STUDIES ON THE MORPHOLOGY AND NUCLEIC ACID CONTENT OF PROTOPLASTS OF BACILLUS MEGATERIUM

Publisher Website
Google Scholar
Abstract
Transfer of rejuvented vegetative cells to sucrose-phosphate-MgSO4 stabilizing medium resulted in a transient aggregation of bacterial nuclear bodies, apparently caused by Mg ions in the presence of sucrose. Strongly cationic buffers caused a more permanent aggregation. Nucleic acid content of the cells was not altered by buffer transfer but 12% of the total ribonucleic acid (RNA) and none of the deoxyribonucleic acid (DNA) was lost when the cell walls were removed by lysozyme digestion. The contraction that occurred when sucrose-stabilized protoplasts were transferred to strongly cationic stabilizing buffers was accompanied by further nuclear aggregation and RNA loss. Osmium but not formalin fixation removed 20% of the remaining protoplast RNA. The nucleic acid contents of native and fixed protoplasts subjected to osmotic shocking were compared. The fixed showed greater retention of RNA and their reversible swelling appeared to result more from ionic than osmotic changes. Depending on the stage of cell division, the protoplast nuclear body is an aggregate structure of a dividing or two just divided nuclei of the vegetative cell. The average DNA-P/protoplast varied from 4.3 to 9.0 x 10-15 g and showed a relation to the degree of rejuvenation of the original cells. The nuclear body of the intact protoplast was subjected to sequential DNA and protein staining procedures.