Changes in integument histology and protein expression related to the molting cycle of the black tiger shrimp, Penaeus monodon

Abstract

We investigated changes in the histology and protein expression in the epidermis and sub-epidermis of the black tiger shrimp (Penaeus monondon) during the molting cycle. The epidermis consists of a cell layer located beneath the cuticle, while the sub-epidermis is mainly composed of sub-epidermal cells and tegumental glands. During the molting cycle, the epidermal cells increase in cell height and number, and the sub-epidermis increases in its storage of carbohydrate, protein, mucus, and other unidentified substances at the time of the active period of cuticular regeneration. At the early premolt (stage D0), the epidermal cells are tidily organized, but short. Storage of carbohydrate and protein in the sub-epidermis is not observed. During the rest of the premolt (D1-4 stages) and the early postmolt A stage, epidermal cell height and sub-epidermal deposition are increased, and reached a maximum during the D4 to A stages. The period of late postmolt stages B-C3 is the time for a decrease in epidermal cell height and sub-epidermal depositions. Lastly at intermolt stage C4, the epidermal cells become short, and untidily organized. Sub-epidermal deposition is not observed. Protein expression in the epidermis and sub-epidermis was observed by SDS-PAGE. This revealed that the profile of a protein band with a molecular mass of 57 kDa corresponded with the profile observed by histochemistry. All results point to the conclusion that both the epidermis and sub-epidermis play major roles in cuticular regeneration. It may also reflect the level of metbolic activity of the integument during the molting cycle. In addition, for the first time, this work provides direct evidence of the epidermal and sub-epidermal changes that occur during the molting cycle of the black tiger shrimp. © 2007 Elsevier Inc. All rights reserved.