Chromosomal localization of the telomeric (TTAGGG)n sequence in eight species of New World Primates (Neotropical Primates, Platyrrhini)

Chromosomal localization of the telomeric sequence (TTAGGG)(n) in eight New World Primates (Platyrrhini) (Alouatta caraya, Alouatta palliata, Alouatta guariba clamitans, Aotus azarae, Ateles chamek, Cebus nigritus, Cebus paraguayanus, and Saimiri boliviensis) using Fluorescence In Situ Hybridization (FISH) with a peptide nucleic acid (PNA) pantelomeric probe and their possible relationship with the C-banding pattern were analyzed. FISH showed telomeric signals only at the terminal regions of chromosomes from all the species analyzed. Although all of them showed centromeric C+ bands and different size and location of extracentromeric C+ bands, none, except Aotus azarae exhibited (peri)centromeric interstitial telomere-like sequences (ITS). The presence of ITS in Aotus azarae was limited to one pair of submetacentric chromosomes and very likely represents telomeric sequences remaining after a fusion event of ancestral chromosomes during karyotype evolution. Therefore, our data indicate that the distribution of heterochromatin blocks do not correlate with the presence of ITS. However, we cannot rule out the possibility that simple ITS arrays with a few copies of the (TTAGGG)(n) sequence, not detectable by conventional FISH, might play a role in the karyotypic evolution of Ceboidea. Further FISH and molecular studies will be needed to confirm this hypothesis.     

Karyotype analysis, banding, and fluorescent in situ hybridization in the scarab beetle Gymnopleurus sturmi McLeay (Coleoptera Scarabaeoidea : Scarabaeidae)

Conventional staining, differential banding, and in situ hybridization with both ribosomal and telomeric probes to mitotic chromosomes of Gymnopleurus sturmi (Scarabaeoidea : Scarabaeidae) are described. The karyotype is distinguished by a pericentric inversion polymorphism in chromosome 3, which is either acrocentric or subtelocentric. Silver staining (Ag-NOR) and chromomycin A3 (CMA3), failed to study the detection of nucleolar organizer regions (NORs), due to the extensive silver and CMA3 stainability of all GC-rich heterochromatin. Fluorescent in situ hybridization (FISH) using a Paracentrotus lividus (Echinodermata) rDNA probe mapped the ribosomal RNA genes (rDNA). FISH with the all-human telomeric sequences (TTAGGG)n revealed a lack of homology between the telomeric probe and the telomeres of G. sturmi. This suggests that the telomeric hesanucleotide (TTAGGG)n is not so conserved within eukaryotes as it has been hypothesized.     

Fluorescence in situ hybridization of rDNA, telomeric (TTAGGG)n and (GATA)n repeats in the red abalone Haliotis rufescens (Archaeogastropoda: Haliotidae)

The physical location of 18S-5.8S-28S rDNA, telomeric sequences with (TTAGGG)n DNA probe and (GATA)n microsatellites were performed by fluorescence in situ hybridization in chromosomes of red abalone Haliotis rufescens. The karyotype of red abalone showed a diploid number of 36 (8M+9SM+1ST). FISH performed with rDNA probe, showed the location of major ribosomal clusters in the terminal region of the large arms of two submetacentric pairs (chromosome 4 and 5). Localization of heteromorphisms of FISH-rDNA was found between chromosome homologues and sister chromatids in all metaphases analyzed. This indicates that rDNA clusters are variable within the red abalone genome. The variability in the NOR-bearing reported using silver staining in other gastropods and our result are discussed. In addition, the presence of microsatellite (TTAGGG)n and (GATA)n was demonstrated after FISH treatment by DNA probes. The telomeric sequence occurred at the ends of all mitotic chromosomes, while the (GATA)n repetitive was found on chromosomal interstitial zones as well as at the telomeres in abalone chromosomes.     

Detection of interstitial telomeric sequences in the Arctic charr (Salvelinus alpinus) (Teleostei: Salmonidae)

Highly polymorphic Arctic charr ( Salvelinus alpinus Linnaeus, 1758) chromosomes were studied using conventional and molecular methods. The diploid chromosome number in the studied individuals was 2n = 81 or 2n = 82, with a fundamental arm number (NF) = 100. These differences are due to Robertsonian fusions. Interindividual variation in the number and size of DAPI and CMA(3) positively stained chromatin sites was observed in studied specimens. In the case of two individuals, the subtelomeric region of the long arm (q) of the largest acrocentric chromosome (chromosome number 10) was positively stained by CMA(3) fluorochrome. Both primed in situ labelling (PRINS) and fluorescence in situ hybridization (FISH) revealed that this CMA(3)-positive region was flanked by telomeric sequences. Previously, the subterminal position of interstitial telomeric sequences located in the vicinity of the CMA(3)-positive guanine-rich chromatin have been described in two other Salvelinus species, brook trout ( Salvelinus fontinalis ) and lake trout ( Salvelinus namaycush ). Moreover, multichromosomal location and variation in size of CMA(3) bands have been observed in various Salvelinus taxa, including fishes with internally located telomeric sequences. These results suggest that relocation of CMA(3)-positive chromatin segments in these species may be facilitated by flanking interstitial telomeric sequences (ITSs).     

Chromosomal evolution in the Brazilian lizards of genus Leposoma (Squamata, Gymnophthalmidae) from Amazon and Atlantic rain forests: banding patterns and FISH of telomeric sequences

An extensive karyotype differentiation was found among three species of gymnophthalmid lizard genus Leposoma which occur in the tropical forest areas of Brazil. We examined the chromosomes of the Amazonic species L. guianense (LOU) and L. oswaldoi (LOS) and the Atlantic forest species L. scincoides (LSC) after conventional and differential staining, and FISH of telomeric sequences. Both Amazonic species shared very similar 2n = 44 karyotypes, including 20 biarmed macrochromosomes and 24 microchromosomes (20 M + 24 m). However, the location of Ag-NORs and the amount of constitutive heterochromatin differed in these karyotypes. The Atlantic forest species L. scincoides has a very distinct karyotype with 52 acrocentric and subtelocentric chromosomes of decreasing size. Comparative R-banding analysis revealed complete homeology of the macrochromosomes of LGU and LOS and correspondence of banding patterns between LSC acrocentrics and subtelocentrics and some arms of biarmed LGU and LOS chromosomes. Pair 1 had similar banding patterns in the three species, implying the occurrence of a pericentric inversion. Interstitial telomeric bands (ITBs) detected by FISH at the pericentromeric region of some biarmed LGU and LOS chromosomes could be remnants of chromosomal rearrangements occurred during the differentiation of the karyotypes. Robertsonian rearrangements as well as pericentric inversions events probable were involved in the karyotype evolution of these Amazon and Atlantic forests species of Leposoma.     

Karyotype characterization of the lake sturgeon, Acipenser fulvescens (Rafinesque 1817) by chromosome banding and fluorescent in situ hybridization.

A karyotype analysis using several staining techniques was carried out on the North American lake sturgeon, Acipenser fulvescens. The chromosome number was found to be 2n = 262 +/- 6. A representative karyotype of 264 chromosomes was composed of 134 meta- and submetacentrics, 70 telo- and acrocentrics, and 60 microchromosomes. The constitutive heterochromatin, revealed by C banding, was localized in various positions on several chromosomes, including microchromosomes. The signals of fluorescent in situ hybridization (FISH) with a HindIII satellite DNA probe were visible as centromeric heterochromatin blocks on 48 chromosomes. The telomeric repeat (TTAGGG)n detected by FISH was localized at both ends of all chromosomes and two chromosomes were entirely marked. Fluorescent staining with GC-specific chromomycin A3 showed recognizable fluorescent regions, whereas a more uniform base composition was revealed by the AT-specific 4',6-diamidino-2-phenylindole (DAPI). After silver staining, the active nucleolar organizer regions (NORs) were detected on 12 chromosomes. FISH with the 5S probe showed four signals on four small chromosomes. Our data suggest that A. fulvescens is a tetraploid species.     

Cytogenetic characterization of the bay scallop, Argopecten irradians irradians, by multiple staining techniques and fluorescence in situ hybridization

The chromosomes of Argopecten irradians irradians were studied by various cytogenetic approaches. Conventional chromosome characterization built on C-banding, DAPI-staining, and silver staining was complemented by the physical mapping of ribosomal DNA and telomeric sequence (TTAGGG)n by FISH. Results showed that the constitutive heterochromatin revealed by C-banding was mainly distributed at telomeric and centromeric regions. However, interstitial C-bands were also observed. The pattern of DAPI banding was almost consistent with that of C-banding. Silver staining revealed that NORs were located on the short arms of chromosome 3 and 10, and this was further confirmed by FISH using 18S-28S rDNA. 5S rDNA was mapped as two distinguishable loci on the long arm of chromosome 11. 18S-28S and 5S rDNA were located on different chromosomes by sequential FISH. FISH also showed that the vertebrate telomeric sequence (TTAGGG)n was located on both ends of each chromosome and no interstitial signals were detected. Sequential 18S-28S rDNA and (TTAGGG)n FISH demonstrated that repeated units of the two multicopy families were closely associated on the same chromosome pair.     

Karyotype and genome characterization in four cartilaginous fishes

Different approaches can be used to elucidate the unsolved questions concerning taxonomic evolution in cartilaginous fish. The study of the karyological characteristics of these vertebrates by combining molecular and traditional techniques of chromosome preparation and banding has been demonstrated to be a very effective method. In this paper we studied the localization and the composition of the constitutive heterochromatin by using C- and restriction endonuclease-banding in four selachian species, belonging to two of the four superorders. We also characterized two different types of repetitive genomic sequences in these species: satellite DNA and (TTAGGG)(n) telomeric sequences. Finally, we analysed the nuclear ribosomal gene to determine the number of the nucleolar organizers and their position on chromosomes by using silver staining, chromomycin A(3), and FISH (fluorescent in situ hybridization). The results showed a prevailingly telomeric localization of constitutive heterochromatin in the Galeomorphii, the presence of additional nucleolar organizer sites in Raja asterias, an exclusively telomeric localization of the (TTAGGG)(n) sequences in Scyliorhinus stellaris and both telomeric and interstitial in Taeniura lymma. These data, together with those concerning the conservation of the satellite DNA, seem to support the hypothesis that Chondrichthyes have an evolutionary history leading them to the acquisition of large genomes rich in highly repeated sequences and subjected to some selective pressures favoring the conservation of this DNA fraction.     

纳特竖蟾(无尾目:滑背蟾科) 的细胞遗传、与相关属物种的核型相似性并兼论其分类地位

本文报道纳特竖蟾(Eupemphix nattereri Steindachner,1863)巴西3个产地标本的核型,均为2n=22,由1对端部和10对中或亚中部着丝点染色体组成.仅一对NORs位于No.11染色体对长臂端部,而其位置有别于常见的具有标志性意义的近着丝点位置.该NORs的位置为rDNA为探针的荧光原位杂交(FISH)所确认.各染色体对中,着丝点C-带明显,插入或端带偶见.某些标本的No.8同源染色体对间C-带的大小随异染色质化的程度不同而变化.居于较小的实验标本量,这种在3个产地的雌或雄性标本之一中观察到的C-带异型现象可能为种下细胞地理学变异,亦或为细胞学意义的性染体分化.3产地之一的标本核型的No.11着丝点C-带异染色质化的程度较高.CMA3染色检测到部分GC-rich区域,DAPI染色未显示任何AT-rich区.成功获得BrdU复制带,并将其与滑背蟾类动物(leiuperid)中近缘属及物种进行对比分析.比较结果表明,纳特竖蟾的核型与斑符泡蟾种组(Physalaemus signifer group)难以相互区别,而与肿肋蟾属(Pleurodema Tschudi,1838)极为相似.核型数据支持形态学上将纳特竖蟾、二光肿肋蟾[Pleurodema diplolister (Peters,1870)]和短头肿肋蟾[P.brachyops(Cope,1869)]划为同一分支的观点[动物学报 53(2):285-293,2007].     

B chromosomes in Nierembergia aristata (Solanaceae): nucleolar activity and competition with the A chromosomes

B chromosomes are additional dispensable chromosomes that may be present in some individuals, populations, or species, which have probably arisen from the A chromosomes but follow their own evolutionary pathway. Supposedly, B chromosomes do not contain major genes except for ribosomal DNA (rDNA) sequences that have been mapped on the supernumerary chromosomes of many plants and animals. This paper is a new report of B chromosome occurrence in plants. B chromosomes with nucleolar organizing regions (NORs) were found in a diploid sample of Nierembergiaaristata D. Don (sub nom. N. stricta Miers) (2n = 2x = 16). This is an extreme case in which B chromosomes possess not only strong nucleolar activity, as revealed by conventional staining methods, AgNOR and fluorescence banding, and fluorescent in situ hybridization (FISH), but also show nucleolar competition with the A chromosomes. The observed phenomenon could be analogous to the nucleolar dominance or 'differential amphiplasty' phenomenon that occurs in interspecific hybrids.     

Cytogenetic analysis of four central Amazonian species of Colostethus (Anura - Dendrobatidae) with a diploid complement of 22 chromosomes

Colostethus marchesianus from the type locality and three related species had 2n = 22 chromosomes, which differed from most other Colostethus species that have 2n = 24 chromosomes. The species analyzed were morphologically similar and showed a conservative karyotype, although they could be distinguished from each other by their C-banding pattern. Additional NOR sites, heteromorphism in NOR size and heterochromatin, and an additional rDNA site detected by FISH, were observed. These data suggest that chromosomal rearrangements and hetrochromatin-related events may have contributed to the karyotype differentiation of these Colostethus.     

Karyotypic characterization of <Emphasis Type="Italic">Trachemys dorbigni</Emphasis> (Testudines: Emydidae) and <Emphasis Type="Italic">Chelonoidis (Geochelone) donosobarrosi</Emphasis> (Testudines: Testudinidae), two species of Cryptodiran turtles from Argentina

We describe for the first time the karyotypes of two species of Cryptodiran turtles from Argentina, namely, Trachemys dorbigni (Emydidae) and Chelonoidis (Geochelone) donosobarrosi (Testudinidae). The karyotype of T. dorbigni (2n = 50) consists of 13 pairs of macrochromosomes and 12 pairs of microchromosomes, whereas the karyotype of C. donosobarrosi (2n = 52) consists of 11 pairs of macrochromosomes and 15 pairs of microchromosomes. Fluorescence in situ hybridization (FISH) with a (TTAGGG)n telomeric probe showed that the chromosomes of these species have four telomeric signals, two at each end, indicating that none of the chromosomes of T. dorbigni and C. donosobarrosi are telocentric. The fact that no interstitial telomeric signals were observed after FISH, suggests that interstitial telomeric sequences did not have a major role in the chromosomal evolution of these species. Additional data will be needed to elucidate if interstitial telomeric sequences have a major role in the karyotypic evolution of Testudines.     

Cytogenetic analysis in Polypterus ornatipinnis (Actinopterygii, Cladistia, Polypteridae) and 5S rDNA

Polypteridae is a family of archaic freshwater African fish that constitute an interesting subject for the study of the karyological evolution in vertebrates, on account of their primitive morphological characters and peculiar relationships with lower Osteichthyans. In this paper, a cytogenetic analysis on twenty specimens of both sexes of Polypterus ornatipinnis the ornate "bichir", coming from the Congo River basin, was performed by using both classical and molecular techniques. The karyotypic formula (2n=36; FN=72) was composed of 26 M+10 SM. The Alu I banding, performed to characterize heterochromatin in this species, was mainly centromeric. Both the chromosome location of the ribosomal 5S and 18S rRNA genes were examined by using Ag-NOR, classical C-banding, CMA(3) staining and FISH. CMA(3) marked all centromerical regions and showed the presence of two GC rich regions on the p arm of the chromosome pair n°1 and on the q arm of the pair n°14. Staining with Ag-NOR marked the only telomeric region of the chromosome n°1 p arm. After PCR, the 5S rDNA in this species was cloned, sequenced and analyzed. In the 665bp 5S rDNA sequence of P.ornatipinnis, a conserved 120bp gene region for the 5S rDNA was identified, followed by a non-transcribed variable spacer (NTS) which included simple repeats, microsatellites and a fragment of a non-LTR retrotransposon R-TEX. FISH with 5S rDNA marked the subtelomeric region of the q arm of the chromosome pair n°14, previously marked by CMA(3). FISH with 18S rDNA marked the telomeric region of the p arm of the pair n°1, previously marked both by Ag-NOR and CMA(3). The (GATA)(7) repeats marked the telomeric regions of all chromosome pairs, with the exclusion of the n°1, n°3 and n°14; hybridization with telomeric probes (TTAGGG)(n) showed signals at the end of all chromosomes. Karyotype evolution in Polypterus genus was finally discussed, including the new data obtained.     

Cytogenetic study of Callicebus hoffmannsii (Cebidae, Primates) and comparison with C. m. moloch.

Callicebus is a neotropical primate genus divided into four or five groups of species. Species of the moloch group are distributed in the tropical forests of the Amazon basin. The karyotype of Callicebus hoffmannsii (moloch group) was studied by means of G- and C-banding, Ag-NOR staining and in situ hybridization of telomeric probes. C. hoffmannsii had 2n = 50 chromosomes, with ten biarmed and fourteen acrocentric autosomal pairs. The X chromosome was submetacentric and the Y chromosome was a minor acrocentric. Constitutive heterochromatin was detected in the centromeric regions of all chromosomes; in pairs 7 and 10, it was found in the distal regions of the short arms, and distally in the long arm of the X chromosome. Size heteromorphism in C-bands was detected in pairs 7 and 10. Ag-NOR staining revealed a maximum of three nucleolar organizers. Telomeric probes hybridized only at the terminal regions of all chromosomes. Additionally, a comparison was carried out between C. hoffmannsii and C. m. moloch (2n = 48), as previously reported. Both species shared gross chromosomal similarities diverging by a single rearrangement of centric fusion/fission. A high similarity between C. hoffmannsii and C. donacophilus indicated a close association between the moloch and donacophilus groups.     

High-resolution FISH on super-stretched flow-sorted plant chromosomes

A novel high-resolution fluorescence in situ hybridisation (FISH) strategy, using super-stretched flow-sorted plant chromosomes as targets, is described. The technique that allows longitudinal extension of chromosomes of more than 100 times their original metaphase size is especially attractive for plant species with large chromosomes, whose pachytene chromosomes are generally too long and heterochromatin patterns too complex for FISH analysis. The protocol involves flow cytometric sorting of metaphase chromosomes, mild proteinase-K digestion of air-dried chromosomes on microscopic slides, followed by stretching with ethanol:acetic acid (3 : 1). Stretching ratios were assessed in a number of FISH experiments with super-stretched chromosomes from barley, wheat, rye and chickpea, hybridised with 45S and 5S ribosomal DNAs and the [GAA]n microsatellite, the [TTTAGGG]n telomeric repeat and a bacterial artificial chromosome (BAC) clone as probes. FISH signals on stretched chromosomes were brighter than those on the untreated control, resulting from better accessibility of the stretched chromatin and maximum observed sensitivity of 1 kbp. Spatial resolution of neighbouring loci was improved down to 70 kbp as compared to 5-10 Mbp after FISH on mitotic chromosomes, revealing details of adjacent DNA sequences hitherto not obtained with any other method. Stretched chromosomes are advantageous over extended DNA fibres from interphase nuclei as targets for FISH studies because they still retain chromosomal integrity. Although the method is confined to species for which chromosome flow sorting has been developed, it provides a unique system for controlling stretching degree of mitotic chromosomes and high-resolution bar-code FISH.     

Chromosomal organization of simple sequence repeats in the Pacific oyster (<Emphasis Type="Italic">Crassostrea gigas</Emphasis>): (GGAT)<Subscript>4</Subscript>, (GT)<Subscript>7</Subscript> and (TA)<Subscript>10</Subscript> chromosome patterns

Chromosome identification is essential in oyster genomic research. Fluorescence in situ hybridization (FISH) offers new opportunities for the identification of oyster chromosomes. It has been used to locate satellite DNAs, telomeres or ribosomal DNA sequences. However, regarding chromosome identification, no study has been conducted with simple sequence repeats (SSRs). FISH was used to probe the physical organization of three particular SSRs, (GGAT)(4), (GT)(7) and (TA)(10) onto metaphase chromosomes of the Pacific oyster, Crassostrea gigas. Hybridization signals were observed in all the SSR probes, but the distribution and intensity of signals varied according to the oligonucleotide repeat. The intercalary, centromeric and telomeric bands were observed along the chromosomes, and for each particular repeat every chromosome pair presented a similar pattern, allowing karyotypic analysis with all the SSRs tested. Our study is the first in mollusks to show the application of SSR in situ hybridization for chromosome identification and karyotyping. This technique can be a useful tool for oyster comparative studies and to understand genome organization in different oyster taxa.     

rDNA (18S-28S and 5S) colocalization and linkage between ribosomal genes and (TTAGGG)(n) telomeric sequence in the earthworm,Octodrilus complanatus (Annelida: Oligochaeta: Lumbricidae), revealed by single- and double-color FISH

Spermatogonial and metaphase I chromosomes of the lumbricid earthworm Octodrilus complanatus (Annelida: Oligochaeta) were examined using fluorescent in situ hybridization (FISH) with three repetitive DNA probes-5S rDNA, 18S-26S rDNA, and (TTAGGG)(n). Single-color FISH consistently mapped one chromosome pair per spread using either 5S rDNA or 18S-26S rDNA as probes. Simultaneous (18S-26S)-5S and (18S-26S)-(TTAGGG)(n) FISH demonstrated that repeated units of the two ribosomal families were overlapped and closely associated with telomeric sequences.     

Molecular cytogenetics and characterization of a ZZ/ZW sex chromosome system in Triportheus nematurus (Characiformes, Characidae)

Chromosomes of Triportheus nematurus, a fish species from family Characidae, were analyzed in order to establish the conventional karyotype, location of C-band positive heterochromatin, Ag-NORs, GC- and AT-rich sites, and mapping of 18S and 5S rDNA with fluorescence in situ hybridization (FISH). The diploid number found was 2n = 52 chromosomes in both males and females. However, the females presented a pair of differentiated heteromorphic chromosomes, characterizing a ZZ/ZW sex chromosome system. The Z chromosome was metacentric and the largest one in the karyotype, bearing C-positive heterochromatin at pericentromeric and telomeric regions. The W chromosome was middle-sized submetacentric, appearing mostly heterochromatic after C-banding and presenting heterogeneous heterochromatin composed of GC- and AT-rich regions revealed by fluorochrome staining. Ag-NORs were also GC-rich and surrounded by heterochromatic regions, being located at the secondary constriction on the short arms of the second chromosome pair, in agreement with 18S rDNA sites detected with FISH. The 18S and 5S rDNA were aligned in tandem, representing an uncommon situation in fishes. The results obtained reinforce the basal condition of the ZZ/ZW sex system in the genus Triportheus, probably arisen prior to speciation in the group.     

Chromosomal Location of Ribosomal DNA (rDNA), (GATA)n and (TTAGGG)n Telomeric Repeats in the Neogastropod Fasciolaria Lignaria (Mollusca: Prosobranchia)

This paper reports on a successful application of fluorescent in situhybridization (FISH) with three repetitive DNA probes (ribosomal DNA (rDNA), (GATA)_nand (TTAGGG)_n) in the chromosomes of Fasciolaria lignaria(Mollusca: Prosobranchia: Neogastropoda). rDNA FISH consistently identified four chromosome pairs per spread in the three examined specimens. The telomeric sequence (TTAGGG)_nhybridized with termini of all chromosomes. GATA FISH revealed abundant, dispersed minisatellite regions which were not associated to the XY sex-determining mechanism as indicated by the absence of a Y specific pattern of labelling. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reduction of chromosome number in Eleocharis subarticulata (Cyperaceae) by multiple translocations

Eleocharis subarticulata is recorded as the third species of Cyperaceae with a reduced chromosome number ( n  = 3), following reports on Rhynchospora tenuis ( n  = 2) and Fimbristylis umbellaris ( n  = 3). For Eleocharis, the numbers recorded to date vary from 2 n  = 10 to 2 n  = c. 196, with x  = 5 as the possible basic number. The karyotype of E. subarticulata was studied using conventional staining (mitosis and meiosis), C-CMA₃/DAPI banding, and FISH with 45S rDNA and telomere probes. The chromosomes showed no primary constrictions, as expected in the holocentric chromosomes of Cyperaceae. The meiotic behaviour was abnormal, with a single multivalent ring of six chromosomes at metaphase I, resulting from multiple translocations. At anaphase I six chromatids migrated to each pole, evidencing the inverted meiosis, and these groups were also visible at metaphase II. The C-CMA₃/DAPI banding technique showed only four terminal GC-rich blocks. FISH with 45S rDNA probes revealed four terminal signals, probably associated with GC-rich blocks. The telomeric probe located terminal signals in all the chromosomes, besides a hybridization site in the middle of the large pair. The occurrence of ectopic telomeric sites has not been described previously for plants with holokinetic karyotypes and with reduced chromosome numbers. These data reinforce the hypothesis of the reduction in chromosome number by multiple translocations.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 457–464.