Identification of a calcitonin-like diuretic hormone that functions as an intrinsic modulator of the American lobster, Homarus americanus, cardiac neuromuscular system.
In insects, a family of peptides with sequence homology to the vertebrate calcitonins has been implicated in the control of diuresis, a process that includes mixing of the hemolymph. Here, we show that a member of the insect calcitonin-like diuretic hormone (CLDH) family is present in the American lobster, Homarus americanus, serving, at least in part, as a powerful modulator of cardiac output. Specifically, during an ongoing EST project, a transcript encoding a putative H. americanus CLDH precursor was identified; a full-length cDNA was subsequently cloned. In silico analyses of the deduced prepro-hormone predicted the mature structure of the encoded CLDH to be GLDLGLGRGFSGSQAAKHLMGLAAANFAGGPamide (Homam-CLDH), which is identical to a known Tribolium castaneum peptide. RT-PCR tissue profiling suggests that Homam-CLDH is broadly distributed within the lobster nervous system, including the cardiac ganglion (CG), which controls the movement of the neurogenic heart. RT-PCR analysis conducted on pacemaker neuron- and motor neuron-specific cDNAs suggests that the motor neurons are the source of the CLDH message in the CG. Perfusion of Homam-CLDH through the isolated lobster heart produced dose-dependent increases in both contraction frequency and amplitude and a dose-dependent decrease in contraction duration, with threshold concentrations for all parameters in the range 10(-11) to 10(-10) mol l(-1) or less, among the lowest for any peptide on this system. This report is the first documentation of a decapod CLDH, the first demonstration of CLDH bioactivity outside the Insecta, and the first detection of an intrinsic neuropeptide transcript in the crustacean CG.
Christie
A E
AE
Center for Marine Functional Genomics, Mount Desert Island Biological Laboratory, PO Box 35, Old Bar Harbor Road, Salisbury Cove, ME 04672, USA. achristi@mdibl.org
Stevens
J S
JS
Bowers
M R
MR
Chapline
M C
MC
Jensen
D A
DA
Schegg
K M
KM
Goldwaser
J
J
Kwiatkowski
M A
MA
Pleasant
T K
TK
Shoenfeld
L
L
Tempest
L K
LK
Williams
C R
CR
Wiwatpanit
T
T
Smith
C M
CM
Beale
K M
KM
Towle
D W
DW
Schooley
D A
DA
Dickinson
P S
PS
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002116:Calcitonin / Q000031:analogs & derivatives*; D002302:Cardiac Output; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004232:Diuretics / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D006728:Hormones / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D008121:Nephropidae / Q000378:metabolism*
D018076:DNA, Complementary; D004232:Diuretics; D006728:Hormones; D002116:Calcitonin