Providing recombinant gonadotropin-based therapies that induce oogenesis from previtellogenic oocytes to produce viable larvae in a teleost, the flathead grey mullet (Mugil cephalus)

Recombinant Fsh and Lh therapy for spawning induction of previtellogenic and early spermatogenic arrested teleost, the flathead grey mullet (Mugil cephalus)

“…Nevertheless, in the present study, the ovaries of the early-vitellogenic females at the beginning of the experiment had few vitellogenic oocytes that were not distributed homogeneously and actually previtellogenic oocytes were the most abundant stage of development in all females. The females that received the rFsh and rLh treatment, as previously described by Ramos-Júdez et al (2021), showed a uniform clutch of abundant oocytes recruited into vitellogenesis and followed the typical ovarian development in this species. Mugil cephalus has group synchronous ovary development with one clutch of oocytes maturing annually following a single spawning episode (Kumar et al, 2015).…”

“…Higher quantities of fluent milt were obtained (0.25 to 2.89 mL) in the present study compared to Ramos-Júdez et al (2021) (max ~ 0.25 mL). The increased sperm production may be due to the different pattern and dosage of rGths administration, which included a longer period and higher doses for rLh.…”

“…Regarding egg quality of fertilised eggs incubated in 96 well plates, 96 ± 3% of fertilized eggs developed embryos and hatched indicating a high egg quality. Moreover, larvae survived as long as 13 days at 21ºC without exogenous feeding which is considered a great improvement compared to the previous study by Ramos-Júdez et al (2021), in which larvae survived no longer than 4 dph at 24 ºC. Not only larvae survived longer without the application of external feeding, but also larvae reared using mesocosm conditions demonstrated the potential to develop until juveniles, indicating that eggs and larvae obtained after the induction of gametogenesis with rFsh and rLh could supply a hatchery.…”

“…One male in each spawning tank received a dose of 24 µg kg -1 of rLh while the others followed the hormonal treatment previously described, receiving 12 µg kg -1 of rLh. The selected females were injected intramuscularly with either (i) priming rLh and resolving Progesterone (P4) (Prolutex, IBSA Group, Italy) as in Ramos-Júdez et al (2021), (ii) rLh for priming and resolving injections or (iii) P4 for priming and resolving injections (doses in Table 1). Priming and resolving injections were administered 24:05 ± 0:40 h apart.…”

“…It represents an important species and a potential candidate in the diversification of aquaculture products mainly in the Mediterranean area, the Southeast of Asia, Taiwan, Japan and Hawaii (González-Castro and Minos, 2016). In the Mediterranean, flathead grey mullet spawn from July to October (Whitfield et al, 2012), however, breeders held in intensive conditions show reproductive dysfunctions; males rarely produce fluent milt (Aizen et al, 2005;De Monbrison et al, 1997;Yashouv, 1969) and females are found to be arrested at previtellogenesis (Ramos-Júdez et al, 2021) or early stages of vitellogenesis (Aizen et al, 2005).…”