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101.
The acrosome reaction induced by the zona pellucida in mouse sperm has been shown to proceed in two stages experimentally distinguishable by the fluorescent probe chlortetracycline. Entry into the first stage of sperm bound to isolated, structurally intact zonae pellucidae is blocked by the compound 3-quinuclidinyl benzilate. In this study, we show, utilizing the fluorescent Ca2+ indicator fluo-3, that the first stage of the zona-induced acrosome reaction is characterized by an increase in intracellular Ca2+, followed by a decrease as the acrosome reaction proceeds. This calcium transient is completely suppressed by 3-quinuclidinyl benzilate. We conclude that the Ca2+ transient is induced by the zona pellucida and is required for the zona-induced acrosome reaction. Blockage of this sperm intracellular Ca2+ transient provides a mechanism for the inhibitory action of 3-quinuclidinyl benzilate on the zona-induced acrosome reaction in mouse sperm. 相似文献
102.
103.
T Okuno J Casals K H Kim D W Walton H K Shin 《Japanese journal of medical science & biology》1976,29(4):187-197
In the light of recent knowledge on a complex of diseases caused by a new group of viruses, arenaviruses, virological studies largely directed toward small field mammals were undertaken during 1973-1974 aiming at etiological clarification of Korean hemorrhagic nephrosonephritis (KHNN). Specimens were collected in an endemic area of KHNN located north to northeast of Seoul. Virus isolation tests with 299 urine specimens and 131 mite pools recovered from small mammals and 14 acute stage sera from typical cases yielded negative results. Complement-fixation (CF) tests failed to detect antibodies against the antigens of Congo, lymphocytic choriomeningitis (LCM), Tacaribe, and Pichinde viruses among 366 small mammal sera. In addition, CF tests of 59 of the above sera against Apoi and Lassa virus antigens were negative. The results do not support the likelihood of an arenavirus being transmitted among Korean small field mammals, the overwhelming majority of which were Apodemus agrarius. A hypothesis that KHNN is caused by a virus of small field mammal origin was not proved within the technical limit of relatively unsophisticated methods employed herein. 相似文献
104.
105.
Unidirectional transfer of broad host-range plasmid R1162 during conjugative mobilization. Evidence for genetically distinct events at oriT 总被引:15,自引:0,他引:15
A segment of R1162 DNA containing genes for conjugative mobilization (Mob) and the origin of transfer (oriT) was integrated into the Escherichia coli chromosome. Bacterial genes were transferred in a polar fashion during conjugative mobilization of the integrated segment by a self-transmissible plasmid vector. The direction of transfer, together with the properties of mutated derivatives of oriT, indicate that initial cleavage of oriT, and subsequent religation after transfer, entail different mechanisms that can be distinguished genetically. 相似文献
106.
T H Kim 《Applied and environmental microbiology》1977,34(5):495-499
Evidence suggests that Bacille Calmette-Guérin (BCG) vaccine for use in cancer immunotherapy should have the following characteristics: high viability which is maintained on storage; high ratio of live to dead cells; high proportion of single cells; and low content of soluble antigen. The production of a vaccine with these characteristics was accomplished by use of a deep-culture technique. The medium was modified Proskauer and Beck medium containing Tween 80 and glucose. The mass culture was grown in a Wheaton double-side-arm bottle (6 liters of medium in an 8-liter container), aerated by means of an aquarium aerator and mixed by a magnetic stirrer. The culture was incubated 7 to 9 days at 37 degrees C, concentrated 11 to 15 times by ultrafiltration, diluted with equal parts of 25% lactose, and then lyophilized. The lyophilized ampoules, stored at -70 degrees C, were cultured at intervals ranging from 3 days to 450 days, and no loss in viability was observed. The mean number of viable BCG per ml of reconstituted vaccine was 8.75 log10. The viable count was 90% of the total bacterial count. Moreover, 85% of the cells were present as single bacilli. 相似文献
107.
108.
109.
Living cells orient the cytoskeleton polarity and directional migration in response to spatial gradients of multiple types of cues. The resulting tactic behaviors are critical for the proper cell localization in the context of complex single-cell and tissue behaviors. In this perspective, we highlight the recent discovery of, to our knowledge, a new -taxis phenomenon, the topotaxis, which mediates directional cell migration in response to the gradients of such topographic features as the density of extracellular matrix fibers. The direction of topotactic migration critically depends on the effective stiffness of the cortical cytoskeleton, which is controlled by the balance between two parallel signaling pathways activated by the extracellular matrix input. Topotaxis can account for such striking cell behaviors as the opposite directionality of migration of benign and metastatic cancer cells and certain aspects of the wound-healing process. We anticipate that, in conjunction with other tactic phenomena, topotaxis can provide critical information for understanding and design of tissue structure and function. 相似文献
110.
E. M. Waite G. P. Closs † J. Kim ‡ B. Barry § A. Markwitz § R. Fitzpatrick 《Journal of fish biology》2008,72(7):1847-1854
The relationship between the strontium content of the outer layers of otoliths (an indication of recent marine, estuarine or riverine habitat use) and the strontium content of roe in ripe female brown trout Salmo trutta was examined in fish collected from the Pomahaka River and the lower reaches of the Clutha River, South Island, New Zealand. A close relationship was found between the strontium content of roe and the outer layers of otoliths. This finding suggests that spawned eggs collected from redds could potentially be used to track the extent of upstream spawning migrations by anadromous brown trout. 相似文献