Study On Molecular Traceabilitry Of Yak Meat Products

In order to develop a comprehensive, rapid and accurate method that can be used to identify yak, taurine and zebu cattle as well as buffalo meats using both mtDNA and nuclear genomic information. this study explored three different extraction protocols of phenol-chloroform extraction, guanidine thiocyanate method and commercial DNA extraction Kit, separately. this experiment extracted DNAs from the fresh meats with known species origins of yak, cattle and buffloes as well as highly processed yak meat products from 10 manufacturers for molecular tests using sequences of Cyt b genes as well as three species specific microsatellite DNA markers for yak and cattle. The following results were obtained:1. The quality and quantity of the extracted DNAs were assessed using three methods of quantitative analysis through spectrophotometer, argarose gel electrophoresis and PCR amplifications for different sizes of mtDNA and nuclear genomic gene fragments.we suggest that guanidine thiocyanate method is a simple, rapid, cheap and sufficient protocol that can be used for routine DNA extraction from the yak meat products for their further molecular traceability tests.2. Within a fragment of 472 bp long Cyt b gene amplified using the universal primers, the species specific recognition sites were identified for yak as GACGCNNNN/with two fragments of 220 bp and 252 bp, for cattle as GGGCC/C with two fragments of 173 bp and 299 bp and for buffaloes as CCANNNN/NTGG with also two fragments in 69 bp and 403 bp. There was no cross-species reaction, therefore this protocol can be used for the identification of species origins in the mixed meat products.3. A total of 135 specimens from 30 packages of yak meat products marketed by the 10 manufacturers were sampled for sequencing the informative Cyt b gene fragment. The results showed that there were only 68 yak sequences, taking up 50.4%, while the remaining half of them (49.6%) were of cattle (51) and buffaloe (16) sequences. These results suggest that the yak meat products have been seriously contaminated by other sources of meats, which certainly affect badly the healthy market development of the yak meat industry.4. Combining the data from the three species specific microsatellite DNA markers for yak and cattle, the accuccy of the molecular traceability of the highly processed yak meats can be enhanced and quaranteed.