The Effect of short-term hyper-ammonia exposure in Indiancatfish, Clarias magur (Hamilton, 1822) on haematological parameters, tissues structure and gene expression profiles

Abstract

In the present study, pattern of changes in blood physiological parameters, structuralchanges in gills, liver and kidnney as well as gene expression patterns for ornithine-ureacycle (OUC) were studied, under hyper-ammonia stress (25 mM NH4Cl) for 1, 3, 6 and 9 hand 24 h in normal water condition after 9 h exposure (9h+N), in Clarias magur (Hamilton,1822). Analysis showed increase in blood ammonia upto 3 h, with decreasing trend (upto2 folds reduction) subsequently. It was accompanied by simultaneous increase in urealevels upto 6 folds at 9 h exposure. However, there were no significant changes in bloodparameters, except for serum protein, serum glutamic pyruvic transaminase (SGPT) andlactate dehydrogenase (LDH) levels after 1 h exposure. Histological analysis of gills revealedhighest (88%) percentage of damaged gills with congested blood capillaries, treated for 9 h,but declined by 65% at 9h+N. Histological alterations in liver and kidney were prominentonly at 9 h exposure, with nuclear hypertrophy and necrosis of hepatic cells in liver tissuesand distension as well as degeneration of Bowman’s capsule in kidneys. Significantup-regulation of cpsIII and otc genes at 9 h and 9h+N, points to activation of OUC in liver at6 h exposure and unique physiological characteristics of turning towards ureotelism fromammoniotelism, after short term exposure to high ammonia level. Keywords:Ammonium chloride; Clarias magur, Congested capillaries, Gills, Hyperplasia, Ornithine urea cycle, Urea