A REINTERPRETATION OF THE ONTOGENY OF THE ASCOCARP OF SPECIES OF THE ERYSIPHACEAE

A study of four species of Erysiphaceae (Uncinula salicis, Podosphaera leucotricha, Erysiphe cichoracearum, and Microsphaera diffusa) revealed that the binucleate stages of the ascocarp are initiated in a similar manner to those of Diporotheca rhizophila Gordon & Shaw. The “appendages” developing on immature ascocarps are considered to be receptive hyphae. Appendages characteristic of mature ascocarps are produced much later. Lysis of certain centrum cells occurs, and asci are initiated from some of the remaining binucleate centrum cells. Resorption of centrum cells by the asci is supported by this investigation, corroborating Björling's earlier studies on Erysiphe graminis.     

假丝酵母同源性的研究

用分光光度法测定了4株郎比可假丝酵母(Candida lambica)间的DNA-DNA同源性,结果:2.1182与LP012的同源性为90.4%,表明它们是同种的;2.1182与DX22为77.5%,DX22与LP012为76.8%,表明它们虽是同种,但产生了一些分化:LP006与LP012为63.2%,表明它们之间产生了较大的分化,接近种的范围,仍可认为是同种的。     

A STUDY OF THE INNERVATION OF THE TAENIA COLI

An electrophysiological and anatomical study of the guinea pig taenia coli is reported. Changing the membrane potential of single cells cannot modulate the rate of firing action potentials but does reveal electrical coupling between the cells during propagation. The amplitude of the junction potentials which occur during transmission from inhibitory nerves is unaffected in many cells during alteration of the membrane potential, indicating electrical coupling during transmission. The taenia coli is shown to consist of smooth muscle bundles which anastomose. There are tight junctions between the cells in the bundles, and these probably provide the pathway for the electrical coupling. The smooth muscle cells towards the serosal surface of the taenia coli are shown electrophysiologically to have an extensive intramural inhibitory innervation, but a sparse sympathetic inhibitory and cholinergic excitatory innervation. These results are in accordance with the distribution of these nerves as determined histochemically. As single axons are only rarely observed in the taenia coli, it is suggested that the only muscle cells which undergo permeability changes during transmission are those adjacent to varicosities in the nerve bundles. The remaining muscle cells then undergo potential changes during transmission because of electrical coupling through the tight junctions.     

THE EFFECT OF A PARTIAL BARRIER ON THE MOVEMENT OF A HYBRID ZONE

Computer simulations of clines (Brues, 1972; Endler, 1977) as well as theoretical arguments (Nagylaki, 1975), have shown that steps in gene frequencies will be pulled to partial barriers (areas of reduced gene flow) if they form within approximately a cline width of the partial barrier. The behavior of a hybrid zone between two chromosomal taxa (“Moreton” and “Torresian”) of the acridine grasshopper Caledia captiva in southeast Queensland has been analyzed and found to comform qualitatively with a model of altered gene flow patterns. Clines in four enzyme systems were analyzed for 1983 and 1986 along a transect across the hybrid zone. The clines have shifted towards an area of regenerating forest, while homozygote frequencies have increased at this point. This forest barrier has broken the continuity of the spatial distribution of C. captiva, forming population islands in part of the hybrid zone, and thus reducing the amount of gene flow. The distance between the barrier and the original cline is approximately of the order of a cline width, so that they would be expected to interact. Historical information suggests that the secondary contact between the “Moreton” and “Torresian” taxa occurred very recently (1844–1940), due to the intensive land-clearing activities during the European settlement.     

(山弄)岗植物区系考察报告

<正> 前言 一、鼻岗植物区系的组成 (一)科、属、种的统计 (二)10种以上的科的统计 (三)含10种以上的科在世界区系中的比重 (四)含10种以上的科在广西区系中的比重 (五)木本植物统计。 二、鼻岗植物区系的特点 (一)热带边缘性质 (二)特有性 (三)岩溶特性 三、鼻岗植物区系的地形分布特点及生态变化 (一)谷地、山坡、崖顶的分布概况 (二)水平分布的差异 (三)生态变化 四、鼻岗植物区系与邻近地区植物区系的关系 (一)与中印半岛的关系 (二)与海南岛的关系 (三)与广西阳朔的关系 (四)与花坪的关系 (五)与马来半岛岩溶植物区系的关系 (六)总的比校