Absorption Spectra of Planarian Visual Pigments and Two States of the Metarhodopsin Intermediates

Azuma, Katsu; Iwasaki, Naoko; Ohtsu, Kohzoh

doi:10.1111/j.1751-1097.1999.tb05312.x

Cited by 13 publications

(10 citation statements)

References 18 publications

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“…The behavior trial lasted 18 h and consisted of the following settings. Background illumination in all quadrants was 50 lm red light, which is undetectable to planarians given their photoreceptor profiles (Azuma, Iwasaki, & Ohtsu, ; Brown & Ogden, ). In addition, half of the arena is illuminated by 420 lm blue light, giving the animals a choice between “light” and “dark” halves of the environment.…”

Section: Methodsmentioning

confidence: 99%

Planarian regeneration in space: Persistent anatomical, behavioral, and bacteriological changes induced by space travel

et al. 2017

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Regeneration is regulated not only by chemical signals but also by physical processes, such as bioelectric gradients. How these may change in the absence of the normal gravitational and geomagnetic fields is largely unknown. Planarian flatworms were moved to the International Space Station for 5 weeks, immediately after removing their heads and tails. A control group in spring water remained on Earth. No manipulation of the planaria occurred while they were in orbit, and space‐exposed worms were returned to our laboratory for analysis. One animal out of 15 regenerated into a double‐headed phenotype—normally an extremely rare event. Remarkably, amputating this double‐headed worm again, in plain water, resulted again in the double‐headed phenotype. Moreover, even when tested 20 months after return to Earth, the space‐exposed worms displayed significant quantitative differences in behavior and microbiome composition. These observations may have implications for human and animal space travelers, but could also elucidate how microgravity and hypomagnetic environments could be used to trigger desired morphological, neurological, physiological, and bacteriomic changes for various regenerative and bioengineering applications.

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Section: Methodsmentioning

confidence: 99%

Planarian regeneration in space: Persistent anatomical, behavioral, and bacteriological changes induced by space travel

et al. 2017

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“…The trajectory of movement was analyzed with SMART software (Panlab) (Figure 1 C) [ 6 ]. All behavioral experiments were performed in a dark room with only a red light of a wavelength that cannot be sensed by planarians (Figure 1 C) [ 18 ]. Calculations based on the data obtained were performed using static ggplot2 package of R software [ 19 ].…”

Section: Methodsmentioning

confidence: 99%

Planarian shows decision-making behavior in response to multiple stimuli by integrative brain function

et al. 2015

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IntroductionPlanarians belong to an evolutionarily early group of organisms that possess a central nervous system including a well-organized brain with a simple architecture but many types of neurons. Planarians display a number of behaviors, such as phototaxis and thermotaxis, in response to external stimuli, and it has been shown that various molecules and neural pathways in the brain are involved in controlling these behaviors. However, due to the lack of combinatorial assay methods, it remains obscure whether planarians possess higher brain functions, including integration in the brain, in which multiple signals coming from outside are coordinated and used in determining behavioral strategies.ResultsIn the present study, we designed chemotaxis and thigmotaxis/kinesis tracking assays to measure several planarian behaviors in addition to those measured by phototaxis and thermotaxis assays previously established by our group, and used these tests to analyze planarian chemotactic and thigmotactic/kinetic behaviors. We found that headless planarian body fragments and planarians that had specifically lost neural activity following regeneration-dependent conditional gene knockdown (Readyknock) of synaptotagmin in the brain lost both chemotactic and thigmotactic behaviors, suggesting that neural activity in the brain is required for the planarian's chemotactic and thigmotactic behaviors. Furthermore, we compared the strength of phototaxis, chemotaxis, thigmotaxis/kinesis, and thermotaxis by presenting simultaneous binary stimuli to planarians. We found that planarians showed a clear order of predominance of these behaviors. For example, when planarians were simultaneously exposed to 400 lux of light and a chemoattractant, they showed chemoattractive behavior irrespective of the direction of the light source, although exposure to light of this intensity alone induces evasive behavior away from the light source. In contrast, when the light intensity was increased to 800 or 1600 lux and the same dose of chemoattractant was presented, planarian behaviors were gradually shifted to negative phototaxis rather than chemoattraction. These results suggest that planarians may be capable of selecting behavioral strategies via the integration of discrete brain functions when exposed to multiple stimuli.ConclusionsThe planarian brain processes external signals received through the respective sensory neurons, thereby resulting in the production of appropriate behaviors. In addition, planarians can adjust behavioral features in response to stimulus conditions by integrating multiple external signals in the brain.Electronic supplementary materialThe online version of this article (doi:10.1186/s40851-014-0010-z) contains supplementary material, which is available to authorized users.

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“…The pigment cells are arranged into a semilunar eyecup, while the visual bipolar neurons are located outside of the eyecup. Dendrites from the visual neurons distribute inside of the pigment eyecup to form a rhabdomeric structure containing opsins (Asano et al ., 1998;Orii et al ., 1998;Azuma et al ., 1999;. The axons of the visual neurons project caudally onto the dorso-medial region of the brain and some of the fibers form an optic chiasma, which integrates photosensory inputs from the left and right sides of the animal (Agata et al ., 1998;Sakai et al ., 2000).…”

Section: Introductionmentioning

confidence: 99%

Morphological and Functional Recovery of the Planarian Photosensing System during Head Regeneration

et al. 2004

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Absorption Spectra of Planarian Visual Pigments and Two States of the Metarhodopsin Intermediates

Cited by 13 publications

References 18 publications

Planarian regeneration in space: Persistent anatomical, behavioral, and bacteriological changes induced by space travel

Planarian regeneration in space: Persistent anatomical, behavioral, and bacteriological changes induced by space travel

Planarian shows decision-making behavior in response to multiple stimuli by integrative brain function

Morphological and Functional Recovery of the Planarian Photosensing System during Head Regeneration

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