Chromosomal studies on the taxonomy of some species of the genus aloe

The aim of this study was to analyse the karyotype by using root tips of three species of the Aloe genus namely Aloe sabaea, A. shadensis, and A. castellorum and to differentiate between them from the view point of chromosomes taxonomy. In addition, the study aimed at determining the DNA concentration for the three species. Chromosome number of these three species was 2n = 14. It consisted of four pairs of large subtelocentric chromosomes and three pairs of relatively small submetacentric chromosomes. The presence of a secondary constriction was clearly visible positioned in the distal end of the long arm of the second chromosome pair in A. shadensis, and on the long arm of the first chromosome pair in A. castellorum, but not observed in A. sabaea. Chromosomes length, arm ratio, the relative length, and the total chromatine length were calculated. The length of the chromosome complement already indicated that the species of Aloes possess a large genome. The DNA concentrations were determined through spectrophotometer measurements, they were 3.46, 5.58, and 4.41 micro g/ml in A. sabaea, A. shadensis, and A. castellorum. respectively. These significant variations in the DNA concentrations along with the observed differences in the Karyotypes would strongly support the species status of each one of them and support their current recognized taxonomic status

Mutagenicity studies of cadmium chloride in mice

Cadmium chloride [CdCl2] was tested for its mutagenicity in Swiss albino mice by the dominant lethal mutation test and the micronuclei test singly or in combination with either nitrosoguanidine [NTG] or ascorbic acid. The results obtained showed that cadmium chloride is a weak mutagen when compared with NTG as a positive control. However, cadmium chloride [CdCl2] and NTG in combination showed a significant increase in the dominant lethal mutations when compared with the effect of either CdCl2 or NTG individually. A statistically significant increase of the frequency of micronucleated erythrocytes was also noticed when CdCl2 was combined with either NTG or ascorbic acid compared with CdCl2 individually