Biology subjects

Chavatte-Palmer, P.

Publications and source records attributed to Chavatte-Palmer, P..

4 recordsLinked to original sources

bioRxiv2022

Factors affecting post-breeding endometritis, pregnancy rate and embryonic/fetal death in sport mares in two French commercial stud farms: special focus on age, parity and lactating status effects

BackgroundFor a long time, important and progressive fertility decline is observed with mare age. Parity and yearly breeding, however, are controversial factors impacting fertility. Most of these studies were performed on race horses and before 2010, on data accumulated before. The cumulative effects of age and nulliparity/nursing with improved reproductive technologies and practices, often observed in sport horses, has not been investigated yet. ObjectivesTo investigate the effect of age, parity and nursing, as well as reproductive management, on post-insemination inflammation and fertility in sports mares. Study designAge, parity, nursing status, follicular size before ovulation, estrus and/or ovulation induction, artificial insemination (AI) protocol, post-breeding inflammation and treatment, Day 14 pregnancies rates (PR) and number of embryos, as well as subsequent foaling the next year were recorded for 277 mares (506 cycles) over one breeding season in two French commercial studs. MethodsMultivariate logistic regression models were used. ResultsPR was 41.9% per cycle and 76.5% at the end of the season. Post-insemination fluid accumulation risk was increased in >10-year-old, barren or July or August inseminated mares (p<0.0001, OR=3.29, 5.389 and 3.329, respectively). PR were reduced in mares >10-year-old vs younger or inseminated with frozen vs fresh or refrigerated semen (p<0.05, OR=0.622 and 0.582, respectively). More pregnancy on Day 14 were observed in mares with multiple ovulations compared to mono- ovulation (p<0.05, OR=1.791). Regardless the age, PR only tended to be improved in multiparous (p=0.07, OR=1.434 in parous vs nulliparous) but in >10-year-old mares, multiparity greatly increased PR (44.09% in parous vs 30.89% in nulliparous, p<0.05). Main limitationsLimited number of mares. ConclusionIn sport horse, maternal age was more important than parity and lactating status for reproductive success but cumulative effects of nulliparity and aging was deleterious on PR, demonstrating their importance in the management of sport mares.

systems biology↗

bioRxiv2022

Nulliparity affects the expression of a limited number of genes and pathways in Day 8 equine embryos

Nulliparous mares produce lighter and smaller foals compared to mares having previously foaled, with effects observed at least until 4 months of age. The need for a first gestation priming for the uterus to reach its full capacity has been proposed to explain this observation. Embryo developmental defects could be hypothesized but effects of maternal parity on the embryo have only been described once, in old mares, thus combining effects of parity and old age. The aim of this study was to determine effects of mare parity on embryo gene expression. Day-8 post ovulation blastocysts were collected from young (5/6 years old) nulliparous (YN, N=6) or multiparous (YM, N=4) non-nursing Saddlebred mares, inseminated with the semen of one stallion. Pure (TE_part) or inner-cell-mass-enriched (ICMandTE) trophoblast were obtained by embryo bisection for RNA sequencing (paired end, non-oriented, Illumina, NextSeq500). Deconvolution was performed on the ICMandTE dataset. Differential expression, with embryo sex and diameter as cofactors and gene set enrichment analysis (GO BP, KEGG, REACTOME databases) were performed using a false discovery rate <0.05 cutoff. Only a few genes were altered (ICM: n=18; TE: n=6) but several gene sets were perturbed (ICM: n=62; TE: n=50) by maternal parity. In YM, only pathways related to transcription, RNA processing and vesicle transport functions were enriched in the ICM whereas only pathways related to RNA localization were enriched in TE. In YN, while only gene sets related to ribosomes and extracellular matrix were enriched in the ICM, functions related to energy and lipid metabolism, lipid transport and interleukin-1 signaling were enriched in the TE. In conclusion, several genes and pathways are affected in embryos collected from nulliparous mares, with different effects on TE and ICM. Embryo development is altered in nulliparous mares, which could partially explain the term phenotype. Whether differences in gene expression result/induce poor embryo-maternal communication remains to be determined.

developmental biology↗

bioRxiv2021

Maternal parity affects Day 8 embryo gene expression in old mares

As sport career is a priority in most of equine breeds, mares are frequently bred for the first time at an advanced age. Both age and first gestation were shown to have a deleterious effect on reproduction outcomes, respectively on fertility and offspring weight but the effect mares parity in older mares on embryo quality has never been considered. The aim of this project was to determine the effect of old mares nulliparity on gene expression in embryos. Day 8 post ovulation embryos were collected from old (10-16 years old) nulliparous (ON, N=5) or multiparous (OM, N=6) non-nursing Saddlebred mares, inseminated with the semen of one stallion. Pure (TE_part) or inner cell mass enriched (ICMandTE) trophoblast were obtained by embryo bisection and paired end, non-oriented RNA sequencing (Illumina, NextSeq500) was performed on each hemi-embryo. To discriminate gene expression in the ICM from that in the TE, deconvolution (DeMixT R package) was used on the ICMandTE dataset. Differential expression was analyzed (DESeq2) with embryo sex and diameter as cofactors using a false discovery rate <0.05 cutoff. Although the expression of only a few genes was altered by mares nulliparity (33 in ICM and 23 in TE), those genes were related to nutrient exchanges and responses to environment signaling, both in ICM and TE, suggesting that the developing environment from these mares are not optimal for embryo growth. In conclusion, being nulliparous and old does not seem to be the perfect match for embryonic development in mares. Summary sentenceMares parity in old mares impacts the expression of genes related to development and molecule exchanges in ICM and TE of blastocysts suggesting an adaptation to an altered environment.

developmental biology↗

bioRxiv2021

Maternal age affects equine Day 8 embryo gene expression both in trophoblast and inner cell mass

BackgroundBreeding a mare until she is not fertile or even until her death is common in equine industry but the fertility decreases as the mare age increases. Embryo loss due to reduced embryo quality is partly accountable for this observation. Here, the effect of mares age on blastocysts gene expression was explored. Day 8 post-ovulation embryos were collected from multiparous young (YM, 6-year-old, N = 5) and older (OM, > 10-year-old, N = 6) non-nursing Saddlebred mares, inseminated with the semen of one stallion. Pure or inner cell mass (ICM) enriched trophoblast, obtained by embryo bisection, were RNA sequenced. Deconvolution algorithm was used to discriminate gene expression in the ICM from that in the trophoblast. Differential expression was analyzed with embryo sex and diameter as cofactors. Functional annotation and classification of differentially expressed genes and gene set enrichment analysis were also performed. ResultsMaternal aging did not affect embryo recovery rate, embryo diameter nor total RNA quantity. In both compartments, the expression of genes involved in mitochondria and protein metabolism were disturbed by maternal age, although more genes were affected in the ICM. Mitosis, signaling and adhesion pathways and embryo development were decreased in the ICM of embryos from old mares. In trophoblast, ion movement pathways were affected. ConclusionsThis is the first study showing that maternal age affects gene expression in the equine blastocyst, demonstrating significant effects as early as 10 years of age. These perturbations may affect further embryo development and contribute to decreased fertility due to aging.

physiology↗