Rock hyrax middens: A palaeoenvironmental archive for southern African drylands

Like many of the world's subtropical regions, southern Africa is highly sensitive to changes in the earth's climate system, but a dearth of reliable palaeoenvironmental records means that relatively little is known about how regional environments have been affected over centennial to multi-millennial timescales. To a large extent this sensitivity is a function of the position of these regions at the interface between temperate and tropical circulation systems. The resulting seasonality and irregularity of rainfall have limited the development of suitable archives, such as lakes and wetlands, for the preservation of palaeoenvironmental proxies.

This paper reviews and evaluates the value of rock hyrax middens as novel palaeoenvironmental archives in southern Africa. Considered are (1) the contemporary taxonomy, distribution and ecology of hyraxes, (2) the mechanisms of hyrax midden development, their physical and chemical structure, rates of accumulation and age; and (3) the palaeoenvironmental proxies preserved within hyrax middens, including fossil pollen, stable isotopes and biomarkers. The interpretive constraints and opportunities offered by these various midden characteristics are assessed with a view to demonstrating the potential of these deposits, widespread as they are through arid and semi-arid southern Africa, in providing a more detailed and chronologically resolved view of late Quaternary palaeoenvironments across the subcontinent. (C) 2012 Elsevier Ltd. All rights reserved.

The molecular dynamics of Trypanosoma brucei UDP-galactose 4'-epimerase:a drug target for African sleeping sickness

During the past century, several epidemics of human African trypanosomiasis, a deadly disease caused by the protist Trypanosoma brucei, have afflicted sub-Saharan Africa. Over 10 000 new victims are reported each year, with hundreds of thousands more at risk. As current drug treatments are either highly toxic or ineffective, novel trypanocides are urgently needed. The T. brucei galactose synthesis pathway is one potential therapeutic target. Although galactose is essential for T. brucei survival, the parasite lacks the transporters required to intake galactose from the environment. UDP-galactose 4'-epimerase (TbGalE) is responsible for the epimerization of UDP-glucose to UDP-galactose and is therefore of great interest to medicinal chemists. Using molecular dynamics simulations, we investigate the atomistic motions of TbGalE in both the apo and holo states. The sampled conformations and protein dynamics depend not only on the presence of a UDP-sugar ligand, but also on the chirality of the UDP-sugar C4 atom. This dependence provides important insights into TbGalE function and may help guide future computer-aided drug discovery efforts targeting this protein.

Senegalin: a novel antimicrobial/myotropic hexadecapeptide from the skin secretion of the African running frog, Kassina senegalensis

Amphibian skin is a rich and unique source of novel bioactive peptides most of which are endowed with either antimicrobial or pharmacological properties. Here we report the identification and structural characterization of a novel peptide, named senegalin, which possesses both activities. Senegalin is a hexadecapeptide amide (FLPFLIPALTSLISSL-NH2) of unique primary structure found in the skin secretion of the African running frog, Kassina senegalensis. The structure of the biosynthetic precursor of senegalin, deduced from cloned skin cDNA, consists of 76 amino acid residues and displays the typical domain organization of an amphibian skin peptide precursor. Both natural senegalin and its synthetic replicate
displayed antimicrobial and myotropic activities. Senegalin was active against Staphylococcus aureus (MIC 50µM) and Candida albicans (MIC 150µM) but was nonhaemolytic at concentrations up to and including 150µM. In contrast, senegalin induced a dose-dependent contraction of rat urinary bladder smooth muscle (EC50 2.9nM) and a dosedependent relaxation of rat tail artery smooth muscle (EC50 37.7nM). Senegalin thus represents a prototype biologically-active amphibian skin peptide and illustrates the fact thatamphibian skin secretion peptidomes continue to be unique sources of such molecules.

Fumonisin B-1 as a Urinary Biomarker of Exposure in a Maize Intervention Study Among South African Subsistence Farmers

Background: The consumption of maize highly contaminated with carcinogenic fumonisins has been linked to high oesophageal cancer rates. The aim of this study was to validate a urinary fumonisin B-1 (UFB1) biomarker as a measure of fumonisin exposure and to investigate the reduction in exposure following a simple and culturally acceptable intervention.

Methods: At baseline home-grown maize, maize-based porridge, and first-void urine samples were collected from female participants (n = 22), following their traditional food practices in Centane, South Africa. During intervention the participants were trained to recognize and remove visibly infected kernels, and to wash the remaining kernels. Participants consumed the porridge prepared from the sorted and washed maize on each day of the two-day intervention. Porridge, maize, and urine samples were collected for FB1 analyses.

Results: The geometric mean (95% confidence interval) for FB1 exposure based on porridge (dry weight) consumption at baseline and following intervention was 4.84 (2.87-8.14) and 1.87 (1.40-2.51) mg FB1/kg body weight/day, respectively, (62% reduction, P < 0.05). UFB1C, UFB1 normalized for creatinine, was reduced from 470 (295-750) at baseline to 279 (202-386) pg/mg creatinine following intervention (41% reduction, P = 0.06). The UFB1C biomarker was positively correlated with FB1 intake at the individual level (r - 0.4972, P < 0.01). Urinary excretion of FB1 was estimated to be 0.075% (0.054%-0.104%) of the FB1 intake.

Conclusion: UFB1 reflects individual FB1 exposure and thus represents a valuable biomarker for future fumonisin risk assessment.

Impact: The simple intervention method, hand sorting and washing, could positively impact on food safety and health in communities exposed to fumonisins. Cancer Epidemiol Biomarkers Prev; 20(3); 483-9. (C)2011 AACR.

Comparative study between African-American and Caucasian Normal Tension Glaucoma patients

Purpose. To evaluate differences in optic disc and visual field damage between African-American and Caucasian Normal Tension Glaucoma (NTG) patients. Methods. We retrospectively selected 33 African-American patients with the diagnosis of NTG and age-matched them with 33 Caucasian patients with the same diagnosis. Three masked observers graded disc photographs and visual fields as being normal, globally damaged or focally damaged for both eyes of the subject. Chi-square test was used to evaluate statistically significant differences between groups. Results. The results of the visual fields showed that in the African-American group, 24% were graded normal, 30% showed global damage, and 46% showed focal damage. This data was compared with the Caucasian group which showed 41% normal graded eyes, 22% with global damage, and 37% with focal damage (p = 0.28). The results of the optic disc photos showed that in the African-American group, 25% were graded normal, 45% showed global damage, and 30% showed focal damage. This data was compared with the Caucasian group which showed 43% graded normal, 32% with global damage, and 25% with focal damage (p=0.16). Conclusions. In our study there was no difference in the frequency of globally damaged, focally damaged, and normal graded discs or visual fields between African-American and Caucasian NTG patients.

European Union Cross-Border Cooperation and Conflict Amelioration

The relevance of European Union (EU) cross-border cooperation for European border con?ict amelioration may be questioned in the contemporary global climate of threat and insecurity posed by forces of ’dark globalisation’. In any case, empirical evidence exposes the limitations of cross-border cooperation in advancing con?ict amelioration in some border regions. Nevertheless, in an enlarged EU which encompasses Central and East European member states and reaches out to neighbouring states through cross-border cooperation initiatives, the number of real and potential border con?icts with which it is concerned has risen exponentially. Fortunately, there are cases of EU ’borderscapes’ that have adopted a cross-border ’peace-building from below’ approach leading to border con?ict amelioration. Unfortunately, countervailing pressures on EU cross-border cooperation from border security regimes (principally Schengen), the Eurozone crisis, EU budgetary constraints, the conceptualisation of ’Europe as Empire’, and the possible recon?guration of the EU itself compromises this approach. Therefore, the path of European integration may well shift from one of inter-state peace-building and regional crossborder cooperation after the Second World War, to border con?ict and coercion in constituting and reconstituting state borders after the recon?guration of the EU.

Financial Taxes and the Sand in the Wheels of Financialization:Legal Challenges for the EU Directive Implementing Enhanced Cooperation in the Area of Financial Transaction Tax

One of the many results of the Global Financial Crisis was the insight that the financial sector is under-taxed compared to other industries. In light of the huge bailouts and continued subsidies for financial institutions that are characterized as too-big-to-fail demands came on the agenda to make finance pay for the mega-crisis it caused. The most prominent examples of such taxes are a Financial Transaction Tax (FTT) and a Financial Activities Tax (FAT). Possible effects of such taxes on the economic constitution and increasingly in particular on the European Single Market have been discussed controversially over the last decades already. Especially with the decision of eleven EU member states to adapt an FTT using the enhanced cooperation procedure a number of additional legal challenges for implementing such a tax have emerged. This paper analyzes how tax measures of indirectly regulating the financial industry differ, what legal challenges they pose, and what their overall contribution would be in making the financial system more stable and resilient. It also analyzes the legal arguments against enhanced cooperation in this area and the legal issues related to the British lawsuit against the Commission’s Directive proposal in the European Court of Justice on grounds of the extra-territoriality application of tax. The paper concludes that the feasibility of an FTT is legally sound and given the FTT’s advantages over a FAT the EU Directive should be implemented as a first step for a European-wide FTT. However, significant uncertainties about its implementation remain at this stage.

Determining the response of African biota to climate change: using the past to model the future

Prediction of biotic responses to future climate change in tropical Africa tends to be based on two modelling approaches: bioclimatic species envelope models and dynamic vegetation models. Another complementary but underused approach is to examine biotic responses to similar climatic changes in the past as evidenced in fossil and historical records. This paper reviews these records and highlights the information that they provide in terms of understanding the local- and regional-scale responses of African vegetation to future climate change. A key point that emerges is that a move to warmer and wetter conditions in the past resulted in a large increase in biomass and a range distribution of woody plants up to 400–500 km north of its present location, the so-called greening of the Sahara. By contrast, a transition to warmer and drier conditions resulted in a reduction in woody vegetation in many regions and an increase in grass/savanna-dominated landscapes. The rapid rate of climate warming coming into the current interglacial resulted in a dramatic increase in community turnover, but there is little evidence for widespread extinctions. However, huge variation in biotic response in both space and time is apparent with, in some cases, totally different responses to the same climatic driver. This highlights the importance of local features such as soils, topography and also internal biotic factors in determining responses and resilience of the African biota to climate change, information that is difficult to obtain from modelling but is abundant in palaeoecological records.