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851.
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Sheryl Coombs Paul Patton 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(3):279-297
Information contained in the spatial excitation pattern along arrayed sensors in the lateral line system of Lake Michigan
mottled sculpin, as well as other surface-feeding fish and amphibians, is thought to play a fundamental role in guiding prey-orienting
behaviors. However, the way in which prey location is encoded by the excitation pattern and used by the nervous system to
direct orienting behaviors is largely unknown. In this study, we test the hypothesis that mottled sculpin use excitation peaks
(local ‘hot spots’) to determine the somatotopic location of an artificial prey (vibrating sphere/dipole source) along the
body surface. Dipole orientation (axis of sphere vibration re: long axis of the fish) is manipulated to produce excitatory
peaks in different body locations without changing the actual sphere location. Our results show that orienting accuracy is
largely independent of source orientation, but not source distance and that turning directions are not guided by local hot
spots in the somatotopic activation pattern of the lateral line. 相似文献
854.
855.
Cleavable Crosslinking reagents were used to study interactions among proteins of the surface coat of Trypanosoma brucei. The proteins were resolved by two-dimensional polyacrylamide gel electrophoresis in sodium dodecyl sulfate. When intact cells were treated with dithiobis(succinimidylpropionate), we obtained extensive intermolecular Crosslinking of major variable surface coat glycoprotein (VSCG) molecules. This reagent generated no apparent crosslinks between VSCG and other membrane-associated proteins. Complete conversion to oligomers equal to or greater than octamers occurred within 20 min. When purified VSCG in solution was treated with dithiobis(succimidylpropionate), dimers were found. A complex of Cu2+ and 1,10-phenanthroline was used to catalyze air oxidation of adjacent sulfhydryls to disulfide bonds; however, no crosslinking among VSCG molecules nor between VSCG and other proteins was observed. The results presented indicate that VSCG in solution exists predominately in the form of dimers. Whether VSCG in situ also occurred as dimers could not be determined; however, since we observed trimeric and tetrameric forms of VSCG when untreated cells were analyzed, it is likely that weak interactions occur among the protein molecules. These interactions are less stable than the dimer association observed with purified VSCG. Finally, the analysis indicated that VSCGs of this stock of T. brucei, derived from UGANDA/ 60/TREU/164[ETat3], contained at least one intramolecular disulfide bond. We examined T. brucei stocks 427 and EATRO 110 and obtained similar results. Thus, it appears that intramolecular disulfide bonding is a general feature of T. brucei VSCGs. 相似文献
856.
857.
Isolation of Clostridium spiroforme from rabbits 总被引:2,自引:0,他引:2
The isolation of Clostridium spiroforme from intestinal contents of rabbits was achieved by sampling the supernatant-pellet interphase of centrifuged specimens processed for routine toxin analysis. High-speed centrifugation at 20,000x for 15 minutes provided a rapid and effective means of separating this anaerobic pathogen from the majority of both indigenous and non-indigenous intestinal microbial flora. The unusual helically-coiled, semicircular shape of the microorganism is considered, at least in part, responsible for this phenomenon. 相似文献
858.
J.R. Patton 《Biochimie》1994,76(12)
Recent in vitro studies on the formation of pseudouridine (Ψ) in the spliceosomal small nuclear RNAs (snRNA) are reviewed. Multiple Ψ synthase activities, in some cases more that one per snRNA, are responsible for this modification of uridine. There is a requirement for Sm protein binding for the efficient formation of Ψ in U5 RNA but not for the modification of U2 RNA. The inhibition of Ψ formation by the incorporation of 5-fluorouridine in the snRNA is also reviewed. 相似文献
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860.
R.E. Erb H.A. Garverick R.S. Patton R.D. Randel E.L. Monk Martina I. Udo-Aka C.J. Callahan 《Theriogenology》1976,5(5):213-226
Effects of continuous free-choice feeding of urea in blended rations on reproductive hormones were compared during three consecutive reproductive periods. Urea nitrogen replaced plant nitrogen as follows for Groups 1, 2 and 3, respectively: 0, 22 and 45% from insemination to mid pregnancy, 0, 8 and 16% thereafter until 2 weeks before first calving, and 0, 18 and 36% precalving and during lactations. Dietary urea was consistently associated with significantly increased progesterone in blood plasma at all periods. In contrast, estrogen was significantly lower in urine of Group 3 during Days 1 to 18 after first insemination as heifers, but not at second calving or during Days 1 to 18 after insemination for third pregnancy. Plasma estrogen was significantly lower in Group 3 than Group 1 only during the first pregnancy. Group 2 was intermediate. Length of first gestation was subnormal in Groups 1 and 2. It was concluded that dietary urea caused differences in reproductive hormones which were improtant only during the first pregnancy as heifers. 相似文献