Cathepsin B & D and the Survival of Early Embryos in Red Spotted Grouper, Ephinephelus akaara

Abstract

Survival of embryos largely depends on yolk processing during early development. Proteolytic enzymes, cathepsin B & D (ctsb & ctsd) are known to have some important roles in yolk processing of various fish species. Mature female red spotted groupers were injected with human chorionic gonadotropin (HCG) to induce ovulation. The fertilized eggs and embryos were sampled at 0, 4 and 24 HPF (hours post fertilization). Survivals of each groups of embryos were checked at 24 and 48 HPH (hours post hatching). Transcripts of ctsb & ctsd showed the highest level at 0 HPF and relatively high at 4 HPF, but greatly decreased at 24 HPF. In bad egg quality group (BE, embryos survived until 24 HPH), transcript level of ctsb at 4 HPF were significantly lower than the transcript level at the same stage in good egg quality group (GE, embryos survived until 48 HPH) while no significant change of ctsb transcript level was observed at 0 or 24 HPF between BE and GE. Transcript level of ctsd was decreased at 24 HPF, but the difference was not as strong as the case of ctsb transcript. These results suggest that maternal ctsb transcript rather than ctsd transcript is likely to be involved in egg quality resulting in the difference of survival rate of embryos at early developmental period in this species.

Domestication modulates the expression of genes involved in neurogenesis in high‐quality eggs of Sander lucioperca

“…In Atlantic cod, cathepsin A ( ctsa ) was found to be overexpressed in the embryos of the domesticated population (Lanes et al, 2013). In finfishes, cathepsins were reported to be involved in the processing of yolk proteins during oogenesis and FOM (Fabra & Cerdà, 2004) and were found to be correlated with the egg quality in several teleosts (Carnevali et al, 2001; Gwon, Kim, Baek, Lee, & Kwon, 2017), including percids (Kestemont, Cooremans, Abi‐Ayad, & Mélard, 1999). For instance, in rainbow trout, ctsz was overexpressed in low‐quality egg (Aegerter, Jalabert, & Bobe, 2005), suggesting that it is an egg‐quality‐associated marker.…”

Oogenesis and Egg Quality in Finfish: Yolk Formation and Other Factors Influencing Female Fertility

“…Dysfunctional cathepsin D and L levels in ovulated eggs and recently fertilized embryos are related to low fertility in seabream [38]. Low levels of cathepsin D and cathepsin B expression in recently fertilized red spotted grouper (Ephinephelus akaara) embryos (0-24 h post-fertilization) also are associated with poor egg quality [39], further suggesting that proper processing of vitellogenin derived yolk proteins is a critical step during vitellogenesis and ovarian maturation and may lead to reproductive failure if disrupted.…”

Expression of Yolk Processing Enzyme Genes in Fertilized Eggs from Artificially Matured Female Eel, Anguilla japonica

“…2D ). In support of this result, the level of ctsb has been suggested to be a criterion for egg quality in yellowtail kingfish and red spotted grouper ( Gwon et al, 2017 ; Palomino et al, 2017 ). However, they focused on the difference between developmental stages while, in this study, we have looked into differences between egg groups with different fertilization rate.…”