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31.
《African Zoology》2013,48(2):150-155
A new freshwater eutardigrade, Dactylobiotus luci is described from a permanent marsh pool (Zaphania’s Pool) at 4225 m elevation in the Alpine zone of the Rwenzori Mountains, Uganda. The new species is most similar to D. dervizi Biserov, 1998 in the shape of the egg processes, absence of papillae and absence of eyes, but differs from it mainly by a different appearance of macroplacoids, by having tips of the egg processes usually sharp, not divided and more slender, and by several morphometric characters of eggs and adults. The new species was found in fairly acidic (pH < 6) Sphagnum-Carex fens bordering/extending into the pool. So far, it has only been recorded in one other high-elevation water body in Rwenzori in a similar habitat. 相似文献
32.
The displacement in east Africa of the US-1 clonal lineage of Phytophthora infestans by 2_A1 clonal lineage has been very rapid. This study tested the hypothesis that dominance of 2_A1 could be due, at least in part, to the increased aggressiveness of 2_A1 over US-1, using both a detached leaf assay (DLA) and a tuber slice assay. The assays were conducted in Uganda and Kenya but US-1 was only assayed in Uganda, because isolates could not be moved across borders and no potato US-1 isolates were available in Kenya. All isolates were collected from potato and compared on two potato cultivars (Kachpot-1 and Sarpo Mira), with the 2_A1 isolates also tested on tomato cultivar Rio Grande. Additionally, a tuber slice assay was done to test whether the capacity to infect tubers differed between 2_A1 and US-1. The aggressiveness of the isolates in the DLA varied significantly both within and among isolates classified according to clonal lineage and for type of host. The 2_A1 isolates were significantly more aggressive than US-1 isolates on both potato varieties evaluated. There were no significant effects of clonal lineage or potato cultivar used in the tuber assay. No significant correlation between foliar and tuber pathogenicity was observed. The 2_A1 isolates were significantly more aggressive on potato than on tomato. An effect of location was also observed in the DLA, on both hosts. It can be concluded from this study that greater pathogenicity of 2_A1 is at least partly attributable to its increased aggressiveness on potato. 相似文献
33.
Abiotic constraints override biotic constraints in East African highland banana systems 总被引:1,自引:0,他引:1
Lydia W.I. Wairegi Piet J.A. van Asten Moses M. Tenywa Mateete A. Bekunda 《Field Crops Research》2010
Banana is the primary food crop in Uganda, but yields are low due to a complex of abiotic and biotic constraints. However, quantitative information on the importance, interactions, and geographic distribution of yields and constraints is scanty. We monitored yields, biotic and abiotic constraints in 159 plots in Central, South and Southwest Uganda in 2006–2007. About half the plots were on-farm demonstrations that received fertilizer (average 71N, 8P, 32 K kg ha−1 year−1) through a development project, the rest were ordinary farmer fields (i.e. controls). Fresh banana yields in controls were significantly (P ≤ 0.05) higher in Southwest (20 t ha−1 year−1) compared with Central (12 t ha−1 year−1) and South (10 t ha−1 year−1). Demonstrations yielded 3–10 t ha−1 year−1 more than controls. Yield losses were calculated using the boundary line approach. In Central, yield losses, expressed as percentage of attainable yield, were mainly attributed to pests (nematodes 10% loss, weevils – 6%) and suboptimal crop management (mulch 25%). In South, poor soil quality (pH – 21%, SOM – 13%, N-total – 13%, and Clay – 11%) and suboptimal crop management (weeds – 20%) were the main constraints. In Southwest, suboptimal crop management (mulch 16%), poor soil quality (K/(Ca + Mg) − 11%) and low rainfall (5%) were the primary constraints. The study revealed that biotic stresses (i.e. pests, weeds) are particularly important in Central, whereas abiotic stresses (i.e. nutrient deficiencies, drought) dominate in South and Southwest. This study concludes that (i) technologies currently available allow farmers to double yields and (ii) past research efforts have mistakenly neglected abiotic constraints. 相似文献
34.
Multilocus sequence analysis revealed a high genotypic diversity of Aeromonas hydrophila infecting fish in Uganda 下载免费PDF全文
Samuel Posian Wamala Saurabh Dubey Abayneh Takele Hetron Mweemba Munang'andu Øystein Evensen Stephen Mutoloki Denis Karuhize Byarugaba Henning Sørum 《Journal of fish diseases》2018,41(10):1589-1600
A multilocus sequence analysis (MLSA) was carried out to delineate Aeromonas hydrophila from fish in Uganda. Five housekeeping genes including recA, gyrB, metG, gltA and pps; and the 16S rRNA gene were amplified and sequenced from a total of nine A. hydrophila isolates. The obtained sequences were edited, and consensus sequences generated for each gene locus. The housekeeping gene sequences were concatenated and phylogenetic analysis performed in MEGA version 7.0.2. Pairwise distances ranged from 0.000 to 0.118, highest within the gltA gene locus and lowest within the 16S rRNA gene. The average evolutionary diversity within isolates from the same source ranged between 0.002 and 0.037, and it was 0.033 between the different sources. Similar tree topologies were obtained from the different gene loci with recA, metG and gyrB being more consistent in discriminating isolates according to sources while the 16S rRNA gene had the lowest resolution. The concatenated tree had the highest discriminatory power. This study revealed that A. hydrophila strains infecting fish in Uganda are of diverse genotypes suggesting different sources of infection in a given outbreak. Efforts to minimize spread of the bacteria across sources should be emphasized to control infections of mixed genotypes. 相似文献
35.
Initial results of a pilot study to link remotely-sensed information on tropical forest loss to field-based information on species endangerment are reported here. LANDSAT multispectral scanner (MSS) imagery from 1973 and 1988 were used to estimate net forest removal (29% of forest area), regrowth (7% of forest area, including possible artifactual errors), and forest edges in Mabira Forest in southeastern Uganda during the 15-year period. Of the forest remaining, the percentage that was heavily disturbed increased from 18% to 42%. This change in forest density was observable with the MSS imagery. The total forest edge-to-area ratio (including edges interior to the forest boundary) increased by 29% over the period. Although four distinct types of closed tropical forest, based on structure or dominance, could be recognized on the ground, the types could not be distinguished by differences in spectral reflectance in the four MSS bands. Closed tropical forest could be readily distinguished from exotic conifer plantations, banana plantations, and other non-forest vegetation types. Field measurements in Mabira and other Ugandan rain forests, and in rain forest isolates on the Atherton Tableland of North Queensland, are being made to relate changes in forest fragmentation to resulting changes in species abundance, structural form of the forests, and morphological diversity of target populations. Possible applications of conservation biology theory and modeling to these data are briefly discussed. 相似文献
36.
L. J. Chapman 《Ecology of Freshwater Fish》1995,4(3):113-123
I examined the effects of extreme hypoxia and water level fluctuations on the distribution and movement of an air-breathing clariid catfish, Clarias liocephalus, in a papyrus swamp in western Uganda. Monthly records of the distribution and relative abundance of C. liocephalus across 28 swamp stations were used to examine seasonal trends in habitat use and movement. My results suggest that dissolved oxygen did not directly limit use of, or dispersal through, the papyrus swamp. C. liocephalus were found at most stations in the dry season, and there was no significant relationship between the number of stations used per month and mean monthly dissolved oxygen levels. In addition, there was no evidence for a significant effect of oxygen on the relative abundance of fish among stations during the driest months, or during peak flood conditions. However, relative abundance was positively correlated with water depth during the dry season. Fish from deeper habitats exhibited fewer injuries and lower rates of disappearance than fish from shallower waters. This may reflect the risk of aerial predation for surfacing fish. A comparison of habitat use and movements of C. liocephalus with the only other fish species found in the papyrus swamp, Barbus neumayeri, supports the idea that respiratory mode can affect the use of hypoxic papyrus swamps. B. neumayeri, is a small water-breathing cyprinid that uses aquatic surface respiration in response to severe hypoxia. The air-breathing capabilities of C. liocephalus permitted more widespread use of swamp waters than B. neumayeri. This study demonstrates that an understanding of the respiratory mode of fish species may be useful in predicting patterns of habitat use. 相似文献
37.
Banana (Musa spp.) — with Coffee robusta a traditional agroforestry system in Uganda is a purely mixed cropping system managed on a sustained production basis. The basic primary production is banana as a main food crop and Coffee robusta as the main cash crop. The variety of trees deliberately retained, managed and planted, animals and crops in the system are managed by the farmers to maximize production by supplying timber, fruits, fuelwood, fodder, food, medicinal and other miscellaneous uses. 相似文献
38.
Trials were established at three sites in Uganda to test the suitability of multipurpose trees (MPTs) as upperstorey in crop lands to provide poles, small timber and fuelwood. The three sites were Kachwekano District Farm Institute (1°16 S, 29°57 E, 2000 m.a.s.l.) in Kabale District, Kabanyolo University Farm (0°28 N, 32°27 E, 1250 m.a.s.l.) in Mpigi District and Bushenyi District Farm Institute (0°34 S, 30°13 E, 1610 m.a.s.l.) in Bushenyi District. The MPTs were planted in single rows at intra spacing of 2 m and each plot contained seven or nine trees. On both sides of the tree row, crops were raised. Data on crop yields were collected every season, while data on the growth of the trees were collected four times each year.In terms of tree growth,Grevillea robusta, Casuarina cunninghamiana andAlnus acuminata performed well with height growth of 1.8–2.4 m per year at Kachwekano, while at BushenyiGrevillea robusta, Casuarina junghuhniana, Cupressus lusitanica andCedrela serrulata averaged 1.6–2.0 m height per year. At Kabanyolo,Melia azedarach, Cassia siamea, Jacaranda mimosifolia, Grevillea robusta andMaesopsis eminii had height increments ranging from 1.8–2.7 m annually. Crop yields were affected by the presence of the MPTs, withMaesopsis eminii being the most competitive (averaging 60% reduction, over five seasons). The crop rows nearest to the tree line were the most affected. OnlyAlnus acuminata seems to have had a positive effect on crop yields. The installation of a root mesh to reduce tree root competition for nutrients and water in four species increased yields in plots with MPTs by 5% (Melia azedarach) to 152% (Maesopsis eminii), but the control plot still had significantly higher bean yields, suggesting that shading could also be important. In the case of maize, suppression seems to be due mainly to root competition because after its elimination yields obtained thereafter did not differ significantly from those of the control except for the Maesopsis plots. The negative influence of the MPTs could, therefore, be minimized by periodically pruning the tree crowns and roots. 相似文献
39.
Denis Rwabiita MUGIZI Sofia BOQVIST George William NASINYAMA Charles WAISWA Kokas IKWAP Kim ROCK Elisabeth LINDAHL Ulf MAGNUSSON Joseph ERUME 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(5):557-564
Brucellosis is a key zoonosis of major public health, animal welfare and
economic significance, and is endemic in livestock in Uganda. A cross-sectional
epidemiological study was carried out to estimate the sero-prevalence of brucellosis and
identify factors associated with sero-positivity in cattle in urban and peri-urban Gulu
and Soroti towns of Northern and Eastern Uganda, respectively. A total of 1007 sera and
data on biologically plausible risk factors from 166 herds and their spatial locations,
were collected from cattle reared in urban and peri-urban Gulu and Soroti towns of Uganda.
The sera were analyzed using indirect ELISA and sero-positive reactors confirmed by
competitive ELISA. Multivariable models were used to investigate for risk factors. The
overall animal-level and herd-level sero-prevalence was 7.5% (76/1007, 95% Confidence
Interval (CI): 6.15–9.4%) and 27.1% (45/166, 95% CI: 20.9–34.3%), respectively. Herd-level
sero-prevalence was significantly (P<0.001) higher in Soroti than
Gulu. In Gulu town, sero-positivity increased with an increase in herd size
(P=0.03) and age (P=0.002), and was higher in cattle
brought in from western Uganda (P<0.0001). In Soroti town,
introduction of new cattle into a herd was significantly (P=0.027)
associated with herd sero-positivity. There was a geographically differential risk
(clustering) of Brucella sero- positivity in herds in Soroti, while
sero-positivity was homogeneously distributed in Gulu. The data highlight brucellosis
occurrence and major risk factors for its transmission in cattle in urban and peri-urban
areas. 相似文献
40.
Kanyima M. Benon David O. Owiny Renée B?ge Maria G. Nassuna-Musoke Patrice Humblot Ulf Magnusson 《Acta veterinaria Scandinavica》2015,57(1)