RESUMO
The microtubule system of normal and microtubule-poisoned amoebae of Dictyostelium discoideum has been investigated both by indirect immunofluorescence with antibodies to microtubule proteins and electron microscopy. Nocodazole, like some other microtubule poisons, destroys most of the microtubules in both interphase and dividing cells resulting in an inhibition of nuclear and cell division. The microtubule organizing centres, however, continue to duplicate once or twice. The daughter organizing centres segregate, they seem to be connected with nuclear material, that splits partly, too, forming more or less extended nuclear clefts. This segregation, at least over short distances, takes place without intranuclear microtubules. Duplication of microtubule organizing centres is not strictly correlated with nuclear division and cytokinesis. Microtubule poisons are able to uncouple these events. Different levels of regulation should be responsible for microtubule organizing centre, nuclear, and cell division.
Assuntos
Dictyostelium/ultraestrutura , Microtúbulos/fisiologia , Animais , Divisão Celular/fisiologia , Núcleo Celular/metabolismo , Núcleo Celular/fisiologia , Dictyostelium/metabolismo , Imunofluorescência , Masculino , Microscopia Eletrônica , Microscopia de Fluorescência , Microtúbulos/ultraestrutura , Mitose/efeitos dos fármacos , Nocodazol/farmacologia , CoelhosAssuntos
Aspergillus nidulans/efeitos dos fármacos , Benomilo/farmacologia , Carbamatos/farmacologia , Aspergillus/ultraestrutura , Núcleo Celular/ultraestrutura , Mitose/efeitos dos fármacos , Organoides/efeitos dos fármacos , Organoides/ultraestrutura , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/ultraestruturaRESUMO
The nucleus-associated organelle (NAO) is a structure, significant for division and motion of the fungal nucleus. In the basidiomycete Polystictus (equals Trametes) versicolor it is composed during somatic interphase of two globular entities (GE) and the connecting middle plate (MP). Its genesis is followed electron optically by analysing serial sections of preselected stages. Genesis is strictly determined by time and space. It starts with synthesis of the new MP a few minutes upon karyokinesis has been completed. Synthesis is localized in the area of contact between old GE and outer membrane of the nuclear envelope. After growing of the MP to its maximal size both new GE's develop from swellings at its ends. Old Ge's are dissolved during this developmental process. The period of genesis takes 30--40 min and fills one third of the cell cycle. A GE-field exhibits characteristic alterations throughout the formation of the NAO. It is composed of GE, periglobular zone, microtubules, and both caps of endoplasmic reticulum and multivesicular bodies.
