Teleost embryos utilise conserved zinc-binding astacin proteinases for the chemical modification of the glycoproteins composing the zona radiata. European eels, an evolutionary basal catadromous species, have multiple isozymes with similar catalytic functions for this task. Researchers are focusing on developing effective rearing practices for this critically endangered species as assisted reproduction efforts are currently obtaining variable embryonal hatching and survival. Thus, the objective was to investigate whether the variant hatching rate could be due to lacking high choriolytic enzyme 1-like, eel hatching enzyme expression and/or it's collagenase-like activity, while examining also the regulatory intercellular Zn2+ concentrations in developing embryos after fertilisation and pre-hatching. Six assisted reproduction was conducted for the collection of buoyant (vital) and sunk (non-vital) fertilised embryo pools two hours post-spawning (t0) and pre-hatching (t55). Real-time PCR was used together with Collagen degradation fluorometric assay, and Inductively Coupled Plasma-Optical Emission Spectrometry to investigate the intracellular Zn2+ concentrations. Transcripts of the eel hatching enzyme were detected in all sample pools with significant difference between vital and non-vital embryos even 2 h post-fertilisation, suggesting maternal derivation, or the onset of hatching enzyme expression before the known maternal-to-zygotic transition. Relative mRNA quantity depended on all factors (time, state, interaction) demonstrating an overall increase of expression. The collagenase-like activity was only time-dependent, and only non-vital samples contained higher intracellular Zn2+ concentrations than 0.6 mg kg−1, suggesting a similar threshold as for other species. Correlation analysis revealed reverse correlations between Zn2+ concentration and the weight of the reproductive female at ovulation.
Hausz, B.L., Casalini, A., Ventrella, D., Bertocchi, M., Zannoni, A., Govoni, N., et al. (2026). The role of hatching enzyme in European eel (Anguilla anguilla): Transcriptomic and enzymatic analysis after fertilisation and before hatching. AQUACULTURE, 623, 744194-744194 [10.1016/j.aquaculture.2026.744194].
The role of hatching enzyme in European eel (Anguilla anguilla): Transcriptomic and enzymatic analysis after fertilisation and before hatching
Hausz, Bálint Lóránt;Casalini, Antonio;Ventrella, Domenico;Bertocchi, Martina;Zannoni, Augusta;Govoni, Nadia;Gentile, Laura;Zaccaroni, Annalisa;Mordenti, Oliviero;Parmeggiani, Albamaria;Bacci, Maria Laura;Elmi, Alberto
2026
Abstract
Teleost embryos utilise conserved zinc-binding astacin proteinases for the chemical modification of the glycoproteins composing the zona radiata. European eels, an evolutionary basal catadromous species, have multiple isozymes with similar catalytic functions for this task. Researchers are focusing on developing effective rearing practices for this critically endangered species as assisted reproduction efforts are currently obtaining variable embryonal hatching and survival. Thus, the objective was to investigate whether the variant hatching rate could be due to lacking high choriolytic enzyme 1-like, eel hatching enzyme expression and/or it's collagenase-like activity, while examining also the regulatory intercellular Zn2+ concentrations in developing embryos after fertilisation and pre-hatching. Six assisted reproduction was conducted for the collection of buoyant (vital) and sunk (non-vital) fertilised embryo pools two hours post-spawning (t0) and pre-hatching (t55). Real-time PCR was used together with Collagen degradation fluorometric assay, and Inductively Coupled Plasma-Optical Emission Spectrometry to investigate the intracellular Zn2+ concentrations. Transcripts of the eel hatching enzyme were detected in all sample pools with significant difference between vital and non-vital embryos even 2 h post-fertilisation, suggesting maternal derivation, or the onset of hatching enzyme expression before the known maternal-to-zygotic transition. Relative mRNA quantity depended on all factors (time, state, interaction) demonstrating an overall increase of expression. The collagenase-like activity was only time-dependent, and only non-vital samples contained higher intracellular Zn2+ concentrations than 0.6 mg kg−1, suggesting a similar threshold as for other species. Correlation analysis revealed reverse correlations between Zn2+ concentration and the weight of the reproductive female at ovulation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
