Preliminary economic assessment of water resources of the Pangani River Basin, Tanzania

River basin managementWater useWater allocationEconomic evaluationDomestic waterIrrigation waterLivestockWater power

Preliminary economic assessment of water resources of the Pangani River Basin, Tanzania: economic values and incentives

River basinsEconomic analysisDomestic waterIrrigated farmingLivestockPolicyWater supplyFinancing

Comparative description of land use and characteristics of belowground biodiversity benchmark sites in Kenya = Descripción comparativa de usos del suelo y características de la diversidad del subsuelo en sitios empleados como referencia en Kenia

In Kenya, the below-ground biodiversity (BGBD) project selected two benchmark sites for the inventory of soil biota; these included the Irangi and Ngangao forest sites in the Mount Kenya region of Embu District and the Taita Hills area of Taita Taveta District. The areas selected by the project were located in biodiversity hotspots that are supporting rare and endemic plant and animal species. For more in-depth studies and analysis, the broader Embu and Taita benchmark areas were further sub-sampled into smaller areas that we refer to as study areas, designated by the symbols E1 and E2 for Embu and T1 and T2 for Taita benchmark. Within the study areas, we plotted and sampled 200x200 square grids for collecting soil as well as socio-economic data. Site characterization was carried out using the method provided by FAO-UNESCO for characterizing and classifying soils. Further to this, attempts were made to establish land use intensity (LUI) and land productivity (PI) indices that provided land condition indicators. The indicators offered insights into the quantitative relationship between the environmental conditions and land use. Parameters used in the computation of the land use intensity were; total quantity of inputs per ha, the frequency of input application, cropping intensity and cultivation frequency. The soils in Taita Taveta benchmark site were classified as Plinthic Lixisols, Plinthic Acrisols, Dystric Cambisols and Chromic Luvisols, while those from Embu ones were Rhodic Nitisols, Humic Nitisols, Humic Acrisols, Haplic Acrisols and Umbric Andosols. The highest level of soil organic carbon recorded was 7.6% in the forest and the lowest value of 1.6% in intensely cultivated maize-based and horticultural systems. Low land use intensity gradients were observed in the forests (LUI40%). The productivity index (PI) followed a similar trend, being highest in the natural forest and grassland (40-50%) and lowest in horticultural and maize-based systems (15-20%) It was concluded that the decline in soil quality and productivity was linked to increased land use intensification and lack of knowledge of the appropriate management practices for sustainable ecosystem functions and services

Rift Valley fever virus seroprevalence among ruminants and humans in northeast Kenya

Rift Valley fever (RVF) is a zoonotic vector-borne disease present in much of Africa, and the Arabic peninsula. During outbreaks, the case fatality is high in young ruminants and there may be abortion storms, human disease is usually mild but some may suffer fatal hemorrhagic fever. Outbreaks in East Africa occur after periods of heavy prolonged rains, such as during El Niño southern oscillations, which lead to a sudden increase in the number of vectors hatched. Between outbreaks, there are indications that the virus is still circulating in some ecologies. Kenya has suffered repeated serious outbreaks of RVF, with high morbidity in humans and animals, and also severe economic consequences. In the northern of Kenya, a hot spot for RVF outbreaks, there are continuous expansions of irrigation schemes, which enable the societies to be less susceptible to droughts. However, there are concerns that the increased irrigation would provide more vector breeding grounds, and thus cause people living close to be more exposed to vector-borne diseases. In this study, 1117 serum samples were collected from humans in the age 5-90 years old, in the irrigated area, a riverine area, and the close-by district where people are fully depending on pastoralism. Samples were tested with a competitive ELISA detecting both IgM and IgG antibodies. Overall seroprevalence was 21.9%, and univarible analyses could find no difference between the three areas, but men were found to be significantly more seropositive than women (26.2 and 18.8% respectively, p=0.004). Ruminants (sheep, goats, and cattle) were also sampled within the irrigation. A total of 1997 animals were sampled, and tested with the same ELISA as the human samples. Overall seroprevalence was 25.6%, with no difference between the seroprevalences in goats, sheep and cattle. Juveniles had lower seroprevalence rates than adults, 12.3% compared to 30.2% (p<0.001). Since the last outbreak occurred in 2006-2007, juveniles could not have been infected during that outbreak. In conclusion, the study confirms that RVF can be circulating in ruminants between epidemics in irrigation schemes. However, the human sampling did not show any evidence that living in irrigation schemes would make people more exposed, although the exposure detected here is cumulative and longitudinal surveys may be more suitable to detect differences in infection rates

Replication stress by Py–Im polyamides induces a non-canonical ATR-dependent checkpoint response

Pyrrole–imidazole polyamides targeted to the androgen response element were cytotoxic in multiple cell lines, independent of intact androgen receptor signaling. Polyamide treatment induced accumulation of S-phase cells and of PCNA replication/repair foci. Activation of a cell cycle checkpoint response was evidenced by autophosphorylation of ATR, the S-phase checkpoint kinase, and by recruitment of ATR and the ATR activators RPA, 9-1-1, and Rad17 to chromatin. Surprisingly, ATR activation was accompanied by only a slight increase in single-stranded DNA, and the ATR targets RPA2 and Chk1, a cell cycle checkpoint kinase, were not phosphorylated. However, ATR activation resulted in phosphorylation of the replicative helicase subunit MCM2, an ATR effector. Polyamide treatment also induced accumulation of monoubiquitinated FANCD2, which is recruited to stalled replication forks and interacts transiently with phospho-MCM2. This suggests that polyamides induce replication stress that ATR can counteract independently of Chk1 and that the FA/BRCA pathway may also be involved in the response to polyamides. In biochemical assays, polyamides inhibit DNA helicases, providing a plausible mechanism for S-phase inhibition

Post-harvest evaluation of selected hybrids to maize weevil Sitophilus zeamais resistance

Sitophilus zeamais has been identified as one of the most destructive pests of maize stored in tropical regions. While most maize hybrids are being developed, it is necessary to evaluate their resistance to this pest. This study determined the resistance of selected maize hybrids to infestation by S. zeamais. Twenty two hybrids with varying resistance to weevil infestation and two checks DUMA 41-suceptible and MTP0701-resistant were used in a randomized complete block design experiment. Assessment was done at 10, 60 and 120 days of maize storage. Data was collected on percent weevil damage, grain weight loss and number of live and dead weevils. Heritability and correlation of factors were also estimated. Analysis of variance showed significant differences (P ≤ 0.05) on weight loss. The selection of the resistant genotypes was based on percent weight loss after 60 days. KH631Q and PH4 were selected as the most resistant and moderately resistant hybrids, respectively. The resistant check MTPO701 was also found to maintain resistance to weevil attack. There was a strong positive correlation between weight loss, number of live weevils and percent damage. Moderate heritability estimates of hybrids at 60 days of storage indicated the possibility of their parents to transfer the desirable traits to subsequent generations. Therefore, parents of the resistant hybrids could be utilized in breeding programs for maize weevil resistance and be deployed to farmers for use, respectively

Organic maize and bean farming enhances free-living nematode dynamics in sub-Saharan Africa

Published online: 03 Jan 2022Despite their important ecological roles for soil health and soil fertility, free-living nematodes (FLN) have received relatively limited research attention. The present study evaluated the community structure and diversity of FLN in a field setting. The experiments were conducted in on-farm and on-station field plots sown to maize (Zea mays) and beans (Phaseolus vulgaris) under four cropping practices. These farming systems included organic (compost and biopesticide use), conventional (synthetic fertilizer and pesticide applications), farmer practice (organic and synthetic amendments) and a control (non-amended plots). Nineteen genera of free living nematodes, belonging to bacterivores, fungivores, omnivores and predators were recorded. Among these, bacterivores (Cephalobidae and Rhabditidae) were the most dominant group in the organic systems when compared to the conventional and control systems. Farming systems influenced the abundance and diversity of free living nematodes, with the organic farming system having higher values of maturity, enrichment and structural indices than other farming systems. This would indicate greater stability in soil health and improved soil fertility. This implies that the organic farming systems play a key role in improving the biodiversity and population buildup of FLN, compared with other systems. Our study helps to improve our understanding of how farming systems influence soil biodynamics, while studies on the longer-term effects of organic and conventional farming systems on the build-up or reduction of free living nematodes for improved ecosystem services are needed