Sub-Chromatid Structure and Chromosome Duplication in Vicia faba

The Karyotype in Systematics

“…Studies in 1957 demonstrated the semicon servative nature of chromosomal DNA distribution, and the results indi cated that each daughter chromatid was composed of a single strand of DNA (15 1). Results at variance with this interpretation, suggesting a mul tistranded model, have come largely from studies on chromosome breakage and reunion brought about by ionizing radiation or chemical mutagens, from treatments involving several kinds of fi xatives or enzymes, and from isolabeling results (5,92,110,111,154,171). Few observations were made on living materials (4).…”

The Double Strandedness of Chromatid in the Metaphase Chromosomes of Cultured Cells Treated With Hot Saline Solutions

“…The occurrence of sidearm anaphase bridges, sidearm exchange, induced in late prophase or metaphase by radiation has been reported by a number of authors (Brinkley and Humphrey 1969;Fox 1966;Heddle 1969;Peacock 1961 were prepared in the same way as described above. The chromosome preparations were immersed in 2 x SSC (0.3 M NaCI/0.03 M trisodium citrate, pH 6.8), Sorensen buffer (M/10 NaH2PO4/Na2HPO4, pH 6.8), or Michaelis buffer (M/10 sodium barbiturate/M/10 HCI, pH 6.8) for appropriate times, ranging from 1 minute to 180 minutes, at 60°C or 69°C.…”

“Sub-chromatid” exchanges in Vicia sativa

“…A quadripartite structure of Vicici f r i h chromosomes has I)een inferred from the fact that chromosome intra-a n d interchanges which apparently involve half-chromatids can be induced b y X-irradiation in prophase a n d metaphase of mitotic a n d meiotic cells (PEACOCK, 1961). T h e same type of a1)errations has been induced in Vicin faba b y ,the chemical 8-ethoxycaffeine, EOC (KIHL-M A N an'd HARTLEY, 1967).…”