Microscopy of multiple visual receptor types in Drosophila

Area of Science:

• * Molecular and Cellular Biology
• * Neuroscience
• * Vision Science

Background:

• * Drosophila melanogaster possesses six distinct rhodopsins (Rh1-Rh6), each contributing to visual perception.
• * Understanding the specific roles and properties of these rhodopsins is crucial for deciphering visual processing in insects.

Purpose of the Study:

• * To characterize the properties of individual Drosophila rhodopsins (Rh1-Rh6) using advanced microscopic techniques.
• * To investigate rhodopsin autofluorescence and imaging properties in transgenic fly models.
• * To differentiate the contributions of various rhodopsins to photoreceptor function, particularly in R7 cells.

Main Methods:

• * Utilized standard and confocal microscopy with the pseudopupil technique to image rhabdomeres in live Drosophila.
• * Employed transgenic Drosophila strains with specific rhodopsins (Rh2-Rh6) replacing native Rh1, alongside controls expressing Rh1.
• * Analyzed green fluorescent protein (GFP) reporter expression driven by Rh1, Rh3, and Rh4 promoters to distinguish R7/8 photoreceptor types.

Main Results:

• * Visual pigment exhibited pink coloration in white light, notably for Rh1 and Rh6.
• * Rh6 demonstrated unique spectral properties where rhodopsin and metarhodopsin could not be spectrally separated.
• * Bright autofluorescence in R7 rhabdomeres was attributed to the presence of Rh4, not relative fluorescent emission levels.

Conclusions:

• * Advanced microscopic imaging is a valuable tool for analyzing Drosophila rhodopsins.
• * The study successfully identified the cellular sources of bright and dim R7 rhabdomeres.
• * Unique spectral characteristics of Rh6 were elucidated, contributing to a deeper understanding of its function.