Can sub-Saharan Africa feed itself?

Although global food demand is expected to increase 60% by 2050 compared with 2005/2007, the rise will be much greater in sub-Saharan Africa (SSA). Indeed, SSA is the region at greatest food security risk because by 2050 its population will increase 2.5-fold and demand for cereals approximately triple, whereas current levels of cereal consumption already depend on substantial imports. At issue is whether SSA can meet this vast increase in cereal demand without greater reliance on cereal imports or major expansion of agricultural area and associated biodiversity loss and greenhouse gas emissions. Recent studies indicate that the global increase in food demand by 2050 can be met through closing the gap between current farm yield and yield potential on existing cropland. Here, however, we estimate it will not be feasible to meet future SSA cereal demand on existing production area by yield gap closure alone. Our agronomically robust yield gap analysis for 10 countries in SSA using location-specific data and a spatial upscaling approach reveals that, in addition to yield gap closure, other more complex and uncertain components of intensification are also needed, i.e., increasing cropping intensity (the number of crops grown per 12 mo on the same field) and sustainable expansion of irrigated production area. If intensification is not successful and massive cropland land expansion is to be avoided, SSA will depend much more on imports of cereals than it does today.

Alpha4-integrin (CD49d) expression on bovine peripheral blood neutrophils is related to inflammation of the respiratory system.

Neutrophil emigration from the pulmonary vasculature, is mediated by cellular adhesion molecules (CAM) expressed on the outer membranes of endothelial cells and neutrophils. Although beta(2)-integrin-dependent migration is a major mechanism of neutrophil migration, which was demonstrated by extensive invasion of neutrophils in pulmonary tissue of calves suffering from a genetic deficit in expression of beta(2)-integrins, termed bovine leukocyte adhesion deficiency (LAD), the role of alternative CAM is still unclear. We investigated whether an alternate CAM for beta(2)-integrin function, i.e. the alpha(4)-integrin, was expressed on peripheral blood neutrophils of calves. As we detected basal but significant expression, the effect of naturally acquired pulmonary infection on the expression of either integrin was determined, as an indication for its function in the migration process. In our experiments, basal expression of alpha(4)-integrins on peripheral blood neutrophils from clinically healthy calves was detected. On neutrophils of calves, experiencing field outbreaks of enzootic bronchopneumonia, higher expression of the alpha(4)-integrin was detected, which returned to normal after successful treatment of the disease. In addition, its level of expression was linearly related to plasma acute phase protein (haptoglobin) concentrations, which is a sensitive parameter for severity of respiratory inflammation. Increased expression of the alpha(4)-integrin on peripheral blood neutrophils during pulmonary inflammation indicates a role for this CAM in neutrophil migration in the lung.