Partial characterization and ontogenetic development of pancreatic digestive enzymes in Japanese eel Anguilla japonica larvae

The pancreatic digestive enzymes, trypsin, chymotrypsin, lipase and amylase were partially characterized, and changes in their activities were examined during the initial ontogeny of Japanese eel Anguilla japonica larvae from 5 to 34 days post-hatching (dph). The pH optima of the eel larval enzymes were narrower than those other fish species; trypsin activity was highest at pH 9, chymotrypsin and amylase activities were highest at pH 7 and 8, and lipase activity was highest at pH 8 and 9. In an analysis of thermal profiles, the larval pancreatic enzymes had a high optimal temperature and high thermal stability, which are typical of fish from the tropics. At 12 and 13 dph, lipase activity and gene expression levels of trypsin (-a and -b), lipase and amylase decreased markedly, suggesting a marked change in larval metabolism at that time. These data could be useful in the development of artificial larval diets in Japanese eel.     

Substitute and complement relations among various fish species in the Japanese market: implications for fishery resource management

A demand system analysis was conducted to examine the substitute relationships between tuna and skipjack tuna in the Japanese market. Data from the Annual Report on Family Income and Expenditure Survey from 1965 to 2006 were used for the analysis using the almost ideal demand system (AIDS). Results suggest that skipjack tuna can be a strong substitute for tuna, while other fish groups are not a clear substitute. Our analysis of substitute relationships among fish species in a market indicates that this is a factor that should be considered for better fisheries resource management. For instance, even under a situation where one fish species is underexploited, proper attention to its fishery management is necessary if the fish is a strong substitute for another popular fish species in the market.     

A Cucumber mosaic virus Isolated from Silene armeria

A Cucumber mosaic virus was newly isolated from Silene armeria and was characterized by biological, serological and molecular biological methods. Received 4 July 2001/ Accepted in revised form 28 August 2001     

A Recessive Lesion Mimic Mutant of Rice with Elevated Resistance to Fungal Pathogens

A gamma-ray-induced rice mutant, M1009, which spontaneously forms brown specks on leaves was isolated. In appearance, these lesions very much resemble those that are produced during the hypersensitive resistance response of rice to pathogens. A similar phenotype has been associated with a number of mutants in maize or Arabidopsis, which have been briefly categorized as disease lesion mimics. Brown speck formation was suppressed at temperatures of 25°C and above, and was severe at 20°C. Light irradiation is also required to initiate brown specks. In addition, the mutant exhibits heightened resistance to two major fungal pathogens of rice, Magnaporthe grisea and Cochliobolus miyabeanus. Genetic characterization of the mutant has indicated that its les-bs (lesion-brown speck) phenotype segregates as a monogenic recessive mutation. Received 13 September 1999/ Accepted in revised form 15 December 1999     

Chemical and morphological changes of porous hydrated calcium silicate in paddy soil

The chemical and morphological changes of porous hydrated calcium silicate material (PS) during the dissolution process in paddy soil were investigated by using both a scanning electron microscope (SEM) and an energy dispersive X-ray (EDX) analysis. The results showed that original PS consisted of agglomerate of various sizes with almost the same elemental composition. The SEM images at a high magnification showed that the original PS consisted of agglomerates of small platelike crystals (≦ μm) of tobermorite [Ca₅(Si₆O₁₈-H₂)·4H₂O]. On the other hand, elemental composition showed that the PS agglomerates in paddy soil altered to Si- and Ca-rich agglomerates after incubation for 53 d. The morphological differences between the two types of agglomerates were observed by SEM at a high magnification. The Si-rich agglomerates were similar to the original PS in morphology, whereas the Ca-rich agglomerate appeared as a large crystal. The X-ray diffraction patterns obtained in a previous study suggested the presence of quartz and calcite in PS after incubation for 53 d (Saigusa et al. 2000: Soil Sci. Plant Nutr., 46, 89–95). Si- and Ca-rich agglomerates were identified as silica skeletons of PS and calcite, respectively. It was suggested that the silica skeletons of PS remained as a silicon source for rice plants even after the disappearance of tobermorite revealed by the X-ray diffractogram.     

多次回交水稻短根突变体RM1的农艺性状

用 射线处理水稻品种大力 ,在 M3世代中选育出短根突变体 RM1。现用回交的 RM1及原品种大力进行土培和水培试验 ,评价短根对产量及其农艺性状的影响。试验结果表明 ,回交的RMI根长、根数和根干重约为大力的 4 0 % ,14 0 %和 6 0 % ;株粒重及株高约为大力的 5 0 %及 90 %。短根形态对经济产量的影响大于对生物产量的影响。     

A possible connection between psychosomatic symptoms and daily rhythmicity in growth hormone secretion in healthy Japanese students

Background  

Students suffering from psychosomatic symptoms, including drowsiness and feelings of melancholy, often have basic lifestyle problems. The aim of this study was to investigate whether psychosomatic complaints may be related to circadian dysfunction.     

Richness of Colchic vegetation: comparison between refugia of south-western and East Asia

Background  

The Colchis is one of the species-rich refugia and a centre of biological diversity in western Eurasia. We analysed patterns of richness, endemism and invasions in relation to taxonomy (family membership), life form, certain habitats in the Colchis, and compared them to patterns found for Japan.     

水稻侧根突变体RM109的农艺性状

用 Na N3 处理水稻品种大力 ,在 M2 世代中选育出了 2 ,4 - D耐性 ,且侧根缺失的突变体RM10 9。RM10 9及大力的土耕和水耕试验 ,评价侧根缺失对产量及其农艺性状的影响。试验结果表明 ,在生育后期 ,RM10 9的根长、根数和根干物重是大力的 6 9% ,16 %和 7% ,株粒重及株高约是大力的 10 %及 5 0 %