Shell Pigmentation Research Articles

Cu(II) Removal from Aqueous Solution by Ultrafiltration Assisted with Chestnut Shell Pigment

Cu(II) Removal from Aqueous Solution by Ultrafiltration Assisted with Chestnut Shell Pigment

Dietary Supplement of Microalgal Astaxanthin Extraction Improved Shell Pigmentation and Nutritional Value of Litopenaeus vannamei in an Indoor Industrial Aquaculture System

Blue-shell syndrome is associated with low levels of astaxanthin (Ax) deposition in cultured shrimp. Such a syndrome is a key issue in indoor industrial shrimp aquaculture. In this study, we investigated the effect of dietary supplementation with microalgal Ax extract (MAAE), extracted from the microalgae, Haematococcus pluvialis, on shell pigmentation and nutritional value of shrimp Litopenaeus vannamei. Dietary supplementation with MAAE (20 mg kg-1) effectively improved shrimp pigmentation. In addition to increased growth and nutritional value, shrimp muscles had higher free amino acid concentrations (Asp, Ser, Ala, Val, and His) and lower fatty acid concentrations (except for C18:0, C18:1n9c, C20:0, C20:2, and C24:1) compared to those in the control group. In conclusion, this study indicated that a relatively low dose of MAAE at 20 mg kg-1 may improve the growth and nutritional value of shrimp in an indoor industrial shrimp aquaculture system.

A StAR‐like gene involved in carotenoid metabolism and inner shell color in the freshwater pearl mussel, Hyriopsis cumingii

AbstractCarotenoids play key roles in organism coloration and have been found to have an effect on shell color. Steroidogenic acute regulatory protein‐like (StAR‐like) is a key gene involved in the accumulation of carotenoids. In this study, the full‐length cDNA sequence of HcStAR‐like, containing 994 nucleotides with an open reading frame encoding 307 amino acid residues, was isolated from the freshwater pearl mussel, Hyriopsis cumingii. HcStAR‐like expression levels were significantly higher in all tissues examined in golden (G‐) mussels compared with white (W‐) and purple (P‐) mussels (p < .05). Moreover, although HcStAR‐like expression levels were higher in P‐mussels than W‐mussels, this difference was only significant in the hepatopancreas (p < .05). Our in situ hybridization assay indicated that StAR‐like was localized to the outer fold of the mantle and the joint of the outer and middle folds of the mantle. The dsRNA interference of HcStAR‐like expression in G‐mussels was effective with an interference rate of 79.89% (p < .05). The total carotenoid content (TCC) in the mantle of the RNAi group decreased by 48.63% (p < .05). Our findings suggested that HcStAR‐like was involved in the accumulation of carotenoids and inner shell pigmentation in H. cumingii.

Cloning, characterization and expression prolife analysis ofldlr: Insight into purple shell formation inCyclina sinensis

The clam Cyclina sinensis is an economically important marine bivalve, and the diversity of its shell colour has potential applications in breeding. In this study, the distribution of purple pigments in the clam shell was examined, and Raman spectroscopy was conducted. The levels of total carotenoids and four common carotenoids in various tissues were also determined and analysed. Furthermore, the full-length cDNA of a low-density lipoprotein receptor gene (ldlr) was cloned and characterized, and the tissue distribution of ldlr gene expression was analysed. The results showed that purple pigments existed mainly in the nacre layer of the shell from the purple-shell clam, in which strong Raman peaks for carotenoids were observed, suggesting that carotenoids might be the main components of purple pigments in the purple shell. The TCC and the levels of four common carotenoids were higher in the outer margin of the mantle and shell of purple-shell clams than in those of white-shell clams, and the ldlr mRNA was highly expressed in the outer margin of the mantle in purple-shell clams. Taken together, our results suggest a possible molecular mechanism governing the selective transport of carotenoids in the mantle of purple-shell clams and shell colour formation. The results of this study will help to elucidate the colour formation mechanism in clam shells.

Multi-target bioactivity of summer quinones production in the Persian Gulf burrowing black-type sea urchin

After harvesting the sea urchin gonads for Japanese food “uni” echinoculture systems, the remaining shells and spines are considered waste. However, the material of shells and spines is thought to be rich in natural bioactive molecules. The current study used liquid chromatography–electrospray mass spectrometry to extract summer quinones pigment present in spines and shells of the burrowing sea urchin ‘black’ type Echinometra mathaei from the natural Qeshm Island echinoculture. Then, the biochemical, antioxidant, anti-inflammatory, antidiabetic, antibacterial, and cytotoxic activities of sea urchin quinones pigment were investigated. In terms of bioactivity, both shell and spine pigments demonstrated strong radical scavenging activity (antioxidant). The shell pigment exhibited maximum albumin denaturation inhibition (IC50 = 9.62 μg/ml) (anti-inflammatory), as well as α-amylase inhibition (92.28 percent 4.77) (antidiabetic). Pigments were discovered to have a low antibacterial effect against positive gramme bacteria, as well as low cytotoxic and embryotoxic effects when compared to Artemia salina and zebrafish (Danio rerio). For identification and quantification of pigment extracts, both the photodiode array detector and LC-ESI-MS were used. Spinochrome A, B, and C, as well as echinochrome A, were identified as bioactive quinonoid pigments. This chemical defence is discussed in relation to its algal diet and environmental conditions. In conclusion, the isolated pigments obtained from the shell and spines of E. mathaei sea urchins found to have potent bio-activity and can be used for various biomedical and pharmaceutical applications.

Ionic liquid and ultrasound-assisted extraction of chestnut shell pigment with good hair dyeing capability

To effectively extract the pigment from chestnut shell in a green and efficient way, an eco-friendly and efficient method based on ionic liquid ultrasonic assisted extraction (IL-UAE) was established. The effect of a series of 1-alkyl-3-methyl imidazole ionic liquids on the yield was investigated. The results indicated that the chain length of ionic liquids and the properties of anions and cations had a significant impact on the extraction, and 1-butyl-3-methylimidazolium acetate ([Bmim]OAc) had the best extraction effect. In addition, the concentration of bond breaking agent (sodium dodecyl sulfate, urea), concentration of [Bmim]OAc, liquid-solid ratio, extraction power, time, temperature and other parameters were tested by single factor. Sodium dodecyl sulfate (SDS), urea concentration and liquid-solid ratio were optimized by response surface methodology (RSM). The optimal process conditions were as follows: SDS concentration of 0.44% (w/v), urea concentration of 2.87% (w/v), [Bmim]OAc concentration of 1.07 mol/L, liquid-solid ratio of 36.26 mL/g, ultrasonic power of 350 W, ultrasonic time of 50 min, and ultrasonic temperature of 80 °C, respectively. Under these conditions, the yield was 71.60 mg/g. Compared with the conventional reflux extraction with organic solvents (sodium hydroxide, ethanol), the optimized method improved the yield by 42.24% and 38.70% in a shorter time (50min versus 120min), respectively. The physico-chemical properties of hair dyed with chestnut shell pigment extracted by IL-UAE were compared with those extracted by conventional organic solvents. The results showed that the former showed excellent color intensity, smooth hair surface morphology and low internal damage than the latter. Our results helped to accelerate the high-value applications of chestnut wastes.

Susceptibility of Four Abalone Species, Haliotis gigantea, Haliotis discus discus, Haliotis discus hannai and Haliotis diversicolor, to Abalone asfa-like Virus

Abalone amyotrophia is a viral disease that causes mass mortality of juvenile Haliotis discus and H. madaka. Although the cause of this disease has yet to be identified, we had previously postulated a novel virus with partial genome sequence similarity to that of African swine fever virus is the causative agent and proposed abalone asfa-like virus (AbALV) as a provisional name. In this study, three species of juvenile abalone (H. gigantea, H. discus discus, and H. diversicolor) and four species of adult abalone (the above three species plus H. discus hannai) were experimentally infected, and their susceptibility to AbALV was investigated by recording mortality, quantitatively determining viral load by PCR, and conducting immunohistological studies. In the infection test using 7-month-old animals, H. gigantea, which was previously reported to be insusceptible to the disease, showed multiplication of the virus to the same extent as in H. discus discus, resulting in mass mortality. H. discus discus at 7 months old showed abnormal cell masses, notches in the edge of the shell and brown pigmentation inside of the shell, which are histopathological and external features of this disease, while H. gigantea did not show any of these characteristics despite suffering high mortality. Adult abalones had low mortality and viral replication in all species; however, all three species, except H. diversicolor, became carriers of the virus. In immunohistological observations, cells positive for viral antigens were detected predominantly in the gills of juvenile H. discus discus and H. gigantea, and mass mortality was observed in these species. In H. diversicolor, neither juvenile nor adult mortality from infection occurred, and the AbALV genome was not increased by experimental infection through cohabitation or injection. Our results suggest that H. gigantea, H. discus discus and H. discus hannai are susceptible to AbALV, while H. diversicolor is not. These results confirmed that AbALV is the etiological agent of abalone amyotrophia.

MiRNA-mRNA Integration Analysis Reveals the Regulatory Roles of MiRNAs in Shell Pigmentation of the Manila clam (Ruditapes philippinarum).

The shell color of the Manila clam (Ruditapes philippinarum) is an economically important trait. We used high-throughput sequencing and transcriptome analysis to study the molecular mechanisms that underlie shell color formation and regulation in this species. We constructed small RNA libraries from mantle tissues from four shell color strains of Manila clam, subjected them to high-throughput sequencing. Notably, the results suggested that a number of pigment-associated genes including Mitf, HERC2, were negatively regulated by nvi-miR-2a, tgu-miR-133-3p, respectively. They might be involved in melanin formation via the activation of the melanogenesis pathway. And aae-miR-71-5p and dme-miR-7-5p linked to shell formation-related genes such as Calmodulin and IMSP3 were considered to participate in the calcium signaling pathway. We then used quantitative PCR to verify the candidate miRNAs and target genes in different shell color groups. Our results indicated that miR-7, miR-71, and miR-133 may regulate target mRNAs to participate in shell color pigmentation. These results provide the foundation to further characterize miRNA effects on the regulation of shell color and have significant implications for the breeding of new varieties of clams.

Specification of polymorphism and classification of shell coloration in gastropods by the example of Littorina obtusata (Gastropoda: Littorinidae)

Understanding the patterns of microevolutionary processes involves a wide range of population genetic studies on different species. However, the number of genetically studied species is limited due to significant methodological difficulties in testing the genetic conditionality of various traits. Developing population phenetics may become an alternative, which allows considering a large number of new species subject to development of morphologically and genetically-based system to describe the variability and classification of phenotypic traits. Gastropods are a classic object for carrying out population genetic studies based on the analysis of polymorphism of shell coloration. The parametric classification system proposed by S. Sergievsky et al. (1995) for periwinkles of the genus Littorina may serve as a basis for the developing of a universal system for classifying color traits for that taxonomic group. Since a large amount of new data has been published in recent years, this system requires correction and revision. The study aims to revise the system, taking into account new material on the pigment composition, as well as on the peculiarities of the formation and inheritance of color traits, their joint occurrence, etc. A revised and modified classification system for shell coloration traits is presented by the example of the White Sea gastropods L. obtusata; this system considers the idea of the formation of a phenotype as a combination of several elementary traits. These are traits associated with the formation of: 1) a shell background color (the ability to include different pigments in the ostracum and the hypostracum color); 2) a pattern of spots (the presence of inclusions of white and/or brown pigment); and 3) wide longitudinal bands (brown, white, and orange). Elementary traits are highlighted taking into account the pigments involved, as well as the mechanisms of their formation and inheritance. When describing the shell coloration, elementary traits are first used to describe relatively simple traits (groups of phenes “Shell background color”, “Hypostracum color”, “Pattern of spots”, and “Wide longitudinal bands”), which are subsequently combined to describe the phenotype as a whole. Our study provides an overview of the available data on the qualitative composition of shell pigments in periwinkles and patterns of formation and inheritance of color traits; their possible combinations are described. The phenes isolated by us are described together with their occurrence, color specification in the RGB system, and the peculiarities of the formation, taking into account the distribution of pigments in the shell. Visible traits, that may be used to assess the distribution of pigments in the shell, are indicated. The ontogenetic changes in traits are described. Despite the fact that the proposed classification system is developed by the example of L. obtusata, it can be used for same purposes for other periwinkle species and, with some modifications, for a wide range of gastropod species.

Shell Biosynthesis and Pigmentation as Revealed by the Expression of Tyrosinase and Tyrosinase-like Protein Genes in Pacific Oyster (Crassostrea gigas) with Different Shell Colors.

The widely recognized color polymorphisms of molluscan shell have been appreciated for hundreds of years by collectors and scientists, while molecular mechanisms underlying shell pigmentation are still poorly understood. Tyrosinase is a key rate-limiting enzyme for the biosynthesis of melanin. Here, we performed an extensive multi-omics data mining and identified two tyrosinase genes, including tyrosinase and tyrosinase-like protein 2 (Tyr and Typ-2 respectively), in the Pacific oyster Crassostrea gigas, and investigated the expression patterns of tyrosinase during adults and embryogenesis in black and white shellcolor C. gigas. Tissue expression analysis showed that two tyrosinase genes were both specifically expressed in the mantle, and the expression levels of Tyr and Typ-2 in the edge mantle were significantly higher than that in the central mantle. Besides, Tyr and Typ-2 genes were black shell-specific compared with whiteshell oysters. In situ hybridization showed that strong signals for Tyr were detected in the inner surface of the outer fold, whereas positive signals for Typ-2 were mainly localized in the outer surface of the outer fold. In the embryos and larvae, the high expression of Tyr mRNA was detected in eyed-larvae, while Typ-2 mRNA was mainly expressed at the trochophore and early D-veliger. Furthermore, the tyrosinase activity in the edge mantle was significantly higher than that in the central mantle. These findings indicated that Tyr gene may be involved in shell pigmentation, and Typ-2 is more likely to play critical roles not only in the formation of shell prismatic layer but also in shell pigmentation. In particular, Typ-2 gene was likely to involve in the initial non-calcified shell of trochophores. The work provides valuable information for the molecular mechanism study of shell formation and pigmentation in C. gigas.

A Genome-Wide Association Study Identifies Candidate Genes Associated With Shell Color in Bay Scallop Argopecten irradians irradians

Molluscan shell color has consistently drawn attention for its abundant diversity and commercial use in shellfish breeding projects. Recently, two new strains of bay scallop (Argopecten irradians irradians) with different shell colors as marked phenotypic traits have been artificially bred to improve their economic values; however, the inheritance mechanism of their shell pigmentation is still unclear. In this study, a genome-wide association study (GWAS) was conducted to determine the genetic basis of shell color in bay scallops utilizing 29,036 high-quality single-nucleotide polymorphisms (SNPs) derived from 80 purple-red (PP) and 80 black-brown (BP) shell color individuals. The result of the GWAS showed that 469 SNPs (p <1.72E−6) significantly associated with shell color were mainly distributed in chromosome 7. The top three SNPs (i.e., chr7-12764003, chr7-13213864, and chr7-11899306) are located in the genic region of G-protein-coupled receptor-like 101 (GRL101), polyketide synthase 1 (PKS1), and phosphoinositide phospholipase C (PLC1), which have been widely reported to be involved in pigmentation. Successfully, the top three SNPs were verified in another non-breeding bay scallop population. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses obtained 38 GO terms covering 297 genes and aggregating pathways involving 252 annotated genes. Specifically, the expression profiles of the top three identified candidate genes were detected in mantles of PP and BP individuals by real-time quantitative reverse transcription PCR. The significantly higher expression levels of GRL101 (6.43-fold) and PLC1 (6.48-fold) in PP, and PKS1 (12.02-fold) in BP implied that GRL101 and PLC1 potentially functioned in PP shell coloration, and black pigmentation in BP might be principally regulated by PKS1. Our data provide valuable information for deciphering the phenotype differences of shell color in the bay scallop.

Identification and characterization of key haem pathway genes associated with the synthesis of porphyrin in Pacific oyster (Crassostrea gigas).

Molluscs exhibit diverse shell colors. The molecular regulation of shell coloration is however not well understood. To investigate the connection of shell coloration with pigment synthesis, we analyzed the distribution of porphyrins, a widespread group of pigments in nature, in four Pacific oyster strains of different shell colors including black, orange, golden, and white. The porphyrin distribution was analyzed in oyster mantles and shells by fluorescence imaging and UV spectrophotometer. The results showed that red fluorescence emitted by porphyrins under the UV light was detected only on the nacre of the orange-shell strain and mantles of orange, black and white-shell strains. Extracts from newly deposit shell, nacre and mantle tissue from orange-shell specimens showed peaks in UV-vis spectra that are characteristic of porphyrins, but these were not observed for the other shell-color strains. In addition, genes of the haem synthetic pathway were isolated and characterized. Phylogenetic analysis of CgALAS, CgALAD, CgPBGD, CgUROS, and CgUROD provide further evidence for a conserved genetic pathway of haem synthesis during evolution. Differential expression of the haem genes expressed in mantle tissues support these findings and are consistent with porphyrins being produced by the orange strain only. Tissue in situ hybridization demonstrated the expression of these candidate genes at the outer fold of C. gigas mantles where shell is deposited. Our studies provide a better understanding of shell pigmentation in C. gigas and candidate genes for future mechanistic analysis of shell color formation in molluscs.

A State-of-the-Art Review on Core–Shell Pigments Nanostructure Preparation and Test Methods

Uses of novel technologies for improving the durability and lifespan of the construction materials have emerged as viable solutions toward the sustainable future wherein the coating industry plays a significant role in economy growth and better livelihoods. Thus, the continual innovation of various technologies to introduce diverse market products has become indispensable. Properties of materials like color stability under UV, elevated temperatures and aggressive environments, and skid and abrasion resistance are the main challenges faced by commercial coating materials, leading to more demand of natural materials as sustainable agents. Lately, nanostructured core–shell pigments with unique compositions have widely been utilized in composite materials to enhance their properties. Core–shell particles exhibit smart properties and have immense benefits when combined with building materials. Based on these facts, we comprehensively overviewed the state-of-the-art research of core–shell nanomaterials in terms of their preparation and performance evaluation methods, as well as feasible applications. The first part of this article discusses effective shell materials, including most common silica and titanium oxides. In addition, nanotechnology enabling the production and patterning of low-dimensional materials for widespread applications is emphasized. The second part deals with various potential core materials used to achieve core–shell nanostructures. The third part of this paper highlights some interesting mechanisms of core–shell structures in the modified systems that display high stability, durability, efficiency, and eco-friendliness. Finally, different applications of these core–shell nanostructures are underscored together with their test methods to evaluate their performances.

Inorganic Mn-Based Core–Shell Pigments by Solution-Combustion Synthesis with Citric Acid as a Fuel

Inorganic Mn-Based Core–Shell Pigments by Solution-Combustion Synthesis with Citric Acid as a Fuel

Experimental simulation of environmental warming selects against pigmented morphs of land snails.

In terrestrial snails, thermal selection acts on shell coloration. However, the biological relevance of small differences in the intensity of shell pigmentation and the associated thermodynamic, physiological, and evolutionary consequences for snail diversity within the course of environmental warming are still insufficiently understood. To relate temperature‐driven internal heating, protein and membrane integrity impairment, escape behavior, place of residence selection, water loss, and mortality, we used experimentally warmed open‐top chambers and field observations with a total of >11,000 naturally or experimentally colored individuals of the highly polymorphic species Theba pisana (O.F. MÜller, 1774). We show that solar radiation in their natural Mediterranean habitat in Southern France poses intensifying thermal stress on increasingly pigmented snails that cannot be compensated for by behavioral responses. Individuals of all morphs acted neither jointly nor actively competed in climbing behavior, but acted similarly regardless of neighbor pigmentation intensity. Consequently, dark morphs progressively suffered from high internal temperatures, oxidative stress, and a breakdown of the chaperone system. Concomitant with increasing water loss, mortality increased with more intense pigmentation under simulated global warming conditions. In parallel with an increase in mean ambient temperature of 1.34°C over the past 30 years, the mortality rate of pigmented individuals in the field is, currently, about 50% higher than that of white morphs. A further increase of 1.12°C, as experimentally simulated in our study, would elevate this rate by another 26%. For 34 T. pisana populations from locations that are up to 2.7°C warmer than our experimental site, we show that both the frequency of pigmented morphs and overall pigmentation intensity decrease with an increase in average summer temperatures. We therefore predict a continuing strong decline in the frequency of pigmented morphs and a decrease in overall pigmentation intensity with ongoing global change in areas with strong solar radiation.

Effect of the pigmentation, shine, weight, and shape index of the quail egg (Coturnix coturnix japonica) on the hatchability rate.

Objective:The influence of the degree of pigmentation, shine, weight, and form index on the hatchability rate of quail eggs (Coturnix coturnix japonica) was examined.Materials and Methods:Three thousand three hundred eggs were incubated after they were classified according to the degree of shell pigmentation: high (HP), medium (MP), and low (LP); shell shine: shiny (SS), and opaque; Egg weight: <11, 11.0–11.9, 12.0–12.9, and >13 gm; form index: <78% and >78%. The Mann–Whitney non-parametric test for independent samples was used to evaluate hatching data.Results:Hatchability was best in eggs with HP and SS (p < 0.05): 69.2% and 75.7%, respectively; eggs with MP had the lowest hatchability rate (63.1%). The highest risk of embryo death (17.8%) was observed in eggs containing LP (p < 0.05). Eggs weighing between 12 and 12.9 gm had the highest hatchability rate (p < 0.05) (79.11%). Eggs with a form index >78% had the highest hatchability rate (p < 0.05) (67.62%).Conclusions:HP, MP shell eggs, and SS eggs with a weight of between 12.0 and 12.9 gm and a shape index of greater than 78% have a higher hatchability rate.

Integrated analysis of microRNA and mRNA expression profiles in Crassostrea gigas to reveal functional miRNA and miRNA-targets regulating shell pigmentation

MicroRNAs (miRNAs) regulate post-transcription gene expression by targeting genes and play crucial roles in diverse biological processes involving body color formation. However, miRNAs and miRNA-targets underlying shell color polymorphism remain largely unknown in mollusca. Using four shell colors full-sib families of the Pacific oyster Crassostrea gigas, we systematically identified miRNAs and miRNA-targets in the mantles, which organ could produce white, golden, black or partially pigmented shell. RNA sequencing and analysis identified a total of 53 known miRNA and 91 novel miRNAs, 47 of which were detected to differentially express among six pairwise groups. By integrating miRNA and mRNA expression profiles, a total of 870 genes were predicted as targets of differentially expressed miRNAs, mainly involving in biomineralization and pigmentation through functional enrichment. Furthermore, a total of four miRNAs and their target mRNAs were predicted to involve in synthesis of melanin, carotenoid or tetrapyrrole. Of them, lgi-miR-317 and its targets peroxidase and lncRNA TCONS_00951105 are implicated in acting as the competing endogenous RNA to regulate melanogenesis. Our studies revealed the systematic characterization of miRNAs profiles expressed in oyster mantle, which might facilitate understanding the intricate molecular regulation of shell color polymorphism and provide new insights into breeding research in oyster.

Genome-wide identification, characterisation and expression analysis of the ALAS gene in the Yesso scallop (Patinopecten yessoensis) with different shell colours.

Porphyrins, one of the most common shell pigments, are by-products of the haem pathway. 5-Aminolaevulinate synthase (ALAS) is the first and rate-limiting enzyme in this pathway and has been well studied in vertebrate species. However, the function of ALAS in shell colouration has been poorly studied in molluscs, which are renowned for their colourful shells. In the present study, an ALAS gene, named PyALAS, was identified through whole-genome scanning in the Yesso scallop (Patinopecten yessoensis), an economically and evolutionarily important bivalve species in which the shell colour represents polymorphism. Two conserved domains were detected in the PyALAS protein sequence, including a Preseq-ALAS domain and a 5-ALAS domain, confirming the identification of PyALAS. Phylogenetic analysis of the ALAS proteins among various invertebrate and vertebrate species revealed a high consistency between the molecular evolution of ALAS and the species taxonomy. PyALAS was ubiquitously expressed in most adult tissues of the Yesso scallop. The left mantle expressed a significantly higher level of PyALAS than the right side in brown scallops, whereas there was no significant difference in white scallops. Significantly different expression levels of PyALAS was also detected between the two different shell colour strains. These data indicate that PyALAS plays an important role in shell colouration in Yesso scallops and the present study provides new insights into the molecular mechanism of shell colouration in molluscs.

Influence of Anticorrosive Coatings Integrated with Novel Core–Shell Pigment on the Corrosion Protection of Pipelines in CO2 Environment

Interior corrosion of pipelines is a major and costly problem encountered in the oil and gas industry. Regarding this problem, coating systems based on waterborne and solvent-based binders integrated with novel core–shell pigment are formulated to maintain excellent mechanical and corrosion resistance. The novel pigment was synthesized using core–shell technique by precipitating layer of zinc and cobalt oxides on the surface of aluminum foil waste. Mechanical testing and electrochemical studies of coatings demonstrated that the integration of polyurethane and acrylic emulsion with the core–shell pigment can enhance the mechanical and corrosion resistivity. The results obtained in this work can be onset to the future use of treated wastes to enhance coating systems for corrosion protection purposes.

Chemical evidence of rare porphyrins in purple shells of Crassostrea gigas oyster

The colour of oyster shells is a very diverse characteristic morphotype, forming intriguing vivid patterns both on the inside and outside of the shell. In the present study, we have identified for the first time, the presence of several porphyrins as constituents of the shell pigmentation of the Crassostrea gigas oyster consumed worldwide. The precise molecular structures of halochromic, fluorescent and acid-soluble porphyrins, such as uroporphyrin and turacin, are unambiguously determined by reverse phase liquid chromatography combined with high resolution mass spectrometry. Their presence account for the purple colouration of shells but also for the dark colouration of adductor muscle scars. We have also defined the endogenous origin of these porphyrins, specifically secreted or accumulated by the shell forming tissue. These findings are pioneering analytical proofs of the existence of the haem pathway in the edible oyster Crassostrea gigas, evidenced by the chemical identification of haem side-products and supported by the recent publication of the corresponding oyster genome.