Background: African trypanosomes are capable of both pyrimidine biosynthesis and salvage of preformed pyrimidines from the host, but it is unknown whether either process is essential to the parasite. Methodology/Principal Findings: Pyrimidine requirements for growth were investigated using strictly pyrimidine-free media, with or without single added pyrimidine sources. Growth rates of wild-type bloodstream form Trypanosoma brucei brucei were unchanged in pyrimidine-free medium. The essentiality of the de novo pyrimidine biosynthesis pathway was studied by knocking out the PYR6-5 locus that produces a fusion product of orotate phosphoribosyltransferase (OPRT) and Orotidine Monophosphate Decarboxylase (OMPDCase). The pyrimidine auxotroph was dependent on a suitable extracellular pyrimidine source. Pyrimidine starvation was rapidly lethal and non-reversible, causing incomplete DNA content in new cells. The phenotype could be rescued by addition of uracil; supplementation with uridine, 29deoxyuridine, and cytidine allowed a diminished growth rate and density. PYR6-52/ 2 trypanosomes were more sensitive to pyrimidine antimetabolites and displayed increased uracil transport rates and uridine phosphorylase activity. Pyrimidine auxotrophs were able to infect mice although the infection developed much more slowly than infection with the parental, prototrophic trypanosome line. Conclusions/Significance: Pyrimidine salvage was not an essential function for bloodstream T. b. brucei. However, trypanosomes lacking de novo pyrimidine biosynthesis are completely dependent on an extracellular pyrimidine source, strongly preferring uracil, and display reduced infectivity. As T. brucei are able to salvage sufficient pyrimidines from the host environment, the py

This paper studies the impact of the implementation of

extensive reading programme on the reading comprehension

and the development of other English language skills such as

speaking, spelling and writing of Libyan university students

studying EFL. 50 students studying English in the English

Department, Faculty of Arts, Al-jabal Algharbi University had

read a written materials of their choice, summarised their

main events and completed a self-completion questionnaire.

The findings of the questionnaire data analysis suggested that

the respondents had a positive attitude towards their selfreading,

learned some new words. These findings may encourage the

teachers of reading comprehension courses to implement

extensive reading programme to complement the intensive

reading programme which is practiced in classroom. Also,

reading materials are required to be available in the

educational institutions' libraries.found the information of the written texts useful and

 Cutaneous leishmaniasis (CL) is an endemic parasitic infection in the Mediterranean region, including Libya and 

its Al-jabal Al-gharbi province. We aimed at studying the occupational relevance as well as other epidemiological aspects 

of CL. We investigated 140 CL cases who attended at Gharyan outpatient polyclinic during a period of 6 months in 2009. 

CL infection was clinically diagnosed and confirmed by demonstration of Leishmania parasites on smears from lesions. 

Our findings showed that males were more affected than females (P=0.04), and people above 10-years were more af￾fected than younger ones (P=0.0001). A significant percent of CL cases belonged to Al-Kawasem subprovince 

(P=0.0001). Farm-related activities were the most frequent occupations among CL cases (P=0.04). In addition to farm 

workers, housewives and students are at risk groups since they are engaged at farm activities. Moreover, those who have 

occupations that require staying outdoors for a part of night, e.g., policemen, are also at risk. Compared to children, adult 

CL patients had multiple lesions (P=0.001) that were more prevalent in their upper and lower extremities than the face 

(P=0.0001). We conclude that CL is a major health problem in Al-jabal Al-gharbi province of Libya. The presence of ro￾dents and sandflies makes it a suitable environment for Leishmania to spread in an endemic epidemiological pattern. Be￾ing engaged in farming activities or outdoor occupations increases the risk of infection. Various clinical patterns of CL 

suggest the presence of more than 1 species of Leishmania at Al-jabal Al-gharbi province. We propose that the 2 species 

responsible for CL in this area are L. major and L. tropica. Further investigations to identify the leishmanial species re￾sponsible for CL at Al-jabal Al-gharbi together with adoption of preventive and control programs are needed.

African trypanosomes are capable of both pyrimidine biosynthesis and salvage of preformed pyrimidines from the host. However, uptake of pyrimidines in bloodstream form trypanosomes has not been investigated, making it difficult to judge the relative importance of salvage and synthesis or to design a pyrimidine-based chemotherapy. Detailed characterization of pyrimidine transport activities in bloodstream form Trypanosoma brucei brucei found that these cells express a high-affinity uracil transporter (designated TbU3) that is clearly distinct from the procyclic pyrimidine transporters. This transporter had low affinity for uridine and 2′deoxyuridine and was the sole pyrimidine transporter expressed in these cells. In addition, thymidine was taken up inefficiently through a P1-type nucleoside transporter. Of importance, the anticancer drug 5-fluorouracil was an excellent substrate for TbU3, and several 5-fluoropyrimidine analogs were investigated for uptake and trypanocidal activity; 5F-orotic acid, 5F-2′deoxyuridine displayed activity in the low micromolar range. The metabolism and mode of action of these analogs was determined using metabolomic assessments of T. brucei clonal lines adapted to high levels of these pyrimidine analogs, and of the sensitive parental strains. The analysis showed that 5-fluorouracil is incorporated into a large number of metabolites but likely exerts toxicity through incorporation into RNA. 5F-2′dUrd and 5F-2′dCtd are not incorporated into nucleic acids but act as prodrugs by inhibiting thymidylate synthase as 5F-dUMP. We present the most complete model of pyrimidine salvage in T. brucei to date, supported by genome-wide profiling of the predicted pyrimidine biosynthesis and conversion enzymes.

This paper considers a common problem that all industries contest with in practice ie the breaking down of machines that influence production and cost directly. In a majority of industrial applications, acquiring optimum utilisation of all available resources for existing and future predicted demand is a major function throughout all the levels of management. This paper uses a number of analytical tools and software that support one another ie Witness Simulation, Bayesian Network Modelling and Hugin Software. The use of expert experience and knowledge has been incorporated throughout the study as it is vital to model building and greater understanding of machine breakdown. This study uses discrete event simulation and Bayesian network modelling collectively to understand machine breakdowns to increase efficiency within a cement manufacturing plant ie the Crusher Machine. The Bayesian network modelling implemented by the Hugin Software is used to generate probabilities which are transferred into a discrete event simulation model using Witness Software based on the historical data, expert knowledge and opinions. The model simulates the three parameters of the machine life based on consumption of each parameter. This is translated into a probability failure rate that changes as the model is running. The model demonstrates decisions based on the probability of failure from the Bayesian model and based on life consumption of the different variables in the simulation model.

The aim was to build an educational website to teach preschoolers aged 2-5 years old some skills; related to reading, writing and pronouncing alphabet, numbers, animal names, shapes and other common words. Also, assist parents and teachers by providing digital game-based learning environment to “edutainment” the children. The study illustrated the usability and usefulness of this educational game-based website and provided future insights for researchers and developers to take into account in future work.