The retinal pigment epithelium (RPE) is a specialized epithelium at the back of the eye that carries out a variety of functions essential for visual health. Recent studies have advanced our molecular understanding of one of the major functions of the RPE; phagocytosis of spent photoreceptor outer segments (POS). Notably, a mechanical link, formed between apical integrins bound to extracellular POS and the intracellular actomyosin cytoskeleton, is proposed to drive the internalization of POS. The process may involve a “nibbling” (...) action, as an initial step, to sever outer segment tips. These insights have led us to hypothesize an “integrin adhesome‐like” network, atypically assembled at apical membrane RPE‐POS contacts. I propose that this hypothetical network orchestrates the complex membrane remodeling events required for particle internalization. Therefore, its analysis and characterization will likely lead to a more comprehensive understanding of the molecular mechanisms that control POS phagocytosis. (shrink)

This article draws on insights of young people learning to make natural pigments and traditional paintings in acute climate vulnerable areas. Why do they paint during ongoing crises and how do they voice their future concerns? Critical realism is applied as a meta-theory in this field-based study in a slum area in Kolkata and the Sundarbans mangrove forest. Methods comprise focus groups, semi-structured interviews, and participant observation. Analysis was done in an abductive process, applying Roy Bhaskar’s model of ‘four-planar social (...) being’. The analysis demonstrates how painting with natural pigments leads the young ones towards: (a) discovering beauty in nature (b) transcendence of borders (c) transformation and responsible action (d) discovering one’s own dignity. Findings are discussed considering the key concepts co-presence and crisis system. I reflect upon how this local effort can inspire a new economy, with the signposts: becoming co-present with the natural world and the necessity of beauty. (shrink)

Skin pigment pattern formation is a paradigmatic example of pattern formation. In zebrafish, the adult body stripes are generated by coordinated rearrangement of three distinct pigment cell‐types, black melanocytes, shiny iridophores and yellow xanthophores. A stem cell origin of melanocytes and iridophores has been proposed although the potency of those stem cells has remained unclear. Xanthophores, however, seemed to originate predominantly from proliferation of embryonic xanthophores. Now, data from Singh et al. shows that all three cell‐types derive from (...) shared stem cells, and that these cells generate peripheral neural cell‐types too. Furthermore, clonal compositions are best explained by a progressive fate restriction model generating the individual cell‐types. The numbers of adult pigment stem cells associated with the dorsal root ganglia remain low, but progenitor numbers increase significantly during larval development up to metamorphosis, likely via production of partially restricted progenitors on the spinal nerves. (shrink)

This article will explore the processes and concepts embedded within Dennis Doty’s fine arts studio practice, giving examples of how the work has developed from traditional paintings into its current interdisciplinary form. It examines why it is important to integrate traditional art-making skills with contemporary new media software and approaches. The article aims to illuminate some of the complex interdisciplinary processes that Doty employs to develop multiple bodies of work, including stereoscopic video paintings and projection-mapping artworks. His work explores ideas (...) of spatial perception and the changes that have been happening to our understanding of both physical and digital environments since the invention of the Internet. Doty’s processes demonstrate ways of finding connections between different mediums, analysing and unifying components in a way that can be helpful and inspiring for various professional fields. (shrink)

Many pigmented heterokonts are able to synthesize elements of their cell walls (the frustules) of dense biogenic silica. These include diatom algae, which occupy a significant place in the biosphere. The siliceous frustules of diatoms have species‐specific patterns of surface structures between 10 and a few hundred nanometers. The present review considers possible mechanisms of uptake of silicic acid from the aquatic environment, its transport across the plasmalemma, and intracellular transport and deposition of silica inside the specialized Silica Deposition Vesicle (...) (SDV) where elements of the new frustule are formed. It is proposed that a complex of silicic acid with positively charged proteins silaffins and polypropylamines remains a homogeneous solution during the intracellular transport to SDV, where biogenic silica precipitates. The high density of the deposited biogenic silica may be due to removal of water from the SDV by aquaporins followed by syneresis—a process during which pore water is expelled from the network of the contracting gel. The pattern of aquaporins in the silicalemma, the membrane embracing the SDV, can determine the pattern of species‐specific siliceous nanostructures. BioEssays 30:328–337, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

The retina pigment epithelium (RPE) is a highly specialised epithelium that serves as a multifunctional and indispensable component of the vertebrate eye. Although a great deal of attention has been paid to its transdifferentiation capabilities and its ancillary functions in neural retina development, little is known about the molecular mechanisms that specify the RPE itself. Recent advances in our understanding of the genetic network that controls the progressive specification of the eye anlage in vertebrates have provided some of the (...) initial cues to the mechanisms responsible for RPE patterning. Here, we have outlined many recent findings that suggest that a limited number of transcription factors, including Otx2, Mitf and Pax6 and a few signalling cascades, are the elements required for the onset of RPE specification in vertebrates. Furthermore, using this information and the data available on the specification of the pigmented cells of primitive chordates, we have ventured some hypotheses on the origin of RPE cells during evolution. BioEssays 26:766–777, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Darwin1 introduced the idea that ornamental secondary sexual traits have evolved in response to female preferences for showy males. Among such traits, yellow and red carotenoid‐based ornaments have been considered as particularly good candidates for explaining why and how females would benefit from mating with showy partners. Because carotenoids can be used for promotion of both health and appearance, colourful male ornaments should honestly reveal the vigour of the bearers. Two recent experiments with birds2,3 now show how allocation of bodily (...) carotenoids to sexual signalling is traded off against the use of carotenoids for boosting immune function. BioEssays 25:746–747, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

In this essay, the hypothesis that biliverdin pigment plays an antioxidant role in the avian eggshell is proposed. Due to its ability to scavenge free radical species and to reduce mutation, biliverdin potentially counteracts the oxidative action of pathogens that penetrate the eggshell and/or protects the shell membrane from oxidation, thus promoting the proven antioxidant and antimicrobial capacities of the shell membrane itself. Additionally, biliverdin may be able to inhibit viral replication in the eggshell due to its ascribed antiviral (...) properties. Moreover, previous results in other taxa leave open the question of whether biliverdin can be absorbed by the embryo from the eggshell and play a role in embryogenesis. These mechanisms of antioxidant action of eggshell biliverdin remain totally unexplored in birds and in other oviparous animals. The main assumptions and predictions of the antioxidant hypothesis are developed, and directions for future research are proposed. (shrink)

Melanin, and other pigments have recently been shown to preserve over geologic time scales, and are found in several different organisms. This opens up the possibility of inferring colours and colour patterns ranging from invertebrates to feathered dinosaurs and mammals. An emerging discipline is palaeo colour: colour plays an important role in display and camouflage as well as in integumental strengthening and protection, which makes possible the hitherto difficult task of doing inferences about past ecologies, behaviours, and organismal appearance. Several (...) studies and techniques have been presented in the last couple of years that have described ways to characterize pigment patterns. Here, I will review the available methods and the likely applications to understand past ecologies. A golden age of colourized dinosaurs and other animals is now dawning upon us, which may elucidate the nature of ancient predator prey interactions and display structures.Also watch the Video Abstract. (shrink)

Recently, we reported that melanoma risk in redheads is linked not only to pale skin, but also to the synthesis of the pigment – called pheomelanin – that gives red hair its color. We demonstrated that pheomelanin synthesis is associated with increased oxidative stress in the skin, yet we have not uncovered the chemical pathway between the molecule pheomelanin and the DNA damage that drives melanoma formation. Here, we hypothesize two possible pathways. On one hand, pheomelanin might generate reactive (...) oxygen species (ROS) that directly or indirectly cause oxidative DNA damage. On the other hand, pheomelanin synthesis might consume cellular antioxidant stores and make the cell nucleus more vulnerable to other endogenous ROS. Uncovering the mechanistic pathway between pheomelanin and oxidative DNA damage will be an important step in developing strategies to lower melanoma risk in redheads. (shrink)

How can a work of art give us clues about scientific aspects? How can chemistry help a painter enhance his creativity and, above all, preserve the original characteristics of his work? Does an artist require scientific knowledge to innovate or, at least, not to be faked? Other symbiotic fields between art and science are: tattoos, as body art with physical and chemical consequences; pigments, as basic materials with interesting historiographical preparations; spectroscopy diagnosis, as very broad and thorough method of analysis (...) ; biosensors, as one of the applications of new pigments. Note also the interconnection between the several possible paths of science and art, which reflect new challenges with enormous potential investigated through a literature review and the application as a case study in an educational inquiry module. (shrink)

The pigment melanin is found in all living kingdoms and in many different structures and forms. When its various functions are examined separately, its behaviors seem disparate and conflicting. It has a clear role in camouflage and sexual display. Other major roles are examined critically. It can act as a sun screen but is not a very effective one. It can also scavenge active chemical species, but this, too, is not done very effectively. It produces active radicals that can (...) damage DNA. It binds to drugs in ways that are either beneficial or deleterious. Aside from camouflage, its other roles can be brought together by a unifying hypothesis as first proposed by Proctor and McGinness nearly 20 years ago. Melanin is envisaged as an energy transducer with the properties of an amorphous semiconductor. It can absorb many different types of energy and dissipate them in the form of heat. However, if the energy input is too great, the output can be expressed in the form of activated chemical species that can damage cellular macromolecules resulting in cell death, mutations and cancer. The protective aspect of melanin in dark skin is seen as resulting from its high concentration and its confinement to ellipsoidal and densely packed organelles that can effectively shield the nucleus. In light skin, its radical nature is seen as potentially participating in the carcinogenic process, particularly when overwhelmed by intense episodes of sunburn. (shrink)

Pigment cells in zebrafish − melanophores, iridophores, and xanthophores − originate from neural crest‐derived stem cells associated with the dorsal root ganglia of the peripheral nervous system. Clonal analysis indicates that these progenitors remain multipotent and plastic beyond embryogenesis well into metamorphosis, when the adult color pattern develops. Pigment cells share a lineage with neuronal cells of the peripheral nervous system; progenitors propagate along the spinal nerves. The proliferation of pigment cells is regulated by competitive interactions among (...) cells of the same type. An even spacing involves collective migration and contact inhibition of locomotion of the three cell types distributed in superimposed monolayers in the skin. This mode of coloring the skin is probably common to fish, whereas different patterns emerge by species specific cell interactions among the different pigment cell types. These interactions are mediated by channels involved in direct cell contact between the pigment cells, as well as unknown cues provided by the tissue environment. (shrink)

Variations in human skin pigmentation are obvious, but how have skin colour differences evolved? Although clearly a polymorphic trait, the number and identity of key variants has remained unclear. Investigation of pigmentation phenotypes in model organisms provides a route to identify these genes and showed MC1R to be one key locus. Now, cloning of a classic zebrafish mutant, golden, identifies slc24a5 as a gene involved in fish skin pigmentation.1 Strikingly this study identifies the human orthologue, SLC24A5, as likely to make (...) a major contribution to the pale skin colouration of Western Europeans. BioEssays 28: 578–582, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

Members of the CAR group of Ig‐like type I transmembrane proteins mediate homotypic cell adhesion, share a common overall extracellular domain structure and are closely related at the amino acid sequence level. CAR proteins are often found at tight junctions and interact with intracellular scaffolding proteins, suggesting that they might modulate tight junction assembly or function. However, impairment of tight junction integrity has not been reported in mouse knockout models or zebrafish mutants of CAR members. In contrast, in the same (...) knockout models deficits in gap junction communication were detected in several organ systems, including the atrioventricular node of the heart, smooth muscle cells of the intestine and the ureter and in Sertoli cells of the testes. Possible interactions between BT‐IgSF and connexin41.8 on the disturbed pattern of pigment stripes found in zebrafish mutants and between ESAM and connexin43 during hematopoiesis in the mouse are also discussed. On the basis of the combined data and phenotypic similarities between CAR member mutants and connexin mutants I hypothesize that they primarily play a role in the organization of gap junction communication. Also see the video abstract here: https://youtu.be/i0yq2KhuDAE. (shrink)

The discovery of traces of a blood meal in the abdomen of a 50‐million‐year‐old mosquito reminds us of the insights that the chemistry of fossils can provide. Ancient DNA is the best known fossil molecule. It is less well known that new fossil targets and a growing database of ancient gene sequences are paralleled by discoveries on other classes of organic molecules. New analytical tools, such as the synchrotron, reveal traces of the original composition of arthropod cuticles that are more (...) than 400 my old. Pigments such as melanin are readily fossilized, surviving virtually unaltered for ∼200 my. Other biomarkers provide evidence of microbial processes in ancient sediments, and have been used to reveal the presence of demosponges, for example, more than 635 mya, long before their spicules appear in the fossil record. Ancient biomolecules are a powerful complement to fossil remains in revealing the history of life. (shrink)

Muriel Wheldale, a distinguished graduate of Newnham College, Cambridge, was a member of William Bateson's school of genetics at Cambridge University from 1903. Her investigation of flower color inheritance in snapdragons (Antirrhinum), a topic of particular interest to botanists, contributed to establishing Mendelism as a powerful new tool in studying heredity. Her understanding of the genetics of pigment formation led her to do cutting-edge work in biochemistry, culminating in the publication of her landmark work, The Anthocyanin Pigments of Plants (...) (1916). In 1915, she joined Frederick Gowland Hopkin's Department of Biochemistry as assistant and in 1926 became one of the first women to be appointed university lecturer. In 1919 she married the biochemist Huia Onslow, with whom she collaborated until his death in 1922. This paper examines Wheldale's work in genetics and especially focuses on the early linkage of Mendelian methdology with new techniques in biochemistry that eventually led to the founding of biochemical genetics. It highlights significant issues in the early history of women in genetics, including the critical role of mentors, funding opportunities, and career strategies. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Participation and Immersion in Walton and CalvinoM. Carleton SimpsonThe novel begins in a railway station, a locomotive huffs, steam from a piston covers the opening of the chapter, a cloud of smoke hides part of the first paragraph... The pages of the book are clouded like the windows of an old train, the cloud of smoke rests on the sentences.1Part of Kendall Walton's theory of psychological participation, explicated in (...) Mimesis as Make-Believe, is that representations that display or draw attention to their fictionality discourage participation; part of our enjoyment of representational art is our psychological participation with the representation. The activity of participating comprises the game world, while the material representation comprises the work world. We play games of make-believe with representations, much as children play games with toys or other props. For Walton, the fullest psychological participation arises from the fullest immersion in the game world. Immersion means ignoring or being unaware of the materiality of the work world, attending only to the fictional reality of the work world. It is to "look past" the painted surface, or to become engrossed in the novel's narrative.To the extent that we consider the material of the work, we are distracted from participating in the game prescribed by the work: we do either the one or the other. So, Walton claims "One obvious way in which works sometimes discourage participation is by prominently declaring or displaying their fictionality, betraying their own pretense" (p. 275).2 For example, "The conspicuous brush strokes of Van Gogh's Starry Night call attention to themselves and to their record of the process by which paint was applied to the canvas, possibly intruding on the viewer's participation in his game... One can ignore the brush [End Page 321] strokes enough to lose oneself in the fictional world" (p. 277). In response to prodding by Patrick Maynard, Walton tempers this position: "Prominent brush strokes, as in many of Vincent van Gogh's paintings, can have an inhibiting effect, especially if the observer isn't used to such. Then they not only constitute a plain indication that what one is seeing is a mere painted canvas, but force this fact on the viewer's attention" (italics added).3Ernst Gombrich endorsed this position in Art and Illusion, attributing it to Kenneth Clark.4 Gombrich tells of Clark attempting to see both the brush strokes and the representation, and his failure to "observe what went on when the brush strokes and dabs of pigment on the canvas transformed themselves into a vision of transfigured reality as he stepped back" (p. 6). Walton intends his theory of psychological participation to be widely applicable to the representational arts; he argues that what holds for visual representations holds also for verbal representations. When reading a novel our ability to participate in the story is diminished to the extent the novel draws attention to its fictionality. We either immerse ourselves in the fictional world of the novel or attend to the historical production or materiality of the novel.Attending is contained in Walton's notion of appreciation. Appreciation without participation results when some representations "positively discourage participation, especially the psychological participation that would constitute the experience of being caught up in the story" (p. 274). Works like these employ a variety of strategies, "deliberately 'distancing' the appreciator from the fictional world... For if one does not imagine a proposition, it is unlikely to be fictional that one knows or believes it; and if one imagines it with minimal vivacity, one is unlikely to have the experience of fictionally being concerned or upset or relieved or frightened or overjoyed by the fact that it is true" (p. 274). Just as children imagine themselves to be participants in games of make-believe, more mature imaginings require us to imagine we are participants, not simply observers. Reflexive imagining is central to Walton's theory, and is a point he extensively develops.I argue against this disjunction of activities. My thesis is that participation need not arise from immersion at the expense of awareness. I am also critical of Walton's distinction between appreciation and participation—they are... (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Titles, Labels, and Names:A House of MirrorsGreg Petersen (bio)An EducationAmong the harshest critiques ever received during my doctoral coursework came from a professor who was noticeably perturbed that I had researched and written a paper on an artwork without considering the title in the interpretation and analysis of the work. The professor insisted that the title is necessary to understand the piece. As a diligent student, the lesson was (...) learned, and the following semester I wrote a different paper for a different professor including the title as part of the interpretation and analysis. The professor's response asserted that the sections of the paper discussing the title should be deleted to improve the paper because a title is a name only—a linguistic referent to speak and write about the work that has no other relationship to the work. The discussions that followed with the two professors evolved into a permanent interest in the relationship between appellations and the works they represent. The debate of whether titles are or are not important is not a two-sided argument but rather a maze. This article is not a specialized theoretical argument but an explication of this maze of disjointed relationships among images, their appellations, and the theories espoused by various artists, art critics, art historians, and philosophers. Nevertheless, the clearest exits from the maze are found by treating the appellations as literature and applying literary theory to them.Between Text and ImageMuch of the world we live in is visual and linguistic in nature: visual to the extent that seeing is associated with knowing, and linguistic to the extent that we can communicate through the use of words and letters. For thousands [End Page 29] of years there has been a close relationship between images and language. Both are commonly represented through the use of pigments on a two-dimensional surface. While we know of no literary relationships in early paintings, it is extremely rare today to find paintings without a literary appellation attached. Today we study paintings through words, but only on the most elementary levels do we study words through paintings. It appears that literate cultures give dominance to textual symbols over those in paintings, while illiterate cultures reverse these relationships. The problem is that words have culturally agreed upon meanings, often more so than visual images. We read and listen and then write and speak about those things we have read and heard. Historically, it may be that the relationship between language and images has reversed itself, and perhaps even reverses itself in our own educational process as we begin teaching children letters and words through the use of pictures. After all, which came first: image or language?There has been little written on the use of word associations with iconographic images during the Middle Ages. Nevertheless, it is clear that identification characteristics other than linguistic ones existed. Hazard Adams is one of the few to raise this issue in his essay on titles: "Before I turn to literary titles it might be well to ask whether... I am correct in assuming that there has never been a nonverbal title of a literary work or of anything else for that matter, the word-objects relation of a title being irreversible. There are certainly nonverbal labels like coats of arms and crowns that imply title in a related sense."1 It may be true that titles are typically thought of as word associations identifying objects, but it may also be possible that medieval imagery was at least as communicatively accurate as our present textual system. For example, a man with arrows fixed in his flesh would still be recognized by a medieval illiterate as St. Sebastian, yet most of the depictions of this Catholic saint are simply titled St. Sebastian. Would hanging the text St. Sebastian next to these depictions have created more meaning or a deeper understanding to a medieval Catholic? Often sacred personages and other important visual images have their own identifying characteristics that make a correlative text unnecessary. These identifying characteristics, to those familiar with them, remain very effective nonverbal symbols that conjure the stories they represent.Furthermore, during the medieval... (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Earth-O-Meter: Color Studies OchreElpitha Tsoutsounakis (bio)Ochre is always in a state of becoming—becoming color, becoming blood. Ancient, stellar death becoming current, terrestrial life; geological making. Design becomes epistemic tool beyond aesthetic representation.I join a body of academic and community scholars around the globe who think with Ochre from a variety of disciplines. How have we evolved through and with Ochre? What future does Ochre bring as art or technology? (...) How can Ochre remediate legacies of extraction? How can we return to the material from our current abstraction and commodification of color? How can we relate to terrestrial beings beyond anonymous resource? How can Ochre reveal plural realities of time and place through erased or forgotten narratives?This exploration has become the Field Studio Geontological Survey (FSGS), a design research collective assembling and extending Ochre dimensions to expand human/nonhuman inter-subjectivity. The collective is inspired by the United States Geological Survey (USGS), which has surveyed, mapped, and catalogued the U.S.—and the world—extensively and completely, translating earth matter into anonymous “natural” resources. Through its manipulation of geopower, USGS mediates our human relation to the more-than-human. The Geontological Survey diverts USGS tactics—survey, map, catalog, archive—towards a future feminist Ochre imaginary though collective practice in field, community, and studio operations. Ochre bodies, pigments, swatches, and the maps and artifacts produced with/by them, are archived at UnknownProspect.org.Earth-O-Meter 231101 (see Fig. 1) is assembled with thirty-six Ochres from FSGS Folio 2301,1 all surveyed in field operations at Temple Mountain Mining District in the San Rafael Swell, Utah. The swell is a geological anomaly at the edge of the Colorado Plateau, an anticline pushed up 60 million years ago during the Laramide Orogeny. It measures roughly 64 [End Page 109] Click for larger view View full resolutionFigure 1.Earth-O-Meter 231101: Ochre bodies from Folio 2301 and their respective swatches made with pigment in gum arabic and water. Full-scale color image and more on Ochres from Folio 2301 can be seen at unknownprospect.org.km wide and 121 km long. Erosion has revealed millions of years of geological time exposed to the desert sun along the reef edge where so-called Temple Mountain emerges from the southeast flank. An ancient marine environment left us the Chinle Formation in the Triassic Period—a formation marked by colorful instances of oxidation or reduction based on [End Page 110] fluctuating sea levels and water conditions. The meter begins and ends with Ochre that appears “green” (28.006) alongside Ochre that appears “violet” (18.003). They arrive next to one another just as they are found in the landscape: green nestled in violet, reminding us of lapping waters so long ago.Folio 2301 and the Earth-O-Meter are lines of flight for a material color theory, one in which color is not an abstract, perceived characteristic observed by physics, or a trick debating its place in or out of the mind. Color, or chroma, are material signs in the universe. Folio 2301 archives Ochre bodies from Temple Mountain alongside their respective pigments and the registry of community members who prepared them. The pigments were swatched to produce eight plates containing color studies or “palettes of place.” In Ochre, heat moves iron from yellow to red, water differentiates green from violet. Fluctuations of heat, time, pressure, electromagnetic field, and energy all play a part in the matter of color.While it is inspired by the cyanometer, a tool made to measure the blueness of the sky,2 the Earth-O-Meter is not a tool for measuring color, or earth-ness. It is a portal and a sign where the energy and intelligence of iron is flowing and evolving—all around us, before us, and after us. The cyanometer is made using Prussian blue, which is an oxidation of ferrous ferrocyanide salts. Prussian blue is known as the “first synthetic pigment.” By tinting Prussian blue to create the spectrum of the sky, technics modify iron to produce a divergent color in order to measure an ephemeral effect of atmosphere. The sky’s blueness is our experience of... (shrink)

'Material thing' is a two-level concept. In 'first-order extension' - the field of perceptual experience - it is a 'body' that may 'body forth' (show, express) a 'content', like the bodies of persons or pictures. In 'second-order extension' -the physical field or space - it is a 'physical object' whose micro-constitution is the target of the reference of theoretical terms or formulae. As such, it has no content - nothing to 'express'. In the description of a material thing in first-order (...) extension, terms are used whose reference is fixed by ostension. (The picture's pigment is cracked, the person's eyes are blue.) The reference of theoretical terms - to the material thing in second-order extension - is fixed by their interrelationships in the theory. (shrink)

Why do some invertebrates store so much carotenoids in their tissues? Storage of carotenoids may not simply be passive and dependent on their environmental availability, as storage variation exists at various taxonomic scales, including among individuals within species. While the strong antioxidant and sometimes immune-stimulating properties of carotenoids may be beneficial enough to cause the evolution of features improving their assimilation and storage, they may also have fitness downsides explaining why massive carotenoid storage is not universal. Here, the functional and (...) ecological implications of carotenoid storage for the evolution of invertebrate innate immune defenses are examined, especially in crustaceans, which massively store carotenoids for unclear reasons. Three testable hypotheses about the role of carotenoid storage in immunological (resistance and tolerance) and life-history strategies (with a focus on aging) are proposed, which may ultimately explain the storage of large amounts of these pigments in a context of host–pathogen interactions. (shrink)

Imbalance in the pH of water reduces this precious resource as an extremely dangerous liquid for human health and plants’ growth. Change in the pH levels of the drinkable water has majorly raised concern towards diverse health issues like heart problems, infant mortality rates, pigmentation of skin, and cholera outbreaks. Therefore, it is necessary to keep a check on essential water quality components that include acidic/basic nature of water. As per the US Environmental Protection Agency, the drinkable water should have (...) a pH level ranging from 6.5 to 8.5. Two sample situates have been identified wherever highly reported pollutants levels were found and have been analyzed through artificial intelligence techniques. It can be observed that wavelet denoised signals fed into the least squares support vector regression and M5 prime regression tree predicted more accurately on the basis of the performance errors that are as follows: root mean squared error ; mean squared error ; mean absolute error. On the basis of these errors, the coefficient of determination/goodness of fit simulated for the prototypes is developed in this study. RMSE outcomes diminish on the whole on applying the training and forecasting data-division via WLSSVR and WM5pRT as compared with fitting the normalized data through LSSVR and M5pRT. These performance measures are essential to analyze the concentration levels of pH in the river streams at the identified sites of study. Thus, the observed pattern from this study may help for future estimation of the quality of water at their sources so that it prohibits the further increase in either acidic or basic salts which prove to be lethal for the environment. Thus, these predictors would be helpful towards formulation of strategies for protection of ecosystem and human health. (shrink)

Rapidly advancing studies on rhodopsin have focused on new strategies for crystallization of this integral membrane protein for x-ray analysis and on alternative methods for structural determination from nuclear magnetic resonance data. Functional studies of the interactions between the apoprotein and its chromophore have clarified the role of the chromophore in deactivation of opsin and in photoactivation of the pigment.

Light can kill the photoreceptors of the eye, not only very bright direct sunlight, but more moderate illumination if the light is present continuously. Recent experiments show that rod apoptosis can be triggered by strong and constant activation of transduction, and that death can be prevented if transduction is inhibited even though the eye is illuminated. Vitamin A deficiency and genetically inherited diseases, such as some forms of retinitis pigmentosa and Leber congenital amaurosis, appear to kill like this: transduction is (...) activated at a high rate and continuously, and this causes the rods to die. Why does transduction kill? Our best guess is that continuous activation produces a prolonged lowering of the Ca2+ concentration, which is also thought to kill neurons in tissue culture and during the development of the nervous system. To prevent death in constant light, rods have evolved protective mechanisms including modulation of channels and ion transport to keep the Ca2+ from going too low. Prolonged light exposure also causes migration of transduction proteins from one part of the cell to another and a reversible shortening of the rod outer segments, the part of the cell that contains the pigment rhodopsin. All of these mechanisms are at work in the normal eye to reduce transduction and prevent the Ca2+ concentration from dropping too low for too long a time. That most of us retain our vision our entire lives is a testament to their effectiveness. BioEssays 28: 344–354, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

If there is life elsewhere in the universe and its level of development is as backward as its terrestrial counterpart, they will probably have sociologists and political scientists constructing and deconstructing social reality. If and when they finally make contact with earth, these pundits will have great difficulty making sense of American race relations, no matter how many studies the Federation will commission to make sense out of the subject. The earth's most developed country, whose success is largely due to (...) its heterogeneity, pragmatism and common sense, does not seem able to deal with differences in skin pigmentation, to the point that its best intellectuals systematically make fools of themselves in explaining it. (shrink)

Graphical AbstractThe antioxidant hypothesis proposes that the blue-green pigment found in many birds’ eggs provides a direct benefit to the developing embryo through its antioxidant-like properties. Such protection is feasible if the pigment transfers to the eggshell membrane or inside the egg. This newly proposed hypothesis provides a range of intriguing possibilities for future tests.

Cancer is one of the most frequent fatal human diseases. It is a genetic disease, and molecular analysis of the genes involved revealed that they belong to several distinct classes of molecules, one of which is the receptor tyrosine kinases. Neoplastic transformation is regarded as the result of a multistep process and, in most cases, it is hard to evaluate what the initial events in tumor formation are. What makes it difficult to approach this question is the paucity of animal (...) models for tumorigenesis allowing investigation of the mechanisms leading to uncontrolled cell proliferation. Melanoma formation in Xiphophorus is one of these model systems. Here, overexpression and activation of a receptor tyrosine kinase causes neoplastic transformation of pigment cells. Xiphophorus provides all the advantages of a well‐characterised genetic system. In addition, some crucial components of the transformation pathway have been identified at the molecular level. As a vertebrate, Xiphophorus might serve as a model system to aid understanding, in more general terms, of the mechanisms of tumorigenesis in human diseases. (shrink)

Mutations within the Steel and Dominant Spotting loci of mice have led to the recent identification of a growth factor/receptor system required for the normal development of germ cells, pigment cells and hematopoietic cells. Interactions between the products of these genes, Steel factor and c‐Kit respectively, have now been demonstrated to influence various developmental processes, including survival, proliferation, and/or differentiation of cells in a tissue specific manner. In addition, our current understanding of the molecular basis of various Steel and (...) Dominant Spotting alleles coupled with the emerging information on the expression pattern of steel factor and c‐kit transcripts during development, is now beginning to explain the pleiotropic affects of these mutations. (shrink)