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Future prospects of crustacean monosex culture: could it benefit from the discovery of an androgenic gland insulin-like factor?
Abstract

Future prospects of crustacean monosex culture: could it benefit from the discovery of an androgenic gland insulin-like factor?

E D Aflalo, Tomer Ventura and A Sagi
Aquaculture, 2010 (San Diego, United States, 01-Mar-2010–05-Mar-2010)
2010
url
https://www.was.org/wasmeetings/meetings/ShowAbstract.aspx?Id=19669View
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Abstract

Fisheries Sciences
Culture of monosex populations is a common procedure in animal husbandry. Differences between males and females of the same cultured species, in growth rate, alimentary needs and behavioral patterns, dictate the need to establish management procedures specifically adjusted to one sex or the other. The monosex culture strategy has become a common practice in fish culture and attempts have been made to apply it to crustaceans. In many crustacean species a sexual bimodal growth pattern is exhibited where females grow larger than males or vise versa. In one of the most economically important freshwater prawn Macrobrachium rosenbergii, males grow faster and reach larger size at harvest than females. Thus, all-male population culture is economically beneficial. Sexual differentiation in crustaceans is regulated by the androgenic gland (AG), which was found to play a pivotal role in the regulation of male differentiation and in the inhibition of female differentiation. In M. rosenbergii, AG removal (andrectomy) from immature males might result in sex reversal. Sex-reversed males (neo-females) are capable of mating and spawning. Crossing neo-females with normal males results in all-male progeny. This was tested and found to be feasible and a two step scheme for commercial all-male production was established. This two phase procedure increased the success rates and proved all male population production to be more feasible. However, a more elegant and easy to use technique is still needed to enable the scale-up of monosex culture of the species throughout the world. Recently, an AG specifically expressed gene, termed M. rosenbergii insulin-like AG factor (Mr-IAG) was studied at the transcript and protein levels. RNAi experiments in young males temporally prevented the regeneration of male secondary sexual features accompanied by a delay in molt and growth parameters. Moreover, prominent histological changes were observed following the silencing such as arrest of spermatogenesis in the testis. A complete functional sex reversal, if achieved by manipulating genes such as Mr-IAG or other AG specific genes and proteins at early developmental stages, might bear potential for the establishment of novel biotechnology for all-male culture in crustaceans.

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