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Nitric oxide synthase activity in the molluscan CNS
L L Moroz1, D Chen, M U Gillette
1Department of Molecular and Integrative Physiology, University of Illinois, Urbana 61801, USA.
Journal of Neurochemistry
|February 1, 1996
Summary
Nitric oxide synthase (NOS) activity is high in the predatory sea slug Pleurobranchaea californica, unlike other mollusks. This suggests a link between NOS activity and predatory behavior in marine invertebrates.
Area of Science:
- Neuroscience
- Marine Biology
- Biochemistry
Background:
- Nitric oxide synthase (NOS) plays crucial roles in neuronal function.
- Investigating NOS activity in diverse molluscan species can reveal evolutionary and functional insights.
- Previous studies have not extensively characterized NOS in predatory opisthobranchs.
Purpose of the Study:
- To assay putative nitric oxide synthase (NOS) activity in the central nervous system (CNS) of mollusks.
- To compare NOS distribution and activity across different opisthobranch and cephalopod species.
- To investigate the characteristics of NOS activity, including cofactor dependence and inhibitor sensitivity.
Main Methods:
- Histochemical localization of NADPH-diaphorase activity in neural tissues.
- Measurement of L-arginine to L-citrulline conversion as an indicator of NOS activity.
- Use of specific enzyme inhibitors (e.g., L-NAME, trifluoperazine) and cofactor analysis (beta-NADPH, Ca2+).
Main Results:
- Numerous NADPH-dependent diaphorase-positive neurons were observed in Pleurobranchaea californica CNS.
- Other studied opisthobranchs and cephalopods exhibited sparse or light staining for diaphorase.
- NOS activity in Pleurobranchaea was NADPH-dependent, Ca2+-independent, and inhibited by L-NAME and trifluoperazine, suggesting a novel isoform.
Conclusions:
- Pleurobranchaea californica exhibits significantly higher NOS activity in its CNS compared to other surveyed mollusks.
- The observed high NOS activity in Pleurobranchaea neurons may be linked to its predatory lifestyle.
- This study identifies a potentially novel, constitutive, Ca2+-independent NOS isoform in molluscan CNS.