Golden Pigment Research Articles

Dragline silk fibers from golden orb‐web spider Trichonephila clavata ensure structural and mechanical robustness against ultraviolet radiation

AbstractA diurnal spider, Trichonephila clavata (T. clavata), is often called a golden orb‐weaver because its dragline or lifeline silk fibers exhibit a golden color. However, little is known about the biological roles of the golden pigment. Meanwhile, Araneus ventricosus, which is a nocturnal spider, spins colorless silk fibers. Here, we investigated the effect of ultraviolet (UV) irradiation on physical properties of silk fibers obtained from these diurnal and nocturnal spiders. After UV exposure, the dragline silk of the nocturnal spiders appeared abraded and became insoluble due to gelation, whereas the diurnal spider silk remained intact. A dynamic mechanical thermal analysis under different humidity conditions revealed that the storage modulus of the silk from the nocturnal spider dropped markedly at low humidity levels after UV irradiation. This indicated that the molecular weight of this silk degraded under UV exposure and that the number of terminal amino and carboxyl groups increased due to the breakage of the main protein chains. In contrast, the structural and mechanical properties of the diurnal spider silk were maintained regardless of the UV irradiation. Therefore, the golden pigments in the dragline silk of T. clavata most likely played a role in protecting the silk from UV damage.

Identification of staphyloxanthin and derivates in yellow-pigmented Staphylococcus capitis subsp. capitis.

Staphylococcus capitis naturally colonizes the human skin but as an opportunistic pathogen, it can also cause biofilm-associated infections and bloodstream infections in newborns. Previously, we found that two strains from the subspecies S. capitis subsp. capitis produce yellow carotenoids despite the initial species description, reporting this subspecies as non-pigmented. In Staphylococcus aureus, the golden pigment staphyloxanthin is an important virulence factor, protecting cells against reactive oxygen species and modulating membrane fluidity. In this study, we used two pigmented (DSM 111179 and DSM 113836) and two non-pigmented S. capitis subsp. capitis strains (DSM 20326T and DSM 31028) to identify the pigment, determine conditions under which pigment-production occurs and investigate whether pigmented strains show increased resistance to ROS and temperature stress. We found that the non-pigmented strains remained colorless regardless of the type of medium, whereas intensity of pigmentation in the two pigmented strains increased under low nutrient conditions and with longer incubation times. We were able to detect and identify staphyloxanthin and its derivates in the two pigmented strains but found that methanol cell extracts from all four strains showed ROS scavenging activity regardless of staphyloxanthin production. Increased survival to cold temperatures (-20°C) was detected in the two pigmented strains only after long-term storage compared to the non-pigmented strains. The identification of staphyloxanthin in S. capitis is of clinical relevance and could be used, in the same way as in S. aureus, as a possible target for anti-virulence drug design.

Investigating Brazilian Paintings from the 19th Century by MA-XRF

In this work, four artworks dating from the 19th century by Brazilian painters Firmino Monteiro, Henrique Bernardelli, and Eliseu Visconti were analyzed by MA-XRF. Pb-L, Fe-K, and Hg-L were the main elemental maps obtained in all paintings. In the artworks of Henrique Bernardelli and Eliseu Visconti, maps of Cr-K and Co-K were also obtained. These results indicate that these Brazilian painters from the 19th century used few pigments to create their paintings, with the different hues coming mainly from ocher pigments. Using correlation image methods, no intentional mixtures of pigments made by the painters were found. These results indicate that the three painters used similar materials and techniques for preparing their pigments. These similarities are confirmed through statistical analysis by non-negative matrix factorization (NMF). In this method, it was possible to verify that the main bases of the contribution of the data registered in each artwork are the same. The analysis also revealed that one of Eliseu Visconti’s paintings had an underlying painting, and another artwork by Eliseu Visconti contained a golden pigment with Cu and Zn. These results have helped art historians and conservators understand the creation process of Brazilian artists in the 19th century.

All that glitters is not gold: Multi-instrumental identification of Viking Age orpiment (As2S3) from Surtshellir cave, Iceland

Fragments of orpiment (As2S3) from a Viking Age structure inside Iceland’s Surtshellir cave represent the farthest-known occurrence of this rare mineral from sources known to have been exploited during the Early Middle Ages. Actual fragments of orpiment (from Latin auripigmentum, golden pigment) are only documented in late first millennium AD northern Europe from Dunadd, the seat of the Dalriadic kings in western Scotland (7th-8th century AD), Tonymore Crannóg, an elite Irish site (8th-9th century AD), and now Surtshellir (AD 920–1020). Ground to create a pigment, orpiment was used to add brilliant yellows to illuminated manuscripts produced from the 7th-10th centuries AD in elite monastic and ecclesiastic centers of Ireland, the Carolingian Empire, and Anglo-Saxon England. Its only prior documented uses in Viking Age Scandinavia, however, are from the furnishings of King Gorm’s grave at Jelling (Denmark), ca. AD 950–960, and possibly the Gokstad ship, ca. AD 900–905. The twelve fragments of orpiment from Surtshellir, verified through pXRF (hand-held X-Ray Fluorescence) and SEM/EDS (Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy), link this site to 10th century AD interaction and trade networks that stretched from the North Atlantic to Anatolia and provide supportive evidence for re-interpreting the cave as an important, elite-controlled ritual site from Iceland’s Viking Age.

Some Biological Features of Staphylococci Isolated from Milk of Cows with Mastitis

White staphylococcus spp. is the common name for staphylococci that do not form a golden pigment. It causes and complicates the course of many inflammatory processes in various organs and tissues of humans and animals. In particular, in dairy cattle breeding, white staphylococcus is the main cause of serous and serous-catarrhal mastitis. Low efficiency in the treatment of staphylococcal mastitis is due to the resistance of the pathogen to antibiotics. Accordingly, the use of chemotherapeutic drugs for mastitis without prior determination of the sensitivity of isolated strains of pathogenic microorganisms to antibiotics leads to double economic damage.

Characterization of pharaonic cartonnage from a late period, Saqqara excavations

PurposeThe purpose of this paper is to identify the pigments, mediums and ground layer used during the late era of ancient Egyptian civilization through the analysis of mummy Cartonnage based on the use of multiple analysis, such as electron microscopy, X-rays, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR).Design/methodology/approachThis study analyzed some fragments from a painted cartonnage of a mummy date back to the late period. Light microscopy, X-ray diffraction analysis, FTIR analysis and investigation of the surface morphology by SEM were used to identify the chemical and anatomical structure of cartonnage.FindingsThe results clearly showed use of copper and extracted gold from the veins of the quartz to get the golden pigment, but it is full of voids which were a major cause of the degradation.Originality/valueThe study is the first of its kind on the components of this cartonnage in Saqqara stores.

Role of SigB and Staphyloxanthin in Radiation Survival of Staphylococcus aureus.

Staphylococcus aureus is a potent human pathogen. The virulence of this bacterium depends on a multitude of factors that it produces. One such virulence factor is the golden pigment, staphyloxanthin, which has been shown to protect the bacterium from oxidative stress. Expression of the staphyloxanthin biosynthetic pathway is dependent on SigB, a global stress response regulator in S. aureus. This study investigated the role of staphyloxanthin and SigB in protection of S. aureus from radiation damage. Using stationary-phase bacterial cells, it was determined that the staphyloxanthin-deficient (crt mutant) strain was significantly sensitive to UV radiation (~ threefold), but not sensitive to X-radiation. However, a SigB-deficient S. aureus that also lacks staphyloxanthin, was significantly sensitive to both UV- and X-radiation. To confirm that protection from X-radiation was due to hydroxyl radicals, effect of 3M glycerol, a known hydroxyl scavenger, was also investigated. Glycerol increased the survival of the S. aureus sigB mutant to the wild-type level suggesting that the X-radiation sensitivity of these mutants was due to deficiency in scavenging hydroxyl radicals. In summary, SigB is critical for protection of S. aureus cells from radiation damage.

A novel SigB(Q225P) mutation in Staphylococcus aureus retains virulence but promotes biofilm formation

Staphylococcus aureus is an important pathogen that produces abundant virulence factors, which cause various diseases that burden human health worldwide. The stress response regulon called sigma factor B (SigB) is a well-characterized global regulator that is involved in the regulation of S. aureus virulence, pigmentation, and biofilm formation. However, the regulatory network upon SigB in S. aureus is incompletely described. Here, we identified a novel substitution mutation, SigB(Q225P), which contributed the nonpigmented phenotype of S. aureus. The S. aureus mutant carrying SigB(Q225P) substitution lacks staphyloxanthin, a key virulence factor in protecting bacteria from host-oxidant killing, but retains bacterial pathogenicity with pleiotropic alterations in virulence factors, resulting in similar lethality and abscess formation ability in animal models. We also reported the SigB(Q225P) promotion of biofilm formation in S. aureus. Real-time quantitative polymerase chain reaction (RT-qPCR) revealed that the expression of nuc gene, which encodes thermonuclease, was significantly downregulated, resulting in accumulation of eDNA in the biofilm of SigB(Q225P) mutant strain. LacZ reporter assay showed that SigB(Q225P) influenced the activity of nuc promoter. Furthermore, electrophoretic mobility shift assay (EMSA) and Bio-layer interferometry (BLI) assay revealed that both SigB and SigB(Q225P) proteins could directly bind to nuc gene promoter; however, the binding activity decreased for SigB(Q225P). Our data renewed the understanding of the relationship between S. aureus golden pigment and its virulence and suggested that a single substitution mutation in SigB might enhance the biofilm formation of S. aureus by directly downregulating nuc expression.

Interactions of staphyloxanthin and enterobactin with myeloperoxidase and reactive chlorine species

When neutrophils engulf bacteria, myeloperoxidase converts hydrogen peroxide to hypochlorous acid, which is toxic to all micro-organisms. It has been suggested that some pathogens have virulence factors that target myeloperoxidase to dampen the oxidative reactions of neutrophils. These virulence factors include staphyloxanthin, the golden pigment of Staphylococcus aureus, and enterobactin – a siderophore released by gram-negative bacteria. We investigated the potential of staphyloxanthin and enterobactin to shield bacteria from hypochlorous acid and related chloramines. Clinical strains of S. aureus with high levels of staphyloxanthin and related carotenoids were in general more resistant to low doses of hypochlorous acid than non-pigmented bacteria. But some non-pigmented strains were also resistant to the oxidant. Doses of reactive chlorine species that killed bacteria also bleached their carotenoids. Hypochlorous acid, NH2Cl, and NHCl2 bleached purified staphyloxanthin. When S. aureus were phagocytosed by neutrophils there was no discernible loss of staphyloxanthin. These data suggest that staphyloxanthin is capable of protecting bacteria from low doses of reactive chlorine species formed inside phagosomes. Enterobactin was not an inhibitor of myeloperoxidase. We conclude that staphyloxanthin may protect some bacterial strains against oxidative killing by neutrophils, but enterobactin will not inhibit the production of hypochlorous acid.

The Staphylococcus aureus AirSR Two-Component System Mediates Reactive Oxygen Species Resistance via Transcriptional Regulation of Staphyloxanthin Production.

Staphylococcus aureus is an important opportunistic pathogen and is the etiological agent of many hospital- and community-acquired infections. The golden pigment, staphyloxanthin, of S. aureus colonies distinguishes it from other staphylococci and related Gram-positive cocci. Staphyloxanthin is the product of a series of biosynthetic steps that produce a unique membrane-embedded C30 golden carotenoid and is an important antioxidant. We observed that a strain with an inducible airR overexpression cassette had noticeably increased staphyloxanthin production compared to the wild-type strain under aerobic culturing conditions. Further analysis revealed that depletion or overproduction of the AirR response regulator resulted in a corresponding decrease or increase in staphyloxanthin production and susceptibility to killing by hydrogen peroxide, respectively. Furthermore, the genetic elimination of staphyloxanthin during AirR overproduction abolished the protective phenotype of increased staphyloxanthin production in a whole-blood survival assay. Promoter reporter and gel shift assays determined that the AirR response regulator is a direct positive regulator of the staphyloxanthin-biosynthetic operon, crtOPQMN, but is epistatic to alternative sigma factor B. Taken together, these data indicate that AirSR positively regulates the staphyloxanthin-biosynthetic operon crtOPQMN, promoting survival of S. aureus in the presence of oxidants.

Discovery of Golden-Colored Channel Catfish (Ictalurus punctatus), with Preliminary Culture Evaluations

Channel catfish (Ictalurus punctatus) with a golden pigment and black spots were discovered during harvest of a University of Arkansas at Pine Bluff (UAPB) experimental channel catfish production pond. Golden catfish were mixed with catfish of normal pigmentation and of similar sizes. Following the observation that differences existed in algal-off flavor, three golden and three normal pigmented harvestable catfish were hand-filleted and proximate and sensory evaluations performed. Golden catfish were significantly lower in percent protein, and total fat, but higher in moisture and ash. Lower lipid levels would account for less off-flavor compounds in golden fish. A lipid profile was performed with both pigmented fishes at a later date from fish cultured separately in the same pond. No significant differences in lipid percentages were found. Taste tests were performed on two occasions with two batches of golden and normal catfish. Six of eight panelists preferred microwaved golden fillet samples for the milder flavor, less toughness, and less greasy/metallic aftertaste. Other golden variant cultured fishes have been evaluated and results are similar. As possible management and willingness to pay benefits appear to exist, further evaluations are recommended.

Curcumin differs from tetrahydrocurcumin for molecular targets, signaling pathways and cellular responses.

Curcumin (diferuloylmethane), a golden pigment from turmeric, has been linked with antioxidant, anti-inflammatory, anticancer, antiviral, antibacterial, and antidiabetic properties. Most of the these activities have been assigned to methoxy, hydroxyl, α,β-unsaturated carbonyl moiety or to diketone groups present in curcumin. One of the major metabolites of curcumin is tetrahydrocurcumin (THC), which lacks α,β-unsaturated carbonyl moiety and is white in color. Whether THC is superior to curcumin on a molecular level is unclear and thus is the focus of this review. Various studies suggest that curcumin is a more potent antioxidant than THC; curcumin (but not THC) can bind and inhibit numerous targets including DNA (cytosine-5)-methyltransferase-1, heme oxygenase-1, Nrf2, β-catenin, cyclooxygenase-2, NF-kappaB, inducible nitric oxide synthase, nitric oxide, amyloid plaques, reactive oxygen species, vascular endothelial growth factor, cyclin D1, glutathione, P300/CBP, 5-lipoxygenase, cytosolic phospholipase A2, prostaglandin E2, inhibitor of NF-kappaB kinase-1, -2, P38MAPK, p-Tau, tumor necrosis factor-α, forkhead box O3a, CRAC; curcumin can inhibit tumor cell growth and suppress cellular entry of viruses such as influenza A virus and hepatitis C virus much more effectively than THC; curcumin affects membrane mobility; and curcumin is also more effective than THC in suppressing phorbol-ester-induced tumor promotion. Other studies, however, suggest that THC is superior to curcumin for induction of GSH peroxidase, glutathione-S-transferase, NADPH: quinone reductase, and quenching of free radicals. Most studies have indicated that THC exhibits higher antioxidant activity, but curcumin exhibits both pro-oxidant and antioxidant properties.

Recent Developments in Delivery, Bioavailability, Absorption and Metabolism of Curcumin: the Golden Pigment from Golden Spice

Curcumin (diferuloylmethane) is a yellow pigment present in the spice turmeric (Curcuma longa) that has been associated with antioxidant, anti-inflammatory, anticancer, antiviral, and antibacterial activities as indicated by over 6,000 citations. In addition, over one hundred clinical studies have been carried out with curcumin. One of the major problems with curcumin is perceived to be the bioavailability. How curcumin should be delivered in vivo, how bioavailable is it, how well curcumin is absorbed and how it is metabolized, is the focus of this review. Various formulations of curcumin that are currently available are also discussed.

Plasmodium, Saurocytozoon and Haemocystidium parasites (Apicomplexa: Plasmodiidae) from the rock agama, Laudakia caucasia (Sauria: Agamidae), in southern Asia

The rock agama, Laudakia caucasia Eichwald (Agamidae) is host to Plasmodium caucasica sp. n. and Saurocytozoon agamidorum sp. n. in western Pakistan. Plasmodium caucasica is characterized by very large meronts, 11-21 by 8-17 microm that produce 32-67 merozoites, which nearly fill the host erythrocyte, and smaller, ovoid to elongate gametocytes, 6-14 by 2.5-6 microm, with length by width (LW) 21-55 microm2, and L/W ratio 1.0-4.0. Host cells are usually mature erythrocytes. In Azerbaijan, P. caucasica parasitizes immature erythroid cells. Dimensions of meronts are 10-16 by 6-12 microm, and merozoite numbers are 12-44. Gametocytes are 6-14 by 3-6 microm, with LW 31-56 microm2, and L/W ratio 1.0-4.0. Saurocytozoon agamidorum sp. n. gametocytes are 6.5-13 microm in diameter, with LW 35-79 microm2, and L/W ratio 1.0-2.2. They occupy lymphocytes as host cells, which are greatly distorted by gametocyte presence and often show nuclei nearly divided into two portions, one portion at each end of the cell. Haemocystidium grahami (Shortt, 1922), redescribed from material found in L. caucasia from Azerbaijan, has rounded to elongate gametocytes, 8-19.5 by 4-8 microm, LW 60.5-102 microm2, and L/W ratio 1.0-4.5. The prominent light golden pigment granules often coalesce to nearly cover the surface of the gametocyte. The presence of P. caucasica and S. agamidorum extends the range of the two genera in saurian hosts throughout much of the southern Asia mainland.

The taming of curcumin: Development and clinical validation of a Meriva®, a phospholipid complex of the golden pigment of turmeric

The taming of curcumin: Development and clinical validation of a Meriva®, a phospholipid complex of the golden pigment of turmeric

Golden Pigment Production and Virulence Gene Expression Are Affected by Metabolisms in Staphylococcus aureus

The pathogenesis of staphylococcal infections is multifactorial. Golden pigment is an eponymous feature of the human pathogen Staphylococcus aureus that shields the microbe from oxidation-based clearance, an innate host immune response to infection. Here, we screened a collection of S. aureus transposon mutants for pigment production variants. A total of 15 previously unidentified genes were discovered. Notably, disrupting metabolic pathways such as the tricarboxylic acid cycle, purine biosynthesis, and oxidative phosphorylation yields mutants with enhanced pigmentation. The dramatic effect on pigment production seems to correlate with altered expression of virulence determinants. Microarray analysis further indicates that purine biosynthesis impacts the expression of approximately 400 genes involved in a broad spectrum of functions including virulence. The purine biosynthesis mutant and oxidative phosphorylation mutant strains exhibit significantly attenuated virulence in a murine abscess model of infection. Inhibition of purine biosynthesis with a known small-molecule inhibitor results in altered virulence gene expression and virulence attenuation during infection. Taken together, these results suggest an intimate link between metabolic processes and virulence gene expression in S. aureus. This study also establishes the importance of purine biosynthesis and oxidative phosphorylation for in vivo survival.

Staphylococcus aureus golden pigment impairs neutrophil killing and promotes virulence through its antioxidant activity

Golden color imparted by carotenoid pigments is the eponymous feature of the human pathogen Staphylococcus aureus. Here we demonstrate a role of this hallmark phenotype in virulence. Compared with the wild-type (WT) bacterium, a S. aureus mutant with disrupted carotenoid biosynthesis is more susceptible to oxidant killing, has impaired neutrophil survival, and is less pathogenic in a mouse subcutaneous abscess model. The survival advantage of WT S. aureus over the carotenoid-deficient mutant is lost upon inhibition of neutrophil oxidative burst or in human or murine nicotinamide adenine dinucleotide phosphate oxidase–deficient hosts. Conversely, heterologous expression of the S. aureus carotenoid in the nonpigmented Streptococcus pyogenes confers enhanced oxidant and neutrophil resistance and increased animal virulence. Blocking S. aureus carotenogenesis increases oxidant sensitivity and decreases whole-blood survival, suggesting a novel target for antibiotic therapy.

Culture conditions for yellow pigment formation byMonascus sp. KB 10 grown on cassava medium

An isolate ofMonascus, from a commercial, fermented soybean curd (sufu) was grown on a cassava medium. With medium at an initial pH of 7.0 an orange-red pigmentation was produced but with an initial pH below 4, a light golden pigment was obtained. A medium containing, w/v, 3% cassava starch, 0.4% peptone and 0.1% glutamic acid, with an initial pH of 2.5 was optimal for the production of this yellow pigment, which had a single maximum absorption spectrum at 330 nm. The spectroscopic characterization of the purified yellow pigments demonstrated a monascin-ankaflavin-monascorubrin skeleton.

Observations on the resistance to drying of staphylococcal strains.

Death rates have been determined for staphylococcal strains dried on cotton blanket material and stored at room temperature in the dark and in the light. Methicillin-resistant Staphylococcus aureus (MRSA) strains that produced a golden pigment and had a wide distribution within the hospital survived for longer periods than MRSA strains that produced little pigment and had a restricted local distribution. Death rates of methicillin-sensitive strains of S. aureus at day 7 were similar to those of the general epidemic MRSA strains, and there was no significant difference between the death rates at day 7 of the local epidemic MRSA strains and the coagulase-negative strains.

Plasmodium brygooisp. n. fromChamaeleo brevicornisof Madagascar, with a redescription ofPlasmodium robinsoni(Brygoo, 1962) from its type host and an additional host,Chamaeleo parsoni crucifer

SUMMARY. Plasmodium brygooi sp. n., described from Chamaeleo brevicornis of Madagascar, has schizonts smaller than or equal to host cell nucleus size. Schizonts produce 10-16 merozoites usually arranged peripherally around clusters of dark pigment granules. Gametocytes, oval or elongate, average slightly larger than host cell nuclei. Schizonts and gametocytes usually lie polar in enlarged erythrocytes. Hypertrophy of host cell nuclei is produced by schizonts but not by gametocytes. Plasmodium robinsoni (Brygoo) 1962 is a much larger parasite of C. brevicornis and Chamaeleo parsoni crucifer. Schizonts are round, oval or elongate, and approximate gameto­ cytes in size. The 40-74 merozoites fill schizonts which usually contain a single, central large mass of golden pigment. Gametocytes are oval to elongate or bulky, with macrogametocytes larger and less elongate than microgametocytes. Both schizonts and gametocytes average three times or more the size of host cell nuclei. Host cells of asexual or sexual stages show hypertrophy but only erythrocytes parasitized by schizonts have enlarged nuclei.