Three opsin-encoding cDNAS from the compound eye of Manduca sexta

Area of Science:

• * Molecular Biology
• * Neuroscience
• * Entomology

Background:

• * The visual system of insects relies on opsins, the light-sensitive proteins within photoreceptor cells.
• * Understanding opsin diversity is crucial for deciphering insect vision and evolution.
• * The sphingid moth Manduca sexta possesses a complex visual system with multiple photoreceptor types.

Purpose of the Study:

• * To isolate and characterize novel opsin-encoding cDNAs from the Manduca sexta retina.
• * To determine the phylogenetic relationships and spectral sensitivities of these opsins.
• * To correlate identified opsins with known rhodopsins in Manduca sexta.

Main Methods:

• * Isolation of three distinct opsin-encoding cDNAs (MANOP1, MANOP2, MANOP3) using molecular cloning techniques.
• * Sequence analysis to determine protein characteristics and phylogenetic relationships.
• * Correlation of cDNA sequences with known spectral properties of Manduca sexta rhodopsins (P520, P450, P357).

Main Results:

• * MANOP1 exhibits sequence similarity to long-wavelength-sensitive arthropod photopigments.
• * MANOP2 and MANOP3 belong to a group of insect visual pigments associated with short-wavelength absorption.
• * Evidence suggests MANOP1 encodes the P520 (green-sensitive) opsin, MANOP2 encodes P357 (UV-sensitive), and MANOP3 encodes P450 (blue-sensitive).

Conclusions:

• * Manduca sexta possesses at least three distinct opsins, reflecting its trichromatic visual system.
• * The identified opsins (MANOP1, MANOP2, MANOP3) are likely responsible for the different spectral sensitivities observed in the moth's retina.
• * This study provides molecular insights into the opsin repertoire and visual processing in a key insect model.