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991.
Synopsis Although kleptoparasitism, or food-stealing, is common in birds and some carnivorous mammals, reported instances are exceedingly
rare in fishes. We studied the behaviour and ecology of the 11 endemic tilapiine cichlids of Lake Barombi Mbo, Cameroon, West
Africa. Here we report that six of the Barombi cichlids (Stomatepia mariae, S. pindu, Konia eisentrauti, Pungu maclareni, Sarotherodon lohbergeri, andS. linnellii) kleptoparasitize freshwater crabsPotamon africanus. 相似文献
992.
Crouch L. S.; Prough R. A.; Kennedy K. A.; Snyder J. B.; Warshaw J. B. 《Journal of applied physiology》1988,65(2):797-804
The hyperoxia-induced increases in the activity of lung glucose-6-phosphate dehydrogenase (G-6-P) and glutathione reductase (GR) after exposure of rats to greater than 97% O2 for 6 days were accompanied by equivalent increases in the amount of the respective immunoreactive proteins. Hyperoxia also increased lung glutathione (GSH) + oxidized glutathione (GSSG) content and the magnitude of this hyperoxic response of increased GSH + GSSG, G-6-P, and GR (maximal 1.3- to 1.8-fold) declined as a function of age during the first 3 wk of life. Fetal rat lung explants cultured 4 days in 95% O2 showed increased G-6-P and GR activity and increased levels of the specific proteins 1.5-fold those of explants at 2 days of culture. We conclude that the hyperoxic response of increased rat lung G-6-P and GR activity in vivo and in vitro involves not just alteration of enzyme activity but also specific increases in the proteins catalyzing the reactions. 相似文献
993.
The role of deoxynucleoside triphosphate pools in the inhibition of DNA-excision repair and replication in human cells by hydroxyurea 总被引:6,自引:0,他引:6
R D Snyder 《Mutation research》1984,131(3-4):163-172
The effects of hydroxyurea (HU) on the DNA-excision repair process in human cells has been systematically examined. It is demonstrated that HU induces DNA single-strand break accumulation in a dose-dependent fashion in ultraviolet-irradiated and MMS-treated confluent but not log-phase fibroblasts and that these breaks are clearly the consequence of the inhibition by HU of the enzyme, ribonucleotide reductase. The breaks form rapidly, are stable for at least 10 h and largely disappear by 20 h. The production of these DNA-strand breaks is antagonized by a combined treatment of 10 microM deoxyadenosine, deoxycytidine and deoxyguanosine whereas thymidine potentiates strand-break formation at low HU concentrations. It is also confirmed that HU, while inhibiting replicative synthesis has no apparent inhibitory effect on unscheduled DNA synthesis (UDS) although the increased uptake of labeled DNA precursors into HU-treated cells makes it difficult to assess the actual effects on the repair-synthetic process. Analysis of the effects of HU on deoxynucleoside triphosphate pool levels and the demonstration of the failure of the HU block to replicative synthesis to be reversed by high (1 mM) concentrations of added deoxynucleosides lend support to the notion of compartmentalized dNTP pools for repair and replication. 相似文献
994.
Viable microorganism detection by induced fluorescence 总被引:1,自引:0,他引:1
995.
996.
Human myometrial cells were dispersed from uterine tissue by limited enzymatic digestion of myometrium that was obtained at the time of hysterectomy. The dispersed myometrial cells that are obtained in this manner can be maintained in monolayer culture in the presence of medium that contains fetal bovine serum. In primary culture, as well as after passage, the characteristics of these cells are morphologically and biochemically similar to those of smooth muscle cells and myometrial tissue. 相似文献
997.
Despite their remoteness from sources of atmospheric pollutant emissions, the Afromontane tarns in the Maloti-Drakensberg region are perfect candidates to study the negative effects of acidifying atmospheric pollution, because mountain lakes are widely recognised as sentinel ecosystems, unimpacted by direct human disturbance within their catchments. Thirty-four tarns were sampled in the Maloti-Drakensberg region and most were found to be extremely sensitive to acidic deposition, as indicated by their low acid neutralising capacity. There are very few studies of freshwater critical loads for any region within South Africa. The steady-state water chemistry model (SSWC) was adapted and used to determine critical loads, whereas exceedance was estimated relative to modelled regional deposition data, in order to understand the risk of harmful effects to aquatic ecosystems. Seventy-six percent of sampled sites across the Maloti-Drakensberg would exceed critical loads even at the lowest modelled deposition levels, but there are no current measured deposition data for the region. The sensitivity of the Maloti-Drakensberg tarns needs to be considered in future policy formulation regarding acceptable levels of acidifying atmospheric pollution from South Africa’s energy sector and indicates the need for assessing aquatic ecosystem impacts in other regions of South Africa. 相似文献
998.
Huizhen Huang Marissa S. Kuzirian Xiaoyun Cai Lindsey M. Snyder Jonathan Cohen Daniel H. Kaplan Sarah E. Ross 《Genesis (New York, N.Y. : 2000)》2016,54(11):593-601
The Neurokinin 1 Receptor (NK1R), which binds Substance P, is expressed in discrete populations of neurons throughout the nervous system, where it has numerous roles including the modulation of pain and affective behaviors. Here, we report the generation of a NK1R‐CreER knockin allele, in which CreERT2 replaces the coding sequence of the TACR1 gene (encoding NK1R) in order to gain genetic access to these cells. We find that the NK1R‐CreER allele mediates recombination in many regions of the nervous system that are important in pain and anxiety including the amygdala, hypothalamus, frontal cortex, raphe nucleus, and dorsal horn of the spinal cord. Other cell types that are labeled by this allele include amacrine cells in the retina and fibroblasts in the skin. Thus, the NK1R‐CreER mouse line is a valuable new tool for conditional gene manipulation enabling the visualization and manipulation of cells that express NK1R. 相似文献
999.
1000.
Vincent Ranwez Frédéric Delsuc Sylvie Ranwez Khalid Belkhir Marie-Ka Tilak Emmanuel JP Douzery 《BMC evolutionary biology》2007,7(1):241