Karyotypes of some species of the genus Lessingianthus (Vernonieae,Asteraceae) and taxonomic implications

We determined the karyotypes of nine species of Lessingianthus, eight of which are here analyzed for the first time. The results include the first chromosome count for L. plantaginoides, which is tetraploid with 2n = 64. All species showed a high proportion of metacentric chromosomes combined with a lower proportion of submetacentric pairs. Only L. coriaceus had a subtelocentric chromosome pair. B chromosomes were observed in L. coriaceus and L. varroniifolius, which were subtelocentric. Differences among the karyotypes of the studied species were small, suggesting that karyotype diversity in the genus evolved by small changes in the structure of chromosomes. Karyotype features appear useful to distinguish Lessingianthus from the closely related genera Chrysolaena and Lepidaploa.     

Karyomorphological parameters and C-band distribution suggest phyletic relationships within the subtribeLimodorinae (Orchidaceae)

Karyotype attributes and heterochromatin distribution were used to characterize fourteen taxa of the subtribeLimodorinae (Orchidaceae). The karyotypes were established using morphometrical parameters following Feulgen staining and C-banding. No significant differences in heterochromatin content were found between specimens collected from various sites. Four species of theEpipactis helleborine group possess some chromosome pairs with quite similar heterochromatin patterns; some differences were found inE. distans with respect to other species of this group.Epipactis palustris differed significantly from otherEpipactis species in its different karyotype and its numerous terminal C-bands. The largest differences from the other genera were shown inLimodorum as far as karyomorphology and heterochromatin patterns were concerned. C-band distribution indicated similarity among non-homologous chromosomes, supporting a possible palaeo-polyploid origin for theCephalanthera andEpipactis karyotypes.     

Karyotype analysis and heterochromatin differentiation with Giemsa C-banding and fluorescent counterstaining inCephalanthera (Orchidaceae)

Detailed studies of the chromosomes of the three Austrian species of the genusCephalanthera showed them all to have basically similar karyotypes. BothC. damasonium (2n = 36) andC. longifolia (2n = 32) have three large and several classes of smaller chromosome pairs. The karyotype ofC. rubra (2n = 44) is composed of four large and several groups of smaller pairs. The heterochromatin in these species amounts to about 10% of total karyotype length. All the chromosomes have Giemsa-positive centromeres, but only a few have intercalary or terminal bands. Using differential fluorescent staining with DAPI/actinomycin D, quinacrine/actinomycin D (both A-T specific), and chromomycin A₃/distamycin A (G-C specific) three different types of major heterochromatic bands can be characterized in respect of their satellite DNA composition: highly A-T rich, slightly A-T rich, and very G-C rich. The chromosomes ofC. longifolia contain more A-T rich C-bands than those ofC. damasonium, while the latter's have more G-C rich heterochromatin. In both species several C-bands appear as secondary constrictions or gaps in the Feulgen-stained chromosomes, but most likely, in each species there is only one pair of chromosomes where the secondary constrictions function as nucleolus organizing regions. No major intraspecific variation could be observed except on one small chromosome pair ofC. longifolia which had a heteromorphic C-band in most individuals. Possible pathways of karyotype evolution involving polyploidy and Robertsonian events are discussed.     

Karyological Differences between Northern Dolly Varden Salvelinus malma malma and White Char Salvelinus albusfrom the Kamchatka River Basin

The karyotypes of northern Dolly Varden and white char, sympatrically inhabiting the Kamchatka River basin, were studied. The karyotype of Dolly Varden was stable: 2n= 78 andNF= 98 + 2, while in white char, polymorphism and mosaicism for the chromosome number were revealed: 2n= 76–79, NF= 98 + 2. Using a routine chromosome staining technique, the karyotype of white char (2n= 78) was shown to be identical to that of Dolly Varden. In both karyotypes, similar sets of marker chromosomes were present: two pairs of submetacentric (SM), one pair of submeta-subtelocentric (SM-ST), one pair of large acrocentric (A), and one pair of large subtelocentric (ST) chromosomes. However, the karyotypes of Dolly Varden and white char differed in the number and location of nucleolus organizer regions (NORs). In Dolly Varden, single NORs located in the telomeric regions of the marker SM-ST chromosomes were observed. In white char, NORs were multiple and located both in the telomeric regions of the marker SM-ST chromosomes and on the short and long arms of large ST chromosomes. The identical marker chromosomes indicate considerable phylogenetic relatedness between Dolly Varden and white char from the Kamchatka River basin. Variation in NORs provides evidence for the reproductive isolation of these chars and their species status.     

Chromatin differentiation between Theobroma cacao L. and T. grandiflorum Schum

A comparative analysis of mitotic chromosomes of Theobroma cacao (cacao) and T. grandiflorum (cupuaçu) was performed aiming to identify cytological differences between the two most important species of this genus. Both species have symmetric karyotypes, with 2n = 20 metacentric chromosomes ranging in size from 2.00 to 1.19 μm (cacao) and from 2.21 to 1.15 μm (cupuaçu). The interphase nuclei of both species were of the arreticulate type, displaying up to 20 chromocentres, which were more regularly shaped in cacao than in cupuaçu. Prophase chromosomes of both species were more condensed in the proximal region, sometimes including the whole short arm. Both species exhibited only one pair of terminal heterochromatic bands, positively stained with chromomycin A ₃ , which co-localized with the single 45S rDNA site. Each karyotype displayed a single 5S rDNA site in the proximal region of another chromosome pair. Heterochromatic bands were also observed on the centromeric/pericentromeric regions of all 20 chromosomes of cacao after C-banding followed by Giemsa or DAPI staining, whereas in cupuaçu they were never detected. These data suggest that the chromosomes of both species have been largely conserved and their pericentromeric chromatin is the only citologically differentiated region.     

CYTOGENETIC STUDIES OF SOME HYPOCHOERIS SPECIES (COMPOSITAE) FROM BRAZIL

Karyotypes of nine Brazilian taxa of genus Hypochoeris were studied utilizing root-tip mitotic metaphases. Two distinct groups were found. One group includes six species that showed high asymmetric bimodal karyotypes, while the second group has two species that have a karyotype similar to those observed in European species. All the species have karyotypes with 2n = 8 that are very uniform within each group, with only small morphological differences. Nucleolar organizing region and C-band patterns are shown for H. brasiliensis.     

A chromosome study of Spanish Bembidiidae and other Caraboidea (Coleoptera,Adephaga)

The karyotypes were studied of fifty-three Spanish Caraboidea species belonging to the following families: Trechidae (3 species), Bembidiidae (48), Pogonidae (1) and Harpalidae (1). Differences in the shape of the largest pair of autosomes (A pair) and the Y-chromosome are frequent among closely related species. The chromosomes of these species have a peculiar centromeric region weakly constricted and surrounded by conspicuous heterochromatic blocks. Eight species have a heteromorphic A pair, probably due to differences in the length of the nucleolar organizer. Species of the first three families either have a male karyotype of 24 chromosomes, or one derived from it, while the only species of the fourth family has a male karyotype of 39 chromosomes derived from the basic karyotype of the Harpalidae, 2n=37.     

Chromosomal variation in the scincid genus Mabuya and its arboreal relatives (Reptilia: Squamata)

Karyotypes of four East and Southeast Asian species of the genus Mabuya and representatives of three arboreal genera considered to be closely related to the genus (Apterygodon, Dasia and Lamprolepis) are examined. Mabuya rugifera and M. rudis possess 2n=32 karyotypes, whereas M. longicaudata lacks one small chromosome pair, which makes its diploid number 30. The karyotype of M. macularia quadrifasciata from southern Thailand differs from any known scincid karyotypes, including a previously reported karyotype of the conspecific Indian population, in exhibiting a high diploid number (38) and a gradual change in size from large to small chromosomes. This suggests that M. macularia may consist of more than one biological species. Karyotypes of Apterygodon vittatus, Dasia olivacea and Lamprolepis smaragdinus, while exhibiting a close similarity to most Mabuya karyotypes, suggest the occurrence of slight rearrangements involving either the deletion of two small chromosome pairs (A. vittatus), or the change of centromeric positions in medium and small chromosomes (D. olivacea and L. smaragdinus).     

The subfamily Myoxocephalinae of cottid fishes (Cottidae): Genetic divergence and phylogenetic relationships

A comprehensive study based on molecular marker and karyotype analyses has provided evidence for the monophyly of the subfamily Myoxocephalinae, which includes the genera Myoxocephalus, Megalocottus, Microcottus, Porocottus, Enophrys and Argyrocottus. In addition, the karyotype of the threadfoot sculpin Argyrocottus zanderi Herzenstein 1892 has been studied for the first time. Marker traits of karyotypes identified 13 species among six cottid genera. As the molecular genetic results confirmed, the subfamily is divided into two groups corresponding to Enophrys and Myoxocephalus. The molecular genetic data did not support the formation of tribes within the subfamily Myoxocephalinae, as proposed earlier based on morphological characters. Moreover, the genera Trichocottus and Taurocottus should be excluded from the Myoxocephalinae. The evolutionary transformations of karyotypes in cottid fish tended towards a reduction in the number of chromosomes and chromosome arms.     

The Karyotype of Chukotka Chars from the Estikhed Lake (Eastern Chukotka)

The karyotype of chars from the Estikhed Lake (Eastern Chukotka) was examined. This karyotype comprises 78 chromosomes, NF = 98. Marker chromosomes include one pair of submetacentrics, one pair of large acrocentrics, and one pair of large subtelocentrics with very short second arms. Nucleolus organizer regions are located in telomeric regions of short arms of marker submetacentric chromosomes. Small heterochromatin blocks are observed in centromeric regions of most chromosomes. The Chukotka char karyotype is very similar to that of Taranetz charSalvelinus taranetzi from the Achchen Lake: these karyotypes differ only in stability of the chromosome number.     

Molecular phylogeny and karyotype differentiation in <Emphasis Type="Italic">Paratelmatobius</Emphasis> and <Emphasis Type="Italic">Scythrophrys</Emphasis> (Anura,Leptodactylidae)

Paratelmatobius and Scythrophrys are leptodactylid frogs endemic to the Brazilian Atlantic forest and their close phylogenetic relationship was recently inferred in an analysis that included Paratelmatobius sp. and S. sawayae. To investigate the interspecific relationships among Paratelmatobius and Scythrophrys species, we analyzed a mitochondrial region (approximately 2.4 kb) that included the ribosomal genes 12S and 16S and the tRNAval in representatives of all known localities of these genera and in 54 other species. Maximum parsimony inferences were done using PAUP* and support for the clades was evaluated by bootstrapping. A cytogenetic analysis using Giemsa staining, C-banding and silver staining was also done for those populations of Paratelmatobius not included in previous cytogenetic studies of this genus in order to assess their karyotype differentiation. Our results suggested Paratelmatobius and Scythrophrys formed a clade strongly supported by bootstrapping, which corroborated their very close phylogenetic relationship. Among the Paratelmatobius species, two clades were identified and corroborated the groups P. mantiqueira and P. cardosoi previously proposed based on morphological characters. The karyotypes of Paratelmatobius sp. 2 and Paratelmatobius sp. 3 described here had diploid chromosome number 2n = 24 and showed many similarities with karyotypes of other Paratelmatobius representatives. The cytogenetic data and the phylogenetic analysis allowed the proposal/corroboration of several hypotheses for the karyotype differentiation within Paratelmatobius and Scythrophrys. Namely the telocentric pair No. 4 represented a synapomorphy of P. cardosoi and Paratelmatobius sp. 2, while chromosome pair No. 5 with interstitial C-bands could be interpreted as a synapomorphy of the P. cardosoi group. The NOR-bearing chromosome No. 10 in the karyotype of P. poecilogaster was considered homeologous to chromosome No. 10 in the karyotype of Scythrophrys sp., chromosome No. 9 in the karyotype of Paratelmatobius sp. 1, chromosome No. 8 in the karyotypes of Paratelmatobius sp. 2 and of Paratelmatobius sp. 3, and chromosome No. 7 in the karyotype of P. cardosoi. A hypothesis for the evolutionary divergence of these NOR-bearing chromosomes, which probably involved events like gain in heteochromatin, was proposed.     

Karyomorphological analyses and heterochromatin characteristics disclose phyletic relationships among 2n = 32 and 2n = 36 species ofOrchis (Orchidaceae)

The karyotypes of eight taxa ofOrchis L. with 2n = 32 and 2n = 36 have been investigated using morphometrical measurements following staining with Feulgen, Giemsa (C-banding) and the DNA specific fluorochrome Hoechst 33258. The karyotypes ofO. coriophora subsp.fragrans, andO. papilionacea proved to be the most asymmetrical, whileO. morio andO. longicornu exhibited the most symmetrical karyotypes. Using C-banding and the fluorochrome H33258 only the taxa with high asymmetry indices showed the presence of differentially stained chromatin bands. In most chromosomes heterochromatin bands were present at the telomeric position. The present results seem to indicate that the analysed species do not form a homogeneous group and further subdivisions are possible, which, in turn, do not always correlate with divisions based on morphological characters. Both karyomorphology and heterochromatin distribution coincide in indicating a possible evolutionary pathway.     

Karyotype analysis of Eucinostomus argenteus, E. gula, E. harengulus, and Eugerres plumieri (Teleostei, Gerreidae) from Florida and Puerto Rico

The karyotypes of four gerreids of the western Atlantic Ocean are documented. A diploid chromosome complement of 48 telocentric chromosomes was found in the four species (2N=48t, fundamental number FN=48). No differences were detected either in the number of chromosomes of the standard karyotype, in their karyotype size, or between the karyotypes derived from male or female specimens of any of the species. Chromosome length decreased progressively and slightly from pair 1 to pair 24. The Ag–NOR karyotypes of E. argenteus and E. harengulus were characterized by the position of the nucleolar organizer regions next to the centromere in chromosome pair 1, whereas in E. gula and E. plumieri Ag–NORs were detected in pair 4. The other 46 chromosomes showed a light staining of the centromere with no terminal or intermediate heterochromatic blocks. All Eucinostomus species showed Ag–NORs of similar size, while Eugerres plumieri showed Ag–NORs 10–20% larger than Eucinostomus species. A combination of size and position of the Ag–NORs identified E. gula, while size alone identified E. plumieri. However, the ancestral state for size and position of Ag–NORs could not be established. There was no differential staining of the chromosomes by G-banding. The karyotype of the gerreids appears similar to the hypothetical ancestral karyotype of fish. The phylogenetic relationships among these species could not be established because of the lack of chromosome G-bands. Most likely this indicates a homogeneous distribution of GC nucleotides in the chromosomes.     

A study of heterochromatin in Drosophila nasuta by the 5-bromodeoxyuridine-giemsa staining technique

Larval brain ganglia of Drosophila nasuta were cultured in vitro in the presence of 5-bromodeoxyuridine for 1 or 5 h at 24° C and the air-dried chromosome preparations stained by the Hoechst 33258-Giemsa technique to reveal bromodeoxyuridine induced sister chromatid differentiation. In 1 h as well as 5 h preparations, 10–15% of well spread metaphase plates show a sister chromatid differentiation in only C-band heterochromatin regions of different chromosomes. We infer that this sister chromatid differentiation in all heterochromatic regions is seen after bromodeoxyuridine incorporation for only one replication cycle and is related to the presence of asymmetric A-T rich satellite sequences in all the C-band regions of D. nasuta karyotype.     

A cytogenetic study on congenital limb malformations in the Japanese monkey (Macaca fuscata)

A cytogenetic investigation was performed on 88 Japanese monkeys (Macaca fuscata) with abnormal limbs from 11 free-ranging provisioned troops including nine individuals with abnormalities indistinguishable as to whether they were congenital or injurious. All of the monkeys with abnormal limbs including the nine questionable individuals had the same karyotypes as those of normal individuals. The chromosome number was 42, consisting of 20 bi-arm autosome pairs and a submetacentric X-chromosome and Y-chromosome. The ninth chromosome pair, which was the only chromosome pair with remarkable secondary constriction, displayed length polymorphism of the centromeric C-band and secondary constriction in both deformed and normal monkeys. These kinds of variants have also been commonly found in other monkey species, which have almost the same karyotype as the Japanese monkey and have not been reported to show frequent occurrence of limb malformation. We concluded therefore that chromosomal abnormalities could be excluded from the main causal factors for limb malformations of the Japanese monkey.     

Cytogenetic Studies on Workers of the Neotropical Ant Wasmannia auropunctata (Roger 1863) (Hymenoptera: Formicidae: Myrmicinae)

Wasmannia auropunctata is known as one of the worst invasive ants in the World. A cytogenetic study was conducted on two native populations from southeastern Bahia, Brazil. The analysis of the chromosomes observed in mitotic metaphases was made by a combination of methods: Giemsa conventional staining, chromomycin A3 (CMA3) and 4-6-diamidino-2-phenylindole (DAPI) fluorochrome staining, and acridine orange banding. The workers have all the karyotype 2n=32, with ten pairs of metacentric and six pairs of acrocentric chromosomes. One chromosome arm of the pair ten was positive for CMA3 and acridine orange, suggesting the occurrence of a nucleolar organizing region. This region is an interesting marker because is very conservative and seems to constitute an interesting specific taxonomic character. The pericentromeric region of many chromosomes was stained with DAPI, evidencing the occurrence of AT bases rich heterochromatin.     

The chromosomes of Lepturinae (Coleoptera: Cerambycidae) II. A study of eight more species,with focus on Desmocerus palliatus

Following the study of 28 species of Lepturinae (Coleoptera: Cerambycidae) the karyotypes of seven additional Palaearctic and one Nearctic species are established. The 19,X male karyotypes found in genera Stictoleptura (four species), Vadonia and Judolia (one species each) confirm the loss of Y chromosome in Lepturini. The 22,XY male karyotype of Cortodera humeralis is very close to that of some species of Rhagiini (genera Gaurotes, Acmaeops, Dinoptera, all 22,XY) and Grammoptera ruficornis (24,XY) recently reported. We propose that these taxa could form a monophyletic group within Rhagiini. The karyotype of the Nearctic species Desmocerus palliates (23,neoXneoXneoY) is quite different and characterized by the presence of many acrocentric chromosomes and a complex autosome–gonosome translocation. Its particular karyotype is compatible with its present classification within a separate tribe, the Desmocerini.     

Heterochromatin accumulation,disposition and diversity in Gibasis karwinskyana (Commelinaceae)

C-banding differences within Gibasis karwinskyana (Roem & Schult.) Rohw. were reassessed using dual fluorochrome staining. Pronounced differences in C-band pattern between two subspecies with identical basic karyotypes were due to different chromosomal locations of AT-rich and GC-rich heterochromatin. The AT-rich component had an equilocal distribution in the karyotype and has evidently been accumulated at telomeres, as shown by its prevalence in supernumerary segments and B chromosomes. The GC-rich component also varied in amount, but was limited to nucleolus organizing regions (NORs) and centromeres. Centromeres and telomeres are suggested to constitute separate, although perhaps interdependent, centres of heterochromatin amplification. The possible role of nuclear architecture in determining the accumulation, distribution and spread of these sequences is discussed.Abbreviations H Hoechst 33258 - CMA chromomycin A3 - NOR nucleolus organizing region - SS supernumerary segment - Q quinacrine dihydrochloride - H⁺ H etc. indicate enhanced (+) and quenched (-) fluorescence with the stated fluorochrome by H.C. Macgregor     

Karyological differences of the Northern Dolly Varden Salvelinus malma malma and the white char Salvelinus albus from the Kamchatka River basin

The karyotypes of northern Dolly Varden and white char, sympathrically inhabiting the Kamchatka River basin, were studied. The karyotype of Dolly Varden was stable: 2n = 78 and NF = 98 + 2, while in white char, polymorphism and mosaicism for the chromosome number were revealed: 2n = 76-79, NF = 98 + 2. Using a routine chromosome staining technique, the karyotype of white char (2n = 78) was shown to be identical to that of Dolly Varden. In both karyotypes, similar sets of marker chromosomes were present: two pairs of submetacentric (SM), one pair of submeta-subtelocentric (SM-ST), one pair of large acrocentric (A), and one pair of large sub-telocentric (ST) chromosomes. However, the karyotypes of Dolly Varden and white char differed in the number and location of nucleolus organizer regions (NORs). In Dolly Varden, single NORs located in the telomeric regions of the marker SM-ST chromosomes were observed. In white char, NORs were multiple and located both in the telomeric regions of the marker SM-ST chromosomes and on the short and long arms of large ST chromosomes. The identical marker chromosomes indicate considerable phylogenetic relatedness between Dolly Varden and white char from the Kamchatka River basin. Variation in NORs provides evidence for the reproductive isolation of these chars and their species status.     

Comparative karyological studies on the species of Eubothrium Nybelin, 1922 (Cestoda: Pseudophyllidea)

Karyotypes of Eubothrium salvelini, E. crassum and Eubothrium sp. were studied using conventional Giemsa staining and comparative karyometric analysis. The karyotypes, reported here for the first time, consist of eight chromosome pairs. The two first pairs of homologues are metacentric and markedly larger than the remaining elements. The obvious similarity in karyotype structure does not exclude the possibility of discriminating E. salvelini and E. crassum using karyotypic characters. The best cytogenetic marker is the last pair of chromosomes, which is acrocentric in the karyotype of E. salvelini and metacentric in that ofE. crassum. Karyological observations provide strong evidence for assigning Eubothrium sp. from Clupea harengus membras to E. crassum. Comments are made on the karyotypes of these and related species with respect to their phylogenetic links.