Highlights • Pigment patterns of zebrafish exhibit the specific dynamic characteristics of a Turing pattern. • Pigmentation patterns arise from the interactions among two/three types of pigment cell. • Tuning of cell–cell interactions changes the pattern from stripes to a variety of other patterns. • The identified mechanism satisfies the necessary conditions of Turing pattern formation. More than half a century ago, Alan Turing postulated that pigment patterns may arise from a mechanism that could be mathematically modeled based on the diffusion of two substances that interact with each other. Over the past 15 years, the molecular and genetic tools to verify this prediction have become available. Here, we review experimental studies aimed at identifying the mechanism underlying pigment pattern formation in zebrafish. Extensive molecular genetic studies in this model organism have revealed the interactions between the pigment cells that are responsible for the patterns. The mechanism discovered is substantially different from that predicted by the mathematical model, but it retains the property of ‘local activation and long-range inhibition’, a necessary condition for Turing pattern formation. Although some of the molecular details of pattern formation remain to be elucidated, current evidence confirms that the underlying mechanism is mathematically equivalent to the Turing mechanism.
An interface unit 4 for a game machine 1 includes a monitor 10 having a single display surface 10a, and an input module 11 serving as an input device overlaid on the display surface 10a, wherein a plurality of push button panels 16, each of which has a panel main body with enough transparency to allow a screen image on the display surface 10a to be visually seen, partitions the unit 4 into input display parts 4a, which are arranged on partial regions of the display surface 10a in a push-down operable manner, and a multi purpose display part 4b for displaying a screen image with a different purpose from that of the input display parts 4a.
Positions of a plurality of objects in a space are detected. A position of reflected light of an object passing through an infrared screen is specified by analyzing an image obtained by selectively imaging the infrared rays. When the infrared screen is formed in front the display, reflected light is only caused just in front of the display. When the infrared rays are selectively imaged, a picture displayed with visible light is separated from reflected light in the infrared region, and only the reflected light can be imaged. A position of the reflected light on the display can be specified by a publicly known image analysis technique.
A push button panel 16, which has a transparent panel main body 16a for allowing a screen image on a display surface 10a to be visually seen, is disposed for each void part 15b between opaque frames 15a of a lattice panel 15 disposed on the display surface 10a of a monitor 10. Extended parts 16c are disposed at the four corners of an outer circumference of the push button panel 16, such that they are extending outwardly in the diagonal directions, and these extended parts 16c are fitted to recessed parts 15c provided at the four corners of an void part 15b of the lattice panel 15 . A rubber contact 17, in which electrodes functioning as detecting means are embedded in an elastic body functioning as supporting means, is disposed at a lower surface side of each extended part 16c.
Mutation in the inward rectifier potassium channel gene, kir7.1, was previously identified as being responsible for the broader stripe zebrafish skin pattern mutant,jaguar/obelix. An amino acid substitution in this channel causes a broader stripe pattern than that of wild type zebrafish. In this study we analyzed cichlid homologs of the zebrafish kir7.1 gene. We identified two kinds of homologous genes in cichlids and named them cikir7.1 and cikir7.2. Southern hybridization using cichlid genome revealed that cichlids from the African Great Lakes, South America and Madagascar have two copies of the gene. Cichlids from Sri Lanka, however, showed only one band in this experiment. Database analysis revealed that only one copy of the kir7.1 gene exists in the genomes of the teleosts zebrafish, tetraodon, takifugu, medaka and stickleback. The deduced amino acid sequence of cikir7.1 is highly conserved among African cichlids, whereas that of cikir7.2 has several amino acid substitutions even in conserved transmembrane domains. Gene expression analysis revealed that cikir7.1 is expressed specifically in brain and eye, and cikir7.2 in testis and ovary, zebrafish kir7.1, however, is expressed in brain, eye, skin, caudal fin, testis and ovary. These results suggest that gene duplication of the cichlid kir7.1 occurred in a common ancestor of the family Cichlidae, that the function of parental kir7.1 was then divided into two genes, cikir7.1 and cikir7.2, and that the evolutionary rate of cikir7.2 might have been accelerated, thereby effecting functional diversification in the cichlid lineage. Thus, the evolution of kir7.1 genes in cichlids provides a typical example of gene duplication-one gene is conserved while the other becomes specialized for a novel function. (C) 2007 Published by Elsevier B.V.
Mutation in the inward rectifier potassium channel gene, kir7.1, was previously identified as being responsible for the broader stripe zebrafish skin pattern mutant, jaguar/obelix. An amino acid substitution in this channel causes a broader stripe pattern than that of wild type zebrafish. In this study we analyzed cichlid homologs of the zebrafish kir7.1 gene. We identified two kinds of homologous genes in cichlids and named them cikir7.1 and cikir7.2. Southern hybridization using cichlid genome revealed that cichlids from the African Great Lakes, South America and Madagascar have two copies of the gene. Cichlids from Sri Lanka, however, showed only one band in this experiment. Database analysis revealed that only one copy of the kir7.1 gene exists in the genomes of the teleosts zebrafish, tetraodon, takifugu, medaka and stickleback. The deduced amino acid sequence of cikir7.1 is highly conserved among African cichlids, whereas that of cikir7.2 has several amino acid substitutions even in conserved transmembrane domains. Gene expression analysis revealed that cikir7.1 is expressed specifically in brain and eye, and cikir7.2 in testis and ovary; zebrafish kir7.1, however, is expressed in brain, eye, skin, caudal fin, testis and ovary. These results suggest that gene duplication of the cichlid kir7.1 occurred in a common ancestor of the family Cichlidae, that the function of parental kir7.1 was then divided into two genes, cikir7.1 and cikir7.2, and that the evolutionary rate of cikir7.2 might have been accelerated, thereby effecting functional diversification in the cichlid lineage. Thus, the evolution of kir7.1 genes in cichlids provides a typical example of gene duplication—one gene is conserved while the other becomes specialized for a novel function.
An abstract of the article "Design and Performance of the Okazaki Large Spectrograph for Photobiological Research," by M. Watanabe, M. Furuya, Y. Miyoshi, Y. Inoue, I. Iwahashi, and K. Matsumoto is presented.
The phototactic response of cells of Cryptomonas sp. to stimulation with continuous or intermittent lateral light was determined by an individual cell method using photomicrography and videomicrography. The cells showed positive phototaxis under the conditions studied. The phototactic orientation of individual cells was induced most effectively by irradiation with light of 570 nm; blue light was less effective and no orientation occurred in red light. An intermittent stimulus regime with a long dark interval (250 ms) elicited a weaker phototactic orientation than did a regime with a short dark interval (63 ms), irrespective of the duration of light pulses (16, 250 and 1000 ms). The swimming rate was .apprx. 240 .mu.m s-1 and the rotation period .apprx. 450 ms in the dark, neither of which was greatly affected by stimulation with continuous or intermittent light. Neither step-up nor step-down photophobic responses occurred at the time of onset or removal of the light stimulus under the experimental conditions. The swimming direction of individual cells became gradually oriented toward the light source. Phototactic response was detectable within 4 s after the onset of light stimulation, reaching a saturation level after > 30 s.
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