Effects of 2-methylisoborneol (MIB), and ethanol on the expression and activity of cytochrome P450s from the channel catfish

Injection of 1 mg kg⁻¹ of 2-methylisoborneol (MIB) caused an increase in a CYP1A-like protein of approximately 56 kDa from the kidneys of juvenile channel catfish as determined by western blot analysis using antibodies raised against trout CYP1A1. Ethoxyresorufin O-deethylase activity from kidneys of MIB-injected fish was significantly elevated as compared to ethanol-injected controls. Static exposure of juvenile channel catfish to 10 ppm MIB caused a statistically significant induction of a CYP2K-like protein of approximately 53 kDa from the livers of treated catfish as determined by western blot analysis using antibodies raised against trout CYP2K1. Treatment of juvenile channel catfish with ethanol (1 ml kg⁻¹) reduced the expression of one kidney and two constitutive liver P450s, while increasing another kidney form. There was no difference in carbon tetrachloride-induced lipid peroxidation in livers after ethanol treatment. Thus, MIB and ethanol affect the expression of at least three P450 isoforms in channel catfish tissues.     

淡水鱼池土腥异味物质含量与浮游藻类和放线菌生物量的关系

通过顶空固相微萃取-气质联用色谱测定北京市精养鱼池中两种主要土腥异味物质(土臭味素和二甲基异莰醇)含量,同时测定鱼池中浮游藻类和放线菌生物量,研究了土腥异味物质含量与浮游藻类和放线菌生物量之间的关系。结果表明,试验鱼池中土腥异味物质以土臭味素为主,土臭味素在精养鱼池中普遍存在,含量为1.22～35.58ng·L-1,二甲基异莰醇在部分鱼池中被检出,含量1.39～6.00ng·L-1。精养鱼池中共检出浮游藻类6门22属,生物量17.33～178.34mg·L-1,以硅藻和裸藻为主。放线菌共测到4个属,其中链霉菌Streptomyces sp.是主要种类,放线菌总生物量0～76×104ind.L-1。鱼池中浮游藻类总生物量与土臭味素含量正相关。浮游藻类中的颗粒直链藻Melosira granulata和条纹小环藻Cyclotella striata可能是北京地区夏秋季节淡水精养鱼池中能够产生土臭味素的主要藻类,裸藻和其他鞭毛藻类对池中异味化合物的产生可能作用较小。     

寡盐水鱼池藻菌土腥异味化合物研究

通过利用固相微萃取-气质联用色谱测定天津市寡盐水养鱼池中浮游藻类和放线菌的次生代谢产物——土腥异味化合物（土臭味素和二甲基异莰醇）浓度,感官评价养殖鱼土腥异味程度,同时测定浮游藻类和放线菌生物量,探讨鱼池中土臭味素和二甲基异莰醇浓度、浮游藻类和放线菌生物量以及养殖鱼异味之间的相互关系。结果表明,寡盐水养鱼池水体中普遍存在土臭味素和二甲基异莰醇,其中二甲基异莰醇是鱼池中的主要异味物质,浓度0．33—5302．70ng·L^-1,土臭味素浓度相对较低,0．29～12．10ng·L^-1。养鱼池中共测到6门94属的浮游藻类,生物量0．07～186．48mg·L^-1,以蓝藻Cyanophyta、裸藻Euglenophyta等种类为主。放线菌共测到3个属,总生物量0．01×10^4-1．50×10^4个·L^-1,以链霉菌属Streptomyces为主。巨颤藻Oscillatoria princeps和放线菌是天津地区寡盐水养鱼池中能够产生二甲基异莰的主要产源。水体异味和鱼肉发生异味不同步。