Light activation of phospholipase A2 in the photoreceptor of the crayfish (Procambarus clarkii)

• Authors: T. Kashiwagi , V.B. Meyer-Rochow , K. Nishimura , E. Eguchi
• Languages of publication: EN

Abstracts

EN

Retinal lipids of crayfish, kept at 4oC 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 4oC 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.

Keywords

EN

CRAYFISH; EYE; FATTY ACID COMPOSITION; PHOSPHOLIPASE; PHOSPHOLIPID

Discipline

• EXPERIMENTAL_BIOLOGY_&_MEDICINE: EXPERIMENTAL BIOLOGY & MEDICINE

• Publisher: Marceli Nencki Institute of Experimental Biology, Polish Academy of Sciences
• Journal: Acta Neurobiologiae Experimentalis
• Year: 2000
• Volume: 60
• Issue: 1
• Pages: 9-16

Contributors

author

T. Kashiwagi

author

V.B. Meyer-Rochow

author

K. Nishimura

author

E. Eguchi

• Document Type: article
• Publication order reference: Takahito Kashiwagi, Department of Virology, School of Medicine, Kurume University, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan