Suchergebnisse

The SARS-CoV-2 virus, since its appearance in 2019, has caused millions of cases and deaths. To date, there is no effective treatment or a vaccine that is fully protective. Despite the efforts made by governments and health institutions around the globe to control its propagation, the evolution of the virus has accelerated, diverging into hundreds of variants. However, not all of them are variants of concern (VoC's). VoC's have appeared in different regions and throughout the two years of the pandemic they have spread around the world. Specifically, in South America, the gamma variant (previously known as P.1) appeared in early 2021, bringing with it a second wave of infections. This variant contains the N501Y, E484K and K417T mutations in the receptor binding domain (RBD) of the spike protein. Although these mutations have been described experimentally, there is still no clarity regarding their role in the stabilization of the complex with the human angiotensin converting enzyme 2 (hACE-2) receptor. In this article we dissect the influence of mutations on the interaction with the hACE-2 receptor using molecular dynamics and estimations of binding affinity through a screened version of the molecular mechanics Poisson Boltzmann surface area (MM-PBSA) and interaction entropy. Our results indicate that mutations E484K and K417T compensate each other in terms of binding affinity, while the mutation N501Y promotes a more convoluted effect. This effect consists in the adoption of a cis configuration in the backbone of residue Y495 within the RBD, which in turn promotes polar interactions with the hACE-2 receptor. These results not only correlate with experimental observations and complement previous knowledge, but also expose new features associated with the specific contribution of concerned mutations. Additionally, we propose a recipe to assess the residue-specific contribution to the interaction entropy.

The SARS-CoV-2 virus, since its appearance in 2019, has caused millions of cases and deaths. To date, there is no effective treatment or a vaccine that is fully protective. Despite the efforts made by governments and health institutions around the globe to control its propagation, the evolution of the virus has accelerated, diverging into hundreds of variants. However, not all of them are variants of concern (VoC's). VoC's have appeared in different regions and throughout the two years of the pandemic they have spread around the world. Specifically, in South America, the gamma variant (previously known as P.1) appeared in early 2021, bringing with it a second wave of infections. This variant contains the N501Y, E484K and K417T mutations in the receptor binding domain (RBD) of the spike protein. Although these mutations have been described experimentally, there is still no clarity regarding their role in the stabilization of the complex with the human angiotensin converting enzyme 2 (hACE-2) receptor. In this article we dissect the influence of mutations on the interaction with the hACE-2 receptor using molecular dynamics and estimations of binding affinity through a screened version of the molecular mechanics Poisson Boltzmann surface area (MM-PBSA) and interaction entropy. Our results indicate that mutations E484K and K417T compensate each other in terms of binding affinity, while the mutation N501Y promotes a more convoluted effect. This effect consists in the adoption of a cis configuration in the backbone of residue Y495 within the RBD, which in turn promotes polar interactions with the hACE-2 receptor. These results not only correlate with experimental observations and complement previous knowledge, but also expose new features associated with the specific contribution of concerned mutations. Additionally, we propose a recipe to assess the residue-specific contribution to the interaction entropy.

Resumo: Este artigo analisa as transformações nas condições de trabalho na atividade canavieira à luz da legislação brasileira nas últimas duas décadas, período em que o setor se expandiu e adotou novas soluções tecnológicas e caminhos gerenciais. Um tema central é compreender os efeitos da mecanização do corte da cana, que chegou a 90% da safra nacional, em média. Foram catalogados 15.488 autos de infração trabalhistas, emitidos pelos fiscais do governo federal entre 2000 e 2019, contra os 280 grupos empresariais autorizados pela ANP, tanto em suas operações agrícolas quanto industriais. Para permitir comparações, dividiu-se o país em três regiões – São Paulo, Nordeste e Demais UFs. O artigo demonstra que as irregularidades mais comuns se referem a saúde e segurança do trabalhador, descanso obrigatório, jornada e remuneração. A emissão de autos registrou tendência de alta até 2013, diante da expansão canavieira e da estratégia das autoridades em pressionar o setor e melhorar a imagem do etanol brasileiro. A aplicação de multas passou a cair em 2014. Entre as principais causas, intensificação da colheita mecanizada, que reduziu a quantidade de trabalhadores no corte manual, etapa na qual se concentravam irregularidades, e redução do ímpeto da fiscalização, diante da crise fiscal do país.

Abstract: This article analyses changes in working conditions in sugarcane in the light of Brazilian legislation in the 20 years, when the sector expanded and adopted new technological solutions and management paths. A central theme is understanding the effects of harvesting mechanization, which reached 90% of the national production on average. In total, 15,488 notices of violation were analysed, issued between 2000 and 2019 against the 280 business groups authorized by the ANP (National Agency for Petroleum, Natural Gas and Biofuels) to produce fuel ethanol from sugarcane, both in their agricultural and industrial operations. For comparisons purposes, the country was divided into three major producing regions – São Paulo, Northeast and Other States. The most common irregularities refer to workers' health and safety, mandatory rest, working hours, and pay. Notices of violation saw an upward trend until 2013, given the expansion of sugarcane throughout the country and authorities' strategy to pressure the sector and improve Brazilian ethanol's international reputation. The number of fines began to fall in 2014. Among the causes, intensification of mechanized harvesting reduced the number of workers in manual cutting – where irregularities were concentrated – and reduction in the impulse towards enforcement, given the Brazilian government's fiscal crisis.