Identification and characterization of Y-organs in orange mud crab Scylla olivacea
Muhammad Achdiat (a*), Yushinta Fujaya (b), Hanafiah Fazhan (a, c), Rusydi Rozaimi (a), J. Sook Chung (d), Muyassar H. Abualreesh (e), Youji Wang (f), Alexander Chong Shu-Chien (c, g), Khor Waiho (a, c)

a) Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, Kuala Nerus, Terengganu, Malaysia
*p4961[at]pps.umt.edu.my
b) Faculty of Marine Science and Fisheries, Hasanuddin University, Makassar, Indonesia
c) Center for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas, Penang, Malaysia
d) Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD, United States
e) Department of Marine Biology, Faculty of Marine Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
f) International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China
g) School of Biological Sciences, Universiti Sains Malaysia, Bayan Lepas, Penang, Malaysia

Abstract

The hormonal physiology approach is one of the breakthroughs that can be made in supporting the development of aquaculture technology to increase aquaculture production. Ecdysteroid, also known as moulting hormone, is synthesised and secreted by the Y-organs (YOs) to regulate the growth and reproduction of crustaceans. The information regarding the YOs of Scylla olivacea (Herbst, 1976) is not yet reported in detail. This study describes the location, morphological characteristics, histology, and fine structure of the YOs of wild adult male of S. olivacea. The YOs are in pairs and located in the anterior of the cephalothorax, beneath the mandibular external adductor muscle, anterior to the branchial chamber space, and around the end of the nerve tract. They are characterised by their yellowish-white, compact, and oval-shaped characteristics. Based on the histological observation, the characteristics of this gland are abundant in the cells that are closely arranged with the surrounding connective tissue. The electron microscope shows the YOs surface morphology, which is rough, bumpy, network-like, and porous, with the presence of several lacunar system tubules, indicating that it was a capillary artery. Besides that, the fine structure of the YOs shows the nuclei, nucleoli, and other organelles, including mitochondria, smooth endoplasmic reticulum, secretory vesicle, and ribosome, that were found sparsely in the perinuclear cytoplasm. The identification and characterisation of the YOs of S.olivacea are similar to the descriptions of the other Brachyura.

Keywords: Brachyura, Scylla olivacea, Y-organ, moulting, growth.

Topic: Sustainable Aquaculture and Fisheries