Growth and salt-water tolerance of juvenile Atlantic salmon, Salmo salar, reared under different combinations of dietary carbohydrate and photoperiod regime

The present study evaluated how different photoperiods, carbohydrate sources and inclusion levels influenced growth, plasma, organ and body compositions in Atlantic salmon (Salmo salar). Four different diets were used, containing 10 or 20% starch on a dry matter basis, using gelatinized corn (C10 and C20) or wheat (W10 and W20). Two different photoperiods were used, Continuous (Con) light throughout the study, Winter (Wi) two initial weeks of continuous light, thereafter 6 weeks of short day, ending with 6 weeks of continuous light. The winter regime resulted in reduced growth rate compared with continuous light. All Wi groups were smaller than Con groups when the experiment was terminated, except for fish given diet C10. Diet W10 resulted in better growth compared with all other groups when exposed to Con. regime. Atlantic salmon fed with diets containing 20% starch had lower growth rates than fish fed diets containing 10% starch, when the same starch source and light regime were compared. All fish belonging to the Con group exhibited similar and higher condition factors compared with fish from groups Wi. Condition factor was not influenced by dietary starch source. Higher whole body lipid concentrations were found when fish were given the corn compared with the wheat diets, without any responses to starch level or light regime. Whole body protein showed increased values in fish exposed to regime Wi compared with Con, without any influence from dietary manipulation. Liver glycogen values and hepatosomatic index reflected dietary starch levels and were significantly influenced by light regime, whilst muscle glycogen levels varied only as a response to light regime with lower values in fish from the Wi compared with the Con groups. Light regime influenced plasma glucose levels, except in groups fed with diet W10. All measured plasma nutrient concentrations were within normal ranges. At the end of the feeding period, all fish were evaluated for glucose and salt water tolerance to ascertain whether diet and/or light regime influenced glucose regulation capacity and/or smolt quality. Fish fed with 20% starch had reduced osmoregulatory ability measured as plasma chloride after a seawater challenge test. Fish from the Wi regime, but not from the Con regime developed characteristics associated with smoltification. Glucose tolerance in Atlantic salmon was substantially influenced by both photoperiod regime and diet. Fish reared under the Wi photoperiod showed reduced glucose regulation capacity compared with fish held under continuous light. Glucose regulation capacity was also reduced in fish adapted to the highest starch levels.     

对淳安县科技与农业转型升级深度融合的思考

从科技兴农氛围、农业服务体系、科技成果转化、龙头企业壮大、产学研合作5个方面,对浙江省淳安县科技与农业融合发展情况进行了全面的总结概述,分析了其中存在的主要问题,并提出促进淳安县科技与农业深度融合的对策。     

海口市休闲农业发展现状与转型升级对策

休闲农业是一种发展较快的新型产业。概括了海口市休闲农业的发展现状,指出了海口市休闲农业发展存在的主要问题,最后提出了促进海口市休闲农业转型升级的若干对策。     

转VEGF165基因红花的研究

【目的】构建转血管内皮生长因子165(VEGF165)基因的红花,为利用植物生物反应器规模化生产VEGF165奠定基础。【方法】采用PCR方法,克隆获得植物偏好性的VEGF165基因,将其与pOP质粒连接,构建重组质粒pOP-VEGF165,对其进行NcoⅠ和HindⅢ双酶切及PCR鉴定。采用冻融法将质粒pOP-VEGF165转入根癌农杆菌EHA105中,通过农杆菌介导获得转化红花植株,经PCR鉴定得到转基因红花阳性植株。【结果】克隆获得了495bp的VEGF165基因片段,并成功构建了植物特异表达载体pOP-VEGF165,用其转化红花子叶后,共获得了8株转基因红花植株,其中2株鉴定为阳性。【结论】获得了转VEGF165基因的红花株系。     

黄瓜遗传转化体系优化及表皮毛基因Gl的转化

选用黄瓜无毛突变体gl的子叶节为材料,对芽诱导阶段及根诱导阶段潮霉素的浓度进行筛选,分别确定2和3mg/L为其最适浓度;以pCAMBIA2301-gusA为载体,农杆菌GV3101介导,筛选出Silwet L-77(表面活性剂)的最佳体积分数为0.04%,侵染液浓度以原菌液(OD600=0.6)等倍稀释最佳;另外,对快速提取黄瓜DNA方法进行了优化。结果表明,添加500μL 0.5mol/L NaOH与200μL 100mmol/L Tris-HCl的组合最好。用优化的体系对表皮毛基因Gl进行遗传转化,获得7株阳性苗,为研究Gl基因的调控机制奠定了基础。     

类球形水果表皮颜色变化校正方法研究

针对类球形水果表面较大的曲率变化会引起表面亮度不均,从而导致水果颜色分级评价中存在误差大、准确率低等问题,提出了二维B样条水果表面亮度不均校正算法。利用该算法分别对原始RGB图像各单通道图像进行亮度校正,然后将校正后的RGB图像转换成HIS颜色空间图像,提取色调H和亮度I分量,通过对比校正前后H和I分量图像像素灰度标准差评价校正效果。对160幅橙图像处理结果表明,校正后的图像在色调和亮度上比原始图像更加均匀,色调H分量和亮度I分量的平均标准差分别仅为原始图像标准差的21.57%和33.94%,色调和亮度均匀性得到了明显的改善。     

蚯蚓转化利用畜禽废弃物研究进展综述

蚯蚓堆肥处理畜禽有机废弃物具有显著的生态、环境及社会效益.该文综合概述了畜禽有机废弃物蚯蚓堆置处理技术、影响因素及其产物（蚓体和蚓粪）应用的主要研究进展.     

大兴安岭白桦低质林改造后土壤肥力的综合评价1）

以大兴安岭白桦低质林为研究对象,通过对白桦低质林进行不同林窗、不同带宽诱导改造,应用灰色关联度法综合分析不同模式改造后的林分土壤肥力的各个指标。研究表明,所有的诱导改造对土壤肥力均有改善作用。白桦低质林林窗诱导改造中土壤肥力综合评价最高的是20 m×20 m（ G4）为0．849;不同带宽的诱导改造中最高的是14m （S3）为0．733。综合评价白桦低质林改造模式土壤肥力质量的改造效果,林窗诱导改造优于带状诱导改造模式。     

天花粉蛋白基因导入欧美杨108

为获得含有天花粉蛋白（ TCS）的转基因欧美杨108植株,进行了植物表达载体的构建以及导入欧美杨108的研究。将北京大学惠赠的含有TCS启动子及结构基因的质粒pT1-3经SacⅠ和BamHⅠ双酶切后与同样双酶切的载体pCambia1301用T4 DNA连接酶相连,转化大肠杆菌,构建植物表达载体pC-tPro-TCS。将构建的植物表达载体转入农杆菌LBA4404,采用农杆菌介导法,将其导入欧美杨108中。结果表明,共得到18个潮霉素抗性愈伤和抗性芽,转化效率为4．3％。抗性体经PCR和PCR-Southern检测,初步确认TCS基因已经导入到欧美杨108中。     

堆肥过程中碳、氮转化与温室气体排放研究进展

农牧业生产事关民生,资源化处理农牧业废弃物是保证种养结合及养分循环必不可少的重要环节。实践表明,利用堆肥技术处理农牧废弃物不仅环保与安全,而且符合循环经济的要求,同时它也是目前国内外处理有机固体废弃物的主要措施。本文在分析和查阅大量文献基础上,对堆肥过程中温室气体排放动态及影响因素,有机肥堆制中碳、氮转化规律及其与微生物间的作用进行综述。分析影响堆肥碳、氮转化因子与相应的研究进展,指出研究中存在的问题并提出今后的研究方向。