Ultrasonography to assist with timing of spawning in European eel

Jéhannet, Pauline; Heinsbroek, L.T.N.; Palstra, Arjan P.

doi:10.1016/j.theriogenology.2017.06.016

Cited by 5 publications

(3 citation statements)

References 23 publications

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“…We highlight the high number of RBCs in the eels from the stock analyzed, values that were similar to those found by Valiente et al (2008b), compared to those found in the eels' stock analyzed by Callol et al (2015a). These apparently contradictory results are not surprising, given that eels do not reproduce in captivity and that researchers work with wild populations of different origins (Palstra et al, 2005;Mes et al, 2016;Jehannet et al, 2017).…”

Section: Cell Analysissupporting

confidence: 70%

A Transcriptomic Study Reveals That Fish Vibriosis Due to the Zoonotic Pathogen Vibrio vulnificus Is an Acute Inflammatory Disease in Which Erythrocytes May Play an Important Role

et al. 2022

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Vibrio vulnificus is a marine zoonotic pathogen associated with fish farms that is considered a biomarker of climate change. Zoonotic strains trigger a rapid death of their susceptible hosts (fish or humans) by septicemia that has been linked to a cytokine storm in mice. Therefore, we hypothesize that V. vulnificus also causes fish death by triggering a cytokine storm in which red blood cells (RBCs), as nucleated cells in fish, could play an active role. To do it, we used the eel immersion infection model and then analyzed the transcriptome in RBCs, white BCs, and whole blood using an eel-specific microarray platform. Our results demonstrate that V. vulnificus triggers an acute but atypical inflammatory response that occurs in two main phases. The early phase (3 h post-infection [hpi]) is characterized by the upregulation of several genes for proinflammatory cytokines related to the mucosal immune response (il17a/f1 and il20) along with genes for antiviral cytokines (il12β) and antiviral factors (ifna and ifnc). In contrast, the late phase (12 hpi) is based on the upregulation of genes for typical inflammatory cytokines (il1β), endothelial destruction (mmp9 and hyal2), and, interestingly, genes related to an RNA-based immune response (sidt1). Functional assays revealed significant proteolytic and hemolytic activity in serum at 12 hpi that would explain the hemorrhages characteristic of this septicemia in fish. As expected, we found evidence that RBCs are transcriptionally active and contribute to this atypical immune response, especially in the short term. Based on a selected set of marker genes, we propose here an in vivo RT-qPCR assay that allows detection of early sepsis caused by V. vulnificus. Finally, we develop a model of sepsis that could serve as a basis for understanding sepsis caused by V. vulnificus not only in fish but also in humans.

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Section: Cell Analysissupporting

confidence: 70%

A Transcriptomic Study Reveals That Fish Vibriosis Due to the Zoonotic Pathogen Vibrio vulnificus Is an Acute Inflammatory Disease in Which Erythrocytes May Play an Important Role

et al. 2022

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“…From these eels, and from an additional N = 5 eels per treatment group, GSI was determined non-invasively by ultrasonography using a compact and portable system (MyLabFive™Vet with a LA435 probe, Esaote, Genoa, Italy; Jehannet et al, 2017 ). GSI was calculated following Bureau du Colombier et al (2015) :

…”

Section: Methodsmentioning

confidence: 99%

Steroid implants for the induction of vitellogenesis in feminized European silver eels (Anguilla anguilla L.)

et al. 2022

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Assisted propagation of the European eel will lead to a closed production cycle supplying the aquaculture industry with juvenile glass eels. Females require long-term weekly treatment with pituitary extract (PE), which is stressful and causes abnormalities in oogenesis. We tested the effects of 17α-methyltestosterone (17 MT), as potent androgen activating the androgen receptor, and 17β-estradiol (E2), as an inducer of vitellogenesis, to shorten the duration of PE treatment.Four groups of feminized eels were subjected to a simulated migration and subsequent injection with implants containing 17 MT (17 MT-group), E2 (E2-group) or 17 MT plus E2 (17 MT + E2-group) to test for synergistic effects, or without any steroids as controls (C-group). The effects of a 2-months treatment were investigated by determining the eye index (EI), hepatosomatic and gonadosomatic index (HSI and GSI, respectively), plasma steroid concentrations by liquid chromatography mass spectrometry (LCMS), gonadal histology, expression of androgen receptors a and b (ara, arb); estrogen receptor 1 (esr1); FSH receptor (fshr); vitellogenin receptor (vtgr) and aromatase (cyp19), and the required number of weekly PE injections to fully mature. For many parameters, both the 17 MT and E2 groups showed an increase vs. controls, with the 17 MT + E2 group showing a synergistic effect, as seen for EI, GSI (3.4 for 17 MT and for E2, 6.6 for 17 MT + E2), oocyte diameter and ara, arb and esr1 expression. Concentrations of almost all focal steroids decreased with simulated migration and steroid treatment. Only eels of the 17 MT-group showed increased expression of cyp19 and of fshr, while fshr expression increased 44-fold in the 17 MT + E2 group, highlighting that co-implantation is most effective in raising fshr mRNA levels. Specific for eels of the E2 groups were vitellogenesis-associated changes such as an increase of HSI, plasma E2, and presence of yolk in the oocytes. Steroid treatments reduced the duration of PE treatment, again synergistically for co-implantation. In conclusion, E2 is necessary to start vitellogenesis, but 17 MT has specific effects on cyp19 and fshr expression. The combination is necessary for synergistic effects and as such, steroid implants could be applied in assisted reproduction protocols for European eel to improve oocyte quality leading to the production of more vital larvae.

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“…European male eels were first matured by injection of urine from pregnant women ( [1]; containing human chorionic gonadotropin-hCG), females by hypophysation (i.e., weekly injection of pituitary extracts) in the 1960s [2], and eggs were first fertilized in 1980 [3], after which the first larvae were produced in the early 1980s [4]. Although several groups can now produce larvae of European eel on a regular basis [5][6][7][8], massive mortality often occurs [9,10], particularly during the first week after hatching. Survival rates during the first week vary widely from 0 to 90% in European eels [10].…”

Section: Introductionmentioning

confidence: 99%

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

Jéhannet

Palstra

Heinsbroek³

et al. 2021

Animals

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In eels, large variations in larval mortality exist, which would impede the viable production of juvenile glass eels in captivity. The transcriptome of European eel larvae was investigated to identify physiological pathways and genes that show differential regulation between non-viable vs. viable larvae. Expression of genes involved in inflammation and host protection was higher, suggesting that non-viable larvae suffered from microbial infection. Expression of genes involved in osmoregulation was also higher, implying that non-viable larvae tried to maintain homeostasis by strong osmoregulatory adaptation. Expression of genes involved in myogenesis, neural, and sensory development was reduced in the non-viable larvae. Expression of the major histocompatibility complex class-I (mhc1) gene, M-protein (myom2), the dopamine 2B receptor (d2br), the melatonin receptor (mtr1), and heat-shock protein beta-1 (hspb1) showed strong differential regulation and was therefore studied in 1, 8, and 15 days post-hatch (dph) larvae by RT-PCR to comprehend the roles of these genes during ontogeny. Expression patterning of these genes indicated the start of active swimming (8 dph) and feed searching behavior (15 dph) and confirmed immunocompetence immediately after hatching. This study revealed useful insights for improving larval survival by microbial control and salinity reduction.

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Ultrasonography to assist with timing of spawning in European eel

Cited by 5 publications

References 23 publications

A Transcriptomic Study Reveals That Fish Vibriosis Due to the Zoonotic Pathogen Vibrio vulnificus Is an Acute Inflammatory Disease in Which Erythrocytes May Play an Important Role

A Transcriptomic Study Reveals That Fish Vibriosis Due to the Zoonotic Pathogen Vibrio vulnificus Is an Acute Inflammatory Disease in Which Erythrocytes May Play an Important Role

Steroid implants for the induction of vitellogenesis in feminized European silver eels (Anguilla anguilla L.)

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

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