Search results for "Eye"
showing 10 items of 2511 documents
Pigment patterns in mutants affecting the biosynthesis of pteridines and xanthommatin in Drosophila melanogaster.
1986
Eye-color mutants of Drosophila melanogaster have been analyzed for their pigment content and related metabolites. Xanthommatin and dihydroxanthommatin (pigments causing brown eye color) were measured after selective extraction in acidified butanol. Pteridines (pigments causing red eye color) were quantitated after separation of 28 spots by thin-layer chromatography, most of which are pteridines and a few of which are fluorescent metabolites from the xanthommatin pathway. Pigment patterns have been studied in 45 loci. The pteridine pathway ramifies into two double branches giving rise to isoxanthopterin, “drosopterins,” and biopterin as final products. The regulatory relationship among the …
Cholesterol-Streptolysin O Interaction: An EM Study of Wild-Type and Mutant Streptolysin O
1998
We present transmission electron microscopical data from negatively stained specimens of cholesterol following interaction with the thiol-activated bacterial toxin streptolysin O (SLO) (wild-type and a number of cysteine substitution mutants), with and without chemical modification of the cysteine residues. Two experimental systems were used, one with an aqueous suspension of cholesterol microcrystals and the other with immobilized thin planar cholesterol crystals attached to a carbon film. In both systems the wild-type SLO and two cytolytically active mutants, Cys 530 --Ala (C530A) and Ser 101 --Cys (S101C), readily generated the characteristic SLO arc- and ring-like oligomers on the surfa…
Evaluation of presumptive biomarkers of oxidative stress, immune response and apoptosis in primary open-angle glaucoma.
2013
There is growing interest on the correlation among oxidative stress, inflammation, apoptosis and primary open-angle glaucoma initiation and progression. Reactive oxygen species are formed in the eyes following a wide variety of stressors, and are largely implicated in glaucoma pathogenesis. Immune-inflammatory response mediators have recently become a target of ophthalmologic concern, including glaucoma. Much attention has been derived to the role of specific pro and anti-apoptotic molecules in glaucoma. This article reviews the early evidence suggesting that reactive oxygen species, immune inflammatory response mediators, and apoptogenic molecules are engaged in glaucoma disease. Moreover,…
Interaction of glutamic-acid-rich proteins with the cGMP signalling pathway in rod photoreceptors.
1999
The assembly of signalling molecules into macromolecular complexes (transducisomes) provides specificity, sensitivity and speed in intracellular signalling pathways. Rod photoreceptors in the eye contain an unusual set of glutamic-acid-rich proteins (GARPs) of unknown function. GARPs exist as two soluble forms, GARP1 and GARP2, and as a large cytoplasmic domain (GARP' part) of the beta-subunit of the cyclic GMP-gated channel. Here we identify GARPs as multivalent proteins that interact with the key players of cGMP signalling, phosphodiesterase and guanylate cyclase, and with a retina-specific ATP-binding cassette transporter (ABCR), through four, short, repetitive sequences. In electron mic…
Visual and ocular effects from the use of flat-panel displays
2016
AIM: To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. METHODS: One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a V…
Stable polymorphism for mutant eye colour geues in populations of Drosophila melanogaster in two different media
1988
In previous work analyzing variability of eye colour alleles existing in natural populations of D. melanogaster, it was observed that the number of females heterozygous for some eye colour alleles was greater in a wine cellar population than in populations outside this cellar. In order to determine which mechanisms caused these eye colour alleles to be favored in the heterozygotes, the changes in the frequency of four eye colour alleles frequently seen in the cellar population (se77o, sf77m, cd77o and multichromosomal 77o) was studied in artificial populations. Two different culture media, one supplemented with 10% ethanol and the other without ethanol were used. It was found that each of t…
Tear production and intraocular pressure values in clinically normal eyes of whooper swans (Cygnus cygnus)
2018
The objective of this study was to determine the normal range of tear production and values of intraocular pressure (IOP) in clinically normal eyes of whooper swans (Cygnus cygnus). A total of 86 birds: 81 cygnets (6-10 weeks old) and 5 moulting – adult swans (3-6 years old) were examined in this study. Both eyes of all birds underwent a complete ophthalmic examination, including evaluation of tear production with the phenol red thread test (PRTT) and the assessment of the IOP by rebound tonometry, employing the TonoVet® device. The mean ± standard deviation of PRTT values were as follows: all cygnets (81) 22.59±3.48 mm/15s, male cygnets (45) 22.64±3.54 mm/15s, female cygnets (36) 22.53±3.4…
Effect of fixation target on the contrast sensitivity in the foveal and parafoveal area
2017
Purpose To determine the influence on the contrast sensitivity when the stimulus contains a fixation target in two retinal locations, foveal and parafoveal. Methods Four young adults with 0.0 logMar acuity participated in this study. The stimulus was based on vertical sinusoidal gratings masked by a circular (for foveal area) or a ring (for parafoveal area). To increase the luminance resolution of the display a bit-stealing technique was used. Four different sets of stimuli were generated, two for exploring the foveal sensitivity and two for the parafoveal area. The difference between the sets designed for the same area was the presence, or absence, of a fixation target (a white cross) in t…
Optomotor-blind negatively regulates Drosophila eye development by blocking Jak/STAT signaling
2015
Organ formation requires a delicate balance of positive and negative regulators. In Drosophila eye development, wingless (wg) is expressed at the lateral margins of the eye disc and serves to block retinal development. The T-box gene optomotor-blind (omb) is expressed in a similar pattern and is regulated by Wg. Omb mediates part of Wg activity in blocking eye development. Omb exerts its function primarily by blocking cell proliferation. These effects occur predominantly in the ventral margin. Our results suggest that the primary effect of Omb is the blocking of Jak/STAT signaling by repressing transcription of upd which encodes the Jak receptor ligand Unpaired.
Diplostomum spathaceum metacercarial infection and colour change in salmonid fish
2004
Colour changes in two salmonid fish, the salmon (Salmo salar) and sea trout (S. trutta), were examined in relation to infection with the trematode Diplostomum spathaceum. This parasite had no effect on the rate of colour change in these fish, although species specific differences in colour adjustment times were observed. Increasing asymmetry in parasite numbers between the right and left eye, which could lead to the retention of vision in one eye, nevertheless tended to reduce the colour change time in salmon with moderate infection (P=0.08). This first experimental attempt to examine colour changes in fish in relation to eye fluke infections provides grounds for future investigations. The …