RESUMO
Variable germination and outgrowth occurred when Bacillus subtilis NCTC 8236 spores were inoculated into nutrient broth prepared with distilled water. More reproducible findings were achieved when the medium was prepared with Elgastat water and the greatest reproducibility occurred with Elgastat water as vehicle combined with a rigorous acid-washing of all glassware. This combined procedure also produced optimum and reproducible results for the synchronous growth of two B. subtilis 168 strains in casein medium supplemented with appropriate amino acids, a technique of value in monitoring the development of resistance to antibacterial agents during sporulation. The levels of aluminium in distilled water were higher than those of other elements; however, the incorporation of aluminium sulphate into broth prepared with Elgastat water had no effect on germination, and outgrowth was reduced (but not eliminated) only at high concentrations of this salt.
Assuntos
Bacillus subtilis/fisiologia , Esporos Bacterianos/crescimento & desenvolvimento , Água/química , Aminoácidos/metabolismo , Bacillus subtilis/efeitos dos fármacos , Caseínas/metabolismo , Meios de Cultura/química , Meios de Cultura/farmacologia , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/fisiologiaRESUMO
Various techniques were studied for fixing spores of Bacillus subtilis prior to examining them by transmission or scanning electron microscopy. A non-aldehyde technique employing carbodiimide in cacodylate buffer produced excellent results and could be of value in studying the cytological changes produced in spores exposed to inimical treatments.
Assuntos
Bacillus subtilis/ultraestrutura , Técnicas Bacteriológicas , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica/métodos , Carbodi-Imidas , Fixadores , Esporos Bacterianos/ultraestruturaRESUMO
The effects of sublethal concentrations of the membrane-active agent chlorhexidine gluconate (CHG) on the growth rate and sporulation of Bacillus subtilis vegetative MB2 cells have been investigated. CHG increased the mean generation time (Mgt) of vegetative cells in casein medium. It also affected spore development: as CHG concentrations increased, spore index (SI) values decreased and sensitivity to both toluene and heat increased.
Assuntos
Bacillus subtilis/efeitos dos fármacos , Clorexidina/análogos & derivados , Bacillus subtilis/fisiologia , Clorexidina/farmacologia , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/crescimento & desenvolvimentoRESUMO
Mice reconstituted with BCR/ABL-infected 5-fluorouracil-treated bone marrow are considered a model system for human chronic myelogenous leukemia, a malignancy that arises in hematopoietic stem cells. These animals develop multiple types of hematopoietic tumors, which could arise either from undifferentiated cells that mature during tumor development or from progenitors committed to different lineages. To examine the BCR/ABL-sensitive target cells present in the marrow of mice treated with 5-fluorouracil, we used a single-step in vitro assay. These experiments revealed that both the P210 and P185 BCR/ABL proteins and the related v-abl protein induce lymphoid and myeloid colonies, colony types that mimic two of the prominent types of tumors found in the reconstitution model. The lymphoid colonies were similar to lymphoid colonies found following infection of normal bone marrow with respect to differentiation state and tumorigenicity. The cells in the myeloid colonies were differentiated and non-tumorigenic. Fluorescence-activated cell sorting revealed that most of the lymphoid and myeloid colonies arose from distinct precursors and that the lymphoid colonies arose from B-lineage-committed cells. These data suggest that most of the lymphomas observed in the reconstitution model arise from committed progenitors that are distinct from those involved in the myeloid disease.