Meeting Abstract

P2.109  Wednesday, Jan. 5  Impacts of hypoxia and hypercapnic hypoxia on the transcription of key antioxidants and protein synthesis genes in the shrimp Litopeaneaus vannamei. DARLING, C.L.*; SHARP, N.J.; BURNETT, K.G.; BURNETT, L.E.; College of Charleston; College of Charleston; College of Charleston; College of Charleston darlingcl@gmail.com

The Pacific whiteleg shrimp,Litopenaeus vannamei, inhabits coastal estuarine waters which are prone to intermittent bouts of low oxygen (hypoxia) and high carbon dioxide (hypercapnia). Hypoxia (H) and hypercapnic hypoxia (HH) can cause oxidative stress and induce the production of reactive oxygen species (ROS). Antioxidants function in scavenging ROS to reduce cell damage and while detrimental to cells, ROS play an important role in crustacean immunity. Previous studies also provide evidence of decreased protein synthesis after prolonged exposure to H. In the current study we exposed shrimp to H (PO₂ = 4.0 kPa, PCO₂ < 0.06 kPa, pH = 7.8-8.0) or HH (PO₂ = 4.0 kPa, PCO₂ = 1.8 kPa, pH = 6.8-6.9) for 4 or 24 h to identify changes in the transcription of genes encoding two antioxidants, superoxide dismutase and thioredoxin-2 (TRX-2), and three enzymes involved in glutathione production, cystathione beta-synthase (CBS), betaine-homocysteine methyltransferase and glutathione s-transferase. We also assessed transcripts of asparaginyl tRNA synthetase (AsnRS) and elongation initiation factor 2α (eIF-2α) to evaluate possible impacts of H and HH on protein synthesis. Optimized qRT-PCR assays for TRX-2,CBS, AsnRS, and eIF2α (efficiencies=101.4–109.7, R²=97.4–99.2%) show that TRX-2 transcripts increased 2.7-fold in H 4 h, while CBS transcripts increased 2.8-fold after HH 24 h. AsnRS and eIF2α were significantly downregulated after HH 24 h (-5.5, -3.6 fold, respectively). These responses are consistent with a temporally dynamic transcriptional response to oxidative stress, and correspond with reports of decreased protein synthesis after sustained (24 h) oxidative stress. (NSF IOS-0725245).