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Expression of selected genes associated with ovarian maturation in mud crab, Scylla serrata
following eyestalk ablation and retinoid injection

1 K Venkaiah, M Hanuma Reddy*, SB Sainath*
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1 Department of Biotechnology, Vikrama Simhapuri University, Nellore-524 324, AP, India
2 Department of Marine Biology, Vikrama Simhapuri University, Nellore-524 324, AP, India

* Corresponding authors: drsainath@vsu.ac.in; mhreddyvsu@gmail.com

Abstract:

The major bottleneck problem in the crustacean aquaculture industry was limited availability of seed.
However, eyestalk ablation (ESX) is a classical operational technique practiced to induced seed in hatchery
industry. However, mortality in the brood stock and inferior quality of seed are major problems associated
with ESX. Thus, alternative strategies are required to promote seed-to-seed technology in hatchery industry.
In the current study, the effect of 9-cis retinoic acid (9CRA) on ovarian maturation in the mud crabs, Scylla
serrata was investigated. Uninjured female mud crabs at intermolt stage were randomly allocated into three
groups (n=24 per group). Intact crabs in groups I did not receive any treatment (controls), while crabs in
group II (concurrent controls: CC) and group III received solvent used to dissolve 9CRA and 9CRA at a
dose of 10 mole/crab, respectively on days 1, 7, 14 and 28. At selected time points, six crabs were
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sacrificed and ovarian parameters such as ovarian index, oocyte diameter and ovarian vitellogenin levels
were analyzed. Further, transcriptomic analysis of mature ovary of crab (stage III/IV) revealed several
differentially expressed genes (DEGs) as compared to controls. Among the DEGs, several genes such as
retinoic acid X receptor (RXR), ecdysteroid receptor (EcR), fatty acid binding protein (FaBP), cellular
retinol binding protein (CRABP), ecdysone inducible gene (E75), and vitelline membrane outer layer 1
(VMO1). Injection of 9CRA significantly elevated the expression of selected genes in the ovary of carb
over controls. The results obtained from this study were comparable to the ESX crabs. The results indicated
that CRA could be used as a tool to overcome problems associated with ESX to promote seed in hatchery
industry. Further, studies were initiated in our lab to establish the link between the retinoid signaling and
the ovarian maturation of crabs.

Keywords: Scylla serrata, Eyestalk ablation, 9-cis retinoic acid, Ovarian maturation.