Recent molecular cytogenetic studies demonstrate that extensive centromere-telomere fusions are the main chromosomal rearrangements underlying the karyotypic evolution of extant muntjacs. Although the molecular mechan...Recent molecular cytogenetic studies demonstrate that extensive centromere-telomere fusions are the main chromosomal rearrangements underlying the karyotypic evolution of extant muntjacs. Although the molecular mechanism of tandem fusions remains unknown, satellite DNA is believed to have facilitated chromosome fusions by non-allelic homologous recombination. Previous studies detected non-random hybridization signals of cloned satellite DNA at the postulated fusion sites on the chromosomes in Indian and Chinese muntjacs. But the genomic distribution and organization of satellite DNAs in other muntjacs have not been investigated. In this study, we have isolated four satellite DNA clones （BMCS, BM700, BM 1.1 k and FM700） from the black muntjac （Muntiacus crinifrons） and Fea＇s muntjac （M. feae）, and hybridized these four clones onto chromosomes of four muntjac species （M. reevesi, M. crinifrons, M. gongshanenisis and M. feae）. Besides the predominant centromeric signals, non-random interstitial hybridization signals from satellite I and II DNA clones （BMC5, BM700 and FM700） were also observed on the arms of chromosomes of these four muntjacs. Our results provide additional support for the notion that the karyotypes of M. crinifrons, M. feae and M. gongshanensis have evolved from a 2n = 70 ancestral karyotype by a series of chromosome fusions.展开更多
Cell lineages of nematodes are completely known: the adult male of Caenorhabditis elegans contains 1031 somatic cells, the hermaphrodite 959, not one more, not one less;cell divisions are strictly deterministic (as in...Cell lineages of nematodes are completely known: the adult male of Caenorhabditis elegans contains 1031 somatic cells, the hermaphrodite 959, not one more, not one less;cell divisions are strictly deterministic (as in the great majority of invertebrates) but so far nothing is known about the mechanism used by cells to count precise numbers of divisions. In vertebrates, each species has its invariable deterministic numbers of somites, vertebrae, fingers, and teeth: counting the number of iterations is a widespread process in living beings;nonetheless, it remains an unanswered question and a great challenge in cell biology. This paper introduces a computational model to investigate the possible role of satellite DNA in counting cell divisions, showing how cells may operate under Boolean logic algebra. Satellite DNA, made up of repeated monomers and subject to high epigenetic methylation rates, is very similar to iterable sequences used in programming: just like in the “iteration protocol” of algorithms, the epigenetic machinery may run over linear tandem repeats (that hold cell-fate data), read and orderly mark one monomer per cell-cycle (cytosine methylation), keep track and transmit marks to descendant cells, sending information to cell-cycle regulators.展开更多
基金the grant from the National Natural Science Foundation of China (30270719)
文摘Recent molecular cytogenetic studies demonstrate that extensive centromere-telomere fusions are the main chromosomal rearrangements underlying the karyotypic evolution of extant muntjacs. Although the molecular mechanism of tandem fusions remains unknown, satellite DNA is believed to have facilitated chromosome fusions by non-allelic homologous recombination. Previous studies detected non-random hybridization signals of cloned satellite DNA at the postulated fusion sites on the chromosomes in Indian and Chinese muntjacs. But the genomic distribution and organization of satellite DNAs in other muntjacs have not been investigated. In this study, we have isolated four satellite DNA clones （BMCS, BM700, BM 1.1 k and FM700） from the black muntjac （Muntiacus crinifrons） and Fea＇s muntjac （M. feae）, and hybridized these four clones onto chromosomes of four muntjac species （M. reevesi, M. crinifrons, M. gongshanenisis and M. feae）. Besides the predominant centromeric signals, non-random interstitial hybridization signals from satellite I and II DNA clones （BMC5, BM700 and FM700） were also observed on the arms of chromosomes of these four muntjacs. Our results provide additional support for the notion that the karyotypes of M. crinifrons, M. feae and M. gongshanensis have evolved from a 2n = 70 ancestral karyotype by a series of chromosome fusions.
文摘Cell lineages of nematodes are completely known: the adult male of Caenorhabditis elegans contains 1031 somatic cells, the hermaphrodite 959, not one more, not one less;cell divisions are strictly deterministic (as in the great majority of invertebrates) but so far nothing is known about the mechanism used by cells to count precise numbers of divisions. In vertebrates, each species has its invariable deterministic numbers of somites, vertebrae, fingers, and teeth: counting the number of iterations is a widespread process in living beings;nonetheless, it remains an unanswered question and a great challenge in cell biology. This paper introduces a computational model to investigate the possible role of satellite DNA in counting cell divisions, showing how cells may operate under Boolean logic algebra. Satellite DNA, made up of repeated monomers and subject to high epigenetic methylation rates, is very similar to iterable sequences used in programming: just like in the “iteration protocol” of algorithms, the epigenetic machinery may run over linear tandem repeats (that hold cell-fate data), read and orderly mark one monomer per cell-cycle (cytosine methylation), keep track and transmit marks to descendant cells, sending information to cell-cycle regulators.
