A cytophotometric study of chromosome pairing

Ansley, Hudson R.

doi:10.1007/bf01259510

Cited by 33 publications

(9 citation statements)

References 9 publications

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“…For instance, the macronucleus of Tetrahymena takes up less fast green relative to the Feulgen stain than does the micronucleus (4). Again in the centipede, Scutigera, and in the pentatomid bug, Loxa, the nuclei which show asynapsis during meiosis bind a relatively greater amount of fast green than the normal nuclei (5). In none of these cases is there independent evidence to indicate whether the variability in staining ratio is due to differences in the DNA/histone ratio, to variability in types of histone or their association with the DNA, or to other factors.…”

Section: Discussionmentioning

confidence: 98%

Macronuclear Duplication in the Ciliated Protozoan Euplotes

Gall

1959

The Journal of Cell Biology

171

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The ribbon-like macronucleus of Euplotes euryslomus pinches in half amitotically at each cell division. Several hours before the actual division two lightly staining duplication bands (reorganization bands) appear at the ends of the nucleus and approach each other slowly, finally meeting near the middle. Distal to the bands, that is, in regions through which the bands have already passed, the concentration of DNA (Feulgen) and "histone" (alkaline fast green) is greater than in the central zone. These facts suggest the hypothesis that DNA-histone synthesis takes place in a sequential fashion starting at the tips of the nucleus and proceeding to the middle. That this hypothesis is correct is shown by autoradiographic and photometric observations. Tritium-labelled thymidine is incorporated only in a limited region immediately distal to the bands. The average amount of Feu]gen dye bound by the nucleus rises as the duplication bands approach each other, and is double the presynthesis value by the time the bands meet. A similar rise in the alkaline fast green dye is seen in duplicating nuclei, although no completely post-synthesis values were obtained in this study. The quantitative data are consistent with the assumption that the macronue]eus contains a number of DNA-histone "units," presumably chromosomes, each of which duplicates once and only once.No other animals display such a diversity of nuclear phenomena as the Protozoa, and consequently, this group has long held the attention of cytologists and geneticists alike. A persistent problem concerns the nature of the ciliate macronucleus which, as is well known, plays an important role in the determination of the phenotype (29) and yet divides "amitotically." The present study deals with the mechanism of macronuclear duplication in the hypotrich ciliate, Euplotes eurystomus, and gives particular attention to the synthesis of deoxyribose nucleic acid (DNA) and histone. As we shall see, amitosis in this case follows an exceedingly precise course (cf. reference 18).In common with other ciliates Enplotes possesses an inconspicuous micronucleus and all enormous, densely staining macronucleus. In this form the macronucleus is a C-or W-shaped band * Supported by funds from the National Science Foundation and the Graduate School of the University of Minnesota.

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Section: Discussionmentioning

confidence: 98%

Macronuclear Duplication in the Ciliated Protozoan Euplotes

Gall

1959

The Journal of Cell Biology

171

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“…Taking into account Ansley's (1957Ansley's ( , 1958 observations on Loxa flavicolis, interesting biochemical explanation for the occurrence of chromosome pairing or the lack of it has been postulated by Riley (1966): Synapsis may be dependent upon the DNA constituent of the chromosomes, but whether or not it is realized in a particular cellular situation is determined by how the DNA is complexed with histones. Desynaptics may provide a valuable tool for the experimental approach to the problems of chromosome pairing and chiasma formation.…”

Section: Observation and Discussionmentioning

confidence: 99%

Partial Desynapsis in <i>Pennisetum ramosum</i> (Hochst.) Schweinf

Jauhar

Alice

1971

CYTOLOGIA

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“…The cytological features of the harlequin lobe have been reported by a number of investigators (Schrader, 1945a(Schrader, , 1945b(Schrader, , 1946a(Schrader, , 1946b(Schrader, , 1960Martin, 1953;Srivastava, 1957;Ansley, 1957Ansley, , 1958 and a renewed description is hardly called for here. In essence, it may be said that the deviations from normal conditions that occur in the harlequin lobe affect especially the mitotic processes of the autosomes so that they are distributed irregularly in the maturation divisions.…”

Section: Spermatogenesismentioning

confidence: 88%

Evolutionary Aspects of Aberrant Meiosis in Some Pentatominae (Heteroptera)

Schradér¹

1960

Evolution

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A cytophotometric study of chromosome pairing

Cited by 33 publications

References 9 publications

Macronuclear Duplication in the Ciliated Protozoan Euplotes

Macronuclear Duplication in the Ciliated Protozoan Euplotes

Partial Desynapsis in <i>Pennisetum ramosum</i> (Hochst.) Schweinf

Evolutionary Aspects of Aberrant Meiosis in Some Pentatominae (Heteroptera)

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