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Chapter 42 : Control of Mobile DNA

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Abstract:

Transposons are almost invisible genetically. There are two reasons for this genetic invisibility. First, transposons and retrotransposons generally move at extremely low frequencies, and second, they participate in illegitimate recombination events at frequencies much lower than anticipated from homology. Transposons and retrotransposons comprise half or more of the maize genome. The major difference between the maize and sorghum regions is the presence of very large continuous blocks of retrotransposons in maize that are not present in sorghum. Importantly, no retrotransposons have been found in the corresponding flanking sequence in sorghum. Recent work in a wide variety of organisms has begun to reveal previously unsuspected, and often interconnected, mechanisms for monitoring both gene expression levels and gene redundancy. Moreover, it is becoming increasingly evident that such mechanisms are central to controlling the expression and transposition of mobile elements. The results of recent studies on the classical epigenetic phenomenon of R locus paramutation in maize have revealed that local endoreduplication of a chromosomal segment both triggers silencing and can render the endoreduplicated locus capable of silencing an active allele of the gene on a homolog. Although the successful constitution of a transposon from the recognition sequences used in immunoglobulin gene rearrangement and the RAG1 and RAG2 proteins was interpreted as evidence that the V(D)J recombination system evolved from an ancient mobile DNA element, the fact is that the critical components of a transposon and a site-specific rearrangement system are the same.

Citation: Fedoroff N. 2002. Control of Mobile DNA, p 997-1007. In Craig N, Craigie R, Gellert M, Lambowitz A (ed), Mobile DNA II. ASM Press, Washington, DC. doi: 10.1128/9781555817954.ch42

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DNA Transposons
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Chromosome Structure
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Neurospora crassa
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Saccharomyces cerevisiae
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References

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1. Anderson, R. P.,, and J. R. Roth. 1977. Tandem genetic duplications in phage and bacteria. Annu. Rev. Microbiol. 31: 473 505.
2. Bailey, J. A.,, L. Carrel,, A. Chakravarti,, and E. E. Eichler. 2000. Molecular evidence for a relationship between LINE- 1 elements and X chromosome inactivation: the Lyon repeat hypothesis. Proc. Natl. Acad. Sci. USA 97: 6634 6639.
3. Banks, J. A.,, and N. Fedoroff. 1989. Patterns of developmental and heritable change in methylation of the Suppressor- mutator transposable element. Dev. Genet. 10: 425 437.
4. Bass, B. L. 2000. Double-stranded RNA as a template for gene silencing. Cell 101: 235 238.
5. Bennett, M. D.,, J. B. Smith,, and J. S. Heslop-Harrison. 1982. Nuclear DNA amounts in angiosperms. Proc. R. Soc. Lond. Biol. Sci. 216: 179 199.
6. Bennetzen, J. L.,, P. San Miguel,, M. Chen,, A. Tikhonov,, M. Francki,, and Z. Avramova. 1998. Grass genomes. Proc. Natl. Acad. Sci. USA 95: 1975 1978.
7. Bennetzen, J. L.,, K. Schrick,, P. S. Springer,, W. E. Brown,, and P. SanMiguel. 1994. Active maize genes are unmodified and flanked by diverse classes of modified, highly repetitive DNA. Genome 37: 565 576.
8. Bingham, P. M. 1997. Cosuppression comes to the animals. Cell 90: 385 387.
9. Bird, A. P. 1995. Gene number, noise reduction and biological complexity. Trends Genet. 11: 94 100.
10. Bureau, T. E.,, P. C. Ronald,, and S. R. Wessler. 1996. A computer-based systematic survey reveals the predominance of small inverted-repeat elements in wild-type rice genes. Proc. Natl. Acad. Sci. USA 93: 8524 8529.
11. Bureau, T. E.,, and S. R. Wessler. 1992. Tourist: a large family of small inverted repeat elements frequently associated with maize genes. Plant Cell 4: 1283 1294.
12. Bureau, T. E.,, and S. R. Wessler. 1994. Mobile inverted-repeat elements of the Tourist family are associated with the genes of many cereal grasses. Proc. Natl. Acad. Sci. USA 91: 1411 1415.
13. Bureau, T. E.,, and S. R. Wessler. 1994. Stowaway: a new family of inverted repeat elements associated with the genes of both monocotyledonous and dicotyledonous plants. Plant Cell 6: 907 916.
14. Chandler, V. L.,, and V. Walbot. 1986. DNA modification of a maize transposable element correlates with loss of activity. Proc. Natl. Acad. Sci. USA 83: 1767 1771.
15. Clemens, J. C.,, C. A. Worby,, N. Simonson-Leff,, M. Muda,, T. Maehama,, B. A. Hemmings,, and J. E. Dixon. 2000. Use of double-stranded RNA interference in Drosophila cell lines to dissect signal transduction pathways. Proc. Natl. Acad.Sci. USA 97: 6499 6503.
16. Cogoni, C.,, J. T. Irelan,, M. Schumacher,, T. J. Schmidhauser,, E. U. Selker,, and G. Macino. 1996. Transgene silencing of the al-1 gene in vegetative cells of Neurospora is mediated by a cytoplasmic effector and does not depend on DNA-DNA interactions or DNA methylation. EMBO J. 15: 3153 3163.
17. Cogoni, C.,, and G. Macino. 1997. Isolation of quelling-defective ( qde) mutants impaired in posttranscriptional transgeneinduced gene silencing in Neurospora crassa. Proc. Natl. Acad. Sci. USA 94: 10233 10238.
18. Cogoni, C.,, and G. Macino. 1999. Gene silencing in Neurospora crassa requires a protein homologous to RNA-dependent RNA polymerase. Nature 399: 166 169.
19. Cogoni, C.,, and G. Macino. 1999. Posttranscriptional gene silencing in Neurospora by a RecQ DNA helicase. Science 286: 2342 2344.
20. Consonni, G.,, F. Geuna,, G. Gavazzi,, and C. Tonelli. 1993. Molecular homology among members of the R gene family in maize. Plant J. 3: 335 346.
21. Dang, V. D.,, M. J. Benedik,, K. Ekwall,, J. Choi,, R. C. Allshire,, and H. L. Levin. 1999. A new member of the Sin3 family of corepressors is essential for cell viability and required for retroelement propagation in fission yeast. Mol. Cell. Biol. 19: 2351 2365.
22. de Vries, H. 1905. Species and Varieties: Their Origin by Mutation. Open Court Publishing Co., Chicago, Ill.
23. Doolittle, W. F.,, and C. Sapienza. 1980. Selfish genes, the phenotype paradigm and genome evolution. Nature 284: 601 603.
24. Emerson, R. A. 1914. The inheritance of a recurring somatic variation in variegated ears of maize. Am. Nat. 48: 87 115.
25. Emerson, R. A. 1917. Genetical studies of variegated pericarp in maize. Genetics 2: 1 35.
26. Emerson, R. A. 1929. The frequency of somatic mutation in variegated pericarp of maize. Genetics 14: 488 511.
27. Engels, W. R. 1996. P elements in Drosophila. Curr. Top. Microbiol. Immunol. 204: 103 123.
28. Engels, W. R. 1997. Invasions of P elements. Genetics 145: 11 15.
29. Fedoroff, N., 1989. Maize transposable elements, p. 375 411. In M. M. Howe, and D. E. Berg (ed.), Mobile DNA. American Society for Microbiology, Washington, D.C.
30. Fedoroff, N.,, D. Furtek,, and O. Nelson. 1984. Cloning of the Bronze locus in maize by a simple and generalizable procedure using the transposable controlling element Ac. Proc. Natl. Acad. Sci. USA 81: 3825 3829.
31. Fedoroff, N.,, S. Wessler,, and M. Shure. 1983. Isolation of the transposable maize controlling elements Ac and Ds. Cell 35: 243 251.
32. Fedoroff, N. V., 1998. The discovery of transposable elements, p. 89 104. In S.-D. Kung, and S.-F. Yang (ed.), Discoveries in Plant Biology. World Scientific Publishing Co., Singapore.
33. Ferguson-Smith, A. C.,, H. Sasaki,, B. M. Cattanach,, and M. A. Surani. 1993. Parental-origin-specific epigenetic modification of the mouse H19 gene. Nature 362: 751 775.
34. Fire, A. 1999. RNA-triggered gene silencing. Trends Genet. 15: 358 363.
35. Fire, A.,, S. Xu,, M. K. Montgomery,, S. A. Kostas,, S. E. Driver,, and C. C. Mello. 1998. Potent and specific genetic interference by double-strandedRNAin Caenorhabditis elegans. Nature 391: 806 811.
36. Flavell, A. J. 1992. Ty1-copia group retrotransposons and the evolution of retroelements in the eukaryotes. Genetica 86: 203 214.
37. Furner, I. J.,, M. A. Sheikh,, and C. E. Collett. 1998. Gene silencing and homology-dependent gene silencing in Arabidopsis: genetic modifiers and DNA methylation. Genetics 149: 651 662.
38. Gale, M. D.,, and K. M. Devos. 1998. Plant comparative genetics after 10 years. Science 282: 656 659.
39. Garrick, D.,, S. Fiering,, D. I. Martin,, and E. Whitelaw. 1998. Repeat-induced gene silencing in mammals. Nat. Genet. 18: 56 59.
40. Goldschmidt, R. 1938. Physiological Genetics. McGraw-Hill, New York, N.Y.
41. Gorbunova, V.,, and A. A. Levy. 1997. Non-homologous DNA end joining in plant cells is associated with deletions and filler DNA insertions. Nucleic Acids Res. 25: 4650 4657.
42. Hamilton, A. J.,, and D. C. Baulcombe. 1999. A species of small antisense RNA in posttranscriptional gene silencing in plants. Science 286: 950 952.
43. Hammond, S. M.,, E. Bernstein,, D. Beach,, and G. J. Hannon. 2000. An RNA-directed nuclease mediates post-transcriptional gene silencing in Drosophila cells. Nature 404: 293 296.
44. Heard, E.,, P. Clerc,, and P. Avner. 1997. X-chromosome inactivation in mammals. Annu. Rev. Genet. 31: 571 610.
45. Henikoff, S. 1998. Conspiracy of silence among repeated transgenes. Bioessays 20: 532 535.
46. Henikoff, S.,, and P. M. Meneely. 1993. Unwinding dosage compensation Cell 72: 1 2.
47. Hiom, K.,, M. Melek,, and M. Gellert. 1998. DNA transposition by the RAG1 and RAG2 proteins: a possible source of oncogenic translocations. Cell 94: 463 470.
48. Hirochika, H.,, H. Okamoto,, and T. Kakutani. 2000. Silencing of retrotransposons in Arabidopsis and reactivation by the ddm1 mutation. Plant Cell 12: 357 369.
49. Hollick, J. B.,, J. E. Dorweiller,, and V. L. Chandler. 1997. Paramutation and related allelic interactions. Trends Genet. 13: 302 308.
50. Hunter, C. P. 1999. Genetics: a touch of elegance with RNAi. Curr. Biol. 9: R440 R442.
51. Hunter, C. P. 2000. Gene silencing: shrinking the black box of RNAi. Curr. Biol. 10: R137 R140.
52. Jakowitsch, J.,, I. Papp,, E. A. Moscone,, J. van der Winden,, M. Matzke,, and A. J. Matzke. 1999. Molecular and cytogenetic characterization of a transgene locus that induces silencing and methylation of homologous promoters in trans. Plant J. 17: 131 140.
53. Jeddeloh, J. A.,, J. Bender,, and E. J. Richards. 1998. The DNA methylation locus DDM1 is required for maintenance of gene silencing in Arabidopsis. Genes Dev. 12: 1714 1725.
54. Jeddeloh, J. A.,, T. L. Stokes,, and E. J. Richards. 1999. Maintenance of genomic methylation requires a SWI2/SNF2-like protein. Nat. Genet. 22: 94 97.
55. Jensen, S.,, L. Cavarec,, M. P. Gassama,, and T. Heidmann. 1995. Defective I elements introduced into Drosophila as transgenes can regulate reactivity and prevent I-R hybrid dysgenesis. Mol. Gen. Genet. 248: 381 390.
56. Jensen, S.,, M.-P. Gassama,, and T. Heidmann. 1999. Taming of transposable elements by homology-dependent gene silencing. Nat. Genet. 21: 209 215.
57. Jones, A. L.,, C. L. Thomas,, and A. J. Maule. 1998. De novo methylation and co-suppression induced by a cytoplasmically replicating plant RNA virus. EMBO J. 17: 6385 6393.
58. Jones, L.,, A. J. Hamilton,, O. Voinnet,, C. L. Thomas,, A. J. Maule,, and D. C. Baulcombe. 1999. RNA-DNA interactions and DNA methylation in post-transcriptional gene silencing. Plant Cell 11: 2291 2302.
59. Kang, X. L.,, F. Yadao,, R. D. Gietz,, and B. A. Kunz. 1992. Elimination of the yeast RAD6 ubiquitin conjugase enhances base-pair transitions and G.C----T.A transversions as well as transposition of the Ty element: implications for the control of spontaneous mutation. Genetics 130: 285 294.
60. Keller, B.,, and C. Feuillet. 2000. Colinearity and gene density in grass genomes. Trends Plant Sci. 5: 246 251.
61. Kelley, R. L.,, V. H. Meller,, P. R. Gordadze,, G. Roman,, R. L. Davis,, and M. I. Kuroda. 1999. Epigenetic spreading of the Drosophila dosage compensation complex from roX RNA genes into flanking chromatin. Cell 98: 513 522.
62. Kennerdell, J. R.,, and R. W. Carthew. 1998. Use of dsRNAmediated genetic interference to demonstrate that frizzled and frizzled 2 act in the wingless pathway. Cell 95: 1017 1026.
63. Kermicle, J. L.,, W. B. Eggleston,, and M. Alleman. 1995. Organization of paramutagenicity in R-stippled maize. Genetics 141: 361 372.
64. Ketting, R. F.,, H. A. Haverkamp,, H. G. A. M. van Luenen,, and R. H. A. Plasterk. 1999. mut-7 of C. elegans required for transposon silencing and RNA interference, is a homolog of Werner syndrome helicase and RNaseD. Cell 99: 133 141.
65. Ketting, R. F.,, and R. H. Plasterk. 2000. A genetic link between co-suppression and RNA interference in C. elegans. Nature 404: 296 298.
66. Koch, A. L. 1979. Selection and recombination in populations containing tandem multiple genes. J. Mol. Evol. 14: 273 285.
67. Kooter, J. M.,, M. A. Matzke,, and P. Meyer. 1999. Listening to the silent genes: transgene silencing, gene regulation and pathogen control. Trends Plant Sci. 4: 340 347.
68. Kricker, M. C.,, J. W. Drake,, and M. Radman. 1992. Duplication- targetedDNAmethylation and mutagenesis in the evolution of eukaryotic chromosomes. Proc. Natl. Acad. Sci. USA 89: 1075 1079.
69. Lagercrantz, U. 1998. Comparative mapping between Arabidopsis thaliana and Brassica nigra indicates that Brassica genomes have evolved through extensive genome replication accompanied by chromosome fusions and frequent rearrangements. Genetics 150: 1217 1228.
70. Lahn, B. T.,, and D. C. Page. 1999. Four evolutionary strata on the human X chromosome. Science 286: 964 967.
71. Lahn, B. T.,, and D. C. Page. 1999. Retroposition of autosomal mRNA yielded testis-specific gene family on human Y choromosome. Nat. Genet. 21: 429 433.
72. Liang, F.,, M. Han,, P. J. Romanienko,, and M. Jasin. 1998. Homology-directed repair is a major double-strand break repair pathway in mammalian cells. Proc. Natl. Acad. Sci. USA 95: 5172 5177.
73. Lohmann, J. U.,, I. Endl,, and T. C. Bosch. 1999. Silencing of developmental genes in Hydra. Dev. Biol. 214: 211 214.
74. Ludwig, S. R.,, L. F. Habera,, S. L. Dellaporta,, and S. R. Wessler. 1989. Lc, a member of the maize R gene family responsible for tissue-specific anthocyanin production, encodes a protein similar to transcriptional activators and contains the mychomology region. Proc. Natl. Acad. Sci. USA 86: 7092 7096.
75. Luff, B.,, L. Pawlowski,, and J. Bender. 1999. An inverted repeat triggers cytosine methylation of identical sequences in Arabidopsis. Mol. Cell 3: 505 511.
76. Lyon, M. F. 1993. Epigenetic inheritance in mammals. Trends Genet. 9: 123 128.
77. Lyon, M. F. 1998. X-chromosome inactivation: a repeat hypothesis. Cytogenet. Cell. Genet. 80: 133 137.
78. Maloisel, L.,, and J. L. Rossignol. 1998. Suppression of crossing- over by DNA methylation in Ascobolus. Genes Dev. 12: 1381 1389.
79. Martienssen, R. 1996. Epigenetic phenomena: paramutation and gene silencing in plants. Curr. Biol. 6: 810 813.
80. Martienssen, R.,, and V. Irish. 1999. Copying out our ABCs: the role of gene redundancy in interpreting genetic hierarchies. Trends Genet. 15: 435 437.
81. Masson, P.,, R. Surosky,, J. A. Kingsbury,, and N. V. Fedoroff. 1987. Genetic and molecular analysis of the Spm-dependent a-m2 alleles of the maize a locus. Genetics 117: 117 137.
82. Matzke, A. J.,, F. Neuhuber,, Y. D. Park,, P. F. Ambros,, and M. A. Matzke. 1994. Homology-dependent gene silencing in transgenic plants: epistatic silencing loci contain multiple copies of methylated transgenes. Mol. Gen. Genet. 244: 219 229.
83. McClintock, B. 1946. Maize genetics. Carnegie Inst. Wash. Year Book 45: 176 186.
84. McClintock, B. 1947. Cytogenetic studie of maize and Neurospora. Carnegie Inst. Wash. Year Book 46: 146 152.
85. McClintock, B. 1948. Mutable loci in maize. Carnegie Inst. Wash. Year Book 47: 155 169.
86. McClintock, B. 1949. Mutable loci in maize. Carnegie Inst. Wash Year Book 48: 142 154.
87. McClintock, B. 1951. Mutable loci in maize. Carnegie Inst. Wash. Year Book 50: 174 181.
88. McClintock, B. 1954. Mutations in maize and chromosomal aberrations in Neurospora. Carnegie Inst. Wash. Year Book 53: 254 260.
89. McClintock, B. 1962. Topographical relations between elements of control systems in maize. Carnegie Inst. Wash. Year Book 61: 448 461.
90. McClintock, B. 1978. Mechanisms that rapidly reorganize the genome. Stadler Genet. Symp. 10: 25 48.
91. McClintock, B. 1987>. The Discovery and Characterization of Transposable Elements. Garland Publishing, Inc., New York, N.Y.
92. Michelmore, R. W.,, and B. C. Meyers. 1998. Clusters of resistance genes in plants evolve by divergent selection and a birth-and-death process. Genome Res. 8: 1113 1130.
93. Misquitta, L.,, and B. M. Paterson. 1999. Targeted disruption of gene function in Drosophila by RNA interference (RNAi): a role for nautilus in embryonic somatic muscle formation. Proc. Natl. Acad. Sci. USA 96: 1451 1456.
94. Mittelsten Scheid, O.,, K. Afsar,, and J. Paszkowski. 1998. Release of epigenetic gene silencing by trans-acting mutations in Arabidopsis. Proc. Natl. Acad. Sci. USA 95: 632 637.
95. Montgomery, M. K.,, S. Xu,, and A. Fire. 1998. RNA as a target of double-stranded RNA-mediated genetic interference in Caenorhabditis elegans. Proc. Natl. Acad. Sci. USA 95: 15502 15507.
96. Morita, M.,, A. Umemoto,, H. Watanabe,, N. Nakazono,, and Y. Sugino. 1999. Generation of new transposons in vivo: an evolutionary role for the ‘‘staggered’’ head-to-head dimer and one-ended transposition. Mol. Gen. Genet. 261: 953 957.
97. Ngo, H.,, C. Tschudi,, K. Gull,, and E. Ullu. 1998. Double-stranded RNA induces mRNA degradation in Trypanosoma brucei. Proc. Natl. Acad. Sci. USA 95: 14687 14692.
98. Noma, K.,, E. Ohtsubo,, and H. Ohtsubo. 1999. Non-LTR retrotransposons (LINEs) as ubiquitous components of plant genomes. Mol. Gen. Genet. 261: 71 79.
99. Orgel, L. E.,, and F. H. C. Crick. 1980. Selfish DNA: the ultimate parasite. Nature 284: 604 607.
100. Pal-Bhadra, M.,, U. Bhadra,, and J. A. Birchler. 1997. Cosuppression in Drosophila: gene silencing of alcohol dehydrogenase by white-Adh transgenes is Polycomb dependent. Cell 90: 479 490.
101. Pal-Bhadra, M.,, U. Bhadra,, and J. A. Birchler. 1999. Cosuppression of nonhomologous transgenes in Drosophila involves mutually related endogenous sequences. Cell 99: 35 46.
102. Palauqui, J. C.,, T. Elmayan,, J. M. Pollien,, and H. Vaucheret. 1997. Systemic acquired silencing: transgene-specific posttranscriptional silencing is transmitted by grafting from silenced stocks to non-silenced scions. EMBO J. 16: 4738 4745.
103. Panning, B.,, and R. Jaenisch. 1998. RNA and the epigenetic regulation of X chromosome inactivation. Cell 93: 305 308.
104. Park, Y. D.,, I. Papp,, E. A. Moscone,, V. A. Iglesias,, H. Vaucheret,, A. J. Matzke,, and M. A. Matzke. 1996. Gene silencing mediated by promoter homology occurs at the level of transcription and results in meiotically heritable alterations in methylation and gene activity. Plant J. 9: 183 194.
105. Pereira, A.,, Z. Schwarz-Sommer,, A. Gierl,, I. Bertram,, P. A. Peterson,, and H. Saedler. 1985. Genetic and molecular analysis of the Enhancer (En) transposable element system of Zea mays. EMBO J. 4: 17 23.
106. Perelson, A. S.,, and G. I. Bell. 1977. Mathematical models for the evolution of multigene families by unequal crossing over. Nature 265: 304 310.
107. Perrot, G. H.,, and K. C. Cone. 1989. Nucleotide sequence of the maize R-S gene. Nucleic Acids Res. 17: 8003.
108. Petrov, D. A.,, and D. L. Hartl. 1998. High rate of DNA loss in the Drosophila melanogaster and Drosophila virilis species groups. Mol. Biol. Evol. 15: 293 302.
109. Pirrotta, V. 1997. Chromatin-silencing mechanisms in Drosophila maintain patterns of gene expression. Trends Genet. 13: 314 318.
110. Purugganan, M. D.,, and S. R. Wessler. 1994. Molecular evolution of magellan, a maize Ty3/ gypsy-like retrotransposon. Proc. Natl. Acad. Sci. USA 91: 11674 11678.
111. Qian, Z.,, H. Huang,, J. Y. Hong,, C. L. Burck,, S. D. Johnston,, J. Berman,, A. Carol,, and S. W. Liebman. 1998. Yeast Ty1 retrotransposition is stimulated by a synergistic interaction between mutations in chromatin assembly factor I and histone regulatory proteins. Mol. Cell. Biol. 18: 4783 4792.
112. Rabinowicz, P. D.,, E. L. Braun,, A. D. Wolfe,, B. Bowen,, and E. Grotewold. 1999. Maize R2R3 Myb genes: sequence analysis reveals amplification in the higher plants. Genetics 153: 427 444.
113. Radman, M. 1991. Avoidance of inter-repeat recombination by sequence divergence and a mechanism of neutral evolution. Biochimie 73: 357 361.
114. Reik, W.,, and J. Walter. 1998. Imprinting mechanisms in mammals Curr. Opin. Genet. Dev. 8: 154 164.
115. Rhoades, M. M. 1936. The effect of varying gene dosage on aleurone colour in maize. J. Genet. 33: 347 354.
116. Rhoades, M. M. 1938. Effect of the Dt gene on the mutability of the a1 allele in maize. Genetics 23: 377 397.
117. Riechmann, J. L.,, and E. M. Meyerowitz. 1998. The AP2/ EREBP family of plant transcription factors. Biol. Chem. 379: 633 646.
118. Rio, D. C. 1991. Regulation of Drosophila P element transposition. Trends Genet. 7: 282 287.
119. Romero, D.,, and R. Palacios. 1997. Gene amplification and genome plasticity in prokaryotes. Annu. Rev. Genet. 31: 91 111.
120. Rossignol, J. L.,, and G. Faugeron. 1994. Gene inactivation triggered by recognition between DNA repeats. Experientia 50: 307 317.
121. Rossignol, J. L.,, and G. Faugeron. 1995. MIP: an epigenetic gene silencing process in Ascobolus immersus. Curr. Top. Microbiol. Immunol. 197: 179 191.
122. Sanchez Alvarado, A., and P. A. Newmark. 1999. Doublestranded RNA specifically disrupts gene expression during planarian regeneration. Proc. Natl. Acad. Sci. USA 96: 5049 5054.
123. SanMiguel, P.,, B. S. Gaut,, A. Tikhonov,, Y. Nakajima,, and J. L. Bennetzen. 1998. The paleontology of intergene retrotransposons of maize. Nat. Genet. 20: 43 45.
124. SanMiguel, P.,, A. Tikhonov,, Y. K. Jin,, N. Motchoulskaia,, D. Zakharov,, A. Melake-Berhan,, P. S. Springer,, K. J. Edwards,, M. Lee,, Z. Avramova,, and J. L. Bennetzen. 1996. Nested retrotransposons in the intergenic regions of the maize genome. Science 274: 765 768.
125. Saxena, R.,, L. G. Brown,, T. Hawkins,, R. K. Alagappan,, H. Skaletsky,, M. P. Reeve,, R. Reijo,, S. Rozen,, M. B. Dinulos,, C. M. Disteche,, and D. C. Page. 1996. The DAZ gene cluster on the human Y chromosome arose from an autosomal gene that was transposed, repeatedly amplified and pruned. Nat. Genet. 14: 292 299.
126. Schiebel, W.,, T. Pelissier,, L. Riedel,, S. Thalmeir,, R. Schiebel,, D. Kempe,, F. Lottspeich,, H. L. Sanger,, and M. Wassenegger. 1998. Isolation of an RNA-directedRNApolymerase-specific cDNA clone from tomato. Plant Cell 10: 2087 2101.
127. Schwartz, A.,, D. C. Chan,, L. G. Brown,, R. Alagappan,, D. Pettay,, C. Disteche,, B. McGillivray,, A. de la Chapelle,, and D. C. Page. 1998. Reconstructing hominid Y evolution: Xhomologous block, created by X-Y transposition, was disrupted by Yp inversion through LINE-LINE recombination. Hum. Mol. Genet. 7: 1 11.
128. Schwartz-Sommer, Z.,, L. Leclercq,, E. Gobel,, and H. Saedler. 1987. CIN4, an insert altering the structure of the A1 gene in Zea mays, exhibits properties of nonviral retrotransposons. EMBO J. 6: 3873 3880.
129. Selker, E. U. 1997. Epigenetic phenomena in filamentous fungi: useful paradigms or repeat-induced confusion? Trends Genet. 13: 296 301.
130. Selker, E. U. 1999. Gene silencing: repeats that count. Cell 97: 157 160.
131. Selker, E. U.,, and P. W. Garrett. 1988. DNA sequence duplications trigger gene inactivation in Neurospora crassa. Proc. Natl. Acad. Sci. USA 85: 6870 6874.
132. Shepherd, N. S.,, Z. Schwarz-Sommer,, J. Blumberg vel Spalve,, M. Gupta,, U. Wienand,, and H. Saedler. 1984. Similarity of the Cin1 repetitive family of Zea mays to eukaryotic transposable elements. Nature 307: 185 187.
133. Sherman, J. M.,, and L. Pillus. 1997. An uncertain silence. Trends Genet. 13: 308 313.
134. Smardon, A.,, J. M. Spoerke,, S. C. Stacey,, M. E. Klein,, N. Mackin,, and E. M. Maine. 2000. EGO-1 is related to RNAdirectedRNApolymerase and functions in germ-line development and RNA interference in C. elegans. Curr. Biol. 10: 169 178.
135. Spell, M. L.,, G. Baran,, and S. R. Wessler. 1988. An RFLP adjacent to the maize waxy gene has the structure of a transposable element. Mol. Gen. Genet. 211: 364 366.
136. Suoniemi, A.,, D. Schmidt,, and A. H. Schulman. 1997. BARE- 1 insertion site preferences and evolutionary conservation of RNA and cDNA processing sites. Genetica 100: 219 230.
137. Suoniemi, A.,, J. Tanskanen,, and A. H. Schulman. 1998. Gypsy-like retrotransposons are widespread in the plant kingdom. Plant J. 13: 699 705.
138. Tabara, H.,, M. Sarkissian,, W. G. Kelly,, J. Fleenor,, A. Grishok,, L. Timmons,, A. Fire,, and C. C. Mello. 1999. The rde- 1 gene, RNA interference and transposon silencing in C. elegans. Cell 99: 123 132.
139. Tanksley, S. D.,, R. Bernatzky,, N. L. Lapitan,, and J. P. Prince. 1988. Conservation of gene repertoire but not gene order in pepper and tomato. Proc. Natl. Acad. Sci. USA 85: 6419 6423.
140. Tanksley, S. D.,, M. W. Ganal,, J. P. Prince,, M. C. de Vicente,, M. W. Bonierbale,, P. Broun,, T. M. Fulton,, J. J. Giovannoni,, S. Grandillo,, G. B. Martin, et al. 1992. High density molecular linkage maps of the tomato and potato genomes. Genetics 132: 1141 1160.
141. Tikhonov, A. P.,, P. J. SanMiguel,, Y. Nakajima,, N. M. Gorenstein,, J. L. Bennetzen,, and Z. Avramova. 1999. Colinearity and its exceptions in orthologous I regions of maize and sorghum. Proc. Natl. Acad. Sci. USA 96: 7409 7414.
142. Timmons, L.,, and A. Fire. 1998. Specific interference by ingested dsRNA. Nature 395: 854.
143. Tuschl, T.,, P. D. Zamore,, R. Lehmann,, D. P. Bartel,, and P. A. Sharp. 1999. Targeted mRNA degradation by doublestranded RNA in vitro. Genes Dev. 13: 3191 3197.
144. Vaucheret, H.,, C. Beclin,, T. Elmayan,, F. Feuerbach,, C. Godon,, J. B. Morel,, P. Mourrain,, J. C. Palauqui,, and S. Vernhettes. 1998. Transgene-induced gene silencing in plants. Plant J. 16: 651 659.
145. Voinnet, O.,, P. Vain,, S. Angell,, and D. C. Baulcombe. 1998. Systemic spread of sequence-specific transgeneRNAdegradation in plants is initiated by localized introduction of ectopic promoterless DNA. Cell 95: 177 187.
146. Walker, E. L.,, T. P. Robbins,, T. E. Bureau,, J. Kermicle,, and S. L. Dellaporta. 1995. Transposon-mediated chromosomal rearrangements and gene duplications in the formation of the maize R-r complex. EMBO J. 14: 2350 2363.
147. Wargelius, A.,, S. Ellingsen,, and A. Fjose. 1999. Doublestranded RNA induces specific developmental defects in zebrafish embryos. Biochem. Biophys. Res. Commun. 263: 156 161.
148. Wassenegger, M.,, S. Heimes,, L. Riedel,, and H. L. Sanger. 1994. RNA-directed de novo methylation of genomic sequences in plants. Cell 76: 567 576.
149. Watson, J. D.,, and F. H. C. Crick. 1953. Molecular structure of nucleic acids. Nature 171: 737 738.
150. Wessler, S. R.,, T. E. Bureau,, and S. E. White. 1995. LTR-retrotransposons and MITEs: important players in the evolution of plant genomes. Curr. Opin. Genet. Dev. 5: 814 821.
151. White, S. E.,, L. F. Habera,, and S. R. Wessler. 1994. Retrotransposons in the flanking regions of normal plant genes: a role for copia-like elements in the evolution of gene structure and expression. Proc. Natl. Acad. Sci. USA 91: 11792 11796.
152. Wianny, F.,, and M. Zernicka-Goetz. 2000. Specific interference with gene function by double-stranded RNA in early mouse development. Nat. Cell Biol. 2: 70 75.
153. Yoder, J. A.,, C. P. Walsh,, and T. H. Bestor. 1997. Cytosine methylation and the ecology of intragenomic parasites. Trends Genet. 13: 335 340.
154. Zamore, P. D.,, T. Tuschl,, P. A. Sharp,, and D. P. Bartel. 2000. RNAi: double-stranded RNA directs the ATP-dependent cleavage of mRNA at 21 to 23 nucleotide intervals. Cell 101: 25 33.

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