Microhabitat selection by the fishfly larva, Parachauliodes japonicus, in relation to its mode of respiration

SUMMARY. 1. Larvae of Parachauliodes japonicus (Megaloptera: Corydalidae) were tracked in streams using miniature radio-transmitters.
2. Larvae usually stayed under stones in shallow water for several days, but occasionally moved about on the stream bed at night.
3. Larvae possess a pair of respiratory tubes on abdominal segment VIII, which can be used as a snorkel to obtain oxygen from the atmosphere. Because respiratory rates decreased as dissolved oxygen decreased, larvae turned to air-breathing under lowered oxygen conditions. When in shallow water, they can alter respiratory mode from aquatic respiration to air breathing instantly by raising their caudal respiratory tubes to the surface of the water.
4. Microhabitat selection and respiratory behaviour are compared with those obtained previously for Protohermes grandis larvae, which belong to the same family and often inhabit the same stream as P. japonicus , but which have gill tufts on abdominal segments I-VII instead of respiratory tubes. The respiratory constraint on microhabitat preference by aquatic insects is discussed.     

Life history variation in a dobsonfly, Protohermes grandis (Megaloptera: Corydalidae): effects of prey availability and temperature

SUMMARY. 1. The life cycle of a predatory insect, Protohermes grandis (Megaloptera: Corydalidae), was compared in four streams in central Japan. The effects of annual temperature regime and prey availability on life history characteristics were also assessed.
2. The larval period was 2 years and small adults emerged in the Morito River, where summer water temperature was high and large prey scarce.
3. In the Nagura River, rich in large prey, the larval period was also 2 years in spite of slightly lower temperature, and the adult size was largest among the streams.
4. In Anado Fork with a low summer temperature, the larval development took 3 years, and large adults emerged. Large prey were abundant in this stream.
5. Seasonal abundance of large prey also affected the time large larvae left the stream to pupate. Larvae emigrated earlier in streams where the density of large prey sharply decreased after spring, than in streams where large prey were available throughout the year.     

Effect of Anoxia on the Spatial Pattern of Electric Potential Formed Along the Root

Spatial patterns of surface electric potential of a root ofazuki bean (Phaseolus chrysanthos) were investigated. A multi-electrodemeasuring system was used to measure the spatial pattern andits variation with time. It was found that a periodic patternwas spontaneously formed along the root but it disappeared underanoxia. Supply of air made the pattern recover. Although thechange in electric potential started from the root tip underanoxia, it occurred first near the seed in the recovery processwhen air was supplied. To explain this phenomenon, a simplifiedtheoretical model was proposed. The model is described by adifferential equation for a concentration of oxygen expressinglongitudinal diffusion and consumption of oxygen within theroot. Assumption of a threshold of the oxygen concentrationneeded to activate a respiration-dependent pump led to a quantitativeexplanation of the above behaviour of surface electric potential.It was suggested that the pattern belongs to a group of self-organizeddynamic structures which are maintained through energy metabolismby a supply of material from outside. Phaseolus chrysanthos, bean root, electric potential, anoxia, self-organized structure, respiration-dependent pump     

Distribution and composition of colony founding associations of a subterranean termite, Reticulitermes kanmonensis

We investigated distribution and sexual composition of founding associations of Reticulitermes kanmonensis, the Japanese subterranean termite, which occurs only in the Kanmon area. These properties are discussed in relation to body size and mitochondrial genotype of the dealates. The founding colonies showed a highly aggregated distribution with a ‘hot spot’ of colony founding; however, mitochondrial haplotypes of the dealates suggested random mating. Monogamous colonies were predominant, but solitary colonies and colonies with two females and/or males also occurred. Paired dealates tended to be larger than solitary founders, suggesting that both sexes were under sexual selection related to body size.     

乳酸菌Enterococcuse faecalis TN-9低温蛋白酶的提纯及性质

对产自乳酸菌Enterococcuze fecalis TN-9的蛋白酶,进行了硫酸铵沉淀,DEAE—Sephadex A-25以及DEAE Cellulofine A-500离子交换层析的3步纯化和特性研究。纯化酶Native PAGE显示1条蛋白带。SDSPAGE和凝胶层析分子量分别为30ku及69ku。纯化酶最适作用温度为30℃,最适作用PH为7．5～8．0,在pH6．0～9．5和45℃以下条件下稳定,在0℃下显示了6．1％的相对活性,60℃以上热处理完全失去酶活。该酶被EDTA-2Na,Hg^2＋、Cu^2＋、Ni^2＋、Ag^2＋、Co^2＋及Pepstatin A不完全抑制。Zn^2＋对蛋白酶具有明显的激活作用。纯化酶作用于偶氮酪蛋白的Km和Vmax分别为0．098％和72mg／（h·mg）。该酶为N末端VGSEVTLKNS的明胶酶（Gelatinase）的一种,性质属于低温蛋白酶。