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PubMed1982

Chromosomal homology in southern Akodon.

Differential staining (G and C) of southern South American Akodon are presented. A. olivaceus, A. longipilis and A. sanborni all have the same karyotype (2n = 52, NF = 58). A virtually identical band sequence is observed. This situation is interpreted using the canalization model of chromosomal evolution which stresses an optimum karyotype for each adaptive zone. Despite the high degree of conservation of the chromosome structures, the specific status of these species is supported by maintenance of distinctness when they occur in areas of sympatry.

Animals↗
PubMed1980

Banding studies on six killer whales: an account of C-band polymorphism and G-band patterns.

The karyotypes of six killer whales were studied by banding techniques. A striking accumulation of C-heterochromatin has occurred in the Oricinus karyotype. The four telocentric pairs characteristic of the 2n = 44 cetacean karyotypes have become masked due to the accumulation of heterochromatin in the short arms. Conspicuous C-band polymorphism occurred in the materials studied, rendering each specimen karyotypically unique. Owing to the amount and variation of C-heterochromatin in the Orcinus karyotype, access to C-banded karyotypes was essential for the evaluation of the G-band pattern. The G-band pattern of Orcinus was found to be closely similar to that of Stenella. The results indicate an evolution of the Orcinus karyotype from the karyotypes characterizing other delphinids.

Animals↗
PubMed1991

Chromosome analysis of 96 uterine leiomyomas.

From September 1989 to May 1990, we attempted cytogenetic analysis on 96 uterine leiomyomas removed from 64 women. Of the 90 tumors in which analysis was successful, 59 had a normal karyotype while 31 had clonal abnormalities. The most common aberration (13 tumors) was 7q-, mostly del(7)(q21.2q31.2); in two tumors with +12 and t(12;14) as the primary abnormalities, the 7q- was obviously a secondary change since it was found only in a subclone. A t(12;14)(q14-15;q23-24) was detected in two tumors, complex aberrations involving both 12q14-15 and 14q23-24 were also present in two, and rearrangements of 12q without concomitant 14q changes were seen in another two myomas. Rearrangements of 6p were present in five tumors, and trisomy 12 was found in two. More than one abnormality could be detected in 17 leiomyomas. Evidence of clonal evolution in the form of subclones was found in eight tumors, all of which were cellular and had histologically detectable mitotic activity. In addition to their clonal complexity, these myomas also frequently exhibited clonal telomeric associations (four tumors) and ring chromosome formation (three tumors; twice affecting chromosome 1). Monosomy 22 occurred as a secondary abnormality in three tumors; it, too, may reflect a preferred pathway in the karyotypic evolution of uterine leiomyomas.

Chromosome Aberrations↗
PubMed1974

Banded marker chromosomes as indicators of intraspecies cellular contamination.

Chromosome banding revealed marked chromosomes characteristic of HeLa cells in cultures designated HEK, HEK/HRV, HBT-3, HBT-39B, MA160, and a strain of SA-4TxS-Husa(1). Ohter HeLa cell characteristics found were glucose-6-phosphate dehydrogense type A mobility and lack the Y chromosome. Conventional chromosome analysis and immunological and enzymatic technique serve to monitor species specificity and racial origin of the donor. Chromosome banding, however, can monitor intralinear karyotype peculiarity and its evolution during long-term cultivation.

Cell Line↗
PubMed2001

Karyotype analysis in Brachiaria (Poaceae) species.

This is the first karyotype characterization of Brachiaria species. Twelve accessions belonging to five species were analysed. The basic chromosome number was x = 9 and 7, the same reported for the tribe Paniceae. Variations in the chromosome number were observed in B. decumbens (2n = 18; 36) and B. humidicola (2n = 36; 42; 54). Chromosome numbers of 2n = 18 in B. ruziziensis and 2n = 36 in B. brizantha and B. jubata were recorded. Inter- and intraspecific karyotype differentiation of the accessions analysed was facilitated by variations in karyotypic symmetry. The karyotypes were generally considered symmetrical, with a tendency to asymmetry in the direction of the polyploids. It is suggested that addition, deletions and mainly polyploidy have been the most direct causes involved in the chromosome evolution of this genus.

Chromosomes↗
PubMed2001

Cytochrome b sequences reveal Acomys minous (Rodentia, Muridae) paraphyly and answer the question about the ancestral karyotype of Acomys dimidiatus.

Sequences of the cytochrome b (cyt b) mitochondrial gene show that the spiny mouse Acomys from Crete, known as the endemic species A. minous, is composed of two distinct maternal lineages ("A" and "B"). Group "A" sequences cluster with A. nesiotes (Cyprus) and group "B" sequences cluster with A. cilicicus (Turkey), which is evidence of paraphyly of A. minous in regard to these two species. From cyt b sequences, the three taxa are very closely related to A. cahirinus (Egypt): the maximum divergence found among these sequences is 1.6%, which is equivalent to the intraspecific diversity observed in other Acomys species. Paleozoology evidenced that man unintentionally introduced Acomys into Crete and Cyprus during antiquity. The divergence time between Acomys cyt b sequences found in Crete was estimated at 0.4 Myr, which means that the diversity observed did not appear after the introduction but reflects a much more ancient polymorphism. Cytochrome b phylogeny and cytogenetic data together comprise evidence that, within the species A. dimidiatus (Saudi Arabia, Israel, Egypt), it is the karyotypic form with 36 chromosomes that derives from the form with 38 chromosomes, due to a single acrocentric fusion.

Animals↗
PubMed2002

Non-random radial arrangements of interphase chromosome territories: evolutionary considerations and functional implications.

In the nucleus of animal and plant cells individual chromosomes maintain a compartmentalized structure. Chromosome territories (CTs), as these structures were named by Theodor Boveri, are essential components of the higher-order chromatin architecture. Recent studies in mammals and non-mammalian vertebrates indicate that the radial position of a given CT (or segments thereof) is correlated with its size, its gene-density and its replication timing. As a representative case, chicken cell nuclei show highly consistent radial chromatin arrangements: gene-rich, early replicating microchromosomes are clustered within the nuclear interior, while gene-poor, later replicating macrochromosomes are preferentially located at the nuclear periphery. In humans, chromosomes 18 and 19 (HSA18 and 19) territories that are of similar size show a distinctly different position in the cell nuclei of lymphocytes and lymphoblastoid cells: the gene-rich and early replicating HSA19 CTs are typically found close to the nuclear center, while the gene-poor and later replicating HSA18 CTs are preferentially located at the nuclear periphery. Recent comparative maps between human and chicken chromosomes revealed that the chicken macrochromosomes 2 and Z contain the genes homologous to HSA18, while the genes on HSA19 are located onto the chicken microchromosomes. These data lend tentative support to the hypothesis that differences in the radial nuclear positions of gene-rich, early replicating and gene-poor, later replicating chromatin have been evolutionarily conserved during a period of more than 300 million years irrespective of the evolution of highly divergent karyotypes between humans and chicken.

Animals↗
PubMed1999

Defining the ancestral karyotype of all primates by multidirectional chromosome painting between tree shrews, lemurs and humans.

We used multidirectional chromosome painting with probes derived by bivariate fluorescence-activated flow sorting of chromosomes from human, black lemur (Eulemur macaco macaco) and tree shrew (Tupaia belangeri, order Scandentia) to better define the karyological relationship of tree shrews and primates. An assumed close relationship between tree shrews and primates also assists in the reconstruction of the ancestral primate karyotype taking the tree shrew as an "outgroup" species. The results indicate that T. belangeri has a highly derived karyotype. Tandem fusions or fissions of chromosomal segments seem to be the predominant mechanism in the evolution of this tree shrew karyotype. The 22 human autosomal painting probes delineated 40 different segments, which is in the range found in most mammals analyzed by chromosome painting up to now. There were no reciprocal translocations that would distinguish the karyotype of the tree shrew from an assumed primitive primate karyotype. This karyotype would have included the chromosomal forms 1a, 1b, 2a, 2b, 3/21, 4-11, 12a/22a, 12b/22b, 13, 14/15, 16a, 16b, 17, 18, 19a, 19b, 20 and X and Y and had a diploid chromosome number of 2n=50. Of these forms, chromosomes 1a, 1b, 4, 8, 12a/22a, and 12b/22b may be common derived characters that would link the tree shrew with primates. To define the exact phylogenetic relationships of the tree shrews and the genomic rearrangements that gave rise to the primates and eventually to humans further chromosome painting in Rodentia, Lagomorpha, Dermoptera and Chiroptera is needed, but many of the landmarks of genomic evolution are now known.

Animals↗
PubMed1987

Progression in a chemically induced transplantable human pancreas carcinoma.

A methylnitrosourea (MNU)-induced transplantable human pancreas carcinoma was examined, at 3, 12, 18 and 36 months after its development, for growth and invasiveness in nude mice, karyotypic alteration and the evolution of marker chromosomes. Progression in tumorigenicity and invasiveness of cells were evident by a significant increase in tumor diameters produced within 8 weeks by the cells at 36 months as compared to those developed by cells from 3-month-old cell lines. Chromosome analysis at 3 months showed normal 46 XX karyotype in about 80% and minor anomalies in 20% of the cells. At 12, 18 and 36 months, all cells were hyperdiploid with 53-61 chromosomes and several abnormal marker chromosomes. Marker chromosomes showed non-reciprocal translocations, deletions, inversion and isochromosomes. The absence of chromosome 13 from the earlier stage onward may have resulted in the loss of genes which suppress tumorigenicity. The increase in homogeneously staining regions of marker chromosome 3 at later stages appears to parallel the augmentation in tumor growth and mitotic indices.

Animals↗
PubMed1999

Chromosomal aberrations identified in culture of squamous carcinomas are confirmed by fluorescence in situ hybridisation.

AIMS: Chromosomal aberrations in tumour cells are often not discernable by direct analysis. Although cell culture allows qualitative analysis of the karyotype, potential selection and evolution during growth in vitro may yield misleading data. To determine whether aberrations observed in vitro are representative of the original lesion, chromosomal aberrations found after prolonged growth in vitro of two squamous cell carcinomas of the head and neck (SSCHN) were evaluated with fluorescence in situ hybridisation (FISH) on the original tumour nuclei. METHODS: Specific karyotypic aberrations identified in cultures of two squamous cell carcinomas were targets for FISH analysis on tumour sections. Chromosome painting mixtures were selected based on in vitro karyotypic data. FISH was performed on cultured interphase and metaphase cells, and on histological sections from the original tumours. RESULTS: The 9cen and 17cen probes yielded FISH signals consistent with the aneusomies predicted for the respective chromosomes from the culture karyotypes. Whole chromosome 9 paint confirmed the prior existence in the tumours of i(9p) and i(9q), although only the latter hybridised with the 9cen probe. FISH data also supported in vivo representation of the diploid and tetraploid tumour subclones observed in cultures. In tumour HFH-SCC-8a, FISH results were generally concordant between cultured interphase and metaphase cells and the histological sections, and improved the interpretation of marker chromosomes identified in culture. CONCLUSION: The karyotypes obtained in these cases after prolonged passage in culture were consistent with the genetic alterations in the original tumours.

Carcinoma, Squamous Cell↗
PubMed1990

Chromosomal evolution in Callithrix emiliae.

We studied the karyotype of specimens of Callithrix emiliae (Callithricidae, Primates) from Rondonia, Brazil. Comparison with the karyotype of Callithrix jacchus showed that, even though these two species show many karyotypic similarities, they differ by a Robertsonian translocation, a paracentric inversion and large-scale addition of heterochromatin. The C. emiliae species appears to be in an active phase of chromosome evolution by the addition of constitutive heterochromatin.

Animals↗
PubMed1976

Long-term cytogenetic studies in acute leukemia of children; the nature of relapse.

Sequential long-term cytogenetic studies in 71 children with acute leukemia were designed to investigate the nature of relapse after prolonged remission. In the overwhelming majority of the cases the findings suggested clonal identity of the leukemic cell population in relapse with that studied at the onset of the disease, notwithstanding considerable karyotypic instability in almost half of the patients. In a small minority an independent origin of the relapse clone could not be excluded on cytogenetic grounds but was considered unlikely, since mechanisms capable of accounting for the changes observed in these patients could be demonstrated in other cases. The persistence of diploid leukemic cells in the presence of an aneuploid subclone was demonstrated in the relapse bone marrow and/or spinal fluid in all active phases of the disease. On this basis the conversion from an aneuploid to a predominantly or exclusively diploid karyotype could be visualized, and a new model of clonal evolution, involving repetitive formation of abnormal karyotypes from a surviving diploid clone could be suggested.

Adolescent↗
PubMed2002

[Comparative chromosome painting shows the red panda (Ailurus fulgens) has a highly conserved karyotype].

We have established a comparative chromosome map between red panda (Ailurus fulgens, 2n = 36) and dog by chromosome painting with biotin-labelled chromosome-specific probes of the dog. Dog probes specific for the 38 automates delineated 71 homologous segments in the metaphase chromosomes of red panda. Of the 38 autosomal paints, 18 probes each delineated one homologous segment in red panda genome, while the other 20 ones each detected two to five homologous segments. The dog X chromosome-specific paint delineated the whole X chromosome of the red panda. The results indicate that at least 28 fissions (breaks), 49 fusions and 4 inversions were needed to "convert" the dog karyotype to that of the red panda, suggesting that extensive chromosome rearrangements differentiate the karyotypes of red panda and dog. Based on the established comparative chromosome homologies of dog and domestic cat, we could infer that there were 26 segments of conserved synteny between red panda and domestic cat. Comparative analysis of the distribution patterns of conserved segments defined by dog paints in red panda and domestic cat genomes revealed at least 2 cryptic inversions in two large chromosomal regions of conserved synteny between red panda and domestic cat. The karyotype of red panda shows high degree of homology with that of domestic cat.

Animals↗
PubMed1988

On the highest chromosome number in mammals.

The mitotic and meiotic chromosomes of the semiaquatic rodent Ichthyomys pittieri (Rodentia, Cricetinae) from Venezuela were analyzed by means of conventional staining and several banding techniques. The diploid chromosome number of this rare species is 2n = 92, which is the highest value known for mammals. It is assumed that this exceptionally high chromosome number is the result of repeated centric fissions. The karyotype of I. pittieri was compared with that of Anotomys leander, for which a diploid number of 2n = 92 has also been reported. The karyological relationships existing within the Neotropical Cricetidae are summarized.

Animals↗
PubMed2001

Karyotype relationships between distantly related marsupials from South America and Australia.

Reciprocal chromosome painting and G-banding were used to compare the karyotypes of three Australian marsupials (Sminthopsis crassicaudata, Macropus eugenii, Trichosurus vulpecula) and one South American marsupial (Monodelphis domestica). The results revealed only a limited number of rearrangements between these species and that the four karyotypes can be described as different combinations of fifteen conserved segments. Five chromosomes are totally conserved between M. domestica (pairs 1, 2, 5, 8 and the X) and the presumed 2n = 14 Australian ancestral karyotype, while M. domestica pairs 3 and 6 and 4 and 7 would have been involved in fusion/fission rearrangements. Chromosome comparisons are presented in a chromosome homology map. Although the species studied diverged 70 million years ago, the karyotype of Monodelphis domestica is highly conserved in relation to those of Australian marsupials.

Animals↗
PubMed1999

Does evolution reduce the body size? A study of the four members of newly evolved nasuta-albomicans complex of Drosophila.

Our long range interracial hybridization experiments between a pair of cross fertile races, Drosophila nasuta (2n = 8) and D. albomicans (2n = 6) have resulted in the evolution of two new karyotypic strains under laboratory conditions, which are named as Cytorace 1 and Cytorace 2. These Cytoraces harbor chromosomes from both parents. Here, we compare the body size of the parental races and newly evolved Cytoraces and the relationship between the body size and fitness. Analysis reveals that the parental races have reduced fertility and are larger in body size than newly evolved Cytoraces. Thus, the newly evolved Cytoraces show reduced body size and better fitness in the course of their evolution.

Animals↗