• 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)
  • 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)
  • Since the genetic code was deciphered much has been learnt about the chromosome structure shared by all organisms from yeast to human. (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)
  • 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)
  • 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)
  • 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)
  • It is important to en- sure that the drainfield is installed with care to keep the porous pipe level, or at a very gradual downward slope away from the distribution box or pump chamber, according to specifications stipulated by public health officials. (top5binarybrokers.com)
  • 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)
  • Here, we show prominent epigenetic marks of the heterochromatic blocks in the giant sex chromosomes of female Microtus cabrerae cells. (biomedcentral.com)
  • We have harnessed single nucleotide polymorphisms (SNPs) to enable an Oligopaint-based method for visually distinguishing the maternal and paternal homologous chromosomes in Drosophila and human systems 3,5 . (pairing.org)
  • In diploid cells, homologous chromosomes occupy separate territories, but expression from genes located on either the paternal or maternal homolog is usually similar. (biomedcentral.com)
  • In order to facilitate future comparative gene mapping studies, computer-aided analysis of digitized metaphase chromosomes allowed development of a detailed Indian muntjac G-banded idiogram incorporating both ISCN-type nomenclature and quantitative estimates of the size of each band and position. (nih.gov)
  • Comparative chromosome painting in mammals: human and the Indian muntjac (Muntiacus muntjak vaginalis). (nih.gov)
  • 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)
  • 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)
  • 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)
  • Hybrids between different species might be expected to suffer deleterious incompatibilities because alleles from orthologous genes from different species may not interact well in hybrids, and if these genes are on the sex chromosomes and are recessive, the heterogametic sex is likely to suffer the most. (nature.com)
  • In mammals, one of the female X chromosomes and all imprinted genes are expressed exclusively from a single allele in somatic cells. (biomedcentral.com)
  • In contrast, X-linked genes are subject to silencing by X chromosome inactivation (XCI) on one of the two homologs in female somatic cells [ 2 ], and a subset of autosomal genes are subject to imprinting and expressed from either the paternal or maternal allele [ 3 ]. (biomedcentral.com)
  • Most recently, we developed and then applied a haplotype-resolved Hi-C approach (Ohm) to elucidate the structure of homologously paired somatic chromosomes in early Drosophila embryos and cultured Drosophila cells, observing at least two types of pairing (tight and loose) and a correlation between pairing and gene expression 14,15 . (pairing.org)
  • The heterochromatization of one of the X chromosomes in female somatic cells is initiated by the long non-coding RNA (lncRNA) Xist that coats the Xi in early embryogenesis and silences transcription by recruiting specific proteins that put in place repressive histone modifications such as tri-methylation of histone H3K27, ubiquitination of histone H2AK119, and de-acetylation [ 9 - 12 ]. (biomedcentral.com)
  • By applying a novel Hi-C method to map allelic chromatin contacts, we discover a specific bipartite organization of the mouse inactive X chromosome that probably plays an important role in maintenance of gene silencing. (biomedcentral.com)
  • One of the variant forms of a gene at a particular locus on a chromosome. (nih.gov)
  • 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)
  • 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)
  • We detected two types of cervine X chromosome-acrocentric and submetacentric. (bvsalud.org)
  • Most recently, we combined HOPs with super-resolution imaging to observe that the maternal and paternal homologs of at least one region of human chromosome 19 differ more from each other in terms of ellipticity when they are present in the same nucleus than would be expected at random 5 . (pairing.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)
  • OligoSTORM can reveal details of chromosome structure and organization that are not accessible via conventional microscopy. (pairing.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)
  • The best-studied sex chromosome systems are ZW and XY, female and male heterogametic systems respectively. (nature.com)
  • We find radically different conformations for the two female mouse X chromosomes. (biomedcentral.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)
  • Previous studies in hybrids detected multiple abnormalities of spermatogenesis and a high frequency of dissociation between the X and Y chromosomes at the meiotic prophase. (mdpi.com)
  • The remarkable diversity of sex determination mechanisms known in fish may be fuelled by exceptionally high rates of sex chromosome turnovers or transitions. (nature.com)
  • We demonstrate the types of rearrangements that may have underlined the variability of Cervidae X chromosomes. (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)
  • Approaches to visualize the 3D configuration of the whole nucleus and of entire chromosomes include Hi-C, a method to identify chromatin contacts within chromosomes (intrachromosomal) or between chromosomes (interchromosomal). (biomedcentral.com)
  • Anti-kinetochore staining for single laser, bivariate flow sorting of Indian muntjac chromosomes. (nih.gov)
  • This would be expected to result in selection for alternative sex chromosome systems in lineages arising from a hybridisation event. (nature.com)
  • Other "retro elements" are components of cell chromosomes that have been generated by intracellular events involving reverse transcription. (nih.gov)