Biology subjects

Riquet, J.

Publications and source records attributed to Riquet, J..

5 recordsLinked to original sources

bioRxiv2026

Genetic and heat-stress related environmental influences on pig whole-blood gene expression levels

BackgroundGene expression levels are affected by genetics and environmental effects. However, quantification of the influence of genetics and environmental effects on gene expression remains limited, especially in farm animals. Here, the relative influence of genetic and heat-related environmental variations on gene expression levels was investigated in pigs, using a backcross herd of diverse heat adaptation levels. Backcross animals were raised in either a tropical or temperate environment. Animals raised in temperate environment were subjected to an experimental heat stress at the end of their growth. ResultsWe identified 1,967 differentially expressed genes (DEGs) between pigs raised in the tropical (n = 181) and temperate (n = 180) facilities, and 472 DEGs throughout a 3 weeks experimental heat stress. Transcriptome-wide association (TWAS) study identified 139 associations between gene expression levels and thermoregulation/production traits. We detected 6,014 expression quantitative trait loci (eQTLs) associated with the expression level of 3,297 genes. Genetic variance was estimated to explain 36.3% of gene expression variance on average, and was the main source of variance for 27.7% of transcripts. Most eQTLs found are located in proximal regions (cis-eQTLs) and few within distal regions (trans-eQTLs) to their assigned genes. A trans-eQTL hotspot highlighted a hematopoietic mechanism driven by GPATCH8. An integration of GWAS and TWAS pointed to TMCO1 and ZNF184 as candidate genes for backfat thickness. ConclusionsThis study provides a better understanding of the impact of climate, heat stress and genetic influences on the pig whole blood transcriptome.

genomics↗

bioRxiv2025

An extensive and unbiased genome-wide scan for parent-of-origin expressed genes in the pig clarifies the conservation landscape of genomic imprinting

Genomic imprinting, a mechanism resulting in parent-of-origin expression of genes through epigenetic regulation, intersects with a broad range of biological fields including evolution, molecular genetics and epigenetics and determinism of complex traits. Although next generation sequencing technologies enable nowadays to detect imprinted genes in a genome-wide manner, a wide spectrum of this phenomena is evaluated only in humans and mice. Here, we propose to map genes showing a parental expression bias in hypothalamus, muscle and placenta in piglets around birth using an extensive and unbiased strategy that relied on reciprocal crosses, genetics reconstruction of parental phases after imputation and statistical analyses discriminating parent-of-origin from allele-specific expression. We detected 440 unique genes with a weak to exclusive parental expression bias including 114 unique genes with an imbalance ratio above 25:75. About thirty imprinted genes are common to human and/or mice and an equivalent number is shared between tissues, suggesting an overall weak conservation landscape of genomic imprinting. Interestingly, we identified novel parent-of-origin expressed genes involved in neurodevelopmental (PITRM1, Pitrilysin Metallopeptidase 1) and fetal growth (FAM20B, Glycosaminoglycan Xylosylkinase and POU6F2, POU Class 6 Homeobox 2) functions. In addition, deeper analyses of specific loci likely highlighted lineage-specific imprinted genes such as a Zinc Finger Protein 300-like gene as well as specific imprinted isoforms of COPG2 (COPI Coat Complex Subunit Gamma 2), a gene showing conflicting data in the literature. Altogether, our results bring pig as the most comprehensively and exhaustively documented species for genomic imprinting after human and mice organisms. A weak conservation of this mechanism across species and tissues suggested a distinction between a small number of core imprinted genes and others parent-of-origin expressed genes that seemed subjected to evolutionary forces for acquiring their imprinting status either in a lineage-specific or tissue-specific manner.

genomics↗

bioRxiv2022

Discovering genomic regions associated with the phenotypic differentiation of European local pig breeds

BackgroundIntensive selection of modern pig breeds resulted in genetic improvement of productive traits while local pig breeds remained less performant. As they have been bred in extensive systems, they have adapted to specifical environmental conditions resulting in a rich genotypic and phenotypic diversity. This study is based on European local pig breeds genetically characterized using DNA-pool sequencing data and phenotypically characterized using breed level phenotypes related to stature, fatness, growth and reproductive performance traits. These data were analyzed using a dedicated approach to detect selection signatures linked to phenotypic traits in order to uncover potential candidate genes that may be under adaptation to specific environments. ResultsGenetic data analysis of European pig breeds revealed four main axes of genetic variation represented by Iberian and modern breeds (i.e. Large White, Landrace, and Duroc). In addition, breeds clustered according to their geographical origin, for example French Gascon and Basque breeds, Italian Apulo Calabrese and Casertana breeds, Spanish Iberian and Portuguese Alentejano breeds. Principal component analysis of phenotypic data distinguished between larger and leaner breeds with better growth potential and reproductive performance on one hand and breeds that were smaller, fatter, and had low growth and reproductive efficiency on the other hand. Linking selection signatures with phenotype identified 16 significant genomic regions associated with stature, 24 with fatness, 2 with growth and 192 with reproduction. Among them, several regions contained candidate genes with possible biological effect on stature, fatness, growth and reproduction performance traits. For example, strong associations were found for stature in two regions containing the ANXA4 and ANTXR1 genes, for fatness containing the DNMT3A and POMC genes and for reproductive performance containing the HSD17B7 gene. ConclusionsThe present study on European local pig breeds used a dedicated approach for searching selection signatures supported by phenotypic data at the breed level to identify potential candidate genes that may have adapted to different living environments and production systems. Results can be useful to define conservation programs of local pig breeds.

genetics↗

bioRxiv2021

A genome-wide epistatic network underlies the molecular architecture of continuous color variation of body extremities: a rabbit model

Deciphering the molecular architecture of coat coloration for a better understanding of the biological mechanisms underlying pigmentation still remains a challenge. We took advantage of a rabbit French experimental population in which both a pattern and a gradient of coloration from white to brown segregated within the himalayan phenotype. The whole experimental design was genotyped using the high density Affymetrix(R) AxiomOrcun SNP Array and phenotyped into 6 different groups ordered from the lighter to the darker. Genome-wide association analyses pinpointed an oligogenic determinism, under recessive and additive inheritance, involving genes already known in melanogenesis (ASIP, KIT, MC1R, TYR), and likely processed pseudogenes linked to ribosomal function, RPS20 and RPS14. We also identified (i) gene-gene interactions through ASIP:MC1R affecting light cream/beige phenotypes while KIT:RPS responsible of dark chocolate/brown colors and (ii) a genome-wide epistatic network involving several others coloration genes such as POT1 or HPS5. Finally, we determined the recessive inheritance of the English spotting phenotype likely involving a copy number variation affecting at least the end of the coding sequence of the KIT gene. Our analyses of coloration as a continuous trait allowed us to go beyond much of the established knowledge through the detection of additional genes and gene-gene interactions that may contribute to the molecular architecture of the coloration phenotype. Moreover, the characterization of a network including genes that contribute to melanogenesis and pigmentation, two processes affected in various human disorders, shows the potential interest of our rabbit model for transversal studies.

genetics↗

bioRxiv2020

Identification of genomic regions affecting production traits in pigs divergently selected for feed efficiency

BackgroundFeed efficiency is a major driver of the sustainability of pig production systems. Understanding biological mechanisms underlying these agronomic traits is an important issue whether for environment and farms economy. This study aimed at identifying genomic regions affecting residual feed intake (RFI) and other production traits in two pig lines divergently selected for RFI during 9 generations (LRFI, low RFI; HRFI, high RFI). ResultsWe built a whole dataset of 570,447 single nucleotide polymorphisms (SNPs) in 2,426 pigs with records for 24 production traits after both imputation and prediction of genotypes using pedigree information. Genome-wide association studies (GWAS) were performed including both lines (Global-GWAS) or each line independently (LRFI-GWAS and HRFI-GWAS). A total of 54 chromosomic regions were detected with the Global-GWAS, whereas 37 and 61 regions were detected in LRFI-GWAS and HRFI-GWAS, respectively. Among those, only 15 regions were shared between at least two analyses, and only one was common between the three GWAS but affecting different traits. Among the 12 QTL detected for RFI, some were close to QTL detected for meat quality traits and 9 pinpointed novel genomic regions for some harbored candidate genes involved in cell proliferation and differentiation processes of gastrointestinal tissues or lipid metabolism-related signaling pathways. Detection of mostly different QTL regions between the three designs suggests the strong impact of the dataset on the detection power, which could be due to the changes of allelic frequencies during the line selection. ConclusionsBesides efficiently detecting known and new QTL regions for feed efficiency, the combination of GWAS carried out per line or simultaneously using all individuals highlighted the identification of chromosomic regions under selection that affect various production traits.

genetics↗