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PubMed1996

Molecular cloning of a mammalian ABC transporter homologous to Drosophila white gene.

Pigmentation of Drosophila eyes requires the concerted action of several genes, most of which have been cloned and characterized. Three of them, white, brown, and scarlet, have been directly implicated in the import of pigment precursors into the cells. These three genes encode similar proteins, belonging to the evolutionary conserved family of ATP Binding Cassette transporters. The identification of a novel mouse gene, ABC8, closely related to white is reported here, together with an analysis of its expression profile and its comparative mapping in mouse and human genome.

ATP-Binding Cassette Transporters↗
PubMedDate not supplied

Visual pigments, cone oil droplets and ocular media in four species of estrildid finch.

A microspectrophotometric study was conducted on the retinal photoreceptors of four species of bird: cut-throat finches (Amadina fasciata), gouldian finches (Erythrura gouldiae), white-headed munias (Lonchura maja) and plum-headed finches (Neochmia modesta). Spectral characteristics of the photoreceptors in all four species were very similar. Rods contained a medium-wavelength-sensitive visual pigment with a wavelength of maximum absorbance at 502-504 nm. Four spectrally distinct types of single cone contained a visual pigment with wavelength of maximum absorbance at either 370-373 nm (ultraviolet-sensitive), 440-447 nm (short-wavelength-sensitive); 500 nm (medium-wavelength-sensitive) or 562-565 nm (long-wavelength-sensitive). Oil droplets in the ultraviolet-sensitive single cones showed no detectable absorption between 330 nm and 800 nm. Oil droplets in the short-, medium-, and long-wavelength-sensitive single cones had cut-off wavelengths at 415-423 nm, 510-520 nm and 567-575 nm, respectively. Double cones contained the visual pigment with wavelength of maximum absorbance at 562-565 nm observed in long-wavelength-sensitive single cones. Only the principal member of the double cone pair contained an oil droplet (P-type, cut-off wavelength at 414-489 nm depending on species and retinal location). Spectral transmittance of the intact ocular media of each species was measured along the optic axis. Wavelengths of 0.5 transmittance for all species were very similar (316-318 nm).

Animals↗
PubMed1997

The visual acuity of the frog (Rana pipiens).

The frog's visual acuity for gratings was tested with a two-choice prey-dummy setup. The two dummies had a constant position in the visual field, but in one of them a striped pattern was constantly drifting, while the other was a potentially less attention arousing dummy with non-moving stripes. The acuity was tested in bright white light and with different brightness levels of green light (500 nm). The highest acuity 2.8 cycles per degree was achieved with the maximum level of green light. When the brightness was lowered by six orders of magnitude the acuity fell to 0.7 cycles per degree. These behavioural acuities are compared with a theoretically calculated resolving power of the retinal ganglion cell array.

Animals↗
PubMed2006

Variations of the melanocortin-1 receptor and the glutathione-S transferase T1 and M1 genes in cutaneous malignant melanoma.

Variations in the melanocortin-1 receptor (MC1R) and in the glutathione-S transferase genes mu1 (GSTM1) and theta 1 (GSTT1) have been reported to influence UV sensitivity and melanoma risk. MC1R is one of the major genes that determine skin pigmentation because the melanocortin-1 receptor regulates eumelanin synthesis. GSTT1 and GSTM1 are enzymes expressed in the skin that detoxify products of oxidative stress reactions caused by UV irradiation. In this study variations in the MC1R, GSTM1 and T1 genes were analyzed in 347 healthy subjects and 322 patients with cutaneous malignant melanoma by direct cycle sequencing, RFLP and multiplex PCR. Important phenotypic characteristics of the study participants were obtained to assess whether genetic associations occurred independently of phenotypic risk factors for melanoma. We found an association of the MC1R D84E and R151C polymorphisms with melanoma (odds ratios for carriage of the rare allele 4.96, 95% CI [1.06-23.13], P = 0.032, and 1.69, 95% CI [1.12-2.55], P = 0.013, respectively). Melanoma risk increased with the number of variant MC1R alleles carried by an individual (P = 0.003). In a multivariate model, however, only the D84E polymorphism influenced melanoma risk independently of the risk factors fair skin type, high nevus count and high age (P = 0.047). There was no effect of homozygous GST M1 or T1 deletions on melanoma risk. In contrast to previous data, there was no evidence that GSTM1 deficiency influences melanoma risk in the subgroup of individuals with red or blond hair.

Adult↗
PubMed1998

Repetitive arrays containing a housekeeping gene have altered polytene chromosome morphology in Drosophila.

Much of our understanding of gene and chromatin organization has been developed from observation of polytene chromosomes. We describe an experimental approach using transgenes that has allowed us to observe local changes in polytene morphology. A composite P transposon that contains a fusion between the regulatory region of Prat, a purine synthesis gene, and brown (bw), an eye pigment reporter, was transformed into the 65A10 polytene band and subjected to P-transposase mutagenesis. Arrays of up to 320 kb at 65A10 were recovered by selection for increased pigment, and pigment levels were found to be proportional to numbers of copies. In polytene chromosomes, the original transformant was found to split 65A10 into two thin bands separated by an interband. With increases in copy number, the interband became progressively denser, eventually forming a dark, amorphous, deformable structure unlike any previously reported. The persistence of Prat expression in development, together with the cytological appearance of these large arrays, suggest that the state of the Prat promoter is affecting polytene structure. Because this unique structure is distinct from bands, interbands, puffs, and the chromocenter, which comprise polytene chromosomes, we suggest that it is composed of an altered form of chromatin.

Animals↗
PubMed2002

Genomic imprinting in Drosophila is maintained by the products of Suppressor of variegation and trithorax group, but not Polycomb group, genes.

Genomic imprinting is a form of epigenetic inheritance that is characterized by differential expression of a gene depending on its parental origin. The mini-X chromosome Dp(1;f)LJ9 in Drosophila shows this type of classical imprinting; when transmitted by the maternal parent genes on this chromosome are fully expressed, but when the chromosome is transmitted by the male parent at least three genes are subject to silencing, resulting in a variegated expression pattern. Chemical and environmental modifiers of position-effect variegation have been shown to alter the somatic maintenance of the imprint. To extend these observations, several mutations in chromatin-associated proteins were examined for their effect on imprinting on the Dp(1;f)LJ9 mini-X chromosome. Effects on establishment and maintenance were independently assessed by genetically associating the mutations in chromatin modifiers with the mini-X chromosome in either the parents, where the imprint is established, or the progeny, in which the imprint must be maintained. Nine Suppressor of variegation [ Su(var)] mutations, including alleles of the Su(var)2-5 gene, which encodes the well characterized heterochromatin-associated protein HP1, abolished maintenance but not the establishment of the imprint. Mutant alleles of two genes in the trithorax group ( trx-G), brahma and trithorax, showed a maternal-effect enhancement of the paternal imprint. Surprisingly, however, with the exception of an Enhancer of Polycomb [ E(Pc)] allele, none of the Polycomb-group ( Pc-G) mutations tested affected the imprint. Thus, the maintenance of this imprint relies on the wild-type products of Su(var) and trx-G, but not Pc-G, genes. Finally, none of the mutations tested affected the maintenance of the maternal imprint or the establishment of either the maternal or paternal imprint, suggesting that the maternal and paternal imprints depend on different molecular processes and that imprint establishment and maintenance are independently regulated.

Animals↗
PubMed1996

Inheritance patterns of new genetic markers and occurrence of spontaneous mosaicism in the monogenic blowfly Chrysomya rufifacies (Diptera:Calliphoridae).

Four new genetic markers for Chrysomya rufifacies, a fly with maternal sex determination, were characterized. The markers include one body colour mutant, black body (bl), and three eye colour mutants, brown eye (br), apricot eye (ap), and red eye (wr). Two of the latter, br and wr, turn out to be sex linked, the others behave as autosomal genes belonging to different linkage groups. wr is a hypomorphic and w an apomorphic mutation of the white gene, w/w is epistatic to br/br and to ap/ap. A preliminary genetic linkage map with the sex realizer F'/f and the loci br and w residing in homomorphic sex chromosomes is established. Evidence is presented that crossing over is absent in the male sex. The possible causes of the spontaneous appearance of mosaics for eye colour observed among individuals heterozygous for recessive genes are discussed.

Animals↗
PubMed1997

Molecular characterization of the deep orange (dor) gene of Drosophila melanogaster.

Mutations of the dor gene of Drosophila melanogaster cause defects in different stages of development. Heterozygotes for lethal or viable dor alleles and the rearrangement T(1;2)dor(var7), which causes position effect variegation of dor, exhibit traits such as rough eyes, reduction of bristles on the thorax and scutellum and wavy wings. The dor gene was mapped to the proximal part of the 2B3-5 band or in the interband between 2B3-5 and 2B6 and localised within an interval of 5 kb on the physical map of the cloned 2B region. The 3.0-3.1 kb dor transcript was detected by Northern hybridization at all stages of development and is expressed in salivary glands of third instar larve. This RNA was not expressed in the dor mutants with insertions in the 5' part of the gene. The sequence of the 3180 bp (dor cDNA predicts a 115.3 kDa protein that contains a cysteine- and histidine-rich zinc finger-like motif CX2CX13CXHX2HX2CX2H at the C-terminus. The protein sequence reveals 23% identity to the Saccharomyces cerevisiae PEP3 protein. The most significant homology (57%) similarity and 32%, identity) between the DOR and PEP3 proteins is observed at the C-termini of the proteins.

Amino Acid Sequence↗
PubMed2006

Preliminary study on eye colour in Japanese macaques (Macaca fuscata) in their natural habitat.

Eye colour in Japanese macaques shows apparent differences between individuals, continuously ranging from orange (bright), through shades of yellow and hazel-blue to dark blue (dark). We arbitrarily classified them into either 'yellow' eyes or 'blue' eyes based on the yellow area occupying in the iris' peripupillary ring. Most Japanese macaques have yellow eyes after infant phase, whilst 19, 17, 12, and 15% of monkeys (>6 months, sexes combined) have blue-eye in studied two groups of Shodoshima and two groups of Takasakiyama, respectively. Frequency of eye colour did not differ between males and females, but significantly differed in each age class. Blue eyes significantly more frequently occurred in newborns, infants and aged monkeys than in juveniles and prime adults. Data from mother-infant pairs indicated eye colour could be inherited from their parents. A case of asymmetric eye colour in Japanese macaques was found from a sample of 1962 individuals. Eye colour variation of Japanese macaques was discussed in relation to those of humans and rhesus macaques. A possible evolutionary model of eye colour in Japanese macaques was discussed.

Age Factors↗
PubMedDate not supplied

A prospective study of iridial pigmentation and eyelash changes due to ophthalmic treatment with latanoprost.

PURPOSE: To conduct a 12-month prospective study on the occurrence of latanoprost-induced iridial pigmentation and eyelash change in Japanese patients with glaucoma METHODS: Seventy-five patients (75 eyes) were enrolled in the study. Photographs of the iris and eyelashes were taken under identical conditions before and after treatment. Three glaucoma specialists assessed the iridial pigmentation/eyelash change independently with no knowledge of patient data. The effects of age, sex, concomitant medication, and type of glaucoma on iridial pigmentation/eyelash change were investigated, and intraocular pressure (IOP) reduction and iridocorneal angle pigmentation before and after latanoprost treatment were compared between patients with iridial pigmentation/eyelash change and patients without these changes. RESULTS: The incidence of iridial pigmentation was 6.3% at 1 month, 15.7% at 3 months, 37.8% at 6 months, and 56.5% at 12 months. The incidence of eyelash change was 0% at 1 month, 33.8% at 3 months, 44.4% at 6 months, and 46.2% at 12 months. Latanoprost did not affect IOP reduction or iridocorneal angle pigmentation. No significant relationship between iridial pigmentation and eyelash change was observed. None of the investigated parameters except age affected the iridial pigmentation/eyelash change. CONCLUSION: Iridial pigmentation and eyelash change occurred at a high frequency in long-term treatment with latanoprost in Japanese glaucoma patients.

Adult↗
PubMed2005

Sun exposure, phenotypic characteristics, and cutaneous malignant melanoma. An analysis according to different clinico-pathological variants and anatomic locations (Italy).

OBJECTIVE: The aim of the study was to examine the relation between sun exposure and other selected risk factors and the development of different clinico-pathological variants of cutaneous malignant melanoma (CMM) at different body locations. METHODS: We analysed data from a case-control study conducted in Italy between 1992 and 1994 on 542 cases of CMM and 538 hospital controls. Clinico-pathological variants included 391 superficial spreading (SSM), 72 nodular (NM) and 39 lentigo maligna (LMM) melanomas. RESULTS: The risk of SSM increased for a high education level (odds ratio, OR = 1.5, 95% confidence interval, CI, 1.0-2.2), sunburn episodes before age 15 (OR = 1.8, 95% CI, 1.1-2.8), light eye colour (OR = 1.6, 95% CI, 1.1-2.4) and solar lentigines (OR = 1.4, 95% CI, 1.0-1.8). The ORs for total number of nevi >30 were 4.4 (95% CI, 2.9-6.7) for SSM, 5.7 (95% CI, 2.6-12.5) for NM and 2.2 (95% CI, 0.5-9.4) for LMM. The risk of CMM located on the trunk seemed to be higher for a high education level (OR = 1.6, 95% CI, 1.0-2.6) and propensity to sunburn (OR = 1.6, 95% CI, 0.8-3.2). The ORs for sunburn episodes, eye and skin colour, and solar lentigines tended to be higher for CMM located on the face/neck and on the upper limbs than the trunk. Total number of nevi was strongly associated with all anatomic locations. CONCLUSIONS: Total number of nevi was the major risk factor associated with all melanoma variants and locations. A higher level of education and sunburn episodes in early childhood appeared to be more strongly related to SSM than to other variants.

Adolescent↗
PubMed1983

Side effects and possible contraindications of amiodarone use.

With the increasing use of amiodarone, several unwanted effects have been recognized. We reviewed 140 patients treated with amiodarone over a 5-year period in an attempt to identify patients at risk, to assess the incidence of these effects and their possible relation to dose, and to determine their outcome. The most common effect was photosensitivity (57% of patients responding to a questionnaire), whereas asymptomatic corneal microdeposits were found in all patients undergoing ophthalmologic examination. In contrast, symptomatic eye changes (colored halos) and slate-gray skin pigmentation were rare. Of the metabolic alterations, the rise in hepatic enzymes correlated with dose and plasma drug and metabolite concentrations (r = 0.59, p less than 0.001; r = 0.62, p less than 0.001, respectively) but was not associated with clinical disease. This relation to dose was not evident in patients developing clinical thyroid abnormalities (two hypothyroidism, two hyperthyroidism), all of whom had normal thyroid function prior to therapy. Four of the five hypothyroid patients were over 70 years of age. No patients developed peripheral neuropathy, but tremor and sleeplessness were common complaints (30% and 28% of patients, respectively) that responded to a decrease in dose. One patient with an abnormal chest x-ray film prior to therapy developed pulmonary fibrosis. We suggest the restricted use of high doses of amiodarone for protracted periods. Patients at particular risk are the older age group (hypothyroidism) and those with abnormal lung function prior to therapy who may be predisposed to pulmonary alveolitis. Most of the observed unwanted effects resolve when amiodarone is decreased in dose or discontinued.

Aged↗
PubMed1979

Mydriatic effect of anticholinergic drugs used during reversal of nondepolarizing muscle relaxants.

Large doses of anticholinergic drugs (atropine, glycopyrrolate) produced mydriasis in a group of adults with no eye abnormalities except strabismus, though the usual intramuscular and intravenous doses of these drugs do not have this tendency. Such large doses are often given intravenously during general anesthesia to prevent the side effects of neostigmine methylsulfate, which is used to reverse the effect of nondepolarizing muscle relaxants. Neostigmine methylsulfate (Prostigmin) reduced the mydriatic effect when given intravenously in conjunction with atropine or glycopyrrolate. Mydriasis was more likely to occur in lightly pigmented eyes than in eyes with dark irides. Pilocarpine eyedrops instilled at the beginning of anesthesia caused miosis that persisted after the large intravenous doses of atropine or glycopyrrolate were given. To prevent an attack of acute angle-closure glaucoma in any patient who is to receive large doses of anticholinergic drugs during general anesthesia, miotic drug therapy should be continued before, during, and after anesthesia at the same frequency as when awake.

Adolescent↗