MIMOSINE, A NATURALLY-OCCURRING DRUG INTERFERING PRIMARILY WITH THE CELL-NUCLEUS

The non-proteinogen aminoacid mimosine interfered seriously with cultu red carp hepatocytes when added to the culture medium for 6 h in a con centration of 0.1 M. Cell transformation started with condensation of the chromatin into an unusual network of fibrils and segregation of th e reticulate nucleolus into its fibrillar and granular components. The n chromatin condensation spread homogeneously across the entire nucleu s. At the end of the condensation period the nuclear envelope extended towards the cytoplasm and the nuclear interior resulting in a very co nfusing nuclear boundary. Later, the nucleus expanded and the chromati n was gradually decondensed but the segregated nucleolus persisted unt il nuclear lysis. The DNA staining pattern did not change throughout t he condensation period. DNA was even present in most decondensing nucl ei. The cytoplasmic organelles were only slightly affected during chro matin condensation but significantly altered thereafter. The observed course of mimosine-induced cell transformation is very unusual. The fi rst period covering chromatin condensation with structural intactness of the cell organelles resembles in some aspects apoptosis but additio nally includes some special signs. The following phase of cellular dis integration, however, is similar to necrosis. Due to this unique cours e of cell death, mimosine should be further tested for its potential s uitability in experimental cell research and cancer chemotherapy.