The Actin Cytoskeleton and Signaling Network during Pollen Tube Tip Growth

The organization and dynamics of the actin cytoskeleton play key roles in many aspects of plant cell development. The actin cytoskeleton responds to internal developmental cues and environmental signals and is involved in cell division, subcellular organelle movement, cell polarity and polar cell growth. The tipgrowing pollen tubes provide an ideal model system to investigate fundamental mechanisms of underlying polarized cell growth. In this system, most signaling cascades required for tip growth...     

Palmin诱导烟草氧化猝发的机制

为探讨植物对病原微生物的防御机制和激发子启动植物体内的信号转导应答过程 ,本文研究了Phytoph thorapalmi激发子palmin诱导其非寄主亲和性烟草的叶片和悬浮细胞系产生氧化猝发的分子机理。利用生化分析和激光共聚焦显微扫描技术动态观察palmin诱导烟草过敏反应中O·- 2 和H2 O2 的形成、胞间转移及引起细胞死亡的特性。结果表明 :palmin诱导激活了烟草细胞内NADPH氧化酶 ,产生大量的O·- 2 ;O·- 2 在SOD催化下迅速转变成H2 O2 ,并且H2 O2 在一定范围的细胞间转移和积累 ,最后诱发烟草细胞的过敏性坏死反应。palmin诱导氧化猝发过程还有Ca2 和蛋白激酶的参与。     

Anatomical and functional evidence for a stress-responsive,monoamine-accumulating area in the dorsomedial hypothalamus of adult rat brain

The dorsomedial hypothalamus (DMH) plays an important role in relaying information to neural pathways mediating neuroendocrine, autonomic, and behavioral responses to stress. Evidence suggests that the DMH is a structurally and functionally diverse integrative structure that contributes to both facilitation and inhibition of the hypothalamo-pituitary-adrenal axis, depending on the nature of the stimulus and the specific neural circuits involved. Previous studies have determined that stress or stress-related stimuli elevate tissue concentrations of serotonin (5-hydroxytryptamine; 5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine, and noradrenaline selectively within the DMH. In order to determine the specific region of the rat DMH involved, we used high-performance liquid chromatography with electrochemical detection to measure tissue concentrations of 5-HT, 5-HIAA, dopamine, and noradrenaline within five different subregions of the DMH in adult female Lewis and Fischer rats immediately or 4 h following a 30-min period of restraint stress. Compared to unrestrained control rats, restrained rats had elevated concentrations of 5-HT, 5-HIAA, dopamine, and noradrenaline immediately after a 30-min period of restraint and had elevated concentrations of 5-HT 4 h following the onset of a 30-min period of restraint stress. These effects were confined to a specific region that included medial portions of the dorsal hypothalamic area and dorsal ependymal, subependymal, and neuronal components of the periventricular nucleus. Furthermore, these effects were observed in Lewis rats, but not Fischer rats, two closely related rat strains with well-documented differences in neurochemical, neuroendocrine, autonomic, and behavioral responses to stress. These data provide support for the existence of a stress-responsive, amine-accumulating area in the DMH that may play an important role in the differential stress responsiveness of Lewis and Fischer rats.     

The Plant Ontology Consortium and plant ontologies

The goal of the Plant Ontology Consortium is to produce structured controlled vocabularies, arranged in ontologies, that can be applied to plant-based database information even as knowledge of the biology of the relevant plant taxa (e.g. development, anatomy, morphology, genomics, proteomics) is accumulating and changing. The collaborators of the Plant Ontology Consortium (POC) represent a number of core participant database groups. The Plant Ontology Consortium is expanding the paradigm of the Gene Ontology Consortium (http://www.geneontology.org). Various trait ontologies (agronomic traits, mutant phenotypes, phenotypes, traits, and QTL) and plant ontologies (plant development, anatomy [incl. morphology]) for several taxa (Arabidopsis, maize/corn/Zea mays and rice/Oryza) are under development. The products of the Plant Ontology Consortium will be open-source.     

A polarity complex of mPar-6 and atypical PKC binds,phosphorylates and regulates mammalian Lgl

The evolutionarily conserved proteins Par-6, atypical protein kinase C (aPKC), Cdc42 and Par-3 associate to regulate cell polarity and asymmetric cell division, but the downstream targets of this complex are largely unknown. Here we identify direct physiological interactions between mammalian aPKC, murine Par-6C (mPar-6C) and Mlgl, the mammalian orthologue of the Drosophila melanogaster tumour suppressor Lethal (2) giant larvae. In cultured cell lines and in mouse brain, aPKC, mPar-6C and Mlgl form a multiprotein complex in which Mlgl is targeted for phosphorylation on conserved serine residues. These phosphorylation sites are important for embryonic fibroblasts to polarize correctly in response to wounding and may regulate the ability of Mlgl to direct protein trafficking. Our data provide a direct physical and regulatory link between proteins of distinct polarity complexes, identify Mlgl as a functional substrate for aPKC in cell polarization and indicate that aPKC is directed to cell polarity substrates through a network of protein-protein interactions.     

Control and statistical analysis of in vitro reporter gene assays

The use of in vitro gene reporter assays is becoming increasingly widespread in biology and particularly in drug metabolism, where the need for rapid screening of novel compounds is a driving factor. There is, however, little standardization of technique in the control of such assays, nor in the interpretation of results. This leads to confusion in the literature, with the possibility of a single piece of data being interpreted by several different methods, potentially giving vastly differing results. We have developed a reporter gene assay methodology that controls for many biological and experimental variables in the system and allows the application of a mathematical model to determine statistical significance between groups. Use of this methodology, we feel, allows an accurate and reproducible method of analyzing in vitro reporter gene assay data and increases its value as a biological tool.     

Surface plasmon resonance imaging of cells and surface-associated fibronectin

Background  

A critical challenge in cell biology is quantifying the interactions of cells with their extracellular matrix (ECM) environment and the active remodeling by cells of their ECM. Fluorescence microscopy is a commonly employed technique for examining cell-matrix interactions. A label-free imaging method would provide an alternative that would eliminate the requirement of transfected cells and modified biological molecules, and if collected nondestructively, would allow long term observation and analysis of live cells.     

几种生理因素对玉米木质部汁液中蛋白质含量的影响

受干旱胁迫的玉米叶和茎木质部汁液中蛋白质含量降低,根中蛋白质含量升高.偏酸性营养液中的玉米各营养器官木质部汁液中蛋白质含量降低,中性或碱性营养液中的则升高.以100mmol·L-1的ABA营养液处理后的玉米根、茎和叶片的木质部汁液中蛋白质含量都升高;而用2 mmol·L-1EGTA、80 mmol·L-1三氟啦嗪或100mmol·L-1异博定处理后的木质部汁液中蛋白质含量变化不明显.