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PubMed1995

Somatic reversion of some copia-like induced mutations, at the white locus of Drosophila melanogaster, after treatment with alkylating agents.

It has been suggested that transposable elements can be associated with different types of genotoxic effects. For this reason it seems appropriate to outline suitable systems to detect changes in the phenotypic expression of the loci containing transposable elements, as well as those agents that induce such changes. The sex-linked white locus offers a suitable experimental system for studying such events because most of the spontaneous mutations at the white locus are the result of insertions of repeated mobile sequences, and it is easy to follow mutational changes of the locus due to the possibility of detecting even slight changes in eye color. Here we report the results obtained in different strains of Drosophila melanogaster with copia-like induced mutations at the white locus, after treatment with three alkylating agents: ethyl methanesulfonate (EMS), methyl methanesulfonate (MMS), and N-nitroso-N-ethylurea (ENU). The three insertional white mutants used in this work were wa4, wbf, and wsp55, with the wa2 mutation used as control because its mutant phenotype is the result of a point mutation instead of the insertion of a DNA fragment. Our data constitute evidence that EMS, MMS, and ENU induce a clear increase in the frequencies of somatic-revertant sectors in the three strains carrying a white allele with an inserted copia-like element. For the wa2 strain, whose mutant phenotype is the result of a point mutation, only ENU at the highest concentration tested is able to induce a significant increase in the somatic reversion frequency. In addition, our results indicate that the use of D. melanogaster strains with transposable elements in the white locus is suitable for detecting genotoxic damage induced by chemicals.

Alkylating Agents↗
PubMed1996

Characterization of a sex-influenced modifier of gene expression and suppressor of position-effect variegation in Drosophila.

Modifier of white (Mow), a dominant transacting gene, has been identified through a mutagenic screen for second-site loci that alter the level of expression of the white eye color locus. Mow reduces the expression of white in most developmental stages, but enhances its expression in the pupal stage, the time at which the major contribution to the adult phenotype is made. Tests with an Alcohol dehydrogenase promoter-white reporter and a series of white truncation constructs have shown that Mow fails to affect the reporter; cis-regulatory mutations of white also show no response, suggesting a requirement for white regulatory domains for interaction with Mow. A quantitative analysis of steady-state transcript levels reveals that the white mRNA level decreases in the presence of one dose of Mow in larvae and adults, but the reduction is greater in females than males. Two other functionally related genes, brown and scarlet, also exhibit a similar sexually dimorphic alteration in expression, mediated by Mow. In the mid-pupal stage, by contrast, the level of white and brown mRNA is increased by Mow. In addition, Mow acts as a weak suppressor of position effect variegation (PEV). These observations suggest a connection between dosage modulation of gene expression and suppression of position-effect variegation.

Alcohol Dehydrogenase↗
PubMed1989

Interaction of the mottler of white with transposable element alleles at the white locus in Drosophila melanogaster.

The mottler of white (mw) locus has been determined to interact with alleles of the white (w) eye color locus which are a subset of the transposable element insertion mutants. The transposable elements belong to six different types, including copia, and are located at several sites within the w gene. Three X-ray-induced revertants of white-apricot (wa) no longer respond to mw, indicating that the transposable element must be present for mw to act. The mottling property of the original allele was analyzed by combining the mw mutant with extra copies of wa, either in a tandem duplication or in a transposable segment on chromosome two. Because neither duplication alters the mottling pattern, the event that results in the mottled pattern must occur at mw and not at w. The pattern of a deficiency for the locus heterozygous with the original allele differs from that of mw/mw females, confirming that this unique mottling property occurs at mw. A new allele of mw was induced in hybrid dysgenic crosses. It is not mottled, slightly enhances wa as a heterozygote, and further enhances as a homozygote or hemizygote. An analysis of RNA from wa with mw shows a reduction of the full-length normal RNA and a concomitant increase in certain RNAs that terminate within the copia element. These results suggest that several retrotransposon-induced alleles share an RNA processing function encoded by mw.

Alleles↗
PubMed1989

Xanthine dehydrogenase is transported to the Drosophila eye.

The rosy (ry) locus in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase. Mutants that have no enzyme activity are characterized by a brownish eye color phenotype reflecting a deficiency in the red eye pigment. This report demonstrates that enzyme which is synthesized in some tissue other than the eye is transported and sequestered at the eye. Previous studies find that no leader sequence is associated with this molecule but a peroxisomal targeting sequence has been noted, and the enzyme has been localized to peroxisomes. This represents a rare example of an enzyme involved in intermediary metabolism being transported from one tissue to another and may also be the first example of a peroxisomal protein being secreted from a cell.

Animals↗
PubMed1998

Characterization of melanins in human irides and cultured uveal melanocytes from eyes of different colors.

The presence of eumelanin and pheomelanin in irides from eyes of various colors was determined and quantified by a highly specific microanalytical procedure based on chemical degradation. Significant differences in the type of melanin were observed in the stroma and iris pigment epithelium (IPE) fractions obtained by micro-dissection of the iris specimens. Melanin from the IPE is essentially eumelanin, while the pigment in IPE-scraped iris (consisting mainly of stroma plus anterior IPE) proved to be both eumelanic and pheomelanic. A pheomelanic-type pigmentation was associated with green irides, while green-blue mixed-color irides were mostly eumelanic; by contrast, green-brown mixed-color and brown irides could not be placed into either of the two categories and probably feature a mixed pigment content. Blue irides invariably exhibited very low pigment content. Analysis of cultured iridial melanocytes in the growing stage showed a significant shift to pheomelanic pigmentation when compared with those in IPE-scraped tissues, providing evidence that growth of iridial melanocyte induce a marked change of melanin metabolism. After senescence, cultured melanocytes exhibited a marked increase in pigment content, most of the variation was associated with the eumelanin content. These results represent the first direct evidence for the presence of eumelanin and pheomelanin in human irides, and suggest that differences in stromal pigmentation are due not only to the quantity, but also the nature of the melanin pigment.

Cells, Cultured↗
PubMed1987

A central binocular mechanism affects chromatic adaptation.

Two experiments explored the role of central binocular mechanisms in color perception. The first experiment examined the effect of adapting to simultaneous, binocularly fused fields. Each eye adapted to a slowly flickering (0.5 Hz) long-wavelength light. The two eyes were adapted either inphase (both eyes stimulated at the same moment) or out-of-phase (only one eye stimulated at any given moment). Both adapting procedures shifted equilibrium yellow toward longer wavelengths, but a significantly greater shift was found when adapting light stimulated both eyes simultaneously. This reveals that a central binocular mechanism affects chromatic adaptation. The second experiment tested whether the binocular mechanism could shift equilibrium yellow measurements made with both eyes (identical, binocularly fused fields presented to each eye) outside of the range of measurements established by left-eye monocular viewing and right-eye monocular viewing. Differences were found between monocular left-eye and monocular right-eye color appearance under conditions of moderate chromatic adaptation, but binocularly fused measurements fell within the range established by the monocular results. This is consistent with the view that central mechanisms serve to keep the two eyes in balance, rather than systematically alter color appearance from colors perceived under monocular viewing.

Adaptation, Ocular↗
PubMed2002

Depressive symptomatology differentiates subgroups of patients with seasonal affective disorder.

Patients with seasonal affective disorder (SAD) may vary in symptoms of their depressed winter mood state, as we showed previously for nondepressed (manic, hypomanic, hyperthymic, euthymic) springtime states [Goel et al., 1999]. Identification of such differences during depression may be useful in predicting differences in treatment efficacy or analyzing the pathogenesis of the disorder. In a cross-sectional analysis, we determined whether 165 patients with Bipolar Disorder (I, II) or Major Depressive Disorder (MDD), both with seasonal pattern, showed different symptom profiles while depressed. Assessment was by the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version (SIGH-SAD), which includes a set of items for atypical symptoms. We identified subgroup differences in SAD based on categories specified for nonseasonal depression, using multivariate analysis of variance and discriminant analysis. Patients with Bipolar Disorder (I and II) were more depressed (had higher SIGH-SAD scores) and showed more psychomotor agitation and social withdrawal than those with MDD. Bipolar I patients had more psychomotor retardation, late insomnia, and social withdrawal than bipolar II patients. Men showed more obsessions/compulsions and suicidality than women, while women showed more weight gain and early insomnia. Whites showed more guilt and fatigability than blacks, while blacks showed more hypochondriasis and social withdrawal. Darker-eyed patients were significantly more depressed and fatigued than blue-eyed patients. Single and divorced or separated patients showed more hypochondriasis and diurnal variation than married patients. Employed patients showed more atypical symptoms than unemployed patients, although most of the subgroup distinctions lay on the Hamilton Scale. These results comprise a set of biological and sociocultural factors-including race, gender, and marital and employment status-which contribute to depressive symptomatology in SAD. Significant mood and sociocultural factors, in contrast to biological factors of gender and eye color, were similar to those reported for nonseasonal depression. Lightly pigmented eyes, in particular, may serve to enhance photic input during winter and allay depressive symptoms in vulnerable populations.

Adolescent↗
PubMed1999

[The characteristics of luminance of color visual evoked potential in macular diseases].

OBJECTIVE: To objectively evaluate the luminance channel damage of macular diseases by color pattern reversal visual evoked potential (CPR-VEP). METHODS: CPR-VEP was performed in 38 eyes with age-related macular degeneration (ARMD) dry type, 24 eyes with ARMD wet type, 20 eyes with Stargardt's disease and 54 normal eyes. Color pattern stimuli were obtained with color monitor controlled by computer program. Color pattern reversal rate was 2 Hz and its spatial frequency was 0.53 cycle/degree. The color graphic system could present white/black (W/B), red/black (R/B), green/black (G/B), blue/black (B/B), yellow/black (Y/B). RESULTS: In normal eyes, CPR-VEP P(1) latency was negatively correlated with luminance, whereas P(1) amplitude positively correlated with luminance; there were linear regressions between the mean luminance and P(1) latency and between the mean luminance and P(1) amplitude. Also in ARMD dry type, the CPR-VEP showed that the characteristics of the luminance channel were similar to that in the normal eyes. However, these phenomena did not exist in ARMD wet type and Stargardt's disease. CONCLUSION: In ARMD dry type, there is no damage of luminance channel, but in ARMD wet type and Stargardt's disease, there is severe damage of luminance channel and the patients can not discriminate luminance difference.

Adolescent↗
PubMed1988

Skin type, hair color, and freckles are predictors of decreased minimal erythema ultraviolet radiation dose.

In a group of 190 white healthy subjects the skin type classification method was found valuable for differentiating subgroups with various degrees of sun sensitivity (except for 33% with borderline or unclassifiable skin type). Sun-sensitive skin types I and II were significantly more common among persons with light hair color or freckles, or both (p less than 0.001). In each skin type category the proportion of subjects with a minimal erythema dose (MED) lower than the median MED of the entire group (%LMED) decreased significantly with increasing skin type number, and distinguished between skin types I through III better than did their mean MED values. Independent predictors of %LMED were skin type and hair color. The contribution of freckles to %LMED was skin type dependent. Age, sex, or eye color had no independent effect on %LMED. The association of skin types I and II, red or blond hair, and freckles with decreased MED may reflect genetically controlled predominance of pheomelanin (a photosensitizing molecule) in the skin of subjects with these phenotypes.

Adult↗
PubMed2003

Effect of resin surface sealers on improvement of stain resistance for a composite provisional material.

BACKGROUND: Resistance to staining is desirable to maintain the esthetic appearance of a provisional material. A resin sealant may improve stain resistance. PURPOSE: Color changes of a resin composite provisional material were measured by reflection spectrophotometry after storage in three staining solutions and water to determine stain resistance when treated with three methacrylate or urethane dimethacrylate resin surface sealants and when left untreated. MATERIALS AND METHODS: Specimens of a resin composite provisional material received one of three resin sealants (Fortify Plus, Bisco, Inc., Schaumburg, IL; Jet Seal, Lang Dental Manfacturing, Wheeling, IL; Triad LC, Dentsply International, York, PA, USA) or no surface sealer and then were stored for 72 hours in one of four staining solutions (water [control], black coffee, cranberry juice, red wine). Color was measured by CIE L*a*b* on a reflection spectrophotometer (Color-Eye 7000, Macbeth Division, Kollmorgen Instruments, Newburgh, NY, USA) at baseline and after storage. Color change (deltaE*) was calculated and analyzed statistically by two-factor analysis of variance, with four solutions and four surface treatments as independent variables. RESULTS: deltaE* ranged from 0.7 to 1.7 in water, from 1.1 to 5.5 in cranberry juice, from 1.1 to 6.5 in black coffee, and from 1.5 to 3.9 in red wine. Statistically significant differences were observed (p < .05), with Fortify Plus showing increased staining (deltaE* > 3.3) and Jet Seal and Triad LC showing decreased staining (deltaE* < 2.0) in cranberry juice and coffee compared with staining of the unsealed specimens. Only Jet Seal provided resistance to staining in red wine. CONCLUSIONS: Specimens without a surface sealer had statistically higher (p < .05) and perceptible or nearly perceptible color changes in cranberry juice, black coffee, and red wine than in water. Specimens coated with Jet Seal had statistically lower (p < .05) color changes than uncoated specimens in cranberry juice, black coffee, and red wine. When coated, the color changes of the stained specimens were not perceptible. Specimens coated with Triad LC had statistically lower (p < .05) color changes than unsealed specimens in cranberry juice and black coffee. When sealed, the color changes of the specimens stained with cranberry juice and black coffee were not perceptible. Both unsealed and sealed specimens stained with red wine were nearly perceptible. Specimens coated with Fortify Plus had statistically higher (p < .05) color changes than uncoated specimens in cranberry juice and black coffee but statistically the same (p < .05) color change as uncoated specimens in red wine. These specimens had perceptible color changes in cranberry juice, black coffee, and red wine. CLINICAL SIGNIFICANCE: Surface of methacrylate or dimethacrylate resins can improve resistance of a resin composite provisional material to staining caused by cranberry juice, black coffee, and red wine.

Acrylic Resins↗
PubMed2006

Ultraviolet radiation, dietary vitamin D, and risk of non-Hodgkin lymphoma (United States).

OBJECTIVE: Because of conflicting findings about the relationship between ultraviolet (UV) radiation and the risk of non-Hodgkin lymphoma (NHL), we evaluated the risk of several indicators related to UV, including two not previously studied: dietary vitamin D, and ambient UV levels by residential location. METHODS: As part of a case-control study conducted in four Surveillance, Epidemiology, and End Results (SEER) registries, we collected UV information from a self-administered questionnaire and computer-assisted personal interview with 551 NHL cases and 462 controls. We estimated the relative risk (RR) and 95% confidence intervals (CI) from unconditional logistic regression models. RESULTS: Eye color, a marker of host susceptibility to UV, showed a decreasing risk gradient for lightest eyes (0.47) compared to darkest. Relative risks were in the range of 0.73-0.78 for participants reporting more hours in the mid-day summer sun. Use of sunlamps or tanning booths was associated with decreased risk (RR = 0.88), as was estimated overall ambient UV (RR = 0.76 per 50 RB-units) overall. Vitamin D intake from diet and supplements was not related to risk. Results were thus consistent for the various indicators, although some estimated risks were not statistically significant. Effects were generally similar for diffuse large B-cell (DLBCL) and follicular lymphomas. CONCLUSION: These data suggest a slight protective effect of sunlight against NHL, and they agree with geographic patterns of NHL incidence observed in the US.

Adult↗
PubMed1994

The effect of similarity and duration on spatial interaction in peripheral vision.

Spatial interactions are extensive in the peripheral visual field, extending up to about half the retinal eccentricity of the target (Toet and Levi, Vision Res. 32, 1349-1357, 1992). In the present study it is shown that the degree and extent of peripheral spatial interaction depends in large measure on the similarity between test and flanking stimuli. The stimulus consisted of a test T surrounded by four distracting flanking Ts, each randomly oriented. The task was to determine the orientation of the test T. The test and flanking Ts differed in contrast polarity, shape, depth, color, eye of origin, or contrast. When the target and flanks differed in contrast polarity, depth, or shape, performance improved markedly for all observers. A color difference enhanced the performance of most but not all observers. Eye-of-origin had no effect, that is, spatial interaction was identical when the target and flanks were presented to the same eye, or to opposite eyes. The role of stimulus duration in spatial interaction was examined in two additional experiments. In the first, the stimulus viewing duration was increased in order to allow the observer time to serially search for the test T. In the second experiment, a postmask was presented at the location of the test T. The results of these experiments showed that the influence of similarity was independent of stimulus duration and the postmask, and suggest that serial search does not play an important role in the spatial interaction effects reported here. The extent of spatial interaction is correlated with the ability to do parallel search.

Color Perception↗
PubMed1976

[Injection of DNA from wild-type strains into the eggs of mutant Drosophila melanogaster].

DNA was extracted from wild-type Drosophila Melanogaster or from v; bw mutant and injected into the eggs of v; bw strain. Progeny of flies obtained from injected eggs was examined for several generations. Colored eyes appeared occasionally in the progeny of flies obtained after injection of either DNA. A recovery of colored strains was possible in progeny of flies obtained after injection of wild type DNA (4 out of 15), and not in progeny of 34 flies obtained after injection of v; bw DNA. Genetic alteration inducing color was localized in three of the recovered strains at Su (s) site and in one strain at v site.

Animals↗
PubMed2004

Assessment of polymorphic variants in the melanocortin-1 receptor gene with cutaneous pigmentation using an evolutionary approach.

The melanocortin-1 receptor gene (MC1R) encodes a membrane-bound receptor protein that is central to melanin synthesis. The coding region of MC1R is highly polymorphic and associations of variants with pigmentation phenotypes and risk for cutaneous neoplasms have been reported. We sought to determine the distribution and frequency of MC1R variants and their relationship to pigmentation characteristics in 179 Caucasian controls from the United States. One hundred thirty-five (75.4%) subjects carried one or more variants, and we determined that carriage of the previously designated "red hair color" (RHC) alleles, R151C, R160W, and D294H was strongly associated with fair pigmentation phenotypes including light hair and eye color, tendency to burn, decreased tendency to tan, and freckling. We used SIFT software to define MC1R protein positions that were predicted intolerant to amino acid substitutions; detected variants that corresponded to intolerant substitutions were D84E, R142H, R151C, I155T, R160W, and D294H. Carriage of one or more of these putative functionally important variants or the frameshift variant ins86A was significantly associated with fair pigmentation phenotypes. Analyses limited to carriage of ins86A and the three non-RHC alleles identified by SIFT were attenuated and no longer reached statistical significance. This is the first study to describe MC1R variants among control subjects from the U.S. Our results indicate that the frequency of variants is similar to that previously observed among non-U.S. Caucasians. Risk variants defined by either the published literature or by evolutionary criteria are strongly and significantly associated with all fair pigmentation phenotypes that were measured.

Adult↗