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黄鳝由间性发育转变为雄性发育的细胞生物学研究 被引量:48
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作者 肖亚梅 刘筠 《水产学报》 CAS CSCD 北大核心 1995年第4期297-304,共8页
黄鳝雄性性成熟产卵后,卵细胞败育,卵巢逐渐退化。同时,分布于生殖褶上的原始精原细胞开始生长发育,形成精小囊。这样,残留的雌性生殖细胞与发育的雄性生殖细胞共同存在于生殖囊腔内,此为黄鳝的雌雄间性发育阶段,这一阶段可分为... 黄鳝雄性性成熟产卵后,卵细胞败育,卵巢逐渐退化。同时,分布于生殖褶上的原始精原细胞开始生长发育,形成精小囊。这样,残留的雌性生殖细胞与发育的雄性生殖细胞共同存在于生殖囊腔内,此为黄鳝的雌雄间性发育阶段,这一阶段可分为早、中、晚三个时期。黄鳝雄性个体是由雌性个体通过性变化发育而来,这种性别的变化是单方向的。黄鳝的雄性性成熟发育也可以划分为六个时期(Ⅰ→Ⅳ),雄性发育为多周期类型。 展开更多
关键词 黄鳝 间性发育 发育 生殖细胞 变化
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Changing paradigm of cancer therapy:precision medicine by next-generation sequencing 被引量:3
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作者 Yuan Xue William R.Wilcox 《Cancer Biology & Medicine》 SCIE CAS CSCD 2016年第1期12-18,共7页
Precision medicine aims to identify the right drug, for the right patient, at the right dose, at the right time, which is particularly important in cancer therapy. Problems such as the variability of treatment respons... Precision medicine aims to identify the right drug, for the right patient, at the right dose, at the right time, which is particularly important in cancer therapy. Problems such as the variability of treatment response and resistance to medication have been longstanding challenges in oncology, especially for development of new medications. Solid tumors, unlike hematologic malignancies or brain tumors, are remarkably diverse in their cellular origins and developmental timing. The ability of next-generation sequencing(NGS) to analyze the comprehensive landscape of genetic alterations brings promises to diseases that have a highly complex and heterogeneous genetic composition such as cancer. Here we provide an overview of how NGS is able to facilitate precision medicine and change the paradigm of cancer therapy, especially for solid tumors, through technical advancements, molecular diagnosis, response monitoring and clinical trials. 展开更多
关键词 Precision medicine cancer therapy next-generation sequencing solid tumor
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Scale dependence in the phylogenetic relatedness of alien and native taxa 被引量:2
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作者 Chris M.McGrannachan Gillis J.Horner Melodie A.McGeoch 《Journal of Plant Ecology》 SCIE CSCD 2020年第5期601-610,共10页
Aims Darwin’s naturalization hypothesis proposes that successfully established alien species are less closely related to native species due to differences in their ecological niches.Studies have provided support both... Aims Darwin’s naturalization hypothesis proposes that successfully established alien species are less closely related to native species due to differences in their ecological niches.Studies have provided support both for and against this hypothesis.One reason for this is the tendency for phylogenetic clustering between aliens and natives at broad spatial scales with overdispersion at fine scales.However,little is known about how the phylogenetic relatedness of alien species alters the phylogenetic structure of the communities they invade,and at which spatial scales effects may manifest.Here,we examine if invaded understorey plant communities,i.e.containing both native and alien taxa,are phylogenetically clustered or overdispersed,how relatedness changes with spatial scale and how aliens affect phylogenetic patterns in understorey communities.Methods Field surveys were conducted in dry forest understorey communities in south-east Australia at five spatial scales(1,20,500,1500 and 4500 m2).Standardized effect sizes of two metrics were used to quantify phylogenetic relatedness between communities and their alien and native subcommunities,and to examine how phylogenetic patterns change with spatial scale:(i)mean pairwise distance and(ii)mean nearest taxon distance(MNTD).Important Findings Aliens were closely related to each other,and this relatedness tended to increase with scale.Native species and the full community exhibited either no clear pattern of relatedness with increasing spatial scale or were no different from random.At intermediate spatial scales(20-500 m2),the whole community tended towards random whereas the natives were strongly overdispersed and the alien subcommunity strongly clustered.This suggests that invasion by closely related aliens shifts community phylogenetic structure from overdispersed towards random.Aliens and natives were distantly related across spatial scales,supporting Darwin’s naturalization hypothesis,but only when phylogenetic distance was quantified as MNTD.Phylogenetic dissimilarity between aliens and natives increased with spatial scale,counter to expected patterns.Our findings suggest that the strong phylogenetic clustering of aliens is driven by human-mediated introductions involving closely related taxa that can establish and spread successfully.Unexpected scale-dependent patterns of phylogenetic relatedness may result from stochastic processes such as fire and dispersal events and suggest that competition and habitat filtering do not exclusively dominate phylogenetic relationships at fine and coarse spatial scales,respectively.Distinguishing between metrics that focus on different evolutionary depths is important,as different metrics can exhibit different scale-dependent patterns. 展开更多
关键词 alien species community phylogenetics Darwin’s naturalization hypothesis spatial scale phylogenetic beta diversity
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