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991.
992.
Yagami T Ueda K Asakura K Nakazato H Hata S Kuroda T Sakaeda T Sakaguchi G Itoh N Hashimoto Y Hori Y 《Journal of neurochemistry》2003,85(3):749-758
Mammalian group IIA secretory phospholipase A2 (sPLA2-IIA) generates prostaglandin D2 (PGD2) and triggers apoptosis in cortical neurons. However, mechanisms of PGD2 generation and apoptosis have not yet been established. Therefore, we examined how second messengers are involved in the sPLA2-IIA-induced neuronal apoptosis in primary cultures of rat cortical neurons. sPLA2-IIA potentiated a marked influx of Ca2+ into neurons before apoptosis. A calcium chelator and a blocker of the L-type voltage-sensitive Ca2+ channel (L-VSCC) prevented neurons from sPLA2-IIA-induced neuronal cell death in a concentration-dependent manner. Furthermore, the L-VSCC blocker ameliorated sPLA2-IIA-induced morphologic alterations and apoptotic features such as condensed chromatin and fragmented DNA. Other blockers of VSCCs such as N type and P/Q types did not affect the neurotoxicity of sPLA2-IIA. Blockers of L-VSCC significantly suppressed sPLA2-IIA-enhanced Ca2+ influx into neurons. Moreover, reactive oxygen species (ROS) were generated prior to apoptosis. Radical scavengers reduced not only ROS generation, but also the sPLA2-IIA-induced Ca2+ influx and apoptosis. In conclusion, we demonstrated that sPLA2-IIA potentiates the influx of Ca2+ into neurons via L-VSCC. Furthermore, the present study suggested that eicosanoids and ROS generated during arachidonic acid oxidative metabolism are involved in sPLA2-IIA-induced apoptosis in cooperation with Ca2+. 相似文献
993.
We collected systematic data on the home range and day ranges of one group of 57–63 muriquis (Brachyteles arachnoides hypoxanthus) at the Estação Biológica de Caratinga, Minas Gerais, Brazil from September 1998–July 1999, and compared them with similar data collected 15 years ago when the 23–27 individuals in the group traveled together as a cohesive unit. Home range size increased from 168 ha to 309 ha, reflecting an expansion into areas of the forest that were previously unutilized and consistent with the positive relationship predicted between group size and home range size. By contrast, muriquis exhibited remarkable seasonal and interannual stability in their day ranges. Day ranges, which were calculated from 144 days with 8 h of observation, averaged 1,313 ± 573 m (median = 1,206 m). Day ranges did not vary with the size of subgroups, defined as independent individuals that traveled with one another out of contact with other group members. Subgroups were significantly larger during the rainy season (mean = 41.8 ± 12.7, median = 46.0 individuals, n = 72) than the dry season (mean = 36.6 ± 13.25, median = 39.5 individuals, n = 72). Subgroups were also larger than the size of the entire group during the previous study, yet their day ranges are indistinguishable. The stability in muriqui day ranges is consistent with predictions for folivorous primates in which other indicators of intragroup feeding competition, such as female dominance relationships, are also absent. We attribute the transition from cohesive to fluid grouping patterns to limits on the number of individuals that can coordinate their movements when they spread out while foraging and suggest that seasonal differences in subgroup sizes without corresponding adjustments in day ranges reflect seasonal differences in the distribution of preferred foods coupled with the effects of reproductive seasonality on muriqui grouping patterns. 相似文献
994.
Ohsawa H 《Primates; journal of primatology》2003,44(2):99-107
Data on social changes in patas monkey (Erythrocebus patas) groups were collected to clarify the general characteristics of male supplantation and to evaluate the overall role of supplanting
in patas society. Seven patas groups were observed in Kala Maloue National Park, Northern Cameroon for 11 years. Analysis
of this data revealed that social change, such as male supplanting, was restricted to the mating season. Male supplanting
occurred in the course of outsider males seeking to gain access to estrous females within the heterosexual group and supplanting
was inevitably followed by a multi-male situation arising in the group. Many cases of multi-male invasion were preceded by
the supplanting of resident males and the multi-male situation arose due to a temporary absence of serious aggression towards
invader males by the new resident males. Notably, an all-male group was found only once and it did not contribute to the supplanting
of resident males in the one-male group.
Electronic Publication 相似文献
995.
A simple analytical model is presented for the prediction of methyl-side chain dynamics in comparison with S(2) order parameters obtained by NMR relaxation spectroscopy. The model, which is an extension of the local contact model for backbone order parameter prediction, uses a static 3D protein structure as input. It expresses the methyl-group S(2) order parameters as a function of local contacts of the methyl carbon with respect to the neighboring atoms in combination with the number of consecutive mobile dihedral angles between the methyl group and the protein backbone. For six out of seven proteins the prediction results are good when compared with experimentally determined methyl-group S(2) values with an average correlation coefficient r = 0.65+/-0.14. For the unusually rigid cytochrome c(2) no significant correlation between prediction and experiment is found. The presented model provides independent support for the reliability of current side-chain relaxation methods along with their interpretation by the model-free formalism. 相似文献
996.
We examined the importance of sex differences in predation risk in generating sexual segregation in the guppy, Poecilia reticulata. We hypothesised that sex differences in predation risk will result in habitat segregation and ultimately social segregation of the sexes, with the more vulnerable sex (males in this case) using safer habitats. In accordance with the predation risk hypothesis we observed sexual segregation in a population associated with high but not low predation risk. Under high predation risk we observed a larger proportion of males in shallow marginal habitats resulting in habitat segregation and ultimately social segregation of the sexes. Furthermore, habitat segregation by sex was associated with habitat segregation by body length with shoals in deeper water having a larger mean body length. Shoaling fish species have been key models in investigating group living, and further research directed towards understanding sexual segregation in other fish species would be valuable. 相似文献
997.
A rickettsial strain IO-1 has been isolated from a tick, Ixodes ovatus, in Japan and genetically identified as Rickettsia helvetica, a member of the spotted fever group rickettsiae. Ultrastructural observations were made on the microorganism. The ultrastructure of R. helvetica IO-1 appeared to be generally the same as that previously shown for other rickettsiae of the spotted fever and typhus groups. The rickettsiae were primarily found free in the cytoplasm of L929 cultured cells. Occasionally, the rickettsiae may also invade the host cell nucleus; however, the frequency of the nuclear localization was very low. 相似文献
998.
Croguennec T Bouhallab S Mollé D O'Kennedy BT Mehra R 《Biochemical and biophysical research communications》2003,301(2):465-471
The role of the free sulfhydryl group of beta-lactoglobulin in the formation of a stable non-native monomer during heat-treatment of beta-lactoglobulin solutions was investigated. Two concomitant events occurred at the earlier stage of heating: unfolding of native globular monomer and intramolecular sulfhydryl/disulfide exchange reaction. Thus, two denatured monomeric species were formed: a non-native monomer with exposed Cys-121 (Mcys121) which became reversible after cooling, and a stable non-native monomer with exposed Cys-119 (Mcys119) which exhibited both a larger hydrodynamic conformation than native monomer and low solubility at pH 4.7. The results also show that the formation of these monomeric species throughout heat-induced denaturation of native beta-lg monomers is faster than their subsequent aggregation. A mechanism describing the behavior of beta-lg denaturation/aggregation during heat-treatment under selected conditions (5.8 mg/ml, low ionic strength, pH 6.6, 85 degrees C) is presented. 相似文献
999.
Thomsen H Reinsch N Xu N Looft C Grupe S Kühn C Brockmann GA Schwerin M Leyhe-Horn B Hiendleder S Erhardt G Medjugorac I Russ I Förster M Brenig B Reinhardt F Reents R Blümel J Averdunk G Kalm E 《Animal genetics》2002,33(2):107-117
Genes determining the bovine erythrocyte antigens were mapped by linkage analysis. In total 9591 genotypes of 20 grandsire families with 1074 sires from a grand-daughter design were elucidated for the genes determining the erythrocyte antigens EAA, EAB, EAC, EAF, EAJ, EAL, EAM, EAN', EAR', EAS, EAT', and EAZ according to standard paternity testing procedures in the blood typing laboratories. Linkage analyses were performed with 248 microsatellite markers, eight SSCP markers and four polymorphic proteins and enzymes covering the 29 autosomes and the pseudoautosomal region of the sex chromosomes. The number of informative meioses for the blood group systems ranged from 76 to 947. Blood group systems EAM and EAT' were non-informative. Most of the erythrocyte antigen loci showed significant linkage to a single chromosome and were mapped unequivocally. The genes determining erythrocyte antigen EAA, EAB, EAC, EAL, and EAS were mapped to chromosomes 15, 12, 18, 3, and 21, respectively. Lod-score values ranged from 11.43 to 107.83. Moreover, the EAF system could be mapped to chromosome 17. However, the EAN' system previously known as part of the EAF system could be mapped to chromosome 5. In addition, the blood group systems EAJ, the new EAN', EAR', and EAZ, showed significant linkage to microsatellite markers on various chromosomes and also to other blood groups. The appearance of a single blood group system might be therefore either dependent on the existence of other blood group systems or because of an interaction between different loci on various chromosomes as is known in humans and in pigs. 相似文献
1000.
The effect of sodium selenite (0.05, 0.1, and 0.2 mg/kg body weight, ip) on the contents of lipids (phospholipids, cholesterol,
esterified fatty acids, gangliosides), thiobarbituric acid reactive substance (TBARS), and thiol group in circadian rhythm
centers (preoptic area, brainstem, and posterior hypothalamus) of male Wistar rats was studied after 7 d of treatment. The
content of phospholipids was elevated significantly with a dose of 0.1 mg/kg of selenite in the preoptic area and brainstem,
but a 0.2-mg/kg dose has depleted its level significantly in these regions. The alteration of phospholipids in posterior hypothalamus
was not significant with three doses of sodium selenite. The level of cholesterol in the preoptic area was inhibited significantly
with a dose of 0.05 mg/kg sodium selenite, but its level was elevated significantly with a dose of 0.2 mg/kg selenite in the
preoptic area and brainstem. Alteration with three doses of sodium selenite in the posterior hypothalamus was not significant.
The ganglioside level in the preoptic area and brainstem was elevated significantly with a 0.1-mg dose of sodium selenite;
conversely, a 0.2 mg dose of sodium selenite caused a significant depletion on its content in these areas. In the posterior
hypothalamus, the ganglioside level was depleted significantly with a dose of 0.1 mg, but elevated significantly with a dose
of 0.2 mg of sodium selenite. The level of esterified fatty acids was decreased significantly in the preoptic area and brainstem
with a dose of 0.1 mg/kg sodium selenite, but in these regions, its level was elevated with a dose of 0.2 mg/kg sodium selenite
and its elevation was significant in the preoptic area. In the posterior hypothalamus, the alteration of esterified fatty
acids with three doses of sodium selenite was not significant. The effect of 0.1 and 0.2 mg/kg sodium selenite on the TBARS
level and thiol group in sleep centers was significantly opposite to the wakefulness center. A sodium selenite dose of 0.1
mg/kg had depleted the content of TBARS in the preoptic area and brainstem but elevated the content of the thiol group significantly
in the posterior hypothalamus. On the other hand, a 0.2-mg/kg dose of sodium selenite has significantly elevated the content
of TBARS but depleted the content of the thiol group significantly in the posterior hypothalamus. No dose-dependent alteration
was observed on the content of lipids, TBARS, and thiol group in the circadian rhythm centers of rats. 相似文献