Characterization of phenylpropanoid pathway genes within European maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) inbreds

Background  

Forage quality of maize is influenced by both the content and structure of lignins in the cell wall. Biosynthesis of monolignols, constituting the complex structure of lignins, is catalyzed by enzymes in the phenylpropanoid pathway.     

Genetic polymorphisms of Fas (CD95) and Fas ligand (CD178) influence the rise in CD4+ T cell count after antiretroviral therapy in drug-naïve HIV-positive patients

Fas and Fas ligand (FasL) are the main genes that control cell death in the immune system. Indeed, they are crucial for the regulation of T lymphocyte homeostasis because they can influence cell proliferation. A strong debate exists on the importance of Fas/FasL system during HIV infection, which is characterized by the loss of CD4+ T cells directly, or indirectly, caused by the virus. To investigate whether the genetic background of the host plays a role in the immunoreconstitution, we studied the influence of different Fas and FasL polymorphisms on CD4+ T lymphocyte count and plasma viral load following initiation of highly active antiretroviral therapy (HAART) in drug-naïve HIV+ patients. We studied 131 individuals, who were compared to 136 healthy donors. Statistical analysis was performed by using X ² test, Fischer's Exact Test, and analysis for repeated measurements. The group of HIV+ patients had an unexpected lower frequency of FasLnt169 polymorphism (delT allele) than healthy controls (p=0.039). We then observed no significant differences in the immune reconstitution, in terms of CD4+ T cell increase, when the influence of single alleles of the gene Fas or FasL was considered. However, the combination of some polymorphisms of Fas or FasL significantly influenced CD4+ T cell production and viral load decrease, showing that these genes can play a role in the immunoreconstitution triggered by antiretroviral therapy.     

Site-specific mutagenesis of the histidine precursor of diphthamide in the human elongation factor-2 gene confers resistance to diphtheria toxin

Protein synthesis elongation factor 2 (EF-2) from eukaryotes contains a conserved post-translationally modified histidine residue known as diphthamide. Diphthamide is a unique site of ADP-ribosylation by diphtheria toxin (DT), which is responsible for cell killing. In this report, we describe the construction of DT-resistant HeLa cell lines by engineering the toxin-resistant form of its specific substrate, protein elongation factor-2. Using site-specific mutagenesis of the histidine precursor of diphthamide, the histidine residue of codon 715 in human EF-2 cDNA was substituted with one of four amino acid residue codons: leucine, methionine, asparagine or glutamine. Mutant EF-2s were subcloned into a pCMVexSVneo expression vector, transfected into HeLa cells, and DT-resistant cell clones were isolated. The protective effect of mutant EF-2s against cell killing by DT, after exposing all four mutant strains derived from HeLa cells to different concentrations of the toxin (5-20 ng/mL) was demonstrated by: (1) the normal morphological appearance of the cells; (2) their unaffected or slightly slower growth rates; (3) their undisturbed electrophoretic DNA profiles whose integrity was virtually preserved. Mutant cell strains showed also considerable levels of resistance to very high concentrations of DT, in that they maintained slower but consistent rates of cell growth. It was hence concluded that despite its strict conservation and unique modification, the diphthamide histidine appears not to be essential to the function of human EF-2 in protein synthesis. In addition, DT-resistant HeLa cell clones should prove valuable hosts for various DT gene-containing vectors that express the toxin intracellularly.     

Coexistence of antibodies to tick-borne agents of babesiosis and Lyme borreliosis in patients from Cotia county,State of São Paulo,Brazil

This paper reports a case of coinfection caused by pathogens of Lyme disease and babesiosis in brothers. This was the first case of borreliosis in Brazil, acquired in Cotia County, State of S o Paulo, Brazil. Both children had tick bite history, presented erythema migrans, fever, arthralgia, mialgia, and developed positive serology (ELISA and Western-blotting) directed to Borrelia burgdorferi G 39/40 and Babesia bovis antigens, mainly of IgM class antibodies, suggestive of acute disease. Also, high frequencies of antibodies to B. bovis was observed in a group of 59 Brazilian patients with Lyme borreliosis (25.4%), when compared with that obtained in a normal control group (10.2%) (chi-square = 5.6; p < 0.05). Interestingly, both children presented the highest titers for IgM antibodies directed to both infective diseases, among all patients with Lyme borreliosis.     

Consequences of relative cellular positioning on quorum sensing and bacterial cell-to-cell communication

Cell-to-cell bacterial communication via diffusible signals is addressed and the conceptual framework in which quorum sensing is usually described is evaluated. By applying equations ruling the physical diffusion of the autoinducer molecules, one can calculate the gradient profiles that would occur either around a single cell or at the center of volumes of increasing size and increasing cell densities. Water-based matrices at 25 °C and viscous biofilms at colder temperatures are compared. Some basic consequences relevant for the field of microbial signalling arise. As regards induction, gradient-mixing dynamics between as little as two cells lying at a short distance appears to be sufficient for the buildup of a concentration reaching the known thresholds for quorum sensing. A straight line in which the highest concentrations occur is also created as a consequence of the gradient overlap geometry, providing an additional signal information potentially useful for chemotactic responses. In terms of whole population signalling, it is shown how the concentration perceived by a cell in the center is critically dependent not only on the cell density but also on the size of the biofilm itself. Tables and formulas for the practical prediction of N -acyl homoserine lactones concentrations at desired distances in different cell density biofilms are provided.     

A hidden deadly venomous insect: First eco-epidemiological assessment and risk mapping of lonomism in Argentina

BackgroundEnvenomation by the South American Lonomia saturniid caterpillars, named lonomism, constitutes an emerging and somewhat neglected public health issue in Argentina and neighboring countries. Considering that there is an intricate relationship between environment and human health in such cases, this study aimed to analyze the eco-epidemiological profile of 40 accidents and 33 occurrences of Lonomia spp. in Misiones (Argentina) between January 2014 and May 2020.Methodology/Principal findingsWe described the eco-epidemiological variables and characterized the abiotic scenario of such cases. Additionally, we obtained a density map that shows the punctual intensity of Lonomia records throughout Misiones. Most of the accidents occurred in the Department of Guaraní and involved male victims younger than 20 years old. The accidental/occasional occurrence of Lonomia spp. (considering both adult and caterpillar stages together) was significantly higher in the rural area, whereas only adult specimens were found in urban areas. We determined that the presence of this insect in Misiones is positively related to higher temperatures and solar radiation, and larger precipitation and evapotranspiration throughout the year.Conclusion/SignificanceThis study represents an initial step towards the global understanding of lonomism as a public health problem in Argentina. It provides a map of the risk level for this envenomation in Misiones, which could help authorities address public health policy efforts to implement sustainable strategies for prevention and response to this threat in Northeastern Argentina and neighboring regions.     

Yeasts isolated from olive mill wastewaters from southern Italy: technological characterization and potential use for phenol removal

Olive mill wastewater (OMW) samples from two traditional varieties (Peranzana and Ogliarola Garganica) of Apulian region (southern Italy) and produced through continuous and traditional methods were microbiologically and chemically examined; thus, 104 yeasts were isolated and selected for further analyses. The strains were identified as Candida boidinii, Pichia holstii, Pichia membranifaciens, and Saccharomyces cerevisiae and analyzed to assess their suitability to metabolize phenols. Based on phenol metabolism, 27 strains were selected and inoculated into OMW aliquots to determine their ability to reduce phenols in vivo; then, five strains (identified with the codes 682—C. boidinii and 625, 642, 647, and 941—P. holstii) were used as a cocktail in wastewaters for a final validation step. In this last experiment, the effects of the temperature (10–30°C) and (NH₄)₂SO₄ (0.0–6.0 g l⁻¹) were studied through a central composite design approach, and the results highlighted that the cocktail was able to reduce phenols by 40% at 10°C with 6.0 g l⁻¹ of (NH₄)₂SO₄ added.