The abundance of Aplysia gliagrana depends on Ca2+ and/or Na+ concentrations in sea water

Keicher, E.; Maggio, Katia; Hernandez‐Nicaise, Mari‐Luz; Nicaise, Ghislain

doi:10.1002/glia.440050207

Cited by 5 publications

(4 citation statements)

References 43 publications

(58 reference statements)

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“…One possible explanation for the fluorescence shell seen in the R2 neurons is that the fluorescence results from NO production in the glia embracing the R2 cell body. It is known that giant Aplysia neurons such as the R2 are surrounded by numerous glia interspersed by extracellular space and forming thin concentric layers − . Microstructural analysis of the abdominal ganglion in a semi-intact preparation by scanning electron microscopy (SEM) (Figure d, e) revealed that the R2 surface exhibits substantial roughness.…”

Section: Resultsmentioning

confidence: 99%

Production of Nitric Oxide within the Aplysia californica Nervous System

Xie

Romanova

et al. 2009

ACS Chem. Neurosci.

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Nitric oxide (NO), an intercellular signaling molecule, helps coordinate neuronal network activity. Here we examine NO generation in the Aplysia central nervous system using 4,5-diaminofluorescein diacetate (DAF-2 DA), a fluorescent reagent that forms 4,5-diaminofluorescein triazole (DAF-2T) upon reaction with NO. Recognizing that other fluorescence products are formed within the biochemically complex intracellular environment, we validate the observed fluorescence as being from DAF-2T; using both capillary electrophoresis and mass spectrometry we confirm that DAF-2T is formed from tissues and cells exposed to DAF-2 DA. We observe three distinct subcellular distributions of fluorescence in neurons exposed to DAF-2 DA. The first shows uniform fluorescence inside the cell, with these cells being among previously confirmed NOS-positive regions in the Aplysia cerebral ganglion. The second, seen inside buccal neurons, exhibits point sources of fluorescence, 1.5 ± 0.7 µm in diameter. Interestingly, the number of fluorescence puncta increases when the tissue is preincubated with the NOS substrate L-arginine, and they disappear when cells are preexposed to the NOS inhibitor L-NAME, demonstrating that the fluorescence is connected to NOS-dependent NO production. The third distribution type, seen in the R2 neuron, also exhibits fluorescent puncta, but only on the cell surface. Fluorescence is also observed in the terminals of cultured bag cell neurons loaded with DAF-2 DA. Surprisingly, fluorescence at the R2 surface and bag cell neuron terminals is not modulated by L-arginine or L-NAME, suggesting it has a source distinct from the buccal and cerebral ganglion DAF 2T-positive tissues.

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Section: Resultsmentioning

confidence: 99%

Production of Nitric Oxide within the Aplysia californica Nervous System

Xie

Romanova

et al. 2009

ACS Chem. Neurosci.

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“…Na+ substitution during Ca2+-free exposure blocks reperfusion Ca2+ rises while Na+ substitution during normal saline reperfusion enhances Ca2+ increases. By contrast, glialgrana pump Ca2+ via a Ca"/H+ exchanger (Keicher et al, 1992).…”

Section: Calcium Homeostasis Calcium Localizationmentioning

confidence: 99%

“…In addition, certain invertebrate glia have glialgrana, unusual acidic Ca2+ containing organelles which may contain as much as 5&100 mM Ca" . Glialgrana density increases in response to decreasing extracellular Ca2+ concentration suggesting these organelles regulate CaZt in the interstitial space (Keicher et al, 1992).…”

Section: Calcium Homeostasis Calcium Localizationmentioning

confidence: 99%

Glial calcium

Finkbeiner

1993

Glia

194

140

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This review summarizes current knowledge relating intracellular calcium and glial function. During steady state, glia maintain a low cytosolic calcium level by pumping calcium into intracellular stores and by extruding calcium across the plasma membrane. Glial Ca2+ increases in response to a variety of physiological stimuli. Some stimuli open membrane calcium channels, others release calcium from intracellular stores, and some do both. The temporal and spatial complexity of glial cytosolic calcium changes suggest that these responses may form the basis of an intracellular or intercellular signaling system. Cytosolic calcium rises effect changes in glial structure and function through protein kinases, phospholipases, and direct interaction with lipid and protein constituents. Ultimately, calcium signaling influence glial gene expression, development, metabolism, and regulation of the extracellular milieu. Disturbances in glial calcium homeostasis may have a role in certain pathological conditions. The discovery of complex calcium-based glial signaling systems, capable of sensing and influencing neural activity, suggest a more integrated neuro-glial model of information processing in the central nervous system.

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“…Echinoderm juxtaligamental cells may increase the stiffness of collagen tendons [57,150] by releasing their granular calcium stores. It has also been proposed that glial granules could function as a store to regulate the perineuronal calcium concentration in molluscs [69,70,102] as well as vertebrates [42]. But many other secretory granules are likely to release significant amounts of calcium (tables II, III) when they undergo partial or total exocytosis.…”

Section: Excretion Of Calcium Can Be Achieved By Granule Exocytosismentioning

confidence: 99%

The calcium loading of secretory granules. A possible key event in stimulus‐secretion coupling

Nicaise

Maggio

Thirion

et al. 1992

Biology of the Cell

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The review focuses on calcium accumulation by secretory organelles. The observation that secretory granules contain variable and often important quantities of calcium (1-200 mM of total calcium) can be interpreted as a maturation index. A progressive loading with calcium would be permitted by a Ca2(+)-transport mechanism on the granular membrane and calcium-binding molecules in the granular core. The saturation of this store by the stimulus-induced calcium transient would permit in mature (calcium-loaded) granules the ionic crisis leading to exocytosis. The inside of secretory organelles being acidic, calcium influx into the granule can be driven by calcium-proton exchange. The calcium-proton exchanger could be a Ca2(+)-ATPase.

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The abundance of Aplysia gliagrana depends on Ca²⁺ and/or Na⁺ concentrations in sea water

Cited by 5 publications

References 43 publications

Production of Nitric Oxide within the Aplysia californica Nervous System

Production of Nitric Oxide within the Aplysia californica Nervous System

Glial calcium

The calcium loading of secretory granules. A possible key event in stimulus‐secretion coupling

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