Melanin and HIV in sub-Saharan Africa

Melanin in Auricularia auricula: biosynthesis, production, physicochemical characterization, biological functions, and applications

Auricularia auricular (A. auricula), a nutritious fungus and traditional medicinal resource, is known for melanin. This review aims to summarize the research progress on melanin in A. auricula, specifically focusing on biosynthesis, fermentation production, extraction processes, physicochemical characterization, biological functions, and applications. The biosynthesis of melanin in A. auricula primarily involves the oxidative polymerization reaction of phenolic compounds. To enhance melanin production, strategies such as deep fermentation culture, selection of optimal fermentation materials, and optimization of the culture medium have been employed. Various extraction processes have been compared to determine their impact on the physicochemical properties and stability of melanin. Moreover, the antioxidant and antibiofilm activities of A. auricula melanin, as well as its potential beneficial effects on the human body through in vivo experiments, have been investigated. These findings provide valuable insights into the application of A. auricula melanin and serve as a reference for future research in this field.

Graphical abstract

Single-Cell Transcriptome and Pigment Biochemistry Analysis Reveals the Potential for the High Nutritional and Medicinal Value of Purple Sea Cucumbers

The sea cucumber Apostichopus japonicus has important nutritional and medicinal value. Unfortunately, we know little of the source of active chemicals in this animal, but the plentiful pigments of these animals are thought to function in intriguing ways for translation into clinical and food chemistry usage. Here, we found key cell groups with the gene activity predicted for the color morphology of sea cucumber body using single-cell RNA-seq. We refer to these cell populations as melanocytes and quinocytes, which are responsible for the synthesis of melanin and quinone pigments, respectively. We integrated analysis of pigment biochemistry with the transcript profiles to illuminate the molecular mechanisms regulating distinct pigment formation in echinoderms. In concert with the correlated pigment analysis from each color morph, this study expands our understanding of medically important pigment production, as well as the genetic mechanisms for color morphs, and provides deep datasets for exploring advancements in the fields of bioactives and nutraceuticals.

Cecum microbiome and metabolism characteristics of Silky Fowl and White Leghorn chicken in late laying stages

Cecal microflora plays a key role in the production performance and immune function of chickens. White Leghorn (WL) is a well-known commercial layer line chicken with high egg production rate. In contrast, Silky Fowl (SF), a Chinese native chicken variety, has a low egg production rate, but good immune performance. This study analyzed the composition of cecal microbiota, metabolism, and gene expression in intestinal tissue of these varieties and the correlations among them. Significant differences were observed in the cecal microbes: Bacteroides was significantly enriched in WL, whereas Veillonellaceae and Parabacteroides were significantly enriched in SF. Carbohydrate biosynthesis and metabolism pathways were significantly upregulated in WL cecum, which might provide more energy to the host, leading to persistently high levels of egg production. The higher Parabacteroides abundance in SF increased volicitin content, enhanced α-linolenic acid metabolism, and significantly negatively correlated with metabolites of propanoate metabolism and carbohydrate metabolism. Genes related to lipid metabolism, immunity, and melanogenesis were significantly upregulated in the SF cecum, regulating lipid metabolism, and participating in the immune response, while genes related to glucose metabolism and bile acid metabolism were expressed at higher levels in WL, benefiting energy support. This study provided a mechanism for intestinal microorganisms and metabolic pathways to regulate chicken egg-laying performance and immunity.

Characterization of the physicochemical properties, antioxidant activity, and antiproliferative activity of natural melanin from S. reiliana

This study aimed to characterize the physicochemical properties and stability of L-25 melanin extracted from Sporisorium reilianum (S. reiliana). The results showed that the maximum absorption wavelength of melanin was 215 nm. Reducing agents, heat, light, microwaving, oxidants, and common food additives did not affect the melanin. Additionally, it has a good metal stability except Mn²⁺. The IR spectra revealed the presence of O–H, N–H, C=O, and C=C bonds as well as carboxyl, alcohol hydroxyl, and phenolic hydroxyl groups and a pyran ring. L-25 melanin could be defined as DL-hydroxy phenylalanine (DOPA)-melanin. The antioxidant and antiproliferative were also measured. The melanin has a specific stability and high antioxidant activity, including a strong DPPH free radical scavenging ability, and protected damaged HepG2 cells by reducing reactive oxygen species, malondialdehyde, and lactate dehydrogenase content. In conclusion, S. reilianum represents a novel source of melanin, that could be applied to health food or food additives. Our results show that melanin from S. reilianum is a natural pigment with good stability that has a great prospect of development and application, providing a theoretical basis and methods for its further processing and development as a functional food.

De Novo assembly and comparative transcriptome analyses of purple and green morphs of Apostichopus japonicus during body wall pigmentation process

Pigmentation processes provide a traceable and relevant trait for understanding key issues in evolutionary biology such as adaptation, speciation and the maintenance of balanced polymorphisms. The sea cucumber Apostichopus japonicus, which has nutritive and medical properties, is considered the most valuable commercial species in many parts of Asia. Compared with the green morph, the purple morph is rare and has great appeal to consumers. However, little is currently known about the molecular mechanism of body color formation in A. japonicus, even in echinoderm. Here, we employ illumina sequencing to examine expression patterns of the gene network underlying body wall development in purple and green morphs of A. japonicus. Overall, the number of down-regulated genes in the green morph was significantly more than in the purple morph during the pigmentation stage. We observed dynamic expression patterns of a large number of pigment, regulation and growth genes from the "Melanogenesis", "Melanoma", "Wnt signaling pathway", "Notch signaling pathway", "epithelium development", "epidermal growth factor receptor binding","growth factor activity" and "growth", including contrasting expression patterns of these genes in green and purple morph. This study provides comprehensive lists of differentially expressed genes during body wall development in the green and purple morphs, revealing potential candidate genes that may be involved in regulating body color formation and polymorphism. These data will provide valuable information for future genetic studies on sea cucumbers elucidating the molecular mechanisms underlying pigmentation, and may support the culture of desirable color morphs.

Molecular cloning and characterization of the endothelin 3 gene in black bone sheep

Background

Black bone sheep was first discovered in Yunnan province of China in 1970, with unique black pigmentation on the body and internal organs. Endothelin 3 (EDN3) has been known as a key gene causing hyperpigmentation in black bone chicken, the Silky fowl.

Methods

In this study, EDN3 was employed as a candidate gene for regulating black color pigmentation. First, EDN3 was cloned from sheep to obtain the full-length cDNA by using the rapid amplification of cDNA ends (RACE). Genomic EDN3 was screened and a total of thirty predicted single nucleotide polymorphisms (SNPs) were genotyped for allele and genotype frequency analysis in a case-control study involving two black bone sheep populations. Genomic copy number analysis of EDN3 in sheep was conducted to measure the variation in copy number. EDN3 expression levels were observed among the groups in adult liver, lymph node, and kidney tissues, as well as embryo kidney samples. Also, among the tissues of black bone and non-black bone sheep.

Results

The size of the full-length cDNA was 1,578 bp, which included 426 bp of 5′-untranslated region (5′-UTR), an open reading frame (ORF) of 639 bp encoding a protein of 212 amino acids, and a 3′-UTR of 513 bp. Genotype and allele frequencies of all the discovered SNPs were found insignificantly different in black bone and non-black bone sheep (P > 0.05). Genomic copy number analysis of EDN3 in sheep revealed no significant difference between the two sheep groups. No significant variations were found in the adult liver and kidney embryo samples. However, the expression in lymph node and kidney tissue was significantly higher in black bone sheep than that in non-black bone sheep (P < 0.05). Significant variations in the EDN3 expression levels were observed among the tissues of non-black bone sheep.

Conclusions

The findings of the present study indicate that unlike in Silky chickens, EDN3 is not responsible for hyperpigmentation but may play a key functional role in immune and excretory systems of black bone sheep.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0272-y) contains supplementary material, which is available to authorized users.

Molecular cloning and expression analysis of tyr and tyrp1 genes in normal and albino yellow catfish Tachysurus fulvidraco

The full-length complementary DNA of two genes related to vertebrate albinism, the tyrosinase gene tyr and tyrosinase-related protein 1 gene tyrp1, were cloned and analysed from normal and albino yellow catfish Tachysurus fulvidraco. The open reading frames (ORF) of tyr and tyrp1 encode putative peptides of 533 and 526 amino acids (amino-acid), both of which possess two conserved copper binding sites. The homologous identities of deduced amino-acid sequences showed that both Tyr and Tyrp1 of T. fulvidraco share considerable similarity with that of channel catfish Ictalurus punctatus. Both tyr and tyrp1 were expressed in a wide range of adult tissues. Tyr gene had the highest expression level in the brain of both normal and albino T. fulvidraco. Tyrp1 had the highest expression level in the skin of normal groups, and the fin of albino groups. The messenger (m)RNA expressions of tyr and tyrp1 were detectable at different early developmental stages and varied with embryonic and larval growth. Tyr and tyrp1 mRNA have obvious tissue specificity both in normal and albino T. fulvidraco and higher expression levels were detected in the normal group revealing that tyr and tyrp1 may have an important role in pigmentation. These results will provide useful data for understanding the molecular mechanism of melanin formation and the occurrence of albinism in T. fulvidraco.

IBT-based quantitative proteomics identifies potential regulatory proteins involved in pigmentation of purple sea cucumber, Apostichopus japonicus

Sea cucumbers are an important economic species and exhibit high yield value among aquaculture animals. Purple sea cucumbers are very rare and beautiful and have stable hereditary patterns. In this study, isobaric tags (IBT) were first used to reveal the molecular mechanism of pigmentation in the body wall of the purple sea cucumber. We analyzed the proteomes of purple sea cucumber in early pigmentation stage (Pa), mid pigmentation stage (Pb) and late pigmentation stage (Pc), resulting in the identification of 5580 proteins, including 1099 differentially expressed proteins in Pb: Pa and 339 differentially expressed proteins in Pc: Pb. GO and KEGG analyses revealed possible differentially expressed proteins, including"melanogenesis", "melanosome", "melanoma", "pigment-biosynthetic process", "Epidermis development", "Ras-signaling pathway", "Wnt-signaling pathway", "response to UV light", and "tyrosine metabolism", involved in pigment synthesis and regulation in purple sea cucumbers. The large number of differentially expressed proteins identified here should be highly useful in further elucidating the mechanisms underlying pigmentation in sea cucumbers. Furthermore, these results may also provide the base for further identification of proteins involved in resistance mechanisms against melanoma, albinism, UV damage, and other diseases in sea cucumbers.

Antioxidant activity of a Lachnum YM226 melanin-iron complex and its influence on cytokine production in mice with iron deficiency anemia

The present study aims to investigate the protective effects of an orally administered Lachnum YM226 melanin-iron complex (LM-Fe) against iron deficiency anemia (IDA) in mice. The IDA mouse model was established by feeding mice with iron-deficient food. Different doses of LM-Fe were given to the anaemic mice via intragastric administration, with FeCl3 and FeSO4 used as positive controls. After the iron supplement administration, it was observed that LM-Fe could significantly improve the decreased haemoglobin (Hb) level, and normalize the serum iron (SI) level, total iron-binding capacity (TIBC) and serum ferritin (SF) of the anaemic mice in a dose-dependent manner. In addition, treatment with LM-Fe significantly increased the antioxidant enzyme activities of superoxidase dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in plasma to normal or better. Furthermore, the levels of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) were obviously decreased in the LM-Fe supplemented groups compared with the model group, while the level of interleukin-2 (IL-2) was significantly increased. In conclusion, LM-Fe was efficient at ameliorating the anemia symptoms, improving the activities of antioxidant enzymes and adjusting the immune dysfunction of anaemic mice. Thus, these results demonstrated that LM-Fe might be exploited as an efficient and multifunctional iron supplement.

Isolation, purification, and anti-aging activity of melanin from Lachnum singerianum

Intracellular melanin from Lachnum singerianum YM296 (LIM) was obtained by the method of microwave-assisted extraction. On the basis of single factor experiment, the optimum microwave-assisted extraction conditions of LIM using Box-Behnken design were as follows: NaOH concentration, 1.05 mol/L; ratio of raw material to liquid ratio, 1:14.72 (g/mL); microwave time, 118.70 s; and microwave power, 320 W. Under these conditions, the extraction yield of LIM was 11.08 %, and 40.43 % higher than that of extraction by alkali extraction and acid precipitation. The results showed that microwave-assisted extraction could increase the extraction yield of LIM. Three homogeneous components were fractionated from LIM by Sephadex G-15 column. LIM-a was the main homogeneous component, accounting for 75.7 % of the total content of the homogeneous components. Aged mice model were induced by injecting D-galactose, and the aged mice were given LIM-a of different dosages, respectively. The results showed that LIM-a can significantly increase body weight, thymus indexes, and spleen indexes of the aged mice; effectively elevate the levels of SOD, GSH-PX, and CAT; and decrease the level of MDA in mice liver homogenate, brain homogenate, and serum, indicating that LIM-a had significant anti-aging activity.

Parasite prevalence and the worldwide distribution of cognitive ability

In this study, we hypothesize that the worldwide distribution of cognitive ability is determined in part by variation in the intensity of infectious diseases. From an energetics standpoint, a developing human will have difficulty building a brain and fighting off infectious diseases at the same time, as both are very metabolically costly tasks. Using three measures of average national intelligence quotient (IQ), we found that the zero-order correlation between average IQ and parasite stress ranges from r=-0.76 to r=-0.82 (p<0.0001). These correlations are robust worldwide, as well as within five of six world regions. Infectious disease remains the most powerful predictor of average national IQ when temperature, distance from Africa, gross domestic product per capita and several measures of education are controlled for. These findings suggest that the Flynn effect may be caused in part by the decrease in the intensity of infectious diseases as nations develop.

Physiological and genetic characteristics of black-boned sheep (Ovis aries)

Here we report for the first time the discovery of sheep that have black bones and black muscles. The spectral pattern of pigment extracted from tissues of these black-boned sheep is similar to that of black-boned Chinese silky fowl. Additionally, black-boned sheep have significantly higher plasma colour, tyrosinase activity and kidney function than normal sheep. Synonymous nucleotide substitutions in the tyrosinase (TYR) and melanocortin 1 receptor (MC1R) genes were detected in black-boned sheep when compared with the corresponding sequences in normal sheep. In addition, a missense mutation (215T>C) in exon 2 of tyrosinase-related protein 1 (TYRP1) was detected in black-boned sheep, and this resulted in a putative valine-to-alanine substitution at codon 68 (Val68Ala).