Color adaptation for anomalous trichromats

AbstractIn the butterfly Inachis io, a pupal melanization reducing factor (PMRF) which is located throughout the entire central nervous system controls the intensity of pigmentation of pupal cuticle depending on the background color of the pupation site. PMRF does not only reduce melanization but, in addition, enhances lutein incorporation in a dose-dependent manner to form pupae with yellow color on bright backgrounds.The present paper reports on the effects on pupal pigmentation caused by cyclic nucleo tides and phosphodiesterase (PDE) inhibitors which prevent degradation of cyclic nucleo tides. The injection of cAMP did not alter pupal coloration whereas its membrane-permeable analog dibutyryl-cAMP mimicked dose-dependently PMRF activity. Thus, pupae of reduced melanization and, in addition, enhanced yellow coloration were formed. This indicates that an increased intracellular cAMP level is capable of mediating PMRF effect. Also, the injection of the PDE inhibitor isobutylmethylxanthine (IBMX) caused dose-dependently pupae of reduced melanization and enhanced lutein incorporation.Theophylline (another PDE inhibitor) was only slightly effective (23% inhibition of melanization) at the highest dose compared to IBMX. The injection of cGMP and its analog dibutyryl-cGMP exhibited no melanization reducing effect.Extracts of abdominal ganglia (AG) which contained PMRF activity caused significantly brighter pupae when injected in combination with IBMX. However, this stimulation by IBMX became no longer effective at higher AG doses. Therefore, the present results are suggestive of an involvement of cAMP as a second messenger in the action of PMRF on pupal color adaptation.

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Parallel Seed Color Adaptation during Multiple Domestication Attempts of an Ancient New World Grain

Molecular Biology and Evolution ◽

10.1093/molbev/msz304 ◽

2019 ◽

Vol 37 (5) ◽

pp. 1407-1419 ◽

Cited By ~ 5

Author(s):

Markus G Stetter ◽

Mireia Vidal-Villarejo ◽

Karl J Schmid

Keyword(s):

Genomic Region ◽

Color Variation ◽

Chromosome 9 ◽

Seed Color ◽

Color Adaptation ◽

Crop Species ◽

Grain Amaranth ◽

Amaranth Species ◽

Genomic Regions ◽

Selection Of

Abstract Thousands of plants have been selected as crops; yet, only a few are fully domesticated. The lack of adaptation to agroecological environments of many crop plants with few characteristic domestication traits potentially has genetic causes. Here, we investigate the incomplete domestication of an ancient grain from the Americas, amaranth. Although three grain amaranth species have been cultivated as crop for millennia, all three lack key domestication traits. We sequenced 121 crop and wild individuals to investigate the genomic signature of repeated incomplete adaptation. Our analysis shows that grain amaranth has been domesticated three times from a single wild ancestor. One trait that has been selected during domestication in all three grain species is the seed color, which changed from dark seeds to white seeds. We were able to map the genetic control of the seed color adaptation to two genomic regions on chromosomes 3 and 9, employing three independent mapping populations. Within the locus on chromosome 9, we identify an MYB-like transcription factor gene, a known regulator for seed color variation in other plant species. We identify a soft selective sweep in this genomic region in one of the crop species but not in the other two species. The demographic analysis of wild and domesticated amaranths revealed a population bottleneck predating the domestication of grain amaranth. Our results indicate that a reduced level of ancestral genetic variation did not prevent the selection of traits with a simple genetic architecture but may have limited the adaptation of complex domestication traits.

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Single and Multiple Visual Systems in Arthropods

The Journal of General Physiology ◽

10.1085/jgp.51.2.125 ◽

1968 ◽

Vol 51 (2) ◽

pp. 125-156 ◽

Cited By ~ 65

Author(s):

George Wald

Keyword(s):

Spectral Sensitivity ◽

Visual Pigment ◽

Light Adaptation ◽

Procambarus Clarkii ◽

Color Discrimination ◽

Visual Pigments ◽

Green Crab ◽

Spider Crab ◽

Color Adaptation ◽

Visual Systems

Extraction of two visual pigments from crayfish eyes prompted an electrophysiological examination of the role of visual pigments in the compound eyes of six arthropods. The intact animals were used; in crayfishes isolated eyestalks also. Thresholds were measured in terms of the absolute or relative numbers of photons per flash at various wavelengths needed to evoke a constant amplitude of electroretinogram, usually 50 µv. Two species of crayfish, as well as the green crab, possess blue- and red-sensitive receptors apparently arranged for color discrimination. In the northern crayfish, Orconectes virilis, the spectral sensitivity of the dark-adapted eye is maximal at about 550 mµ, and on adaptation to bright red or blue lights breaks into two functions with λmax respectively at about 435 and 565 mµ, apparently emanating from different receptors. The swamp crayfish, Procambarus clarkii, displays a maximum sensitivity when dark-adapted at about 570 mµ, that breaks on color adaptation into blue- and red-sensitive functions with λmax about 450 and 575 mµ, again involving different receptors. Similarly the green crab, Carcinides maenas, presents a dark-adapted sensitivity maximal at about 510 mµ that divides on color adaptation into sensitivity curves maximal near 425 and 565 mµ. Each of these organisms thus possesses an apparatus adequate for at least two-color vision, resembling that of human green-blinds (deuteranopes). The visual pigments of the red-sensitive systems have been extracted from the crayfish eyes. The horse-shoe crab, Limulus, and the lobster each possesses a single visual system, with λmax respectively at 520 and 525 mµ. Each of these is invariant with color adaptation. In each case the visual pigment had already been identified in extracts. The spider crab, Libinia emarginata, presents another variation. It possesses two visual systems apparently differentiated, not for color discrimination but for use in dim and bright light, like vertebrate rods and cones. The spectral sensitivity of the dark-adapted eye is maximal at about 490 mµ and on light adaptation, whether to blue, red, or white light, is displaced toward shorter wavelengths in what is essentially a reverse Purkinje shift. In all these animals dark adaptation appears to involve two phases: a rapid, hyperbolic fall of log threshold associated probably with visual pigment regeneration, followed by a slow, almost linear fall of log threshold that may be associated with pigment migration.

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Novel calibration and color adaptation schemes in three-fringe RGB photoelasticity

Optics and Lasers in Engineering ◽

10.1016/j.optlaseng.2014.10.007 ◽

2015 ◽

Vol 66 ◽

pp. 320-329 ◽

Cited By ~ 13

Author(s):

Digendranath Swain ◽

Binu P. Thomas ◽

Jeby Philip ◽

S. Annamala Pillai

Keyword(s):

Color Adaptation ◽

Rgb Photoelasticity

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