الفهرس 
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Abstract
Fusion PCR is one of the gene targeting procedures, which was used for studying GMT biological role in our study. Aspergillus nidulans nkuA deficient strains were used to create three GDP-mannose transporter null mutants gmtAΔ, gmtBΔ and gmtAΔgmtBΔ double mutant.
The effect of gmtA gene deletion on colony morphology was clear, gmtAΔ strains lost the green pigmentation of the spores of the wildtype. It had fewer spore count per colony in comparison to wildtype, also there was a decrease in the colony diameter after 3 days incubation. The effect of gmtB gene deletion on colony morphology was noticed in further reduction in both colony size and sporulation. The effect of gmtAΔgmtBΔ double gene deletion was evident in the significantly smaller colonies produced with fewer spores. Sporulation was markedly reduced by deletion of GDP-mannose transporter A, B and double deletion in comparison to wildtype. Hyphal width and cell wall thickness was increased markedly in the null mutants than in wildtype. Growth rate was determined as mm/hour, gmtAΔ showed the greatest growth rates at the first 24 hours (153% of the wild type) then growth rate was markedly reduced from the second to the forth day, while gmtAΔgmtBΔ had the lowest growth rate. Spores viability was not affected by either gmt genes deletion.
Scanning electron microscopy (SEM) was used to study the characters of 3 days old colonies growing on RPMI agar wildtype and gmt single and double mutants. Wildtype is characterized by abundant conidiophores and sporulation, while gmtAΔ had less conidiophores, less sporulation, presence of bulb formation or ballooning of the hyphal tip and impaired polarity. Spores of gmtAΔ had rough surface appearance as wild type but with the presence of more ornaments on the outer surface. The gmtBΔ strain had abundant branched hyphae than gmtAΔ strain, fewer conidiophores and less sporulation than both wildtype and gmtAΔ and excessive adhesive ECM on the outer wall of hyphae and loss of polarity. Spores of gmtBΔ lost the presence of ornaments and the rough surface appearance of the wildtype, which was exchanged with outermost arranged rodlet layer. The gmtAΔgmtBΔ strain had more branching hyphae, less sporulation, aberrant or sterile conidiophores and adhesive extraneous material on the outer wall of hyphae and loss of polarity. Spores of gmtAΔgmtBΔ are of various sizes and differ from the gmtAΔ and wildtype in their rough outermost surface appearance and resemble gmtBΔ in its arranged rodlet layer.