RESUMO
Seasonal and topographical variations of abundance and quality composition of periphyton at up and down stream of Imphal, Thoubal and Khuga rivers were studied from 1999-2002. It was found that periphyton population was high (3,055-53,450 u cm-2) and fluctuated in a wide range. Upper stretches (3053-53,450 u cm-2) of the rivers have higher periphyton population and showed definite seasonal fluctuation than the middle and lower stretches (3,276-16,320 u cm-2). Species richness was also higher in upper stretches in comparison to lower stretches of all the rivers. Bacillariophyceae dominated the periphyton population and contribution of Cyanophyceae was nominal. Shannon and Weaver species diversity index was within the favorable range and evenness value for all the rivers were near unity and reflected a stable and unpolluted aquatic environment of the rivers.
RESUMO
The fisher folk are belongs to schedule cast community. They are known as Koibotra community in Assam. The total 50 families of the village were surveyed during the study. The results reveal that total number of population of the village was 210; 61.90 % (literate) and 38.1% (Illiterate). Among the literate population, 51.53 % have upto primary, 33.84 % up to middle school, 11.53 % up to matriculation and only 3.07 % of the fisherman was found to be higher degree. The peoples were in different services such as agriculture (23.81 %), fishing (28.1 %), business (19.52 %), service (15.24 %) and labour (13.33 %). Again, 90% people were lived in the kachcha house and remaining (10 %) in pukka house while, per month income was found to be lowest (Rs. 500-1000) in the age of 20-30 and highest (1500- 4000) in the age of 50-60 group. The overall fish production of the beel was 1757 kg/yr. Out of these productions, miscellaneous was found to be maximum (679 kg/yr) with 38.65% while feather back was minimum (218 kg/yr) with 12.41%. Production of carp was lowest but production of small fishes was highest. All the villagers were not only confined in fishing but also in different occupation, because of reducing fish production in the beels due to overexploitation, siltation, human activities etc.
RESUMO
Two vitamin A2 compounds (3-dehydroretinol and 3-dehydroretinyl palmitate) which are predominantly present in fresh water fish have been found to be very effective in inhibiting the microsome catalysed formation of DNA adduct by the carcinogen aflatoxin B1. The inhibition appears to be due to modulation of microsomal enzymes which activate the carcinogen. Such inhibition may suggest a potential chemopreventive role of these compounds against carcinogenesis induced by aflatoxin B1.