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排序方式: 共有595条查询结果,搜索用时 15 毫秒
91.
92.
Extracellular-regulated protein kinase cascades are activated in response to injury in human skeletal muscle 总被引:6,自引:0,他引:6
93.
Olle Lindvall Anders Björklund Tomas Hökfelt Åke Ljungdahl 《Histochemistry and cell biology》1973,35(1):31-38
Summary The glyoxylic acid fluorescence histochemical method for the visualization of neuronal monoamines has been applied to fresh or glyoxylic acid-perfused brain tissue, sectioned with the Vibratome intrument. This technique demonstrates the central noradrenaline and dopamine neuron systems with a sensitivity and richness in details that is superior to the standard Falck-Hillarp formaldehyde method, as observed in the following three ways: First, the entire axon, including the non-terminal portions, became fluorescent; second, more extensive terminal systems were detected in certain brain regions ; third, due to the absence of diffusion, the delicate dopamine-containing fibres in e. g. the caudate nucleus and the median eminence had a distinct fluorescence. It is concluded that the glyoxylic acid method applied to Vibratome sections should be ideal for precise and detailed neuroanatomical studies on central catecholamine neuron systems. 相似文献
94.
Stimulation of ornithine decarboxylase activity and inhibition of S-adenosyl-l-methionine decarboxylase activity in leukaemic mice by methylglyoxal bis(guanylhydrazone) (Short Communication) 下载免费PDF全文
Administration of methylglyoxal bis(guanylhydrazone) to leukaemic mice results in an early depression followed by a marked elevation of S-adenosyl-l-methionine decarboxylase activity. Further, there is an early prolonged increase in the activity of ornithine decarboxylase, the initial enzyme in the polyamine biosynthetic pathway. Because of the profound effects of methylglyoxal bis(guanylhydrazone) in vivo on the polyamine biosynthetic pathway, the drug can no longer be considered a specific inhibitor of spermidine synthesis. 相似文献
95.
Wolfgang Uerkvitz Olle Karlström Agnete Munch-Petersen 《Molecular & general genetics : MGG》1973,121(4):337-346
Summary A two-step mutant lacking two periplasmic enzymes, alkaline phosphatase and 5-nucleotidase, was prepared. In extracts of this strain phosphatase activities towards several 5-nucleotides could be detected. We have partially purified a dUMP phosphatase by streptomycin precipitation and DEAE-chromatography. This preparation has significant phosphatase activity towards three substrates, viz. dUMP, dTMP and UMP, but only traces of activity towards nine other tested nucleoside monophosphates. The three activities are probably due to a single enzyme, since they decrease in parallel on long time storage at 4°C and respond in parallel to stimulatory and inhibitory influences of different buffers and metal ions. The best buffer tested is glycylglycine buffer; Mg2+ is required but 25% activity can be obtained with Co2+ and Mn2+ and 6–8% activity with Fe2+ and Ni2+. Ca2+, Cu2+ or Zn2+ inhibit the phosphatase activities in the presence of Mg2+ or Co2+. The activities towards UMP and dUMP in the DEAE—chromatography eluted identically. The enzyme has the remarkably high apparent K
m of 10-2 M with all three substrates. 相似文献
96.
Aileen Berasategui Karolin Axelsson Göran Nordlander Axel Schmidt Anna‐Karin Borg‐Karlson Jonathan Gershenzon Olle Terenius Martin Kaltenpoth 《Molecular ecology》2016,25(16):4014-4031
The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta‐analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on nonconifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis‐associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or through the supplementation of essential nutrients. 相似文献
97.
98.
Yucca moth oviposition and pollination behavior is affected by past flower visitors: evidence for a host-marking pheromone 总被引:1,自引:0,他引:1
Insect larvae such as those of yucca moths that feed on small, patchily distributed food items often face an elevated risk
of intraspecific competition or cannibalism. For this reason, ovipositing females may assess a potential oviposition site
for prior conspecific eggs or larvae before deciding whether to oviposit. Selective abortion of yucca flowers with high egg
numbers prevents competition among larvae of the yucca moth Tegeticula yuccasella, but the same mechanism should select for female detection of and fewer ovipositions in flowers that already contain eggs.
Female yucca moths presented with either virgin or previously visited flowers laid significantly fewer eggs in the latter
flowers and pollinated them less often. A significant negative association was found between number of previous oviposition
attempts in a flower and number of additional attempts by a female, suggesting a quantitative assessment of prior egg load,
but the correlation coefficient was low. Factors contributing to this low correlation may include variation in signal quality,
poor detection capability, uncertainty contributed by a variable oviposition attempt to egg ratio, and a variable response
criterion based on recent female experience and physiological status. Females rationed their pollen by pollinating at decreasing
frequency during a bout within a flower, and by depositing smaller pollen loads during later pollinations within a flower.
Females ovipositing into a previously visited flower pollinated as frequently as would a first female for a given oviposition
attempt within a flower, i.e., the probability of pollination after the nth oviposition was independent of whether it was performed by a first or a later moth. Experimental presentation of virgin
flowers marked with a homogenate from female abdomens induced the same oviposition and pollination behavior as seen on previously
visited flowers, suggesting the presence of a host-marking pheromone. Given that all eggs within a selectively aborted flower
die, there may be selection among some yucca moths for providing a strong signal of floral egg status to conspecific females.
Received: 1 December 1998 / Accepted: 7 February 1999 相似文献
99.
100.
We describe a method, DNA array to protein array (DAPA), which allows the 'printing' of replicate protein arrays directly from a DNA array template using cell-free protein synthesis. At least 20 copies of a protein array can be obtained from a single DNA array. DAPA eliminates the need for separate protein expression, purification and spotting, and also overcomes the problem of long-term functional storage of surface-bound proteins. 相似文献