Chromosome Studies on Trillium kamtschaticum Pall

VI. On the nucleolus-chromosome relationship

Abstract

1. In Trillium kamtschaticum in whose complement neither satellited nor secondary-constricted chromosomes are present, the development of nucleoli is related to the particular ends of particular chromosomes, viz., both distal ends of chromosome A and the distal end of the short arm of chromosome E. No heterochromatic region is found at these particular chromosome ends; they are distinguished only functionally.
2. In contrast with the above, Paris hexaphylla is of the so-called SAT-chromosome type as to the nucleolus development. In this, the idiogram is closely allied to that of Trillium except that chromosome D is satellited and the nucleolus develops at the satellite portion of the same (see Diagram 2).
3. Evidence from abnormal meiotic divisions in Trillium shows that every chromosome of a complement is provided with functional activity for nucleolar development which comes to express itself in such special conditions as that each of the chromosomes is isolated and forms a micronucleus.
4. From these findings, a hypothesis on the origin of SAT-chromosomes was presented.