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71.
The adaptive function of trophic egg-laying is generally regarded as extended parental investment to the offspring. However, the evolutionary factors promoting trophic egg-laying are still unclear, because the amount of maternal investment per offspring should be ideally equal between smaller offspring with trophic eggs and larger offspring without any additional investment. Several authors have suggested that trophic egg-laying should evolve only when egg size is constrained, but this hypothesis has not been evaluated. We investigated the evolutionary mechanisms of trophic egg-laying by two different approaches. First, we evaluated morphological constraints on egg size in two sibling ladybird species, Harmonia axyridis, which is known to produce trophic eggs, and H. yedoensis. Second, we theoretically predicted the optimal proportion of trophic eggs to total eggs and egg size in relation to environmental heterogeneity, predictability of environmental quality, and investment efficiency of trophic egg consumption. The intra- and interspecific morphological comparisons suggest that morphological constraints on the evolutionary determination of egg size are weak at best in the two ladybird species. Moreover, we theoretically showed that small egg size and trophic egg-laying are favoured in heterogeneous environments when mothers cannot adjust egg size plastically. We also showed that even a small reduction in investment efficiency makes a trophic egg strategy unlikely, despite relatively high environmental predictability. We conclude that trophic egg provisioning may be a flexible maternal adaptation to a highly heterogeneous environment rather than a response to a morphological constraint on egg size. 相似文献
72.
Atsushi Tohei Yasuyuki Mogi Hiroe Kon Ryoji Hokao Motoo Shinoda 《Experimental Animals》2003,52(5):437-439
In the present study, we used closed colony-Wistar-Imamichi (WI), inbred WI and Long Evans (LE) adult male rats to examine the secretion of ACTH and corticosterone in response to restraint stress. Blood (0.3 ml) was withdrawn through a jugular cannula at 0, 15, 30, 60 and 120 min after the onset of restraint stress. Plasma concentrations of ACTH and corticosterone increased after stress in all groups, but the responses of ACTH and corticosterone secretion were higher in LE rats than in WI rats. Present data suggest that the LE rat might be a good model as a high-response strain and the closed colony or the inbred WI rat might be a good model as a low-response strain in restraint stress experiments. 相似文献
73.
Yoshino H Sato H Shiraishi T Tachibana K Emura T Honma A Ishikura N Tsunenari T Watanabe M Nishimoto A Nakamura R Nakagawa T Ohta M Takata N Furumoto K Kimura K Kawata H 《Bioorganic & medicinal chemistry》2010,18(23):8150-8157
A series of 5,5-dimethylthiohydantoin derivatives were synthesized and evaluated for androgen receptor pure antagonistic activities for the treatment of castration-resistant prostate cancer. Since CH4933468, which we reported previously, had a problem with agonist metabolites, novel thiohydantoin derivatives were identified by applying two strategies. One was the replacement of the alkylsulfonamide moiety by a phenylsulfonamide to avoid the production of agonist metabolites. The other was the replacement of the phenyl ring with a pyridine ring to improve in vivo potency and reduce hERG affinity. Pharmacological assays indicated that CH5137291 (17b) was a potent AR pure antagonist which did not produce the agonist metabolite. Moreover, CH5137291 completely inhibited in vivo tumor growth of LNCaP-BC2, a castration-resistant prostate cancer model. 相似文献
74.
The response of large calanoid, Eucalanus bungii, to environmental fluctuation, particularly in relation to the spring diatom bloom in the Oyashio region, western subarctic
Pacific Ocean, was examined by investigating egg production, grazing, development and starvation tolerance. Mean in situ egg
production rate increased with ambient chlorophyll-a concentration, ranging from 0 to 47 eggs female−1 d−1, while no diurnal synchronous spawning behavior was observed. Under the spring bloom condition, E. bungii showed prey preference for less mobile and larger-sized prey (≥30 μm ESD) and bloom-forming diatom Thalassiosira spp. accounted for >80% of ingested carbon. In the laboratory, E. bungii was successfully reared from newly hatched nauplii to adult with the diatom, Thalassiosira
nordenskioldi, as a food resource. Nauplii newly hatched from eggs reached the adult stage in ca. 150 days (5°C) with a sigmoidal developmental
pattern and no sexual difference in development pattern. Starvation experiments indicated that the starved copepodids (C1–C4)
became more vulnerable to high temperature with the progression of developmental stage, suggesting that the post-bloom condition
with low food availability and increased temperature is harsh for their copepodids. The results of this study in conjunction
with previous findings suggest that E. bungii is well adapted to utilize large-sized phytoplankton, such as a bloom-forming diatoms and, therefore, their recruitment processes,
including egg production, development and mortality would be strongly affected by the duration and intensity of the spring
bloom. 相似文献
75.
Nomura T Yamamoto H Shiino T Takahashi N Nakane T Iwamoto N Ishii H Tsukamoto T Kawada M Matsuoka S Takeda A Terahara K Tsunetsugu-Yokota Y Iwata-Yoshikawa N Hasegawa H Sata T Naruse TK Kimura A Matano T 《Journal of virology》2012,86(12):6481-6490
Nonhuman primate AIDS models are essential for the analysis of AIDS pathogenesis and the evaluation of vaccine efficacy. Multiple studies on human immunodeficiency virus and simian immunodeficiency virus (SIV) infection have indicated the association of major histocompatibility complex class I (MHC-I) genotypes with rapid or slow AIDS progression. The accumulation of macaque groups that share not only a single MHC-I allele but also an MHC-I haplotype consisting of multiple polymorphic MHC-I loci would greatly contribute to the progress of AIDS research. Here, we investigated SIVmac239 infections in four groups of Burmese rhesus macaques sharing individual MHC-I haplotypes, referred to as A, E, B, and J. Out of 20 macaques belonging to A(+) (n = 6), E(+) (n = 6), B(+) (n = 4), and J(+) (n = 4) groups, 18 showed persistent viremia. Fifteen of them developed AIDS in 0.5 to 4 years, with the remaining three at 1 or 2 years under observation. A(+) animals, including two controllers, showed slower disease progression, whereas J(+) animals exhibited rapid progression. E(+) and B(+) animals showed intermediate plasma viral loads and survival periods. Gag-specific CD8(+) T-cell responses were efficiently induced in A(+) animals, while Nef-specific CD8(+) T-cell responses were in A(+), E(+), and B(+) animals. Multiple comparisons among these groups revealed significant differences in survival periods, peripheral CD4(+) T-cell decline, and SIV-specific CD4(+) T-cell polyfunctionality in the chronic phase. This study indicates the association of MHC-I haplotypes with AIDS progression and presents an AIDS model facilitating the analysis of virus-host immune interaction. 相似文献
76.
Reevaluation and Reduction of a PCR Bias Caused by Reannealing of Templates 总被引:3,自引:1,他引:3 下载免费PDF全文
Shinya Kurata Takahiro Kanagawa Yukio Magariyama Kyoko Takatsu Kazutaka Yamada Toyokazu Yokomaku Yoichi Kamagata 《Applied microbiology》2004,70(12):7545-7549
We reevaluated the bias toward a 1:1 ratio of products in multitemplate PCR used in ecological studies and showed that the template reannealing at the annealing step would not cause the bias; however, the preferential homoduplex formation during temperature decrease from denaturation to annealing step would cause the bias. 相似文献
77.
Hosoe T Nozawa K Kawahara N Fukushima K Nishimura K Miyaji M Kawai K 《Mycopathologia》1999,146(1):9-12
An indole derivative, schizocommunin, was isolated along with indigotin (indigo), indirubin, isatin, and tryptanthrin, from
the liquid culture medium in which a culture of Schizophyllum commune, isolated from the bronchus of a human patient with allergic bronchopulmonary mycosis, had been grown. The structure of schizocommunin
was established by spectroscopic investigation. Schizocommunin showed the strong cytotoxicity against murine lymphoma cells.
The assignments of the 1H- and 13C-NMR signals of indigotin were also listed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
78.
Multiple targeted gene replacements are often required for functional analyses of cyanobacterial genomes. For this purpose, we previously devised a simple genetic method, termed rps12-mediated gene replacement, in a cyanobacterium Synechococcus elongatus PCC 7942 for construction of mutants free from drug resistance markers. Here, we improved the method by employing a heterologous rps12 gene encoding a ribosomal protein S12 from Synechocystis sp. PCC 6803. Dominant streptomycin-sensitive phenotype of the Synechocystis rps12 gene was manifested only when it was expressed under the strong promoter of psbAI gene in S. elongatus PCC 7942 bearing a streptomycin-resistant rps12 allele. Transformation of the rps12 heteroallelic strains with non-replicating template plasmids permitted the selection of recombinants with gene replacement at frequencies up to 50% among streptomycin-resistant progeny. 相似文献
79.
Promyelocytic leukemia nuclear bodies (PML-NBs) comprise multiple regulatory factors and play crucial roles in the maintenance of cellular integrity, while unregulated activation of PML-NBs induces death and premature senescence. Hence, the function of PML-NBs must be directed properly; however, the mechanism that regulates PML-NBs remains unclear. In this paper, we show that PML-NBs are disintegrated by an AT-rich interaction domain family protein E2FBP1/hDril1 through specific desumoylation of promyelocytic leukemia protein (PML) in vivo and in vitro. RNA interference-mediated downregulation of E2FBP1/hDril1 results in hyperplasis of PML-NBs and consequent commitment to PML-dependent premature senescence. Thus, the function of E2FBP1/hDril1 is required for maintenance of survival potential of the cells. Our data suggest a novel mechanism to govern cellular integrity through the modulation of nuclear depots. 相似文献
80.
Electromyographic analysis of walking in water in healthy humans 总被引:2,自引:0,他引:2
Masumoto K Takasugi S Hotta N Fujishima K Iwamoto Y 《Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science》2004,23(4):119-127
This study was designed to describe and clarify muscle activities which occur while walking in water. Surface electromyography (EMG) was used to evaluate muscle activities in six healthy subjects (mean age, 23.3 +/- 1.4 years) while they walked on a treadmill in water (with or without a water current) immersed to the level of the xiphoid process, and while they walked on a treadmill on dry land. The trials in water utilized the Flowmill which has a treadmill at the base of a water flume. Integrated EMG analysis was conducted for the quantification of muscle activities. In order to calculate the %MVC, the measurement of maximal voluntary contraction (MVC) of each muscle was made before the gait analysis, thus facilitating a comparison of muscle activities while walking in water with those on dry land. The %MVCs obtained from each of the tested muscles while walking in water, both with and without a water current, were all found to be lower than those obtained while walking on dry land at a level of heart rate response similar to that used when walking on dry land. Furthermore, the %MVCs while walking in water with a water current tended to be greater when compared to those while walking in water without a water current. In conclusion, the present study demonstrated that muscle activities while walking in water were significantly decreased when compared to muscle activities while walking on dry land, that muscle activities while walking in water tended to be greater with a water current than without, and that the magnitude of the muscle activity in water was relatively small in healthy humans. This information is important to design water-based exercise programs that can be safely applied for rehabilitative and recreational purposes. 相似文献