Escape of volcanic gas into shallow groundwater systems at Unzen Volcano (Japan): evidence from chemical and stable carbon isotope compositions of dissolved inorganic carbon

 Chemical and stable carbon isotopic analyses of dissolved inorganic carbon (DIC) were carried out for groundwater samples collected from cold springs and shallow wells in the Unzen volcanic region in 1999 and 2000. All of the data sets plotted on the carbon isotope ratio (δ¹³C) vs 1/DIC diagram can be explained by mixing of volcanic CO₂ with DIC equilibrated with soil CO₂. Groundwater DIC showing a high mixing ratio of volcanic CO₂ appears to have a tendency to distribute along two major faults near the activity center of the 1990–1995 eruption. This suggests that these faults are escape routes of volcanic CO₂ diffused into the volcanic edifice. The total flux of the volcanic DIC discharged from the cold springs is shown to be one to two orders of magnitude lower than the roughly estimated flux of volcanic CO₂ discharged from the summit during the eruptive period. Received: November 10, 2001 / Accepted: June 6, 2002 Acknowledgments The Unzen Scientific Drilling Project, Ministry of Education, Culture, Sports, Science and Technology (Japan), provided funding. We acknowledge G. Lyon and W. Gooley for stable carbon isotope measurement, K. Amita for DIC analysis, and students of Kyoto University and Okayama University of Science for assistance in field work. Correspondence to:S. Ohsawa     

Distribution of cellular isoform of prion protein in T lymphocytes and bone marrow, analyzed by wild-type and prion protein gene-deficient mice

In this study, the authors investigated normal cellular prion protein (PrP(C)) expression on murine immune systems using prion protein gene-deficient mouse as negative control. Immunocytes expressing PrP(C) in adult and fetal mice were detected by flow cytometry with the monoclonal antibody against PrP(C), 6H4. Cells from thymus and bone marrow reacted positively with 6H4, while spleen cells, peritoneal cells, peripheral blood leukocytes, and intestinal intraepithelial lymphocytes were nonreactive. In thymus, PrP(C) was observed in CD4(-)CD8(-) double-negative thymocytes. PrP(C+) cells of double-negative thymocytes belonged to the CD3(-) subset, but not to the CD3(+) subset. Triple-negative PrP(C+) thymocytes expressed CD44 or CD25 antigens. Furthermore, PrP(C) was observed in c-kit(+) bone marrow cells. In fetuses, PrP(C+) cells were observed in the liver and thymus at day 16.0 and 15.0 of gestation, respectively. These results demonstrated that PrP(C) is expressed on immature immunocytes.     

Enhanced infectivity of HIV-1 by X4 HIV-1 coinfection

Two strains of human immunodeficiency virus type 1 (HIV-1) expressing different reporters, human placental alkaline phosphatase (PLAP) and murine heat stable antigen (HSA, CD24), were used for dual infection. Flow cytometric analysis enabled us to distinguish cells not only infected with individual reporter virus but also superinfected with both reporter viruses. When the CD4 positive T cell line, PM1, was dually infected by both reporter viruses with different coreceptor utilization, coinfection with CXCR4-tropic HIV-1 (X4 HIV-1) expressing one reporter increased the rate of cells infected with HIV-1 expressing another reporter. This enhancement was accompanied by an increased level of p24 antigen Gag in culture supernatant, indicating that infectivity of HIV-1 was augmented by X4 HIV-1 coinfection. The CXCR4 antagonist, T140 eliminated this enhancement, suggesting the role of X4 envelope via CXCR4. These results imply the role of X4 HIV-1 at the late stage of infection.     

KIR2DL4 is an IL-2-regulated NK cell receptor that exhibits limited expression in humans but triggers strong IFN-gamma production

Killer cell Ig-like receptor (KIR)2DL4 (2DL4, CD158d) was previously described as the only KIR expressed by every human NK cell. It is also structurally atypical among KIRs because it possesses a basic transmembrane residue, which is characteristic of many activating receptors, but also contains a cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM). We expressed epitope-tagged 2DL4 in an NK-like cell line to study receptor function. Three distinct 2DL4 cDNA clones were analyzed: one encoding the "conventional" 2DL4 with the cytoplasmic ITIM (2DL4.1) and two encoding different cytoplasmic truncated forms lacking the ITIM (2DL4.2 and 2DL4(*)). Surprisingly, one truncated receptor (2DL4.2), which is the product of a prevalent human 2DL4 allele, was not expressed on the cell surface, indicating that some individuals may lack functional 2DL4 protein expression. Conversely, both 2DL4.1 and 2DL4(*) were expressed on the cell surface and up-regulated by IL-2. Analysis of primary NK cells with anti-2DL4 mAb confirmed the lack of surface expression in a donor with the 2DL4.2 genotype. Donors with the 2DL4.1 genotype occasionally expressed receptor only on CD56(high) NK cells, although their expression was up-regulated by IL-2. Interestingly, Ab engagement of epitope-tagged 2DL4 triggered rapid and robust IFN-gamma production, but weak redirected cytotoxicity in an NK-like cell line, which was the opposite pattern to that observed upon engagement of another NK cell activating receptor, NKp44. Importantly, both 2DL4.1 and 2DL4(*) exhibited similar activation potential, indicating that the ITIM does not influence 2DL4.1 activating function. The unique activation properties of 2DL4 suggest linkage to a distinct signaling pathway.     

Differences in mRNA-1273 (Moderna) and BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 vaccine immunogenicity among patients undergoing dialysis

Background:Differences in immunogenicity between mRNA SARS-CoV-2 vaccines have not been well characterized in patients undergoing dialysis. We compared the serologic response in patients undergoing maintenance hemodialysis after vaccination against SARS-CoV-2 with BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna).Methods:We conducted a prospective observational cohort study at 2 academic centres in Toronto, Canada, from Feb. 2, 2021, to July 20, 2021, which included 129 and 95 patients who received the BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines, respectively. We measured SARS-CoV-2 immunoglobulin G antibodies to the spike protein (anti-spike), receptor binding domain (anti-RBD) and nucleocapsid protein (anti-NP) at 6–7 and 12 weeks after the second dose of vaccine and compared those levels with the median convalescent serum antibody levels from 211 controls who were previously infected with SARS-CoV-2.Results:At 6–7 weeks after 2-dose vaccination, we found that 51 of 70 patients (73%) who received BNT162b2 and 83 of 87 (95%) who received mRNA-1273 attained convalescent levels of anti-spike antibody (p < 0.001). In those who received BNT162b2, 35 of 70 (50%) reached the convalescent level for anti-RBD compared with 69 of 87 (79%) who received mRNA-1273 (p < 0.001). At 12 weeks after the second dose, anti-spike and anti-RBD levels were significantly lower in patients who received BNT162b2 than in those who received mRNA-1273. For anti-spike, 70 of 122 patients (57.4%) who received BNT162b2 maintained the convalescent level versus 68 of 71 (96%) of those who received mRNA-1273 (p < 0.001). For anti-RBD, 47 of 122 patients (38.5%) who received BNT162b2 maintained the anti-RBD convalescent level versus 45 of 71 (63%) of those who received mRNA-1273 (p = 0.002).Interpretation:In patients undergoing hemodialysis, mRNA-1273 elicited a stronger humoral response than BNT162b2. Given the rapid decline in immunogenicity at 12 weeks in patients who received BNT162b2, a third dose is recommended in patients undergoing dialysis as a primary series, similar to recommendations for other vulnerable populations.

Patients with end-stage kidney disease who are receiving maintenance hemodialysis (HD) are at increased risk for severe COVID-19, with mortality rates ranging from 9% to 28%.^1,2 Highly effective vaccines have been developed against SARS-CoV-2, with 94.1%–95% efficacy in reducing the risk of severe COVID-19 (D614G strain) as confirmed by 2 large randomized controlled trials; however, these studies included limited numbers of patients with kidney disease.^3,4 Humoral response to vaccination appears to be heterogeneous in dialysis patients in comparison with the general population, and a review of 35 studies involving dialysis patients found that in the 1-month period after 2-dose vaccination, seroconversion rates ranged from 70% to 96%.⁵The BNT162b2 (Pfizer BioNTech) and mRNA-1273 (Moderna) SARS-CoV-2 vaccines are both lipid nanoparticle-encapsulated, nucleoside-modified mRNA encoding for the full-length SARS-CoV-2 spike protein stabilized in its prefusion conformation. The BNT162b2 vaccine is administered as a 30 μg dose 21 days apart and mRNA-1273 is administered as a 100 μg dose 28 days apart.^3,4 The spike protein and its receptor-binding domain of SARS-CoV-2 are antigens that are targeted by the currently available vaccines and are used as measures of humoral response to vaccination or natural infection. An antibody response to the amount of nucleocapsid protein (NP), which is not targeted by mRNA SARS-CoV-2 vaccines, may be used as a marker of natural exposure to SARS-CoV-2.Recognition of the high morbidity and mortality from COVID-19 and reduced immunogenicity to vaccination against SARS-CoV-2 in patients undergoing HD has resulted in the prioritization of vaccination of this population in many jurisdictions.^1,6 However, differences in immunogenicity among SARS-CoV-2 vaccines have not been well characterized in this vulnerable population. Therefore, we conducted a prospective observational study in a cohort of patients undergoing dialysis who received either the mRNA-1273 or BNT162b2 vaccine to evaluate humoral response through comparison of spike and receptor-binding domain antibodies in response to 2-dose vaccination.     

Total biosynthesis of antitumor nonribosomal peptides in Escherichia coli

Nonribosomal peptides (NRPs) are a class of microbial secondary metabolites that have a wide variety of medicinally important biological activities, such as antibiotic (vancomycin), immunosuppressive (cyclosporin A), antiviral (luzopeptin A) and antitumor (echinomycin and triostin A) activities. However, many microbes are not amenable to cultivation and require time-consuming empirical optimization of incubation conditions for mass production of desired secondary metabolites for clinical and commercial use. Therefore, a fast, simple system for heterologous production of natural products is much desired. Here we show the first example of the de novo total biosynthesis of biologically active forms of heterologous NRPs in Escherichia coli. Our system can serve not only as an effective and flexible platform for large-scale preparation of natural products from simple carbon and nitrogen sources, but also as a general tool for detailed characterizations and rapid engineering of biosynthetic pathways for microbial syntheses of novel compounds and their analogs.     

Laser photolysis of carboxymethylated chitin derivatives in aqueous solution. Part 2. Reaction of OH* and SO4*- radicals with carboxymethylated chitin derivatives

The reactions of OH* or SO4*- radicals with carboxymethyl chitin (CM-chitin) and its deacetylated product, carboxymethyl chitosan (CM-chitosan), were investigated in aqueous solutions using a laser photolysis technique. The rate constants of the reactions of OH* and SO4*- radicals with CM-chitosan are always higher than those for CM-chitin, indicating that the amino-group could increase the reactivity of carboxymethylated chitin derivatives. The rate of the reactions of CM-chitin and CM-chitosan with OH* radical was found to decrease at lower pH when polymers chains tend to the coiled conformation. In comparison, the rate constant of the reaction of SO4*- radicals with CM-chitin or CM-chitosan decreased with pH, indicating that CM-chitin or CM-chitosan has a higher reactivity with the SO4*- radical at low pH due to the protonation of the amino group.     

Crystal structure of mevalonate 3,5-bisphosphate decarboxylase reveals insight into the evolution of decarboxylases in the mevalonate metabolic pathways

Mevalonate 3,5-bisphosphate decarboxylase is involved in the recently discovered Thermoplasma-type mevalonate pathway. The enzyme catalyzes the elimination of the 3-phosphate group from mevalonate 3,5-bisphosphate as well as concomitant decarboxylation of the substrate. This entire reaction of the enzyme resembles the latter half-reactions of its homologs, diphosphomevalonate decarboxylase and phosphomevalonate decarboxylase, which also catalyze ATP-dependent phosphorylation of the 3-hydroxyl group of their substrates. However, the crystal structure of mevalonate 3,5-bisphosphate decarboxylase and the structural reasons of the difference between reactions catalyzed by the enzyme and its homologs are unknown. In this study, we determined the X-ray crystal structure of mevalonate 3,5-bisphosphate decarboxylase from Picrophilus torridus, a thermoacidophilic archaeon of the order Thermoplasmatales. Structural and mutational analysis demonstrated the importance of a conserved aspartate residue for enzyme activity. In addition, although crystallization was performed in the absence of substrate or ligands, residual electron density having the shape of a fatty acid was observed at a position overlapping the ATP-binding site of the homologous enzyme, diphosphomevalonate decarboxylase. This finding is in agreement with the expected evolutionary route from phosphomevalonate decarboxylase (ATP-dependent) to mevalonate 3,5-bisphosphate decarboxylase (ATP-independent) through the loss of kinase activity. We found that the binding of geranylgeranyl diphosphate, an intermediate of the archeal isoprenoid biosynthesis pathway, evoked significant activation of mevalonate 3,5-bisphosphate decarboxylase, and several mutations at the putative geranylgeranyl diphosphate–binding site impaired this activation, suggesting the physiological importance of ligand binding as well as a possible novel regulatory system employed by the Thermoplasma-type mevalonate pathway.     

Membrane perturbations induced by the interactions of zinc ions with band 3 in human erythrocytes

Of group 12 metals, zinc is an essential element to maintain our life, but other metals such as cadmium and mercury are toxic in cellular activities. Interactions of these metals with biomembranes are important to understand their effects on our living cells. Here, we describe the membrane perturbations induced by these metals in human erythrocytes. Of these metals, Zn²⁺ ions only induced the erythrocyte agglutination. Histidine residues in extracellular domains of band 3 participated in Zn²⁺-induced agglutination. Interestingly, it was found that band 3-cytoskeleton interactions play an important role in Zn²⁺-induced agglutination. In contrast with Hg²⁺ and Cd²⁺ ions, Zn²⁺ ions greatly suppressed pressure-induced hemolysis by cell agglutination. Such a suppression was removed upon dissociation of agglutinated erythrocytes by washing, indicating the reversible interactions of Zn²⁺ ions with erythrocyte membranes. Excimer fluorescence of pyrene indicated that spectrin is denatured by a pressure of 200 MPa irrespective of hemolysis suppression. Taken together, these results suggest that the agglutination of erythrocytes due to the interactions of Zn²⁺ ions with band 3 is stable under pressure, but spectrin, cytoskeletal protein, is denatured by pressure