An initial survey of the cattle grub Dermatobia hominis (L. Jr.) in Nicaragua

After the civil war and the Hurricane-Mitch disaster, cattlemen in Nicaragua were forced to transport their cattle from lowland areas to higher, dryer areas of the country. These areas are natural ecological niches for the cattle grub Dermatobia hominis (L. Jr.) (Diptera: Cuterebridae). To determine the importance of this infestation, the Agricultural and Livestock-Forestry Ministry selected a central area of Nicaragua to run a pioneer survey program to acquire information about hosts involved, number of cases, treatments applied and general knowledge of 42 farmers about the life cycle of the parasite. The subjects were either farm owners or farm managers. Ninety-five percentage of the farms indicated cases of D. hominis infestation in their animals, with cattle being the most affected host (100% of the affected farms). There was poor understanding of the D. hominis life cycle, vectors and control methods. A misuse of insecticides for the treatment of larval infestation by D. hominis was indicated.     

Organic Seed-treatment as a Substitute for Chemical Seed-treatment to Control Common Bunt of Wheat

Common bunt of wheat, caused by Tilletia laevis and T. tritici, is a major seed and soil-borne disease in West Asia and North Africa. The use of resistant cultivars and chemical seed-treatments are the current control measures used to combat this disease. The aim of this study was to investigate alternative control measures to chemical seed-treatments that are environmentally friendly to support cultivar resistance. Several organic nutrients [skimmed milk powder, hucket (local skimmed milk) and wheat flour] at a concentration of 160g per kg of seeds were used as seed-treatments on two susceptible bread and durum wheat cultivars (Bau and Sebou, respectively) to examine their effectiveness in controlling the disease. Field trials over four years showed that skimmed milk powder, hucket, and wheat flour reduced common bunt infection levels by 96%, 93% and 62%, respectively. In most cases, the effectiveness of the skimmed milk powder and hucket was equal to the chemical seed-treatment; thus, these organic nutrients offer an effective and environmentally safe alternative to chemical treatments. However, a study of their economic value as well as of their effect on seed germination, and field emergence is needed.     

ELLA: A Rapid Technique to Estimate Chromium Stress-Induced Modification of E. coli EI19

An enzyme-linked lectin assay (ELLA) was used to differentiatebetween chromium-stressed and unstressed cells of Escherichia coli EI19. The assay is a modification of the enzyme-linked immunosorbent assay (ELISA) that uses Concanavalin A (Con A) conjugated with peroxidase to detect the carbohydrate moiety of the cell envelope glycoconjugates. The ELLA test shows that Con A binds to stressed bacteria much moreefficiently than it does to unstressed bacteria. Effects of heat,phenol and papain treatments on Con A-binding to chromium-stressed bacteria were also studied. Con A-binding to bacteria was sensitive to heat and phenol treatment, but not to treatment with papain. A potential analytical method for estimating the concentration of certain environmental pollutants is outlined.     

Shocks in ion sputtering sharpen steep surface features

We report a regime of ion beam sputtering that occurs for sufficiently steep slopes. High slopes propagate over large distances without dissipating the steepest features. Both the propagation velocity and the dynamically selected slope are universal, independent of the details of the initial shape of the surface. The resulting behavior can be understood as the propagation of a shock front that self-selects a stable slope, as has been previously observed in thin-film fluid flows. Experiments confirm predictions of the theory. An important implication of the propagative behavior at high surface slopes is that a pattern can be fabricated at a large length scale and, through uniform ion irradiation, reduced to a smaller length scale while preserving, or even sharpening, the sharpest features.     

Evaluation of the hepatic NK cell response during the early phase of Fasciola hepatica infection in rats

The in situ distribution of NK cells in rat liver during the first 28 days of an experimental infection with F hepatica was investigated. NK cells were distributed homogeneously throughout the hepatic parenchyma in uninfected animals. The total number of hepatic mononuclear cells increased significantly following infection, but the proportion of NK cells did not change. After infection, these cells were found around the portal space, around the centrolobular vein, in the periportal fibrosis and in the band of collagen. However, no NK cells could be detected in or around the granuloma during infection. The frequency of both I L-2- and IFNgamma-producing NK cells was higher on day 7 postinfection (pi) but only the percentage of IFNgamma -CD161+ subsets remained elevated thereafter, whereas the percentage of both IL-2+CD161+ and IL-4+CD161+ subsets returned to the baseline. The number of CD161+IL10+ cells did not change significantly. These results suggest that NK cells could be another source for the early production of IFNgamma but provide no evidence that these cells are involved in early events associated with granuloma formation.     

The Contribution of Small-Scale Forestry-Based Enterprises to the Rural Economy in the Developing World: The Case of the Informal Carpentry Sector, Sudan

Small-scale forestry-based enterprises connected with wood processing are becoming of growing importance in the rural economy of developing countries. Little attention has been paid to the characteristics of these enterprises and their role in supporting economic development. The objectives of this study are to: (1) determine the socioeconomic characteristics of the operators of these enterprises; (2) assess the contribution of the informal carpentry sector to operators’ income; and (3) identify the factors limiting the expansion of the sector. The study was carried out in the Singa district, Sinnar State in 2011. Snowball sampling was used to select 250 operators from five markets in the district. The quantitative and qualitative data were collected using Participatory Rural Appraisal methods. The results revealed that most operators involved in the informal carpentry sector are males aged <30 years and their businesses have been in existence for <10 years. Operators’ incomes ranged between USD 100 and 500 monthly on average. The results also indicated that the operators face many constraints (e.g. finance shortage, lack of raw materials, insecure market, lack of technology and lack of organization) to expanding the informal carpentry sector. The study concluded that the informal carpentry sector has potential to contribute to rural economic development through increasing income and reducing rural poverty.     

Trans-endocytosis of CD80 and CD86: a molecular basis for the cell-extrinsic function of CTLA-4

Cytotoxic T lymphocyte antigen 4 (CTLA-4) is an essential negative regulator of T cell immune responses whose mechanism of action is the subject of debate. CTLA-4 shares two ligands (CD80 and CD86) with a stimulatory receptor, CD28. Here, we show that CTLA-4 can capture its ligands from opposing cells by a process of trans-endocytosis. After removal, these costimulatory ligands are degraded inside CTLA-4-expressing cells, resulting in impaired costimulation via CD28. Acquisition of CD86 from antigen-presenting cells is stimulated by T cell receptor engagement and observed in vitro and in vivo. These data reveal a mechanism of immune regulation in which CTLA-4 acts as an effector molecule to inhibit CD28 costimulation by the cell-extrinsic depletion of ligands, accounting for many of the known features of the CD28-CTLA-4 system.     

Measurements and estimates of potential evapotranspiration over Egypt

Mehanna (1976) estimated potential evapotranspiration (PE) for a number of stations in Egypt, using Penman's method with adjustment of the constants of the radiation term and the aerodynamic term, such that they would agree with measurements of radiation in Egypt and with estimations by Omar (1971a,b) of PE in a large field at Giza, to the southwest of Cairo. Measurements of PE were made at Bahtim, about 20 km to the north of Cairo, by evapotranspirometers.In the FAO Irrigation and Drainage Paper No. 24 on “Crop Water Requirements” (Doorenbos and Pruitt,1977) four methods were given for the calculation of PE; Blaney—Criddle, radiation, Penman (adjusted) and pan evaporation. It was considered that the Penman method was the most accurate of those given.The main features of comparison of the Mehanna and FAO's estimates of PE with measurements at Bahtim were that Mehanna, and three of the FAO's estimates (Blaney—Criddle, radiation and pan evaporation) are within ±10%0 of the measurements while the Penman estimate was 15% higher. An estimate of PE at Aswan was based on measurements of pan evaporation and estimates of evaporation from a large water surface at both Bahtim and Aswan, together with measurement of PE at Bahtim. The estimates by the methods of Mehanna, Blaney—Criddle, radiation and Penman lie in the limits 0—6% of the estimate based on measurements while the pan evaporation estimate is markedly lower. Comparison of the estimates at eight stations over Egypt shows that the Penman estimate is higher than the other estimates in Northern Egypt. The pan evaporation estimate is lower than the other estimates except at Bahtim where it is generally higher than Mehanna's and Blaney—Criddle's estimates. The low values of the pan evaporation estimates at Assuit and Aswan are remarkable.     

Spatial Distribution and Temporal Trends of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments from Lake Maryut, Alexandria, Egypt

Surface and core sediments from Lake Maryut, Egypt, one of the most polluted lakes in Egypt, were analyzed for polycyclic aromatic hydrocarbons (PAHs) using gas chromatography?Cmass spectrometry. This investigation represents the first extensive study of the distribution and sources of PAHs in sediments from Lake Maryut. The total PAHs concentrations (sum of 39 PAH compounds) in surface sediments varied greatly depending on the sampling location and ranged from 106 to 57,800 ng/g dry weight with a mean concentration of 6,950 ng/g. The most polluted areas are distributed in areas which are mainly influenced by municipal sewage and industrial effluent discharges, suggesting a direct influence of these sources on the pollutant distribution patterns. PAH concentrations were one to two orders of magnitude higher in comparison with those reported for riverine/estuaries systems around the world. Molecular indices, such as pyrogenic index (PI), methylphenanthrenes to phenanthrene ratio, HMW_PAH/LMW_PAH, A-PAHs/P-PAHs, FL/FL?+?PY, BaP/BaP?+?C, IP/IP?+?BgP, and Per/??(penta-aromatics) were calculated to evaluate different hydrocarbon origins and their relative importance. In general, sediments from the main basin and northwest basin of Lake Maryut showed the highest PAH concentrations with petrogenic signatures, indicating major sources of petrogenic PAHs in the city. On the other hand, lower levels of PAHs with a pyrogenic signature were widely recorded in areas that are distant from anthropogenic sources. At other locations, both petrogenic and pyrogenic inputs were significant. The concentrations of perylene relative to the penta-aromatic isomers are dominant especially in locations associated with terrestrial inputs and in the deepest core sediments, indicating diagenetic origin for the presence of perylene. Temporal trends of PAH concentrations in both cores sediments were influenced by input pathways and followed the economic development and the environmental policies of the Egyptian Government in the last 15 years. Finally, PAH levels in sediments were compared with Sediments Quality Guidelines (effects range median?Ceffects range low) for evaluation probable toxic effects on organism. Results suggest an ecotoxicological risk for benthic organisms mainly in the main basin area, where high concentrations of PAHs were found in sediments influenced by anthropogenic activities.     

Identification of the Egyptian species of Fasciola.

Reports on the species of Fasciola present in the Nile Delta, Egypt, appear controversial. Some authors reported the presence of both Fasciola gigantica and Fasciola hepatica, others reported F. gigantica only and mentioned that F. hepatica was found only in imported animals.This study was an attempt to identify the species of Fasciola flukes collected from locally bred animals. Morphologic, morphoanatomic, morphometric, and chemotaxonomic criteria of the fluke isolates were studied. Speciation based on morphologic and morphometric data was not decisive due to overlap in the values of most measurements. Morphoanatomic data proved the presence of both the species, and isoelectric focusing (IEF) of fluke soluble protein confirmed the presence of both F. gigantica and F. hepatica in Egypt.