@article{LamatschTrifonovSchoriesetal.2011,
  author    = {Lamatsch, D. K. and Trifonov, V. and Schories, S. and Epplen, J. T. and Schmid, M. and Schartl, M.},
  title     = {Isolation of a Cancer-Associated Microchromosome in the Sperm-Dependent Parthenogen Poecilia formosa},
  series = {Cytogenetic and Genome Research},
  volume    = {135},
  journal   = {Cytogenetic and Genome Research},
  number    = {2},
  issn      = {1424-8581},
  doi       = {10.1159/000331271},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196785},
  pages     = {135-142},
  year      = {2011},
  abstract  = {In the asexual all-female fish species Poecilia formosa, the Amazon molly, supernumerary chromosomes have frequently been found in both laboratory-reared and wild-caught individuals. While wild-caught individuals with B chromosomes are phenotypically indifferent from conspecifics, individuals carrying B chromosomes from recent introgression events in the laboratory show phenotypic changes. Former analyses showed that the expression of a pigment cell locus is associated with the presence of these B chromosomes. In addition, they contain a so far unidentified locus that confers a higher susceptibility to tumor formation in the presence of pigmentation pattern. Isolation by microdissection and hybridization to metaphase chromosomes revealed that they contain one or several sequences with similarity to a highly repetitive pericentromeric and subtelomeric sequence in A chromosomes. Isolation of one particular sequence by AFLP showed that the B chromosomes contain at least 1 copy of an A-chromosomal region which is highly conserved in the whole genus Poecilia, i.e. more than 5 million years old. We propose it to be a single copy sequence.},
  language  = {en}
}
@article{CamachoSchmidCabrero2011,
  author    = {Camacho, J.P.M. and Schmid, M. and Cabrero, J.},
  title     = {B Chromosomes and Sex in Animals},
  series = {Sexual Development},
  volume    = {5},
  journal   = {Sexual Development},
  number    = {3},
  issn      = {1661-5425},
  doi       = {10.1159/000324930},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196321},
  pages     = {155-166},
  year      = {2011},
  abstract  = {Supernumerary (B) chromosomes are dispensable elements found in many eukaryote genomes in addition to standard (A) chromosomes. In many respects, B chromosomes resemble sex chromosomes, so that a common ancestry for them has frequently been suggested. For instance, B chromosomes in grasshoppers, and other insects, show a pycnotic cycle of condensation-decondensation during meiosis remarkably similar to that of the X chromosome. In some cases, B chromosome size is even very similar to that of the X chromosome. These resemblances have led to suggest the X as the B ancestor in many cases. In addition, sex chromosome origin from B chromosomes has also been suggested. In this article, we review the existing evidence for both evolutionary pathways, as well as sex differences for B frequency at adult and embryo progeny levels, B chromosome effects or B chromosome transmission. In addition, we review cases found in the literature showing sex-ratio distortion associated with B chromosome presence, the most extreme case being the paternal sex ratio (PSR) chromosomes in some Hymenoptera. We finally analyse the possibility of B chromosome regularisation within the host genome and, as a consequence of it, whether B chromosomes can become regular members of the host genome.},
  language  = {en}
}