Cyclic AMP concentration and protein kinase A (PKA) gene expression at different developmental stages of the polychaete Hydroides elegans.
The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) showed inductive effect on larval settlement of the polychaete Hydroides elegans. It has been suggested that IBMX triggers larval settlement by elevating the cellular adenosine 3',5'-cyclic monophosphate (cAMP) level in this species. To test this hypothesis, we first examined cAMP-level changes in both the competent (CL) and attached larvae (AL) and then characterized the cAMP-dependent protein kinase in H. elegans, which is the major mediator of cAMP action. Tissue extracts of the larvae were assayed for cAMP by enzyme immunoassay; the results showed that IBMX increased cAMP production up to approximately two-folds in the CL. However, there was no significant difference in the cAMP concentration between the CL and AL that were not treated with IBMX. The catalytic subunit of protein kinase A gene from H. elegans (designated HePKAc) was cloned, and its expression in different developmental stages of H. elegans was examined using quantitative real-time polymerase chain reaction. The gene expression level in the pre-competent trochophore larvae was the lowest, increased in the CL, reached the highest in the larvae undergoing normal and IBMX-induced metamorphosis, and then decreased in the adult stage. In situ hybridization results showed that HePKAc expressed mainly around eye regions and along body fragments of the CL and AL. Our results indicated that the IBMX-induced cAMP changes and the cAMP-dependent protein kinase gene may mediate larval development and settlement of H. elegans.
Li
Hong-Lei
HL
Atmospheric, Marine, and Coastal Environment Program and Coastal Marine Laboratory, Department of Biology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People's Republic of China.
Song
Lin-Sheng
LS
Qian
Pei-Yuan
PY
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry / Q000235:genetics*; D017931:DNA Primers; D018076:DNA, Complementary; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011077:Polychaeta / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D018076:DNA, Complementary; D010726:Phosphodiesterase Inhibitors; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015056:1-Methyl-3-isobutylxanthine