Project description:Long rough dab (Hippoglossoides platessoides) is an important flatfish fish species in the north Atlantic arctic and sub-arctic marine foodweb that could be vulnerable to contaminant exposure from offshore petroleum related activities. The study was conducted to map transcriptome responses in long rough dab precision cut liver slice (PCLS) culture exposed to benzo[a]pyrene (BaP). BaP is a polyaromatic hydrocarbon (PAH) which is among the most toxic compounds found in crude oil. PCLS culture was performed under 10 µM BaP exposure for 72 h and transcriptome analysis (RNA-seq) analysis was performed to characterize de novo transcriptome of the liver and identify genes responding to BaP exposure.
Project description:Despite the commercial importance of Greenland Halibut (Reinhardtius hippoglossoides), important gaps still persist in our knowledge of this species, including its reproductive biology and sex determination mechanism. Here, we combined single-molecule sequencing of long reads (Pacific Sciences) with chromatin conformation capture sequencing (Hi-C) data to assemble the first chromosome-level reference genome for this species. The high-quality assembly encompassed more than 598 Megabases (Mb) assigned to 1594 scaffolds (scaffold N50 = 25 Mb) with 96% of its total length distributed among 24 chromosomes. Investigation of the syntenic relationship with other economically important flatfish species revealed a high conservation of synteny blocks among members of this phylogenetic clade. Sex determination analysis revealed that similar to other teleost fishes, flatfishes also exhibit a high level of plasticity and turnover in sex determination mechanisms. A low-coverage whole-genome sequence analysis of 198 individuals revealed that Greenland Halibut possesses a male heterogametic XY system and several putative candidate genes implied in the sex determination of this species. Our study also suggests for the first time in flatfishes that a putative Y-autosomal fusion could be associated with a reduction of recombination typical of the early steps of sex chromosome evolution.
