Please use this identifier to cite or link to this item: http://hdl.handle.net/10497/22104
Title: 
Authors: 
Keywords: 
Bicarbonate
CA4
Carbon dioxide
Light-enhanced calcification
Symbiosis
Zooxanthellae
Issue Date: 
2019
Citation: 
Chew, S. F., Koh, C. Z. Y., Hiong, K. C., Choo, C. Y. L., Wong, W. P., Neo, M. L., & Ip, Y. K. (2019). Light-enhanced expression of Carbonic Anhydrase 4-like supports shell formation in the fluted giant clam Tridacna squamosa. Gene, 683, 101-112. https://doi.org/10.1016/j.gene.2018.10.023
Abstract: 
Giant clams represent symbiotic associations between a host clam and its extracellular zooxanthellae. They are able to grow in nutrient-deficient tropical marine environments and conduct light-enhanced shell formation (calcification) with the aid of photosynthates donated by the symbiotic zooxanthellae. In light, there is a high demand for inorganic carbon (Ci) to support photosynthesis in the symbionts and light-enhanced calcification in the host. In this study, we cloned and characterized a host Carbonic Anhydrase 4 homolog (CA4-like) from the
whitish inner mantle of the giant clam Tridacna squamosa. The full cDNA coding sequence of CA4-like consisted of 1,002 bp, encoding for 334 amino acids of 38.5 kDa. The host CA4-like was phenogramically distinct from algal CAs. The transcript level of CA4-like in the inner mantle was ~3-fold higher than those in the colorful outer mantle and the ctenidium. In the inner mantle, CA4-like was immunolocalized in the apical membrane of the seawater-facing epithelial cells, but absent from the shell-facing epithelium. Hence, CA4-like was positioned to catalyze the conversion of HCO3 − to CO2 in the ambient seawater which would facilitate
CO2 uptake. The absorbed CO2 could be converted back to HCO3 − by the cytoplasmic CA2-like. As the protein abundance of CA4-like increased in the inner mantle after 6 or 12 h of light exposure, there could be an augmentation of the total CA4-like activity to increase Ci uptake in light. It is plausible that the absorbed Ci was allocated preferentially for shell formation due to the close proximity of the seawater-facing epithelium to the shell-facing epithelium in the inner mantle that contains only few zooxanthellae.
Description: 
This is the final draft, after peer-review, of a manuscript published in Gene. The published version is available online at https://doi.org/10.1016/j.gene.2018.10.023
URI: 
ISSN: 
0378-1119 (print)
1879-0038 (online)
Other Identifiers: 
10.1016/j.gene.2018.10.023
Appears in Collections:Journal Articles

Files in This Item:
File Description SizeFormat 
G-683-101.pdf2.27 MBAdobe PDFThumbnail
View/Open
Show full item record

Page view(s)

26
checked on Jun 3, 2020

Download(s)

10
checked on Jun 3, 2020

Google ScholarTM

Check

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.