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1.
Juliana Marge Pagnozzi Maria José de Jesus Silva Yatiyo Yonenaga-Yassuda 《Chromosome research》2000,8(7):585-591
The distribution of the telomeric sequence (TTAGGG)n was studied in chromosomes of Micoureus demerarae (2n=14), a South American marsupial, by fluorescence in-situ hybridization (FISH). The telomeric repeat sequence was present at both ends of all chromosomes, but also various interstitial telomeric sequences (ITS) were detected in the pericentromeric heterochromatic regions. Intraspecific differences in the number of ITS (2 to 8) were observed without intraindividual variation. The presence of telomere-like sequences in the same regions of constitutive heterochromatin suggest that these segments are not necessarily remnants of true telomeres resulting from chromosome rearrangements but could be part of the satellite DNA. 相似文献
2.
Takeshi Inoue Ryo Inoue Rio Tsutsumi Kikuo Tada Yuko Urata Chiaki Michibayashi Shota Takemura Kiyokazu Agata 《Developmental dynamics》2012,241(10):1575-1583
Background: It is widely accepted that juvenile animals can regenerate faster than adults. For example, in the case of lens regeneration of the newt Cynops pyrrhogaster, larvae and adults require approximately 30 and 80 days for completion of lens regeneration, respectively. However, when we carefully observed lens regeneration in C. pyrrhogaster at the cellular level using molecular markers in the present study, we found that lens regeneration during the larval stage proceeded at similar speed and by means of similar steps to those in adults. Results: We could not find any drastic difference between regeneration at these two stages, except that the size of the eyes was very different. Conclusions: Our observations suggested that larvae could regenerate a lens of the original size within a shorter time than adults because the larval lens was smaller than the adult lens, but the speed of regeneration was not faster in larvae. In addition, by repeatedly observing the regeneration in one individual transgenic newt that expressed fluorescence specifically in lens fiber cells in vivo and comparing the regeneration process at the embryonic, larval, and postmetamorphosis stages, we confirmed that the regeneration speed was the same at each of these stages in the same individual. Developmental Dynamics 241:1575–1583, 2012. © 2012 Wiley Periodicals, Inc. 相似文献
3.
Indrajit Nanda Sonja Schneider-Rasp Heinz Winking Michael Schmid 《Chromosome research》1995,3(7):399-409
Mouse chromosomes possessing multiple Robertsonian rearrangements (Rb chromosomes) have been examined using fluorescencein situ hybridization with the telomeric consensus sequence (TTAGGG)n. No hybridization signals were detected at the primary constriction of Rb chromosomes. This observation leads us to conclude that the formation of Rb chromosomes in the mouse is invariably associated with the loss of telomeric regions. More significantly, a further alteration in regions flanking the primary constrictions was observed after hybridizing with a minor satellite DNA probe to Rb chromosomes. It seems likely that the breakpoints required for a Robertsonian process do not include telomeric sites exclusively but extend to the adjacent pericentromeric regions of the original acrocentric chromosomes. In contrast to previous reports, these observations demonstrate the elimination of substantial amounts of chromosomal DNA during the formation of mouse Rb chromosomes. 相似文献
4.
Frank Chan 《Anatomical record (Hoboken, N.J. : 2007)》1982,202(4):521-525
It is well known that if the original lens is removed from the eyeball in certain Urodeles, a new lens will regenerate from the dorsal iris. Experiments were designed to study the different effects on lens regeneration in the newt, Triturus viridescens, between the light and dark preadapted animals and light and dark non-preadapted animals. The preadapted animals were preadapted to continuous light or dark for 90 days prior to lentectomy. The newts remained in the same controlled environments postlentectomy for 25 days to test the effect of light preadaptation on lens regeneration. The non-preadapted animals were placed in the light controlled environment immediately after lentectomy for a 25-day regeneration period. The results indicated that there was no difference in the rate of regeneration between continuous light preadapted and non-preadapted animals. However, the dark non-preadapted animals regenerated new lenses at a much slower rate than the dark preadapted animals. The rate of lens regeneration was similar among the controls with 12 hours of light per 24-hour period, the dark preadapted, the continuous light preadapted, and continuous light non-preadapted groups. 相似文献
5.
Taiki Kawagoshi Chizuko Nishida Hidetoshi Ota Yoshinori Kumazawa Hideki Endo Yoichi Matsuda 《Chromosome research》2008,16(8):1119-1132
Crocodilians have several unique karyotypic features, such as small diploid chromosome numbers (30–42) and the absence of
dot-shaped microchromosomes. Of the extant crocodilian species, the Siamese crocodile (Crocodylus siamensis) has no more than 2n = 30, comprising mostly bi-armed chromosomes with large centromeric heterochromatin blocks. To investigate
the molecular structures of C-heterochromatin and genomic compartmentalization in the karyotype, characterized by the disappearance
of tiny microchromosomes and reduced chromosome number, we performed molecular cloning of centromeric repetitive sequences
and chromosome mapping of the 18S-28S rDNA and telomeric (TTAGGG)
n
sequences. The centromeric heterochromatin was composed mainly of two repetitive sequence families whose characteristics
were quite different. Two types of GC-rich CSI-HindIII family sequences, the 305 bp CSI-HindIII-S (G+C content, 61.3%) and 424 bp CSI-HindIII-M (63.1%), were localized to the intensely PI-stained centric regions of all chromosomes, except for chromosome 2 with
PI-negative heterochromatin. The 94 bp CSI-DraI (G+C content, 48.9%) was tandem-arrayed satellite DNA and localized to chromosome 2 and four pairs of small-sized chromosomes.
The chromosomal size-dependent genomic compartmentalization that is supposedly unique to the Archosauromorpha was probably
lost in the crocodilian lineage with the disappearance of microchromosomes followed by the homogenization of centromeric repetitive
sequences between chromosomes, except for chromosome 2. 相似文献
6.
Masaki Fujisawa Shigeki Nakayama Tomohisa Nishio Mariko Fujishita Kiwako Hayashi Kimitsune Ishizaki Masataka Kajikawa Katsuyuki T. Yamato Hideya Fukuzawa Kanji Ohyama 《Chromosome research》2003,11(7):695-703
In the haploid dioecious liverwort, Marchantia polymorpha, the X chromosome, but not the Y, carries a cluster of ribosomal RNA genes (rDNAs). Here we show that sequences of 5S, 17S,
5.8S and 26S rDNAs are highly conserved (>99% identity) between the X chromosomal and autosomal rDNA repeat units, but the
intergenic spacer sequences differ considerably. The most prominent difference is the presence of a 615-bp DNA fragment in
the intergenic spacer, X615, which has accumulated predominantly in the rDNA cluster of the X chromosome. These observations
suggest that the rDNA repeat unit on the X chromosome evolved independently of that on autosomes, incorporating sex chromosome-specific
sequences.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Marta Gromicho Jean-Pierre Coutanceau Catherine Ozouf-Costaz Maria João Collares-Pereira 《Chromosome research》2006,14(3):297-306
The diploid–polyploid Squalius alburnoides complex resulted from interspecific hybridization. The chromosomal mapping of 28S and 5S ribosomal genes and of (TTAGGG)n telomeric repeats was performed on specimens from the complex and from the sympatric bisexual species S. pyrenaicus (the complex maternal ancestor) as part of an investigation of the evolutionary relationships between genomic constitutions
and the consequences of the ongoing polyploidization process in terms of chromosome reshaping. Contrasting results were obtained.
While results with 5S rDNA and telomeric probes gave an impression of genomic stability, the variability detected with 28S
rDNA probe suggested quite the opposite. The 5S rDNA probe mapped constantly to three chromosomes per haploid genome with
apparently conserved locations in morphologically similar chromosomes; conversely, prominent intra- and inter-individual variations
of 28S rDNA and of syntenic sites with 5S rDNA were detected with regard to number, size and location. Hypotheses for the
causes of such polymorphisms are discussed. The terminal position of most 28S rDNA sites and the absence of detectable interstitial
telomeric sequences suggest a mechanism that does not involve major chromosomal rearrangements. These fishes share similar
patterns for the studied cytogenetic markers which may be taken as evidence of an apparent stability that may be hiding extensive
and subtle genome variations that are possibly related to an ongoing evolutionary process of genome tetraploidization and
speciation. 相似文献
8.
Natalia?S.?Zhdanova Tatjana?V.?Karamisheva Julia?Minina Natalia?M.?Astakhova Peter?Lansdorp Makoto?Kammori Nikolai?B.?Rubtsov Jeremy?B.?Searle
Sorex araneus and Sorex granarius are sibling species within the Sorex araneus group with karyotypes composed of almost identical chromosome arms. S. granarius has a largely acrocentric karyotype, while, in S. araneus, various of these acrocentrics have combined together by Robertsonian (Rb) fusions to form metacentrics, with the numbers and types of metacentrics differing between chromosomal races. Our studies on telomeric sequences in S. araneus and S. granarius revealed differences between chromosomes and between species. In S. araneus (the Novosibirsk race), hybridization signals were present on the telomeres of all the chromosomes after FISH with a PCR-generated telomeric probe. In addition, hybridization signals were observed at high frequencies in the pericentric regions of some but not all metacentrics formed by Rb fusion. There were fewer signals on those metacentrics formed earlier in the evolution of S. araneus. This suggests that S. araneus chromosomes retain at least some telomeric repeats during Rb fusion, but that these repeats are lost or modified over time. These results are critical for the interpretation of the well-studied hybrid zones between chromosomal races of S. araneus, given that Rb fission has been postulated in such hybrid zones and that the likelihood of Rb fission will relate to presence/absence of telomeric sequences at the centromeres of metacentrics. In S. granarius, there were strong signals at the proximal (centromeric) telomeres of the acrocentrics after FISH with a DNA telomeric probe. FISH with a PNA telomeric probe on S. granarius acrocentrics showed that the proximal telomeres were 213 kb on average, while the length of the distal telomeres was 3.8 kb on average. Two-colour FISH, using a telomeric DNA probe and a microdissected probe generated from the pericentric regions of the S. granarius chromosomes a and b, revealed regions on distinct chromatin fibres where telomeric and microdissected probes were colocalized or localized sequentially. The proximal telomeres of S. granarius are highly unusual both in their large size and their heterogeneous structure relative to the telomeres of other mammals. 相似文献
9.
Kazumi Matsubara Kazuhiko Yamada Shu Umemoto Kimiyuki Tsuchiya Naoki Ikeda Chizuko Nishida Takahito Chijiwa Kazuo Moriwaki Yoichi Matsuda 《Chromosome research》2008,16(7):1013-1026
Three novel families of repetitive DNA sequences were molecularly cloned from the Korean field mouse (Apodemus peninsulae) and characterized by chromosome in-situ hybridization and filter hybridization. They were all localized to the centromeric regions of all autosomes and categorized
into major satellite DNA, type I minor, and type II minor repetitive sequences. The type II minor repetitive sequence also
hybridized interspersedly in the non-centromeric regions. The major satellite DNA sequence, which consisted of 30 bp elements,
was organized in tandem arrays and constituted the majority of centromeric heterochromatin. Three families of repetitive sequences
hybridized with B chromosomes in different patterns, suggesting that the B chromosomes of A. peninsulae were derived from A chromosomes and that the three repetitive sequences were amplified independently on each B chromosome.
The minor repetitive sequences are present in the genomes of the other seven Apodemus species. In contrast, the major satellite DNA sequences that had a low sequence homology are present only in a few species.
These results suggest that the major satellite DNA was amplified with base substitution in A. peninsulae after the divergence of the genus Apodemus from the common ancestor and that the B chromosomes of A. peninsulae might have a species-specific origin. 相似文献
10.
The course of chromosome evolution in small apes is still not clear, though painting analyses have opened the way for elucidating
the puzzle. Even the C-banding pattern of the lar-group of gibbons (the genus Hylobates) is not clarified yet, although our previous studies suggested that lar-group gibbons have a unique C-banding pattern. We
therefore made observations to establish C-banded karyotypes of the agile gibbons included in the lar-group. The data were
compared with those of siamangs (the genus Symphalangus), which carry distinctive C-bands, to determine the chromosomal patterns in each group. C-banded chromosomes of agile gibbons
showed several terminal, interstitial and paracentric bands, whose patterns are specific for each chromosome, whereas the
C-bands of siamangs were located only at the terminal and centromeric regions in most chromosomes. Moreover, the C-bands of
agile gibbons and siamangs were shown to be G+C-rich and A+T-rich DNA, respectively, by DAPI/C-band sequential staining. Additionally,
PRINS labelling with a telomere primer revealed that agile gibbons have telomeric DNA only at chromosome ends where there
is no C-band (non-telomeric heterochromatin), whereas the telomeric DNA of siamangs is located in the terminal C-banded regions
(telomeric heterochromatin). Although the evolutionary mechanisms in small apes are still unknown, C-banding patterns and
distribution of telomeric DNA sequences should provide valuable data to deduce the evolutionary pathways of small apes. 相似文献
11.
We have isolated families of subtelomeric satellite DNA sequences from species of four sections of the genus Beta and from spinach, a related Chenopodiaceae. Twenty-five clones were sequenced and representative repeats of each family were
characterized by Southern blotting and FISH. The families of ApaI restriction satellite repeats were designated pAv34, pAc34, the families of RsaI repeats pRp34, pRn34 and pRs34. The repeating units are 344–362 bp long and 45.7–98.8% homologous with a clear species-specific
divergence. Each satellite monomer consists of two subrepeats SR1 and SR2 of 165–184 bp, respectively. The repeats of each
subrepeat group are highly identical across species, but share only a homology of 40.8–54.8% with members of the other subrepeat
group. Two evolutionary steps could be supposed in the phylogeny of the subtelomeric satellite family: the diversification
of an ancestor satellite into groups representing SR1 and SR2 in the progenitor of Beta and Spinacea species, followed by the dimerization and diversification of the resulting 360 bp repeats into section-specific satellite
DNA families during species radiation. The chromosomal localization of telomeric, subtelomeric and rDNA tandem repeats was
investigated by multi-colour FISH. High-resolution analysis by fibre FISH revealed a unique physical organization of B. vulgaris chromosome ends with telomeric DNA and subtelomeric satellites extending over a maximum of 63 kb and 125 kb, respectively. 相似文献
12.
Comparison of the human and mouse genes encoding the telomeric protein, TRF1: chromosomal localization, expression and conserved protein domains 总被引:11,自引:0,他引:11
Broccoli D; Chong L; Oelmann S; Fernald AA; Marziliano N; van Steensel B; Kipling D; Le Beau MM; de Lange T 《Human molecular genetics》1997,6(1):69-76
13.
Silvia Garagna Elena Ronchetti Silvia Mascheretti Sergio Crovella Daniele Formenti Yves Rumpler Maria G. Manfredi Romanini 《Chromosome research》1997,5(7):487-491
The chromosomal distribution of the (TTAGGG)n telomeric repetitive sequences was studied in the Malagasy species Eulemur fulvus fulvus (2n = 60), Eulemur rubriventer (2n = 50), Eulemur coronatus (2n = 46) and Eulemur macaco (2n = 44). These sequences hybridize to the telomeres of all chromosomes of the four species and also to the pericentromeres of all chromosomes of E. fulvus, E. coronatus and E. macaco, with the exception of the pericentromeres of E. coronatus and E. macaco chromosomes 9, the homeologous E. fulvus chromosomes 2 and E. macaco chromosomes 1. In E. rubriventer only a very weak signal was detected at the pericentromeres of a few chromosomes. In E. fulvus, E. coronatus and E. macaco, non-telomeric (TTAGGG)n sequences collocalize with constitutive heterochromatin. The interspecific differences of the hybridization pattern of (TTAGGG)n sequences at the pericentromeres suggest that E. rubriventer branched off the common trunk before amplification of endogenous (TTAGGG)n sequences occurred in pericentromeric regions.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
14.
Adriana Okumura Finato Marileila Varella-Garcia Eloisa Helena Tajara Valdir Antonio Taddei Eliana Morielle-Versute 《Chromosome research》2000,8(7):563-569
The location of chromosomal telomeric repeats (TTAGGG)n was investigated in two species of the Molossidae family, Eumops glaucinus and Eumops perotis. The diploid chromosome number (2n) is 40 in E. glaucinus and 48 in E. perotis and the fundamental numbers (FN) are 64 and 58, respectively. It has been suggested that the E. glaucinus karyotype has evolved from the E. perotis karyotype through Robertsonian fusion events. In the present study, the telomeric sequences were detected at the termini of chromosomes in both species. In addition, E. glaucinus also displayed telomeric repeats in centromeric and pericentromeric regions in almost all biarmed chromosomes. Conversely, in E. perotis pericentromeric signals were only observed in two biarmed chromosomes. In both E. glaucinus and E. perotis, such telomeric sequences were observed as part of the heterochromatin. The interstitial sites of telomeric sequences suggest that they are remnants of telomeres of ancestral chromosomes that participated in the fusion event. 相似文献
15.
R. Chaves F. Adega J. S. Heslop-Harrison H. Guedes-Pinto J. Wienberg 《Chromosome research》2003,11(7):641-648
We have analysed and mapped physically the satellite I, III (subunits pvu and sau) and IV DNA sequences in cattle using in-situ hybridization. Four breeds were analysed including individuals with a chromosome number of 2n=60 and individuals with the widespread t(1;29) in the homozygous (2n=58) and heterozygous state (2n=59). All three satellite DNA families were present at the centromeres of the many but not all of the autosomal acrocentric
chromosomes, and essentially absent from the sex chromosomes. In the translocated t(1;29) chromosome, the satellite DNA families
showed a different pattern from that simply derived by fusion of the acrocentric autosomes and loss of satellite sequences,
with no variation between breeds. A model of centromeric evolution is presented involving two independent events. Knowledge
of mechanisms of translocation formation within cattle is important for a functional understanding of centromere and satellites,
investigation of chromosomal abnormalities, and for understanding chromosomal fusion during evolution of other bovids and
genome evolution in general.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Susanna Salvadori AnnaMaria Deiana Coluccia Elisabetta Giovanna Floridia Elena Rossi Orsetta Zuffardi 《Chromosome research》1995,3(1):54-58
The distribution of (TTAGGG)n telomeric repeats was studied in chromosomes of two Atlantic eels,Anguilla anguilla andA. rostrata. We found that these sequences hybridize to all the telomeres but also to the entire nucleolar organizer region (NOR) localized in both species at the short arm of chromosome 8. This was considered to be due to the interspersion of telomeric sequences within the NOR ones. Whatever the significance of this interspersion may be, it seems to be limited toA. anguilla andA. rostrata since inMuraena helena (family muraenidae), which also belongs to the Anguilliformes, no telomeric hybridization signals were found along the NOR regions. 相似文献
17.
There are only a few reports on the chromosomal location of DNA sequences in bivalve species, none of them using meiotic chromosomes. Mitotic chromosomes of the clam Dosinia exoleta were analysed by means of Giemsa, silver and fluorochrome staining and fluorescent in situ hybridization (FISH) with 18S + 28S rDNA and telomeric probes. A technique for surface spreading of synaptonemal complexes (SCs) of Dosinia exoleta was developed for the first time in a bivalve species. Silver and DAPI/PI staining and SC-FISH were also applied to the study of the meiotic chromosomes of this clam. The diploid chromosome number in this species is 38 and the karyotype is composed of 11 pairs of metacentric and eight pairs of submetacentric chromosomes. 18S + 28S rDNA clusters map to the subtelomeric region of the short arm of one metacentric chromosome pair whereas telomeric signals appear at both ends of every chromosome. 相似文献
18.
Riccardo Castiglia Silvia Garagna Valeria Merico Nicholas Oguge Marco Corti 《Chromosome research》2006,14(5):587-594
We present the results of a cytogenetic study on Mus (Nannomys) minutoides from Kenya by means of C- and G- banding and in-situ fluorescence hybridization (FISH) to localize the telomeric sequences. The karyotype is characterized by the occurrence of
several Rb chromosomes Rb(1.X), Rb(1.Y). Rb(2.17), Rb(3.13), Rb(4.10), Rb(5.11), Rb(6.7), Rb(8.12), not previously described
for this species. This finding suggests a high level of chromosomal diversification, which means it is possible to consider
this cytotype as a new, well-differentiated, chromosomal lineage within the subgenus. The C-banding of the metaphases illustrated
conspicuous blocks of centromeric heterochromatin at the paracentromeric regions of all telocentric chromosomes. Centromeric
heterochromatin is not visible on all biarmed chromosomes. Following hybridization with telomeric probes, bright interstitial
telomeric sequence (ITS) fluorescence signals are evident at the pericentromeric area of all Rb chromosomes, with the exception
of Rb(2.17). Considering the localization of the C-positive heterochromatin and of the telomeric sequences, the events leading
to the Kenyan cytotype from an all-telocentric condition probably included two steps: first, fusion without loss of heterochromatin
and pericentromeric telomeric sequences; second, the reduction of the C-positive satellite DNA followed by the amplification
of telomeric sequences in the C-negative paracentromeric region of Rb chromosomes. The presence of a single Rb(2.17) without
ITS indicates possible variations of this mechanism. 相似文献
19.
Two paralogous mitochondrial malate dehydrogenase 2 (Mdh2) genes of Xenopus laevis have been cloned and sequenced, revealing 95% identity. Fluorescence in-situ hybridization (FISH) combined with tyramide amplification discriminates both genes; Mdh2a was localized into chromosome q3
and Mdh2b into chromosome q8. One kb cDNA probes detect both genes with 85% accuracy. The remaining signals were on the paralogous
counterpart. Introns interrupt coding sequences at the same nucleotide as defined for mouse. Restriction polymorphism has
been detected in the first intron of Mdh2a, while the individual variability in intron 6 of Mdh2b gene is represented by an
insertion of incomplete retrotransposon L1Xl. Rates of nucleotide substitutions indicate that both genes are under similar
evolutionary constraints. X. laevis Mdh2 genes can be used as markers for physical mapping and linkage analysis. 相似文献
20.
Nobuyasu Maki Katsuaki Takechi Shozo Sano Hiroshi Tarui Yoshiki Sasai Kiyokazu Agata 《Developmental dynamics》2007,236(4):941-950
In newt regeneration, differentiated cells can revert to stem cell-like cells in which the proliferative ability and multipotentiality are restored after dedifferentiation. However, the molecular events that occur during the dedifferentiation still remain obscure. Nucleostemin has been identified in mammals as a nucleolar protein specific to stem cells and cancer cells. In this study, a newt nucleostemin homologue was cloned and its regulation was analyzed. During lens regeneration, the expression of nucleostemin was activated and nucleostemin rapidly accumulated in the nucleoli of dedifferentiating pigmented epithelial cells 2 days before cell cycle reentry. During limb regeneration, nucleostemin also accumulated in the nucleoli of degenerating multinucleate muscle fibers before blastema formation. These findings suggest that nucleostemin plays a role in the dedifferentiation of newt cells and can provide crucial clues for addressing the molecular events at early steps of cellular dedifferentiation in newts. 相似文献