Distinct low level chemiluminescence patterns during aerobic growth of a selection of bacterial strains of the lactic acid group were recorded in on-line measurements. These patterns may be specific for the strain and the medium employed for cultivation. The patterns are oxygen-dependent and consist in the case of Enterococcus faecalis of three basic patterns, which reflect different mechanisms leading to both the generation and depletion of initiators of the chemiluminescence, particularly hydrogen peroxide and superoxide radical. The influence of catalase and superoxide dismutase on the patterns was examined. We could demonstrate the sensitivity of chemiluminescence measurements for the detection of both exogenous oxidative stress, which is imposed to the cells by reactive species formed in the medium, as well as endogenous oxidative stress, which is due to products of the cellular oxygen metabolism, the latter being often the reason for growth restriction.

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PubMedDate not supplied

Cytotoxic and genotoxic effects of bromodeoxyuridine during in vitro labelling for sister-chromatid differentiation in preimplantation mouse embryos.

Exposure of preimplantation mouse embryos in culture to bromodeoxyuridine (BrdU) in the concentration range of 10(-9) to 2 x 10(-6) M allows sister-chromatid differentiation at the morula and blastocyst stage. The same BrdU concentrations induced no chromosomal aberrations, but a prolongation of the cell cycle and an increase of the SCE frequency. Even at the lowest BrdU concentration for sister-chromatid differentiation (10(-9) M the background level for SCE was found to be significantly higher in early embryos than in fetal or adult tissues of the mouse. Therefore, the high SCE frequency seems to be characteristic of undifferentiated embryonic cells. Methodological recommendations are also given for SCE assay in preimplantation mouse embryos.

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PubMedDate not supplied

Increased sister-chromatid exchange frequency in preimplantation mouse embryos after maternal cyclophosphamide treatment before implantation.

The effect of a toxic agent in vivo on sister-chromatid exchange (SCE) frequency of preimplantation mouse embryos and bone marrow cells was determined using combined in vivo treatment and in vitro culture in the presence of 5-bromo-2-desoxyuridine (BrdU) for differential staining of the chromatids. In mice exposed to cyclophosphamide (CPA) on day 2 of pregnancy SCE frequency was increased dose-dependently both in embryos and bone marrow cells 1 h after treatment. It returned to control values in bone marrow cells obtained 24 h after exposure but was still significantly increased in the embryos. A closer time-related evaluation of SCE on day 2 of gestation showed a significant increase in SCE in bone marrow cells and in embryos obtained 20-60 min after CPA treatment. Furthermore, SCE frequency was the most sensitive toxicological endpoint to detect embryotoxic effects of CPA treatment before implantation, since it was significantly increased in embryos exposed to 5 mg/kg CPA on day 2 of pregnancy while embryolethality at term and both cytogenetical (structural chromosomal aberrations, micronuclei) and developmental parameters (cell number, differentiation in culture) before implantation did not indicate any toxic effect.

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PubMedDate not supplied

[The Leafhopper Neoaliturus haematoceps (Mulsant & Rey) is a vector of Spiroplasma citri in the Mediterranean].

Among the many leafhoppers which we have collected and identified in Morocco, Turkey, Syria and France (Corsica), only the species Neoaliturus haematoceps was found to be infected with Spiroplasma citri. In Syria, this leafhopper was encountered on ornamental stock plants (Matthiola incana L.) in the Oronte valley, and on Salsola kali L., a wild Chenopodiacae of the semi-arid regions of the coastal area. In Corsica, we found it on wild stock plants (Matthiola sinuata R.Br.) of the oriental coast and on bush plants. A breeding of this leafhopper was initiated, and we demonstrated that it was able to acquire S. citri from infected periwinkles, multiply the organisms in its body and transmit them to healthy plants. This leafhopper can also be infected after injection of S. citri. The leafhoppers thus inoculated can transmit the spiroplasma very efficiently to healthy plants. This is the first report of the transmission of S. citri by Neoaliturus haematoceps both after acquisition on a diseased plant and after injection.

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