title: Transcriptomic profiling of differential responses to drought in two freshwater mussel species, the giant floater Pyganodon grandis and the pondhorn Uniomerus tetralasmus.
abstract: The southeastern US has experienced recurrent drought during recent decades. Increasing demand for water, as precipitation decreases, exacerbates stress on the aquatic biota of the Southeast: a global hotspot for freshwater mussel, crayfish, and fish diversity. Freshwater unionid mussels are ideal candidates to study linkages between ecophysiological and behavioral responses to drought. Previous work on co-occurring mussel species suggests a coupling of physiology and behavior along a gradient ranging from intolerant species such as Pyganodon grandis (giant floater) that track receding waters and rarely burrow in the substrates to tolerant species such as Uniomerus tetralasmus (pondhorn) that rarely track receding waters, but readily burrow into the drying sediments. We utilized a next-generation sequencing-based RNA-Seq approach to examine heat/desiccation-induced transcriptomic profiles of these two species in order to identify linkages between patterns of gene expression, physiology and behavior. Sequencing produced over 425 million 100 bp reads. Using the de novo assembly package Trinity, we assembled the short reads into 321,250 contigs from giant floater (average length 835 bp) and 385,735 contigs from pondhorn (average length 929 bp). BLAST-based annotation and gene expression analysis revealed 2,832 differentially expressed genes in giant floater and 2,758 differentially expressed genes in pondhorn. Trancriptomic responses included changes in molecular chaperones, oxidative stress profiles, cell cycling, energy metabolism, immunity, and cytoskeletal rearrangements. Comparative analyses between species indicated significantly higher induction of molecular chaperones and cytoskeletal elements in the intolerant P. grandis as well as important differences in genes regulating apoptosis and immunity.
authors.affiliation: School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, United States of America ; Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Agriculture, Shanghai, People's Republic of China.
authors.forename: Yupeng
authors.initials: Y
authors.lastname: Luo
authors.affiliation: School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, United States of America.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: Georgia Department of Natural Resources, Wildlife Resources Division, Nongame Conservation Section, Social Circle, Georgia, United States of America.
authors.forename: Andrew Gascho
authors.initials: AG
authors.lastname: Landis
authors.affiliation: Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Agriculture, Shanghai, People's Republic of China.
authors.forename: Guiling
authors.initials: G
authors.lastname: Wang
authors.affiliation: School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Stoeckel
authors.affiliation: School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, Alabama, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Peatman
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics; D003599:Cytoskeleton / Q000235:genetics; D004734:Energy Metabolism / Q000235:genetics; D005618:Fresh Water; D015870:Gene Expression / Q000235:genetics*; D020869:Gene Expression Profiling; D018832:Molecular Chaperones / Q000235:genetics; D018384:Oxidative Stress / Q000235:genetics; D059467:Transcriptome / Q000235:genetics*
chemical_list: D018832:Molecular Chaperones