SNP genotyping in sheep from northwest and east China for meat traceability
Meat traceability is essential for meat safety and to solve adulteration issues. Single nucleotide polymorphisms (SNPs) are commonly used as a DNA marker and provide a way to trace meat and meat products. The high resolution melting method is a relatively cheap and fast method for detecting specific SNPs. In the present study, we selected 8 SNPs from the NCBI dbSNP database and tested their feasibility in blood or meat samples from 135 sheep reared in northwestern and eastern China. The results indicated that seven SNPs were suitable for meat traceability and the probability of 2 individuals having the same genotype was 1.85 out of 1000.
Development of a 25-plex SNP assay for traceability in cattle.
Single nucleotide polymorphisms (SNPs) are amenable to automation and therefore have become the marker of choice for DNA profiling. SNaPshot, a primer extension-based method, was used to multiplex 25 SNPs that have been previously validated as useful for identity control. Detection of extended products was based on four different fluorochromes and extension primers with oligonucleotide tails of differing lengths, thus controlling the concise length of the entire chromatogram to 81 bases. Allele frequencies for Holstein, Simmental, Limousin, Angus, Charolais and Tux Cattle were estimated and significant positive Pearson-correlation coefficients were obtained among the analysed breeds. The probability that two randomly unrelated individuals would share identical genotypes for all 25 loci varied from 10(-8) to 10(-10) for these breeds. For parentage control, the exclusion power was found to be 99.9% when the genotypes of both putative parents are known. A traceability test of duplicated samples indicated a high genotyping precision of >0.998. This was further corroborated by analysis of 60 cases of parent-sib pairs and trio families. The 25-plex SNaPshot assay is adapted for low- and high-throughput capacity and thus presents an alternative for DNA-based traceability in the major commercial cattle breeds.
Pasteurella haemolytica serotype 1 colonization of the nasal passages of virus-infected calves.
Nasal passages of calves with a virus-induced respiratory tract disease became colonized by Pasteurella haemolytica serotype 1 after they were inoculated intranasally with P haemolytica. Inoculation with infectious bovine rhinotracheitis virus caused a more severe clinical illness and resulted in a greater degree of colonization with P haemolytica than developed after inoculation with parainfluenza-3 virus. Nasal passages of parainfluenza-3 virus-inoculated calves were colonized to a greater degree with P haemolytica than were those of healthy, nonstressed calves. Calves were susceptible to P haemolytica colonization during or shortly after virus-induced illness, even though they had been previously exposed to P haemolytica and had serum antibody and nasal secretion antibody to P haemolytica.