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991.
Competition matters: Determining the drivers of land snail community assembly among limestone karst areas in northern Vietnam
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Parm Viktor von Oheimb Katharina C. M. von Oheimb Takahiro Hirano Tu Van Do Hao Van Luong Jonathan Ablett Sang Van Pham Fred Naggs 《Ecology and evolution》2018,8(8):4136-4149
The insular limestone karsts of northern Vietnam harbor a very rich biodiversity. Many taxa are strongly associated with these environments, and individual species communities can differ considerably among karst areas. The exact processes that have shaped the biotic composition of these habitats, however, remain largely unknown. In this study, the role of two major processes for the assembly of snail communities on limestone karsts was investigated, interspecific competition and filtering of taxa due to geographical factors. Communities of operculate land snails of the genus Cyclophorus were studied using the dry and fluid‐preserved specimen collections of the Natural History Museum, London. Phylogenetic distances (based on a Bayesian analysis using DNA sequence data) and shell characters (based on 200 semilandmarks) were used as proxies for ecological similarity and were analyzed to reveal patterns of overdispersion (indicating competition) or clustering (indicating filtering) in observed communities compared to random communities. Among the seven studied karst areas, a total of 15 Cyclophorus lineages were found. Unique communities were present in each area. The analyses revealed phylogenetic overdispersion in six and morphological overdispersion in four of seven karst areas. The pattern of frequent phylogenetic overdispersion indicated that competition among lineages is the major process shaping the Cyclophorus communities studied. The Coastal Area, which was phylogenetically overdispersed, showed a clear morphological clustering, which could have been caused by similar ecological adaptations among taxa in this environment. Only the community in the Cuc Phuong Area showed a pattern of phylogenetic clustering, which was partly caused by an absence of a certain, phylogenetically very distinct group in this region. Filtering due to geographical factors could have been involved here. This study shows how museum collections can be used to examine community assembly and contributes to the understanding of the processes that have shaped karst communities in Vietnam. 相似文献
992.
Takahiro Ito Yee Voan Teo Shane A. Evans Nicola Neretti John M. Sedivy 《Cell reports》2018,22(13):3480-3492
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994.
Takashi Seino Shintaro Kawasaki Mariko Shimokawa Hiroki Tamagawa Kohta Toshimitsu Masayuki Fujii Yuki Ohta Mami Matano Kosaku Nanki Kenta Kawasaki Sirirat Takahashi Shinya Sugimoto Eisuke Iwasaki Junichi Takagi Takao Itoi Minoru Kitago Yuko Kitagawa Takanori Kanai Toshiro Sato 《Cell Stem Cell》2018,22(3):454-467.e6
995.
Differentiation of female chicken primordial germ cells into spermatozoa in male gonads 总被引:2,自引:0,他引:2
Takahiro Tagami Yuko Matsubara Hirofumi Hanada Mitsuru Naito 《Development, growth & differentiation》1997,39(3):267-271
In avian species, the developmental fate of different-sex germ cells in the gonads is unclear. The present study attempted to confirm whether genetically female germ cells can differentiate into spermatozoa in male gonads using male germline chimeric chickens produced by the transfer of primordial germ cells (PGC), and employing molecular biological methods. As a result of Southern hybridization, specific sequences of the W chromosome (the female specific sex chromosome in birds) were detected in the genomic DNA extracted from one out of four male germline chimeric chickens. When two-color in situ hybridization was conducted on the spermatozoa of this germline chimera, 0.33% (average) of the nuclei of each semen sample showed the fluorescent signal indicating the presence of the W chromosome. The present study shows that female PGC can differentiate into spermatozoa in male gonads in the chicken. However, the ratio of produced W chromosome-bearing (W-bearing) spermatozoa fell substantially below expectations. It is therefore concluded that most of the W-bearing PGC could not differentiate into spermatozoa because of restricted spermatogenesis. 相似文献
996.
Emiko Isogai Kimiharu Hirose Koichi Kimura Shunji Hayashi Toru Kubota Nobuhiro Fujii Hiroshi Isogai 《Microbiology and immunology》1997,41(3):271-275
Leptospire lipopolysaccharide (LPS) stimulated the adherence of polymorphonuclear neutrophils (PMNs) to human umbilical vein endothelial cells (HUVEC). Enhanced PMN adherence in response to leptospire LPS can be mediated by platelet-activator-factor (PAF), because a PAF antagonist reduced adherence. Leptospire LPS also induced the adherence platelets or U937. The second experiment involved leptospire LPS elicited platelet aggregation in a PMN-platelet mixture, because leptospire LPS stimulated human PMN but not the human platelets. The platelet response was observed only in the mixture system and was inhibited by a PAF antagonist. PAF could be an important pathogenic factor in human leptospirosis. 相似文献
997.
Amounts of several metabolites were measured in overwintering larvae of Enosima leucotaeniella acclimated to temperatures between -5 and 15 degrees C for 30days. In the diapausing stage, cold hardiness, as shown by the survival rate, began rising below 15 degrees C. Glycogen content decreased as the temperature decreased from 10 to 0 degrees C. Trehalose content rose as the temperature decreased from 15 to 5 degrees C, but remained unchanged as the temperature decreased from 5 and 0 degrees C. Twenty-eight free amino acids were detected in the haemolymph; levels of proline, glutamine and glutamic acid increased at high temperatures, but alanine increased at low temperatures, especially as temperature decreased from 5 to 0 degrees C. Lipid content was unchanged by the different acclimation temperatures. The effects of temperature, diapause and aerobic conditions on the levels of carbohydrates and amino acids in overwintering larvae were analyzed. Alanine levels rose at low temperature only when the larvae were in the diapausing stage. The level of trehalose rose at low temperature in both the diapausing and post-diapausing stages, although it was higher at aerobic conditions in the post-diapausing stage. These results suggest that efficient trehalose synthesis occurs under the combination of low temperature and aerobic conditions of the post-diapausing stage, so that cold hardiness in overwintering E. leucotaeniella larvae may rise to a high level in winter. 相似文献
998.
Kamimura Yasumaro; Mori Takahiro; Yamasaki Takenobu; Katoh Sakae 《Plant & cell physiology》1997,38(2):133-138
A water-soluble Chl a/b-protein (CP673) was isolated and purifiedfrom Brussels sprouts (Brassica oleracea L. var. gemmifera DC).The protein had a molecular mass of 78 kDa and an isoelectricpoint of 4.7, consisted of three or four subunits of 22 kDaand was extremely heat-stable. Although CP673 contained aboutone Chl a per protein, the blue and red absorption bands ofChl a that consisted of three or four Chl a forms with differentabsorption maxima suggested that there are several differentmodes or sites of binding for Chl a. Chl a/b ratio of largerthan 10 also indicated that Chl b is present only in a smallfraction of CP673. The heterogeneity of CP673 in terms of compositionand binding of Chl suggests that Chl is not an intrinsic componentof the Chl-protein. Homology search showed that the N-terminalamino acid sequence of CP673 is highly homologous with thatof a 22 kDa protein that accumulates in water-stressed leavesof two Brassicaceae plants, rapeseed and radish, but not withthose of the light-harvesting Chl a/b-proteins of photosynthesis.A possible function of the water-soluble Chl-protein was discussed. (Received September 17, 1996; Accepted November 18, 1996) 相似文献
999.
Recording of mitochondrial transmembrane potential and volume in cultured rat osteoclasts by confocal laser scanning microscopy 总被引:2,自引:0,他引:2
H. Fujii S. H. Cody U. Seydel J. M. Papadimitriou D. J. Wood M.-H. Zheng 《Journal of molecular histology》1997,29(8):571-581
Osteoclasts are multinuclear bone-resorbing cells which contain abundant mitochondria. Morphological studies have suggested
that a correlation may exist between mitochondrial concentration and bone resorption by osteoclasts. However, investigation
of mitochondrial transmembrane potential (Delta rho) and volume has been hampered by the difficulty in obtaining a sufficient
number of osteoclasts for assessing these characteristics by flow cytometric analysis. In this study, we have used confocal
laser scanning microscopy after loading the cells with Rhodamine 123 and 10-nonyl Acridine Orange to record mitochondrial
Delta rho and volume, respectively, in isolated rat osteoclasts cultured on bovine bone slices. Optimal staining conditions
were found to be 10 mu g ml-1 for 40 min for Rhodamine, and 1 mu S mD for 10 min for the 10-nonyl Acridine Orange derivative.
Two osteoclast populations, whose shape seemed to reflect bone resorption and migratory functions, were identified depending
on their shape and on the distribution of the two dye probes. ‘Round-shaped’ osteoclasts had significantly higher mitochondrial
Delta rho and volume in the apical regions than in the basolateral portions (p 0.00001). In contrast, mitochondrial Delta
rho and volume in ‘irregular- shaped’ osteoclasts were rather evenly distributed in both these regions (p > 0.05). Our results
indicate that there is an apical polarization of mitochondria in osteoclasts corresponding to the energy demands associated
with bone resorption.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
1000.