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Results for “karyotype evolution”

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PubMed1997

Evolution of the black muntjac (Muntiacus crinifrons) karyotype revealed by comparative chromosome painting.

The black muntjac (Muntiacus crinifrons) has an unusual karyotype of 2n = 8 in females and 2n = 9 in males. We have studied the evolution of this karyotype by hybridising chromosome-specific paints derived from flow-sorted chromosomes of the Chinese muntjac (M. reevesi, 2n = 46) to chromosomes of the black muntjac. The hybridisation pattern allowed us to infer chromosomal homologies between these two species. Tandem and centromeric fusions, reciprocal translocations, and insertions are involved in the reduction of the diploid number from 2n = 46 to 2n = 8, 9. The painting patterns further show complex chromosomal rearrangements in the male black muntjac which involve more than half the karyotype, including both sex chromosomes. Since early meiosis is reported to be normal without any visible inversion loops of the synaptonemal complex, the observed chromosomal rearrangements would lead to heterosynapsis and, therefore, leave a large fraction of the male black muntjac karyotype balanced between the two sexes.

Animals↗
PubMed2006

Karyotypic differences and evolutionary tendencies of some species from the subgenus Obliquodesmus Mlad. of genus Scenedesmus Meyen (Chlorophyta, Chlorococcales).

Karyotype structures of Scenedesmus acuminatus (Lagerch.) Chod. and Scenedesmus pectinatus Meyen are compared. The karyotype of S. acuminatus (n = 5) is described for the first time. It reveals four large metacentric and one large submetacentric chromosomes (4M + 1SM). The established karyotype differences have been helpful in clarifying the taxonomic position of these two species. The cytological analyses of other related clonal cultures suggest an evolutionary transition from S. pectinatus towards S. regularis through S. pectinatus f. regularis, which correlates with the morphological data about their variability. These results are discussed from the cytogenetic, morphological and evolutionary point of view. On the basis of the karyotypic analysis, it was confirmed that from a taxonomic point of view S. pectinatus, S. acuminatus and S. regularis are separate biological species.

Biological Evolution↗
PubMed1999

Karyotype relationships between four distantly related marsupials revealed by reciprocal chromosome painting.

Marsupial karyotypes have shown extensive conservation even between distantly related groups with a high diversity of life forms and reproductive biology. Banding analysis has been the main test for assessing their homologies and chromosome rearrangements. More recently, cross-species reciprocal chromosome painting has been developed and applied to several mammalian species and has shown homologies and rearrangements not revealed by banding analysis. Karyotype relationships between four marsupial species, Sminthopsis crassicaudata, Potorous tridactylus, Trichosurus vulpecula and Macropus eugenii, which are from different families in two orders, were investigated and presented in the form of comparative chromosome maps. These show that only a limited number of chromosomal rearrangements have occurred during their evolution. A karyotype phylogeny of the four marsupials was derived from these maps. A comparison between published gene location and the comparative chromosome maps for these species is presented and inconsistencies with previous gene mapping data indicated.

Animals↗
PubMed1995

Karyotypic analysis of three species of Phasianidae (Galliformes: Aves).

The karyology of the partridges Francolinus francolinus asiae (2n = 70) and F. pondicerianus interpositus (2n = 68) and the Japanese quail Coturnix coturnix japonica (2n = 78) was investigated. The frequency distribution of the diploid number of chromosomes was tabulated and the most frequent number was taken to be the diploid number. All species showed a bimodal karyotype and the variation in the number of chromosomes was attributed to the macrochromosomes, although twelve macrochromosomes were present in all the species. Female heterogamety revealed that ZZ male:ZW female sex chromosome mechanism was present. The structure and behaviour of chromosomes during mitosis are described and the evolution of karyotype and cytotaxonomic considerations discussed.

Animals↗
PubMed1985

Cytogenetic findings in childhood acute lymphoblastic leukemia.

Chromosome studies were performed on the bone marrow cells of 42 children with newly diagnosed acute lymphoblastic leukemia (ALL). All the children were subsequently treated with the same protocol. Chromosomal abnormalities were found in 25 patients, i.e., in 59.5% of the cases. Hyperdiploidy was observed in 21.4% hypodiploidy in 14.3%, and pseudodiploidy in 23.8% of the children. The most frequent structural aberrations were translocations, which were found in half of the patients with abnormal karyotypes. Chromosomes #5, #6, #7, #9, #14, #17, and #21 were involved in different types of changes most frequently. Because these findings correspond with observations published by others, they can be regarded as evidence of nonrandom involvement of these chromosomes in rearrangements in ALL. Special attention should be also paid to the deletion of 6q, which seems to be relatively common in ALL. In 12 cases, clonal evolution of karyotypic changes was observed.

Adolescent↗
PubMed2006

The karyotypes of the thorny catfishes Wertheimeria maculata Steindachner, 1877 and Hassar wilderi Kindle, 1895 (Siluriformes: Doradidae) and their relevance in doradids chromosomal evolution.

We studied the karyotypes of two doradids, the rare and endangered Wertheimeria maculata and a derived Amazonian species, Hassar wilderi. Cytogenetic characterization was assessed using conventional staining (Giemsa), C-banding, and NOR banding. Both species had 2n = 58 chromosomes but differed in their chromosome formulae, 24 m + 14sm + 8st + 12a for W. maculata and 32 m + 16sm + 10st for H. wilderi. In W. maculata heterochromatin was mainly telomeric, and three chromosomes had a fully heterochromatic arm; in H. wilderi heterochromatin was also predominantly telomeric and evident in many more chromosomes. Hassar wilderi also presented one pair of homologues with a fully heterochromatic arm. In both species, nucleolar organizer regions were restricted to one pair of subtelocentric chromosomes. Assuming a basal position for W. maculata, we hypothesized that underlying conserved diploid and NOR-bearing chromosome numbers, chromosomal evolution in doradids has involved pericentric inversions and an increase of heterochromatic blocks.

Animals↗
PubMed1991

High risk myelodysplastic syndrome coexistent with chronic lymphocytic leukemia for more than 9 years: inhibition of the myeloid clone by the lymphoid clone?

We describe a patient in whom the concomitant diagnosis of refractory anemia with excess of blasts (16% on initial marrow examination) and chronic lymphocytic leukemia was made more than 9 years ago. The myeloid clone showed a complex karyotypic abnormality. Evolution has so far been remarkably stable, without transformation into acute leukemia. Clonogenic assays showed that patient's serum inhibited the patient's own granulocyte-macrophage colony-forming units (CFU-GM). This inhibition was also present for a control subject's CFU-GM and acute myeloid leukemia clonogenic cells. This raises the problem of a down-regulation of the myeloid clone by the malignant lymphoid clone in this patient, and the possible mechanisms for this are discussed.

Bone Marrow↗
PubMed1985

The pattern and clinical significance of karyotypic abnormalities in patients with idiopathic and postpolycythemic myelofibrosis.

Six of eight (75%) patients with postpolycythemic myelofibrosis (PPMF) and 11 of 20 (55%) patients with idiopathic myelofibrosis (MF), seen at the University of Chicago, had abnormal karyotypes in cells of bone marrow origin. The specific chromosomal findings and their clinical significance in these patients were analyzed. A review of the literature added the findings from abnormal karyotype studies in 10 patients with PPMF and 36 patients with MF to this series. The demonstration of an increased frequency of cytogenetic abnormalities after cytotoxic therapy in polycythemia vera (PV) implies that such therapy may have a role in the development of chromosomal changes seen in treated PV and PPMF. The cytogenetic abnormalities in MF appear to be unrelated to therapy except possibly for an association with partial or complete losses of chromosome 5 or 7. Trisomy 8 is the only finding that is more common in MF than in PPMF. Other abnormalities were more common in PPMF, particularly 20q-, loss of 7 or 7q-, and trisomy 9, and to a lesser extent trisomy 1q and 5q-. Cytogenetic abnormalities do not show a pattern that can be used to distinguish between PPMF and MF, nor are they useful in the prognosis of MF or in initial studies in PPMF. PPMF does appear to have a higher tendency toward leukemic transformation than does MF, and an evolution in karyotype appears to have serious prognostic implications in PPMF in regard to this transition.

Adult↗
PubMed1994

Clonal structural chromosome aberrations in fibrous dysplasia.

Cytogenetic analysis of short-term cultures from a case of monostotic fibrous dysplasia in a 14-year-old girl revealed multiple clonal structural rearrangements with evidence of clonal evolution. The karyotype was 46,XX,del(3)(q27),add(10)(q22),add(12)(p13)/46,idem,t(3;8)(p21;q13 ),add(10) (q26),der(15)del(15)del(15)(q15q22)ins(15;?) q15;?)/46,id em,-X,+2,t(3;8),add(10),der(15). The finding of clonal structural aberrations suggests that fibrous dysplasia is a neoplastic lesion which develops as the result of somatic mutations.

Adolescent↗
PubMed1992

Pentasomy 21 in leukemia complicating Diamond-Blackfan anemia.

We present the cytogenetic pattern of a leukemic infant with Diamond-Blackfan anemia (DBA). The karyotype was characterized by clonal evolution involving consecutive gains of chromosome 21 up to pentasomy. No chromosomal changes were present in normal lymphocytes. Such a karyotype evolution has been described in some cases of acute leukemia associated with Down Syndrome, but rarely in non-Down cases.

Chromosomes, Human, Pair 21↗
PubMed2003

Localization of 5S rRNA loci in three coregonid species (Salmonidae).

In the present study the chromosome distribution of the 5S rDNA loci and its relation to the major rDNA genes were investigated in three Coregonid species (Salmonidae): Coregonus lavaretus, Coregonus peled and Coregonus albula, a family which has experienced large karyotype rearrangements along its evolution starting from a tetraploid ancestor. 5S PRINS/CMA3 sequential staining together with previous data enabled us to locate 5S rRNA genes and nucleolar organizer regions (NORs) in the three species analyzed. PRINS revealed the 5S rDNA cluster at the distal part of the long arm of a similar submetacentric chromosome pair in the three species. Our data indicate that 5S rDNA clusters have probably conserved chromosomal location in the genus Coregonus, whereas 45S rDNA (NOR) sites are clearly differentiated, from a single locus in C. peled, to multiple loci in C. lavaretus and highly polymorphic multichromosomal location in C. albula.

Animals↗
PubMed1997

Cytogenetics of collared lemmings (Dicrostonyx groenlandicus). I. Meiotic behavior and evolution of the neo-XY sex-chromosome system.

Electron-microscopic analysis of surface-spread synaptonemal complexes at pachynema and light-microscopic analysis of chromosomal configurations at diakinesis/metaphase I corroborate the hypothesized neo-XY derivation of the sex chromosomes of Dicrostonyx groenlandicus. Although an intact neo-XY pairing configuration was observed in a relatively small percentage of the pachytene cells in each individual, the high incidence of neo-XY bivalents at diakinesis/metaphase I suggests that the other observed pachytene configurations were artifacts of the physical stresses of the surface-spreading procedure. The very low frequency (0.6%) of univalent neo-X and neo-Y chromosomes at diakinesis and metaphase I is attributable to consistent synapsis and recombination between their homologous autosomally derived segments. The resultant stability of the sex bivalent through metaphase I may have increased the efficacy of sex-chromosome segregation, and thereby played a mechanistic role in the evolutionary incorporation of the neo-XY sex-chromosome constitution in D. groenlandicus.

Animals↗
PubMed1976

Satellite DNA and cytogenetic evolution. DNA quantity, satellite DNA and karyotypic variations in kangaroo rats (genus Dipodomys).

The genus Dipodomys (kangaroo rats) exhibits major interspecies variations in the proportions of highly reiterated satellite DNA sequences in the genome as well as in the chromosome number and the proportions of uni-armed and bi-armed chromosomes. For nearly all of the approximately 22 species of the genus and several subspecies, liver DNA was distributed in neutral CsCl buoyant density gradients into four fractions; principal DNA (1.698 g/ml), intermediate-density DNA (1.702 G/ML), MS satellite (1.707 g/ml) and HS (heavy satellites (1.713 g/ml). The total nuclear DNA content of diploid liver cells measured in eleven species by quantitative cytophotometry, ranged from 6.9 to 10.9 pg. These data were correlated with known features of the karotypes of individual species. The salient findings were: (1) that interspecies variations in diploid chromosome number cluster at 52-54, 60-64 and 70-72 (2) that high total nuclear DNA was associated with high chromosome number, and with relatively large amounts of satellite DNA (3) that a high ratio of HS satellites to intermediate-density DNA was generally correlated with a predominance of metacentric and submetacentric chromosomes (high fundamental number). The relationships of satellite DNA to karyotype structure reveal a new level of hierarchy in the genome that appears capable of exerting global control over environmental adaptation and the evolution of new species. This mechanism is consistent with recent hypotheses that changes in the macro-structure of the genome are more important than point mutations in facilitating the rapid phases of animal evolution.

Animals↗