Melanin Pathway Research Articles

The risk of inbreeding versus outbreeding depression in managing an endangered and locally adapted population of a sedentary bird

AbstractA debate in conservation genomics centers on whether to conserve small, fragmented populations independently or blend them through translocations from larger populations. Translocations of red grouse (Lagopus scotica) from Great Britain to supplement the Irish population have been suggested. We incorporate a variety of genetic datasets to address this. We used genome wide data from 23 contemporary and historic red grouse from Great Britain and Ireland. We also investigate microsatellite data, sequence candidate pigmentation genes, and assess phenotypic color variation. Genomic data indicate higher inbreeding in Irish grouse relative to an English population and significant divergence for genomic (FST = 0.095) and microsatellite (FST = 0.03) markers. Contemporary Ne was seven times smaller in the Irish population compared to the English. We identified divergent regions linked to pigmentation, immune response, and food intake. We show phenotypic differences in plumage color and sequence divergence among coding regions in the melanin pathway including MC1R (FST from genomic data of 0.3). The two populations thus appear locally adapted and this divergence between the source and target population when used for conservation translocations can swamp locally adapted alleles and/or introduce maladapted genotypes, leading to outbreeding depression. While it is important to avoid inbreeding by sustaining larger populations, our research emphasizes the need for practitioners to consider population divergence and local adaptation. We advocate against translocations between Ireland and Britain as a conservation strategy in this particular case and underscore the importance of prioritizing local populations where possible.

Engineering the by-products pathway in Aureobasidium pullulans for highly purified polymalic acid fermentation with concurrent recovery of l-malic acid

The fermentation of polymalic acid (PMA) by Aureobasidium pullulans, followed by acid hydrolysis to release the monomer l-malic acid (l-MA), has emerged as a promising process for the bio-based production of l-MA. However, the presence of specific by-products significantly affects the quality of the final products. In this study, chassis strains harboring an overexpressed endogenous malate dehydrogenase gene (ApMDH2) were engineered to delete key genes involved in the pullulan, melanin, and liamocin biosynthetic pathways. Furthermore, to enhance PMA synthesis productivity and prevent intracellular NADPH accumulation, an irreversible trans-hydrogenase transformation system was designed to efficiently convert NADPH to NADH. In fed-batch fermentation, the engineered strain produced the highest PMA titer (194.3 ± 1.1 g/L) and l-MA yield (0.89 ± 0.01 g/g) with an increased productivity (1.45 ± 0.06 g/L∙h). Moreover, a total of 86.19 % l-MA, with a purity of 99.7 %, was successfully extracted from fermentation broth.

The divergence of DHN-derived melanin pathways in Metarhizium robertsii.

The important role of dihydroxynaphthalene-(DHN) melanin in enhancing fungal stress resistance and its importance in fungal development and pathogenicity are well-established. This melanin also aids biocontrol fungi in surviving in the environment and effectively infecting insects. However, the biosynthetic origin of melanin in the biocontrol agents, Metarhizium spp., has remained elusive due to the complexity resulting from the divergence of two DHN-like biosynthetic pathways. Through the heterologous expression of biosynthetic enzymes from these two pathways in baker's yeast Saccharomyces cerevisiae, we have confirmed the presence of DHN biosynthesis in M. roberstii, and discovered a novel naphthopyrone intermediate, 8, that can produce a different type of pigment. These two pigment biosynthetic pathways differ in terms of polyketide intermediate structures and subsequent modification steps. Stress resistance studies using recombinant yeast cells have demonstrated that both DHN and its intermediates confer resistance against UV light prior to polymerization; a similar result was observed for its naphthopyrone counterpart. This study contributes to the understanding of the intricate and diverse biosynthetic mechanisms of fungal melanin and has the potential to enhance the application efficiency of biocontrol fungi such as Metarhizium spp. in agriculture.

Tyrosinase inhibition prevents non-coplanar polychlorinated biphenyls and polybrominated diphenyl ethers-induced hyperactivity in developing zebrafish: Interaction between pigmentation and neurobehavior

Non-coplanar polychlorinated biphenyl (PCB) mixture Aroclor 1254 and polybrominated diphenyl ether (PBDE) BDE-47 are known to impede neurogenesis and neuronal development. We previously reported that exposure to PCB and PBDE leads to increased embryonic movement in zebrafish by decreasing dopamine levels. In this study, we studied the connection between the melanin and dopamine synthesis pathways in this context. Both genetic and chemical inhibition of tyrosinase, the rate-limiting enzyme in melanin synthesis, not only led to reduced pigmentation but also inhibit PCB/PBDE-induced embryonic hyperactivity. Furthermore, PCB and PBDE rarely affected tyrosinase expression in the potential pigment cells, suggesting that these compounds reduce dopamine through enzymatic regulation, including a competitive interaction for the substrate tyrosine. Our results provide new insights into the interactions between melanogenesis and dopaminergic neuronal activity, which may contribute to understanding the mechanisms underlying PCB/PBDE toxicity in developing organisms.

Tebentafusp Induces a T-Cell–Driven Rash in Melanocyte-Bearing Skin as an Adverse Event Consistent with the Mechanism of Action

Tebentafusp is a gp100xCD3 bispecific ImmTAC designed to redirect polyclonal T cells against cells presenting the melanocyte lineage specific antigen gp100 on HLA-A*02:01. Skin-related adverse events, predominantly rash, are frequent and occur within a few hours after initial infusions, yet the mechanisms are unknown. Here we analysed clinical data from the randomised phase 3 trial (NCT03070392) of tebentafusp (n=252) versus investigator's choice (n=126). Translational analyses were performed on paired on-treatment skin samples from 19 patients collected in the phase 1 trial (NCT01211262). Our analyses showed that rash is a clinical manifestation of tebentafusp-induced recruitment of T cells to cutaneous melanocytes. Development of rash depended on baseline expression levels of gp100 and other melanin pathway genes in the skin. On treatment, melanocyte number was reduced and expression of melanocytic genes decreased, while gene expression related to immunity and cytokine signalling increased. When adjusted for baseline prognostic features, patients with rash within the first week of tebentafusp treatment had the same overall survival compared to patients without a rash in the phase 3 randomized trial IMCgp100-202 (HR 0.84; 95% CI 0.53-1.32). In summary, skin rash is an off-tumour, on-target effect of tebentafusp against gp100+ melanocytes, in line with the mechanism of action.

Integrating Skincare into Medical Practice.

The integration of skincare into medical practice can enhance patient care. Understanding the anatomy and physiology of the skin is the foundation for effective skincare interventions. Genetic and inflammatory conditions play a significant role in aesthetic skin physiology. There are key active ingredients that are pivotal in addressing various skin concerns. Sunscreens provide crucial protection against UV radiation, while pigment control agents such as hydroquinone, kojic acid, and arbutin target the melanin pathway. Exfoliating agents and skin turnover enhancers such as retinoids and hydroxy acids promote skin renewal and rejuvenation. In addition, ingredients such as hyaluronic acid, ceramides, niacinamide, antioxidants, peptides, and botanicals contribute to improving skin quality. Adding skincare to medical practice requires careful product selection, patient education, and marketing strategies.

ZnO nanoparticles: A key ingredient of sunscreen shows absence of adverse effects on Drosophila melanization pathway

The rapid development of zinc oxide nanoparticle (ZnO NP) based sunscreens, shampoos and other skin care products has raised a concern about their safety at the cellular level. The melanization pathway, being an important pathway of skin cells, is prone to being affected by ZnO NPs. Therefore it is necessary to understand the ZnO NP mediated effect on the melanin synthetic pathway. Our previous study on bulk zinc oxide has shown that large sized zinc oxide particles did not have any adverse effect on melanization in Drosophila, hence it would be interesting to study the behavior of ZnO when present in the nano-form by virtue of the changed size and thereby changed properties. The present study was undertaken to investigate ZnO NP mediated effects on key metabolites of the Drosophila melanin pathway. Spectrophotometric analysis of melanin was performed. followed by a study of the enzyme activity of phenol oxidase and HPLC quantification of dopa and tyrosine. FTIR spectroscopy was carried out to examine the interaction of the ZnO NPs and precursor amines of the melanin synthetic pathway. Pigmentation mutants of Drosophila were also investigated for validation of the results under a different genetic background. The ZnO NPs did not show any decrement in the levels of melanin after the treatment. Moreover there was no adverse effect on the phenol oxidase activity, Tyrosine and L-Dopa. The FTIR studies showed minimal interaction between the ZnO NPs and the metabolites of the melanin pathway. The results of the present study have clearly indicated the absence of any adverse effects on key metabolites of the melanin pathway after ZnO NP treatment in both wild-type and mutant Drosophila. This is the first report of a detailed analysis of ZnO NP mediated effects on key constituents of the Drosophila melanization pathway, providing information about its safety for the usage in cosmetics.

Comprehensive analysis of differentially expressed mRNA, lncRNA and miRNA, and their ceRNA networks in the regulation of shell color in the Manila clam (Ruditapes philippinarum)

The regulatory mechanism of ceRNA network plays an important role in molecular function and biological processes, however, the molecular mechanism in the shell color of Ruditapes philippinarum has not yet been reported. In this study, we performed transcriptome sequencing on the mantle of R. philippinarum with different shell colors, and screened for mRNA, miRNA, and lncRNA. A total of 61 mRNAs, 3725 lncRNAs and 90 miRNAs were obtained from all the shell color comparison groups (all mRNAs, lncRNAs and miRNAs P < 0.05), and 7 mRNAs, 8 lncRNAs, and 4 miRNAs of the porphyrin pathway and melanin pathway were screened for competitive endogenous RNA (ceRNA) network construction. The results indicate that the ceRNA network composed of mRNA and lncRNA, centered around efu-miR-101, mle-bantam-3p, egr-miR-9-5p, and sma-miR-75p, may play a crucial regulatory role in shell color formation. This study reveals for the first time the mechanism of ceRNA regulatory networks in the shell color of R. philippinarum and providing important reference data for molecular breeding of shell color in R. philippinarum.

Two zinc finger proteins, VdZFP1 and VdZFP2, interact with VdCmr1 to promote melanized microsclerotia development and stress tolerance in Verticillium dahliae

BackgroundMelanin plays important roles in morphological development, survival, host–pathogen interactions and in the virulence of phytopathogenic fungi. In Verticillum dahliae, increases in melanin are recognized as markers of maturation of microsclerotia which ensures the long-term survival and stress tolerance, while decreases in melanin are correlated with increased hyphal growth in the host. The conserved upstream components of the VdCmr1-regulated pathway controlling melanin production in V. dahliae have been extensively identified, but the direct activators of this pathway are still unclear.ResultsWe identified two genes encoding conserved C2H2-type zinc finger proteins VdZFP1 and VdZFP2 adjacent to VdPKS9, a gene encoding a negative regulator of both melanin biosynthesis and microsclerotia formation in V. dahliae. Both VdZFP1 and VdZFP2 were induced during microsclerotia development and were involved in melanin deposition. Their localization changed from cytoplasmic to nuclear in response to osmotic pressure. VdZFP1 and VdZFP2 act as modulators of microsclerotia melanization in V. dahliae, as confirmed by melanin biosynthesis inhibition and supplementation with the melanin pathway intermediate scytalone in albino strains. The results indicate that VdZFP1 and VdZFP2 participate in melanin biosynthesis by positively regulating VdCmr1. Based on the results obtained with yeast one- and two-hybrid (Y1H and Y2H) and bimolecular fluorescence complementation (BiFC) systems, we determined the melanin biosynthesis relies on the direct interactions among VdZFP1, VdZFP2 and VdCmr1, and these interactions occur on the cell walls of microsclerotia. Additionally, VdZFP1 and/or VdZFP2 mutants displayed increased sensitivity to stress factors rather than alterations in pathogenicity, reflecting the importance of melanin in stress tolerance of V. dahliae.ConclusionsOur results revealed that VdZFP1 and VdZFP2 positively regulate VdCmr1 to promote melanin deposition during microsclerotia development, providing novel insight into the regulation of melanin biosynthesis in V. dahliae.

Metabolome and Transcriptome Association Analysis Reveals the Link Between Pigmentation and Nutrition Utilization in the Juveniles of Sea Cucumber Holothuria leucospilota.

The sea cucumber Holothuria leucospilota is an economically and ecologically important tropical species. Following development into juveniles, H. leucospilota undergoes a color change from white to black, involving a pigmentation process for over a period of several months. In this study, a combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and Next-Generation sequencing (NGS) were employed to investigate the changes in metabolomic and transcriptomic profiles during pigmentation in H. leucospilota juveniles. The metabolomic analysis identified a total of 341 metabolites, of which 52 were found to be differentially regulated (P < 0.05 and VIP > 1), with 27 being upregulated in white individuals and 25 in black individuals. Additionally, 632 differentially expressed genes (DEGs) were identified, with 380 genes upregulated in white samples and 252 genes upregulated in black samples. Interestingly, the melanin content and tyrosinase transcript levels did not display significant differences between the two groups. Metabolomic data suggested the involvement of the linoleic acid metabolic pathway in pigmentation. Transcriptomic analysis, coupled with realtime PCR validation, revealed a decrease in the transcript levels of digestive enzymes like α-amylase, maltase-glucoamylase, and trehalase after the juveniles changed to black. Furthermore, the mRNA expressions of major yolk proteins showed a decline, indicating a shift in the accumulation of protein nutrient sources. Overall, our findings suggest that during the pigmentation process in H. leucospilota, no significant changes were observed in the classical melanin pathway, while notable alterations were observed in their nutritional status. This study provides valuable insights into the regulatory mechanisms of pigmentation in marine organisms.

Melanogenesis Is Directly Affected by Metabolites of Melatonin in Human Melanoma Cells.

Melatonin (N-acetyl-5-methoxytryptamine, MEL), its kynurenic (N1-acetyl-N2-formyl-5-methoxykynurenine, AFMK) and indolic derivatives (6-hydroxymelatonin, 6(OH)MEL and 5-methoxytryptamine, 5-MT) are endogenously produced in human epidermis. Melatonin, produced by the pineal gland, brain and peripheral organs, displays a diversity of physiological functions including anti-inflammatory, immunomodulatory, and anti-tumor capacities. Herein, we assessed their regulatory effect on melanogenesis using amelanotic (A375, Sk-Mel-28) and highly pigmented (MNT-1, melanotic) human melanoma cell lines. We discovered that subjected compounds decrease the downstream pathway of melanin synthesis by causing a significant drop of cyclic adenosine monophosphate (cAMP) level, the microphthalmia-associated transcription factor (MITF) and resultant collapse of tyrosinase (TYR) activity, and melanin content comparatively to N-phenylthiourea (PTU, a positive control). We observed a reduction in pigment in melanosomes visualized by the transmission electron microscopy. Finally, we assessed the role of G-protein-coupled seven-transmembrane-domain receptors. Obtained results revealed that nonselective MT1 and MT2 receptor antagonist (luzindole) or selective MT2 receptor antagonist (4-P-PDOT) did not affect dysregulation of the melanin pathway indicating a receptor-independent mechanism. Our findings, together with the current state of the art, provide a convenient experimental model to study the complex relationship between metabolites of melatonin and the control of pigmentation serving as a future and rationale strategy for targeted therapies of melanoma-affected patients.

Transcriptional profiling of pigmentation-regulated long non-coding RNAs in the mantle of Manila clam (Ruditapes philippinarum)

Long non-coding RNAs (lncRNAs) play important roles in a variety of biological processes and have received extensive attention in recent years. However, the expression and roles of lncRNAs in the Manila clam (Ruditapes philippinarum) are still poorly understood. In this study, we identified lncRNAs in the mantle of clams with different shell colors (orange (O), zebra (Z), white (W), and white zebra (WZ)). Using poly(A)-independent and strand-specific RNA-seq, we obtained 183,818,4888 clean reads and 32,541 lncRNA transcripts. In total, 1988 lncRNAs were identified as differentially expressed lncRNAs in comparisons between six pairs of groups. Fourteen mRNAs and their target genes were found to be related to the shell color pathway of melanin and porphyrin metabolism. Protein kinase C, calmodulin, melanogenesis associated transcription factor, peroxidase-like protein, tyrosine decarboxylase, myeloperoxidase, putativetyrosinase-like protein tyr-3, dopamine beta-hydroxylase, 5-aminolevulinate synthase, tyrosine aminotransferase, uroporphyrinogen-III synthase, hephaestin, delta-aminolevulinic acid dehydratase and ferrochelatase and their corresponding 77 cis-acting lncRNAs are thought to play important roles in the melanin synthesis pathway and porphyrin metabolic pathway. This study identified the catalog of lncRNAs expressed in the mantle of Manila clam, and the results provide insights into understanding the molecular regulation of shell color and genetic breeding in R. philippinarum.

Differential gene expression patterns between the head and thorax of Gynaephora aureata are associated with high-altitude adaptation.

Grassland caterpillars (Lepidoptera: Erebidae: Gynaephora) are important pests in alpine meadows of the Qinghai-Tibetan Plateau (QTP). These pests have morphological, behavioral, and genetic adaptations for survival in high-altitude environments. However, mechanisms underlying high-altitude adaptation in QTP Gynaephora species remain largely unknown. Here, we performed a comparative analysis of the head and thorax transcriptomes of G. aureata to explore the genetic basis of high-altitude adaptation. We detected 8,736 significantly differentially expressed genes (sDEGs) between the head and thorax, including genes related to carbohydrate metabolism, lipid metabolism, epidermal proteins, and detoxification. These sDEGs were significantly enriched in 312 Gene Ontology terms and 16 KEGG pathways. We identified 73 pigment-associated genes, including 8 rhodopsin-associated genes, 19 ommochrome-associated genes, 1 pteridine-associated gene, 37 melanin-associated genes, and 12 heme-associated genes. These pigment-associated genes were related to the formation of the red head and black thorax of G. aureata. A key gene, yellow-h, in the melanin pathway was significantly upregulated in the thorax, suggesting that it is related to the formation of the black body and contributed to the adaptation of G. aureata to low temperatures and high ultraviolet radiation in the QTP. Another key gene, cardinal, in the ommochrome pathway was significantly upregulated in the head and may be related to red warning color formation. We also identified 107 olfactory-related genes in G. aureata, including genes encoding 29 odorant-binding proteins, 16 chemosensory proteins, 22 odorant receptor proteins, 14 ionotropic receptors, 12 gustatory receptors, 12 odorant degrading enzymes, and 2 sensory neuron membrane proteins. Diversification of olfactory-related genes may be associated with the feeding habits of G. aureata, including larvae dispersal and searching for plant resources available in the QTP. These results provide new insights into high-altitude adaptation of Gynaephora in the QTP and may contribute to the development of new control strategies for these pests.

CRISPR/Cas9-Mediated genomic knock out of tyrosine hydroxylase and yellow genes in cricket Gryllus bimaculatus.

Gryllus bimaculatus is an emerging model organism in various fields of biology such as behavior, neurology, physiology and genetics. Recently, application of reverse genetics provides an opportunity of understanding the functional genomics and manipulating gene regulation networks with specific physiological response in G. bimaculatus. By using CRISPR/Cas9 system in G. bimaculatus, we present an efficient knockdown of Tyrosine hydroxylase (TH) and yellow-y, which are involved in insect melanin and catecholamine-biosynthesis pathway. As an enzyme catalyzing the conversion of tyrosine to 3,4-dihydroxyphenylalanine, TH confines the first step reaction in the pathway. Yellow protein (dopachrome conversion enzyme, DCE) is also involved in the melanin biosynthetic pathway. The regulation system and molecular mechanism of melanin biogenesis in the pigmentation and their physiological functions in G. bimaculatus hasn't been well defined by far for lacking of in vivo models. Deletion and insertion of nucleotides in target sites of both TH and Yellow are detected in both F0 individuals and the inheritable F1 progenies. We confirm that TH and yellow-y are down-regulated in mutants by quantitative real-time PCR analysis. Compared with the control group, mutations of TH and yellow-y genes result in defects in pigmentation. Most F0 nymphs with mutations of TH gene die by the first instar, and the only adult had significant defects in the wings and legs. However, we could not get any homozygotes of TH mutants for all the F2 die by the first instar. Therefore, TH gene is very important for the growth and development of G. bimaculatus. When the yellow-y gene is knocked out, 71.43% of G. bimaculatus are light brown, with a slight mosaic on the abdomen. The yellow-y gene can be inherited stably through hybridization experiment with no obvious phenotype except lighter cuticular color. The present loss of function study indicates the essential roles of TH and yellow in pigmentation, and TH possesses profound and extensive effects of dopamine synthesis in embryonic development in G. bimaculatus.

New panel of biomarkers to discriminate between amelanotic and melanotic metastatic melanoma.

Melanoma is a form of skin cancer that can rapidly invade distant organs. A distinctive feature of melanomas is their pigmentation status, as melanin is present in most skin melanomas, whilst many metastatic tumors could become amelanotic. Besides the obvious malfunction of the key genes of the melanin pathway, the amelanotic tumors could bear a characteristic molecular signature accounting for their aggressivity. Using mass spectrometry-based proteomics we report here a distinctive panel of biomarkers for amelanotic aggressive melanoma that differ from the less invasive pigmented cells. The developed method allows the label-free quantification of proteins identified by LC-MS/MS analysis. We found a set of proteins comprising AHNAK, MYOF, ANXA1, CAPN2, ASPH, EPHA2, THBS1, TGM2, ACTN4 along with proteins involved in cell adhesion/migration (integrins, PLEC, FSCN1, FN1) that are highly expressed in amelanotic melanoma. Accompanying the down regulation of pigmentation specific proteins such as tyrosinase and TYRP1, these biomarkers are highly specific for a type of highly invasive melanoma. Interestingly, the LC-MS/MS proteomics analysis in hypoxia revealed that the abundance of this specific set of proteins found in normoxia was rather unaltered in these conditions. These biomarkers could therefore predict a metastatic behaviour for the amelanotic cells in the early stages of the tumor development and thus serve in melanoma prognostic. Applying this algorithm to related databases including melanoma samples published by independent laboratories/public databases we confirm the specificity of the newly found signatures. Overall, we begin to unravel the molecular alterations in the amelanotic melanoma and how basic proteomics offers insights into how to assess the clinical, pathological and misdiagnosis differences between the main subtypes of melanoma.

In Vitro Reconstitution of the Melanin Pathway's Catalytic Activities Using Tyrosinase Nanoparticles.

The melanogenesis pathway is characterized by a series of reactions catalyzed by key enzymes, such as tyrosinase (TYR), tyrosinase-related protein 2 (TYRP2), and tyrosinase-related protein 1 (TYRP1), to produce melanin pigment. However, in vitro studies of the catalytic activity were incomplete because of a lack of commercially available enzyme substrates, such as dopachrome. Herein, human recombinant intra-melanosomal domains of key enzymes were produced in Trichoplusia ni (T. ni) larvae and then purified using a combination of chromatography techniques in catalytically active form. Using Michaelis-Menten kinetics, the diphenol oxidase activity of tyrosinase achieved the maximum production of native dopachrome at 10 min of incubation at 37 °C for TYR immobilized to magnetic beads (TYR-MB). The presence of dopachrome was confirmed spectrophotometrically at 475 nm through HPLC analysis and in the TYRP2-catalyzed reaction, yielding 5,6-dihydroxyindole-2-carboxylic acid (DHICA). In the TYRP1-driven oxidation of DHICA, the formation of 5,6-indolequinone-2-carboxylic acid (IQCA) was confirmed at ~560 nm. This is the first in vitro reconstitution of the reactions from the melanogenic pathway based on intra-melanosomal domains. In the future, this approach could be used for quantitative in vitro analysis of the melanin pathway, biochemical effects associated with inherited disease-related mutations, and drug screens.

The pleiotropic effects of melanin loss in cave snails Physella sp.

A traditional explanation for the loss of pigmentation in cave dwellers is the absence of negative selection acting on surface species to remove all albinos from the population. Recently, however, evidence has been accumulating that albinism in the cavefish Astyanax mexicanus has several beneficial pleiotropic effects. Albino cavefish have higher catecholamine levels due to a loss-of-function mutation in the oca2 gene, higher resistance to anesthesia, and sleep less than their pigmented, surface-dwelling conspecifics. All of these traits are beneficial to cavefish, given the scarcity of food and the availability of mates in caves. To understand whether pleiotropy might be a general mechanism for the loss of melanin pigmentation in cave animals, we use Physella sp., a freshwater snail from SW Illinois, USA. Within one cave Physella sp. occurs in several different morphs, ranging from completely albino to fully pigmented individuals. Using melanogenic substrate assay, we demonstrated that the first step of melanin synthesis is blocked in Physella sp. To investigate the pleiotropic effects of this blockade, we tested anesthesia resistance (AR). Similar to A. mexicanus, albino morphs of Physella sp. exhibited higher AR levels compared to pigmented morphs, with AR being controlled by the noradrenergic system in both morphs. AR and the noradrenergic system are linked to melanin synthesis via a common precursor L-tyrosine, which can be redirected between melanin and catecholamine pathways. Using RNA sequencing of albino and pigmented morphs of Physella sp. we aim to gain further insight into other pleiotropic effects of melanin loss. Our results suggest that pleiotropy may be involved in the evolution of albinism in both cave vertebrates and invertebrates.

Nanocomposite packaging materials delay the browning of Agaricus bisporus by modulating the melanin pathway

To elucidate the browning inhibition mechanism of nanocomposite packaging (nano-PM) Agaricus bisporus during cold storage, we analyzed the biophysical and biochemical indices, including substrates, key enzymes, and relative gene expression associated with browning. The results showed that nano-PM could maintain a higher total phenol content and lower flavonoid content of mushrooms throughout the storage period than the commercial polyethylene packaging treatment (control). The activity of phenylalanine ammonia lyase (PAL) and its relative gene expression were inhibited by nano-PM, whereas cinnamic acid-4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL) activities were promoted. Nano-PM promoted the synthesis of γ-L-glutaminyl-4-hydroxybenzene (GHB), tyrosine, and catechol, but inhibited the synthesis of soluble quinone, γ-L-glutaminyl-3,4-dihydroxybenzene (GDHB), and 3,4-dihydroxyphenylalanine (DOPA), which were mainly attributed to polyphenol oxidase (PPO), tyrosinase (TYR), and laccase (LAC) activities as well as gene relative expression at low levels. Nano-PM increased the enzyme activities of the phenylpropanoid pathway by activating their relative gene expression, promoting the accumulation of phenolic substances to enhance the resistance of mushrooms to harsh environments. Additionally, nano-PM inhibited TYR activity to delay the conversion of GHB to GDHB and tyrosine to DOPA, which ultimately reduced melanin formation and delayed mushroom browning, leading to a longer shelf life.

Taxonomy, comparative genomics and evolutionary insights of Penicillium ucsense: a novel species in series Oxalica.

The genomes of two Penicillium strains were sequenced and studied in this study: strain 2HH was isolated from the digestive tract of Anobium punctatum beetle larva in 1979 and the cellulase hypersecretory strain S1M29, derived from strain 2HH by a long-term mutagenesis process. With these data, the strains were reclassified and insight is obtained on molecular features related to cellulase hyperproduction and the albino phenotype of the mutant. Both strains were previously identified as Penicillium echinulatum and this investigation indicated that these should be reclassified. Phylogenetic and phenotype data showed that these strains represent a new Penicillium species in series Oxalica, for which the name Penicillium ucsense is proposed here. Six additional strains (SFC101850, SFCP10873, SFCP10886, SFCP10931, SFCP10932 and SFCP10933) collected from the marine environment in the Republic of Korea were also classified as this species, indicating a worldwide distribution of this new taxon. Compared to the closely related strain Penicillium oxalicum 114-2, the composition of cell wall-associated proteins of P. ucsense 2HH shows five fewer chitinases, considerable differences in the number of proteins related to β-D-glucan metabolism. The genomic comparison of 2HH and S1M29 highlighted single amino-acid substitutions in two major proteins (BGL2 and FlbA) that can be associated with the hyperproduction of cellulases. The study of melanin pathways shows that the S1M29 albino phenotype resulted from a single amino-acid substitution in the enzyme ALB1, a precursor of the 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis. Our study provides important knowledge towards understanding species distribution, molecular mechanisms, melanin production and cell wall biosynthesis of this new Penicillium species.

Identification of genes associated with feather color in Liancheng white duck using FST analysis.

Liancheng white duck has two phenotypic traits: white feather and black beak-black foot, but the genes controlling these phenotypic traits are unknown. The objective of this study is to identify various candidate genes related to the plumage of Liancheng white duck. This study used F2 population construction generated between white Kaiya duck and Liancheng white duck and FST analysis between the dominant and recessive loci associated with the Liancheng white duck white feather in order to identify specific gene regions. As per the feather color statistics of the F2 population, it is estimated that there are about three or four genes controlling the white feather of Liancheng white ducks, and the FST results showed that four significant signals were found on chromosomes 4, 12, 13, and 21. Further annotation of these regions led to the identification of five genes involved in the melanin pathway, namely, KIT, CLOCK, MITF, CEBPA, and DOK5. Among them, CEBPA and DOK5might be affecting the white feather traits of Liancheng white duck by regulating the melanin production and its transfer to the feather. The results provide insightful understanding into the genetic mechanisms of white feather in Liancheng white duck.