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1.
Genomic divergence between species can be quantified in terms of the number of chromosomal rearrangements that have occurred in the respective genomes following their divergence from a common ancestor. These rearrangements disrupt the structural similarity between genomes, with each rearrangement producing additional, albeit shorter, conserved segments. Here we propose a simple statistical approach on the basis of the distribution of the number of markers in contiguous sets of autosomal markers (CSAMs) to estimate the number of conserved segments. CSAM identification requires information on the relative locations of orthologous markers in one genome and only the chromosome number on which each marker resides in the other genome. We propose a simple mathematical model that can account for the effect of the nonuniformity of the breakpoints and markers on the observed distribution of the number of markers in different conserved segments. Computer simulations show that the number of CSAMs increases linearly with the number of chromosomal rearrangements under a variety of conditions. Using the CSAM approach, the estimate of the number of conserved segments between human and mouse genomes is 529 +/- 84, with a mean conserved segment length of 2.8 cM. This length is <40% of that currently accepted for human and mouse genomes. This means that the mouse and human genomes have diverged at a rate of approximately 1.15 rearrangements per million years. By contrast, mouse and rat are diverging at a rate of only approximately 0.74 rearrangements per million years. 相似文献
2.
Evolutionary characterization of a Y chromosomal sequence conserved in the genus Mus 总被引:1,自引:0,他引:1
Y Nishioka 《Genetical research》1988,52(2):145-150
3.
S. T. Tarzami A. M. Kringstein R. A. Conte R. S. Verma 《Molecular & general genetics : MGG》1997,253(4):512-514
In humans, acute myelomonocytic leukemia (AMML) with abnormal bone marrow eosinophilia is diagnosed by the presence of a
pericentric inversion in chromosome 16, involving breakpoints p13;q23 [i.e., inv(16)(p13;q23)]. A pericentric inversion involves
breaks that have occurred on the p and q arms and the segment in between is rotated 180° and reattaches. The recent development
of a “human micro-coatasome” painting probe for 16p contains unique DNA sequences that fluorescently label only the short
arm of chromosome 16, which facilitates the identification of such inversions and represents an ideal tool for analyzing the
“divergence/convergence” of the equivalent human chromosome 16 (PTR 18, GGO 17 and PPY 19) in the great apes, chimpanzee,
gorilla and orangutan. When the probe is used on the type of pericentric inversion characteristic of AMML, signals are observed
on the proximal portions (the regions closest to the centromere) of the long and short arms of chromosome 16. The probe hybridized
to only the short arm of all three ape chromosomes and signals were not observed on the long arms, suggesting that a pericentric
inversion similar to that seen in AMML has not occurred in any of these great apes.
Received: 4 July 1996 / Accepted: 18 September 1996 相似文献
4.
Mitotic chromosomes, interphase cell nuclei, and male meiosis of 41 species representing all vertebrate classes were analyzed with distamycin A/mithramycin counterstaining. The purpose of the study was to recognize differences and common characteristics in the reverse (R) fluorescent banding patterns in the chromosomes of vertebrate species at various stages of evolution. In contrast to the warm-blooded mammals and birds, the euchromatic segments in the chromosomes of most reptiles, amphibians, and fishes contain no multiple fluorescent R-bands. This is thought to be due to the absence of the long homogeneous regions (isochores) in the DNA of the cold-blooded vertebrates. Distamycin A/mithramycin banding specifically reveals the GC-rich constitutive heterochromatin in all vertebrates. In most of the vertebrate chromosomes examined, the heterochromatic regions have opposite staining properties with mithramycin and quinacrine. Mithramycin labels the nucleolus organizer regions very brightly in the karyotypes of fishes, amphibians, reptiles and birds, but not of mammals. The lack of mithramycin fluorescence at the nucleolus organizer regions of mammals is attributed to the relatively low level of redundancy of the GC-rich ribosomal DNA in their genomes. Studies on the various meiotic stages of the cold-blooded vertebrates show that the mithramycin labeling of the nucleolus organizers is independent of their state of activity. This can be confirmed by mithramycin fluorescence at the nucleoli of actinomycintreated cells.Dedicated to the memory of Professor Dr. Hans Bauer 相似文献
5.
Comparative mapping between the human and the mouse genomes allows characterization of linkage groups that have been conserved over evolution. In this study, genes previously localized to adjacent regions of human chromosome 1 were mapped to discrete regions on distal mouse chromosomes 1 and 3 using an interspecific cross. Linkage analysis in mouse defined two groups in which the gene order appears to be the same as that in humans: 15 genes localized between human chromosome 1q21 and 1q32 were found to span 29.5 cM on distal mouse chromosome 1; 6 genes localized between human chromosome 1q21 and 1p22 spanned 15.6 cM on distal mouse chromosome 3. These data suggest that gene order within large chromosome segments may remain stable over long periods of evolution and that the position of the centromere may reflect a late event in the evolution of higher eukaryotic organisms. These studies provide a model for examination of specific evolutionary events. 相似文献
6.
7.
Gaiti Hasan 《Journal of genetics》1989,68(3):139-146
A chromosomal walk on the X chromosome ofDrosophila in the region of polytene bands 7C1 to 7D5 is described. The region is of interest since three olfactory genes have been
found to map here in addition to a haplo-inviable locus. Genomic clones spanning 160 kilobases have been isolated and their
complete restriction map is presented. The clones have been aligned on the polytene chromosome bands byin situ hybridisation. In addition the end-points of a deficiency and duplication lying in this region have been mapped approximately,
showing that an overlap exists between them. 相似文献
8.
Gabriel Gonzalez Kanako O. Koyanagi Koki Aoki Nobuyoshi Kitaichi Shigeaki Ohno Hisatoshi Kaneko Susumu Ishida Hidemi Watanabe 《Gene》2014
Human adenovirus species D (HAdV-D), which is composed of clinically and epidemiologically important pathogens worldwide, contains more taxonomic “types” than any other species of the genus Mastadenovirus, although the mechanisms accounting for the high level of diversity remain to be disclosed. Recent studies of known and new types of HAdV-D have indicated that intertypic recombination between distant types contributes to the increasing diversity of the species. However, such findings raise the question as to how homologous recombination events occur between diversified types since homologous recombination is suppressed as nucleotide sequences diverge. In order to address this question, we investigated the distribution of the recombination boundaries in comparison with the landscape of intergenomic sequence conservation assessed according to the synonymous substitution rate (dS). The results revealed that specific genomic segments are conserved between even the most distantly related genomes; we call these segments “universally conserved segments” (UCSs). These findings suggest that UCSs facilitate homologous recombination, resulting in intergenomic segmental exchanges of UCS-flanking genomic regions as recombination modules. With the aid of such a mechanism, the haploid genomes of HAdV-Ds may have been reshuffled, resulting in chimeric genomes out of diversified repertoires in the HAdV-D population analogous to the MHC region reshuffled via crossing over in vertebrates. In addition, some HAdVs with chimeric genomes may have had the opportunity to avoid host immune responses thereby causing epidemics. 相似文献
9.
10.
Between rat and mouse zoo-FISH reveals 49 chromosomal segments that have been conserved in evolution
Mouse single chromosome paints were applied to rat prophase/prometaphase chromosomes to detect homologous chromosome regions. The analysis revealed 49 rat chromosomal regions ranging in size from whole chromosomes down to small bands near the limit of detection with this method, which was estimated to be 2-3 Mb. When all the painted regions were taken into account, the whole rat genome was covered with mouse-homologous regions, with the exception of small segments near the centromeres and the short arms of Chromosomes (Chrs) 3, 11, 12, and 13. These regions were shown to contain high levels of rat-specific repetitive DNA. The number of conserved segments between rat and mouse detected by our high-resolution zoo-FISH method was significantly higher than that reported in previous studies. 相似文献
11.
Plant genome archaeology: evidence for conserved ancestral chromosome segments in dicotyledonous plant species 总被引:3,自引:0,他引:3
Dominguez I Graziano E Gebhardt C Barakat A Berry S Arús P Delseny M Barnes S 《Plant biotechnology journal》2003,1(2):91-99
We have developed genetic maps, based on expressed sequence tags (ESTs) that are homologous to Arabidopsis genes, in four dicotyledonous crop plant species from different families. A comparison of these maps with the physical map of Arabidopsis reveals common genome segments that appear to have been conserved throughout the evolution of the dicots. In the four crop species analysed these segments comprise between 16 and 33% of the Arabidopsis genome. Our findings extend the synteny patterns previously observed only within plant families, and indicate that structural and functional information from the model species will be, at least in part, applicable in crop plants with large genomes. 相似文献
12.
Characterization of the canine karyotype by counterstain-enhanced chromosome banding 总被引:1,自引:0,他引:1
The application of the counterstain-contrasted fluorescent banding technique to canine chromosomes provided an improved capability to highlight specific heterochromatic regions and to produce well defined banding patterns both on mitotic and meiotic chromosomes. Triple staining with chromomycin A3 - distamycin A - DAPI revealed the occurrence of DA - DAPI positive heterochromatin in chromosomes 33, 36, 37, and 38. Pachytene nuclei present more favourable material for the detection of very small amounts of DA - DAPI material than mitotic division stages. Counterstain-enhanced chromomycin R-banding greatly facilitated chromosome identification. A standard R-band karyotype of Canis familiaris is proposed and described in some detail. DAPI - actinomycin D staining produced a QFH-type banding pattern and enhanced differentiation of some polymorphic regions. 相似文献
13.
A colored banding pattern for human chromosomes is described that distinguishes each chromosome in a single fluorescence
in situ hybridization with a set of subregional DNA probes. Alu/polymerase chain reaction products of various human/rodent
somatic cell hybrids (fragment hybrids) were pooled into two probe sets that were labeled differentially and detected by red
and green fluorescence. Chromosome regions hybridized by DNA present in both pools appeared yellow. The result was a multi-color
set of 110 distinct signals per haploid chromosome set for the human karyotype. Each individual chromosome showed a unique
sequence of signals, a result termed the “chromosome bar code”. The reproducibility of the hybridization pattern in various
labeling and hybridization experiments was analyzed by computer densitometry. We have applied the chromosome bar code both
in diagnostic cytogenetics and in genome studies. The approach allows the rapid identification of chromosomes and chromosome
rearrangements. Although not yet showing the resolution of classical banding patterns, the present experiments demonstrate
various applications in which the present multi-color bar code can significantly add to the spectrum of cytogenetic techniques.
Received: 18 December 1996 / Accepted: 10 February 1997 相似文献
14.
A. I. Ibraimov 《Human genetics》1983,63(4):384-391
The distribution of chromosomal Q-polymorphic bands was studied in different human populations. The populations studied showed no differences in the relative amount of Q bands in all the 12 polymorphic loci of seven autosomes, but interpopulation differences did exist in the absolute amount of Q bands in all the 12 potentially polymorphic loci of seven autosomes, these differences consisting of uniform increases or decreases in this absolute amount. Comparisons of the mean number of Q-heterochromatin bands with fluorescence levels 4 and 5 per individual showed a consistent prevalence of this quantitative parameter of chromosomal Q polymorphism in females as compared to males in all the national groups. It is suggested that there is some dosage compensation of chromosomal Q-heterochromatin material in females due to the absence of a chromosome in their genome, which is able to "compensate" for the large Q band in chromosome Y which is present only in the karyotype of males. 相似文献
15.
Ruiz-Herrera A Robinson TJ 《BioEssays : news and reviews in molecular, cellular and developmental biology》2008,30(11-12):1126-1137
In this review, we focus on the evolutionary and biomedical aspects of the architecture of human chromosome 3 (HSA3) by analyzing chromosomal regions that have been conserved during the evolutionary process, compared to those that have been involved in the genomic restructuring of different placental lineages. Given that the organization of human chromosome 3 is derived when compared to the ancestral primate karyotype, and is an autosome that is commonly implicated in human tumour formation, we examined the patterns of change and the genomic consequences that have resulted from its complex evolutionary history. The data show four discrete chromosomal regions that are frequently implicated in chromosomal rearrangements (3p25, 3p22, 3p12 and 3q21). These are rich in repetitive elements and are commonly implicated in structural rearrangements that underpin human genomic disorders and neoplasias. Additional Supporting Information may be found in the online version of this article. 相似文献
16.
A method for mapping nonisotopically labeled probes to human metaphase chromosomes that can be used with laser scanning confocal microscopy has been developed. Only a limited number of wavelengths are available from the argon ion lasers used in most commercial instruments and therefore a method that allowed the visualization of bands on human chromosomes stained with propidium iodide and, simultaneously, the detection of hybridization signals using FITC-labeled antibodies was developed. The confocal microscope was used to map single-copy probes to chromosome bands and the positions of the probes on the R-banded chromosomes corresponded to map positions previously determined on Hoechst 33258-stained chromosomes (G-banded). A comparison of confocal imaging of single-copy hybridization signals with conventional fluorescence microscopy and high-sensitivity video cameras revealed little difference in sensitivity but greater resolution of chromosome bands with the confocal microscope. The polymerase chain reaction was used to prepare nonisotopically labeled probes for in situ hybridization and to amplify Alu and KpnI family repeats from cloned DNA to be used to suppress hybridization of these repeat sequences so that a cosmid probe could be mapped to a chromosome band. 相似文献
17.
Deletion of human JK segments by site-specific recombination recognizing the conserved nonamer and heptamer sequences. 总被引:2,自引:0,他引:2 下载免费PDF全文
T Nakatani K Horigome N Nomura T Kondo H Ohtsuka H Noguchi T Honjo 《Nucleic acids research》1990,18(18):5529-5532
Mapping and partial sequencing of the productive K chain genomic DNA of FK-001 demonstrated a 1.8-kb deletion including the JK2, JK3, JK4, and JK5 segments. This deletion occurred between the heptamer recombination signal sequence of the JK2 segment and the heptamer-like sequence located 1.8 kb downstream of the JK2 segment. The recombination reaction kept the reciprocally joined signal sequences on the chromosome and deleted the intervening DNA segment. The cloned FK-001 K chain gene was expressed efficiently in mouse myeloma cells, demonstrating that the 1.8-kb deleted region conferred no functions for gene expression. 相似文献
18.
19.
N Ayraud 《Comptes rendus des séances de la Société de biologie et de ses filiales》1975,169(2):365-372
A precise identification of chromosome abnormalities observed in cancerous human cells may be demonstrated by chromosome banding. The types of newly formed chromosomes seem to indicate the possibility of a correlation between chromosome rearrangements and regions of heterochromatin. The evolution of neoplastic cells would be due to a balance between an increase in the level of chromosome mutation and stable changes. 相似文献