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Differential expression of eight transcripts and their roles in the cuticle of the blue crab, Callinectes sapidus

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Lindsay Faircloth (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/

Abstract: Biomineralization in the exoskeleton of decapods is under the control of proteins deposited in each of the cuticle layers by the hypodermis. The epicuticle and exocuticle are deposited before ecdysis, but their mineralization is delayed until after the molt. The endocuticle, however, mineralizes as it is deposited postecdysis. Furthermore, cuticle at the joints known as arthrodial membrane, consists of both pre- and post-ecdysial layers, but does not mineralize at all. Therefore, obtaining sequences and conducting expression analyses for many cuticular proteins may provide insights into the process of mineral formation. This study examines the expression patterns of eight new cuticle protein genes from Callinectes sapidus across the molt cycle in both calcifying and non-calcifying cuticle hypodermis using quantitative PCR, Northern blots, and in situ hybridization. Four of the transcripts were found only in calcifying hypodermis and are designated CsCP followed by the molecular weight of the predicted mature protein. CsCP6.1 is expressed post-molt and contains a Rebers-Riddiford (RR) motif, suggesting that it binds to chitin in the endocuticle. CsCP14.1 also contains an RR motif. Interestingly, it is the RR-1 variant common in non-calcifying cuticle proteins. The other two transcripts from calcifying hypodermis do not code for RR proteins, but both contain three copies of a different cuticle motif. One of these, CsCP19.0, is expressed only post-molt while the other, CsCP15.0, is present both before and after ecdysis. The other four transcripts characterized in this study are found only in arthrodial memebrane hypodermis and are designated CsAMP. They all contain RR-1 motifs and so presumably bind chitin in the non-calcifying cuticle. CsAMP9.3 is most likely an exocuticle constituent since it is expressed only during pre-molt. The other three transcripts are present both before and after ecdysis. Though the specific timing of gene expression differs, all these proteins may be necessary structural elements common to all non-calcifying arthrodial cuticle layers. One of these, CsAMP16.3, contains the RGD cell-attachment motif. It could be involved in anchoring the hypodermis of pore canals to chitn fibers.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Biomineralization, Blue crab--Genetics, Blue crab--Molecular genetics, Callinectes--Molecular genetics, Callinectes--Morphology, Callinectes--Physiology, Decapoda (Crustacea)--Morphology
Subjects
Biomineralization
Callinectes -- Morphology
Callinectes -- Physiology
Blue crab -- Genetics
Decapoda (Crustacea) -- Morphology
Blue crab -- Molecular genetics
Callinectes -- Molecular genetics