The purpose of this study was (1) to determine whether a correlation exists among the protein profiles, extracted from cell membranes of mutants belonging to five pigment cluster groups, (2) to locate the protein moiety and cartenoprotein complex in the membranes of wild type and colorless mutant (designated W-19) of C. poinsettae and to show whether there are any structural differences between cell membranes of the wild type and a colorless mutant, (3) to determine the effect of six antibiotics on cartenoid gene expression.

No description available.

Master of Science

This investigation has for its aim the explanation of growth and pigment production of Micrococcus flavus, Micrococcus roseus, Micrococcus subvitreus, and Sarcina citrea by the addition of various nutrient test materials to a standard culture medium.

No / The proopiomelanocortin (POMC)-derived peptides, ACTH and alpha-MSH, are the principal mediators of human skin pigmentation via their action at the melanocortin-1 receptor (MC-1R). Recent data have demonstrated the existence of a functionally active beta-endorphin/mu-opiate receptor system in both epidermal and hair follicle melanocytes, whereby beta-endorphin can regulate melanogenesis, dendricity, and proliferation in these cells. However, a role for ACTH and alpha-MSH in the regulation of the human follicular pigmentary unit has not been determined. This study was designed to examine the involvement of ACTH and the alpha-MSH/MC-1R system in human follicular melanocyte biology. To address this question we employed RT-PCR and immunohisto/cytochemistry, and a functional role for these POMC peptides was assessed in follicular melanocyte cultures. Human scalp hair follicle melanocytes synthesized and processed POMC. ACTH and alpha-MSH in association with their processing enzymes and MC-1R are expressed in human follicular melanocytes at the message level in vitro and at the protein level both in situ and in vitro. The expression of the POMC/MC-1R receptor system was confined only to subpopulations of poorly and moderately differentiated melanocytes. In addition, functional studies revealed that ACTH and alpha-MSH are able to promote follicular melanocyte differentiation by up-regulating melanogenesis, dendricity, and proliferation in less differentiated melanocyte subpopulations. Thus, these findings suggest a role for these POMC peptides in regulating human hair follicle melanocyte differentiation.

No / The adoption of mineral pigments for artistic expression can be traced back to the paintings of the Magdalenian and Cro-Magnon cultures of about 25 000 years BCE, wherein a limited range of oxides such as pyrolusite, goethite, and hematite were utilized along with the first synthetic pigment, carbon, to decorate cave dwellings with surprisingly lifelike images. The growth of chemistry created a new palette of colors, culminating in the preparation of organic dyes and pigments in the mid-nineteenth century. The historical usage of mineral pigments largely based on metal sulfides, oxides, carbonates, sulfates, and nitrates followed by early natural organic extracts from botanical and insect species such as dragon's blood, indigo, gamboge, and cochineal that were later partially superseded by a wide range of synthetic azo dyes is described, where possible alongside their accepted date of first adoption in artworks; while this is relatively easy to define in the case of synthetic materials, it is rather more conjectural for the establishment of an historical timeline for naturally occurring minerals. The characterization of pigments using analytical chemical techniques applied to artworks and artifacts can therefore be used to identify an out-of-context material in an otherwise perfectly acceptable work of art sufficient to render an appellation of ‘fake’ being applied to the object. However, unrecorded later restoration whereby an artwork has been retouched using modern, more stable pigments replacing their more fugitive analogues can cause problems in this respect. In this article, the mineral pigments used are tabulated along with their synthetic counterparts that frequently have precise dates for their appearance in the chemical literature giving rise to a contextual and chronological aspect to analytical science applied to artworks – a forensic art theme. Much work has recently been discussed in the analytical discrimination between natural mineral pigments used historically and their more recent synthetic counterparts: here, terminological differences are critically important and often lacking – hence, the confused usage of terms such as cinnabar and vermilion, lapis lazuli and ultramarine, which are to be found in artists' manuals and contemporary texts.

No / Chemical investigation of nonindigenous Tubastraea coccinea and T. tagusensis by Raman spectroscopy resulted in the identification of carotenoids and indolic alkaloids. Comparison of Raman data obtained for the in situ and crude extracts has shown the potential of the technique for characterizing samples which are metabolic fingerprints, by means of band analysis. Raman bands at ca. 1520, 1160, and 1005 cm–1 assigned to ν1(C═C), ν2(C—C), and ρ3(C—CH3) modes were attributed to astaxanthin, and the band at 1665 cm–1 could be assigned to the ν(C—N), ν(C—O), and ν(C—C) coupled mode of the iminoimidazolinone from aplysinopsin. The antioxidant activity of the crude extracts has also been demonstrated, suggesting a possible role of these classes of compounds in the studied corals.

No / The Raman spectrum of scytonin, a novel derivative of the parent scytonemin, is predicted from DFT calculations of the most stable, lowest energy, conformational structure. The diagnostic importance of this study relates to the spectral ability to discriminate between scytonemin and its derivatives alone or in admixture with geological matrices from identified characteristic Raman spectral signatures. The successful interpretation of biosignatures from a wide range of cyanobacterial extremophilic colonization in terrestrial and extraterrestrial scenarios is a fundamental requirement of the evaluation of robotic spectroscopic instrumentation in search for life missions. Scytonemin is produced exclusively by cyanobacterial colonies in environmentally stressed habitats and is widely recognized as a key target biomarker molecule in this enterprise. Here, the detailed theoretical analysis of the structure of scytonin enables a protocol to be established for the recognition of characteristic bands in its Raman spectrum and to accomplish the successful differentiation between scytonin and scytonemin as well as other scytonemin derivatives such as the dimethoxy and tetramethoxy compounds that have been isolated from cyanobacterial colonies but which have not yet been characterized spectroscopically. The results of this study will facilitate an extension of the database capability for miniaturized Raman spectrometers which will be carried on board search for life robotic missions to Mars, Europa, and Titan.

No / In this study, we have shown how particles in carbon black tattoo ink accumulate in the human skin dermis using fine-resolution atomic force microscopy, with which a single ink particle in the collagenous network can be imaged. This information further demonstrates that tattoo inks are nano-particles. Further, we have deposited a commercially available tattoo ink on a glass slide and calculated a range of volumes for single ink particles.

Yes / This article aims to investigate the flowability, physical, mechanical, and durability properties of metakaolin (MK)-added colored cement mortars exposed to the effects of H2SO4 sulfuric acid (SA) and HNO3 nitric acid (NA). MK was used in 20% replacement with cement, and yellow (YP) and red pigments (RP) were added to the mixtures at 1% and 3% of the cement by weight. According to the results, although MK reduced the workability and, therefore, the flow diameter (FD) of mortars, thanks to the void-filling feature of MK, filling the voids in the microstructure caused the samples' apparent porosity (AP) and relative dynamic modulus of elasticity (RDME) to decrease. Additionally, MK significantly improved the residual compressive (RCS) and residual flexural strengths (RFS) of the samples thanks to the calcium-silicate-hydrate (C-S-H) bonds it formed in the interior structure, owing to its high pozzolanic efficiency. Moreover, this improvement of MK is more remarkable in samples that remain subject to SA and NA attacks for more time. Furthermore, while YP reduces the workability of mortars and, therefore, the FD value due to its needle-tipped grain structure, RP increases the FD value of the mortars with its spherical grain structure. However, YP and RP contributed to reducing the AP of the samples and increasing RCS and RFS capacities at a meager rate by showing a micro-filling effect. In addition, there were significant increases in the total color changes (E) of YP and RP-added colored mortar samples, especially after longer SA and NA attacks. / This paper is financially supported by the University of Van Yüzüncü Yil, Department of BAP, within the scope of the CDS-2023-10468 project. / The full-text of this article will be released for public view at the end of the publisher embargo on 4 May 2025.