Stem-cell-triggered immunity through CLV3p-FLS2 signalling

Stem cells in the shoot apical meristem (SAM) of plants are the self-renewable reservoir for leaf, stem and flower organogenesis. In nature, disease-free plants can be regenerated from SAM despite infections elsewhere, which underlies a horticultural practice for decades. However, the molecular basis of the SAM immunity remains unclear. Here we show that the CLAVATA3 peptide (CLV3p), expressed and secreted from stem cells and functioning as a key regulator of stem-cell homeostasis in the SAM of Arabidopsis, can trigger immune signalling and pathogen resistance via the flagellin receptor kinase FLS2 (refs 5, 6). CLV3p-FLS2 signalling acts independently from the stem-cell signalling pathway mediated through CLV1 and CLV2 receptors, and is uncoupled from FLS2-mediated growth suppression. Endogenous CLV3p perception in the SAM by a pattern recognition receptor for bacterial flagellin, FLS2, breaks the previously defined self and non-self discrimination in innate immunity. The dual perception of CLV3p illustrates co-evolution of plant peptide and receptor kinase signalling for both development and immunity. The enhanced immunity in SAM or germ lines may represent a common strategy towards immortal fate in plants and animals.     

关于低熔点铝电解质成分的探讨

本文提出一种强酸性电解质,并对其物理化学性质进行了讨讨,分析这类电解质在操作中所存在的问题,指出这类电解质在我省铝工业中应用的可能性。     

Mutations in ARFGEF2 implicate vesicle trafficking in neural progenitor proliferation and migration in the human cerebral cortex

Disruption of human neural precursor proliferation can give rise to a small brain (microcephaly), and failure of neurons to migrate properly can lead to an abnormal arrest of cerebral cortical neurons in proliferative zones near the lateral ventricles (periventricular heterotopia). Here we show that an autosomal recessive condition characterized by microcephaly and periventricular heterotopia maps to chromosome 20 and is caused by mutations in the gene ADP-ribosylation factor guanine nucleotide-exchange factor-2 (ARFGEF2). By northern-blot analysis, we found that mouse Arfgef2 mRNA levels are highest during embryonic periods of ongoing neuronal proliferation and migration, and by in situ hybridization, we found that the mRNA is widely distributed throughout the embryonic central nervous system (CNS). ARFGEF2 encodes the large (>200 kDa) brefeldin A (BFA)-inhibited GEF2 protein (BIG2), which is required for vesicle and membrane trafficking from the trans-Golgi network (TGN). Inhibition of BIG2 by BFA, or by a dominant negative ARFGEF2 cDNA, decreases cell proliferation in vitro, suggesting a cell-autonomous regulation of neural expansion. Inhibition of BIG2 also disturbed the intracellular localization of such molecules as E-cadherin and beta-catenin by preventing their transport from the Golgi apparatus to the cell surface. Our findings show that vesicle trafficking is an important regulator of proliferation and migration during human cerebral cortical development.     

旁插槽生产的不稳定性

在旁插自焙槽中,阳极拔棒出形成的孔洞,造成阳极实际有效面积达不到设计面积,使阳极电流密度发生变化,造成电解槽不稳定。可采取调整计算机程序逻辑处理,使其适应阳极电流密度的这种变化。     

电解法生产铅钙合金的研究

本文研究了在实验室条件下电解温度和阴极电流密度对熔盐电解法制取铅钙合金的电流效率的影响,当电解温度为720—740℃、阴极电流密度为0.85—0.90安/厘米~2时电流效率出现最大值。