Action of short-term cycloheximide administration associated with colchicine on nuclear and chromosome structure in cleaving Newt eggs. Reappearance of chromomeres?
Association of short-term cycloheximide (CHM) administration (1/3, 1/2 or 1 cycle) with long-term treatment by colchicine (Co) confirms the results obtained by CHM alone under similar conditions, namely the striking relationship between the starting-time of treatment and the type of nuclei obtained (centred telophasic or non-centred prophasic). This relationship is highly significant. Various nuclear structures were observed: they correspond to a special evolution of the abnormal nuclei during telophase, telo-prophase and prophase which is very different from that in untreated ones. A difference in evolution of the central and peripheral parts of the same nucleus explains their centred structure. On the contrary, this difference disappears at prophase. The association CHM-Co favours the unveiling of beads which are interpreted as prophasic chromomeres. These beads are of different size, spacing and form according to the moment of the prophasic evolution attained. Electron microscopy study confirms the strong dispersion of chromatin by CHM and the beaded appearance of chromosomes by CHM and Co. Simultaneously, many dense bodies are accumulated in the centrospheres, as after quinoline and glutaraldehyde administration. The mechanisms of production of centred nuclei and of the beaded appearance of chromosomes are discussed.
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects* / Q000648:ultrastructure; D002875:Chromosomes / Q000187:drug effects* / Q000648:ultrastructure; D002970:Cleavage Stage, Ovum / Q000187:drug effects* / Q000648:ultrastructure; D003078:Colchicine / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology*; D012455:Salamandridae
D003513:Cycloheximide; D003078:Colchicine