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Journal of Experimental Zoology. Part... Jul 2021Non-iridescent, structural coloration in birds originates from the feather's internal nanostructure (the spongy matrix) but melanin pigments and the barb's cortex can...
Non-iridescent, structural coloration in birds originates from the feather's internal nanostructure (the spongy matrix) but melanin pigments and the barb's cortex can affect the resulting color. Here, we explore how this nanostructure is combined with other elements in differently colored plumage patches within a bird. We investigated the association between light reflectance and the morphology of feathers from the back and belly plumage patches of male swallow tanagers (Tersina viridis), which look greenish-blue and white, respectively. Both plumage patches have a reflectance peak around 550 nm but the reflectance spectrum is much less saturated in the belly. The barbs of both types of feathers have similar spongy matrices at their tips, rendering their reflectance spectra alike. However, the color of the belly feather barbs changes from light green at their tips to white closer to the rachis. These barbs lack pigments and their morphology changes considerably throughout. Toward the rachis, the barb is almost hollow, with a reduced area occupied by spongy matrix, and has a flattened shape. By contrast, the blue back feathers' barbs have melanin underneath the spongy matrix resulting in a much more saturated coloration. The color of these barbs is also even along the barbs' length. Our results suggest that the color differences between the white and greenish-blue plumage are mostly due to the differential deposition of melanin and a reduction of the spongy matrix near the rachis of the belly feather barbs and not a result of changes in the characteristics of the spongy matrix.
Topics: Animals; Feathers; Male; Passeriformes; Pigmentation; Pigments, Biological
PubMed: 33988912
DOI: 10.1002/jez.b.23043 -
Die Naturwissenschaften Dec 2021Examining the role of color in mate choice without testing what colors the study animal is capable of seeing can lead to ill-posed hypotheses and erroneous conclusions....
Examining the role of color in mate choice without testing what colors the study animal is capable of seeing can lead to ill-posed hypotheses and erroneous conclusions. Here, we test the seemingly reasonable assumption that the sexually dimorphic red coloration of the male jumping spider Saitis barbipes is distinguishable, by females, from adjacent black color patches. Using microspectrophotometry, we find clear evidence for photoreceptor classes with maximal sensitivity in the UV (359 nm) and green (526 nm), inconclusive evidence for a photoreceptor maximally sensitive in the blue (451 nm), and no evidence for a red photoreceptor. No colored filters within the lens or retina could be found to shift green sensitivity to red. To quantify and visualize whether females may nevertheless be capable of discriminating red from black color patches, we take multispectral images of males and calculate photoreceptor excitations and color contrasts between color patches. Red patches would be, at best, barely discriminable from black, and not discriminable from a low-luminance green. Some color patches that appear achromatic to human eyes, such as beige and white, strongly absorb UV wavelengths and would appear as brighter "spider-greens" to S. barbipes than the red color patches. Unexpectedly, we discover an iridescent UV patch that contrasts strongly with the UV-absorbing surfaces dominating the rest of the spider. We propose that red and black coloration may serve identical purposes in sexual signaling, functioning to generate strong achromatic contrast with the visual background. The potential functional significance of red coloration outside of sexual signaling is discussed.
Topics: Animals; Female; Humans; Male; Spiders
PubMed: 34894274
DOI: 10.1007/s00114-021-01774-6 -
Food Chemistry Mar 2021The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single...
Combined liquid phase microextraction and fiber-optics-based cuvetteless micro-spectrophotometry for sensitive determination of ammonia in water and food samples by the indophenol reaction.
The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single drop microextraction of ammonia in phosphoric acid served to attain selectivity in complex matrices, and liquid-liquid microextraction of red or blue indophenol species into 1-octanol-isooctane (60:40, v/v) resulted into high sensitivity. Fiber-optics-based cuvetteless micro-spectrophotometry has been used for colorimetric determination on microliter volumes of extract. The linear dynamic range, limit of detection and enrichment factor have been found to be 0.2-3 mg kg, 0.14 mg kg and 38, respectively, measuring red species for milk, cheese and beer (4.9-5.5% error; 4.8-6.3% RSD; n = 5); and 5-400 µg L, 0.4 µg L and 137, respectively, measuring blue species for water samples (3.3-5.7% error; 3.6-6.8% RSD; n = 5). A plausible reaction scheme has been proposed for nitroprusside catalysis in indophenol reaction.
Topics: Ammonia; Beer; Fiber Optic Technology; Food Analysis; Indophenol; Limit of Detection; Liquid Phase Microextraction; Quantum Theory; Spectrophotometry; Water
PubMed: 33011465
DOI: 10.1016/j.foodchem.2020.128156 -
Journal of the Royal Society, Interface Oct 2023Colour is often not a static trait but can change over time either through biotic or abiotic factors. Humidity-dependent colour change can occur through either...
Colour is often not a static trait but can change over time either through biotic or abiotic factors. Humidity-dependent colour change can occur through either morphological change (e.g. to feather barbules in birds) or by the replacement of air by water causing a shift in refractive index, as seen in arthropod multi-layer cuticles or scales. The scaled springtail has scales that produce colour largely via thin film interference from their lamina. We observed a marked colour change from golden to violet/purple coloration in humid conditions. Light microscopy, micro-spectrophotometry, contact angle goniometry and optical modelling indicate that the formation of a thin film of water on top of the hydrophilic scales increases their laminar thin film thickness, causing a shift towards violet/purple colour. Evaporation of the water film causes the metallic golden colour to return. This constitutes a remarkably rapid colour change (in the order of seconds), only limited by the speed of water film condensation and evaporation, that may serve as inspiration for new dynamically coloured materials and sensors.
Topics: Animals; Humidity; Water; Color; Birds; Arthropods; Microscopy, Electron, Transmission
PubMed: 37788712
DOI: 10.1098/rsif.2023.0228 -
Analytical Chemistry Jan 2021The central relevance of cellular heterogeneity to biological phenomena raises the rational needs for analytical techniques with single-cell resolution. Here, we...
The central relevance of cellular heterogeneity to biological phenomena raises the rational needs for analytical techniques with single-cell resolution. Here, we developed a single-cell FTIR microspectroscopy-based method for the quantitative evaluation of cellular heterogeneity by calculating the cell-to-cell similarity distance of the infrared spectral data. Based on this method, we revealed the infrared phenotypes might reflect the dynamic heterogeneity changes in the cell population during the adipogenic differentiation of the human mesenchymal stem cells. These findings provide an alternative label-free optical approach for quantifying the cellular heterogeneity, and the combination with other single-cell analysis tools will be very helpful for understanding the genotype-to-phenotype relationship in cellular populations.
Topics: Adipogenesis; Cell Differentiation; Humans; Mesenchymal Stem Cells; Microspectrophotometry; Single-Cell Analysis; Spectroscopy, Fourier Transform Infrared; Synchrotrons
PubMed: 33290049
DOI: 10.1021/acs.analchem.0c04110 -
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 -
Journal of Forensic Sciences Nov 2019A new type of erasable gel pen ink is becoming increasingly popular because of the modifiable characteristics for writing on documents. This study attempts to...
A new type of erasable gel pen ink is becoming increasingly popular because of the modifiable characteristics for writing on documents. This study attempts to distinguish 12 types of blue and black erasable gel pens produced by mainstream stationery manufacturers using infrared (IR) visual analysis, Fourier transform infrared (FTIR) analysis, fluorescence analysis, and microspectrophotometry. The results demonstrate that IR visual, FTIR, and fluorescence analysis can be used to help distinguish each type of erasable gel ink. While microspectrophotometry can be used to effectively differentiate the blue gel inks in this study, there are limitations with respect to distinguishing black erasable gel pens. When these four optical analyses methods were used in combination, the gel inks could be accurately distinguished.
PubMed: 31107552
DOI: 10.1111/1556-4029.14072 -
Forensic Science International Apr 2020The analysis of soil evidence is crucial for the association of crime scenes, tools, and people involved. This work presents a case of excavating ancient tombs to steal...
The analysis of soil evidence is crucial for the association of crime scenes, tools, and people involved. This work presents a case of excavating ancient tombs to steal antiques. The soil from the criminal tools, tombs, and an antique were collected and analyzed. The color, element, and mineral composition of soil evidence were detected through microspectrophotometry, X-ray fluorescence, and X-ray diffraction. Chemometrics, including hierarchical cluster analysis and K-means clustering, was also utilized to assist in the differentiation and classification. The source of the antique was successfully inferred. The criminal tool and the location of the crime scene were also associated correctly. The soil analysis was highly supportive in reconstructing the crime scene.
Topics: Adult; Crime; Forensic Sciences; Humans; Male; Minerals; Soil; X-Ray Diffraction
PubMed: 32151883
DOI: 10.1016/j.forsciint.2020.110231 -
Journal of Forensic Sciences Nov 2021Identifying the formation time of a document is a problem forensic document examiners often face. It is understood that intersections with different intersecting...
Identifying the formation time of a document is a problem forensic document examiners often face. It is understood that intersections with different intersecting sequences made by the same laser printer and the same gel pen are distinct from each other under coaxial light, and the appearance of an oil film or bright metallic marks in the regions of interest can be used as the basis to identify that the ink is above the toner. However, the characteristics of intersections may be influenced by a number of factors. Studying the characteristics of the intersections formed by laser-printed graphics and handwriting strokes made with a gel pen in different intersecting sequences can help us determine the formation sequence of each part on a questioned document. In this manuscript, samples were made using three pen types and two laser printers. A Leica stereo microscope M205A was used to capture the apparent morphology of the intersections. Microspectrophotometry spectra of all intersections were collected in reflectance mode using a video spectral comparator 6000 (VSC6000), and the resultant data were measured and analyzed in Statistical Product and Service Solutions 26.0 (SPSS). The results showed that 92.5% absolute accuracy was achieved from blind tests, and the intersecting sequence can be determined using the optical data of the intersections with an accuracy of up to 97.5% through discriminant analysis under ideal conditions.
PubMed: 34379328
DOI: 10.1111/1556-4029.14830 -
Forensic Science International Dec 2019Microspectrophotometry data arise in the study of many forensically applicable situations. The situations here are those of ink and fibres. In a criminal investigation,...
Microspectrophotometry data arise in the study of many forensically applicable situations. The situations here are those of ink and fibres. In a criminal investigation, data associated with a crime scene are compared with data associated with a person of interest. Methods based on the likelihood ratio are often used to evaluate such evidence. A technique known as functional data analysis for determining likelihood ratios using the full spectrum is described. It provides support comparing a proposition of common source with a proposition of different sources for data from the crime scene and from the person of interest. Data are available from ink, woollen and cotton fibres. The effectiveness of the method is assessed using false positive and false negative rates and Tippett plots in the comparison of data from known sources.
PubMed: 31756683
DOI: 10.1016/j.forsciint.2019.110007