Stavenga, Doekele Gerben

English

The main theme of the present study has been the elucidation of the pupil mechanism of fly photoreceptor cells. It is argued in chapter 0 that essential elements in this system must be: the waveguide properties of the rhabdomeres, the visual pigment, the change in membrane potential generated by photopigment conversion, the resulting potential gradient in the sense cell and finally the properties of the retinula cell pigment granula, the latter effectuating the pupil action. ... Zie: Summar

Proceedings - University of Groningen

   University of GroningenVisual receptor opticsStavenga, Doekele GerbenIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:1974Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Stavenga, D. G. (1974). Visual receptor optics: Rhodopsin and pupil in fly retinula cells. s.n.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 03-06-2022SUMMARYThe  ma in  t heme o f  t he  p resen t  s tudy  has  been  the  e luc i -d a t i o n  o f  t h e  p u p i l  m e c h a n i s m  o f  f l y  p h o t o r e c e p t o r  c e l 1 s .I t  i s  a rgued  i n  chap te r  0  t ha t  essen t i a l  e l emen ts  i nth i s  sys tem mus t  be :  t he  wavegu ide  p rope r t i es  o f  t he  rhab -domeres ,  t he  v i sua l  p i gmen t ,  t he  change  i n  membrane  po ten t i a lgene ra ted  by  pho top igmen t  conve rs ion ,  t he  resu l t i ng  po ten t -i a 1  g r a d i e n t  i n  t h e  s e n s e  c e l l  a n d  f i n a l l y  t h e  p r o p e r t i e so f  t h e  r e t i n u l a  c e l 1  p i g m e n t  g r a n u l a ,  t h e  l a t t e r  e f f e c t u -a t i n g  t h e  p u p i l  a c t i o n .A  number  o f  r e l evan t  t op i cs  has  been  tack led .  F i r s tf r om wavegu ide  op t i cs  i t  i s  i n fe r red  tha t  t he  re f rac t i ve  i n -dex  o f  f l y  r habdomeres  as  we l l  as  t ha t  o f  o the r  i nve r teb ra tep h o t . o r e c e p t o r s  c a n  b e  t a k e n  a s  1 . 3 6 5  +  0 . 0 0 6  ( c h a p t e r s  I  a n d2 ) .  T h i s  v a l u e  i s  a c h i e v e d  t h r o u g h  t h E  a p p l i c a t i o n  o f  as imp le  me thod  by  wh i ch  expe r imenEaL  re f rac t i ve  i nd i ces  canb e  c o r r e c t e d  f o r  w a v e g u i d e  e f f e c t s  ( c h a p t e r  I  )  .Fu r the rmore  i t  i s  conc luded  t . haE  the  con t r i bu t i on  o ft he  abso rb ing  v i sua l  p i gmen t  ch romophore  to  t he  re f rac t i veindex  can  be  neg lec ted  i n  f l y  pho to recep to rs  on  the  g roundo f  w a v e g u i d e  o p t i c a l  c o n s i d e r a t i o n s  ( c h a p t e r  3 ) .T h a t  f l y  v i s u a l  p i g m e n t  i s  a  p h o t o c h r o m e ,  i . e .  t h a t  i tc a n  e x i s t  i n  t w o  t h e r m o s t a b l e  s t a t e s ,  i s  s h o w n  i n  c h a p t e r s6  and  l ,  I t  hence  i s  access ib le  t o  a  gene ra l  me thod  deve lop -e d  i n  c h a p t e r  4 ,  w i t h  t h e  a i d  o f  w h i c h  t h e  a b s o r p t i o n  s p e c -t ra  o f  t he  two  s ta tes  o f  a  pho toch rome  can  be  de r i ved  f rome x p e r i m e n t a l  d i f f e r e n c e  s p e c t r a .The  expe r imen ta l  seE-up  and  the  app l i ed  me thods  andp r o c e d u r e s  a r e  p r e s e n l e d  i n  c h a p t e r  5 .D i f f e r e n c e  s p e c t r a  o b t a i n e d  f r o m  d i f f e r e n t  r h a b d o m e r e s ,a f t e r  c o r r e c t i o n  f o r  w a v e g u i d e  e f f e c t s ,  i n d i c a t e  t h a t  a l lf l y  p h o t o r e c e p t o r  c e l 1 s  c o n t a i n  o n e  a n d  t h e  s a m e  v i s u a lp i g m e n t ,  d e s c r i b e d  b y  p z a 9 5 3 y 5 3 g  ( c h a p t e r  7 ) .1 ' h e  s p e c t r a l  p r t p e r t i e t - o f  t h e  t w o  s t a t e s ,  r h o d o p s i na n d  m e t a r h o d o p s i n  r e s p e c t i v e l y ,  a r e  t h o u g h t  t o  b e  c l o s e l yr e l a t e d  t o  t h e  a b s o r b a n c e  s p e c E r u m  o f  E h e  p u p i l ,  w h i c h  p e a k si n  t h e  h l r r e  ( c h , a - * ^ -  r ' \  ^ +  L i  ^ L  i l  l u m i n a t i o n  i n t e n s i C i e s\ L r r q y L s r  w / .  n L  r r r E i t r8 5the  pup i l  i s  ac t i va ted  ow ing  to  t he  i n f l uence  o f  t he  pup i l  onthe  spec t ra l  compos i t i on  o f  t he  l i gh t  f l ux  i n  t he  rhabdom-e res ;  t he  pho toconve rs ion  o f  r hodops in  P495  i n to  me ta rhodop -s in M580 is  more hampered than the reverse t ransformat ion(chap te r  6 ) .  Th i s  e f f ec t  mus t  be  o f  p r ime  impor tance  fo rthe  v i sua l  p rocess  s ince  a  h igh  rhodops in  conve rs ion  ra teseve re l y  obs t ruc t s  subsequen t  da rk  adap ta t i on ,  as  f o l l owsf rom the  t ime  cou rse  o f  t he  pup i1 .  Da rk  adap ta t i on  on  thecon t ra ry  i s  acee le ra ted  by  me ta rhodops in  conve rs ion  i n torhodops in  ( chap te r  8 ) .Nex t  t o  t he  f unc t i on  o f  t he  pup i l  f o r  l i gh t -da rk  adap -ta t i on  t he re  i s  t he  h igh  p robab i l i t y  t ha t  i t  imp roves  thec o l o u r - v i s i o n  s y s t e m  o f  f l i e s  ( c f .  c h a p t e r s  6  a n d  7 ) .F ina l l y  we  l i ke  t o  po in t  ou t  t ha t  t he  evo l vemen t  o ft he  pup i l  i n  t he  pho to recep to r  ce l l s  o f  f l i es  may  exemp l i f yR o b e r t  B o y l e r s  s t a t e m e n t r r t h a E  t h e  e y e  o f  a  f l y  i s  a  m o r ecur ious p iece of  workmanship than the body of  the sun" buteven  so  the  l a t t e r t s  rad ia t i on  eve r  i s  needed  to  e i ve  t hev i s u a l  s y s t e m  o f  f l i e s  i t s  s e n s e .

Visual receptor optics:Rhodopsin and pupil in fly retinula cells

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Visual receptor optics:Rhodopsin and pupil in fly retinula cells

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