Specific glycine uptake by identified neurons of Aplysia californica. II. Biochemistry

McAdoo, David J.; Iliffe, Thomas M.; Price, Christopher H.; Novak, Roger A.

doi:10.1016/0006-8993(78)91049-1

Cited by 24 publications

(3 citation statements)

References 22 publications

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“…The formation of P-DG could be a mechanism for inactivating either aspartate or glycine, both of which have been proposed as possible neurotransmitters or neuromodulators in Aplysia (Zeman and Carpenter, 1975;McAdoo et al, 1978;Sawada et al, 1981). However because the peptide was aiso found in high concentration in nonnervous tissues it may also be associated with cellular processes independent of nervous activity.…”

Section: Discussionmentioning

confidence: 99%

Identification of an Acidic Dipeptide, β‐Aspartylglycine, in the CNS of Aplysia

McCaman

Stetzler

1984

Journal of Neurochemistry

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A novel dipeptide, beta-aspartylglycine (beta-DG), has been isolated from tissues of the marine gastropod mollusc Aplysia californica. This compound was detected only in Aplysia and not in other molluscs, such as Helix or Mercenaria, or in lobster or frog. Among the Aplysia tissues, the highest levels of beta-DG were in nervous tissue and in the reproductive tract. beta-DG was assayed by HPLC as the o-phthaldialdehyde derivative and found to be present in all individual, identified neurons at a concentration of approximately 40 pmol/microgram protein. The peptide was identified as beta-DG by gas chromatography-mass spectrometry (GCMS) using trimethylsilyl derivatives prepared before and after acid hydrolysis. It was further characterized as the beta-isomer by TLC, including Rf, atypical blue-gray color with ninhydrin, and a violet color with Cu2+-ninhydrin. A fractionation scheme is described whereby acid-soluble tissue constituents can be divided into acidic, neutral, and basic components using mini ion-exchange columns. This partial purification prior to TLC analysis was necessary to remove compounds that interfered with the isolation of beta-DG.

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Section: Discussionmentioning

confidence: 99%

Identification of an Acidic Dipeptide, β‐Aspartylglycine, in the CNS of Aplysia

McCaman

Stetzler

1984

Journal of Neurochemistry

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“…The basis for this approach was that the R3-14 soma, axons, and terminals possess rapid, high-affinity uptake and axonal transport systems for glycine (McAdoo et al, 1978;. Low concentrations of 3H-glycine can thus be used to label these neurons.…”

Section: Autoradiographymentioning

confidence: 99%

“…These neurons possess high concentrations of free glycine in their soma (Iliffe et al, 1977;Price et al, 1978a) and are supplied by a rapid and selective uptake system (McAdoo et al, 1978;Price et al, 1978b). Once taken up, glycine undergoes both rapid anterograde and retrograde (Carlson et al, 1984) axonal transport.…”

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confidence: 99%

Electrophysiological and anatomical identification of the peripheral axons and target tissues of Aplysia neurons R3-14 and their status as multifunctional, multimessenger neurons

Rittenhouse¹,

Price²

1986

J. Neurosci.

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The giant neurons R3-14 in the parietovisceral ganglion of Aplysia, originally proposed to be a homogeneous group of neuroendocrine cells, are likely candidates for a multifunctional and multiple messenger status. The studies reported here suggest that individual R3-14 giant neurons not only innervate specific target tissues but appear to operate more autonomously than previously thought. Identified members of the group were traced into peripheral tissues by electrophysiological, autoradiographic, and intracellular cobalt staining techniques. Five neurons (numbered R6, R7, R8, Rll, and R14) were identified on the basis of their unique patterns of axonal projections. R6 innervates the ganglionic artery and pericardial area; R7 and R8, the heart; Rll, the kidney; and R14, a large number of vascular tissues. The wide distribution of R3-14 terminals innervating a variety of vascular tissues indicates that several general and local aspects of circulatory physiology are likely to be regulated by these neurons. R3-14 contain the free amino acid glycine, a putative neuromodulator that potentiates cardiac and vascular smooth muscle contraction and several small peptides of unknown, but probably neurohormonal, function. A model is proposed in which R3-14 release glycine to modulate local (e.g., hemolymph pressure and distribution) cardiovascular performance and, indirectly, metabolic homeostasis as well.Many invertebrate neurons can be identified by their size, color, and location within the nervous system, as well as by their endogenous spike activity and synaptic input. In the parietovisceral ganglion (PVG) of the mollusc Aplysia, for example, perhaps 5% of its neurons in the PVG have been used for singlecell level studies on the neural organization underlying defined behavior, learning, neurochemistry, and expression of genetic information. The functions of many of the other PVG cells are not known because it has been difficult, in many cases, to trace peripheral axons. Intracellular stains often travel only short distances in these large neurons (Winlow and Kandel, 1976) and electrophysiological tracing can be a tedious task with low return. These factors have limited study of the most distinctive group of giant cells in Aplysia, the 12 "white cells" (numbered R3-14) in the PVG, neurons whose peptide synthesis, endogenous electrical activity, and general morphology have been described, but whose function(s) are largely unknown (Coggeshall, 1967;Coggeshall et al., 1966;Frazier et al

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Anatomy and ultrastructure of the axons and terminals of neurons R3‐R14 in Aplysia

Price

McAdoo

1979

J of Comparative Neurology

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Using light and electron microscopy and autoradiography, we have traced the axons of neurons R3-R14 in the parietovisceral ganglion (PVG) of Aplysia to terminal fields associated with vascular tissue. The axons are identified by their large size (15-30 micrometer diameter), extensive glial infolding, characteristic dense core vesicles (DCV; approximately 180 nm diameter), and specific, rapid uptake of 3H-glycine. Each neuron in this homogeneous group sends an axon via the branchial nerve to the pericardial region surrounding the junction of the efferent gill vein and the heart. R14 also sends axons to major arteries near the PVG. The R3-R14 axons branch extensively; we estimate that there are at least several hundred per cell. Branches along axons in the branchial nerve exit the nerve, subdivide, and end blindly in the sheath which is bathed by hemolymph. Similar blind endings from R3R14 occur in the sheath of the PVG (Coggeshall, '67). Axonal branches in the pericardial region and the special R14 axons in the arterial walls form both varicose endings near and terminals in contact with vasvular smooth muscle. All R3-R14 endings are free of glia, packed with DCV, show occasional omega-shaped profiles and rapidly take up 3H-glycine. R3-R14 manufacture specific low molecular weight peptides (Gainer and Wollberg, '74), and both the cell bodies (Iliffe et al., '77) and the germinals contain unusually high concentrations of glycine. The presence of peptides as putative neurohormones and sheath endings (neurohormonal release areas) are consistent with R3-R14 being neurosecretory (Coggeshall et al., '66). While glycine could not be a circulating hormone due to its high circulating levels (Iliffe et al., '77), glycine could act as a local chemical messenger between R3-R14 and smooth muscle. The terminal morphology of R3-R14 is consistent with these neurons having both synaptic-type and neurosecretory-type functions.

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Specific glycine uptake by identified neurons of Aplysia californica. II. Biochemistry

Cited by 24 publications

References 22 publications

Identification of an Acidic Dipeptide, β‐Aspartylglycine, in the CNS of Aplysia

Identification of an Acidic Dipeptide, β‐Aspartylglycine, in the CNS of Aplysia

Electrophysiological and anatomical identification of the peripheral axons and target tissues of Aplysia neurons R3-14 and their status as multifunctional, multimessenger neurons

Anatomy and ultrastructure of the axons and terminals of neurons R3‐R14 in Aplysia

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