Heterogeneity in the Response of Different Subtypes of Drosophila melanogaster Midgut Cells to Viral Infections.

Single-cell RNA sequencing (scRNA-seq) offers the possibility to monitor both host and pathogens transcriptomes at the cellular level. Here, public scRNA-seq datasets from Drosophila melanogaster midgut cells were used to compare the differences in replication strategy and cellular responses between two fly picorna-like viruses, Thika virus (TV) and D. melanogaster Nora virus (DMelNV). TV exhibited lower levels of viral RNA accumulation but infected a higher number of cells compared to DMelNV. In both cases, viral RNA accumulation varied according to cell subtype. The cellular heat shock response to TV and DMelNV infection was cell-subtype- and virus-specific. Disruption of bottleneck genes at later stages of infection in the systemic response, as well as of translation-related genes in the cellular response to DMelNV in two cell subtypes, may affect the virus replication.

siRNA biogenesis and advances in topically applied dsRNA for controlling virus infections in tomato plants.

A non-transgenic approach based on RNA interference was employed to induce protection against tomato mosaic virus (ToMV) infection in tomato plants. dsRNA molecules targeting the cp gene of ToMV were topically applied on plants prior to virus inoculation. Protection was dose-dependent and sequence-specific. While no protection was achieved when 0-16 µg dsRNA were used, maximum rates of resistance (60 and 63%) were observed in doses of 200 and 400 µg/plant, respectively. Similar rates were also obtained against potato virus Y when targeting its cp gene. The protection was quickly activated upon dsRNA application and lasted for up to 4 days. In contrast, no detectable antiviral response was triggered by the dsRNA from a begomovirus genome, suggesting the method is not effective against phloem-limited DNA viruses. Deep sequencing was performed to analyze the biogenesis of siRNA populations. Although long-dsRNA remained in the treated leaves for at least 10 days, its systemic movement was not observed. Conversely, dsRNA-derived siRNA populations (mainly 21- and 22-nt) were detected in non-treated leaves, which indicates endogenous processing and transport through the plant. Altogether, this study provides critical information for the development of novel tools against plant viruses; strengths and limitations inherent to the systems are discussed.

Antioxidative effect and phytochemical profile of natural products from the fruits of "babaçu" (Orbignia speciose) and "buriti" (Mauritia flexuosa).

Orbignya speciosa and Mauritia flexuosa are two native palm tree species found in Brazil. Their fruits are rich in edible fixed oils, which are used for many purposes in industry, such as in the manufacture of soaps, surfactants and margarines. The aim of this work was to characterize the chemical profiles and antioxidant properties of the methanol extracts obtained from the fruits of O. speciosa and M. flexuosa. The chemical prospection was carried out using specific qualitative tests to evaluate the presence of phenolic compounds (tannins and flavonoids) in the extracts of both species. The antioxidant properties of the extracts were analyzed by the following methods: production of thiobarbituric acid reactive substances (TBARS) from phospholipids, deoxyribose degradation, radical-scavenging activity-DPPH, iron chelation assay and ferric-reducing antioxidant power (FRAP). The methanolic extracts obtained from M. flexuosa and O. speciosa presented significant antioxidant activities, although M. flexuosa presented higher antioxidant activity than O. speciosa. In conclusion, M. flexuosa and O. speciosa are important sources of antioxidant substances that may be useful in the development of new products to prevent diseases associated with oxidative stress.

Effectiveness and biological compatibility of different generations of dentin adhesives.

OBJECTIVES: Besides possessing good mechanical properties, dental materials should present a good biological behavior and should not injure the involved tissues. Bond strength and biocompatibility are both highly significant properties of dentin adhesives. For that matter, these properties of four generations of adhesive systems (Multi-Purpose/Single Bond/SE Plus/Easy Bond) were evaluated. MATERIALS AND METHODS: Eighty bovine teeth had their dentin exposed (500- and 200-µm thickness). Adhesive was applied on the dentin layer of each specimen. Following that, the microshearing test was performed for all samples. A dentin barrier test was used for the cytotoxicity evaluation. Cell cultures (SV3NeoB) were collected from testing materials by means of 200- or 500-µm-thick dentin slices and placed in a cell culture perfusion chamber. Cell viability was measured 24 h post-exposition by means of a photometrical test (MTT test). RESULTS: The best bonding performance was shown by the single-step adhesive Easy Bond (21 MPa, 200 µm; 27 MPa, 500 µm) followed by Single Bond (15.6 MPa, 200 µm; 23.4 MPa, 500 µm), SE Plus (18.2 MPa, 200 µm; 20 MPa, 500 µm), and Multi-Purpose (15.2 MPa, 200 µm; 17.9 MPa, 500 µm). Regarding the cytotoxicity, Multi-Purpose slightly reduced the cell viability to 92% (200 µm)/93% (500 µm). Single Bond was reasonably cytotoxic, reducing cell viability to 71% (200 µm)/64% (500 µm). The self-etching adhesive Scotchbond SE decreased cell viability to 85% (200 µm)/71% (500 µm). Conversely, Easy Bond did not reduce cell viability in this test, regardless of the dentin thickness. CONCLUSIONS: Results showed that the one-step system had the best bond strength performance and was the least toxic to pulp cells. In multiple-step systems, a correct bonding technique must be done, and a pulp capping strategy is necessary for achieving good performance in both properties. CLINICAL RELEVANCE: The study showed a promising system (one-step self-etching), referring to it as a good alternative for specific cases, mainly due to its technical simplicity and good biological responses.