Neural pathways involved in mutual interactions between optic lobe circadian pacemakers in the cricketGryllus bimaculatus

Yukizane, M.; Tomioka, Kenji

doi:10.1007/bf01021580

Cited by 28 publications

(1 citation statement)

References 23 publications

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“…The lens optics and retinal structure suggest that the ocelli of G. bimaculatus are heavily under-focused with poor image quality (T Labhart, unpublished observations). A number of investigations in different cricket species proposed that the ocelli play a role in compound eye adaptation [35], entrainment of circadian rhythms ([36]; but see [37,38]) and phototaxis [39]. In other insects, ocelli provide compass cues based on polarized skylight (reviewed by [40]) or are horizon detectors that serve the control of head orientation and stabilize flight posture (reviewed by [41]).…”

Section: Introductionmentioning

confidence: 99%

Opsin evolution and expression in Arthropod compound Eyes and Ocelli: Insights from the cricket Gryllus bimaculatus

et al. 2012

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BackgroundOpsins are key proteins in animal photoreception. Together with a light-sensitive group, the chromophore, they form visual pigments which initiate the visual transduction cascade when photoactivated. The spectral absorption properties of visual pigments are mainly determined by their opsins, and thus opsins are crucial for understanding the adaptations of animal eyes. Studies on the phylogeny and expression pattern of opsins have received considerable attention, but our knowledge about insect visual opsins is still limited. Up to now, researchers have focused on holometabolous insects, while general conclusions require sampling from a broader range of taxa. We have therefore investigated visual opsins in the ocelli and compound eyes of the two-spotted cricket Gryllus bimaculatus, a hemimetabolous insect.ResultsPhylogenetic analyses place all identified cricket sequences within the three main visual opsin clades of insects. We assign three of these opsins to visual pigments found in the compound eyes with peak absorbances in the green (515 nm), blue (445 nm) and UV (332 nm) spectral range. Their expression pattern divides the retina into distinct regions: (1) the polarization-sensitive dorsal rim area with blue- and UV-opsin, (2) a newly-discovered ventral band of ommatidia with blue- and green-opsin and (3) the remainder of the compound eye with UV- and green-opsin. In addition, we provide evidence for two ocellar photopigments with peak absorbances in the green (511 nm) and UV (350 nm) spectral range, and with opsins that differ from those expressed in the compound eyes.ConclusionsOur data show that cricket eyes are spectrally more specialized than has previously been assumed, suggesting that similar adaptations in other insect species might have been overlooked. The arrangement of spectral receptor types within some ommatidia of the cricket compound eyes differs from the generally accepted pattern found in holometabolous insect taxa and awaits a functional explanation. From the opsin phylogeny, we conclude that gene duplications, which permitted differential opsin expression in insect ocelli and compound eyes, occurred independently in several insect lineages and are recent compared to the origin of the eyes themselves.

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Section: Introductionmentioning

confidence: 99%

Opsin evolution and expression in Arthropod compound Eyes and Ocelli: Insights from the cricket Gryllus bimaculatus

et al. 2012

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Optic lobe commissures in a three‐dimensional brain model of the cockroach Leucophaea maderae: A search for the circadian coupling pathways

Reischig

Stengl

2002

J of Comparative Neurology

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The circadian rhythm of locomotor activity in the cockroach Leucophaea maderae is controlled by bilaterally symmetric, apparently directly coupled, circadian pacemakers in the optic lobes. Strong evidence predicts that ventromedial to the medulla, the accessory medulla with associated pigment-dispersing hormone-immunoreactive neurons is this circadian clock. In search for direct coupling pathways between both clocks, we performed horseradish peroxidase backfills from one optic stalk as well as dextran and horseradish peroxidase injections into one accessory medulla. Seven commissures with projections in the contralateral optic lobe were identified and reconstructed. Three of these commissures connected both accessory medullae. Two of these resembled the arborization pattern of the pigment-dispersing hormone-immunoreactive neurons, which are circadian pacemaker candidates in insects. This finding suggests that some of these pacemaker candidates form a direct circadian coupling pathway. For better visualization of reconstructed commissures, we implemented the reconstructions into a three-dimensional model of the cockroach brain.

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Circadian Systems of Invertebrates

Page

2001

Handbook of Behavioral Neurobiology

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Neural pathways involved in mutual interactions between optic lobe circadian pacemakers in the cricketGryllus bimaculatus

Cited by 28 publications

References 23 publications

Opsin evolution and expression in Arthropod compound Eyes and Ocelli: Insights from the cricket Gryllus bimaculatus

Opsin evolution and expression in Arthropod compound Eyes and Ocelli: Insights from the cricket Gryllus bimaculatus

Optic lobe commissures in a three‐dimensional brain model of the cockroach Leucophaea maderae: A search for the circadian coupling pathways

Circadian Systems of Invertebrates

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