Differential expression of neuropeptide gene mRNA within the LUQ cells of Aplysia californica

Abstract

Two neuropeptide precursor cDNAs (LUQ-1 and L5-67) have been recently isolated from the Left Upper Quadrant (LUQ) neurons of the abdominal ganglion of Aplysia californica (Shyamala, Fisher, and Scheller, 1986; Wickham and DesGroseillers, 1991). Using in situ hybridization techniques as well as dot blot and polymerase chain reaction (PCR) assays, we have studied the expression of these genes in the central nervous system (CNS) of Aplysia californica. The LUQ-1 gene was found to be expressed in neuron L5 in the abdominal ganglion, whereas the expression of the L5-67 gene was observed in the other four LUQ cells (L2-4 and L6). When in situ hybridization was performed on paraffin sections of the abdominal ganglion, clusters of smaller cells located in the left hemiganglion, were also found to express either the LUQ-1 or the L5-67 gene, never both. In many sections, the mRNAs coding for the two neuropeptides were found not only in cell bodies but also in the axon of individual LUQ neurons and even as far as the pericardial nerve. The presence of neuropeptide mRNA in axons, pericardial nerve, and kidney has been confirmed by polymerase chain reaction. A specific, although diffuse hybridization in the left upper quadrant also suggests that mRNA is present in the neuritic field. Taken together these results indicate that neuron L5 is the only giant neuron expressing the LUQ-1 gene and might therefore have a physiological function different from the other four LUQ cells. Neuropeptide mRNAs were also found in the axon and/or the neuritic field of giant neurons and could play important roles related to cell signalling in axons and nerve termini.

Kinesin mRNA Is Present in the Squid Giant Axon

“…Indeed, similar results were obtained in previous hybridization histochemical studies that employed ['H]poly(U) as a generic probe (Perrone Capano et al ., 1987), as well as riboprobes encoding the murine 68-kDa neurofilament protein (Giuditta et al ., 1991), and squid ,ß-actin and ß-tubulin (Kaplan et al ., 1992) . In addition to these findings, mRNAs encoding several neuropeptides have been reported in the axons of Aplysia californica (Van Minnen and Schallig, 1990;Landry et al ., 1992) and the pond snail, Lymnaea stagnalis (Van Minnen et al ., 1988 ;Dirks et al ., 1993). The presence of ruRNAs encoding neuropeptides (Jirikowski et al ., 1990;Mohr et al ., 1991), T (Litman et al ., 1993), and neurofilament proteins (Mohr and Richter, 1992) in mammalian axons demonstrates that intraaxonal mRNA is not a unique feature of these invertebrate model systems .…”

Ancient origin of somatic and visceral neurons

“…The kidney also receives input from giant neurons of the ‘left upper quadrant’. Among those, L5 is uniquely identified by expression of the peptide encoding the LUQ-1 gene [41], allowing us to show on consecutive sections that it was Phox2 + (Figure  4c,d). In Lymnaea , large ‘Light Yellow Cells’ (LYCs) [42] are considered homologous to the R3-R14 neurons on the basis of their size, color, location, synthesis of a peptide similar to HRBP [43] and projections to the heart, aorta, kidney, and connective tissue of the CNS [44].…”

Comparative analysis of neutral endopeptidase (NEP) and villin gene expression during mouse embryogenesis and enterocyte maturation

“…In situ hybridization on paraffin sections was performed according to the description of Jaffe et al [31] and Landry et al [36]. Tissues were fixed, dehydrated and embedded 1/1 in paraflin wax: Tissue Prep I1 (Fisher Scientific, Montreal, Quebec, Canada).…”

“…[31] and Landry et al[36]. Tissues were fixed, dehydrated and embedded 1/1 in paraflin wax: Tissue Prep I1 (Fisher Scientific, Montreal, Quebec, Canada).…”