Search results for "PIGMENTATION"

Preliminary approach to elucidate the role of pigment as a binding site for drugs and chemicals in anagen hairs: pigments as carriers for 3 H-haloper…

2002

In view of the melanin-binding characteristics of haloperidol and its differential uptake by pigment- and non-pigment-producing cells, a co-culture of HaCaT with Sk-Mel-1 cell lines was performed to investigate whether melanosomes act as carriers for drug molecules associated with the pigments. Initially, HaCaT and Sk-Mel-1 cells were separately cultivated in the presence of 3H-haloperidol (400 pmol/ml medium ) for 28 days followed by subsequent co-cultivation in the absence of 3H-haloperidol for 5 days. The transfer of pigments into the keratinocytes during co-culture was confirmed by transmission electron microscopy. After the co-culture experiments a striking increase (or = 50%) of 3H-ha…

Hyperspectral venous image quality assessment for optimum illumination range selection based on skin tone characteristics

2014

Background Subcutaneous veins localization is usually performed manually by medical staff to find suitable vein to insert catheter for medication delivery or blood sample function. The rule of thumb is to find large and straight enough vein for the medication to flow inside of the selected blood vessel without any obstruction. The problem of peripheral difficult venous access arises when patient’s veins are not visible due to any reason like dark skin tone, presence of hair, high body fat or dehydrated condition, etc. Methods To enhance the visibility of veins, near infrared imaging systems is used to assist medical staff in veins localization process. Optimum illumination is crucial to obt…

2-D mapping of skin chromophores in the spectral range 500 - 700 nm

2009

The multi-spectral imaging technique has been used for distant mapping of in-vivo skin chromophores by analyzing spectral data at each reflected image pixel and constructing 2-D maps of the relative concentrations of oxy-/deoxy-haemoglobin and melanin. Instead of using a broad visible-NIR spectral range, this study focuses on narrowed spectral band 500–700 nm, speeding-up the signal processing procedure. Regression analysis confirmed that superposition of three Gaussians is optimal analytic approximation for the oxy-haemoglobin absorption tabular spectrum in this spectral band, while superposition of two Gaussians fits well for deoxy-haemoglobin absorption and exponential function – for mel…

Environmental stress affects the expression of a carotenoid-based sexual trait in male zebra finches.

2007

SUMMARY Abiotic factors including thermal stress are suggested to exert constrains on sexual ornaments through trade-offs between sexual displays and physiological functions related to self-maintenance. Given the health properties of carotenoid pigments, carotenoid-based ornaments offer a relevant context in which to investigate the effect of environmental stress, such as ambient temperature, on the production and maintenance of secondary sexual traits and, also, to explore the proximate mechanisms shaping their expression. In this study, we exposed male zebra finches (Taeniopygia guttata) to environmental stress by exposing them to two temperature regimes (6 and 26°C) over a 4 week period.…

Rapid Changes in the Sex Linkage of Male Coloration in Introduced Guppy Populations

2017

Theory predicts that the sex linkage of sexually selected traits can influence the direction and rate of evolution and should itself evolve in response to sex-specific selection. Some studies have found intraspecific differences in sex linkage associated with differences in selection pressures, but we know nothing about how fast these differences can evolve. Here we show that introduced guppy populations showing rapid evolution of male coloration also show rapid changes in sex-linkage patterns. A comparison, using hormonal manipulations in females, of introduced populations of different ages suggests a consistent increase of autosomal or X-linked coloration 2 years after introduction from h…

Sex and MC1R variants in human pigmentation: Differences in tanning ability and sensitivity to sunlight between sexes

2016

Synaptic ribbons, spheres and intermediate structures in the developing rat retina

1992

The present study was conducted to investigate the qualitative and quantitative development of synaptic bodies in retinae of Wistar rats during postnatal days 4-28. In addition, the effects of different light regimens and of eye pigmentation on SB numbers were studied. Synaptic bodies were counted and measured in the outer plexiform layer of retinal tissue fixed and processed by routine electron microscopical techniques. At postnatal days 4 and 5, retinae showed only few synaptic bodies. The main numerical development of synaptic bodies occurred between postnatal days 4 and 9, numbers remaining more or less constant thereafter. The intracellular location of synaptic ribbons changed from pre…

Immune activation rapidly mirrored in a secondary sexual trait.

2003

A crucial assumption underlying most models of sexual selection is that sexual advertisements honestly reflect the phenotypic and/or genetic quality of their bearers ([1][1]). Here we show that experimental activation of the immune system is rapidly mirrored in the expression of a carotenoid-based

Differential detectability of polymorphic warning signals under varying light environments.

2014

The striking colour-pattern variation of some aposematic species is paradoxical because selection by predators is expected to favour signal uniformity. Although the mechanisms allowing for the maintenance of such variation are not well understood, possible explanations include both non-adaptive processes like drift and gene flow; and adaptive processes, such as an interaction between natural and sexual selection, spatial and temporal variation in selection, a link between behaviour or other fitness-related traits and phenotype, and predators' ability to generalise among different signals. Here we test whether warning-signal polymorphisms, such as that of dyeing poison frogs (Dendrobates tin…

Increased radiation from Chernobyl decreases the expression of red colouration in natural populations of bank voles (Myodes glareolus)

2014

AbstractPheomelanin is a pink to red version of melanin pigment deposited in skin and hair. Due to its bright colour, pheomelanin plays a crucial function in signalling, in particular sexual signalling. However, production of pheomelanin, as opposed to its dark alternative, eumelanin, bears costs in terms of consumption of antioxidants important for protection of DNA against naturally produced reactive oxidative species. Therefore, decreased expression of pheomelanin is expected in organisms exposed to severe oxidative stress such as that caused by exposure to chronic ionizing radiation. We tested if variable exposure to radiation among natural populations of bank voles Myodes glareolus in …