饲料中转基因成分检测及对水产动物安全性评价的初步研究

自转基因作物问世以来，转基因产品的安全性问题一直是人们关注的焦点。本文根据GenBank中登录的转基因大豆完整外源DNA序列设计了几对引物，对转基因大豆进行了巢式PCR检测。结果表明，巢式PCR可以扩增10-10g/μl浓度的DNA溶液，检测灵敏度高达0.01％。该巢式PCR技术具有高度特异性、灵敏度和很好的重复性。用巢式PCR对部分市售的水产饲料和豆制食品进行检测，90.6％的水产饲料和46.5％的食品能检测出外源基因片段，表明转基因大豆广泛存在于水产饲料和我们的日常食品中，为食品安全分析和管理提供了方法和依据。环介导的等温扩增技术（LAMP）依赖于能够识别靶序列上6个特异区域的引物和一种具有链置换特性的DNA聚合酶，在等温条件下可高效、快速、高特异地扩增靶序列。本研究建立了转基因大豆的LAMP扩增技术，针对豆制品以及饲料的转基因LAMP检测技术正在研究和开发中。 利用转基因和非转基因豆粕制作的饲料，喂养吉富罗非鱼，分别于4周、7周取样，对其体重和血液指标进行了检测。实验显示，投喂转基因饲料7周以后，增重率和血清指标，转基因组与非转基因饲料组相比没有显著差异。全血指标中白细胞数目、大血小板比率、平均血小板体积和血小板体积分布宽度4项指标显著高于非转基因饲料组，而且差异达到极显著水平。由以上结果可见，转基因大豆与非转基因大豆相比，对罗非鱼的一些生理过程造成了一定的影响，但是并未对其生长造成可见的影响。分别于投喂1h、4h和8h以后取罗非鱼胃内容物、肠道内容物和粪便，并分别于4周、7周和继续饥饿2周后，取罗非鱼不同组织，提取DNA，用巢式PCR法检测转基因大豆中的外源基因在各种组织中的分布，结果显示在胃内容物、肠内容物、粪便、心脏、肝脏、胃、肠、卵巢、精巢、脑、鳃丝、脾脏、胆囊、肌肉等不同部位的DNA中都能检测到外源基因的存在，说明转基因大豆中的外源DNA并不能被罗非鱼的消化道完全降解，其DNA片段可能通过消化吸收转移到鱼体的各种组织。在投喂转基因饲料7周以后以及停止投喂饥饿2周以后分离水体中的微生物，提取其DNA，进行转基因检测。结果显示在所分离纯化的各种微生物中都没有检测到转基因大豆中外源基因35S-EPSPS的存在。

Growth characters and photosynthetic capacity of Gracilaria lemaneiformis as a biofilter in a shellfish farming area in Sanggou Bay, China

Experiments on growth characters and ecological functions of the macroalgae Gracilaria lemaneiformis, collected from south China, were conducted in polyculture areas of kelp and filter-feeding bivalve in Sanggou Bay in Weihai City, Shandong, in north China from May 2002 to May 2003. The results of 116 days cultivation showed that the average wet weight of alga increased 89 times from 0.1 to 8.9 kg rope(-1), with an average specific growth rate ( based on wet weight) of 3.95% per day. The most favorable water layer for its growth was 1.0 - 1.8 m below the surface in July and August, with an average specific growth rate of 8.2% per day in 30-day experiments. Photosynthetic activity changed seasonally, with an average of 7.3 mg O-2 g dw(-1) h(-1). The maximum rate (14.4 mg O-2 g dw(-1) h(-1)) was recorded in July, or 19.3 mg CO2 g dw(-1) h(-1), while the minimum (0.40 mg CO2 g dw(-1) h(-1)) was in April. This study indicated that the culture of G. lemaneiformis is an effective way to improve water quality where scallops are cultivated intensively.

Seasonal variation in metabolism of cultured Pacific oyster, Crassostrea gigas, in Sanggou Bay, China

Rates of respiration and excretion of the Pacific oyster, Crassostrea gigas, were measured seasonally from June 2002 to July 2003 under ambient conditions of food, water temperature, pH, and salinity in Sanggou Bay, an important mariculture coast in north China. The aim of this study is to obtain fundamental data for further establishing an energy budget model and assessing the carrying capacity for cultivation of C. gigas in north China. Oysters were collected monthly or bimonthly from the integrated culture areas of bivalve and kelp in the bay. Oxygen consumption and ammonium and phosphorus excretion rates were measured, and ratios of O/N and NIP were calculated. One-way ANOVA was applied to determine differences among these parameters that act as a function of seasonal variation. All the physiological parameters yielded highly significant variations with season (P<0.01) The rate of respiration varied seasonally, with the highest oxygen consumption rate in July and the lowest rate in January, ranging from 0.07 to 2.13 mg O-2 h(-1) g(-1) dry tissue weight (DW). Maximum and minimum ammonium excretion rates were recorded in August and January, respectively, ranging from 0.51 to 5.40 mu mol NH4-N h(-1) g(-1) DW. Rates of phosphorus excretion varied from 0.11 (in January) to 0.64 (in July) mu mol PO4-P h(-1) g(-1) DW. The O/N and N/P ratios changed from 9.2 (in January) to 59.8 (in July) and from 4.6 (in January) to 10.9 (in August), respectively. For each season, the allometric relationship between the physiological response (e.g., rate of oxygen consumption, ammonium and phosphorus excretion) and DW of the animal was estimated using the formula: Y=a x DWb. (C) 2005 Elsevier B.V. All rights reserved.