Evolution of the marked chromosomes of primates: experimental evidence for centric fusion.
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Animals↗
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Results for “karyotype evolution”
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How to deal with a rare entity: the coexistence of a complete mole and a healthy egg in a twin pregnancy?
The association of a normal and a molar egg within a twin pregnancy is extremely rare. The key to diagnosis is the fetal karyotype, thus allowing elimination of its principal differential diagnosis: partial triploid mole. We report a case where the evolution of the pregnancy was complicated by severe toxemia. Interruption of pregnancy was then necessary, even though a conservative attitude had first been considered. Throughout this case, we discuss the means of diagnosis and the clinical handling of this rare entity.
Abortion, Therapeutic↗
[Pericentric inversion of chromosome 3, homozygote and heterozygote, and centromeric translation of chromosome 12 in a family of orangutangs. Evolutionary implications].
An orangutang family is reported in which the father (Piku) is homozygous for a pericentric inversion of chromosome 3 and heterozygous for a structural rearrangement of chromosome 12 (author's nomenclature for this species). The latter is interpreted as transposition of the centromere by insertion into band q213 [in cen (12)(q213)]. Piku's mate has a normal female chromosome complement. His daughters by this mate (Agnès and Ursula) are heterozygous for both his rearrangements.
Animals↗
Clues to homologous regions in mammalian autosomes.
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Animals↗
Human renal cell carcinoma xenografts in SCID mice: tumorigenicity correlates with a poor clinical prognosis.
To establish human renal cell carcinoma (RCC) xenografts for preclinical studies, 55 renal tumors (33 primary and 22 metastatic lesions) were transplanted subcutaneously into severe combined immunodeficient mice. Twenty of 49 evaluable tumors (40.8%) grew with a median latency period of 89 days (36 to 209 days) from the day of engraftment. Tumor growth was stabilized after the fifth passage with a median time between passages of 38 days (19 to 80 days). Tumorigenicity was correlated with the metastatic phenotype of the tumor (54% success rate, p = 0.007) and with reduced survival of patients. Despite a possible evolution of histological features and tumor grading, established RCC xenografts were comparable to parental tumors, as assessed by karyotype and DNA-ploidy analyses. Molecular cytogenetic analysis also revealed specific genetic alterations characterizing distinct RCC types that were constant in parental and corresponding xenografts. In addition, this xenograft model has permitted the selection of minor tumor subclones with a proliferative advantage and minimal overexpressed chromosomal regions. We conclude that severe combined immunodeficient mice are useful recipients for the establishment of long-term RCC xenografts that can be used as valuable tools to evaluate the activity of new therapeutic approaches and to study biological parameters determining in vivo aggressiveness of human RCC.
Adult↗
[Clinical spectrum of prenatal tetralogy of Fallot].
The aim of this study of 44 cases of tetralogy of Fallot was to assess the echocardiographic aspects and the prognosis with respect to associated abnormalities and the potential evolution in utero. Group I, tetralogy of Fallot with other abnormalities (N = 27: 2 valvular agenesis, 26.5 5.3 weeks), had genetic anomalies in 18 of the foetus (10 trisomies including 5 trisomy 21, 5 structural abnormalities including 2 micro-deletions 22q11 in the two cases of valvular agenesis, and one deletion of chromosome 8p23.1, 3 mendelian syndromes) and other abnormalities in 9 cases. Hypoplasia of the pulmonary artery was present in 60% of cases with a non-dilated aorta in 72%, infundibular hypertrophy in 33% and 2 evolutions to pulmonary atresia. Aspect of "isolated" ventricular septal defect were observed in 20% of cases. Survival was 10%. In Group II, tetralogy of Fallot was isolated (N = 17, including 2 pulmonary valve agenesis, 31 +/- 6 weeks) (p < 0.01 versus Group I). Pulmonary artery hypoplasia was observed in 50% of cases with dilatation of the aorta and infundibular hypertrophy in all and in one a postnatal progression towards pulmonary atresia. A correlation between growth of the pulmonary artery and gestational age was found in 5 foetus out of 9 studied sequentially (p between 0.03 and 0.007) and between age at first surgery and size of the pulmonary artery (r = 0.80, p = 0.001). Survival was 84%. The risk of malformation (61%) and the prenatal potential evolution of this disease justifies continuous follow-up of all cases of tetralogy of Fallot, high resolution karyotyping and postnatal evaluation in a specialized centre.
Abnormalities, Multiple↗
Genotypic diversity in species of Scilla.
Two cytotypes of Scilla indica and three other species, namely S. nervosa, S. siberica and S. vindobonensis were investigated. The estimation of nuclear DNA content was utilized as a measure of genetic diversity at inter- and intraspecific levels and as an index of the trends of evolution. S. siberica with a very high DNA value was regarded as indicative of a primitive state. The heavy intraspecific difference in DNA content in S. indica has been attributed to amplification of the DNA.
Analysis of Variance↗
Zoos and the pathologist--a two-way street or cytogenetics on zoo animals.
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Animals↗
Cytogenetics and cancer.
When present, chromosome abnormalities can contribute useful information for tumor diagnosis and prognosis. However, the existence of diploid tumor cells indicates that such abnormalities are not necessary in tumors. Their time of appearance, sometimes preceding or predisposing to tumor and sometimes occurring late in disease, also suggests that chromosomal events are not critical. Rather, they should be considered as markers of the underlying and essential gene changes. The great frequency of chromosome aberrations in human tumors probably reflects two roles: (1) they provide an efficient means to effect a multiplicity of gene changes, and (2) they permit rapid cellular evolution.
Chromosome Aberrations↗
Chromosomes and spermatozoa of the African great apes.
We have analysed the chromosome constitution of 8 chimpanzees (Pan troglodytes), 3 pygmy chimpanzees (Pan paniscus), and 16 gorillas (Gorilla gorilla). In the chimpanzees, the frequency of brilliant Q-band polymorphisms accounted for 8.85 regions per individual, and in the gorilla 14.9, whereas in man it was only 2.9-4.6. Variation in the amount of constitutive heterochromatin was also observed, and the gorilla appeared to be the most variable of all. A detailed analysis of the spermatozoa of the African apes showed that the gorilla produced pleiomorphic spermatozoa. As the animals under investigation were phenotypically normal, of proven fertility, and were kept in unheated cages, it is probable that gorillas, like human males, normally exhibit pleiomorphic spermatozoa. This makes it unlikely that clothing-induced hyperthermia could account for pleiomorphic spermatozoa in man. The modal cell types in the ejaculates of men and gorillas were also morphologically identical. The less frequent cell types defined as morphologically abnormal spermatozoa were also very similar and occurred in similar proportions. It is therefore impossible to distinguish between man and the gorilla by a simple examination of the ejaculate, although it is possible to distinguish between man and the chimpanzees or between the gorilla and the chimpanzees. Both species of chimpanzee produced identical spermatozoa. With quinacrine fluorescence, F-bodies were observed in the sperm head of the chimpanzees and the gorilla. In the chimpanzee and the pygmy chimpanzee, F-bodies correspond to brilliant autosomal regions, whereas in the gorilla they probably correspond both the the autosomes and the Y chromosome. There was no consistently visible F-body in the sperm head of the chimpanzee or the gorilla; in the pygmy chimpanzee, one fluorescent region appeared, and it probably corresponded to a brilliant region in autosomal pair No. 23.
Animals↗
Human chromosomes and their anomalies.
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Animals↗
Identification of cytogenetic subgroups and karyotypic pathways in transitional cell carcinoma.
The clinical course in urinary bladder cancer is difficult or impossible to predict based on conventional disease parameters. It is a reasonable hypothesis that the genetic aberrations acquired by the tumor cells, being instrumental in bringing about the disease in the first place, may also hold the key to more reliable prognostication. However, though 200 transitional cell carcinomas (TCC), the most common bladder cancer in the Western world, with clonal chromosomal abnormalities have been reported, our knowledge about the karyotypic characteristics of these tumors remains insufficient. The aberration pattern is clearly nonrandom, but no completely specific primary or secondary karyotypic abnormality has been identified, and the chronological order in which the aberrations appear during disease progression is not well known. The high degree of karyotypic complexity in epithelial tumors like TCC is one reason why our picture of the sequential order of cytogenetic evolution is unclear. To overcome some of these difficulties we have used several statistical methods that allow analysis and interpretation of the relationship between cytogenetic aberrations in TCC. We show that there exists a temporal order with respect to the appearance of chromosomal imbalances and that this order is highly correlated with tumor stage and grade. Analyzing changes in the distribution of imbalances per tumor in G1, G2, and G3 tumors, we suggest that progression involves the acquisition of cytogenetically detectable and submicroscopic genetic changes at comparable frequencies. By means of computer simulations, we show that the imbalances -9, +7, and 1q+ appear earlier than expected from random events and that -6q, -5q, -18, +5p, -22p, and -15 appear later than expected. Using principal component analysis, we identify two cytogenetic pathways in TCC, one initiated by -9 and followed by -11p and 1q+, the other initiated by +7 and followed by 8p- and +8q. The -9 pathway was correlated with stage Ta-T2 tumors, whereas the +7 pathway was correlated with stage T1-T3 tumors, i.e., +7 tumors appeared to be more aggressive. Although these pathways are well separated at earlier stages, they later converge to contain a common set of imbalances.
Carcinoma, Transitional Cell↗
Reconstruction of the ancestral ferungulate karyotype by electronic chromosome painting (E-painting).
By comparing high-coverage and high-quality whole genome sequence assemblies it is now possible to reconstruct putative ancestral progenitor karyotypes, here called protokaryotypes. For this study we used the recently described electronic chromosome painting technique (E-painting) to reconstruct the karyotype of the 85 million-year-old (MYA) ferungulate ancestor. This model is primarily based on dog (Canis familiaris) and cattle (Bos taurus) genome data and is highly consistent with comparative gene mapping and chromosome painting data. The protokaryotype bears 23 autosomal chromosome pairs and the sex chromosomes and preserves most of the chromosomal associations described previously for the boreo-eutherian protokaryotype. The model indicates that five interchromosomal rearrangements occurred during the transition from the boreo-eutherian to the ferungulate ancestor. From there on 66 further interchromosomal rearrangements took place in the lineage leading to cattle and 61 further interchromosomal rearrangements in the lineage to dog.
Animals↗
Evidence for a conspecific relationship between two morphologically and cytologically different forms of Korean Anopheles pullus mosquito.
Despite the medical importance of anopheline mosquitoes as vectors of Korean vivax malaria, differentiation between Korean anopheline mosquitoes by traditional morphological taxonomic criteria is difficult. An. yatsushiroensis is the second most common Anopheles mosquito species in Korea and a possible vector of Korean vivax malaria together with An. sinensis, the predominant anopheline species. Recently, An. yatsushiroensis has been declared a synonym of An. pullus, based on comparisons of egg morphology and adult progeny, although they differ in ecology and morphology. To verify the species status of these two ambiguous forms, we established isofemale lines of Korean An. pullus and An. yatsushiroensis (An. pullus form yatsushiroensis) mosquitoes and investigated their genetic relationship by metaphase karyotype analysis, comparing the DNA sequences of rDNA internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunits I (COI) and II (COII), and by hybridization experiments. Two isofemale lines had differently shaped X and Y chromosomes. However reciprocal crosses between them yielded viable progeny with completely synaptic salivary gland polytene chromosomes. DNA analyses also strongly supported their conspecificity. The two strains also showed great sequence similarity in the ITS2, COI and COII regions (variation rate = 0.0 to 0.8%). Based on these findings, we conclude that the two forms, though differing distinctly in morphological, cytological and ecological traits, remain interfertile.
Animals↗
Unusual C-band patterns in three karyotypically rearranged forms of Scapteromys (Rodentia, Cricetidae) from Brazil.
Chromosome studies of 30 specimens of the rodent Scapteromys collected at nine localities in southern Brazil revealed the occurrence of three karyotypic taxa with 2n = 36 (one locality), 34 (two localities), and 24 (six localities), although all three had 40 autosomal arms (AN). The G-band analysis indicated that this reduction in diploid number was mainly due to Robertsonian translocations which have occurred along a gradient, possibly in two independent evolutive routes. The C-bands occur on one autosomal pair and on the X and Y in the 2n = 36 and 34 forms and on the X and Y chromosomes only in the 2n = 24 taxon. The broad genomic reorganization which has occurred in this genus, in which the chromosomes do not have large amounts of constitutive heterochromatin, argues against the idea that a large amount of constitutive heterochromatin favors chromosome evolution and speciation.
Animals↗
"Bar-coding" primate chromosomes: molecular cytogenetic screening for the ancestral hominoid karyotype.
Two recently introduced multicolor FISH approaches, cross-species color banding (also termed Rx-FISH) and multiplex FISH using painting probes derived from somatic cell hybrids retaining fragments of human chromosomes, were applied in a comparative molecular cytogenetic study of higher primates. We analyzed these "chromosome bar code" patterns to obtain an overview of chromosomal rearrangements that occurred during higher primate evolution. The objective was to reconstruct the ancestral genome organization of hominoids using the macaque as outgroup species. Approximately 160 individual and discernible molecular cytogenetic markers were assigned in these species. Resulting comparative maps allowed us to identify numerous intra-chromosomal rearrangements, to discriminate them from previous contradicting chromosome banding interpretations and to propose an ancestral karyotype for hominoids. From 25 different chromosome forms in an ancestral karyotype for all hominoids of 2N=48 we propose 21. Probes for chromosomes 2p, 4, 9 and Y were not informative in the present experiments. The orangutan karyotype was very similar to the proposed ancestral organization and conserved 19 of the 21 ancestral forms; thus most chromosomes were already present in early hominoid evolution, while African apes and human show various derived changes.
Animals↗
Appearance and evolution of the specific chromosomal rearrangements associated with malignant transformation of mouse m5S cells.
Chromosomal alterations were studied during the acquisition of malignant phenotypes in two karyotypically distinct cells isolated from transformed foci induced by x-irradiation in mouse m5S cells. Because the transformants, despite foci origin, showed low ability to grow in agar, they were cultured in vitro with serial transfer schedules to allow further cell generations and assayed for anchorage independence (AI) at each passage level. The AI frequency increased with the cell doubling numbers. Chromosome analysis showed that a focus was one cell origin, but the transformants showed karyotypic instability during cell proliferation, giving rise to the rearrangements clustered in the distal region of the specific chromosomes. These rearrangements appeared to be directed toward the acquisition of malignant phenotypes. Analysis of the types and sites of rearrangements indicated that a mechanism exists that induces frequent rearrangements of the specific region of a chromosome during the process of transformation into the malignant state.
Animals↗
Chromosome evolution involving Robertsonian rearrangements in Xyrichthys fish (Labridae, Perciformes).
Three Xyrichthys fish (Labridae, Perciformes), X. pavo, X. dea, and X. twistii, were cytogenetically studied. X. pavo and X. dea had 2n = 44 chromosomes, which were all acrocentric. X. twistii had 2n = 22 chromosomes consisting of eighteen meta- and submetacentric and four acrocentric chromosomes. The cellular DNA contents of X. pavo and X. twistii measured using flow cytometry were nearly equal. These results suggest that the karyotype of X. twistii evolved by decreasing the number of chromosomes by fusion events, probably Robertsonian fusion. Cytogenetic relationships among the three species were surmized on the basis of features on the karyotypes and the NOR locations. A large gap in the chromosome number between 2n = 44 and 2n = 22 is an interesting feature related to the process of chromosome evolution.
Animals↗