Study On LF Gene Sequence And SNPs Of Goat

On the basis of cattle DNA and goat mRNA lactoferrin (LF) gene sequences from GenBank, partial 5'UTR to exon 17 of goat LF gene fragments was amplified. The total length of determined sequence was 30306bp, which had been handed out to GenBank, the accession number was FJ609300. In order to compareing the genetic diversity and differentiation among ruminant, sheep LF gene was sequenced (30340bp), and the accession number was FJ541507.30 point mutations were found in goat LF gene sequence, of which 1 was in exon, and 29 was in intron. The mutation in exon was 7605C>T resulting in Arg136Trp. The 29 mutation in intron were 2428C>G, 2761C>G, 6053A>G, 6538A>C, 7363A>G, 8642C>T, 8655C>T, 9284C>T, 13719C>T, 15783A>G, 15820A>G, 16820A>G, 17774A>T, 17775A>G, 17793A>G, 17808A>G, 17855C>G, 8266C>G, 18428A>G, 18930A>G, 19764C>T, 19997C>T, 20740A>G, 20989C>T, 21146C>T, 21281C>G, 23146C>T, 24300C>T, 24720A>G and 25249A>G. Meanwhile, 16 point mutations were detected in LF gene sequence of sheep, which all were in intron. The 16 mutation in intron were 2432C>T, 2764C>G, 4197C>T, 4274A>T, 4633C>T, 11038C>T, 13045A>G, 13075A>G, 13482A>G, 18072A>G, 20660C>T, 21022C>T, 21625T>G, 21706T>G, 22583T>G and 22594C>T. 21 short interspersed nuclear elements and 14 long interspersed nuclear elements were detected in LF gene of goat, and 19 short interspersed nuclear elements and 14 long interspersed nuclear elements were detected in LF gene of sheep. Moreover, 5 simple sequence repeats (SSR) was discovered in LF gene of goat and sheep, respectively.We determined a missense mutation C→T at position 7605. Meanwhile the PCR-RFLP of this mutation was performed in 300 individuals from 10 Chinese indigenous goat breeds/strain(sChengde polled goat, Chengdu Ma goat, Jining gray goat, Leizhou goat, Liaoning cashmere goat, two strains of Nanjiang brown goat, Tangshan dairy goat, Neimenggu cashmere goat and Wuan goat). The results showed that the gene frequency of allele T (50.12%) was little higher and that of allele C (49.88%) and the difference of genotypes was great among goat populations. The 7605C>T site performed higher genetic diversity in goat populations. The genetic differentiation was 0.0783 and gene flow was 2.9433 among 10 goat populations.The coding regions (CDS) sequence of LF gene of goat was obtained by splicing in this study, and 60 sequences from 11 species were studied to investigate its evolution and differentiation within and among species. Most species use TAA as stop codon for the LF gene, with only one human variation (DQ892855) using TAG. Mus musculus uses TGA, except for one variation (CT010339) with TAG. It was shown that the length of the LF gene with the complete CDS varies greatly among species, ranging from 2055 to 2190bp. Species with close relationships according to the taxonomy in the National Center for Biotechnology Information (NCBI) have a similar length of the LF gene. The longest length (2190bp) of the LF gene, in Rattus norvegicus, is due to the stop codon mutation of TAA to GAA resulting in the 66 bp elongation. And the shortest length (2055bp) is one variant type of Pan roglodytes (XM₀01150238) due to an 81bp deletion. There was length variation within species. Intricate length variations were in Canis familiaris with three variant regions, and simple length variations was in other species. Most species had abundant genetic diversity of LF gene, and genetic diversity was higher among species than within species. Novel amino acid variation sites were detected within several species (8 in Homo sapiens, 6 in Mus musculus, 2 in Capra hircus, 3 in Ovis aries, 10 in Bos Taurus and 20 in Sus scrofa). Differentiation of the LF gene was obvious among species, and the clustering result was consistent with the taxonomy in NCBI.