Identification of heat stress responsive transcripts in Sprague-Dawley rats using mixed linear models

Investigators: Kotlarz K., Mielczarek M., Suchocki T., Dou J., Wang Y., Szyda J.


Heat stress is an increasingly serious problem in livestock production, not only due to the rise of global warming but also because of constantly increasing metabolic load, especially for high-productive animals. In this study, we used the Norwegian rat (Rattus norvegicus) as a model organism for a genome-wide scan of the transcriptional expression alterations induced by heat stress.

Material and methods:

In the experiment, 5 rats were used in the control and the heat-stressed groups to investigate the transcriptomic regulation profiles. The RNA was isolated from the liver and adrenal gland from the control and heat-stressed group.

By applying different models, we considered four sources of variation in transcript expression, comprising transcripts (1), genes (2), Gene Ontology terms (3), and Reactome pathways (4) and focussed on accounting for the similarity within each source, which was expressed as a covariance matrix. Models based on transcripts or genes levels explained a larger proportion of log2 fold change than models fitting the functional components of Gene Ontology terms or Reactome pathways.


Since global temperature is expected to rise by 2°C in 2050, heat stress may become the most serious environmental factor. Individuals cope with heat stress by:

  • increasing body temperature,
  • reducing feed intake,
  • as well as changing of physiological state.

In animal production, heat stress is among the best characterized environmental stressors and it can lead to economic losses and increased health burdens.