The effect of X-rays on the first meiotic division in three species of orthoptera

White, M. J. D.

doi:10.1098/rspb.1937.0081

Cited by 19 publications

(2 citation statements)

References 2 publications

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“…There is chromosome lagging and 'bridge' formation in anaphase and telophase (table 1). Such 'bridges' were also found by White (1937) in irradiated grasshoppers where the chromosomes certainly have a localised kinetochore.…”

Section: Observationsmentioning

confidence: 80%

The Kinetochore in <i>Eurybrachis apicalis</i> (Hornoptera Auchenorrhyncha)

1959

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Section: Observationsmentioning

confidence: 80%

The Kinetochore in <i>Eurybrachis apicalis</i> (Hornoptera Auchenorrhyncha)

1959

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“…X-ray induced fragmentation of chromosomes with localized kinetochore produced multiple fragments, only one of which contained a kinetochore. This fragments attached to the spindle and moved normally, but the fragments that lacked a kinetochore failed to attach and were lost at subsequent divisions [124]. By contrast, chromosomes with diffuse kinetochores were connected to spindle fibers by the entire poleward surface of each chromosome.…”

Section: Insights Into Mitotic Mechanism From Studies Of Mitotic Pmentioning

confidence: 99%

A Brief History of Research on Mitotic Mechanisms

McIntosh

Hays

2016

Biology

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This chapter describes in summary form some of the most important research on chromosome segregation, from the discovery and naming of mitosis in the nineteenth century until around 1990. It gives both historical and scientific background for the nine chapters that follow, each of which provides an up-to-date review of a specific aspect of mitotic mechanism. Here, we trace the fruits of each new technology that allowed a deeper understanding of mitosis and its underlying mechanisms. We describe how light microscopy, including phase, polarization, and fluorescence optics, provided descriptive information about mitotic events and also enabled important experimentation on mitotic functions, such as the dynamics of spindle fibers and the forces generated for chromosome movement. We describe studies by electron microscopy, including quantitative work with serial section reconstructions. We review early results from spindle biochemistry and genetics, coupled to molecular biology, as these methods allowed scholars to identify key molecular components of mitotic mechanisms. We also review hypotheses about mitotic mechanisms whose testing led to a deeper understanding of this fundamental biological event. Our goal is to provide modern scientists with an appreciation of the work that has laid the foundations for their current work and interests.

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Spontaneous Meiotic Chromosome Breakage in Natural Populations of Paeonia Californica

Walters

1956

American J of Botany

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THE AMERICAN SPECIES of Paeonia, P. calilornica and P. brownii, show in natural populations a high degree of meiotic irregularity. They have evolved a cytogenetic system of which the most prominent feature is permanent translocation heterozygosity, comparable to that of Oenothera (Stebbins and Ellerton, 1939; J. Walters, 1942). They show in addition a great deal of inversion hybridity, revealed by the familiar bridge-and-fragment configurations of heterozygous paracentric inversions, and by the presence of heteromorphic chromosome pairs which have been interpreted as the result of heterozygosity for pericentric inversions (J . Walters, 1952). In the course of the previous studies of structural hybridity, occasional cells were noted which showed fragmentation in meiosis occurring in various degrees. A range of breakage has been observed from cells with a single fragment to cells in which not a single intact chromosome is present. As spontaneous fragmentation in meiosis is not common, and has not previously been reported to occur in a structural hybrid, a study was undertaken to determine the extent to which fragmentation occurs in P. calijornica, and whether any relationship can be shown with the other kinds of meiotic irregularity. The results of this study form the subject of the present paper.MATERIALS AND METHODS.-Flower buds of P. calilornica were collected in the field, fixed in Bradley's (1948) fixative, and stored in the fixative under refrigeration. The studies and photomicrographs were made from temporary and permanent iron-acetocarmine smears. In order to investigate the relationship between the extent of translocation heterozygosity and that of breakage, the plants selected for study included four pairing types: the translocation homozygote, with 5[]; an intermediate translocation heterozygote, with 06+2[]2; and two types of extreme heterozygote, with 010 and 06 +04 respectively. In addition to the material collected in the wild, fixations were made from two plants that had been transplanted several years earlier into the Santa Barbara Botanic Garden, to observe possible effects on breakage of growing a plant in other than its native habitat. In five plants, four stages of meiosis (metaphase and anaphase of the first and second divisions) were studied, to 1 Received for publication October 25, 1955. This work has been supported by grants from the Committee on Research of the University of California, Santa Barbara College. Much of the research was done in the laboratory of the Santa Barbara Botanic Garden. The author acknowledges with thanks the support of these institutions, and wishes also to thank Dr. Marta S. Walters for helpful suggestions and for critical reading of the manuscript.2 The symbol 0 means "ring of." determine the frequency and behavior of fragments and related phenomena throughout the course of meiosis. In an additional 11 plants, only anaphase I was studied. One hundred cells of each stage studied in each plant were selected at random. TYPES AND FREQUENCIES OF FRAGMENTs.-Meiotic fr...

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The effect of X-rays on the first meiotic division in three species of orthoptera

Cited by 19 publications

References 2 publications

The Kinetochore in <i>Eurybrachis apicalis</i> (Hornoptera Auchenorrhyncha)

The Kinetochore in <i>Eurybrachis apicalis</i> (Hornoptera Auchenorrhyncha)

A Brief History of Research on Mitotic Mechanisms

Spontaneous Meiotic Chromosome Breakage in Natural Populations of Paeonia Californica

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