INVESTIGATIONS ON RESISTANCE TO DISEASE AMONG SPECIES OF THE GENUS AVENA

Fifty-three samples representing species of the genus Arena were tested for resistance to infection by Ustilago avenae and U. kolleri following artificial inoculation. Among the diploid and tetraploid species tested, eleven out of thirty-seven samples of Arena strigosa subsp. strigosa showed complete resistance to all the cultures with which they were inoculated. Avena strigosa subsp. barbata (three samples), and Avena strigosa subsp. abyssinica (one sample), also proved to be resistant to all the available races.
Variation in morphological and physiological characteristics within species and samples (varieties?) of the lower chromosome groups of Avena were observed and its consequences in breeding and race identification discussed.
Race identification was carried out on the eight Ustilago cultures and the existence of at least six races established. The tester varieties used in the present study proved inadequate for the complete separation of the smut races.     

INFLUENCE OF CELL WALL COMPOSITION ON THE RESISTANCE OF TWO CHLORELLA SPECIES (CHLOROPHYTA) TO DETERGENTS1

The influence of dodecylbenzene sulfonate (DBS) and Triton X-100 (TX-100) was examined on two species of Chlorella exhibiting conspicuous differences in cell wall composition. Chlorella emersonii has both a classical polysaccharidic wall and a thin trilaminar outer wall (TLS) composed of nonhydrolyzable macromolecules. Chlorella vulgaris lacks a TLS. Photosynthetic capacity was measured following short exposures (1 h) of the algae at different physiological stages to high DBS and TX-100 concentrations, up to 1 g·L^?1. Comparisons with untreated controls indicated that 1) the presence of a TLS in C. emersonii was associated with a very high resistance to the anionic (DBS) and nonionic (TX-100) detergents at all growth stages, and net photosynthesis was not significantly affected in that species, 2) a high toxicity, particularly pronounced with TX-100, was observed for actively growing cells of the TLS-devoid species, C. vulgaris, and 3) aging exerted a protective influence, especially efficient against DBS, on the latter species. Additional observations, including fluorescence spectra and high-performance liquid chromatography pigment analyses, were conducted following short exposures of actively growing cells. Fluorescence emission spectra revealed that the chlorophyll a-protein complexes in thylakoid membranes were not substantially affected by DBS and TX-100, even in the case of C. vulgaris. In sharp contrast, fluorescence excitation spectra on the latter species showed 1) that excitation transfer from antenna pigments to chlorophyll a in reaction centers was substantially altered with both detergents and 2) that the two detergents affected different parts of the photosynthetic system of the TLS-devoid species. Analyses of C. vulgaris extracts indicated significant decreases in pigment content following exposure to DBS and, to a lesser extent, to TX-100. Longer exposure experiments (1 day) were conducted with actively growing algae. The TLS-containing species still showed a very high resistance and no important changes in photosynthetic capacity compared to cells exposed for 1 h. For the sensitive TLS-devoid species, the detrimental influence of TX-100, already very high after 1 h, was not increased. DBS toxicity was markedly increased and may reflect a lower uptake rate of DBS by C. vulgaris. Taken together, these observations confirm the important protective role of TLS against detergents. They also provide information on the factors controlling detergent toxicity in the sensitive, TLS-devoid species and on the different modes of action of DBS and TX-100 on its photosynthetic system. Such large differences in microalgal sensitivity to detergents, related to TLS occurrence, should have important consequences for the selection of suitable species in toxicity tests.     

THE MECHANISM OF CHANGE IN RESISTANCE OF ERYTHROCYTES TO HYPOTONIC SALT SOLUTIONS

Ashby''s work on the effects of KCl and NaCl on the resistance to hypotonic hemolysis of K^•-rich and K^•-poor erythrocytes has been repeated with great attention to purity of materials and refinement of technique. The results fail to agree with those of Ashby. 1. KCl produces greater loss in resistance to hypotonic hemolysis than does NaCl, irrespective of the species of the animal from which the cells are taken. 2. While cases of an increase in resistance have been encountered in my experiments, they are either very slight, or else the particular determination is subject to very great uncertainty. The great increases in resistance found by Ashby are not even approached in any of the present series of experiments. 3. Ashby''s generalization that KCl and NaCl have opposite effects on red blood cells, and that the sense of these effects depends on whether the cell is K^•-rich or K^•-poor is not substantiated.     

家蝇对敌百虫的抗性及增效磷(SV_1)对表皮穿透作用的增效机制研究(英语)

增效磷(SV_1)对抗敌百虫家蝇有明显的增效作用,能够延缓家蝇对敌百虫抗性的发展.测定了敌百虫对一个敏感和两个抗性品系家蝇的表皮穿透作用,结果表明抗性品系家蝇对敌百虫的穿透速率比敏感品系低,说明表皮穿透作用的降低和体内解毒速率的增强在家蝇对敌百虫的抗性中起重要作用.SV_1与敌百虫混用后,穿透速率明显提高,敌百虫对家蝇表皮穿透速率的增强和体内代谢速度的降低是SV_1在抗性家蝇体内对敌百虫增效的机制之一.     

扁叶属甲虫的种类鉴别

扁叶蝌属(Gastrolina)隶属于叶蝌科叶(虫甲)亚科,是一个典型的古北-东洋交界属。在我国,东部从黑龙江到广东,西部从甘肃(东南)、陕西、四川到云南,都有记载;国外分布已知有西伯利亚东部、朝鲜、日本和越南等地。全属计有三种,其中一种又可分为三个亚种。它们的寄主植物包括胡桃和桦木两科,是核桃、核桃楸、枫杨和赤杨的害虫,在某些地方,为害且相当严重。本文特将各种类的名称和鉴别特征,作一简略介绍,以便有关工作者的参考。     

秦岭天名精属植物的新种及新分布

在编写《秦岭植物志》的过程中,对本所馆藏的天名精属(Carpesium Linn.)标本进行整理鉴定,发现本区该属的10种及3变种中有1新种和7种为本区首次记录,现报导如下。     

THE TOXICITY OF CERTAIN SYNTHETIC ORGANIC COMPOUNDS TO THE FRUIT-TREE RED-SPIDER MITE

The acaricidal activity of ninety synthetic organic compounds has been investigated in the laboratory. Considerable differences were found between the winter eggs, the summer eggs and the adult female stages of the fruit-tree red-spider mite (Meta-tetranychus ulmi (Koch)) in their susceptibility to many of the compounds but two substances, namely azoxybenzene and n-dodecyl thiocyanate, were appreciably toxic to all three stages. Of the compounds showing promise against summer eggs and mites, bis-( p -chlorophenyl) methyl carbinol and 4-chloroazobenzene were the best, being highly toxic to both summer stages. Of the remainder, diphenylsulphone, 4-chlorodiphenylsulphone, azobenzene and hydrazobenzene were highly ovicidal, while C₁₂-C₁₃ alkyl thiocyanates and sec .-dodecyl thiocyanate gave high kills of the adult female mite.
Relationships between molecular structure and acaricidal activity have been sought. In a series of compounds characterized by the presence of two benzene nuclei connected by certain bridging groups, it has been found that activity to the summer stages of the mite can be influenced by alterations to the bridging group and by substitution in the benzene nuclei. Maximum activity appears to be associated with chlorine substitution in the para position in one nucleus and also with compounds of this type having unsubstituted nuclei.     

三种小鲵和极北鲵的核型

本文报道了安吉小鲵（Ｈｙｎｏｂｉｕｓａｍｊｉｅｎｓｉｓ）、中国小鲵（Ｈ．ｃｈｉｎｅｎｓｉｓ）、东北小鲵（Ｈ．ｌｅｅｃｈｉ）（辽宁桓仁）和极北鲵（Ｓａｌａｍａｎｄｒｅｌａｋｅｙｓｅｒｌｉｎｇｉ）（吉林白河）的核型。３种小鲵２ｎ＝５６,染色体按大小和形状分为大、中、小型双臂和小型单臂４组。极北鲵２ｎ＝６２,染色体按大小和形状可分为大、中、小型３组。对东北小鲵辽宁桓仁与辽宁千山标本核型的显著差异结合分类学问题进行了讨论。对３种小鲵核型进行了比较分析,并讨论了中国的小鲵属核型特点。比较了不同地区极北鲵核型的异同,并将其与小鲵属核型进行了比较。     

虫疫霉属新种和中国新记录

本文报道了虫疫霉属2个新种及1个中国新记录种。新种北虫疫霉(Eryniaborea Fan et Li sp.nov.)发生于西北及东北地区的丽蝇成虫体上,菜叶蜂虫疫霉(Eryniaathaliae Li et Fan sp.nov)发生于陕西杨陵的黄翅菜叶蜂幼虫;新记录种近藤虫疫霉(Erynia kondoiensis Milner)发生于福州的烟蚜虫体上。本文详细描述了新种的形态。