Homologous chromosome pairing and recombination are essential components of meiosis and sexual reproduction. The reshuffling of genetic material through breakage and reunion of chromatids ensure proper segregation of homologous chromosomes in reduction division and genetic diversity in the progeny. The advent of somatic cell nuclear transfer (SCNT) as a reproductive biotechnology for use in livestock industry has made it easy to bypass these vital steps. However, few studies have been carried out on the impact of SCNT on the reproductive characteristics of cloned animals and, none to date, on the meiotic processes in animals, which were created by circumventing meiosis. In an attempt to assess the impact of cloning by SCNT on the meiotic processes, we undertook an immunocytological comparison of recombination in normal and clone bulls using antibodies raised against the synaptonemal complex protein 3 (SCP3) to label the lateral elements and the mismatch repair protein 1 (MLH1) foci on bivalents as indicators of recombination events. Our studies involving five normal bulls of proven fertility, two SCNT-derived bulls, and four mature offspring of SCNT bulls showed that the mean number of crossing over per spermatocyte for normal bulls (42 ± 4 SD; ranging from 33 to 56), was not significantly different from that of SCNT-derived bulls (43 ± 5 SD; ranging from 35 to 56), and the offspring of SCNT-derived bulls (43 ± 5 SD; ranging from 37 to 58). It would appear that circumventing meiosis to produce these animals does not influence the meiotic processes revealed by MLH1 foci detected in spermatocytes.

Anderson LK, Reeves A, Webb LM, Ashley T: Distribution of crossing over on mouse synaptonemal complexes using immunofluorescent localization of MLH1 protein. Genetics 151:1569–1579 (1999).
Barlow AL, Hultén MA: Crossing over analysis at pachytene in man. Eur J Hum Genet 6:330–358 (1998).
Borts RH, Chambers SR, Abdullah MFF: The many faces of mismatch repair in meiosis. Mut Res 451:129–150 (2000).
Bronner CE, Baker SM, Morrison PT, Warren G, Smith LG, et al: Mutation in the DNA mismatch repair gene homologue hMLH1 is associated with hereditary non-polyposis colon cancer. Nature 368:258–261 (1994).
Collins A, Frezal J, Teague J, Morton NE: A metric map of humans: 23 500 loci in 850 bands. Proc Natl Acad Sci USA 93:14771–14775 (1996).
Cooke HJ, Saunders PT: Mouse models of infertility. Nat Rev Genet 3:790–801 (2002).
Critchlow HM, Payne A, Griffin DK: Genes and proteins involved in the control of meiosis. Cytogenet Genome Res 105:4–10 (2004).
Daniels R, Hall V, Trounson AO: Analysis of gene transcription in bovine nuclear transfer embryos reconstructed with granulosa cell nuclei. Biol Reprod 63:1034–1040 (2000).
Dindot SV, Farin PW, Farin CE, Romano J, Walker S, et al: Epigenetic and genomic imprinting analysis in nuclear transfer derived Bos gaurus/Bos taurus hybrid fetuses. Biol Reprod 71:470–478 (2004).
Dunne LD, Diskin MG, Srenan JM: Embryo and fetal loss in beef heifers between day 14 of gestation and full term. Anim Reprod Sci 58:39–44 (2000).
Jagiello GM, Miller WA, Ducayen MB, Lin JS: Chiasma frequency and disjunctional behavior of ewe and cow oocytes matured in vitro. Biol Reprod 10:354–363 (1974).
Lawrie NM, Tease C, Hultén MA: Chiasma frequency, distribution and interference maps of mouse autosomes. Chromosoma 140:308–331 (1995).
Lynn A, Koehler KE, Judis L, Chan ER, Cherry JP, et al: Covariation of synaptonemal complex length and mammalian meiotic exchange rates. Science 296:2222–2225 (2002).
Lynn A, Ashley T, Hassold T: Variation in human meiotic recombination. Annu Rev Genomics Hum Genet 5:317–349 (2004).
Mann MR, Chung YG, Nolen LD, Verona RI, Latham KE, Artolomei MS: Disruption of imprinted gene methylation and expression in cloned preimplantation stage mouse embryos. Biol Reprod 69:902–914 (2003).
Moens P, Marcon E, Shore JS, Kockakpour N, Spyropoulous B: Initiation and resolution of interhomolog connections crossover and non-crossover sites along mouse synaptonemal complexes. J Cell Sci 120:1017–1027 (2007).
Page SL, Hawley RS: The genetics and molecular biology of the synaptonemal complex. Annu Rev Cell Dev Biol 20:525–558 (2004).
Pigozzi MI: Distribution of MLH1 foci on the synaptonemal complexes of chicken oocytes. Cytogenet Cell Genet 95:129–133 (2001).
Powell AM, Talbot NC, Wells KD, Kerr DE, Pursel VG, Wall RJ: Cell donor influences success of producing cattle by somatic cell nuclear transfer. Biol Reprod 71:210–216 (2004).
Rho GJ, Coppola G, Sosnowski J, Kasimanickam R, Johnson W, et al: Use of somatic cell nuclear transfer to study meiosis in female cattle carrying a sex-dependent fertility-impairing X-chromosome abnormality. Cloning Stem Cells 9:118–127 (2007).
Sandovici I, Kassovska-Bratinova S, Vaughan JE, Stewart R, Leppert M, Sapienza C: Human imprinted chromosomal regions are historical hot-spots of recombination. PLoS Genet 2:944–954 (2006).
Tease C, Hultén MA: Inter-sex variation in synaptonemal complex lengths largely determine the different recombination rates in male and female germ cells. Cytogenet Genome Res 107:208–215 (2004).
Tease C, Hartshorne GM, Hultén MA: Altered patterns of meiotic recombination in human fetal oocytes with asynapsis and/or synaptonemal complex fragmentation at pachytene. Reprod Biomed Online 13:88–95 (2006).
Topping D, Brown P, Judis L, Schwartz S, Seftel A, et al: Synaptic defects at meiosis I and non- obstructive azoospermia. Hum Reprod 20:3171–3177 (2006).
Wells DN, Forsyth JT, McMillan V, Oback B: The health of somatic cell cloned cattle and their offspring. Cloning Stem Cells 6:101–110 (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.