Seasonal variation of gut Cyanophyta contents and liver GST expression of mud carp （Cirrhina molitorella） and Nile tilapia （Oreochromis niloticus） in the tropical Xiangang Reservoir （Huizhou, China）

Liver glutathione S-transferase(GST) plays a major role in the detoxification of microcystins(MCs) via conjugation to glutathione(GSH).We evaluated the relationship between seasonal variation in fish gut contents and the expression of GST isoforms in mud carp(Cirrhina molitorella) and Nile tilapia(Oreochromis niloticus).We quantified the abundance and diversity of plankton in the water column and foregut of mud carp and Nile tilapia in the tropical Xiangang Reservoir between October 2007 and July 2008.The mRNA expression of 7 liver GST isoforms was determined by real-time RT-PCR.The gut contents of both species were dependent on the amount and type of phytoplankton and zooplankton in the water.The expression of liver GST genes in Nile tilapia and mud carp was positively and negatively correlated,respectively,with the abundance of toxic cyanobacteria in the fore-gut.The expression of liver GST mRNA was correlated to the abundance of toxic cyanobacteria in the gut contents of both species,suggesting that mRNA expression of GST isoforms could be used as a biomarker in Nile tilapia and mud carp to monitor cyanobacteria blooms in reservoirs.     

鲮鱼肌肉热变性特点的研究

研究了鲮鱼肌肉在75、85、95℃下加热时,其fh值、Kp值、失水率以及过氧化物酶活力的变化特点．研究结果表明：75℃下鲮鱼肌肉的fh值约为4．0min,失水率与加热温度成正相关关系;使鱼肉过氧化物酶完全失活所需的Vp值约为90min．加热温度高,Vp值增加速率快,使过氧化物酶失活的时间大大缩短．