• Journal of Plant Biology
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• v.38 no.1
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• pp.87-93
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• 1995

For understanding physiological nature of phototaxis in Synechocystis sp. PCC 6803 PTX(S. 6803 PTX), we examined the effects of some metabolic inhibitors and cation ionophore on the phototactic movement. In the presence of DCMU, which blocks the photosynthetic electron transport just after photosystem II acceptor, there was no inhibitory effect on the phototaxis up to $100\;\mu\textrm{M}$. Instead, the respiratory electron chain inhibitor such as sodium azide dramatically impaired the phototaxis in S. 6803 PTX. These observations indicate that the phototaxis is linked not to photo-phosphorylation, but to respiratory phosphorylation. When the cells were treated with un couplers such as CCCP or DNP, which dissipate the electrochemical gradient of proton($\Delta\mu_{H}+$) across the cytoplasmic membrane, these chemicals did not affect phototaxis. In contrast, when cells were treated with DCCD or NBD which deprive cells of A TP but leave $\Delta\mu_{H}+$ intact across the membrane, the phototactic movement was severly reduced. These results imply that ATP production, not proton motive force, is involved in the phototactic movement in this organism as a driving motive force. The application of specific calcium ionophore A23187 strongly impaired positive phototaxis. Calcium fluxes should be engaged in the sensory trans-duction of phototactic orientation. Finally, when ethionine was supplimented to culture media, the photomovement of this organism was inhibited. This implies that methylation/demethylation mechanism controls the process of phototaxis in S. 6803 PTX like chemotaxis in E. coli and Salmonella typhimurium.murium.

• The Korean Journal of Zoology
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• v.20 no.1
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• pp.1-8
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• 1977

Several hundred flies of Drosophila melanogaster collected in Anyang City were selected for positive, negative and neutral directions during 15 generations. The population responded effectively to the artificial selection. The realized heritability estimated for the first 10 generations was $2 \\sim 4%$ per generation in the positive and negative phototaxis. The results of diallel crosses among selected populations indicated that some polygenes showing a negative phototaxis were partially dominant over polygenes controlled the positive phototaxis, and the dominant effect became greater in later generations. The populations selected for positive and negative phototaxis were relaxed after 15 generations of selection, and their phototactic responses were completely returned to their original states. Such phenomena would be explained by the genetic homeostasis resulted from an action of natural selection. It seems reasonable to assume that the phototactic neutrality of a natural population was maintained as an adaptive trait under natural environment.

• Journal of Photoscience
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• v.9 no.2
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• pp.287-289
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• 2002

Planarians show negative phototaxis and have extensive regenerative ability, including the ability to regenerate the brain. Recently the process of regeneration of the planarian brain has been divided into three steps based on the expression of neural markers. In this study, we have analyzed the process of recovery of the light response during head regeneration. Although morphological observations indicated that regeneration of the eyes and optic nerves appeared to be completed by the fourth day, the recovery of the evasion behavior against light was not recovered within 4 days after amputation. Functional recovery of the evasion behavior could be detected starting 5 days after amputation and then gradually recovered. We previously identified genes which are specifically expressed in the brain after the recovery of morphological structures. This characteristic suggested that these genes may be involved in functional recovery of the brain. To investigate the function of these genes, we performed gene knockout analysis using the RNA interference method. The results clearly indicated that these genes are involved in the functional recovery of the visual system.

• Proceedings of the Korean Society of Potoscience Conference
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• 2005.06a
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• pp.110-110
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• 2005

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.3
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• pp.245-257
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• 2020

Behavioral response to a diel photoperiodicity (500 lx for 16 h, 5 lx for 4 h and < 0.5 lx for 4 h) and phototactic characteristics in dark conditions were examined with Siberian sturgeon Acipenser baerii (Chondrostei, Actinopterygii) prelarvae. Siberian sturgeon prelarvae represented both qualitative and quantitative changes in their behavioral patterns according to different light intensities in a diel photoperiodicity. Under daylight conditions (500 lx), prelarvae displayed saltatory changes of behavioral features with ages (Day 0-Day 9) in a general order of swimming-up/drifting, swimming in the upper water column, benthic swimming with rheotaxis, schooling and post-schooling behavior. Compared to daylight conditions, prelarvae tended to show more benthic performances and quantitative reductions of schooling and post-schooling behaviors under dimlight conditions (5 lx). Under dark conditions (< 0.5 lx), prelarvae exhibited a fairly uniform behavioral pattern characterized by the benthic swimming across the bottom of the tank. From phototaxis tests under dark conditions, navigational responses of prelarvae to a spotlight illumination were quantitatively changed as their ages increased. The phototactic responses reached the peak on Day 2, continued until Day 4, and then gradually decreased until Day 8. A partial recovery of positive phototaxis was observed on Day 9. Data from this study suggest that the diel light cycle as well as the light intensity of each interval in the cycle should be considered as important components of a practical guide for evaluating fitness and developmental states of artificially propagated Siberian sturgeon prelarvae.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.108-108
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• 1999

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.2
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• pp.79-86
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• 1979

The phototaxis of common carp Cyprinus carpio was studied tinder laboratory conditions to find out distributional pattern of the fish under light gradient and to find the light intensity which causes the maximum gathering rate. The optimum light intensities were determined, The fish tended to escape from tile light source when the light intensity was stronger or weaker than a certain optimum value. The mean illumination intensity which caused the maximum gathering rate was 3.813lux (2.99-4.76 lux) in the daytime and 6.292 lux (5.0-7.89 lux) at night. The gathering rate of the fish could be divided into two types: reflex gathering rate and equilibrium gathering rate. The reflex gathering rate appeared quickly soon after lighting and gradually changed as time elapsed, while the equilibrium gathering rate was almost always constant.

• Journal of Photoscience
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• v.11 no.3
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• pp.89-94
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• 2004

Motile cyanobacterium Synechocystis sp. PCC 6803 cells show photomovement with respect to the light stimulus. Under lateral irradiation, Synechocystis displays a phototactic gliding movement toward the light source by a twodimensional random biased walk. Under vertical irradiation, Synechocystis decreased the frequency of mean vectorial gliding speed dependent on the applied fluence rate, whereas the deviation distribution width of the speed increased. This strongly suggests the involvement of photokinesis. Evidence for the cyanobacterial photokinesis was discussed in the previous report (Choi et al., 1999. Photochem. Photobiol. 70, 95-102) demonstrating that the gross scalar speed of vertically irradiating cells increased by about 50% compared with that of dark-adapted cells. In the visible wavelength range, Synechocystis cells showed a maximal photokinetic activity at 420 nm and a second maximal activity at 680 nm. The threshold action spectrum for the photokinesis resembles the absorption spectrum of chlorophyll with major differences in the phototaxis action spectrum at 560 nm and 660 nm. We postulate that the cyanobacterial photokinesis is powered by the energy-generating chlorophyll pigments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.274-282
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• 2019

Female Siberian sturgeon Acipenser baerii were crossed with male Russian sturgeon A. gueldenstaedtii and the development, ontogenetic behavior, and phototactic characteristics of the resultant hybrid prolarvae were examined. The fertilization rate of the hybrid group was similar to that of Siberian sturgeon (the maternal species), and the overall developmental characteristics of hybrid embryos were not significantly different from those of either parental species. The time window from first hatch to the completion of hatching was wider in Russian sturgeon than in Siberian and hybrid sturgeon groups. The prolarval viability of the hybrid group was similar to that of the maternal species, and significantly higher than that of the paternal species. Hybrid prolarvae displayed ontogenetic behavioral patterns that were quite similar to those of Siberian sturgeon. In an illumination preference test, hybrid prolarvae displayed significant positive phototaxis, similar to the maternal species, and clearly distinct from the negative phototactic character of the paternal species. Taken together, our data indicate that the prolarval traits of hybrid sturgeon from this cross more closely resemble those of the maternal than the paternal species.

• Fisheries and Aquatic Sciences
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• v.22 no.1
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• pp.4.1-4.10
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• 2019

Russian sturgeon (Acipenser gueldenstaedtii) is commercially important in Korea because its caviar is highly prized. Although the early ontogeny of the species has been described, behavioral modifications in response to various light intensities or diel photoperiodicity patterns have not been studied extensively. The objective of the present study was to examine the behavioral characteristics of hatchery-produced A. gueldenstaedtii prelarvae over a diel photoperiodic cycle. During a diel light cycle comprising 16 h of daylight (450 lx), 4 h of dim light (10 lx), and 4 h of darkness (< 1 lx), newly hatched A. gueldenstaedtii prelarvae exhibited negative phototaxis in daylight (day 0-day 2), and this early behavior was not significantly affected by changes of light intensities. Rheotactic and non-rheotactic aggregation into schools was typical between days 3 and 6. Under the diel light cycle conditions described, rheotaxis was not influenced by environmental light intensity as much as non-rheotactic schooling behavior. Post-schooling behavior, which progressed from day 7 to day 8, did not change significantly during the diel light cycle. The data from the present study could be of practical value in developing a visual guide for assessing the fitness and quality of Russian sturgeon prelarvae under diel light cycle conditions in hatcheries.