Engineering DNA nanoparticles as immunomodulatory reagents that activate regulatory T cells

Nanoparticles containing DNA complexed with the cationic polymer polyethylenimine are efficient vehicles to transduce DNA into cells and organisms. DNA/polyethylenimine nanoparticles (DNPs) also elicit rapid and systemic release of proinflammatory cytokines that promote antitumor immunity. In this study, we report that DNPs possess previously unrecognized immunomodulatory attributes due to rapid upregulation of IDO enzyme activity in lymphoid tissues of mice. IDO induction in response to DNP treatment caused dendritic cells and regulatory T cells (Tregs) to acquire potent regulatory phenotypes. As expected, DNP treatment stimulated rapid increase in serum levels of IFN type I (IFN-αβ) and II (IFN-γ), which are both potent IDO inducers. IDO-mediated Treg activation was dependent on IFN type I receptor signaling, whereas IFN-γ receptor signaling was not essential for this response. Moreover, systemic IFN-γ release was caused by TLR9-dependent activation of NK cells, whereas TLR9 signaling was not required for IFN-αβ release. Accordingly, DNPs lacking immunostimulatory TLR9 ligands in DNA stimulated IFN-αβ production, induced IDO, and promoted regulatory outcomes, but did not stimulate potentially toxic, systemic release of IFN-γ. DNP treatment to induce IDO and activate Tregs blocked Ag-specific T cell responses elicited in vivo following immunization and suppressed joint pathology in a model of immune-mediated arthritis. Thus, DNPs lacking TLR9 ligands may be safe and effective reagents to protect healthy tissues from immune-mediated destruction in clinical hyperimmune syndromes.     

Evaluation of the bioremoval of Cr(VI) and TOC in biofilters under continuous operation using response surface methodology

In the present study, the bioremoval of Cr(VI) and the removal of total organic carbon (TOC) were achieved with a system composed by an anaerobic filter and a submerged biofilter with intermittent aeration using a mixed culture of microorganisms originating from contaminated sludge. In the aforementioned biofilters, the concentrations of chromium, carbon, and nitrogen were optimized according to response surface methodology. The initial concentration of Cr(VI) was 137.35 mg l⁻¹, and a bioremoval of 85.23% was attained. The optimal conditions for the removal of TOC were 4 to 8 g l⁻¹ of sodium acetate, >0.8 g l⁻¹ of ammonium chloride and 60 to 100 mg l⁻¹ of Cr(VI). The results revealed that ammonium chloride had the strongest effect on the TOC removal, and 120 mg l⁻¹ of Cr(VI) could be removed after 156 h of operation. Moreover, 100% of the Cr(VI) and the total chromium content of the aerobic reactor output were removed, and TOC removals of 80 and 87% were attained after operating the anaerobic and aerobic reactors for 130 and 142 h, respectively. The concentrations of cells in both reactors remained nearly constant over time. The residence time distribution was obtained to evaluate the flow through the bioreactors.     

Age-dependent fecundity and fertility life tables of the predator Brontocoris tabidus (Heteroptera: Pentatomidae) under field conditions

Reproductive potential, longevity, life expectancy, and fertility life tables of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae), a predator of lepidopteran defoliators in eucalyptus (Eucalyptus spp.) plantations, were studied in the field. After a 50-d preoviposition period (emergence of adults to the deposition of the first egg mass), ovipositional activity of B. tabidus continued until females died at 160 d. Females laid an average of 4.2 eggs per day and 601.1 eggs in a lifetime. Gross and net reproductive rates were 216.7 and 75.8 females, respectively. Generation time was 146.1 d, the period for doubling the population was 23.4 d, intrinsic rate was 0.03, and finite population increase was 1.03. Number of females per generation increased at 33.4 times. Results from our field studies indicate that B. tabidus has greater potential reproduction, oviposition period, and longevity than was expected from previous laboratory experiments. This suggests that B. tabidus has potential as a biological control agent to limit economically damaging pests in eucalyptus plantations.     

Enhancing the thermal stability of lipases through mutagenesis and immobilization on zeolites

The hydrolysis reaction of p-nitrophenyl butyrate catalyzed by lipases was followed with in situ UV/vis diode array spectrophotometry. Five enzymes - Candida antarctica lipase B and Fusarium solani pisi cutinase wild-type and three single-mutation variants - were tested as catalysts in homogeneous conditions and immobilized on zeolite NaY, on a polyacrylate support and as cross-linked aggregates. Using deconvolution techniques and kinetic modeling, the thermal stability of the different biocatalysts was compared in operational conditions and the results were supported by steady-state enzyme fluorescence measurements. We concluded that both the mutagenesis and the immobilization on zeolite NaY had a positive effect on the thermal stability of F. solani pisi cutinase.     

Distinctively variable sequence-based nuclear DNA markers for multilocus phylogeography of the soybean- and rice-infecting fungal pathogen Rhizoctonia solani AG-1 IA

A series of multilocus sequence-based nuclear DNA markers was developed to infer the phylogeographical history of the Basidiomycetous fungal pathogen Rhizoctonia solani AG-1 IA infecting rice and soybean worldwide. The strategy was based on sequencing of cloned genomic DNA fragments (previously used as RFLP probes) and subsequent screening of fungal isolates to detect single nucleotide polymorphisms (SNPs). Ten primer pairs were designed based on these sequences, which resulted in PCR amplification of 200-320 bp size products and polymorphic sequences in all markers analyzed. By direct sequencing we identified both homokaryon and heterokaryon (i.e. dikaryon) isolates at each marker. Cloning the PCR products effectively estimated the allelic phase from heterokaryotic isolates. Information content varied among markers from 0.5 to 5.9 mutations per 100 bp. Thus, the former RFLP codominant probes were successfully converted into six distinctively variable sequence-based nuclear DNA markers. Rather than discarding low polymorphism loci, the combination of these distinctively variable anonymous nuclear markers would constitute an asset for the unbiased estimate of the phylogeographical parameters such as population sizes and divergent times, providing a more reliable species history that shaped the current population structure of R. solani AG-1 IA.     

Germ band retraction as a landmark in glucose metabolism during <Emphasis Type="Italic">Aedes aegypti</Emphasis> embryogenesis

Background  

The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown.