Break Points in Human Chromosomes

Yu, Chunmei; Borgaonkar, Digamber S.; Bolling, David R.

doi:10.1159/000152960

Cited by 28 publications

(19 citation statements)

References 18 publications

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“…We also note that our proposal is consistent with studies of human chromosomes that show that breakpoints in human chromosomes occur preferentially in telomeres (Yu et al 1978;Stoll 1980) and in G+C-rich G-light regions (Aula and von Koskull 1976;Nakagome and Chiyo 1976;Stoll 1980;Abeysinghe et al 2003). The proposal may be valid for other genomes besides those of human and dog because double-stranded breaks are also known to occur predominantly in high G+C regions in the yeast Saccharomyces cerevisiae (Baudat and Nicolas 1997;Gerton et al 2000).…”

Section: Mutation Hotspots In Dog and Human Chromosomessupporting

confidence: 90%

Hotspots of mutation and breakage in dog and human chromosomes

Webber¹,

Ponting²

2005

Genome Res.

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Sequencing of the dog genome allows an investigation of the location-dependent evolutionary processes that occurred since the common ancestor of primates and carnivores, ∼95 million years ago. We investigated variations in G+C nucleotide fraction and synonymous nucleotide substitution rates (K s ) across dog and human genomes. Our results show that dog genes located either in subtelomeric and pericentromeric regions, or in short synteny blocks, possess significantly elevated G+C fraction and K s values. Human subtelomeric, but not pericentromeric, genes also exhibit these elevations. We then examined 1.048 Gb of human sequence that is likely not to have been located near a primate telomere at any time since the common ancestor of dog and human. We observed that regions of highest G+C or K s ("hotspots"; median sizes of 0.5 or 1.3 Mb, respectively) within this sequence were preferentially segregated to dog subtelomeres and pericentromeres during the rearrangements that eventually gave rise to the extant canine karyotype. Our data cannot be accounted for solely on the basis of gradually elevating G+C fractions in subtelomeric regions as a consequence of biased gene conversion. Rather, we propose that high G+C sequences are found preferentially within dog subtelomeres as a direct consequence of chromosomal fission occurring more frequently within regions elevated in G+C.

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Section: Mutation Hotspots In Dog and Human Chromosomessupporting

confidence: 90%

Hotspots of mutation and breakage in dog and human chromosomes

Webber¹,

Ponting²

2005

Genome Res.

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“…The differential incorporation of fissioned chromosomes in five families (Lepilemuridae, Daubentoniidae, Lemuridae, Cheirogaleidae, and Indridae) accounts for extant karyotypes of all living lemur species. A fission event in the proposed ancestral karyotype for all lemurs (2n ϭ 20) generated a diploid number range of [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. A secondary fission event in a karyologically polymorphic population (2n ϭ 34, which either includes one acrocentric pair or is comprised of all mediocentric autosomes) explains all karyotypes of Lemuridae (2n ϭ 44-62) and Cheirogaleidae (2n ϭ 46 and 66), respectively.…”

mentioning

confidence: 99%

“…However, if both chromatids have bipolar attachment in opposition to one another, double strand breaks will occur at weak points, which are likely to be at intercentromeric regions and have no deleterious effect on phenotype. Chromatin breakpoints are most frequently associated in the centromeric and telomeric regions at light G-bands areas (36). The de novo formation of stable fission-generated acrocentric derivatives of human chromosome 21 has no clinical significance, for example (37).…”

mentioning

confidence: 99%

Kinetochore reproduction in animal evolution: Cell biological explanation of karyotypic fission theory

Kolnicki

2000

Proc. Natl. Acad. Sci. U.S.A.

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Karyotypic fission theory of Todd offers an explanation for the diverse range of diploid numbers of many mammalian taxa. Theoretically, a full complement of acrocentric chromosomes can be introduced into a population by chromosomal fission. Subsequent inheritance of ancestral chromosomes and paired fission derivatives potentially generates a diploid range from the ancestral condition to double its number of chromosomes. Although it is undisputed that both chromosomal fission and fusion (''Robertsonian rearrangements'') have significantly contributed to karyological diversity, it is generally assumed that independent events, the fission of single chromosomes or the fusion of two chromosomes, are the sources of such change. The karyotypic fission idea by contrast posits that all mediocentric chromosomes simultaneously fission. Here I propose a specific cell biological mechanism for Todd's karyotypic fission concept, ''kinetochore reproduction theory,'' where a complete set of dicentric chromatids is synthesized during gametogenesis, and kinetochore protein dephosphorylation regulates dicentric chromatid segregation. Three postulates of kinetochore reproduction theory are: (i) breakage of dicentric chromosomes between centromere pairs forms acrocentric derivatives, (ii) de novo capping of newly synthesized acrocentric ends with telomeric DNA stabilizes these derivatives, and (iii) mitotic checkpoints regulate chromosomal disjunction to generate fissioned karyotypes. Subsequent chromosomal rearrangement, especially pericentric inversion, increases the probability of genetic isolation amongst incipient sympatric species polytypic for fissiongenerated acrocentric autosomes. This mechanism obviates the requirement for numerous independent Robertsonian rearrangements and neatly accounts for mammalian karyotype evolution as exemplified in analyses of Carnivora, Artiodactyla, and Primates.

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“…Chromosome 11 having a breakage point close to the one in the present translocation has recently been observed in a rcp(7q -; 1 lq +) ( GUSTAVSSON and SEITERGREN 1984). A preponderance of chromosome breakages in the centromere and telomere regions has also been observed in translocations of human chromosomes (Yu et al 1978), and concentrations of structural aberrations in certain chromosomes and chromosome segments have also been observed. Examples of the latter phenomenon are translocations between chromosomes 7 and 14 (ZECH and HAGLUND 1978).…”

Section: Discussionmentioning

confidence: 95%

“…Examples of the latter phenomenon are translocations between chromosomes 7 and 14 (ZECH and HAGLUND 1978). Several explanations have been put forward for the preference for certain chromosomes as well as chromosome segments ( Yu et al 1978) but none has provided conclusive answers to those questions.…”

Section: Discussionmentioning

confidence: 99%

Occurrence of two different reciprocal translocations in the same litter of domestic pigs

2008

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A translocation designated t(9p+;l Iq-) was found in a boar producing small litters but having a normal sexual behaviour and a normal semen picture. Investigation of one of his litters revealed, in addition to t(9p+;l lq-) in two individuals, another translocation designated rcp(lp-;Xq+) in all offspring. The latter translocation had been transmitted from the dam. Both translocations concerned greatly unequalsized chromosome segments but only rcp( lp-;8q+) could be demonstrated to be truly reciprocal. The breakages of both translocations had occurred in RBA-positive bands of telomeric and centromeric segments. These observations support the hypothesis that aberrations occur non-randomly in chromosomes and chromosome segments of the pig karyotype. Embryonic studies indicated that probably only one chromosomally unbalanced gametic product, dexfl l)t(9p+; 1 lq-), can survive implantation. The t(9p +; I Iq -) effected a reduced litter size of approximately 50 % in the proband and it was also assumed, although evidence was lacking, that rcp( lp-;8q+) implied impaired fertility for the carriers. Newborns had either normal or balanced heterozygous karyotype. Those boars demonstrated a normal sexual behaviour and a normal semen picture. The finding of translocations almost exclusively in the male sex is probably attributable to the fact that boars are more often used for extensive breeding work than are females, and fertility impairment is therefore more easily detected in the male sex.A boar with normal sexual behaviour and normal semen picture, yet producing small litters, demonstrated a chromosomal translocation designated t(9p+;Ilq-). When a litter sired by this boar was studied in order to obtain information about the heredity of t h e translocation, an additional translocation, rcp( Ip -;8q+) was found. 1964; LOCNISKARet al. 1976; HAGELTORNet Ell. 1976; The latter translocation had been transmitted from the dam. The present work describes the cytogenetic and hereditary features of the two translocations, their behaviour in male meiosis and their role in embryonic mortality and fertility. Materials and methodsThe pigs investigated were of the Swedish Yorkshire breed. The proband and his progeny available at the farm were studied, and so were the available dams of those litters. Two whole-brothers available at neighbouring farms were also studied. Blood samples were taken from a total of 8 adult animals and skin biopsies from 30 piglets. Embryos were recovered, measured and morphologically examined, from two gilts and one sow 21 days after mating with the proband.Cultures were set up in conventional ways. The lymphocytes were grown in medium RPMI 1640 plus 30 % foetal calf serum and stimulated with pokeweed (Grand Island). The skin biopsies and embryos were cut into small pieces, explanted in

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Break Points in Human Chromosomes

Cited by 28 publications

References 18 publications

Hotspots of mutation and breakage in dog and human chromosomes

Hotspots of mutation and breakage in dog and human chromosomes

Kinetochore reproduction in animal evolution: Cell biological explanation of karyotypic fission theory

Occurrence of two different reciprocal translocations in the same litter of domestic pigs

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