72 Environmental conditions can modulate the gene expression of embryo from primiparous beef cows
A. P. Lemes A , P. K. Fontes B , M. F. G. Nogueira C , Y. F. Watanabe D , A. R. Garcia E and L. U. Gimenes AA São Paulo State University, Jaboticabal, Sao Paulo, Brazil
B Federal University of ABC, Santo Andre, Sao Paulo, Brazil
C São Paulo State University, Botucatu, Sao Paulo, Brazil
D Vitrogen, Cravinhos, Sao Paulo, Brazil
E Embrapa Southeast Livestock, Sao Carlos, Sao Paulo, Brazil
Reproduction, Fertility and Development 34(2) 272-272 https://doi.org/10.1071/RDv34n2Ab72
Published: 7 December 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
It is known that the natural shading provided by silvopastoral systems ameliorates the microclimate in tropical pasture areas and improves animal thermal comfort (Lemes et al. 2021 Sci. Rep. 11, 14092). Thus, the aim of this study was to evaluate the expression of genes that signal embryonic quality, heat stress, metabolism, and embryonic development in embryos produced in vitro from oocytes of primiparous Canchin beef cows (5/8 Charolais - Bos taurus; and 3/8 Nelore and Guzerá - Bos indicus) maintained in two different grazing systems: (1) silvopastoral system (SP; 10 cows; intensive rotational grazing combined with eucalyptus trees at 15 × 2 m spacing); (2) rotational regular system (IR; 8 cows; intensive rotational grazing without trees). The experiment was carried out at Embrapa Livestock Southeast, in São Carlos, SP, Brazil, under tropical climate condition, (Cwa, Köppen’s climate classification). The cows were simultaneously submitted to ovum pick-up (OPU) once a month, and viable oocytes were submitted to in vitro embryo production by a commercial laboratory, from January to May 2017. The embryos (hatched, hatching, and expanded blastocysts) produced in this period were cryopreserved by the slow-freezing method and stored in liquid nitrogen on Day 8. Embryos from cows of SP and IR produced in the period were thawed and pooled in a total of 24 samples (12 samples of four embryos each/group) were submitted to gene expression analysis using Applied Biosystems™ TaqMan® Assays, specific for Bos taurus species. Total mRNA abundance of 96 genes was analysed and real-time quantitative (RT-q)PCR was performed in the Biomark HD System (Fluidigm). Relative mRNA abundance was calculated by ΔCt [target genes/reference genes (GAPDH, HMBS, PPIA, and RPL15)] and then transformed to 2^-(ΔCt). For statistical analysis, 42 genes related to lipid metabolism, glucose metabolism, epigenetic regulation, embryo quality and development, apoptosis, oxidative stress, heat shock response, and stress response were submitted to PROC MIXED of SAS (SAS Institute Inc.). The results were presented as mean ± standard error and P-values < 0.05 were considered significant. The expression of the ACSL1 gene (P < 0.01), signalling lipid metabolism, was higher in embryos from cows kept in SP (0.09 ± 0.004 vs. 0.07 ± 0.004). Likewise, the expression of IGFBP4 (P = 0.05) and NANOG (P = 0.03), predictors of embryo quality, were higher in embryos from cows in SP (0.024 ± 0.003; 0.12 ± 0.02, respectively) than in IR (0.016 ± 0.003; 0.07 ± 0.02, respectively). The H3F3A gene (P = 0.02), involved in epigenetic regulation, was more expressed in embryos from cows kept in SP (0.48 ± 0.04 vs. 0.34 ± 0.04). Furthermore, the expression of the SOD2 (P = 0.025), signalling response to stress, was higher in embryos from cows kept in IR (0.17 ± 0.18) than in SP (0.11 ± 0.02). In conclusion, natural shading can modulate gene expression to increase embryo quality of beef cows raised on afforested pasture systems.
This research was supported by FAPESP Grants: 2015/26627-5; 2019/04528-6, and by Alessandro Giro, Messy Pantoja, André Silva, Gustavo dos Santos and Annelise Camplesi.
