SILICON APPLICATION AND MYCORRHIZA INOCULATION PROMOTED LEUCAENA LEUCOCEPHALA GROWTH IN A SOIL HIGHLY CONTAMINATED BY MANGANESE

ABSTRACT: Arbuscular mycorrhizal fungi (AMF) can increase the acquisition of silicon (Si) and, therefore, alleviate the problems caused by metallic toxicity in plants, but this effect remains poorly understood. The objective was to evaluate the influence of Si application on the growth of Leucaena leucocephala inoculated with AMF (Claroideoglomus etunicatum) in a soil contaminated by manganese (Mn). We exposed plants to increasing levels of Si (0, 100, 200 and 400 mg kg-1) in the soil for 90 days. Intermediate levels of Si and AMF inoculation significantly increased shoot and root dry mass, the number of sheets, root system length and mycorrhizal colonization. The abundance of AMF spores decreased linearly with increasing levels of Si applied to the soil, suggesting a low correlation with mycorrhizal colonization. In addition to the higher Mn contents in the shoots and, mainly, in the roots, the combined application of Si and inoculation with AMF significantly reduced foliar toxicity by more than 40%, when compared to the absence of Si and AMF inoculation. Our results demonstrated a synergistic effect of AMF and Si in improving the growth and tolerance of L. leucocephala plants in soil contaminated by Mn. Keywords: heavy metals; stress; remediation; AMF; Mn toxicity.   Aplicação de silício e inoculação de micorriza promove crescimento de Leucaena leucocephala em solo altamente contaminado por manganês   RESUMO: Os fungos micorrízicos arbusculares (FMA) podem aumentar a aquisição de silício (Si) e, portanto, amenizar os problemas causados ​​pela toxidez metálica nas plantas, mas esse efeito ainda é pouco conhecido. O objetivo foi avaliar a influência da aplicação de Si no crescimento de Leucaena leucocephala inoculada com FMA (Claroideoglomus etunicatum) em solo contaminado por manganês (Mn). Expusemos as plantas a níveis crescentes de Si (0, 100, 200 e 400 mg kg-1) no solo por 90 dias. Níveis intermediários de Si e inoculação de FMA aumentaram significativamente a massa seca da parte aérea e radicular, o número de folhas, o comprimento do sistema radicular e a colonização micorrízica. A abundância de esporos de FMA diminuiu linearmente com o aumento dos níveis de Si aplicados ao solo, sugerindo uma baixa correlação com a colonização micorrízica. Além dos maiores teores de Mn na parte aérea e, principalmente, nas raízes, a aplicação combinada de Si e inoculação com FMA reduziu significativamente a toxidez foliar em mais de 40%, quando comparada à ausência de Si e inoculação de FMA. Nossos resultados demonstraram um efeito sinérgico de FMA e Si na melhoria do crescimento e tolerância de plantas de L. leucocephala em solo contaminado por Mn. Palavras-chave: metais pesados; estresse; remediação; FMA; toxidez por Mn.ABSTRACT: Arbuscular mycorrhizal fungi (AMF) can increase the acquisition of silicon (Si) and, therefore, alleviate the problems caused by metallic toxicity in plants, but this effect remains poorly understood. The objective was to evaluate the influence of Si application on the growth of Leucaena leucocephala inoculated with AMF (Claroideoglomus etunicatum) in a soil contaminated by manganese (Mn). We exposed plants to increasing levels of Si (0, 100, 200 and 400 mg kg-1) in the soil for 90 days. Intermediate levels of Si and AMF inoculation significantly increased shoot and root dry mass, the number of sheets, root system length and mycorrhizal colonization. The abundance of AMF spores decreased linearly with increasing levels of Si applied to the soil, suggesting a low correlation with mycorrhizal colonization. In addition to the higher Mn contents in the shoots and, mainly, in the roots, the combined application of Si and inoculation with AMF significantly reduced foliar toxicity by more than 40%, when compared to the absence of Si and AMF inoculation. Our results demonstrated a synergistic effect of AMF and Si in improving the growth and tolerance of L. leucocephala plants in soil contaminated by Mn. Keywords: heavy metals; stress; remediation; AMF; Mn toxicity.   Aplicação de silício e inoculação de micorriza promove crescimento de Leucaena leucocephala em solo altamente contaminado por manganês   RESUMO: Os fungos micorrízicos arbusculares (FMA) podem aumentar a aquisição de silício (Si) e, portanto, amenizar os problemas causados ​​pela toxidez metálica nas plantas, mas esse efeito ainda é pouco conhecido. O objetivo foi avaliar a influência da aplicação de Si no crescimento de Leucaena leucocephala inoculada com FMA (Claroideoglomus etunicatum) em solo contaminado por manganês (Mn). Expusemos as plantas a níveis crescentes de Si (0, 100, 200 e 400 mg kg-1) no solo por 90 dias. Níveis intermediários de Si e inoculação de FMA aumentaram significativamente a massa seca da parte aérea e radicular, o número de folhas, o comprimento do sistema radicular e a colonização micorrízica. A abundância de esporos de FMA diminuiu linearmente com o aumento dos níveis de Si aplicados ao solo, sugerindo uma baixa correlação com a colonização micorrízica. Além dos maiores teores de Mn na parte aérea e, principalmente, nas raízes, a aplicação combinada de Si e inoculação com FMA reduziu significativamente a toxidez foliar em mais de 40%, quando comparada à ausência de Si e inoculação de FMA. Nossos resultados demonstraram um efeito sinérgico de FMA e Si na melhoria do crescimento e tolerância de plantas de L. leucocephala em solo contaminado por Mn. Palavras-chave: metais pesados; estresse; remediação; FMA; toxidez por Mn

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Toxicity of different fatty acids and methyl esters on Culex quinquefasciatus larvae

The Culex quinquefasciatus mosquito is a vector of several diseases, and its control has been performed with synthetic insecticides, which may have human and environmental side effects. Thus, the use of new and safe molecules are important, and this study evaluated the toxicity of active substances against this mosquito. The oleic, linoleic, linolenic, palmitic and stearic acids and their respective methyl esters were tested against fourth instar C. quinquefasciatus larvae. Oleic, linoleic and linolenic acids had LC50 values of 8.58, 10.04 and 19.78 mg/L, respectively. Histological analysis showed that these three compounds caused cell instability with an increase in the number of vesicles in the fat body and in the midgut cells. Based on these results, glucose, triglyceride, and protein levels were evaluated after 1 h of acid exposure. These compounds decreased in insects treated with linoleic acid. Linolenic acid also caused a significant increase in acetylcholinesterase activity. These results show that oleic, linoleic, and linoleic acids have a lower LC50 for C. quinquefasciatus, affecting its metabolism and the morphology of midgut and fat body

Legislative Documents

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