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Biomedical subjects

J M Elsen

Publications and source records attributed to J M Elsen.

At least 19 recordsLinked to original sources
PubMed2006

No associations between PrP genotypes and reproduction traits in INRA 401 sheep.

In this study, the potential association of PrP genotypes with ewe reproductive traits and lamb growth traits was investigated. Data were included on ewes and lambs of the INRA 401 breed from the Bourges-La Sapinière INRA experimental farm. This breed was chosen because of good breeding (prolificacy and maternal abilities) and carcass qualities, and the large number of available animals with performance records and PrP genotypes. Ewes were categorized into 3 PrP genotype classes: ARR homozygous, ARR heterozygous, and animals without any ARR haplotype. Two analyses differing in the traits considered were carried out. Firstly, the potential association of the PrP genotype of ewes with their reproduction traits (fertility, litter size, and ovulation rate) was studied. The data included 801, 779, and 587 genotyped ewes for fertility, litter size, and ovulation rate, respectively. Secondly, the association of the PrP genotype of the ewes with growth traits of their lambs (birth weight, ADG between 10 and 30 d of age) was investigated. The data included 3,749 and 3,512 lambs for birth weight and ADG, respectively. The different traits were analyzed using an animal model, where the PrP genotype effect was included as a fixed effect. The reproductive traits were modeled under a probit or a threshold approach. The results of this study indicate no evidence of an association between PrP genotypes and reproductive and growth traits. It is unlikely that selection for scrapie resistance will have an effect on the reproductive or performance traits studied in the INRA 401 breed.

Animals↗
PubMed2005

Interval mapping methods for detecting QTL affecting survival and time-to-event phenotypes.

Quantitative trait loci (QTL) are usually searched for using classical interval mapping methods which assume that the trait of interest follows a normal distribution. However, these methods cannot take into account features of most survival data such as a non-normal distribution and the presence of censored data. We propose two new QTL detection approaches which allow the consideration of censored data. One interval mapping method uses a Weibull model (W), which is popular in parametrical modelling of survival traits, and the other uses a Cox model (C), which avoids making any assumption on the trait distribution. Data were simulated following the structure of a published experiment. Using simulated data, we compare W, C and a classical interval mapping method using a Gaussian model on uncensored data (G) or on all data (G'=censored data analysed as though records were uncensored). An adequate mathematical transformation was used for all parametric methods (G, G' and W). When data were not censored, the four methods gave similar results. However, when some data were censored, the power of QTL detection and accuracy of QTL location and of estimation of QTL effects for G decreased considerably with censoring, particularly when censoring was at a fixed date. This decrease with censoring was observed also with G', but it was less severe. Censoring had a negligible effect on results obtained with the W and C methods.

Animals↗
PubMed2004

Effects of a quantitative trait locus for muscle hypertrophy from Belgian Texel sheep on carcass conformation and muscularity.

A QTL for muscle hypertrophy has been identified in the Belgian Texel breed. A population of F2 and backcross lambs created from crosses of Belgian Texel rams with Romanov ewes was studied. Effects on carcass traits and muscle development of the Belgian Texel breed polygenes and Belgian Texel single QTL were compared. In both cases, carcass conformation and muscularity were improved. The Texel polygenic environment improved conformation mainly through changes in skeletal frame shape. Segments were shorter and bone weight lower. Muscles were more compact, shorter, and thicker. The single QTL affected muscle development. Thickness and weight of muscles were increased. Composition in myosin changed toward an increase of fast contractile type. The relative contribution of hind limb joint to carcass weight was increased. Differences in skeletal frame morphology among the three genotypes of the single QTL were small. Conformation scoring was mainly influenced by leg muscularity. Back and shoulder muscle development, which largely contributed to variability of muscularity, were less involved in the conformation scoring. Lastly, the QTL explains a small part of differences between these Belgian Texel and Romanov breeds for conformation or muscle development. A large part of genetic variability remains to be explored.

Animals↗
PubMed2003

Effect of two candidate genes on the Salmonella carrier state in fowl.

Selection for increased resistance to Salmonella carrier-state (defined as the persistency of the bacteria 4 wk after inoculation) could reduce the risk for the consumer of food toxi-infections. The effects of two genomic regions on chromosomes 7 and 17 harboring two genes, NRAMP1 (SLC11A1) and TLR4, known to be involved in the level of chicken infection 3 d after inoculation by Salmonella were thus tested on a total of 331 hens orally inoculated at the peak of lay with 10(9) bacteria. The animals and their parents were genotyped for a total of 10 microsatellite markers mapped on chromosomes 7 and 17. Using maximum likelihood analysis and interval mapping, it was found that the SLC11A1 region was significantly involved in the control of the probability of spleen contamination 4 wk after inoculation. Single nucleotide polymorphisms (SNP) within the SLC11A1 and TLR4 gene were tested on those animals as well as on a second batch of 279 hens whose resistance was assessed in the same conditions. As the former was significantly associated with the risk of spleen contamination and the number of contaminated organs, SLC11A1 appears to be involved in the control of resistance to Salmonella carrier state. The involvement of the TLR4 gene was also highly suspected as a significant association between SNP within the gene, and the number of contaminated organs was detected.

Animals↗
PubMed2003

Prolificacy genes in sheep: the French genetic programmes.

It has been demonstrated that variations in litter size or ovulation rate in different breeds of sheep can be associated with the segregation of several major genes. This set of natural mutants constitutes a valuable resource to determine key points in the biochemical pathways controlling the development of ovarian follicles. The French genetic programmes were devised to identify two of these genes: the Booroola (FecB) and Lacaune genes. The FecB prolific mutation corresponds to a non-conservative mutation (Q249R) in the intracellular kinase-signalling domain of the bone morphogenetic protein receptor type IB (BMPR-IB) gene. The Lacaune gene is situated on ovine chromosome 11. Positional cloning is currently in progress to identify the relevant gene and mutation. A similar approach, limited to linkage testing of candidate genes, is proposed to classify the different prolificacy genes in sheep.

Animals↗
PubMed2002

Discriminant value of blood and urinary corticoids for the diagnosis of scrapie in live sheep.

The mean (sd) concentration of plasma 20beta-dihydrocortisol in 126 scrapie-affected sheep was 5-5 (7.0) ng/ml compared with 1.1 (0.7) ng/ml in 52 healthy sheep. The mean (sd) concentration of creatinine in the urine of 93 scrapie-affected sheep was 2.43 (1.56) microg/ml compared with 0.94 (0.86) pg/ml in 49 healthy sheep and 1.10 (0-95) pg/ml in 25 sheep with other diseases. These discriminant analyses carried out on healthy and scrapie-affected sheep showed that plasma 20beta-dihydrocortisol and urinary creatinine were the best predictors of the disease, and classified correctly 98 per cent of healthy sheep and 82 per cent of scrapie-affected sheep.

Animals↗
PubMed2001

Mutation in bone morphogenetic protein receptor-IB is associated with increased ovulation rate in Booroola Mérino ewes.

Ewes from the Booroola strain of Australian Mérino sheep are characterized by high ovulation rate and litter size. This phenotype is due to the action of the FecB(B) allele of a major gene named FecB, as determined by statistical analysis of phenotypic data. By genetic analysis of 31 informative half-sib families from heterozygous sires, we showed that the FecB locus is situated in the region of ovine chromosome 6 corresponding to the human chromosome 4q22-23 that contains the bone morphogenetic protein receptor IB (BMPR-IB) gene encoding a member of the transforming growth factor-beta (TGF-beta) receptor family. A nonconservative substitution (Q249R) in the BMPR-IB coding sequence was found to be associated fully with the hyperprolificacy phenotype of Booroola ewes. In vitro, ovarian granulosa cells from FecB(B)/FecB(B) ewes were less responsive than granulosa cells from FecB(+)/FecB(+) ewes to the inhibitory effect on steroidogenesis of GDF-5 and BMP-4, natural ligands of BMPR-IB. It is suggested that in FecB(B)/FecB(B) ewes, BMPR-IB would be inactivated partially, leading to an advanced differentiation of granulosa cells and an advanced maturation of ovulatory follicles.

Amino Acid Sequence↗
PubMed2001

A centuries-long epidemic of scrapie in British sheep?

The apparent persistence of scrapie in British sheep for more than 250 years is difficult to explain. Susceptibility to scrapie is associated with particular alleles at a single locus, the PrP gene. As the only known effect of these alleles is to confer susceptibility to a fatal disease, natural selection is expected to reduce their frequency, as has been observed in practice during scrapie outbreaks in single sheep flocks. Susceptibility alleles, and hence scrapie itself, are therefore expected to become rare, yet the disease remains widespread. We suggest that the paradox of scrapie's persistence can be explained by the exceptionally long time-scales inherent in the epidemiology of the disease. It is proposed that scrapie should be regarded as epidemic in British sheep but, unlike more familiar epidemics, which have time-scales of months or years, the scrapie epidemic has a time-scale of centuries. This interpretation implies that scrapie should eventually disappear from the sheep population.

Animals↗
PubMed2001

Statistical power of QTL mapping methods applied to bacteria counts.

Most QTL mapping methods assume that phenotypes follow a normal distribution, but many phenotypes of interest are not normally distributed, e.g. bacteria counts (or colony-forming units, CFU). Such data are extremely skewed to the right and can present a high amount of zero values, which are ties from a statistical point of view. Our objective is therefore to assess the efficiency of four QTL mapping methods applied to bacteria counts: (1) least-squares (LS) analysis, (2) maximum-likelihood (ML) analysis, (3) non-parametric (NP) mapping and (4) nested ANOVA (AN). A transformation based on quantiles is used to mimic observed distributions of bacteria counts. Single positions (1 marker, 1 QTL) as well as chromosome scans (11 markers, 1 QTL) are simulated. When compared with the analysis of a normally distributed phenotype, the analysis of raw bacteria counts leads to a strong decrease in power for parametric methods, but no decrease is observed for NP. However, when a mathematical transformation (MT) is applied to bacteria counts prior to analysis, parametric methods have the same power as NP. Furthermore, parametric methods, when coupled with MT, outperform NP when bacteria counts have a very high proportion of zeros (70.8%). Our results show that the loss of power is mainly explained by the asymmetry of the phenotypic distribution, for parametric methods, and by the existence of ties, for the non-parametric method. Therefore, mapping of QTL for bacterial diseases, as well as for other diseases assessed by a counting process, should focus on the occurrence of ties in phenotypes before choosing the appropriate QTL mapping method.

Algorithms↗
PubMed2000

Genetic variability in milking speed of dairy goats.

The present investigation deals with the genetic variability of milking speed, measured as the volume of milk collected during the first minute of milking (MD1), and its association with dairy traits. Data originated from 2589 lactations of 1421 Alpine goats, sired by 93 bucks, measured between 1985 and 1997 at the Moissac Goat Experimental Station (Lozère, France). Two genetic analyses were carried out. Firstly, a polygenic model was used to estimate genetic and phenotypic parameters among milking speed and dairy traits using a multiple-trait animal model. Secondly, segregation analysis was used to test the hypothesis of mixed model inheritance (polygenes + major gene) for MF1. Heritability and repeatability of MF1 under the polygenic model were high (0.65 and 0.82, respectively). Estimated genetic and phenotypic correlations between milking speed and dairy traits were low, positive for yields and negative for contents. Segregation analysis yielded a highly significant likelihood ratio, confirming the segregation of a major gene with two alleles with partial dominance. The difference between the mean values of the two homozygotes was around 2.3 phenotypic standard deviation units of the trait. The major gene explained more than 60% of the estimated total genetic variance. The estimate of the 'residual' heritability, after taking into account the effect of the major locus, was 0.30.

Animals↗
PubMed2000

Consequences of the presence of the Booroola F gene on the intraovarian insulin-like growth factor system and terminal follicular maturation in Mérinos d'Arles ewes.

In sheep, the presence of the Booroola F gene has several important consequences for ovarian function. This study investigated the consequences of the presence of the F gene for the insulin-like growth factor (IGF) system in the ewe ovary. Studies were undertaken in ovaries from F+ and ++ Mérinos d'Arles ewes to determine 1) the levels of type I IGF receptors and IGF binding proteins (IGFBPs) in follicular cells by quantitative autoradiography of [(125)]-IGF-I binding sites on ovarian sections; 2) the pattern of intrafollicular IGFBPs, by Western-ligand blotting on follicular fluids; and 3) the effects of IGF-I and FSH on proliferation and differentiation of granulosa cells in vitro, assessed by progesterone secretion and cytochrome P450 side-chain cleavage (P450(scc)) expression. The amounts of type I IGF receptors were similar in F+ and ++ follicular cells; however, at the same follicular size, F+ healthy follicles contained lower concentrations of IGFBPs smaller than 40 kDa (particularly IGFBP-2) than ++ healthy follicles. In vitro, in basal conditions as well as in IGF-I- or FSH-stimulated conditions (or both), granulosa cells from F+ follicles had a lower proliferative activity, secreted higher amounts of progesterone, and expressed higher levels of P450(scc) than granulosa cells from ++ follicles of the same size. When F+ and ++ preovulatory follicles were compared at the end of the follicular phase, IGFBPs <40 kDa concentrations were slightly higher, and responsiveness of granulosa cells to FSH in vitro was lower in F+ than in ++ follicles, suggesting that terminal maturation of F+ follicles, although precocious, was less complete than it was in ++ follicles. The early decrease in intrafollicular IGFBPs <40 kDa concentrations observed in F+ antral follicles, which likely leads to an early increase in IGF bioavailability, may at least partly account for the increased ovulation rate that characterizes F-carrier ewes.

Animals↗
PubMed1999

Genetic susceptibility and transmission factors in scrapie: detailed analysis of an epidemic in a closed flock of Romanov.

Information from a scrapie epidemic in a closed INRA Romanov flock is presented. Performances, pedigree, histopathological diagnoses and PrP genotypes were recorded from the beginning of the outbreak (in 1993). Between 1st of April, 1993 and 1st of May, 1997, 1015 animals were exposed to scrapie, and 304 died from this disease. A major influence of the polymorphisms at codons 136, 154 and 171 is shown, A136H154Q171 allele carriers proving to be nearly as resistant as A136R154R171 carriers. A possible relationship between gastrointestinal parasitism and scrapie is discussed. There is evidence of maternal transmission, with a risk ratio for artificially fed lambs of 67 percent of the risk of lambs fed by their mother. Our results strongly suggest that resistant animals were not healthy carriers or at least were less infectious when comparing risk for lambs born to healthy dams either of resistant (risk = 0.431) or of susceptible (risk = 1.000) genotype.

Animals↗
PubMed1999

Influence of the three RN genotypes on chemical composition, enzyme activities, and myofiber characteristics of porcine skeletal muscle.

An experiment was conducted to evaluate the effects of the RN genotype on skeletal muscle characteristics in pigs sharing otherwise the same polygenic background. Animals were genotyped for RN on the basis of RTN (Rendement Technologique Napole) records using segregation analysis methods. Samples of longissimus (L) and semispinalis capitis (S) muscles were taken from 39 rn+/rn+, 38 RN-/rn+ and 37 RN-/RN- pigs slaughtered at 108 +/- 8.6 kg live weight. Activities of lactate dehydrogenase (LDH), citrate synthase (CS), and beta-hydroxy-acyl-coenzyme A dehydrogenase (HAD) were measured on both muscles to assess glycolytic, oxidative, and lipid beta-oxidation capacities, respectively. Histological examinations and chemical analyses were performed on L muscle. The energetic metabolism of the white L muscle was more oxidative in RN-/RN- than in rn+/rn+ pigs, as shown by increased CS and HAD activities (P < .001), decreased LDH activity (P < .001), larger cross-sectional area of IIA (P < .05) and IIB-red (P < .05) fibers, higher relative area of IIA fibers ( P < .05), and lower relative area of IIB-white fibers (P < .001). No significant difference was found between heterozygous and homozygous carriers of the RN- allele, except for CS activity, which was lower in RN-/rn+ than in RN-/RN- pigs. In L muscle, the RN- allele led to a large increase in glycolytic potential (+3.5 phenotypic SD between homozygotes) and lightness (+.7 SD), and a decrease in ultimate pH, dry matter, and protein contents (-1.7 to -2 phenotypic SD for these three traits), with an almost completely dominant effect. No differences were found between genotypes for intramuscular fat and hydroxyproline contents. In the red S muscle, the presence of RN- had no influence on enzyme activities. These results indicate that the RN genotype greatly influences compositional and histochemical traits and metabolic enzyme activities in a muscle type-dependent manner, with a completely or incompletely dominant effect of the RN- allele.

Alleles↗
PubMed1998

cDNA cloning, structural organization, and expression of the sheep NRAMP1 gene.

Mouse resistance to several intracellular pathogens including Mycobacteria, Leishmania, and Salmonella is under the control of the Chromosome (Chr) 1 Natural Resistance Associated Macrophage Protein I gene (Nramp1). This gene could have an economic and health importance for domestic animals and humans as well. Therefore, equivalents of the NRAMP1 gene have been cloned by several research groups in various animal species. To study in sheep the influence of the NRAMP1 gene on the susceptibility to intracellular pathogens induced diseases, we have cloned the sheep NRAMP1 cDNA by screening a splenic cDNA library. The genomic organization of the sheep NRAMP1 gene was then determined by sequencing the exon/intron boundaries. The transcription start points (tsp) from the NRAMP1 mRNA have been located with primer extension experiments. RT-PCR reactions have been used to determine the profile of mRNA expression of this gene.

Amino Acid Sequence↗
PubMed1996

Accurate mapping of the "acid meat" RN gene on genetic and physical maps of pig chromosome 15.

It has been shown that a major gene, called RN, is responsible for the RTN technological yield, a meat quality porcine trait. Experimental families informative for the segregation of RN gene were constituted from animals belonging to the Laconie composite line. We have previously mapped the RN gene to Chromosome (Chr) 15 (Milan et al. Genet. Sel. Evol. 27, 195-199, 1995). A Chr 15 map was established with 16 markers. The RN gene was found to be located between markers Sw120 and Sw936, at 2 cM from Sw936 (LOD = 38.1). In addition, by localizing Sw936 at 15q21-22 using DISC-PCR, we also located RN on the physical map.

Animals↗
PubMed1996

Genetic mapping of the autosomal region involved in XX sex-reversal and horn development in goats.

Contrary to other genetic disorders, the genetic study of sex determination anomalies in humans stumbles over the difficulty in observing large pedigrees. In goats, abnormalities in sex determination are intimately linked to a dominant Mendelian gene coding for the "polled" (hornless) character, which could render this species an interesting animal model for the rare human cases of SRY-negative XX males. In this report, we describe genetic linkage between the polled/intersex synchome (PIS) and four microsatellite markers of the distal region of goat Chromosome 1 (CHI1), quite distinct from the bovine "polled" region. According to comparative mapping data, no sex-determining gene has been described so far in homologous regions in the human. This genetic localization constitutes a first step towards identifying a new autosomal sex-determining gene in mammals.

Animals↗