Isolation of actin-encoding cDNAs from symbiotic corals

Area of Science:

• Marine Biology
• Molecular Biology
• Coral Genetics

Background:

• Actin is a crucial cytoskeletal protein involved in various cellular processes.
• Scleractinian corals host symbiotic dinoflagellates, influencing their physiology.
• Understanding gene expression in corals is vital for assessing their health and response to environmental changes.

Purpose of the Study:

• To identify and characterize actinencoding cDNAs in the scleractinian coral Galaxea fascicularis.
• To investigate the differential expression of identified actin forms between coral larvae and adults.
• To explore the presence of similar actin forms in other coral species.

Main Methods:

• Reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) were employed.
• RNA and genomic DNA were extracted from planular larvae and adult corals.
• Sequence analysis was performed to compare coral actin cDNAs with those from Symbiodinium.

Main Results:

• Two distinct actin cDNAs, LGfact and AGfact-p, were identified in Galaxea fascicularis.
• LGfact transcripts were found in both asymbiotic larvae and symbiotic adults, indicating host expression.
• AGfact-p was specifically detected in adults, suggesting an adult-specific actin form, and orthologues were found in Favites chinensis.

Conclusions:

• LGfact represents a constitutively expressed host actin, while AGfact-p is likely an adult-specific actin form in scleractinian corals.
• The findings suggest differential regulation of actin isoforms during coral development and potentially in response to symbiosis.
• Orthologous sequences in other coral species indicate conserved actin gene families.