Meeting Abstract
Mitochondria are a critical component of an animal’s response to environmental stressors such as temperature, as they are the primary site of aerobic energy production. Mitochondrial uncoupling proteins (UCPs) are known to be involved in temperature responses in mammals, for example by helping to generate heat in mammalian brown adipose tissue upon cold exposure. UCPs are also present in ectotherms but their functional role in these animals is not well understood. Here we use Atlantic killifish, Fundulus heteroclitus, as a model organism in which to address the role of UCPs in thermal acclimation and adaptation in ectotherms. Atlantic killifish are broadly eurythermal and display extensive phenotypic plasticity in response to thermal acclimation. In addition, there are geographically separated subspecies that differ in their thermal biology, making this an ideal system in which to investigate mechanisms of acclimation and adaptation to temperature. To characterize UCPs in killifish, the gene sequences and tissue-specific expression of members of the UCP family (UCP1, UCP2, UCP3, UCP3-like and UCP5) were determined. In general, the tissue-specific expression of these genes was similar to those reported in other fish species. Most isoforms differed in mRNA expression levels between subspecies, but not with thermal acclimation. However, the fish-specific isoform, UCP3-like, that is primarily expressed in gill tissue, was not responsive to thermal acclimation in the northern subspecies, but in the southern subspecies, mRNA expression declined with increasing temperatures. The functional consequences of this change in gene expression plasticity between the subspecies are currently being investigated.
