02600nam a2200205 a 450000100080000000500110000800800410001902200140006010000290007424501830010326000950028650001890038152017010057065000160227165300230228770000150231070000290232570000190235470000210237316546752023-07-24       2007    bl uuuu     u00u1 u    #d  a0967-38491 aAGUIAR-PERECIN, M. L. R.  aAnalysis of karyotype variability of tropical maize inbred lines and hybrids using FISH of tandemly repeated DNA sequences to identify somatic chromosomes.h[electronic resource]  aIn: Chomosome Research, Netherlands, v. 15, n. 2, p. 41 jul. 2007. Supplement. P.088c2007  aEdição do 16 INTERNATIONAL CHROMOSOME CONFERENCE, Abstracts...Amsterdam, ago. 2007. Editado por Hans de Jong, Hans Tanke and Paul Fransz. DOI: 10.1007/s10577  ISSN 0967-3849 em papel  aThe analysis of pachytene chromosomes has greatly contributed to maize cytogenetics. Recently, FISH procedures using repeated DNA sequences have been described and improved the identification of somatic chromosomes. Due to the polymorphism of knobs and repetitive DNA sequences, karyotype diversity is observed among varieties. Mitotic chromosome analysis is valuable for the screening of several individuals, and studies of evolution. We investigaded root-tip chromosomes of inbred lines and hybrids, derived from a tropical variety (Cateto races), using the following sequences as probes: subtelomeric 4-12-1 clone (PNAS 101, 13555), knob 180-bp sequence, 5S rDNA, centromeric satellite 4 (Cent 4). Pachytene chromosomes and C-banded mitotic metaphases were previously analysed, and except for chromosomes 2, 4 and 5, most chromosomes were distinguished by their length, arm ratio or presence of knobs. We identified chromosomes 2 and 4 using probes of 5S rDNA (2L) and Cent4, respectively, but their arm ratios were atypical. Signals of the 180-bp sequence were correspondent to knobs detected by C-banding, and additional small signals were found at 1S, 6S and 9S, located at arm tips, a feature also found in other varieties. The subtelomeric sequence was observed at 1S, 2S, 4SL, 5S, 8L. One line was crossed with KYS, an inbred extensively investigated, and the following observations shoul be emphasized: differences in the subtelomeric sequence signals; homologues (with different arm ratios) of chromosomes 2 and 4 formed normal bivalents at pachtytene. This aspect apparently provides evidence for epigenetic location of centromeres, a finding that has been observed in many organisms.  achromosomes  aMaize cytogenetics1 aMONDIN, M.1 aSANTOS-SEREJO, J. A. dos1 aVIDA, A. C. F.1 aMOLINA, S. C. M.