Biological Effects of Radiation: Mechanism and Measurement of Radiation, Applications in Biology, Photochemical Reactions, Effects of Radiant Energy on Organisms and Organic Products - Vol. 2

By Benjamin M. Duggar | Go to book overview

Rearrangement or translocation and losses of portions of the chromosome complement occur with very high frequency as a consequence of X-ray treatment--thus, Stadler (64) concluded from his studies on Zea Mays. In both translocation and deficiency, a part of a chromosome is separated from the remainder; in deficiency, this section is lost, while in translocation it becomes attached to another chromosome or section. Deficiency may involve a section of an entire chromosome and may be single or multiple; translocation, whether simple or reciprocal, may involve one or more transfers or interchanges. Combinations of deficiency and translocation also may occur.

Recent work by Narimatsu (45) on V. Faba, which confirmed results of certain authors mentioned previously, indicated that with weak irradiation there was no marked abnormality in cell arrangement as compared with the nonirradiated group. The most marked change was in the cell nucleus where mitoses were decreased. Degenerative changes and swelling of the cell body were more pronounced with medium irradiation, and abnormal cell arrangement occurred. With strong irradiation, swelling of the cell body took place and almost no structure was observed in the protoplasm. No mitoses were observed and the nuclei were swollen and degenerated. Narimatsu (45) concluded that the change in cell arrangement was not a direct result of irradiation but was secondary to change in the nucleus, since the part first affected is the nucleus.

Bersa (7a) concludes that so-called ray-resistant and ray-susceptible plants behave similarly cytologically. X-rays cause depression in frequency of nuclear division; the stronger the rays, the greater the depression. Prophases suffer only temporarily a stronger depression, which indicates that the rays delay appearance of division phases from the resting nuclei. Bersa did not observe abnormal mitoses until 36 hr. after irradiation.

There seems to be general agreement that cells of the growing tip are more sensitive to the action of the rays than those of other regions. The nucleus is more ray-sensitive than the cytoplasm; hence it is suggested that there may be an alteration in the nucleus-cytoplasm ratio when mitoses are decreased without a proportional decrease in the amount of protoplasm. Mitotic irregularities occur in the leaves as well as in the growing points of stems and roots. Numerous chromosomal irregularities, including rearrangement or translocation of portions of chromosomes, are evident after heavy irradiation.


GENERAL SUMMARY

The investigations reviewed in this paper have dealt with the physiological, morphological, histological, and cytological aspects of the effects of X-radiation on green plants. In spite of the large number of publica-

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Biological Effects of Radiation: Mechanism and Measurement of Radiation, Applications in Biology, Photochemical Reactions, Effects of Radiant Energy on Organisms and Organic Products - Vol. 2
Table of contents

Table of contents

  • Title Page iii
  • Contents v
  • Xix Photoperiodism 677
  • Introduction 677
  • References 709
  • Xx Plant Growth in Continuous Illumination 715
  • References 725
  • Xxi the Effects of Light Intensity Upon Seed Plants 727
  • Introduction 727
  • References 757
  • Xxii Effects of Different Regions of the Visible Spectrum Upon Seed Plants 763
  • Introduction 763
  • Concluding Remarks 787
  • References 788
  • Xxiii Effect of the Visible Spectrum Upon the Germination of Seeds and Fruits 791
  • References 823
  • Xxiv the Effects of Visible and Ultra-Violet Radiation on the Histology of Plant Tissues 829
  • References 838
  • Xxv Some Infra-Red Effects on Green Plants 841
  • References 851
  • Xxvi the Effect of Ultra-Violet Radiation Upon Seed Plants 853
  • Introduction 853
  • Concluding Remarks 881
  • References 882
  • Xxvii the Effects of Radiation on Fungi 889
  • Introduction 889
  • References 910
  • Xxviii the Problem of Mitogenetic Rays 919
  • Introduction 919
  • Conclusions 944
  • References 946
  • Xxix Effects of X-Rays Upon Green Plants 961
  • Introduction 961
  • General Summary 980
  • References 983
  • Xxx the Effects of Radium Rays on Plants 987
  • References 1009
  • Xxxi the Light Factor in Photosynthesis 1015
  • References 1051
  • Xxxii the Influence of Radiation on Plant Respiration and Fermentation Charles J. Lyon 1059
  • Introduction 1059
  • Summary 1071
  • References 1072
  • Xxxiii Growth Movements in Relation to Radiation 1073
  • Xxxiv Chlorophyll and Chlorophyll Development in Relation to Radiation 1093
  • References 1104
  • Xxxv Radiation and Anthocyanin Pigments 1109
  • Introduction 1109
  • Conclusion 1116
  • References 1118
  • XXXVI - Effects of Radiation on Bacteria 1119
  • References 1141
  • Xxxvii the Effects of Radiation on Enzymes 1151
  • References 1160
  • Xxxviii Induced Chromosomal Aberrations in Animals 1167
  • Introduction 1167
  • References 1202
  • Xxxix Radiation and the Study of Mutation in Animals 1209
  • Introduction 1209
  • References 1252
  • Xl Induced Mutations in Plants 1263
  • Introduction 1263
  • References 1278
  • Xli Induced Chromosomal Alterations 1281
  • References 1293
  • Xlii Induced Chromosomal Alterations in Maize 1297
  • References 1308
  • Xliii Biological Aspects of the Quantum Theory of Radiation Absorptions in Tissues 1311
  • References 1326
  • Subject Index 1331
  • Alphabetical List of Contributors 1343
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