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PubMed1986

Germ line and somatic instability of a white mutation in Drosophila mauritiana due to a transposable genetic element.

A spontaneous white mutation recovered in Drosophila mauritiana is unstable and reverts to normal eye color at a frequency greater than 4 per 1,000 X-chromosomes. Germ line reversion occurs at a high rate in D. mauritiana males and in interspecific hybrid females, while the rate is depressed in D. mauritiana females. These events are not restricted to the germ line, as cases of variegated patterns of eye pigmentation, indicating somatic reversion, are recovered at a frequency comparable to that of the male germ line reversion rate. Germ line reversion events are genetically stable, while the somatic variegation patterns are not heritable. The patterns of eye pigment variegation produced suggests that reversion events are occurring throughout development. Whole genome DNA digests blotted and probed with the cloned D. melanogaster white gene indicate that this unstable white mutation in D. mauritiana is associated with an insertion of DNA that is lost upon reversion to wild type, indicating that this DNA insert is in fact a transposable element.

Animals↗
PubMed1982

Synaptogenesis in the first optic neuropile of the fly's visual system.

The developmental transformation of the chief afferent class of fly photoreceptor synapse has been examined from serial electron micrographs of animals fixed at 74, 81, 94 and 100% pupal development (100% pupal development being defined by the time of normal adult eclosion). Animals were selected both by their age and the conformity of their eye coloration to standards for each stage. Two animals were analysed from each stage, one in greater detail than the other. For the first, the exact coordinates of the cartridges (the synaptic columns of the first optic neuropile) from which the analyses were made were mapped and selected to be within the same region of the eye field at all stages. From all animals a portion of one or two cartridges was analysed from series of up to 100 sections and the synapse populations (greater than 80) were analysed for their fine structure and postsynaptic composition. Adult synapses are confirmed as tetrads, with two of the four postsynaptic elements invariably from two monopolar interneurons L1 and L2, one from each. The two others are usually from alpha processes of the same amacrine cell. Synapses appear during the last half of pupal development, with no obvious asynchrony of ultrastructural maturation and in parallel with those of at least one of the other synaptic classes present (which were otherwise not studied). Many adult features of synaptic ultrastructure emerge late, only by 94% pupal development. These include adult numbers of synaptic vesicles, the complete form of the presynaptic ribbon with platform and the postsynaptic cisternae of L1/L2. Prior to 94% the synapses are smaller with postsynaptic elements having a less regular geometry and with postsynaptic densities which are subsequently lost (alpha processes) or replaced by cisternae (L1/L2). At the presynaptic sites of the younger animals (74%, 81%) dyads and triads of postsynaptic elements coexist with tetrads, those of older animals having, on average, more postsynaptic processes per synapse. It is suggested that individual synapses assemble piecemeal, element by element.

Afferent Pathways↗
PubMed2002

Lesions of the fusiform face area impair perception of facial configuration in prosopagnosia.

BACKGROUND: Prosopagnosia, the inability to recognize faces, is associated with medial occipitotemporal lesions, especially on the right. Functional imaging has revealed a focal region in the right fusiform gyrus activated specifically during face perception. OBJECTIVE: The study attempted to determine whether lesions of this region were associated with defects in face perception in patients with prosopagnosia. METHODS: Five patients with acquired prosopagnosia were tested. They were asked to discriminate faces in which the spatial configuration of features had been altered. This was contrasted with their discrimination of changes in feature color, an alteration that does not affect spatial relations. RESULTS: All four patients whose lesions included the right fusiform face area were severely impaired in discriminating changes in the spatial position of features. The one patient with anterior bilateral lesions was normal in this perceptual ability. For three of the five patients, accuracy was normal for changes in eye color. When subjects knew that only changes in mouth position would be shown, performance improved markedly in two of the four patients who were impaired in the initial test. CONCLUSION: Perception of facial configuration is impaired in patients with prosopagnosia whose lesions involve the right fusiform gyrus. This deficit is especially manifest when attention must be distributed across numerous facial elements. It does not occur with more anterior bilateral temporal lesions. Loss of this ability may contribute to the recognition defect in some forms of prosopagnosia.

Adult↗
PubMed1986

Spectrally selective flash early receptor potential (ERP) in dichromats.

The human spectrally selective flash early receptor potential (ERP) was studied in 12 dichromats: 6 protanopes (12 eyes) and 6 deuteranopes (12 eyes). Color filters used were Kodak Wratten filters No.23A, No.57, and No.47 for the red, green, and blue flash ERPs, respectively. The ERP amplitude was measured between the summits of R1 and R2. Mean amplitudes of the red flash ERP and green flash ERP were highly significantly decreased in the protanopes (p less than 0.001) and deuteranopes (p less than 0.01) as compared with the corresponding data in 10 normal subjects (20 eyes). The mean amplitude of the blue flash ERP was significantly lower than normal (p less than 0.001) in the deuteranopes. The mean ratio of the blue flash ERP amplitude to the red flash ERP amplitude showed a highly significant increase in the protanopes (p less than 0.001) and a highly significant decrease in the deutoranopes (p less than 0.001) compared with the mean ratio in the normal subjects, indicating a new, useful index for the objective clinical detection of congenital color defects.

Adolescent↗
PubMed2006

Insulated piggyBac vectors for insect transgenesis.

BACKGROUND: Germ-line transformation of insects is now a widely used method for analyzing gene function and for the development of genetically modified strains suitable for pest control programs. The most widely used transposable element for the germ-line transformation of insects is piggyBac. The site of integration of the transgene can influence gene expression due to the effects of nearby transcription enhancers or silent heterochromatic regions. Position effects can be minimized by flanking a transgene with insulator elements. The scs/scs' and gypsy insulators from Drosophila melanogaster as well as the chicken beta-globin HS4 insulator function in both Drosophila and mammalian cells. RESULTS: To minimize position effects we have created a set of piggyBac transformation vectors that contain either the scs/scs', gypsy or chicken beta-globin HS4 insulators. The vectors contain either fluorescent protein or eye color marker genes and have been successfully used for germ-line transformation of Drosophila melanogaster. A set of the scs/scs' vectors contains the coral reef fluorescent protein marker genes AmCyan, ZsGreen and DsRed that have not been optimized for translation in human cells. These marker genes are controlled by a combined GMR-3xP3 enhancer/promoter that gives particularly strong expression in the eyes. This is also the first report of the use of the ZsGreen and AmCyan reef fluorescent proteins as transformation markers in insects. CONCLUSION: The insulated piggyBac vectors should protect transgenes against position effects and thus facilitate fine control of gene expression in a wide spectrum of insect species. These vectors may also be used for transgenesis in other invertebrate species.

Animals↗
PubMed2000

Short-term effects of cervical manipulation on edge light pupil cycle time: a pilot study.

BACKGROUND: Edge light pupil cycle time (ELPCT) is one of the eye's light reflexes. Studies have shown ELPCT to be a measurable constant, unaffected by visual acuity, refractive error, eye color, pupil size, or sex. Control of this reflex occurs through the autonomic nervous system. Various authors suggest that spinal manipulative techniques can produce distant effects mediated in part by alterations in autonomic tone after intervention. OBJECTIVE: To investigate the effects of a C1-2 high-velocity, low-amplitude manipulation on ELPCT. DESIGN: A single-group, randomized pilot study without a control group. METHODS: Thirteen men (mean age 24.2 years) without a history of eye disease or central or autonomic nervous system pathologic conditions had their ELPCT measured before and after manipulation. The manipulation comprised a high-velocity, low-amplitude rotatory thrust, localized to the C1-2 joint on the left (n = 6) or right (n = 7) eye, determined randomly. RESULTS: ELPCT measures demonstrated a significant difference for both eyes before and after manipulation (P = .002; the right eye, P = .027; the left eye, P = .046). CONCLUSION: This suggests that ELPCT, which is mediated through the autonomic nervous system, can be directly influenced by high-velocity manipulation to the upper cervical spine.

Adolescent↗
PubMed2001

Gender effects in hearing loss in Dalmatians.

Brainstem auditory-evoked-response data were collected from 3101 Dalmatian dogs from 1984 to 1998 at the Veterinary Medicine Teaching Hospital at the University of California, Davis. Also collected were data on eye color and the presence or absence of a color-patch at birth. Our objective was to evaluate the role of gender in hearing loss, including the possibility that the probability of suffering unilateral or bilateral deafness was greater if the dam was hearing impaired than if the sire was hearing impaired. Results of a multiple-trait threshold-model analysis support the commonly held observation that females were more likely to be deaf than males. In addition, females were also more likely to have two blue eyes (a condition associated with an increased prevalence of deafness). However, gender differences in hearing loss were limited to these direct observations. There was no detectable difference in the prevalence of hearing loss between offspring of deaf mothers and the offspring of deaf fathers. Finally, there was no detectable decrease in the prevalence of hearing loss over the years covered in the data set - suggesting that Dalmatian breeders are not yet selecting against hearing problems.

Animals↗
PubMed2005

Drosophila Vps16A is required for trafficking to lysosomes and biogenesis of pigment granules.

Mutations that disrupt trafficking to lysosomes and lysosome-related organelles cause multiple diseases, including Hermansky-Pudlak syndrome. The Drosophila eye is a model system for analyzing such mutations. The eye-color genes carnation and deep orange encode two subunits of the Vps-C protein complex required for endosomal trafficking and pigment-granule biogenesis. Here we demonstrate that dVps16A (CG8454) encodes another Vps-C subunit. Biochemical experiments revealed a specific interaction between the dVps16A C-terminus and the Sec1/Munc18 homolog Carnation but not its closest homolog, dVps33B. Instead, dVps33B interacted with a related protein, dVps16B (CG18112). Deep orange bound both Vps16 homologs. Like a deep orange null mutation, eye-specific RNAi-induced knockdown of dVps16A inhibited lysosomal delivery of internalized ligands and interfered with biogenesis of pigment granules. Ubiquitous knockdown of dVps16A was lethal. Together, these findings demonstrate that Drosophila Vps16A is essential for lysosomal trafficking. Furthermore, metazoans have two types of Vps-C complexes with non-redundant functions.

Animals↗
PubMed1998

Squamous and basal cell carcinoma in heart transplant recipients.

BACKGROUND: Cutaneous malignancies are frequent in organ transplant recipients. We retrospectively reviewed a large series of heart transplant recipients and report on the prevalence and risk factors for development of cutaneous squamous and basal cell carcinoma. METHODS: Between Dec. 4, 1985, and Dec. 27, 1996, 299 heart transplantations were performed at the Oregon Health Sciences University. Heart transplant recipients with more than 6 months survival or follow-up were investigated for squamous and basal cell carcinoma (n = 248). RESULTS: Forty-one patients (17%) were found to have 192 squamous or basal cell carcinomas. Squamous cell carcinoma was the predominate skin malignancy, constituting 172 (90%) of the lesions. The mean number of skin malignancies per patient was 4.7 +/- 0.81 (range 125). Patients with development of a skin malignancy were 8 years older on average, with a male-to-female ratio of 19.5:1. The predominant skin type and eye color were fair (59%) and blue (59%), respectively. Cumulative risk, based on actuarial survival analysis for development of a squamous or basal cell carcinoma at 1 year, was 3% and increased to 21% and 35% at 5 and 10 years, respectively. In addition, cumulative risk increased in patients who received treatment with OKT3. CONCLUSION: Cumulative risk of development of a skin malignancy increased with time and use of OKT3. Additional patient risk factors included older age, male sex, fair skin, and blue eyes.

Actuarial Analysis↗
PubMed1996

Cloning of the cDNA for a human homologue of the Drosophila white gene and mapping to chromosome 21q22.3.

In an effort to contribute to the transcript map of human chromosome 21 and the understanding of the pathophysiology of trisomy 21, we have used exon trapping to identify fragments of chromosome 21 genes. Two trapped exons, from pools of chromosome 21-specific cosmids, showed homology to the Drosophila white (w) gene. We subsequently cloned the corresponding cDNA for a human homologue of the Drosophila w gene (hW) from human retina and fetal brain cDNA libraries. The gene belongs to the ATP-binding cassette transporter gene family and is homologous to Drosophila w (and to w genes from other species) and to a lesser extent to Drosophila brown (bw) and scarlet (st) genes that are all involved in the transport of eye pigment precursor molecules. A DNA polymorphism with 62% heterozygosity due to variation of a poly (T) region in the 3' UTR of the hW has been identified and used for the incorporation of this gene to the genetic map of chromosome 21. The hW is located at 21q22.3 between DNA markers D21S212 and D21S49 in a P1 clone that also contains marker BCEI. The gene is expressed at various levels in many human tissues. The contributions of this gene to the Down syndrome phenotypes, to human eye color, and to the resulting phenotypes of null or missense mutations are presently unknown.

ATP-Binding Cassette Transporters↗
PubMed1989

Drosophila purine auxotrophy: new alleles of adenosine 2 exhibiting a complex visible phenotype.

New mutant alleles of the adenosine2 locus (ade2; 2-17.7) have been isolated using the eye-color phenotype exhibited by the prototype auxotrophic allele ade2 as the screening criterion. The new mutants form a single complementation group, suggesting that they all exhibit purine auxotrophy and defective formylglycineamide ribotide amidotransferase enzyme, like ade2. Tests carried out on particular new alleles confirm these suggestions. The new mutants all exhibit more extreme physical defects than the prototype. They have wing abnormalities like mutants defective in pyrmidine biosynthesis and reduced bristles like those defective in protein synthesis; thus they exhibit the combined visible phenotype of rudimentary wings, rosy eyes, and bobbed bristles. Cytogenetic analysis places the locus in the interband proximal to 26B1-2.

Adenosine↗
PubMed1982

Physical map of the white locus of Drosophila melanogaster.

The white locus of Drosophila melanogaster is a genetically well-characterized locus, mutations in which alter the degree of pattern of pigmentation of the eyes. Using a previously cloned DNA segment containing a portion of the white locus of a mutant allele, we have cloned and characterized the DNA of a 48-kilobase chromosomal region of the Canton S wild-type strain. We have mapped the positions, relative to restriction endonuclease cleavage sites, of several previously characterized chromosomal rearrangement breakpoints that bracket the while locus. These results define a segment of 14 kilobase that contains all of the white locus sequences necessary for the production of a wild-type eye color phenotype. By conventional criteria, no repetitive sequences are present within this 14-kilobase segment; however, we have identified an extremely weak DNA sequence homology between a portion of this segment and a chromosomal region in the vicinity of the zeste locus.

Animals↗
PubMed1989

Ultrastructure of the ocellar visual system in normal and mutant Drosophila melanogaster.

Between the two compound eyes on the vertex on the adult head are the three simple eyes, ocelli. Transmission and scanning electron microscopy were used to investigate the corneal lenses, ocellar photoreceptors, and axonal projections in normal and mutant Drosophila melanogaster. In wild type flies, the cornea consists of about 45 lamellae. It has corneal nipples distally and is underlaid with a monolayer of corneagenous cells. Retinula cells have open rhabdomeres of about 2 microns (diameter) x 7 microns (length). Rhabdomeres extend to the distal extent of the cell and do not have caps. Microvilli have a rodlet within. Retinula cells are joined by belt desmosomes on the lateral borders. Eye color pigment granules are housed within the retinula cells of normal flies, not in accessory cells. The granules do not migrate in response to light. No screening pigment granules exist in the white mutant. Each ocellus has about 80 retinula cells whose axons project to corresponding ganglia from which 4 giant afferent interneurons (per ganglion) project to the brain. receptor terminals are invested with capitate projections from glia. Receptors synapse onto dyads of follower cells, usually interneuron processes, at sites of T shaped presynaptic ribbons. These "T bars" are surrounded by indistinct flattened vesicles. Interneurons make feed back synapses onto receptor terminals at T bars clustered with distinct round vesicles. Three mutants with abnormal ocelli were investigated. The none mutant has unusual compound eye and ocellar corneas. The compound eye is devoid of differentiated photoreceptors but some axons from undifferentiated cells from synapses. No receptors were found in the ocelli of none. The oc mutant has no ocelli, although sometimes an ocellar cornea like that of none is seen; the compound eye is normal. The rdo mutant is also specific to ocelli with smaller ocelli having half the wild type allotment of receptor cells; the number of giant afferents is unaffected. Mutants best known for their compound eye defects were examined. The norpA mutant loses its ocellar rhabdomeres with age but has normal feed forward and feed back synapses. This normal synaptology prevails despite the electrophysiological defects in norpA ocelli reported earlier. The rdgABS12 mutant has poorly formed ocellar receptors which show some degeneration with age but synapses survive. The trp. rdgBKS222 and rgdAPC47 mutants are essentially normal with respect to structure and survival of ocellar receptors and synapses.

Animals↗
PubMed2000

Parallel monitoring of mitotic recombination, clastogenicity and teratogenic effects in eye tissue of Drosophila.

Loss of heterozygosity (LOH) of the wild-type allele by structural chromosome aberrations (SCAs), homologous mitotic recombination (HMR) or intra-chromosomal (deletion/amplification) recombination (ICR) plays a crucial role in multistage carcinogenesis. We describe here an in vivo system, enabling the detection of all three chromosome breakage-related events in the same genetic experiment, with eye tissue of Drosophila as targets. This modification of the white/white(+) system enables to measure, simultaneously, HMR and ICR on the X-chromosome, and loss of a ring-shaped X-chromosome, utilizing the eye color gene white. Optimal conditions for the detection and quantification of SCAs (ring-X loss) compared to HMR are discussed in detail. Emerging new techniques comprise the parallel detection of HMR on chromosomes X and 3, using the tumor suppressor gene warts in addition to the X-linked marker white. Another modification of the white/white(+) system measures, again in parallel, HMR and chromosome duplication (non-disjunction).

Abnormalities, Drug-Induced↗
PubMed1988

Maternally inherited transposon excision in Drosophila simulans.

A mutation in the white gene of Drosophila mauritiana resulting from insertion of the transposable element mariner exhibits genetic instability in germline and somatic cells. The instability is greatly enhanced in the presence of the trans-acting autosomal factor Mos, giving eye-color mosaics with pigmented sectors of tissue on an otherwise peach-colored background. The Mos factor, when introduced into the genome of the sibling species Drosophila simulans, exhibited a dramatic maternal effect on expression of the mosaic phenotype. When D. simulans mosaic females (heterozygous for Mos) were crossed with non-mosaic males, two distinct classes of mosaic offspring occurred, one resulting from a maternal effect in which the non-Mos offspring were nevertheless mosaic. The maternal effect was mediated by a product acting after fertilization, and was expressed to varying extents in different backcross strains.

Animals↗
PubMedDate not supplied

Potential implications for pathophysiology in a type 1 diabetic patient affected by Stargardt disease.

PURPOSE/METHOD: To present a 35-year-old woman affected by type 1 diabetes mellitus, Stargardt maculopathy and fundus flavimaculatus. To our knowledge, this association is unusual and not yet described in the ophthalmic literature. RESULTS/CONCLUSIONS: Visual acuity was reduced to < 20/200 in both eyes, color vision was absent and computerized perimetry showed an absolute central scotoma. Pattern visual evoked potentials and electroretinogram (ERG) (scotopic, photopic and flicker) were considerably reduced in amplitudes. Full-field ERG was within normal limits whereas oscillatory potentials were reduced in number and amplitude. Fluorescein angiography confirmed the diagnosis of Stargardt maculopathy and fundus flavimaculatus but no diabetic retinopathy was clinically evident. Potential interactions between the diabetic microangiopathy and the retinal degenerative disorder are hypothesized and discussed.

ATP-Binding Cassette Transporters↗
PubMed1970

The mating advantage of rare males in Drosophila.

The mating advantage of rare Drosophila males in tested using two eye color mutants. In one experiment, the flies remained for three hours in observation chambers containing 25 pairs; in another experiment they stayed for 24 hours in mass cultures of 200 individuals. The outcome of this latter experiment was followed for ten generations, with all competition other than that for mates eliminated. For initial frequencies of 80 per cent for the common and 20 per cent for the rare type, the frequencies converged to approximate equality because the rare males were favored as mates. When the formerly rare type increases in frequency, it loses its mating advantage, and a balanced equilibrium is eventually attained.

Animals↗