Magnesium supplementation and iron status among female students: The intervention study

BackgroundLiterature data indicate the benefit of magnesium (Mg) supplementation. The aim of this study was to examine the effect of short-term Mg supplementation on iron status in healthy female participants.MethodsOne hundred healthy female students of the University of Belgrade - Faculty of Pharmacy participated the study during eleven intervention days. Students ingested Mg preparations with the same dose of the active substance. The analysis included the measurement of serum iron, unsaturated iron binding capacity (UIBC), total iron binding capacity (TIBC), total Mg (tMg), ionized Mg (iMg), complete blood count, met-, carboxyand oxy-haemoglobin (metHgb, COHgb, O2Hgb). Transferrin concentrations and percentage of transferrin saturation (SAT) were calculated manually. The association among the analyzed biochemical parameters was examined using polynomial regression. A principal component analysis (PCA) was used for the evaluation of interdependence between the analyzed parameters.ResultsA statistically significant trend for change in O2Hgb (%) by tertiles of iMg concentrations was found (P = 0.029). Serum tMg reached significant positive correlation with the SAT at concentration levels greater than 0.9 mmol/L, after 11 days of intervention (R2=0.116). Ionized Mg in a concentration higher than 0.6 mmol/L is positively correlated with SAT and serum Fe (R2=0.214; 0.199, respectively). PCA revealed variability of 64.7% for two axes after 11 days.ConclusionsMg supplementation leads to an improvement in the certain iron status parameters even in individuals with optimal levels of these indices. However, caution should be exercised when supplementing Mg, and laboratory monitoring of the interaction is required.     

Cbp1, a fungal virulence factor under positive selection,forms an effector complex that drives macrophage lysis

Intracellular pathogens secrete effectors to manipulate their host cells. Histoplasma capsulatum (Hc) is a fungal intracellular pathogen of humans that grows in a yeast form in the host. Hc yeasts are phagocytosed by macrophages, where fungal intracellular replication precedes macrophage lysis. The most abundant virulence factor secreted by Hc yeast cells is Calcium Binding Protein 1 (Cbp1), which is absolutely required for macrophage lysis. Here we take an evolutionary, structural, and cell biological approach to understand Cbp1 function. We find that Cbp1 is present only in the genomes of closely related dimorphic fungal species of the Ajellomycetaceae family that lead primarily intracellular lifestyles in their mammalian hosts (Histoplasma, Paracoccidioides, and Emergomyces), but not conserved in the extracellular fungal pathogen Blastomyces dermatitidis. We observe a high rate of fixation of non-synonymous substitutions in the Cbp1 coding sequences, indicating that Cbp1 is under positive selection. We determine the de novo structures of Hc H88 Cbp1 and the Paracoccidioides americana (Pb03) Cbp1, revealing a novel “binocular” fold consisting of a helical dimer arrangement wherein two helices from each monomer contribute to a four-helix bundle. In contrast to Pb03 Cbp1, we show that Emergomyces Cbp1 orthologs are unable to stimulate macrophage lysis when expressed in the Hc cbp1 mutant. Consistent with this result, we find that wild-type Emergomyces africanus yeast are able to grow within primary macrophages but are incapable of lysing them. Finally, we use subcellular fractionation of infected macrophages and indirect immunofluorescence to show that Cbp1 localizes to the macrophage cytosol during Hc infection, making this the first instance of a phagosomal human fungal pathogen directing an effector into the cytosol of the host cell. We additionally show that Cbp1 forms a complex with Yps-3, another known Hc virulence factor that accesses the cytosol. Taken together, these data imply that Cbp1 is a fungal virulence factor under positive selection that localizes to the cytosol to trigger host cell lysis.     

Six years of wild bee monitoring shows changes in biodiversity within and across years and declines in abundance

Wild bees form diverse communities that pollinate plants in both native and agricultural ecosystems making them both ecologically and economically important. The growing evidence of bee declines has sparked increased interest in monitoring bee community and population dynamics using standardized methods. Here, we studied the dynamics of bee biodiversity within and across years by monitoring wild bees adjacent to four apple orchard locations in Southern Pennsylvania, USA. We collected bees using passive Blue Vane traps continuously from April to October for 6 years (2014–2019) amassing over 26,000 bees representing 144 species. We quantified total abundance, richness, diversity, composition, and phylogenetic structure. There were large seasonal changes in all measures of biodiversity with month explaining an average of 72% of the variation in our models. Changes over time were less dramatic with years explaining an average of 44% of the variation in biodiversity metrics. We found declines in all measures of biodiversity especially in the last 3 years, though additional years of sampling are needed to say if changes over time are part of a larger trend. Analyses of population dynamics over time for the 40 most abundant species indicate that about one third of species showed at least some evidence for declines in abundance. Bee family explained variation in species‐level seasonal patterns but we found no consistent family‐level patterns in declines, though bumble bees and sweat bees were groups that declined the most. Overall, our results show that season‐wide standardized sampling across multiple years can reveal nuanced patterns in bee biodiversity, phenological patterns of bees, and population trends over time of many co‐occurring species. These datasets could be used to quantify the relative effects that different aspects of environmental change have on bee communities and to help identify species of conservation concern.     

Uncoupling protein-3 (UCP3) mRNA expression in reconstituted human muscle after myoblast transplantation in RAG2-/-/gamma c/C5(-) immunodeficient mice

Uncoupling protein-3 (UCP3), which is expressed abundantly in skeletal muscle, is one of the carrier proteins dissipating the transmitochondrial electrochemical gradient as heat and has therefore been implicated in the regulation of energy metabolism. Myoblasts or differentiated muscle cells in vitro expressed little if any UCP3, compared with the levels detected in biopsies of skeletal muscle. In the present report, we sought to investigate UCP3 mRNA expression in human muscle generated by myoblast transplantation in the skeletal muscle of an immunodeficient mouse model. Time course experiments demonstrated that 7-8 weeks following transplantation fully differentiated human muscle fibers were formed. The presence of differentiated human muscle fibers was assessed by quantitative PCR measurement of the human alpha-actin mRNA together with immunohistochemical staining using specific antibodies for spectrin and the slow adult myosin heavy chain. Interestingly, we found that the expression of UCP3 mRNA was dependant on human muscle differentiation and that the UCP3 mRNA level was comparable with that found in human muscle biopsies. Moreover, the human UCP3 (hUCP3) promoter seems to be fully functional, since triiodothyronine treatment of the mice not only stimulated the mouse UCP3 (mUCP3) mRNA expression but also strongly stimulated the hUCP3 mRNA expression in human fibers formed after myoblast transplantation. To our knowledge, this is the first time that primary myoblasts could be induced to express the UCP3 gene at a level comparable of that found in human muscle fibers.     

The sensitivity of ABI2 to hydrogen peroxide links the abscisic acid-response regulator to redox signalling

ABI1 and ABI2 are two protein serine/threonine phosphatases of type 2C (EC 3.1.3.16) that act as key regulators in the responses of Arabidopsis thaliana (L.) Heynh. to abscisic acid (ABA). They are involved in the control of ABA-mediated seed dormancy, stomatal closure and vegetative growth inhibition. Analysis of the enzymatic properties of ABI2 revealed high sensitivities towards protons and unsaturated fatty acids. Furthermore, the protein phosphatase activity of ABI2 is very sensitive to H2O2, which has recently emerged as a secondary messenger of ABA signalling. Upon H2O2 challenge, ABI2 is rapidly inactivated with an IC50 value of 50 microM in the presence of reduced glutathione. Inhibitor studies with phenylarsine oxide and manipulation of the redox status of ABI2 in vitro indicate that oxidation of critical cysteine residue(s) is responsible for inactivation. The levels of the major cellular thiol compounds cysteine and glutathione in leaves and seedlings of A. thaliana are compatible with a physiological role of H2O2 in regulating ABI2 activity. ABI2 is considered to exert negative regulation on ABA action. Thus, transient inactivation of this protein phosphatase by H2O2 would allow or enhance the ABA-dependent signalling process. In conclusion, ABI2 represents a likely target for redox-regulation of a hormonal signalling pathway in higher plants.     

Genetic Screens Identify Host Factors for SARS-CoV-2 and Common Cold Coronaviruses

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Biological soil crusts in ecological restoration: emerging research and perspectives

Drylands encompass over 40% of terrestrial ecosystems and face significant anthropogenic degradation causing a loss of ecosystem integrity, services, and deterioration of social‐ecological systems. To combat this degradation, some dryland restoration efforts have focused on the use of biological soil crusts (biocrusts): complex communities of cyanobacteria, algae, lichens, bryophytes, and other organisms living in association with the top millimeters of soil. Biocrusts are common in many ecosystems and especially drylands. They perform a suite of ecosystem functions: stabilizing soil surfaces to prevent erosion, contributing carbon through photosynthesis, fixing nitrogen, and mediating the hydrological cycle in drylands. Biocrusts have emerged as a potential tool in restoration; developing methods to implement effective biocrust restoration has the potential to return many ecosystem functions and services. Although culture‐based approaches have allowed researchers to learn about the biology, physiology, and cultivation of biocrusts, transferring this knowledge to field implementation has been more challenging. A large amount of research has amassed to improve our understanding of biocrust restoration, leaving us at an opportune time to learn from one another and to join approaches for maximum efficacy. The articles in this special issue improve the state of our current knowledge in biocrust restoration, highlighting efforts to effectively restore biocrusts through a variety of different ecosystems, across scales and utilizing a variety of lab and field methods. This collective work provides a useful resource for the scientific community as well as land managers.     

CAPABILITY OF TUBULIN AND MICROTUBULES TO INCORPORATE AND TO RELEASE TYROSINE AND PHENYLALANINE AND THE EFFECT OF THE INCORPORATION OF THESE AMINO ACIDS ON TUBULIN ASSEMBLY

Abstract— Incorporation of [¹⁴C]tyrosine into the C-terminal position of α-tubulin of rat brain cytosol was 10-fold higher for non-assembled than for assembled tubulin. The incorporation into tubulin from disassembled microtubules was higher than into non-assembled tubulin; therefore, the low incorporation into microtubules was not due to a lower acceptor capacity of their tubulin constituent.
[¹⁴C]Tyrosine was released from assembled and non-assembled [¹⁴C]tyrosinated tubulin by the action of an endogenous carboxypeptidase. Release from non-assembled tubulin was shown by incubating a tubulinyl-[¹⁴C]tyrosine preparation in the presence of CaCl₂ at a concentration that abolished microtubule formation. Release from microtubules was inferred from the observation that the percentages of [¹⁴C]tyrosine released and the decrease of the specific radioactivity of the recovered microtubules were practically identical and did not change after a 10-fold dilution of the incubated microtubules.
[³H]Phenylalanine was released from a preparation of tubulinyl-[³H]phenylalanine also by an enzymatic activity.
The capacity of a tubulin preparation to incorporate tyrosine was increased 43% by pre-treatment with endogenous carboxypeptidase.
Tubulin tyrosinated in vitro was assembled to the same extent as native tubulin. After a mixture of tubulinyl-[¹⁴C]tyrosine and tubulinyl-[³H]phenylalanine was partially assembled, the ratio of ¹⁴C/³H found in the microtubules was the same as in the non-assembled tubulin fraction.     

Periplasmic localization of nicotinate phosphoribosyltransferase in Escherichia coli.

Nicotinate phosphoribosyltransferase (NAPRTase) in Escherichia coli mediates the formation of nicotinate mononucleotide, a direct precursor of nicotinamide adenine dinucleotide (NAD), from nicotinate and 5-phosphoribosyl-1-pyrophosphate. Specifically, NAPRTase contributes to NAD synthesis by utilizing intracellular nicotinate formed from NAD degradation products, which are recycled by NAD cycle enzymes and exogenous nicotinate when it is available. In previous studies, it has been tacitly assumed that almost all NAD cycle enzymes are localized in the cytoplasm of E. coli. The results of this investigation provide evidence that NAPRTase is a periplasmic (extracytoplasmic) enzyme. The osmotic shock of exponential-phase cells of E. coli K-12 and ML 308-225 resulted in the release of 63 to 72% and 42 to 48%, respectively, of the NAPRTase into the shock medium. In addition, when exponential cells of strains K-12 and ML 308-225 were converted into spheroplasts, 75 to 84% and 54 to 68%, respectively, of the enzyme was released into the spheroplast medium. Since previous estimates of the effective levels of NAPRTase present in putative repressed and derepressed E. coli cells appeared to be very low, a more convenient and accurate alternative method for the evaluation of NAPRTase in whole cells was developed. The results show that NAPRTase is subject only to a modest degree of enzyme repression. In addition, no evidence was found for the presence of a protein or low-molecular-weight inhibitor of the enzyme in repressed cells.