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Phylogenomic study of the subfamily Caprinae by cross-species chromosome painting with Chinese muntjac paints.

Chromosomal homologies have been established between the Chinese muntjac (Muntiacus reevesi, MRE, 2n = 46) and five ovine species: wild goat (Capra aegagrus, CAE, 2n = 60), argali (Ovis ammon, OAM, 2n = 56), snow sheep (Ovis nivicola, ONI, 2n = 52), red goral (Naemorhedus cranbrooki, NCR, 2n = 56) and Sumatra serow (Capricornis sumatraensis, CSU, 2n = 48) by chromosome painting with a set of chromosome-specific probes of the Chinese muntjac. In total, twenty-two Chinese muntjac autosomal painting probes detected thirty-five homologous segments in the genome of each species. The chromosome X probe hybridized to the whole X chromosomes of all ovine species while the chromosome Y probe gave no signal. Our results demonstrate that almost all homologous segments defined by comparative painting show a high degree of conservation in G-banding patterns and that each speciation event is accompanied by specific chromosomal rearrangements. The combined analysis of our results and previous cytogenetic and molecular systematic results enables us to map the chromosomal rearrangements onto a phylogenetic tree, thus providing new insights into the karyotypic evolution of these species.

Animals↗

Karyometrical analysis of Microsomacanthus spasskii and M. spiralibursata.

Analysis of Giemsa-stained mitotic metaphase plates of Microsomacanthus spasskii and M. spiralibursata (Cestoda:Hymenolepididae) revealed the diploid chromosome numbers for both species to be 2n = 6. The karyotypes are remarkably similar in general morphology; they both consist of three pairs of metacentric or meta-submetacentric chromosomes graded in size from 4.3 to 7.0 microns. Slight interspecific differences exist in the position of the centromere of chromosomes of the pair 3. Based on existing chromosome data the possible pathways of the karyotypic evolution within the family Hymenolepididae are discussed.

Animals↗

Y chromosome duplication in chronic myeloid leukemia.

Y chromosome duplication appeared in a patient with chronic myeloid leukaemia (CML) during blastic crisis. Additional chromosome changes were present. Y chromosome duplication may be a minor route of karyotype evolution in CML.

Adult↗

Phylogenetic relationships of African killifishes in the genera Aphyosemion and Fundulopanchax inferred from mitochondrial DNA sequences.

We have analyzed the phylogenetic relationships of 52 species representing all defined species groups (J. J. Scheel, 1990, Atlas of Killifishes of the Old World, 448 pp.) of the African aplocheiloid fish genera Aphyosemion and Fundulopanchax in order to examine their interrelationships and to reveal trends of karyotypic evolution. The data set comprised 785 total nucleotides from the mitochondrial 12S rRNA and cytochrome b genes. The molecular-based topologies analyzed by both maximum parsimony and neighbor-joining support the monophyly of most previously defined species groups within these two killifish genera. The genus Aphyosemion is monophyletic except for the nested position of Fundulopanchax kunzi (batesi group; subgenus Raddaella) within this clade, suggesting that this taxon was improperly assigned to Fundulopanchax. The remaining Fundulopanchax species sampled were supported as being monophyletic in most analyses. Relationships among the species groups in both genera were not as strongly supported, suggesting that further data will be required to resolve these relationships. Additional sampling from the 16S rRNA gene allowed further resolution of relationships within Fundulopanchax, more specifically identifying the nonannual scheeli group as the basal lineage of this otherwise annual genus. Chromosomal evolution within Aphyosemion has been episodic, with the evolution of a reduced n = 9-10 metacentric complement having occurred in multiple, independent lineages. Polarity of chromosomal reductions within the elegans species group appears to support previous hypotheses concerning mechanisms of karyotypic change within the genus Aphyosemion.

Africa↗

Zoo-fluorescence in situ hybridization analysis of human and Indian muntjac karyotypes (Muntiacus muntjak vaginalis) reveals satellite DNA clusters at the margins of conserved syntenic segments.

Zoo-fluorescence in situ hybridization (FISH) with human whole chromosome-specific paint probes revealed extensive homoeologies between Indian muntjac (2n=6, 7 female, male) and human karyotypes (2n=46). Forty-two conserved syntenic segments, corresponding to all human chromosomes except the Y chromosome, produced a near-complete coverage of the muntjac complement and revealed margins of interspecific segmental homoeology. To test the hypothesis that interstitial satellite DNA loci, illuminated by a Chinese muntjac C5-satellite probe in Indian muntjac chromosome arms, mark ancestral fusion points (Lin CC, Sasi R, Fan YS, Chen Z-Q (1991) New evidence for tandem chromosome fusions in the karyotypic evolution of the Asian muntjacs. Chromosoma 101: 19-24), we combined Zoo-FISH with C5 satellite mapping. Twenty-six interstitial satellite DNA loci were detected in the haploid Indian muntjac genome and were found to co-localize with the margins of conserved human/Indian muntjac syntenic segments. These results were confirmed by two-colour FISH and are in accordance with the tandem fusion hypothesis for Indian muntjac chromosomes. Furthermore, conserved syntenic segment combinations detected in pig, cattle and Indian muntjac Zoo-FISH maps reveal ancestral artiodactyl chromosomes.

Animals↗

Sex determination without the Y chromosome in two Japanese rodents Tokudaia osimensis osimensis and Tokudaia osimensis spp.

Both males and females of the species of spinous country-rats (Tokudaia osimensis osimensis, T.o.o., Rodentia: Muridae), which live on Amami Oshima Island, a southern Japanese island, have 25 chromosomes. Another species of spinous country-rats (Tokudaia osimensis spp., T.o. spp., which live on Tokunoshima Island 40 km south of Amami Oshima Island, also have an odd number of chromosomes, 45. Karyotypes of males and females by the G-band method were indistinguishable in both populations. The lesser number of chromosomes (25) of T.o.o. is likely to be a result of Robertsonian fusions of 45 chromosomes of T.o. spp. that seem to be the offspring of another spinous country-rat Tokudaia osimensis muenninki (T.o.m.), which live on Okinawa Island and have 44 chromosomes including the X and Y Chrs. The lengths of the non-paired, putative X-Chr of T.o.o. and T.o. spp. occupied roughly 3.2% and 1.7% of the total lengths, respectively, hinting at translocation or exchange of a part of the X Chr and thus in violation of Ohno's Law. Southern blot analysis with murine Sry as a probe indicated that these two animals do not have Sry. When Zfx from T.o. spp. was used as a probe, both males and females of T.o.o. and T.o. spp. showed two bands, suggesting possible translocation of Zfy from the Y Chr. Comparison of physical characteristics, constituents of chromosomes, and sex-determination methods of these three Tokudaia country-rat populations suggests that each is endemic to each island and constitutes an independent species. These specialized species would provide us with clues to elucidate the mechanisms of primary sex determination and karyotype evolution in mammals.

Animals↗

Localisation of aphidicolin-induced break points in Holstein-Friesian cattle (Bos taurus) using RBG-banding.

Fragile sites (FS) seem to play a role in genome instability and may be involved in karyotype evolution and chromosome aberrations. The majority of common fragile sites are induced by aphidicolin. Aphidicolin was used at two different concentrations (0.15 and 0.30 microM) to study the occurrence of FS in the cattle karyotype. In this paper, a map of aphidicolin induced break points and fragile sites in cattle chromosomes was constructed. The statistical analysis indicated that any band with three or more breaks was significantly damaged (P<0.05). According to this result, 30 of the 72 different break points observed were scored as fragile sites. The Pearson correlation test showed a positive association between chromosome length and the number of fragile sites (r=0.54). On the contrary, 21 FS were identified on negative R bands while 9 FS were located on positive R bands.

Animals↗

Neocentromeres: role in human disease, evolution, and centromere study.

The centromere is essential for the proper segregation and inheritance of genetic information. Neocentromeres are ectopic centromeres that originate occasionally from noncentromeric regions of chromosomes. Despite the complete absence of normal centromeric alpha-satellite DNA, human neocentromeres are able to form a primary constriction and assemble a functional kinetochore. Since the discovery and characterization of the first case of a human neocentromere in our laboratory a decade ago, 60 examples of constitutional human neocentromeres distributed widely across the genome have been described. Typically, these are located on marker chromosomes that have been detected in children with developmental delay or congenital abnormalities. Neocentromeres have also been detected in at least two types of human cancer and have been experimentally induced in Drosophila. Current evidence from human and fly studies indicates that neocentromere activity is acquired epigenetically rather than by any alteration to the DNA sequence. Since human neocentromere formation is generally detrimental to the individual, its biological value must lie beyond the individual level, such as in karyotype evolution and speciation.

Animals↗

Folic acid sensitive fragile sites are not limited to the human karyotype. Demonstration of nonrandom gaps and breaks in the Persian vole Ellobius lutescens Th. inducible by methotrexate, fluorodeoxyuridine, and aphidicolin.

At least four folic acid sensitive fragile sites have been detected in the karyotype of the Persian vole Ellobius lutescens Th. (Rodentia, Microtinae). Two such "hot spots" are located on chromosome 1 flanking the pericentric segment which is inverted in many individuals. The fragile site on 1p was observed on both homologues in one cell. Our findings suggest that fragile sites are common properties of mammalian chromatin and might have played a role in karyotype evolution.

Animals↗

Distribution of intrachromosomal telomeric sequences (ITS) on Macaca fascicularis (Primates) chromosomes and their implication for chromosome evolution.

The intrachromosomal location of the telomeric sequence in the crab-eating macaque, Macaca fascicularis (F. Cercopithecidae, Catarrhini) has been analysed by fluorescent in situ hybridisation with a long synthetic (TTAGGG)(n) probe. A total of 237 metaphases was analysed. As expected, all telomeres hybridised with the probe and 90 intrachromosomal loci with different hybridisation frequencies were also detected. The chromosomal location of interstitial telomeric sequences in M. fascicularis and in Homo sapiens was then compared, 37 sites (41.11%) being found to be conserved. Some of these sequences can be derived from rearrangements, such as inversions (MFA13q23) or fusions (MFA2p13 and MFA13p12), that have taken place during karyotype evolution.

Animals↗

Cytogenetic biclonality corresponding to multiphasic differentiation in an atypical thyroid adenoma.

Cytogenetic aberrations have been described in about 30% of benign thyroid tumors, but their role for tumorigenesis or progression has not yet been elucidated. We describe the cytogenetic analyses in a thyroid adenoma with two different clonal cytogenetic stemlines: 45,XX,der(1)t(1;14)(p13;q11.2-q(13),t(5;12)(q11.2;q24),del(9)(q12),- 10,der(11)t(11;?;19)(p15;q13),der(14)t(14;15)(q11.2-q13;q23),del(15)(q23 ), der(15)t(9;15)(q12;p10),der(19)t(10;19)(q11.2;q13)/46,X,?inv(x),?inv(3) (p21q29),t(3;8)(q26;q12). Histologic examination revealed an atypical follicular thyroid adenoma containing microfollicular, follicular, trabecular-solid, and oncocytic components. There may be a direct relation between the different cytogenetic stemlines and the histologic diversity of the tumor. Thyroid tumors with complex karyotypes involving the 19q13 breakpoint may represent advanced stages of karyotypic evolution and therefore warrant an extensive clinical follow-up.

Adenoma↗

Molecular phylogeny of the marmots (Rodentia: Sciuridae): tests of evolutionary and biogeographic hypotheses.

There are 14 species of marmots distributed across the Holarctic, and despite extensive systematic study, their phylogenetic relationships remain largely unresolved. In particular, comprehensive studies have been lacking. A well-supported phylogeny is needed to place the numerous ecological and behavioral studies on marmots in an evolutionary context. To address this situation, we obtained complete cytochrome (cyt) b sequences for 13 of the species and a partial sequence for the 14th. We applied a statistical approach to both phylogeny estimation and hypothesis testing, using parsimony and maximum likelihood-based methods. We conducted statistical tests on a suite of previously proposed hypotheses of phylogenetic relationships and biogeographic histories. The cyt b data strongly support the monophyly of Marmota and a western montane clade in the Nearctic. Although some other scenarios cannot be rejected, the results are consistent with an initial diversification in North America, followed by an invasion and subsequent rapid diversification in the Palearctic. These analyses reject the two major competing hypotheses of M. broweri's phylogenetic relationships--namely, that it is the sister species to M. camtschatica of eastern Siberia, and that it is related closely to M. caligata of the Nearctic. The Alaskan distribution of M. broweri is best explained as a reinvasion from the Palearctic, but a Nearctic origin can not be rejected. Several other conventionally recognized species groups can also be rejected. Social evolution has been homoplastic, with large colonial systems evolving in two groups convergently. The cyt b data do not provide unambiguous resolution of several basal nodes in the Palearctic radiation, leaving some aspects of pelage and karyotypic evolution equivocal.

Animals↗

Origin and significance of centric fusions in domestic sheep.

The karyotypes of 731 sheep of various breeds were studied and considered in association with previous chromosome studies of domestic sheep. A high incidence of the t2 trnslocation was found in two pedigree flocks of New Zealand Romney sheep. One of these flocks was established over 100 years ago and it is suggested that this translocation originated in the Romney Marsh breed of sheep in England. A naturally occurring double translocation heterozygote 52t1t2 was reported for the first time. A further flock of sheep of the Perendale breed was found with a high incidence of dicentric chromosome fusion that was identified as the t3 translocation. The apparently common occurrence of chromosome polymorphism, due to centric fusions, in domestic sheep is discussed in relation to karyotype evolution among both domestic and wild sheep.

Animals↗

The karyotype of the parasitoid Chelonus insularis Cresson (Hymenoptera, Braconidae, Cheloninae).

The karyotype of Chelonus insularis (Hymenoptera, Braconidae, Cheloninae) is described. The males show an haploid number of seven chromosomes and the females a diploid number of fourteen chromosomes, confirming haplo-diploid sex determination. Comparisons of these results with karyotypes of other species of the same family were done and a possible mechanism involved in the karyotype evolution of this species is discussed.

Animals↗

Mathematical tree models for cytogenetic development in solid tumors.

We present a new approach for modeling the occurrence of genetic changes in human tumors over time. In solid tumors, data on genetic alterations are usually only available at a single point in time, allowing no direct insight into the sequential order of genetic events. In our approach, genetic tumor development and progression is assumed to follow a probabilistic tree model. We use maximum likelihood estimation to reconstruct a tree model for the genetic evolution of a given tumor type. The use of the proposed method is illustrated by an application to cytogenetic data from 173 cases of clear cell renal cell carcinoma, which results in a model for the karyotypic evolution of this tumor.

Carcinoma, Renal Cell↗

Transient leukemoid disorder in a newborn with Down syndrome followed 19 months later by an acute myeloid leukemia: demonstration of the same structural change in both instances with clonal evolution.

A transient leukemoid disorder (TLD) was observed in a newborn with Down syndrome (DS), demonstrating a clonal abnormality: 47,XX,der(X;15)(p10;q10),+21(c). Spontaneous remission was observed, but 19 months later an acute leukemia from the myeloid series was discovered. Cytogenetic study revealed the same structural change as at birth, with karyotypic evolution corresponding to addition of one chromosome 8 and a fourth chromosome 21. These findings demonstrate, at least in our patient, that TLD and the subsequent acute leukemia are closely related and that TLD, closely related to DS, must be viewed as a preleukemic disorder undergoing spontaneous remission. A review of literature data shows that most cytogenetic studies reported so far are related to either TLD or acute leukemia in DS. Serial studies performed in the same patient are quite infrequent and, to the best of our knowledge, there is only one other report demonstrating a cytogenetic relation between TLD and the subsequent acute leukemia.

Acute Disease↗

Cytogenetic findings in a new case of adenoid cystic carcinoma arising in sphenoidal sinus.

We studied a case of adenoid cystic carcinoma. Cytogenetic analysis was performed on short-term culture, and the karyotype revealed only an abnormal cell line with the following changes: partial trisomy 5q, 6q deletion, monosomy of chromosome 9,der(10)t(10;15), a possible ring chromosome 22, and loss of the Y chromosome. The implication of chromosomes 6 and 9 is considered in relation to the karyotypic evolution of this type of tumor.

Adult↗

A newly established human lymphoma cell line, FL-18, carrying a 14;18 translocation.

A new human cell line named FL-18, carrying a 14;18 translocation [t(14;18)(q32;q21)], was established from a Japanese patient with follicular small cleaved cell lymphoma. The established FL-18 cells had monoclonal surface immunoglobulins (IgG-kappa) and were negative for Epstein-Barr virus nuclear antigens. The high-resolution banding technique indicated the breakpoints of chromosomes 14 and 18 involved in the characteristic 14;18 translocation to be at sub-bands 14q32.3 and 18q21.3, respectively. The FL-18 cell line should be useful for studying oncogenic events associated with 14;18 translocation and karyotype evolution.

Aged↗