Myostatin is a regulator of myogenesis and has been implicated in the regulation of adiposity and in controlling the structure and function of tendons. Polymerase Chain Reaction Single-Stranded Conformational Polymorphism (PCR-SSCP) analysis of intron-1 was used to identify five variants (designated A-E) of the myostatin gene (MSTN). The effect of this genetic variation on growth and carcass traits was investigated in 517 Romney male lambs from 17 sire-lines, born on a South Island New Zealand farm. General linear mixed effect models revealed that the presence of allele A in a lamb's genotype was associated with decreased leg, loin and total yield of lean meat, whereas the presence of allele B was associated with increased loin yield and proportion loin yield (loin yield divided by total yield expressed as percentage). The effect of the number of allele copies present was investigated, and it was found that the absence of A, or the presence of two copies of B, was associated with increased mean leg yield, loin yield and total yield. Two copies of B were also associated with a decrease in proportion of shoulder yield, whereas two copies of A were associated with a decrease in proportion of loin yield. Associations with allele C were not detected. No associations of MSTN variation with birth weight, weaning weight, pre-weaning growth rate, draft age and hot carcass weight (H-W) were detected. These results suggest that variation in ovine MSTN is associated with meat production, but not birth weight or growth rate in New Zealand Romney sheep.

Myostatin, which is also known as growth and differentiation factor 8 (GDF8), acts as a negative regulator of skeletal muscle growth. Variation in the myostatin gene (MSTN) has been associated with variation in muscularity in many animals including sheep. Polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis was used to investigate MSTN in a diverse range of sheep breeds including the New Zealand (NZ) Romney, Coopworth, Corriedale, Dorper, Perendale, Suffolk, Merino, Dorset Down, Poll Dorset, Texel and other NZ cross-bred sheep. A total of 28 nucleotide substitutions were identified from nucleotide c.-1199 in the promoter region to c.*1813 (based on NCBI GenBank accession number DQ530260) and including the well-described substitution c.*1232G>A (MSTN g+6223G>A). Of these 28 substitutions, 3 were located in the promoter region, 3 in the 5'UTR, 11 in intron 1, 5 in intron 2 and 5 in the 3'UTR. One substitution in exon 1 (c.101G>A) potentially results in an amino acid substitution of glutamic acid (Glu) with glycine (Gly) at codon 34. Ten of these substitutions have not been reported previously. The genetic variation revealed in this study suggests this gene is more variable than hitherto reported and provides a foundation for future research into how this variation affects muscle and growth traits.

Myostatin, which is also known as growth and differentiation factor 8 (GDF8), has been reported to act as a negative regulator of skeletal muscle development. Variation in the myostatin gene (MSTN) has been associated with variation in muscularity in certain "meaty" sheep breeds. Polymerase Chain Reaction-Single Strand Conformational Polymorphism (PCR-SSCP) analysis was used to investigate allelic variation in the previously described g+6223G>A single-nucleotide polymorphism (SNP) in the 3' untranslated region (3'UTR) of MSTN. The sheep studied were 79 New Zealand (NZ) Romney lambs derived from a single sire heterozyous for g+6223G>A, which is in itself notable as this polymorphism has not been described previously in this breed. Allelic variation was observed to be associated with an abnormal gender ratio (p = 0.046) in the progeny. The presence of allele A was observed to have an effect (p<0.05) on birth weight, mean loin yield, proportion yield loin and total muscle yield. Allelic variation did not significantly affect mean shoulder yield, leg yield, proportion yield shoulder and proportion yield leg. This preliminary result suggests that while the A allele at MSTN g+6223 appears to improve some valuable traits in NZ Romney sheep, further research is required to understand if and how it may affect other traits.

In Chinese population, the PT/NBL ratio is not a very strong ultrasound marker to predict trisomy 21 fetuses. However, it can be used as an ultrasound marker for Down syndrome screening during the second and third trimester of pregnancy.

No abstract