Histofarcin test for the diagnosis of epizootic lymphangitis in Ethiopia: development, optimisation, and validation in the field

Histofarcin, a skin test antigen for the diagnosis of epizootic lymphangitis, was locally produced from the mycelial form of Histoplasma capsulatum var. farciminosum (HCF) in disease-endemic districts of Ethiopia and tested for its application in the field between April 2002 and May 2003. The test was evaluated using 108 mules, 84 in endemic and 24 in disease-free districts. Microscopic and mycological examinations of clinical lesions were used as the "gold standard" for the validation of the test. The concentration of histofarcin that caused an optimum reaction was 0.2-0.4 mg/mL in a 0.1 mL dose and this was attained 24-48 h post-injection. The sensitivity and specificity of the histofarcin test were 90.3% (CI = 73.1, 97.5) and 69% (95%, CI = 48.1, 84.9%) in disease-endemic districts. On the other hand, specificity was 100% (CI=94.8, 100) in disease-free districts. Positive and negative predictive values of the histofarcin test were 77.78% (95% CI = 60.4, 89.3) and 85.71% (95% CI = 62.6, 96.2), respectively. A marginal substantial agreement (kappa = 0.61, P = 0.0000) was observed between the clinical status and the result of the histofarcin test. A large proportion (31%) of 'false positives' was recorded in endemic districts, which could be due to the pre-clinical stage of the disease. The latter ended in lower specificity and positive predictive value of the test since the true infection status of a 'false positive' could not be known on the basis of clinical features. Therefore, standard test validation procedures including slaughtering and isolation of HCF is required. After proper validation, we conclude that the histofarcin test could play a significant role in detecting early infection, and differentiating of EL from glanders, ulcerative lymphangitis, and sporotrichosis.     

Arbuscular mycorrhizal association of indigenous agroforestry tree species and their infective potential with maize in the rift valley, Ethiopia

Tree species in agroforestry are important source of inoculum for companion agricultural crops. Agroforestry trees can serve as a source of Arbuscular mycorrhiza (AM) inoculants to intercropped annuals. We studied spore abundance, root colonization of Albizia gummifera (J.F. Gmel.) and Croton macrostachyus (Hochst Ex Del.) trees and their effect on colonization of maize. Soil and root samples were collected from field standing trees from under and outside the canopy of trees and maize crops in the main rainy season. The number of spore count was significantly higher under the canopy of A. gummifera (791/100 g of dry soil) and C. macrostachyus (877/100 g of dry soil) trees than outside the canopy (547 and 588/100 g of dry soil, respectively). The level of root colonization of C. macrostachyus (45 %) was higher than A. gummifera (41 %). Root colonization of maize crops grown under the canopy of A. gummifera and C. macrostachyus trees was significantly higher than outside the canopy (P < 0.001). Maize seedlings grown on non-sterilized soils collected under and outside the canopy of A. gummifera and C. macrostachyus trees recorded higher root colonization, plant height, shoot and root dry weight than grown on sterilized soils (P < 0.001). The percentage of AM colonized roots of Zea mays seedlings was significantly positively correlated with the number of spore counts for field soils. The rhizospheres of indigenous agroforestry perennial species are important source of inoculum for annuals. The integration of perennials and annuals in an agroforestry system enhances the maintenance of soil quality in the tropics.     

First confirmation of foot and mouth disease virus serotype SAT-1 in cattle and small ruminants in Ethiopia in 2007/08

The study was conducted in three regional states of Ethiopia: Amhara, Oromia, and the Southern Nations Nationalities and people regional state from August 2007 to April 2008 with the objective of identifying the foot and mouth disease virus (FMDV) serotypes circulating in the region. Two serotypes were recorded from epithelial tissue and oesophageal–pharyngeal (OP) fluid that were taken from outbreaks in study regions of Ethiopia. Serotype O FMDV was identified in Girar Jarso, Yabello, and Ankesha Guagusa districts while SAT-1 was isolated in Surma and Maji districts from tissue samples and this was the first report of the FMDV serotype in Ethiopia. Similarly, the OP fluid samples were found positive for SAT-1 FMDV in Maji and Surma districts.     

Micro-nutrient composition and end-user acceptable quality in potato in Ethiopia

Micronutrient deficiencies in diets, including iron (Fe) and zinc (Zn), are an important public health problem across population in Ethiopia. Potato is a modest source of dietary nutrients. The purpose of this study was to assess the mineral (Fe & Zn) composition of potato germplasm in Ethiopia and grower's willingness to try new potato types. The Fe and Zn contents were assessed in peeled tubers of popular farmer varieties, and newly introduced Andean diploid group Phureja accessions and improved tetraploid clones grown in multi-location trials. Grower's preferences for the new potato types was assessed using a participatory approach. Significant variations in mineral and tuber yield traits exist among the germplasm assessed and broad-sense heritability appears to be high for most traits measured, suggesting that progress through breeding can be made among these materials. However, the slightly negative correlation of tuber yield with Fe and Zn content and user appreciation traits found in this study suggests that progress in improving crops for yield and enhanced Fe and Zn concentrations with end-user acceptable quality will be challenging. The results from this study provide baseline information on Fe and Zn composition of many popular farmer varieties in Ethiopia and end-user preference criteria for evaluating new potato varieties that would help to orient the biofortification breeding to the conditions and preference of farmers.     

Labile, recalcitrant, and microbial carbon and nitrogen pools of a tallgrass prairie soil in the US Great Plains subjected to experimental warming and clipping

Carbon (C) and nitrogen (N) fluxes are largely controlled by the small but highly bio-reactive, labile pools of these elements in terrestrial soils, while long-term C and N storage is determined by the long-lived recalcitrant fractions. Changes in the size of these pools and redistribution among them in response to global warming may considerably affect the long-term terrestrial C and N storage. However, such changes have not been carefully examined in field warming experiments. This study used sulfuric acid hydrolysis to quantify changes in labile and recalcitrant C and N fractions of soil in a tallgrass prairie ecosystem that had been continuously warmed with or without clipping for about 2.5 years. Warming significantly increased labile C and N fractions in the unclipped plots, resulting in increments of 373 mg C kg⁻¹ dry soil and 15 mg N kg⁻¹ dry soil, over this period whilst clipping significantly decreased such concentrations in the warmed plots. Warming also significantly increased soil microbial biomass C and N in the unclipped plots, and increased ratios of soil microbial/labile C and N, indicating an increase in microbial C- and N-use efficiency. Recalcitrant and total C and N contents were not significantly affected by warming. For all measured pools, only labile and microbial biomass C fractions showed significant interactions between warming and clipping, indicating the dependence of the warming effects on clipping. Our results suggest that increased soil labile and microbial C and N fractions likely resulted indirectly from warming increases in plant biomass input, which may be larger than warming-enhanced decomposition of labile organic compounds.     

Increased grain protein content and its association with agronomic and end-use quality in two hard red spring wheat populations derived from Triticum turgidum L. var. dicoccoides

Suitability of wheat (Triticum aestivum L.) for many food products depends on its unique protein. Elevated grain protein content (GPC) and its quality influences the bread making properties of wheat. The objective of this study was to examine the association of elevated GPC with agronomic and end-use quality in two hard red spring wheat recombinant inbred (RI) populations derived from wild emmer (Triticum turgidum L. var. dicoccoides). The two hard red spring populations (ND683/Bergen and Glupro/Bergen) were developed using a single-seed-descent method. ND683 and ‘Glupro’ are high in GPC (180 g kg^-1), presumably due to the introgression of gene(s) from Triticum turgidum L. var. dicoccoides and ‘Bergen’ is low in GPC (145 g kg^-1). From each of the two populations 12 high- and 12 low-GPC RI lines (F_5:7) were selected for replicated testing at two North Dakota (ND) locations in 1995. In both populations, the high-GPC lines had significantly (p < 0.05) higher values compared to the low-GPC lines for mean GPC and water absorption. Mean grain yield of the high-GPC lines was not significantly different from the low-GPC lines in both populations. In the ND683/Bergen population, the high-GPC lines had significantly (p < 0.05) higher values than the low-GPC lines for mean plant height, days to heading, and flour extraction. GPC was significantly (p < 0.05)and negatively associated with test weight and also significantly (p < 0.01) and positively associated with water absorption in the Glupro/Bergen population. In these populations, results suggested that it may be possible to select lines that combine higher GPC and acceptable yield level, but later in maturity and taller in plant height. This revised version was published online in July 2006 with corrections to the Cover Date.     

Australopithecus garhi: a new species of early hominid from Ethiopia

The lack of an adequate hominid fossil record in eastern Africa between 2 and 3 million years ago (Ma) has hampered investigations of early hominid phylogeny. Discovery of 2.5 Ma hominid cranial and dental remains from the Hata beds of Ethiopia's Middle Awash allows recognition of a new species of Australopithecus. This species is descended from Australopithecus afarensis and is a candidate ancestor for early Homo. Contemporary postcranial remains feature a derived humanlike humeral/femoral ratio and an apelike upper arm-to-lower arm ratio.     

Increased number of large non‐atretic follicles and co‐dominance effects account for high litter sizes in Bonga sheep

To understand the ovarian basis for prolificacy of Bonga sheep, a total of 31 ewes were selected based on litter size (LS) records and divided into two groups: High Prolificacy (HP) (n = 20) with LS ≥ 2 and Low Prolificacy (LP) (n = 11) with LS = 1. At a synchronized estrus, follicular dynamics were determined using transrectal ultrasonography. Plasma estradiol concentrations were also monitored. In total 27 ewes were observed in estrus being 9/11 LP (82%) and 18/20 HP (90%). On the day of estrus (day 0), the mean number of large follicles was higher (p < .05) in HP (1.78 ± 0.19) than in LP (1.0 ± 0.28) ewes. Prior to estrus, more (p < .05) medium follicles were visible for HP compared to LP ewes. Plasma estradiol concentrations were higher in HP compared to LP ewes (18.91 ± 0.41 vs. 14.51 ± 0.65 pg/ml; p < .05) and similarly was ovulation number (2.3 ± 0.15 vs. 1.28 ± 0. 14; p < .05). Higher ovulation rates and litter size in Bonga sheep are evidenced by the previous presence of more large follicles and the existence of co‐dominance effects as most likely medium follicles are selected to ovulate.