Structure and electronic properties of azadirachtin

We performed a combined DFT and Monte Carlo ¹³C NMR chemical-shift study of azadirachtin A, a triterpenoid that acts as a natural insect antifeedant. A conformational search using a Monte Carlo technique based on the RM1 semiempirical method was carried out in order to establish its preferred structure. The B3LYP/6-311++G(d,p), wB97XD/6-311++G(d,p), M06/6-311++G(d,p), M06-2X/6-311++G(d,p), and CAM-B3LYP/6-311++G(d,p) levels of theory were used to predict NMR chemical shifts. A Monte Carlo population-weighted average spectrum was produced based on the predicted Boltzmann contributions. In general, good agreement between experimental and theoretical data was obtained using both methods, and the ¹³C NMR chemical shifts were predicted highly accurately. The geometry was optimized at the semiempirical level and used to calculate the NMR chemical shifts at the DFT level, and these shifts showed only minor deviations from those obtained following structural optimization at the DFT level, and incurred a much lower computational cost. The theoretical ultraviolet spectrum showed a maximum absorption peak that was mainly contributed by the tiglate group.     

Irradiance-driven 20-hydroxyecdysone production and morphophysiological changes in Pfaffia glomerata plants grown in vitro

Pfaffia glomerata possesses potential pharmacological and medicinal properties, mainly owing to the secondary metabolite 20-hydroxyecdysone (20E). Increasing production of biomass and 20E is important for industrial purposes. This study aimed to evaluate the influence of irradiance on plant morphology and production of 20E in P. glomerata grown in vitro. Nodal segments of accessions 22 and 43 (Ac22 and Ac43) were inoculated in culture medium containing MS salts and vitamins. Cultures were maintained at 25 ± 2 °C under a 16-h photoperiod and subjected to irradiance treatments of 65, 130, and 200 μmol m⁻² s⁻¹ by fluorescent lamps. After 30 days, growth parameters, pigment content, stomatal density, in vitro photosynthesis, metabolites content, and morphoanatomy were assessed. Notably, Ac22 plants exhibited 10-fold higher 20E production when cultivated at 200 μmol m⁻² s⁻¹ than at 65 μmol m⁻² s⁻¹, evidencing the importance of light quantity for the accumulation of this metabolite. 20E production was twice as high in Ac22 as in Ac43 plants although both accessions responded positively to higher irradiance. Growth under 200 μmol m⁻² s⁻¹ stimulated photosynthesis and consequent biomass accumulation, but lowered carotenoids and anthocyanins. Furthermore, increasing irradiance enhanced the number of palisade and spongy parenchyma cells, enhancing the overall growth of P. glomerata.

Graphical abstract

     

Latitude and Social Habits as Determinants of the Distribution of Morning and Evening Types in Brazil

Previous application of a Portuguese version of the Horne and Östberg (H&O) questionnaires in Brazil showed a displacement of the distribution of Morningness/Eveningness (M/E) types towards morningness, demanding a reclassification of the score's limits for each of the 5 possible M/E types. Among city, age and sex, city was the only factor determining significant group differences. In the present paper, the same version of the H&O's questionnaire was applied to a distinct population of 260 adults, balanced according to age, sex and city. Data were collected from October to December, to control the effect of the photoperiod. City remains the only factor determining significant group differences (p <0.001). Moreover, there does not appear a coherent latitude trend that could explain differences among cities as a function of photoperiod. Local social habits could probably explain our results, suggesting further investigations of peculiar temporal patterns.     

Genomic sequencing of different sequevars of Ralstonia solanacearum belonging to the Moko ecotype

Banana vascular wilt or Moko is a disease caused by Ralstonia solanacearum. This study aimed to sequence, assemble, annotate, and compare the genomes of R. solanacearum Moko ecotypes of different sequevar strains from Brazil. Average nucleotide identity analyses demonstrated a high correlation (> 96%) between the genome sequences of strains CCRMRs277 (sequevar IIA-24), CCRMRs287 (IIB-4), CCRMRs304 (IIA-24), and CCRMRsB7 (IIB-25), which were grouped into phylotypes IIA and IIB. The number of coding sequences present in chromosomes and megaplasmids varied from 3,070 to 3,521 and 1,669 to 1,750, respectively. Pangenome analysis identified 3,378 clusters in the chromosomes, of which 2,604 were shared by all four analyzed genomes and 2,580 were single copies. In megaplasmids, 1,834 clusters were identified, of which 1,005 were shared by all four genomes and 992 were identified as single copies. Strains CCRMRsB7 and CCRMRs287 differed from the others by having unique clusters in both their chromosomes and megaplasmids, and CCRMRsB7 possessed the largest genome among all Moko ecotype strains sequenced to date. Therefore, the genomic information obtained in this study provides a theoretical basis for the identification, characterization, and phylogenetic analysis of R. solanacearum Moko ecotypes.     

Intracardiac Injection of Dental Pulp Stem Cells After Neonatal Hypoxia-Ischemia Prevents Cognitive Deficits in Rats

Neonatal hypoxia-ischemia (HI) is associated to cognitive and motor impairments and until the moment there is no proven treatment. The underlying neuroprotective mechanisms of stem cells are partially understood and include decrease in excitotoxicity, apoptosis and inflammation suppression. This study was conducted in order to test the effects of intracardiac transplantation of human dental pulp stem cells (hDPSCs) for treating HI damage. Seven-day-old Wistar rats were divided into four groups: sham-saline, sham-hDPSCs, HI-saline, and HI-hDPSCs. Motor and cognitive tasks were performed from postnatal day 30. HI-induced cognitive deficits in the novel-object recognition test and in spatial reference memory impairment which were prevented by hDPSCs. No motor impairments were observed in HI animals. Immunofluorescence analysis showed human-positive nuclei in hDPSC-treated animals closely associated with anti-GFAP staining in the lesion scar tissue, suggesting that these cells were able to migrate to the injury site and could be providing support to CNS cells. Our study evidence novel evidence that hDPSC can contribute to the recovery following hypoxia-ischemia and highlight the need of further investigation in order to better understand the exact mechanisms underlying its neuroprotective effects.     

Parasitoid associated with Liriomyza huidobrensis (Diptera: Agromyzidae) outbreaks in tomato fields in Brazil

1. The knowledge of natural factors that affect pest populations is essential in predicting the occurrence of pest outbreaks and in developing integrated pest management programmes. Natural enemies, climatic elements and host plants are among the most important factors affecting pest dynamics.
2. Tomato (Solanum lycopersicum) is the second most consumed vegetable worldwide. The pea leaf miner Liriomyza huidobrensis (Diptera: Agromyzidae) is a major pest to the tomato in Brazil.
3. This study aimed to determine the main natural factors that regulate L. huidobrensis populations in tomato fields in Brazil.
4. Liriomyza huidobrensis densities were evaluated by directly counting the number of active mines on the basal leaf of the middle section of the plant canopy, and predators and parasitoids were assessed using the leaf‐beating‐against‐a‐tray technique. Eight commercial tomato fields were assessed over two years. The phenological growth stages of the tomato plants (vegetative and reproductive) were noted during the assessments.
5. Liriomyza huidobrensis populations peaked between the middle and end of the planting season.
6. Opius sp. (Hymenoptera: Braconidae) was the main natural enemy of L. huidobrensis.
7. Our results suggest that phenological growth stage and Opius sp. are associated with population dynamics of L. huidobrensis in tomato fields.
8. Therefore, integrated pest management programmes should aim to preserve populations of the parasitoid Opius sp.

     

A decade of malaria during pregnancy in Brazil: what has been done concerning prevention and management

In Brazil, malaria remains a disease of major epidemiological importance because of the high number of cases in the Amazonian Region. Plasmodium spp infections during pregnancy are a significant public health problem with substantial risks for the pregnant woman, the foetus and the newborn child. In Brazil, the control of malaria during pregnancy is primarily achieved by prompt and effective treatment of the acute episodes. Thus, to assure rapid diagnosis and treatment for pregnant women with malaria, one of the recommended strategy for low transmission areas by World Health Organization and as part of a strategy by the Ministry of Health, the National Malaria Control Program has focused on integrative measures with woman and reproductive health. Here, we discuss the approach for the prevention and management of malaria during pregnancy in Brazil over the last 10 years (2003-2012) using morbidity data from Malaria Health Information System. Improving the efficiency and quality of healthcare and education and the consolidation of prevention programmes will be challenges in the control of malaria during pregnancy in the next decade.