Meeting Abstract
P3.206 Sunday, Jan. 6 Gene expression biomarkers of acute and chronic heat stress in a reef-building coral KENKEL, CD*; MATZ, MV; PARTICIPANTS OF THE 2010 AND 2011 GENE EXPRESSION BIOMARKERS WORKSHOPS, ; Univ. of Texas at Austin; Univ. of Texas at Austin carly.kenkel@gmail.com
Coral reefs are declining worldwide due to increased incidence of coral bleaching, which will have widespread biodiversity and economic impacts. While the environmental conditions that promote bleaching are known, how climate information relates to the actual stress experienced by corals at any particular reef site is not well understood. Gene expression analysis based on quantitative PCR (qPCR) can be used as a diagnostic tool to determine coral condition in situ, providing means of linking physiology with putative environmental stress. First, we performed a graded heat-stress experiment to assess the sensitivity of our previously published acute stress markers in the mustard hill coral, Porites astreoides. Four candidates showed correspondingly graded expression, as well as the simplified double-gene assay, which relies on the non-normalized expression values of only two genes, Hsp16 and Actin. However, when these acute stress candidates were tested in response to a natural bleaching event, no expression differences between bleached and non-bleached individuals were observed. A second experiment subsequently exposed P. astreoides fragments to chronic heat stress (six weeks under elevated temperature), which did induce bleaching responses. A subset of these bleached individuals were used in an RNAseq analysis to identify chronic stress candidates. Nine candidate genes were validated in the remaining experimental individuals using qPCR. Two of them showed significant (adjusted, p<0.05) down-regulation under stress, a carbonic anhydrase and an anion transporter, while two more showed noticeable trends (adjusted p<0.1). The anion transporter demonstrated a particularly large dynamic range, with down-regulation of 26-fold, rendering it a viable marker of chronic heat stress.
