The somatic chromosomes and karyotype traits of three Romanian genotypes (coded as CB-1, S-16, L-4) of Hippophae rhamnoides L. have been studied. Diploid chromosome number is 2n=24. The karyomorphological data show that the complements have small chromosomes (1.33 ± 0.014 -2.80±0.01 µm, for CB-1 genotype; 1.13 ± 0.029 -2.90 ± 0.029 µm, for S-16; 1.15 ± 0.099 -2.88 ± 0.024 µm, for L-4 genotype) and the length of haploid complements is 23.97 µm, for CB-1, 22.20 µm, for S-16, 21.73 µm, for L-4. In CB-1 and S-16 male genotypes, the putative Y-chromosome has larger sizes than X-chromosome and it is of metacentric type (CI = 45.77, r = 1.18, for CB-1; CI = 46.22, r = 1.15, for S-16). The L-4 female karyotype is constituted by twelve pairs of morphologically similar chromosomes. The karyotype formulae are 2n = 24 = 13m + 11sm (putative male: 22 + XY), for CB-1 genotype, 2n = 24 = 18m + 6sm (putative male: 22 + XY), for S-16 genotype, respectively 2n = 24 = 22m + 2sm (L-4 genotype, considered as female: 22 + XX). The small size of chromosomes (< 3µm), the presence of only two morphometric chromosome types and preponderance of metacentrics confer a relatively high degree of symmetry to the studied karyotypes. Our results show a low intraspecifi c karyotype variation.

In this experimental study the authors present their results regarding the cellular division rate and the percentage of chromosomal aberrations in the root meristematic cells of Helianthus annuus cultivated in the presence of different volume fractions of magnetic nanoparticle suspensions, ranging between 20 and 100 microl/l. The aqueous magnetic colloids were prepared from chemically co-precipitated ferrites coated in sodium oleate. Tissue samples from the root meristeme of 2-3 day old germinated seeds were taken to prepare microscope slides following Squash method combined with Fuelgen techniques. Microscope investigation (cytogenetic tests) has resulted in the evaluation of mitotic index and chromosomal aberration index that appeared diminished and respectively increased following the addition of magnetic nanoparticles in the culture medium of the young seedlings. Zinc ferrite toxic influence appeared to be higher than that of magnetite, according to both cytogenetic parameters.

Sea buckthorn is a dioecious Eurasian shrub or small tree with large morphological, biochemical and physiological variability, evidenced by the great number of studies. Cytogenetically, uncertainties exist on species basic number, ploidy level, and sex chromosomes. In this study, detailed cytogenetic measurements were carried out on six Romanian ecotypes belonging to Hippophaë rhamnoides L. ssp. carpatica Rousi, in order to establish the features and the symmetry degree of karyotypes, to evidence the sex chromosomes, and to construct the idiogram. The ecotypes have 2n = 24 metacentric and submetacentric chromosomes. An intraspecific variation exists concerning the proportion of these two morphotypes. The karyotypes have similar symmetry patterns (R = 2.57-2.89; TF%= 38.54-42.70; AsI%= 57.99-61.41; A1=0.27-0.35; A2 = 0.26-0.36) and belong to 1B and 2B classes, being relatively high symmetric. Based on obtained results, we presume that the male sex chromosomes are heteromorphic, while in female plants are homomorphic. The Y chromosome is larger than X chromosome.

No abstract

The response of maize to radiation exposure was investigated by two cytogenetic methods considering the importance of the genotoxic effect for environmental and agricultural purposes. Uniform genophond seeds, freshly germinated, were exposed to relatively low radiation doses using a radiotherapy X-ray applicator from a hospital irradiation device and to a 50 Hz electromagnetic field with about 10 mT magnetic induction (generated within laboratory assembled electromagnetic coils). Radicular meristeme tissue aliquots were prevailed for cytogenetic investigation based on microscopic observations and cell counting. Microscope slides were prepared following a specific procedure (squash technique and Feulgen method based on modified Carr reactive coloration). Mitotic index as well as chromosomal aberration percentage were calculated for more than 30,000 cells taken into account. From a qualitative viewpoint, chromosomal aberrations such as interchromatidian bridges, lagging and expelled chromosomes and multipolar divisions were evidenced -no distinct situation for either ionizing radiation or electromagnetic field being identified. quantitative difference consisted in the increased mitotic index for electromagnetic exposure increased times compared with the diminished mitotic index in the case of low X-ray doses.