BREED unit offers a thesis topic

Global warming is currently driving livestock industries to adapt their practice to changes. Ruminants are poorly adapted to heat waves due to rumen fermentations. In addition, their fertility seems to be a trade-off for heat resistance. Indeed, several studies have identified a direct impact of the combined temperature and humidity index (THI) on health, production and fertility1,2,3, with a decrease in sperm production and an increase in sperm defects (morphological abnormalities). In cattle, direct effects of in utero heat stress on future adult performance have also been described4. 
In adult bulls, heat waves directly applied to the testes have been shown to alter small non-coding RNAs (sncRNAs) in sperm5. Composed of several families (miRNA, piRNA, tRNA, rRNA...), sncRNAs are involved in the post-transcriptional regulation of genome expression. Their tissue-specific expression is thus altered by environmental changes, leading to potential changes in genome expression. In several species, studies have highlighted that post-testis modifications of mature sperm sncRNAs could affect early embryo development, leading to perturbations in phenotype construction of the next generation. Accumulating scientific knowledge on changes in ruminant sperm sncRNAs and their potential impact on embryo development is needed to manage the effects of global warming in livestock. To reduce the effects of heat stress, mitigation solutions exist (fans, sprayers...), but they are often not always adapted to farming conditions (important resources required). However, other approaches, mainly focused on food additive, can be applied. As a matter of fact, the use of nitric oxide precursors, promoting vasodilation, is one of the solutions tested in BREED to counteract the negative effects of heat waves during gestation. 

In collaboration with Florida University and INRAE SELMET (Toulouse, France), the proposed project, based on small ruminants, will decipher the epigenetic sncRNA mechanisms involved in the construction of male phenotypes. Composed of 6 workpackages, the project aims to (i) study the effects of heat wave and citrulline and/or other appropriate supplementation on the expression of sncRNA profiles in sperm and somatic cells; (ii) explore the dialogue between the sperm and somatic cells through the extracellular vesicles (epididymosomes and prostasomes); identify and develop early (pre-puberty) predictors of male fertility, through the extracellular vesicles in the blood.

The student, with the supervisor’s support, will (i) assist for the animal experimentation set-up, making sure it follows the experimental plan; (ii) handle the sampling of tissues, the semen and somatic cells; (iii) perform sncRNA extractions and preparations to next-generation sequencing; (iv) conduct and decipher the bioinformatic analysis. An important part of the work is to characterize the iso and canonical sequences, the different sncRNA subfamilies and the dynamic of sncRNAs expression according to the tissue and the applied stress.

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