| The molecular genetic linkage map of duck is essential for the identification and localization of quantitative trait loci (QTL) as well as for the marker-assisted selection program to improve production traits in this bird. However, only a limited number of duck (Anas platyrhynchos) microsatellite markers have been isolated, and the genetic map of duck has not been developed. The purposes of this study include three aspects. First is to isolate some microsatellite DNA sequences by microsatellite libraries. Second is to develop the genetic map in duck genome. The last one is to localize some QTL for growth, carcass traits and meat quality in duck by regression interval mapping.Microsatellite-enriched Libraries, which enriched for (CA)n, (CAG)n, (GCC)nand (TTTC)n, were constructed using the streptavidin-coated magnetic beads. A total of 1181 random clones were sequenced, 832 (73. 18%) were found to contain (CA)n, (CAG)n, (GCC) n or (TTTC) n microsatellites with five or more repeats. Of the 832 sequences, 571 contained >15bp of uninterrupted core repeats. And the inserted fragment ranged from 300 to 1000, with an average of 372. 87 bp. The microsatellite sequences were divided into four categories: perfect repeat (65.29% of total), imperfect repeat (13.29% of total), compound repeat (8.25% of total), and other repeat (13.27% of total). Among the perfect repeat, the sequence with (CA)n motif was 64.56%, with (CAG)n was 12.81%, with (GCC)n was 1.58%, and with (TTTC)n was 13. 17%. And the among the imperfect repeat, the sequence with (CA)n was 70.69%, with (GCA)n was 6.03%, with (GCC)n was 1.58%, and with (TTTC)n was 5.96%. Primers were designed and synthesized using sequence information from 300 clones, which contained >15bp of uninterrupted core repeats in the enriched libraries. One primer in each pair was labeled with either 6-FAM or HEX, or appended with the forward universal primer (Ml3) at its 5" end. In the later, the primer with M13 tail, the sequence-specific reverse primer, together with the universal fluorescent-labeled M13 primer would take part in the PCR reaction. Of the 300 primer pairs, 138 were suitable for genotyping with the expected size fragments obtained by modifying the annealing temperature. Their polymorphisms were detected in the genomic DNA of 31 unrelated individuals according to the conditions of the optimized multiplex PCR and multi-run. Of the 138 pairs, 113 exhibited the sequence length polymorphisms in 31 individuals. A total of 525 alleles were observed from these polymorphic microsatellite markers in the detected animals, and the numbers of alleles ranged from 2 to 18 with an average of 4. 68 per microsatellite locus. In the detected individuals, the heterozygositis of the polymorphic loci ranged 0.03 to 1 with an average of 0.48, and the polymorphism information cotent (PIC) of those loci ranged 0. 03 to 0. 97 with an average of 0. 46.A preliminary linkage map was developed by segregation analysis of 113 polymorphic markers in the population, which consisted of 12 full sib families with a total of 224 F2 individuals. 85 markers were placed into 16 linkage groups and 28 markers were unlinked. The total length of preliminary linkage map for duck is 1110. 7cM (sex-averaged map), as in other poultries, the total of genetic map for the female with 928.7 cM is shorterthan that for the male with 1377. 2cM. However, the length of some linkage groups for the female map is larger than that for the male.Some QTLs affecting body weight at week 1 to week 7 were mapped on group 1, 4, 6, 10 and 16. The number of suggestive (0. 01 |
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