Transcriptomic Changes during Previtellogenic and Vitellogenic Stages of Ovarian Development in Wreckfish (Hāpuku), Polyprion oxygeneios (Perciformes)

Abstract

‘Wreckfish’ a collective of species belonging to the family Polyprionidae, are an important commercial fishery and have significant aquaculture potential. Until now, genomic or transcriptomic information for any species within the genus Polyprion has either remained unpublished or is non-existent. Using Illumina HiSeq, we compared the transcriptomes of hāpuku (Polyprion oxygeneios) ovaries to explore developmental stage-specific variations underlying their reproductive physiology. We sought to identify differentially expressed genes and the associated shifts in biological pathways between previtellogenic and early vitellogenic ovaries. Ovarian tissue was repeatedly biopsied by gonopore cannulation from the same females (n = 3) throughout oogenesis. Reproductive status of initial biopsies was confirmed as being previtellogenic and that in biopsies collected eight weeks later as early vitellogenic. A de novo hāpuku transcriptome was assembled (146,189 transcripts) from RNA-Seq data without a reference genome. On average, each tissue sample contained 17.5 million trimmed reads. Gene annotation was 80% when using BLASTX against Genbank Non Redundant database. Fifty-three transcripts were differentially expressed within the FDR of 0.05 when previtellogenic and early vitellogenic ovaries were compared; this reduced to 35 differentially expressed genes when transcript duplications were pooled. Among these were genes tentatively associated with the electron transport chain, lipid metabolism, steroidogenesis and mineral/solute transportation. These data provide a snap-shot into stage-specific physiological events during oogenesis in the ovary of a teleost and an extensive molecular resource for research on species in the Genus Polyprion.

Comparative transcriptomic analysis of gonadal development and renewal in the ovoviviparous black rockfish (Sebastes schlegelii)

“…Members of the slc6 gene family ( slc6a11 , slc6a15 , slc6a6 , and slc6a8 ), which perform Na + - and Cl − -dependent transport of the neurotransmitter γ-aminobutyric acid (GABA), creatine and taurine, were differentially expressed during ovarian development. The result was coincident with the transcriptomic analysis of hapuku ( Polyprion oxygeneio s) [ 75 ]. However, these transport proteins are more commonly studied in the central nervous system of vertebrates [ 76 ], which implies that SLCs may also function in the ovary.…”

Comparative Transcriptomic Analysis of Gonad Development and Renewal of Ovoviviparous Black Rockfish (Sebastes Schlegelii)

“…which performs Na + and Cl − dependent neurotransmitter transport for γ-aminobutyric acid (GABA), creatine and taurine were differentially expressed along ovary development. The result was coincident with the transcriptomic analysis of hapuku (Polyprion oxygeneios) (77) . However, these transport proteins were more commonly mentioned in central nervous system of vertebrates (78) , which imply the SLCs may also functional in ovary.…”

Transcriptome analysis of flathead grey mullet (Mugil cephalus) ovarian development induced by recombinant gonadotropin hormones

“…However, a noteworthy aspect of the transition from previtellogenesis to early-to-mid-vitellogenesis was the cytochrome complex (GO:0070069) enrichment from downregulated genes. Contrarily to other species, in which mRNA levels of genes involved in mitochondrial respiration and oxidative phosphorylation were upregulated in early-vitellogenesis respect to previtellogenesis ( Lokman et al, 2003 ; Martyniuk et al, 2013 ; Wylie et al, 2019 ), in the present study cytochrome c ( cycs ) and b ( cycb ) transcripts were downregulated. However, a high expression of cytochrome c was still present together with an upregulated expression of some cox genes, and thus, the proton gradient required for ATP production might have been present.…”