Action spectra for what was later understood to be rhodopsin <-> metarhodopsin conversions

I thought this figure deserved to be on this "selected cool findings" page for two reasons: (1) the early date (1975), and (2) the "heroic" nature of the experiments, electrophysiological recordings lasting for hours (Stark, J Comp Physiol 96, 343-356)

UV and blue sensitivity peaks in R1-6 are both mediated by the blue rhodopsin 1977

I was proud of this early (1977) demonstration that the UV peak was mediated through the blue rhodopsin (relevant to the hypothesis that UV sensitivity was mediated by a sensitizing retinoid) (Stark et al. J Comp Physiol 121, 289-305)

UV induced afterpotential and inactivation in Drosophila R7 photoreceptors 1977

After showing that vitamin A deprivation abolished the afterpotential and inactivation in R1-6 (Figure, text), I cranked up the sensitivity and showed the UV induced afterpotential and inactivation in R7 (Stark, J Comp. Physiol 115, 47-59, 1977)

5 ways to show it takes 15 to 16 (log quanta per sq cm) to convert Drosophila rhodopsin to metarhodopsin

From StarkWS, Frayer,KL and Johnson,MA, Photopigment and receptor properties in Drosophila compound eye and ocellar receptors. Biophysics of structure and mechanism, 1979, 5, 197-209 (Invited review to accompany European Neurosciences Association 1978 Meeting presentation)

Ommatidium, pseudocartridge, cartridge
Retinula cells of the ommatidium (top), the axons (pseudocartridge, middle right) and the R1-6 terminals (bottom) are pristine despite the lack of R1-6 opsin (ora was later shown by the O'Tousa lab to be a nonsense mutant at about 220 in the coding sequence). Arrows (in the top figure) are belt desmosomes. Semper (cone) cell processes are clearly seen just in from the belt desmosomes between R8&R2, R3&R4, and R5&R6; A 4th is seen (but less clearly) between R7 and R1. Arrows in the bottom are sites of synapses with T-shaped membrane specializations. (from DIS [Drosophila Information Service] 61, 1985, 162-164, Stark and Carlson, "Retinal degeneration in rdgBKS222 is blocked by oraJK84 which lacks photoreceptor organelles.")

12 log unit dynaqmic range from visual threshold to light damage for Drosophiola retina
From Stark,WS, Christianson,JS,Maier,L, and Chen,D-M. Inherited and environmentally induced retinal degeneration in Drosophila.In Retinal Degenerations. Stockholm Retinal Degenerations Satellite Symposium Proceedings Book (eds REAnderson, JGHollyfield, and MMLaVail) Boca Raton, CRC Press, 1991, pp. 61-75

New (in 2010)Q Imaging camera in my microscope lab

I noticed that these did not open in Safari, and in Firefox, they downloaded and converted to work
here is a movie I made of rhodopsin to metarhodopsin conversion with blue light
Here is a movie I made of the autofluorescence increase induced by bright blue light
Here is a movie I made of a focus series for GFP in ninaE Rh1-GFP flies

Light damages Rh1-GFP driven by ninaE

George Denny workd on GGA knockdowns in 2010 that had been in the light 17 days earlier. The movie shows substantial structural abnormality later shown not to depend on the GGA knockdown but to be attributed to ninaE Rh1-GFP

This page was last updated on June 15, 2016

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