Partial characterization of porcine obesity gene (OBS) and its localization to chromosome 18 by somatic cell hybrids

Allelic to genome wide perspectives of swine genetic variation to litter size and its component traits

Litter size is a complex and sex limited trait that depends on various biological, managemental and environmental factors. Owing to its low heritability it is inefficaciously selected by traditional methods. However, due to higher heritability of ovulation rate and embryo survival, selection based on component traits of litter size is advocated. QTL analysis and candidate gene approach are among the various supplementary/alternate strategies for selection of litter size. QTL analysis is aimed at identifying genomic regions affecting trait of interest significantly. Candidate gene approach necessitates identification of genes potentially affecting the trait. There are various genes that significantly affect litter size and its component traits viz. ESR, LEP, BF, IGFBP, RBP4, PRLR, CTNNAL1, WNT10B, TCF12, DAZ, and RNF4. These genes affect litter size in a complex interacting manner. Lately, genome wide association study (GWAS) have been utilized to unveil the genetic and biological background of litter traits, and elucidate the genes governing litter size. Favorable SNPs in these genes have been identified and offers a scope for inclusion in selection programs thereby increasing breeding efficiency and profit in pigs. The review provides a comprehensive coverage of investigations carried out globally to unravel the genetic variation in litter size and its component traits in pigs, both at allelic and genome wide level. It offers a current perspective on different strategies including the profiling of candidate genes, QTLs, and genome wide association studies as an aid to efficient selection for litter size and its component traits.

Distribution and linkage disequilibrium analysis of polymorphisms of MC4R, LEP, H-FABP genes in the different populations of pigs, associated with economic traits in DIV2 line

PCR-RFLP was used to analyze the polymorphisms of MC4R, LEP, H-FABP genes in a swine breed composite (DIV2) and 4 swine breeds (Yorkshire, Landrace, Meishan, Bamei). The association study of these polymorphisms with several economic traits was carried out on a DIV2 population. The results obtained showed that MC4R/TaqI genotype had an effect for average backfat thickness (P < 0.05) and lean meat percentage (P < 0.05). At locus LEP/HinfI animals of AA genotype had lower test daily gain than that of BB (P < 0.01) or AB genotype (P < 0.05). At the H-FABP/HaeIII locus lean meat percentage of the individuals with genotype DD were higher than that with genotype dd (P < 0.05). Linkage disequilibrium analysis among MC4R, LEP and H-FABP revealed that these genes were independent. This represented two or more genes that could be combined together within one genotype in order to facilitate breeding for objective traits. In addition, a method allowing simultaneous detection of fragments of MC4R and LEP gene was developed.

Variations of plasma leptin in show horses during a work season

Leptin is an adipocytokine mainly expressed by adipose tissue. Secretion of leptin in healthy animals is closely related to fat mass and metabolic activity. The aim of this study was to investigate plasma leptin variations, in relation to nutritional and exercise parameters in adult show horses during a work season. EDTA-blood samples were taken at rest from 37 Iberian horses. Body weight, body condition score and fat percentage determined by ultrasonic measurement of rump fat thickness were measured. Plasma leptin was determined with a multi-species RIA kit. Linear mixed effects model was used to assess relationship between plasma leptin and other biological parameters. Plasma leptin concentration was <12.6 ng/ml (mean = 2.8 ± 1.6 ng/ml) and was significantly higher during training periods (p < 0.0001) (4.5 ± 1.7 ng/ml) than in show periods (2.0 ± 1.1 ng/ml), despite a significant increase (p < 0.0001) in energy intake. The body weight remained almost constant. The plasma leptin concentrations were significantly affected by exercise (p < 0.0001), body weight (p = 0.04) and BCS (p < 0.0001), but were not affected by percentage of fat. In conclusion, the marked decrease in leptin values observed during a period of intense (i.e. excessive) exercise could result from an adaptation to cumulative alterations in energy balance, to exercise per se or to a combination of both.

Influence of Fasting and Exercise on the Daily Rhythm of Serum Leptin in the Horse

The hormone leptin is secreted by white adipocytes and regulates food intake and energy expenditure in rodents and humans. The goal of the present study was to investigate the existence of a daily rhythm of serum leptin in horses and its dependence on fasting and physical exercise. A robust daily rhythm of leptin was found in both athletic and sedentary horses, with a daytime trough and a peak in the dark phase. While physical exercise never induced changes in circulating leptin, fasting reliably affected serum leptin levels. Food deprivation did not abolish the daily rhythm of serum leptin, but daily mean leptin levels in fasted horses were significantly lower than in regularly fed horses. This result indicates that leptin production is not a mere consequence of feeding behavior. The fact that in a large animal such as the horse a short fast decreases leptin without significantly changing the body weight demonstrates that changes in levels of circulating leptin associated with food restriction do not solely reflect changes in amount of body fat.

Daily Rhythms of Serum Leptin in Ewes: Effects of Feeding, Pregnancy and Lactation

The aim of the present study was to test whether serum concentrations of leptin in ewes vary with a daily rhythm. For this purpose, we examined 24 h serum leptin profiles of ewes exposed to natural photoperiodic conditions and subjected to two different feeding schedules (regular feeding and fasting). The results show for the first time the existence of daily rhythm of plasma leptin in regularly fed ewes, with a minimum during the light phase and a peak during the dark phase. Daily rhythms of serum leptin persisted after 50 h of fasting, although fasting shifted the peak of the rhythm to the beginning of the light phase and significantly reduced daily leptin production. To gain a better understanding of the role of leptin in the temporal organization of physiological events related to pregnancy and lactation, we measured serum leptin profiles throughout 24 h in ewes either during pregnancy or lactation. Daily leptin rhythms were found to persist during pregnancy and lactation, but both physiological conditions altered leptin concentrations. Maternal serum leptin concentration rose between early and mid pregnancy, then decreased in the late pregnancy and during lactation. Daily serum leptin concentration was significantly lower in nonpregnant, nonlactating ewes, compared either to lactating or to early pregnant ewes.

Characterization of exon 2 and intron 2 of leptin gene in Indian goats

Leptin, the hormonal product of the leptin (obese) gene (LEP), has multiple physiological effects and plays a pivotal role in the control of body growth, immune function, and reproduction. LEP gene polymorphism has been analyzed in cattle, buffalo, and pigs, and the polymorphic pattern has been associated with energy balance, milk production, and live weight and fertility trait in different livestock species. The present study has been designed to analyze polymorphism in exon 2 and intron 2 region of leptin gene in Indian goats. Genotyping was carried out in 111 kids including 70 samples from Barbari and 41 samples from Jamunapari breeds. The amplified product of exon 2 and intron 2 region of leptin gene was 152 bp and 400 bp, respectively, in both breeds. Sequencing of the exon 2 and intron 2 region of leptin gene and restriction analysis were carried out to analyze the polymorphism in goats. Five major haplotypes were observed in exon 2 region and six major haplotypes observed in intron 2 region in both breeds. Restriction fragment analysis and sequence analysis confirmed the mutation at 60 bp position of exon 2 and 100 bp position in intron 2 in all the analyzed samples. Sequences of exon 2 region of goats were unique as compared to other livestock species in BLAST analysis.

Associations of leptin gene polymorphisms with production traits in pigs

The associations of leptin (LEP) gene polymorphisms C798T, T2411C, T3266G and T3469C with production traits were investigated in a F2 pig population produced by divergent crosses. The statistical model included genotype, sex, batch and genotype by sex interaction as fixed effects and sire as random effect. Polymorphism C798T was associated with variation in total teat number (p < 0.02) and left teat number (p < 0.03), and polymorphism T3469C was associated with weight at 21 days (p < 0.03), 42 days (p < 0.05), 63 days (p < 0.02) and 77 days of age (p < 0.04) as well as feed intake (p < 0.01), average daily gain (p < 0.01), feed conversion (p < 0.01), bacon depth (p < 0.03) and slaughter weight (p < 0.03). Phenotypic associations were also performed by combining T3469C and C798T genotypes. Interaction between C798T genotypes and sex was observed for some traits. LEP genotypes had significant influence on performance traits, and can be considered as potential genetic markers for selection. However, these results have to be validated in commercial herds.

Characterization of the porcine FSCN3 gene: cDNA cloning, genomic structure, mapping and polymorphisms

Fascin 3 (FSCN3)is a testis-specific actin-bundling protein involved in spermatid development. Here we describe the molecular characterisation of the porcine FSCN3 gene. The 1,800-bp cDNA sequence contains a 1,497-bp open reading frame encoding a protein of 498 amino acids with a calculated molecular mass of 56.2 kDa and an isoelectric point of 6.82. The porcine FSCN3 protein shares high identity with other mammalian FSCN3. The FSCN3 gene contains seven exons, spans approximately 9 kb, and maps to pig chromosome 18. We also identified 24 DNA polymorphisms.

Effect of the polymorphism of prolactin receptor (PRLR) and leptin (LEP) genes on litter size in Polish pigs

The aim of the experiment was to use the DNA mutations in the PRLR and LEP genes to determine associations between the genotype and litter size in Polish Large White x Landrace sows. Reproductive traits investigated were: total number of piglets born (TNB), number of piglets born alive (NBA) and number of piglets weaned. The polymorphism in PRLR and LEP genes was detected using the polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) method, with specific primers and the restriction enzymes AluI and HinfI respectively. Two different alleles of PRLR and LEP gene were identified: alleles A (0.62) and B (0.38) of the PRLR gene and alleles C (0.10) and T (0.90) of the LEP gene. The relationships between the PRLR and LEP genotypes and TBN, NBA and NW were analysed. The analysis showed, in first parity sows, statistically significant (p < or = 0.01) differences between sows carrying different PRLR genotypes. In later parities, sows with the AA genotype still had the largest litter size compared with AB and BB sows, but the difference was statistically not significant. Analysis of the interaction PARITY x PRLR showed small and statistically not significant differences. The analysis of relationship between different LEP genotypes and TNB, NBA, NW showed small and statistically non-significant differences.

Novos polimorfismos no gene da obesidade em raças divergentes de suínos

Investigou-se a existência de polimorfismo no gene da leptina (gene da obesidade) entre varrões da raça nativa Piau (porco tipo banha) e matrizes mestiças de raças comerciais (Landrace/Large White e Landrace/Large White com Pietrain), selecionadas para peso e precocidade. Oito pares de primers foram desenhados a partir da seqüência disponível no GenBank (U66254), usada, neste trabalho, como seqüência de referência. Amostras de DNA foram extraídas de células sangüíneas brancas utilizando-se solução de fenol:clorofórmio, após tratamento com proteinase K. Os fragmentos gerados por amplificação da reação em cadeia da polimerase foram purificados e seqüenciados em seqüenciador automático. As seqüências de nucleotídeos, obtidas a partir do DNA das raças comerciais de suíno, apresentaram maior similaridade com a seqüência de referência, e as seqüências geradas a partir do DNA dos animais nativos divergiram de ambas em algumas posições. Dos 28 polimorfismos encontrados, oito foram observados em apenas uma das três seqüências geradas a partir do DNA das raças nativas. Doze estavam presentes em duas seqüências, e os oito polimorfismos restantes foram encontrados nos três animais nativos.

Leptin in horses: tissue localization and relationship between peripheral concentrations of leptin and body condition

Obesity has been a major concern in the horse industry for many years, and the recent discovery of leptin and leptin receptors in numerous nonequine species has provided a basis for new approaches to study this problem in equine. The objectives were to: 1) clone a partial sequence ofthe equine leptin and leptin receptor genes so as to enable the design of primers for RT-PCR determination of leptin and leptin receptor gene presence and distribution in tissues, 2) develop a radioimmunoassay to quantify peripheral concentrations of leptin in equine, 3) determine if peripheral concentrations of leptin correlate with body condition scores in equine, and 4) determine if changing body condition scores would influence peripheral concentrations of leptin in equine. In Experiment 1, equine leptin (GenBank accession number AF179275) and the long-form of the equine leptin receptor (GenBank accession number AF139663) genes were partially sequenced. Equine leptin receptor mRNA was detected in liver, lung, testis, ovary, choroid plexus, hypothalamus, and subcutaneous adipose tissues using RT-PCR. In Experiment 2, 71 horses were categorized by gender, age, and body condition score and blood samples were collected. Sera were assayed for leptin using a heterologous leptin radioimmunoassay developed for equine sera. Serum concentrations of leptin increased in horses with body condition score (1 = thin to 9 = fat; r = 0.64; P = 0.0001). Furthermore, serum concentrations of leptin were greater in geldings and stallions than in mares (P = 0.0002), and tended to increase with age of the animal (P = 0.08). In Experiment 3, blood samples, body weights, and body condition scores were collected every 14 d from 18 pony mares assigned to gain or lose weight over a 14-wk interval based on initial body condition score. Although statistical changes (P = 0.001) in body condition scores were achieved, congruent statistical changes in peripheral concentrations of leptin were not observed, likely due to the small range of change that occurred. Nonetheless, serum concentrations of leptin tended to be greater in fat-restricted mares than in thin-supplemented mares (P = 0.09). We conclude that leptin and leptin receptors are present in equine tissues and that peripheral concentrations of leptin reflect a significant influence of fat mass in equine.

cDNA cloning and physical mapping of porcine 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4 isomerase

The 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4-isomerase (3 beta-HSD) enzymes are essential for the biosynthesis of steroid hormones. The 3 beta-HSD gene family has been reported to encode for different isoenzymes which function either as dehydrogenase/isomerase or as reductase. The 3 beta-HSD enzymes are involved in the formation of the pheromone androstenone (5 alpha-androst-16-ene-3-one) which contributes to the unpleasant odour present in the meat of uncastrated boars. An reverse-transcription-polymerase chain reaction (RT-PCR) probe from porcine testicular tissue of a 3 beta-HSD enzyme was used to screen a porcine adipose tissue cDNA library. Both strands of the positive clones were sequenced and the putative coding sequence of 1122 nucleotides encodes 374 amino acids. Comparison of the putative open reading frame with the bovine and the human type I homologues revealed 85.6 and 79.3% identity, respectively. Fluorescence in situ hybridization (FISH) was performed with a labelled PAC clone containing the gene of interest. The 3 beta-HSD gene was mapped to the porcine chromosome 4q16-4q21 which is in accordance with the comparative gene map.

Confirmed quantitative trait loci for fatness and growth on pig chromosome 4

Quantitative trait loci (QTLs) with large effects on fatness and growth have been identified previously on pig chromosome 4 in an intercross between the European wild pig and Large White domestic pigs. Two F2 sows, heterozygous for the actual chromosome region, were backcrossed to a Large White boar, and two backcross (BC1) boars were in turn backcrossed to Large White/Landrace sows. One of the boars was heterozygous for an intact wild pig-derived QTL region, whereas the other carried a recombinant haplotype. A total of 85 BC2 animals were produced. Phenotypical measurements included daily weight gain, ultrasonic measurements of fat depth at 70 and 90 kg and several carcass traits. QTL segregation was deduced using 15 markers previously assigned to chromosome 4. Highly significant QTL effects were observed on all fatness traits and on the length of the carcass. A small but significant effect on growth was also observed. The results confirm the presence of one or more QTLs on chromosome 4 affecting fatness and growth. There was a good agreement between the estimates of QTL effects in the F2 and BC2 generations. The results from the recombinant sire family allowed us to map the major QTL effect distal to the recombination breakpoint. We propose that this confirmed QTL with a major effect on fatness is designated FAT1.

cDNA cloning and tissue-specific gene expression of ovine leptin, NPY-Y1 receptor, and NPY-Y2 receptor

The physiological regulation of food intake is a critical factor in both the rate at which an animal grows and its reproductive activity. Recently, progress has been made in elucidating a complex system in which insulin, leptin, and neuropeptide Y function to monitor an animal's energy balance and regulate feed intake and fertility. RNA was extracted from ovine hypothalamic, anterior pituitary, pancreas, and adipose tissue. Using the reverse transcription-polymerase chain reaction. cDNAs were cloned and sequenced for leptin (350 base pairs [bp], GenBank accession number U62123 and 441 bp, GenBank accession number U84247), NPY-Y1 receptor (350 bp, GenBank accession no. U62122) and NPY-Y2 receptor (440 bp, GenBank accession no. U83458). Probes generated from these clones were used to detect mRNA expression within tissues thought to be involved in the coregulation of feed intake and reproduction. Leptin was found to be expressed in sheep adipose tissue. The ovine NPY-Y1 receptor mRNA was detected within the arcuate nucleus and paraventricular nucleus of the hypothalamus, the dentate gyrus of the hippocampus and in pancreatic, anterior pituitary, and adipose tissues. Expression of ovine NPY-Y2 receptor mRNA was detected in the hippocampus and within pancreatic tissue. These observations provide evidence of potential mechanisms that exist for mediating communication between peripheral and central tissues within the insulin-leptin-NPY pathway.

Leptin receptor mRNA is expressed in ewe anterior pituitary and adipose tissues and is differentially expressed in hypothalamic regions of well-fed and feed-restricted ewes

Infertility associated with suboptimal nutrition is a major concern among livestock producers. Recently, much effort has been put into understanding the role of the protein leptin in regulating feed intake and reproduction. Leptin, produced by adipocytes, has receptors in the hypothalamus, but more precise locations of leptin receptor-expressing cell bodies have not been reported in a livestock species. The leptin receptor transcript has several splice variants in the mouse and human, but only the "long-form" product (OBRL) is capable of signal transduction. A partial ovine long-form leptin receptor cDNA was cloned and used to evaluate OBRL mRNA expression within hypothalamic, anterior pituitary, and adipose tissues of ovariectomized adult ewes. Expression was detected in reverse transcription-polymerase chain reaction products of all tissues examined. OBRL mRNA was detected by in situ hybridization in the ventromedial and arcuate nuclei of the hypothalamus. In ewes that had been feed restricted for 3 wk before tissue collection, the expression of OBRL mRNA in these areas was greater (P < 0.05) than that found in well-fed ewes. These findings provide evidence that the full-length leptin receptor is expressed in hypothalamic, anterior pituitary, and adipose tissue (the latter proffering an autoregulatory mechanisms for leptin) and that within the hypothalamus, this receptor form is differentially expressed in well-fed vs. feed-restricted animals.