Differential micronuclei induction in human lymphocyte cultures by imidacloprid in the presence of potassium nitrate

Humans are exposed to pesticides as a consequence of their application in farming or their persistence in a variety of media, including food, water, air, soil, plants, animals, and smoke. The interaction of pesticides with environmental factors may result in the alteration of their physicochemical properties. Square wave cathodic stripping voltammetry (SW-CSV), a technique that simulates electrodynamically the cellular membrane, is used to investigate whether the presence of potassium nitrate (KNO(3)) in the culture medium interferes with the genotoxic behavior of imidacloprid. The cytokinesis block micronuclei (CBMN) method is used to evaluate imidacloprid's genotoxicity in the absence or presence of KNO(3) in the culture medium and, as a consequence, its adsorption by lymphocytes. Comparing micronuclei (MN) frequencies in control and imidacloprid-treated blood cell cultures, statistically significant differences were not detected. KNO(3) did not induce MN frequencies compared to control. Statistically significant differences in MN frequencies were observed when blood cell cultures were treated with imidacloprid in the presence of increasing concentrations of KNO(3). SW-CSV revealed that by increasing KNO(3) molarity, imidacloprid's concentration in the culture medium decreased in parallel. This finding indicates that imidacloprid is adsorbed by cellular membranes. The present study suggests a novel role of a harmless environmental factor, such as KNO(3), on the genotoxic behavior of a pesticide, such as imidacloprid. KNO(3) rendered imidacloprid permeable to lymphocytes, resulting in elevated MN frequencies.

Influence of low doses of gamma-irradiation on mouse skin collagen fibrils

The structure of mouse skin collagen fibrils after treatment with 0.5, 1 and 2.5 Gy gamma-irradiation was studied by electron microscopy. Animals were sacrificed 1, 4 and 8 weeks after irradiation. Although there were areas where the normal parallel packing of fibrils was retained in some regions packing was interrupted by abnormal fibrils and in some cases helical twisting was apparent. Irradiated collagen fibrils had a lower mean diameter compared with normal and a large variability in width. The diameter of 0.5 Gy irradiated fibrils returned to normal by 4 or 8 weeks after irradiation. Clusters of abnormal fibrils were found when viewed in cross-sections. Their number and size was reversibly dependent on the dose level. All fibrils retained normal banding periodicity. Computer analysis of irradiated and control patterns led to the conclusion that 0.5-2.5 Gy gamma-irradiation had no considerable effect in modifying the charge distribution along the mouse skin collagen fibril.

Morphological alterations caused by lithium in various cell lines

Lithium is being used for the treatment of mental diseases and for the attenuation of muelosuppression during chemotherapy. As during long term lithium treatment kidney damage has been reported, we studied morphological alterations in cells of kidney origin after exposure to lithium chloride. Above the level of 4 mmol, lithium has fatal effects in CV1 cells while HeLa cells that are not originating from kidneys, tolerate higher lithium concentrations. Cellular morphology alters during treatment duration. At early stages, cells become flatter on their substrate and upon longer than 4 days treatment begin to detach from their substrate and eventually cell death comes in a concentration dependent manner. The only morphological alteration observed in a lymphoblastoid cell line was a statistically significant cellular swelling.

Variable expression of SV40 large T antigen in CV1 cell clones

Using immunofluorescence and immunoadsorption, CV1 cell clones MA2, V4, USA3, TR7 and P3 infected with SV40 were found to express variably SV40 large T antigen. The monoclonal antibody used was Pab 419. The results indicate that P3 cells express T antigen to a considerable level as early as 10 h post-infection, while that of TR7 and USA3 cells is minute as judged from their positive nuclei. MA2 and V4 cells did not show any positive nuclei over this period of infection. At 20 h post-infection MA2, V4 and USA3 cells developed a considerable amount of fluorescence in their nuclei while TR7 and P3 cells produced high values. By immunoadsorption of cell extracts for the same periods of infection, similar results were obtained on the electrophoretograms. We also relate these findings with those from induction of heatshock proteins by SV40 infection.

The effect of elevated temperature on the aggregation of African green monkey kidney cells

The aggregation kinetics of African green monkey kidney cells CV1 and of the SV40 transformed derivative COS1 cells that had been incubated at 37 degrees C or 43.5 degrees C was studied using the shaking flask system. COS1 cells show a three fold decrease in aggregation rate compared to CV1 cells when both cell types were incubated and aggregated at 37 degrees C. When these cell types were incubated at 43.5 degrees C for 5 hours, then aggregated at 37 degrees C showed a faster aggregation kinetics than before. Their aggregation at 43.5 degrees C with prior incubation at 37 degrees C or 43.5 degrees C reached the aggregation kinetics of 43.5 degrees C incubated cells aggregated at 37 degrees C. The addition of serum in the aggregation medium did not influence extensively the aggregation rates of both cell types.

Heat shock induces variably the major heat shock proteins of CV1 clones

CV1 cells have been subcloned several times. Five of these clones were studied for the induction of the major heat shock proteins. These CV1 clones exhibit morphological differences as well as differences in SDS-PAGE protein profiles. These clones responded to heat shock variably as judged from the induction of the major heat shock proteins, 70, 72 and 92 kDa. Variable expression of the heat shock proteins suggests that the selective pressure for isolation of cell clones may affect gene expression differently.

The differential effect of normal cells and their neoplastic transformants on embryonic cell adhesion

The adhesion of 7 day old embryonic chick neural retina cells was reduced by adult calf serum whereas foetal calf serum diminished adhesion to a lesser extent. Conditioned media from normal cells either increased the adhesion of neural retina cells or had no effect. Media from malignant cells reduced the adhesion of the retina cells. The results are discussed in relation to malignant invasion.