Formation of wall openings in root cells of Arabidopsis thaliana following infection by the plant-parasitic nematode Heterodera schachtii

The induction and differentiation of feeding structures (syncytia) of the cyst nematode Heterodera schachtii in roots of Arabidopsis thaliana is accompanied by drastic cellular modifications. We investigated the formation of cell wall openings which occurred during syncytium differentiation. At the beginning of syncytium induction, a callose-like layer was deposited inside of the wall of the initial syncytial cell (ISC). First wall dissolutions developed by gradual widening of plasmodesmata between the ISC and neighbouring cells. As a general thickening of syncytial cell walls blocked existing plasmodesmata, other large openings were formed by enzymatic dissolution of intact walls by putative cellulase activity.     

Changes in the structure of Arabidopsis thaliana roots induced during development of males of the plant parasitic nematode Heterodera schachtii

Plant parasitic nematodes of the genus Heterodera show a high degree of sexual dimorphism, which is reflected by different nutritional demands and differences in the structure of the induced specific syncytial feeding site in the plant. The determination of the sex of the nematode Heterodera schachtii and other related species was repeatedly reported to be dependent on trophic factors, which are provided by the induced syncytia. The structural differences of syncytia induced by H. schachtii in roots of Arabidopsis thaliana were analysed at the anatomical and ultrastructural level. Syncytia of males were induced in the root pericycle. The developing syncytium then expanded into procambial or cambial cells of the vascular cylinder. Differentiated vascular elements were not included. The expansion of the syncytium triggered the proliferation of cambial and peridermal tissues, in a manner similar to secondary growth, and the formation of additional xylem and phloem elements. In comparison to syncytia associated with females, syncytia associated with males were less hypertrophied and were composed of more cells. Distinct cell wall openings were mostly found between the few strongly hypertrophied syncytial elements at the actual feeding site in the pericycle. The ultrastructure was very similar to female-associated syncytia but showed conspicuous differences in the structure and localization of cell wall ingrowths. These ingrowths were rare and weakly developed and occurred not only at the interface with xylem elements but also at the internal and external walls of the syncytia. After feeding had ceased at the end of the third developmental stage the syncytia degenerated.     

仔猪睾丸组织块生精细胞体外培养及鉴定初报

目的：建立仔猪睾丸组织块生精细胞爬片体外培养模型。方法：应用溴脱氧核苷尿嘧啶(5＇-Bromo-2＇-deoxyuridine, BrdU)免疫荧光技术检测生精细胞体外增殖分化情况；采用HE染色鉴定体外培养生精细胞分化程度。结果：结果表明体外培养第3天支持细胞开始游出睾丸组织块并贴壁；体外培养第4～8天睾丸组织块周围可见生精细胞，但未见明显增殖分化情况；体外培养第9～20天可明显观察到生精细胞增殖分化，间桥连接(gap junction)的生精细胞集落呈葡萄串或串珠状，并有精子细胞形成。结论：本培养体系能够提供睾丸组织块生精细胞增殖分化所需要的条件，在没有添加睾酮的情况下能够使非精子细胞分化为精子细胞。     

Role of membrane phospholipids and glycolipids in cell-to-cell fusion by VSV

To identify membrane components of CER cells interacting with vesicular stomatitis virus (VSV) during fusion at acidic pH (fusion from without, FFWO) two different approaches have been used, i.e. (i) treating the whole cells with enzymes and (ii) testing the ability of isolated membrane molecules to interfere with FFWO. Phospholipase A₂ and C digestion of cells greatly reduced syncytia formation, pointing towards the involvement of lipid structures as target sites for VSV. Cell susceptibility to FFWO was also reduced after neuraminidase, β-galactosidase or periodate treatment, suggesting that carbohydrate residues may participate in a complex receptor structure required for virus fusion. When membrane molecules were examined separately for their ability to inhibit viral FFWO, phosphatidylserine, phosphatidylinositol, sphingomyelin, cholesterol and GM3 ganglioside were found to be active, confirming the role of membrane lipid moiety in the cell surface structures involved in the early phases of VSV infection.     

尼帕病毒G和F蛋白单克隆抗体的制备与鉴定

为制备抗尼帕病毒(NiV)G和F蛋白的单克隆抗体(MAb),本研究以表达NiV G和F蛋白的真核重组表达质粒pCAGG-NiVG和pCAGG-NiVF分别免疫BALB/c小鼠,采用常规技术制备杂交瘤细胞;以表达G和F蛋白的重组牛痘病毒(rWR-NiVG、rWR-NiVF)分别感染BHK细胞,通过间接免疫荧光(IFA)筛...