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PubMed1982

Cytotaxonomy of the Ciconiiformes (Aves), with karyotypes of eight species new to cytology.

Somatic karyotypes of 13 species of ciconiiform birds, Phoenicopterus ruber chilensis, Phoeniconaias minor, Cochlearius cochlearius, Geronticus eremita, Threskiornis molucca, T. spinicollis, Balaeniceps rex, Ciconia ciconia, C. nigra, Euxenura maguari, Xenorhynchus asiaticus, Ephippiorhynchus senegalensis, and Leptoptilos crumeniferus are presented. The chromosomes of eight of these species are described in detail for the first time. Of special interest are a case of structural heterozygosity in a male B. rex and remarkably low diploid numbers in C. nigra (2n = ca 52) and L. crumeniferus (2n = ca 52). The karyological relationships of the ciconiiform families are discussed. The karyotypes of the Phoenicopteridae are identical to karyotypes found in various other bird orders. All members of the Ardeidae hitherto studied are characterized by a submetacentric third pair of macrochromosomes (subtelocentric in all other Ciconiiformes). All Threskiornithidae share a pair of acrocentric chromosomes resulting from a reciprocal translocation between a pair of microchromosomes and pair No. 1. Both the Ciconiidae and the Balaenicipitidae show the original structure of Nos. 1, 2 and 3, also found in the Phoenicopteridae and many other birds. In contrast to the Phoenicopteridae, however, both families share a relatively high number of medium-sized to small biarmed chromosomes with the Ardeidae and the Threskiornithidae. Several characteristics in this group of chromosomes separate Balaenicipitidae from Ciconiidae.

Animals↗
PubMed1980

Chromosomal evolution in Malagasy lemurs. V. Chromosomal banding studies of Lemur fulvus albifrons, Lemur rubriventer and its hybrids with Lemur fulvus fulvus.

The karyotype of Lemur fulvus albifrons, L. rubriventer and its hybrids with L. fulvus fulvus were compared with that of L. fulvus. fulvus. The two subspecies of L. fulvus have the same karyotype. L. rubriventer differs from L. fulvus by five Robertsonian translocations and also by increased heterochromatin in the juxtacentromeric region of the X chromosome. The karyotypes in the present study compared with those of other lemurs allowed us to propose a general scheme representing the chromosomal evolution of the genus Lemur. In this genus Robertsonian translocations represent 29 of the 33 chromosomal rearrangements which have so far been identified. We cannot affirm that sterility of the hybrids is exclusively due to the accumulation of Robertsonian translocations.

Animals↗
PubMed1986

Chromosomal evolution in malignant human gliomas starts with specific and usually numerical deviations.

Our previous karyotypic studies of malignant human gliomas have demonstrated that their most consistent early or primary gross changes include gains of #7, losses of #10, #22, and the gonosomes, and the presence of double minutes. Karyotypes of 15 additional malignant human gliomas reported here have confirmed these observations and, by enlarging our series, we can now show that in addition to double minutes, certain other gross structural abnormalities also are clearly associated with the early evolution of this type of tumor. The most prevalent deviations are deletions and translocations involving 9p. Other chromosomes commonly involved in rearrangements are #1, #6, and #13, and less frequently #7, #11, and #16.

Adult↗
PubMed1996

Chromosomal relationships and phylogenetic and clustering analyses on genes Callithrix group argentata (Callitrichidae, Primates).

The karyotypes of three species of marmosets of the Callithrix argentata group (C. argentata, C. humeralifera and C. chrysoleuca) were studied. Comparisons were made among species and with the previously described karyotypes of C. emiliae, C. mauesi (argentata group) and C. jacchus (jacchus group). Two chromosomes rearrangements differentiate the argentata (2n=44) and jacchus (2n=46) groups: fusion or fission and a paracentric invasion. The argentata group is also characterized by the addition of large amounts of distal constitutive heterochromatin (CH) in some chromosomes, while the jacchus group shows mainly centromeric heterochromatin. The five species of the argentata group differ in the amount or location of the distal CH. Interspecific differences were converted to a Basic Data Matrix (BDM), that was submitted to phenetic and cladistic analyses. For cladistic analyses C. jacchus was the outgroup. The results agree with morphological and geographical data.

Animals↗
PubMed2005

Leukemic transformation of polycythemia vera: a single center study of 23 patients.

BACKGROUND: Acute leukemia (AL) may occur as rare and late event of polycythemia vera (PV). METHODS: The current study included 23 patients who developed acute leukemia in a cohort of 414 consecutive PV patients with long-term observation (3208 person years of follow-up). Kaplan-Meier Product-Limit method was used to estimate the cumulative probability of survival; Gehan-Wilcoxon test was applied to compare survival in different groups of patients. RESULTS: Median age was 68 years, and 18 patients (78%) were > 60 years of age. At diagnosis of AL, most patients had a white blood count > 10 x 10(9)/L (n = 17; 74%), Hgb < 10 g/dL (n = 13; 57%), and platelet count > 50 x 10(9)/L (n = 17; 74%). Of 14 patients in whom cytogenetic analysis was available at leukemic transformation, 12 showed high-risk abnormalities including complex karyotype (n = 10), del (7)(q22) sole (n = 1) and del (X)(q26) sole (n = 1), whereas 2 had a normal karyotype. In patients whose karyotype was available at diagnosis of PV, cytogenetic evolution was documented at progression to AL. Treatment consisted of supportive care and/or low-dose chemotherapy (n = 15), or induction chemotherapy (n = 8). This included idarubicin plus cytarabine (n = 3), high-dose cytarabine (n = 4), and fludarabine-based regimen (n = 1). Allogenic stem cell transplantation was offered to a single patient, who is alive at Day + 70. The outcome of patients was poor, with a median survival of 2.9 months (range, 0.6-20.1 mos), with no significant differences between palliation and intensive treatments. CONCLUSIONS: AL following PV has distinct clinical and biologic features. Outcome of patients is poor irrespective of the treatment employed.

Acute Disease↗
PubMed2000

Comparative cytogenetics of tapirs, genus tapirus (Perissodactyla, tapiridae).

Chromosomes of the four species of Tapirus were 2n = 52 in T. indicus, 2n = 76 in T. pinchaque, 2n = 80 in T. bairdii, and 2n = 80 in T. terrestris. The number of autosomal arms was 80-94. G-banded karyotypes indicated that a heterochromatic addition/deletion distinguished chromosomes 2 and 3 of T. bairdii and T. pinchaque, respectively. There were at least 13 conserved autosomes between the karyotypes of T. bairdii and T. terrestris, and at least 15 were conserved between T. bairdii and T. pinchaque. In G- and C-banded preparations, the X chromosomes of T. bairdii, T. indicus, and T. terrestris were identical, whereas the X chromosome of T. pinchaque differed from the X of the other species by a heterochromatic addition/deletion. The Y chromosome was a medium-sized to small acrocentric in T. bairdii, T. indicus, and T. pinchaque, but it was not positively identified in T. terrestris. There appeared to be fewer homologies between T. indicus and the three species occurring in Central and South America. Future cytogenetic studies of tapirs from the entire range of each of the four species might provide additional insight into their evolutionary biology and aid wildlife conservation efforts aimed at these threatened mammals.

Animals↗
PubMed1998

Comparative genomics: tracking chromosome evolution in the family ursidae using reciprocal chromosome painting.

The Ursidae family includes eight species, the karyotype of which diverges somewhat, in both chromosome number and morphology, from that of other families in the order Carnivora. The combination of consensus molecular phylogeny and high-resolution trypsin G-banded karyotype analysis has suggested that ancestral chromosomal fissions and at least two fusion events are associated with the development of the different ursid species. Here, we revisit this hypothesis by hybridizing reciprocal chromosome painting probes derived from the giant panda (Ailuropoda melanoleuca), domestic cat (Felis catus), and man (Homo sapiens) to representative bear species karyotypes. Comparative analysis of the different chromosome segment homologies allowed reconstruction of the genomic composition of a putative ancestral bear karyotype based upon the recognition of 39 chromosome segments defined by painting as the smallest conserved evolutionary unit segments (pSCEUS) among these species. The different pSCEUS combinations occurring among modern bear species support and extend the postulated sequence of chromosomal rearrangements and provide a framework to propose patterns of genome reorganization among carnivores and other mammal radiations.

Animals↗
PubMed1977

A chromosome survey of five species of Cassidinae (Coleoptera: Chrysomelidae).

Chromosome numbers and sex-determining mechanisms of five species of Cassida beetles from different Spanish sources are given. C. deflorata Suffr. and C. flaveola Thunb. show a 8(11) + Xyp formula, C. vibex L. 9(11) + Xyp, and C. margaritacea Schall. and C. viridis L., 14(11) + Xyp. These chromosomal findings are in agreement with the current morphological systematics of Cassida. The karyotypes of C. deflorata, C. vibex and C. viridis are constituted by metacentric chromosomes mostly, but there are clear differences in the total complement lengths between the three species. The possible tendencies in the chromosomal evolution of Cassidinae beetles are also discussed assuming a primitive karyotype of 18 chromosomes.

Animals↗
PubMed2006

Synaptonemal complexes and XY behavior in two species of Argentinian armadillos: Chaetophractus villosus and Dasypus hybridus (Xenarthra, Dasypodidae).

Spermatocytes from the two armadillo species, C. villosus and D. hybridus were studied in microspreads for synaptonemal complexes (SCs) and in thin sections for electron microscopy (EM). The complete SC karyotype generally agrees with previous reports on mitotic chromosomes, except for the sex chromosomes. The X chromosome is submetacentric in both species and the Y is the shortest one in C. villosus and the second shortest in D. hybridus, and an extremely acrocentric one. A SC is formed along the total length of the Y chromosome, and this SC persists along all the pachytene substages. A single recombination nodule (RN) is located in the region of the SC nearest to the attachment to the nuclear envelope. The lateral element (LE) of the X axis in the SC shows a wavy aspect in most of the SC length distant from the nuclear envelope. Nucleoli are attached to acrocentric or submetacentric bivalents, are visibly double in some cells, and in thin sections show an elaborate nucleolonema. Some differences in the XY are species-specific, as the higher degree of tangling and stronger heteropycnosis in D. hybridus. The effective, single crossover of the XY pair is highly localized, despite the permanence of a long tract of SC.

Animals↗
PubMed2004

B chromosomes are more frequent in mammals with acrocentric karyotypes: support for the theory of centromeric drive.

The chromosomes of mammals tend to be either mostly acrocentric (having one long arm) or mostly bi-armed, with few species having intermediate karyotypes. The theory of centromeric drive suggests that this observation reflects a bias during female meiosis, favouring either more centromeres or fewer, and that the direction of this bias changes frequently over evolutionary time. B chromosomes are selfish genetic elements found in some individuals within some species. B chromosomes are often harmful, but persist because they drive (i.e. they are transmitted more frequently than expected). We predicted that species with mainly acrocentric chromosomes would be more likely to harbour B chromosomes than those with mainly bi-armed chromosomes, because female meiosis would favour more centromeres over fewer in species with one-armed chromosomes. Our results show that B chromosomes are indeed more common in species with acrocentric chromosomes, across all mammals, among rodents, among non-rodents and in a test of independent taxonomic contrasts. These results provide independent evidence supporting the theory of centromeric drive and also help to explain the distribution of selfish DNA across species. In addition, we demonstrate an association between the shape of the B chromosomes and the shape of the typical ('A') chromosomes.

Animals↗
PubMed1989

Selection in natural and experimental populations of Drosophila pseudoobscura.

The inverted gene arrangements of Drosophila pseudoobscura were used by Th. Dobzhansky in pioneering analyses of natural selection. Recent experiments have shed light on the mechanisms of selection contributing to the balanced polymorphism for the gene arrangements. In experimental populations, both major components of fitness, viability and fertility, are frequency dependent, and rare genotypes often have a selective advantage. Viabilities are also density dependent. The frequency dependence and density dependence of the fitness components are not universal. Some karyotypes are strongly influenced by frequency or density, some are slightly influenced, and some do not appear to be influenced at all. The role of heterozygote advantage in the selection on the gene arrangements is not clear. It is probably one important element in the overall selection, but viability and fertility do not always show a heterozygote advantage. Viability and fertility components of selection seem to be about equally important in changing inversion frequencies. Male mating success is an important component of selection in natural populations, and in one population rare male karyotypes have been found to have a pronounced mating advantage.

Animals↗
PubMed1998

Cytogenetic analysis shows that carcinosarcomas of the breast are of monoclonal origin.

Carcinosarcoma of the breast is a rare biphasic neoplasm composed of a carcinomatous component contiguous or admixed with a pleomorphic spindle cell component. The issues of the histogenesis and clonal composition of carcinosarcomas have long been debated. We present the first cytogenetic characterization of mammary carcinosarcomas by analysis of eight tumor samples from two patients with this disease. In the first case, the same karyotypically complex clone, as well as evidence of clonal evolution, was found in samples from three separate areas of the primary tumor. The analysis of one intramammary and one axillary lymph node metastasis from the same patient, both showing only the sarcomatous tumor component, also revealed the common complex stemline and one of the two sidelines found in the primary tumor. The carcinosarcoma of the second patient contained six complex but karyotypically related clones unevenly distributed among the three samples examined. From this case, cells belonging to the carcinomatous and sarcomatous tumor components were separated by differential sedimentation and culturing in specific growth media. Analysis of both fractions showed largely the same karyotype, although one of the subclones was restricted to the epithelial component. Our findings indicate that the epithelial and mesenchymal components of mammary carcinosarcomas are both part of the neoplastic parenchyma and that they have evolved from a single common stem cell, in agreement with the hypothesis that the tumors are of monoclonal origin.

Breast Neoplasms↗
PubMed2001

Conserved chromosome segments in Hylobates hoolock revealed by human and H. leucogenys paint probes.

A complete comparative chromosome map of the white-browed gibbon (Hylobates hoolock, 2n = 38), white-cheeked gibbon (Hylobates leucogenys, 2n = 52), and human has been established by hybridising H. leucogenys chromosome-specific paints and human 24-colour paints onto H. hoolock metaphase chromosomes. In the 18 H. hoolock autosomes, we identified 62 conserved segments that showed DNA homology to regions of the 25 H. leucogenys autosomes. Numerous interchromosomal rearrangements differentiate the karyotypes of H. leucogenys and H. hoolock. Only H. hoolock chromosome 10 showed homology to one entire autosome of H. leucogenys. The hybridisation of human 24-colour paints not only confirmed most of the chromosome correspondences between human and H. hoolock established previously but also helped to correct five erroneous assignments and revealed three new segments. Our results demonstrate that the karyotypes of the extant gibbons have arisen mainly through extensive translocation events and that the karyotype of H. hoolock more closely resembles the ancestral karyotype of Hylobates, rather than the karyotype of H. leucogenys.

Animals↗
PubMed1988

Spontaneous in vitro neoplastic evolution of cultured Chinese hamster cells. Nucleolus organizing region activity.

Silver staining to demonstrate active nucleolus organizing regions (NORs) was performed at four different stages of the spontaneous tumorigenic progression in vitro of Chinese hamster WCHE/5 cells. The number of active NORs increased for fully transformed, highly tumorigenic, late passage cells. The increase of NOR material was due to additional NOR-bearing chromosomes or chromosome arms, i.e., trisomy 5, trisomy 8, and the marker chromosome i(3q). Intermediate stages of the neoplastic evolution showed changing patterns of NOR activity, but not an overall increase. We postulate that the increase of active rDNA enhances cell growth and provides undefined selective advantage, and that this supports our previous conclusion that selectable karyotype changes provide competitive advantages rather than being essential for neoplastic evolution in vitro.

Animals↗
PubMed1996

Cytogenetic analysis of aggressive meningiomas: possible diagnostic and prognostic implications.

BACKGROUND: Published karyotypes from aggressive (atypical and malignant) meningiomas are few, but suggest clonal evolution from benign tumors with monosomy 22 to aggressive forms with additional abnormalities. The goal of this study was to identify the most frequent karyotypic abnormalities associated with aggressive histopathology and biologic behavior. METHODS: Eight intracranial meningiomas exhibiting histologically atypical features at the time of intraoperative diagnosis were chosen for cytogenetic analysis. The study set was comprised entirely of histologically atypical meningiomas. Four were considered malignant; three on the basis of brain invasion and one due to extracranial metastases. None was histologically anaplastic. RESULTS: Chromosomal abnormalities were demonstrated in 6 cases (75%), 5 of which were complex (63%). Loss of chromosome 22 was identified in two cases, both of which were associated with additional aberrations. Abnormalities most frequently involved chromosomes 1 (63%), 3 (50%), and 6 (63%). Four cases (50%) had dicentric or ring chromosomes. An additional 47 previously reported karyotypes from atypical and malignant meningiomas were reviewed. Comparison with published karyotypes of 200 histologically benign meningiomas served to underscore the increased frequency of complex karyotypes, chromosome 1, 3, and 6 abnormalities, and telomeric associations in the aggressive tumors. Apparently normal karyotypes as well as monosomy 22 alone were more frequently associated with benign, nonatypical histopathology. CONCLUSIONS: These findings suggest a possible role for cytogenetic analysis in determining the prognosis and perhaps in refining the diagnosis of atypical or aggressive meningiomas. Further studies are necessary to determine the significance of complex karyotypes, chromosome 1, 3, and 6 abnormalities, and telomeric associations, particularly whether they portend a more aggressive clinical course in meningiomas lacking features of histologic atypia.

Adult↗