Molecular detection of adulteration in chicken products based on mitochondrial 12S rRNA gene.

The aim of this study is to detect the fraudulent in chicken products constitutes in order to protect consumers in Saudi Arabia from illegal substitutions. Two different approaches were used in this study, direct sequencing of specific fragments of amplified mitochondrial 12S rRNA gene in addition to species-specific PCR primers for confirmation of the obtained Blast search results. The results showed that all processed chicken products were identified as chicken (Gallus gallus) by 90-98% homology depending on obtained sequence quality. Samples labeled with chicken luncheon (samples tested in this study) were identified as turkey meat (Meleagris gallopavo) by 98% homology, suggesting adulteration with inedible parts of turkey in chicken luncheon ingredients. The results showed also that not only chicken luncheon was mixed with inedible parts of turkey but also all chicken products tested in this study (chicken balls, chicken burger, chicken sausage and chicken mined meat) contained this turkey meat. Applying methods used in this study could be useful for accurate and rapid identification of commercial processed meat.

Generation of diversity by somatic mutation in the Camelus dromedarius T-cell receptor gamma variable domains.

In jawed vertebrates the V-(D)-J rearrangement is the main mechanism generating limitless variations of antigen-specific receptors, immunoglobulins (IGs), and T-cell receptors (TCRs) from few genes. Once the initial diversity is established in primary lymphoid organs, further diversification occurs in IGs by somatic hypermutation, a mechanism from which rearranged TCR genes were thought to be excluded. Here, we report the locus organization and expression of the T-cell receptor gamma (TCRG) genes in the Arabian camel (Camelus dromedarius). Expression data provide evidence that dromedary utilizes only two TCRG V-J genomic arrangements and, as expected, CDR3 contributes the major variability in the V domain. The data also suggest that diversity might be generated by mutation in the productively rearranged TCRGV genes. As for IG genes, the mutational target is biased toward G and C bases and (A/G/T)G(C/T)(A/T) motif (or DGYW). The replacement and synonymous substitutions (R/S) ratios in TCRGV regions are higher for CDR than for framework region, thus suggesting selection toward amino acid changes in CDR. Using the counterpart human TCR γδ receptor as a template, structural models computed adopting a comparative procedure show that nonconservative mutations contribute to diversity in CDR2 and at the γδ V domain interface.

Microsatellite instability at three microsatellite loci (D6mit3, D9mit2 and D15Mgh1) located in different common fragile sites of rats exposed to cadmium.

Cadmium (Cd) is a non-essential element and is a widespread environmental pollutant. Exposure to cadmium can result in cytotoxic, carcinogenic and mutagenic effects. Mutagenesis is an indicative of genetic instability and can be assayed using microsatellites instability. The aim of the present study is to investigate; based on the rat model, the effects of oral acute (single 8.8mg/kg BW, 1/10 LD(50)) and sub-chronic (2.93mg/kg BW, 1/30 LD(50), for 4 weeks) doses of cadmium chloride on microsatellite instability at D6mit3, D9mit2 and D15Mgh1 loci, which are located in three different common fragile sites (6q21, 9q32-q33 and 15p14, respectively), within rat genome. In the acute study, no microsatellite instability (MSI) was observed in all the three tested loci (D6mit3, D9mit2 and D15Mgh1). In the sub-chronic study, the MSI were observed in the three studied loci and was in the form of deletion of 2-3bp or addition of 3-6bp. These finding may indicate the sensitivity of microsatellite sequences located at the fragile sites and the sensitivity of the simple sequence repeats (SSRs) assay for the detection of small variations in DNA sequence. However, additional chronic toxicological trials are needed in order to assess genotoxic effects of chronic exposure to Cd.