Impact of brick-kiln effluent on transamination of tyrosine and mobilization of thyroid hormones in gills and hepatopancreas of Channa punctata (Bloch, 1793) with reference to histo-architecture of the tissues

Abstract

Dhubri district of Western Assam, India comprises of large number of brick-kilns yielding huge amount of ashes of burnt or partially burnt coal, supposed to be the major soil and water pollutants of the locality. This study dealt with the histological investigations of the gills and hepatopancreas of Channa punctata Bloch collected from some brick kiln-adjacent wetlands of Dumardaha Pt. II and Geramari Pt. III areas of Dhubri District with supporting observation of lipid and protein peroxidation, mobilization of thyroid and thyroid stimulating hormones, phenylalanine-tyrosine ratio in the tissues and serum ammonia-urea ratio. Studies carried out both in freshly collected fishes, acclimatized fishes and experimental fishes treated with two sub-lethal concentrations of an effluent prepared using brick-kiln refusals collected from the studied areas.

During acclimatization process of about first five weeks mortality was observed in some of the collected fishes and rest survived thereafter. Histopathological lesions were marked both in gills and hepatopancreas of freshly collected fishes, were not seen after eight weeks of survival. Similar lesions were again observed in fishes exposed to brick-kiln effluent with varied degree. Rate of lipid and protein peroxidation were observed more in both gills and hepatopancreas of freshly collected fishes and effluent-treated fishes with hypothyroidic conditions and big phenylalanine-tyrosine ratios in comparison to fishes of eight weeks survivability. These indicate healing of tissues at about eight weeks. Reobserving of similar histopathological lesions in the effluent-treated fishes revealed that brick-kiln refusals are toxic to fishes.