The B chromosome polymorphism in Spanish populations of the grasshopper, Eyprepocnemis plorans (Charpentier) is ancient and widespread. Meiocytes containing B chromosomes were analyzed in our laboratory using the 3F3/2 monoclonal antibody, which binds to a kinetochore phosphoepitope whose degree of phosphorylation is sensitive to tension applied to the kinetochore. Further, the tension created by the spindle at metaphase controls a checkpoint (the metaphase checkpoint) that allows the cell to begin anaphase when all chromosomes are aligned at the metaphase plate. Fluorescence patterns of the 3F3/2 phosphoepitope in cells containing B chromosomes were determined using confocal laser scanning microscopy. The phosphorylation pattern of kinetochores in these cells was shown to be different from that of cells without Bs. This suggests that the metaphase checkpoint has been modified in some way. We propose that B chromosomes in these grasshopper populations may have survived during evolution due to an alteration of the metaphase checkpoint, making it more permissive to the presence of misaligned chromosomes.   

1.
Ault JG: Stable versus unstable orientations of sex chromosomes in two grasshopper species. Chromosoma 93:298–304 (1986).
2.
Beukeboom LW: Bewildering Bs: an impression of the 1st B-Chromosome Conference. Heredity 73:328–336 (1994).
3.
Camacho JPM, Carballo AR, Cabrero J: The B-chromosome system of the grasshopper Eyprepocnemis plorans subsp. plorans (Charpentier). Chromosoma 80:163–176 (1980).
4.
Campbell MS, Gorbsky GJ: Microinjection of mitotic cells with the 3F3/2 anti-phosphoepitope antibody delays the onset of anaphase. J Cell Biol 129:1195–1204 (1995).
5.
Cyert MS, Scherson T, Kirschner MW: Monoclonal antibodies specific for thiophosphorylated proteins recognize Xenopus MPF. Dev Biol 129:209–216 (1988).
6.
Gorbsky GJ: Cell cycle progression and chromosome segregation in mammalian cells cultured in the presence of the topoisomerase II inhibitors ICRF-187 [(+)-1,2-bias(3,5-dioxopiperazinyl-u1)propane; ADR-529] and ICRF-159 (Razoxane). Cancer Res 54:1042–1048 (1994).
7.
Gorbsky GJ: Kinetochores, microtubules, and the metaphase checkpoint. Trends Cell Biol 5:143–148 (1995).
8.
Gorbsky GJ, Ricketts WA: Differential expression of a phosphoepitope at the kinetochores of moving chromosomes. J Cell Bio 122:1311–1321 (1993).
9.
Hartwell LH, Weinert TA: Checkpoints: controls that ensure the order of cell cycle events. Science 246:629–634 (1989).
10.
Henriques-Gil N, Arana P: Origin and substitution of B chromosomes in the grasshopper Eyprepocnemis plorans. Evolution 44:747–753 (1990).
11.
Henriques-Gil N, Santos JL, Arana P: Evolution of a complex B-chromosome polymorphism in the grasshopper Eyprepocnemis plorans. Chromosoma 89:290–298 (1984).
12.
Jones N, Houben A: B chromosomes in plants: escapees from the A chromosome genome? Trends Plant Sci 8:417–423 (2003).
13.
Jones RN, Rees H: B-chromosomes (Academic Press, New York 1982).
14.
Li X, Nicklas RB: Tension-sensitive kinetochore phosphorylation and the chromosome distribution checkpoint in praying mantid spermatocytes. J Cell Sci 110:537–545 (1997).
15.
Lopez-Leon MD, Cabrero J, Pardo MC, Visceras E, Camacho JPM, Santos JL: Generating high variability of B chromosomes in Eyprepocnemis plorans (grasshopper). Heredity 71:352–362 (1993).
16.
Nicklas RB, Arana P: Evolution and the meaning of metaphase. J Cell Sci 102:681–690 (1992).
17.
Nicklas RB, Brinkley BR, Pepper DA, Kubai DF, Richards GK: Electron microscopy of spermatocytes previously studied in life: methods and some observations on micromanipulated chromosomes. J Cell Sci 35:87–104 (1979).
18.
Nicklas RB, Ward SC, Gorbsky GS: Kinetochore chemistry is sensitive to tension and may link mitotic forces to a cell cycle checkpoint. J Cell Biol 130:929–939 (1995).
19.
Rebollo E, Arana P: A comparative study of orientation at behavior of univalent in living grasshopper spermatocytes. Chromosoma 104:56–67 (1995).
20.
Rebollo E, Martin S, Manzanero S, Arana P: Chromosomal strategies for adaptation to univalency. Chromosome Res 6:515–531 (1998).
21.
Rieder CL, Cole RW, Alexey K, Sluder G: The checkpoint delaying anaphase in response to chromosome monoorientation is mediated by an inhibitory signal produced by unattached kinetochores. J Cell Biol 130:941–948 (1995).
22.
Wise D, Brinkley BR: Mitosis in cells with unreplicated genomes (MUGs): spindle assembly and behavior of centromere fragments. Cell Motil Cytoskel 36:291–302 (1997).
© 2004 S. Karger AG, Basel
2004
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.