Maternal transmission of mitochondrial DNA in ducks

Mitochondrial D-loop analysis for uncovering the population structure and genetic diversity among the indigenous duck (Anas platyrhynchos) populations of India

The indigenous domestic duck (Anas platyrhynchos domestica) which is domesticated from Mallard (Anas platyrhynchos) contributes significantly to poor farming community in coastal and North Eastern regions of India. For conservation and maintenance of indigenous duck populations it is very important to know the existing genetic diversity and population structure. To unravel the population structure and genetic diversity among the five indigenous duck populations of India, the mitochondrial D-loop sequences of 120 ducks were analyzed. The sequence analysis by comparison of mtDNA D-loop region (470 bp) of five Indian duck populations revealed 25 mitochondrial haplotypes. Pairwise F_ST value among populations was 0.4243 (p < .01) and the range of nucleotide substitution per site (Dxy) between the five Indian duck populations was 0.00034-0.00555, and the net divergence (Da) was 0-0.00355. The phylogenetic analysis in the present study unveiled three clades. The analysis revealed genetic continuity among ducks of coastal region of the country which formed a separate group from the ducks of the inland area. Both coastal as well as the land birds revealed introgression of the out group breed Khaki Campbell, which is used for breed improvement programs in India. The observations revealed very less selection and a single matrilineal lineage of indigenous domestic ducks.

Development of pedigree classification using microsatellite and mitochondrial markers for Giant grouper broodstock (Epinephelus lanceolatus) management in Taiwan

Most giant groupers in the market are derived from inbred stock. Inbreeding can cause trait depression, compromising the animals' fitness and disease resistance, obligating farmers to apply increased amounts of drugs. In order to solve this problem, a pedigree classification method is needed. Here, microsatellite and mitochondrial DNA were used as genetic markers to analyze the genetic relationships among giant grouper broodstocks. The 776-bp fragment of high polymorphic mitochondrial D-loop sequence was selected for measuring sibling relatedness. In a sample of 118 giant groupers, 42 haplotypes were categorized, with nucleotide diversity (π) of 0.00773 and haplotype diversity (HD) of 0.983. Furthermore, microsatellites were used for investigation of parentage. Six out of 33 microsatellite loci were selected as markers based on having a high number of alleles and compliance with Hardy-Weinberg equilibrium. Microsatellite profiles based on these loci provide high variability with low combined non-exclusion probability, permitting practical use in aquaculture. The method described here could be used to improve grouper broodstock management and lower the chances of inbreeding. This approach is expected to lead to production of higher quality groupers with higher disease resistance, thereby reducing the need for drug application.

Sequences and comparisons of duck mitochondrial DNA control regions

In this study, the nucleotide sequences of the displacement loop (D-loop) and the ribosomal RNA genes of mitochondrial DNA (mtDNA) were determined from a representative each of two genera of ducks, Cainina muschata and Anas platyrhynchos. The duck mtDNA shows a specific gene order at 5' upstream of D-loop (5'ND6-tRNA(Glu)-D-loop3') that is identical to chick mtDNA but is different from that of mammalian or amphibian (5' cytochrome b-tRNA(Thr)-tRNA(Pro)-D-loop3'). Nucleotide diversity is greatest in the D-loop while being most conserved in the 12S rRNA gene, as indicated from a sequence comparison between duck and chick mtDNA. A consensus sequence in the D-loop region, which may play influential roles in the regulation of transcription and replication of mtDNA, was found in both CSB-1 and repeated sequences of birds. Sequences of four tRNA genes in this region are also reported. Among them, tRNA(Glu) shows the greatest sequence divergence when different order of birds are compared.

Complete homology in metallothionein from two genera of ducks and their hybrids

Metallothionein purified from two genera of domesticated duck, Anas platyrhnchos and Cairina muschata, and their hybrid were analyzed and shown to consist of one identical amino acid sequence. Since most vertebrates carry two or more isospecies of this inducible, thiol rich, metal sequestering protein, this finding suggests that duck metallothionein is evolutionary primitive.