Exploring the molecular basis of adaptive evolution in hydrothermal vent crab Austinograea alayseae by transcriptome analysis

Abstract

Elucidating the genetic mechanisms of adaptation to the hydrothermal vent in organisms at genomic level is significant for understanding the adaptive evolution process in the extreme environment. We performed RNA-seq on four different tissues of a vent crab species, Austinograea alayseae, producing 725,461 unigenes and 134,489 annotated genes. Genes related to sensory, circadian rhythm, hormone, hypoxia stress, metal detoxification and immunity were identified. It was noted that in the degenerated eyestalk, transcription of phototransduction related genes which are important for retinal function was greatly reduced; three crucial neuropeptide hormones, one molt-inhibiting and two crustacean hyperglycemic hormone precursors were characterized with conserved domains; hypoxia-inducible factor 1 and two novel isoforms of metallothioneins in the vent crabs were discovered. An analysis of 6,932 orthologs among three crabs A. alayseae, Portunus trituberculutus and Eriocheir sinensis revealed 19 positive selected genes (PSGs). Most of the PSGs were involved in immune responses, such as crustins and anti-lipopolysaccharide factor, suggesting their function in the adaptation to environment. The characterization of the first vent crab transcriptome provides abundant resources for genetic and evolutionary studies of this species, and paves the way for further investigation of vent adaptation process in crabs.

The complete mitochondrial genomes of two vent squat lobsters, Munidopsis lauensis and M. verrilli: Novel gene arrangements and phylogenetic implications

“…Decapod crustaceans, such as alvinocaridid shrimps, bythograeid crabs, and galatheid squat lobsters, are dominant fauna in the hydrothermal vents, representing approximately 10% of all taxa reported from these vents (Little & Vrijenhoek, ; Martin & Haney, ; Yang et al, ). Recently, the hydrothermal vent bythograeid crabs (Hui, Song, Liu, Li, & Cui, ) and alvinocaridid shrimps (Cottin et al, ; Hui, Cheng, & Sha, ; Wang et al, ; Zhang, Sun, Luan, Lian, & Sun, ) have demonstrated numerous genetic basis for the adaptations to vent habitats. However, little genomic and molecular genetic information are available for hydrothermal vent galatheid squat lobsters, impeding the study for the molecular mechanism in their adaptation process.…”

Evolution of crab eye structures and the utility of ommatidia morphology in resolving phylogeny

“…While a handful of studies have used RNA-seq to characterize the genes expressed within eyes or 870! eyestalks, understanding the visual capabilities of crabs was not the main objective of this research (Hui et al, 2017;Lv et al, 2017;Yingdong et al, 2019). For example, tissue-specific RNA-seq from the eyestalks of Portunus trituberculatus and Eriocheir sinensis identified genes involved in molting and the circadian cycle, respectively.…”

“…A separate study 875! extracted RNA from the vestigial eyes of the hydrothermal vent crab, Austinograea alayseae to investigate genes associated with living in extreme environments (Hui et al, 2017). From the vent crab, evidence was found for all genes involved in the fly phototransduction pathway and two distinct opsin sequences, however the expression levels were low.…”

A review of the brachyuran deep-sea vent community of the western Pacific, with two new species of Austinograea Hessler & Martin, 1989 (Crustacea, Decapoda, Brachyura, Bythograeidae) from the Lau and North Fiji Back-Arc Basins

“…sp., and, in addition, an unnamed species with the chelae as in Fig. 12. Recently, the first transcriptome for a hydrothermal crab was based on two individuals of a vent crab collected from the Manus Basin and identified to A. alayseae (Hui et al 2017), but, as always, illustration of the sequenced specimens was not provided so that the identity of the sequenced brachyuran remains in doubt. A genetic study using mitochondrial DNA and microsatellite markers revealed that populations of the vent-restricted gastropod Ifremeria nautilei from the Manus Basin did not show genetic subdivisions but were genetically distinct from those of the North Fiji and Lau Basins in which populations were undifkey to speCies of AustinogrAeA hessler & martin, 1989 A key to the five species of Austinograea is provided, based on chelae, in order to potentially identify the crabs photographed in situ by evaluating the videos of the dives on board or later by examining the photographs.…”

“…; Hashimoto et al 1989, as bythograeid sp. ;Guinot 1990in Desbruyères & Segonzac 1997Galkin 1997;Tsuchida & Hashimoto 2002;Komai & Segonzac 2004;Martin & Haney 2005;López-González et al 2005;Segonzac 2006;Guinot & Segonzac 2006a, b;Desbruyères et al 2006b;McLay 2007;Shields & Segonzac 2007;Ng et al 2008;Erickson et al 2009;Corbera & Segonzac 2010;Podowski et al 2010;Mateos et al 2012;Kim et al 2013Kim et al , 2014Sen et al 2013Sen et al , 2014Sen et al , 2016Yang et al 2013;Hui et al 2017). Some of these records, however, deserve to be checked.…”