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显花植物的受精涉及许多识别过程;其中第一个是雌性生殖组织心皮对花粉的识别。自交不亲和性(Self-incompatibility,SI)是一种广泛分布于显花植物的种内生殖障碍。在多数自交不亲和的植物中,SI的遗传控制比较简单,受控于一个由复等位基因构成的单一位点,称为S位点。在以茄科、玄参科和蔷薇科为代表的配子体自交不亲和植物中,S位点编码一类核酸酶,即S核酸酶(Fig.1),控制SI在花柱中的表达,但是与花粉自交不亲和性的表达无关。后者可能由与S核酸酶不同的基因控制,这种基因常被称为花粉S基因。它是目前了解显花植物花粉识别生化和分子机理的关键。近来;通过对影响花粉SI表达突变体的分子遗传分析提出了一个花粉S基因产物如何与S核酸酶相互作用完成自体和异体花粉识别过程的模型(Fig.2)。另外,描述了两个在金鱼草中克隆花粉S基因的方法,即S位点选择性的转座子标记和图位克隆。  相似文献   

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In this longitudinal developmental study, 12 boys and 12 girls provided home dreams and waking fantasies at 3 age levels: 9–11, 11–13, and 13–15. A total of 299 dreams and 286 fantasies were coded by 2 independent raters using Hall and Van de Castle (1966) content categories. In addition, word counts and bizarreness ratings were completed. There were very few changes in the dreams or waking fantasies of either boys or girls, but dream reports were longer at ages 13–15, the aggression/friendliness percent increased over the course of the study, joint-sex peer groups became more frequent, and girls showed a decline in animal percent. The tendency in a wide range of societies for men to dream mostly about other men and for women to dream equally of women and men was found in both the dreams and waking fantasies. Dreams and fantasies differed markedly, with dreams containing more outdoor and unfamiliar settings, and more bizarreness. In dreams the children tended to portray themselves as victims of aggression and recipients of friendliness, but in fantasies they took a more active role as aggressors and befrienders. It is suggested that the children in this study portrayed themselves in their dreams as they conceived of themselves in everyday life, while in their waking fantasies they imagined themselves as they would have liked to be.  相似文献   

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microRNAs (miRNAs) are small RNA molecules controlling messenger RNA (mRNA) and protein abundance. Since their discovery, research has been aimed at identifying the functions and target genes of miRNAs. A number of computer algorithms have been developed capable of predicting putative targets for any given miRNA. However, they might predict many false-positive targets and on top of that some true targets could be missed. This reflects the incomplete knowledge we still have concerning the rules governing true and effective miRNA-mRNA interactions. To experimentally identify miRNA-target genes, we have recently developed a genetic approach and employed it on p27Kip1, a hapo-insufficient tumor suppressor and cell cycle inhibitor. Here we review the difficulties interpreting the data from available computer algorithms, and critically address the pros and cons of our genetic screening method. Additionally, we focus on the different ways in which p27 is managed, argue how miRNAs could be involved in the regulation of p27 in both normal and malignant conditions, and discuss possible use of this knowledge for cancer therapy.  相似文献   

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Plants are continually facing biotic and abiotic stresses, and hence, they need to respond and adapt to survive. Plant response during multiple and combined biotic and abiotic stresses is highly complex and varied than the individual stress. These stresses resulted alteration of plant behavior through regulating the levels of microRNA, heat shock proteins, epigenetic variations. These variations can cause many adverse effects on the growth and development of the plant. Further, in natural conditions, several abiotic stresses causing factors make the plant more susceptible to pathogens infections and vice-versa. A very intricate and multifaceted interactions of various biomolecules are involved in metabolic pathways that can direct towards a cross-tolerance and improvement of plant’s defence system. Systems biology approach plays a significant role in the investigation of these molecular interactions. The valuable information obtained by systems biology will help to develop stress-resistant plant varieties against multiple stresses. Thus, this review aims to decipher various multilevel interactions at the molecular level under combinatorial biotic and abiotic stresses and the role of systems biology to understand these molecular interactions.  相似文献   

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The Molecular Biology Database Collection: 2002 update   总被引:5,自引:0,他引:5       下载免费PDF全文
The Molecular Biology Database Collection is an online resource listing key databases of value to the biological community. This Collection is intended to bring fellow scientists’ attention to high-quality databases that are available throughout the world, rather than just be a lengthy listing of all available databases. As such, this up-to-date listing is intended to serve as the initial point from which to find specialized databases that may be of use in biological research. The databases included in this Collection provide new value to the underlying data by virtue of curation, new data connections or other innovative approaches. Short, searchable summaries and updates for each of the databases included in the Collection are available through the Nucleic Acids Research Web site at http://nar.oupjournals.org.  相似文献   

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植物离子通道特征、功能、调节与分子生物学   总被引:6,自引:1,他引:6  
本文对植物离子通道的特征、生理功能、影响通道启闭的因素和通道分子生物学研究的新进展作了较为系统的综述  相似文献   

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