Chromosome banding in amphibia

A cytogenetic study performed on a population of the South American leptodactylid frog Eleutherodactylus maussi revealed multiple sex chromosomes of the X₁X₁X₂X₂/X₁X₂Y (=XXAA/XXA^Y) type. The diploid chromosome number is 2n=36 in all females and 2n=35 in most males. The multiple sex chromosomes originated by a centric fusion between the original Y chromosome and a large autosome. In male meiosis the X₁X₂Y (=XXA^Y) multiple sex chromosomes form a classical trivalent configuration. E. maussi is the first species discovered in the class Amphibia that is distinguished by a system of multiple sex chromosomes. Only one single male was found in the population with 2n=36 chromosomes and lacking the Y-autosomal fusion. This karyotype (XYAA) is interpreted as the ancestral condition, preceding the occurrence of the Y-autosome fusion.by H.C. Macgregor     

A comparison of male and female recombination frequency in wheat using RFLP maps of homoeologous group 6 and 7 chromosomes

A novel approach was used to compare male and female recombination rates in wheat. Doubled haploid lines were developed from an F₁ using two distinct approaches: the anther-culture technique and the Hordeum bulbosum system, from which sets of lines were developed from male and female meioses, respectively. The genotype of the lines was established at RFLP and isozyme markers polymorphic on chromosomes of homoeologous groups 6 and 7, and male and female linkage maps were calculated using this information. The markers in one segment of chromosome 6B exhibited disturbed segregation frequencies in the anther-culture population. The male and female maps differed significantly in recombination frequency between some markers on two chromosomes, and these were consistent in direction within chromosomes and inconsistent in direction between chromosomes. In two of the four chromosomes studied the male map was much longer than the female map. These results suggest that significant differences may exist in male and female recombination frequencies in bread wheat which are specific to certain chromosomal segments but are inconsistent in direction between chromosomes. Other factors, such as environmental influences, may also be important in creating differences.     

Determination of sex chromosomal constitution and chromosomal origin of drumsticks,drumstick-like structures,and other nuclear bodies in human blood cells at interphase by fluorescence in situ hybridization

The sex chromosomal constitution has been determined in various types of human leukocytes at interphase by use of fluorescence in situ hybridization with X- and/or Y-specific DNA probes. It is found that during aging and differentiation of myelocytes into polymorphs there is no significant change in the relative frequency of various types of male and female cells with a specific type of sex chromosomal constitution. Nonrandom variability of the relative proximity between the X chromosomes within the nuclei is also observed in female cells. Moreover, we are the first to determine that sex-specific drumsticks and sessile nodules in female polymorphs originate from the X chromosomes and that non-sex-specific drumstick-like bodies in male polymorphs are of Y chromosomal origin.     

Biotechnological production of unnatural L-amino acids from D,L-5-monosubstituted hydantions. II. L-α- and L-β-naphthylalanine

Summary Resting cells ofArthrobacter sp. (DSM 3745) with the ability to form L-tryptophan from D,L-5-(3-indolylmethy)hydantoin were used for the bioconversion of D,L-5-- and D,L-5--naphthylmethylhydantoin (D,L-5-- and D,L-5--NMH) to the corresponding L-amino acids. Under the optimal reaction conditions of pH 9.7 and 40°C specific productivities of 0.2 (-naphtylalanine) and 0.6 (-naphtylalanine) mM amino acid x g cell dry mass^–1 x h^–1 were obtained in a 0.1 M Na₂CO₃/NaHCO₃-buffer in a strirred bioreactor.     

The behavior of allocyclic chromosomes in Bloom's syndrome

The behavior of individual allocyclic chromosomes has been analyzed in lymphocytes of a sister and a brother with Bloom's syndrome. Of 4,633 diploid cells, 115 showed allocyclic chromosomes, and 74 of these had 44, 45 or 46 normal metaphase chromosomes accompanied by one or two allocyclic chromosomes. Of 56 tetraploid cells, 9 contained such chromosomes. The allocyclic chromosomes appeared pulverized or extended corresponding to S or G₂ PCC. We have proposed the hypothesis that individual allocyclic chromosomes do not, as a rule, come from micronuclei, as has often been assumed, but have been left behind in their cycle. This would be caused by a mutation or deletion of a hypothetical coiling center situated near the centromere of each chromosome arm. The following observations agree with our explanation but less well or not at all with the idea of micronuclei: (1) In only 9.6% of the cells does the allocyclic chromosome lie at the edge of the metaphase plate. (2) In 24 cells a part of a chromosome is pulverized while the rest is in metaphase. (3) Both a pulverized and an extended chromosome were present in the same cell. (4) A pulverized acrocentric is often nose-to-nose with a normal D or G chromosome. (5) No allocyclic chromosomes corresponding to G₁ PCC have been found in our material. (6) When a ring is replaced by an allocyclic chromosome, it is usually a member of a 46-chromosome complement. Furthermore, the occurrence of allocyclic chromosomes is correlated with that of other chromosome anomalies which do not follow a Poisson distribution. Allocyclic chromosomes are also more frequent (16%) in tetraploid than in diploid cells (2%).     

Solution conformations of proline rings in proteins studied by NMR spectroscopy

Summary Three different conformations of proline rings in a protein in solution, Up, Down and Twist, have been distinguished, and stereospecific assignments of the pyrrolidine -, - and -hydrogens have been made on the basis of ¹H-¹H vicinal coupling constant patterns and intraresidue NOEs. For all three conformations, interhydrogen distances in the pairs -³, ³-³, ²-², ²-², and ³-³ (2.3 Å) are shorter than those in the pairs -², ²-³, ³-², ²-³, and ³-² (2.7–3.0 Å), resulting in stronger NOESY cross peaks. For the Up conformation, the ³-² and ²-³ spin-spin coupling constants are small (<3 Hz), and weak cross peaks are obtained in a short-mixing-time (10 ms) TOCSY spectrum; all other vicinal coupling constants are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. For the Down form, the -², ²-³, and ³-² vicinal coupling constants are small, leading to weak TOCSY cross peaks; all other couplings again are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. In the case of a Twist conformation, dynamically averaged coupling constants are anticipated. The procedure has been applied to bovine pancreatic trypsin inhibitor and Cucurbita maxima trypsin inhibitor-V, and ring conformations of all prolines in the two proteins have been determined.     

Karyotypes and sex determination in two species of laelapid mites (Acari: Gamasida)

The chromosome number and morphology of two species of the family Laelapidae have been determined: Hypoaspis aculeifer Canestrini, 1887 has 9() and 18() chromosomes and Cosmolaelaps miles Berlese, 1914 7() and 14(). Both karyotypes have monokinetic chromosomes and show obvious similarity. The longest chromosome of both species consists of a normal and a heterochromatic arm. The two laelapid mites prove to be arrhenotokous, as unfertilized females lay eggs from which only males arise. A theory has been postulated that within the Gamasida an evolutionary line towards arrhenotoky is present.Arguments supporting an independent evolution of sex determining system in the two acarine taxa Actinotrichida and Anactinotrichida are discussed.     

Visible and “cryptic” segregation of parental chromosomes in embryonic stem hybrid cells

Chromosome segregation of the parental chromosomes was studied in 20 interspecific hybrid clones obtained by fusion of Mus musculus embryonic stem cells with Mus caroli splenocytes. FISH analysis with labeled species specific probes and microsatellite markers was used for identification of the parental chromosomes. Cytogenetic analysis has shown significant intra- and interclonal variability in chromosome numbers and ratios of the parental chromosomes in the hybrid cells: six clones contained all M. caroli chromosomes, nine clones showed moderate segregation of M. caroli chromosomes (from 1 to 7), and five clones showed extensive loss of M. caroli chromosomes (from 12 to complete loss of all M. caroli autosomes). Both methods demonstrated cryptic segregation of the somatic partner chromosomes. For instance, five clones with near-tetraploid chromosome sets contained only few M. caroli chromosomes (from 1 to 8). The data obtained suggest that the tetraploid chromosome set per se is not a sufficient criterion for conclusion on the absence of chromosome loss in the hybrid cells. Note that cryptic chromosome segregation occurred at a high frequency in the examined hybrid clones. Thus, cryptic segregation should be borne in mind for assessing pluripotency and genome reprogramming of embryonic stem hybrid cells.__________Translated from Ontogenez, Vol. 36, No. 2, 2005, pp. 151–158.Original Russian Text Copyright © 2005 by Pristyazhnyuk, Temirova, Menzorov, Kruglova, Matveeva, Serov.     

Identification of a complete set of isogenic wheat/rye D-genome substitution lines by means of Giemsa C-banding

Summary A complete set of isogenic wheat/rye D-genome substitutions were produced by crossing an inbred line of spring rye Secale cereale L. cv. Prolific to a tetraploid wheat, the A-and B-genomes of which had previously been extracted from hexaploid wheat, Triticum aestivum L. em Thell. cv. Thatcher. After chromosome doubling, the derived hexaploid triticale (x Triticosecale Wittmack) was backcrossed to 6x Thatcher and selection for wheat/rye substitution lines was carried out in BCF₃ to BCF₆ families by using Giemsa C-banding. Five fertile disomic wheat/rye D-genome substitution lines were obtained and their chromosomal constitution was determined to be 1D/1R, 2D/2R, 7D/4R, 6D/6R, 7D/7R. The two remaining 3R and 5R substitutions are at the moment in a monosomic condition. Another 1D/7R substitution was detected but this plant was very weak and sterile, indicating that only substitutions between homoeologous chromosomes result in fertile, vigorous plants. Furthermore, many rye telocentrics as well as rye-rye and rye-wheat translocations were selected. Since all lines selected in this program share the same genetic background of Thatcher wheat, genetic heterogeneity is excluded. The material is very useful, therefore, for analyzing the effects of different rye chromosomes or chromosome segments in an otherwise homozygous background.Contribution No. 797     

Observations on the fine structure of the cercaria of Notocotylus attenuatus and formation of the cyst wall of the metacercaria

Summary The dorsal tegument of the mature cercaria of Notocotylus attenuatus is a syncytial, cytoplasmic layer, containing two types of secretory granule which are identifiable ultrastructurally. The type 1 secretory bodies are electron lucid, whereas most type 2 granules have a banded appearance. The ventral tegument contains granules which are secreted from the type 3 cells; the type 3 granules are membrane bound, electron dense, and consist of both an amorphous and a finely striated zone. The type 4 cells mainly contain cigar-shaped granules consisting of an amorphous core surrounded by concentric striations. The granules exhibit structural variability in shape and content. The type 4 cells undergo a cellular migration to the tegument during encystment. The structure of the posterior-lateral glands and mode of secretion of the granules are described. Possible functions of microtubules are discussed for each cell type. Details of some secretory processes involved in the formation of the hemispherical cyst wall are described. The layers of the cyst wall may be related to the granular contents of the various parenchymal cells of the cercaria. The tegument of the metacercaria originates primarily from the cytoplasm of the type 1, type 2, type 3 and type 4 cells.     

A further survey of the chromosomes in the Japanese

Summary In the present study, information was obtained on the chromosomes in somatic cells derived from various organs of 135 foetuses, 1 to 7 months of age, and in germ-cells of two adult males.The chromosome counts were carried out on 2633 cells in primary cultures, on 3933 cells in subcultures and on 30 cells from directly squashed organs.In this total of 6596 cells studied, 6344 cells, or 96.18 per cent contained the normal complement of 46 chromosomes, regardless of sex, age, organ or experimental procedure. No evidence was detected for a chromosomal polymorphism in either somatic or germ-cells.In primary cultures from 127 foetuses two chromosomally abnormal individuals have been found. One contained in the majority of cells studied an obnormal complement of 45 chromosomes, a new, unusual karyotype of XY sex-chromosome constitution. The other showed cells with chromosome aberrations involving chromosome breaks, translocations and fragments in relatively high frequency.The sex-ratio (100 × N/N), observed on the basis of chromosomal diagnosis, was 96.67.Contribution No. 534 from the Zoological Institute, Faculty of Science, Hokkaido University, Sapporo, Japan.Supported by a grant from the Damon Runyon Memorial Fund for Cancer Research to S. Makino (DRG-563 A).     

Synaptonemal Complex Analysis in Oocytes and Spermatocytes of Threespine Stickleback Gasterosteus Aculeatus (Teleostei, Gasterosteidae)

A surface-spreading synaptonemal complex (SC) technique was employed to analyze spermatocytes and oocytes of stickleback, Gasterosteus aculeatus, in order to visualize the process of chromosome synapsis. The mean SC length was 150±18m in three males and 143±12m in one female analyzed. A representative SC karyotype with 21bivalents was also presented. Each SC had lateral elements of equal length. No bivalent displaying the atypical synaptic behaviour which is often associated with heteromorphic sex chromosomes was observed neither in males nor in the female analyzed.     

Silver staining the chromosome scaffold

Cytological silver-staining procedures reveal the presence of a core running along the chromatid axes of isolated HeLa mitotic chromosomes. In this communication we examine the relationship between this core and the nonhistone chromosome scaffolding, isolated and characterized in previous publications from this laboratory. When chromosomes on coverslips were subjected to the steps used for scaffold isolation in vitro and subsequently stained with silver, the characteristic core staining was unaffected. Control experiments suggested that the core does not contain large amounts of DNA. When scaffolds were isolated in vitro, centrifuged onto electron microscope grids, and stained with silver, they were found to stain selectively under conditions where specific core staining was observed in intact chromosomes. These results suggest that the nonhistone scaffolding is the principal target of the silver stain in chromosomes.     

Analysis of chromatin-associated fiber arrays

The distribution of constitutive heterochromatin has been investigated in four chromosomal races of the grasshopper Caledia captiva (2n= 23 /24 ) by the C-banding technique. Each of the four races was found to have a distinctive banding pattern which is associated with the inter-racial differences in chromosomal rearrangements. — The Ancestral race has a telocentric chromosome complement with large procentric C-bands which are structurally double on six pairs of chromosomes. The centromeres are unstained. — The General Purpose race has a C-banding pattern very similar to that seen in other Acridine grasshoppers with the majority of its chromosomes showing a centromeric localisation of the bands. — The two southern races, which show a complex polymorphism for presumed pericentric inversions on all twelve chromosomes, also show an unusually high level of interstitial and terminal C-bands. The different locations and numbers of these bands allow unambiguous identification of all the chromosome pairs within the complement. — In two cases, there is good evidence to indicate that a C-band redistribution between acrocentric and metacentric chromosomes has occurred by pericentric inversion. Furthermore, C-band variation on the long arm of the metacentric X-chromosome indicates the presence of a large paracentric inversion. This double inversion system has involved over 95% of the X-chromosome. — The interstitial and terminal C-bands probably have not resulted from heterochromatin movement within the complement but, more likely, have arisen by saltatory duplication of pre-existing sequences on the chromosome. — A new nomenclature system for banded chromosomes is proposed which allows most kinds of chromosomal restructuring and rearrangement to be adequately enumerated.     

Relationship between measured chromosome distribution parameters and Ag-staining of the nucleolus organizer regions

Summary Trypsin-banded metaphase plates provided by one whole blood culture of a normal adult female were analyzed as to the chromosome distribution by measuring: (1) distances between centromeres; (2) angles formed between a centromere, the gravity center of the metaphase plane, and a second centromere; and (3) the measured tendency to associate, as defined by Galperin (1969b). These data are correlated with Ag-NOR staining findings obtained from 72 cells from another culture of the same individual. In these cells, the chromosome pairs are identified using a simultaneous Ag-NOR staining and acridine orange banding technique. The silver precipitation is also correlated with the scored satellite associations in these cells. The results show a correlation between all concerned parameters, indicating that the nucleolar function of the human acrocentric chromosomes, as demonstrated by the silver precipitation technique, is probably one of the major determinants of the proximity of these chromosomes. There is a pronounced correlation of the Ag-NOR findings with those measured parameters which describe best the preferential small distances between chromosomes (angle analysis and tendency to associated data). Moreover, the association patterns of the acrocentrics with small amounts of NOR provide some evidence for the interference of other determinants cogoverning the position of the human D-and G-group chromosomes.To whom offprint requests should be sent     

Purification and characterization of aspartate aminotransferase from developing embryos of the camel tick Hyalomma dromedarii

Aspartate transaminase (AST) activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of AST to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). AST II with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of AST II was 52KDa for the native enzyme, composed of one subunit of 50KDa. AST II had a Km value of 0.67mM for -ketoglutarate and 15.1mM for aspartate. AST II had a pH optimum of 7.5 with heat stability up to 50°C for 15min. The enzyme was activated by MnCl₂, and inhibited by CaCl₂, MgCl₂, NiCl₂, and ZnCl₂.     

Sex determination in Sarotherodon (tilapia)

Summary The simplest possible model of the sex determination process adding autosomal influence to a minimal number of sex chromosomes was developed to explain matings of Tilapia (Sarotherodon) species. Eighteen different genotypes, each having two autosomes (AA, Aa, or aa) and two sex chromosomes (WX, WY, WW, XY, XX or YY) involved in sex determination, are predicted by the theory. Their sex (10 males and 8 females) were determined using a series of directed graphs, showing the relative strength of the chromosome pairs, developed on the basis of Chen's sex ratio results (Chen 1969). This theoretical model predicts eight different sex ratios (01, 13, 35, 11, 97, 53, 31, 10 ); three of them are not predicted by the WXYZ theory. The greatest part of these sex ratios have been obtained experimentally in extensive series of crosses between related species of Tilapia and their hybrids, carried out by several authors. The theory succeeds in explaining all of Chen's results, including those ratios 53 and 01 seen in certain crosses but not predicted by the WXYZ theory. The importance of the autosomes is seen in comparisons of the genotype pairs (AaWY, aaWY), (AaXY, aaXY) and (AAWW, AaWW) in which the first genotype in each case is male while the second is female as proven by the sex ratio results. The members of the pair differ only in the substitution of one autosome for the other. To test the theory, experiments consisting of hormonal sex reversion and a series of crosses are proposed. Finally, theoretical and practical implications of the theory are discussed.     

The addition of Dasypyrum villosum (L.) Candargy chromosomes to durum wheat (Triticum durum Desf.)

Summary Six monosomic addition lines were produced in which different Dasypyrum villosum (L.) Candargy chromosomes were added to the chromosome complement of Triticum durum Desf. cv. Creso. Each added alien chromosome was found to have a specific effect on plant morphology and fertility. Transmission rate varied widely (from 7.5 to 27.7%) among the six univalent chromosomes. Different monotelosomic addition plants derived by a relatively high frequency of chromosome misdivision were isolated. The addition lines should be useful for studying Dasypyrum chromosome homoeology and the introduction of alien variation into durum and common wheats.Research supported by a grant from the Italian Research Council for Finalized Project IPRA. Sub-project Plant Breeding, Paper No. 1095     

Unequal X Chromosomes in Bradysia Hygida (Diptera:Sciaridae) Females: Karyotype Assembly and Morphometric Analysis

The mitotic chromosomes of Bradysia hygida(Diptera:Sciaridae) neuroblast cells are described together with their morphometric data. Giemsa-stained neuroblast chromosomes from female and male larvae confirm the chromosome number of this species, 2n=8 (XX) and 2n=7 (XO), respectively. The karyotype assembly reveals two metacentric autosomic pairs, the A and B chromosome; a subtelocentric, the C chromosome, the smallest one; and a sexual unequal metacentric pair, X chromosome, in female karyotype and a one sexual metacentric X chromosome in male. The implications of the unequal X chromosome pair are discussed.     

Chromosomal C-band variation inAllium schœnoprasum (Liliaceae) in eastern North America

Variation in C-banding was studied in seven populations ofAllium schnoprasum from eastern N. America, including populations referable to var.sibiricum, var.laurentianum, and ± intermediate. 23 bands were recognized on five pairs of chromosomes, and were treated as 23 loci. No banding site was monomorphic throughout the plants studied. The level of polymorphism per population was >60%, and the average heterozygosity values varied from 0.21 to 0.27. The various banding patterns of chromosomes were shown to depend on the random combination of individual bands. Nei's genetic distances between populations varied from 0 to 0.070 (mean: 0.033). The matrix of genetic distances was analysed by non-metric multidimensional scaling, and the results showed a significant relationship between longitude and population scores on the ordination. The chromosomal data did not clearly discriminate between the two native varieties ofA. schnoprasum, but were interpreted as a longitudinal cline. It is suggested that studies of C-banding variation in vascular plants should focus on individual banding sites, rather than on whole chromosome banding patterns.