马鞍山林场松墨天牛病原微生物种类调查鉴定及毒力测定研究

在马鞍山市马鞍山林场,对松材线虫病(Bursaphelenchus xylophilus)的传媒昆虫松墨天牛(Monochamus alternatus)的病原微生物进行调查,结果鉴定了8种真菌和1种细菌.对松墨天牛幼虫的致病率测定显示不同的微生物种类和同一种白僵菌(Beauveria bassiana)的不同菌株均有显著差异.白僵菌的高毒力菌株营养生长无明显差异,而产孢量有明显差异.通过测定,白僵菌菌株226可能是优良菌株,对生物防治松黑天牛方面有潜在的实用价值.     

Effect of dietary inclusion of various plant ingredients as an alternative for Sargassum thunbergii on growth and body composition of juvenile sea cucumber Apostichopus japonicus

Two feeding experiments were conducted to investigate the effects of dietary inclusion of different plant ingredients on growth and body composition of juvenile sea cucumber. In the first experiment, three replicate groups of the sea cucumber (average weight of 1.5 ± 0.05 g) were fed one of the seven experimental diets containing Sargassum thunbergii (CON), Undaria (UND), Laminaria (LAM), Brassica oleracea L. var. capitata (BRA), fermented soybean (FSB), distillers dried grain (DDG) and rice straw powder (RIC) for 10 weeks. After the feeding trial, survival was not significantly different among the dietary treatments. Specific growth rate (SGR) of sea cucumber fed the FSB diet (0.73) was significantly higher than that of sea cucumber fed the other diets (P < 0.05), except for the DDG diet (0.64). The lowest SGR was observed in sea cucumber fed the CON diet (0.14). Based on the result of the first experiment, the second experiment was conducted to determine the proper level of dietary DDG for growth of juvenile sea cucumber. Three replicate groups of sea cucumber (average weight of 1.6 ± 0.02 g) were fed one of the five experimental diets containing different levels (g kg^?1) of DDG (DDG0, DDG10, DDG20, DDG30 and DDG40) for 12 weeks. Survival was not significantly different among the treatments (P > 0.05). The best SGR was obtained in sea cucumber fed the DDG10 diet (10.1) and the value of sea cucumber fed the DDG40 diet (5.6) was the lowest (P < 0.05). The SGR of sea cucumber fed the DDG10 diet did not differ from that of sea cucumber fed the DDG20 diet (P > 0.05). Moisture, crude protein, crude lipid and ash contents of whole body in sea cucumber among the dietary treatments (P > 0.05) did not differ significantly at both experiments. Results of two feeding trial suggest that dietary inclusion with 100 g kg^?1 FSB or 100–200 g kg^?1 DDG may improve growth of juvenile sea cucumber, and especially DDG could be used as a good ingredient for the low‐cost feed formulation.     

Effects of dietary glucose level during late gestation on litter performance and glucose concentration in sows

The effects of feeding glucose during the 5 days before parturition on litter performance and on glucose concentration in sows were studied. At day 100 of gestation, 130 multiparous sows were assigned to the treatments. Late gestating sows were fed 0 g, 150 g, 250 g, 350 g and 450 g of glucose a day, respectively. During lactation, all sows were given free access to the same lactation diet (without glucose). One day before parturition, blood samples were collected from 30 sows (6 sows per treatment) at 10 before and 20, 40, 60 and 80 min after the meal. The supply of additional dietary glucose increased piglet birth weight ( P  < 0.05). Feed intake in week 1 and week 1–4 of lactation was greatest in sows fed the 0% glucose diet, least by sows fed the 18% glucose diet, and intermediate by sows fed the 6, 10, 14% glucose diets ( P  < 0.05). Basal glucose concentration and time of maximum glucose concentration after glucose intake were not affected by dietary treatment in the last 5 days of gestation. The sows fed the 14 and 18% glucose diets had greater maximum increase in glucose concentration than sows fed diet without glucose ( P  < 0.05). In conclusion, feeding glucose to sows during 5 days before parturition increased birth weight of live-born piglet and decreased sows feed intake during lactation, but did not affect the performance of sows and piglets.     

Analysis on the movement of bag-net in set-net by acoustictelemetry techniques

ABSTRACT:   A mooring-type underwater positioning system (UPS) to measurethe bag-net movements in a set-net by acoustic telemetry techniqueswith five transponders was reconstructed. The field experimentswere conducted in Jaran Bay, Kosung, Korea on 6 October 2000 (neaptide) and 28 November 2000 (spring tide). The average UPS fixingerrors of x -axis, y -axis and z -axis were less than0.6 m, 0.8 m and 1.2 m, respectively.The longitudinal movement range, the latitudinal range and the verticalrange of the bag-net at the neap tide were 3.2 m, 3.4 mand 2.1 m, respectively. At the spring tide, these rangeswere 7.8 m, 7.8 m and 5.0 m, respectively.It was confirmed that the UPS system could be used for measuringa part of the bag-net movement.     

Differential levels of antioxidants in paraquat-resistant and -susceptible Erigeron canadensis biotypes in Korea

To characterize the biochemical differences in paraquat-resistant and -susceptible biotypes of Erigeron canadensis L. collected from Korea, we investigated the constitutive levels of various antioxidants such as antioxidant enzymes and low molecular weight antioxidants in leaves, as well as after paraquat treatment. The activities of superoxide dismutase, peroxidase, ascorbate peroxidase, and catalase were higher in the paraquat-resistant biotype than in the paraquat-susceptible biotype. Reduced ascorbic acid content was higher in the resistant biotype, but the content of reduced glutathione was higher in the susceptible biotype. These results indicate that one of the paraquat-resistant mechanisms in E. canadensis in the present study might be related to protecting the activities of antioxidant enzymes, such as superoxide dismutase, peroxidase ascorbate peroxidase, and catalase, as well as the contents of low molecular weight antioxidants such as ascorbate and glutathione.     

Initial design for a fish bioenergetics model of Pacific saury coupled to a lower trophic ecosystem model

A fish bioenergetics model coupled with an ecosystem model was developed to reproduce the growth of Pacific saury. The model spatially covers three different oceanographic spatial domains corresponding to the Kuroshio, Oyashio, and interfrontal (mixed water) regions. In this coupled model, three (small, large, and predatory) zooplankton densities which were derived from the lower trophic level ecosystem model were input to the bioenergetics model of saury as the prey densities. Although certain model parameters were imposed from other species’ bioenergetics, several model parameters were estimated from observational data specific to Pacific saury. The integrated model results reproduced appropriate growth rates of Pacific saury. Model sensitivities to water temperature and prey density are examined and observational methods to evaluate the model parameters are discussed.     

Effects of estrogen on estrogen receptor expression in the bursal cells of chick embryos and steroidogenic enzymes gene expression in the bursa: Relevance of estrogen receptor and estrogen synthesis in the bursa of chick embryos

Estrogen has been reported to act on B cell genesis in the bursa of Fabricius of chick embryos. In this study, we attempted to demonstrate the hypothesis that B cell genesis is controlled by estrogen receptor (ER) in the bursal cells and steroidogenic enzymes synthesized in the bursa. We previously reported the presence of estrogen receptor α (ERα) in the bursa during the late stage of embryogenesis and an increase in the expression of ERα messenger RNA (mRNA) between the 13th day and 16th day. The number of ER-positive cells was maximal on the 16th day. In the present study, ER-positive cells in the bursa during the late stage of embryogenesis increased 4 h after β-estradiol treatment on the 14th to 18th day. The concentration of β-estradiol in the embryonic bursa increased. These results suggest that this stage of embryogenesis is critical in B cell development in the bursa in connection with the effect of estrogen treatment. Our findings also showed that the mRNA expression of five steroidogenic enzymes occurred in the bursa of chick embryos. These results suggest that estrogen is synthesized in the embryonic bursa and estrogen acts on the bursal cells in a paracrine fashion.