الفهرس 
Importance of Withania somnifera extractsOnly 14 pages are availabe for public view
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Abstract
Cylindrotheca closterium alga belongs to family Bacillariaceae, order Bacillariales, class Bacillariophyceae and phylum Bacillariophyta. In this study Cylindrotheca closterium alga was isolated from Alexandria coastal region (Eastern Harbor) using two methods: dilution method and streak and spray plating technique. Isolated algal cells were cultured on Guillard F2 liquid medium. Morphological identification was carried out by light microscope and scanning electric microscope. Algal cells were found to be wrapped by the raphe canal of valves, which is a typical characteristic of Cylindrotheca closterium shape. The cells contained two plastids lying next to each other along the longitudinal axis of the cell and apprised to one side of the cell with lobes extending onto the other sides, and the nucleus centrally in between. Genetic identification of Cylindrotheca closterium was carried out using ribulosebisphosphate carboxylase gene (rbcL) located in the plastids as molecular marker. Specific PCR primers were used to amplify rbcL gene fragment from total genomic DNA extracted from Cylindrotheca closterium cells. Amplified rbcL (1177 bp) gene fragment was purified and sequenced. Nucleotide sequence was compared with Cylindrotheca sequences available in the GenBank. The Genetic distances and multi alignments were computed by Pairwise Distance method using Clusteral W software analysis. The nucleotide sequence of amplified rbcL gene showed varied identity percentages (81%, 80% and 78%) with other related sequences in the GenBank. This could be correlated to the observed morphological variations. Previous studies indicated high sequence divergences of rbcL gene among Cylindrotheca isolates, and numerous nucleotide variations of rbcL gene caused relatively few variation of deduced amino acid sequence. These results may indicate that Cylindrotheca closterium is a species complex as was previously evidenced by the variations of rbcL gene. Withania somnifera (L.) Dunal, a member of the family Solanaceae, is an important medicinal plant commonly called Indian ginseng. It is commonly used for medicine to increase longevity and vitality. The whole plant extract and several separate constituents have poly-pharmaceutical uses. Plant material of Withania somnifera was collected from the Garden of Tanta University then the plant identified in Tanta university herbarium. Leaves of W. somnifera were collected, washed and Dried. Powder were dissolved in different solvents (Methanol, Ethyl athetate, Petroleum ether, Hexane) then dried and kept in freeze. GC-MS analysis of different solvents of the plant was carried out at the Central Laboratory of Tanta University -Gas chromatograph Unit. The components of Withania Somnifera different extracts were identified by comparing their retention time and mass spectrum with those of the GC-MS system and literature data. The results were presence of many fatty acids and sterols. Decanoic acid derivatives were the predominant fatty acids Random amplified polymorphic DNA (RAPD) technique was performed to evaluate the genotoxic effect of five solvents prepared from Withania somnifera on Cylindrotheca closterium. Highest genetic polymorphism and genetic variation (23.8%) was resulted with hexane solvent for Withania somnifera extract comparing with other solvents. Genetic variation of Cylindrotheca closterium after exposure to four solvent for Withania somnifera extract were arranged descendingly for Ethyl acetate, Methanol. Petroleum ether solvents with 19.6%, 19.2% and 18.2% of genetic polymorphism respectively.