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Results for “karyotype evolution”

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At least 667 records · Page 37Linked to original sources
PubMed1999

Kodamaea nitidulidarum, Candida restingae and Kodamaea anthophila, three new related yeast species from ephemeral flowers.

Three new yeast species were discovered during studies of yeasts associated with ephemeral flowers in Brazil, Australia and Hawaii. Their physiological and morphological similarity to Kodamaea (Pichia) ohmeri suggested a possible relationship to that species, which was confirmed by rDNA sequencing. Kodamaea nitidulidarum and Candida restingae were found in cactus flowers and associated nitidulid beetles in sand dune ecosystems (restinga) of South-eastern Brazil. Over 350 strains of Kodamaea anthophila were isolated from Hibiscus and morning glory flowers (Ipomoea spp.) in Australia, and from associated nitidulid beetles and Drosophila hibisci. A single isolate came from a beach morning glory in Hawaii. Expansion of the genus Kodamaea to three species modified the existing definition of the genus only slightly. The type and isotype strains are as follows: K. nitidulidarum strains UFMG96-272T (h+; CBS 8491T) and UFMG96-394I (h-; CBS 8492I); Candida restingae UFMG96-276T (CBS 8493T); K. anthophila strains UWO(PS)95-602.1T (h+; CBS 8494T), UWO(PS)91-893.2I (h-; CBS 8495I) and UWO(PS)95-725.1I (h-; CBS 8496I).

Base Sequence↗
PubMed1977

Albumin phylogeny for clawed frogs (Xenopus).

Comparisons of albumin indicate that the frogs commonly used by North American molecular and developmental biologists under the name of Xenopus muelleri belong to another species, X. borealis. Phylogenetic analysis of the albumin data reveals two major groups of Xenopus species, one containing only X. tropicalis and the other, called the X. laevis grou, containing the remaining species of the genus. The phylogenetic tree, in conjunction with evidence from chromosomes and DNA content, leads to the hypothesis that total genome duplication occurred in the common ancestor of the X. laevis group.

Animals↗
PubMed1977

Heteromorphic sex chromosomes in male rainbow trout.

A pair of subtelocentric chromosomes differs in the size of the short arm in male, but not female, rainbow trout (Salmo gairdneri). The morphological similarity of the X and Y chromosomes, and the observation of Y chromosomes intermediate between the X and normal Y, suggest that the sex chromosomes are at an early stage of differentiation in this species.

Animals↗
PubMed1992

Polytene chromosomes of the Old World screwworm fly (Chrysomya bezziana) and its evolutionary relationships with Lucilia cuprina and Cochliomyia hominivorax (Diptera: Calliphoridae).

Standard polytene chromosome maps for the Old World screwsworm fly, Chrysomya bezziana, are presented. Good quality polytene chromosomes obtainable from pupal trichogen cells allow detailed analysis of autosomal euchromatin. The sex chromosomes are represented by irregular heterochromatic structures resembling those described previously in trichogen polytene chromosomes of the Australian sheep blowfly, Lucilia cuprina. A high degree of homology with the banding pattern of L. cuprina polytene chromosomes allowed direct recognition of approximately 60% of the L. cuprina complement in the C. bezziana maps. A further 13% may be homologous. The extensive homology observed is discussed in relation to the rate of chromosome rearrangement and conservation of karyotype elements in the evolution of Calliphorid flies. The observed conservation in polytene banding patterns should facilitate construction of phylogenies over a number of generic groups.

Animals↗
PubMed1995

De-novo acute myeloid leukemia with trilineage myelodysplasia (AML/TMDS) and myelodysplastic remission marrow (AML/MRM).

Trilineage myelodysplasia (TMDS) in de novo acute myeloid leukemia (AML) at initial diagnosis and during remission has not been well recognized yet. In this review we describe the characteristics of de novo AML with TMDS (AML/TMDS) and with myelodysplastic remission marrow (AML/MRM) in view of the in vivo and in vitro disease progression. AML/TMDS was found in ten (10.4%) of 96 patients with de novo AML at initial diagnosis and AML/MRM were also observed in three (5.0%) out of 60 cases in remission after chemotherapy in our hospital between 1984 and 1992. Abnormal karyotypes were seen in six of nine AML/TMDS patients and all of the three AML/MRM. Karyotypic changes occurred in two of AML/TMDS and two of AML/MRM during their clinical course. Using the long term bone marrow culture (LTBMC) system that allowed abnormal clones to survive preferentially to the clone of normal karyotype, latent clones were detected in three patients with AML/TMDS and three of AML/MRM as in the cases of myelodysplastic syndrome (MDS) and AML transformed from MDS (MDS/AML) but not in the typical AML without myelodysplastic changes. Four of these cases exhibited the same karyotypes as seen during the clinical course. Primary abnormal karyotypes prior to clonal evolution were also observed in two of the AML/MRM. Taken together, both AML/TMDS and AML/MRM are similar to MDS/AML with respect to their myelodysplastic background and potential for disease progression and may have progressed to AML from the preceding disease status more rapidly than MDS/AML.

Acute Disease↗
PubMed2000

Chromosome evolution in the genus Poecilimon (Orthoptera, Tettigonioidea, Phaneropteridae).

Cytotaxonomic analysis of 20 species and subspecies of the genus Poecilimon using C-banding pattern, chiasma frequency, and morphometric characteristics of the chromosomes were described. Using a cladistic analysis the chromosome data provided a basis to produce a phylogenetic tree which was compared with a tree based on morphological characters and DNA sequence data. There are important differences in the grouping of data sets to species obtained on the basis of morphology/DNA analyses and that based on chromosomes. The explanation of the differences between C-banding patterns and taxonomic proximity is probably that the C-banding pattern changes quickly as the result of the high degree of variation of constitutive heterochromatin.

Animals↗
PubMed2002

Episodic chromosomal evolution in Planipapillus (Onychophora: Peripatopsidae): a phylogenetic approach to evolutionary dynamics and speciation.

Planipapillus, a clade of onychophorans from southeastern Australia, exhibits substantial chromosomal variation. In the context of a robust phylogeny based on nuclear and mitochondrial sequence data, we evaluate models of chromosomal evolution and speciation that differ in the roles assigned to selection, mutation, and drift. Permutation tests suggest that all chromosome rearrangements in the clade have been centric fusions and, on the basis of parsimony and maximum-likelihood methods with independent estimates of branch lengths, we conclude that at least 31 centric fusions have been fixed in Planipapillus. A likelihood-ratio test approach, which is independent of our point estimates of ancestral states, rejects an evolutionary model in which the mutation rate is constant and centric fusions are effectively neutral. In contrast to the nucleotide sequence data, which are consistent with neutrality and rate constancy, centric fusions in Planipapillus are underdominant, spontaneous fusion rates vary among lineages, or both. We predict an inverse relationship between rates of chromosomal evolution and historical population size. Chromosomal evolution may play a role in speciation in Planipapillus, both by interactions between centric fusions with monobrachial homology and by the accumulation of multiple weakly underdominant fusions.

Animals↗
PubMed1984

Chromosome order--possible implications for development.

Chromosomes are arranged in ordered haploid sets around the centre of the metaphase plate at mitosis in several grass species and hybrids. Each chromosome is in a fixed mean position relative to other, heterologous chromosomes, this order can be predicted using Bennett's model, and is clearly demonstrated from reconstructions of electron micrographs of serial sections (see Heslop-Harrison & Bennett, 1983a,b,c). The nucleus contains spatial domains of genes with similar functions. Chromosomes with major effects on nuclear behaviour--division or meiotic pairing--may be at special positions in the order. Changing spatial relationships of chromosomes with respect both to each other and the nuclear envelope (during the cell cycle and during development) may affect cell differentiation and gene activity. Chromosome order may have implications for the control of development within the nucleus and the organism. Order may constrain karyotype and hence species evolution.

Cell Differentiation↗
PubMed1983

Chromosome identification of the rusty-spotted cat (Felis rubiginosa): one more down and four to go.

The chromosomes of the rusty-spotted cat, Felis rubiginosa, of Sri Lanka (Ceylon) were analyzed. Although the 38-chromosome complement of F rubiginosa closely resembles that of several other species, it seems to be unique with only minor variations in the D and F chromosomes. This reduces, from 5 to 4, the number of the 37 recognized world feline species not yet cytogenetically studied. Despite great differences in size and distribution, the feline species of the world are one of the most homogenous families of mammals, with only subtle chromosomal differences separating most species. By comparative cytogenetic analyses, it is becoming possible to map the probable evolutionary pathway of the world's cats.

Animals↗
PubMed1983

Spontaneous neoplastic evolution of Chinese hamster cells in culture: multistep progression of karyotype.

Chromosomes from successive passages of a Chinese hamster cell strain (WCHE/5) that spontaneously progressed from a euploid primary cell culture to a heteroploid tumorigenic cell line were isolated and analyzed by Giemsa banding and high-resolution flow karyotype analysis. The frequency and identification of aneuploid and marker chromosomes were determined at both pre- and postcrisis culture stages and pre- and posttumorigenic stages. The combination of Giemsa banding and flow karyotypes provided detailed analysis of karyotype instability at each stage of cell culture progression. Aneuploidy (trisomy of chromosome 5) preceded the appearance of tumorigenicity in nude mice as well as in vitro indicators of neoplasia. The four stages of neoplastic progression defined in the previous paper correlated with a steady progression in karyotypic instability, including, in sequence: trisomy of chromosome 5; an 8q marker chromosome; a 3q+ insertion; and trisomy of chromosome 8. Additional changes continued to appear as the cells acquired classical properties of in vitro transformation.

Animals↗