Biotin in metabolism and its relationship to human disease

Unlocking the brain's code: The crucial role of post-translational modifications in neurodevelopment and neurological function

Post-translational modifications (PTMs) represent a crucial regulatory mechanism in the brain, influencing various processes, including neurodevelopment and neurological function. This review discusses the effects of PTMs, such as phosphorylation, ubiquitination, acetylation, and glycosylation, on neurodevelopment and central nervous system functionality. Although neurodevelopmental processes linked to PTMs are complex, proteins frequently converge within shared pathways. These pathways encompass neurodevelopmental processes, signaling mechanisms, neuronal migration, and synaptic connection formation, where PTMs act as dynamic regulators, ensuring the precise execution of brain functions. A detailed investigation of the fundamental mechanisms governing these pathways will contribute to a deeper understanding of nervous system functions and facilitate the identification of potential therapeutic targets. A thorough examination of the PTM landscape holds significant potential, not only in advancing knowledge but also in developing treatments for various neurological disorders.

Biotin Mitigates Alcohol Withdrawal-Induced Anxiety and Depression by Regulating Serotonin Metabolism, BDNF, Inflammation, and Oxidative Stress in Rats

INTRODUCTION

Substance use disorders, particularly alcohol use disorders, represent a significant public health problem, with adolescents particularly vulnerable to their adverse effects. This study examined the possible anxiolytic and antidepressant effects of biotin, a crucial vitamin for brain function, in attenuating the behavioral and neurobiological changes associated with alcohol withdrawal in adolescent rats.

MATERIALS AND METHODS

Sixty male Sprague-Dawley rats were exposed to a 20% ethanol solution for 21 days, followed by a 21-day drug-free period to assess long-term behavioral and physiological changes. Behavioral assessments included the Open Field Test, Elevated Plus Maze, and Forced Swimming Test, administered post-withdrawal to evaluate anxiety and depression behaviors. Additionally, biochemical analyses were performed to measure serotonin levels, monoamine oxidase-A (MAO-A) activity, and BDNF concentrations.

RESULTS

The results indicate that ethanol withdrawal significantly induced anxiety- and depression-like behavior in the rats. However, treatment with biotin, particularly at higher doses, effectively attenuated these withdrawal-related behavioral changes. Mechanistically, biotin administration was found to regulate serotonin levels, monoamine oxidase activity, brain-derived neurotrophic factor, and glial fibrillary acidic protein, and alleviate oxidative stress markers in cortical tissue.

DISCUSSION

The results of this study suggest that biotin may have therapeutic potential for alleviating the negative effects of alcohol withdrawal, particularly those related to anxiety and depression. Further research is needed to elucidate the underlying mechanisms and examine the clinical effects of biotin supplementation for individuals undergoing alcohol withdrawal.

The association of gut microbiome composition with musculoskeletal features in middle-aged and older adults: a two-cohort joint study

Background

Bones and muscles are connected anatomically, and functionally. Preliminary evidence has shown the gut microbiome influences the aging process of bone and muscle in animal studies. However, such evidence in humans is still scarce. This study aimed to assess the microbiome-bone and microbiome-muscle associations in two cohorts of community-dwelling older adults.

Methods

We leveraged information from two large population-based cohorts, i.e., the Rotterdam Study (mean age 62.7 ± 5.6 years; n=1,249) and the Framingham Heart Study (mean age 55.2 ± 9.1 years; n=1,227). For individuals included in this study, gut microbiome 16S rRNA sequencing, musculoskeletal phenotyping derived from DXA images, lifestyle and socioeconomic data, and medication records were available. Per cohort, the 16S rRNA sequencing data, derived from stool, were processed with the DADA2 pipeline and taxonomies were assigned using the SILVA reference database. In addition, the microbiome functional potential was obtained with PICRUSt2. Further, we investigated the association between the human gut microbiome (alpha diversity, genera and predicted functional pathways) and appendicular lean mass (ALM), femoral neck bone mineral density (FN-BMD) and trabecular bone score (TBS) using multilinear regression models controlling for multiple confounders, and performed a joint analysis from both cohorts. Sex-stratified analyses were also conducted.

Results

The gut microbiome alpha diversity was not associated with either tested phenotype after accounting for multiple-testing (P>1.67e-02). In the joint analysis, lower abundance of Oscillibacter (beta= -.51, 95%CI [-0.74, -.29]), Anaerotruncus (beta=-0.41, 95%CI [-0.61, - 0.21]), Eisenbergiella (beta=-0.39, 95%CI [-0.59, -.19]) and higher abundance of Agathobacter (beta=0.40, 95%CI [0.20, 0.60]) were associated with higher ALM (P<2.0e-04). Lower abundance of Anaerotruncus (beta=-0.32, 95%CI [-0.45, -.19]), Hungatella (beta=-0.26, 95%CI [-0.38, -.15]) and Clostridiales bacterium DTU089 (beta=-0.37, 95%CI [-0.55, -.19]) was associated with higher ALM only in females (P< 2.0e-04). Moreover, the biotin biosynthesis II pathway was positively associated with ALM (beta=0.44, 95% CI [0.24, 0.64]) (P<1.90e-04) in females while no associations were observed in males. We did not observe any robust association of bone traits with gut microbiome features.

Conclusion

Our results indicate that specific genera are associated with ALM in middle-aged and older adults and these associations can present in a sex-specific manner. Overall, our study suggests that the gut microbiome is linked to muscle aging in middle-aged and older adults. However, larger sample sizes are still needed to underpin the specific microbiome features involved.

Vitamin Bs as Potent Anticancer Agents through MMP-2/9 Regulation

In recent years, the role of coenzymes, particularly those from the vitamin B group in modulating the activity of metalloenzymes has garnered significant attention in cancer treatment strategies. Metalloenzymes play pivotal roles in various cellular processes, including DNA repair, cell signaling, and metabolism, making them promising targets for cancer therapy. This review explores the complex interplay between coenzymes, specifically vitamin Bs, and metalloenzymes in cancer pathogenesis and treatment. Vitamins are an indispensable part of daily life, essential for optimal health and well-being. Beyond their recognized roles as essential nutrients, vitamins have increasingly garnered attention for their multifaceted functions within the machinery of cellular processes. In particular, vitamin Bs have emerged as a pivotal regulator within this intricate network, exerting profound effects on the functionality of metalloenzymes. Their ability to modulate metalloenzymes involved in crucial cellular pathways implicated in cancer progression presents a compelling avenue for therapeutic intervention. Key findings indicate that vitamin Bs can influence the activity and expression of metalloenzymes, thereby affecting processes such as DNA repair and cell signaling, which are critical in cancer development and progression. Understanding the mechanisms by which these coenzymes regulate metalloenzymes holds great promise for developing novel anticancer strategies. This review summarizes current knowledge on the interactions between vitamin Bs and metalloenzymes, highlighting their potential as anticancer agents and paving the way for innovative, cell-targeted cancer treatments.

Changes in blood physiological and biochemical parameters and intestinal flora in newborn horses and mares with angular limb deformities

Introduction

Angular limb deformities (ALDs) are a common skeletal development disorder in newborn foals. This condition affects the growth and development of foals and severely impacts their future athletic performance and economic value, causing significant financial losses to the horse industry. Placentitis, metritis, and severe metabolic diseases during mare pregnancy are significant causes of ALDs in newborn foals. It has been established that intestinal flora disorders can easily lead to inflammatory and metabolic diseases in the host. However, the incidence of ALDs in foals in Zhaosu County, Xinjiang, a key production area of China's horse industry, remains unclear. Additionally, the relationship between functional changes in foals with ALDs and their mares and changes in their intestinal flora is not well-understood.

Methods

This study investigated the status of ALD in newborn foals through clinical observation and imaging examinations. In addition, molecular biological methods were applied to examine the effects of ALDs foals and their mares on physiological and biochemical markers and gut microbiota.

Results

The results showed that the incidence of ALD in Zhaosu area of China was 4.13%. In addition, by comparing and correlating the physiological and biochemical indicators and intestinal flora of foals and mares with ALD with those of healthy horses, it was found that foals and mares with ALD may promote the occurrence and development of the disease through the "blood marker changes-intestinal flora-ALDs" axis. In addition, by comparing the physiological and biochemical indicators and intestinal flora of foals and mares with ALD with the intestinal flora of healthy horses, it was found that the physiological and biochemical indicators and intestinal flora structure and metabolic pathways of foals and mares with ALD had significant changes.

Discussion

The diversity, species composition, and function of the intestinal flora of ALDs and their mares were significantly altered. These findings provide a scientific basis for understanding the etiology of ALDs in foals and offer new perspectives for diagnosing and treatment ALDs in newborn foals.

Structural insights into BirA from Haemophilus influenzae, a bifunctional protein as a biotin protein ligase and a transcriptional repressor

Biotin is an essential coenzyme involved in various metabolic processes across all known organisms, with biotinylation being crucial for the activity of carboxylases. BirA from Haemophilus influenzae is a bifunctional protein that acts as a biotin protein ligase and a transcriptional repressor. This study reveals the crystal structures of Hin BirA in both its apo- and holo-(biotinyl-5'-AMP bound) forms. As a class II BirA, it consists of three domains: N-terminal DNA binding domain, central catalytic domain, and C-terminal SH3-like domain. The structural analysis shows that the biotin-binding loop forms an ordered structure upon biotinyl-5'-AMP binding. This facilitates its interaction with the ligand and promotes protein dimerization. Comparative studies with other BirA homologs from different organisms indicate that the residues responsible for binding biotinyl-5'-AMP are highly conserved. This study also utilized AlphaFold2 to model the potential heterodimeric interaction between Hin BirA and biotin carboxyl carrier protein, thereby providing insights into the structural basis for biotinylation. These findings enhance our understanding of the structural and functional characteristics of Hin BirA, highlighting its potential as a target for novel antibiotics that disrupt the bacterial biotin synthesis pathways.

Fusarium graminearum spores disrupt gut microbiota and metabolome via the lung-gut axis in mice

Fusarium graminearum, the primary pathogen responsible for wheat Fusarium head blight, can induce pulmonary damage through its spores. However, the detailed mechanism by which these spores cause intestinal injury is not yet fully understood. This study aimed to investigate the impact of exposure to fungal spores on the intestinal microbiota using a mice model that mimics the effects of fusarium graminearum spores on the gut microbiota and its metabolic profile. The study utilized 16S rRNA sequencing and metabolomics methodologies to analyze the contents of the cecum and feces in mice. The results showed that exposure to fungal spores led to significant changes in the composition of the intestinal microbiota in mice, characterized by an increase in Akkermansia and Staphylococcus populations. A non-targeted metabolomics analysis identified 316 metabolites associated with various metabolic pathways, particularly galactose metabolism. Pre-exposure to antibiotics before fungal spore exposure resulted in a decrease in the metabolic capacity of the intestinal microbiota in mice. This research demonstrates that fusarium graminearum spores can disrupt the intestinal microbiota and metabolome via the lung-gut axis. These findings provide valuable insights into the intestinal damage caused by fungal spores and offer important support for the development of therapeutic strategies for intestinal diseases.

The Interplay between Liver and Adipose Tissue in the Onset of Liver Diseases: Exploring the Role of Vitamin Deficiency

The deficiency of vitamins, a condition known as "hidden hunger", causes comprehensive pathological states. Research over the years has identified a relationship between liver diseases and hypovitaminosis or defects in vitamin metabolism. The exact mechanisms remain elusive; however, the crucial involvement of specific vitamins in metabolic functions, alongside the reclassification of liver disease as metabolic dysfunction-associated steatotic liver disease (MASLD), has prompted researchers to investigate the potential cause-effect dynamics between vitamin deficiency and liver disease. Moreover, scientists are increasingly investigating how the deficiency of vitamins might disrupt specific organ crosstalk, potentially contributing to liver disease. Although the concept of a dysmetabolic circuit linking adipose tissue and the liver, leading to liver disease, has been discussed, the possible involvement of vitamin deficiency in this axis is a relatively recent area of study, with numerous critical aspects yet to be fully understood. In this review, we examine research from 2019 to July 2024 focusing on the possible link between liver-adipose tissue crosstalk and vitamin deficiency involved in the onset and progression of non-alcoholic fatty liver disease (NAFLD). Studies report that vitamin deficiency can affect the liver-adipose tissue axis, mainly affecting the regulation of systemic energy balance and inflammation.

In Vivo Regulation of Small Molecule Natural Products, Antioxidants, and Nutrients by OAT1 and OAT3

The organic anion transporters OAT1 (SLC22A6) and OAT3 (SLC22A8) are drug transporters that are expressed in the kidney, with well-established roles in the in vivo transport of drugs and endogenous metabolites. A comparatively unexplored potential function of these drug transporters is their contribution to the in vivo regulation of natural products (NPs) and their effects on endogenous metabolism. This is important for the evaluation of potential NP interactions with other compounds at the transporter site. Here, we have analyzed the NPs present in several well-established databases from Asian (Chinese, Indian Ayurvedic) and other traditions. Loss of OAT1 and OAT3 in murine knockouts caused serum alterations of many NPs, including flavonoids, vitamins, and indoles. OAT1- and OAT3-dependent NPs were largely separable based on a multivariate analysis of chemical properties. Direct binding to the transporter was confirmed using in vitro transport assays and protein binding assays. Our in vivo and in vitro results, considered in the context of previous data, demonstrate that OAT1 and OAT3 play a pivotal role in the handling of non-synthetic small molecule natural products, NP-derived antioxidants, phytochemicals, and nutrients (e.g., pantothenic acid, thiamine). As described by remote sensing and signaling theory, drug transporters help regulate redox states by meditating the movement of endogenous antioxidants and nutrients between organs and organisms. Our results demonstrate how dietary antioxidants and other NPs might feed into these inter-organ and inter-organismal pathways.

Biotin Homeostasis and Human Disorders: Recent Findings and Perspectives

Biotin (vitamin B7, or vitamin H) is a water-soluble B-vitamin that functions as a cofactor for carboxylases, i.e., enzymes involved in the cellular metabolism of fatty acids and amino acids and in gluconeogenesis; moreover, as reported, biotin may be involved in gene regulation. Biotin is not synthesized by human cells, but it is found in food and is also produced by intestinal bacteria. Biotin status/homeostasis in human individuals depends on several factors, including efficiency/deficiency of the enzymes involved in biotin recycling within the human organism (biotinidase, holocarboxylase synthetase), and/or effectiveness of intestinal uptake, which is mainly accomplished through the sodium-dependent multivitamin transporter. In the last years, administration of biotin at high/"pharmacological" doses has been proposed to treat specific defects/deficiencies and human disorders, exhibiting mainly neurological and/or dermatological symptoms and including biotinidase deficiency, holocarboxylase synthetase deficiency, and biotin-thiamine-responsive basal ganglia disease. On the other hand, according to warnings of the Food and Drug Administration, USA, high biotin levels can affect clinical biotin-(strept)avidin assays and thus lead to false results during quantification of critical biomarkers. In this review article, recent findings/advancements that may offer new insight in the abovementioned research fields concerning biotin will be presented and briefly discussed.

Design, Synthesis, and Antibacterial Evaluation of Novel Isoindolin-1-ones Derivatives Containing Piperidine Fragments

A series of novel isoindoline-1-one derivatives containing piperidine moiety were designed and synthesized using natural compounds as raw materials, and their biological activities were tested for three bacterial and three fungal pathogens. These derivatives exhibited good against phytopathogenic bacteria activities against Pseudomonas syringae pv actinidiae (Psa) and Xanthomonas axonopodis pv.citri (Xac). Some compounds exhibited excellent antibacterial activities against Xanthomonas oryzae pv oryzae (Xoo). The dose of Y8 against Xoo (the maximum half lethal effective concentration (EC50) = 21.3 μg/mL) was better than that of the thiediazole copper dose (EC50 = 53.3 μg/mL). Excitingly, further studies have shown that the molecular docking of Y8 with 2FBW indicates that it can fully locate the interior of the binding pocket through hydrogen bonding and hydrophobic interactions, thereby enhancing its anti-Xoo activity. Scanning electron microscopy (SEM) studies revealed that Y8 induced the Xoo cell membrane collapse. Moreover, the proteomic results also indicate that Y8 may be a multifunctional candidate as it affects the formation of bacterial Xoo biofilms, thereby exerting antibacterial effects.

An integrated metabo-lipidomics profile of induced sputum for the identification of novel biomarkers in the differential diagnosis of asthma and COPD

BACKGROUND

Due to their complexity and to the presence of common clinical features, differentiation between asthma and chronic obstructive pulmonary disease (COPD) can be a challenging task, complicated in such cases also by asthma-COPD overlap syndrome. The distinct immune/inflammatory and structural substrates of COPD and asthma are responsible for significant differences in the responses to standard pharmacologic treatments. Therefore, an accurate diagnosis is of central relevance to assure the appropriate therapeutic intervention in order to achieve safe and effective patient care. Induced sputum (IS) accurately mirrors inflammation in the airways, providing a more direct picture of lung cell metabolism in comparison to those specimen that reflect analytes in the systemic circulation.

METHODS

An integrated untargeted metabolomics and lipidomics analysis was performed in IS of asthmatic (n = 15) and COPD (n = 22) patients based on Ultra-High-Pressure Liquid Chromatography-Mass Spectrometry (UHPLC-MS) and UHPLC-tandem MS (UHPLC-MS/MS). Partial Least Squares-Discriminant Analysis (PLS-DA) was applied to resulting dataset. The analysis of main enriched metabolic pathways and the association of the preliminary metabolites/lipids pattern identified to clinical parameters of asthma/COPD differentiation were explored. Multivariate ROC analysis was performed in order to determine the discriminatory power and the reliability of the putative biomarkers for diagnosis between COPD and asthma.

RESULTS

PLS-DA indicated a clear separation between COPD and asthmatic patients. Among the 15 selected candidate biomarkers based on Variable Importance in Projection scores, putrescine showed the highest score. A differential IS bio-signature of 22 metabolites and lipids was found, which showed statistically significant variations between asthma and COPD. Of these 22 compounds, 18 were decreased and 4 increased in COPD compared to asthmatic patients. The IS levels of Phosphatidylethanolamine (PE) (34:1), Phosphatidylglycerol (PG) (18:1;18:2) and spermine were significantly higher in asthmatic subjects compared to COPD.

CONCLUSIONS

This is the first pilot study to analyse the IS metabolomics/lipidomics signatures relevant in discriminating asthma vs COPD. The role of polyamines, of 6-Hydroxykynurenic acid and of D-rhamnose as well as of other important players related to the alteration of glycerophospholipid, aminoacid/biotin and energy metabolism provided the construction of a diagnostic model that, if validated on a larger prospective cohort, might be used to rapidly and accurately discriminate asthma from COPD.

Biotin as a structural component in the detection of small model antigens in BLA-S-ELISA

An interesting biotin-linked-antigen-Sandwich-ELISA was developed (BLA-S-ELISA), which based on the captured Trinitrophenol-Biotin (TNP-Biotin) molecule between the immobilised monovalent antibody and enzyme-conjugated streptavidin. Monoclonal anti-Trinitrotoluene single chain fragment antibody (anti-TNT-scFv) was cloned and expressed in E. coli cells, and then used as an immobilised component in an assay. Thereafter, the previously synthesised TNP-Biotin was added as antigen followed by the addition of streptavidin-horseradish peroxidase (streptavidin-HRP) conjugate which led finally to the formation of a three-component system (antibody/TNP-Biotin/streptavidin-HRP). The assay was performed with a range of different dilutions of TNP-Biotin to establish its minimal detectable concentration. The detection limit of TNP-Biotin was 4 ngmL-1 (i.e. 200 pg or 0.42 pmol antigen calculated on the basis of 50 μL sample or 8.4 nM expressed in concentration units). According to our best knowledge, this is the very first time for any model antigen to be detected with such a form of biotin-streptavidin sandwich-assay.

The formulation and in vitro evaluation of WS Biotin, a novel encapsulated form of D-Biotin with improved water solubility for hair and skin treatment applications

OBJECTIVE

To develop and evaluate the efficacy of WS Biotin, a novel water-soluble form of D-Biotin, for cosmetic use.

METHODS

A new encapsulated form of D-Biotin was developed with the purpose of improving the water solubility of biotin. This novel form of encapsulated biotin was characterized by its physicochemical properties: particle size, D-Biotin content and solubility in water. Also, proliferation and gene expression in vitro tests in cell culture were performed to evaluate its effectiveness in promoting hair growth, an ELISA test was conducted for hair keratinization and skin lightening property was tested by analysing the intracellular melanin content.

RESULTS

The developed WS Biotin microcapsules exhibit a particle size range of 2-30 μm with D-Biotin content of ~50% (w/w). The water solubility of WS Biotin was found to be 20-fold greater than free biotin. The obtained in vitro results indicated that WS Biotin enhances the expression of hair-related keratins in hair follicle keratinocytes, as well as the expression of hair growth-promoting genes in dermal papilla cells. Moreover, the melanin content in UVA-exposed epidermal melanocytes was reduced upon exposure to WS Biotin.

CONCLUSION

In this work, a novel form of encapsulated biotin, WS Biotin, was developed in order to improve the water solubility of free biotin and was found to be effective for cosmetic use in both hair and skin applications.

Metabolomic analysis of combined exposure to microplastics and methylmercury in the brackish water flea Diaphanosoma celebensis

Owing to their widespread distribution and high bioaccumulation, microplastics (MPs) and mercury (Hg) are considered major threats to the ocean. MP interacts with Hg because of its high adsorption properties. However, their toxicological interactions with marine organisms, especially combined effects at the molecular level, are poorly understood. This study investigated the single and combined effects of MP and Hg on the metabolic profile of the brackish water flea Diaphanosoma celebensis. A total of 238 metabolites were significantly affected by MP, Hg, or MP + Hg. Metabolite perturbation patterns showed that toxicity of Hg and MP + Hg was similar and that of MP was not significant. Among the 223 metabolites affected by Hg, profiles of 32 unannotated metabolites were significantly different from those of MP + Hg, and combined effects of MP + Hg decreased the effect of Hg on 25 of these metabolites. Only 11 annotated metabolites were significantly affected by Hg or MP + Hg and were related to carbohydrate, lipid, vitamin, and ecdysteroid metabolism. Ten metabolites were decreased by Hg and MP + Hg and were not significantly different between the exposure groups. Enrichment analysis showed that galactose, starch, and sucrose metabolism were the most affected pathways. These findings suggest that MP has negligible toxic effect, and Hg can induce energy depletion, membrane damage, and disruption of growth, development, and reproduction. Although the impact of MP was negligible, the combined effects of MP + Hg could be metabolite specific. This study provides better understanding of the combined effects of MP and Hg on marine organisms.

Novel practical stereoselective synthesis of a bicyclic hydantoino-thiolactone as the key intermediate for production of (+)-biotin

Bicyclic hydantoinothiolactone (1), as the key intermediate for production of (+)-biotin, has been efficiently and high-stereoselectively synthesized from the cheap starting material l-cystine via nine steps in 44% overall yield. In this new practical synthesis, there are two characteristic steps worthy of note. One step is TMSOTf-catalyzed efficient cyanation of (3S,7aR)-6-benzyl-5-oxo-3-phenyltetrahydro-1H,3H-imidazo[1,5-c]thiazol-7-yl acetate, the other step is DBU-catalyzed rapid isomerization of trans-isomer to cis-isomer of the bicyclic hydantoinothiolactone.

Metagenomic analysis of soybean endosphere microbiome to reveal signatures of microbes for health and disease

BACKGROUND

Soil metagenomics is a cultivation-independent molecular strategy for investigating and exploiting the diversity of soil microbial communities. Soil microbial diversity is essential because it is critical to sustaining soil health for agricultural productivity and protection against harmful organisms. This study aimed to perform a metagenomic analysis of the soybean endosphere (all microbial communities found in plant leaves) to reveal signatures of microbes for health and disease.

RESULTS

The dataset is based on the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) release "microbial diversity in soybean". The quality control process rejected 21 of the evaluated sequences (0.03% of the total sequences). Dereplication determined that 68,994 sequences were artificial duplicate readings, and removed them from consideration. Ribosomal Ribonucleic acid (RNA) genes were present in 72,747 sequences that successfully passed quality control (QC). Finally, we found that hierarchical classification for taxonomic assignment was conducted using MG-RAST, and the considered dataset of the metagenome domain of bacteria (99.68%) dominated the other groups. In Eukaryotes (0.31%) and unclassified sequence 2 (0.00%) in the taxonomic classification of bacteria in the genus group, Streptomyces, Chryseobacterium, Ppaenibacillus, Bacillus, and Mitsuaria were found. We also found some biological pathways, such as CMP-KDO biosynthesis II (from D-arabinose 5-phosphate), tricarboxylic acid cycle (TCA) cycle (plant), citrate cycle (TCA cycle), fatty acid biosynthesis, and glyoxylate and dicarboxylate metabolism. Gene prediction uncovered 1,180 sequences, 15,172 of which included gene products, with the shortest sequence being 131 bases and maximum length 3829 base pairs. The gene list was additionally annotated using Integrated Microbial Genomes and Microbiomes. The annotation process yielded a total of 240 genes found in 177 bacterial strains. These gene products were found in the genome of strain 7598. Large volumes of data are generated using modern sequencing technology to sample all genes in all species present in a given complex sample.

CONCLUSIONS

These data revealed that it is a rich source of potential biomarkers for soybean plants. The results of this study will help us to understand the role of the endosphere microbiome in plant health and identify the microbial signatures of health and disease. The MG-RAST is a public resource for the automated phylogenetic and functional study of metagenomes. This is a powerful tool for investigating the diversity and function of microbial communities.

Effect of yhfS gene on Bt LLP29 antioxidant and UV ray resistance

BACKGROUND

Bacillus thuringiensis (Bt) is a widely used microbial insecticide. However, its persistence is limited because of ultraviolet (UV) rays or other environmental factors. The yhfS gene, which encodes acetyl-CoA acyltransferase, plays an important role in lipid transport and metabolism in many organisms. To explore whether it is related to the stress resistance of Bt LLP29, the yhfS gene knockout strain LLP29 Δ-yhfS and the complementary strain LLP29 R-yhfS were generated successfully by homologous recombination technology, and the related phenotypic changes were compared in this study.

RESULTS

Gene yhfS was found to be functional in response to UV radiation in Bt by comparing the survival rates of Bt LLP29 harboring yhfS or not under UV light. Enzyme activity assays of key enzymes showed the the Embden-Meyerhof-Parnas pathway was enhanced yet the tricarboxylic acid cycle as well as butanoate synthesis were repressed when the gene was deleted. At the same time, the amino acid content was decreased, but reduced nicotinamide adenine dinucleotide (NADH) and reactive oxygen species (ROS) content were increased. Most noteworthy, antioxidase (such as superoxide dismutase and peroxidase) activities and contents of some potent antioxidants (such as pyruvate, carotenoids and NADPH) were lower in LLP29 Δ-yhfS than in LLP29.

CONCLUSION

These tests revealed that the loss of the yhfS gene led to metabolic disorders and reduction of the antioxidant ability of Bt. Higher ROS level and lower anti-oxidative capacity might be responsible for the reduced UV resistance when the gene was deleted. These results not only greatly enrich understanding of the mechanism of Bt UV resistance, but also provide an important theoretical basis for Bt application. © 2023 Society of Chemical Industry.

Dissecting the microbial community structure of internal organs during the early postmortem period in a murine corpse model

BACKGROUND

Microorganisms distribute and proliferate both inside and outside the body, which are the main mediators of decomposition after death. However, limited information is available on the postmortem microbiota changes of extraintestinal body sites in the early decomposition stage of mammalian corpses.

RESULTS

This study investigated microbial composition variations among different organs and the relationship between microbial communities and time since death over 1 day of decomposition in male C57BL/6 J mice by 16S rRNA sequencing. During 1 day of decomposition, Agrobacterium, Prevotella, Bacillus, and Turicibacter were regarded as time-relevant genera in internal organs at different timepoints. Pathways associated with lipid, amino acid, carbohydrate and terpenoid and polyketide metabolism were significantly enriched at 8 h than that at 0.5 or 4 h. The microbiome compositions and postmortem metabolic pathways differed by time since death, and more importantly, these alterations were organ specific.

CONCLUSION

The dominant microbes differed by organ, while they tended toward similarity as decomposition progressed. The observed thanatomicrobiome variation by body site provides new knowledge into decomposition ecology and forensic microbiology. Additionally, the microbes detected at 0.5 h in internal organs may inform a new direction for organ transplantation.

Self-Supplied Electron Photoelectrochemical Biosensor with PTB7-Th as a Photoelectric Material and Biotin as an Efficient Quencher

In this work, a self-supplied electron photoelectrochemical (PEC) biosensor for sensitive determination of Pb²⁺ was established by utilizing donor-acceptor (D-A)-type PTB7-Th (poly{4,8-bis[5-(2-ethylhexyl) thiophen-2-yl]benzo[1,2-b,4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]-thiophene-4,6-diyl}) as a photoelectric material coupled with biotin as an efficient signal quencher. Impressively, compared with the traditional PEC signal quenchers, biotin was first applied as a PEC signal quencher in this work and it effectively avoided a cumbersome preparation process, complex DNA sequence design, and extra reagent assistance and greatly simplified experimental steps, which could achieve an efficient PEC signal quenching toward PTB7-Th. In addition, the execution of a DNAzyme-assisted Pb²⁺ recycling amplification reaction could release the quencher biotin, leading to the recovery of the PEC signal, thereby realizing the quantitative detection of Pb²⁺. Resultantly, the submitted self-supplied electron PEC biosensor presented an extensive coverage of assay Pb²⁺ (50 fM to 500 nM) along with a low determination limit (16.7 fM), which exhibited the advantages of high selectivity and excellent stability. Importantly, this work provided a powerful alternative to traditional heavy metal-ion assessment methods and possessed the potential for application in environment, biomedicine, and food-safety fields.

Untargeted metabolomics of human keratinocytes reveals the impact of exposure to 2,6-dichloro-1,4-benzoquinone and 2,6-dichloro-3-hydroxy-1,4-benzoquinone as emerging disinfection by-products

INTRODUCTION

The 2,6-dichloro-1,4-benzoquinone (DCBQ) and its derivative 2,6-dichloro-3-hydroxy-1,4-benzoquinone (DCBQ-OH) are disinfection by-products (DBPs) and emerging pollutants in the environment. They are considered to be of particular importance as they have a high potential of toxicity and they are likely to be carcinogenic.

OBJECTIVES

In this study, human epidermal keratinocyte cells (HaCaT) were exposed to the DCBQ and its derivative DCBQ-OH, at concentrations equivalent to their IC20 and IC50, and a study of the metabolic phenotype of cells was performed.

METHODS

The perturbations induced in cellular metabolites and their relative content were screened and evaluated through a metabolomic study, using 1H-NMR and MS spectroscopy.

RESULTS

Changes in the metabolic pathways of HaCaT at concentrations corresponding to IC20 and IC50 of DCBQ-OH involved the activation of cell membrane α-linolenic acid, biotin, and glutathione and deactivation of glycolysis/gluconeogenesis at IC50. The changes in metabolic pathways at IC20 and IC50 of DCBQ were associated with the activation of inositol phosphate, pertaining to the transfer of messages from the receptors of the membrane to the interior as well as with riboflavin. Deactivation of biotin metabolism was recorded, among others. The cells exposed to DCBQ exhibited a concentration-dependent decrease in saccharide concentrations. The concentration of steroids increased when cells were exposed to IC20 and decreased at IC50. Although both chemical factors stressed the cells, DCBQ led to the activation of transporting messages through phosphorylated derivatives of inositol.

CONCLUSION

Our findings provided insights into the impact of the two DBPs on human keratinocytes. Both chemical factors induced energy production perturbations, oxidative stress, and membrane damage.

In the Swim of Cannabis: Developmental Toxicity and Metabolomic Pathway Alterations of Zebrafish Larvae Exposed to THC for the Assessment of Its Potential Environmental and Human Health Impact

As the pharmacological properties and therapeutic applications of Cannabis sativa L. pace with the upsurge of interest of the scientific community in harnessing its constituent phytocannabinoids, illicit use may raise serious health issues. Tetrahydrocannabinol (THC) is one of the most well-known phytoactive constituents of cannabis and continues to garner scientific and public attention not only because of its pharmacological value but also because over-the-counter products of THC and prescription medications are becoming increasingly available from pharmacies, dispensaries, Internet, local retail stores, or by illicit means. Hence, a multidimensional approach was employed to examine the impact of THC on zebrafish larvae. The acute toxicity, expressed as LC50, was 1.54 mg/L. Adverse effects were observed on the phenotype, such as tail bending, pericardial edema, etc., even at concentrations lower than LC50, and fundamental functions of larvae (e.g., heart rate and cardiac contractility, and rhythm) were significantly affected. Behavioral changes were noticed, which were reflected in locomotor activity and sensitivity to light/dark changes. Finally, an untargeted metabolomic study was carried out to shed light on the metabolic alterations that occurred, providing substantiating evidence of the observed phenotype alterations. Overall, the potentially detrimental effects of THC on a vertebrate model are depicted.

Study on osteoinductive activity of biotin film by low-energy electron beam deposition

Biotin film was prepared by low-energy electron beam deposition (LEBD). The molecular structure, chemical composition and micromorphology of the biotin film were investigated by ¹HNMR, FTIR, XPS, AFM and SEM. The results showed the molecular structure of a monolayer of biotin film is fully consistent with the molecular structure of the initial biotin powders. The contact angle test showed that the biotin film exhibit good hydrophilicity. The release kinetics of biotin film was tested by UV-Vis method. It was found that the film was almost completely released in about two weeks. The cell viability of MC3T3-E1 cells on the surface of the biotin film was attaining 100.54 ± 1.7% (P < 0.05), showing excellent biocompatibility and biosafety. Titanium implant with surface of biotin film was implanted into the femoral head of rabbits as experimental group. The animals were euthanized after four weeks. Compared with the control group, mature lamellar bone formation was observed with dense trabecular bone, and the expression of Coll-I, Runx2 and BMP-2 was better. The results showed that the repair effect of bone defect in the experimental group was excellent.

Efficient decolorization of azo dye wastewater with polyaniline/graphene modified anode in microbial electrochemical systems

Azo dye pollution has become a worldwide issue, and the current treatment methods can hardly meet the expected emission standards. Microbial electrochemical systems (MESs) show promising applications for decolorization, but their performance critically depends on the microorganisms. Electrode modification is an interesting method of improving decolorization performance. However, the mechanisms of how the modification can affect microbial communities and the decolorization process remain unclear. Here, a modified anode with polyaniline (PANI) and graphene was fabricated via electro-deposition. Consequently, the highest decolorization efficiency was obtained. The Congo red (CR) decolorization rate of the MESs with the PANI/graphene-modified electrode (PG) reached 90% at 54 h. By contrast, the CR decolorization rates of the MESs with the PANI-modified electrode (P) and those of the MESs with the unmodified electrode (C) only reached 68% and 79%, respectively. Results of the microbial community analysis showed abundant Methanobrevibacter arboriphilus in PG (11%), which was 5.5 times that in C (2%) at 18 h. This phenomenon may be related to the rapid decolorization. The upregulated metabolism pathways, including arginine and proline metabolism, purine metabolism, arginine biosynthesis, and riboflavin metabolism, provided more electron shuttles and redox mediators that facilitated the extracellular electron transfer. Therefore, the PG-modified electrode facilitated the decolorization by altering certain metabolic pathways. This study can help to improve the guideline on the potential application of MESs for wastewater treatment.

Effect of biotin supplementation on neuropathic pain induced by chronic constriction of the sciatic nerve in the rat

Background and purpose

Neuropathic pain is one of the most common types of chronic pain that is very difficult to treat. Numerous studies have shown the potential role of vitamins in relieving both hyperalgesia and allodynia. Based on the convincing evidence, this study was designed to evaluate the possible antinociceptive effect of biotin on neuropathic pain in rats.

Experimental approach

This study was performed on male Sprague Dawley rats weighing 200-300 g. Neuropathic pain was induced by tying the sciatic nerve. Chronic constriction injury (CCI) of the sciatic nerve resulted in hyperalgesia and allodynia. To measure the thermal hyperalgesia, the plantar test was used. Also to evaluate the cold and mechanical allodynia, acetone test and von Frey test were applied. Biotin (4, 8, and 16 mg/kg) was administered orally as two different treatment regimens, acute and chronic.

Findings/Results

Acute oral administration of biotin (4, 8, and 16 mg/kg p.o.) on the 7^th, 14^th, and 21^st postoperative days couldn't reduce pain sensitivity compared to the CCI group. However, following the oral administration of biotin (8 and 16 mg/kg p.o.) from the first day after the surgery until day 21, mechanical allodynia (P < 0.001) and heat hyperalgesia (P < 0.05) significantly relieved.

Conclusion and implications

Our results suggest that biotin can be considered as a potential therapeutic for the treatment of neuropathic pain, and supplementation with this vitamin could reduce the required doses of analgesic drugs. However, further studies are needed to confirm this hypothesis.

Screening of biotin-binding FV-antibodies from autodisplayed FV-library on E. coli outer membrane

This study aimed to isolate F_V-antibodies with biotin-binding activity from a F_V-antibody library that was successfully screened on the outer membrane of E. coli. The aims were achieved by (1) preparing a library of F_V-antibodies on the outer membrane of E. coli using autodisplay technology, (2) screening the F_V-antibodies with biotin-binding activity from the F_V-antibody library, and (3) synthesizing peptides (molecular weight of several kDa) from the biotin-binding amino acid sequence of F_V-antibodies. An F_V-antibody library with a diversity of 1.7 × 10⁵ clones was prepared on the outer membrane of E. coli, using a surface display method called autodisplay technology. For the screening of biotin-binding F_V-antibodies, the fluorescence-labeled biotin was introduced into the library, and the target E. coli with biotin-binding activity were screened using flow cytometry. For the screened E. coli clones, the binding affinity (K_D) of Fv-antibodies against biotin was calculated and the binding properties of the screened F_V-antibody were analyzed through competition assay with a synthetic peptide having the biotin-like activity. From the FRET experiment with the synthetic peptide corresponding to the CDR3 region of the screened Fv-antibody, the biotin-binding activity of the screened F_V-antibody was proved to be originated from the CDR3. Finally, the applicability of the biotin-binding domain was demonstrated through the co-expression with a protein called Z-domain with antibody binding activity.

Biochemical and structural characterization of the BioZ enzyme engaged in bacterial biotin synthesis pathway

Biotin is an essential micro-nutrient across the three domains of life. The paradigm earlier step of biotin synthesis denotes "BioC-BioH" pathway in Escherichia coli. Here we report that BioZ bypasses the canonical route to begin biotin synthesis. In addition to its origin of Rhizobiales, protein phylogeny infers that BioZ is domesticated to gain an atypical role of β-ketoacyl-ACP synthase III. Genetic and biochemical characterization demonstrates that BioZ catalyzes the condensation of glutaryl-CoA (or ACP) with malonyl-ACP to give 5'-keto-pimeloyl ACP. This intermediate proceeds via type II fatty acid synthesis (FAS II) pathway, to initiate the formation of pimeloyl-ACP, a precursor of biotin synthesis. To further explore molecular basis of BioZ activity, we determine the crystal structure of Agrobacterium tumefaciens BioZ at 1.99 Å, of which the catalytic triad and the substrate-loading tunnel are functionally defined. In particular, we localize that three residues (S84, R147, and S287) at the distant bottom of the tunnel might neutralize the charge of free C-carboxyl group of the primer glutaryl-CoA. Taken together, this study provides molecular insights into the BioZ biotin synthesis pathway.

Biotin rescues mitochondrial dysfunction and neurotoxicity in a tauopathy model

Mitochondrial and metabolic dysfunction are often implicated in neurological disease, but effective mechanism-based therapies remain elusive. We performed a genome-scale forward genetic screen in a Drosophila model of tauopathy, a class of neurodegenerative disorders characterized by the accumulation of the protein tau, and identified manipulation of the B-vitamin biotin as a potential therapeutic approach in tauopathy. We show that tau transgenic flies have an innate biotin deficiency due to tau-mediated relaxation of chromatin and consequent aberrant expression of multiple biotin-related genes, disrupting both carboxylase and mitochondrial function. Biotin depletion alone causes mitochondrial pathology and neurodegeneration in both flies and human neurons, implicating mitochondrial dysfunction as a mechanism in biotin deficiency. Finally, carboxylase biotin levels are reduced in mammalian tauopathies, including brains of human Alzheimer's disease patients. These results provide insight into pathogenic mechanisms of human biotin deficiency, the resulting effects on neuronal health, and a potential therapeutic pathway in the treatment of tau-mediated neurotoxicity.

Metalloproteomics for molecular target identification of protein-binding anticancer metallodrugs

Proteomics has played an important role in elucidating the fundamental processes occuring in living cells. Translating these methods to metallodrug research ('metalloproteomics') has provided a means for molecular target identification of metal-based anticancer agents which should signifcantly advance the research field. In combination with biological assays, these techniques have enabled the mechanisms of action of metallodrugs to be linked to their interactions with molecular targets and aid understanding of their biological properties. Such investigations have profoundly increased our knowledge of the complex and dynamic nature of metallodrug-biomolecule interactions and have provided, at least for some compound types, a more detailed picture on their specific protein-binding patterns. This perspective highlights the progression of metallodrug proteomics research for the identification of non-DNA targets from standard analytical techniques to powerful metallodrug pull-down methods.

Identification and Characterization of BTD Gene Mutations in Jordanian Children with Biotinidase Deficiency

Biotinidase deficiency is an autosomal recessive metabolic disorder whose diagnosis currently depends on clinical symptoms and a biotinidase enzyme assay. This study aimed to investigate the mutational status and enzymatic activity of biotinidase deficiency in seven unrelated Jordanian families including 10 patients and 17 healthy family members. Amplified DNA was analyzed by the automated Sanger sequencing method, and the enzymatic assay was performed using a colorimetric assessment. Biotinidase level was significantly lower (p < 0.001) in BTD children compare to their non-affected family members. Genetic sequencing revealed six different mutations in Jordanian patients. One mutation was novel and located in exon 4, which could be a prevalent mutation for biotinidase deficiency in the Jordanian population. Identification of these common mutations and combing the enzymatic activity with genotypic data will help clinicians with regard to better genetic counseling and management through implementing prevention programs in the future.

Fabrication of Furan-Functionalized Quinazoline Hybrids: Their Antibacterial Evaluation, Quantitative Proteomics, and Induced Phytopathogen Morphological Variation Studies

The limited number of agrochemicals targeting plant bacterial diseases has driven us to develop highly efficient, low-cost, and versatile antibacterial alternatives. Herein, a novel type of simple furan-functionalized quinazolin-4-amines was systematically fabricated and screened for their antibacterial activity. Bioassay results revealed that compounds C₁ and E₄ could substantially block the growth of two frequently mentioned pathogens Xanthomonas oryzae pv oryzae and X. axonopodis pv citri in vitro, displaying appreciable EC₅₀ values of 7.13 and 10.3 mg/L, respectively. This effect was prominently improved by comparing those of mainly used agrochemicals. An in vivo experiment against bacterial blight further illustrated their viable applications as antimicrobial ingredients. Quantitative proteomics demonstrated that C₁ possessed a remarkable ability to manipulate the upregulation and downregulation of expressed proteins, which probably involved d-glucose and biotin metabolic pathways. This finding was substantially verified by parallel reaction monitoring analysis. Scanning electron microscopy images and fluorescence spectra also indicated that the designed compounds had versatile capacities for destroying the integrity of bacteria. Given these remarkable characteristics, furan-functionalized quinazoline hybrids can serve as a viable platform for developing innovative antibiotic alternatives against bacterial infections.

Biotin deficiency in hyperemesis gravidarum

The aim of this study was to determine the serum biotin levels in patients with hyperemesis gravidarum (HG). Ninety pregnant women with HG (mild (n = 30), moderate (n = 30) and severe (n = 30)), and 80 pregnant women without HG were included for this study. In both groups, serum biotin levels were measured. There were no statistically significant differences in demographic and clinical characteristics between the HG groups and the control group except for PUQE scores. Serum biotin levels in all hyperemesis gravidarum groups were statistically significantly lower than control group. Negative statistically significant correlation between hyperemesis gravidarum severity and serum biotin levels was noted. This is the first study that shows low serum biotin levels in women with hyperemesis gravidarum. Impact statement What is already known on this subject? Almost 80% of pregnant women have nausea and vomiting. If nausea and vomiting became severe and the symptoms combined with weight loss and ketonuria; the diagnosis should be hyperemesis gravidarum (HG). The etiopathogenetic factors of this unwanted condition have not been exactly known. Biotin is an essential water-soluble vitamin. Biotin catabolism increases in pregnancy. Marginal biotin deficiency occurs in approximately 50% of the gestations despite the "normal" biotin intake on the diet. What do the results of this study add? Current study results elucidated that serum biotin levels were lower in HG cases compared to non HG cases. This study is the first study that reports the association between low serum level of biotin and HG. What are the implications of these findings for clinical practice and/or further research? Further research is needed to show the importance of biotin supplementation in women with hyperemesis gravidarum.

Identification of Racemic and Chiral Carbazole Derivatives Containing an Isopropanolamine Linker as Prospective Surrogates against Plant Pathogenic Bacteria: In Vitro and In Vivo Assays and Quantitative Proteomics

Recent observations on the emergence of drug-resistant plant pathogenic bacteria have highlighted and elicited an acute campaign to develop novel, highly efficient antibiotic surrogates for managing bacterial diseases in agriculture. Thus, a type of racemic and chiral carbazole derivative containing an isopropanolamine pattern was systematically synthesized to discover low-cost and efficient antibacterial candidates. Screening results showed that compounds 2f, 6c, and 2j could significantly suppress the growth of tested plant pathogens, namely Xanthomonas oryzae pv oryzae, X. axonopodis pv citri, and Pseudomonas syringae pv actinidiae, and provided the corresponding EC₅₀ values of 1.27, 0.993, and 0.603 μg/mL, which were significantly better than those of existing commercial drugs. In vivo studies confirmed their prospective applications for controlling plant bacterial diseases. Label-free quantitative proteomics analysis indicated that compound 2f could dramatically induce the up- and down-regulation of a total of 247 differentially expressed proteins, which was further validated by the parallel reaction monitoring technique. Moreover, fluorescence spectra and SEM images were obtained to further explore the antibacterial mechanism.

Mitigating effect of biotin against irradiation-induced cerebral cortical and hippocampal damage in the rat brain tissue

Radiation-induced brain injury is common and mainly occurs in patients receiving radiotherapy for malignant head and neck tumors. The brain is oversensitive to oxidant injury induced by radiation. Biotin is a member of the vitamin B complex family and its deficiency has been associated with neurogenesis impairment in animals and humans. The present study was undertaken to investigate the mitigating effect of biotin on the cerebral cortical and hippocampal damage induced by radiation exposure. Animals were exposed to radiation in the presence or absence of biotin and sacrificed on day 10. The results demonstrated that the administration of biotin 2 mg to irradiated rats had no significant effect on the radiation-induced damage of the cerebral cortex and the hippocampus, while the administration of biotin 6 mg has significantly attenuated oxidative stress in the hippocampus, manifested by a reduction of 4-hydroxynonenal (4HNE), total nitrate/nitrite (NOx), and xanthine oxidase (XO) levels associated with an elevation of glutathione (GSH) content as well as superoxide dismutase (SOD) and catalase (CAT) activities. In addition, biotin decreased the pro-inflammatory cytokines (interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrotic factor alpha (TNF-α)), caspase-3, poly(ADP-ribose) polymerase 1 (PARP1) level, and PARP1 gene expression. Moreover, biotin 6 mg treatment diminished serum S100 protein (S100B) and neuron-specific enolase (NSE) levels. In conclusion, biotin treatment at high dose post-irradiation has efficiently neutralized the effect of free radicals in the hippocampal region of rats. Thus, it could be applicable as a radio-mitigator for reducing or delayed radiation-induced brain injury in patients post-radiotherapy.

Effects of the supplementation of plant-based formulations on microbial fermentation and predicted metabolic function in vitro

This study aimed at testing the effects of three different formulations of feed supplements based on three different combinations of plant derived alkaloids, prebiotics, tannins, vitamins and minerals on rumen fermentation and the microbiome in vitro. A Rusitec experiment was conducted in 2 identical runs using a complete randomized design with 3 replicates per treatment resulting in total of 6 treatment combinations (n = 6). Each run lasted 12 d with sampling occurring in the last 5 d. Diets were a standard dairy ration (60:40; concentrate:forage) supplemented with one of 3 different plant-based combinations (PI, PII, and PIII) at a level of 100 mg/l and a non-supplemented control (basal diet, control). Microbial DNA samples were taken on the last day of each run and the 16S rRNA target gene sequenced using Illumina MiSeq technology. The supplementations had no effect on the pH, methane and carbon dioxide production. However, both total SCFA (P = 0.08) and molar concentrations of acetate (P = 0.06) tended to be increased in the treatment groups in comparison to control, with PII having the highest overall values (102.7 mmol/L and 43.3 mmol/L, respectively). Alpha diversity indices Shannon, Simpson and Chao1 showed no effect of supplementations or combinations. The addition of PII increased the relative abundance of Bacteroidetes compared to all other treatments (P = 0.05). Supplementation with plant-based combinations reduced the relative abundance of Pyramidobacter from the family Dethiosulfovibrionaceae in comparison with the control diet (P = 0.05). Evaluation of predicted gene function through PICRUSt analysis showed variation in predicted cellular function and metabolism between bacterial communities supplemented with plant-based combinations compared to the control diet. This shows that the addition of plant-based combinations can have the potential to modulate the metabolic function of rumen microbes, and likely the production of small-sized rumen metabolites, without disrupting the rumen microbial community structure and diversity.

Structural insights into operator recognition by BioQ in the Mycobacterium smegmatis biotin synthesis pathway

BACKGROUND

Biotin is an essential cofactor in living organisms. The TetR family transcriptional regulator (TFTR) BioQ is the main regulator of biotin synthesis in Mycobacterium smegmatis. BioQ represses the expression of its target genes by binding to a conserved palindromic DNA sequence (the BioQ operator). However, the mechanism by which BioQ recognizes this DNA element has not yet been fully elucidated.

METHODS/RESULTS

We solved the crystal structures of the BioQ homodimer in its apo-form and in complex with its specific operator at 2.26 Å and 2.69 Å resolution, respectively. BioQ inserts the N-terminal recognition helix of each protomer into the corresponding major grooves of its operator and stabilizes the formation of the complex via electrostatic interactions and hydrogen bonding to induce conformational changes in both the DNA and BioQ. The DNA interface of BioQ is rich in positively charged residues, which help BioQ stabilize DNA binding. We elucidated the structural basis of DNA recognition by BioQ for the first time and identified the amino acid residues responsible for DNA binding via further site-directed mutagenesis.

GENERAL SIGNIFICANCE

Our findings clearly elucidate the mechanism by which BioQ recognizes its operator in the biotin synthesis pathway and reveal the unique structural characteristics of BioQ that are distinct from other TFTR members.

Genomewide association analysis of sow lactation performance traits in lines of Yorkshire pigs divergently selected for residual feed intake during grow-finish phase

Lactation is an economically and biologically important phase in the life cycle of sows. Short generation intervals in nucleus herds and low heritability of traits associated with lactation along with challenges associated with collecting accurate lactation performance phenotypes emphasize the importance of using genomic tools to examine the underlying genetics of these traits. We report the first genomewide association study (GWAS) on traits associated with lactation and efficiency in 2 lines of Yorkshire pigs that were divergently selected for residual feed intake during grow-finish phase. A total of 862 farrowing records from 2 parities were analyzed using a Bayesian whole genome variable selection model (Bayes B) to locate 1-Mb regions that were most strongly associated with each trait. The GWAS was conducted separately for parity 1 and 2 records. Marker-based heritabilities ranged from 0.03 to 0.39 for parity 1 traits and from 0.06 to 0.40 for parity 2 traits. For all traits studied, around 90% of genetic variance came from a large number of genomic regions with small effects, whereas genomic regions with large effects were found to be different for the same trait measured in parity 1 and 2. The highest percentage of genetic variance explained by a 1-Mb window for each trait ranged from 0.4% for feed intake during lactation to 4.2% for back fat measured at farrowing in parity 1 sows and from 0.2% for lactation feed intake to 5.4% for protein mass loss during lactation in parity 2 sows. A total of thirteen 1-Mb nonoverlapping windows were found to explain more than 1.5% of genetic variance for either a single trait or across multiple traits. These 1-Mb windows were on chromosomes 2, 3, 6, 7, 8, 11, 14, 15, 17, and 18. The major positional candidate genes within 1 Mb upstream and downstream of these windows were , (SSC2), (SSC6) (SSC7), (SSC8), (SSC11), (SSC14), (SSC17). Further validation studies on larger populations are required to validate these findings and to improve our understanding of the biology and complex genetic architecture of traits associated with sow lactation performance.

p-Azidophenylarsenoxide: An Arsenical "Bait" for the In Situ Capture and Identification of Cellular Arsenic-Binding Proteins

Identification of arsenic-binding proteins is important for understanding arsenic health effects and for developing arsenic-based therapeutics. We report here a strategy for the capture and identification of arsenic-binding proteins in living cells. We designed an azide-labeled arsenical, p-azidophenylarsenoxide (PAzPAO), to serve bio-orthogonal functions: the trivalent arsenical group binds to cellular proteins in situ, and the azide group facilitates click chemistry with dibenzylcyclooctyne. The selective and efficient capture of arsenic-binding proteins enables subsequent enrichment and identification by shotgun proteomics. Applications of the technique are demonstrated using the A549 human lung carcinoma cells and two in vitro model systems. The technique enables the capture and identification of 48 arsenic-binding proteins in A549 cells incubated with PAzPAO. Among the identified proteins are a series of antioxidant proteins (e.g., thioredoxin, peroxiredoxin, peroxide reductase, glutathione reductase, and protein disulfide isomerase) and glyceraldehyde-3-phosphate dehydrogenase. Identification of these functional proteins, along with studies of arsenic binding and enzymatic inhibition, points to these proteins as potential molecular targets that play important roles in arsenic-induced health effects and in cancer treatment.

Selective accumulation of biotin in arterial chemoreceptors: requirement for carotid body exocytotic dopamine secretion

KEY POINTS

Biotin, a vitamin whose main role is as a coenzyme for carboxylases, accumulates at unusually large amounts within cells of the carotid body (CB). In biotin-deficient rats biotin rapidly disappears from the blood; however, it remains at relatively high levels in CB glomus cells. The CB contains high levels of mRNA for SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Animals with biotin deficiency exhibit pronounced metabolic lactic acidosis. Remarkably, glomus cells from these animals have normal electrical and neurochemical properties. However, they show a marked decrease in the size of quantal dopaminergic secretory events. Inhibitors of the vesicular monoamine transporter 2 (VMAT2) mimic the effect of biotin deficiency. In biotin-deficient animals, VMAT2 protein expression decreases in parallel with biotin depletion in CB cells. These data suggest that dopamine transport and/or storage in small secretory granules in glomus cells depend on biotin.

ABSTRACT

Biotin is a water-soluble vitamin required for the function of carboxylases as well as for the regulation of gene expression. Here, we report that biotin accumulates in unusually large amounts in cells of arterial chemoreceptors, carotid body (CB) and adrenal medulla (AM). We show in a biotin-deficient rat model that the vitamin rapidly disappears from the blood and other tissues (including the AM), while remaining at relatively high levels in the CB. We have also observed that, in comparison with other peripheral neural tissues, CB cells contain high levels of SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Biotin-deficient rats show a syndrome characterized by marked weight loss, metabolic lactic acidosis, aciduria and accelerated breathing with normal responsiveness to hypoxia. Remarkably, CB cells from biotin-deficient animals have normal electrophysiological and neurochemical (ATP levels and catecholamine synthesis) properties; however, they exhibit a marked decrease in the size of quantal catecholaminergic secretory events, which is not seen in AM cells. A similar differential secretory dysfunction is observed in CB cells treated with tetrabenazine, a selective inhibitor of the vesicular monoamine transporter 2 (VMAT2). VMAT2 is highly expressed in glomus cells (in comparison with VMAT1), and in biotin-deficient animals VMAT2 protein expression decreases in parallel with the decrease of biotin accumulated in CB cells. These data suggest that biotin has an essential role in the homeostasis of dopaminergic transmission modulating the transport and/or storage of transmitters within small secretory granules in glomus cells.

CSL protein regulates transcription of genes required to prevent catastrophic mitosis in fission yeast

For every eukaryotic cell to grow and divide, intricately coordinated action of numerous proteins is required to ensure proper cell-cycle progression. The fission yeast Schizosaccharomyces pombe has been instrumental in elucidating the fundamental principles of cell-cycle control. Mutations in S. pombe 'cut' (cell untimely torn) genes cause failed coordination between cell and nuclear division, resulting in catastrophic mitosis. Deletion of cbf11, a fission yeast CSL transcription factor gene, triggers a 'cut' phenotype, but the precise role of Cbf11 in promoting mitotic fidelity is not known. We report that Cbf11 directly activates the transcription of the acetyl-coenzyme A carboxylase gene cut6, and the biotin uptake/biosynthesis genes vht1 and bio2, with the former 2 implicated in mitotic fidelity. Cbf11 binds to a canonical, metazoan-like CSL response element (GTGGGAA) in the cut6 promoter. Expression of Cbf11 target genes shows apparent oscillations during the cell cycle using temperature-sensitive cdc25-22 and cdc10-M17 block-release experiments, but not with other synchronization methods. The penetrance of catastrophic mitosis in cbf11 and cut6 mutants is nutrient-dependent. We also show that drastic decrease in biotin availability arrests cell proliferation but does not cause mitotic defects. Taken together, our results raise the possibility that CSL proteins play conserved roles in regulating cell-cycle progression, and they could guide experiments into mitotic CSL functions in mammals.

Targeting demyelination and virtual hypoxia with high-dose biotin as a treatment for progressive multiple sclerosis

Progressive multiple sclerosis (MS) is a severely disabling neurological condition, and an effective treatment is urgently needed. Recently, high-dose biotin has emerged as a promising therapy for affected individuals. Initial clinical data have shown that daily doses of biotin of up to 300 mg can improve objective measures of MS-related disability. In this article, we review the biology of biotin and explore the properties of this ubiquitous coenzyme that may explain the encouraging responses seen in patients with progressive MS. The gradual worsening of neurological disability in patients with progressive MS is caused by progressive axonal loss or damage. The triggers for axonal loss in MS likely include both inflammatory demyelination of the myelin sheath and primary neurodegeneration caused by a state of virtual hypoxia within the neuron. Accordingly, targeting both these pathological processes could be effective in the treatment of progressive MS. Biotin is an essential co-factor for five carboxylases involved in fatty acid synthesis and energy production. We hypothesize that high-dose biotin is exerting a therapeutic effect in patients with progressive MS through two different and complementary mechanisms: by promoting axonal remyelination by enhancing myelin production and by reducing axonal hypoxia through enhanced energy production. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.

An Untargeted Metabolomics Analysis of Antipsychotic Use in Bipolar Disorder

BACKGROUND

Second generation antipsychotic (SGA) use in bipolar disorder is common and has proven effective in short-term trials. There continues to be a lack of understanding of the mechanisms underlying many of their positive and negative effects in bipolar disorder. This study aimed to describe the metabolite profiles of bipolar subjects treated with SGAs by comparing to metabolite profiles of bipolar subjects treated with lithium, and schizophrenia subjects treated with SGAs.

METHODS

Cross-sectional, fasting untargeted serum metabolomic profiling was conducted in 82 subjects diagnosed with bipolar I disorder (n = 30 on SGAs and n = 32 on lithium) or schizophrenia (n = 20). Metabolomic profiles of bipolar subjects treated with SGAs were compared to bipolar subjects treated with lithium and schizophrenia subjects treated with SGAs using multivariate methods.

RESULTS

Partial lease square discriminant analysis (PLS-DA) plots showed separation between bipolar subjects treated with SGAs, bipolar subjects treated with lithium, or schizophrenia subjects treated with SGAs. Top influential metabolite features were associated with several pathways including that of polyunsaturated fatty acids, pyruvate, glucose, and branched chain amino acids.

CONCLUSIONS

The findings from this study require further validation in pre- and posttreated bipolar and schizophrenia subjects, but suggest that the pharmacometabolome may be diagnosis specific.

Biotin amelioration of nephrotoxicity in streptozotocin-induced diabetic mice

The current study was carried out to investigate the protective role of biotin in kidney injury and oxidative stress in diabetic mice type 1. Male Swiss albino mice were randomly divided into 3 groups. Control group received saline. Diabetes type 1 was induced in second and third groups by intraperitoneal injection of streptozotocin as a single dose (150 mg/kg). Second group remained as the untreated diabetic group and the third group received 15 mg/kg daily oral dose of biotin for 12 successive days. Biochemical results showed significant elevation in blood glucose and urea levels in both diabetic groups. Also, there is an increase in glomerular areas and decrease in glomerular cellularity in both diabetic groups. Histopathological results showed severe alterations in the untreated diabetic group represented by distorted glomeruli, inflammatory cells, and giant macrophages. In addition, there was an intense immune-reaction response toward acrolein indicator of oxidative damage. Upon biotin administration of diabetic mice, the above mentioned histopathological changes were reduced and also acroline reaction of oxidative damage was diminished. Our findings prove that biotin has a protective role against streptozotocin-induced oxidative damage in kidneys of laboratory mice.

Holocarboxylase synthetase acts as a biotin-independent transcriptional repressor interacting with HDAC1, HDAC2 and HDAC7

In human cells, HCS catalyzes the biotinylation of biotin-dependent carboxylases and mediates the transcriptional control of genes involved in biotin metabolism through the activation of a cGMP-dependent signal transduction pathway. HCS also targets to the cell nucleus in association with lamin-B suggesting additional gene regulatory functions. Studies from our laboratory in Drosophila melanogaster showed that nuclear HCS is associated with heterochromatin bands enriched with the transcriptionally repressive mark histone 3 trimethylated at lysine 9. Further, HCS was shown to be recruited to the core promoter of the transcriptionally inactive hsp70 gene suggesting that it may participate in the repression of gene expression, although the mechanism involved remained elusive. In this work, we expressed HCS as a fusion protein with the DNA-binding domain of GAL4 to evaluate its effect on the transcription of a luciferase reporter gene. We show that HCS possesses transcriptional repressor activity in HepG2 cells. The transcriptional function of HCS was shown by in vitro pull down and in vivo co-immunoprecipitation assays to depend on its interaction with the histone deacetylases HDAC1, HDAC2 and HDAC7. We show further that HCS interaction with HDACs and its function in transcriptional repression is not affected by mutations impairing its biotin-ligase activity. We propose that nuclear HCS mediates events of transcriptional repression through a biotin-independent mechanism that involves its interaction with chromatin-modifying protein complexes that include histone deacetylases.