Characterization of potential genes related to thermoregulation in Santa Ines sheep

• Grant number: 24/04286-0
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2024
• End date: August 31, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Ecology of Domestic Animals and Ethology
• Principal Investigator: Cristiane Gonçalves Titto
• Grantee: Cristiane Gonçalves Titto
• Host Institution: Faculdade de Zootecnia e Engenharia de Alimentos (FZEA). Universidade de São Paulo (USP). Pirassununga , SP, Brazil
• Associated researchers: Alfredo Manuel Franco Pereira ; Francisco José de Novais ; Gerson Barreto Mourão ; Heidge Fukumasu ; Messy Hannear de Andrade Pantoja ; Raluca Mateescu

Abstract

In sheep farming, there is a lot of knowledge about the effects of heat stress on health, reproduction and performance. However, there are few studies on the adaptation of hair sheep to extreme weather events, especially heat, from a genomic point of view. The study is based on the hypothesis that an animal with greater thermotolerance has comparative advantages in the face of climatic irregularities and that this is related to the greater expression of certain genes. The aim is to identify the most expressed genes between more and less heat-tolerant sheep, characterized based on the maintenance of their rectal temperature (RT) during the acclimatization process in a climate chamber during heat stress. Phase 1 will use pancreas, thyroid and adrenal tissue samples from 14 sheep (7 thermotolerant and 7 non-thermotolerant) selected from an initial group of 80 Santa Ines sheep. For selection, the TR taken was used as the response variable and analyzed using the restricted maximum likelihood method under a mixed model. This included only the fixed effect of evaluation time and, as a random effect, the animal effect. The BLUP predictions obtained for each sheep, which quantify the individual heat stress response, were used to order the sheep from the most heat tolerant to the least tolerant. Samples were taken after humane slaughter, after 7 days of 36°C cycles starting at 10:00 until 16:00, with 28°C maintained from 16:00 until 10:00. There was a controlled interval of up to 15 minutes between leaving the chamber and collecting the tissues, to avoid altering the RNA response. The samples will be used for RNA sequencing analysis to evaluate the gene expression of possible genes involved in heat tolerance, as well as a global analysis between the tissues to identify similar metabolic pathways. In a second phase, the two best tissues in terms of differential expression will be chosen for validation in 14 new animals, following the same methodology as in phase 1. In the future, these studied characteristics will be used to select more and less thermotolerant animals. (AU)