| 1. The cloning and sequencing analysis of sheep MBLIn the study, PCR technique was applied to amplify the sheep MBL in which the DNA was extracted from blood of Poll Dorset sheep. The target fragment was extracted and purified by using the purification kit then cloned into PBS-T vector. Consequently, the recombinant plasmid was amplified and extracted from the transformant and tested the inserting of DNA fragment. The results were as follows:(1)The fragment was 549bp, including exon 1(47bp),exon 2(107bp) and intron 1(395bp). The exon 1 and 2 coded 51 amino acids in which there were 16 Gly-X-Y repeat, following the sixth Gly-X-Y were leucine and arginine.(2) The nucleotide sequences among different species were quite conservative. The homologies of the MBL gene between the poll Dorset and cattle,human,rhesus,pig,horse,mouse,rat MBL and cattle MBL-A were 96.8%,85.7%,85.7%,84.4%,83.1%,81.2%,81.2%,80.5%. The result showed the poll Dorset sheep MBL was closed to the cattle MBL-C and it may be sheep MBL-C genotype. Comparing their amino acids encoded by different species MBL gene, GEKGEP were common amino acids, which indicated that"GEKGEP"amino acids sequences among different species were quite conservative.2. Relationship between the polymorphisms of sheep MBL gene and mycoplasma pneumoniaeAs a key anti-infection molecule in the first line of human innate immunity, A number of studies have suggested that MBL have associated with much diseases, such as immunodeficiency, specific infection, cystic fibrosis, systemic lupus erythematosus, rheumatoid arthritis et al. Sheep mycoplasmal pneumonia is a specific-infected disease caused by mycoplasma ovipneumoniae.This study was designed to investigate the polymorphisms of sheep MBL and its relationship with Mycoplasma ovipneumoniae of 155 sheep in poll Dorset,Texel,Suffolk sheep and Hu sheep by PCR-RFLP with Alu I and BssT1 I. At the same time, tested the infecting percentage of Mycoplasma ovipneumoniae in these sheep by means of indirect agglutination reaction. All these data were analyzed by DPS software, The all results were as follows:(1)Four genotype: AA,BB,AB,AC had been discovered by PCR-RFLP digested with Alu I in the four breeds sheep, all these genotypes were controlled by A,B,C allele gene. Among these genotypes and allele genes, AA was the advantage genotype and A was the advantage allele gene.(2)In the PCR-RFLP site of Alu I, statistical results ofχ2 test indicated that the polymorphism in poll Dorset and Hu sheep did not fit with Hardy-weinberg equilibrium but Texel and Suffolk sheep did. The polymorphism information contents (PIC) in Hu sheep population was the highest, followed by the poll Dorset sheep population. In Texel sheep and Suffolk sheep population the PIC were light polymorphic.(3)The results of these sheep infecting Mycoplasma ovipneumoniae were: the infecting percentage in Hu sheep was the highest, Suffolk was the lowest, and the infecting percentage of Hu sheep population was significantly higher than that of poll Dorset and Suffolk sheep, but not significantly higher than that of Texel sheep. Among Texel,poll Dorset and Suffolk sheep population, their infecting percentage were not significant.(4)In the PCR-RFLP site of AluI, the effect of polymorphism of sheep MBL gene on infecting Mycoplasma ovipneumoniae was analyzed, the results showed that the infecting probability in sheep with genotype AA were lowest significantly than that AB,AC genotype. In a word, the genotype AA plays an important role in adaptability on sheep, maybe it could be used as a marker in molecular breeding of sheep in the future.(5)In the PCR-RFLP site of BssT1I, there were only one genotype (274bp+250bp+25bp)in four breeds sheep, which indicated that there was no polymorphisms in this locus.
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