A new approach to automated CBMN scoring following high doses

In recent years we have automated the CBMN assay using microvolumes of blood, processed in multiwell plates. We have seen that at doses above 6 Gy the detected yield of micronuclei actually declines with dose, likely because of mitotic delay, preventing cells from forming micronuclei and also, when using one color imaging, resulting in many false binucleated cells, consisting of two randomly-adjacent nuclei. By using the inverse mitotic index (the ratio of mononuclear to binuclear cells) to adjust the micronucleus yield we were able to obtain a monotonic increasing dose response curve at doses of up to at least 10 Gy from the same samples which generated dose-response curve with a peak near 6 Gy, when scored using the traditional micronucleus yield.

INFLUENCE OF BASIC VARIABLES ON MICRONUCLEI FREQUENCY AND CHROMOSOMAL ABERRATIONS IN GENERAL POPULATION OF FB&H

The aim of this study was to determine the values of micronuclei (MN) and structural chromosomal aberrations (CA) in peripheral blood lymphocytes from 200 healthy participants of both genders from general population of FB&H, as well as to explore the influence of gender and age on MN and CA frequencies. Standard protocols for MN test, cultivation and micronuclei analysis from peripheral blood binuclear lymphocytes have been applied. MN values ranged from 0 to 8 MN per 1000 binuclear cells. The results suggest that gender and age influence MN frequency, with pronounced effect on 2 MN frequencies. Females on average have higher values of all observed variables of MN test than men. We have also found significant effect of gender – females had increased number of CAs – chromatid type; and of the age in both genders. Frequency distribution of CTAs and CSAs between male and female groups showed predominance of CTAs over CSAs, independently of gender. The results of this study will be incorporated into reference data base for comparative research in future.

THE CYTOGENETIC AND PHYTOTOXIC ASSESSMENT OF THE ANTI-ICING MATERIAL ON ONION ASSAY (ALLIUM CEPA)

Allium cepa assay is one of the relevant methods for the cytogenetic analysis. Today modern anti-icing reagents seem to be unstudied in the field of cytogenetics studies. The aim of the experiment is to study the phytotoxic and cytogenetic activity of multi-component anti-icing material using an onion Allium cepa. We researched anti-icing concentrations in the range of from 1 to 100 g/l. The test object was onion «Stuttgarter risen» variety couched in anti-icing solutions during the 72 hours. According to the assessment of phytotoxic effects, there was estimated the number of roots, the length of the longest root and the length of all roots for the every onion plant. The parallel experiment included the phytotoxic research of the same anti-icing using wheat seeds according to method MR 2.1.7.2297-07. Every onion roots were cut away, fixed, painted and pressured for microscopic analysis for the purposes of the cytogenetic research. About 2000 cells were analyzed for each onion. We estimated the number of mitosis per 1000 cells (mitotic index, ‰) and the proportion of cells in each phase of mitosis by the total number of dividing cells (%). For the analysis of cytogenetic damage using micronucleus test that provided the estimation of micronucleus, protrusions, and binuclear cells. An ana-telophase analysis included the estimation of fragments bridges and lagging chromosomes. As a result of analysis of the roots growth, we founded acting concentrations (2; 4; 10 and 100 g/l) and in-acting ones (1.3 and 1). The experiment showed the similar susceptibility of the onion and wheat root response. The mitosis analysis showed that concentrations from 1 to 1.3 g/l increased a mitosis activity and concentration of 10 g/l provided the decline of mitosis. There were no cytogenetic defects in all studied concentrations.

Influence of aluminium chloride and sulphate on the root meristem of Vicia faba L.

The influence of various (0.1, 0.05, 0.01, 0.001 and 0.0001 M) aluminium chloride and aluminium sulphate concentrations on the mitotic activity of the root meristem of the bean <em>Vicia faba</em> L. was investigated after 24 h of incubation. A mito-depressive action of the tested compounds, irreversible at higher concentrations was observed. The tested substances induced chromosome aberrations (fragmentation and bridges in anaphase or telophase, micronuclei, binuclear cells) and inhibited elongation of roots. The results of topochemical analysis are described.

Cep57 Protein Is Required for Cytokinesis by Facilitating Central Spindle Microtubule Organization

Cytokinesis is the final stage of cell division in which the cytoplasm of a cell is divided into two daughter cells after the segregation of genetic material, and the central spindle and midbody are considered to be the essential structures required for the initiation and completion of cytokinesis. Here, we determined that the centrosome protein Cep57, which is localized to the central spindle and midbody, acts as a spindle organizer and is required for cytokinesis. Depletion of Cep57 disrupted microtubule assembly of the central spindle and further led to abnormal midbody localization of MKLP1, Plk1, and Aurora B, which resulted in cytokinesis failure and the formation of binuclear cells. Furthermore, we found that Cep57 directly recruited Tektin 1 to the midbody matrix to regulate microtubule organization. Thus, our data reveal that Cep57 is essential for cytokinesis via regulation of central spindle assembly and formation of the midbody.

Increased Cell Fusion in Cerebral Cortex May Contribute to Poststroke Regeneration

In this study, we used a model of a hemorrhagic stroke in a motor zone of the cortex in rats at the age of 3 months The report shows that cortical neurons can fuse with oligodendrocytes. In formed binuclear cells, the nucleus of an oligodendrocyte undergoes neuron specific reprogramming. It can be confirmed by changes in chromatin structure and in size of the second nucleus, by expression of specific neuronal markers and increasing total transcription rate. The nucleus of an oligodendrocyte likely transforms into a second neuronal nucleus. The number of binuclear neurons was validated with quantitative analysis. Fusion of neurons with oligodendrocytes might be a regenerative process in general and specifically following a stroke. The appearance of additional neuronal nuclei increases the functional outcome of the population of neurons. Participation of a certain number of binuclear cells in neuronal function might compensate for a functional deficit that arises from the death of a subset of neurons. After a stroke, the number of binuclear neurons increased in cortex around the lesion zone. In this case, the rate of recovery of stroke-damaged locomotor behavior also increased, which indicates the regenerative role of fusion.

Importance of using micronucleus test for hospital personnel exposed to cytostatics – Croatian study

Health personnel and administration is exposed to health risks. The paper ´s objective is to show that despite protection measures the exposed persons´ health is damaged. The government and management show intentions to enhance protection programs but they lack the means because of recession. Twenty-seven employees of Clinical Centre Rijeka working with cytostatics have been analyzed by micronucleus test. In 11 nurses at the Pediatric oncology, 10 nurses at Internal hematology and 6 at Oncology there have been no significant differences in MN, p=0.2106, p>0.05, mean 10 MN, range 2-29. In 7 nurses differences from referential values in the number of MN/1000 binuclear cells were found and they were not allowed to work for six months. Occupational medicine was done his part for the hospital. Meanwhile the problem of payment according to the Rules guarantied special standard remains since MN test although compulsory is not a part of routine examination