Comparison of defence ability against the white spot syndrome virus between Fenneropenaeus chinensis and Marsupenaeus japonicus

The defence ability of Fenneropenaeus chinensis and Marsupenaeus japonicus against the intrusion of the white spot syndrome virus (WSSV) was compared after injecting WSSV intramuscularly by recording cumulative mortality, diagnosing the virus and examining variations in immunological parameters including the total haemocyte counts (THCs), phagocytic percentage (PP), plasma protein concentration (PPC), phenoloxidase (PO) and nitric oxide synthase (NOS) activity. The results showed that the variations in the immunological parameters of F. chinensis and M. japonicus showed similar trends. The THCs of the two species decreased significantly postchallenge of WSSV. The virus was detected at 78 h in M. japonicus and at 42 h in F. chinensis after infection, which was in correlation with the accumulative mortality, and the variations in PO, PP, NOS and PPC in the two species. All shrimps of F. chinensis in the mortality experiment died within 66 h, much more quickly than M. japonicus, whose cumulative mortality reached 100% after 198 h. In conclusion, the immune system of M. japonicus has a stronger resistant ability to antagonize and endure the invasion of WSSV than that of F. chinensis.     

RAPD和酯酶同工酶技术在香菇杂交育种中的应用

利用ＲＡＰＤ和酯酶同工酶技术研究了６个香菇品种间的遗传差异和亲缘关系。通过聚类分析发现，类间组合杂种优势强，类内组合杂种优势弱，因此，杂交亲本应选择不同类的菌析不同类的菌。通过单孢杂交和出菇试验发现，杂交子代酶谱出现“互补型酶带”和“杂种新酶带”，杂交后代杂种优势强，容易选出优良品种。     

间伐对兴安落叶松人工林林分结构的影响

研究并分析了间伐前后及不同间伐强度林分结构的变化。利用三参数韦布尔函数模拟林分胸径分布，通过其参娄的变化进行定性分析。结果表明，以小径木为间伐对象的间伐作业对林分胸径分布有正面影响。对于林木生长，以中度间伐效果最好。     

牛蛙膨化颗粒饵料生产技术

近几年来,由于人们追求营养价值高、味道鲜美的食品,以及牛蛙在国际市场上的高昂身价,使牛蛙再度成为人们的美食对象;而利用挤压膨化生产的牛蛙颗粒饵料也越来越被广大养殖者所喜爱.这种饲料为圆柱状颗粒,直径3～5 mm,长5～8 mm,表面光滑,色泽均匀.     

Excessive application of nitrogen and phosphorus fertilizers induces soil acidification and phosphorus enrichment during vegetable production in Yangtze River Delta,China

Intensive vegetable cultivation has developed very rapidly in China, and investigation of current soil nutrient problems in vegetable fields and their potential environmental risk is important for local soil nutrient management strategies. Three hundred and sixty‐six soil samples were collected from greenhouse vegetable fields, open vegetable fields and rice/wheat rotation fields in southern Jiangsu Province, the most intensive vegetable‐producing areas in Yangtze River Delta, China, for the analysis of their soil fertility status. Soil acidification and P enrichment were the main problems identified in this area of vegetable production, with about 20 and 17% of the open and greenhouse vegetable field soils, respectively, being extremely acid with soil pH values below 5.0. In contrast, no soils under rice/wheat rotation fields were as acidic. Percentages of sites with Olsen‐P concentrations < 90 mg/kg were 61, 85 and 0% for soils growing greenhouse vegetable, field vegetable and rice/wheat, respectively. The nitrogen (N) surplus for vegetable fields exceeded 170 kg/ha/crop, and the phosphorus (P) surplus exceeded 40 kg/ha/crop. Thus, current vegetable production leads to potential environmental risks of N and P pollution of nearby aquatic bodies. Insufficient supplementation with potassium fertilizers was found in some vegetable fields. Several ameliorative measures are proposed.     

催青条件对蚁色限性品种的雌雄孵化及蚁蚕生命力的影响

养蚕生产的蚕种催青，通常是将蚕种放在25～26℃、相对湿度75～85％的条件下保护孵化。对普遍品种而言，催青温度如果超过30℃或低于20℃、相对湿度高于90％或低于60％，均不利于蚕胚胎的正常发育，甚至导致蚕卵不能孵化。为进一步探讨高温干燥催青对蚁色限性雌雄蚕体的影响，我们就蚁蚕生命力进行了试验调查。     

鸡布氏艾美耳球虫致病性研究

用１８日龄公雏作为试验对象，以增重、病变和死亡为判定指标，用Ｅ．ｂｒｕｎｅｔｉ的０．５万／只、１万、５万、１０万、２０万、５０万和１００万／只为接种梯度，研究了布氏艾美耳球虫的致病性。结果表明：接种０．５万／只至２０万／只剂量的Ｅ．ｂｒｕｎｅｔｉ都明显影响鸡的增重；（与对照组相比，均存在极显著性差异（Ｐ＜０．０１），各剂量组间增重无差异，）５０万／只和１００万／只剂量组的鸡出现减重。５０万／只剂量组鸡死亡５０％，１００万／只剂量组鸡死亡１００％；Ｅ．ｂｒｕｎｅｔｉ接种５万／只剂量组及以上各组鸡饮食欲消失，鸡失去自洁行为，粪量少，含有粘液和血液；剖检病变主要在小肠至直肠，肠壁变薄，易碎，呈粉红色至暗红色，肠粘膜上有小的出血点，肠内容物以粘液和血液为主。部分鸡的盲肠内容物干、呈暗红色。（病变计分为：对照组０分，０．５万／只为０．５７＋；１万／只０．０３＋；５万／只１．１７＋；１０万／只１．５０＋；２０万／只２．２３＋；５０万／只３．６４＋；１００万／只３．８３＋。）１００万／只剂量组中有两只鸡出现腿麻痹症状，不能站立。     

Cartilage proteoglycans from normal and osteochondrotic porcine joints.

Modern pigs grow fast but are highly susceptible to degenerative joint abnormalities, including osteochondrosis. Normal and osteochondrotic humeri and femurs were obtained from five normal and ten lame adolescent boars to study cartilage proteoglycans. Histological examination of joints indicated a locally-reduced intensity of proteoglycan staining by safranin-O in lesion areas of cartilage. Cartilage proteoglycans extracted with 4.0 M guanidinium chloride were studied using Sepharose 2B gel chromatography. The proteoglycans from severely osteochondrotic joints were less (P less than 0.05) aggregated and contained a greater (P less than 0.05) proportion of smaller monomers than those from normal joints. Loss or damage of core protein, including its hyaluronic acid-binding regions, may account for the greater proportion of small monomers. The results also indicated that the proportion of hyaluronic acid in the total glycosaminoglycan uronic acid fraction, estimated by Sephadex G-200 chromatography and cellulose acetate electrophoresis, was lower (P less than 0.05) for the extracted proteoglycans than for the residual or the whole cartilage proteoglycans in all joints studied.     

浅析我国麻类产品的地位和开发前景

全面分析了世界主要麻类作物的地位,论述了麻类产品的开发前景。     

晚松球果烘干取种试验

根据恒温干燥箱（设立４种温度）烘裂晚松球果取种，进行发芽试验的结果，选择适宜温度（４１℃～５０℃）用ＩＨＴ球果烘干机烘干晚松球果，烘干３２ｈ，脱粒后取种，进行发芽测定。结果表明，种子发芽率为８８％，发芽势为６７％，大大缩短了晚松种子处理周期。