Number and pattern of association of chromonemata in the chromosomes of Tradescantia

Observations on a Vesicular Particle Associated with the Chromatin of the Nuclei ofTradescantiaStaminate-Hair Cells

“…Although the idea is purely speculative, it seems possible that after the PV s have made contact with the chromosomes in anaphase and early telophase they bind specific areas of these chromosomes with the nuclear membrane. There is now mounting evidence that the chromosomes are connected with the nuclear membrane (SPARVOLI et al 1965;DuPRAW 1965;FELDMAN 1966;COMINGS and KAKEFUDA 1968), and our observations suggest a possible mechanism by which such contacts are established.…”

“…The technique used was the same as that employed in our previous studies (SPARVOLI, GAY and KAUFMANN 1965). In brief, it consists of fixing the staminate hairs for two hours in 1% Os04 at pH 7 .4, post-fixing in uranyl acetate, embedding and orienting single hairs in small drops of Maraglas (FREEMAN and SPURLOCK 1962 ), and eventually incorporating such droplets in inverted gelatin capsules filled with fresh resin.…”

“…During an investigation of the chromosomal changes occurring in the mitotic cycle of apical celJs of staminate hairs in Tradescantia (SPARVOLI et al 1965) we repeatedly observed small ring-like structures, closely associated with the chromatin, that were tentatively designated as perichromatin vesicles. Although a variety of small particles and granules have been reported to be present in the nucleolus (CoHEN 1957;LAFONTAINE 1958;PORTER 1966;SANKARANARAYANAN and BUSH 1965;SuN 1961) and in the nucleus (WATSON 1962;SwiFT 1959), they all differ appreciably in structure from the perichromatin vesicles.…”

THE STRANDEDNESS OF MEIOTIC CHROMOSOMES FROM ONCOPELTUS

“…In their extensive review of the literature of light microscopy dealing with the problem of strandedness, Kaufmann et al (16) conclude that results from this source eliminate the possibility of a single stranded chromosome. In a more recent electron microscope study (25), in which a report is given of reconstruction of the three-dimensional configuration of mitotic chromosomes from thin sections of Tradescantia, Kaufmann and his coworkers report that these chromosomes are multistranded and reaffirm their earlier interpretation of chromosome structure. Trosko and Wolff (28) have also determined the chromosome to be multistranded under the light microscope, after digestion by trypsin, and in their review of the literature similarly point out the preponderance of evidence from light microscopy for the multistranded chromosome.…”

The Fine Structure of Chromosomes in Pollen Mother Cells of <i>Tradescantia reflexa</i>

“…The structure has been examined in more detail by light microscopic autoradiography and by electron microscopy. Several models of chromosomes have been proposed, such as a multistrand model (Steffensen 1959, Sparvoli, Gay and Kaufman 1965, Ris 1962, Wolfe and Martin 1968, Wolff 1969, protein-backbone model (Taylor 1957, andFreese 1958), supercoil model (Amano, Dohi, Tanaka, Uchino and Hiraoka 1956), cycloid model (Whitehouse 1967) and single strand model (Callen 1963, Gall 1963, DuPraw 1966, Ris 1969. DuPraw (1966) was offered "folded fiber model" as one of single strand models.…”