• Dobzhansky-Muller interactions among individual genes, and chromosomal rearrangements causing problems with chromosome synapsis and recombination in meiosis, have both long been considered as major mechanisms behind intrinsic postzygotic isolation. (bvsalud.org)
  • Walter Sutton (left) and Theodor Boveri (right) independently developed the chromosome theory of inheritance in 1902. (wikipedia.org)
  • In his famous textbook The Cell in Development and Heredity , Wilson linked together the independent work of Boveri and Sutton (both around 1902) by naming the chromosome theory of inheritance the Boveri-Sutton chromosome theory (the names are sometimes reversed). (wikipedia.org)
  • [1] [2] These chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation . (wikipedia.org)
  • In 1944 it was realized that genetic transformation in bacteria was due to DNA and not protein and that DNA was the molecule responsible for heredity in genes and chromosomes [ 8 ]. (biomedcentral.com)
  • Since the genetic code was deciphered much has been learnt about the chromosome structure shared by all organisms from yeast to human. (biomedcentral.com)
  • Morgan, Sturtevant, Bridges and Muller constructed the first genetic linkage maps from recombination studies in crosses made in the fruit fly and from cytological preparations of its polytene salivary gland chromosomes [ 4 - 6 ]. (biomedcentral.com)
  • Using pulse-chase replication labeling and time-lapse microscopy, we found that the heterochromatic block enriched for macroH2A/H3K27me3 of the X chromosome is replicated during mid-S-phase, prior to the heterochromatic block enriched for H3K9me3/HP1 beta, which is replicated during late S-phase. (biomedcentral.com)
  • To test whether histone acetylation level regulates its replication dynamics, we induced either global hyperacetylation by pharmacological inhibition or by targeting a histone acetyltransferase to the heterochromatic region of the X chromosomes. (biomedcentral.com)
  • In conclusion, we mapped major epigenetic modifications controlling the structure of the sex chromosome-associated heterochromatin and demonstrated the occurrence of differences in the molecular mechanisms controlling the replication timing of the heterochromatic blocks at the sex chromosomes in female Microtus cabrerae cells. (biomedcentral.com)
  • The list of organisms by chromosome count describes ploidy or numbers of chromosomes in the cells of various plants, animals, protists, and other living organisms. (wikipedia.org)
  • Attention is paid to their length, the position of the centromeres, banding pattern, any differences between the sex chromosomes, and any other physical characteristics. (wikipedia.org)
  • Fusion of ancestral chromosomes left distinctive remnants of telomeres, and a vestigial centromere. (wikipedia.org)
  • [4] Before this happens, each chromosome is duplicated ( S phase ), and both copies are joined by a centromere , resulting either in an X-shaped structure (pictured above), if the centromere is located equatorially, or a two-arm structure, if the centromere is located distally. (wikipedia.org)
  • A chromosome is a long DNA molecule with part or all of the genetic material of an organism. (wikipedia.org)
  • For the genetic algorithm, see Chromosome (genetic algorithm) . (wikipedia.org)
  • Wilhelm Roux suggested that each chromosome carries a different genetic configuration , and Boveri was able to test and confirm this hypothesis. (wikipedia.org)
  • Genomic, transcriptomic, and metabolomic analyses together with lab experiments mimicking the two opposite environmental conditions suggest that diploid B. stacei populations have diverged sympatrically in two slopes characterized by distinct biomes at Evolution Canyon I (ECI), Mount Carmel, Israel. (bvsalud.org)
  • The review provides a brief account of the structure of somatic and meiotic chromosomes, stressing the high conservation of structure in plants and animals, with emphasis on aspects that require further research. (biomedcentral.com)
  • The future of molecular cytogenetics is likely to depend on a better knowledge of chromosome structure and function. (biomedcentral.com)
  • These studies reaffirmed that chromosome structure and behavior in somatic and germ cell divisions were common to all plants and animals. (biomedcentral.com)
  • One of the purposes of this review is to encourage research into chromosome structure as this could help advance molecular cytogenetics. (biomedcentral.com)
  • [5] In animal cells, chromosomes reach their highest compaction level in anaphase during chromosome segregation . (wikipedia.org)
  • Some use the term chromosome in a wider sense, to refer to the individualized portions of chromatin in cells, either visible or not under light microscopy. (wikipedia.org)
  • The mechanisms of transmission of both discontinuous and continuous characteristics across the generations were unknown before Mendel's laws were explained at the turn of the 20th Century by the behavior of chromosomes in germ cells [ 2 , 3 ]. (biomedcentral.com)
  • It shows 22 homologous autosomal chromosome pairs, both the female (XX) and male (XY) versions of the two sex chromosomes, as well as the mitochondrial genome (at bottom left). (wikipedia.org)
  • Theoretically, such transitions can happen on the same pair of sex chromosomes (homologous transition) or involve an autosome, which then becomes a new sex chromosome (heterologous transition). (nature.com)
  • With the possible exception of L. schreiberi, all the species of the family Lacertidae described to date appear to share homologous Z chromosomes, which date back to the last common ancestor of the whole group. (bvsalud.org)
  • Fusion of ancestral chromosomes left distinctive remnants of telomeres, and a vestigial centromere. (wikipedia.org)
  • either there was no chromosomal sex determination in the last common ancestor and both systems developed independently, or one lineage retained the ancestral sex chromosomes while in the other lineage a transition to the alternate system occurred. (nature.com)
  • Furthermore, we show that the multiple sex-chromosome system of the Pyrenean species of Iberolacerta originated from the fusion of the ancestral W chromosome with one of the shortest autosomes, and provide additional evidence of the fast evolution of DNA sequences linked to the W chromosome in Lacertini. (bvsalud.org)
  • As intriguing as these concepts are, empirical evidence for the evolution of new sex chromosome systems following hybridization is very scant because these events have happened in the evolutionary past and would be expected to take long time periods to complete. (nature.com)
  • We carried out comparative analyses of chromosome evolution in the congeneric species I. galani and I. bonnali, as well as in two other species of Lacertini (Lacerta schreiberi and Timon lepidus) whose sex chromosomes were also studied through comparative genomic hybridization. (bvsalud.org)
  • In both species, inverted DAPI karyotypes showed the same diploid number, 2n = 46, and hybridization of the (TTAGGG) n probe revealed interstitial telomeric sequences (ITSs) at the centromeres of almost all bi-armed chromosomes. (karger.com)
  • The introduction of FISH (fluorescence in situ hybridization) marked the beginning of a new era for the study of chromosome structure and function. (biosyn.com)
  • Sex chromosomes evolve from autosomes and are typically extremely conserved, not only among species but entire classes of organisms. (nature.com)
  • X chromosomes in Cervidae evolved through complex chromosomal rearrangements of conserved segments within the chromosome, changes in centromere position, heterochromatic variation, and X-autosomal translocations. (bvsalud.org)
  • To track chromosomal rearrangements during Cervidae evolution, we summarized new data, and compared them with available X chromosomal maps and chromosome level assemblies of other species. (bvsalud.org)
  • We show that chromosomal rearrangements on the X-chromosome in Cervidae occur at a higher frequency than in the entire Ruminantia lineage: the rate of rearrangements is 2 per 10 million years. (bvsalud.org)
  • The euchromatin conservatism was shown by comparative chromosome painting with stone marten probes in newly built maps of the sable and pine marten. (bvsalud.org)
  • We detected two types of cervine X chromosome-acrocentric and submetacentric. (bvsalud.org)
  • We provide conclusive evidence that L. schreiberi should no longer be considered an exception to this rule, and demonstrate that the loss of microchromosomes in Iberolacerta was produced by their fusion to a middle-sized chromosome. (bvsalud.org)
  • At the molecular level, the gene(s) determining sex might have changed their mode of action, e.g. from female to male determination, or a novel sex-determining (SD) gene might have arisen and taken over (SD turnover) in the evolving lineage. (nature.com)
  • Our results highlight the complexity of factors contributing to patterns observed in hybrid genomes, and we experimentally demonstrate that hybridisation can catalyze rapid evolution of a new sex chromosome. (nature.com)
  • The best-studied sex chromosome systems are ZW and XY, female and male heterogametic systems respectively. (nature.com)
  • As other non-human extant hominidae have 48 chromosomes it is believed that the human chromosome 2 is the result of the merging of two chromosomes. (wikipedia.org)
  • This would be expected to result in selection for alternative sex chromosome systems in lineages arising from a hybridisation event. (nature.com)
  • Based on Haldane's rule, one would expect that the heterogametic sex in hybrids tends to show greater inviability or sterility than the homogametic sex 18 and one proposed explanation for this is dominance theory 19 . (nature.com)