Seven transcripts from the chitinase gene family of the mud crabScylla paramamosain: Their expression profiles during development and moulting and under environmental stresses

Abstract

In crustaceans, chitinases (Chts) play crucial roles in physiological functions such as chitinous food digestion, moulting and stress responses. Chitinases have been identified in both prokaryotes and eukaryotes, but the composition and number of Cht family members vary across species, especially in crustaceans. Seven Cht transcripts, all of which contained the conserved enzyme activity motif, were cloned from Scylla paramamosain for the first time, and SpCht1-SpCht6 were clearly classified into groups 1-6, respectively, through phylogenetic analysis. Notably, SpCht7, which had two catalytic domains, was identified for the first time in crabs and crustaceans.Although SpCht7 could not be grouped into any known Cht subclasses, it clustered together with insect Cht7 and could be classified into a novel subclass that we named group 7. The tissue distributions of SpChts, as well as their expression profiles during embryonic and larval development, growth-related moulting, salinity and cadmium stresses, were also investigated. The results suggested that SpChts might have different and varied biological functions. These results would be helpful for understanding and clarifying the roles of chitinases in crab development, moulting and responses to environmental stress. These results also provide new insight into the origin and evolution of the chitinase gene family in crabs and other crustaceans. K E Y W O R D Schitinase, development, moulting, Scylla paramamosain, stress

Chitin Synthesis and Degradation in Crustaceans: A Genomic View and Application

“…Further studies have shown that the chitinase expressed in the hepatopancreas and intestines may be mainly related to the degradation of chitin-containing foods and nutrient absorption, whereas the chitinase gene expressed in the epidermis is mainly related to the exoskeleton’s physiological cycle or molting. Additionally, some chitinases expressed in the hepatopancreas, hemocytes and epidermis also participate in immune response mechanisms [ 44 , 49 ].…”

Transcriptome Analysis of The Whole Body Provides Novel Insights Into The Molecular Mechanisms of Growth, Immunity, and Metabolism During The Molting Cycle of The Juvenile Mud Crab Scylla Paramamosain

“…Similar to other crustaceans, growth of S. paramamosain is a stepwise process comprising periodic shedding, subsequent reconstruction of a rigid external exoskeleton and cuticle, and muscle growth to ll the new body during a molting cycle [3,38]. Some functional genes involved in the molting cycle of crabs were identi ed as associated with a series of biological processes in previous studies, for example, in cuticle reconstruction, cytoskeletal structure remodeling, protein synthesis, hormone regulation, immune response, and metabolism [4,13,15,17]. Among these processes, cuticle reconstruction and cytoskeletal structure remodeling have been considered to be essential for all four phases of the molting cycle [33].…”

“…Scylla paramamosain (Crustacea: Decapoda: Portunidae), commonly known as the mud crab, is widely distributed along the temperate, subtropical, and tropical areas of the Paci c Ocean and Indian Ocean, and this species is cultivated in many countries. S. paramamosain undergoes molting up to 18 times during its life cycle, including during larval development, during growth-related molting, and in adult reproductive molting [13]. The economic signi cance of this species makes the mud crab a valuable system for exploring the genes involved in the molting cycle.…”

“…Molt-inhibiting hormone (MIH) genes and the crustacean hyperglycemic hormone (CHH) genes that serve as key regulators of hormones controlling the molting process in crustaceans have been cloned and their distribution explored in different tissues during the molting cycle of the mud crab [15,16]. Moreover, the expression pro les of the chitinase gene family and the Na + /K + /2Cl − cotransporter of mud crabs have been explored during molting [13,17]. Most recently, a transcriptome study on the hepatopancreas immune response during the molting cycle in S. paramamosain has provided a better understanding of the hepatopancreas immune system [17], but our knowledge of the molecular mechanisms remains limited.…”

Whole-body transcriptome analysis provides insights into the cascade of sequential expression events involved in growth, immunity, and metabolism during the molting cycle in Scylla paramamosain

“…Moreover, recent studies have explored molting-related genes and their effects on protein synthesis 10 , chitin metabolism 11 , and muscle hydration control 12 during the molting cycle. In addition, great progress has been made in elucidating molting in the last decade by focusing on the effects of environmental factors, the immune system, and endocrine regulation molting, and by conducting gene expression analysis 13 – 28 . However, the molecular events and mechanisms associated with the dynamic process of molting remain poorly understood in crustaceans, especially in crabs.…”