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PubMed2003

Chromosome painting in Callicebus lugens, the species with the lowest diploid number (2n=16) known in primates.

Cytogenetic studies have shown that New World primates are karyologically diverse and highly derived. The genus Callicebus is the best example of this karyological diversity, with diploid numbers ranging from 2n=50 to 2n=16. We report on Callicebus lugens, which has the lowest diploid number (2n=16) yet found in the primate order and represents a striking example of extreme karyotypic shuffling. To better understand the genomic rearrangements that have resulted in this extremely low diploid number, we mapped chromosome homologies between C. lugens and humans by in situ hybridization. The total number of hybridization signals was 42, excluding the Y chromosome, with a total of 34 syntenic associations not found in humans. This species has one of the most derived karyotypes among the Platyrrhini. Fusion has been the predominant mode of karyological evolution, although fissions and inversions have also transformed the C. lugens karyotype. Remarkably in such a highly rearranged karyotype, the synteny of 11 human chromosomes (4, 5, 9, 12, 13, 14, 17, 18, 20, 21, and X) was maintained intact, even if most of these human-homologous gene clusters were translocated. Other human syntenies, such as homologues to human chromosomes 10 and 16, were highly fragmented. Comparisons of the C. lugens-human homology map with those of other New World primates have not yet helped establish a phylogenic arrangement between congeneric species or link Callicebus with any other genus.

Animals↗
PubMed1988

Twofold CuZnSOD activity suggesting homozygous submicroscopic duplication of chromosome 21 in the orangutan.

A twofold CuZnSOD activity was observed in an orangutan as compared to man and a chimpanzee. This suggests that a submicroscopic duplication of chromosome 21 (similar to those demonstrated in patients with the trisomy 21 phenotype but with a normal karyotype) has occurred in the homozygous state during evolution of the orangutan phylum. Such duplications could be important evolutionary mechanisms, together with visible chromosome rearrangements and classical gene mutations.

Animals↗
PubMedDate not supplied

Characterization of Leishmania donovani stocks by genomic DNA heterogeneity and molecular karyotype.

A hypervariable deoxyribonucleic acid (DNA) probe was isolated by screening a Leishmania donovani genomic DNA library with L. donovani total DNA. The probe was used to characterize L. donovani stocks on the basis of restriction fragment length polymorphisms (RFLPs). The molecular karyotype of the same stocks was examined by orthogonal field alternation gel electrophoresis. On the basis of the observed RFLPs Mediterranean L. donovani infantum and South American L. donovani chagasi stocks were more similar to one another than they were to Indian L. donovani donovani or African L. donovani stocks. This conclusion was also supported by the studies on molecular karyotype. The probe also showed African L. donovani stocks to be heterogeneous in their restriction fragment patterns: the patterns of Indian stocks were, by contrast, relatively homogeneous. Certain L. donovani stocks that appeared to be closely related on the basis of RFLPs and isoenzyme data were markedly different in karyotype, demonstrating the rapidity of chromosome evolution in Leishmania donovani.

Animals↗
PubMed1997

Recent evolution of NOR-bearing and sex chromosomes of the North African rodent Lemniscomys barbarus.

The karyotype and meiotic phases of Lemniscomys barbarus from Morocco were extensively studied with G- and C-banding, Ag-NOR and fluorochrome staining, in situ hybridization with an rDNA probe, and synaptonemal complex analysis. Comparison of the data with those previously published for an Algerian specimen revealed in the Moroccan specimens the presence of large heterochromatic segments in the sex chromosomes, a new nucleolar organizer at chromosome pair 1, and silent NORs on both sex chromosomes - features that are not present in the Algerian specimen. These findings demonstrate that during the very recent evolution of the karyotype of this species a new NOR was acquired by pair 1, possibly by amplification of ribosomal genes after a translocation event. This new NOR changed the preference of activation of the NORs in these individuals and became the preferentially activated NOR. Another autosome-sex chromosome translocation led to the presence of NORs on the sex chromosomes, which were then inactivated by the invasion of repetitive sequences. These silent NORs may be involved in the pairing of the two sex chromosomes.

Animals↗
PubMed1992

Tandem and centric fusions in the chromosomal evolution of the South American phyllotines of the genus Auliscomys (Rodentia, cricetidae).

The karyotypes of three of the four extant species of the genus Auliscomys (A. micropus, living in central [2n = 32, NF = 34] and southern [2n = 34, NF = 36, 37] Chile; A. sublimis [2n = 28, NF = 32] and A. boliviensis [2n = 22, NF = 32], which inhabit the Andean Altiplano) were analyzed. Comparisons of G-, C-, and AgNOR-banded karyotypes showed that extensive conservation of entire chromosomes and chromosomal regions had occurred during the evolution of this genus, with centromeretelomere tandem fusions and centric fusions probably being the most frequent chromosome changes. A chromosomal phylogeny, based on the chromosome homoeologies detected and parsimonious analysis of the nature and distribution of the inferred chromosomal changes, is proposed. This hypothetical phylogeny assumes that the ancestral telocentric karyotype would have undergone three consecutive tandem fusions, first originating the 2n = 32 (NF = 34) karyomorph exhibited by present-day specimens of A. micropus captured in central Chile and then the 2n = 28 (NF = 32) karyotype of A. sublimis. Subsequent centric fusions involving the tandem-fusion products would presumably have generated the 2n = 22 (NF = 32) A. boliviensis karyotype. Assuming some conditions related to early geographic distribution, this chromosomal phylogeny is in agreement with a paleogeographic model, which explains the present distribution of living Auliscomys species mainly on the basis of geologic and climatic events.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed2006

Structural divergence between the human and chimpanzee genomes.

The structural microheterogeneity evident between the human and chimpanzee genomes is quite considerable and includes inversions and duplications as well as deletions, ranging in size from a few base-pairs up to several megabases (Mb). Insertions and deletions have together given rise to at least 150 Mb of genomic DNA sequence that is either present or absent in humans as compared to chimpanzees. Such regions often contain paralogous sequences and members of multigene families thereby ensuring that the human and chimpanzee genomes differ by a significant fraction of their gene content. There is as yet no evidence to suggest that the large chromosomal rearrangements which serve to distinguish the human and chimpanzee karyotypes have influenced either speciation or the evolution of lineage-specific traits. However, the myriad submicroscopic rearrangements in both genomes, particularly those involving copy number variation, are unlikely to represent exclusively neutral changes and hence promise to facilitate the identification of genes that have been important for human-specific evolution.

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PubMed1980

Karyotypes, constitutive heterochromatin and taxonomy of ringtail opossums of the genus Pseudocheirus (Marsupialia: Petauridae).

Karyotypes are presented for three forms of the common ringtail oppossum, Pseudocheirus peregrinus. These are tentatively regarded as the subspecies P.p. cookii, P.p. pulcher, and P.p. rubidus. In addition, we report for the first time the karyotype of the rock ringtail oppossum, P. dahli. The three forms of P. peregrinus each have a diploid number of 2n=20. C-banding studies indicate that the addition of large blocks of constitutive heterochromatin has played a major role in the evolution of all chromosomes in the karyotype. The X chromosome of P.p. pulcher is metacentic and approximately twice the relative size of the acrocentric X chromosomes of the other two forms of peregrinus. All three forms had two or three pairs of autosomes with secondary constrictions, a rare occurrence within the superfamily Phalangeroidea. P. (Pseudochirops) dahli has a diploid number of 2n=16; a reduction in chromosome number may have occurred by Robertsonian fusions. Four of the eight chromosome pairs lack large blocks of C-band material and the secondary constrictions are located on the sex chromosomes.

Animals↗
PubMed1993

Genome organization and species formation in vertebrates.

Some years ago Wilson and co-workers proposed that the higher rates of karyotypic change and species formation of mammals compared to cold-blooded vertebrates are due to the formation of small demes, as favored by the social structuring and brain development of the former. Here, evidence is reviewed which indicates that mammals are more prone to karyotypic change and species formation than cold-blooded vertebrates because of their different genome organization. Similar evidence has also recently become available for birds. While this different organization appears to be a necessary and, in all likelihood, a sufficient condition for the increased rates of karyotypic change and species formation found in mammals, it is still possible that social structuring and brain development may have played an additional accelerating role.

Animals↗
PubMed2001

Chromosome banding in Cacopsylla mali (Schmidberger) and Cacopsylla sorbi (Linnaeus) (Homoptera, Psyllidae) with polymorphic sex chromosomes.

C-banding and Ag staining were applied to Cacopsylla sorbi and C. mali. The aim was to discover some additional cytological markers to follow the pathways of the sex determination system transformation in the evolution of the species. Of three karyotype patterns so far described in the literature for these species--a type A (XO), B (neoXY) and C (neoX1X2Y), only the last two types (B and C) were found. All 6 studied Cacopsylla sorbi from Finland had a karyotype of type B (2n = 20 + XY), while C. mali had both types. Type B (2n = 22 + XY) was observed in 31 males, whereas type C (2n = 20 + neoX1X2Y) in the remaining four. The karyotype of C. sorbi was found to be characterized by a very small amount of C-positive material, localized in a telomere of the Y chromosome. The karyotype of C. mali was also characterized by a very small amount of C-banded material. Both the sex chromosomes and the autosomes displayed a marked polymorphism of C-positive bands within different individuals and even the same individual. In both species the nucleolus was located in the telomere of a middle sized autosomal till diplotene inclusive. The C-banding and Ag staining in the studied Cacopsylla species did not provide any additional cytological markers for an understanding of the pathways of sex determination system transformation in the evolution of the species.

Animals↗
PubMed2002

Ancient tetraploidy and slow molecular evolution in Scaphiophryne: ecological correlates of speciation mode in Malagasy relict amphibians.

Karyotypes of three microhylid frog species of the Malagasy relict genus Scaphiophryne were studied: Scaphiophryne gottlebei, S. madagascariensis and S. spinosa. The latter two showed a plesiomorphic ranoid karyotype of 2n = 26. In contrast, tetraploidy was demonstrated in S. gottlebei, which constitutes an exceptional state among Malagasy amphibians. A combination of different banding techniques and of rDNA-FISH provided evidence for allopolyploidy in the species and for a completed subsequent functional and structural diploidization. Phylogenetic analysis of mitochondrial 16S rDNA sequences revealed a significant deceleration of nucleotide substitution rates in Scaphiophryne. The tetraploidy of S. gottlebei probably occurred early in their radiation. Ecological and behavioural patterns of Scaphiophryne probably favoured intraspecific gene flow and hybridization events, thereby leading to slow molecular substitution rates and to allopolyploid chromosome speciation in S. gottlebei.

Animals↗
PubMed1995

Adult acute lymphoblastic leukemia at relapse. Cytogenetic, immunophenotypic, and molecular changes.

BACKGROUND: There have been published reports on cytogenetic, immunophenotypic, and molecular changes at relapse in childhood acute lymphoblastic leukemia (ALL) including lineage switch and secondary leukemia. There are limited data, however, on the cytogenetic, immunophenotypic, and molecular parameters of adult ALL at relapse. Because, as in children, the cytogenetic and/or immunophenotypic changes observed in adult ALL at relapse may have prognostic significance, the authors investigated the significance of such changes. METHODS: Fifty-three patients with relapsed adult ALL for whom cytogenetic, immunophenotypic, and/or molecular analyses were performed at diagnosis and at relapse were studied. Changes in any of the parameters at relapse were correlated with total survival and survival from the time of relapse. RESULTS: Of the 32 patients for whom cytogenetic studies were performed at relapse, 21 (66%) showed clonal cytogenetic changes, 40% of which were clonal evolution. None of these cases, however, showed two entirely different abnormal karyotypes at diagnosis and at relapse. The immunophenotypes showed occasional gain or loss of one or two surface markers, and the molecular genetic configurations for JH, JK, and the T-cell receptor beta were stable throughout the evolution of the disease. Patients with clonal evolution had a shorter overall survival than the rest of the group (P = 0.02). This difference, however, was not significant with respect to survival measured from the time of relapse. CONCLUSIONS: The most frequent changes in the biologic profile of adult ALL at relapse are shifts in the karyotype, with or without clonal evolution. Clonal evolution detected at relapse is associated with a higher frequency of unfavorable karyotypes at diagnosis and with a worse overall prognosis. However, survival from the time of relapse is similar in patients with and without clonal evolution.

Adolescent↗
PubMed1999

Microevolution, low clonal diversity and genetic affinities of parthenogenetic sitobion aphids in new zealand

In sharp contrast to their southeast Asian and European counterparts, Sitobion miscanthi and S. near fragariae aphids in Australia exhibit a complete absence of sexual reproduction. This demands an explanation within the context of the evolution and maintenance of sex and parthenogenesis. Accordingly, we executed a genetic analysis of the two species in neighbouring New Zealand. Microsatellites and single-stranded conformation polymorphism/sequence analysis of the nuclear gene elongation factor 1alpha were used to identify aphid clones and confirm species identification, respectively. Karyotypic variation was also investigated. The New Zealand fauna showed few (nonrecombining) genotypes and appears to have received migrants from both Australia and Asia. Other genotypes have apparently arisen in situ in New Zealand, exhibiting stepwise mutation of microsatellite alleles and also karyotypic change. Thus, these data represent rare evidence of evolution within wild-living parthenogenetic lineages. Karyotypic changes appear to occur at a rate even greater than that of microsatellite evolution. Strong geographical partitioning of genotypes/karyotypes was found, with certain ones predominating over large areas. These data suggest that clonal selection could be important in the distribution and patterning of genetic variation. We present a model to explain the genetic patterns, with particular reference to the absence of sexual reproduction in Sitobion aphids in New Zealand and Australia.

Journal Article↗
PubMed2006

Chromosome painting between human and lorisiform prosimians: evidence for the HSA 7/16 synteny in the primate ancestral karyotype.

Multidirectional chromosome painting with probes derived from flow-sorted chromosomes of humans (Homo sapiens, HSA, 2n = 46) and galagos (Galago moholi, GMO, 2n = 38) allowed us to map evolutionarily conserved chromosomal segments among humans, galagos, and slow lorises (Nycticebus coucang, NCO, 2n = 50). In total, the 22 human autosomal painting probes detected 40 homologous chromosomal segments in the slow loris genome. The genome of the slow loris contains 16 sytenic associations of human homologues. The ancient syntenic associations of human chromosomes such as HSA 3/21, 7/16, 12/22 (twice), and 14/15, reported in most mammalian species, were also present in the slow loris genome. Six associations (HSA 1a/19a, 2a/12a, 6a/14b, 7a/12c, 9/15b, and 10a/19b) were shared by the slow loris and galago. Five associations (HSA 1b/6b, 4a/5a, 11b/15a, 12b/19b, and 15b/16b) were unique to the slow loris. In contrast, 30 homologous chromosome segments were identified in the slow loris genome when using galago chromosome painting probes. The data showed that the karyotypic differences between these two species were mainly due to Robertsonian translocations. Reverse painting, using galago painting probes onto human chromosomes, confirmed most of the chromosome homologies between humans and galagos established previously, and documented the HSA 7/16 association in galagos, which was not reported previously. The presence of the HSA 7/16 association in the slow loris and galago suggests that the 7/16 association is an ancestral synteny for primates. Based on our results and the published homology maps between humans and other primate species, we propose an ancestral karyotype (2n = 60) for lorisiform primates.

Animals↗
PubMed2001

[Karyological study of some Corvine birds (Corvidae, aves)].

Karyotypes were studied in the hooded and carrion crows, their naturally occurred hybrids, the jungle crow, the azure-winged magpie (2n = 80 in all aforementioned birds), and the magpie (2n = 82). Corvine birds of Primorskii Krai were karyotyped for the first time. In addition to the similarity in the diploid chromosome sets, corvine birds were shown to have a similar structure of karyotype: in all studied birds, 14 macrochromosomes (Mchs) classified into three groups according to their size were detected. By karyotype structure, birds belonging to the same genus are similar. Some intergeneric differences are due to a change in the position of centromeres of the largest and sex chromosomes. Karyotypes of interspecific hybrids of crows are remarkable for the presence of heteromorphic (t/st) chromosome pair 2 in some individuals, which apparently does not affect their fecundity. Using differential C-banding, the sex chromosome W in female magpies was identified. In addition, heteromorphism was detected in C-bands of homologs of Mch pair 4 in the hooded crow. In the jungle crow, the azure-winged magpie, and the magpie, bright QH-bands and numerous G-bands were detected on Mchs and on some microchromosomes only. Active Ag-NOR-bands were detected on one macrochromosome pair in the magpie. In all, the karyotype structure of corvine birds is comparable to the basic structural scheme of the karyotype in the order Passeriformes, which confirms the concept of conservatism of the avian karyotype.

Animals↗
PubMedDate not supplied

Systematic implications of chromosomal data from two insular species of Peromyscus from the Gulf of California.

G- and C-banded karyotypes for two insular species of deer mice, Peromyscus slevini and P. sejugis, are described and analyzed relative to the evolutionary relationship of these species to and their inclusion within the P. maniculatus species group. The chromosomal phenotype of P. slevini is unique among all banded karyotypes reported for Peromyscus, and comparison with published karyotypes suggests that P. slevini has systematic affinities with either the P. boylii or P. mexicanus species groups. The karyotypic data for P. sejugis clearly align these mice with P. maniculatus and provide a diagnostic character that supports the specific distinction between these taxa.

Animals↗
PubMed2004

[The research on the karyotypes of six species in the genus Eremias from China].

Based on the Giemsa-dyeing karyotypes and silver-staining bands of 15 populations from different localities in China belonging to 6 species of the genus Eremias , We found all species studied have 19 pairs of chromosomes, the size of chromosomes reduces gradually and there are no marked differences between the arranged pairs of macrochromosomes except the last pair of microchromosome. There are the same karyotype formula as 2n=38=36I+2m with NF=38 in E. argus, E. multiocellata, E. velox, E. arguta and E. grammica; but the karyotype formula of E. vermiculata is different as 2n=38=12V+2sI+22I+2m with NF=50. The NOR are all located on one small pair in female of E. velox, and E. arguta , in male of E. grammica and E. vermiculata ,and in both male and female of E. multiocellata. We have not found two or more than two pairs of NOR. Having one pair of NOR may be common in Genus Eremias and also the trait of Eremias. We speculate that the derivation of the karyotype of E. vermiculata had two possible way: one experienced the stage of triploid, and later the Robertsonian transposal of chromosomes; the other way was through the inversions between the arms on the chromosome and the phenomenon of inversions might occur during or subsequently after the upheaval of the Tibet and Qinghai plateau and the founding of the Tianshan . With regard to the trend of the evolution of chromosomes in the lizards ([1]), the karyotype of E. vermiculata is more advanced. Making specialties of E. vermiculata will help in building the phylogenic tree of Eremias. In both male and female of the species studied, the heteromorphic sex-chromosomes were not found.

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PubMed1984

[Chromosomal phylogeny of Gerbillidae. III. Species study of the genera Tatera, Taterillus, Psammomys and Pachyuromys].

The karyotypes of six species of Gerbillidae (Rodentia)--Taterillus congicus, Tetarillus sp d'Oursi, Tatera sp cf. nigrita, Tatera guineae, Psammomys obesus, and Pachyuromys duprasi--are described and compared to those of species already studied. Many chromosomal homoeologies are demonstrated, as well as the existence of many rearrangements. Some genera, e.g., Taterillus, have undergone a very complex chromosomal evolution, while others have kept their karyotypes fairly close to that of the common ancestor.

Animals↗