Estado da arte dos estudos de expressão gênica em ruminantes sob estresse térmico

Abstract

Changes in temperature beyond the thermoneutral zone affect ruminants, which can cause behavioral, physiological, and reproductive changes. The effect of the environment can alter the expression of some genes. Identifying these genes makes it possible to compile information to build a database for studies of genetic alterations aiming at the genetic improvement of animals, to obtain adaptive varieties, to improve thermotolerance. In this sense, this work aimed to conduct a scientometric review to characterize the state of the art and identify hotspots, research fronts and relevant relationships about heat stress and gene expression in ruminants. The articles selected for review were compiled in the Web of Science database and analyzed using CiteSpace and Excel softwares. The selected publications formed a dataset containing 272 articles, H-index of 35 and showed an increase of publications starting in 2006, demonstrating how recent molecular studies in heatstressed ruminants are. The countries with the highest frequency of publications are also those with the largest herds and cattle production, such as India, United States, China and Brazil. Keyword analysis revealed that the most relevant hotspot is gene expression, followed by heat stress and dairy cows. The citation explosion analysis revealed that there may be a change of trend in gene expression studies in heat stressed ruminants. The influence of temperature in the dry period is the main research front, with the bovine species and the HSP70 gene being the most studied. There is a need for further studies to understand the molecular responses of the organism under heat stress and to identify genes that allow gene changes in order to improve adaptation to temperature changes.