-
Vision Research Sep 2012The morphology, fine structure and spectral sensitivity of retinal photoreceptors of two anchovy species were investigated using light and electron microscopy and...
The morphology, fine structure and spectral sensitivity of retinal photoreceptors of two anchovy species were investigated using light and electron microscopy and microspectrophotometry. Distinct regional specialisation of cones was observed. Long and short (bilobed) cones were observed in the horizontal retinal belt, including the nasal and temporal retinal zones. Only triple cones with two long lateral components, one small central component were observed in the dorsal and ventro-nasal retinal regions. The long cones presented various lamellar organisation patterns: (1) in parallel along the cell axis in the central retina, (2) oriented transversely at the base of the outer segment, and (3) tilted longitudinally while extending to the tip of the cone in the retinal periphery. In the short cones, the lamellae were always oriented along the cell axis, and their planes were perpendicular to the lamellae in the long cones, providing a structural basis for the detection of polarisation of incident light. The lamellae in all the outer segments of the triple cones are arranged perpendicular to the long cell axis. In both species, the long and short cones from the ventro-temporal retina were slender and more densely packed, and the outer segments of the long cones lay far more sclerad compared with the outer segments of the bifid cones. Microspectrophotometry revealed that in both species the lateral components of the triple cones displayed a maximum absorbance wavelength (λ(max)) of approximately 502nm, while the short central components were more shortwave sensitive (λ(max)=475nm). The λ(max) of all long and short cones in the ventro-temporal zone was 492nm, compared to 502nm in other retinal regions. Anchovies are unique among vertebrates in that they contain clear structural basis for both colour and polarisation vision in the same retina.
Topics: Animals; Fishes; Light; Microscopy; Microspectrophotometry; Retinal Cone Photoreceptor Cells; Vision, Ocular; Visual Perception
PubMed: 22819727
DOI: 10.1016/j.visres.2012.07.005 -
BMC Evolutionary Biology Nov 2017Longwing butterflies, Heliconius sp., also called heliconians, are striking examples of diversity and mimicry in butterflies. Heliconians feature strongly colored...
BACKGROUND
Longwing butterflies, Heliconius sp., also called heliconians, are striking examples of diversity and mimicry in butterflies. Heliconians feature strongly colored patterns on their wings, arising from wing scales colored by pigments and/or nanostructures, which serve as an aposematic signal.
RESULTS
Here, we investigate the coloration mechanisms among several species of Heliconius by applying scanning electron microscopy, (micro)spectrophotometry, and imaging scatterometry. We identify seven kinds of colored scales within Heliconius whose coloration is derived from pigments, nanostructures or both. In yellow-, orange- and red-colored wing patches, both cover and ground scales contain wavelength-selective absorbing pigments, 3-OH-kynurenine, xanthommatin and/or dihydroxanthommatin. In blue wing patches, the cover scales are blue either due to interference of light in the thin-film lower lamina (e.g., H. doris) or in the multilayered lamellae in the scale ridges (so-called ridge reflectors, e.g., H. sara and H. erato); the underlying ground scales are black. In the white wing patches, both cover and ground scales are blue due to their thin-film lower lamina, but because they are stacked upon each other and at the wing substrate, a faint bluish to white color results. Lastly, green wing patches (H. doris) have cover scales with blue-reflecting thin films and short-wavelength absorbing 3-OH-kynurenine, together causing a green color.
CONCLUSIONS
The pigmentary and structural traits are discussed in relation to their phylogenetic distribution and the evolution of vision in this highly interesting clade of butterflies.
Topics: Animals; Butterflies; Color; Phylogeny; Pigmentation; Spectrum Analysis; Vision, Ocular; Wings, Animal
PubMed: 29162029
DOI: 10.1186/s12862-017-1073-1 -
Frontiers in Zoology 2016Wrasses represent the second largest family of marine fishes and display a high diversity of complex colours linked to ecological functions. Recently, red...
BACKGROUND
Wrasses represent the second largest family of marine fishes and display a high diversity of complex colours linked to ecological functions. Recently, red autofluorescent body colouration has been reported in some of these fishes. However, little is known about the distribution of such fluorescent body patterns in wrasses or the animals' ability to perceive such colours.
RESULTS
Against this background, we (1) investigated long-wavelength emission autofluorescence in thirteen species of pseudocheilinid wrasses and (2) characterised the spectral absorbance of visual pigments in one of the examined species, the fairy wrasse Cirrhilabrus solorensis. Spectrophotometric analysis revealed that fluorescent body colouration is widespread and diverse within this clade, with considerable variation in both fluorescent pattern and maximum emission wavelength between species. Characterisation of visual pigments in retinal photoreceptors showed a single class of rod and three spectrally distinct cone photoreceptors, suggesting possible trichromacy.
CONCLUSION
Combining the emission characteristics of fluorescence body colouration and the spectral sensitivity data of retinal cells suggests that the visual system of C. solorensis is sensitive to pseudocheilinid fluorescence.
PubMed: 26981144
DOI: 10.1186/s12983-016-0145-1 -
The Journal of Biological Chemistry Jun 2002The binding of substrates and inhibitors to wild-type Proteus vulgaris tryptophan indole-lyase and to wild type and Y71F Citrobacter freundii tyrosine phenol-lyase was...
The binding of substrates and inhibitors to wild-type Proteus vulgaris tryptophan indole-lyase and to wild type and Y71F Citrobacter freundii tyrosine phenol-lyase was investigated in the crystalline state by polarized absorption microspectrophotometry. Oxindolyl-lalanine binds to tryptophan indole-lyase crystals to accumulate predominantly a stable quinonoid intermediate absorbing at 502 nm with a dissociation constant of 35 microm, approximately 10-fold higher than that in solution. l-Trp or l-Ser react with tryptophan indole-lyase crystals to give, as in solution, a mixture of external aldimine and quinonoid intermediates and gem-diamine and external aldimine intermediates, respectively. Different from previous solution studies (Phillips, R. S., Sundararju, B., & Faleev, N. G. (2000) J. Am. Chem. Soc. 122, 1008-1114), the reaction of benzimidazole and l-Trp or l-Ser with tryptophan indole-lyase crystals does not result in the formation of an alpha-aminoacrylate intermediate, suggesting that the crystal lattice might prevent a ligand-induced conformational change associated with this catalytic step. Wild-type tyrosine phenol-lyase crystals bind l-Met and l-Phe to form mixtures of external aldimine and quinonoid intermediates as in solution. A stable quinonoid intermediate with lambda(max) at 502 nm is accumulated in the reaction of crystals of Y71F tyrosine phenol-lyase, an inactive mutant, with 3-F-l-Tyr with a dissociation constant of 1 mm, approximately 10-fold higher than that in solution. The stability exhibited by the quinonoid intermediates formed both by wild-type tryptophan indole-lyase and by wild type and Y71F tyrosine phenol-lyase crystals demonstrates that they are suitable for structural determination by x-ray crystallography, thus allowing the elucidation of a key species of pyridoxal 5'-phosphate-dependent enzyme catalysis.
Topics: Catalysis; Citrobacter freundii; Crystallization; Kinetics; Models, Chemical; Protein Binding; Proteus vulgaris; Serine; Spectrophotometry; Tryptophanase; Tyrosine; Tyrosine Phenol-Lyase; Ultraviolet Rays
PubMed: 11934889
DOI: 10.1074/jbc.M200216200 -
PloS One 2011Valproic acid (VPA) is a potent anticonvulsant that inhibits histone deacetylases. Because of this inhibitory action, we investigated whether VPA would affect chromatin...
BACKGROUND
Valproic acid (VPA) is a potent anticonvulsant that inhibits histone deacetylases. Because of this inhibitory action, we investigated whether VPA would affect chromatin supraorganization, mitotic indices and the frequency of chromosome abnormalities and cell death in HeLa cells.
METHODOLOGY/PRINCIPAL FINDINGS
Image analysis was performed by scanning microspectrophotometry for cells cultivated for 24 h, treated with 0.05, 0.5 or 1.0 mM VPA for 1-24 h, and subjected to the Feulgen reaction. TSA-treated cells were used as a predictable positive control. DNA fragmentation was investigated with the TUNEL assay. Chromatin decondensation was demonstrated under TSA and all VPA treatments, but no changes in chromosome abnormalities, mitotic indices or morphologically identified cell death were found with the VPA treatment conditions mentioned above, although decreased mitotic indices were detected under higher VPA concentration and longer exposure time. The frequency of DNA fragmentation identified with the TUNEL assay in HeLa cells increased after a 24-h VPA treatment, although this fragmentation occurred much earlier after treatment with TSA.
CONCLUSIONS/SIGNIFICANCE
The inhibition of histone deacetylases by VPA induces chromatin remodeling in HeLa cells, which suggests an association to altered gene expression. Under VPA doses close to the therapeutic antiepileptic plasma range no changes in cell proliferation or chromosome abnormalities are elicited. The DNA fragmentation results indicate that a longer exposure to VPA or a higher VPA concentration is required for the induction of cell death.
Topics: Anticonvulsants; Cell Death; Cell Proliferation; Chromatin Assembly and Disassembly; Chromosome Aberrations; DNA Fragmentation; Epigenesis, Genetic; HeLa Cells; Humans; Micronucleus Tests; Mitosis; Molecular Imaging; Valproic Acid
PubMed: 22206001
DOI: 10.1371/journal.pone.0029144 -
Fertility and Sterility Nov 2012To determine whether Raman microspectroscopy can identify different levels of oxidative sperm nDNA damage and to corroborate the findings using an established method and... (Comparative Study)
Comparative Study
OBJECTIVE
To determine whether Raman microspectroscopy can identify different levels of oxidative sperm nDNA damage and to corroborate the findings using an established method and an alternative but complementary spectroscopic technique.
DESIGN
Three-way comparison of Raman profiles, Fourier transform infrared spectroscopy (FTIR) spectra, and flow-cytometric assessments of sperm nDNA damage.
SETTING
University-based research laboratory.
PATIENT(S)
Thirty-eight men attending the infertility clinic at the Centre of Reproductive Medicine and Andrology.
INTERVENTION(S)
Induction of oxidative damage by Fenton's reaction on semen samples.
MAIN OUTCOME MEASURE(S)
Raman profiles, FTIR spectra, and flow-cytometric analysis of DNA fragmentation.
RESULT(S)
Raman and FTIR spectra contained distinctive differences between untreated and fragmented nDNA sperm that were indicative of oxidative attack. The changes in Raman profiles were similar to those previously seen and corresponded to the DNA backbone. The peak attributions were corroborated by the FTIR spectra. Principal component analysis of the entire Raman spectra distinguished samples with varying degrees of damage. After determination of a cutoff value (0.63), estimation of the percentage of sperm with nDNA damage using the intensity ratio of Raman peaks (1,050/1,095 cm(-1)) correlated linearly to the flow-cytometric assessment.
CONCLUSION(S)
Raman microspectroscopy still requires further validation but may potentially provide a means of assessing the nDNA status of a living sperm.
Topics: Biomarkers; DNA; DNA Damage; Flow Cytometry; Humans; Hydrogen Peroxide; Infertility, Male; Iron; Linear Models; Male; Microspectrophotometry; Oxidation-Reduction; Oxidative Stress; Predictive Value of Tests; Principal Component Analysis; Reproducibility of Results; Semen Analysis; Spectroscopy, Fourier Transform Infrared; Spectrum Analysis, Raman; Spermatozoa
PubMed: 22835447
DOI: 10.1016/j.fertnstert.2012.07.1059 -
PeerJ 2018The palm borer moth (Castniidae; giant butterfly-moths) has brown dorsal forewings and strikingly orange-coloured dorsal hindwings with white spots surrounded by black...
The palm borer moth (Castniidae; giant butterfly-moths) has brown dorsal forewings and strikingly orange-coloured dorsal hindwings with white spots surrounded by black margins. Here, we have studied the structure and pigments of the wing scales in the various coloured wing areas, applying light and electron microscopy and (micro)spectrophotometry, and we analysed the spatial reflection properties with imaging scatterometry. The scales in the white spots are unpigmented, those in the black and brown wing areas contain various amounts of melanin, and the orange wing scales contain a blue-absorbing ommochrome pigment. In all scale types, the upper lamina acts as a diffuser and the lower lamina as a thin film interference reflector, with thickness of about 200 nm. Scale stacking plays an important role in creating the strong visual signals: the colour of the white eyespots is created by stacks of unpigmented blue scales, while the orange wing colour is strongly intensified by stacking the orange scales.
PubMed: 29666756
DOI: 10.7717/peerj.4590 -
Dental Materials Journal 2012The aim of this study was to optimize the concentration of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin® TPO) in unfilled and filled composite resins in... (Comparative Study)
Comparative Study
The aim of this study was to optimize the concentration of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin® TPO) in unfilled and filled composite resins in relation to the degree of conversion (DC). Increasing concentrations of Lucirin® TPO between 0.05-4.97 wt% were added to equimolar mixtures of Bis-GMA/TEGDMA. Filled resins contained 75 wt% fillers. Standardized samples were cured using a polywave LED light-curing unit (bluephase® G2, Ivoclar Vivadent). Increased initiator concentrations increased logarithmically the DC of unfilled and filled resins. The DC of unfilled resins was in the range of 73-91% at the top and 63-81% at the bottom surfaces and that of filled resins was in the range of 53-81% at the top and 47-70% at the bottom surfaces. The DC in unfilled and filled resins reached a plateau at 1.08 wt% and 1.50 wt% Lucirin® TPO, respectively. Fillers significantly reduced conversion but had no effect on the logarithmic relationship between initiator concentration and the DC.
Topics: Bisphenol A-Glycidyl Methacrylate; Composite Resins; Curing Lights, Dental; Dental Materials; Humans; Microspectrophotometry; Particle Size; Phosphines; Photoinitiators, Dental; Polyethylene Glycols; Polymerization; Polymethacrylic Acids; Spectrum Analysis, Raman; Surface Properties
PubMed: 23037832
DOI: 10.4012/dmj.2012-064 -
Proceedings. Biological Sciences Oct 2011Progress in developing animal communication theory is frequently constrained by a poor understanding of sensory systems. For example, while lizards have been the focus...
Progress in developing animal communication theory is frequently constrained by a poor understanding of sensory systems. For example, while lizards have been the focus of numerous studies in visual signalling, we only have data on the spectral sensitivities of a few species clustered in two major clades (Iguania and Gekkota). Using electroretinography and microspectrophotometry, we studied the visual system of the cordylid lizard Platysaurus broadleyi because it represents an unstudied clade (Scinciformata) with respect to visual systems and because UV signals feature prominently in its social behaviour. The retina possessed four classes of single and one class of double cones. Sensitivity in the ultraviolet region (UV) was approximately three times higher than previously reported for other lizards. We found more colourless oil droplets (associated with UV-sensitive (UVS) and short wavelength-sensitive (SWS) photoreceptors), suggesting that the increased sensitivity was owing to the presence of more UVS photoreceptors. Using the Vorobyev-Osorio colour discrimination model, we demonstrated that an increase in the number of UVS photoreceptors significantly enhances a lizard's ability to discriminate conspecific male throat colours. Visual systems in diurnal lizards appear to be broadly conserved, but data from additional clades are needed to confirm this.
Topics: Animals; Biological Evolution; Electroretinography; Lizards; Male; Microspectrophotometry; Pigments, Biological; Retina; Ultraviolet Rays; Vision, Ocular
PubMed: 21389031
DOI: 10.1098/rspb.2011.0118 -
The Journal of Cell Biology Sep 1988A more complete understanding of calcium's role in cell division requires knowledge of the timing, magnitude, and duration of changes in cytoplasmic-free calcium,...
A more complete understanding of calcium's role in cell division requires knowledge of the timing, magnitude, and duration of changes in cytoplasmic-free calcium, [Ca2+]i, associated with specific mitotic events. To define the temporal relationship of changes in [Ca2+]i to cellular and chromosomal movements, we have measured [Ca2+]i every 6-7 s in single-dividing Pt K2 cells using fura-2 and microspectrophotometry, coupling each calcium measurement with a bright-field observation. In the 12 min before discernable chromosome some separation, 90% of metaphase cells show at least one transient of increased [Ca2+]i, 72% show their last transient within 5 min, and a peak of activity is seen at 3 min before chromosome separation. The mean [Ca2+]i of the metaphase transients is 148 +/- 31 nM (61 transients in 35 cells) with an average duration of 21 +/- 14 s. The timing of these increases makes it unlikely that these transient increases in [Ca2+]i are acting directly to trigger the start of anaphase. However, it is possible that a transient rise in calcium during late metaphase is part of a more complex progression to anaphase. In addition to these transient changes, a gradual increase in [Ca2+]i was observed starting in late anaphase. Within the 2 min surrounding cytokinesis onset, 82% of cells show a transient increase in [Ca2+]i to 171 +/- 48 nM (53 transients in 32 cells). The close temporal correlation of these changes with cleavage is consistent with a more direct role for calcium in this event, possibly by activating the contractile system. To assess the specificity of these changes to the mitotic cycle, we examined calcium changes in interphase cells. Two-thirds of interphase cells show no transient increases in calcium with a mean [Ca2+]i of 100 +/- 18 nM (n = 12). However, one-third demonstrate dramatic and repeated transient increases in [Ca2+]i. The mean peak [Ca2+]i of these transients is 389 +/- 70 nM with an average duration of 77 s. The necessity of any of these transient changes in calcium for the completion of mitotic or interphase activities remains under investigation.
Topics: Anaphase; Animals; Calcium; Cell Division; Cell Line; Cytophotometry; Interphase; Metaphase; Mitosis; Spectrometry, Fluorescence; Time Factors
PubMed: 3417787
DOI: 10.1083/jcb.107.3.993