Association of T1740C polymorphism of L-FABP with meat quality traits in Junmu No. 1 white swine.

This study was designed to investigate a single nucleotide polymorphism in intron 1 of the liver fatty acid-binding protein (L-FABP) gene in 156 Junmu No. 1 white swine using PCR-single-strand conformational polymorphism. The association between the polymorphism and meat quality traits was also studied. The cloning and sequencing results indicated that the polymorphism in intron 1 was due to a T→C mutation at position 1740 of L-FABP, yielding three genotypes (TT, TC, and CC). Association analysis revealed that the polymorphism had a significant effect on marbling (P < 0.05): genotype CC had more marbling than TC, and TC had more marbling than TT. The polymorphism also had a highly significant effect on intramuscular fat content (P < 0.01). Genotypes CC and TC had higher intramuscular fat content than TT; there was no significant difference between CC and TC (P > 0.05). However, no significant conclusions concerning other traits could be drawn. We tentatively conclude that L-FABP is a candidate gene or a quantitative trait locus-linked gene associated with meat quality traits.

Luteinizing hormone receptor splicing variants in bovine Leydig cells.

The luteinizing hormone receptor (LHR) plays a key role in testosterone production through its interaction with the gonadotropins, LH and chorionic gonadotropin. We examined the LHR splicing pattern in bovine Leydig cells; LH-induced expression of eight cloned splicing variants was detected by real-time PCR. Luteinizing hormone applied to cultured Leydig cells resulted in expression of full-length LHR and the A and B isoforms, as well as secretion of testosterone, which first increased, then declined, and then increased further, with increased LH levels. The secretion of testosterone progressively increased with increasing LH, but the expression levels of LHR (FL, A, and B) did not increase correspondingly. We conclude that the LHR splicing pattern is complex in bovine Leydig cells, and that expression of full-length LHR and isoforms A and B changes when induced with LH.

Molecular cloning and sequence analysis of follicle-stimulating hormone beta polypeptide precursor cDNA from the bovine pituitary gland.

Follicle-stimulating hormone (FSH) plays an essential role in mammalian spermatogenesis and follicular development. In a previous study, we demonstrated that some bulls carry numerous linked mutations in the FSH beta-subunit (FSHB) gene, and that these bulls have poor-quality semen, low fertility, and slightly lower serum FSH concentration compared to those without such mutations. Here, we identified the different FSHB mRNA transcripts in such individuals and analyzed the evolutionary pattern of the FSHB open reading frame (ORF) in different species. Two different lengths of FSHB mRNA transcripts corresponding to two different polyadenylation sites in the 3'-UTR were detected in wild-type bull pituitary glands, and four different mRNA transcripts resulting from the different polyadenylation sites and linked mutations were identified in mutation-bearing bull pituitaries. All transcripts had almost the same putative FSHB precursor molecule. When the ORF sequences of wild-type and mutation-bearing genes were compared with those of other tetrapod species, the leopard frog had the lowest level of homology (57.8 and 58.1%) and the buffalo had the highest level (95.9 and 96.7%), respectively. These results indicated that the bovine FSHB gene transcribes at least two classes of mRNA in the wild-type and four classes of mRNA in the mutation-bearing individuals, which provides a new insight into the bovine FSHB evolutionary pattern. In addition, these findings lay a foundation for further study of gene expression regulation and the effects of mutations on male fertility traits in cattle.

Tradescantia-micronucleus (Trad-MCN) bioassay on clastogenicity of wastewater and in situ monitoring.

The Tradescantia-micronucleus (Trad-MCN) bioassay was used to determine the clastogenicity of wastewater samples collected from the Arena canal which contains effluent from the industrial district Benito Juarez of the city of Queretaro, Mexico. Fifteen wastewater samples which were collected, in most cases, at bi-weekly intervals beginning in September 1986 through February 1988, after a 3-fold dilution were used to treat Tradescantia plant cuttings. The clastogenicity expressed in terms of micronucleus frequencies of treated groups (30 h of treatment without recovery time) was significantly (0.01) higher than that of the tapwater control groups. The Trad-MCN bioassay was also used for in situ monitoring of air pollutants for the clastogenicity at 3 sites near the industrial and residential areas (Flores Magon, Conalep and Bellas Artes) of the city of Queretaro. Fourteen monitoring trips were made to each of the 3 sites at monthly intervals beginning in May 1988 through June 1990. Seasonal variation of micronucleus frequencies was exhibited with the peak clastogenicities shown in May and June 1988, June 1989 and April 1990 at the three sites. Micronucleus frequencies of all the exposed groups at the Conalep site, a predominantly industrial area, were markedly higher than that of the laboratory control groups throughout the 2-year period.