Region Of Long Arm Research Articles

Variation and evolution in the karyotype of Lycoris, Amaryllidaceae. IV Intraspecific variation in the karyotype of L. radiata (L'Herit.) Herb. and the origin of this triploid species.

1) Intraspecific variation in the karyotype of L. radiata was studied. Five hundred and nineteen bulbs from fifty-eight populations were examined.2) Standard karyotype consisting of thirty-three A type chromosomes (2n=33=33A) was found in 97.3% of examined materials.3) Standard karyotype includes two A type satellite chromosomes heterozygously. Namely the size of short arm of one satellite chromosome is smaller than that of the other. Moreover, four A type chromosomes having high r value are always included in the standard karyotype.4) In some cells, three satellite chromosomes were observed.5) Robertsonian fusion between two A type chromosomes had occurred in some bulbs, then M' and m type chromosomes were produced. So, this m type chromosome is euchromatic and it segregates normally and inherits into the daughter cells. This chromosome must be equivalent to m type chromosome observed in L. albiflora and L. incarnata.6) The karyotype consisting of 31A and 1M' was found in the bulbs from Ebira population. This M' type chromosome might also be a product of Robertsonian change between two A type chromosomes, and in this case m type chromosome or fragemented short arms were eliminated.7) Secondary constriction at the proximal region of long arm of one A type chromosome was observed in the complements of some bulbs from Uematsu population.8) The birthplace of this triploid plant is supposed to be China, and its very stable karyotype also suggests that it is a prehistoric naturalized plant introduced into Japan from China with the traffic of men.

Isolabeling of the long arm of the human Y chromosome demonstrated by the FPG technique.

Isolabeling segments were found in the distal region of the long arm of Y chromosomes derived from human leukocytes grown through two replication cycles in medium containing BrdU and stained by the FPG technique. Three main types of Y chromosome staining patterns were demonstrated: I-Y chromosome with typical SCD, II-Y chromosome with weakly stained distal regions of long arms (isolabeling segments), III-Y chromosome with both terminal regions displaying SCD interrupted by one isolabeled segment. The existence of different types of Y chromosome staining patterns was explained on the basis of the previously described hypothesis of unequal distribution of thymine residues between two DNA polynucleotide chains in the distal part of the long arms of human Y chromosomes.