Document Detail

Light activation of phospholipase A2 in the photoreceptor of the crayfish (Procambarus clarkii).
MedLine Citation:
PMID:  10769925     Owner:  NLM     Status:  MEDLINE    
Retinal lipids of crayfish, kept at 4 degrees C under continuous darkness for 3 weeks, consisted mainly of phosphatidylcholine (PC) and phosphatidylethanolamine (PE); sphingomyelin (SM), phosphatidylinositol (PI) and phosphatidylserine (PS) were minor contributors. PI, involved in the phototransduction cascade, never reached greater concentrations than 7% of the total. High concentrations of polyunsaturated fatty acids (PUFA) such as 20:4n-6, 20:5n-3 and 22:6n-3 (DHA, docosahexaenoic acid) were present in PC, PE and PS, but scarce in SM and PI. In retinae of crayfish kept at 4 degrees C in darkness for 3 weeks and then exposed to white light (6 h; ca. 4,500 lx), SM and PS remained seemingly unaffected. PC, however, significantly decreased within 10 min to 65% of the initial value and 50% at 180 min. To study the reduction of PC, lipids of retinae suspended in physiological solution with/without phospholipase C (PLC) and phospholipase A2 (PLA2) inhibitors such as DMDA (= DEDA), manoalide, ET-18-OCH3, and U-73122 were measured. Only free fatty acids (FFA) of retinae with inhibitors of PLA2 like DMDA and manoalide decreased. Retinae irradiated by white light for 3 h displayed a significant reduction of PC, compared with those that had remained in continuous darkness. However, the PC of retinae with PLA2-inhibitors was not decreased by light. Our results provide evidence that not only photoreceptor cell PLC, but also PLA2 is activated by light.
T Kashiwagi; V B Meyer-Rochow; K Nishimura; E Eguchi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Acta neurobiologiae experimentalis     Volume:  60     ISSN:  0065-1400     ISO Abbreviation:  Acta Neurobiol Exp (Wars)     Publication Date:  2000  
Date Detail:
Created Date:  2000-05-18     Completed Date:  2000-05-18     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  1246675     Medline TA:  Acta Neurobiol Exp (Wars)     Country:  POLAND    
Other Details:
Languages:  eng     Pagination:  9-16     Citation Subset:  IM; S    
Department of Virology, School of Medicine, Kurume University, Fukuoka, Japan.
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MeSH Terms
Cell Membrane / enzymology
Dark Adaptation / physiology
Enzyme Activation / physiology
Estrenes / pharmacology
Fatty Acids, Nonesterified / metabolism
Fatty Acids, Unsaturated / metabolism,  pharmacology
Phosphatidylcholines / metabolism
Phosphodiesterase Inhibitors / pharmacology
Phospholipases A / metabolism*
Phospholipases A2
Phospholipid Ethers / pharmacology
Photic Stimulation
Photoreceptor Cells, Invertebrate / drug effects,  enzymology*
Pyrrolidinones / pharmacology
Terpenes / pharmacology
Vision, Ocular / physiology*
Reg. No./Substance:
0/Estrenes; 0/Fatty Acids, Nonesterified; 0/Fatty Acids, Unsaturated; 0/Phosphatidylcholines; 0/Phosphodiesterase Inhibitors; 0/Phospholipid Ethers; 0/Pyrrolidinones; 0/Terpenes; 112648-68-7/1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; 65492-82-2/edelfosine; 75088-80-1/manoalide; 89560-01-0/7,7-dimethyl-5,8-eicosadienoic acid; EC 3.1.1.-/Phospholipases A; EC A2

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