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PubMed1982

Chromosomal evolution in allopatric populations of the Odontophrynus occidentalis group (Amphibia, Anura) from western Argentina.

A karyological study of some populations of the Odontophrynus occidentalis group (2n = 22) from Argentina is reported. Ammoniacal silver (Ag-AS) and alkaline Giemsa (CBG) staining have been performed on specimens from La Rioja, Mendoza, Malargue, Tamelen, Tapiluque, Valcheta, and Meseta de Somuncura. All populations showed active ribosomal cistrons (NORs) on chromosome 11. Some metaphases of three specimens from Mendoza and five from La Rioja also showed bands on 9. Centromeric and telomeric C-bands were common to all populations, and a block of heterochromatin on both sides of the centromere of 2 was remarkable in all but the La Rioja populations. The specimens from La Rioja showed a similar block of heterochromatin on the short arm of 1. Taxonomic studies of several specimens from these localities revealed differences in larval development, glandular pattern, the size of specimens, etc. As a whole, biological as well as karyological features suggest that the isolated population at La Rioja is a separate entity, at the species level, as described elsewhere.

Animals↗
PubMed1997

Haplotype analysis of hemochromatosis: evaluation of different linkage-disequilibrium approaches and evolution of disease chromosomes.

We applied several types of linkage-disequilibrium calculations to analyze the hereditary hemochromatosis (hh) locus. Twenty-four polymorphic markers in the major histocompatibility complex (MHC) class I region were used to haplotype hh and normal chromosomes. A total of 169 hh and 161 normal chromosomes were analyzed. Disequilibrium values were found to be high over an unusually large region beginning 150 kb centromeric of HLA-A and extending nearly 5 Mb telomeric of it. Recombination in this region was approximately 28% of the expected value. This low level of recombination contributes to the unusually broad region of linkage disequilibrium found with hh. The strongest disequilibrium was found at locus HLA-H (delta = .84) and at locus D6S2239 (delta = .85), a marker approximately 10 kb telomeric to HLA-H. All disequilibrium methods employed in this study found peak disequilibrium at HLA-H or D6S2239. The cys282tyr mutation in HLA-H, a candidate gene for hh, was found in 85% of disease chromosomes. A haplotype phylogeny for hh chromosomes was constructed and suggests that the mutation associated with the most common haplotype occurred relatively recently. The age of the hh mutation was estimated to be approximately 60-70 generations. Disequilibrium was maintained over a greater distance for hh-carrying chromosomes, consistent with a recent mutation for hh. Our data provide a reasonable explanation for previous difficulties in localizing the hh locus and provide an evolutionary history for disease chromosomes.

Evolution, Molecular↗
PubMed2006

Karyology of the Antarctic scallop Adamussium colbecki, with some comments on the karyological evolution of pectinids.

Karyotype, location of the nucleolar organiser region (NOR) and heterochromatin presence and composition were studied in the Antarctic scallop Adamussium colbecki Smith, 1902. The karyotype exhibits 2n = 38 chromosomes with 11 pairs of metacentrics, 5 of submetacentrics, one subtelocentric and two telocentrics. Ag-NOR, CMA(3), DA/MM and NOR-FISH evidenced paracentromeric NORs on the short arm of 2nd pair chromosomes. Digestion with three restriction endonucleases followed by sequential staining with Giemsa, CMA(3) and DAPI evidenced on all chromosomes centromeric heterochromatin positive for both DAPI and CMA(3). In situ hybridisation analysis showed the presence of an AT-rich satellite DNA in the centromeric heterochromatin of several chromosomes. A mosaicism was detected in the germinal cell lines of one specimen, as in six of the 20 plates examined the set had 37 chromosomes with a missing pair of telocentrics and an unpaired metacentric. Comparison of the chromosome sets of all the pectinids studied to date and comparison with a phyletic tree obtained from molecular mitochondrial genes studies yielded good agreement between karyotype morphology and taxonomic classification.

Animals↗
PubMed2000

(T2AG3)n telomeric sequence hybridization suggestive of centric fusion in karyotype marsupials evolution.

It has been suggested that the karyotype of the marsupials derived from a low diploid number (2n = 14) which originated, through fissions of biarmed chromosomes, the karyotypes with a higher 2n. The telomeric sequence (T2AG3)n was in situ hybridized to the chromosomes of Gracilinanus microtarsus and G. emiliae, Micoureus demerarae and Marmosa murina, species with 2n = 14, in Monodelphis sp., M. domestica, M. kunsi and M. brevicaudata with 2n = 18, and in Lutreolina crassicaudata, Didelphis albiventris, Chironectes minimus, Philander opossum and P. frenata, all of them with 2n = 22. The probe hybridization occurred in the telomeric regions of both arms, short and long, of all chromosomes of the complement of all individuals of all species analysed. However, in some pairs of the karyotypes of Gracilinanus microtarsus and Micoureus demerarae (with 2n = 14), and in Monodelphis sp., M. domestica, M. kunsi and M. brevicaudata (2n = 18) ectopic signs of hybridization were detected proximal to the centromeres, suggesting the retention of this telomeric sequence in the centromeric regions of some chromosomes of these species. Based on these results, it is proposed that the karyotype of marsupials evolved from a 2n = 22 to a 2n = 14, by means of chromosomal fusions.

Animals↗
PubMed1998

Selective co-evolution of the D6STNFa microsatellite region with HLA class I and II loci.

We analyzed the HLA-A, -B, -DR and -DQ phenotypes and 12 microsatellite locus genotypes within and close to the major histocompatibility complex in a panel of 98 randomly selected, healthy, unrelated Dutch Caucasoid individuals. Allele frequencies and Hardy-Weinberg equilibrium (HWE) were calculated. Also, the linkage disequilibrium patterns between HLA and microsatellite loci were studied. The HLA-A, -B, -DR, -DQ and six microsatellite loci centromeric of the HLA-A showed HWE. In contrast, all microsatellites telomeric of the HLA-A showed deviation from HWE due to excess of homozygosity. Linkage disequilibrium analyses provided strong evidence that among the tested microsatellite loci only the alleles of the D6STNFa locus are in linkage disequilibrium with both HLA-B and -DR. Our results suggest that selection acting on the HLA genes includes the D6STNFa locus and linked genes.

Denmark↗
PubMed2005

Long inversely oriented subunits form a complex monomer of Tribolium brevicornis satellite DNA.

Highly abundant satellite DNA named TBREV is detected and characterized in the beetle Tribolium brevicornis (Insecta: Coleoptera). An outstanding peculiarity of the TBREV satellite monomer is its complex structure based on the two approximately 470-bp-long subunits, inversely oriented within a 1061-bp-long monomer sequence. The proposed evolutionary history demonstrates a clear trend toward increased complexity and length of the TBREV satellite monomer. This tendency has been observed on three levels: first as direct and inverted duplications of short sequence motifs, then by inverse duplication of the approximately 470-bp sequence segment, and, finally, by spread of inversely duplicated elements in a higher-order register and formation of extant monomers. Inversely oriented subunits share a similarity of 82% and have a high capacity to form a thermodynamically stable dyad structure that is, to our knowledge, the longest ever described in any satellite monomer. Analysis of divergences between inversely oriented subunits shows a tendency to a further reduction in similarity between them. Except in its centromeric localization, the TBREV satellite does not show similarity to other known Tribolium satellites, either in nucleotide sequence or in monomer length and complexity. However, TBREV shares common features of other Tribolium satellites that might be under functional constraints: nonconstant rate of evolution along the monomer sequence, short inverted repeats in the vicinity of an A+T tract, nonrandom distribution of A or T >/=3 tracts, and CENP-B box-like motifs. Although long inverted subunits might reinforce structural characteristics of the satellite monomer, their nucleotide sequence does not seem to be under constraints in order to preserve the dyad structure.

Animals↗
PubMed1988

Human tyrosinase gene, mapped to chromosome 11 (q14----q21), defines second region of homology with mouse chromosome 7.

The enzyme tyrosinase (monophenol,L-dopa:oxygen oxidoreductase; EC 1.14.18.1) catalyzes the first two steps in the conversion of tyrosine to melanin, the major pigment found in melanocytes. Some forms of oculocutaneous albinism, characterized by the absence of melanin in skin and eyes and by a deficiency of tyrosinase activity, may result from mutations in the tyrosinase structural gene. A recently isolated human tyrosinase cDNA was used to map the human tyrosinase locus (TYR) to chromosome 11, region q14----q21, by Southern blot analysis of somatic cell hybrid DNA and by in situ chromosomal hybridization. A second site of tyrosinase-related sequences was detected on the short arm of chromosome 11 near the centromere (p11.2----cen). Furthermore, we have confirmed the localization of the tyrosinase gene in the mouse at or near the c locus on chromosome 7. Comparison of the genetic maps of human chromosome 11 and mouse chromosome 7 leads to hypotheses regarding the evolution of human chromosome 11.

Animals↗
PubMed2000

Chromosome structure of Triticum timopheevii relative to T. turgidum.

The chromosome structure of four different wild populations and a cultivated line of Triticum timopheevii (2n = 28, AtAtGG) relative to Triticum turgidum (2n = 28, AABB) was studied, using genomic in situ hybridisation (GISH) and C-banding analysis of meiotic configurations in interspecific hybrids. Two wild accessions and the cultivated line showed the standard C-banding karyotype. The other two accessions are homozygous for translocation 5At/3G and translocations 1G/2G and 5G/6G. GISH analysis revealed that all the T. timopheevii accessions carry intergenome translocations 6At/1G and 1G/4G and identified the position of the breakpoint in translocation 5At/3G. C-banding analysis of pairing at metaphase I in the hybrids with T. turgidum provides evidence that four species-specific translocations (6AtS/1GS, 1GS/4GS, 4GS/4AtL, and 4AtL/3AtL) exist in T. timopheevii, and that T. timopheevii and T. turgidum differ in the pericentric inversion of chromosome 4A. Bridge plus acentric fragment configurations involving 4AL and 4AtL were identified in cells at anaphase I. This result suggests that the paracentric inversion of 4AL from T. turgidum does not exist in T. timopheevii. Both tetraploid species have undergone independent and distinct evolutionary chromosomal rearrangements. The position, intercalary or subdistal, of the breakpoints in species-specific translocations and inversions contrasts with the position, at or close to the centromere, of intraspecific translocations. Different mechanisms for intraspecific and species-specific chromosome rearrangements are suggested.

Anaphase↗
PubMed1998

Evidence for linkage to psychosis and cerebral asymmetry (relative hand skill) on the X chromosome.

The hypothesis that psychosis arises as a part of the genetic diversity associated with the evolution of language generates the prediction that illness will be linked to a gene determining cerebral asymmetry, which, from the evidence of sex chromosome aneuploidies, is present in homologous form on the X and Y chromosomes. We investigated evidence of linkage to markers on the X chromosome in 1) 178 families multiply affected with schizophrenia or schizoaffective disorder with a series of 16 markers spanning the centromere (study 1), and 2) 180 pairs of left-handed brothers with 14 markers spanning the whole chromosome (study 2). In study 1, excess allele-sharing was observed in brother-brother pairs (but not brother-sister or a small sample of sister-sister pairs) over a region of approximately 20 cM, with a maximum LOD score of 1.5 at DXS991. In study 2, an association between allele-sharing and degree of left-handedness was observed extending over approximately 60 cM, with a maximum lod score of 2.8 at DXS990 (approximately 20 cM from DXS991). Within the overlap of allele-sharing is located a block in Xq21 that transposed to the Y chromosome in recent hominid evolution and is now represented as two segments on Yp. In one of two XX males with psychosis we found that the breakpoint on the Y is located within the distal region of homology to the block in Xq21. These findings are consistent with the hypothesis that an X-Y homologous determinant of cerebral asymmetry carries the variation that contributes to the predisposition to psychotic illness.

Female↗
PubMed2002

Chromosomal rearrangements and evolution of recombination: comparison of chiasma distribution patterns in standard and robertsonian populations of the house mouse.

The effects of chromosomal rearrangements on recombination rates were tested by the analysis of chiasma distribution patterns in wild house mice. Males and females of two chromosomal races from Tunisia differing by nine pairs of Robertsonian (Rb) fusions (standard all-acrocentric, 2N = 40 and 2N = 22) were studied. A significant decrease in chiasma number (CN) was observed in Rb mice compared to standard ones for both sexes. The difference in CN was due to a reduction in the number of proximal chiasmata and was associated with an overall more distal redistribution. These features were related to distance of chiasmata to the centromere, suggesting that the centromere effect was more pronounced in Rb fusions than in acrocentric chromosomes. These modifications were interpreted in terms of structural meiotic constraints, although genic factors were likely involved in patterning the observed differences between sexes within races. Thus, the change in chromosomal structure in Rb mice was associated with a generalized decrease in recombination due to a reduction in diploid number, a lower CN, and a decrease in the efficiency of recombination. The effects of such modifications on patterns of genic diversity are discussed in the light of models of evolution of recombination.

Animals↗
PubMed1994

Mapping in plants: progress and prospects.

Comprehensive genetic maps are now available for all of the world's important crop species. Data show a remarkable conservation of order of markers over family-wide taxonomic groupings and illuminate species relationships and mechanisms of genome evolution. Comparison of genetic and physical maps has revealed differences in genetic distance throughout genomes with implications for genome organization, gene isolation and transformation.

Base Sequence↗
PubMed1984

Linkage disequilibrium and evolutionary relationships of DNA variants (restriction enzyme fragment length polymorphisms) at the serum albumin locus.

Four additional DNA variants (restriction enzyme fragment length polymorphisms) making a total of eight polymorphic sites at the human albumin locus have been identified. These eight sites were found after screening 689 of 20,000 nucleotides by using cDNA probes for albumin with 27 different restriction enzymes. One in 85 nucleotides was therefore potentially polymorphic. The average nucleotide diversity between any two randomly chosen chromosomes was calculated to be 1/500. We observed marked linkage disequilibrium between the eight variants. Only 7 haplotypes among 256 possible combinations were observed in 160 chromosomes from Caucasoids, Blacks, and Asians. Two haplotypes were found in all three human races, indicating that their origin predated human racial divergence. The three rarest haplotypes appear to represent recombinational events between the more common haplotypes. All crossovers occurred in the same general region. Studies of several nonhuman primates indicated that the origin of one haplotype predated the human-African ape divergence. Although it is not possible to rule out maintenance of this tight linkage by selection or fixation, it is suggested that the limited number of haplotypes at the chromosomal site of the albumin gene near the centromere of chromosome 4 may be the result of decreased recombination.

Animals↗
PubMed1998

Numeric aberration of chromosome 17 is strongly correlated with p53 overexpression, tumor proliferation and histopathology in human bladder cancer.

BACKGROUND: This study investigated the relationships between the numeric aberrations of chromosome 17 and p53 expression, the proliferating cell nuclear antigen labeling index (PCNA-LI) and histopathology, to determine their prognostic significance in bladder cancer. METHODS: Using in situ hybridization (ISH) with a biotin-labeled chromosome-specific DNA probe, the copy number of pericentromeric sequences in chromosome 17 were detected within interphase nuclei in formalin-fixed paraffin-embedded sections from 59 nonmetastasized transitional cell carcinomas (TCCs) of the urinary bladder. Expression of p53 and PCNA-LI were determined in serial sections by an immunohistochemical method. RESULTS: The percentage of hyperdiploid cells for chromosome 17 correlated with p53 overexpression (P< 0.002), PCNA-LI (P< 0.002), increasing tumor grade (P< 0.002) and advanced pathologic stage (P< 0.002). The average percentage of hyperdiploid cells was lower in tumors with negative p53 expression than in tumors with p53 overexpression (P< 0.002). Also, more polysomic TCCs were found in muscle-invasive than in superficial cases (P< 0.01 ), and there was a difference in both p53 overexpression or PCNA-LI between disomic and polysomic TCCs (P< 0.01). Patients with chromosome 17 disomic tumors showed less frequent tumor progression than patients with polysomic tumors (P< 0.05). However, chromosome 17 polysomy was an independent prognostic indicator only for patient survival (P< 0.05). CONCLUSION: The occurrence and extent of numeric aberrations of chromosome 17 may be associated with the evolution of aggressive growth in TCC and may be a useful indicator for survival.

Aged↗
PubMed2004

A 3347-locus genetic recombination map of sequence-tagged sites reveals features of genome organization, transmission and evolution of cotton (Gossypium).

We report genetic maps for diploid (D) and tetraploid (AtDt) Gossypium genomes composed of sequence-tagged sites (STS) that foster structural, functional, and evolutionary genomic studies. The maps include, respectively, 2584 loci at 1.72-cM ( approximately 600 kb) intervals based on 2007 probes (AtDt) and 763 loci at 1.96-cM ( approximately 500 kb) intervals detected by 662 probes (D). Both diploid and tetraploid cottons exhibit negative crossover interference; i.e., double recombinants are unexpectedly abundant. We found no major structural changes between Dt and D chromosomes, but confirmed two reciprocal translocations between At chromosomes and several inversions. Concentrations of probes in corresponding regions of the various genomes may represent centromeres, while genome-specific concentrations may represent heterochromatin. Locus duplication patterns reveal all 13 expected homeologous chromosome sets and lend new support to the possibility that a more ancient polyploidization event may have predated the A-D divergence of 6-11 million years ago. Identification of SSRs within 312 RFLP sequences plus direct mapping of 124 SSRs and exploration for CAPS and SNPs illustrate the "portability" of these STS loci across populations and detection systems useful for marker-assisted improvement of the world's leading fiber crop. These data provide new insights into polyploid evolution and represent a foundation for assembly of a finished sequence of the cotton genome.

Chromosome Mapping↗
PubMed2006

Distribution of Ty3-gypsy- and Ty1-copia-like DNA sequences in the genus Helianthus and other Asteraceae.

Two repeated DNA sequences, pHaS13 and pHaS211, which revealed similarity to the int gene of Ty3-gypsy retrotransposons and the RNAse-H gene of Ty1-copia retroelements, respectively, were surveyed in Asteraceae species and within the genus Helianthus. Southern analysis of the genome of selected Asteraceae that belong to different tribes showed that pHaS13- and pHaS211-related subfamilies of gypsy- and copia-like retroelements are highly redundant only in Helianthus and, to a lesser extent, in Tithonia, a Helianthus strict relative. However, under low stringency posthybridization washes, bands were observed in almost all the other Asteraceae tested when pHaS13 was used as a probe, and in several species when pHaS211 was hybridized. FISH analysis of pHaS13 or pHaS211 probes was performed in species in which labelling was observed in Southern hybridizations carried out under high stringency conditions (Helianthus annuus, Tithonia rotundifolia, Ageratum spp., Leontopodium spp., Senecio vulgaris for pHaS13, and H. annuus, Tithonia rotundifolia, and S. vulgaris for pHaS211). Scattered labelling was observed over all metaphase chromosomes, indicating a large dispersal of both Ty3-gypsy- and Ty1-copia-like retroelements. However, preferential localization of Ty3-gypsy-like sequences at centromeric chromosome regions was observed in all of the species studies but one, even in species in which pHaS13-related elements are poorly represented. Ty1-copia-like sequences showed preferential localization at the chromosome ends only in H. annuus. To study the evolution of gypsy- and copia-like retrotransposons in Helianthus, cladograms were built based on the Southern blot hybridization patterns of pHaS13 or pHaS211 sequences to DNA digests of several species of this genus. Both cladograms agree in splitting the genomes studied into annuals and perennials. Differences that occurred within the clades of perennial and annual species between gypsy- and copia-like retroelements indicated that these retrotransposons were differentially active during Helianthus speciation, suggesting that the evolution of the 2 retroelement families was, within limits, independent.

Amino Acid Sequence↗
PubMed2002

[Evidence of species specific pericentric inversion in the karyotype of the midge Chironomus balatonicus].

Pericentric inversions do not play any important role in chromosomal rearrangements in the karyotype evolution of the genus Chironomus. However, a unique case of the fixed pericentric inversion was discovered in chromosome 2 of Chironomus balatonicus--one of the members of plumosus-species group (Kikhadze et al., 1996a; Golygina et al., 1996). According to morphological criteria, a centromere band on chromosome 2 changed its position in Ch. balatonicus. The cloned H3-SauDNA, specific for centromeres in plumosus group, was in situ hybridized with Ch. balatonicus polytene chromosomes, and thus a real change in the centromere position was proved to be a result of pericentric inversion. This was also confirmed after differential C-staining.

Animals↗
PubMed1998

Conventional cytogenetics and FISH evaluation of chimerism after sex-mismatched bone marrow transplantation (BMT) and donor leukocyte infusion (DLI).

BACKGROUND AND OBJECTIVES: Sensitive and quantitative cytogenetic methods to better assess the biological significance of post-BMT chimerism have been recently developed. In this study, we compared the results of chimerism analysis and evolution employing conventional cytogenetics and fluorescence in situ hybridization (FISH) in 16 patients after sex-mismatched BMT, and in 5 patients after donor lymphocyte infusion (DLI) to treat post-BMT relapse. DESIGN AND METHODS: FISH studies were performed using separate digoxigenin labeled centromeric DNA probes for the X (pDMX1) and Y (DYZ1/DYZ3) chromosomes. To this purpose, different types of samples were used: bone marrow (BM) and peripheral blood (PB) slides processed for conventional cytogenetics, and routine BM and PB smears. RESULTS: Results of chimerism studies performed on different types of samples showed no significant differences. No significant differences in the ability to identify the sex of each cell with both pDMX1 and DYZ1/DYZ3 probes were found and the results obtained from independent experiments showed a high linear correlation. Chimerism analysis by FISH showed initial mixed chimerism after BMT in 10 patients. Seven of these patients were also studied by conventional cytogenetics and 2 of these showed mixed chimerism. Seven of the former 10 patients evolved to complete donor chimera. 6 patients showed cytogenetic or hematologic bone marrow relapse, 3 of which were preceded by mixed chimaerism as revealed by FISH studies. FISH studies permitted an easy and accurate monitorization of the response to DLI in 5 relapsed patients, showing an increase in the proportion of donor cells in 4 patients as they reached a new complete remission. INTERPRETATION AND CONCLUSIONS: Both FISH and conventional cytogenetics are quantitative methods to assess chimerism. However, FISH is more sensitive, accurate and can even be applied on routine BM and PB smears. Furthermore, its combination with immunophenotyping approaches to quantify chimerism on cell subpopulations, will help to clarify post-BMT chimerism significance.

Adolescent↗
PubMed1998

Familial supernumerary marker chromosome evolution through three generations.

A mosaic chromosome complement, 46,XY/47,XY,+r(15), was detected at prenatal diagnosis. Family studies showed the mother and one of her two children to have a bisatellited supernumerary marker chromosome (SMC) in all lymphocytes examined. The maternal grandfather also showed a bisatellited SMC, but in only 2 per cent of his lymphocytes. NOR, DA/DAPI, and chromosome 15 centromere and short arm-specific probes confirmed the identify of the bisatellited SMC and of ring SMC as derived from chromosome 15. An apparently normal male was born at full term. At age 1 year, the baby continues to have normal growth and development. The bisatellited 15 likely originated by somatic mutation in the grandfather (2 per cent cells), was transmitted unchanged to the daughter and grandson (germline transmission, no mosaicism), and then evolved by excising the satellites and forming a ring SMC in the index case. Progressive changes in the frequency and subsequent changes in the structure of this SMC illustrate the unusual characteristics of chromosome 15.

Adult↗