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The concept of biocultural diversity, originally used to describe indigenous people and their ways of using and managing natural resources, has more recently been applied within the urban context to understand the variability of interactions between humans and nature. Significant progress has been made internationally in acknowledging the need to preserve and maintain green spaces in urban environments. Current efforts to address the need for greening urban areas in South Africa primarily focus on the establishment and maintenance of botanical gardens and parks as well as various green belts within the urban landscape. South Africa's urban areas are overwhelmingly shaped by the historical segregation of space and stark disparities in wealth. The distribution, quality, and extent of urban green spaces reflect this. Many township dwellers do not have access to these amenities and their interactions with nature are thus usually constrained to access to municipal commonages. This article explores how areas of natural vegetation in municipal commonages on the outskirts of urban centers in South Africa continue to offer places of cultural, spiritual, and restorative importance to Xhosa-speaking township dwellers. A case study from Grahamstown, an urban center in the Eastern Cape with a population of around 80,000, illustrates how ability to access and move through such places contributes to people's well-being, identity formation, and shared heritage. A case is made for adopting a biocultural diversity approach to spatial planning and urban development within the South African context.

Spinach chloroplast NAD(P)-glyceraldehyde-3-phosphate dehydrogenase (NAD(P)-GAPDH; EC, 1.2.1.13) was purified as the 600-kDa oligomer of low specific activity. Incubation of the enzyme with either a reductant or a 1,3-bisphosphoglycerate (1,3bisPGA) generating system, but most effectively with both, resulted in an increase of the apparent NADPH-dependent activity. Only the 1,3bisPGA treatment caused dissociation and yielded the 150-kDa heterotetramer (A2B2). The higher activity of the tetramer is largely due to a decreasedKMvalue for the substrate 1,3bisPGA. Reductive treatment alone does not dissociate the enzyme. Reduction was equally effective with glutathione as with dithiothreitol or with reduced thioredoxin f. The concentration of 1,3bisPGA required to obtain 50% activity (Ka) was 19.5 ± 4.1 μMfor the untreated enzyme and 2.0 ± 1.4 μMfor the thiol-pretreated enzyme. Thus,in vitro1,3bisPGA, alone or—at much lower concentrations—together with a reductant can activate (and dissociate) NAD(P)-GAPDH. The enzyme exhibits similarKavalues in its reduced and its oxidized form for ATP (1–2 mM), NADP (50–200 μM), and NADPH (0.3–0.5 mM) as positive effectors, but these effectors do not lead to any activation when present together with 0.14 mMNAD. Only 1,3bisPGA retained its characteristic effect in the presence of NAD. The dissociated enzyme reaggregates upon removal of the positive effectors. From these results it is concluded (i) that the role of the reduction of the NAD(P)-GAPDHin vivois to increase its sensitivity toward the activator 1,3bisPGA and (ii) that the actual activation (and aggregation) state of the enzyme in chloroplasts in the light is regulated by the concentration of 1,3bisPGA as activator in the stroma and its actual activity by the availability of 1,3bisPGA as substrate.

Abstract.: Chloroplasts isolated from spinach (Spinacia oleracea L.) leaves and green sweet-pepper (Capsicum annuum L. var. grossum (L.) Sendt.) fruits contain NADP-dependent malate dehydrogenase (MDH; EC 1.1.1.82) and the bispecific NAD(P)-glyceraldehyde 3-phosphate dehydrogenase (GAPDH; EC 1.2.1.13). The NADP-dependent MDH and GAPDH are activated in the light, and inactive in the dark. We found that chloroplasts possess additional NAD-dependent MDH activity which is, like the NAD-dependent GAPDH activity, not influenced by light. In heterotrophic chromoplasts from red sweet-pepper fruits, the NADP-dependent MDH and the NAD(P)-GAPDH isoenzymes disappear during the developmental transition and only NAD-specific isoforms are found. Spinach chloroplasts contain both NAD/H and NADP/H at significant concentrations. Measurements of the pyridine dinucleotide redox states, performed under dark and various light conditions, indicate that NAD(H) is not involved in electron flow in the light. To analyze the contribution of NAD(H)-dependent reactions during dark metabolism, plastids from spinach leaves or green and red sweet-pepper fruits were incubated with dihydroxyacetone phosphate (DHAP). Exogenously added DHAP was oxidized into 3-phosphoglycerate by all types of plastids only in the presence of oxaloacetate, but not with nitrite or in the absence of added electron acceptors. We conclude that the NAD-dependent activity of GAPDH is essential in the dark to produce the ATP required for starch metabolism; excess electrons produced during triose-phosphate oxidation can selectively be used by NAD-MDH to form malate. Thus NADPH produced independently in the oxidative pentose-phosphate pathway will remain available for reductive processes inside the plastids.