In-vitro Assays of Meloidogyne incognita and Heterodera glycines for Detection of Nematode-antagonistic Fungal Compounds

In-vitro methods were developed to test fungi for production of metabolites affecting nematode egg hatch and mobility of second-stage juveniles. Separate assays were developed for two nematodes: root-knot nematode (Meloidogyne incognita) and soybean cyst nematode (Heterodera glycines). For egg hatch to be successfully assayed, eggs must first be surface-disinfested to avoid the confounding effects of incidental microbial growth facilitated by the fungal culture medium. Sodium hypochlorite was more effective than chlorhexidine diacetate or formaldehyde solutions at surface-disinfesting soybean cyst nematode eggs from greenhouse cultures. Subsequent rinsing with sodium thiosulfate to remove residual chlorine from disinfested eggs did not improve either soybean cyst nematode hatch or juvenile mobility. Soybean cyst nematode hatch in all culture media was lower than in water. Sodium hypochlorite was also used to surface-disinfest root-knot nematode eggs. In contrast to soybean cyst nematode hatch, root-knot nematode hatch was higher in potato dextrose broth medium than in water. Broth of the fungus Fusarium equiseti inhibited root-knot nematode egg hatch and was investigated in more detail. Broth extract and its chemical fractions not only inhibited egg hatch but also immobilized second-stage juveniles that did hatch, confirming that the fungus secretes nematode-antagonistic metabolites.     

Microstructures formed in aqueous solutions of a hydrophobically modified nonionic cellulose derivative and sodium dodecyl sulfate: a fluorescence probe investigation

The association behavior of hydrophobically modified ethyl hydroxyethyl cellulose (HM-EHEC) and its interaction with the anionic surfactant sodium dodecyl sulfate (SDS) has been studied in the dilute concentration regime. Steady-state fluorescence probe techniques have been utilized to obtain microstructural information of the system properties and combined with macroscopic bulk information from equilibrium dialysis experiments in order to determine binding isotherms of SDS to HM-EHEC. HM-EHEC was found to self-associate and form polymeric micelles in semi-dilute aqueous solutions. c^* for the self-association process was determined to be approximately 0.4%. The microviscosity of the polymeric micelles is much higher, and the micropolarity slightly higher, than that of ordinary SDS micelles. The onset of interaction between HM-EHEC and SDS was evidenced by a simultaneous strong increase in microviscosity and decrease in micropolarity upon successive addition of SDS. There is a minor, noncooperative SDS binding to the HM-EHEC starting from low concentrations of SDS (<5 mM) followed by a highly cooperative binding region at SDS concentrations ≥5 mM. The polymer–surfactant aggregates are rigid and hydrophobic with a maximum in microviscosity in the noncooperative binding region at a very low degree of SDS-adsorption.     

银合欢根瘤细胞的光学显微镜和电子显微镜研究

银合欢接种根瘤菌形成根瘤后,应用光镜和电镜技术观察。银合欢根瘤由分生组织细胞、皮层组织细胞、维管束系统和侵染细胞区域四个不同部分组成。根瘤菌借助于侵染线侵染细胞,释放进入宿主细胞质中,转变成固氮类菌体。最初每个包被膜内只含单独的类菌体,随后较老的侵染细胞中,每个包被膜内含有一个以上的类菌体。因此,成熟根瘤的侵染细胞可见有2~5个类菌体群集包被膜里,并且明显地累积PHB物质,显示电子染色透明颗粒。本文还讨论了上述变化的意义与银合欢根瘤细胞结构和功能的关系。     

On the Application of Computer Graphics Technique to Reconstruct Three-Dimension of Coal Ball Plants

This paper reports a new way by which three-dimensional images of coal ball plants are revealed conveniently. In order to reconstruct outer images of coal ball plants, especially seeds, three different reconstruction methods (additional method, symmetric method and mixed method) have been developed. In the meantime, the way of reconstruction of membrane-like structure was explored. The establishment of these methods contributes to the reconstructing the whole shape of coal ball plants and relating coal bails to other fossil forms. In addition, the difficulties in three-dimensional reconstruction of coal ball plants by using computer are discussed.     

The Use of a Whole Stain-Clearing Technique for Observations on Embryo Sac,Embryo, Endosperm and Embryoid

A new stain-clearing procedure has been developed for embryological observations on whole mounted specimens. Ovules of Helianthus annus and Nicotiana tabacum as well as ovaries of Oryza sativa were stained with diluted Ehrlich's hematoxylin for a proper short time, followed by steps of washing and dehydration, and finally cleared and mounted in methyl salicylate. When observed by ordinary bright-field microscopy, the embryo sacs before fertilization and the embryos and endosperms after fertilization were clearly visible. The gynogenic embryoids induced in unpollinated rice ovaries in vitro were also finely detectable. The Ehrlich's hematoxylin-methyl salicylate technique has the merits of rapidity in specimen preparation, high contrast and three dimensional view, needlessness of phase- or interference-contrast equipment, and the feasibility for a wide range of materials. The special significance of this technique for in vitro embryological studies is emphasized.     

Experimental Measurement of the Water Relations Parameters of Nine Shrubs and Some Ecological Interpretations

Determination of some water relations parameters of 9 shrubs with the Pressure-volume technique has shown that there were considerable variations in the water relations parameters of different shrubs and that some parameters were indicative for their adaptations to the ecological conditions. It has been found that two desert shrubs, Tetraena mongolica Maxim. and Zygophyllum xanthoxylon (Bge.) Maxim., exhibited strong ability of drought tolerance, whereas the typical sandy shrubs were quite diverse in adaptation strategy. Salix psammophila C. Wang et Ch. Y. Yang, Artemis& ordosica Krasch., Caragana intermedia Kuang et H. C. Fu and Ammopiptanthus mongolicus (Maxim.) were more or less close to each other in water relations parameters. Their фπ, p ranged from - 1.4 MPa to -2.4MPa, and Vp/Vo lay between 62% and 76%. However, some special features of adaptation were found in the other three species, e.g., Sabina vulgaris Ant., Hedysarum mongolicum Turcz. and Artemisia sphaerocephala Krasch.     

选择感染性噬菌体（SIP）技术：一种新的相互作用分子筛选技术

选择感染性噬菌体（SIP）技术是利用丝状噬菌体次要衣壳蛋白PⅢ的分子结构组件,并以噬菌体展示技术为基础发展而来.SIP的技术关键在于使没有感染性的噬菌体颗粒必须严格依赖分子间的相互作用、结合而重获感染性,已有的研究表明SIP技术可望成为一项获得相互作用分子对的极其有效和高度特异性的新技术,具有广阔的应用前景.     

银杏叶黄酮提取方法比较

比较不同溶剂提取银杏（ＧｉｎｋｇｏｂｉｌｏｂａＬ．）叶黄酮类化合物的提取效率,从成本效益角度考虑,以７０％乙醇作为提取溶剂更为有利。在分级沉淀中,黄酮含量与蛋白质含量呈正相关,在乙醇提取液中黄酮和蛋白质含量最高;蛋白质的存在有助于提高黄酮的溶解度。乙醇提取液用饱和（ＮＨ４）２ＳＯ４浓缩两次,可使醇相中的黄酮沉淀析出。根据试验结果,提出了银杏叶黄酮的优化提取方法。