When it comes to inbreeding: slower is better

Population structuring of Channa striata from Indian waters using control region of mtDNA

Striped snakehead (Channa striata) is a freshwater species of early Miocene period belonging to family Channidae. The genetic variability of the snakehead populations in India was not well known. Present study was undertaken using 149 sequences of control region of mitochondrial DNA from seven geographically distinct populations of Indian water, which resulted in 46 haplotypes with 137 variable nucleotide sites (60 singletons and 77 parsimony informative) and the nucleotide frequencies was: A = 33.0, T = 28.1, G = 15.4, and C = 23.5%. The presence of low-frequency of younger haplotypes with a large number of singletons indicates the absence of dominant haplotype. Hierarchical AMOVA showed highly significant genetic differentiation (F_ST = 0.56, p < .00) among the populations. The pattern of genetic differentiation was not consistent with geographical distributions. AMOVA identified three genetically heterogeneous clades. The significant finding of Imphal and Chaliyar was that they were found genetically close to each other, but geographically much isolated from each other. The inference of the study suggests that the hypothesis of the single panmictic population of C. striata in Indian waters is rejected.

Population structure and genetic diversity of Indian Major Carp, Labeo rohita (Hamilton, 1822) from three phylo-geographically isolated riverine ecosystems of India as revealed by mtDNA cytochrome b region sequences

The population structure and genetic diversity of Rohu (Labeo rohita Hamilton, 1822) was studied by analysis of the partial sequences of mitochondrial DNA cytochrome b region. We examined 133 samples collected from six locations in three geographically isolated rivers of India. Analysis of 11 haplotypes showed low haplotype diversity (0.00150), nucleotide diversity (π) (0.02884) and low heterogeneity value (0.00374). Analysis of molecular variance (AMOVA) revealed the genetic diversity of L. rohita within population is very high than between the populations. The Fst scores (-0.07479 to 0.07022) were the indication of low genetic structure of L. rohita populations of three rivers of India. Conspicuously, Farakka-Bharuch population pair Fst score of 0.0000, although the sampling sites are from different rivers. The phylogenetic reconstruction of unique haplotypes revealed sharing of a single central haplotype (Hap_1) by all the six populations with a point mutations ranging from 1-25 nucleotides.

Comparative transcriptome of wild type and selected strains of the microalgae Tisochrysis lutea provides insights into the genetic basis, lipid metabolism and the life cycle

The applied exploitation of microalgae cultures has to date almost exclusively involved the use of wild type strains, deposited over decades in dedicated culture collections. Concomitantly, the concept of improving algae with selection programs for particular specific purposes is slowly emerging. Studying since a decade an economically and ecologically important haptophyte Tisochrysis lutea (Tiso), we took advantage of the availability of wild type (Tiso-Wt) and selected (Tiso-S2M2) strains to conduct a molecular variations study. This endeavour presented substantial challenges: the genome assembly was not yet available, the life cycle unknown and genetic diversity of Tiso-Wt poorly documented. This study brings the first molecular data in order to set up a selection strategy for that microalgae. Following high-throughput Illumina sequencing, transcriptomes of Tiso-Wt and Tiso-S2M2 were de novo assembled and annotated. Genetic diversity between both strains was analyzed and revealed a clear conservation, while a comparison of transcriptomes allowed identification of polymorphisms resulting from the selection program. Of 34,374 transcripts, 291 were differentially expressed and 165 contained positional polymorphisms (SNP, Indel). We focused on lipid over-accumulation of the Tiso-S2M2 strain and 8 candidate genes were identified by combining analysis of positional polymorphism, differential expression levels, selection signature and by study of putative gene function. Moreover, genetic analysis also suggests the existence of a sexual cycle and genetic recombination in Tisochrysis lutea.

Mitochondrial and pedigree analysis in Przewalski's horse populations: implications for genetic management and reintroductions

BACKGROUND AND AIMS

Przewalski's horses have been imported from the western zoos to China since 1985. Yet the genetic diversity in China's populations has not been studied, thus lacking of such knowledge inevitably affects this population's management. The aim of this study was to assess genetic diversity in Chinese population of Przewalski's horses via mitochondrial DNA (mtDNA) control region and pedigree analysis.

MATERIALS AND METHODS

Two captive and one reintroduced populations were examined based on mitochondrial DNA control region variation via fecal sampling from 2010 to 2012, together with pedigree analysis.

RESULTS

Amplification success rates of fecal mtDNA were as high as 96.2% (93.8%-100%), and were higher for sample in winter than in summer and autumn. Two haplotypes were identified and shared among three populations, but the proportion of individuals with each haplotype varied among the three populations (F(ST) = 0.10874, p = 0.00978). Haplotype diversity in the released population (0.153) was much lower than that in the two captive populations (0.4011 and 0.4966), in accordance with the direction of increase in probability of identity at the dam lines.

CONCLUSION

Future concerns in Przewalski's horse population management should emphasize on strict reproduction control to minimize inbreeding in captivity, followed by long-term genetic diversity guidelines and non-invasive monitoring in the reintroduction programmes.