Genotoxic effect induced by hydrogen peroxide in human hepatoma cells using comet assay

Background: Hydrogen peroxide is a common reactive oxygen intermediate generated by variousforms of oxidative stress. Aims: The aim of this study was to investigate the DNA damage capacity ofH2O2 in HepG2 cells. Methods: Cells were treated with H2O2 at concentrations of 25 μM or 50 μM for5 min, 30 min, 40 min, 1 h or 24 h in parallel. The extent of DNA damage was assessed by the cometassay. Results: Compared to the control, DNA damage by 25 μM and 50 μM H2O2 increasedsignificantly with increasing incubation time up to 1 h, but it was not increased at 24 h. Conclusions:Our Findings confirm that H2O2 is a typical DNA damage inducing agent and thus is a good modelsystem to study the effects of oxidative stress. DNA damage in HepG2 cells increased significantlywith H2O2 concentration and time of incubation but later decreased likely due to DNA repairmechanisms and antioxidant enzyme

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Citizen science for the prediction of climate extremes in South Africa and Namibia

Seasonal-to-interannual variations of rainfall over southern Africa, key to predicting extreme climatic events, are predictable over certain regions and during specific periods of the year. This predictability had been established by testing seasonal forecasts from models of varying complexity against official station rainfall records typically managed by weather services, as well as against gridded data sets compiled through a range of efforts. Members of the general public, including farmers, additionally have extended records of rainfall data, often as daily values spanning several decades, which are recorded and updated regularly at their farms and properties. In this paper, we show how seasonal forecast modelers may use site recorded farm rainfall records for the development of skillful forecast systems specific to the farm. Although the uptake of seasonal forecasts in areas with modest predictability such as southern Africa may be challenging, we will show that there is potential for financial gain and improved disaster risk farm management by co-developing with farmers forecast systems based on a combination of state-of-the-art climate models and farm rainfall data. This study investigates the predictability of seasonal rainfall extremes at five commercial farms in southern Africa, four of which are in the austral summer rainfall areas, while one is located in the winter rainfall area of the southwestern Cape. We furthermore calculate a measure of cumulative profits at each farm, assuming a “fair odds” return on investments made according to forecast probabilities. The farmers are presented with hindcasts (re-forecasts) at their farms, and potential financial implications if the hindcasts were used in decision-making. They subsequently described how they would use forecasts for their farm, based on their own data.The National Research Foundation of South Africa (NRF)https://www.frontiersin.org/journals/climatepm2021Geography, Geoinformatics and Meteorolog

Seasonal forecasts for the Limpopo Province in estimating deviations from grazing capacity

Application of seasonal forecasts in agriculture has significant potential and realized utility. Other sectors that may also benefit from using seasonal forecasts include (but are not limited to) health, hydrology, water, and energy. This paper shows that seasonal forecast model data, satellite Pour l’Observation de la Terre (SPOT), dry matter productivity (DMP) data (proxy of grass biomass) along with other sets of data are effectively used to estimate grazing capacity (GC) over a 12-year test period (1998/1999–2009/2010) in Limpopo Province. GC comprises a vital consideration in agricultural activities, particularly for a province in South Africa like Limpopo, due to its varying climate. The Limpopo Province capitalizes on subsistence farming, including livestock and crop production. Grazing should thus be regulated in order to conserve grass, shrubs, and trees, thereby ensuring sustainability of rangelands. In a statistical downscaling model, the predictor is the 850 geopotential height fields of a coupled ocean–atmosphere general circulation (CGCM) over Southern Africa to predict seasonal DMP values. This model shows that the mid-summer rainfall totals are important predictors for the November through April (NDJFMA) DMP (as well as grazing capacity) growing season. Forecast verification is conducted using the relative operating characteristics (ROC) and reliability diagrams. The CGCM model shows skill in discriminating high and low DMP (GC) seasons in the Limpopo Province, as well as reliability in the probabilistic forecasts. This paper demonstrates the development of a tailored forecast, an avenue that should be explored in enhancing relevance of forecasts in agricultural production.The Agricultural Research Councilhttp://link.springer.com/journal/7042019-11-10hj2018Geography, Geoinformatics and Meteorolog

South Africa’s winter rainfall region drought : a region in transition?

The Western Cape region of South Africa is a key producing area for South African agriculture, with a strong dependence on austral winter rainfall. The past three years have, however, seen extensive drought impacting this region, with significant impacts on agriculture. In this article, we unpack how the drought unfolded, as well as possibilities in predicting winter rainfall. We consider how drought impacted agriculture, looking in depth at two commodities key to the winter rainfall region agricultural sector – namely, wheat and apples; concluding with a brief discussion of implications for the future.https://www.elsevier.com/locate/crmam2020Geography, Geoinformatics and Meteorolog

Managing climate risk in livestock production in South Africa : how might improved tailored forecasting contribute?

The 2015–2017 summer rainfall seasons in both South and southern Africa saw drought and heat stress severely impacting the livestock production sector, as well as agriculture more broadly. Although the region has a longstanding operational forecasting system; tailored forecasting, including that designed for the livestock sector, has declined in presence and operational use in recent years. The potential use of such information to enable the livestock sector to better cope with difficult seasons such as those of 2015–17 is clear. A range of promising initiatives attempt to move South Africa (and the broader southern Africa region) in the direction of improved tailored forecasting, integrated, in part, into the operational system. A number of gaps in application remain, however, and the paper concludes with a discussion as to how the field might move forward, particularly in the light of possible increased frequency of drought and heat stress in the future.A National Research Foundation (NRF) Rated Researchers’ Incentive grant; SASSCAL project 203 and the Agricultural Research Council (ARC) Professional Development Programme (PDP).https://www.elsevier.com/locate/crmpm2021Geography, Geoinformatics and Meteorolog

Understanding the evolution of the 2014–2016 summer rainfall seasons in southern Africa : key lessons

The recent 2015/16 summer rainfall season in the terrestrial Southern African Development Community (SADC) region appears to be the most severe since the droughts of the early 1980s and 1990s; with well-publicized significant impacts on agriculture and food security. Impacts have been particularly concerning since the 2015/6 season followed a poor rainy season in 2014/15, in certain areas compounding already compromised production (total maize production was, for example, down 40% relative to the previous 5 year average). This paper reviews climate forecasts and observations of the two seasons, and presents examples of the resulting impacts on agriculture within the region. We conclude by considering what may be learnt from this experience, focussing on operational recommendations for early warning within SADC, as well as longstanding needs for awareness raising and capacity building.The authors would like to thank the SASSCAL programme, who supported elements of the work and analysis presented here (SASSCAL project 203), as well as Michael Bell of the IRI, and the UMFULA programme (Emma Archer is partly supported by UK NERC Grant Ref: NE/M020398/1) under Future Climate for Africa (www.futureclimateafrica.orghttp://www.elsevier.com/locate/crmam2017Geography, Geoinformatics and Meteorolog

Agency as vulnerability : accounting for children's movement to the streets of Accra

This paper considers the agency of children moving to the streets of Accra, Ghana's capital city. A much used but largely unexamined concept, agency is nevertheless commonly deployed in childhood studies as a means to stress the capacity of children to choose to do things. In the literature on street and working children, and a cognate area of study concerned with children's independent migration, this has involved accounts of children's agency made meaningful by reference to theories of rational choice or to the normative force of childhood. It is our argument that both approaches leave unanswered important questions and to counter these omissions we draw upon the arguments of social realists and, in particular, the stress they place on vulnerability as the basis for human agency. We develop this argument further by reference to our research with street children. By drawing upon the children's accounts of leaving their households and heading for Accra's streets, it is our contention that these children do frame their departures as matters of individual choice and self-determination, and that in doing so they speak of a considerable capacity for action. Nevertheless, a deeper reading of their testimonies also points to the children's understandings of their own vulnerability. By examining what we see as their inability to be dependent upon family and kin, we stress the importance of the children's perceptions of their vulnerability, frailty and need as the basis for a fuller understanding of their agency in leaving their households

Brazilian plant specimens at the Regnellian herbarium:history and repatriation : Brazilian plant specimens at the Regnellian herbarium (S)

This article visits the history of Brazil-Sweden’s partnership in botany and the contribution of Anders Fredrik Regnell and other botanical collectors to the knowledge of Brazilian flora. The importance of the herbarium of Stockholm (S) is widely recognized for its collections of Brazilian plants, one of the largest in the world. The majority of the collections from Brazil date from the period between the second half of nineteenth century and the beginning of the twentieth century. The main collectors of Brazilian flora from that phase, whose bulk of collections are in Stockholm are Anders Regnell, Gustaf Malme, Per Dusén, Carl Lindman and many others sponsored by the Regnellian fund. The herbarium also houses substantial collections of August Glaziou, a great contributor to the knowledge of the flora of state of Goiás, and Adolf Ducke, pioneer in the taxonomy of Amazonian tree species. The cooperation between Brazil and Sweden is currently being renewed through Rio de Janeiro Botanical Garden and the Reflora Program, allowing repatriation of Brazilian specimens housed in Stockholm