Pairs Of Telocentric Chromosomes Research Articles

Karyotype analysis of Neodiplostomum seoulense.

A karyotype analysis of the chromosome of Neodiplostomum seoulense, one of causative agents of human intestinal trematodiasis, was done from the gonad tissue by the squashing method. The chromosome number was n = 10 and 2n = 20. Chromosome length was 1.30-4.0 microns. Chromosome pairs in the complement consisted of two pairs of metacentric, five pairs of submetacentrics/subtelocentric and three pairs of telocentric chromosomes. These data were comparable with those of other intestinal trematodes.

Cytogenetics of vesper mice, Calomys (Sigmodontinae): a new karyotype from the Puna region and its implication for chromosomal phylogeny.

The karyotype of specimens identified as Calomys lepidus, trapped at 3600 m above sea level in the Puna region, northwestern Argentina, was studied. All specimens analysed showed a 2n = 44 (NF(a) = 68) asymmetrical karyotype with 13 pairs of metacentric/submetacentric autosomes and 7 pairs of telocentric chromosomes. The X was a medium-sized submetacentric and the Y a small submetacentric chromosome. This karyotype was quite different from that previously described for C. lepidus from Peru (2n = 36, NF(a) = 68). However, both karyotypes may be easily interrelated by means of four centric fusions, and the chromosome complement of Punian C. lepidus fitted into a previously proposed chromosomal phylogeny of the genus. In addition, the spermatozoa of specimens corresponded to a morphological pattern previously described for other species of Calomys.

On the mechanism of homologous synapsis in lycosid spiders

Lycosid spiders have 13 pairs of telocentric chromosomes and 2 nonhomologous sex chromosomes in males. At leptotene, the kinetochore ends are attached to the nuclear envelope via thickened attachment plaques. Homologous synapsis begins at the attachment plaques and proceeds zipper-like through the length of the synaptonemal complex. We have tested whether or not this simple form of homologous synapsis is obligatory by inducing reciprocal translocations. Since we find many irradiated cells with quadrivalents at diakinesis-prometaphase and metaphase I, clearly a backup system exists that can bring together homologous segments disparate from each other in the nucleus. This mechanism apparently does not depend on end-initiated synapsis. Furthermore, we have found in previous studies that wolf spider bivalents are always unichiasmate, with either proximally or distally placed chiasmata. Since many chain quadrivalents, but no ring quadrivalents, were seen in this study, crossing over and chiasma placement obey a different set of rules when homologous segments are switched between chromosomes.

Cytological Abnormality Control Seed Set in Panicum repens L. in Egypt.

The cytology, meiotic behaviour and breeding system were investigated in this work for Panicum repens trying to find out its genetic situation with other Egyptian species and to study the reasons cause reduction in seed set and induce sterility. Mitotic counts of chromosomes shows 36 as tetraploid species based on 9 as basic number. Based on length and centromere position the karyotype formula shows 14 pairs of metacentric, 3 pairs of submetacentric and one pair of telocentric chromosomes. The mean chromosome length measure 0.97μm and arm ratio of 1.25. The heterogenity in chromosome set suggests the alloploid origin of the species.Meiotic behaviour of chromosomes was found somehow irregular with high frequency of univalents and low multivalents. The latter insures that the species is not autotetraploid in origin. Also the high level of univalents suggests the structural hybridity of the species. Irregular meiosis lead to form abnormal pollen and non functional gamets which directly decrease fertility and probably affect seed set either at open or self pollination. Cytological results indicate that the species is cytologically complex with alloploid origin and more self incompatible in breeding system.

Physical Mapping of 5S rRNA Genes in Cycas revoluta.

The 5S rRNA gene (5S rDNA) was physically mapped on the somatic chromosomes (2n=22) in Cycas revoluta Thunb. by in situ hybridization using biotin-labeled probes amplified from total genomic DNA. The 5S rDNA was localized at approximate terminal region of the longest pair of telocentric chromosomes. The site of 5S rDNA were the same as C- or chromomycin A3-band.

Chromosomal Studies of the Freshwater Snail Cleopatra bulimoides Common in Upper Egypt.

Chromosomes were counted in the preparation of gonad tissues from Cleopatra bulimoides collected from different localities around Qena City in Upper Egypt. The diploid chromosome number of this species was determined to be twenty eight (2n=28). The karyotype was made up of four metacentric, eight submetacentric and two telocentric chromosome pairs. Increased levels of polyploidy in the form of tetraploidy, pentaploidy, hexaploidy, heptaploidy and octaploidy were determined only in the specimens which have dark brown bands on their shells of this species. Shell measurements are also described in details. (These results are reported for the first time in Egypt.)

Intra-individual variations of chromosomes and DNA content in meristems of adventitious roots ofOrnithogalum umbellatumL.

SUMMARYThe 92 bulbs from a population of Ornithogalum umbellatum which is stable at 2n = 2x = 18, are characterized by a karyotype containing one pair of large metacentric chromosomes, five pairs of large telocentric chromosomes and three pairs of small submetacentric chromosomes; only, two meristematic root cells of one bulb show aneuploidy (2n = 19 and 2n = 25). Although the mean DNA content measured in metaphase plates of meristematic cells of adventitious roots from a single bulb is highly variable (up to 50% difference); in the two cases where aneuploidy was encountered very little or no increase in DNA content was observed.

Cytogenetics and Biology of the Intermediate Host of Human Bilharziasis, Bulinus truncatus Common in Upper Egypt.

Species of the qenus Bulinus occur as a polyploid series which is of interest because of the rarity of polyploidy in the animal kingdom and because it appears that there is some kind of relationship between polyploidy and the ability of this genus to transmit schistosomiasis, a parasitic disease of a major public health importance in most developing coutries. Chromosome analyses were performed in preparations of gonads, gills and embryos, from a hunded specimens of Bulinus truncatus which were collected from different localities around Qena City. The diploid chromosome number was determined to be seventy two (2n=72). The karyotype was made up of seventeen metacentric, thirteen submetacentric, three subtelocentric and three telocentric chromosome pairs. Considering previously reported cytogenetic data in the genus Bulinus, the present specimene appear to represent a tetraploid form and this is the first report in which detailed karyotype for Bulinus truncatus is presented. Habitat, morphological characters and shell measurements for this species are also described in detail in this paper.

Cytogenetics of Ditelotetrasomic for Short Arm of Chromosome 3 of Barley (Hordeum vulgare L.).

Ditelotetrasomic is a plant with a pair of extra homologous telocentric chromosomes in addition to the normal chromosome complement. Ditelotetrasomic 3S in barley is a plant with 2n=14+2 telocentric chromosome 3S. Comparing with their related telotrisomic 3S (2n=14+1 telo 3S) and disomic sibs (2n=14), ditelotetrasomic 3S did not show much qualitative difference in plant morphology; however, quantitative differences were observed in plant morphology: the ditelotetrasomic 3S plants were weaker, slower growing, with fewer tillers and much shorter. Meiotic chromosome behavior was studied from diakinesis through microspore quartet stage. At diakinesis and metaphase I., chromosome configuration were observed with 6II+1IV, 7II, +1 teloII, 6II+1III+l teloI, and 7II+2 teolI. Most of the sporocytes at anaphase and telophase in the first and second meiotic division showed quite normal chromosome behavior. Microspore quartet stage showed mostly normal with some micronuclei. Certain degrees of instability had been observed in the progenies of ditelotetrasomic 3S. The details were discussed.

Karyotypes ofCerastoderma edule, Venerupis pullastraandVenerupis rhomboides(Bivalvia, Veneroida)

The chromosomes of three commercially important species of veneroid bivalves were studied: Cerastoderma edule (Cardiidae), Venerupis pullastra and Venerupis rhomboides (Veneridae, Tapetinae) using conventional Giemsa staining and morphometric measurements. C. edule showed a diploid chromosome number of 2n=38 and a variable occurrence of supernumerary chromosomes. Its karyotype consists of 12 submetacentric, 4 subtelocentric and 3 telocentric chromosome pairs. The supernumerary chromosomes were easily distinguished by their reduced differentiated size and by their intra and inter-individual variability. C. edule is the first bivalve species where supernumerary chromosomes have been observed. V. ullustra had 2n = 38 with a karyotype including 3 metacentric, 8 submetacentric and 8 subtelocentric chromosome pairs. V. rhomboides had 2n = 38 with a karyotype including 4 metacentric, 8 submetacentric, 4 subtelocentric and 3 telocentric chromosome pairs. Cytotaxonomic relationships are proposed within Tapetinae from comparative analysis of karyotypes of two species studied here and three other species of the same subfamily previously studied.

Cytogenetics of ditelotetrasomics for short arms of four chromosomes of barley (Hordeum vulgare L.)

Plants with a pair of extra homologous telocentric chromosomes in addition to the normal chromosome complement are called ditelotetrasomics. Six types of ditelotetrasomics of barley have been obtained. Four types obtained in the selfed progenies of telotrisomics (Triplo 2S, Triplo 5S, Triplo 6S, and Triplo 7S) are reported in this paper. The ditelotetra 2S showed a stronger expression of the diagnostic characteristics of Triplo 2S. It was weak and small, with narrow, short, dark-green leaves, and was almost completely pollen and seed sterile. However, three other ditelotetrasomics (ditelotetra 5S, 6S, and 7S) did not show specific diagnostic characteristics and were similar to normal diploid plants, with the exception of ditelotetrasomic 5S, which showed some effects. At meiotic diakinesis and metaphase I, these ditelotetrasomic plants showed chromosome configurations of 6II+1IV, 7II+1 teloII, 6II+1III+1teloI, or 7II+2 teloI. Most of the sporocytes at anaphase and telophase in the first and second meiotic divisions showed almost normal chromosome behavior. Quartets were mostly normal with no micronuclei. Approximately 30% of the selfed progenies of these three ditelotetrasomics were ditelotetrasomics and almost 50% were telotrisomics, indicating a high percentage of male and female transmission of the extra telocentric chromosomes.

Cytogenetics of Australian scorpions. II. Chromosome polymorphism in species of Urodacus (family Scorpionidae)

The cytogenetic features of six species of scorpion from the Australian genus Urodacus (family Scorpionidae) were examined. Australian scorpionids possess monocentric chromosomes and male meiosis is achiasmate. Chromosome numbers are generally high and in some species extremely variable. Chromosome variation in one species, U. manicatus, was found to be due to fusion – fission polymorphism and variation in the number of small telocentric chromosome pairs. Additionally two populations exhibited extensive inversion heterozygosity. Available evidence suggests that female meiosis may also be achiasmate. The extensive numerical and structural heterozygosity found in U. manicatus may be related to the achiasmate meiosis, which allows regular pairing and disjunction of the multiple chromosome associations.Key words: achiasmate meiosis, chromosome polymorphism, structural heterozygosity, Robertsonian fusions.

Karyotype Structure and Evolution in Cyclamen L. subgen. Psilanthum Schwz.(Primulaceae)

Summary The present contribution deals with karyotypic differentiation of the 7 morphologically or chromosomally distinguishable taxonomic units in Cyclamen subgen. Psilanthum , namely C. balearicum (2n = 20, 2n = 20 + B), C. repandum subsp. repandum (2n = 20), C. repandum subsp. peloponnesiacum forma peloponnesiacum (2n = 20), C. repandum subsp. peloponnesiacum forma vividum (2n = 20), C. repandum subsp. rhodense (2n = 20), and 2 chromosomal races of C. creticum (2n = 20, 2n = 22). In contradistinction to a hypothesis forwarded by L epper (1964, 1975), karyotypes with 2n=22 in C. creticum and 2n=20 in the other species show a Robertsonian relationship. I.e., 2 telocentric chromosome pairs in C. creticum (2n = 22) are replaced by 1 metacentric pair in the other species. In C. creticum with 2n = 20, the analyzed karyotype is neither directly comparable with the other 2n = 20 karyotypes, nor does it show a simple relationship to the 2n = 22 karyotype in C. creticum . On the other hand, the arm ratios of several chromosomes, especially NOR-chromosomes, discriminate C. creticum (2n = 20 and 2n = 22) from all other taxa in Cyclamen subgen. Psilanthum. C. creticum (2n = 20) is not identical with C. repandum subsp. rhodense (syn. C. rhodium ) as suggested by L epper (1975).

Systematics and Evolution of Western North American Frogs Allied to Rana Aurora and Rana Boylii: Karyological Evidence

C-banded karotypes of five species of frogs endemic to western North America were analyzed to investigate the use of such chromosomal data in determining their systematic interrelationships. Morphologically, three of the species (Rana aurora, R. cascadae and R. pretiosa) may be considered generalized brown while the other two species (R. boylii and R. muscosa) are morphologically divergent and may be termed stream frogs. The peculiar karyo- type of R. muscosa, with its three pairs of telocentric chromosomes, can be derived from that of R. boylii by postulating a series of chromosomal inversions. Based on karyotypic character anal- ysis, R. boylii and R. muscosa constitute a pair of sister taxa that appears to have arisen from within the western Rana. The chromosomal evidence, while concordant with morphological considerations, conflicts with various systematic hypotheses that have been proposed concern- ing these frogs based on immunological distance studies and reanalyses. (Anura; Ranidae; Rana; systematics; evolutionary relationships; chromosomes; C-bands; western North America.) Five species of frogs, genus Rana, are en- demic to the far western United States and Canada. The relationships of these species-R. aurora, R. boylii, R. cascadae, R. pretiosa and R. muscosa-that constitute the R. boylii group (sensu Case, 1978a) have been the subject of repeated analyses by various means, including study of mor- phology, comparative biochemistry and karyology (Boulenger, 1920; Zweifel, 1955;

Karyology of the Indo-Pacific Parioglossus raoi (Herre) (Teleosstei : Gobioidei) from Fiji

The diploid number of chromosomes from gills, spleen and gonads of Fijian specimens of P. raoi was 46, 23 bivalents being observed during the meiotic division in spermatocytes. The karyotype comprised 23 pairs of telocentric chromosomes, giving an arm number of 46. There was no evidence for morphologically identifiable sex chromosomes. Comparisons with other gobioids indicate that the karyotype of P. raoi is superficially similar to those of a number of taxonomically diverse members of the suborder and bears no special resemblance to species from a similar ecotope.

New Chromosome Counts in the Palmae

Summary. The chromosome counts for nine palm species are given. They include 2n = 34 for Sommieria afinis which is the first record of that number in the tribe Arecoideae. The taxon contains two pairs of telocentric chromosomes suggesting that it may differ from 2n = 32 plants by a Robertsonian fission.

Chromosomes in Three Species of Fishes,Aplocheilus Panchax(Cyprinodontidae),Lates Calcerifer(Percidae) andGadusia Chapra(Clupeidae)

SUMMARYSomatic chromosomes from the kidneys of both sexes of Aplocheilus panchax (Cyprinodontidae), of male Lates calcerifer (Percidae) and germinal chromosomes from the testes of A. panchax and Gadusia chapra (Clupeidae) are described. In both sexes of A. panchax, the somatic complements consist of 38 chromosomes, measuring between 2.6 and 1.1 μm in male and 2.7 and 1.1 μm in female. The male karyotype comprises 7 pairs of metacentric, 4 pairs of submetacentric, 2 pairs of subtelocentric and 6 pairs of telocentric chromosomes. The female karyotype differs in having one fairly large submetacentric more and small metacentric less than the male karyotype indicating thereby female heterogamety (ZW) in this species. The spermatocytic metaphase I contained 19 apparently homomorphic bivalents. L. calcerifer contains 2n=48 chromosomes which can be aligned into 24 homomorphic pairs comprising 1 pair of metacentric, 3 pairs of submetacentric, 1 pair of subtelocentric and 19 pairs of telocentric chromosomes. The ch...

C-band distribution, DNA content and base composition inAdoxa moschatellina (Adoxaceae), a plant with cold-sensitive chromosome segments

The chromosomes ofAdoxa moschatellina (2n = 36, paleo-4x) contain mostly terminal, occasionally intercalary, negatively heteropycnotic cold-induced regions which correspond to all major C-bands including the satellites, as revealed by sequential analysis. Positively C-stained are also centromeres, the dotlike arms of the 7 telocentric chromosome pairs, and some very narrow intercalary bands; their cold-sensitivity is hardly traceable. There exists a fraction of condensed interphase chromatin, at least after chilling, which is virtually not C-banded (possibly condensed euchromatin).

Biochemical detection of alien DNA incorporated into wheat by chromosome engineering

Wheat lines carrying homologous pairs of complete or telocentric rye chromosomes have been used to investigate the detection of rye chromosomes or chromosome fragments in a wheat genetic background, by nucleic acid hybridisation. Three different radioactive rye probes were used: (1) the most highly repeated DNA sequences made radioactive in vitro by “nick translation”, (2) the whole complement of repeated sequences radioactively labelled in vivo and (3) 25s and 18s ribosomal RNAs radioactively labelled in vivo. Radioactive highly repeated sequence DNA was hybridised to unlabelled DNAs from wheat-rye chromosome addition lines immobilised on nitrocellulose filters. Rye-specific highly repeated sequences were detected in all the lines, illustrating that rye-specific highly repeated sequences reside on all chromosome arms. The effect of the size of the radioactive probe DNA was investigated by hybridising labelled rye repeated sequences to unlabelled DNAs from wheat-rye chromosome addition lines in solution. Short fragments round 300 nucleotides long detected rye-specific repeated sequences in all the unlabelled DNAs. Longer fragments, greater than 2000 nucleotides, were used to show that some of these rye-specific repeated sequences are in chromosomal regions which lack repeated sequences related to repeated sequences in wheat. The regions are probably considerably longer than 10,000 base pairs. Saturating concentrations of 25s and 18s ribosomal RNAs were hybridised to DNAs from Holdfast wheat-King II rye chromosome addition lines bound to nitrocellulose filters. The results showed that chromosome 1R of King II possesses the major cluster of ribosomal RNA genes of rye. However with DNAs from Chinese Spring wheat-Imperial rye chromosome addition lines, those with rye chromosome 1R and chromosome 5R had considerably more ribosomal RNA genes than Chinese Spring wheat. Using labelled barley repeated sequences as probe DNA it was shown in wheat-barley DNA mixtures that it was possible to detect 0.05 per cent barley DNA, i.e. 5 parts in 10,000, by incubating the DNAs to C0t 100 at 70°C in 0.12-M phosphate buffer. It is concluded that these sorts of experiments should be of considerable use for detecting the presence of alien chromosome segments in wheat and other plant species.

The G-banding pattern of chromosomes in Ehrlich Lettŕe ascites tumor cells.

The trypsin digestion-Giemsa staining technique was used to produce distinctive banding patterns in chromosomes of Ehrlich Lettŕe ascites tumor cells derived from a frozen culture originally begun from the ELD line. The chromosome numbers most frequently encountered in cells were 44 and 45. Four large marker chromosomes were identified in the karyotype. One of these was a large submetacentric chromosome, the banding pattern of which indicated its probable origin was from a pair of telocentric chromosomes. Using banding patterns and lengths, the chromosomes were classified into four groups--marker, paired, unpaired, and minute chromosomes.