ORCID Profile
0000-0002-9846-0923
Current Organisations
McGill University
,
Dalhousie University Faculty of Medicine
,
Tufts University
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Publisher: UPV/EHU Press
Date: 2009
Abstract: Prohormone convertase 2 (PC2) belongs to a family of enzymes involved in the proteolytic maturation of neuropeptide precursors into mature peptides that act as neurotransmitters, neuromodulators or neurohormones. Here we show that a gene encoding a PC2-like enzyme (HasPC2) is expressed during larval development and in the adult ganglia of the vetigastropod Haliotis asinina. HasPC2 exhibits high sequence identity to other gastropod PC2s and thus is likely to function in peptide processing. Analysis of HasPC2 expression indicates that it is activated early in nervous system development. During trochophore and early veliger larval stages, HasPC2 is expressed in the vicinity of the forming ganglia of the central nervous system and parts of the putative peripheral nervous system. Later in larval development, at the time the veliger becomes competent to interact with the external environment and initiate metamorphosis, HasPC2 expression largely restricts to cells of the major ganglia and their commissures. Profiling of veliger larvae by bioinformatic approaches suggests the expression of a variety of peptides. Direct MALDI-MS-based peptide profiling of juvenile Haliotis cerebral ganglia (brain) reveals an abundance of neuropeptides, including FMRFamide-related peptides and APGWamide, compatible with PC2 functioning in neuropeptide processing in these regions. These results are consistent with PC2 regulating neuropeptide generation in the earliest functioning of the gastropod nervous system.
Publisher: Wiley
Date: 23-05-2011
DOI: 10.1002/CNE.22621
Abstract: FMRFamide-related peptides (FaRPs) are involved in numerous neural functions across the animal kingdom and serve as important models for understanding the evolution of neuropeptides. Gastropod molluscs have proved to be particularly useful foci for such studies, but the developmental expression of FaRPs and the evolution of specific transcripts for different peptides are unclear within the molluscs. Here we show that FaRPs are encoded by two transcripts that appear to be splice variants of a single gene in the abalone, Haliotis asinina, which represents the basal vetigastropods. Has-FMRF1 comprises 1,438 nucleotides and encodes a precursor protein of 329 amino acids that can potentially produce two copies of FLRFamide, one copy each of TLAGDSFLRFamide, QFYRIamide, SDPDLDDVIRASLLAYSLDDSPNN, and SVATAPVEAKAVEAGNKDIE, and 13 copies of FMRFamide. The second 1,241-nucleotide transcript, Has-FMRF2, encodes a 206-amino acid precursor protein with single copies of FLRFamide and FMRFamide along with such extended forms as NFGEPFLRFamide, FDSYEDKALRFamide, and NGWLHFamide, in addition to SDPGEDMLKSILLRGAPSNNGLQY and DTUDETTUNDNAHSRQ. Both transcripts are present early in life and are expressed in different but overlapping patterns within the developing larval nervous system. Mass spectrometry and immunocytochemistry demonstrate that FaRPs are cleaved from larger precursors and localize to the developing nervous system. Our results confirm previous evidence that FaRPs are expressed early and potentially play many roles during molluscan development and suggest that the last common ancestor to living gastropods used alternative splicing of an FMRFamide gene to generate a ersity of FaRPs in spatially restricted patterns in the nervous system.
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.CBPA.2009.07.021
Abstract: The Pacific lion's paw scallop Nodipecten subnodosus has been one of the most important commercial species of mollusc in the Baja California peninsula in Mexico since 1990. This species is a functional hermaphrodite with tropical and sub-tropical distributions and experiences wide annual temperature oscillations influencing its physiological functions. We determined norepinephrine (NE), dopamine (DA), and serotonin (5-HT) concentrations in different organs (female and male gonads, digestive gland, adductor muscle, gill, mantle, and foot) of N. subnodosus, at 6 reproductive stages (resting, initial, maturing, mature, partially spent and fully spent). Monoamine concentrations were determined by HPLC fitted with an electrochemical detector. Results indicated that monoamine concentrations increased during maturing stage, peaked at mature stage and declined after spawning. NE concentrations were higher than the rest of monoamines followed by DA, and 5-HT. NE was present in all organs at all reproductive stages. DA concentrations were higher in the gill and digestive gland during all stages. 5-HT was only detectable in the male gonadic portion at all stages except at spent stage. NE was the most abundant neurotransmitter found in the female gonad of N. subnodosus, while 5-HT was the most abundant neurotransmitter found in the male gonad. Furthermore, these two neurotransmitters accumulated in the respective gonad tissues during the initial reproductive stages I to IV and then declined after spawning (stages V and VI). This suggests that this species utilized different neurotransmitters specific for each gender and that this utilization was related to the reproductive cycle.
No related grants have been discovered for Roger Croll.