الفهرس 
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Abstract
Sugarcane crop is considered one of the most important sugar crops, since its production represents approximately 70 % of the total sugar yield : However, biosafety and risk assessment of genetically modified foods is nowadays one of the most challenging problems worlds wide. However, employing a variety of short–term genotoxic bioassays might be a fruit full approach for detection of DNA lesions. An attempt was done to obtain transgenic sugarcane plants. To achieve such a purpose, genetically modified Agrobacterium carrying Cry1A (b) gene was Kindly obtained from Department of Biochemistry and molecular Biology – University of Nevada, U.S.A.
In this work two main experiments were carried out:-
1- First experiment
In the first experiment an attempt was done to obtain transgenic sugarcane plants. Calli were obtained after culturing the explants, that explants were incubated with Agrobacterium for 25 min. and transferred to CIM containing neomycin sulfate (50 mg/ml ) as a selective agent for a month. Calli were transferred to SFM in order to obtain shoots for month. Then they were transferred on RFM for one month.
Healthy plantlets were then transferred to a green house for acclimatization for a period of three months. Plants were then cultivated in field Agriculture Research Station (A.R.S.) at Subbhia, ARC. Syrup was obtained from the stems of plants and the second experiment was conducted after analysis of amino acid. Amino acids contents of sugarcane syrup of transgenic as well as non- transgenic plants were stimulated. The results revealed that two amino acids in transgenic plants were shown to be higher then that of non- transgenic. They are Glutamic acid and proline.
2- Second experiment
A variety of short term genotoxic bioassays had been conducted employing mice. Genome is a sensitive indicator for DNA lesions. The following genotoxic bioassays were used:
1- Estimation of cell proliferation activity.
2- Analysis of chromosomal abnormalities in mice bone-marrow cells.
3- Analysis of micronucleated polychromatic erythrocytes in mice.
4- Analysis of mice primary spermatocytes.
5- Analysis of mice sperm- head abnormalities.
The obtained data might be summarized as follows:
a- Analysis of amino acids revealed that there were significant differences between the tested sources (transgenic and non transgenic plants). However, Aspartic acid, Seriene, Glutamic acid, Proline, Glycine, Alanine, Cystine, Valine, Methionine and Isoleucine were proven to be highly significant different. On the other hand, Threonine showed significant different. The amino acid leucine was found to be insignificant.
b- With respect to the short-term genotoxic bioassays employed in this work the obtained results might be summarized as follows:
1- There were statistically significant differences in mitotic index and cell proliferation in bone marrow of animals treated (Fed) with sugarcane transgenic syrup. It ranged from 1.1 to 6.5 % for the doses 5 and 0.5 g/kg b.wt., respectively.
2- Analysis of chromosomal abnormalities in mice bone-marrow cells revealed that there were significant differences. There were different types of aberrations such as: Stickiness, Fragments, RCF or Robertsonian Centric Fusion, Deletion and Ring chromosomes. Statistical analysis showed that there was a dose response relationship since significant increases of aberrations were significantly increased with the increasing of the tested dose.
3- Regarding the analysis of micronucleated polychromatic erthrocytes, the data obtained showed that no significant increases in micronucleated polychromatic erythrocytes were achieved.
4- The analysis of diakinesis stage revealed that transgenic sugarcane syrup was proven to be a positive inducer of chromosomal aberrations, giving important evidence that its effect reached germinal cells of mice and affected the genome, giving evidence that the present transgenic sugarcane syrup was found to clastogenic at the level of germinal cells.
5- Examination of sperm head abnormalities showed that there were unknown substances in transgenic sugarcane syrup and these substances were proven to interact with sperm head differentiation.
In conclusion, the present investigation was proven to be successful in producing transgenic sugarcane plants. However, assessment of genetic lesions by transgenic plants employing genetic toxicology bioassays is considered to be a very sensitive, accurate and cheap method in evaluative purposes. This study clearly revealed that there were genetic lesions in mice genome after treatment with transgenic sugarcane syrup. However, such DNA lesions might not be occurred when humans consume sugar, since extraction and purification processes of sugars needs high temperature (≈ 300 o C). On the other hand, consumption of the syrup may cause such damage.
Genotoxic bioassays or a variety of short-term genotoxic bioassays employed in this work have been extensively used for assessment of genetic lesions induced by environmental contaminants. These assays, however, were employed for the first time in this work to assess the possible genetic lesions induced by genetic modified crops (GMC).