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T Haaf

Publications and source records attributed to T Haaf.

At least 127 records · Page 7Linked to original sources
PubMed1989

Immunocytogenetics. II. Human autoantibodies to synaptonemal complexes.

Synaptonemal complex (SC) autoantibodies are spontaneously produced by patients with various autoimmune diseases. Immunofluorescence staining of pachytene cells localized the antigen to the central element or transverse filaments of the SC but not to the lateral elements. Specific antibody labeling was confined to the SC at synapsis. Cytochemical tests showed that the SC autoantigen is a basic protein possibly bound to DNA. An unusual characteristic of the SC autoantigen is its species specificity. Patients were found whose sera selectively labeled the SCs of other humans, mice, or newts. The combining of anti SC and anti-kinetochore antibodies provides a new immunocytochemical method for the analysis of SC karyotypes. The optimum conditions for preparation of pachytene cells for visualization by indirect immunofluorescence were determined. The nature and functions of the SC antigen, as well as possible applications of SC-specific autoantibodies in cytogenetics and cell biology, are discussed.

Animals↗
PubMed1989

Immunocytogenetics. III. Analysis of trivalent and multivalent configurations in mouse pachytene spermatocytes by human autoantibodies to synaptonemal complexes and kinetochores.

Mice heterozygous for one or more Robertsonian (Rb) translocation chromosomes have been used to analyze synaptonemal complex (SC) configurations and kinetochore arrangements in trivalents and multivalents. Rb heterozygosity without arm homologies leads to the formation of heteromorphic trivalents in meiosis I; alternating homology of the chromosome arms produces ringlike or chainlike multivalents. Immunofluorescence double-labeling with human antibodies to SCs and kinetochores was performed on surface-spread pachytene spermatocytes. Both Rb bivalents and Rb trivalents clearly showed that metacentrics possess only one centromere. In heteromorphic trivalent SCs, the nonhomologous kinetochores of the two acrocentrics were closely paired in a cis-configuration and juxtaposed opposite the kinetochore of the metacentric; the latter appeared to be an integral part of the longitudinal SC axis. Meiotic multivalents of interpopulation hybrids included up to 36 chromosome arms. In multivalent SCs, the kinetochores always lay together, with the SC arms arranged away from the central centromere cluster. The paracentromeric regions of the Rb chromosomes appeared to remain unsynapsed on both sides of the centromeres. The SC arms were often linked by end-to-end associations. Following desynapsis of the multivalent SC, the kinetochores of the Rb metacentrics showed a highly nonrandom topologic distribution within the nucleus, reminiscent of their arrangement during synapsis.

Animals↗
PubMed1989

Berenil-induced undercondensation in human heterochromatin.

The aromatic diamidine berenil specifically inhibits the condensation of a subset of constitutive heterochromatin in human lymphocyte cultures. In the normal male chromosome complement, only the quinacrine-brilliant Y heterochromatin exhibits distinct undercondensation. The optimal culture conditions for inhibiting heterochromatin condensation are achieved when berenil is added at a final concentration of 150 micrograms/ml 24 h before cell harvest. Various examples of the use of berenil in the analysis of chromosome rearrangements involving quinacrine-brilliant heterochromatin are presented. A variant, giant-satellited chromosome 22 was found to respond to berenil treatment, although its enlarged and quinacrine-bright short-arm region did not contain Y heterochromatin. Southern blot analysis and chromosome in situ hybridization suggested that most chromosome 22 variants do not stem from Y; acrocentric translocations. The experimentally undercondensed Y heterochromatin is characterized by moderate C-band labeling, bright quinacrine fluorescence, and specific silver staining. At the ultrastructural level, undercondensation is associated with loosely packed, mutliply folded chromatin fibers with a diameter of approximately 250 A and organized probably as loops.

Amidines↗
PubMed1988

Duplication 8q24.2----qter and 15q14----pter resulting from a 3:1 meiotic segregation of a maternal reciprocal translocation.

We report on a 16-year-old female with duplication 8q24.2----qter and 15q14----pter resulting from a 3:1 segregation of a maternal balanced reciprocal translocation. This mode of unbalanced segregation could be predicted from Pachytene-diagram drawing. Most of her clinical manifestations can be related to the proximal 15q trisomy. To our knowledge there is only one previous report of a similar chromosome constitution.

Adolescent↗
PubMed1988

Cytology, embryology, and evolution of the developmental arrest syndrome in newts of the genus Triturus (Caudata: Salamandridae).

We have examined embryonic development in three species (T. carnifex, T. cristatus, and T. marmoratus) of European newts of the genus Triturus (subgenus Neotriton) in which developmental arrest occurs in embryos that are homomorphic for a chromosomal heteromorphism involving chromosome 1 (Horner and Macgregor: J. Herpetol., 19:261-270, 1985). Embryonic arrest occurred during tailbud stages in all three species, but at a slightly earlier stage in T. marmoratus. Two phenotypes were identified among the arrested embryos. One of these is indistinguishable in embryonic morphology from normal embryos at all stages up to the time of arrest, but the other is characterized by a protruding yolk plug, which persists from the late gastrula/early neurula stage to the tailbud arrest stage and apparently interferes with normal morphogenesis. Evidence is presented that the two arrested phenotypes, which occur in approximately equal numbers, represent embryos that carry the two alternative homomorphic chromosome pairs of chromosome 1 heteromorphism. We conclude that developmental arrest reflects a balanced lethal heterozygosity probably resulting from an unequal exchange of genic material between the homologues of chromosome 1 which occurred in a common ancestor of the Neotriton species.

Animals↗
PubMed1988

Inhibition of condensation in the late-replicating X chromosome induced by 5-azadeoxycytidine in human lymphocyte cultures.

The cytidine analogue 5-azadeoxycytidine (5-azadC) induces a very distinct inhibition of condensation in the genetically inactive, late-replicating X chromosome (XL) when applied to human lymphocyte cultures. One of the two X chromosomes in cytogenetically normal female cells becomes dramatically longer than its homologous partner. The highest rate of metaphases with an undercondensed XL chromosome is achieved when 5-aza-dC is added at a final concentration of 10(-5) M 2 h before cell harvesting. The interactions between 5-aza-dC and chromosomal DNA as well as the factors involved in X chromosome inactivation are discussed.

Azacitidine↗
PubMed1988

Analysis of double minutes and double minute-like chromatin in human and murine tumor cells using antikinetochore antibodies.

Antikinetochore antibodies from patients with the calcinosis, Raynaud's phenomenon, esophageal dismobility, sclerodactyly, telangiectasia-(CREST)-syndrome of scleroderma were used as immunofluorescent probes to discriminate between the presence and absence of kinetochores in minute chromosomes not previously seen by conventional banding methods. Double minute chromosomes (DM) consistently lack the antigenic component of the kinetochore, which is direct evidence for the fact that they do not have a centromere. Although somatically stable in malignant cell populations, DM are unable to attach to the mitotic spindle. Conversely, despite their structural similarity to DM, chromosome fragments and supernumerary marker chromosomes exhibit intensely fluorescing kinetochores and, thus, are subject to a precise anaphasic distribution.

Animals↗
PubMed1988

Immunocytogenetics: localization of transcriptionally active rRNA genes in nucleoli and nucleolus organizer regions by use of human autoantibodies to RNA polymerase I.

Cytological staining with silver nitrate (AgNO3) has proved useful for the localization of nucleoli in interphase nuclei, as well as of nucleolus organizer regions (NORs) in metaphase chromosomes. The affinity of interphase nucleoli and chromosomal NORs to silver is a direct measure of the ongoing transcriptional activity of the rRNA genes or their activity during the preceding interphase, respectively. Correspondingly, human autoantibodies directed against chromatin-associated RNA polymerase I (RPI) should also be of value in the investigation of transcribed rRNA genes. Indirect immunofluorescence using the anti-RPI antibody as a probe has been employed successfully to visualize the chromosomal distribution of NORs in various mammalian species, as well as in human tumor cells. Immunofluorescence staining even permits the identification of heteromorphisms and small aberrations of the chromosomal NORs. The fluorescent intensity of interphase nucleoli is correlated with the different stages of nucleolar activation. In male gametogenesis, RPI-positive granules are present during meiotic prophase up to pachytene, as well as during the early and middle spermatid stages.

Animals↗
PubMed1987

The fragile site (16)(q22). II. Sister chromatid exchanges.

In the lymphocytes of heterozygous carriers of the rare autosomal fragile site (16)(q22) an exceptionally high frequency of sister chromatid exchanges was demonstrated at the induced fragile site by means of simultaneous berenil and BrdU treatment of the cultures. The rate of sister chromatid exchanges at q22 is also increased in the fragile chromosome 16 by treating the cells with BrdU alone. The possible reasons for the preferential occurrence of induced and spontaneous sister chromatid exchanges at fra (16)(q22) are discussed.

Bromodeoxyuridine↗
PubMed1987

The chromosomes of Micromys minutus (Rodentia, Murinae). II. Pairing pattern of X and Y chromosomes in meiotic prophase.

Both light and electron microscopy were used to study the pairing behavior of the sex chromosomes of the harvest mouse, Micromys minutus, in surface-spread pachytene spermatocytes. The XY pairing pattern is very exceptional in that the site of synaptic initiation is located interstitially in the short arms of the X and the Y, next to their centromeric regions. From this tiny euchromatic site, synapsis proceeds unidirectionally along the homologous heterochromatic short arms of the X and the Y toward the ends of the chromosomes. After pairing of the short arm is concluded, synapsis begins between the nonhomologous long arms of the X and the Y in the immediate vicinity of the centromeres and progresses unidirectionally toward the end of the long arm of the Y. A synaptic complex develops between the constitutive heterochromatin of the long arm of the Y and the euchromatin of the long arm of the X. Analysis of C-banded and distamycin A/DAPI-stained diakineses revealed a trefoil-like XY bivalent, which was interpreted to be the result of an interstitial chiasma occurring in the paired short arms of the X and the Y. A conspicuous, electron-dense body, about 1 micron in diameter, was found closely associated with the centromeres of the X and the Y in numerous pachytene spermatocytes. A review of the literature showed that comparable XY-associated bodies have been found in only eight other mammals to date.

Animals↗
PubMed1986

Paracentric inversions in human chromosome 7.

A paracentric inversion (7)(q11q22) and mosaicism 46,XX/45,X was detected in a female with minor malformations. The same inversion was observed in the mother of the patient. The analysis of high resolution banded chromosomes revealed no visible imbalance in the inverted long arm of the chromosome 7. All published cases of paracentric inversions in the human chromosome 7 are reviewed and the relationship between this inversion and the occurrence of an aneuploidy of the sex chromosomes is discussed.

Adolescent↗
PubMed1986

Differential inhibition of sister chromatid condensation induced by 5-azadeoxycytidine in human chromosomes.

The deoxycytidine analogue 5-azadeoxycytidine (5-aza-dC) induces differential inhibition of sister chromatid condensation when cells are treated with this substance for two replication cycles, as the subsequent staining of metaphase chromosomes with Giemsa shows. The bifilarly substituted chromatid is dramatically longer than the unifilar one. A percentage of the metaphases treated with 5-aza-dC even show a complete undercondensation of the bifilarly substituted chromatid. The optimum conditions for inducing sister chromatid differentiation were determined. No method has been developed as yet to permit enhancement of the differential staining in 5-aza-dC-treated preparations. The interactions between 5-aza-dC and chromosomal DNA as well as the factors involved in the differential staining of sister chromatids are discussed.

Azacitidine↗
PubMed1986

Structure, origin and effects of a supernumerary marker chromosome 15.

A de novo supernumerary small marker chromosome 15 was observed in a female infant with mental and statomotoric retardation as well as minor facial dysmorphia. The marker chromosome was analyzed by ten different staining techniques and 5-azacytidine treatment of lymphocyte cultures. It is shown that the supernumerary chromosome was derived by a non-sister chromatid exchange between the two homologous maternal chromosomes 15. The cytogenetical properties of the marker chromosome, the different activity of its two nucleolus organizer regions and the somatic pairing configurations revealed by 5-azacyidine are reported.

Child, Preschool↗
PubMed1986

Heterochromatin in the chromosomes of the gorilla: characterization with distamycin A/DAPI, D287/170, chromomycin A3, quinacrine, and 5-azacytidine.

The chromosomes of the gorilla were extensively studied with various staining techniques labeling the different classes of heterochromatin. The chromosomal distribution of distamycin A/DAPI-, D287/170-, quinacrine-, and chromomycin A3-positive heterochromatic regions, as well as the nucleolus organizer regions, is described and compared with the karyotypes of other hominoid species. Lymphocyte cultures were treated with low doses of 5-azacytidine during the last hours of culture. This cytidine analog induces distinct undercondensation in 37 heterochromatic regions in the 24 gorilla chromosomes. The 5-azacytidine-induced undercondensations are localized not only in most of the distamycin A/DAPI-bright heterochromatic regions but also in many telomeric C-bands of the chromosomes. Furthermore, 5-azacytidine preserves the somatic pairing between heterochromatic regions from the interphase nuclei into the metaphase stage. The homeologies and differences in the chromosomal localization of the various classes of heterochromatin, 5-azacytidine-sensitive regions, 5-methylcytosine-rich DNA sequences, and satellite DNAs in the gorilla, chimpanzee, orangutan, and man are discussed.

5-Methylcytosine↗
PubMed1986

Chromosomal homoeologies in hamster species of the genus Phodopus (Rodentia, Cricetinae).

The karyotypes of the two hamster species Phodopus sungorus and P. roborovskii were analyzed with several banding techniques and compared. The homoeologies found between all chromosomes led to the proposal of the most likely common ancestral karyotype of these two species. The differences in the karyotypes were found to be a result of seven independent centric fusions, three inversions, and one possible telomeric fusion, as well as changes in the quantity and DNA-base pair composition of the constitutive heterochromatin.

Animals↗
PubMed1986

Preferential somatic pairing between homologous heterochromatic regions of human chromosomes.

The cytidine analog 5-azacytidine (5-azaC) induces an undercondensation of the heterochromatin in human chromosomes 1, 9, 15, 16, and Y when it is added in low concentrations to the late S-phase of growing lymphocyte cultures. In interphase nuclei, these heterochromatic regions are frequently somatically paired. The somatic pairing configurations are preserved up to metaphase stage in the 5-azaC-treated cultures and are thus susceptible to a direct microscopical examination. The statistical analysis of 1,000 somatic pairing configurations from 5-azaC-treated cells showed that the somatic pairing between the heterochromatic regions of homologous chromosomes is preferred over that between nonhomologous chromosomes.

Azacitidine↗
PubMed1985

Chromosome banding in Amphibia. IX. The polyploid karyotypes of Odontophrynus americanus and Ceratophrys ornata (Anura, Leptodactylidae).

The somatic and meiotic chromosomes of the South American leptodactylid toads Odontophrynus americanus, Ceratophyrys ornata, and C. cranwelli were analysed both with conventional staining and differential banding techniques. The karyotypes of O. americanus were tetraploid; those of C. ornata octaploid. Ceratophrys cranwelli is a diploid species whose karyotype displays great similarities with that of C. ornata. The high frequency of multivalent pairing configurations in the meioses of O. americanus and C. ornata indicate that these animals were of autopolyploid origin. The conventionally stained somatic chromosomes of O. americanus can be arranged into sets of four similar chromosomes (quartets); those of C. ornata, into sets of eight similar chromosomes (octets). The banding patterns revealed heterogeneity within some quartets of O. americanus, dividing each of them into two pairs of homologous chromosomes. In analogy, some octets of C. ornata can be subdivided into two quartets of chromosomes with homologous bands. These structural heterogeneities within the quartets and octets are interpreted as a "diploidization" of the polyploid karyotypes. Diploidization leads to genomes that are polyploid with respect to the amount of genetic material and diploid with respect to chromosomal characteristics and the level of gene expression. In tetraploid O. americanus, the number of nucleolus organizer regions (NORs) and their DNA content is proportional to the degree of ploidy. In contrast, up to eight NORs have been deleted in the octoploid C. ornata. These NOR losses are discussed as a possible reason for the reduction of genetic activity in polyploid genomes.

Animals↗