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.
Molecular Epidemiology of Mycoplasma pneumoniae: Genotyping Using Single Nucleotide Polymorphisms and SNaPshot Technology
ABSTRACT Molecular typing of Mycoplasma pneumoniae is an important tool for identifying grouped cases and investigating outbreaks. In the present study, we developed a new genotyping method based on single nucleotide polymorphisms (SNPs) selected from the whole-genome sequencing of eight M. pneumoniae strains, using the SNaPshot minisequencing assay. Eight SNPs, localized in housekeeping genes, predicted lipoproteins, and adhesin P1 genes were selected for genotyping. These SNPs were evaluated on 140 M. pneumoniae clinical isolates previously genotyped by multilocus variable-number tandem-repeat analysis (MLVA-5) and adhesin P1 typing. This method was also adapted for direct use with clinical samples and evaluated on 51 clinical specimens. The analysis of the clinical isolates using the SNP typing method showed nine distinct SNP types with a Hunter and Gaston diversity index (HGDI) of 0.836, which is higher than the HGDI of 0.583 retrieved for the MLVA-4 typing method, where the nonstable Mpn1 marker was removed. A strong correlation with the P1 adhesin gene typing results was observed. The congruence was poor between MLVA-5 and SNP typing, indicating distinct genotyping schemes. Combining the results increased the discriminatory power. This new typing method based on SNPs and the SNaPshot technology is a method for rapid M. pneumoniae typing directly from clinical specimens, which does not require any sequencing step. This method is based on stable markers and provides information distinct from but complementary to MLVA typing. The combined use of SNPs and MLVA typing provides powerful discrimination of strains.
Effects of thyrotropin-releasing hormone and a thyrotropin releasing hormone analog on growth and selected plasma hormones in lambs.
An 8-wk growth trial was conducted to assess the effects of continuous infusion of thyrotropin-releasing hormone (TRH) and an active TRH analog less than Aad-His-Pro-NH2 (the less than Aad is L-pyro-alpha-aminoadipic acid) on growth trial performance, carcass composition and hormone profiles of growing lambs. Both drugs were infused at 600 micrograms X lamb -1 X d -1 with 16 lambs/treatment. Both TRH and less than Aad-His-Pro-NH2 decreased average daily gain (ADG; P less than .01) and increased feed conversion (FC; P less than .01) compared with saline infused controls. Average daily feed intake was not altered. Carcasses of lambs given TRH or less than Aad-His-Pro-NH2 contained fewer kilograms of moisture (P less than .05) and appeared to contain fewer kilograms of protein. Thyrotropin-releasing hormone and less than Aad-His-Pro-NH2 increased thyroid gland weights (P less than .05), but pituitary gland weights were not different. Plasma thyrotropin (TSH) concentrations were increased by both drugs compared with control lambs, peaking at 4 to 7 d after initiating infusion. However, by 14 d, TSH concentrations returned to control levels. Triiodothyronine (T3) and thyroxine (T4) were elevated by both drugs over the entire 8-wk trial, with peak levels reached at 10 d and maintained for the duration of the study. Both TRH and less than Aad-His-Pro-NH2 increased prolactin over the entire period. Growth hormone levels were not altered by either drug. The effects of less than Aad-His-Pro-NH2 infusion on growth trial performance, carcass composition and hormone profiles of growing lambs were very similar to TRH. The negative effects of TRH and less than Aad-His-Pro-NH2 infusion on ADG, FC and carcass protein appear to be the result of elevated T3 and T4 levels.