Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/1998
Publication Date: N/A
Technical Abstract: The objective of this study was to characterize variants of leptin mRNA and to confirm their concurrent expression in individual pigs. Total RNA, extracted from fat tissue, was used in reverse transcription reactions to produce cDNA. Polymerase chain reaction (PCR) was used to produce the cDNA corresponding to the leptin mRNA coding region. The amplified DNA was then ncloned and sequenced. Three variant sequences (V1-3) were identified whic were verified by restriction enzyme digestion of PCR products. The V1 sequence is identical to that previously reported (GenBank U59894). A mutation of T214 to C in V2 results in a TTG to CTG codon change, however, both code for leucine. The point mutation giving rise to V2 creates a Hinf I restriction site. A deletion of the codon corresponding to bases 145-147 (CAG) relative to V1 and V2 results in V3, which can be selectively digested with Afl III. Fat tissue RNA from 80 individual pigs was used to generate cDNAs for subsequent PCR amplification and restriction enzyme digestion. Of the animals sampled, 50% expressed V1 alone, 47.9% expressed both V1 and V2, and 2.1% expressed V2 only. A low level of V3 mRNA was present in fat tissue from all experimental animals tested. A tendency for a reduction in time required to reach 240 lb was observed in the V1 genotype, based on a limited group of animals in which market weights were available (7 V1 and 7 V1/V2; 184.5 vs 201.4 d, SEM = 7.8; P = .15). The functional significance of the expression of V3, which appears to be a splice variant with a CAG codon (Glutamine) deletion, remains to be addressed. This study provides the first evidence of polymorphisms in porcine leptin cDNAs, creating the possibility for development of an RFLP for animal selection based on a gene with a known role in appetite control.