What Goes Wrong during Early Development of Artificially Reproduced European Eel Anguilla anguilla? Clues from the Larval Transcriptome and Gene Expression Patterns

Jéhannet, Pauline; Palstra, Arjan P.; Heinsbroek, L.T.N.; Kruijt, L.; Dirks, Ron P.; Swinkels, William; Komen, Hans

doi:10.3390/ani11061710

Cited by 12 publications

(5 citation statements)

References 118 publications

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“…Eticlopride was expected to lift the dopaminergic inhibition of gonadotropin production and release but did not show any additional effect on sexual maturation to simulated migration. (E) eel larvae at 1-, 8-and 15-days post hatching (source: Jéhannet et al, 2021); (F) eel larva at 15 days post hatching ready to initiate exogenous feeding.…”

Section: Resultsmentioning

confidence: 99%

488. Five years of optimizing the assisted reproduction protocol for European eel: what worked and what didn’t?

Palstra

Jéhannet

Heinsbroek³

et al. 2022

Proceedings of 12th World Congress on Genetics Applied to Livestock Production (WCGALP)

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The production cycle of the European eel needs to be closed in order to supply aquaculture with juvenile glass eels and to alleviate fishery pressure on the natural population, thereby contributing to its recovery. Currently, we are able to produce larvae batches three times per week. Over the past five years we have executed experiments aiming to condition glass eels into high quality brood stock females and optimize the artificial reproduction protocol. Feminization of young juveniles contributes to shortening the generation time at least 5-fold. Simulated migration induces early sexual maturation. Steroid implants containing 17 methyltestosterone (17MT) and 17β estradiol (E2) induce the more advanced maturation stages and shorten the stressful period of weekly carp pituitary extract (CPE) injections to fully mature females. Instead of using CPE, stable eel-specific recombinant gonadotropins have been successfully applied to produce eel larvae.

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Section: Resultsmentioning

confidence: 99%

488. Five years of optimizing the assisted reproduction protocol for European eel: what worked and what didn’t?

Palstra

Jéhannet

Heinsbroek³

et al. 2022

Proceedings of 12th World Congress on Genetics Applied to Livestock Production (WCGALP)

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“…Gene expression analysis was performed as previously described ( Jéhannet et al, 2021 ). Diluted complementary DNA was mixed with SensiFAST™ SYBR ® Lo-ROX Ki (Bioline, London, United Kingdom) and the primer set of the target gene ( Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

The induction of oocyte maturation and ovulation in the European eel (Anguilla anguilla): in vitro and in vivo comparison of progesterone with 17α,20β-dihydroxy-4-pregnen-3-one

et al. 2023

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Ovulation in European eel is induced by injection of 17α,20β-dihydroxy-4-pregnen-3-one (DHP) as the maturation-inducing hormone (MIH). Female eels need to ovulate within 18 h after injection to release good quality eggs. Progesterone (P), as an upstream precursor of DHP, may promote endogenous DHP production and improve egg quality. The purpose of this study was therefore to compare treatment of P with DHP on batch level, in vitro, to determine dose-response effects, and in vivo, at a single dose. For the in vitro experiment, ovarian tissue was extracted and placed in culture plates containing hormone-free medium and media supplemented with the treatment: DHP at 1, 10 and 100 ng mL−1, or P at 10, 100 and 1,000 ng mL−1. At the start of incubation, the folliculated oocytes were sampled for histology, microscopy and qPCR. After incubation for 12 and 18 h, the oocytes were sampled for microscopy and qPCR analysis. For the in vivo experiment, females were either injected with DHP or P at a dose of 2 mg kg−1 to assess their effects on ovulation and reproductive success. At the moment of release, eggs were sampled for RNA sequencing to compare effects of DHP and P on the expression of genes involved in egg quality aspects. Remaining eggs were fertilized and larval viability was recorded. Both DHP and P were able to induce GVBD (DHP at 10 and 100 ng mL−1, P at 100 and 1,000 ng mL−1) in vitro. Expression of genes involved in oocyte maturation and ovulation was similar in vitro for both DHP and P treatments. Regarding the in vivo results, RNAseq results reflected similar DHP and P effects on the expression of genes involved in egg quality aspects. Females injected with either DHP or P ovulated, released eggs, and were equally able to produce larvae without any differences in reproductive success. Our results support the conclusion that DHP and P work equally well in vitro and in vivo. P is more attractive to apply as the price is 3,000 times lower than the price of DHP.

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“…Concerning embryonic development, in recent years the technology and incubation methods to produce European eel larvae have advanced considerably, allowing the production of large batches of viable eggs and larvae that reach the first feeding stage [43][44][45] despite the early development stages being sensitive to biophysical parameters [46,47]. Although it was not one of the objectives of our project, some of the females that achieved maturation and developed the oocytes in the required stage were induced to final ovulation.…”

Section: Femalesmentioning

confidence: 99%

Using Osmotic Pumps to Induce the Production of Gametes in Male and Female European Eels

Blanes-García

García-Salinas

Morini

et al. 2022

Animals

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The European eel (Anguilla anguilla) is a commercially valued species for aquaculture. Over the past decades, it has experienced a drastic reduction in its natural stocks. Thus, breeding in captivity is considered essential, nowadays, to guarantee the eel aquaculture and to reduce pressure on natural populations. Traditionally, the European eel has been sexually matured by means of weekly hormonal injections, which cause stress to the fish. The purpose of this research study was to assess the use of osmotic pumps as a new method to induce sexual maturation in male and female European eels, without the weekly injection. The control groups were treated with weekly hormone injections (recombinant human chorionic gonadotropin for males and carp pituitary extract for females), and the implanted groups were treated with osmotic pumps (ALZET® osmotic pumps) loaded with the respective hormones. Regarding male European eels, this study shows that the use of controlled release systems was able to induce the maturation and spermiation, but without the necessary capacity to produce enough gametes with acceptable quality parameters that could meet the needs of a commercial eel hatchery. Concerning female European eels, the study demonstrates that the use of osmotic pumps loaded with CPE became an effective method, generating early maturations (4 to 10 weeks) in 50% of the females, so this method could become a viable alternative for eel hatchery procedures.

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What Goes Wrong during Early Development of Artificially Reproduced European Eel Anguilla anguilla? Clues from the Larval Transcriptome and Gene Expression Patterns

Cited by 12 publications

References 118 publications

488. Five years of optimizing the assisted reproduction protocol for European eel: what worked and what didn’t?

488. Five years of optimizing the assisted reproduction protocol for European eel: what worked and what didn’t?

The induction of oocyte maturation and ovulation in the European eel (Anguilla anguilla): in vitro and in vivo comparison of progesterone with 17α,20β-dihydroxy-4-pregnen-3-one

Using Osmotic Pumps to Induce the Production of Gametes in Male and Female European Eels

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