caa a22 4500 477089917 CHVBK 20180405111513.0 cr unu---uuuuu 170330e19960601xx s 000 0 eng 10.1007/BF02263684 doi (NATIONALLICENCE)springer-10.1007/BF02263684 Ribosomal DNA is frequently concentrated on only one X chromosome in permanently apomictic aphids, but this does not inhibit male determination [Elektronische Daten] [Roger Blackman, Jennifer Spence] The ribosomal DNA arrays in the nucleolar organizer regions (NORs) of aphids are generally located in a telomeric or subtelomeric position on the X chromosomes. In aphid populations or species that have lost the sexual part of their life cycle and become permanent apomicts, multiple rDNA copies are often concentrated on only one of the original X chromosomes. This situation has been found in apomictic members of three aphid subfamilies, although not as yet in the tribe Aphidini, which includes several permanent apomicts that are important pests. Some clonal cultures ofAcyrthosiphon pisum andMyzus persicae reared for many years in conditions that prolong apomixis and inhibit sexual reproduction also have their rDNA arrays concentrated on one X chromosome. A 50-year-old clone ofAphis fabae, however, still retains a pair of similar-sized rDNA arrays on its X chromosomes. Although pairing of the X chromosomes by their NORs during prophase of the maturation division seems to be required for determination of XO males in aphids, a clone ofA. pisum with one rDNA array was nevertheless able to produce males when subjected to appropriate environmental conditions. Rapid Science Publishers, 1996 aphid sex determination nationallicence apomixis nationallicence B chromosome nationallicence fluorescence in situ hybridization nationallicence ribosomal RNA gene nationallicence Blackman Roger Department of Entomology, The Natural History Museum, Cromwell Road, SW7 5BD, London, UK aut Spence Jennifer Department of Entomology, The Natural History Museum, Cromwell Road, SW7 5BD, London, UK aut Chromosome Research Kluwer Academic Publishers 4/4(1996-06-01), 314-320 0967-3849 4:4<314 1996 4 10577 https://doi.org/10.1007/BF02263684 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02263684 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Blackman Roger Department of Entomology, The Natural History Museum, Cromwell Road, SW7 5BD, London, UK aut NATIONALLICENCE 700 1- Spence Jennifer Department of Entomology, The Natural History Museum, Cromwell Road, SW7 5BD, London, UK aut NATIONALLICENCE 773 0- Chromosome Research Kluwer Academic Publishers 4/4(1996-06-01), 314-320 0967-3849 4:4<314 1996 4 10577 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer