Response of rats to dose rates of ionizing radiation evaluated by dielectric properties of bone marrow.

The response of adult Wistar albino female rats toward two dose rates of gamma radiation delivered as acute dose of 7 Gy is investigated using classical methodologies as chemical, hematological and histological parameters in comparison with newly introduced dielectric parameters. Two groups of rats were exposed to γ ray with dose rates 533.35 mGy/min and 325.89 mGy/min. Then the irradiated groups were followed up for two weeks after irradiation. In case of higher dose rate, high percentage of animals was lost and there were substantial alterations in the dielectric parameters in addition to massive damage in liver and bone marrow cells. On the other hand, a reduction of death rate of rats, different behavior in the dielectric parameters of bone marrow and lesser injury of liver tissue were well noticeable in case of lower dose rate. Moreover, the sensitivity of dielectric parameters toward the two different dose rates was well pronounced during the 1st and 2nd weeks after irradiation more than other parameters.

Cloning and characterization of some rep20 DNA fragments from the genome of the human malaria pathogen Plasmodium falciparum.

Chromosomes of the human malaria parasite Plasmodiumfalciparum contain long subtelomeric repeat sequences and little is known about them. In this study, we have cloned 10 fragments of the non-coding rep20 sequence from the genome of Plasmodium falciparum 3D7 and HB3 strains. Analysis of these fragments showed that they represent 4 different 3D7 fragments and 2 different HB3 ones. Blasting the sequence of these fragments to the PlasmoDB revealed a varying degree of identity to the released rep20 sequence. One of these fragments was found to contain 27 degenerate repeats and show the highest consistency with the rep20 consensus sequence. This fragment was. inserted into a plasmid construct containing the green fluorescence gene and a stably transfected plasmodium cell line was established. Our data show that this rep20 fragment enhances the establishment of drug-resistant parasite populations after transfection; however it restricts the expression of the green fluorescence transgene. These results attract attention to an in-depth study of the role that some rep20 sequences may play between the telomeres and the differentially expressed virulence-related genes.