No abstract

This research was implemented to study the effects of androgenic gland ablation in the white shrimp Litopenaeus vannamei to explore sex reversal potential as an alternative technology for monosex female mariculture based on the sex dimorphic growth of this species. The surgical procedure was applied to male postlarvae (PL) at different ages, after external sex differentiation, as well as in sex undifferentiated PL. Andrectomized males regenerated normal appendices including pereiopods and pleopods; however, body growth and relative size of regenerated petasmas and appendices masculinae were statistically inferior (P ˂ 0.05) to control males. Spermatogenesis in andrectomized males was active, but a phenomenon of degradation of spermatids and reproductive tissues was detected. No sex reversal was accomplished regardless of PL age from sex undifferentiated stages (PL38) to sex differentiated stages (˃PL55). The complete regeneration of sexual characters in andrectomized L. vannamei (Dendrobranchiata) is different from previous reports from Decapoda.

Shrimp farming worldwide is based on a similar technological package, characterized by three phases: Controlled Reproduction, Larvae Culture, and Grow-out Culture. This basic aquaculture package uses broodstock animals, with different levels of fundamental genetic selection, induced to mature and reproduce based on unilateral eyestalk ablation. This review identified ten reproduction-related research subjects that can improve the shrimp industry based on basic scientific knowledge and four levels of application: eyestalk ablation alternatives, larvae production, product protection, and grow-out yield improvement. Species-specificity must be considered in developing biotechnology solutions. Alternatives to eyestalk ablation for controlling ovarian maturation are based on neurotransmitter regulation in Litopenaeus; however, the environmental impact of this approach has to be evaluated. Maturation by RNAi requires further evaluation, and maturation pheromones have not been explored. Sex reversal, hybridization, in vitro fertilization, and seedstock cryopreservation of penaeids require fundamental research. Triploid culture and genetic selection can be applied to some species for product protection; however, for L. vannamei, triploidization is not practical yet.

No abstract

A research was designed to explore the effect of ibuprofen (IBU) as an intervening agent for prostaglandin biosynthesis on male and female reproduction of three species of Litopenaeus. Ovarian maturation was studied in L. stylirostris and L. vannamei injected periodically with IBU at 0.01 and 0.1 μg g−1 body weight (b.w.) and treated for unilateral eyestalk ablation. IBU at 0.1 μg induced a statistically (P < 0.05) higher rate of L. vannamei females with developing ovaries (45 ± 19%) as compared with controls (12 ± 8%) during 5 weeks; L. stylirostris did not activate vitellogenesis under this experimental protocol. IBU was also evaluated for male sexuality in L. occidentalis, L. stylirostris and L. vannamei. Periodic injections of IBU had no effect on sperm counts and spermatophore weights; however, sperm abnormalities in IBU 0.1 μg treated L. occidentalis and L. stylirostris were very low. In L. stylirostris, the renovation of normal spermatophores was remarkably improved in IBU treated males as compared with controls, but in L. vannamei spermatophore deterioration was not affected. The findings of this research support the hypothesis that prostaglandins are involved in penaeid reproduction playing a negative physiological role; however, altered steroidogenic pathways could also be involved.