Decreasing dietary lipids improves larval survival and growth of Japanese eel Anguilla japonica     

Hirofumi Furuita  Koji Murashita  Hiroyuki Matsunari  Takeshi Yamamoto  Jiro Nagao  Kazuharu Nomura  Hideki Tanaka 《Fisheries Science》2014,80(3):581-587

Shark eggs-based diet is the only diet by which eel larvae can grow to glass eels in captivity. However, the high level of lipids in the diet is suggested to negatively affect eel larvae. This paper examines the effect of defatted shark eggs (DSE) and hen egg yolk (HY) on growth and survival of larvae of Japanese eel Anguilla japonica. Lyophilized shark egg and commercial HY were defatted with n-hexane, and four experimental diets were prepared using both defatted and untreated shark eggs and HY. Larvae were reared for 3 weeks by feeding the experimental diets. The highest survival rate was observed in the larvae fed DSE, and larvae fed HY showed the lowest survival rate. The best growth was found in larvae fed DSE, followed by shark eggs and defatted HY, and the worst growth was in HY-fed larvae. These results show that decreasing dietary lipids improves the nutritional value of both shark eggs and HY for eel larvae. Regulation of the dietary lipid level may positively affect the larval performance of eels by combination of ingredients with a low lipid content.  相似文献   

Can research on the early marine life stage of juvenile chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> forecast returns of adult salmon? A case study from eastern Hokkaido,Japan     

Toshihiko Saito  Ikutaro Shimizu  Jiro Seki  Toshiki Kaga  Eiichi Hasegawa  Hiromi Saito  Kazuya Nagasawa 《Fisheries Science》2010,76(6):909-920

To examine the efficacy of juvenile salmon research as a tool for forecasting adult returns, the results from a study on the early marine life stage of juvenile chum salmon, conducted in the Nemuro Strait during 1999–2002 (i.e., 1998–2001 brood years), were compared with the return rates of adult salmon. Among the four brood years, the 2000 brood year (i.e., salmon migrating to the sea in 2001) was previously reported as showing higher abundance, higher growth rate and better somatic condition during the coastal residency period. Consequently, we expected it to have the highest return rate, under a hypothesis that juvenile survival in coastal residency regulates brood-year strength. Contrary to this expectation, the 2000 brood year had almost the lowest return rate. Alternatively, a statistical model in which sea surface temperature during the first year of marine life and size at release were utilized as explanatory variables reconstructed the actual variability in return rates more accurately than that based on the early marine life stage. Possible reasons for the discrepancy between the results of the juvenile salmon research and adult returns are discussed, and we suggest improvements for future research on juvenile salmon.  相似文献   

Species diversity of broad-leaved trees in Cryptomeria japonica plantations in relation to the distance from adjacent broad-leaved forests   总被引：1，自引：0，他引：1  

Jiro Kodani 《Journal of Forest Research》2006,11(4):267-274

The species diversity of broad-leaved trees in relation to the distance from a broad-leaved forest was investigated in Cryptomeria japonica plantations with crown snow damage near the Japan Sea in central Japan. The number and diversity of species and stem density decreased with distance from the broad-leaved forest in maturing gap stands (51–58 years old; >10 years after crown snow damage), but not in recent gap stands (34–42 years old; <10 years after crown snow damage), and increased with improved light conditions in the interior of recent gap stands, but not in that of maturing gap stands. The stem densities of tall and small tree species and woody lianas were greater in the interior of recent gap stands than in maturing gap stands. Woody lianas, which are characteristically shade intolerant, had a high stem density in the interior of recent gap stands. In contrast, the stem density of shrubs was greater in maturing gap stands than in recent gap stands, irrespective of distance. Shade-tolerant shrubs had a high stem density in maturing gap stands. Wind-dispersed and frugivore-dispersed species were concentrated at the edges of maturing gap stands, but some frugivore-dispersed species, which may persist in soil seed banks, occurred in the interior of recent gap stands. Gravity-dispersed species tended to occur both at the plantation edge and in the interior. The differences in the occurrence patterns of broad-leaved trees in the two types of stands reflected the difference in the effect of both the distance from the adjacent broad-leaved forest and the light conditions related to canopy gaps, with the time since gap formation in a region where crown snow damage often occurs.  相似文献   

Etiolated growth in relation to energy reserves and winter survival in three temperate grasses     

Masahisa Moriyama  Jiro Abe  Midori Yoshida 《Euphytica》2003,129(3):351-360

The role of energy reserves in development of winter hardiness was examined in timothy (Phleum pratense L.), orchardgrass (Dactylis glomerata L.) and perennial ryegrass (Lolium perenne L.) through periodically measuring etiolated growth (EG; shoot growth of crown under dark, warm and humid conditions following defoliation) and determining sugar profiles at critical stages of hardening and wintering. Seasonal changes in weight and duration of EG were monitored by sampling once or twice a month from September to the following April. In all species, total etiolated growth (TEG; total shoot production at each sampling time as determined by weekly or biweekly harvests until exhaustion of reserves) increased from September to reach peak levels during the second hardening stage in mid-November. Thereafter, TEG remained high until the following spring in orchardgrass while it declined linearly in timothy, which had the lowest TEG. The decline in TEG was intermediate in perennial ryegrass. Changes in the duration of EG were most marked in orchardgrass, as it required six weeks to produce about 150 mg g^-1 TEG in early November but only one week in March. The results indicated occurrence of dormancy in apical meristems of orchardgrass at the end of the first hardening stage with temperatures above 0 ^°C, which roughly corresponded with the phase of dormancy in woody plants. Dormancy was weak in timothy and largely undetectable in perennial ryegrass, as measured by the EG technique. A positively significant correlation between total nonstructural carbohydrates (TNC) content and TEG was found in all species. Detailed analysis, however, showed that direct estimation of TNC content using TEG was difficult because TEG production per unit TNC was negatively correlated with TNC level, and the amount of TNC unused in early autumn was more than in the rest of the season. Changes in sugar profiles occurred at transition from the first to the second hardening stage with subzero temperatures and varied with wintering strategy of each species. Simple sugar content dramatically declined while fructan content increased in both timothy (cv. ‘Senpoku’) and orchardgrass (cv. ‘Wasemidori’), which were selected at sites covered with snow for more than 120 days. In contrast, a cold tolerant perennial ryegrass cv. `‘éveille’ selected in the Netherlands retained high amounts of simple sugars. The results suggest that EG technique is suitable to monitor physiological status (amount and rate of mobilization of energy reserves, intensity of dormancy and bud development) of plants expressing winter hardiness. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Heading behaviour in Japan of Turkish populations of cocksfoot,Dactylis glomerata L.     

Jiro Abe  S. Kawabata 《Euphytica》1979,28(3):643-649

Summary Ninety-nine populations of cocksfoot collected throughout Turkey were examined for heading behaviour at Sapporo, Japan. In some populations, all the plants produced heads in the year of sowing or in the aftermath of the next year. Much of the Turkish populations, even from the mountainous regions with severe winters, is also distinct in heading behaviour in autumn from the north European types, which fail to head in the year of sowing. This behaviour is related to winter temperatures of the place of origin, with the milder winter tending to result in a higher heading rate. Date of heading is also influenced by the climatic factors of the habitat, especially by the length of the growing period between winter and summer dormancies. Turkish populations provided useful material for the study of flowering habit.  相似文献   

Effect of pH Conditions on Actual and Apparent Fluoride Adsorption by Biochar in Aqueous Phase   总被引：1，自引：0，他引：1  

Taek-Keun Oh  Bongsu Choi  Yoshiyuki Shinogi  Jiro Chikushi 《Water, air, and soil pollution》2012,223(7):3729-3738

Biochar is a carbon-rich product derived from biomass through pyrolysis. Fluoride adsorption potential of the biochar derived from orange peel (OP) and water treatment sludge (WS) at different pyrolytic temperatures (400, 600, and 700?°C) was investigated in a batch mode as a function of pH. With respect to adsorption, two types were considered, i.e., actual and apparent adsorption where fluoride combined with metal complexes in solution were counted and not counted, respectively. The highest actual fluoride adsorption was observed in the pH range of 2.0 to 3.9 for OP biochar and 5.1 to 6.2 for WS biochar, respectively. For the WS biochar, apparent fluoride adsorption showed nearly 100?% in the pH range of 2.0 to 4.5, and then the adsorption capacity diminished drastically as the pH increased from 5.0 to 10.0. There was no significant difference between apparent and actual fluoride adsorption for OP biochar. In the Fourier-transform infrared spectroscopic analysis of WS biochar, a strong and sharp band was observed at around 2,364?cm^?1 after adsorption of fluoride. Elemental content analysis by the energy-dispersive X-ray method revealed that the fluorine content was higher at pH 6.0 than at pH 3.0 and 9.0 as the results of actual fluoride adsorption. From these results, we may conclude that the biochar derived from OP and WS can be reused as an economical and effective adsorbent for fluoride removal in acidic aqueous phase.  相似文献   

Immunohistochemical localization of rainbow trout androgen receptors in the testis     

Jiro Takeo  Shinya Yamashita 《Fisheries Science》2001,67(3):518-523

SUMMARY: We examined the distribution of two rainbow trout androgen receptors (rtAR: rtAR-α and rtAR-β) in the testis immunohistochemically using a specific antibody to clarify the target cells of androgen in spermatogenesis. Positive rtAR immunoreactivity in paraffin-embedded sections was revealed using microwave treatment, and was detected in the nuclei of Sertoli cells, Leydig cells, and other interstitial cells. The presence of rtAR in Leydig cells suggested that fish androgens regulate Leydig cell activity in an autocrine fashion similar to mammalian androgens. In addition, we found that not all Leydig cells exhibited rtAR immunoreactivity in the mature testis by double staining using anti-3β-hydroxysteroid dehydrogenase (3β-HSD) antibody. Furthermore, rtAR immunoreactivity was also detected in the nuclei of spermatogonia, spermatocytes, and spermatids. The intensity of rtAR immunoreactivity in the nuclei of spermatogonia seemed to be weaker than those of spermatocytes and spermatids. These results suggested that androgens act directly on both germ cells and somatic cells in the regulation of spermatogenesis in the rainbow trout.  相似文献   

Fractionation of Humus by Sulfacetolysis     

Jiro Kosaka  Chikabumi Honda 《Soil Science and Plant Nutrition》2013,59(1):59-62

Introduction

Springer¹⁾ used in his earlier work acetyl bromide for separating true humic substance from soil organic matter, and proposed to designate the degree of decomposition (Zersetzungsgrad) by such a numeral C_h C_t x 100, of which C_t, was total carbon, and C_h was carbon insoluble in acetyl bromide. In Germany this numeral, abbreviated as Z. G., has been widely applied.  相似文献   

Organic phosphorus in upland soil     

Jiro Kosaka  Kazuo Abe 《Soil Science and Plant Nutrition》2013,59(1):95-99

The nature and behaviour of soil organic phosphorus has been studied in many places of the world, especially in Iowa, U.S.A., and Quebec, Canada.  相似文献   

Division of the Process of Humification in Upland Soils,and its Application to Soil Classification     

Jiro Kosaka 《Soil Science and Plant Nutrition》2013,59(3):14-18

On the basis of the results from previous studies^{1 ,2)} the author proposed the basal idea to classify all the process of humification into five stages (designated A, B, C, D and E), covering from the stage at the decomposition of raw material to that at the accumulation of highly deformed material.  相似文献