不同氮源对红檬实生苗菌根依赖性的影响

将红檬实生苗培养于改良无土基质中，接种泡囊－丛枝菌根Ｇｌｏｍｕｓｃｉｔｒｏｃｏｌｕｍ，以不接种菌根为对照，并分别施用含氮量相等的３种氮肥，即硝酸按（ＮＯ３－Ｎ）、尿素（ＮＨ２－Ｎ）和硫酸铵（ＮＨ４－Ｎ）。接种菌根１６周后，施不同氮肥的红檬实生苗均有效地感染了菌根，并促进了植株的生长。试验证明，红实生苗施硝态氮（ＮＯ３－Ｎ）使植株的菌根依赖性有明显提高。     

Studies on efficacy and stability of a vaccine bait containing ERA strain of rabies virus propagated in a BHK-21 cell line.

In a dose response study in foxes, the median protective dose of ERA BHK21 vaccine in a blister pack bait was 10(6.0) tissue culture infective doses (TCID)/mL, while artificially aged baits with titers of 10(6.3) TCID/mL induced seroconversion in 78% of foxes. There was no significant difference in the development of antibodies in foxes receiving 1, 2 or 3 mL volumes of vaccine in the bait. When baits were exposed to the elements and fed to foxes over a 21 day period, 85% of the animals seroconverted. Age, sex and the way in which the vaccine container was contacted did not appear to be factors in the responses of these animals. Juvenile foxes, approximately six months of age, were marked more readily with the tetracycline bait marker than older animals. Approximately 25% of foxes did not appear to respond well to vaccination and the titer of the vaccine was a critical factor in producing seroconversion in these animals.     

Inheritance of myotonic discharges in American quarter horses and the relationship to hyperkalemic periodic paralysis.

Electromyography (EMG) was used to detect myotonic discharges in Quarter Horse breeding stock and to follow the results of mating horses with hyperkalemic periodic paralysis (HPP). The studies were performed on two brood mare farms. A total of six breeding stock showed myotonic discharges and 15 were nonmyotonic. Myotonic discharges were seen in five of six horses belonging to the blood line previously implicated as being predisposed to HPP. Two of these horses had shown clinical signs of HPP. Only one of 15 breeding horses unrelated to the HPP predisposed blood line showed myotonic discharges. When both parents were non-myotonic on EMG than the F1 generation (n = 6) were also nonmyotonic. When a stallion with HPP and myotonic discharges was mated to eight nonmyotonic mares over a six year period half the animals of the F1 generation (n = 25) showed myotonic discharges. When both parents showed myotonic discharges four F1 offspring were myotonic and two were nonmyotonic on EMG testing. There was no evidence of sex linkage. The results are consistent with an autosomal dominant mode of inheritance. Hyperkalemic periodic paralysis and myotonic discharges on EMG may be different manifestations of the same underlying defect.     

Studies on mutlispecific resistance of gastrointestinal nematodes to benzimidazoles on dairy-goat farms

Multispecific resistance to benzimidazoles was studied in three selected farms. These farms had bred dairy goats for more than 15 years. The helminths were introduced with the goats at the establishment of the farms which afterwards remained isolated. Nematode resistance could then be related to their own management practices. Faecal egg count tests and egg hatch assays were performed to assess intensity of resistance. The generic (infective larvae in faecal cultures) and specific richness (adult worms) were assessed. The resistant species were Trichostrongylus colubriformis, Teladorsagia circumcincta, Haemonchus contortus and Oesophagostomum venulosum. Faecal egg count reduction tests and egg-hatch assays did not match exactly. Faecal larval counts after treatments gave a distorted picture of multispecific resistance: Haemonchus and Oesophagostomum were very largely over represented. The number of species found in the three farms was relatively low compared with other reports in goat farms of the area. This reduction of diversity might also be due in part to characteristics of breeding management and history (use of permanent pasture and introduction of goats at the establishment of farm).     

柚木(Tectona grandis)无性系繁育及造林技术

柚木为马鞭草科柚木属植物,是世界上最珍贵的用材树种之一。文章介绍了柚木的生物学特性、无性繁殖即组培技术要点以及造林技术,论述了柚木在我省的推广前景。     

鸭瘟病毒的PCR检测及其产物分析

根据基因库中已有的鸭瘟 Ul6的序列 ,合成一对引物 ,对 3株鸭瘟病毒进行 PCR扩增 ,均扩增出大小约 42 0 bp的特异性片段。进行测序 ,结果表明 3个毒株扩增后的片段均为 42 1bp。经重复实验后确定最佳反应条件 ,按该条件对两例临床病料进行检测 ,结果均出现大小约为 42 0 bp的特异片段。PCR产物与 L ake Andes株的相关序列比较 ,广东毒株与 L ake Andes株同源性较高     

羔羊全营养代乳粉对羔羊增重影响的试验

为了研究羔羊出生后采取人工饲喂代乳粉溶液的效果，对10日龄羔羊称重，以平均日增重与母乳组比较，用t检验方法检验差异显著性。研究结果显示羔羊平均日增重试验组为0.097-0.126kg，母乳组为0.071-0.113kg，二者没有显著差异。在生产中，代乳粉能替代绵羊母乳饲喂羔羊，对多胎品系羊的推广应用以及解决绵羊缺乳、少乳或无乳问题具有重要意义。