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PubMedDate not supplied

Disparity in population differentiation of sex-linked and autosomal variation in sibling species of the Jaera albifrons (Isopoda) complex.

The genetic variation at four enzyme loci is described for 22 populations of three Jaera species--J. albifrons, J. ischiosetosa, and J. praehirsuta--in the J. albifrons complex (Crustacea, Isopoda) in Denmark. The variation at three of the loci is similar, with the allele frequency spectra close to each other in all three species. An evolutionary tree based on the variation at these three loci revealed that the populations from the different species are completely intermixed in the tree. This was supported by hierarchical F-statistics where the between-species component was zero. At a fourth locus, Gpi (glucose phosphate isomerase), the species differ substantially. This locus is sex linked in J. ischiosetosa, but in the two other species, J. albifrons and J. praehirsuta, it is either found on autosomes or is sex linked with a high recombination rate between the locus and the centromere. An evolutionary tree for this locus partitions the populations into separate groups and a hierarchical F-statistic has a between-species component of about 50%. The results are attributed to introgression with a higher rate for autosomes than for sex chromosomes.

Animals↗
PubMed2005

[Intratetrad mating and its genetic and evolutionary consequences].

Genetic characteristics of intratetrad mating, i.e., fusion of haploid products of one meiotic division, are considered. Upon intratetrad mating, the probability of homozygotization is lower than that upon self-fertilization, while heterozygosity at genes linked to the mating-type locus, which determines the possibility of cell fusion, is preserved. If the mating-type locus is linked to the centromere, the genome regions adjoining the centromeres of all chromosomes remain heterozygous. Intratetrad mating is characteristic of a number of fungi (Saccharomyces cerevisiae, Saccharomycodes ludwigii, Neurospora tetrasperma, Agaricus bisporus, Microbotrium violaceum, and others). Parthenogenetic reproduction in some insects also involves this type of fusion of nuclei. Intratetrad mating leads to the accumulation of haplolethals (i.e., lethals manifesting in haploid cells but not hindering their mating) in pericentric chromosome regions. Since heterozygosity increases viability of an organism, recombination has been suppressed during evolution in fungi characterized by intratetrad mating, which ensures heterozygosity of the most part of the genome.

Biological Evolution↗
PubMed1997

Are rice chromosomes components of a holocentric chromosome ancestor?

Comparative genomics reveals that cereal genomes are composed of similar genomic building blocks (linkage blocks). By stacking these blocks in a unique order, it is possible to construct a single ancestral 'chromosome' which can be cleaved to give the basic structure of the 56 different chromosomes found in wheat, rice, maize, sorghum, millet and sugarcane. The borders of linkage blocks are defined by cereal centromeric and telomeric sites. However, a number of studies have shown that telomeric heterochromatin has neocentromeric activity, implying that linkage blocks are in fact defined by centromeric-like sites with conserved sequences. The structure of the ancestral cereal genome thus resembles a holocentric chromosome, which is the chromosome structure shared by the closest relatives of the Gramineae, the Cypericeae and Juncaceae.

Biological Evolution↗
PubMed2002

Assessing genetic diversity of wheat ( Triticum aestivum L.) germplasm using microsatellite markers.

A set of 24 wheat microsatellite markers, representing at least one marker from each chromosome, was used for the assessment of genetic diversity in 998 accessions of hexaploid bread wheat ( Triticum aestivum L.) which originated from 68 countries of five continents. A total of 470 alleles were detected with an average allele number of 18.1 per locus. The highest number of alleles per locus was detected in the B genome with 19.9, compared to 17.4 and 16.5 for genomes A and D, respectively. The lowest allele number per locus among the seven homoeologous groups was observed in group 4. Greater genetic variation exists in the non-centromeric regions than in the centromeric regions of chromosomes. Allele numbers increased with the repeat number of the microsatellites used and their relative distance from the centromere, and was not dependent on the motif of microsatellites. Gene diversity was correlated with the number of alleles. Gene diversity according to Nei for the 26 microsatellite loci varied from 0.43 to 0.94 with an average of 0.77, and was 0.78, 0.81 and 0.73 for three genomes A, B and D, respectively. Alleles for each locus were present in regular two or three base-pair steps, indicating that the genetic variation during the wheat evolution occurred step by step in a continuous manner. In most cases, allele frequencies showed a normal distribution. Comparative analysis of microsatellite diversity among the eight geographical regions revealed that the accessions from the Near East and the Middle East exhibited more genetic diversity than those from the other regions. Greater diversity was found in Southeast Europe than in North and Southwest Europe. The present study also indicates that microsatellite markers permit the fast and high throughput fingerprinting of large numbers of accessions from a germplasm collection in order to assess genetic diversity.

Journal Article↗
PubMed2005

Unusual distribution pattern of telomeric repeats in the shrews Sorex araneus and Sorex granarius.

Sorex araneus and Sorex granarius are sibling species within the Sorex araneus group with karyotypes composed of almost identical chromosome arms. S. granarius has a largely acrocentric karyotype, while, in S. araneus, various of these acrocentrics have combined together by Robertsonian (Rb) fusions to form metacentrics, with the numbers and types of metacentrics differing between chromosomal races. Our studies on telomeric sequences in S. araneus and S. granarius revealed differences between chromosomes and between species. In S. araneus (the Novosibirsk race), hybridization signals were present on the telomeres of all the chromosomes after FISH with a PCR-generated telomeric probe. In addition, hybridization signals were observed at high frequencies in the pericentric regions of some but not all metacentrics formed by Rb fusion. There were fewer signals on those metacentrics formed earlier in the evolution of S. araneus. This suggests that S. araneus chromosomes retain at least some telomeric repeats during Rb fusion, but that these repeats are lost or modified over time. These results are critical for the interpretation of the well-studied hybrid zones between chromosomal races of S. araneus, given that Rb fission has been postulated in such hybrid zones and that the likelihood of Rb fission will relate to presence/absence of telomeric sequences at the centromeres of metacentrics. In S. granarius, there were strong signals at the proximal (centromeric) telomeres of the acrocentrics after FISH with a DNA telomeric probe. FISH with a PNA telomeric probe on S. granarius acrocentrics showed that the proximal telomeres were 213 kb on average, while the length of the distal telomeres was 3.8 kb on average. Two-colour FISH, using a telomeric DNA probe and a microdissected probe generated from the pericentric regions of the S. granarius chromosomes a and b, revealed regions on distinct chromatin fibres where telomeric and microdissected probes were colocalized or localized sequentially. The proximal telomeres of S. granarius are highly unusual both in their large size and their heterogeneous structure relative to the telomeres of other mammals.

Animals↗
PubMed1976

The chromosomal localisation of satellite DNA in Ptyas mucosus (Ophidia, Colubridae).

Ptyas mucosus male DNA has a repetitious DNA satellite (p = 1.700 g cm-3) constituting 5% of the haploid genome. In situ hybridisation of radioactive complementary RNA (cRNA) has revealed that satellite sequences are located in the centromeric region of one pair of macrochromosomes and in the terminal region of 8 pairs of microchromosomes. These regions are constitutively heterochromatic as revealed by C-banding. The possibility of involvement of satellite rich microchromosomes in nucleolus organisation is discussed.

Animals↗
PubMed1996

Progression of a myelodysplastic syndrome to pre-B acute lymphoblastic leukemia: a case report and cell lineage study.

The evolution of acute lymphoblastic leukemia from a myelodysplastic syndrome is a very uncommon event. We describe a 46-year-old man in whom refractory anemia with excess blasts (RAEB) evolved to a pre-B acute lymphocytic leukemia. Trisomy 8 was one of the cytogenetic abnormalities in the dysplastic clone and was detected in both peripheral blood and bone marrow smears of interphase cells by the fluorescence in situ hybridization (FISH) technique. Using a chromosome 8 centromeric specific DNA probe we identified the trisomy 8 to be present in lymphoblasts, erythroid precursors, myeloblasts, promyelocytes, myelocytes, metamyelocytes, granulocytes, and monocytes. Our case supports the hypothesis that in MDS the pluripotent precursor cell is affected, and we examine the potential role of FISH for the study and follow-up of some hematological diseases.

Antigens, Surface↗
PubMed1991

Applications of fluorescence in situ hybridization in biological dosimetry and detection of disease-specific chromosome aberrations.

Dual color FISH with whole chromosome and pan-centromere probes facilitates rapid detection of stable structural aberrations such as translocations. This approach should allow analysis of translocations for assessment of genetic damage at long times after exposure or as a result of chronic exposure during a long period of time. Multi-color FISH with locus specific probes allows assessment of the frequency of cells carrying specific aberrations known to be associated with tumorigenesis, analysis of the series of genetic changes that occur during tumor evolution and correlation between genotype and phenotype. The power of FISH for analysis of random and tumor related events will increase steadily as informative probes are developed during the course of the International Human Genome Project.

Chromosome Aberrations↗
PubMed2005

Molecular characterization of the pericentric inversion of chimpanzee chromosome 11 homologous to human chromosome 9.

In addition to the fusion of human chromosome 2, nine pericentric inversions are the most conspicuous karyotype differences between humans and chimpanzees. In this study we identified the breakpoint regions of the pericentric inversion of chimpanzee chromosome 11 (PTR 11) homologous to human chromosome 9 (HSA 9). The break in homology between PTR 11p and HSA 9p12 maps to pericentromeric segmental duplications, whereas the breakpoint region orthologous to 9q21.33 is located in intergenic single-copy sequences. Close to the inversion breakpoint in PTR 11q, large blocks of alpha satellites are located, which indicate the presence of the centromere. Since G-banding analysis and the comparative BAC analyses performed in this study imply that the inversion breaks occurred in the region homologous to HSA 9q21.33 and 9p12, but not within the centromere, the structure of PTR 11 cannot be explained by a single pericentric inversion. In addition to this pericentric inversion of PTR 11, further events like centromere repositioning or a second smaller inversion must be assumed to explain the structure of PTR 11 compared with HSA 9.

Animals↗
PubMed1980

Chromosome analysis of Schistosoma rodhaini (Trematoda: Schistosomatidae).

The chromosome number of Schistosoma rodhaini Brumpt is 2n=16, with apparent sexual dimorphism quantifiable in chromosome pair no. 2. A method for dissociating host tissue coupled with hypotonic treatment yields permanent mitotic chromosome spreads with very defined centromere regions. The karyotype of S. rodhaini is very similar to that of its sibling species, S. mansoni Sambon, except there is a pericentric inversion in the S. rodhaini nucleolar organizer chromosome pair, S. rodhaini does not have any satellited chromosomes, and S. rodhaini has slightly shorter short arms of the group I chromosomes than S. mansoni. This distinction of chromosomes of similar species of schistosomes will be important for field identification of parasites and in elucidating the evolution of the schistosomes.

Animals↗
PubMed2004

Isolation from the horse genome of a new DNA transposon belonging to the Tigger family.

Tigger elements are human DNA transposons homologous to the pogo element of Drosophila melanogaster. They contain an open reading frame for a transposase very similar to the major mammalian centromere protein CENP-B. We found in the horse genome a DNA element ( Ecatig3) sharing 88% homology with human Tigger3. The presence of Tigger elements in the horse genome confirms previous data that date these elements before the divergence between Perissodactyla and Primates (80-90 Myr ago). Copy number evaluation indicates that the horse element is much more abundant than its human counterpart. Southern blot analysis demonstrates that Ecatig3 elements are extremely homogeneous; this may indicate that the evolution of this DNA transposon has been driven by some kind of selection and has not been neutral.

Animals↗
PubMed1994

Clonality of combined testicular germ cell tumors of adults.

BACKGROUND: Recently we have shown, by combining in situ hybridization and immunohistochemistry, that carcinoma in situ (CIS) adjacent to seminoma (CIS/SE), like SE, usually contains three copies of the centromeric region of chromosome 15/tumor cell. In contrast, CIS adjacent to nonseminomatous testicular germ cell tumors of adults (CIS/NS), as well as NS itself, have two copies. EXPERIMENTAL DESIGN: In the present study we have used this approach to investigate the clonal origin of the SE and NS components of combined tumors (CTs). We counted the number of copies of chromosome 15 centromeric regions in tumor cell nuclei of the CIS, SE, and NS components of nine CTs. RESULTS: We show that the number of copies of centromeric regions of chromosome 15 in both the SE and the NS component, and the adjacent CIS of the same CT, may be high (SE-pattern) or low (NS-pattern). In two cases, the copy numbers were high in the SE component and its adjacent CIS, and low in the NS component and its adjacent CIS. CONCLUSIONS: The data suggest that in most CTs the SE and the NS components have a monoclonal origin, and that karyotype evolution in CIS and the invasive tumor is very similar.

Adult↗
PubMed2002

A plant-transformation-competent BIBAC library from the Arabidopsis thaliana Landsberg ecotype for functional and comparative genomics.

The genome of the model plant Arabidopsis thaliana has been sequenced to near completion. To facilitate experimental determination of the function of every gene in the species, we constructed a large-insert library from the Landsberg ecotype using a plant-transformation-competent binary BAC vector, BIBAC2. The library contains 11,520 clones with an estimated average insert size of 162 kb. Of a sample of 102 clones, 17.6% had no inserts; further, in the library as a whole, 287 clones contained chloroplast DNA, and 25 contained mitochondrial DNA. Thus it is estimated that 9,295 clones originated from the nuclear genome, representing a 11.5 x coverage. The library was further characterized by screening with probes corresponding to 180-bp repeats, 5S rDNA, 18S-25S rDNA and 23 single-copy RFLP markers. The results showed that 92 clones contained 180-bp centromeric repeats, 78 contained 5S rDNA and 95 contained 18S-25S rDNA, approximately 1%, 0.8% and 1%, respectively, of the nuclear clones in the library. Screening the library with the 23 RFLP markers showed that each one hybridized to an average of seven clones. This library is the first large-insert DNA library for the widely studied Landsberg erecta strain. It will greatly facilitate gene identification by complementation screening, and will enhance analysis of the structure, organization and evolution of the A. thaliana genome.

Arabidopsis↗
PubMed2003

Elucidation of correspondence between swine chromosome 4 and human chromosome 1 by assigning 27 genes to the ImpRH map, and development of microsatellites in the proximity of 14 genes.

Loci affecting swine intramuscular fat content, backfat thickness, carcass weight, and daily weight gain were assigned to regions of swine chromosome (SSC) 4, which were shown to correspond to human chromosome (HSA) 1p22--> q25 by ZOO-FISH, bidirectional chromosome painting, as well as by the linkage map of genes. In order to select candidate genes responsible for the above traits from the human genome database, precise correspondence between SSC4 and HSA1 is a prerequisite. In the present study, 27 genes, PTGFR, GBP1, GBP2, GFI1, GCLM, ABCD3, EXTL2, KCNA3, ADORA3, KCND3, WNT2B, NRAS, SYCP1, PTGFRN, IGSF2, NOTCH2, S100A10, SHC1, SSR2, LMNA, CCT3, CD5L, PEA15, FCER1G, EAT2, DDR2, and LAMB3, located in the HSA1 region corresponding to SSC4 or possibly SSC4, were assigned to the IMpRH map. The alignment of genes from centromere to telomere in the SSC4 q arm is basically conserved in HSA1p22-->q25 with the direction from the q arm to the p arm, which is in good agreement with results from linkage mapping. In addition, the present study first demonstrated that WNT2B residing in the middle of the HSA1 region was assigned to SSC18 with a high lod score (> 5), and that at least three intrachromosomal rearrangements occurred in the region in the process of swine and human evolution. PTGFR, and LAMB3 localized at both ends of the HSA1 region were assigned to SSC6 and SSC9, respectively, which is consistent with regional correspondence reported earlier. In the course of the above analysis, microsatellite markers were developed in the proximity of eleven genes localized on SSC4, and three genes on other swine chromosomes.

Animals↗
PubMed2005

A reciprocal translocation 46,XY,t(8;9)(p11.2;q13) in a bladder exstrophy patient disrupts CNTNAP3 and presents evidence of a pericentromeric duplication on chromosome 9.

A patient with sporadic bladder exstrophy and de novo apparently balanced chromosomal translocation 46,XY,t(8;9)(p11.2;q13) was analyzed by fluorescence in situ hybridization (FISH) and molecular methods. We were able to map both translocation breakpoints to single genomic clones. The chromosome 8p11.2 breakpoint was mapped to BAC clone RP4-547J18, predicted to contain several hypothetical genes. Characterization of the chromosome 9q13 breakpoint indicated a disruption in the 5' region of CNTNAP3 within BAC RP11-292B8. This observation suggests possible involvement of CNTNAP3 in the etiology of bladder exstrophy. Additionally, FISH analysis identified several genomic copies of CNTNAP3 on both sides of the chromosome 9 centromere flanking the polymorphic heterochromatin. Northern blot analysis of lymphoblast and bladder RNA confirmed CNTNAP3 transcripts in these tissues and did not show abnormal CNTNAP3 expression in the proband and two unrelated patients with bladder exstrophy. The identification of multiple copies of three BAC clones in the proband, his parents, and unrelated controls suggests that duplications of CNTNAP3 and the surrounding genomic region have occurred as a result of repeated events of unequal crossing over and pericentric inversions during chromosome 9 evolution.

Base Sequence↗
PubMed1999

A molecular cytogenetic analysis of the tribe Bovini (Artiodactyla: Bovidae: Bovinae) with an emphasis on sex chromosome morphology and NOR distribution.

Q-band comparisons were made among representative species of the four genera of the tribe Bovini (Bos, Bison, Bubalus, Syncerus) as well as to selected outgroup taxa representing the remaining two tribes of the subfamily Bovinae (nilgai, Boselaphini; eland, Tragelphini), the Bovidae subfamily Caprinae (domestic sheep) and the family Cervidae (sika deer and white-tailed deer). Extensive autosomal arm homologies were noted, but relatively few derivative character states were shared. Focus was then made on variation of the sex chromosomes and the chromosomal distribution of nucleolar organizer regions (NORs). Bovine BAC clones were used in molecular cytogenetic analyses to decipher rearrangements of the sex chromosomes, and a pocket gopher 28s ribosomal probe was used to map the chromosomal locations of nucleolar organizing regions (NORs). Some of the more noteworthy conclusions drawn from the comparative analysis were that: 1. The Bovidae ancestral X chromosome was probably acrocentric and similar to acrocentric X chromosomes of the Bovinae; 2. The domestic sheep acrocentric X is probably a derivative character state that unites non-Bovinae subfamilies; 3. Bos and Bison are united within the tribe Bovini by the presence of shared derivative submetacentric X chromosomes; 4. Sika and white-tailed deer X chromosomes differ by inversion from X chromosomes of the Bovinae; 5. The Bovini ancestral Y chromosome was probably a small acrocentric; 6. Bos taurus, B. gaurus and B. banteng share derivative metacentric Y chromosomes; 7. Syncerus and Bubalus are united by the acquisition of X-specific repetitive DNA sequence on their Y chromosomes; 8. Bovinae and Cervidae X chromosome centromere position varies without concomitant change in locus order. Preliminary data indicate that a knowledge of the chromosomal distribution of NORs among the Bovidae will prove to be phylogenetically informative.

Animals↗
PubMed1986

The 724 family of DNA sequences is interspersed about the pericentromeric regions of human acrocentric chromosomes.

We describe the organization of the complex, interspersed 724 family of DNA sequences that is distributed in multiple copies about the pericentromeric region of human acrocentric chromosomes. 724 family members were isolated using an efficient recombination-based assay for nucleotide sequence homology to screen a human genomic library. Eight related but distinct 724 family members were isolated that hybridized to a total of 20 different human-genomic EcoRI DNA fragments spanning 100,000 base pairs. In contrast with tandemly clustered satellite and ribosomal DNA sequences also located on the short arms of human acrocentric chromosomes, 724 family members are interspersed. No evidence for local interspersion or homology between 724 family members and ribosomal or satellite DNA sequences was found. Juxtaposition of the complex 724 family to the nucleolus organizer region was a recent event in primate evolution. The unique organization of 724 family members on each of the five human acrocentric chromosomes indicates that the 724 family continues to evolve within the human karyotype.

Base Composition↗
PubMed1994

Cloning and comparative mapping of recently evolved human chromosome 22-specific alpha satellite DNA.

We have isolated and characterized a new alphoid probe, named p190.22. Its chromosomal location was investigated using fluorescence in situ hybridization. Under high stringency conditions p190.22 recognizes specifically the centromere of chromosome 22. A chromosome 22-specific alphoid subset has been previously reported in the literature (p22/1:2.1). The partial sequence and the genomic organization comparison strongly suggests that they recognize distinct subsets both specific for chromosome 22. The comparative mapping of probes p190.22 and p22/1:2.1 on chimpanzee (PTR and PPA) and gorilla (GGO) chromosomes was investigated. The two probes showed different hybridization results. p190.22, in particular, did not show any hybridization signal in these three species, suggesting a recent evolution.

Animals↗