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Immunotherapy occupies a growing place in urologic oncology, mainly for kidney and bladder cancers. On the basis of encouraging preclinical work, the combination of immunotherapy with radiotherapy aims to increase the tumor response, including in metastatic tumors, which raises many hopes, which this article reviews., L’immunothérapie occupe une place grandissante en cancérologie urologique, principalement pour les cancers du rein et de la vessie. Sur la base de travaux précliniques encourageants, la combinaison de l’immunothérapie avec la radiothérapie ambitionne de majorer la réponse tumorale, y compris des tumeurs métastatiques ce qui suscite de nombreux espoirs dont cet article fait le bilan.

Background The effectiveness of malaria chemoprophylaxis is limited by the lack of compliance whose determinants are not well known. Methods The compliance with malaria chemoprophylaxis has been estimated and analysed by validated questionnaires administered before and after the short-term missions (about four months) in five tropical African countries of 2,093 French soldiers from 19 military companies involved in a prospective cohort study. "Correct compliance" was defined as "no missed doses" of daily drug intake during the entire mission and was analysed using multiple mixed-effect logistic regression model. Results The averaged prevalence rate of correct compliance was 46.2%, ranging from 9.6%to 76.6% according to the companies. Incorrect compliance was significantly associated with eveningness (p = 0.028), a medical history of clinical malaria (p < 0.001) and a perceived mosquito attractiveness inferior or superior to the others (p < 0.007). Correct compliance was significantly associated with the systematic use of protective measures against mosquito bites (p < 0.001), the type of military operations (combat vs. training activities, p < 0.001) and other individual factors (p < 0.05). Conclusions The identification of circumstances and profiles of persons at higher risk of lack of compliance would pave the way to specifically targeted strategies aimed to improve compliance with malaria chemoprophylaxis and, therefore, its effectiveness.

International audience; An evaluation of the European pig diversity has been carried on by several countries, with the support of the European Union over the period of 1994 to 2000. This article presents an overview of the results of this investigation, focussing on two genetic marker techniques, namely microsatellites (MS) and amplification of fragment length polymorphism (AFLP). Nearly 200 loci were characterised on about 50 individuals from each of 59 to 71 breeds, according to the marker considered. The analysis of diversity, based on genetic distances, led to similar conclusions for the two marker types (MS and AFLP), in spite of a markedly lower total diversity of AFLP compared to MS. The analysis of the MS loci showed that the allelic diversity pattern among breeds was quasi-independent from the diversity pattern based on allele frequencies. Genetic distances showed no particular clustering of local with international breeds, confirming the genetic uniqueness of the European local breeds compared to mainstream international breeds. The taxonomy of the local breeds revealed a cluster of the Iberian type breeds, in contrast with a wider dispersal of the breeds from other countries. Phylogeny often disagreed with documented breeds’ history, showing the complex migration/admixture patterns which underlie the breeds’ relationships. Methodologies developed in this investigation as well as the database and the DNA depository created should provide support for further innovative research in the field of domestic animal diversity management.

Resume Les etudes de la litterature ont porte sur la structure du compte-rendu radiologique, sa normalisation, la communication avec le medecin traitant, les aspects reglementaires et l’importance medico-legale. Les elements retenus comme devant y figurer concernent essentiellement le fond : identification, contexte clinique et questions posees, technique et limites techniques, resultats hierarchises, elements negatifs pertinents, conclusion comportant une reponse a la question, proposant une orientation diagnostique et suggerant d’autres examens, si necessaire. Concernant la forme, l’informatique a fait evoluer le debat opposant le texte libre au compte-rendu structure. Aucune recommandation concernant le « style » n’a ete retrouvee dans les publications recentes. Le probleme n’est pourtant pas nouveau. En 1904, Hickey introduisit le terme « interpretation ». En 1922, il constatait que le style des « rapports » etait toujours individualiste et souvent excentrique. Il proposa de standardiser les comptes-rendus pour « eviter la verbosite et encourager la concision et la clarte ». Apres un rappel des elements devant figurer dans le compte-rendu, nous avons souhaite insister sur la forme et le style de la redaction. Il ne s’agit pas ici d’un travail scientifique, nous exprimons notre opinion a travers l’analyse critique d’exemples releves dans des dossiers de patients. Beaucoup de comptes-rendus comportent de multiples repetitions de mots, de tics de langage qui sont inutiles et nuisent a la credibilite de l’analyse. Les principales qualites du compte-rendu, utiles pour le clinicien, sont la clarte, la concision et la correlation avec la clinique.

In this review, we first analyse the objectives to consider in preserving diversity, fitness and adaptability of farm animal genetic resources (AnGR), given the links between genetic diversity and fitness-adaptedness (FA) traits. Ways to measure diversity are then presented, and tools available for managing genetic diversity within given economic constraints are described, under a theoretical framework proposed by Martin Weitzman. The emphasis is on molecular diversity and the exploitation of genetic marker information for use in conservation management of AnGR, through the use of a diversity function which may be applied either to gene diversity (based on allele frequencies) or to allelic diversity (based on allele counts). The question is raised of the possible relationships between molecular diversity of AnGR and FA traits. Methods for investigating those relationships based on within-breed heterozygosity or between-breed molecular divergence are reviewed. The concepts are illustrated on data from a European study of pig diversity.

Assessing allelic richness in a set of populations requires that variations of sample size be taken into account. One way of doing this is to estimate the number of alleles expected in samples of specified size, using the rarefaction method applied in ecology. An alternative method, based on extrapolation, consists of adding to the number of alleles actually seen in a population the expected number of alleles missing, given the number of genes examined in the population and the allelic frequencies observed over the whole set of populations. Heterogeneity of allelic richness across populations and across loci can also be tested in this framework by numerical re-sampling. Both methods provide a measure of “private” allelic richness, a useful criterion in genetic diversity preservation, by allowing evaluation of the uniqueness of each population in terms of allele numbers. The two methods are compared on isozyme loci in the argan tree of Morocco and on microsatellite genotypes in the European pig. In both species, allelic richness and gene diversity behave quasi-independently over the populations compared and a higher differentiation is observed in allelic richness compared to gene diversity. In general, the rarefaction technique is sensitive to the sample size of reference and may lack sensitivity to rare alleles when the sample size of reference is small. Extrapolation may thus be recommended especially when the sample sizes of the populations are either low on average or highly unbalanced among populations.

Between-breed genetic diversity is classically considered as a major criterion to be taken into account when setting priorities for conservation of domestic animal breeds. However, it has been argued that methods based on the between-breed component of genetic diversity may not be optimal because they ignore the within-breed component of variation. The paper considers the most common methods used to evaluate those two components when genetic diversity is evaluated on the basis of genetic markers, and proposes to define an aggregate diversity combining linearly the two components. This implies defining for each breed (or population) its contributions to the between-breed and to the within-breed diversity. When defining an aggregate diversity, one can weight these contributions by FST and 1−FST, respectively, since the fixation index FST of Wright represents the proportion of the total genetic variation which is due to differences in allelic frequencies between populations. Such an approach is valid when the objective is genetic improvement by selection within a so-called “meta-population”. However, in a more general context of animal breeding, when heterosis and complementarities between breeds have to be considered, as well as adaptation to specific environments, more weight should be given to the between-breed variation. The proper weight to apply may require solutions adapted to each particular situation. In a long-term conservation perspective, priorities should also take into account the degree of endangerment of each breed. By combining diversity contributions and probability of extinction, a cryopreservation potential (or priority) may be estimated for each breed. The problem is illustrated on a sample of 11 European pig breeds typed for 18 microsatellite loci.

Genetic diversity within and between breeds (and lines) of pigs was investigated. The sample comprised 68 European domestic breeds (and lines), including 29 local breeds, 18 varieties of major international breeds, namely Duroc, Hampshire, Landrace, Large White and Pietrain, and 21 commercial lines either purebred or synthetic, to which the Chinese Meishan and a sample of European wild pig were added. On average 46 animals per breed were sampled (range 12–68). The genetic markers were microsatellites (50 loci) and AFLP (amplified fragment length polymorphism, 148 loci). The analysis of diversity showed that the local breeds accounted for 56% of the total European between-breed microsatellite diversity, and slightly less for AFLP, followed by commercial lines and international breeds. Conversely, the group of international breeds contributed most to within-breed diversity, followed by commercial lines and local breeds. Individual breed contributions to the overall European between- and within-breed diversity were estimated. The range in between-breed diversity contributions among the 68 breeds was 0.04–3.94% for microsatellites and 0.24–2.94% for AFLP. The within-breed diversity contributions varied very little for both types of markers, but microsatellite contributions were negatively correlated with the between-breed contributions, so care is needed in balancing the two types of contribution when making conservation decisions. By taking into account the risks of extinction of the 29 local breeds, a cryopreservation potential (priority) was estimated for each of them.

A selection experiment on litter size in the pig was carried on for seventeen generations in an Inra experimental herd. The founder population was made up of 10 males and 120 females from the Large White breed. Selection was first performed for ten generations in a closed line, compared to a control line derived from the same founder population. Selection was carried on within sire family on the total number of piglets born in the first two litters of the dam (TB1 + TB2). After ten generations, the selection criterion became dam TB1 only. The control line was then discontinued and a panel of frozen semen from the 11th generation boars was created for later comparisons. The selected line was opened to gilt daughters of hyperprolific boars and sows, at a rate of 1/8 per generation, and the same selection procedure was applied irrespective of the origin of the gilt. During the whole experiment, the number of ova shed (OS) and the number of live embryos (LE) at 30 days in the 3rd pregnancy were recorded. These two parts of the experiment were analysed using REML estimation of genetic parameters and a BLUP-Animal Model in order to estimate the responses to selection. Significant heritabilities for TB1, TB2, OS and LE were obtained, i.e. 0.10, 0.05, 0.43 and 0.19, respectively. Significant common environment variances and covariances were estimated for nearly all traits. Significantly positive BLUP responses per generation were observed from G0 to G17 for TB1 (+0.086), TB2 (+0.078), OS (+0.197) and LE (+0.157). However, the responses were 3- to 4-fold higher in the G12–G17 interval compared to G0–G11, and they were also in fair agreement with previous estimates based on standard least-squares procedures, using the control line and the control frozen semen panel. Since G11, the selection intensity was increased by nearly 80 p. cent compared to the previous generations, and the proportion of hyperprolific ancestry increased up to 65 p. cent in the sows of the last generation. The total genetic gain of about 1.4 piglets at birth per litter could be shared between a gain due to immigration, of about 0.8 piglets per litter, and a within-line selection gain of about 0.6 piglets. Thus by combining selection and immigration in the second part of the experiment, advantage could be taken from both the genetic superiority of the immigrants and the higher internal selection intensity made possible by immigration.

Using the concept of conditional coancestry, given observed markers, an explicit expression of the accuracy of marker-based selection is derived in situations of linkage equilibrium between markers and quantitative trait loci (QTL), for the general case of full-sib families nested within half-sib families. Such a selection scheme is rather inaccurate for moderate values of family sizes and QTL variance, and the accuracies predicted for linkage disequilibrium can never be reached. The result is used to predict the accuracy of marker-assisted combined selection (MACS) and is shown to agree with previous MACS results obtained by simulation of a best linear unbiased prediction animal model. Low gains in accuracy are generally to be expected compared to standard combined selection. The maximum gain, assuming infinite family size and all QTLs marked, is about 50%.

Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Access; International audience; A linkage map of the porcine genome has been developed by segregation analysis of 239 genetic markers. Eighty-one of these markers correspond to known genes. Linkage groups have been assigned to all 18 autosomes plus the X Chromosome (Chr). As 69 of the markers on the linkage map have also been mapped physically (by others), there is significant integration of linkage and physical map data. Six informative markers failed to show linkage to these maps. As in other species, the genetic map of the heterogametic sex (male) was significantly shorter (∼16.5 Morgans) than the genetic map of the homogametic sex (female) (∼21.5 Morgans). The sex-averaged genetic map of the pig was estimated to be ∼18 Morgans in length. Mapping information for 61 Type I loci (genes) enhances the contribution of the pig gene map to comparative gene mapping. Because the linkage map incorporates both highly polymorphic Type II loci, predominantly microsatellites, and Type I loci, it will be useful both for large experiments to map quantitative trait loci and for the subsequent isolation of trait genes following a comparative and candidate gene approach.

Une expérience de sélection sur la croissance du tissu maigre chez le porc Large White a été réalisée au centre d’insémination artificielle porcine de l’INRA à Rouillé (Vienne) entre 1965 et 1989. Au cours de cette période, 24 générations de verrats ont été sélectionnées sur un indice croissance-gras dorsal, et leurs descendances comparées à l’aide d’un dispositif expérimental de pères répétés. Cet article concerne l’analyse des 2 caractères mesurés sur les 2 987 verrats contrôlés au cours de l’expérience : le gain moyen quotidien (GMQ) de 30 à 80 (ou 85) kg de poids vif, et l’épaisseur moyenne du lard dorsal (LM) mesurée à 80 (ou 85) kg de poids vif. Un modèle mixte individuel univariate a été utilisé. Il inclut des effets de groupe génétique prenant en compte les géniteurs inconnus, c’est-à-dire les parents des pères non contrôlés (fondateurs ou immigrants) et des mères des verrats contrôlés. En fonction du sexe et de l’année de naissance de leurs produits, 35 groupes ont été définis et, après regroupement, les calculs ont été réalisés avec 27 ou 8 groupes au total. Avec le modèle à 27 groupes, les gains génétiques annuels chez les pères, sur la période 1965-1988, sont estimés à 11,4 g de GMQ et -0,15 mm de LM, soit respectivement 1,4 % et 0,9 % de la moyenne. Les gains génétiques annuels chez les mères, sur la période 1959-1987, sont inférieurs d’environ 20 % à ceux des pères pour les 2 variables. Le modèle à 8 groupes donne des gains génétiques plus faibles, notamment pour LM. L’évolution génétiques de L31 est assez régulière sur l’ensemble de l’expérience, alors que celle du GMQ est plus irrégulière, avec une tendance à un plafonnement au cours des 5 dernières années. L’incidence sur les évaluations du nombre de groupes génétiques pris en considération dans le modèle est discutée, en relation avec le degré de connexion statistique du dispositif qui en résulte., A selection experiment on lean tissue growth in Large White pigs was carried on at the INRA artificial insemination center of Rouille (Vienne, France) from 1965 to 1989. Over that period of time, 24 boar generations were selected on a growth-backfat index and their progeny compared using a repeat-sire mating design. The 2 traits measured on the 2 987 boars tested in the experiment are analyzed in this paper, namely average daily gain (ADG) from 30 to 80 (or 85) kg liveweight, and average backfat thickness (ABT) measured at 80 (or 85) kg liveweight. These traits, however, were not included in a repeat-sire design until 1977, and the design was again modified in 1984 by including male progeny from outside untested contemporary boars. The schedule of the experiment is summarized in table I, which gives the number of boars tested, selected, repeated and the number of immigrants for each year. An individual univariate mixed model has been used in the analysis. It includes genetic group effects to deal with unknown ("phantom") parents. As described in the general pedigree of figure 1, these are parents either of untested sires (founders and immigrants) or of the dams of tested boars. On the basis of the sex and year of birth of the parents’ progeny, 35 genetic groups have been defined. They were regrouped in totals of 27 or 8 groups, as shown in table II, for 2 separate analyses. Under the 27-group model, the estimated sire annual genetic gains for the period 1965-1988 are 11.4 g and -0.15 mm for ADG and ABT respectively, equivalent to 1.4 and 0.9 % of the mean. Dam genetic trends, covering the period 1959-1987, are about 20 % below sire trends for both traits. As shown in table III, the 8-group model yields lower sire and dam trends, especially for ABT, but dam trends are below sire trends only for ADG. Phenotypic trends in figure 2 and genetic trends in figures 3 and 4 show similar general patterns. Genetic trend for fatness is consistent over the whole experiment, but genetic change in growth rate is less regular and tends to plateau in the last 5 years. This may be partly due to a lower genetic merit of the immigrants, as shown in table IV. The effect of the number of genetic groups chosen in the model is discussed, in relation to the connectedness of the ensuing design.

Les diarrhées colibacillaires, notamment celles dues à des souches d’E coli entéropathogènes pourvues de l’antigène K88, sont une cause majeure de mortalité chez le porcelet nouveau-né. L’existence d’une résistance génétique, liée à plusieurs marqueurs biochimiques, dont les bases sont brièvement rappelées ici, permet d’envisager de réduire par sélection l’incidence économique de la maladie. Cet article présente les conditions dans lesquelles une telle sélection pourrait s’intégrer dans les schémas courants d’amélioration génétique du porc. La plupart des populations porcines manifestent un polymorphisme pour les gènes de résistance à la colibacillose K88. Dans une population exposée à cette maladie, la mortalité du porcelet dépend de la fréquence p du gène de résistance et de 2 taux de mortalité m1 et m2 s’appliquant respectivement aux porcelets sensibles issus de mères sensibles, qui bénéficient d’une certaine protection colostrale, et aux porcelets sensibles issus de mères résistantes, qui ne bénéficient pas de cette protection. De ce fait on a généralement m1 < m2, et on montre que, au sein d’une population, le risque global de mortalité peut, dans certaines conditions, être une fonction croissante de la fréquence du gène de résistance. Dans un système de croisement, le choix d’un génotype approprié pour les verrats utilisés à chaque niveau permet de minimiser la mortalité du porcelet terminal. Ainsi l’utilisation d’un verrat terminal résistant offre l’avantage de la plus faible mortalité dans sa descendance, quelle que soit la fréquence p chez les mères, et cette mortalité diminue à mesure que p augmente. On note, au contraire, que si le verrat terminal est homozygote sensible, la mortalité augmente avec p. Dans un système de croisement triple, par exemple, l’utilisation d’un grand-père maternel homozygote sensible devrait alors être recommandée. Il faut aussi prendre en compte les effets de la sélection naturelle, par la mortalité, et de la sélection (artificielle) sur l’âge à 100 kg, qui peuvent, dans certaines situations, défavoriser le gène de résistance. On montre cependant que la fréquence p = 0,5 est un seuil critique, au-dessus duquel ce risque est totalement écarté. L’existence de 3 variants sérologiques de l’adhésine K88 et de 3 récepteurs intestinaux correspondants apporte une complexité supplémentaire, et peut induire des interactions entre plusieurs locus de résistance. En tout état de cause, un important travail d’identification des génotypes est nécessaire, au moins dans les lignées paternelles. Des recherches restent à poursuivre pour parvenir à un marquage génétique suffisamment étroit des gènes de résistance ou à leur identification biochimique., Use of genetic resistance to K88 colibacillosis in pig breeding schemes. Neonatal colibacilloses, and particularly those due to strains of E coli bearing the K88 antigen, are a major cause of piglet mortality. The existence of a genetic resistance, linked to several biochemical markers, which is briefly presented here, offers the possibility of reducing the economic impact of the disease through selection. This paper discusses the conditions under which such a selection could be implemented within current pig breeding schemes. Most pig populations are polymorphic with regard to the gene(s) for resistance to K88 colibacillosis. The adhesion phenotypes for the 3 possible variants, K88ab, K88ac, and K88ad, are given in table I, and their observed frequencies in 5 reports from the literature are given in table II. Within a population exposed to the disease, piglet mortality depends on the frequency p of the resistance gene and on 2 mortalities m1 and m2, respectively applying to susceptible pigs from susceptible dams, which benefit from colostral protection, and to susceptible pigs from resistant dams, which lack this protection. From table III, which gives the expected mortality for the different combinations of sire and dam genotype, the global risk of mortality may be derived in a population in Hardy-Weinberg equilibrium and expressed as a function of p. As shown in figure 1, in which mortality is plotted against p for various values of m1 and m2, the risk of mortality may increase with p, under some conditions. In a crossbreeding scheme, the choice of an appropriate boar genotype at each level allows minimizing mortality among terminal piglets. The use of a resistant terminal sire, for instance, minimizes mortality in the progeny, whichever the frequency p in the dam line(s), and mortality decreases with increasing p. However, as shown in figure 2, where mortality is plotted against gene frequency in the dam line for each sire genotype, if the terminal sire is homozygous susceptible, mortality in the progeny increases with p. In a 3-way cross, the use of a homozygous susceptible maternal grand-sire should then be recommended, as shown in table IV, which gives the expected mortality for each combination of sire and maternal grand-sire genotype. In addition, natural selection, through piglet mortality, and (artificial) selection for age at 100 kg are also to be considered, as they may, in some situations, act against the resistance gene. However, it can be shown that the gene frequency value p = 0.5 is a critical threshold, above which such a risk is totally avoided. This is shown graphically for natural selection in figure 3, which gives the gene frequency change due to mortality as a function of the gene frequency in the population. The existence of 3 serological variants of the K88 adhesin and of 3 corresponding intestinal receptors introduces additional complexities and it may induce interactions between several receptor loci. In any case, a large amount of work for identifying genotypes is necessary, at least in sire lines. Investigations should be pursued in order to reach a sufficintly precise marking of the resistance genes or to identify them biochemically.

Les résultats recueillis entre 1966 et 1975 dans une expérience de sélection sur un indice à 2 caractères, au centre d’insémination artificielle porcine I.N.R.A. de Rouillé (Vienne), ont été analysés en vue d’estimer des paramètres génétiques réalisés concernant les 2 variables de l’indice de sélection - vitesse de croissance de 30 à 80 kg (X,) et épaisseur du gras à 80 kg (Xa) - et un ensemble de 14 variables (Y) différentes, pour lesquelles les réponses à la sélection avaient été précédemment estimées. A cette occasion, la méthode classique d’estimation des paramètres génétiques réalisés a été étendue au cas des populations avec recouvrement des générations successives. Connaissant la structure du réseau de migration des gènes entre les diverses cohortes de géniteurs, on peut prédire, pour chaque cohorte au temps t, la proportion de ses gènes provenant d’un groupe d’individus sélectionné au temps t-1, t-2, etc... Dans le cas d’une sélection sur un caractère, une différentielle de sélection cumulée par cohorte peut ainsi être calculée pour chaque valeur de t. Dans le cas d’une sélection sur un indice à plusieurs caractères, les coefficients des variables de l’indice de sélection « rétrospectif » peuvent être calculés pour chaque cycle de sélection et cumulés dans le temps, par cohorte, selon le même principe. Les covariances réalisées entre les variables de l’indice (ici X1 et X3) et la valeur génétique d’un caractère quelconque (Y) sont alors obtenues par la régression multiple de la réponse du caractère en fonction des coefficients d’indice ainsi cumulés. Les résultats montrent que, dans notre expérience, ces paramètres ne peuvent pas être estimés avec précision par suite du dispositif expérimental utilisé. Par contre, les corrélations réalisées entre l’indice de sélection et les valeurs génétiques des Y sont estimées avec une précision satisfaisante, puisqu’on se place alors dans la situation d’une sélection sur un seul caractère qui est l’indice. Les estimations globales, combinant les estimations des cohortes paternelles et maternelles, sont comparées aux valeurs attendues, calculées à partir des paramètres génétiques dérivés des covariances entre apparentés. Si l’accord est satisfaisant pour la vitesse de croissance, les corrélations réalisées sont inférieures aux valeurs attendues pour la plupart des variables de carcasse. Il faut noter cependant que les corrélations réalisées sur les cohortes maternelles sont en général inférieures à celles des cohortes paternelles. Cette différence incline à mettre en doute le modèle de migration-sélection postulé, en particulier l’hypothèse que la population étudiée est fermée à l’immigration. En fait, l’absence d’information précise sur l’importance de l’immigration ne permet pas une comparaison rigoureuse des paramètres génétiques réalisés de cet article aux paramètres génétiques estimés dans l’article précédent. Les conclusions générales de l’expérience, qui a donné lieu à 3 articles, sont présentées., Realized genetic parameters are derived from the results of a selection experiment carried on at a pig artificial insemination centre belonging to I.N.R.A. (located at Rouillé, Vienne, France). The characters considered are the 2 traits of the selection index used, namely average daily gain from 30 to 80 kg liveweight (X1) and backfat thickness at 80 kg liveweight (X3) and a set of 14 Y variables, including various growth and carcass traits, for which the responses to selection had previously been estimated. The method of analysis is an extension of the classical method of estimation of realized genetic parameters to the case of populations with overlapping generations Knowing the pattern of gene migrations through the various age-sex cohorts of breeding animals, one can, for each group at time t, predict the proportion of genes coming from any cohort selected at any earlier time. When selection is on one trait, a cumulative selection differential can thus be calculated for each cohort at each time t. When selection is on an index including several traits, the coefficients of the index « in retrospect may be calculated for each cycle of selection and cumulated over time in each cohort by the same method as for one-trait selection. The realized covariances between the index traits (here X1 and X3) and the breeding value for any Y variable are then obtained as the multiple regression of the response of Y on the index coefficients cumulated as indicated above. The results show that the design of the selection experiment analysed is inadequate to allow precise estimation of those parameters. However, the realized correlations between the selection index and the Y breeding values can be estimated rather precisely, by using single trait methodology and considering the index as this trait. The combined estimates, obtained by pooling the sire and dam cohorts estimates, are compared to the values derived from covariances between relatives. The agreement is satisfactory for growth rate, but the realized correlations are below their expectation for most carcass traits. However, as dam cohorts estimates are generally lower than sire cohorts estimates, the migration-selection model which is postulated in the analysis may be questioned, and particularly the assumption of a closed population. The lack of information on the amount of immigration into the sow population under insemination prevents any strict comparison betweeen the realized genetic parameters of this article and the genetic parameters estimated in the previous one. General conclusions from the 3-part analysis of this pig selection experiment are presented.

National audience

National audience; Very early, the origin of the Belgian pig of Piétrain has been a matter of speculations. Several Belgian authors have put forward a hypothesis according to which the Piétrain breeders would have detected and selected for a mutation. Indeed, the exceptional muscle development of the breed cannot easily be explained by selection for a quantitative polygenic trait. A crossbreeding experiment was conducted in France, some fifteen years ago, in order to test the above hypothesis. In that experiment, muscle hypertrophy was assessed in two different ways, namely by a visual score for conformation at weaning (20 kg liveweight) and by a combination of several carcass measurements at 100 kg liveweight. In both cases the results strongly suggested the existence of a major gene responsible for muscle hypertrophy in the Piétrain pig. Later on the evidence found for a monogenic determination of the halothane-induced malignant hyperthermia syndrome (MHS) and the narrow links between MHS and muscularity naturally led to postulate that a single pleiotropie gene might be responsible for both phenomena. Thus, halothane inhalation may be considered as a specific test for the " Piétrain entity " previously defined. The relationships found between the MHS gene and three different biochemical polymorphisms loci allow to locate the gene, rather precisely, within " chromosome map " about 6 centimorgans long. The incidence of MHS on meat quality has been very intensively investigated in the recent years and the underlying biological mechanism might be a defect of the mitochondrial membrane affecting the Ca++ transport system in the muscle. However, the biological mechanism leading to muscular hypertrophy itself still remains unexplained.; L’apparition du porc belge de Piétrain a suscité très tôt des spéculations quant à son origine Une hypothèse fréquemment avancée par les auteurs belges était que les éleveurs de Piétrain avaient détecté et sélectionné une mutation, car le développement musculaire exceptionnel de cette race pouvait difficilement s’expliquer par une sélection sur un caractère à déterminisme polygénique. Une expérience de croisement réalisée en France il y a une quinzaine d’années suggérait aussi l’existence d’un gène « majeur » responsable de l’hypertrophie musculaire du porc de Piétrain, telle qu’elle peut être jugée d’une part sur l’animal vivant par appréciation visuelle et d’autre part sur la carcasse soumise à une découpe. Enfin, la mise en évidence dans cette même race d’un gène responsable du syndrome d’hyperthermie maligne déclenché par l’inhalation d’halothane et la liaison étroite entre cette sensibilité à l’halothane et le développement musculaire ont conduit naturellement à postuler que le même gène, par une action pléiotropique, est responsable des deux phénomènes. L’inhalation d’halothane peut donc être considérée comme un test spécifique de l’ «entité» Piétrain telle qu’eile avait été précédemment définie. Les relations entre ce gène et des polymorphismes biochimiques à trois locus voisins ont permis de dresser un début de « carte chromosomique » sur une longueur d’environ 6 centimorgans. Les répercussions de ce phénomène sur la qualité de la viande ont fait l’objet de recherches nombreuses et le mécanisme biologique sous-jacent serait un défaut de la membrane mitochondriale affectant les mouvements de l’ion Calcium. Par contre, le mécanisme biologique induisant l’hypertrophie musculaire reste encore inexpliqué.

International audience

"Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Access "; National audience

A comparative trial was performed on 15 Large White and 12 Chinese germ-free, colostrumdeprived piglets, maintained in plastic film isolators. Shortly after successive oral inoculations of 2 E. coli strains, one K88-positive and one K88-negative, the piglets were sacrificed and bacterial numerations of the 2 strains were done on 3 different intestinal segments of each pig, using both the lumen content and the washed intestinal wall. The percentage of bacteria specifically bound to the intestinal wall was estimated, and the presence or absence of the piglet K88 intestinal receptor was thus inferred. The results tended to indicate that the 12 Chinese piglets lacked this receptor, as against 7 Large White’s. This raises the question of possible breed differences in resistance to this type of colibacillosis., Un essai comparatif a été réalisé sur 15 porcelets Large White et 12 porcelets Chinois, prélevés à la naissance de manière axénique, privés de colostrum et placés en isolateur sous film plastique. Après inoculation par voie orale de 2 souches de E. coli, l’une possédant l’antigène d’attachement K88 (K88+)l’autre dépourvue de cet antigène (K88-), les porcelets sont sacrifiés et 3 segments différents de l’intestin grêle sont prélevés sur chaque porcelet en vue de numérations des 2 souches bactériennes, à la fois dans le contenu intestinal et sur la paroi. Le pourcentage de bactéries spécifiquement attachées à la paroi est ainsi estimé et la présence ou l’absence chez le porcelet du récepteur intestinal K88 peut en être déduite. Les résultats indiquent que les 12 porcelets Chinois ne possèdent pas ce récepteur et doivent donc être résistants à l’attachement de K88, contre 7 porcelets Large White. Cela soulève la question de l’existence possible de races résistantes à cette colibacillose.

National audience

National audience