCP), and 3,3-dimethyl-cyclopropene (3,3-DMCP) in their ability to protect plants against ethylene. In bananas, both CP and 1-MCP are effective around 0.5 nL L–1, and 3,3-DMCP was effective at 1 L L–1. Bananas treated with CP and 1-MCP again become sensitive to ethylene at 12 days and those treated with 3,3-DMCP at 7 days. Mature green tomatoes are protected by 5–7 nL L–1 of 1-MPC for 8 days at 25°C and tomatoes treated with 3,3-DMCP at 5–10 L L–1 are protected for 5 days. Carnation flowers are protected with CP or 1-MCP after exposure to 0.5 nL L–1 for 24 hours and by 1 L L–1 of 3,3-DMCP. The display life of Campanula flowers is increased from 3.3 to 5.4 days by 10 L L–1 of 3,3-DMCP and to 9 days by 20 nL L–1 of 1-MCP. Ethylene inhibition of pea seedlings is reduced by treatment with 1-MCP at 10 L L–1 of ethylene but as ethylene is increased to 3000 L L–1 growth inhibition increases. 3,3-DMCP treatment causes very little reduction of the ethylene effect even at very low concentrations. 相似文献
127.
Mathilde Mercat Olivier Clermont Méril Massot Etienne Ruppe Michel de Garine-Wichatitsky Eve Miguel Hugo Valls Fox Daniel Cornelis Antoine Andremont Erick Denamur Alexandre Caron 《Applied and environmental microbiology》2016,82(5):1459-1467
At a human/livestock/wildlife interface, Escherichia coli populations were used to assess the risk of bacterial and antibiotic resistance dissemination between hosts. We used phenotypic and genotypic characterization techniques to describe the structure and the level of antibiotic resistance of E. coli commensal populations and the resistant Enterobacteriaceae carriage of sympatric African buffalo (Syncerus caffer caffer) and cattle populations characterized by their contact patterns in the southern part of Hwange ecosystem in Zimbabwe. Our results (i) confirmed our assumption that buffalo and cattle share similar phylogroup profiles, dominated by B1 (44.5%) and E (29.0%) phylogroups, with some variability in A phylogroup presence (from 1.9 to 12%); (ii) identified a significant gradient of antibiotic resistance from isolated buffalo to buffalo in contact with cattle and cattle populations expressed as the Murray score among Enterobacteriaceae (0.146, 0.258, and 0.340, respectively) and as the presence of tetracycline-, trimethoprim-, and amoxicillin-resistant subdominant E. coli strains (0, 5.7, and 38%, respectively); (iii) evidenced the dissemination of tetracycline, trimethoprim, and amoxicillin resistance genes (tet, dfrA, and blaTEM-1) in 26 isolated subdominant E. coli strains between nearby buffalo and cattle populations, that led us (iv) to hypothesize the role of the human/animal interface in the dissemination of genetic material from human to cattle and toward wildlife. The study of antibiotic resistance dissemination in multihost systems and at anthropized/natural interface is necessary to better understand and mitigate its multiple threats. These results also contribute to attempts aiming at using E. coli as a tool for the identification of pathogen transmission pathway in multihost systems. 相似文献
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The distribution of a pulse of teichoic acid-specific radiolabel between wall and membrane teichoic acids in pneumococci was constant over a subsequent chase period, suggesting that wall and membrane teichoic acids are biosynthesized simultaneously and independently. 相似文献
130.
Heptabrachia canadensis , previously known from one juvenile specimen, has been redescribed from new material and transferred to the genus Polybrachia. About 1400 specimens were available for study, including a series of developmental stages ranging from juveniles less than 0.1 mm in diameter to adults 0.6 mm in diameter. The smallest juveniles have one tentacle while most adults have 30 to 40 tentacles. Juveniles differ from adults in diameter, length, number of tentacles and type of tube. The most important observation to emerge is the variability of characters hitherto thought to distinguish different genera, and the need for care in the diagnosis of new species from limited material. 相似文献