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PubMed2004

Lightoid and Claret: a rab GTPase and its putative guanine nucleotide exchange factor in biogenesis of Drosophila eye pigment granules.

To elucidate the biogenetic pathways for the generation of lysosome-related organelles, we have chosen to study the Drosophila eye pigment granules because they are lysosome-related and the fruit fly provides the advantages of a genetic system in which many mutations affect eye color. Here, we report the molecular identification of two classic Drosophila eye-color genes required for pigment granule biogenesis, claret and lightoid; the former encodes a protein containing seven repeats with sequence similarity to those that characterize regulator of chromosome condensation 1 (RCC1, a guanine nucleotide exchange factor for the small GTPase, Ran), and the latter encodes a rab GTPase, Rab-RP1. We demonstrate in transfected cells that Claret, through its RCC1-like domain, interacts preferentially with the nucleotide-free form of Rab-RP1, and this interaction involves Claret's first three RCC1-like repeats that are also critical for Claret's function in pigment granule biogenesis in transgenic rescue experiments. In addition, double-mutant analyses suggest that the gene products of claret and lightoid function in the same pathway, which is different from that of garnet and ruby (which encode the delta- and beta-subunit of the tetrameric adaptor protein 3 complex, respectively). Taken together, our results suggest that Claret functions as a guanine nucleotide exchange factor for Lightoid/Rab-RP1 in an adaptor protein 3-independent vesicular trafficking pathway of pigment granule biogenesis.

Animals↗
PubMed1983

Inbreeding studies in Brasilian schoolchildren.

We present results of comparisons between consanguineous and control couples and their children in Southern Brasil. Multiple regression, t-test and chi 2 analyses were applied to the data. The following variables were investigated; Parents: structure of first cousin marriages, latitude and longitude of birthplaces, cohabitation time, rurality, marriage age, occupation, number of liveborn children, and frequency of twinning. Schoolchildren: clinical data as classified into 24 discontinuous traits, each one subdivided into two categories (number and severity), and seven continuous traits (weight, height, pulse rate, respiratory rate, systolic pressure, diastolic pressure, and temperature); nutrition indices and biotype; family names; intelligence tests and school performance; birth order, age, hair color, hair type, eye color, and skin color; twinning in the sibship, and infant mortality among sibs of the propositi. Our study showed a) nonrandomness of consanguineous marriages as detected on structural, racial, geographical, and temporal levels; b) a heavy mutational load of about 1.5 lethons acting on infant mortality; c) no inbreeding effect on morbidity in general (with a possible exception of "ear morbidity", including hearing deficit); d) a modest inbreeding depression on height (a decrease of 2 cm with an increase of 10% of inbreeding); 3) a suggestion of inbreeding depression on "intelligence".

Brazil↗
PubMed1996

Halothane resistance in Drosophila melanogaster: development of a model and gene localization techniques.

Studying genetically altered animals that are resistant to inhaled anesthetics may ultimately lead to an understanding of anesthetics' mechanism(s) of action. We studied the genetics of halothane resistance in a strain of Drosophila melanogaster that showed substantially increased resistance to halothane anesthesia. We developed a test method that allowed us to repeatedly observe several samples of flies exposed to the same concentration of halothane, and we measured halothane resistance. The 50% effective dose (ED50) of 91R flies (our resistant population) was greater than the ED50 of Canton-S (our control strain) by 69% in females and by 48% in males. By assessing the contributions of the three major chromosomes of Drosophila to resistance, this study found that the X and third chromosomes of 91R have no effect on resistance, while the second chromosome has a major impact. Resistance within the second chromosome was further localized by testing marked recombinant chromosomes. The central region of 91R's second chromosome, bounded by the genes for black thoracic color and cinnabar eye color, determined most if not all of the increase in resistance. We were not able to further localize resistance within this segment of the second chromosome (containing about 8% of the total genetic map distance). An autosomal dominant gene for halothane resistance in 91R was localized to a small region of the second chromosome.

Anesthetics, Inhalation↗
PubMed1995

Frequency and characteristics of familial aggregation of Paget's disease of bone.

The cause of Paget's disease of bone (PDB) is unknown. In an attempt to ascertain the proportion of familial cases and evaluate the influence of genetic factors on the occurrence of the disease, a study was undertaken based on 35 PDB patients from our Unit. Their families were investigated, with the participation of a total of 128 first-degree relatives. Fourteen (40%) of these 35 index cases had at least one other first-degree relative affected with PDB and were defined as "familial." The remaining 21 (60%) were considered "sporadic." The frequency of males in the familial cases (79%) was significantly higher than among the sporadics (29%; p < or = 0.01). Mean age at diagnosis (63.1 +/- 12.6 vs. 71.3 +/- 8.7; p < or = 0.02), proportion of polyostotic cases (85.7% vs. 52.4%, p < or = 0.05), and mean number of involved bones per patient (4.36 +/- 2.50 vs. 2.33 +/- 1.93, p < or = 0.01) differ significantly in the familial and sporadic groups. The disease appears to be transmitted via both paternal and maternal sides, and pedigree analysis suggested an autosomal dominant inheritance or multifactorial mechanism. Apart from green-and-blue eye color, which was clearly associated with familial grouping (OR 6.25, 95% CI 1.15-37.16, p < or = 0.01), crude analysis on several genetically based traits and environmental variables revealed no other significant differences between the groups. The adjusted odds ratio estimated for green-and-blue eye color was 2.92 (95% CI 0.38-22.74).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

Relationship of dietary fat to age-related maculopathy in the Third National Health and Nutrition Examination Survey.

OBJECTIVE: To evaluate the associations between dietary fat and age-related maculopathy (ARM) in persons 40 years or older who participated in the Third National Health and Nutrition Examination Survey. METHODS: We used a single, nonmydriatic, fundus photograph of 1 eye to ascertain ARM status in 7883 of 11 448 survey participants. Intake of fat was estimated from 24-hour recall, and specific sources of dietary fat were estimated from responses to food frequency questionnaires. Logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CIs) that accounted for complex survey design, nonresponse, and potential risk factors for ARM (age, smoking, race, sex, body mass index, history of cardiovascular disease or hypertension, eye color, and sedentary lifestyle). Persons aged 40 to 79 years (n = 7405) were included in analyses for early ARM (n = 644); those 60 years or older (n = 4294) were included in analyses for late ARM (n = 53). RESULTS: After adjustment for age, race, eye color, and sedentary lifestyle, OR for early ARM was 1.4 (95% CI, 0.9-2.2; P for trend,.10) among persons in high vs low quintiles of total fat intake (percentage of total energy). Associations for specific types of fatty acids (as percentages of caloric intake) were in the same direction and unrelated to ARM. The OR for late ARM was 0.7 (95% CI, 0.2-2.6; P for trend,.60) in persons 60 years or older. Further adjustments for other potential confounders did not significantly affect the ORs. CONCLUSION: Age-related maculopathy was not significantly associated with dietary fat in this large cross-sectional survey.

Adult↗
PubMed2001

Terminal retrotransposons activate a subtelomeric white transgene at the 2L telomere in Drosophila.

Genetically marked P elements inserted into the subtelomeric satellites of Drosophila show repression and variegation of the reporter gene. One such white+ reporter, inserted between the subtelomeric satellite and the terminal HeT-A array in the left arm of chromosome 2 (2L), is sensitive to its context; changes in the structure of the telomere region can be identified by changes in eye color. Addition of HeT-A or TART elements to the 2L terminus increases w+ expression, and loss of sequence from the end decreases expression. This indicates that the telomeric retrotransposons in Drosophila have an activating influence on the repressed subterminal reporter gene. Changes in eye color due to altered expression of the transgene also allow the detection of interactions between homologous telomeres. The 2L arms that terminate in long HeT-A/TART arrays showed increased expression of the subterminal w+ transgene when the terminal repeats on the homologue are absent or markedly shorter. We propose that the chromatin structure of the terminal HeT-A/TART array and the activity of a putative promoter/enhancer element on HeT-A are affected by telomeric interactions. Such trans-activation may reflect control over HeT-A transcription and, thus, transposition activity.

Animals↗
PubMed1986

Photoreactivation rescue and hypermutability of ultraviolet-irradiated excisionless Drosophila melanogaster larvae.

There is accumulating evidence suggesting that expression of genes for repair of UV damage to DNA in mammals and fish is regulated developmentally. Therefore, the activity of excision repair and photoreactivation in vivo in young larvae of Drosophila melanogaster was examined in a strain carrying the mutation mus201 that was unable to carry out excision repair. The photoreactivation activity in first-instar larvae was so high that UV-induced lethality in excision-less larvae was almost completely rescued by posttreatment with fluorescent light. Excision repair activity in first-instar repair-proficient larvae was so high that UV irradiation was scarcely able to produce somatic eye-color mutations. In contrast, excisionless larvae showed a high incidence of somatic eye-color mutation after UV-irradiation, and this incidence was reduced to the spontaneous level by posttreatment with fluorescent light. Incorporation of a postreplication repair-defective mutation into the excisionless strain decreased the incidence of UV-induced somatic mutations by a factor of 3. The analogous repair dependence of UV mutagenesis in Drosophila and Escherichia coli is discussed. It is proposed that UV-induced somatic mutations in excisionless Drosophila larvae are caused primarily by pyrimidine dimers and that a constitutive, error-prone pathway for filling daughter-strand gaps opposite dimers is, at least partly, responsible for the fixation of mutations.

Age Factors↗
PubMedDate not supplied

New mutants and their chromosome assignment in the fly Megaselia scalaris.

We describe six new mutants, spontaneous or EMS-induced, and a previously isolated radiation-induced mutant of Megaselia scalaris Loew (Diptera, Phoridae). Five are eye-color mutants, one affects the segmentation of the abdomen, and one disturbs the regular form and arrangement of ommatidia in the compound eye. A complementation test exposed two pairs of alleles among the five eye-color mutants, leaving three different loci that affect eye pigmentation. Two of them influence the amount of xanthommatin synthesized, and one blocks the ommochrome pathway at the kynurenine step. We established chromosome assignment of the mutants by crossbreeding them with Y chromosome-autosome translocation strains.

Animals↗
PubMed2003

Attending to faces: change detection, familiarization, and inversion effects.

We tested detection of changes to eye position, eye color (brightness), mouth position, and mouth color in frontal views of faces. Two faces were presented sequentially for 555 ms each, with a blank screen of 120 ms separating the two. Faces were presented either both upright or both inverted. Measures of detection (d') were calculated for several different degrees of change for each of the four dimensions of change. We first compared results to an earlier experiment that used an oddity design, in which subjects indicated which of three simultaneously viewed and otherwise identical faces had been altered on one of these four dimensions. Subjects in both of these experiments were partially cued, in that they knew the four possible types of changes that could occur on a given trial. The change-detection results correlated well with the oddity data. They confirmed that face inversion had little effect upon detection of changes in eye color, a moderate effect upon detection of eye-position or mouth-color changes, and caused a drastic reduction in the detection of mouth-position changes. An experiment in which uncued and fully cued subjects were compared showed that cueing significantly improved detection of feature color changes, but there was little difference between upright and inverted faces. Full cueing eliminated all effects of inversion. Compared to partial cueing, changes in mouth color were poorly detected by uncued subjects. Last, a change in the frequency of the base (unaltered) face in an experiment from 75% to 40% showed that increased short-term familiarity decreased the detection of eye changes and increased the detection of mouth changes, regardless of face orientation and the type of change made (color or position). We conclude that uncued subjects encode the spatial relations of features more than the colors of features, that mouth color in particular is not considered a relevant dimension for encoding, and that familiarization redistributes attention from more to less salient facial regions. Inversion effects are not simply an exaggeration of the salience effects revealed by withdrawing cueing, but represent an interaction of spatial encoding with salience, in that the greatest inversion effects occur for spatial shifts in less salient facial regions, and can be eliminated through the use of focused attention.

Adolescent↗
PubMed1999

Mobilization of two retroelements, ZAM and Idefix, in a novel unstable line of Drosophila melanogaster.

We describe a novel transposition system in a line of Drosophila melanogaster called RevI in which two retroelements are mobilized. These elements are the retroelement ZAM, recently described in the literature, and a novel element designated Idefix. Like ZAM, Idefix displays the structural features of a vertebrate retrovirus. Its three open reading frames encode predicted products resembling the products of the gag, pol, and env genes of retroviruses. In situ hybridization and Southern analyses performed on the RevI genome revealed the presence of some 20 copies of ZAM and Idefix, whereas ZAM is absent and Idefix is present in only four copies on the chromosomal arms of the original parental line. From RevI, a series of mutations affecting eye coloration has been recovered. The genetic and molecular analyses of these mutations have shown that most of them affected the white locus through three rounds of mutational events. The first mutational event was previously shown to be caused by a ZAM insertion 3 kb upstream of the transcription start site of white. It confers a red-brick phenotype to the orange eye coloration of the parental line. The second event results from the insertion of an Idefix copy 1.7 kb upstream of the transcription start site of the white gene, which modifies the red-brick phenotype to orange. This second mutational event was recovered as a recurrent specific mutation in 11 independent individuals. The third event results from an additional Idefix located 1.7 kb upstream of white that is responsible for the full reversion of the orange phenotype to red-brick. The fact that such mutations due to recurrent appearances of both ZAM and Idefix at the white locus result in such a variety of phenotypes brings to light a new molecular system in which the interference of mobile elements with the correct expression of the host gene can be tested.

Alleles↗
PubMed1984

Transformation of white locus DNA in drosophila: dosage compensation, zeste interaction, and position effects.

P-element-mediated DNA transformation was used to generate transformants carrying segments of DNA from the white locus of D. melanogaster. The vast majority of transduced copies of an 11.7 or a 14.3 kb segment of DNA from white successfully rescued the white- eye-color phenotype when inserted in many different chromosomal locations. However, two transformants with abnormal eye pigmentation--apparently a consequence of the genomic positions of the transduced white gene--were also recovered. In all seven cases tested, autosomal insertions of white, which is dosage-compensated in its normal location on the X chromosome, retained the property of dosage compensation. In contrast to the relative insensitivity of eye-color pigmentation and dosage compensation to genomic position, the transduced white DNA segments differed widely in their interactions with the zeste mutation, ranging from greater than normal repression by zeste to insensitivity to the presence of zeste.

Animals↗
PubMed1994

Unusual properties of regulatory DNA from the Drosophila engrailed gene: three "pairing-sensitive" sites within a 1.6-kb region.

We have previously shown that a 2-kb fragment of engrailed DNA can suppress expression of a linked marker gene, white, in the P element vector CaSpeR. This suppression is dependent on the presence of two copies of engrailed DNA-containing P elements (P[en]) in proximity in the Drosophila genome (either in cis or in trans). In this study, the 2-kb fragment was dissected and found to contain three fragments of DNA which could mediate white suppression [called "pairing-sensitive sites" (PS)]. A PS site was also identified in regulatory DNA from the Drosophila escargot gene. The eye colors of six different P[en] insertions in the escargot gene suggest an interaction between P[en]-encoded and genome-encoded PS sites. I hypothesize that white gene expression from P[en] is repressed by the formation of a protein complex which is initiated at the engrailed PS sites and also requires interactions with flanking genomic DNA. Genes were sought which influence the function of PS sites. Mutations in some Polycomb and trithorax group genes were found to affect the eye color from some P[en] insertion sites. However, different mutations affected expression from different P[en] insertion sites and no one mutation was found to affect expression from all P[en] insertion sites examined. These results suggest that white expression from P[en] is not directly regulated by members of the Polycomb and trithorax group genes, but in some cases can be influenced by them. I propose that engrailed PS sites normally act to promote interactions between distantly located engrailed regulatory sites and the engrailed promoter.

Animals↗
PubMed1978

Effects of stimulus size, intensity, color, and eye strain on autokinetic movement: an error signal and noise analysis.

In two experiments, with a total of 116 male and female undergraduate S s, predictions were tested from the following hypothesized explanation of autokinetic movement (AKM): undetected eye drifts lead to movement of the AKM target across the retina; this movement or error signal leads to the initiation of a cancelling response, and the AKM is directly due to CNS monitoring of the efferent responses or signals sent to the eye muscles with subsequent detection of these signals against a background of efferent noise. The error signal variables studied were stimulus color (yellow or blue-green), stimulus intensity (dim or bright), and stimulus size (1.0 or .1 deg visual angle). Small, dim lights foveally viewed and yellow as opposed to blue-green lights led to significantly more error signals and hence more AKM as measured by mean number of perceived direction changes. Also, increasing retinal displacement by changing viewing angle (from zero to 60 deg) or increasing displacement by increasing diopter strength of prisms (from zero to 30) decreased AKM as measured by number of direction changes, and this effect is due at least in part to the increase in efferent noise caused by the increases in eye muscle tension involved. It was concluded that retinal displacement affects both error signal and noise variables in the AKM and, presumably, in the perception of real movement as well.

Color Perception↗
PubMed1988

Genetics of an unstable white mutant in Drosophila simulans: reversion, suppression and somatic instability.

A spontaneous white mutation, white-milky (wmky) of Drosophila simulans is moderately unstable and is associated with a 16-kb long DNA insertion into the white gene. wmky, which is an unstable mutation found in D. simulans, has been genetically analyzed. Among nine spontaneous, partial reversions toward wild type, five were white locus mutations. They are phenotypically different from each other and three show eye color sexual dimorphism indicating a failure of the dosage compensation mechanism. Two w locus mutations whose eye color appeared identical between males and females were also isolated. Of the other back-mutants, three were associated with a recessive suppressor of wmky and one was a semidominant suppressor. These suppressor loci are located on the third chromosome at map positions about 90 and 120, respectively. The suppressor mutations demonstrate specific effects on w locus mutations derived from wmky which lack in the gene dosage compensation. Somatic instability was detected at the frequency of 5.6 X 10(-4) in wmky flies heterozygous for the recessive suppressor and the frequency was increased 10-fold when the suppressor mutation was placed in a different genetic background.

Alleles↗
PubMed2003

deep-orange and carnation define distinct stages in late endosomal biogenesis in Drosophila melanogaster.

Endosomal degradation is severely impaired in primary hemocytes from larvae of eye color mutants of Drosophila. Using high resolution imaging and immunofluorescence microscopy in these cells, products of eye color genes, deep-orange (dor) and carnation (car), are localized to large multivesicular Rab7-positive late endosomes containing Golgi-derived enzymes. These structures mature into small sized Dor-negative, Car-positive structures, which subsequently fuse to form tubular lysosomes. Defective endosomal degradation in mutant alleles of dor results from a failure of Golgi-derived vesicles to fuse with morphologically arrested Rab7-positive large sized endosomes, which are, however, normally acidified and mature with wild-type kinetics. This locates the site of Dor function to fusion of Golgi-derived vesicles with the large Rab7-positive endocytic compartments. In contrast, endosomal degradation is not considerably affected in car1 mutant; fusion of Golgi-derived vesicles and maturation of large sized endosomes is normal. However, removal of Dor from small sized Car-positive endosomes is slowed, and subsequent fusion with tubular lysosomes is abolished. Overexpression of Dor in car1 mutant aggravates this defect, implicating Car in the removal of Dor from endosomes. This suggests that, in addition to an independent role in fusion with tubular lysosomes, the Sec1p homologue, Car, regulates Dor function.

Animals↗
PubMed2005

Pigmentary characteristics and moles in relation to melanoma risk.

Although benign and atypical moles are considered key melanoma risk factors, previous studies of their influence were small and/or institution-based. We conducted a population-based case-control study in the state of New Hampshire. Individuals of ages 20-69 with an incident diagnosis of first primary cutaneous melanoma were ascertained through the New Hampshire State Cancer Registry. Controls were identified through New Hampshire driver's license lists and frequency-matched by age and gender to cases. We interviewed 423 eligible cases and 678 eligible controls. Host characteristics, including mole counts, were evaluated using logistic regression analyses. Our results showed that pigmentary factors, including eye color (OR = 1.57 for blue eyes compared to brown), hair color (OR = 1.85 for blonde/red hair color compared to brown/black), freckles before age 15 (OR = 2.39 for freckles present compared to absent) and sun sensitivity (OR = 2.25 for peeling sunburn followed by no tan or a light tan and 2.42 for sunburn followed by tan compared to tanning immediately), were related to melanoma risk; these associations held after adjustment for sun-related factors and for moles. In analyses confined to skin examination participants, the covariate-adjusted effects of benign and atypical moles were moderately strong. Compared to 0-4 benign moles, risk increased steadily for 5-14 moles (OR = 1.71), 15-24 moles (OR = 3.55) and >or= 25 moles (OR = 4.33). Risk also increased with the number of atypical moles; compared to none, the ORs for having 1, 2-3, or >or= 4 atypical moles were 2.08, 1.84 and 3.80, respectively. Although risk was highest for those with multiple benign and atypical moles, the interaction was not of statistical significance. Our findings, arising from the first population- and incidence-based study to evaluate atypical moles in relation to melanoma risk, confirm the importance of host susceptibility, represented by pigmentary factors and the tendency to develop benign or atypical moles, in the etiology of this disease.

Adult↗