氨氮污染源区包气带剖面微生物生态分布特征的研究

包气带土壤中氨氮污染迁移规律已成为近年来国内外学者研究的重点,目前在氨氮污染迁移规律研究中采用柱实验模拟以及软件模拟的方法较多,土壤生物技术则广泛应用于污染物降解领域,而在污染物迁移规律研究中应用较少。本文采用变性梯度凝胶电泳(DGGE)技术、16S rRNA序列分析技术以及典范对应分析相结合,对华北平原3个典型氨氮污染区土壤表层至包气带剖面微环境的细菌垂直分布特征及群落结构进行研究。结合污染区土壤理化性质分析,认为包气带土壤剖面的细菌群落中存在着与氮循环、硫酸盐代谢等过程偶联的优势细菌类群,说明土壤微环境中细菌群落分布明显受氨态氮、硝态氮、亚硝态氮和硫酸盐的分布影响,进一步表明污染土壤优势菌群的群落结构信息是描述包气带土壤环境氨氮污染物迁移规律的重要参数。     

Combined Effects of Molecular Size and Electroendosmotic Flow on the Capillary Electrophoretic Behaviour of Humic Substances

The electroendosmotic flow (EOF), generated by the migration of solvated ions near the charged capillary surface, is an important factor in determining the capillary electrophoretic behaviour of humic substances (HS). We investigated the electrophoretic mobilities of HS fractions of reduced molecular-weight polydispersity extracted from peat and from a spodosol either in the presence or after suppression of the EOF. When the EOF was not suppressed, HS migrated to the cathode in spite of their negative charge. Fractionation of HS according to molecular size was achieved in polyacrylamide-coated capillaries filled with 0.05 M tris-phosphate buffer. In uncoated capillaries filled with the same buffer, all fractions had very close mobilities. Addition of polyethylene glycol MW 4000 at concentrations above its entanglement threshold caused the migration times of larger molecules to increase more than those of smaller molecules. The separation was a linear function of molecular size up to 75000 g mol^–1 for peat HS and to 50000 g mol^–1 for HS extracted from the spodosol.     

Impaired Functions in Nile Tilapia,Oreochromis niloticus (Linnaeus, 1757), from Polluted Waters

Oreochromis niloticus is an endemic species in the River Nile and represents the main object of fishery in the Nile Delta Lakes of which Lake Maryût is the smallest and most polluted. Due to current pollution problems, fish production in the lake greatly declined. Besides fish biology, this study considered a wide array of water databases in selected sites along the lake. Hydrologic and biologic data were compared to that of a reference fish hatchery. Water concentrations of ammonia, manganese, nickel, cadmium, lead and mercury proved hazardous to fish, whereas chromium, copper, iron, zinc, pH, alkalinity, hardness, phosphate, nitrate, and nitrite always fell within acceptable levels. Physiologic evaluation of O. niloticus pointed out improper growth, protein inadequacy, and functional impairment in fish inhabiting polluted sites, in particular the lake main basin. These were reflected by data of specific formulae as RNA/DNA and the relative RNA content (r) in cells of the liver and gill arches as well as by the relative mobilization of serum protein fractions. It seems, however, that growth competence is additionally affected by the stress impact exerted upon fish by massive population numbers in some cramped commercial ponds.     

泥蚶(Tegillarca granosa)不同地理居群同工酶变异及遗传分化的研究

采用聚丙烯酰胺凝胶同工酶电泳技术对韩国釜山、山东荣成、浙江奉化和乐清、福建福鼎、广东汕头和湛江7个地理群体的泥蚶进行同工酶分析，结果发现在所检测的MDH、ADH、ATPase、LDH、POD、IDH、SOD、SDH、ME、SCD和EST等11种同工酶中，除ATPase外其他10种在各地理群体之间存在着或大或小的差异，特别是汕头和湛江两地理群体与其他5个地理群体之间的这种差异尤其显著，两组间的平均酶距达0．4209，而汕头和湛江群体间的差异较小，两者酶距为0．0909；釜山、荣成、奉化、乐清、福鼎5个群体间的平均酶距也只有0．0191。这说明上述7个地理群体泥蚶已明显分化为两大类群，汕头和湛江群体为一类群，其他5个群体为一类群，两大类群的分界线在东海和南海的分界处。还对不同泥蚶群体间的同工酶分子标记的建立、不同群体间的遗传变异水平及泥蚶群体间分化的可能机制等问题进行了探讨，以期为泥蚶资源的进一步开发和利用提供科学资料。     

黑斑蛙(Rana nigromaculata)早期发育过程中乳酸脱氢酶同工酶

用垂直平板聚丙烯酸胺凝胶电泳技术对黑斑蛙早期胚胎发育过程中乳酸脱氢酶（LDH）同工酶进行研究。结果表明,黑斑蛙胚胎各个不同发育时期LDH同工酶谱有很大差异：LDH1在整个胚胎发育过程中均处于活化状态,LDH2、LDH4在原肠中期开始出现,LDH3在尾芽期开始出现。从尾芽期到尾血循环期只出现LDH－1、－2、－3和-4四条酶带,但不同时期各种同工酶的表达活性不同。