Ambient temperature-mediated changes in hepatic gene expression of a mammalian herbivore (Neotoma lepida)

Herbivores regularly ingest natural toxins produced by plants as a defence against herbivory. Recent work suggests that compound toxicity is exacerbated at higher ambient temperatures. This phenomenon, known as temperature-dependent toxicity (TDT), is the likely result of decreased liver function at warmer temperatures; however, the underlying cause of TDT remains speculative. In the present study, we compared the effects of temperature and dietary plant toxins on differential gene expression in the liver of an herbivorous rodent (Neotoma lepida), using species-specific microarrays. Expression profiles revealed a greater number of differentially expressed genes at an ambient temperature below the thermal neutral zone for N. lepida (22°C) compared to one within (27°C). Genes and pathways upregulated at 22°C were related to growth and biosynthesis, whereas those upregulated at 27°C were associated with gluconeogenesis, apoptosis and protein misfolding, suggestive of a stressed state for t...