Taxonomy of the genusBrimeura (Hyacinthaceae)

A taxonomic reevaluation of two little-knownBrimeura taxa,B. fontqueri (Pau)Speta andB. duvigneaudii (L. Llorens)Rosselló et al., has been made.Brimeura fontqueri, described from the Iberian peninsula, has been put into synonymy ofB. amethystina (L.)Salisb., since it could not be distinguished on morphological, anatomical or cytogenetic grounds.Brimeura duvigneaudii, from the Balearic Islands, is closely related toB. amethystina and has 2n=28 chromosomes. It differs from the latter by its naked bulbs lacking dark cataphylls, and its narrower leaves and whitish corollas. Accessory chromosomes are reported for the first time in the genus. Karyological instability (with chromosome numbers ranging from 2n=28 to 42) is reported for a population ofB. fastigiata (Viv.)Chouard. A key to the recognized taxa ofBrimeura is provided.     

Karyotypes and geographical distribution of ricefishes from Yunnan,southwestern China

Morphometric and karyotypic studies were made on two species of ricefishes collected from Yunnan, southwestern China.Oryzias latipes from Yunnan had the same morphological and karyological characteristics asO. latipes collected from eastern China. The Yunnan populations had 2n, 46 chromosomes consisting of 3 metacentric, 8 submetacentric, 2 subtelocentric, and 10 acrocentric pairs, the arm number (NF) being 68 (2n=46, NF=68, 3M+8SM+2ST+10A). The karyotype was characterized by having a “large” metacentric pair and nucleolus organizer regions (NORs) on the short arms of a submetacentric pair.Oryzias minutilius from Yunnan had the same morphological characteristics asO. minuiillus from Thailand and Burma, although the karyotype was different from that collected from Thailand. The Yunnan population had 2n, 42 chromosomes consisting of 21 acrocentric pairs, NF being 42 (2n=42, NF=42, 21A). The karyotype was characterized by having NORs at the telomeric regions of an acrocentric pair.Oryzias latipes occurs widely on the eastern Yunnan Plateau where the climate is temperate or subtropical, whereasO. minutilius is found in Xishiangbanna, the southern low mountain areas of Yunnan, where the climate is tropical.     

The karyotype of Axarus festivus (Say) and a comparison with species of Lipiniella (Chironomidae: Diptera)

Larvae of Axarus andLipiniella share several apparantly apomorphic features of the mouth-part structure, however adults ofLipiniella show possible relationships toDemeijerea andChironomus. In order to assist in refining the relationships ofAxarus toLipiniella the karyotype ofAxarus festivus was determined and compared to the karyotypes ofLipiniella arenicola andL. moderata. Larvae ofA. festivus from a population in Kansas were monomorphous, with 2n=8, the Ist, IInd and IIIrd chromosomes metacentric, and IVth acrocentric.Axarus festivus therefore differs fromL. arenicola in chromosome number (2n=6), however homologous sections of all chromosomes were identified. Inversions were detected in the Ist, IInd and IIIrd chromosomes ofA. festivus relative toL. arenicola. It was determined that both species have high functional activity, as indicated by the presence of three Balbiani rings, and more than one nucleolus per genome. Differing degrees of polyteny, a feature previously described forL. arenicola, were observed in the salivary glands, with highest degrees of polyteny in cells near the salivary duct. These similarities of chromosome structure indicate close genetic relationships betweenA. festivus andL. arenicola. However, we did not find evidence for similarity ofA. festivus toL. moderata, which supports the previous conclusions byKiknadze et al. (1989) regardingL. arenicola andL. moderata.     

Chromosomal banding pattern and idiogram of the cotton rat,Sigmodon arizonae (Rodentia,Muridae)

A procedure for obtaining G-bands on chromosomes of mammals is outlined. The procedure was utilized in an investigation of the idiogram and banding pattern of the mitotic chromosomes of the cotton rat, Sigmodon arizonae. The diploid number of this species is 22, and each pair of homologues is easily separated on the basis of size, centromeric position, and banding pattern. The autosomes are represented by four pairs of large submetacentric chromosomes, three pairs of medium to small submetacentric chromosomes, two pairs of large subtelocentric chromosomes and one pair of small acrocentric chromosomes. The X chromosome is acrocentric and averages from 5.42% to 5.46% of the haploid female complement. The Y chromosome is a minute acrocentric and easily separated from the smallest acrocentric autosome. The usefulnes of Sigmodon arizonae as a laboratory animal for cytogenetic studies is substantiated.     

Multiple sex chromosome system of X1X1X2X2/X1X2)Y type in lutjanid fish, Lutjanus quinquelineatus (Perciformes)

The karyotype and other chromosomal markers as revealed by C-banding and Ag-staining were studied in Lutjanus quinquelineatus and L. kasmira (Lutjanidae, Perciformes). While in latter species, the karyotype was invariably composed of 48 acrocentric chromosomes in both sexes, in L. quinquelineatus the female karyotype had exclusively 48 acrocentric chromosomes (2n = 48) but that of the male consisted of one large metacentric and 46 acrocentric chromosomes (2n = 47). The chromosomes in the first meiotic division in males showed 22 bivalents and one trivalent, which was formed by an end-to-end association and a chiasmatic association. Multiple sex chromosome system of X₁X₁X₂X₂/X₁X₂Y type resulting from single Robertsonian fusion between the original Y chromosome and an autosome was hypothesized to produce neo-Y sex chromosome. The multiple sex chromosome system of L. quinquelineatus appears to be at the early stage of the differentiation. The positive C-banded heterochromatin was situated exclusively in centromeric regions of all chromosomes in both species. Similarly, nucleolus organizer region sites were identified in the pericentromeric region of one middle-sized pair of chromosomes in both species. The cellular DNA contents were the same (3.3 pg) between the sexes and among this species and related species.     

Chromosome polymorphism in <Emphasis Type="Italic">Rineloricaria pentamaculata</Emphasis> (Loricariidae,Siluriformes) of the Paraná River basin

Cytogenetic analysis in three Rineloricaria pentamaculata populations revealed diploid number 2n = 56 chromosomes, karyotype formula 8m/sm + 48st/a and FN = 64. Owing to the presence of the heteromorphic chromosome pair with a big submetacentric chromosome and a small acrocentric one in both males and females, 42.9% of specimens in the Tauá Stream population had the karyotype formula 9m/sm + 47st/a and FN = 65. Analysis of the nucleolus-organizing region by Ag-NOR and FISH techniques showed a single NOR system at pair 5 for R. pentamaculata populations of the Keller River and the Tauá Stream. However, specimens of populations of the Tatupeba Stream had multiple NOR systems at pairs 5 and 8. A constitutive heterochromatin pattern in R. pentamaculata is mainly distributed in the pericentromeric and telomeric regions with interstitial markers in certain chromosomes. Heterochromatin is located in the telomeric and centromeric positions of the acrocentric chromosome in the heteromorphic pair of the Tauá Stream population. In the submetacentric chromosome the markings are located in the telomeric (short arm), pericentomeric and interstitial (long arm) positions. The origins of polymorphisms are discussed.     

Karyotype of the Snow Sculpin <Emphasis Type="Italic">Myoxocephalus brandti</Emphasis> Steindachner (Cottidae) from Peter the Great Bay,Sea of Japan

The karyotype of the snow sculpin Myoxocephalus brandti, 2n = 44, NF = 46, from Peter the Great Bay was studied. Two-armed chromosomes were presented by one pair of metacentric chromosomes of medium size; one-armed chromosomes included two pairs of large subtelocentric chromosomes and a pair of large acrocentric chromosomes. Ag-NOR-staining in the telomere vicinity revealed nucleolus-organizing regions in one metacentric chromosome and in one medium size acrocentric chromosome in one of the fishes, in two homological small acrocentric chromosomes in three fishes, and in one acrocentric chromosome of average size in six fishes. No difference between the male and female karyotypes and any type of variability was revealed. The karyotypes of the snow sculpin M. brandti and the frog sculpin M. stelleri were compared. Their distinctions and similarities were displayed.Original Russian Text Copyright ¢ 2005 by Biologiya Morya, Ryazanova.     

Karyotype studies in seven species of cyprinidae

The present report embodies karyotype studies of seven Indian cyprinids. Of these, the karyotypes of five species possess chromosomes all of which are acrocentric. These areLabeo calbasu (Ham.) 2n=54,Puntius sophore (Ham.),P. conchonius Ham.,P. stigma (Ham.) 2n=50 andChela bacaila (Ham.) 2n=52. The karyotype ofCrossocheilus latius punjabensis Mukerji has 48 chromosomes, 12 of which are metacentric (2n=12m+36r's). InAmblypharyngodon mola (Ham.), 52 chromosomes form the diploid set which include 8 metacentrics. In none of the seven species morphologically distinguishable sex chromosomes were found.Literature on cyprinid karyotypes has been reviewed in order to understand in how far the cytological characters are in agreement with the classification based on morphological studies. The validity ofMatthey's notion of nombre fondamental to establish kinship between cytologically known cyprinid species has also been discussed.     

Note on the karyotype and NOR phenotype of leuciscine fish Acanthobrama marmid (Osteichthyes, Cyprinidae)

The karyotype and major ribosomal sites as revealed using silver staining of Anatolian leuciscine cyprinid fish Acanthobrama marmid were studied. The diploid chromosome number was invariably 2n = 50. Karyotype consisted of eight pairs of metacentric, 13 pairs of submetacentric and four pairs of subtelocentric to acrocentric chromosomes. The largest chromosome pair of the complement was subtelo-to acrocentric characteristically, which is a characteristic cytotaxonomic marker for representatives of the cyprinid lineage Leuciscinae. The nucleolar organizer regions (NORs) were detected in the telomeres of two pairs of medium sized submeta-to subtelocentric chromosomes. No heteromorphic sex chromosomes were found. The karyotype pattern of A. marmid is nearly identical to that found in most other representatives of the Eurasian leuciscine cyprinids, while the multiple NOR phenotype appears to be more derived as opposed to a uniform one, ubiquitous in this group.     

A complex sex-chromosome system in the hare-wallaby Lagorchestes conspicillatus Gould

Among specimens of the spectacled hare-wallaby Lagorchestes conspicillatus Gould (Marsupialia, family Macropodidae) 4 males had 15 chromosomes and 2 females 16 chromosomes. The sex chromosomes are X₁X₁X₂X₂ in the female and X₁X₂Y in the male, the Y being metacentric and both X chromosomes are acrocentric. In about 96% of sperm mother cells at meiosis the sex chromosomes form a chain trivalent and in more than 99% of these this orients convergently so that the X₁ and X₂ move to the same pole. Evidence is presented that L. conspicillatus has evolved from a form with 22 chromosomes including a small X and a minute Y. Autoradiographic studies show that the proximal fifth of the X₁ chromosome replicates late. This is probably the ancestral X chromosome which has been translocated to an autosome. The fate of the original Y is obscure but an hypothesis is proposed that it forms the centromeric region of the Y. A single male had 14 chromosomes and was heterozygous for a translocation involving the centric fusion of two acrocentric autosomes. In about 30% of sperm mother cells the autosomal trivalent did not disjoin regularly but, despite this, all secondary spermatocytes observed at metaphase 2 had balanced complements of chromosomes. It is assumed that unbalanced secondary spermatocytes died before reaching metaphase.     

Physical mapping of the 5S ribosomal RNA genes in Arabidopsis thaliana by multi-color fluorescence in situ hybridization with cosmid clones

The 5S ribosomal RNA genes were mapped to mitotic chromosomes of Arabidopsis thaliana by fluorescence in situ hybridization (FISH). In the ecotype Landsberg erecta, hybridization signals appeared on three pairs of chromosomes, two of which were metacentric and the other acrocentric. Hybridization signals on one pair of metacentric chromosomes were much stronger than those on the acrocentric and the other pair of metacentric chromosomes, probably reflecting the number of copies of the genes on the chromosomes. Other ecotypes, Columbia and Wassilewskija, had similar chromosomal distribution of the genes, but the hybridization signals on one pair of metacentric chromosomes were very weak, and detectable only in chromosomes prepared from young flower buds. The chromosomes and arms carrying the 5S rDNA were identified by multi-color FISH with cosmid clones and a centromeric 180 bp repeat as co-probes. The metacentric chromosome 5 and its L arm carries the largest cluster of the genes, and the short arm of acrocentric chromosome 4 carries a small cluster in all three ecotypes. Chromosome 3 had another small cluster of 5S rRNA genes on its L arm. Chromosomes 1 and 2 had no 5S rDNA cluster, but they are morphologically distinguishable; chromosome 1 is metacentric and 2 acrocentric. Using the 5S rDNA as a probe, therefore, all chromosomes of A. thaliana could be identified by FISH. Chromosome 1 is large and metacentric; chromosome 2 is acrocentric carrying 18S-5.8S-25S rDNA clusters on its short arm; chromosome 3 is metacentric carrying a small cluster of 5S rDNA genes on its L arm; chromosome 4 is acrocentric carrying both 18S-5.8S-25S and 5S rDNAs on its short (L) arm; and chromosome 5 is metacentric carrying a large cluster of 5S rDNA on its L arm.     

Chromosomal description of the rodent generaOecomys andNectomys from Brazil

We analysed karyotypes of five taxa of the rodent generaOecomys andNectomys, trapped in 14 localities in an area ranging from 8° to 29°S on Brazilian territory.Oecomys cf.concolor, collected in the Amazon and in two localities of the Cerrado biome, showed a 2n=60 karyotype constituted by a pair of large subtelocentric chromosomes, a small metacentric pair and 27 acrocentric pairs. The X chromosome was a large submetacentric and a subtelo-submetacentric, the morphology of the latter showing variable C-banding patterns. In all three localities the Y chromosome was a medium size heterochromatic acrocentric. Two individuals from the Cerrado had a heterochromatic acrocentric B-chromosome.Oecomys cf.bicolor presented two cytotypes, 2n=80 in the specimens from the Cerrado biome and 2n=82 in individuals trapped in the Amazon. The 2n=80 cytotype 1 showed a large subtelocentric, 22 biarmed pairs (medium to small) and 16 acrocentric autosomal pairs. The karyotype of the 2n=82 cytotype 2 is constituted by 15 biarmed chromosomes (median to small) and 25 acrocentric pairs with heterochromatic blocks at pericentromeric regions. The sexual pairs were the same (large submetacentric X and median acrocentric Y) in both cytotypes. InO. cf.concolor and in both cytotypes ofO. cf.bicolor the nucleolar organizer regions were observed in 1-3 pairs, located in the short arms.Nectomys genus presented two cytotypes, 2n=52–55 (N. rattus, with 0–3 biarmed heterochromatic accessory chromosomes) and 2n=56–59 (N. squamipes, bearing 0–3 biarmed, heterochromatic, B-chromosomes). These 2 cytotypes occupy disjunct regions of South America, with overlapping areas in the Brazilian states of Pernambuco, Bahia, and Mato Grosso do Sul.     

Karyotypes of metaphase chromosomes in diploid populations of<Emphasis Type="Italic"> Dendranthema zawadskii</Emphasis> and related species (Asteraceae) from Korea: diversity and evolutionary implications

Although the Dendranthema zawadskii complex has been known to comprise a series of polyploids (4×, 6×, 8×), we found diploid individuals (with 2n=18) to occur in four populations of D. zawadskii var. latilobum in the southern region of Korea. Karyotypes of metaphase chromosomes were diverse because numbers of metacentric, submetacentric, and acrocentric chromosomes differ even within a population. A total of 17 karyotypes were found in 31 diploid individuals collected from the four populations. The karyotypes were also diverse in the presence or absence of chromosomes with a secondary constriction on a short or long arm and, if present, in the number of such chromosomes. They were further diverse in the presence or absence of non-homologous chromosome(s), the presence or absence of a chromosome with a satellite, and, if present, how many and where satellites are present. Almost the same pattern of diversity was found in diploid individuals (with 2n=18) of D. boreale and D. indicum as well, irrespective of whether they occur together with D. zawadskii var. latilobum or not. Structural features of chromosomes in the variously different karyotypes suggest that reciprocal translocation and the hybridization between individuals with different karyotypes had repeatedly occurred not only in D. zawadskii var. latilobum, but also in D. boreale and D. indicum. Morphologically intermediate individuals between D. zawadskii var. latilobum and D. indicum suggests that the hybridization occur with different species as well. Electronic Publication     

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.     

Karyotype with 210 chromosomes in guaraná (<Emphasis Type="Italic">Paullinia cupana</Emphasis> ‘Sorbilis’)

The genus Paullinia includes the economically important P. cupana, known as guaraná in Brazil and more recently in the world market. Native Americans of the Maué and Andirá tribes cultivated P. cupana ‘Sorbilis’ in central Amazon, and the Barés cultivated the ‘Typica’ variety in the upper Negro River (Brazil). Cytological studies in the Sapindaceae family have concentrated on the diversity in number (from 2n = 14 to 96) and size of the chromosomes. In Paullinia, seven species have been karyotyped and all show 2n = 24. Meristem maceration, cellular dissociation and air-drying techniques were used for cytogenetic preparations and DNA content was determined by flow cytometry. Chromosome characterization and DNA content of Paullinia cupana Kunth ‘Sorbilis’ (Mart.) Ducke (Sapindaceae) were studied. The high chromosome number (2n = 210) fall into two cytomorphological groups: (a) a metacentric and submetacentric group showing 25 sets of three pairs of chromosomes (2–76); (b) a group containing only acrocentric showing 12 sets of two pairs of chromosomes (82–105), a homologous submetacentric pair (1) and an acrocentric pair (81). Mean nuclear DNA content of guaraná was 2C = 22.8 pg. A karyogram was set up showing a high chromosome number complement.     

The karyotype of the Azumi shrew<Emphasis Type="Italic">Sorex hosonoi</Emphasis>

Karyotype ofSorex hosonoi Imaizumi, 1954 from Mt. Asama in central Honshu, Japan, were examined with conventional staining and G-banding using ASG methods. The diploid and fundamental autosomal arm numbers were 42 and 66, respectively. The autosomes consisted of seven metacentric, six submetacentric, and seven acrocentric pairs. The sex chromosomes were large-sized acrocentric X and small-sized subtelocentric Y. The relationship between the karyotypes ofS. hosonoi andS. shinto was explained by one pericentric inversion at the no. 5 ofS. hosonoi and the no. 9 ofS. shinto. A rearrangement inS. shinto-hosonoi differed from the rearrangements occurring on no. 5 ofS. shinto-caecutiens/unguiculatus.     

Revision of Asian species of the Drosophila melanica species group (Diptera: Drosophilidae), with a description of a new species from Vietnam

A new species of the Drosophila (Drosophila) melanica species group (Diptera: Drosophilidae), Drosophila denruoi Suwito & Watabe, sp. nov., is described from northern Vietnam. It is proved by crossing experiments that reproductive isolation is complete between this species and other morphologically similar species. Larval ganglion cells of D. denruoi possess 2n = 12 chromosomes, comprised of four pairs of acrocentric, one pair of metacentric and one pair of micro‐chromosomes. This is the largest number of acrocentric chromosomes in the group and implies that the species has the most primitive chromosomal configuration in the melanica group. Based on the results of crossing experiments and close morphological examination, Drosophila pengi Okada & Kurokawa, 1957 from central Japan, once regarded as a synonym of Drosophila tsigana Burla & Gloor, 1952, is shown to be distinct from D. tsigana. Drosophila pengi is thus resurrected as a member of the melanica group. We synonymize Drosophila bisetata Toda, 1988, described from central Myanmar, with D. pengi. In addition, a population from Guizhou, southwestern China, once regarded as D. tsigana, is also identified as D. pengi. These populations from central Myanmar and southwestern China share the diagnostic characters of D. pengi. At the same time, it is reconfirmed that the Hokkaido population is conspecific with European D. tsigana. Furthermore, another species, Drosophila longiserrata Toda, 1988 described from central Myanmar, is synonymized with Drosophila afer Tan, Hsu & Sheng, 1949 from China, based on their having identical karyotypes and external morphology.     

Sympatric occurrence of three cytotypes and four morphological types of B chromosomes of Astyanax scabripinnis (Pisces, Characiformes) in the River Ivaí Basin, state of Paraná, Brazil

Chromosomes of Astyanax scabripinnis from the Tatupeba stream, Ivaí basin (state of Paraná, Brazil), were analyzed. Astyanax scabripinnis population presents 3 different diploid numbers (2n = 46, 48 and 50) and B chromosomes in each cytotype. Eighty per cent of the females among individuals of cytotype I (2n = 50) has a metacentric B macrochromosome, whereas three different types of B chromosomes were identified in individuals of cytotype II (2n = 48). Cytotype III (2n = 46) showed two B chromosomes of different morphologic types (metacentric macrochromosomes and acrocentric) in all specimens and cells analyzed. Constitutive heterochromatin pattern for the three cytotypes showed weak markings in centromeric regions and conspicuous blocks in the telomere regions of ST and A chromosomes. Whereas C-banding showed that B chromosomes were totally or partially heterochromatic, a discussion on their behavior and origin was also undertaken.     

Evidence for eight tandem and five centric fusions in the evolution of the karyotype ofAethomys namaquensis A. Smith (Rodentia: Muridae)

G- and C-banded chromosomes ofAethomys namaquensis (2n=24),A. chrysophilus (2n=44), andPraomys coucha (2n=36) are compared and contrasted with publised material on Australian Muridae and North American Sigmodontidae. Direction and types of chromosomal rearrangements are established using cladistic methodology. An acrocentric morphology for chromosomes 5, 14, 15 and 20 (numbering system fromPeromyscus) are proposed as primitive for the common ancestor of the Muridae and Sigmodontidae rodent lineages. Reduced diploid number ofAethomys namaquensis is derived by eight tandem and five centric fusions since divergence from the common ancestor withA. chrysophilus. The two species ofAethomys share one derived metacentric chromosome that distinguishes them fromPraomys. Praomys has unique chromosomes which can be derived from the proposed primitive condition by five centric fusions and five pericentric inversions. It is concluded that karyotypic orthoselection for tandem and centric fusions is best explained by cellular or biochemical mechanisms rather than variation in population characteristics.     

A comparative cytogenetic study of five piranha species (Serrasalmus,Serrasalminae) from the Amazon basin

Cytogenetic studies were conducted on five piranha species belonging to the genus Serrasalmus, subfamily Serrasalminae (Serrasalmus altispinis, S. compressus, S. elongatus, S. manuelli, and S. spilopleura). All the species were collected in the Amazon basin: confluence of Negro and Solimõoes Rivers (CatalãoLake), Solimões River (Marchantaria Island – Camaleão Lake), Uatumã River (Hydroelectric Power Station of Balbina), and Pitinga River (Hydroelectric Power Station of Pitinga). All the five species possess 2n = 60 chromosomes with 5–12 subtelo- and acrocentric chromosomes bearing nucleolar organizer regions. A proximal C-band positive heterochromatin block was evident on the long arms of a medium-sized metacentric chromosome pair in all the analized species, thus making it a cytogenetic marker for the genus. It is hypothesized that 2n = 60 chromosomes represents a derived feature in terms of the chromosomal evolution of piranhas because the basal lineages possess 2n = 62. Both Robertsonian centric fusion and non-Robertsonian rearragements such as pericentric inversions seem implicated in the chromosomal evolution of this group.