Pathogen exposure influences immune parameters around weaning in pigs reared in commercial farms.

BACKGROUND: Multiple antigenic stimulations are crucial to immune system training during early post-natal life. These stimulations can be either due to commensals, which accounts for the acquisition and maintenance of tolerance, or to pathogens, which triggers immunity. In pig, only few works previously explored the influence of natural exposition to pathogens upon immune competence. We propose herein the results of a multicentric, field study, conducted on 265 piglets exposed to contrasted pathogen levels in their living environment. Piglets were housed in 15 different commercial farms, sorted in two groups, low (HSLOW)- and high (HSHIGH)-health status farms, depending on their recurrent exposition to five common swine pathogens. RESULTS: Using animal-based measures, we compared the immune competence and growth performances of HSLOW and HSHIGH pigs around weaning. As expected, we observed a rise in the number of circulating leucocytes with age, which affected different cell populations. Monocyte, antigen-experienced and cytotoxic lymphocyte subpopulation counts were higher in piglets reared in HSLOW farms as compared to their HSHIGH homologs. Also, the age-dependent evolution in γδ T cell and neutrophil counts was significantly affected by the health status. With age, circulating IFNα level decreased and IgM level increased while being greater in HSLOW piglets at any time. After weaning, LPS-stimulated blood cells derived from HSLOW piglets were more prone to secrete IL-8 than those derived from HSHIGH pigs did. Monocytes and granulocytes issued from HSLOW pigs also exhibited comparable phagocytosis capacity. Altogether our data emphasize the more robust immunophenotype of HSLOW piglets. Finally, piglets raised under higher pathogen pressure grew less than HSHIGH piglets did and exhibited a different metabolic profile. The higher cost of the immune responses associated with the low farm health status may account for lower HSLOW piglet performances. CONCLUSIONS: Altogether, our data, obtained in field conditions, provide evidence that early exposure to pathogens shapes the immune competence of piglets. They also document the negative impact of an overstimulation of the immune system on piglets' growth.

Impact of Genetic Variation on Stress-Related Ethanol Consumption.

BACKGROUND: The effect of stress on alcohol consumption in humans is highly variable, and the underlying processes are not yet understood. Attempts to model a positive relationship between stress and increased ethanol (EtOH) consumption in animals have been only modestly successful. Our hypothesis is that individual differences in stress effects on EtOH consumption are mediated by genetics. METHODS: We measured alcohol consumption, using the drinking-in-the-dark (DID) paradigm in females from 2 inbred mouse strains, C57BL/6J (B6) and DBA/2J (D2), and 35 of their inbred progeny (the BXD family). A control group was maintained in normal housing and a stress group was exposed to chronic mild stress (CMS), consisting of unpredictable stressors over 7 weeks. These included predator, social, and environmental perturbations. Alcohol intake was measured over 16 weeks in both groups during baseline (preceding 5-week period), CMS (intervening 7-week period), and post-CMS (final 4-week period). RESULTS: We detected a strong effect of CMS on alcohol intake. A few strains demonstrated CMS-related increased alcohol consumption; however, most showed decreased intake. We identified 1 nearly significant quantitative trait locus on chromosome 5 that contains the neuronal nitric oxide synthase gene (Nos1). The expression of Nos1 is frequently changed following alcohol exposure, and variants in this gene segregating among the BXD population may modulate alcohol intake in response to stress. CONCLUSIONS: The results we present here represent the first study to combine chronic stress and alcohol consumption in a genetic reference population of mice. Differences in susceptibility to the effects of stressful environments vis-à-vis alcohol use disorders would suggest that the differences have at least some basis in genetic constitution. We have also nominated a likely candidate gene underlying the large individual differences in effects of stress on alcohol consumption.

Effects of divergent selection upon adrenocortical activity on immune traits in pig.

BACKGROUND: The sustainability of farming and animal welfare requires the reconsideration of current selection schemes. In particular, implementation of new selection criteria related to animal health and welfare should help to produce more robust animals and to reduce anti-microbial use. The hypothalamo-pituitary-adrenocortical (HPA) axis plays a major role in metabolic regulation and adaptation processes and its activity is strongly influenced by genetic factors. A positive association between HPA axis activity and robustness was recently described. To explore whether selecting pigs upon HPA axis activity could increase their robustness, a divergent selection experiment was carried out in the Large White pig breed. This allowed the generation of low (HPAlo) and high (HPAhi) responders to adrenocorticotropic hormone administration. RESULTS: In this study, we compared 23 hematologic and immune parameters of 6-week-old, HPAlo and HPAhi piglets and analysed their response to a low dose of lipopolysaccharide (LPS) two weeks later. At six weeks of age, HPAhi piglets displayed greater red blood cell and leucocyte number including CD8α+ γδ cells, cytotoxic T lymphocytes, naive T helper (Th) cells and B lymphocytes as compared to HPAlo individuals. The ability of blood cells to secrete TNFα in response to LPS ex vivo was higher for HPAhi pigs. At week eight, the inflammatory response to the LPS in vivo challenge was poorly affected by the HPA axis activity. CONCLUSIONS: Divergent selection upon HPA axis activity modulated hematologic and immune parameters in 6-week-old pigs, which may confer an advantage to HPAhi pigs at weaning. However, HPAlo and HPAhi piglets did not exhibit major differences in the parameters analysed two weeks later, i. e. in 8-week-old pigs. In conclusion, chronic exposure to high cortisol levels in HPAhi pigs does not negatively impact immunity.

Time course study of the response to LPS targeting the pig immune gene networks.

BACKGROUND: Stress is a generic term used to describe non-specific responses of the body to all kinds of challenges. A very large variability in the response can be observed across individuals, depending on numerous conditioning factors like genetics, early influences and life history. As a result, there is a wide range of individual vulnerability and resilience to stress, also called robustness. The importance of robustness-related traits in breeding strategies is increasing progressively towards the production of animals with a high level of production under a wide range of climatic conditions and management systems, together with a lower environmental impact and a high level of animal welfare. The present study aims at describing blood transcriptomic, hormonal, and metabolic responses of pigs to a systemic challenge using lipopolysaccharide (LPS). The objective is to analyze the individual variation of the biological responses in relation to the activity of the HPA axis measured by the levels of plasma cortisol after LPS and ACTH in 120 juvenile Large White (LW) pigs. The kinetics of the response was measured with biological variables and whole blood gene expression at 4 time points. A multilevel statistical analysis was used to take into account the longitudinal aspect of the data. RESULTS: Cortisol level reaches its peak 4 h after LPS injection. The characteristic changes of white blood cell count to LPS were observed, with a decrease of total count, maximal at t=+4 h, and the mirror changes in the respective proportions of lymphocytes and granulocytes. The lymphocytes / granulocytes ratio was maximal at t=+1 h. An integrative statistical approach was used and provided a set of candidate genes for kinetic studies and ongoing complementary studies focused on the LPS-stimulated inflammatory response. CONCLUSIONS: The present study demonstrates the specific biomarkers indicative of an inflammation in swine. Furthermore, these stress responses persist for prolonged periods of time and at significant expression levels, making them good candidate markers for evaluating the efficacy of anti-inflammatory drugs.

Comparing the intestinal transcriptome of Meishan and Large White piglets during late fetal development reveals genes involved in glucose and lipid metabolism and immunity as valuable clues of intestinal maturity.

BACKGROUND: Maturity of intestinal functions is critical for neonatal health and survival, but comprehensive description of mechanisms underlying intestinal maturation that occur during late gestation still remain poorly characterized. The aim of this study was to investigate biological processes specifically involved in intestinal maturation by comparing fetal jejunal transcriptomes of two representative porcine breeds (Large White, LW; Meishan, MS) with contrasting neonatal vitality and maturity, at two key time points during late gestation (gestational days 90 and 110). MS and LW sows inseminated with mixed semen (from breed LW and MS) gave birth to both purebred and crossbred fetuses. We hypothesized that part of the differences in neonatal maturity between the two breeds results from distinct developmental profiles of the fetal intestine during late gestation. Reciprocal crossed fetuses were used to analyze the effect of parental genome. Transcriptomic data and 23 phenotypic variables known to be associated with maturity trait were integrated using multivariate analysis with expectation of identifying relevant genes-phenotypic variable relationships involved in intestinal maturation. RESULTS: A moderate maternal genotype effect, but no paternal genotype effect, was observed on offspring intestinal maturation. Four hundred and four differentially expressed probes, corresponding to 274 differentially expressed genes (DEGs), more specifically involved in the maturation process were further studied. In day 110-MS fetuses, Ingenuity® functional enrichment analysis revealed that 46% of DEGs were involved in glucose and lipid metabolism, cell proliferation, vasculogenesis and hormone synthesis compared to day 90-MS fetuses. Expression of genes involved in immune pathways including phagocytosis, inflammation and defense processes was changed in day 110-LW compared to day 90-LW fetuses (corresponding to 13% of DEGs). The transcriptional regulator PPARGC1A was predicted to be an important regulator of differentially expressed genes in MS. Fetal blood fructose level, intestinal lactase activity and villous height were the best predicted phenotypic variables with probes mostly involved in lipid metabolism, carbohydrate metabolism and cellular movement biological pathways. CONCLUSIONS: Collectively, our findings indicate that the neonatal maturity of pig intestine may rely on functional development of glucose and lipid metabolisms, immune phagocyte differentiation and inflammatory pathways. This process may partially be governed by PPARGC1A.

Time course of the response to ACTH in pig: biological and transcriptomic study.

BACKGROUND: HPA axis plays a major role in physiological homeostasis. It is also involved in stress and adaptive response to the environment. In farm animals in general and specifically in pigs, breeding strategies have highly favored production traits such as lean growth rate, feed efficiency and prolificacy at the cost of robustness. On the hypothesis that the HPA axis could contribute to the trade-off between robustness and production traits, we have designed this experiment to explore individual variation in the biological response to the main stress hormone, cortisol, in pigs. We used ACTH injections to trigger production of cortisol in 120 juvenile Large White (LW) pigs from 28 litters and the kinetics of the response was measured with biological variables and whole blood gene expression at 4 time points. A multilevel statistical analysis was used to take into account the longitudinal aspect of the data. RESULTS: Cortisol level reached its peak 1 h after ACTH injection. White blood cell composition was modified with a decrease of lymphocytes and monocytes and an increase of granulocytes (F D R<0.05). Basal level of cortisol was correlated with birth and weaning weights. Microarray analysis identified 65 unique genes of which expression responded to the injection of ACTH (adjusted P<0.05). These genes were classified into 4 clusters with distinctive kinetics in response to ACTH injection. The first cluster identified genes strongly correlated to cortisol and previously reported as being regulated by glucocorticoids. In particular, DDIT4, DUSP1, FKBP5, IL7R, NFKBIA, PER1, RGS2 and RHOB were shown to be connected to each other by the glucocorticoid receptor NR3C1. Most of the differentially expressed genes that encode transcription factors have not been described yet as being important in transcription networks involved in stress response. Their co-expression may mean co-regulation and they could thus provide new patterns of biomarkers of the individual sensitivity to cortisol. CONCLUSIONS: We identified 65 genes as biological markers of HPA axis activation at the gene expression level. These genes might be candidates for a better understanding of the molecular mechanisms of the stress response.

Transcriptional responses of PBMC in psychosocially stressed animals indicate an alerting of the immune system in female but not in castrated male pigs.

BACKGROUND: Brain and immune system are linked in a bi-directional manner. To date, it remained largely unknown why immune components become suppressed, enhanced, or remain unaffected in relation to psychosocial stress. Therefore, we mixed unfamiliar pigs with different levels of aggressiveness. We separated castrated male and female pigs into psychosocially high- and low- stressed animals by skin lesions, plasma cortisol level, and creatine kinase activity obtained from agonistic behaviour associated with regrouping. Peripheral blood mononuclear cells (PBMC) were collected post-mortem and differential gene expression was assessed using the Affymetrix platform (n = 16). RESULTS: Relevant stress-dependent alterations were found only between female samples, but not between castrated male samples. Molecular routes related to TREM 1 signalling, dendritic cell maturation, IL-6 signalling, Toll-like receptor signalling, and IL-8 signalling were increased in high stressed females compared to low stressed females. This indicates a launch of immune effector molecules as a direct response. According to the shifts of transcripts encoding cell surface receptors (e.g. CD14, TLR2, TLR4, TREM1) the study highlights processes acting on pattern recognition, inflammation, and cell-cell communication. CONCLUSIONS: The transcriptional response partly affected the degree of 'stress responsiveness', indicating that the high stressed females altered their signal transduction due to potential infections and injuries while fighting.

Effect of a high-fat--high-fructose diet, stress and cinnamon on central expression of genes related to immune system, hypothalamic-pituitary-adrenocortical axis function and cerebral plasticity in rats.

The intake of a high-fat/high-fructose (HF/HFr) diet is described to be deleterious to cognitive performances, possibly via the induction of inflammatory factors. An excess of glucocorticoids is also known to exert negative effects on cerebral plasticity. In the present study, we assessed the effects of an unbalanced diet on circulating and central markers of inflammation and glucocorticoid activity, as well as their reversal by dietary cinnamon (CN) supplementation. A group of male Wistar rats were subjected to an immune challenge with acute lipopolysaccharide under a HF/HFr or a standard diet. Another group of Wistar rats were fed either a HF/HFr or a control diet for 12 weeks, with or without CN supplementation, and with or without restraint stress (Str) application before being killed. We evaluated the effects of such regimens on inflammation parameters in the periphery and brain and on the expression of actors of brain plasticity. To assess hypothalamic-pituitary-adrenocortical axis activity, we measured the plasma concentrations of corticosterone and the expression of central corticotrophin-releasing hormone, mineralocorticoid receptor, glucocorticoid receptor and 11ß-hydroxysteroid dehydrogenase. We found that the HF/HFr diet induced the expression of cytokines in the brain, but only after an immune challenge. Furthermore, we observed the negative effects of Str on the plasma concentrations of corticosterone and neuroplasticity markers in rats fed the control diet but not in those fed the HF/HFr diet. Additionally, we found that CN supplementation exerted beneficial effects under the control diet, but that its effects were blunted or even reversed under the HF/HFr diet. CN supplementation could be beneficial under a standard diet. [corrected].

Thermoregulatory responses during thermal acclimation in pigs divergently selected for residual feed intake.

The objective of this study was to evaluate the performance and thermoregulatory responses during acclimation to high ambient temperature (Ta) of pigs from two lines selected for high (RFI(+)) or low (RFI(-)) residual feed intake with the hypothesis that RFI(-) pigs producing less heat would better tolerate high Ta. Pigs (50 kg initial body weight; 17 per line among which 10 of them were catheterized) were individually housed in a climatic-controlled room where Ta was maintained at 24.2 ± 0.4 °C during 7 days and thereafter at 30.4 ± 0.7 °C during 14 days. Irrespective of Ta, RFI(-) pigs had lower feed intake (ADFI) and similar average daily gain (ADG) than RFI(+) pigs. Whatever the line, ADFI, ADG, and feed efficiency decreased with increased Ta. Overall, the Ta increase resulted in an increase in rectal temperature (RT), skin temperature (ST), and respiratory rate (RR) within the first 24-48 h and, subsequently, in a decrease followed by stabilization. The RT decrease during acclimation occurred 24 h earlier in RFI(-) pigs than in RFI(+). Thyroid hormones and cortisol decreased at high Ta and it was similar in both lines. Based on performance and RT, ST, and RR responses, it seems that selection for low RFI tends to ameliorate pigs' tolerance to high Ta. Nevertheless, this selection does not induce significant differences between lines in endocrine and metabolite responses during thermal stress.

Genotype on the pigmentation regulating PMEL17 gene affects behavior in chickens raised without physical contact with conspecifics.

Chickens homozygous for the Dominant white or wild-type allele of PMEL17 were subjected to a broad phenotyping in order to detect consistent differences between genotypes. To exclude feather pecking, the chickens were individually housed without physical contact, from the day of hatching, and tested for social, aggressive, fear and exploratory behaviors, and corticosterone and testosterone levels were assessed. In a principal component analysis, 53.2% of the behavior variation was explained by two factors. Factor one was an activity and social factor, and there was a significant effect of genotype on the factor scores. On factor two, related to aggressive behavior, there were significant effects of genotype, sex and their interaction. There were no genotype effects on hormone levels or any other measured non-behavioral phenotypes. Hence, differences in behavior between PMEL17 genotypes remained when negative social experiences were excluded, indicating a direct pleiotropic effect of the gene on behavior.

Association of HPA axis-related genetic variation with stress reactivity and aggressive behaviour in pigs.

BACKGROUND: Stress, elicited for example by aggressive interactions, has negative effects on various biological functions including immune defence, reproduction, growth, and, in livestock, on product quality. Stress response and aggressiveness are mutually interrelated and show large interindividual variation, partly attributable to genetic factors. In the pig little is known about the molecular-genetic background of the variation in stress responsiveness and aggressiveness. To identify candidate genes we analyzed association of DNA markers in each of ten genes (CRH g.233C>T, CRHR1 c.*866_867insA, CRHBP c.51G>A, POMC c.293_298del, MC2R c.306T>G, NR3C1 c.*2122A>G, AVP c.207A>G, AVPR1B c.1084A>G, UCN g.1329T>C, CRHR2 c.*13T>C) related to the hypothalamic-pituitary-adrenocortical (HPA) axis, one of the main stress-response systems, with various stress- and aggression-related parameters at slaughter. These parameters were: physiological measures of the stress response (plasma concentrations of cortisol, creatine kinase, glucose, and lactate), adrenal weight (which is a parameter reflecting activity of the central branch of the HPA axis over time) and aggressive behaviour (measured by means of lesion scoring) in the context of psychosocial stress of mixing individuals with different aggressive temperament. RESULTS: The SNP NR3C1 c.*2122A>G showed association with cortisol concentration (p = 0.024), adrenal weight (p = 0.003) and aggressive behaviour (front lesion score, p = 0.012; total lesion score p = 0.045). The SNP AVPR1B c.1084A>G showed a highly significant association with aggressive behaviour (middle lesion score, p = 0.007; total lesion score p = 0.003). The SNP UCN g.1329T>C showed association with adrenal weight (p = 0.019) and aggressive behaviour (front lesion score, p = 0.029). The SNP CRH g.233C>T showed a significant association with glucose concentration (p = 0.002), and the polymorphisms POMC c.293_298del and MC2R c.306T>G with adrenal weight (p = 0.027 and p < 0.0001 respectively). CONCLUSIONS: The multiple and consistent associations shown by SNP in NR3C1 and AVPR1B provide convincing evidence for genuine effects of their DNA sequence variation on stress responsiveness and aggressive behaviour. Identification of the causal functional molecular polymorphisms would not only provide markers useful for pig breeding but also insight into the molecular bases of the stress response and aggressive behaviour in general.

Tonic and phasic effects of corticosterone on food restriction-induced hyperactivity in rats.

In the experimental rat model of anorexia nervosa the interactions between the hyperactivity of the hypothalamo-pituitary-adrenal (HPA) axis and increased physical activity associated with food restriction remain unidentified. In addition to their role in energy homeostasis, glucocorticoids have complex effects in the central nervous system, increasing the salience of activities such as wheel running. The objective of the present study was to analyze the role of corticosterone (cort) on wheel activity in food-restricted rats. Lewis rats were adrenalectomized and replaced with pellets containing increasing amounts of cort that caused different steady-state plasma concentrations from low to high HPA activity. They were given free access to a running wheel and were fed ad libitum or food-restricted. We also investigated the acute effect of cort injection mimicking the prefeeding cort peak on prefeeding wheel activity. Wheel running induced by food restriction was nearly non-existent in adrenalectomized food-restricted rats and increased in a dose-related manner with cort replacement. An acute stimulation of activity was also expressed during the preprandial peak of cort, suppressed by adrenalectomy and experimentally restored by acute cort injection. No such effects of cort were found in ad libitum fed rats. Our data demonstrate that food restriction-induced hyperactivity is critically and quantitatively dependent upon cort, not only on the mean basal levels of the hormone but also on the secretory peak that accompanies the burst of preprandial activity. The present results have special relevance for the pathophysiology of anorexia nervosa and other compulsive behaviors.

Genetic Factors Mediate the Impact of Chronic Stress and Subsequent Response to Novel Acute Stress.

Individual differences in physiological and biobehavioral adaptation to chronic stress are important predictors of health and fitness; genetic differences play an important role in this adaptation. To identify these differences we measured the biometric, neuroendocrine, and transcriptional response to stress among inbred mouse strains with varying degrees of genetic similarity, C57BL/6J (B), C57BL/6NJ (N), and DBA/2J (D). The B and D strains are highly genetically diverse whereas the B and N substrains are highly similar. Strain differences in hypothalamic-pituitary-adrenal (HPA) axis cross-sensitization were determined by plasma corticosterone (CORT) levels and hippocampal gene expression following 7-weeks of chronic mild stress (CMS) or normal housing (NH) and subsequent exposure to novel acute restraint. Fecal CORT metabolites and body and organ weights were also measured. All strains exposed to CMS had reduced heart weights, whereas body weight gain was attenuated only in B and N strains. Acute stress alone produced larger plasma CORT responses in the D and N strains compared to the B strain. CMS paired with acute stress produced cross-sensitization of the CORT response in the N strain. The N strain also had the largest number of hippocampal transcripts with up-regulated expression in response to stress. In contrast, the D strain had the largest number of transcripts with down-regulated expression following CMS and acute stress. In summary, we observed differential responses to CMS at both the physiological and molecular level among genetically diverse strains, indicating that genetic factors drive individual differences in experience-dependent regulation of the stress response.

Exploring the involvement of Tac2 in the mouse hippocampal stress response through gene networking.

Tachykinin 2 (Tac2) is expressed in a number of areas throughout the brain, including the hippocampus. However, knowledge about its function has been only well explored in the hypothalamus in the context of reproductive health. In this study, we identified and validated increased hippocampal Tac2 mRNA expression in response to chronic mild stress in mice. Expression quantitative trait locus (eQTL) analysis showed Tac2 is cis-regulated in the hippocampus. Using a systems genetics approach, we constructed a Tac2 co-expression network to better understand the relationship between Tac2 and the hippocampal stress response. Our network identified 69 total genes associated with Tac2, several of which encode major neuropeptides involved in hippocampal stress signaling as well as critical genes for producing neural plasticity, indicating that Tac2 is involved in these processes. Pathway analysis for the member of Tac2 gene network revealed a strong connection between Tac2 and neuroactive ligand-receptor interaction, calcium signaling pathway, as well as cardiac muscle contraction. In addition, we also identified 46 stress-related phenotypes, specifically fear conditioning response, that were significantly correlated with Tac2 expression. Our results provide evidence for Tac2 as a strong candidate gene who likely plays a role in hippocampal stress processing and neural plasticity.

On association of the lethal yellow (AY) mutation in the agouti gene with the alterations in mouse brain and behavior.

Lethal yellow (AY) mutation causes obesity and type-2 diabetes in mice. Here we studied the effect of the AY mutation on the brain and behavior. The experiments were carried out on adult (11-12 weeks old) males of AY/a mice and their wild-type littermates (a/a). Mice of AY/a and a/a genotypes did not differ in their home cage activity, sleep, food and water consumption, learning ability in the Morris water maze, anxiety in the open field and elevated plus-maze, as well as in the level of monoamines, metabolites and some genes expression in the brain. At the same time, the fat mass, depressive-like immobility in the forced swim and tail suspension tests were significantly increased in AY/a mice compared with a/a ones. Magnetic resonance imaging revealed a significant reduction of cortex volume in AY/a mice. The level of mRNA of Ptpn5 gene encoding striatal enriched tyrosine phosphatase in the frontal cortex of AY/a mice was significantly elevated compared with their wild-type littermates. This is the first report on the alterations in the brain and behavior in the AY/a mouse line. It is tempting to speculate that this mouse line can serve as a new and useful preclinical model to study neurobehavioral complications associated with obesity and type-2 diabetes.

Gene array and real time PCR analysis of the adrenal sensitivity to adrenocorticotropic hormone in pig.

BACKGROUND: Variability in hypothalamic-pituitary-adrenal (HPA) axis activity has been shown to be influenced by genetic factors and related to great metabolic differences such as obesity. The aim of this study was to investigate molecular bases of genetic variability of the adrenal sensitivity to ACTH, a major source of variability, in Meishan (MS) and Large White (LW) pigs, MS being reported to exhibit higher basal cortisol levels, response to ACTH and fatness than LW. A pig cDNA microarray was used to identify changes in gene expression in basal conditions and in response to ACTH stimulation. RESULTS: Genotype and/or ACTH affected the expression of 211 genes related to transcription, cell growth/maintenance, signal transduction, cell structure/adhesion/extra cellular matrix and protein kinase/phosphatase activity. No change in the expression of known key regulator proteins of the ACTH signaling pathway or of steroidogenic enzymes was found. However, Mdh2, Sdha, Suclg2, genes involved in the tricarboxylic acid (TCA) pathway, were over-expressed in MS pigs. Higher TCA cycle activity in MS than in LW may thus result in higher steroidogenic activity and thus explain the typically higher cortisol levels in MS compared to LW. Moreover, up-regulation of Star and Ldlr genes in MS and/or in response to ACTH suggest that differences in the adrenal function between MS and LW may also involve mechanisms requisite for cholesterol supply to steroidogenesis. CONCLUSION: The present study provides new potential candidate genes to explain genetic variations in the adrenal sensitivity to ACTH and better understand relationship between HPA axis activity and obesity.

Genetic Contribution to Initial and Progressive Alcohol Intake Among Recombinant Inbred Strains of Mice.

We profiled individual differences in alcohol consumption upon initial exposure and during 5 weeks of voluntary alcohol intake in female mice from 39 BXD recombinant inbred strains and parents using the drinking in the dark (DID) method. In this paradigm, a single bottle of 20% (v/v) alcohol was presented as the sole liquid source for 2 or 4 h starting 3 h into the dark cycle. For 3 consecutive days mice had access to alcohol for 2 h followed by a 4th day of 4 h access and 3 intervening days where alcohol was not offered. We followed this regime for 5 weeks. For most strains, 2 or 4 h alcohol intake increased over the 5-week period, with some strains demonstrating greatly increased intake. There was considerable and heritable genetic variation in alcohol consumption upon initial early and sustained weekly exposure. Two different mapping algorithms were used to identify QTLs associated with alcohol intake and only QTLs detected by both methods were considered further. Multiple suggestive QTLs for alcohol intake on chromosomes (Chrs) 2, 6, and 12 were identified for the first 4 h exposure. Suggestive QTLs for sustained intake during later weeks were identified on Chrs 4 and 8. Thirty high priority candidate genes, including Entpd2, Per3, and Fto were nominated for early and sustained alcohol intake QTLs. In addition, a suggestive QTL on Chr 15 was detected for change in 2 h alcohol intake over the duration of the study and Adcy8 was identified as a strong candidate gene. Bioinformatic analyses revealed that early and sustained alcohol intake is likely driven by genes and pathways involved in signaling, and/or immune and metabolic function, while a combination of epigenetic factors related to alcohol experience and genetic factors likely drives progressive alcohol intake.

Methodologies for Assessing Disease Tolerance in Pigs.

Features of intensive farming can seriously threaten pig homeostasis, well-being and productivity. Disease tolerance of an organism is the adaptive ability in preserving homeostasis and at the same time limiting the detrimental impact that infection can inflict on its health and performance without affecting pathogen burden per se. While disease resistance (DRs) can be assessed measuring appropriately the pathogen burden within the host, the tolerance cannot be quantified easily. Indeed, it requires the assessment of the changes in performance as well as the changes in pathogen burden. In this paper, special attention is given to criteria required to standardize methodologies for assessing disease tolerance (DT) in respect of infectious diseases in pigs. The concept is applied to different areas of expertise and specific examples are given. The basic physiological mechanisms of DT are reviewed. Disease tolerance pathways, genetics of the tolerance-related traits, stress and disease tolerance, and role of metabolic stress in DT are described. In addition, methodologies based on monitoring of growth and reproductive performance, welfare, emotional affective states, sickness behavior for assessment of disease tolerance, and methodologies based on the relationship between environmental challenges and disease tolerance are considered. Automated Precision Livestock Farming technologies available for monitoring performance, health and welfare-related measures in pig farms, and their limitations regarding DT in pigs are also presented. Since defining standardized methodologies for assessing DT is a serious challenge for biologists, animal scientists and veterinarians, this work should contribute to improvement of health, welfare and production in pigs.

Functional implication of an Arg307Gly substitution in corticosteroid-binding globulin, a candidate gene for a quantitative trait locus associated with cortisol variability and obesity in pig.

We previously reported that corticosteroid-binding globulin gene (Cbg) may be the causal gene of a quantitative trait locus associated with cortisol levels, fat deposition, and muscle content in a pig intercross. Sequence analysis of parental animals allowed us to identify four amino-acid substitutions. Here we have examined if any of these single amino acid substitutions could be responsible for the difference in CBG binding and affinity for cortisol between the parental breeds, using in vitro assays of Cbg variants after transfection of mammalian cells. Additionally, the Cbg coding region was analyzed in samples from a synthetic pig line to study association between polymorphism and CBG biochemical properties, carcass composition, and meat quality. Both in vitro transfection assays and the association studies suggest a role of the Arg307Gly mutation in increasing CBG capacity (by >70%) and decreasing CBG affinity for cortisol (by 30%). The Ile265Val substitution may also have an effect on decreasing CBG affinity for cortisol by 25%. The mutations Ser15Ile and Thr257Met do not seem to have an effect on CBG parameters. The Arg307Gly substitution was the only mutation associated with a parameter of meat quality and no mutation was linked to carcass composition.