Abstract
Heat-shock proteins (HSPs) are a prominent family of cellular chaperones that are involved in the folding, assembly and degradation of cellular proteins, cell-cycling and signal transduction. HSPs are high conserved across taxa and form a key component of the stress response with signatures of molecular adaptation in some species exposed to extreme environmental stressors such as dehydration, heavy metal pollutants and arctic temperatures. Here we characterise two key heat-shock protein genes (hsp70 and hsp90) in deep-sea Lysianassoidea amphipods, with a focus on copy number variation and signatures of selection on the DNA sequences. Four phylogenetically distinct isoforms were resolved for both hsp70 and hsp90, with one isoform in each gene being exclusive to the hadal genus Hirondellea. Signatures of purifying selection were shown across hsp70 and hsp90 from dN:dS ratios. The GC content of each gene was lower, and the number of codons used was higher, than in shallow water amphipods suggesting a relaxation in codon usage bias. Such observations suggest that increased hydrostatic pressure is an important environmental stress that shapes the adaptation of heat-shock protein genes in deep-sea amphipods.
Original language | English |
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Pages (from-to) | 61-69 |
Number of pages | 9 |
Journal | Deep Sea Research Part II: Topical Studies in Oceanography |
Volume | 155 |
Early online date | 3 May 2018 |
DOIs | |
Publication status | Published - Sept 2018 |
Bibliographical note
We thank the chief scientists, crew and company of the Japanese RV Hakuho-Maru (KH0703 and KH0803), the RV Tansei-Maru (KT-09-03), the RV Kairei (KR0716), the German FS Sonne (SO197 and SO 209) and the New Zealand RV Kaharoa (KAH0190, KAH1109, KAH1202, KAH1301 and KAH1310). This work was supported by the HADEEP projects, funded by the Nippon Foundation, Japan (2009765188), the Natural Environmental Research Council, UK (NE/E007171/1) and the Total Foundation, France. We acknowledge additional support from the Marine Alliance for Science and Technology for Scotland (MASTS) funded by the Scottish Funding Council (Refs: HR09011 and DSSG14), the Natural Environment Research Council (NE/N01149X/1), the Leverhulme Trust, and contributing institutions. Additional sea time was supported by NIWA's ‘Impact of Resource Use on Vulnerable Deep-Sea Communities’ project (CO1_0906). From NIWA we thank Malcolm Clark, Ashley Rowden, Kareen Schnabel, and Sadie Mills for logistical support at the NIWA Invertebrate Collection. We also thank Dr. Niamh Kilgallen for identifying the majority of the amphipod samples and Dr. Tammy Horton (NOCS, UK) for identifying some of the earlier amphipod samples.Keywords
- Adaptation
- Deep sea
- Evolution
- Heat-shock proteins
- Lysianassoidea amphipods