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511.
During the non-reproductive season, male and female Corythoichthys haematopterus came to a particular site every early morning and performed a series of displays, called greetings, for a few minutes. After
exchanging greetings, they had no further interactions during the daytime. This behavioural pattern was basically the same
as that observed during the reproductive season. All greeting pairs bred in the following reproductive season if both members
were present. These results indicate that mate fidelity of this pipefish is very high and that daily greetings lasting only
a few minutes were enough to maintain pair bond all year around. 相似文献
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A small crabZebrida adamsii, an obligate symbiont of the sea urchin, lives solitary on a host from the earliest stage of its benthic life. In the breeding
season males frequently move between hosts to search for mates. Analysis of daily positional changes of individually marked
crabs indicates that males often land on the substrate to migrate between separate hosts. Females also change hosts before
they copulate, but after oviposition they stay on the same hosts for a long time, similarly to crabs in the nonbreeding season. 相似文献
516.
Superantigens are known to induce clonal anergy and/or deletion in reactive T cells peripherally. This study was undertaken to investigate the T-cell status early after exposure to staphylococcal enterotoxin A (SEA) in vivo and in vitro. At the peak of clonal expansion following the administration of 5 μg SEA (i.e., 2 days after the injection), C57BL/6 mice were rechallenged with the same dose of SEA in vivo. The secondary stimulation augmented clonal expansion of the T cells bearing Vβ3 and Vβ11 in both CD4+ and CD8+ populations. In vitro restimulation of the spleen cells taken from the SEA-primed mice also induced further expansion of the Vβ3+ T cells during 2 days of culturing, whereas without restimulation, a marked reduction of Vβ3+ T cells occurred. The spleen cells from the SEA-primed mice were hyper-reactive to in vitro restimulation with SEA as measured by 3H-TdR uptake on day 1 of culturing, but augmented proliferation leveled off thereafter. By day 3, the values of 3H-TdR uptake were less than 20% of those of the controls in which spleen cells from native mice were stimulated with SEA in vitro. These results suggest that T cells exposed to SEA in vivo are still capable of proliferating upon SEA rechallenge, but subsequently, the proliferation starts to wane. 相似文献
517.
Shinji Murosaki Kyoko Inagaki-Ohara Hiroaki Kusaka Hitoshi Ikeda Yasunobu Yoshikai 《Microbiology and immunology》1997,41(2):139-148
To investigate the effect of glucocorticoids on apoptosis in intestinal intraepithelial lymphocytes (i-IEL), we examined the changes of i-IEL followed by in vivo treatment with dexamethasone. The fragmented DNA of i-IEL were significantly increased at 15 hr after dexamethasone treatment and, subsequently, the number of total i-IEL were decreased by day 4 after treatment. Although all subsets of i-IEL including CD8α/α+, CD8α/β+, CD4+ and CD4+ CD8+ i-IEL were decreased after dexamethasone treatment, CD8α/α+ i-IEL appeared to be relatively resistant to dexamethasone-induced apoptosis. Consistent with the in vivo findings, CD8α/α+ i-IEL exhibited less susceptibility to dexamethasone-induced cell death in vitro than other subsets. To investigate whether this process occurs under physiological conditions, we examined the kinetics of i-IEL after treatment with 15-hr water immersion stress. In mice subjected to water immersion stress, plasma glucocorticoids were remarkably elevated soon after the 15-hr stress. The increase in the fragmented DNA of i-IEL and subsequent decrease in the number of i-IEL were observed in the stressed mice in the same kinetics as seen in the dexamethasone-treated mice. Similar to dexamethasone-induced cell death, CD8α/α+ i-IEL appeared to be relatively resistant to stress-induced apoptosis compared with other i-IEL subsets. The expression level of Bcl-2 was significantly higher in CD8α/α+ i-IEL than in CD8α/β+ i-IEL. Our results indicate that i-IEL are subjected to cell death via apoptosis by exogenous and endogenous glucocorticoids and that different sensitivity to steroid-induced apoptosis may exist among i-IEL subsets in relation to their Bcl-2 expression. 相似文献
518.
Tomonori Osugi Yasunobu Yanagisawa Nobuhiko Mizuno 《Environmental Biology of Fishes》1998,52(1-3):331-343
The social structure and feeding behaviour of the benthic goby Rhinogobius sp. DA (dark type) were investigated in a small river in Shikoku, Japan, where nektonic fishes are absent. The gobies had overlapped home ranges but were often aggressive against conspecifics, especially of the same sex and similar body size. Their diet consisted mainly of aquatic invertebrates, but terrestrial invertebrates were also an important item. This contrasted with few terrestrial invertebrates in the diet of the conspecifics in an adjacent river harbouring a nektonic cyprinid fish. An increase in flow level greatly changed their feeding behaviour; on high flow days, a greater portion of the population appeared from the interstices of the bottom and more often rose into the water column to catch drift than on normal flow days. Plasticity of their feeding behaviour is discussed in terms of ecological release. 相似文献