Chromosomal organization of Drosophila tumours

In otu mutants of Drosophila melanogaster ovarian tumours develop because of the high mitotic activity of the mutant cystocytes; the latter are normally endopolyploid. In certain alleles of otu, however, a varying proportion of the mutant ovarian cystocytes undergo polyteny. Mutant cystocytes with polytene chromosomes are termed pseudonurse cells (PNC). Polytene chromosome morphology and banding patterns in PNC of otu ¹/otu³ flies were cytologically analysed. Extensive variability was noted in the quality of the banding pattern of the PNC chromosomes which ranged from highly condensed (condensed PNC chromosomes) to those with a banding pattern (banded PNC chromosomes) similar to that in larval salivary gland cells (SGC). Both the condensed and banded PNC chromosomes frequently enter into a diffuse state characterised by weakened synapsis of the polytene chromatids and alterations in their banding pattern (diffuse PNC chromosomes). Analysis of DNA synthesis patterns in the various morphological forms of PNC polytene chromosomes by ³H-thymidine autoradiography revealed a basic similarity to the pattern seen in polytene nuclei of larval SGC. Independently replicating sites, however, could be unambiguously identified only in banded PNC chromosomes. Comparison of late replicating sites in such PNC chromosomes with those of larval SGC showed a remarkable similarity in the two cell types. These results suggest a close correlation between the polytene chromosome banding pattern and its replicative organization.     

The karyotype of the golden monkey (Rhinopithecus r. roxellanae)

In this paper, the karyotype and G-banding pattern of the chromosomes of cultured peripheral blood lymphocytes in R. r. roxellanae were investigated. The chromosome number of this species is 44 in both sexes. In R. r. roxellanae, as in other monkeys, sex is determined by specific sex chromosomes, i.e. the male is XY and the female is XX. The 21 pairs of autosomes consist of 7 pairs of metacentric chromoomes, 13 pairs of submetacentric chromosomes and one acrocentric pair. Chromosome measurements were made from highly enlarged photographic prints. They included the relative length, arm ratio and centromere index of each chromosome. Both chromosomal and chromatid aberrations were observed. They were 0·67 and 2%, respectively. Finally, G-banding pattern analysis of chromosomes of R. r. roxellanae were carried out. The results show that each homologous pair has its own special banding pattern, so that each of them is easily recognizable. Idiograms of chromosome complements with the Giemsa banding pattern are constructed.     

Diversified chromosomal distribution of tandemly repeated sequences revealed evolutionary trends in Secale (Poaceae)

Genomic in situ hybridization (GISH) with Secale cereale cv. ‘Jingzhou rye’ DNA as a probe to chromosomes of hexaploid triticale line Fenzhi-1 revealed that not only were all chromosomes of rye strongly hybridized along the entire chromosome length, but there were also stronger signals in terminal or subtelomeric regions. This pattern of hybridization signals is referred to as GISH banding. After GISH banding, sequential fluorescene in situ hybridizaion (FISH) with tandem repeated sequence pSc200 and pSc250 as probes showed that the chromosomal distribution of pSc200 is highly coincident with the GISH banding pattern, suggesting that GISH banding revealed chromosomal distribution of pSc200 in rye. In addition, FISH using pSc200 and pSc250 as probes to chromosomes of 11 species of the genus Secale and two artificial amphiploids (Triticum aestivum-S. strictum subsp. africanum amphiploid and Aegilops tauschii-S. silvestre amphiploid) showed that (1) the chromosomal distribution of pSc200 and pSc250 differed greatly in Secale species, and the trend towards an increase in pSc200 and pSc250 binding sites from wild species to cultivated rye suggested that pSc200 and pSc250 sequences gradually accumulated during Secale evolution; (2) the chromosomal distribution of pSc200 and pSc250 presented polymorphism on homologous chromosomes, suggesting that the same species has two heterogeneous homologous chromosomes; (3) the intensity and number of hybridization signals varied differently on chromosomes between pSc200 and pSc250, suggesting that each repetitive family evolved independently.     

Quinacrine fluorescence staining of chromosomes and its relationship to DNA base composition

The quinacrine banding patterns of chromosomes of Dipodomys ordii and Mus musculus are described. Satellite and mainband DNA fractions from D. ordii and M. musculus were tested for their ability to quench or enhance the fluorescence of quinacrine dihydrochloride in solution. The relationship between the base composition of a particular DNA fraction, its effect on the fluorescence of quinacrine in solution and its location in chromosomes relative to the quinacrine banding pattern is discussed.     

C banding in polytene chromosomes of Simulium ornatipes and S. melatum (Diptera: Simuliidae)

Polytene and mitotic chromosomes of Simulium ornatipes and S. melatum were subjected to C banding procedures. In both species polytene chromosomes consistently show C banding of centromere regions, telomeres, nucleolar organiser and, unexpectedly, numerous interstitial sites. The interstitial C banding sites correspond to morphologically single polytene bands. Their response is graded and independent of band size. Interstitial C bands in S. ornatipes are scattered throughout the complement, whereas in S. melatum they are clustered. Supernumerary heterochromatic segments in S. ornatipes also exhibit strong C banding and inverted segments can differ from standard in C banding pattern. — Mitotic chromosomes of both species show a single centric C band with indications of two weak interstitial bands in S. ornatipes, suggesting that many C band regions, detectable in polytene chromosomes, are not resolved by present techniques in mitotic chromosomes. — Contrary to current opinion that C banding is diagnostic for constitutive heterochromatin, the interstitial C band sites of polytene chromosomes are regarded as euchromatic. Conversely, the heterochromatic pericentric regions of S. ornatipes are not C banded. — It appears that polytene chromosomes offer a promising system for the elucidation of C banding mechanisms.     

Further evidence of intraspecific heterochromatin variants in Drosophila melanogaster

The analysis of inter-strain heterochromatin polymorphism in mitotic chromosomes of Drosophila melanogaster was extended to some stocks characterized by chromosomal mutations. In particular, the present investigation aims to compare, in the same cell, the quinacrine banding of two different Y chromosomes of male hybrids derived from crosses using special stocks. A direct comparison of homologous heteromorphic chromosomes in F₁ hybrids provided additional evidence of differences in the fluorescence pattern of the Y chromosome, as well as in the length of the heterochromatin segment of the X chromosome.     

Polytene chromosomes from ovarian pseudonurse cells of the Drosophila melanogaster otu mutant

Certain mutant alleles of the otu locus in Drosophila melanogaster produce abnormal nurse cells in the ovaries. These cells are called pseudonurse cells (PNC), since they generate polytene chromosomes instead of endopolyploid ones and do not normally have an oocyte to nurse. The banding pattern of polytene chromosome 3 from the salivary glands (SG) and from PNCs of homozygous otu ¹ females was compared and a detailed photomap of PNC chromosomes with different degrees of polyteny is presented. The banding pattern was found to be strikingly similiar in the two tissues. The puffing pattern of the PNC chromosomes was also studied and the function of the PNC chromosomes is discussed. No constrictions or breaks were found in the PNC chromosomes which seems to indicate that these sites, which are known to be underreplicated in the SG chromosomes, are equally replicated along with the rest of the chromosomes in the PNC nuclei.     

A new species of Liolaemus related to L. nigroviridis from the Andean highlands of Central Chile (Iguania,Liolaemidae)

The Liolaemus nigroviridis group is a clade of highland lizards endemic to Chile. These species are distributed from northern to central Chile, and currently there are no cases of sympatric distribution. This study describes a new species, Liolaemus uniformis sp. n., from this group, and provides a detailed morphological characterization and mitochondrial phylogeny using cytochrome-b. Liolaemus uniformis was found in sympatry with Liolaemus nigroviridis but noticeably differed in size, scalation, and markedly in the color pattern, without sexual dichromatism. This new species has probably been confused with Liolaemus monticola and Liolaemus bellii, both of which do not belong to the nigroviridis group. The taxonomic issues of this group that remain uncertain are also discussed.     

Chromosome Banding and DNA Methylation Patterns, Chromatin Organisation and Nuclear DNA Content in Zingeria biebersteiniana

Chromosome structure and chromatin organisation of a two-chromosome model cereal Zingeria biebersteiniana (Claus) P. Smirnov were studied: nuclear DNA content was determined by microdensitometric analysis after Feulgen staining; Feulgen absorption at different thresholds of absorbance in interphase nuclei also provided evidence on the organisation of chromatin, allowing quantitative estimation of condensed chromatin within interphasic nucleus. The DNA methylation pattern of Z. biebersteiniana metaphase chromosomes was examined with a specific monoclonal antibody. 5-methyl-cytosine residues are present in several chromosome sites and differences may be present between corresponding regions of homologues. Chromosome banding pattern reveals large bands in the centromeric regions of each chromosome, showing constitutive heterochromatin; by fluorochromes staining pericentromeric blocks are evidenced. After the cold and 9-aminoacridine pre-treatments and after aceto-carmine and aceto-orceine staining, respectively, the metaphase chromosomes were analysed by image analysis system revealing a segmentation of the chromosome body that resembles Giemsa/Reverse banding in animal chromosomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Karyotype and chromosomal banding pattern in Heteropeza pygmaea

The chromosomes of somatic and germ line cells of female embryos produced by paedogenesis were studied. The haploid set in somatic cells consists of one long submetacentric chromosome, one large acrocentric, one medium metacentric and two small acrocentrics. The length vs arm index karyogram makes it possible to distinguish all but the two pairs of small acrocentric chromosomes. — Attempts were made to develope a method for banding pattern visualization. The best result was obtained using trypsin which induced banding in the chromosomes of the somatic cells and occasionally also of the germ line cells. The resulting banding patterns were frequently not identical in members of a chromosome pair. There was also a variation between metaphases within an embryo as well as from different embryos. Some tentative explanations for these results are discussed.     

Differential staining of plant chromosomes with Giemsa

Simple Giemsa staining techniques for revealing banding patterns in somatic chromosomes of plants are described. The value of the methods in the recognition of heterochromatin was demonstrated using five monocotyledonous and two dicotyledonous species. In Trillium grandiflorum the stronger Giemsa stained chromosome segments were shown to be identical with the heterochromatic regions (H-segments) revealed by cold treatment. Preferential staining of H-segments was also observed in chromosomes from three species of Fritillaria and in Scilla sibirica. Under suitable conditions the chromosomes of Vicia faba displayed a characteristic banding pattern and the bands were identified as heterochromatin. The Giemsa techniques proved to be more sensitive than Quinacrine fluorescence in revealing a longitudinal differentiation of the chromosomes of Crepis capillaris, where plants with and without B-chromosomes were examined. Again all chromosome types had their characteristic bands but there was no difference in Giemsa staining properties between the B-chromosomes and those of the standard complement.     

Die Speicheldrüsenchromosomen der StechmückeCulex pipiens L. II. Ergänzungen zur Kartierung

The map of larval salivary gland chromosomes of the mosquitoCulex pipiens L. is amended as follows: The banding pattern is corrected in arm 1L, and completed in 2L. The amendments were verified on isolated entire chromosomes. Discrepancies between the three maps published previously, are ascribed to differences in method of the respective authors. In map collation, only well-spread chromosomes of a similar degree of polyteny should be used. The spatial arrangement of chromosomes in the nucleus is discussed, and indications are given for distinguishing between chromosome ends and accidental breaks.     

Syntheseprozesse an den Riesenchromosomen von Glyptotendipes

At the heterochromatic sections of salivary gland chromosomes in Glyptotendipes barbipes puffs can be induced by temperature shocks and X-rays. There is no measureable RNA- synthesis at these puffs, but small amounts of the typical puff-proteins are produced. It has been proved cytophotometrically that DNA makes the same number of replication steps in the hetero-chromatic and euchromatic regions. The incorporation of ³H-thymidine shows that the heterochromatic parts of the polytene chromsomes start replication at the same time as euchromatic parts. The rate of synthesis in the heterochromatic regions is rather small at the beginning of replication. The relation between DNA-replication and the composition of proteins in salivary gland chromosomes was studied by the autoradiographic method using ¹⁴C-thymidine, ³H-lysine and ³H-arginine. Contrary to ¹⁴C-thymidine the radioactive amino acids are steadily incorporated into the chromosomes without any differences in concentration corresponding to the banding pattern. A more differentiated pattern could only be obtained by long-time incorporation of ³H-lysine. Together with cytophotometric results on DNA and protein-amounts of single, isolated salivary gland chromosomes the hypothesis is discussed that pre-stages of protein are steadily incorporated into the chromosomes but that they only linked with DNA after replication. The characteristics of heterochromatin in Glyptotendipes barbipes in comparison with the heterochromatin of other Chironomus species are discussed under the phylogenetic view-point.     

Dynamic organization of the β-heterochromatin in the Drosophila melanogaster polytene X chromosome

Region 20 of the polytene X chromosome of Drosophila melanogaster was studied in salivary glands (SG) and pseudonurse cells (PNC) of otu mutants. In SG chromosomes the morphology of the region strongly depends on two modifiers of position effect variegation: temperature and amount of heterochromatin. It is banded in XYY males at 25°?C and β-heterochromatic in X0 males at 14°?C, i.e. it shows dynamic transitions. In PNC chromosomes region 20 is not heterochromatic, but demonstrates a clear banding pattern. Some molecular markers of mitotic heterochromatin were localized by means of in situ hybridization on PNC chromosomes: DNA of the gene su(f) in section 20C, the nucleolar organizer and 359-bp satellite in 20F. The 359-bp satellite, which has been considered to be specific for heterochromatin of the mitotic X chromosome, was found at two additional sites on chromosome 3L, proximally to 80C. The right arm of the X chromosome in SG chromosomes was localized in the inversion In(1LR)pn2b: the telomeric HeT-A DNA and AAGAG satellite from the right arm are polytenized, having been relocated from heterochromatin to euchromatin.     

Cytogenetic Mapping of Enzyme Loci on Chromosomes J and U of DROSOPHILA SUBOBSCURA

Enzyme loci located on chromosome J and U were mapped cytologically by means of a Y translocation technique. A linkage map of the two chromosomes was established in a parallel experiment and the recombination frequency in different regions of the chromosomes determined. A comparison of the cytogenetic localization of the enzyme genes in D. subobscura and D. melanogaster indicates that many paracentric inversions must have taken place in the course of divergent evolution. However, no displacements of genes from one element to another due to pericentric inversions, reciprocal translocations or transposing elements can be observed. In spite of the large number of structural rearrangements that have occurred in the phylogeny of the genus Drosophila, gross similarities of banding pattern in homologous regions of the chromosomes of the two species become apparent.     

Increased degradation rates of protein in aging human fibroblasts and in cells treated with an amino acid analog.

Isolated polytene nuclei from Drosophila hydei salivary glands were subjected to various in vitro conditions, and structural and functional alterations were observed. The conditions required to best maintain the structure were different from those needed for maximal RNA synthesis. However, both the structure and function were adequately maintained at a moderate ionic strength. Functionally the RNA synthetic activity of giant chromosomes under these conditions shows a close resemblance to the in vivo situation according to several criteria. Morphologically chromosomes from isolated nuclei show an intact and distinctive banding pattern in squash preparations, but they are much more condensed than chromosomes derived directly from cells. Decreasing the ionic strength reduces the degree of condensation but also diminishes the RNA synthetic activity of the isolated nuclei. Increasing the ionic strength results in maximal endogenous RNA polymerase activity, but considerably alters the chromosomal morphology. The chromosomes from isolated nuclei did not exhibit any template activity with exogenously added RNA polymerase B from Drosophila hydei. The possible implications of these findings are discussed.     

On the Quinacrine fluorescence and Giemsa staining patterns of the chromosomes of Vicia faba

Abstract

A comparison has been made between the Quinacrine fluorescence bands and the bands obtained with a denaturating-reannealing-Giemsa technique in Vicia faba. The results show that some of the bands, particularly on the M and, proximally, on the S chromosomes are visible with both techniques. A complex pattern of bands on the S chromosomes is revealed with the Giemsa technique. Both the similarities and the differences between the banding patterns obtained with the two methods in Vicia faba may indicate various degrees of DNA repetitiousness and other physico-chemical properties in the chromosome segments involved.     

Chromosome banding in the genusPinus

The chromosomes (2n=24) ofPinus densiflora Sieb. et Zucc. andP. thunbergii Parl. collected from several localities were analyzed on their fluorescent banding patterns by sequential staining with the base specifically binding fluorochromes, CMA and DAPI. In both species, the CMA-bands were localized at the proximal and/or interstitial regions of most of the chromosomes. The CMA-banding pattern was constant among the cells in a plant and was specific to respective species with a few variations. After the CMA and DAPI stainings each chromosome was identified individually. The fluorescent banding patterns of the two species were somewhat similar, but were diferent with respect to in some characters.Pinus thunbergii had two pairs of metacentric chromosomes without CMA-band and two pairs of metacentric chromosomes with an additional thin CMA-band at the interstitial region. The 10th and 11th pairs of chromosomes of both species, which showed similarity in interstitial CMA and DAPI banding and chromosome shape, had the proximal CMA-bands inP. densiflora and DAPI-band inP. thunbergii. The interspecific F₁ hybrid between the two species could easily be identified by the fluorescent banding method.