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Vision Research Jan 2001Microspectrophotometry was used to determine the absorbance spectra of both rod and cone visual pigments and oil droplets from the retinae of the ostrich (Struthio...
Microspectrophotometry was used to determine the absorbance spectra of both rod and cone visual pigments and oil droplets from the retinae of the ostrich (Struthio camelus) and rhea (Rhea americana). Light and fluorescence microscopy of whole fresh tissue mounts were used to determine the relative numbers and distribution of oil droplets in the retinae. Both species possessed rods, double cones and four classes of single cone identified by their oil droplets. The rods had lambda max at about 505 nm, whereas three cone pigments were recorded with lambda max at 570, 505 and 445 nm. The P570 pigment was located in both members of the double cones and in a class of single cone containing an R-type oil droplet (lambda cut at 555 nm). The P505 and P445 cone pigments were found in populations of single cones containing Y-type and C-type oil droplets (lambda cut of 500 and 420 nm, respectively). The fourth class of single cone contained a T-type droplet and in the ostrich contained a visual pigment with lambda max at about 405 nm. Double cones possessed a P-type droplet in the principal member and an A-type droplet in the accessory member. The complement of visual pigments and oil droplets, and the ratio of cone types in the ostrich and rhea, are remarkably similar to those found in many groups of neognathous birds.
Topics: Animals; Microscopy, Fluorescence; Microspectrophotometry; Oils; Photoreceptor Cells, Vertebrate; Pigment Epithelium of Eye; Rheiformes; Spectrum Analysis; Struthioniformes
PubMed: 11163611
DOI: 10.1016/s0042-6989(00)00227-3 -
Investigative Ophthalmology & Visual... Sep 2009Accumulation of free opsin by mutations in rhodopsin or insufficiencies in the visual cycle can lead to retinal degeneration. Free opsin activates phototransduction;...
PURPOSE
Accumulation of free opsin by mutations in rhodopsin or insufficiencies in the visual cycle can lead to retinal degeneration. Free opsin activates phototransduction; however, the link between constitutive activation and retinal degeneration is unclear. In this study, the photoresponses of Xenopus rods rendered constitutively active by vitamin A deprivation were examined. Unlike their mammalian counterparts, Xenopus rods do not degenerate. Contrasting phototransduction in vitamin A-deprived Xenopus rods with phototransduction in constitutively active mammalian rods may provide new understanding of the mechanisms that lead to retinal degeneration.
METHODS
The photocurrents of Xenopus tadpole rods were measured with suction electrode recordings, and guanylate cyclase activity was measured with the IBMX (3-isobutyl-1-methylxanthine) jump technique. The amount of rhodopsin in rods was determined by microspectrophotometry.
RESULTS
The vitamin A-deprived rod outer segments were 60% to 70% the length and diameter of the rods in age-matched animals. Approximately 90% of its opsin content was in the free or unbound form. Analogous to bleaching adaptation, the photoresponses were desensitized (10- to 20-fold) and faster. Unlike bleaching adaptation, the vitamin A-deprived rods maintained near normal saturating (dark) current densities by developing abnormally high rates of cGMP synthesis. Their rate of cGMP synthesis in the dark (15 seconds(-1)) was twofold greater than the maximum levels attainable by control rods ( approximately 7 seconds(-1)).
CONCLUSIONS
Preserving circulating current density and response range appears to be an important goal for rod homeostasis. However, the compensatory changes associated with vitamin A deprivation in Xenopus rods come at the high metabolic cost of a 15-fold increase in basal ATP consumption.
Topics: Animals; Calbindins; Cyclic GMP; Dark Adaptation; Electrophysiology; Fluorescent Antibody Technique, Indirect; Guanylate Cyclase; Hydrolysis; Light; Microspectrophotometry; Photic Stimulation; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Rhodopsin; S100 Calcium Binding Protein G; Vision, Ocular; Vitamin A Deficiency; Xenopus laevis
PubMed: 19407019
DOI: 10.1167/iovs.08-3186 -
Skin Pharmacology and Physiology 2016In vivo Raman spectroscopy is a powerful tool for real-time analysis and in situ evaluation of tissues such as the skin. The efficiency of this technique has been widely...
BACKGROUND
In vivo Raman spectroscopy is a powerful tool for real-time analysis and in situ evaluation of tissues such as the skin. The efficiency of this technique has been widely demonstrated as a label-free method for in vivo evaluation of the skin. The aim of this study is to gather information about inter- and intra-individual variations in the spectral descriptors of water content and structure, organization of the lipid barrier and structure of proteins in the stratum corneum (SC).
METHODS
In vivo SC measurements were performed on 17 female volunteers aged 20-30 years (phototypes I and II). For intra-individual variability, spectral collection was performed on 5 successive days per volunteer. Shapiro-Wilk and Cochran tests were applied to check the normality and the homoscedasticity of variances. ANOVA was then applied to evaluate intra- and intergroup variability.
RESULTS
ANOVA was performed on the spectral descriptors of water content and structure, organization of the lipid barrier and secondary structure of proteins in the SC. No significant intra- and interday variability was observed for all volunteers. Despite the low value of the total relative standard deviation, a highly significant variation was observed between volunteers.
CONCLUSION
Interindividual variability for Raman measurements is significant for a set of volunteers with normal nondiseased SC and close phototypes. This variability should be taken into consideration as a threshold for significant variance when working in vivo.
Topics: Adult; Biomarkers; Epidermal Cells; Epidermis; Female; Humans; Microspectrophotometry; Spectrum Analysis, Raman; Young Adult
PubMed: 27160092
DOI: 10.1159/000445079 -
Arquivos Brasileiros de Oftalmologia 2006To describe the electroretinogram of the South-American opossum (Didelphis aurita) obtained by chromatic stimulus of specific wavelengths. The electroretinogram records...
PURPOSE
To describe the electroretinogram of the South-American opossum (Didelphis aurita) obtained by chromatic stimulus of specific wavelengths. The electroretinogram records voltage variations of retinal cells triggered by light stimulation. The electroretinogram represents the combination of electric activity of many different cells and varies according to retinal physiology and examination methods.
METHODS
We recorded the electroretinogram of six animals in dark adaptation using chromatic Kodak Wratten filters, and recorded the spectral sensitivity to specific wavelengths in the spectrum of blue, green, yellow, orange and red light bands.
RESULTS
The most consistent electrorretinographic results were obtained when the animals were stimulated by selective spectral bands instead of white light. These results are consistent with the absorbance curve of the opsins described in marsupial photoreceptors. Previous studies using microspectrophotometry of opsins and retinal immunohistochemistry suggested marsupial trichromacy. This morphologic knowledge has not before been physiologically demonstrated by electroretinographic methods.
CONCLUSION
The South-American opossum has proven to be an interesting experimental animal for comparative visual physiology studies among other mammals, especially studies on phylogenetic of chromatic vision. The opossum represents a retinal model that superimposes both the photopic and scotopic systems; and the Didelphis genus shows few changes when compared to the fossils of the Pleocene period. Therefore the marsupial's visual system retrieves characteristics from ancient mammal evolution to the retinal patterns found in modern mammals.
Topics: Animals; Biological Evolution; Color; Color Perception; Dark Adaptation; Electroretinography; Female; Light; Male; Mammals; Marsupialia; Models, Animal; Photic Stimulation; Retinal Cone Photoreceptor Cells; Sensory Thresholds; Vision, Ocular
PubMed: 17273680
DOI: 10.1590/s0004-27492006000600014 -
Annals of Botany Jun 2006BACKGROUND AND AIMS The effect of heating and cooling on cambial activity and cell differentiation in part of the stem of Norway spruce (Picea abies) was investigated.
UNLABELLED
BACKGROUND AND AIMS The effect of heating and cooling on cambial activity and cell differentiation in part of the stem of Norway spruce (Picea abies) was investigated.
METHODS
A heating experiment (23-25 degrees C) was carried out in spring, before normal reactivation of the cambium, and cooling (9-11 degrees C) at the height of cambial activity in summer. The cambium, xylem and phloem were investigated by means of light- and transmission electron microscopy and UV-microspectrophotometry in tissues sampled from living trees.
KEY RESULTS
Localized heating for 10 d initiated cambial divisions on the phloem side and after 20 d also on the xylem side. In a control tree, regular cambial activity started after 30 d. In the heat-treated sample, up to 15 earlywood cells undergoing differentiation were found to be present. The response of the cambium to stem cooling was less pronounced, and no anatomical differences were detected between the control and cool-treated samples after 10 or 20 d. After 30 d, latewood started to form in the sample exposed to cooling. In addition, almost no radially expanding tracheids were observed and the cambium consisted of only five layers of cells. Low temperatures reduced cambial activity, as indicated by the decreased proportion of latewood. On the phloem side, no alterations were observed among cool-treated and non-treated samples.
CONCLUSIONS
Heating and cooling can influence cambial activity and cell differentiation in Norway spruce. However, at the ultrastructural and topochemical levels, no changes were observed in the pattern of secondary cell-wall formation and lignification or in lignin structure, respectively.
Topics: Cell Differentiation; Cell Wall; Climate; Cold Temperature; Hot Temperature; Microscopy, Electron, Transmission; Picea; Plant Stems; Spectrophotometry, Ultraviolet
PubMed: 16613904
DOI: 10.1093/aob/mcl050 -
Vision Research 1991This study demonstrates correlations between u.v. sensitivity and microspectrophotometric absorption spectra determined sequentially for the same group of individuals....
This study demonstrates correlations between u.v. sensitivity and microspectrophotometric absorption spectra determined sequentially for the same group of individuals. We used the heart-rate conditioning technique to measure spectral sensitivity of carp, a species known to have u.v.-sensitive photoreceptors. Mean spectral sensitivity (n = 3) determined with a spectrally-broad background (450 nm long pass filter) revealed a small but consistent u.v. peak (lambda max of 380 nm) in addition to the other long wavelength peaks. An intense blue-green background (490 nm) produced a more prominent u.v. peak (lambda max of 400 nm) when a 450 nm longpass filter was added to the background. Microspectrophotometric measurements of u.v.-sensitive photoreceptors from one individual, which belonged to the group used in the spectral sensitivity experiments, revealed an average lambda max of 377.5 nm (SD +/- 4.5 nm, n = 5 cells). Bleaching and dichroic measurements of these receptors ensured that we were examining typical vertebrate visual pigments and not stable photoproducts. The mean spectral sensitivity points were compared with the u.v. and blue-sensitive visual pigment absorption spectra. A linear subtractive model and ocular media absorption were used in this comparison for the various photic conditions used in the heart-rate conditioning experiments. The model successfully described the sensitivity of the test fish in two cases but in a third case there was some discrepancy. The model generated curve was broader than the spectral sensitivity of the u.v.-sensitive cone mechanism on the shortwave side even though the ocular media corrections had been accounted for.
Topics: Animals; Carps; Light; Microspectrophotometry; Photoreceptor Cells; Retinal Pigments; Sensory Thresholds; Ultraviolet Rays; Visual Perception
PubMed: 1843761
DOI: 10.1016/0042-6989(91)90107-g -
The Journal of Comparative Neurology Oct 2020The retinas of nonmammalian vertebrates have cone photoreceptor mosaics that are often organized as highly patterned lattice-like distributions. In fishes, the two main...
The retinas of nonmammalian vertebrates have cone photoreceptor mosaics that are often organized as highly patterned lattice-like distributions. In fishes, the two main lattice-like patterns are composed of double cones and single cones that are either assembled as interdigitized squares or as alternating rows. The functional significance of such orderly patterning is unknown. Here, the cone mosaics in two species of Soleidae flatfishes, the common sole and the Senegalese sole, were characterized and compared to those from other fishes to explore variability in cone patterning and how it may relate to visual function. The cone mosaics of the common sole and the Senegalese sole consisted of single, double, and triple cones in formations that differed from the traditional square mosaic pattern reported for other flatfishes in that no evidence of higher order periodicity was present. Furthermore, mean regularity indices for single and double cones were conspicuously lower than those of other fishes with "typical" square and row mosaics, but comparable to those of goldfish, a species with lattice-like periodicity in its cone mosaic. Opsin transcripts detected by quantitative polymerase chain reaction (sws1, sws2, rh2.3, rh2.4, lws, and rh1) were uniformly expressed across the retina of the common sole but, in the Senegalese sole, sws2, rh2.4, and rh1 were more prevalent in the dorsal retina. Microspectrophotometry revealed five visual pigments in the retina of the common sole [S(472), M(523), M(536), L(559), and rod(511)] corresponding to the repertoire of transcripts quantified except for sws1. Overall, these results indicate a loss of cone mosaic patterning in species that are primarily nocturnal or dwell in low light environments as is the case for the common sole and the Senegalese sole. The corollary is that lattice-like patterning of the cone mosaic may improve visual acuity. Ecological and physiological correlates derived from observations across multiple fish taxa that live in low light environments and do not possess lattice-like cone mosaics are congruent with this claim.
Topics: Animals; Body Patterning; Flatfishes; Retinal Cone Photoreceptor Cells; Species Specificity
PubMed: 32103501
DOI: 10.1002/cne.24893 -
Dental Materials : Official Publication... Oct 2009The molecular structural nature of the dentin substrate in non-carious cervical lesions (NCCLs) is poorly understood. This investigation characterized the chemical... (Comparative Study)
Comparative Study
OBJECTIVE
The molecular structural nature of the dentin substrate in non-carious cervical lesions (NCCLs) is poorly understood. This investigation characterized the chemical structure including inhomogeneities, composition, mineral crystallinity, collagen organization of normal dentin and affected dentin substrates within NCCLs using Raman microspectroscopic mapping/imaging.
MATERIALS AND METHODS
Three extracted human pre-molars affected with NCCLs were selected and cavities matching the natural lesion with respect to size and location were prepared on the lingual/palatal surface of each tooth to serve as controls. The specimens were sectioned to expose the gingival and occlusal margins of the NCCLs and the control cavities. Micro-Raman spectra and imaging were acquired at 1.5 microm spatial resolution at positions perpendicular to the lesion surfaces.
RESULTS
The Raman spectra and imaging comparisons showed the distinct compositional and structural alterations in mineral and matrix components of NCCL affected dentin. A heterogeneous hyper-mineralized layer, with characteristic features such as high phosphate/low carbonate content, high degree of crystallinity and partially denatured collagen were revealed in affected dentin substrate of NCCLs.
SIGNIFICANCE
Generating Raman images based on different strategies from the same data set provides a powerful means to study the structural alterations within heterogeneous dental tissues. Direct overlay of the images indicated that the changes in chemical structure and composition are synchronized. Further studies are required to understand the role that these alterations play in response to acid etching and bonding to these clinically relevant substrates.
Topics: Carbonates; Collagen; Crystallography; Dentin; Humans; Microspectrophotometry; Minerals; Molecular Structure; Phosphates; Spectrum Analysis, Raman; Tooth Abrasion; Tooth Cervix; Tooth Erosion
PubMed: 19464050
DOI: 10.1016/j.dental.2009.04.006 -
Brain, Behavior and Evolution 2015Deep-sea fishes possess several adaptations to facilitate vision where light detection is pushed to its limit. Lanternfishes (Myctophidae), one of the world's most...
Deep-sea fishes possess several adaptations to facilitate vision where light detection is pushed to its limit. Lanternfishes (Myctophidae), one of the world's most abundant groups of mesopelagic fishes, possess a novel and unique visual specialisation, a sexually dimorphic photostable yellow pigmentation, constituting the first record of a visual sexual dimorphism in any non-primate vertebrate. The topographic distribution of the yellow pigmentation across the retina is species specific, varying in location, shape and size. Spectrophotometric analyses reveal that this new retinal specialisation differs between species in terms of composition and acts as a filter, absorbing maximally between 356 and 443 nm. Microspectrophotometry and molecular analyses indicate that the species containing this pigmentation also possess at least 2 spectrally distinct rod visual pigments as a result of a duplication of the Rh1 opsin gene. After modelling the effect of the yellow pigmentation on photoreceptor spectral sensitivity, we suggest that this unique specialisation acts as a filter to enhance contrast, thereby improving the detection of bioluminescent emissions and possibly fluorescence in the extreme environment of the deep sea. The fact that this yellow pigmentation is species specific, sexually dimorphic and isolated within specific parts of the retina indicates an evolutionary pressure to visualise prey/predators/mates in a particular part of each species' visual field.
Topics: Animals; Biological Evolution; Female; Fishes; Male; Models, Biological; Photoreceptor Cells, Vertebrate; Retina; Retinal Pigments; Sex Characteristics; Species Specificity; Vision, Ocular; Visual Fields
PubMed: 25766394
DOI: 10.1159/000371652 -
Journal of Pharmaceutical and... Sep 2011During the past years, pharmaceutical counterfeiting was mainly a problem of developing countries with weak enforcement and inspection programs. However, Europe and...
During the past years, pharmaceutical counterfeiting was mainly a problem of developing countries with weak enforcement and inspection programs. However, Europe and North America are more and more confronted with the counterfeiting problem. During this study, 26 counterfeits and imitations of Viagra® tablets and 8 genuine tablets of Viagra® were analysed by Raman microspectroscopy imaging. After unfolding the data, three maps are combined per sample and a first PCA is realised on these data. Then, the first principal components of each sample are assembled. The exploratory and classification analysis are performed on that matrix. PCA was applied as exploratory analysis tool on different spectral ranges to detect counterfeit medicines based on the full spectra (200-1800 cm⁻¹), the presence of lactose (830-880 cm⁻¹) and the spatial distribution of sildenafil (1200-1290 cm⁻¹) inside the tablet. After the exploratory analysis, three different classification algorithms were applied on the full spectra dataset: linear discriminant analysis, k-nearest neighbour and soft independent modelling of class analogy. PCA analysis of the 830-880 cm⁻¹ spectral region discriminated genuine samples while the multivariate analysis of the spectral region between 1200 cm⁻¹ and 1290 cm⁻¹ returns no satisfactory results. A good discrimination of genuine samples was obtained with multivariate analysis of the full spectra region (200-1800 cm⁻¹). Application of the k-NN and SIMCA algorithm returned 100% correct classification during both internal and external validation.
Topics: Algorithms; Chemistry, Pharmaceutical; Counterfeit Drugs; Discriminant Analysis; Excipients; Feasibility Studies; Fraud; Lactose; Microspectrophotometry; Multivariate Analysis; Phosphodiesterase 5 Inhibitors; Piperazines; Principal Component Analysis; Purines; Reference Standards; Reproducibility of Results; Sildenafil Citrate; Spectrum Analysis, Raman; Sulfones; Tablets; Technology, Pharmaceutical
PubMed: 21715121
DOI: 10.1016/j.jpba.2011.05.042