2005 Fiscal Year Final Research Report Summary
Analysis of color vision mechanism in a microbrain
| Project/Area Number |
14204080
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | Yokohama City University |
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Principal Investigator |
ARIKAWA Kentaro Yokohama City Univ, Grad Sch Integ Sci, Professor, 大学院・国際総合科学研究科, 教授 (20167232)
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| Project Period (FY) |
2002 – 2005
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| Keywords | Insect / Compound eye / Visual behavior / Visual center / Color vision / Color constancy / Color induction / Microbrain |
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| Research Abstract |
1)Mechanism of wavelength information processing in the Papilio visual system
Firstly, we analyzed the spectral origin of characteristic broadband receptors in the Papilio retina. The broadband receptors were shown to coexpress green-absorbing and orange-absorbing visual pigment both functioning at the same time. Secondly, we carried out detailed anatomy of the first optic ganglion, the lamina, at the EM level. There we found numerous interphotoreceptor connections in addition to the synaptic connections between photoreceptors and second order visual interneurons. Observation of serial EM sections revealed that the pattern of interphotoreceptor connection is different among three types of spectrally heterogeneous ommatidia. Thirdly we initiated an immunocytochemical analysis of the Papilio brain using specific antibodies against neurotransmitter candidates, such as serotonin, tyramine, histamine, and GABA, etc.
2)Behavioral analysis of color vision function in Papilio
We established an ex
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perimental method to let Papilio to discriminate monochromatic lights. By using the protocol we measured the action spectrum of foraging flight as well as proboscis extension. It appeared that Papilio could actually see the light of the wavelength range of 300-700nm. We also established a Y-maze experiment protocol to make Papilio to discriminate two stimuli from certain distance. We thus measured the minimum visual angle for color detection of foraging Papilio : they could discriminate color of the target whose diameter is about 1 degree. The size is comparable to their special resolution limit. We also carried out some preliminary experiments to check their wavelength discrimination ability and the 'color-mixture' phenomenon, etc.
3)Compound eye structure in insects other than Papilio
We carried out a comparative anatomy and physiology of insect compound eyes, using the small white butterfly, Pieris rapae crucivora, and the honeybee, Apis mellifera. By localizing mRNAs encoding visual pigment opsins in the retina, we found the eyes of both species consist of three types of spectrally distinct ommatidia as in Papilio. We further analyzed photoreceptor spectral sensitivities in Pieris. The Pieris eyes have three classes of long wavelength receptors, green, red, and deep-red receptors, all share a visual pigment PrL. The difference hi the spectral sensitivities is attributable to the filtering effect of perirhabdomeral pigments that absorb boundary wave of light propagating the slender rhabdom. Less
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Research Products
(49 results)
