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This study analysed buffaloes from north-east India and compared their nuclear and mitochondrial DNA variations with buffaloes of mainland India, China, Mediterranean and South-East Asia. Microsatellite genotypes of 338 buffaloes including 210 from six north-east Indian buffalo populations and three mainland Indian breeds were analysed to evaluate their genetic structure and evolutionary relationships. Phylogenetic analysis and multidimensional scaling plot of pairwise FST revealed the clustering of all swamp-type buffaloes of north-east India with Lower Assamese (significantly hybrid type) buffaloes in one plane and all the mainland river buffaloes in another plane while the upper Assamese buffaloes being distinct from both these clusters. Analysis of mtDNA D-loop region of 530-bp length was performed on 345 sequences belonging to 23 buffalo populations from various geographical regions to establish the phylogeography of Indian water buffalo. The swamp buffaloes of northeast India clustered with both the lineages of Chinese swamp buffalo. Multidimensional scaling display of pairwise FST derived from mitochondrial DNA data showed clustering of upper Assamese, Chilika and Mediterranean buffaloes distinctly from all the other Indian buffalo populations. Median-joining network analysis further confirmed the distinctness and ancestral nature of these buffaloes. The study revealed north-east region of India forming part of the wider hybrid zone of water buffalo that may probably extend from north-east India to South-East Asia. [ABSTRACT FROM AUTHOR]

It is now a well-accepted notion that each new experimental design requires proper evaluation of internal control genes (ICGs) for accurate normalization of expression data. In riverine buffaloes, till date no appropriate ICG has been reported for studying transcriptional response under any of the physiological stressful condition. The objective here was to test 16 well-known reference genes from different functional categories that could serve as suitable ICG during heat stress studies in buffalo mammary tissue. Briefly, the mammary explants were exposed to 45°C for 1 h and subsequently allowed to recover at 37°C for different time points (2-24 h). Three software programs, geNorm, Normfinder and BestKeeper, were used to measure gene transcript stability. RPL22 was excluded because of weak amplification and unacceptable PCR efficiency. Except GAPDH, all other genes showed expression stability within the acceptable range (<1.5). RPL4, B2M, RPS23 and EEF1A1 genes were found to be most stably expressed while GAPDH and ACTB showed least stability. The BestKeeper analysis identified high correlation for RPL4 ( r = 0.953) and EEF1A1 ( r = 0.914) with BestKeeper index. Based on the present findings, it could be suggested that geometric average of RPL4, B2M, RPS23 and EEF1A1 would provide accurate normalization to transcriptional data of buffalo mammary explant in response to heat stress. [ABSTRACT FROM AUTHOR]