TY - JOUR
T1 - Higher-order genome organization in platypus and chicken sperm and repositioning of sex chromosomes during mammalian evolution
AU - Tsend-Ayush, Enkhjargal
AU - Dodge, Natasha
AU - Mohr, Julia
AU - Casey, Aaron
AU - Himmelbauer, Heinz
AU - Kremitzki, Colin L.
AU - Schatzkamer, Kyriena
AU - Graves, Tina
AU - Warren, Wesley C.
AU - Griützner, Frank
N1 - Funding Information:
Acknowledgments We are grateful to Megan Wright for excellent technical assistance and Felicia Paulraj for contributing data on chicken chromosome 16 and Prof. Russell Jones for support with the monotreme sample collection. We thank Glenrock Station and Macquarie Generation for providing facilities; Prof. Bill Breed for critically reading the manuscript; and Dr. Jack daSilva, Dr. Daniel Kortschak, and Prof. David Adelson for their help with the statistical analysis. The work was supported by the Australian Research Council Discovery Project and Fellowship schemes. Frank Grützner is an Australian Research Council Australian Research Fellow and Enkhjargal Tsend-Ayush is an Australian Research Council Postdoctoral Fellow.
PY - 2009
Y1 - 2009
N2 - In mammals, chromosomes occupy defined positions in sperm, whereas previous work in chicken showed random chromosome distribution. Monotremes (platypus and echidnas) are the most basal group of living mammals. They have elongated sperm like chicken and a complex sex chromosome system with homology to chicken sex chromosomes. We used platypus and chicken genomic clones to investigate genome organization in sperm. In chicken sperm, about half of the chromosomes investigated are organized non-randomly, whereas in platypus chromosome organization in sperm is almost entirely non-random. The use of genomic clones allowed us to determine chromosome orientation and chromatin compaction in sperm. We found that in both species chromosomes maintain orientation of chromosomes in sperm independent of random or non-random positioning along the sperm nucleus. The distance of loci correlated with the total length of sperm nuclei, suggesting that chromatin extension depends on sperm elongation. In platypus, most sex chromosomes cluster in the posterior region of the sperm nucleus, presumably the result of postmeiotic association of sex chromosomes. Chicken and platypus autosomes sharing homology with the human X chromosome located centrally in both species suggesting that this is the ancestral position. This suggests that in some therian mammals a more anterior position of the X chromosome has evolved independently.
AB - In mammals, chromosomes occupy defined positions in sperm, whereas previous work in chicken showed random chromosome distribution. Monotremes (platypus and echidnas) are the most basal group of living mammals. They have elongated sperm like chicken and a complex sex chromosome system with homology to chicken sex chromosomes. We used platypus and chicken genomic clones to investigate genome organization in sperm. In chicken sperm, about half of the chromosomes investigated are organized non-randomly, whereas in platypus chromosome organization in sperm is almost entirely non-random. The use of genomic clones allowed us to determine chromosome orientation and chromatin compaction in sperm. We found that in both species chromosomes maintain orientation of chromosomes in sperm independent of random or non-random positioning along the sperm nucleus. The distance of loci correlated with the total length of sperm nuclei, suggesting that chromatin extension depends on sperm elongation. In platypus, most sex chromosomes cluster in the posterior region of the sperm nucleus, presumably the result of postmeiotic association of sex chromosomes. Chicken and platypus autosomes sharing homology with the human X chromosome located centrally in both species suggesting that this is the ancestral position. This suggests that in some therian mammals a more anterior position of the X chromosome has evolved independently.
UR - http://www.scopus.com/inward/record.url?scp=58349104767&partnerID=8YFLogxK
U2 - 10.1007/s00412-008-0177-1
DO - 10.1007/s00412-008-0177-1
M3 - Article
C2 - 18726609
AN - SCOPUS:58349104767
SN - 0009-5915
VL - 118
SP - 53
EP - 69
JO - Chromosoma
JF - Chromosoma
IS - 1
ER -