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At least 217 records · Page 12Linked to original sources

PubMed1998

Mariner transposition and transformation of the yellow fever mosquito, Aedes aegypti.

The mariner transposable element is capable of interplasmid transposition in the embryonic soma of the yellow fever mosquito, Aedes aegypti. To determine if this demonstrated mobility could be utilized to genetically transform the mosquito, a modified mariner element marked with a wild-type allele of the Drosophila melanogaster cinnabar gene was microinjected into embryos of a kynurenine hydroxylase-deficient, white-eyed recipient strain. Three of 69 fertile male founders resulting from the microinjected embryos produced families with colored-eyed progeny individuals, a transformation rate of 4%. The transgene-mediated complementation of eye color was observed to segregate in a Mendelian manner, although one insertion segregates with the recessive allele (female-determining) of the sex-determining locus, and a separate insertion is homozygous lethal. Molecular analysis of selected transformed families demonstrated that a single complete copy of the construct had integrated independently in each case and that it had done so in a transposase-mediated manner. The availability of a mariner transformation system greatly enhances our ability to study and manipulate this important vector species.

Aedes↗

PubMed1977

Mechanism of suppression in Drosophila. V. Localization of the purple mutant of Drosophila melanogaster in the pteridine biosynthetic pathway.

The suppressible eye color mutant purple (pr) of Drosophila melanogaster is known to be unable to synthesize a wild-type complement of pteridine eye pigments. This study measures the reduced levels of drosopterins, sepiapterin, and an unidentified presumed pteridine in pr and prbw. Pteridine analyses in double mutants combining pr with one of three other eye color mutants sepia, Henna-recessive3, and prune2, suggest that the metabolic block in pr occurs prior to sepiapterin biosynthesis. Measurements of GTP and GTP cyclohydrolase in pr showed wild-type levels and indicate the metabolic block in pr to be at one of the steps converting dihydroneopterin triphosphate to sepiapterin. Quantitation of pteridines in suppressed purple [su(s)2; pr and pr; su(pr)e3] shows restoration of pteridines to wild-type or nearly wild-type levels.

Aging↗

PubMed1986

Eye disease and color defects.

The groundwork for understanding color defects in eye disease was established by the end of the nineteenth century. Thereafter the field was neglected as scientists concentrated on studies of normal color vision and congenital color vision defects. Spurred by the development of the Farnsworth 100 hue-test, interest was renewed in the 1950s. The past 25 years have seen an explosion of interest in color defects in eye disease. The International Research Group on Color Vision Deficiencies has played an important role in this activity. The development of new clinical tests and instruments as well as refinement of laboratory techniques are among the important developments.

Color Perception Tests↗

PubMed1996

Transgene Coplacement and high efficiency site-specific recombination with the Cre/loxP system in Drosophila.

Studies of gene function and regulation in transgenic Drosophila are often compromised by the possibility of genomic position effects on gene expression. We have developed a method called transgene coplacement, in which any two sequences can be positioned at exactly the same site and orientation in the genome. Transgene coplacement makes use of the bacteriophage P1 system of Cre/loxP site-specific recombination, which we have introduced into Drosophila. In the presence of a cre transgene driven by a dual hsp70-Mos1 promoter, a white reporter gene flanked by loxP sites is excised with virtually 100% efficiency both in somatic cells and in germ cells. A strong maternal effect, resulting from Cre recombinase present in the oocyte, is observed as white or mosaic eye color in F1 progeny. Excision in germ cells of the F1 yields a strong grand-maternal effect, observed as a highly skewed ratio of eye-color phenotypes in the F2 generation. The excision reactions of Cre/loxP and the related FLP/FRT system are used to create Drosophila lines in which transgenes are at exactly allelic sites in homologous chromosomes.

ATP-Binding Cassette Transporters↗

PubMed2002

Unassisted isolated-pair mating of Anopheles gambiae (Diptera: Culicidae) mosquitoes.

Female Anopheles mosquitoes usually mate only once, but mating is seldom seen in small containers containing only one female and male. Therefore, matings are often performed among many adults in large cages or by forced copulation. Isolated-pair mating of Anopheles gambiae G3 strain-derived mosquitoes without forced copulation in small vials is described. We observed that the experimental variables eye color and male number were significant factors in the mating frequency. Females mated more frequently when three males were present over only one male. White-eyed females were more likely to be mated than wild-eyed females, but wild males mated more frequently than did white-eyed males. Experiments were also conducted to determine when mating was occurring by using wild-eye-color mosquitoes in isolated pairs. Almost no matings were observed before day 6 rather than the frequencies typically observed after 1-2 d in standard large-cage matings among large numbers of adults.

Animals↗

PubMed1982

Ultrastructural, histochemical, and biochemical studies of the melanin metabolism in eye and skin of pallid mice.

The hair follicles and the eyes of pallid mice (C57/6J-Pa/Pa) and those of black mice (C57/6J-+/Pa) were examined ultrastructurally, histochemically, and biochemically to determine the cause of pigment dilution. The pigment cells in the hair follicles and the eyes of pallid mice have less mature melanosomes than those of black mice. In the hair follicles the pallid melanosomes were transferred into keratinocytes and became aggregated. In the eyes they were already aggregated within the pigment cells and were digested in acid phosphatase-positive lysosomes. The activity of acid phosphatase, a marker of lysosomal enzymes was significantly higher in pallid hair follicles and eyes than in black hair follicles and eyes. Dopa reactions at light and electron microscopical level indicated that the pigment cells in each tissue produced a large amount of Dopa oxidase when compared with those in each black counterpart. However, the rate of hydroxylation of L-tyrosine-3,5-3H was significantly lower in the pallid eyes than in black eyes, while this rate was significantly higher in pallid hair follicles than in black hair follicles. Immediate digestion of melanosomes within the pigment cells, i.e., autophagocytosis, seemed to explain the low activity in the pallid eyes. The diluted coat and eye colors of pallid mice are, therefore, not related to low Dopa oxidase activity but to immaturity of melanosomes and high activities of lysosomal enzymes; these enzymes seem to digest many of these immature melanosomes and contribute to the diluted coat and eye colors of pallid mice.

Animals↗

PubMed1992

[Enhancer-of-white-apricot and its effects on the copia insertion allele white-apricot in Drosophila melanogaster].

In Drosophila melanogaster, the w(a) allele differs from the red-eye gene (w+) by the insertion of the retrovirus-like transposable element copia within the transcription unit. The w(a) flies have the apricot eye color. Most RNAs derived from w(a) have 3' termini within the 3' LTR of copia, and only small amounts of structurally normal RNA are produced. The eye color of flies with w(a) is affected by the gene Enhancer-of-white-apricot [E(w(a))] and become lighter. This effect on pigmentation is correlated with a corresponding decrease in white RNA having wild-type structure which was determined by the Northern blot. Three revertant alleles of E(w(a)) was generated by the irradiation with gamma-ray. These alleles are recessive lethals with death occurring during the larval stage. The original E(w(a)) allele is an antimorph and produces a product that interferes with the activity of the wild-type gene which have the product expected to either have a positive role in the splicing of w(a) RNAs or a negative role in polyadenylation.

Alleles↗

PubMed2002

Risk factors for epithelial erosions in laser in situ keratomileusis.

PURPOSE: To determine the risk factors for an epithelial defect during laser in situ keratomileusis (LASIK). SETTING: LASIK Vision, Toronto, Ontario, Canada. METHODS: In this prospective cohort study, 926 patients (1852 eyes) presenting for LASIK over a 6-month period were evaluated for age, sex, Fitzpatrick Skin Type (FST), eye color, hair color at 3 years of age, facial skin wrinkling, ethnicity (Lancer Ethnicity Scale [LES]), keratometry, Schirmer I reading, corneal thickness, and preexisting signs of corneal epithelial dystrophy. In all patients, LASIK was performed using the Technolas 217 laser (Bausch & Lomb), the Hansatome(R) microkeratome (Bausch & Lomb), and the same nomogram settings. RESULTS: Fourteen percent of patients had significant epithelial fragility. In patients with FST I or II or LES 1 or 2, the relative risk of an epithelial defect was 10 times greater than in other patients; in those older than 40 years, it was 6 times greater than in other patients; in those with lighter hair or eye color, it was 2 to 3 times greater than in patients with darker hair or eyes. There was no significant difference in pachymetry, vertical or horizontal keratometry, or Schirmer readings between eyes with epithelial defects and eyes without. CONCLUSIONS: The risk of epithelial erosions during LASIK strongly correlated with patients' skin type and age.

Adult↗

PubMed1981

Skin and eye diseases among arc welders those exposed to welding operations.

The prevalence of skin and eye abnormalities was determined in 77 journeymen welders, 75 members of other trades exposed to welding operations and 58 non-exposed comparison workers. Characteristics including possible risk factors for skin cancer were compared among the groups. Localized cutaneous erythema was frequent in welders and occasional in other exposed workers. Small cutaneous scars were frequent in welders. There was no significant difference in the prevalence of actinic elastosis by occupational group; however, the degree of elastosis was significantly associated with type of complexion, original hair color, eye color, childhood freckling poor ability to tan and ease of sunburning. There were no significant difference among the groups in the prevalence of various dermatoses, skin tumors, alterations in visual acuity or clinical ocular abnormalities on slit lamp biomicroscopy and fundoscopy apart from variations in the amount of dust in the lids. The observed prevalences of skin and eye diseases may provide useful comparative data.

Adult↗

PubMed1971

Eye lens color: formation and function.

Aromatic amino acids are photooxidized by near-ultraviolet light to colored products that are bound very tightly to protein amino groups. The resulting colored proteins absorb near-ultraviolet light more strongly and are rendered more hydrophobic than the untreated compounds, and they fluoresce at 440 nanometers when excited at 360 nanometers. Coloration in the lenses of diurnally active animals (including man) may be caused by this reaction, and senile cataracts may result. Such changes in many other proteins (as in the skin and retina) could lead to more serious consequences.

Aging↗

PubMed1997

Analysis of blink rate patterns in normal subjects.

The present study measured the normal blink rate (BR) variations in relation to behavioral tasks in 150 healthy volunteers (70 males and 80 females; aged 35.9 +/- 17.9 years, range 5-87 years). The subjects were videotaped in a standard setting while performing three different tasks: resting quietly, reading a short passage, talking freely. The mean BR was computed during each task; the data were compared by means of analysis of variance and Student's t tests. Mean BR at rest was 17 blinks/min, during conversation it increased to 26, and it was as low as 4.5 while reading. As compared with rest, BR decreased by -55.08% while reading (p < 1 x 10(-15)) and increased by 99.70% during conversation (p < 1 x 10(-9)). As compared with reading, BR increased during conversation by 577.8% (p < 1 x 10(-17). The distribution curves were highly reproducible in each task. The best curve fit was represented by a log-normal distribution, with the upper tail of each curve having a normal distribution. Eye color and eyeglass wearing did not influence BR. Women had higher BR than men just while reading. No age-related differences were found. The most common BR pattern was conversation > rest > reading, which occurred in 101 subjects (67.3%); 34 subjects (22.7%) had the pattern rest > conversation > reading; 12 (8.0%) had the pattern conversation > reading > rest. This study identified three normal behavioral BR patterns and showed that BR is more influenced by cognitive processes than by age, eye color, or local factors. The present findings provide a normal reference for the analysis of BR in movement disorders such as dystonia or tics.

Adolescent↗

PubMed1995

The white gene of Ceratitis capitata: a phenotypic marker for germline transformation.

Reliable germline transformation is required for molecular studies and ultimately for genetic control of economically important insects, such as the Mediterranean fruit fly (medfly) Ceratitis capitata. A prerequisite for the establishment and maintenance of transformant lines is selectable or phenotypically dominant markers. To this end, a complementary DNA clone derived from the medfly white gene was isolated, which showed substantial similarity to white genes in Drosophila melanogaster and other Diptera. It is correlated with a spontaneous mutation causing white eyes in the medfly and can be used to restore partial eye color in transgenic Drosophila carrying a null mutation in the endogenous white gene.

ATP-Binding Cassette Transporters↗

PubMed2000

The prevalence of seborrheic keratoses in people aged 15 to 30 years: is the term senile keratosis redundant?

BACKGROUND: Seborrheic keratoses (SKs) are common skin lesions that have been shown to occur with increasing age, although the age of onset is not well recorded. OBJECTIVE: To determine the prevalence, nature, and distribution of SKs in young people. METHODS: One hundred seventy people aged 15 to 30 years were given a total body examination during which the presence, number, site, and size of SKs were recorded. Biopsy specimens were taken from the first 22 people who had lesions clinically diagnosed as SKs. Data on age, skin type, eye color, and hair color were recorded for all respondents. RESULTS: Forty (23.5%) of 170 respondents had at least one SK, with no significant difference between the sexes. There was an increase in prevalence with age from 15.7% in 15- to 19-year-olds to 32.3% in those aged 25 to 30 years. The size of the SKs also increased with age. A total of 77.5% of SKs were found on the trunk and 22.5% on the limbs, head, and neck. There was no correlation between SKs and any particular hair and eye color or skin type. CONCLUSIONS: These findings confirm that SKs are common lesions in young Australians, appearing in a substantial proportion of people younger than 30 years. The term senile keratosis is no longer appropriate for these lesions.

Adolescent↗

PubMed2003

A mariner-like element with a 5' lesion in Drosophila simulans.

The unstable white-S2 (wS2) allele of the white gene occurred spontaneously in the S2 strain of Drosophila simulans. This mutation was caused by insertion of the submariner element, a mariner-like element with an abnormal tandem duplication of the 5' inverted terminal repeat (ITR). Although it has an incomplete ITR, submariner excises efficiently. The rate of somatic reversion, estimated by the number of eye-color mosaic flies, was 79.9%, and the reversion frequency in the germline was 0.6%. The change to the 5' ITR contributes to make this transposon precise excision.

ATP-Binding Cassette Transporters↗

PubMed1996

The somatic white-ivory eye spot test does not detect the same spectrum of genotoxic events as the wing somatic mutation and recombination test in Drosophila melanogaster.

A groups of six chemical compounds was tested in parallel in two different somatic genotoxicity assays in Drosophila melanogaster, the wing somatic mutation and recombination test (SMART) and the white-ivory eye spot test. The wing spot test makes use of the wing cell markers multiple wing hairs (mwh) and flare (flr) and detects both mitotic recombination and various types of mutational events. The white-ivory eye spot test makes use of the white-ivory (wi) quadruplication and detects the somatic reversion of the recessive eye color mutation wi to the wild-type (w+). Three- or two-day-old larvae were fed chronically with the compounds ethylnitrosourea (ENU), N-nitrosopyrrolidine (NNP), caffeine (CAF), chromium (VI) oxide (CRO), potassium chromate (POC), and 2,4-dichlorophenoxyacetic acid (2,4-D). All six compounds are genotoxic to various degrees in the wing spot test. The percentage of the genotoxic activity that is due to mitotic recombination was between 84% and 91% for the hexavalent chromium compounds CRO and POC and about 68% for 2,4-D. In contrast, ENU and NNP showed only 46% and 25% recombinagenic activity, respectively. In the white-ivory eye spot test, the three compounds (CRO, POC, and 2,4-D) with high recombinagenic activity and CAF were clearly nongenotoxic, whereas only ENU and NNP gave a positive response. From these results, it is concluded that the spectrum of genotoxic events detected by the two assays is different. In particular, the white-ivory eye spot test appears not to detect mitotic recombination the way the wing spot test does.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2002

RNAi related mechanisms affect both transcriptional and posttranscriptional transgene silencing in Drosophila.

Two types of transgene silencing were found for the Alcohol dehydrogenase (Adh) transcription unit. Transcriptional gene silencing (TGS) is Polycomb dependent and occurs when Adh is driven by the white eye color gene promoter. Full-length Adh transgenes are silenced posttranscriptionally at high copy number or by a pulsed increase over a threshold. The posttranscriptional gene silencing (PTGS) exhibits molecular hallmarks typical of RNA interference (RNAi), including the production of 21--25 bp length sense and antisense RNAs homologous to the silenced RNA. Mutations in piwi, which belongs to a gene family with members required for RNAi, block PTGS and one aspect of TGS, indicating a connection between the two types of silencing.

ATP-Binding Cassette Transporters↗

PubMed1998

Human matrix attachment regions insulate transgene expression from chromosomal position effects in Drosophila melanogaster.

Germ line transformation of white- Drosophila embryos with P-element vectors containing white expression cassettes results in flies with different eye color phenotypes due to position effects at the sites of transgene insertion. These position effects can be cured by specific DNA elements, such as the Drosophila scs and scs' elements, that have insulator activity in vivo. We have used this system to determine whether human matrix attachment regions (MARs) can function as insulator elements in vivo. Two different human MARs, from the apolipoprotein B and alpha1-antitrypsin loci, insulated white transgene expression from position effects in Drosophila melanogaster. Both elements reduced variability in transgene expression without enhancing levels of white gene expression. In contrast, expression of white transgenes containing human DNA segments without matrix-binding activity was highly variable in Drosophila transformants. These data indicate that human MARs can function as insulator elements in vivo.

ATP-Binding Cassette Transporters↗

PubMed2002

Sun exposure predicts risk of ocular melanoma in Australia.

Previous studies examining sun exposure and ocular melanoma have produced inconsistent results. We investigated this association in a population-based case-control study in Australia. Cases (n = 290) aged 18-79 years were diagnosed between January 1996 and July 1998. Controls (n = 893) were randomly selected from the electoral rolls and frequency-matched to cases by age, sex and state. A self-administered questionnaire and a telephone interview measured sun exposure on weekdays and weekends at 10, 20, 30 and 40 years of age and over the whole of life for specific jobs and recreations. Multivariate logistic regression models of ocular melanoma and sun exposure contained age, sex, region of birth, eye color and measures of ocular and cutaneous sun sensitivity as covariates. Choroid and ciliary body melanoma (n = 246) was positively associated with time outdoors on weekdays and, less persuasively, total time outdoors but not ambient solar irradiance. Odds ratios increased with increasing exposure to OR 1.8 (95% confidence interval 1.1-2.8) for the highest quarter of sun exposure on weekdays up to 40 years of age for men and women together. The strongest positive associations were for total exposure up to 40 years of age, lifetime occupational exposure and total exposure at about 20 years of age in men; all had odds ratios between 2 and 3 in the highest exposure categories. There was inconclusive evidence for an association between sun exposure and iris (n = 25) or conjunctival (n = 19) melanomas. Sun exposure is an independent risk factor for choroidal and ciliary body melanoma in Australia.

Adolescent↗