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Scientists focusing on climate change in east Africa are interrogating climate models to provide more reliable information for decision-makers. Their burning questions include:\ud \ud • How will aspects of climate that are relevant to decision-makers change? Will heavy rain and droughts increase? Will the region get wetter or drier in future?\ud \ud • How will climate change impact on above- and below-ground water flow, the water levels of Lake Victoria, and underground water storage?\ud \ud • What are the implications for rural livelihoods, including those dependent on rain-fed agriculture and fishing? And what are the policy and governance considerations within these sectors?\ud \ud • How can cities design the most resilient water, sanitation and hygiene systems, in light of future climate change predictions?

Rising temperatures and changing rainfall patterns will have significant impacts across east African society. Decision-makers need accessible information on likely climate change if they are to plan appropriately for this uncertain future. This factsheet considers how the climate is likely to change in east Africa, and the likely implications for: • water availability • sanitation • livelihoods, including agriculture and fresh water fisheries • hydropower • the potential for wind energy.

Rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (Pisum sativum) and vetch (Vicia cracca), and has been widely used as a model to study nodule biochemistry. To understand the complex biochemical and developmental changes undergone by R. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate, and acetoacetate) and then compared to bacteroids. Bacteroid metabolism is essentially that of dicarboxylate-grown cells (i.e., induction of dicarboxylate transport, gluconeogenesis and alanine synthesis, and repression of sugar utilization). The decarboxylating arm of the tricarboxylic acid cycle is highly induced, as is gamma-aminobutyrate metabolism, particularly in bacteroids from early (7-day) nodules. To investigate bacteroid development, gene expression in bacteroids was analyzed at 7, 15, and 21 days postinoculation of peas. This revealed that bacterial rRNA isolated from pea, but not vetch, is extensively processed in mature bacteroids. In early development (7 days), there were large changes in the expression of regulators, exported and cell surface molecules, multidrug exporters, and heat and cold shock proteins. fix genes were induced early but continued to increase in mature bacteroids, while nif genes were induced strongly in older bacteroids. Mutation of 37 genes that were strongly upregulated in mature bacteroids revealed that none were essential for nitrogen fixation. However, screening of 3,072 mini-Tn5 mutants on peas revealed previously uncharacterized genes essential for nitrogen fixation. These encoded a potential magnesium transporter, an AAA domain protein, and proteins involved in cytochrome synthesis.