Identification of trehalose dimycolate (cord factor) in Mycobacterium leprae

AbstractGlycolipids of Mycobacterium leprae obtained from armadillo tissue nodules infected with the bacteria were analyzed. Mass spectrometric analysis of the glycolipids indicated the presence of trehalose 6,6′-dimycolate (TDM) together with trehalose 6-monomycolate (TMM) and phenolic glycolipid-I (PGL-I). The analysis showed that M. leprae-derived TDM and TMM possessed both α- and keto-mycolates centering at C78 in the former and at C81 or 83 in the latter subclasses, respectively. For the first time, MALDI-TOF mass analyses showed the presence of TDM in M. leprae

Involvement of a Binuclear Species with the Re−C(O)O−Re Moiety in CO_2 Reduction Catalyzed by Tricarbonyl Rhenium(I) Complexes with Diimine Ligands: Strikingly Slow Formation of the Re−Re and Re−C(O)O−Re Species from Re(dmb)(CO)_3S (dmb = 4,4‘-Dimethyl-2,2‘-bipyridine, S = Solvent)

Excited-state properties of fac-[Re(dmb)(CO)_3(CH_3CN)]PF_6, [Re(dmb)(CO)_3]_2 (where dmb = 4,4‘-dimethyl-2,2‘-bipyridine), and other tricarbonyl rhenium(I) complexes were investigated by transient FTIR and UV−vis spectroscopy in CH_3CN or THF. The one-electron reduced monomer, Re(dmb)(CO)_3S (S = CH_3CN or THF), can be prepared either by reductive quenching of the excited states of fac-[Re(dmb)(CO)_3(CH_3CN)]PF_6 or by homolysis of [Re(dmb)(CO)_3]_2. In the reduced monomer's ground state, the odd electron resides on the dmb ligand rather than on the metal center. Re(dmb)(CO)_3S dimerizes slowly in THF, k_d = 40 ± 5 M^(-1) s^(-1). This rate constant is much smaller than those of other organometallic radicals which are typically 10^9 M^(-1) s^(-1). The slower rate suggests that the equilibrium between the ligand-centered and metal-centered radicals is very unfavorable (K ≈ 10^(-4)). The reaction of Re(dmb)(CO)_3S with CO_2 is slow and competes with the dimerization. Photolysis of [Re(dmb)(CO)_3]_2 in the presence of CO_2 produces CO with a 25−50% yield based on [Re]. A CO_2 bridged dimer, (CO)_3(dmb)Re−CO(O)−Re(dmb)(CO)_3 is identified as an intermediate. Both [Re(dmb)(CO)_3]_2(OCO_2) and Re(dmb)(CO)_3(OC(O)OH) are detected as oxidation products; however, the previously reported formato-rhenium species is not detected

Cryo-electron microscopic structure of the nucleoprotein-RNA complex of the European filovirus, Lloviu virus

ヨーロッパに分布するエボラウイルス近縁ウイルスの増殖機構を解明 --広範囲の抗フィロウイルス療法の開発に期待--. 京都大学プレスリリース. 2023-04-10.Lloviu virus (LLOV) is a novel filovirus detected in Schreiber’s bats in Europe. The isolation of the infectious LLOV from bats has raised public health concerns. However, the virological and molecular characteristics of LLOV remain largely unknown. The nucleoprotein (NP) of LLOV encapsidates the viral genomic RNA to form a helical NP-RNA complex, which acts as a scaffold for nucleocapsid formation and de novo viral RNA synthesis. In this study, using single-particle cryo-electron microscopy, we determined two structures of the LLOV NP-RNA helical complex, comprising a full-length and a C-terminally truncated NP. The two helical structures were identical, demonstrating that the N-terminal region determines the helical arrangement of the NP. The LLOV NP-RNA protomers displayed a structure similar to that in the Ebola and Marburg virus, but the spatial arrangements in the helix differed. Structure-based mutational analysis identified amino acids involved in the helical assembly and viral RNA synthesis. These structures advance our understanding of the filovirus nucleocapsid formation, and provide a structural basis for the development of anti-filoviral therapeutics

Diagnosing nocturnal frontal lobe epilepsy: A case study of two children

AbstractWe describe two children of nocturnal frontal lobe epilepsy (NFLE) diagnosed using carefully observed nocturnal sleep EEGs and detailed patient histories.Case #1, a 14-year-old boy, showed repeated generalized tonic convulsions and frequent eyes opening seizures during sleep. Conventional EEGs – done with the patient awake or in sleep stage I – showed no abnormalities, while a nocturnal sleep EEG – done during in sleep stage II – revealed the repeated, sharp wave bursts predominantly in the right frontal lobe characteristic of NFLE. During these wave bursts, we noticed the boy's eyes opening, although his parents had not been aware this NFLE symptom.Case #2, a 12-year-old boy, showed one daytime generalized convulsion. He had also been suffering from repeated paroxysmal episodes similar to parasomnia – waking up, sitting, walking, screaming, and speaking – which always followed the same patterns lasting several minutes. During the nocturnal sleep EEG, episodes occurred twice, showing abnormal epileptic discharges predominantly in the frontal lobe. His parents did not mention the episodes to us until questioned, as they had recognized them as parasomnia. The previous conventional EEG showed abnormal slow waves in the frontal lobe, which led us to suspect frontal lobe epilepsy and to take a detailed patient history.The frequency and stereotypy of their symptoms during sleep caused us to perform nocturnal sleep EEGs and led us NFLE diagnosis. Detailed patient histories including sleep habits and carefully observed nocturnal sleep EEGs enabled us to recognize these NFLE clinical features

北海道石狩川河口のハンノキ林床のミズバショウ (Lysichiton camtschatcense (L.) Schott)個体群における展葉フェノロジーと光環境の関係

[論文

Serologic Markers in Relation to Parasite Exposure History Help to Estimate Transmission Dynamics of Plasmodium vivax

Plasmodium vivax infection has been gaining attention because of its re-emergence in several parts of the world. Southeastern Turkey is one of the places in which persistent focal malaria caused exclusively by P. vivax parasites occurs. Although control and elimination studies have been underway for many years, no detailed study has been conducted to understand the mechanisms underlying the ineffective control of malaria in this region. Here, for the first time, using serologic markers we try to extract as much information as possible in this region to get a glimpse of P. vivax transmission. We conducted a sero-immunological study, evaluating antibody responses of individuals living in Sanliurfa to four different P. vivax antigens; three blood-stage antigens (PvMSP119, PvAMA1-ecto, and PvSERA4) and one pre-erythrocytic stage antigen (PvCSP). The results suggest that a prior history of malaria infection and age can be determining factors for the levels and sustainability of naturally acquired antibodies. Significantly higher antibody responses to all the studied antigens were observed in blood smear-negative individuals with a prior history of malaria infection. Moreover, these individuals were significantly older than blood smear-negative individuals with no prior history of infection. These data from an area of sole P. vivax-endemic region may have important implications for the global malaria control/elimination programs and vaccine design

Regulation of Recombination between gtfB/gtfC

Streptococcus mutans produces 3 types of glucosyltransferases (GTFs), whose cooperative action is essential for cellular adhesion. The recombinase A (RecA) protein is required for homologous recombination. In our previous study, we isolated several strains with a smooth colony morphology and low GTF activity, characteristics speculated to be derived from the GTF fusions. The purpose of the present study was to investigate the mechanism of those fusions. S. mutans strain MT8148 was grown in the presence of recombinant RecA (rRecA) protein, after which smooth colonies were isolated. The biological functions and sequences of the gtfB and gtfC genes of this as well as other clinical strains were determined. The sucrose-dependent adherence rates of those strains were reduced as compared to that of MT8148. Determination of the sequences of the gtfB and gtfC genes showed that an approximately 3500 bp region was deleted from the area between them. Furthermore, expression of the recA gene was elevated in those strains as compared to MT8148. These results suggest that RecA has an important role in fusions of gtfB and gtfC genes, leading to alteration of colony morphology and reduction in sucrose-dependent adhesion