, Volume 9, Issue 1, pp 292-304

Adhension loci in the differentiated heterochromation of trillium species

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Summary

  1. After cold treatment, specific points in heterochromatic (H) segments stick together at anaphase. These have been calledadhesion loci. They are constant in position within a given segment. Sister reunion (SR) of the ends of H-segments can also follow cold treatment.

  2. SR sometimes persists into telophase, so forming a bridge between daughter nuclei.

  3. Adhesion loci have been found only onT. erectum, T. cernuum,T. luteum, T. sessile, T. recurvatum andT. chloropetalum. They have not been found inT. grandiflorum, T. ovatum, T. stylosum, T. undulatum,Paris polyphylla or any of the Japanese species ofTrillium.

  4. Adhesion loci are found in all chromosomes other than A. They do not occur in H-segments less than 1.5 μ in length.

  5. Evidence is. presented of inversion within the H-segments ofT. erectum andT. cernuum.

  6. Adhesions are probably due to subchromatid breakage followed by partial inverted reunion. Such reunions seem to be under the control of the centromere.

  7. Spontaneous adhesions are probably not identical with those “point errors” which follow X-rays and chemical treatments.