Myomodulin Gene ofLymnaea: Structure, Expression, and Analysis of Neuropeptides

Abstract

The myomodulin family of neuropeptides is an important group of neural cotransmitters in molluscs and is known to be present in the neural network that controls feeding behavior in the snailLymnaea. Here we show that a single gene encodes five structurally similar forms of myomodulin: GLQMLRLamide, QIPMLRLamide, SMSMLRLamide, SLSMLRLamide, and PMSMLRLamide, the latter being present in nine copies. Analysis of the organization of the gene indicates that it is transcribed as a single spliced transcript from an upstream promoter region that contains multiple cAMP-responsive elements, as well as putative elements with homology to tissue-specific promoter-binding sites. The presence in nervous tissue of two of the peptides, GLQMLRLamide and PMSMLRLamide, is confirmed by mass spectrometry.In situhybridization analysis indicates that the gene is expressed in specific cells in all ganglia of the CNS ofLymnaea, which will allow physiological analysis of the function of myomodulins at the level of single identified neurons.

Peptide Cotransmitter Release from Motorneuron B16 inAplysia californica: Costorage, Corelease, and Functional Implications

“…First, to measure the release of MMs from motorneuron B16. This is of particular importance because despite the presence of MMs and related peptides in a number of systems of a variety of species (Brezina et al, 1995;Kellett et al, 1996;Greenberg et al, 1997;Wang et al, 1998), no direct evidence exists for their release.…”

Identification of Genes Differentially Expressed in the Ganglia of GrowingHaliotis asinina

“…Although a number of genes related to the control of growth, reproduction, and feeding have been found in molluscs (Geraerts et al 1991, Geraerts et al 1992, Lopez et al 1993, Kellett et al 1996, Smit et al 1996, there is currently a paucity of such sequences in abalone. In this study we focused on genes expressed in anterior cerebral and pleuropedal ganglia of the tropical abalone H. asinina, because evidence to date from other molluscs suggests that these ganglia are central to the control of growth and reproduction (Geraerts et al 1991, Geraerts et al 1992, Lopez et al 1993, Kellett et al 1996, Smit et al 1996.…”

“…For example, a neuropeptide related to feeding and reproduction, myomodulin, has not been reported in haliotids, despite its characterization in other gastropods (Miller et al 1993, Kellett et al 1996. In terms of abalone production, there is interest both in improving growth rates and controlling reproduction.…”

“…In other gastropods, there appears to be an antagonism between growth and reproduction that is manifested, at least in part, by the differential expression of certain genes in the ganglia. These genes encode neuropeptides that are known to regulate growth, feeding behavior, hormonal processes, neurotransmission, and reproduction (Geraerts et al 1991, Geraerts et al 1992, Miller et al 1993, Kellett et al 1996, Smit et al 1996, Perry et al 1998, Vilim et al 2000, Proekt et al 2005. The expression of these neuropeptide genes is controlled by transcriptional regulators whose own expression is contingent on the developmental and physiological state of the animal (O'Brien & Degnan 2000).…”

The distinction between retractor and protractor muscles of the freshwater snail's male organ has no physiological basis

“…Hernádi et al, 1995). In L. stagnalis, five different myomodulin peptides are encoded by a myomodulin gene (Kellett et al, 1996) and the different myomodulins modulate the contractions of the preputium retractor muscles (Li et al, 1994;Van Golen et al, 1996). Given their contractile and relaxing properties, these peptides may thus The different lesions are indicated based on the band's location, side and number (see Fig.1).…”