The requirement for cobalt in vitamin B12: A paradigm for protein metalation

Vitamin B12: prevention of human beings from lethal diseases and its food application

Vitamin B12, a water-soluble essential micronutrient, plays a pivotal role in numerous physiological processes in the human body. This review meticulously examines the structural complexity and the diverse mechanisms through which vitamin B12 exerts its preventive effects against a spectrum of health conditions, including pernicious anaemia, neurological disorders, obesity, diabetes, dyslipidaemia and complications in foetal development. The selection of articles for this review was conducted through a systematic search across multiple scientific databases, including PubMed, Scopus and Web of Science. Criteria for inclusion encompassed relevance to the biochemical impact of vitamin B12 on health, peer-reviewed status and publication within the last decade. Exclusion criteria were non-English articles and studies lacking empirical evidence. This stringent selection process ensured a comprehensive analysis of vitamin B12's multifaceted impact on health, covering its structure, bioavailable forms and mechanisms of action. Clinical studies highlighting its therapeutic potential, applications in food fortification and other utilizations are also discussed, underscoring the nutrient's versatility. This synthesis aims to provide a clear understanding of the integral role of vitamin B12 in maintaining human health and its potential in clinical and nutritional applications. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Site-specific incorporation of 19F-nulcei at protein C-terminus to probe allosteric conformational transitions of metalloproteins

Allosteric conformational change is an important paradigm in the regulation of protein function, which is typically triggered by the binding of small cofactors, metal ions or protein partners. Here, we found those conformational transitions can be effectively monitored by 19F NMR, facilitated by a site-specific 19F incorporation strategy at the protein C-terminus using asparaginyl endopeptidase (AEP). Three case studies show that C-terminal 19F-nuclei can reveal protein dynamics not only adjacent but also distal to C-terminus, including those occurring in a hemoprotein neuroglobin (Ngb), calmodulin (CaM), and a cobalt metalloregulator (CoaR) responding to both cobalt and tetrapyrrole. In Ngb, the heme orientation disorder is affected by missense mutations that perturb backbone rigidity or surface charges close to the heme axial ligands. In CaM, the C-terminal 19F-nuclei is an ideal probe for detecting the binding states of Ca2+, peptides and inhibitors. Furthermore, multiple 19F-moieties were incorporated into the two domains of CoaR, revealing the intrinsically disordered C-terminal metal binding tail might be an allosteric conformational switch to maintain cobalt homeostasis and balance corrinoid biosynthesis. This study demonstrates that the AEP-based 19F-modification strategy can be applied to various targets to study allosteric regulation, especially for those biological processes modulated by the protein C-terminus.

Biological properties of vitamin B12

Vitamin B12, cobalamin, is indispensable for humans owing to its participation in two biochemical reactions: the conversion of l-methylmalonyl coenzyme A to succinyl coenzyme A, and the formation of methionine by methylation of homocysteine. Eukaryotes, encompassing plants, fungi, animals and humans, do not synthesise vitamin B12, in contrast to prokaryotes. Humans must consume it in their diet. The most important sources include meat, milk and dairy products, fish, shellfish and eggs. Due to this, vegetarians are at risk to develop a vitamin B12 deficiency and it is recommended that they consume fortified food. Vitamin B12 behaves differently to most vitamins of the B complex in several aspects, e.g. it is more stable, has a very specific mechanism of absorption and is stored in large amounts in the organism. This review summarises all its biological aspects (including its structure and natural sources as well as its stability in food, pharmacokinetics and physiological function) as well as causes, symptoms, diagnosis (with a summary of analytical methods for its measurement), prevention and treatment of its deficiency, and its pharmacological use and potential toxicity.

Promoting salt tolerance, growth, and phytochemical responses in coriander (Coriandrum sativum L. cv. Balady) via eco-friendly Bacillus subtilis and cobalt

In plant production, evaluation of salt stress protectants concerning their potential to improve growth and productivity under saline stress is critical. Bacillus subtilis (Bs) and cobalt (Co) have been proposed to optimize salt stress tolerance in coriander (Coriandrum sativum L. cv. Balady) plants by influencing some physiological activities. The main aim of this work is to investigate the response of (Bs) and (Co) as eco-safe salt stress protectants to resist the effect of salinity, on growth, seed, and essential oil yield, and the most important biochemical constituents of coriander produced under salt stress condition. Therefore, in a split-plot factorial experiment design in the RCBD (randomized complete block design), four levels of salinity of NaCl irrigation water (SA) were assigned to the main plots; (0.5, 1.5, 4, and 6 dS m-1); and six salt stress protectants (SP) were randomly assigned to the subplots: distilled water; 15 ppm (Co1); 30 ppm (Co2); (Bs); (Co1 + Bs); (Co2 + Bs). The study concluded that increasing SA significantly reduced coriander growth and yield by 42.6%, which could be attributed to ion toxicity, oxidative stress, or decreased vital element content. From the results, we recommend that applying Bs with Co (30 ppm) was critical for significantly improving overall growth parameters. This was determined by the significant reduction in the activity of reactive oxygen species scavenging enzymes: superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) and non-enzyme: proline by 5, 11.3, 14.7, and 13.8% respectively, while increasing ascorbic acid by 8% and preserving vital nutrient levels and enhancing plant osmotic potential to buffer salt stress, seed yield per plant, and essential oil yield increased by 12.6 and 18.8% respectively. The quality of essential oil was indicated by highly significant quantities of vital biological phytochemicals such as linalool, camphor, and protein which increased by 10.3, 3.6, and 9.39% respectively. Additional research is suggested to determine the precise mechanism of action of Bs and Co's dual impact on medicinal and aromatic plant salt stress tolerance.

2,4-Diarylpyrroles: synthesis, characterization and crystallographic insights

Three 2,4-diarylpyrroles were synthesized starting from 4-nitrobutanones and the crystal structures of two derivatives were analysed. These are 4-(4-methoxyphenyl)-2-(thiophen-2-yl)-1H-pyrrole, C15H13NOS, and 3-(4-bromophenyl)-2-nitroso-5-phenyl-1H-pyrrole, C16H11BrN2O. Although pyrroles without substituents at the α-position with respect to the N atom are very air sensitive and tend to polymerize, we succeeded in growing an adequate crystal for X-ray diffraction analysis. Further derivatization using sodium nitrite afforded a nitrosyl pyrrole derivative, which crystallized in the triclinic space group P-1 with Z = 6. Thus, herein we report the first crystal structure of a nitrosyl pyrrole. Interestingly, the co-operative hydrogen bonds in this NO-substituted pyrrole lead to a trimeric structure with bifurcated halogen bonds at the ends, forming a two-dimensional (2D) layer with interstitial voids having a radius of 5 Å, similar to some reported macrocyclic porphyrins.

Gold Nanodots-Anchored Cobalt Ferrite Nanoflowers as Versatile Tumor Microenvironment Modulators for Reinforced Redox Dyshomeostasis

Given that tumor microenvironment (TME) exerts adverse impact on the therapeutic response and clinical outcome, robust TME modulators may significantly improve the curative effect and increase survival benefits of cancer patients. Here, Au nanodots-anchored CoFe2O4 nanoflowers with PEGylation (CFAP) are developed to respond to TME cues, aiming to exacerbate redox dyshomeostasis for efficacious antineoplastic therapy under ultrasound (US) irradiation. After uptake by tumor cells, CFAP with glucose oxidase (GOx)-like activity can facilitate glucose depletion and promote the production of H2O2. Multivalent elements of Co(II)/Co(III) and Fe(II)/Fe(III) in CFAP display strong Fenton-like activity for·OH production from H2O2. On the other hand, energy band structure CFAP is superior for US-actuated 1O2 generation, relying on the enhanced separation and retarded recombination of e-/h+ pairs. In addition, catalase-mimic CFAP can react with cytosolic H2O2 to generate molecular oxygen, which may increase the product yields from O2-consuming reactions, such as glucose oxidation and sonosensitization processes. Besides the massive production of reactive oxygen species, CFAP is also capable of exhausting glutathione to devastate intracellular redox balance. Severe immunogenic cell death and effective inhibition of solid tumor by CFAP demonstrates the clinical potency of such heterogeneous structure and may inspire more relevant designs for disease therapy.

Emission-based sensing of cobalt (II) and vitamin B12 via a bis-indole derivative

In this study, a bis-indole compound was synthesized, characterized by 1H NMR, Fourier transform infrared, and mass spectroscopic measurements and used as a selective and efficient probe for the spectrofluorimetric analysis of Co (II). The cobalt-induced quenching in the emission maximum at 567 nm was considered as the analytical signal in calibration studies. When encapsulated in a polymethyl methacrylate (PMMA) matrix, the bis-indole compound exhibited a limit of detection (LOD) of 3.60 × 10-11 M for Co (II). Vitamin B12, which contains a cobalt ion in the center of a corrin ring in its structure, was also successfully quantified using the same probe. The bis-indole compound showed a linear response based on quenching for increasing concentrations of vitamin B12, partially mimicking the contracted tetrapyrrole ring found naturally in the center of vitamin B12. The LOD for vitamin B12 was found to be 76 nm. Promising photophysical properties of the proposed probe, including high molar extinction coefficient, considerable quantum yield (0.46 and 0.64 in tetrahydrofuran and PMMA, respectively), high Stoke's shift and satisfactory photostability, make it a good choice for fluorescence-based Co (II) determination. The ML3-type stoichiometry of the complex between the dye and cobalt was elucidated both by Job's method and by high-resolution mass spectrometry (HR-MS).

An Update Overview on Mechanistic Data and Biomarker Levels in Cobalt and Chromium-Induced Neurodegenerative Diseases

There is increasing evidence that the imbalance of metals as cobalt (Co) and chromium (Cr) may increase the risk of development and progression of neurodegenerative diseases (NDDs). The human exposure to Co and Cr is derived mostly from industry, orthopedic implants, and polluted environments. Neurological effects of Co and Cr include memory deficit, olfactory dysfunction, spatial disorientation, motor neuron disease, and brain cancer. Mechanisms of Co and Cr neurotoxicity included DNA damage and genomic instability, epigenetic changes, mitochondrial disturbance, lipid peroxidation, oxidative stress, inflammation, and apoptosis. This paper seeks to overview the Co and Cr sources, the mechanisms by which these metals induce NDDs, and their levels in fluids of the general population and patients affected by NDDs. To this end, evidence of Co and Cr unbalance in the human body, mechanistic data, and neurological symptoms were collected using in vivo mammalian studies and human samples.

Exposure to different cobalt chloride levels produces oxidative stress and lipidomic changes and affects the liver structure of Cyprinus carpio juveniles

The present investigation was undertaken to evaluate the toxic effects of CoCl2-induced hepatotoxicity and fatty acid changes in juvenile Cyprinus carpio. Fish were divided into six experimental groups in duplicate. The first group served as controls. The second group received the lowest exposure dose at 2.5 µg/L. In the third group, fish were exposed to 25 µg/L of CoCl2. The fourth group was exposed to 50 µg/L of CoCl2. The last two groups were exposed to the highest doses, 100 and 500 µg/L of CoCl2. Total antioxidant activities were estimated using a colorimetric method. Liver fatty acid compositions were analyzed by high-performance gas chromatography (GC). Hepatopathy was identified through microscopic analysis. Exposure of C. carpio to CoCl2 resulted in hepatotoxicity, indicated by increased levels of malondialdehyde (MDA), hydrogen peroxide (H2O2), protein carbonyls (PCO), and alterations in the ferric reducing antioxidant power system (FRAP). Superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione peroxidase (GPx), reduced glutathione (GSH), metallothioneins (MTs), and low thiol levels (L-SH) significantly increased, particularly under exposure to the highest CoCl2 doses (100 and 500 µg/L). Acetylcholinesterase activity decreased significantly in C. carpio exposed to graded CoCl2 doses. Additionally, there was a decrease in polyunsaturated fatty acids (PUFA), primarily n-3 PUFA, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), while an increase in monounsaturated (MUFA) and saturated fatty acids (SFA), including palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), and oleic (C18:1) acids, was observed. Histopathological examination of the liver confirmed hepatopathy revealing characteristic tissue changes such as leucocyte infiltration, hepatic cell membrane degradation, vacuolization, and lipid inclusions. The study provided ethnophysiology insights into the responses of C. carpio to CoCl2-induced oxidative stress and lipidomic alteration, underscoring its potential as a bioindicator for assessing environmental impacts and metal contamination.

Metal Homeostasis in Land Plants: A Perpetual Balancing Act Beyond the Fulfilment of Metalloproteome Cofactor Demands

One of life's decisive innovations was to harness the catalytic power of metals for cellular chemistry. With life's expansion, global atmospheric and biogeochemical cycles underwent dramatic changes. Although initially harmful, they permitted the evolution of multicellularity and the colonization of land. In land plants as primary producers, metal homeostasis faces heightened demands, in part because soil is a challenging environment for nutrient balancing. To avoid both nutrient metal limitation and metal toxicity, plants must maintain the homeostasis of metals within tighter limits than the homeostasis of other minerals. This review describes the present model of protein metalation and sketches its transfer from unicellular organisms to land plants as complex multicellular organisms. The inseparable connection between metal and redox homeostasis increasingly draws our attention to more general regulatory roles of metals. Mineral co-option, the use of nutrient or other metals for functions other than nutrition, is an emerging concept beyond that of nutritional immunity.

Microencapsulation of vitamins: A review and meta-analysis of coating materials, release and food fortification

Vitamins are responsible for providing biological properties to the human body; however, their instability under certain environmental conditions limits their utilization in the food industry. The objective was to conduct a systematic review on the use of biopolymers and lipid bases in microencapsulation processes, assessing their impact on the stability, controlled release, and viability of fortified foods with microencapsulated vitamins. The literature search was conducted between the years 2013-2023, gathering information from databases such as Scopus, PubMed, Web of Science and publishers including Taylor & Francis, Elsevier, Springer and MDPI; a total of 49 articles were compiled The results were classified according to the microencapsulation method, considering the following information: core, coating material, solvent, formulation, process conditions, particle size, efficiency, yield, bioavailability, bioaccessibility, in vitro release, correlation coefficient and references. It has been evidenced that gums are the most frequently employed coatings in the protection of vitamins (14.04%), followed by alginate (10.53%), modified chitosan (9.65%), whey protein (8.77%), lipid bases (8.77%), chitosan (7.89%), modified starch (7.89%), starch (7.02%), gelatin (6.14%), maltodextrin (5.26%), zein (3.51%), pectin (2.63%) and other materials (7.89%). The factors influencing the release of vitamins include pH, modification of the coating material and crosslinking agents; additionally, it was determined that the most fitting mathematical model for release values is Weibull, followed by Zero Order, Higuchi and Korsmeyer-Peppas; finally, foods commonly fortified with microencapsulated vitamins were described, with yogurt, bakery products and gummy candies being notable examples.

The Role of Cobalamin in Multiple Sclerosis: An Update

Multiple sclerosis (MS) is a neurodegenerative condition that results in axonal and permanent damage to the central nervous system, necessitating healing owing to autoimmune reactions and persistent neuroinflammation. Antioxidant and anti-inflammatory drugs are essential for the management of oxidative stress and neuroinflammation. Additionally, multivitamin supplementation, particularly vitamin B12 (cobalamin), may be beneficial for neuronal protection. Although there is no documented connection between vitamin B12 deficiency and MS, researchers have explored its potential as a metabolic cause. This review highlights the therapeutic benefits of cobalamin (Cbl) in patients with MS.

Metals on the Menu-Analyzing the Presence, Importance, and Consequences

Metals are integral components of the natural environment, and their presence in the food supply is inevitable and complex. While essential metals such as sodium, potassium, magnesium, calcium, iron, zinc, and copper are crucial for various physiological functions and must be consumed through the diet, others, like lead, mercury, and cadmium, are toxic even at low concentrations and pose serious health risks. This study comprehensively analyzes the presence, importance, and consequences of metals in the food chain. We explore the pathways through which metals enter the food supply, their distribution across different food types, and the associated health implications. By examining current regulatory standards for maximum allowable levels of various metals, we highlight the importance of ensuring food safety and protecting public health. Furthermore, this research underscores the need for continuous monitoring and management of metal content in food, especially as global agricultural and food production practices evolve. Our findings aim to inform dietary recommendations, food fortification strategies, and regulatory policies, ultimately contributing to safer and more nutritionally balanced diets.

Serum Vitamin B12 and Holotranscobalamin Levels in Subclinical Hypothyroid Patients in Relation to Thyroid-Stimulating Hormone (TSH) Levels and the Positivity of Anti-thyroid Peroxidase Antibodies: A Case-Control Study

Background Subclinical hypothyroidism (SCH) is characterized by elevated thyroid-stimulating hormone (TSH) levels, while thyroid hormones (free thyroxine (T4) and free triiodothyronine (T3)) remain within the reference ranges. Vitamin B12 (cobalamin) deficiency is common in patients with autoimmune disorders, including autoimmune hypothyroidism. The study was aimed at evaluating serum vitamin B12 levels and holotranscobalamin (HoloTC) levels in SCH patients and ascertaining their association with a risky level of TSH and the positivity of anti-thyroid peroxidase (anti-TPO) antibodies. Methodology A case-control study was conducted at Azadi Teaching Hospital, Duhok, a city in the Kurdistan region of Iraq, involving 153 participants, including 72 newly diagnosed SCH patients and 81 healthy controls. Serum levels of vitamin B12, HoloTC, TSH, free T4, free T3, and anti-TPO antibodies were measured based on different principles. Results The mean age of patients with SCH was 32.87±8.7 years, with predominantly females comprising 75% and 77.8% being less than 40 years of age. Moreover, the mean levels of serum TSH (6.96±2.68 µIU/L), anti-TPO antibodies (53.31±81.32 IU/ml), and HoloTC (41.93±19.42 pmol/l) were significantly higher in patients with SCH compared to healthy control participants (p < 0.05), whereas there was a non-significantly higher level of vitamin B12(320.72±98.42 pg/ml) among SCH patients compared to healthy control participants (p = 0.220). The mean levels of vitamin B12 (345.33±103.22 pg/ml) and HoloTC (40.14±18.16 pmol/l) were insignificantly lower in SCH patients with TSH levels more than 7 µIU/L (p > 0.05), as well as the mean levels of vitamin B12 (308.82±96.12 pg/ml) and HoloTC (41.14±19.29 pmol/l) insignificantly lower in SCH patients with positive anti-TPO antibodies (p > 0.05).  Conclusions This study highlights the potential association between SCH and altered vitamin B12 status, particularly evident in HoloTC levels. The presence of positive anti-TPO antibodies and the degree of elevation in TSH levels may exacerbate vitamin B12 deficiency in SCH patients.

Toxic metals and essential trace elements in placenta and their relation to placental function

INTRODUCTION

Placental function is essential for fetal development, but it may be susceptible to malnutrition and environmental stressors.

OBJECTIVE

To assess the impact of toxic and essential trace elements in placenta on placental function.

METHODS

Toxic metals (cadmium, lead, mercury, cobalt) and essential elements (copper, manganese, zinc, selenium) were measured in placenta of 406 pregnant women in northern Sweden using ICP-MS. Placental weight and birth weight were obtained from hospital records and fetoplacental weight ratio was used to estimate placental efficiency. Placental relative telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) were determined by quantitative PCR (n = 285). Single exposure-outcome associations were evaluated using linear or spline regression, and joint associations and interactions with Bayesian kernel machine regression (BKMR), all adjusted for sex, maternal smoking, and age or BMI.

RESULTS

Median cadmium, mercury, lead, cobalt, copper, manganese, zinc, and selenium concentrations in placenta were 3.2, 1.8, 4.3, 2.3, 1058, 66, 10626, and 166 μg/kg, respectively. In the adjusted regression, selenium (>147 μg/kg) was inversely associated with placental weight (B: -158; 95 % CI: -246, -71, per doubling), as was lead at low selenium (B: -23.6; 95 % CI: -43.2, -4.0, per doubling). Manganese was positively associated with placental weight (B: 41; 95 % CI: 5.9, 77, per doubling) and inversely associated with placental efficiency (B: -0.01; 95 % CI: -0.019, -0.004, per doubling). Cobalt was inversely associated with mtDNAcn (B: -11; 95 % CI: -20, -0.018, per doubling), whereas all essential elements were positively associated with mtDNAcn, individually and joint.

CONCLUSION

Among the toxic metals, lead appeared to negatively impact placental weight and cobalt decreased placental mtDNAcn. Joint essential element concentrations increased placental mtDNAcn. Manganese also appeared to increase placental weight, but not birth weight. The inverse association of selenium with placental weight may reflect increased transport of selenium to the fetus in late gestation.

The Rhodium Analogue of Coenzyme B12 as an Anti-Photoregulatory Ligand Inhibiting Bacterial CarH Photoreceptors

Coenzyme B12 (AdoCbl; 5'-deoxy-5'-adenosylcobalamin), the quintessential biological organometallic radical catalyst, has a formerly unanticipated, yet extensive, role in photoregulation in bacteria. The light-responsive cobalt-corrin AdoCbl performs this nonenzymatic role by facilitating the assembly of CarH photoreceptors into DNA-binding tetramers in the dark, suppressing gene expression. Conversely, exposure to light triggers the decomposition of this AdoCbl-bound complex by a still elusive photochemical mechanism, activating gene expression. Here, we have examined AdoRhbl, the non-natural rhodium analogue of AdoCbl, as a photostable isostructural surrogate for AdoCbl. We show that AdoRhbl closely emulates AdoCbl in its uptake by bacterial cells and structural functionality as a regulatory ligand for CarH tetramerization, DNA binding, and repressor activity. Remarkably, we find AdoRhbl is photostable even when bound "base-off/His-on" to CarH in vitro and in vivo. Thus, AdoRhbl, an antivitamin B12, also represents an unprecedented anti-photoregulatory ligand, opening a pathway to precisely target biomimetic inhibition of AdoCbl-based photoregulation, with new possibilities for selective antibacterial applications. Computational biomolecular analysis of AdoRhbl binding to CarH yields detailed structural insights into this complex, which suggest that the adenosyl group of photoexcited AdoCbl bound to CarH may specifically undergo a concerted non-radical syn-1,2-elimination mechanism, an aspect not previously considered for this photoreceptor.

The association of urinary heavy metal exposure with frailty susceptibility and mortality in middle-aged and older adults: a population-based study

Heavy metals' presence as environmental pollutants has a close link to adverse health effects. Frailty, a clinical syndrome hallmarked by elevated vulnerability to stressors, presents a substantial challenge in healthcare. However, the association between exposure to heavy metals and frailty largely remains unexplored. Utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2003-2018 and correlated with the U.S. National Death Index (NDI) from 2019, we investigated mortality outcomes. Logistic regression, Cox regression, Kaplan-Meier survival curves, weighted quantile-sum (WQS) regression, and Bayesian kernel machine regression (BKMR) were employed to assess the association between heavy metal exposure and frailty incidence and mortality in the frail population. Eight metals were measured in urine using inductively coupled plasma mass spectrometry with values adjusted for urinary creatinine, which was used to reflect heavy metal exposure. The cohort incorporated 5370 female participants aged 45 and above, with 1518 diagnosed with frailty. The findings indicated a substantial correlation between exposure to specific heavy metals, namely tungsten (odds ratio [OR]: 1.94, 95% confidence interval [CI]: 1.31-2.89), cobalt (OR: 1.64, 95% CI: 1.40-1.93), cadmium (OR: 1.93, 95% CI: 1.52-2.43), and uranium (OR: 7.36, 95% CI: 1.53-35.28), and an elevated risk of frailty. WQS and BKMR regression models identified cadmium, cobalt, and tungsten as main contributors to frailty. Cox regression analysis, after adjustment for covariates, suggested that the higher the exposure levels to cadmium and lead, the higher the risk of death in frail patients, with associated hazard ratios (HR) of 95% CI: 1.96 (1.53, 2.52) and 1.30 (1.13, 1.49), respectively. Our study revealed a significant positive correlation between exposure to heavy metal mixtures and frailty onset in middle-aged and older adults, along with increased mortality in frail patients. Cobalt, cadmium, and tungsten emerged as prominent contributors to frailty, with cobalt and cadmium directly impacting the long-term life expectancy of frail patients.

Potassium humate and cobalt enhance peanut tolerance to water stress through regulation of proline, antioxidants, and maintenance of nutrient homeostasis

Water stress is an important factor that substantially impacts crop production. As a result, there is a need for various strategies that can mitigate these negative effects. One such strategy is the application of potassium humate (Kh) and cobalt (Co), which have been reported to enhance the resistance of crop plants. Therefore, the present experiment was designed to investigate whether the application of Kh and Co could positively affect proline, chlorophyll and mineral elements contents, and antioxidant defense systems which in turn will mitigate the negative impact of water stress under different irrigation strategies. In 2021 and 2022, an open-field experiments were conducted by using a split-plot design. The main plots were divided to represent different irrigation strategies (ST), with additional control of full irrigation requirements (ST1). Four STs were implemented, with ST1, followed by the application of 75%, 50%, and 25% irrigation strategies in ST2, ST3, and ST4 respectively, in the next irrigation, followed by the full requirements, and so on. In the subplots, peanut plants were treated with tap water (Control), Kh at 2 g l-1 and 3 g l-1, Co, Co + Kh 2 g l-1 and Co + Kh 3 g l-1. The yield was negatively affected by the implementation of ST4, despite the increase in proline contents. Furthermore, there was a decrease in relative water content, chlorophyll content, antioxidant enzymes, protein, and mineral nutrient elements. However, the application of Kh or Co showed better improvements in most of the studied parameters. It is worth noting that there was an antagonistic relationship between Co and iron/manganese, and the intensity of this relationship was found to depend on the STs implemented. The highest mineral nutrient accumulation, chlorophyll content, relative water content, protein content, oil content, seed yield, and water productivity were observed when peanut plants were treated with Kh 3 g l-1 + Co under the ST2 water strategy.

Global biogeography and ecological implications of cobamide-producing prokaryotes

Cobamides, a class of essential coenzymes synthesized only by a subset of prokaryotes, are model nutrients in microbial interaction studies and play significant roles in global ecosystems. Yet, their spatial patterns and functional roles remain poorly understood. Herein, we present an in-depth examination of cobamide-producing microorganisms, drawn from a comprehensive analysis of 2862 marine and 2979 soil metagenomic samples. A total of 1934 nonredundant metagenome-assembled genomes (MAGs) potentially capable of producing cobamides de novo were identified. The cobamide-producing MAGs are taxonomically diverse but habitat specific. They constituted only a fraction of all the recovered MAGs, with the majority of MAGs being potential cobamide users. By mapping the distribution of cobamide producers in marine and soil environments, distinct latitudinal gradients were observed: the marine environment showed peak abundance at the equator, whereas soil environments peaked at mid-latitudes. Importantly, significant and positive links between the abundance of cobamide producers and the diversity and functions of microbial communities were observed, as well as their promotional roles in essential biogeochemical cycles. These associations were more pronounced in marine samples than in soil samples, which suggests a heightened propensity for microorganisms to engage in cobamide sharing in fluid environments relative to the more spatially restricted soil environment. These findings shed light on the global patterns and potential ecological roles of cobamide-producing microorganisms in marine and soil ecosystems, enhancing our understanding of large-scale microbial interactions.

Pyrrole: A Decisive Scaffold for the Development of Therapeutic Agents and Structure-Activity Relationship

An overview of pyrroles as distinct scaffolds with therapeutic potential and the significance of pyrrole derivatives for drug development are provided in this article. It lists instances of naturally occurring pyrrole-containing compounds and describes the sources of pyrroles in nature, including plants and microbes. It also explains the many conventional and modern synthetic methods used to produce pyrroles. The key topics are the biological characteristics, pharmacological behavior, and functional alterations displayed by pyrrole derivatives. It also details how pyrroles are used to treat infectious diseases. It describes infectious disorders resistant to standard treatments and discusses the function of compounds containing pyrroles in combating infectious diseases. Furthermore, the review covers the uses of pyrrole derivatives in treating non-infectious diseases and resistance mechanisms in non-infectious illnesses like cancer, diabetes, and Alzheimer's and Parkinson's diseases. The important discoveries and probable avenues for pyrrole research are finally summarized, along with their significance for medicinal chemists and drug development. A reference from the last two decades is included in this review.

Vitamin B12 Deficiency and the Nervous System: Beyond Metabolic Decompensation-Comparing Biological Models and Gaining New Insights into Molecular and Cellular Mechanisms

Vitamin B12 (VitB12) is a micronutrient and acts as a cofactor for fundamental biochemical reactions: the synthesis of succinyl-CoA from methylmalonyl-CoA and biotin, and the synthesis of methionine from folic acid and homocysteine. VitB12 deficiency can determine a wide range of diseases, including nervous system impairments. Although clinical evidence shows a direct role of VitB12 in neuronal homeostasis, the molecular mechanisms are yet to be characterized in depth. Earlier investigations focused on exploring the biochemical shifts resulting from a deficiency in the function of VitB12 as a coenzyme, while more recent studies propose a broader mechanism, encompassing changes at the molecular/cellular levels. Here, we explore existing study models employed to investigate the role of VitB12 in the nervous system, including the challenges inherent in replicating deficiency/supplementation in experimental settings. Moreover, we discuss the potential biochemical alterations and ensuing mechanisms that might be modified at the molecular/cellular level (such as epigenetic modifications or changes in lysosomal activity). We also address the role of VitB12 deficiency in initiating processes that contribute to nervous system deterioration, including ROS accumulation, inflammation, and demyelination. Consequently, a complex biological landscape emerges, requiring further investigative efforts to grasp the intricacies involved and identify potential therapeutic targets.

Design, synthesis, pharmacological evaluation, and in silico studies of the activity of novel spiro pyrrolo[3,4-d]pyrimidine derivatives

In the present study, spiro compounds are shown to have distinctive characteristics because of their interesting conformations and their structural impacts on biological systems. A new family of functionalized spiro pyrrolo[3,4-d]pyrimidines is prepared via the one-pot condensation reaction of amino cyclohexane derivatives with benzaldehyde to prepare fused azaspiroundecanedione and azaspirodecenone/thione derivatives. A series of synthesized spiro compounds were scanned against DPPH and evaluated for their ability to inhibit COX-1 and COX-2. All compounds exhibit significant antiinflammatory activity, and they inhibited both COX-1 and COX-2 enzymes with a selectivity index higher than celecoxib as a reference drug. The most powerful and selective COX-2 inhibitor compounds were 11 and 6, with selectivity indices of 175 and 129.21 in comparison to 31.52 of the standard celecoxib. However, candidate 14 showed a very promising antiinflammatory activity with an IC50 of 6.00, while celecoxib had an IC50 of 14.50. Our findings are promising in the area of medicinal chemistry for further optimization of the newly designed and synthesized compounds regarding the discussed structure-activity relationship study (SAR), in order to obtain a superior antioxidant lead compound in the near future. All chemical structures of the novel synthesized candidates were unequivocally elucidated and confirmed utilizing spectroscopic and elemental investigations.

Cobalt and Titanium Alleviate the Methylglyoxal-Induced Oxidative Stress in Pennisetum divisum Seedlings under Saline Conditions

Salinity is considered to be a global problem and a severe danger to modern agriculture since it negatively impacts plants' growth and development at both cellular- and whole-plant level. However, cobalt (Co) and titanium (Ti), multifunctional non-essential micro-elements, play a crucial role in improving plant growth and development under salinity stress. In the current study, Co and Ti impact on the morphological, biochemical, nutritional, and metabolic profile of Pennisetum divisum plants under three salinity levels which were assessed. Two concentrations of Co (Co-1; 15.0 mg/L and Co-2; 25.0 mg/L), and two concentrations of Ti (Ti-1; 50.0 mg/L and Ti-2; 100.0 mg/L) were applied as foliar application to the P. divisum plants under salinity (S1; 200 mM, S2; 500 mM, and S3; 1000 mM) stress. The results revealed that various morphological, biochemical, and metabolic processes were drastically impacted by the salinity-induced methylglyoxal (MG) stress. The excessive accumulation of salt ions, including Na+ (1.24- and 1.21-fold), and Cl- (1.53- and 1.15-fold) in leaves and roots of P. divisum, resulted in the higher production of MG (2.77- and 2.95-fold) in leaves and roots under severe (1000 mM) salinity stress, respectively. However, Ti-treated leaves showed a significant reduction in ionic imbalance and MG concentrations, whereas considerable improvement was shown in K+ and Ca2+ under salinity stress, and Co treatment showed downregulation of MG content (26, 16, and 14%) and improved the antioxidant activity, such as a reduction in glutathione (GSH), oxidized glutathione (GSSG), Glutathione reductase (GR), Glyoxalase I (Gly I), and Glyoxalase II (Gly II) by up to 1.13-, 1.35-, 3.75-, 2.08-, and 1.68-fold under severe salinity stress in P. divisum roots. Furthermore, MG-induced stress negatively impacted the metabolic profile and antioxidants activity of P. divisum's root and leaves; however, Co and Ti treatment considerably improved the biochemical processes and metabolic profile in both underground and aerial parts of the studied plants. Collectively, the results depicted that Co treatment showed significant results in roots and Ti treatment presented considerable changes in leaves of P. divism under salinity stress.

Occurrence of trace elements in print paper products: Non-carcinogenic risk assessment through dermal exposure

Over time, the risk assessment of dermal exposure to pollutants in print paper products has received considerable attention. Most studies have focused on organic pollutants, especially bisphenol A (BPA). However, little is known about the levels of trace elements in print paper products, despite the knowledge that these elements are components of printing inks and toners. This study was aimed at determining the concentrations of trace elements in 5 types of paper products, namely bulletins, magazines, special events program booklets, handbills, and newspapers. The average daily intake (ADI) of each element was subsequently estimated through dermal exposure to the papers. The detection frequency of the elements of interest was high (nearly 100%) in most paper products, with the exception of chromium, whose detection was low. In contrast, Ag was not detected in any sample. The levels of the elements in the paper products were low and comparable to those found in other personal and consumer products with the potential for skin contact. The range values of estimated ADIs were 1.70-3.90E-08, 2.30-18.2E-10, 2.60-16.4E-09, 3.65-5.75E-08, 1.29-4.38E-08, 6.23-15.6E-10, 1.51-2.80E-10, 1.43-9.16E-09, 0.00-9.47E-09, and 4.68-220E-08 mg/kg bw/day for Mn, Co, Ni, Cu, Zn, As, Cd, Pb, Cr and Fe respectively. These values were well below the dermal standard reference doses (RfD) for each element. The present results indicate that dermal exposure to trace elements from print paper products was low and does not pose significant risks for toxic (non-carcinogenic) effects on humans.

Recent Advances in Dietary Sources, Health Benefits, Emerging Encapsulation Methods, Food Fortification, and New Sensor-Based Monitoring of Vitamin B12: A Critical Review

In this overview, the latest achievements in dietary origins, absorption mechanism, bioavailability assay, health advantages, cutting-edge encapsulation techniques, fortification approaches, and innovative highly sensitive sensor-based detection methods of vitamin B12 (VB12) were addressed. The cobalt-centered vitamin B is mainly found in animal products, posing challenges for strict vegetarians and vegans. Its bioavailability is highly influenced by intrinsic factor, absorption in the ileum, and liver reabsorption. VB12 mainly contributes to blood cell synthesis, cognitive function, and cardiovascular health, and potentially reduces anemia and optic neuropathy. Microencapsulation techniques improve the stability and controlled release of VB12. Co-microencapsulation of VB12 with other vitamins and bioactive compounds enhances bioavailability and controlled release, providing versatile initiatives for improving bio-functionality. Nanotechnology, including nanovesicles, nanoemulsions, and nanoparticles can enhance the delivery, stability, and bioavailability of VB12 in diverse applications, ranging from antimicrobial agents to skincare and oral insulin delivery. Staple food fortification with encapsulated and free VB12 emerges as a prominent strategy to combat deficiency and promote nutritional value. Biosensing technologies, such as electrochemical and optical biosensors, offer rapid, portable, and sensitive VB12 assessment. Carbon dot-based fluorescent nanosensors, nanocluster-based fluorescent probes, and electrochemical sensors show promise for precise detection, especially in pharmaceutical and biomedical applications.

Prevalence of Cobalt in the Environment and Its Role in Biological Processes

Cobalt (Co) is an essential trace element for humans and other animals, but high doses can be harmful to human health. It is present in some foods such as green vegetables, various spices, meat, milk products, seafood, and eggs, and in drinking water. Co is necessary for the metabolism of human beings and animals due to its key role in the formation of vitamin B12, also known as cobalamin, the biological reservoir of Co. In high concentrations, Co may cause some health issues such as vomiting, nausea, diarrhea, bleeding, low blood pressure, heart diseases, thyroid damage, hair loss, bone defects, and the inhibition of some enzyme activities. Conversely, Co deficiency can lead to anorexia, chronic swelling, and detrimental anemia. Co nanoparticles have different and various biomedical applications thanks to their antioxidant, antimicrobial, anticancer, and antidiabetic properties. In addition, Co and cobalt oxide nanoparticles can be used in lithium-ion batteries, as a catalyst, a carrier for targeted drug delivery, a gas sensor, an electronic thin film, and in energy storage. Accumulation of Co in agriculture and humans, due to natural and anthropogenic factors, represents a global problem affecting water quality and human and animal health. Besides the common chelating agents used for Co intoxication, phytoremediation is an interesting environmental technology for cleaning up soil contaminated with Co. The occurrence of Co in the environment is discussed and its involvement in biological processes is underlined. Toxicological aspects related to Co are also examined in this review.

Association between mediterranean diet and metal(loid) exposure in 4-5-year-old children living in Spain

Even relatively low levels of metals exposure may impact health, particularly among vulnerable populations such as infants and young children. However, little is known about the interplay between simultaneous metal exposures, common in real-life scenarios, and their association with specific dietary patterns. In this study, we have evaluated the association between adherence to Mediterranean diet (MD) and urinary metal concentrations individually and as an exposure mixture in 713 children aged 4-5-years from the INMA cohort study. We used a validated food frequency questionnaire to calculate two MD indexes scores: aMED and rMED. These indexes gather information on various food groups within the MD and score differently. To measure urinary concentrations of cobalt, copper, zinc, molybdenum, selenium, lead, and cadmium as exposure biomarkers, we used inductively coupled plasma mass spectrometry (ICP-MS), coupled with an ion chromatography (IC) equipment for arsenic speciation analysis. We applied linear regression and quantile g-computation, adjusted for confounders, to analyse the association between MD adherence and exposure to the metal mixture. High adherence to MD such as the quintile (Q) 5 MD was associated with higher urinary arsenobetaine (AsB) levels than Q1, with β values of 0.55 (confidence interval - CI 95% 0.01; 1.09) for aMED and 0.73 (CI 95% 0.13; 1.33) for rMED. Consumption of fish was associated with increased urinary AsB but reduced inorganic arsenic concentrations. In contrast, the aMED vegetables consumption increased urinary inorganic arsenic content. A moderate level of adherence to MD (Q2 and Q3) was associated with lower copper urinary concentrations than Q1, with β values of -0.42 (CI 95% -0.72; -0.11) for Q2 and -0.33 (CI 95% -0.63; -0.02) for Q3, but only with aMED. Our study, conducted in Spain, revealed that adhering to the MD reduces exposure to certain metals while increasing exposure to others. Specifically, we observed increase in exposure to non-toxic AsB, highlighting the significance of consuming fish/seafood. However, it is crucial to emphasize the necessity for additional efforts in reducing early-life exposure to toxic metals, even when adhering to certain food components of the MD.

Electrostatic interactions - key determinants of the metal selectivity in La3+ and Ca2+ binding proteins

Nearly half of all known proteins contain metal co-factors. In the course of evolution two dozen metal cations (mostly monovalent and divalent species) have been selected to participate in processes of vital importance for living organisms. Trivalent metal cations have also been selected, although to a lesser extent as compared with their mono- and divalent counterparts. Notably, factors governing the metal selectivity in trivalent metal centers in proteins are less well understood than those in the respective divalent metal centers. Thus, the source of high La³⁺/Ca²⁺ selectivity in lanthanum-binding proteins, as compared with that of calcium-binding proteins (i.e., calmodulin), is still shrouded in mystery. The well-calibrated thermochemical calculations, performed here, reveal the dominating role of electrostatic interactions in shaping the metal selectivity in La³⁺-binding centers. The calculations also disclose other (second-order) determinants of metal selectivity in these systems, such as the rigidity and extent of solvent exposure of the binding site. All these factors are also implicated in shaping the metal selectivity in Ca²⁺-binding proteins.

B12 and F430 models: Metal- versus ligand-centered redox in cobalt and nickel tetradehydrocorrin derivatives

DFT calculations with the well-tested OLYP and B3LYP* exchange-correlation functionals (along with D3 dispersion corrections and all-electron ZORA STO-TZ2P basis sets) and careful use of group theory have led to significant insights into the question of metal- versus ligand-centered redox in Co and Ni B,C-tetradehydrocorrin complexes. For the cationic complexes, both metals occur in their low-spin M(II) forms. In contrast, the charge-neutral states vary for the two metals: while the Co(I) and Co^II-TDC^•2- state are comparable in energy for cobalt, a low-spin Ni^II-TDC^•2- state is clearly preferred for nickel. The latter behavior stands in sharp contrast to other corrinoids that reportedly stabilize a Ni(I) center.

Dietary exposure to potentially harmful elements in edible plants in Poland and the health risk dynamics related to their geochemical differentiation

Differences in the health risk values calculated for consumers of potentially harmful elements (PHEs) present in edible plants were investigated. Based on a comprehensive literature search, the highest PHE contents in plants were identified in the southern and western regions of Poland, that also revealed the highest geochemical enrichment with Zn, Pb, Cu, As, Cd, and Tl. The highest unacceptable non-carcinogenic risk (HQ) values for mean PHE contents in Poland were found for Pb: toddlers (2.80), pre-schoolers (1.80), and school-aged children (1.45) and for Cd for toddlers (1.42). The highest unacceptable carcinogenic risk (CR) values for mean As content was observed for adults (5.9 × 10^-5). The highest non-carcinogenic risk values for consumers were reported in Silesia, Lower Silesia, Lublin, Lesser Poland, and Opole Provinces, indicating the impact of geochemical variability on risk values.

Two Distinct Thermodynamic Gradients for Cellular Metalation of Vitamin B12

The acquisition of Co^II by the corrin component of vitamin B₁₂ follows one of two distinct pathways, referred to as early or late Co^II insertion. The late insertion pathway exploits a Co^II metallochaperone (CobW) from the COG0523 family of G3E GTPases, while the early insertion pathway does not. This provides an opportunity to contrast the thermodynamics of metalation in a metallochaperone-requiring and a metallochaperone-independent pathway. In the metallochaperone-independent route, sirohydrochlorin (SHC) associates with the CbiK chelatase to form Co^II-SHC. Co^II-buffered enzymatic assays indicate that SHC binding enhances the thermodynamic gradient for Co^II transfer from the cytosol to CbiK. In the metallochaperone-dependent pathway, hydrogenobyrinic acid a,c-diamide (HBAD) associates with the CobNST chelatase to form Co^II-HBAD. Here, Co^II-buffered enzymatic assays indicate that Co^II transfer from the cytosol to HBAD-CobNST must somehow traverse a highly unfavorable thermodynamic gradient for Co^II binding. Notably, there is a favorable gradient for Co^II transfer from the cytosol to the Mg^IIGTP-CobW metallochaperone, but further transfer of Co^II from the GTP-bound metallochaperone to the HBAD-CobNST chelatase complex is thermodynamically unfavorable. However, after nucleotide hydrolysis, Co^II transfer from the chaperone to the chelatase complex is calculated to become favorable. These data reveal that the CobW metallochaperone can overcome an unfavorable thermodynamic gradient for Co^II transfer from the cytosol to the chelatase by coupling this process to GTP hydrolysis.

A Bifunctional Fluorescence Probe Based on AIE-ICT Strategy for Visual Detection of Cu2+/Co2+ in Complex Matrix

A novel fluorescence chemical sensor-based probe 1-{[(E)-(2-aminophenyl)azanylidene]methyl}naphthalen-2-ol (AMN) was designed and synthesized, which performed a "naked eye" detection ability toward Cu²⁺ and Co²⁺ based on aggregation-induced emission (AIE) fluorescence strategy. It has sensitive detection ability for Cu²⁺ and Co²⁺. In addition, the color changed from yellow-green to orange under the sunlight, realizing the rapid identification of Cu²⁺/Co²⁺, which has the potential of on-site visual detection under the "naked eye". Moreover, different "on" and "off" fluorescence expressions were exhibited under excessive glutathione (GSH) in AMN-Cu²⁺ and AMN-Co²⁺ systems, which could be employed to distinguish Cu²⁺ from Co²⁺. The detection limits for Cu²⁺ and Co²⁺ were measured to be 8.29 × 10^-8 M and 9.13 × 10^-8 M, respectively. The binding mode of AMN was calculated to be 2:1 by Jobs' plot method analysis. Ultimately, the new fluorescence sensor was applied to detect Cu²⁺ and Co²⁺ in real samples (tap water, river water, and yellow croaker), and the results were satisfying. Therefore, this high-efficiency bifunctional chemical sensor platform based on "on-off" fluorescence detection will provide significant guidance for the advance development of single-molecule sensors for multi-ion detection.

The elements of life: A biocentric tour of the periodic table

Living systems are built from a small subset of the atomic elements, including the bulk macronutrients (C,H,N,O,P,S) and ions (Mg,K,Na,Ca) together with a small but variable set of trace elements (micronutrients). Here, we provide a global survey of how chemical elements contribute to life. We define five classes of elements: those that are (i) essential for all life, (ii) essential for many organisms in all three domains of life, (iii) essential or beneficial for many organisms in at least one domain, (iv) beneficial to at least some species, and (v) of no known beneficial use. The ability of cells to sustain life when individual elements are absent or limiting relies on complex physiological and evolutionary mechanisms (elemental economy). This survey of elemental use across the tree of life is encapsulated in a web-based, interactive periodic table that summarizes the roles chemical elements in biology and highlights corresponding mechanisms of elemental economy.

The complex machinery of human cobalamin metabolism

Vitamin B₁₂ (cobalamin, Cbl) is required as a cofactor by two human enzymes, 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) and methylmalonyl-CoA mutase (MMUT). Within the body, a vast array of transporters, enzymes and chaperones are required for the generation and delivery of these cofactor forms. How they perform these functions is dictated by the structure and interactions of the proteins involved, the molecular bases of which are only now being elucidated. In this review, we highlight recent insights into human Cbl metabolism and address open questions in the field by employing a protein structure and interactome based perspective. We discuss how three very similar proteins-haptocorrin, intrinsic factor and transcobalamin-exploit slight structural differences and unique ligand receptor interactions to effect selective Cbl absorption and internalisation. We describe recent advances in the understanding of how endocytosed Cbl is transported across the lysosomal membrane and the implications of the recently solved ABCD4 structure. We detail how MMACHC and MMADHC cooperate to modify and target cytosolic Cbl to the client enzymes MTR and MMUT using ingenious modifications to an ancient nitroreductase fold, and how MTR and MMUT link with their accessory enzymes to sustainably harness the supernucleophilic potential of Cbl. Finally, we provide an outlook on how future studies may combine structural and interactome based approaches and incorporate knowledge of post-translational modifications to bring further insights.

Protein metalation in a nutshell

Metalation, the acquisition of metals by proteins, must avoid mis-metalation with tighter binding metals. This is illustrated by four selected proteins that require different metals: all show similar ranked orders of affinity for bioavailable metals, as described in a universal affinity series (the Irving-Williams series). Crucially, cellular protein metalation occurs in competition with other metal binding sites. The strength of this competition defines the intracellular availability of each metal: its magnitude has been estimated by calibrating a cells' set of DNA-binding, metal-sensing, transcriptional regulators. This has established that metal availabilities (as free energies for forming metal complexes) are maintained to the inverse of the universal series. The tightest binding metals are least available. With these availabilities, correct metalation is achieved.

Rapid metal speciation of cell culture media using reversed-phase separations and inductively coupled plasma optical emission spectrometry

Cell culture media metal content is critical in mammalian cell growth and monoclonal antibody productivity. The variability in metal concentrations has multiple sources of origin. As such, there is a need to analyze media before, during, and after production. Furthermore, it is not the simple presence of a given metal that can impact processes, but also their chemical form that is, speciation. To a first approximation, it is instructive to simply and quickly ascertain if the metals exist as inorganic (free metal) ions or are part of an organometallic complex (ligated). Here we present a simple workflow involving the capture of ligated metals on a fiber stationary phase with passage of the free ions to an inductively coupled plasma optical emission spectrometry for quantification; the captured species are subsequently eluted for quantification. This first level of speciation (free vs. ligated) can be informative towards sources of contaminant metal species and means to assess bioreactor processes.

The DmeRF System Is Involved in Maintaining Cobalt Homeostasis in Vibrio parahaemolyticus

Although cobalt (Co) is indispensable for life, it is toxic to cells when accumulated in excess. The DmeRF system is a well-characterized metal-response system that contributes to Co and nickel resistance in certain bacterial species. The Vibrio parahaemolyticus RIMD 2210633 genome also harbors a dmeRF operon that encodes a multiple antibiotic resistance regulator family transcriptional regulator and a cation diffusion facilitator family protein. Quantitative real-time PCR, growth curves analysis, inductively coupled plasma-mass spectrometry, β-galactosidase activity assays, electrophoretic mobility shift assays, and a mouse infection experiment were performed to characterize the function of the DmeRF system in V. parahaemolyticus. Zinc, copper, and Co significantly increase dmeF expression, with Co inducing the greatest increase. DmeF promotes V. parahaemolyticus growth under high-Co conditions. Additionally, increased accumulation of cellular Co in the ΔdmeF mutant indicates that DmeF is potentially involved in Co efflux. Moreover, DmeR represses the dmeRF operon by binding directly to its promoter in the absence of Co. Finally, the DmeRF system was not required for V. parahaemolyticus virulence in mice. Collectively, our data indicate that the DmeRF system is involved in maintaining Co homeostasis in V. parahaemolyticus and DmeR functioning as a repressor of the operon.

Genomic Landscape Highlights Molecular Mechanisms Involved in Silicate Solubilization, Stress Tolerance, and Potential Growth-Promoting Activity of Bacterium Enterobacter sp. LR6

Silicon (Si) is gaining widespread attention due to its prophylactic activity to protect plants under stress conditions. Despite Si's abundance in the earth's crust, most soils do not have enough soluble Si for plants to absorb. In the present study, a silicate-solubilizing bacterium, Enterobacter sp. LR6, was isolated from the rhizospheric soil of rice and subsequently characterized through whole-genome sequencing. The size of the LR6 genome is 5.2 Mb with a GC content of 54.9% and 5182 protein-coding genes. In taxogenomic terms, it is similar to E. hormaechei subsp. xiangfangensis based on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH). LR6 genomic data provided insight into potential genes involved in stress response, secondary metabolite production, and growth promotion. The LR6 genome contains two aquaporins, of which the aquaglyceroporin (GlpF) is responsible for the uptake of metalloids including arsenic (As) and antimony (Sb). The yeast survivability assay confirmed the metalloid transport activity of GlpF. As a biofertilizer, LR6 isolate has a great deal of tolerance to high temperatures (45 °C), salinity (7%), and acidic environments (pH 9). Most importantly, the present study provides an understanding of plant-growth-promoting activity of the silicate-solubilizing bacterium, its adaptation to various stresses, and its uptake of different metalloids including As, Ge, and Si.

Riboswitch-mediated regulation of riboflavin biosynthesis genes in prokaryotes

Prokaryotic organisms frequently use riboswitches to quantify intracellular metabolite concentration via high-affinity metabolite receptors. Riboswitches possess a metabolite-sensing system that controls gene regulation in a cis-acting fashion at the initiation of transcriptional/translational level by binding with a specific metabolite and controlling various biochemical pathways. Riboswitch binds with flavin mononucleotide (FMN), a phosphorylated form of riboflavin and controls gene expression involved in riboflavin biosynthesis and transport pathway. The first step of the riboflavin biosynthesis pathway is initiated by the conversion of guanine nucleotide triphosphate (GTP), which is an intermediate of the purine biosynthesis pathway. An alternative pentose phosphate pathway of riboflavin biosynthesis includes the enzymatic conversion of ribulose-5-phosphate into 3, 4 dihydroxy-2-butanone-4-phosphates by DHBP synthase. The product of ribAB interferes with both GTP cyclohydrolase II as well as DHBP synthase activities, which catalyze the cleavage of GTP and converts DHBP Ribu5P in the initial steps of both riboflavin biosynthesis branches. Riboswitches are located in the 5' untranslated region (5' UTR) of messenger RNAs and contain an aptamer domain (highly conserved in sequence) where metabolite binding leads to a conformational change in an aptamer domain, which modulate the regulation of gene expression located on bacterial mRNA. In this review, we focus on how riboswitch regulates the riboflavin biosynthesis pathway in Bacillus subtilis and Lactobacillus plantarum.

Beneficial effects of vitamin B12 treatment in pediatric patients diagnosed with vitamin B12 deficiency regarding total-native thiol, oxidative stress, and mononuclear leukocyte DNA damage

Vitamin B₁₂ is involved in biochemical metabolic pathways. B₁₂ deficiency is common in childhood when the need for the vitamin increases and growth and development occur. Various hematological, neurological, psychiatric, and gastrointestinal disorders are observed in its deficiency. In addition, B₁₂ deficiency is associated with oxidative stress and DNA damage. Therefore, the aim of our study is to evaluate oxidative stress, thiol/disulfide homeostasis, and DNA damage pre and post-treatment in children diagnosed with B₁₂ deficiency. A total of 40 children with B₁₂ deficiency were included in the study after the consent form was approved. Blood was drawn from children pre and posttreatment. Hemoglobin (HGB), hematocrit (HCT), and red blood cells (RBC) were measured by autoanalyzer; total antioxidant status (TAS), total oxidant status (TOS), total thiol (TT), and native thiol (NT) were measured by the photometric method, and DNA damage was analyzed by the comet assay method. Oxidative stress index (OSI) and disulfide (DIS) values were calculated. As a result of the experiments, HGB, HCT, and RBC increased with treatment. While TAS, TT, and NT as antioxidant parameters increased; TOS, OSI, and DIS decreased with treatment compared to pretreatment. DNA damage was also found to decrease with treatment. Additionally, these data were statistically significant (p < 0.001). It was found that oxidative stress and DNA damage decreased with oral B₁₂ treatment in children with B₁₂ deficiency, and clinical parameters were also improved.

Atypical Serogroup IVb-v1 of Listeria monocytogenes Assigned to New ST2801, Widely Spread and Persistent in the Environment of a Pork-Meat Producing Plant of Central Italy

In this study, we characterized 84 Listeria monocytogenes (Lm) strains having an atypical IVb-v1 profile and isolated in a meat producing plant of Central Italy. They were assigned to the new MLST type ST2801 (CC218). The new ST was widespread in the food-producing environment where it was able to persist for over a year even after cleaning and sanitation. Cluster analysis identified three main clusters genetically close to each other (0-22 allelic differences and 0-28 SNPs) from two different cgMLST types, suggesting a common source. The coexistence of closely related clusters over time could be the result of a different evolution path starting from a common ancestor first introduced in the plant and/or the consequence of the repetitive reintroduction of closely related clones probably by raw materials. All the strains presented several determinants for heavy metals resistance, stress response, biofilm production, and multidrug efflux pumps with no significant differences among the clusters. A total of 53 strains carried pLI100 and the j1776 plasmids, while in one strain, the pLM33 was found in addition to pLI100. Only the strains carrying plasmids presented cadA and cadC for cadmium resistance and the mco gene encoding a multicopper oxidase and gerN for an additional Na+/H+-K+ antiporter. All the strains presented a virulence profile including a full-length inlA gene and the additional LIPI-3. The isolation of a new ST with a large pattern of stress-adaptation genes and able to persist is an important contribution to deepening the current knowledge on the uncommon IVb-v1 and in general on the genomic diversity of Lm.

Cobalt protoporphyrin promotes human keratinocyte migration under hyperglycemic conditions

Background

Complete healing of diabetic wounds continues to be a clinically unmet need. Although robust therapies such as stem cell therapy and growth factor treatment are clinically applied, these treatments are costly for most diabetic wound patients. Therefore, a cheaper alternative is needed. Cobalt protoporphyrin (CoPP) has recently been demonstrated to promote tissue regeneration. In this study, the therapeutic benefits of CoPP in diabetic wound healing were examined.

Methods

An in vitro wound healing model that mimics re-epithelialization was established to examine the effect of CoPP on the migratory capability of human keratinocytes (HaCaT) in either normal glucose (NG) or high glucose (HG) media, as well as in the presence of either H₂O₂ or lipopolysaccharide (LPS). At the end of the migration assays, cells were collected and subjected to Western blotting analysis and immunostaining.

Results

HaCaT were found to migrate significantly more slowly in the HG media compared to the NG media. CoPP treatment was found to enhance cell migration in HG media, but was found to decrease cell migration and proliferation when HaCaT were cultured in NG media. CoPP treatment induced high levels of expression of Nrf-2/HO-1 and FoxO1 in HaCaT cultured in either glucose concentration, although the FoxO1 expression was found to be significantly higher in HaCaT that underwent the migration assay in NG media compared to those in HG media. The higher level of FoxO1 expression seen in CoPP-treated HaCaT cultured in NG media resulted in upregulation of CCL20 and downregulation of TGFβ1. In contrast, HaCaT migrated in HG media were found to have high levels of expression of TGFβ1, and low levels of expression of CCL20. Interestingly, in the presence of H₂O₂, CoPP-pretreated HaCaT cultured in either NG or HG media had similar expression level of Nrf-2/HO-1 and FoxO1 to each other. Moreover, the anti-apoptotic effect of CoPP pretreatment was noticed in HaCaT cultured in either glucose concentration. Additionally, CoPP pretreatment was shown to promote tight junction formation in HaCaT suffering from LPS-induced damage.

Conclusions

CoPP enhances cell migratory capacity under hyperglycemic conditions, and protects cells from oxidative and LPS-induced cellular damage in HG media containing either H₂O₂ or LPS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00499-0.

Vitamin B12 photoreceptors

Photoreceptor proteins enable living organisms to sense light and transduce this signal into biochemical outputs to elicit appropriate cellular responses. Their light sensing is typically mediated by covalently or noncovalently bound molecules called chromophores, which absorb light of specific wavelengths and modulate protein structure and biological activity. Known photoreceptors have been classified into about ten families based on the chromophore and its associated photosensory domain in the protein. One widespread photoreceptor family uses coenzyme B₁₂ or 5'-deoxyadenosylcobalamin, a biological form of vitamin B₁₂, to sense ultraviolet, blue, or green light, and its discovery revealed both a new type of photoreceptor and a novel functional facet of this vitamin, best known as an enzyme cofactor. Large strides have been made in our understanding of how these B₁₂-based photoreceptors function, high-resolution structural descriptions of their functional states are available, as are details of their unusual photochemistry. Additionally, they have inspired notable applications in optogenetics/optobiochemistry and synthetic biology. Here, we provide an overview of what is currently known about these B₁₂-based photoreceptors, their discovery, distribution, molecular mechanism of action, and the structural and photochemical basis of how they orchestrate signal transduction and gene regulation, and how they have been used to engineer optogenetic control of protein activities in living cells.

Mucilaginibacter sp. Strain Metal(loid) and Antibiotic Resistance Isolated from Estuarine Soil Contaminated Mine Tailing from the Fundão Dam

In 2015 a mine dam with Mn-Fe-rich tailings collapsed releasing million tons of sediments over an estuary, in the Southwest of Brazil. The tailings have a high concentration of metals that contaminated soil until the present day. The high contaminant concentrations possibly caused a selection for microorganisms able to strive in such harsh conditions. Here, we isolated metal(loid) and anti-biotic resistance bacteria from the contaminated estuarine soil. After 16S rDNA sequencing to identify the strains, we selected the Mucilaginibacter sp. strain for a whole-genome sequence due to the bioprospective potential of the genus and the high resistance profile. We obtained a complete genome and a genome-guided characterization. Our finding suggests that the 21p strain is possibly a new species of the genus. The species presented genes for resistance for metals (i.e., As, Zn, Co, Cd, and Mn) beyond resistance and cross-resistance for antibiotics (i.e., quinolone, aminoglycoside, β-lactamase, sulphonamide, tetracycline). The Mucilaginibacter sp. 21p description as new species should be further explored, as their extracellular polymeric substances and the potential of this strain as bioremediation and as a growth promoter in high met-al(loid) contaminated soil.

ICP-MS Assessment of Essential and Toxic Trace Elements in Foodstuffs with Different Geographic Origins Available in Romanian Supermarkets

The present study was conducted to quantify the daily intake and target hazard quotient of four essential elements, namely, chromium, cobalt, nickel, and copper, and four toxic trace elements, mercury, cadmium, lead, and arsenic. Thirty food items were assigned to five food categories (seeds, leaves, powders, beans, and fruits) and analyzed using inductively coupled plasma-mass spectrometry. Factor analysis after principal component extraction revealed common metal patterns in all foodstuffs, and using hierarchical cluster analysis, an association map was created to illustrate their similarity. The results indicate that the internationally recommended dietary allowance was exceeded for Cu and Cr in 27 and 29 foodstuffs, respectively. According to the tolerable upper level for Ni and Cu, everyday consumption of these elements through repeated consumption of seeds (fennel, opium poppy, and cannabis) and fruits (almond) can have adverse health effects. Moreover, a robust correlation between Cu and As (p < 0.001) was established when all samples were analyzed. Principal component analysis (PCA) demonstrated an association between Pb, As, Co, and Ni in one group and Cr, Cu, Hg, and Cd in a second group, comprising 56.85% of the total variance. For all elements investigated, the cancer risk index was within safe limits, highlighting that lifetime consumption does not increase the risk of carcinogens.

Global Analysis of the Zinc Homeostasis Network in Pseudomonas aeruginosa and Its Gene Expression Dynamics

Zinc is one of the most important trace elements for life and its deficiency, like its excess, can be fatal. In the bacterial opportunistic pathogen Pseudomonas aeruginosa, Zn homeostasis is not only required for survival, but also for virulence and antibiotic resistance. Thus, the bacterium possesses multiple Zn import/export/storage systems. In this work, we determine the expression dynamics of the entire P. aeruginosa Zn homeostasis network at both transcript and protein levels. Precisely, we followed the switch from a Zn-deficient environment, mimicking the initial immune strategy to counteract bacterial infections, to a Zn-rich environment, representing the phagocyte metal boost used to eliminate an engulfed pathogen. Thanks to the use of the NanoString technology, we timed the global silencing of Zn import systems and the orchestrated induction of Zn export systems. We show that the induction of Zn export systems is hierarchically organized as a function of their impact on Zn homeostasis. Moreover, we identify PA2807 as a novel Zn resistance component in P. aeruginosa and highlight new regulatory links among Zn-homeostasis systems. Altogether, this work unveils a sophisticated and adaptive homeostasis network, which complexity is key in determining a pathogen spread in the environment and during host-colonization.