CABI Abstracts Databases

Nisin is a known bacteriocin, which exhibits a wide spectrum of antimicrobial activity, while commonly being inefficient against Gram-negative bacteria. In this work, we present a proof of concept of novel antimicrobial methodology using targeted magnetic nisin-loaded nano-carriers [iron oxide nanoparticles (NPs) (11–13 nm) capped with citric, ascorbic, and gallic acids], which are activated by high pulsed electric and electromagnetic fields allowing to overcome the nisin-resistance of bacteria. As a cell model the Gram-positive bacteria Bacillus subtilis and Gram-negative Escherichia coli were used. We have applied 10 and 30 kV cm-1 electric field pulses (100 μs × 8) separately and in combination with two pulsed magnetic field protocols: (1) high dB/dt 3.3 T × 50 and (2) 10 mT, 100 kHz, 2 min protocol to induce additional permeabilization and local magnetic hyperthermia. We have shown that the high dB/dt pulsed magnetic fields increase the antimicrobial efficiency of nisin NPs similar to electroporation or magnetic hyperthermia methods and a synergistic treatment is also possible. The results of our work are promising for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections.

Strongly consistent and asymptotically normal estimators of the Hurst index and volatility parameters of solutions of stochastic differential equations with polynomial drift are proposed. The estimators are based on discrete observations of the underlying processes.

Tricyclic wyosine derivatives are found at position 37 of eukaryotic and archaeal tRNAPhe. In Archaea, the intermediate imG-14 is targeted by three different enzymes that catalyze the formation of yW-86, imG, and imG2. We have suggested previously that a peculiar methyltransferase (aTrm5a/Taw22) likely catalyzes two distinct reactions: N1-methylation of guanosine to yield m1G; and C7-methylation of imG-14 to yield imG2. Here we show that the recombinant aTrm5a/Taw22-like enzymes from both Pyrococcus abyssi and Nanoarchaeum equitans indeed possess such dual specificity. We also show that substitutions of individual conservative amino acids of P. abyssi Taw22 (P260N, E173A, and R174A) have a differential effect on the formation of m1G/imG2, while replacement of R134, F165, E213, and P262 with alanine abolishes the formation of both derivatives of G37. We further demonstrate that aTrm5a-type enzyme SSO2439 from Sulfolobus solfataricus, which has no N1-methyltransferase activity, exhibits C7 -methyltransferase activity, thereby producing imG2 from imG-14. We thus suggest renaming such aTrm5a methyltransferases as Taw21 to distinguish between monofunctional and bifunctional aTrm5a enzymes.

Our aim is to evaluate the complement component C4 (C4) and its fragment C4d (C4d) levels, focusing on their associations with other markers of B cells’ activity in patients with primary Sjögren’s syndrome (pSS). Humoral factors C4, C4d, B cell-activating factor (BAFF), κ and λ free light chains (FLCs) and IgG (by immunoassay) were investigated in 58 patients with pSS and in 28 healthy controls. We observed significantly higher levels of BAFF, κ and λ FLC and IgG, and significantly lower level of C4 in pSS patients, while the level of C4d was similar in the both groups. Significantly higher levels of BAFF, κ and λ FLCs, IgG, and significantly lower C4 level were found in anti-SSA/SSB antibodies (Abs) seropositive pSS patients’ group comparing with healthy controls. Level of C4d was significantly lower in anti-SSA/SSB Abs seropositive pSS patients comparing with seronegative pSS patients and healthy controls. C4d correlated with C4, anti-SSB Abs level and κ/λ ratio. Significantly higher κ FLC and IgG levels were found in anti-SSA/SSB Abs seronegative pSS patients comparing with healthy controls. Anti-SSA/SSB seropositivity in pSS patients is associated with the decreased level of C4d. These results show that C4d can be an appropriate marker of antibody response and complement activation in pSS patients with Abs, and possibly may show the more severe condition—exhaustion of C4. Further studies are required to determine whether C4d assessment could be a relevant biomarker for the more severe condition and the worse prognosis of pSS.

Saccharomyces cerevisiae K2 toxin is a highly active extracellular protein, important as a biocontrol agent for biotechnological applications in the wine industry. This protein is produced at negligible levels in yeast, making difficult to isolate it in amounts sufficient for investigation and generation of analysis tools. In this work, we demonstrate the use of a bacterial system for expression of the recombinant K2 protein, suitable for generation of antibodies specific for toxin of the yeast origin. Synthesis of the full-length S. cerevisiae K2 preprotoxin in Escherichia coli was found to be toxic to the host cell, resulting in diminished growth. Such effect was abolished by the introduction of the C-terminal truncation into K2 protein, directing it into non-toxic inclusion body fraction. The obtained protein is of limited solubility thus, facilitating the purification by simple and efficient chromatography-free procedure. The protein aggregates were successfully refolded into a soluble form yielding sufficient amounts of a tag-less truncated K2 protein suitable for polyclonal antibody production. Antibodies were raised in rabbit and found to be specific for detection of both antigen and native S. cerevisiae K2 toxin.

Background: Epigenetic regulation is known to affect gene expression, and recent research shows that aberrant DNA methylation patterning and histone modifications may play a role in leukemogenesis. In order to highlight the co-operation of epigenetic mechanisms acting during the latter process it is important to clarify their potential as biomarkers of granulocytic differentiation. Results: In this study we investigated epigenetic alterations in human hematopoietic cells at a distinct differentiation stages: primary hematopoietic CD34+ cells, KG1 myeloid leukemic cells, whose development is stopped at early stage of differentiation, and mature neutrophils. We focused on the epigenetic status of cell cycle regulating (p15, p16) and differentiation related (E-cadherin and RARβ) genes. We found that the methylation level in promoter regions of some of these genes was considerably higher in KG1 cells and lower in CD34+ cells and human neutrophils. As examined and evaluated by computer-assisted methods, histone H3 and H4 modifications, i.e. H3K4Me3, H3K9Ac, H3K9Ac/S10Ph and H4 hyperAc, were similar in CD34+ cells and human mature neutrophils. By contrast, in the KG1 cells, histone H3 and H4 modifications were quite high and increased after induction of granulocytic differentiation with the HDAC inhibitor phenyl butyrate. Conclusions: We found the methylation status of the examined gene promoters and histone modifications to be characteristically associated with the hematopoietic cell progenitor state, induced to differentiate myeloid KG1 cells and normal blood neutrophils. This could be achieved through epigenetic regulation of E-cadherin, p15, p16 and RARβ genes expression caused by DNA methylation/demethylation, core and linker histones distribution in stem hematopoietic cells, induced to differentiation KG1 cells and mature human neutrophils, as well as the histone modifications H3K4Me3, H3K9Ac, H3K9Ac/S10Ph and H4 hyperAc in relation to hematopoietic cell differentiation to granulocyte. These findings also suggest them as potentially important biomarkers of hematopoietic cell granulocytic differentiation and could be valuable for leukemia induced differentiation therapy.

The peculiar methyltransferase aTrm5a catalyzes two distinct reactions: N1-methylation of guanosine and C7-methylation of 4-demethylwyosine (imG-14) that allows the production of isowyosine (imG2), an intermediate in the 7-methylwyosine (mimG) biosynthetic pathway. This bifunctional tRNA methyltransferase that acts on two chemically distinct guanosine derivatives located at the same position of tRNAPhe is unique to certain archaea and has no homologs in eukaryotes.