|
| ||
|
|
||
Chromatic Adaptation (chromatic + adaptation)
Selected AbstractsN2 -fixation and complementary chromatic adaptation in non-heterocystous cyanobacteria from Lake ConstanceFEMS MICROBIOLOGY ECOLOGY, Issue 2 2001Christine Postius Abstract Non-heterocystous, mostly filamentous cyanobacteria were isolated from the crust of stones, from the periphyton of two macrophytes from the littoral zone and from the pelagic environment of Lake Constance. All isolates were cultivated as unialgal strains. DNA analysis by restriction fragment length polymorphism with the psbA gene probe revealed high genetic diversity among the strains from the littoral zone. For all genotypes, the occurrence of the nifH gene encoding a nitrogenase subunit and of genes encoding subunits of phycoerythrin and phycocyanin were tested by Southern blot hybridization. In addition, the isolates were investigated for their ability for complementary chromatic adaptation (CCA) and for anaerobic N2 -fixation. With respect to these characteristics, all cyanobacteria included in this study were assigned to four different types: (1) strains without the capability to fix N2 or to perform CCA of the group III type (CCA III); (2) strains which show both features; (3) strains with the ability to fix nitrogen, but that do not show any CCA III; and (4) strains that produce phycoerythrin, but without the capacity for CCA III or N2 -fixation. By examining the frequency distribution of isolates, these types were shown to prefer different habitats. While cyanobacterial strains capable of N2 -fixation, but without CCA III, were mainly obtained from stone crusts in the supralittoral zone, those with the potential for N2 -fixation as well as for CCA III were largely isolated from submersed macrophytes. Cyanobacteria that produce phycoerythrin, but do not perform CCA III or N2 -fixation, were found in the pelagic zone only. [source] LIGHT REGULATION OF PHYCOBILISOME BIOSYNTHESIS AND CONTROL BY A PHYTOCHROME-LIKE PHOTORECEPTORJOURNAL OF PHYCOLOGY, Issue 2000K. Terauchi Ambient light quality changes dramatically affect the composition of light harvesting structures, the phycobilisomes, in many cyanobacterial species. In the cyanobacterium Fremyella diplosiphon, shifts in the ratio of red to green light lead to transcriptional changes and altered synthesis of several phycobilisome components. This process is called complementary chromatic adaptation (CCA). These two colors have opposite effects: red light activates an operon encoding the biliprotein phycocyanin (PC) and inactivates the operon encoding phycoerythrin (PE), whereas green light activates PE synthesis and shuts down PC synthesis. The effects of red and green light on CCA are photoreversible. Thus, CCA is similar to transcriptional processes that are controlled by phytochromes, a family of eukaryotic red/far red photoreversible photoreceptors. We are using molecular genetics to determine the mechanisms by which F. diplosiphon senses changes in the color of light of its environment. Initial mutant generation and complementation lead to the discovery of three CCA regulatory components that are part of a complex two component system. The most interesting of these is RcaE (regulator of chromatic adaptation), a histidine kinase-class protein containing a region in its amino-terminal half with similarity to the chromophore binding domains of phytochromes. Within this region, RcaE contains a cysteine residue in a similar location as that used for covalent attachment of the open-chain tetrapyrrole chromophore in phytochromes. We will present recent data characterizing RcaE, including in vivo analysis of the chromophore that is attached to RcaE, as well as results from our recent isolation of a new CCA regulatory component. [source] The Regulation of Motile Activity in Fish ChromatophoresPIGMENT CELL & MELANOMA RESEARCH, Issue 5 2000RYOZO FUJII Chromatophores, including melanophores, xanthophores, erythrophores, leucophores and iridophores, are responsible for the revelation of integumentary coloration in fish. Recently, blue chromatophores, also called cyanophores, were added to the list of chromatophores. Many of them are also known to possess cellular motility, by which fish are able to change their integumentary hues and patterns, thus enabling them to execute remarkable or subtle chromatic adaptation to environmental hues and patterns, and to cope with various ethological encounters. Such physiological color changes are indeed crucial for them to survive, either by protecting themselves from predators or by increasing their chances of feeding. Sometimes, they are also useful in courtship and mutual communications among individuals of the same species, leading to an increased rate of species survival. Such strategies are realized by complex mechanisms existing in the endocrine and/or nervous systems. Current studies further indicate that some paracrine factors such as endothelins (ETs) are involved in these processes. In this review, the elaborate mechanisms regulating chromatophores in these lovely aquatic animals are described. [source] Development of chromatic adaptation transforms and concept for their classificationCOLOR RESEARCH & APPLICATION, Issue 3 2006Yoshinobu NayataniArticle first published online: 7 APR 200 Abstract Three types of international recommendations are necessary on CATs (chromatic adaptation transforms). CAT-Type I and CAT-Type II are for general use on chromatic adaptation studies. The former is related to chromatic adaptation theory and the latter to performance on field trial data. In addition, CAT-Type III is necessary for a specific and practical purposes. The need for classifying to CAT-Type I and CAT-Type II is found from a careful inspection of the development process from Nayatani et al. transform to BFD transform, referring to the Ph. D. thesis by Lam (University of Bradford, 1985). The process clearly shows two types of flows on the development of various CATs. One is the flow for deepening the theory of chromatic adaptation (CAT-Type I), and the other is for giving good performance to existing field trial data and also ease of use (CAT-Type II). Additional CAT-Type III is, for example, CAT recommended in CIE TC 8-04 technical report. The CAT is only applicable to compare hardcopy and softcopy images for the specified observing conditions in the report. Still, a difficult problem, determination of corresponding colors, remains in the method of subjective estimation, which is useful and widely used for estimating chromatic adaptation effects experimentally. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 205,217, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20210 [source] | ||||||||||