Ameer E. Elfarash

Bacterial soft rot disease is one of the most important and widespread bacterial diseases that cause destructive losses to the crop in a matter of days. The disease causes severe many vegetable crops including potato. In this study, four isolates of Pectobacterium carotovorum the main causal of the soft rot disease were isolated from naturally rotted tubers. Then, the isolates were subjected to a new set of primer pairs designed to amplify the pel gene which distinguish the P. carotovorum strains. The results confirmed that four isolates belong to P. carotovorum by having the pel gene. Then, a pathogenicity test was performed on potato tubers which showed variability between the isolates in pathogenicity and diseases severity. Finally, a quantitative reverse transcriptase PCR (qRT-PCR) techniquewas used to investigate the effect of the presence of the potatoes tissues on stimulating the expression of the pathogenicity genes. The gene expression of five pathogenicity genes was studied included: polygalacturonase (Peh), pectate lyase (Pel), xylanase (Xy), protease (Prt), and cellulase (Cel). The results confirmed that the presence of potatoes tissues stimulates the expression of pathogenicity genes in both strong and weak P. carotovorum isolates.

The infectious prion protein (PrPSc or prion) is derived from its cellular form (PrPC) through a conformational transition in animal and human prion diseases. Studies have shown that the interspecies conversion of PrPC to PrPSc is largely swayed by species barriers, which is mainly deciphered by the sequence and conformation of the proteins among species. However, the bank vole PrPC (BVPrP) is highly susceptible to PrPSc from different species. Transgenic mice expressing BVPrP with the polymorphic isoleucine (109I) but methionine (109M) at residue 109 spontaneously develop prion disease. To explore the mechanism underlying the unique susceptibility and convertibility, we generated soluble BVPrP by co-expression of BVPrP with Quiescin sulfhydryl oxidase (QSOX) in Escherichia coli. Interestingly, rBVPrP-109M and rBVPrP-109I exhibited distinct seeded aggregation pathways and aggregate morphologies upon seeding of mouse recombinant PrP fibrils, as monitored by thioflavin T fluorescence and electron microscopy. Moreover, they displayed different aggregation behaviors induced by seeding of hamster and mouse prion strains under real-time quaking-induced conversion. Our results suggest that QSOX facilitates the formation of soluble prion protein and provide further evidence that the polymorphism at residue 109 of QSOX-induced BVPrP may be a determinant in mediating its distinct convertibility and susceptibility.

Thirty six samples of raw milk were collected from three different farms located in Merida, Yucatan, Mexico and seventy two samples of soft cheese were manufactured from thirty six samples of raw milk and thirty six samples of pasteurized milk from the previous collected raw milk during May 2013 to April 2014. The first and second farm located at Faculty of Veterinary Medicine and Animal Science, Autonomous University of Yucatan (FMVZ/UADY) used two different production regimes; intensive silvopastoral system (ISS) and traditional system (TS). The third farm in Kampepen under (ISS). The collected raw milk samples were divided into three portions, one portion of raw milk and two portions for soft cheese manufacture from (raw and pasteurized milk) for PCR screening. PCR screening was performed for one hundred and eight samples to detect four types of the most dangerous foodborne pathogens (Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, Staphylococcus aureus and Listeria monocytogenes). PCR results showed that almost samples were negative for all tested pathogens except six samples (5.56%); 3 samples of raw milk and other 3 samples of soft cheese manufactured from this raw milk under traditional system which were positive for Staphylococcus aureus.