CYTOCHEMICAL AND IMMUNOCYTOCHEMICAL STUDY OF NUCLEAR-STRUCTURES OF LACANDONIA-SCHISMATICA

The interphase nucleus of the cells of several tissues of Lacandonia s chismatica was studied using electron microscopy cytochemical and immu nocytochemical methods. The EDTA staining procedure, preferential for RNP, contrasted the Lacandonia granules and perichromatin fibrils. The se granules were found to be relatively resistant to RNAse hydrolysis, but they were easily digested if RNAse treatment was carried out afte r a short hydrolysis with pronase. Bismuth oxynitrate stained granular structures about 17 nm in diameter and the periphery of a few Lacando nia granules. The anti-snURNPs bound to RNP-containing fibrils in the perichromatin and interchromatin space and also to the periphery of so me Lacandonia granules. Immunolabeling of DNA demonstrated numerous fi laments of extended chromatin in the perichromatin and interchromatin spaces which were closely related to, Lacandonia granules. These obser vations suggested that Lacandonia granules are equivalent to Balbiani ring granules of nuclei with polytene chromosomes and to perichromatin granules of other plant and animal nuclei. The small number of Lacand onia granules labeled in their periphery by anti-snURNP mAb were inter preted as being immature granules in the process of formation. The ext ernal or annular part of the ring-shaped structures is heavily labeled by anti-URNP mAbs but scarcely stained by the EDTA procedure. These f eatures indicate that this region contains abundant proteins associate d with snURNAs but probably little snURNAs. The synaptonemal-like comp lexes previously found in the interphase nuclei of Lacandonia are form ed by two parallel masses of compact chromatin, which react with anti- DNA, and a central clear space crossed by fiber. Most of these fibers do not react with tests for DNA or RNA and are probably composed of pr oteins. The EDTA procedure contrasts some fibrils at the internal aspe ct of the masses of compact chromatin, suggesting the presence of remn ants of the lateral element of a synaptonemal complex.