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C Heyting

Publications and source records attributed to C Heyting.

At least 55 records · Page 3Linked to original sources
PubMed1988

Molecular nature of genetic changes resulting in loss of heterozygosity of chromosome 11 in Wilms' tumours.

In this paper we describe the analysis of genetic changes in chromosome 11 in Wilms' tumours. Using a range of probes for regions 11p15, 11p13 and 11q we have screened DNA from 14 Wilms' tumours together with control DNA obtained from the patients' lymphocytes and their parents. We have been able to demonstrate loss of heterozygosity in 5 of the 14 different Wilms' tumours. In three of these five tumours, loss of heterozygosity did not involve markers for 11p13, 11p15.4 or the proximal region of 11p15.5, but only some markers assigned to the most distal part of 11p15.5. In two of these tumours we could demonstrate unequal mitotic recombination in 11p with breakpoints in the hypervariable regions 5' of the insulin gene and/or 3' of the HRASI proto-oncogene. In one tumour, from a Beckwith-Wiedemann patient, all markers for the region 11q13-pter became hemizygous; the region 11q13-qter remained heterozygous. These results demonstrate that loss of heterozygosity in Wilms' tumours may not necessarily involve the proposed Wilms' tumours locus at 11p13 but may be limited to 11p15.5. This suggests that not only the 11p13 region, but also the 11p15.5 region is involved in Wilms' tumour development. The possible role of both regions in the development of Wilms' tumour is discussed.

Alleles↗
PubMed1988

Two major components of synaptonemal complexes are specific for meiotic prophase nuclei.

Monoclonal antibody II52F10 was elicited against purified synaptonemal complexes (SCs); it recognizes two major components of the lateral elements of SCs, namely an Mr = 30,000 and an Mr = 33,000 protein. We studied the distribution of the antigens of II52F10 within tissues and cells of the male rat by immunoblot analysis and immunocytochemical techniques. Nuclear proteins from various cell types, including spermatogonia and spermatids, did not react with antibody II52F10 on immunoblots; the same holds for proteins from isolated mitotic chromosomes. As expected, an Mr = 30,000 and an Mr = 33,000 protein from spermatocyte nuclei did react with the antibody. In cryostat sections of liver, brain, muscle and gut we could not detect any reaction with II52F10. In the testis the reaction was confined to SCs or SC fragments. Partly on the basis of indirect evidence we identified the antigen-containing cells as zygotene up to and including post-diffuse diplotene spermatocytes. The persistence of some antigen-containing fragments in the earliest stages of spermatids could not be excluded. We conclude that the lateral elements (LEs) of SCs are not assembled by rearrangement of pre-existing components of the nucleus: at least two of their major components are newly synthesized, presumably during zygotene. Furthermore we conclude partly from indirect evidence that the major components of the LEs of SCs are not involved in the chromosome condensation processes that take place during the earliest stages of meiotic prophase.

Animals↗
PubMed1988

Morphological transformation by early region human polyomavirus BK DNA of human fibroblasts with deletions in the short arm of one chromosome 11.

Human fibroblasts derived from four individuals with various deletions in the short arm of one chromosome 11 were susceptible to morphological transformation by early region BK virus DNA, whereas diploid human fibroblasts were not. This difference in susceptibility to transformation by early region BK virus DNA might be explained by a putative 'transformation suppressor' locus situated within the deleted region on the short arm of chromosome 11.

BK Virus↗
PubMed1987

Regional localization of DNA probes on the short arm of chromosome 11 using aniridia-Wilms' tumor-associated deletions.

We are interested in the precise localization of various DNA probes on the short arm of chromosome 11 for our research on the aniridia-Wilms' tumor association (AWTA), assigned to region 11p13 (Knudson and Strong 1972; Riccardi et al. 1978). For this purpose we have screened lymphocyte DNA and material derived from somatic cell hybrids from individuals with constitutional 11p deletions with a range of available probes: D11S12; calcitonin/CGRP (CALC1/CALC2); insulin (INS); Harvey ras 1 (HRAS 1); beta-globin gene cluster (HBBC); human insulin-like growth factor 2 (IGF-2); parathyroid hormone (PTH); human pepsinogen A (PGA). Using this material, it has been possible to map all probes used, except insulin, outside the region 11p111-p15.1, resulting in an SRO (same regional overlap) of 11p15.1-p15.5 for most probes. We found an SRO for PGA of 11p111-q12 and an SRO for CALC2 of 11p15.1-p15.5 or 11p111-q12. We have localised the insulin gene to band 11p15.1.

Animals↗
PubMed1987

Synaptonemal complex antigen location and conservation.

The axial cores of chromosomes in the meiotic prophase nuclei of most sexually reproducing organisms play a pivotal role in the arrangement of chromatin, in the synapsis of homologous chromosomes, in the process of genetic recombination, and in the disjunction of chromosomes. We report an immunogold analysis of the axial cores and the synaptonemal complexes (SC) using two mouse monoclonal antibodies raised against isolated rat SCs. In Western blots of purified SCs, antibody II52F10 recognizes a 30- and a 33-kD peptide (Heyting, C., P. B. Moens, W. van Raamsdonk, A. J. J. Dietrich, A. C. G. Vink, and E. J. W. Redeker, 1987, Eur. J. Cell Biol., 43: 148-154). In spreads of rat spermatocyte nuclei it produces gold grains over the cores of autosomal and sex chromosomes. The cores label lightly during the chromosome pairing stage (zygotene) of early meiotic prophase and they become more intensely labeled when they are parallel aligned as the lateral elements of the SC during pachytene (55 grains/micron SC). Statistical analysis of electronically recorded gold grain positions shows that the two means of the bimodal gold grain distribution coincide with the centers of the lateral elements. At diplotene, when the cores separate, the antigen is still detected along the length of the core and the enlarged ends are heavily labeled. Shadow-cast SC preparations show that recombination nodules are not labeled. The continued presence suggests that the antigens serve a continuing function in the cores, such as chromatin binding, and/or structural integrity. Antibody III15B8, which does not recognize the 30- and 33-kD peptides, produces gold grains predominantly between the lateral elements. The grain distribution is bimodal with the mean of each peak just inside the pairing face of the lateral element. The antigen is present where and while the cores of the homologous chromosomes are paired. From the location and the timing, it is assumed that the antigen recognized by III15B8 functions in chromosome pairing at meiotic prophase. The two anti-rat SC antibodies label rat and mouse SCs but not rabbit or dog SCs. A positive control using human CREST (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia) anti-centromere serum gives equivalent labeling of SC centromeres in the rat, mouse, rabbit, and dog. It is concluded that the SC antigens recognized by II52F10 and III15B8 are not widely conserved. The two antibodies do not bind to cellular or nuclear components of somatic cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Identification of two major components of the lateral elements of synaptonemal complexes of the rat.

This paper describes the identification of two major components of the lateral elements of synaptonemal complexes of the rat by immunocytochemical techniques. We prepared monoclonal antibodies against synaptonemal complexes (SCs) by immunization of mice with purified SCs. One of these antibodies, II52F10, reacts with a 30 and a 33 kDa polypeptide, which are major components of purified SCs. Using this antibody, we studied the localization of its antigens light microscopically, by means of the indirect immunoperoxidase technique, as well as ultrastructurally, by means of the immunogold labeling technique. The immunolocalization was carried out on whole-mount preparations of lysed spermatocytes. The antibody reacts with paired as well as unpaired segments of zygotene, pachytene and diplotene SCs. In light microscopic preparations, the attachment plaques, particularly those of late pachytene and diplotene SCs, also appear to react strongly. In electron micrographs the lateral elements in paired as well as unpaired segments could be seen to react. No reaction was observed in the attachment plaques; however, in late pachytene and diplotene SCs the swollen terminal segments of the lateral elements did react with the antibody. Thus, we conclude that a 30 and a 33 kDa polypeptide make part of the lateral elements of synaptonemal complexes of the rat.

Animals↗
PubMed1985

Hybridization of N-acetoxy-N-acetyl-2-aminofluorene-labelled RNA to Q-banded metaphase chromosomes.

This paper describes improvements of a recently developed immunocytochemical method for the detection of specific polynucleotide sequences within chromosomes, as well as conditions by which this method can be combined with chromosome banding. The immunocytochemical method involves modification of polynucleotide probes with N-acetoxy-N-acetyl-2-aminofluorene (AAAF)2), and hybridization of the modified probes with metaphase chromosomes; the hybrids are made visible immunocytochemically by means of an antiserum which recognizes AAAF-induced polynucleotide modifications. We have sorted out conditions which allow a high sensitivity of hybrid detection by the above procedure, in combination with chromosome banding. The best results are obtained if the ABC-technique is used for the visualization of the hybrids; the lower limit of detection is estimated to be a sequence of about 7000 nucleotides. The method can be combined with Q-banding of chromosomes, if this is performed not more than 1 day prior to hybridization, and if excitation of the Q-banded chromosomes is kept to a minimum.

2-Acetylaminofluorene↗
PubMed1985

Structure and composition of synaptonemal complexes, isolated from rat spermatocytes.

Synaptonemal complexes (SCs) (structures involved in chromosome pairing during meiosis) were isolated and purified from rat spermatocytes for the purpose of biochemical and morphological analysis. Spermatocytes were lysed in a medium, containing Triton X-100, EDTA and DTT; the resulting swollen nuclei were disrupted by DNAse II, and the suspension was centrifuged through 1.5 M sucrose. The resulting preparation consisted for at least 60% of free SCs, as judged from electron micrographs of agar filtrates. The purified SCs still possessed lateral and transversal elements and attachment plaques. A small fraction also contained a central element. Particularly in diplotene SCs, the lateral elements clearly consisted of two subelements, which are connected by thinner fibres. The lateral elements may fall apart into a network of thinner fibres, presumably as a result of degradation during isolation. On SDS-polyacrylamide gels, the major protein components of purified SCs had relative mobilities (Mrs) of 67 to 60 and 57 to 55 kDa; in addition, there were minor proteins with Mrs of 90, 35, 33, 28, and 26 kDa, and varying amounts of histones. The 67 to 60 kDa proteins comigrate with lamins of rat liver pore complexes and laminae. A possible relationship between SCs and pore complexes and laminae is discussed.

Animals↗
PubMed1983

Immunohistochemical detection of O6-ethyldeoxyguanosine in the rat brain after in vivo applications of N-ethyl-N-nitrosourea.

An immunohistochemical procedure was developed which allows the localization of the DNA lesion O6-ethyldeoxyguanosine (O6-EtdGuo) within tissues and organs. The method permits the detection of 24,000 residues of O6-EtdGuo per diploid nucleus. We have used this procedure to localize N-ethyl-N-nitrosourea (ENU)-induced O6-EtdGuo in the rat brain. Shortly after a single injection of ENU, we observed O6-EtdGuo in most or all of the rat brain nuclei. After repeated injections of small doses of ENU, with intervals of 1 or 2 weeks between the injections and between the last injection and sacrifice, we could demonstrate O6-EtdGuo only in part of the rat brain nuclei. Oligodendrocytes, granular neurons and endothelial cells, and part of the pyramidal neurons and astrocytes had accumulated O6-EtdGuo, while in all other cells this lesion was not detectable after repeated injections of small doses of ENU. We found no obvious correlation between the putative sensitivity of rat brain cells to tumor induction and the accumulation of O6-EtdGuo in their DNA.

Animals↗
PubMed1982

Differentiation of muscle fiber types in the teleost Brachydanio rerio, the zebrafish. Posthatching development.

The trunk musculature of adult zebrafishes contains three major fiber types: adult red, intermediate, and white; and two minor populations: red muscle rim and scattered intermediate fibers. In this paper, the post hatching development of these muscle fiber types was studied by means of immunohistochemistry, using anti-myosin sera. Just hatched larvae contain two muscle fiber populations: embryonic red and white, which give rise to the red muscle rim and the intermediate fibers respectively. Adult red fibers arise post hatching as a new separate population with distinct myosin properties. The differentiation of these fiber types occurs within the first four weeks after fertilization, when the adult pattern of peripheral axon bundles has become established. Differences in the muscle fiber type composition between the midbody and the tail myotomes become apparent in two month old fries. The number of scattered intermediate fibers increases from rostral to caudal, the opposite holds for the red muscle rim fibers. The red and intermediate area is triangular in the midbody; in the tail part it is stretched out along the lateral surface of the myotomes. These changes are considered as adaptations to improve the efficiency of the swimming performance.

Animals↗
PubMed1982

Effects of immobilization and partial denervation on the differentiation of muscle fiber types in the Zebrafish, Brachydanio rerio.

In this study we tested the effects of immobilization and of spinal cord lesion on the differentiation of muscle fiber types in the myotomal muscle of the zebrafish. We found that the differentiation of embryonic red and white muscle fibers occurs in immobilized as well as in denervated myotomes of zebrafish embryos. Intermediate and adult red muscle fibers are not formed in denervated myotomes of larvae. Adult zebrafishes with spinal cord lesions in the anal region show abnormal undulating movements in the rostral part of the body. This change in muscle activity correlates with an increase in the number of intermediate scattered fibers. We conclude that direct contact with spinal cord motorneurons is not necessary for the differentiation of embryonic red and white fibers. The differentiation of intermediate muscle fibers is under extrinsic control. The factors that determine the formation of adult red fibers are not yet clear.

Animals↗
PubMed1980

Repair of ethylnitrosourea-induced DNA damage in the newborn rat. I. Alkali-labile lesions and in situ breaks.

The extreme sensitivity of the developing rat brain to tumor induction by N-ethyl-N-nitrosourea (ENU) has been ascribed to the relatively inefficient repair of the presumed promutagenic lesion O6-ethylguanine from brain DNA. We have compared the brain of the newborn rat with liver, kidney and lung with respect to the repair of other types of DNA lesions that ENU induces, namely single strand breaks and alkali-labile lesions. The induction and repair or loss of these lesions has been analysed by alkaline sucrose gradient sedimentation using both mild as well as strong alkaline hydrolysis conditions. We found that ENU induces few lesions in the DNA of various organs that are detectable as breaks after mild alkaline hydrolysis. 24 h after ENU treatment such lesions are no longer detectable in brain DNA, while they are detectable in the DNA from other organs up to 10 days after ENU treatment. The number of ENU-induced lesions, detectable as breaks after strong alkaline hydrolysis, is far larger. These lesions were persistent in kidney DNA, disappeared slowly from liver DNA (t(1/2) = about 10 days), and more rapidly from brain and lung DNA (t(1/2) = 2-3 days). The latter result seems to be in contradiction with various reports that a large fraction of the ENU-induced alkali-labile lesions are stable in vivo. This difference between our results and those of others might be due to a difference between proliferating and non-proliferating cells. Whether the alkali-labile lesions are removed from brain and lung DNA by a specific repair mechanism or by other causes remains to be investigated.

Adenine↗
PubMed1979

Fine structure of the 21S ribosomal RNA region on yeast mitochondria DNA. I. Construction of the physical map and localization of the cistron for the 21S mitochondrial ribosomal RNA.

1. We have used restriction enzyme analysis of petite mtDNAs to construct a detailed physical map of the 21S region on the mtDNA of the Saccharomyces cerevisiae strain JS1-3D. The map covers a segment of about 20,000 bp, on which the recognition sites of the enzymes HapII, HindII, HindIII, Sa1I, XhoI and HhaI have been localized (22 sites in total). This map has been checked in various ways against the independently constructed overall physical map of the mtDNA of strain JS1-3D. In addition, we have constructed a physical map with a resolution of about 200 bp of a HapII fragment of 1850 bp long, which carries the loci omega, RIB-1 and probably RIB-2. 2. The 21S rRNA hybridizes with the five adjacent HindII + III fragments TD9, DT19, TD15, DT14 and TT1, which lie in that order on the physical map of the 21S region. Of these, the two non-adjacent fragments TD9 and DT14 show a much stronger hybridization with 21S rRNA than DT19, TD15, and TT1. 3. The fragment DD5 (= DT19 + TD15) and part of DT14 belong to a sequence of about 1000 bp, which is absent from Saccharomyces carlsbergensis mtDNA. Although DD5 and DT14 show (very weak, respectively stronger) hybridization with 21S rRNA, the 1000 bp insert probably does not code for the 21S rRNA: the 21S rRNA of S. carlsbergensis comigrates with the 21S rRNA of JS1-3D on polyacrylamide gels under denaturing conditions. 4. Fragment DT14 hybridizes with the HindII + III fragment TD9, which shows the strongest hybridization with 21S rRNA. The presence of these sequence homologies has hampered the precise mapping of the 21S rRNA cistron. Our results are compatible, however, with the hypothesis that the sequences, coding for 21S rRNA, are located on HindII + III fragments that are not adjacent on JS1-3D mtDNA, namely TD9, DT14 and TT1.

DNA Restriction Enzymes↗
PubMed1979

Fine structure of the 21S ribosomal RNA region on yeast mitochondrial DNA. II. The organization of sequences in petite mitochondrial DNAs carrying genetic markers from the 21S region.

We have investigated the organization of sequences in ten rho- petite mtDNAs by restriction enzyme analysis and electron microscopy. From the comparison of the physical maps of the petite mtDNAs with the physical map of the mtDNA of the parental rho+ strain we conclude that there are at least three different classes of petite mtDNAs: I. Head-to-tail repeats of an (almost) continuous segment of the rho+ mtDNA. II. Head-to-tail repeats of an (almost) continuous segment of the rho+ mtDNA with a terminal inverted duplication. III. Mixed repeats of an (almost) continuous rho+ mtDNA segment. In out petite mtDNAs of the second type, the inverted duplications do not cover the entire conserved rho+ mtDNA segment. We have found that the petite mtDNAs of the third type contain a local inverted duplication at the site where repeating units can insert in two orientations. At least in one case this local inverted duplication must have arisen by mutation. The rearrangements that we have found in the petite mtDNAs do not cluster at specific sites on the rho+ mtDNA map. Large rearrangements or deletions within the conserved rho+ mtDNA segment seem to contribute to the suppressiveness of a petite strain. There is also a positive correlation between the retention of certain segments of the rho+ mtDNA and the suppressiveness of a petite strain. We found no correlation between the suppressiveness of a petite strain and its genetic complexity. The relevance of these findings for the mechanism of petite induction and the usefulness of petite strains for the physical mapping of mitochondrial genetic markers and for DNA sequence analysis are discussed.

Base Sequence↗
PubMed1979

Fine structure of the 21S ribosomal RNA region on yeast mitochondrial DNA. III. Physical location of mitochondrial genetic markers and the molecular nature of omega.

1. We have determined the physical location of mitochondrial genetic markers in the 21S region of yeast mtDNA by genetic analysis of petite mutants whose mtDNA has been physically mapped on the wild-type mtDNA. 2. The order of loci, determined in this study, is in agreement with the order deduced from recombination analysis and coretention analysis except for the position of omega+: we conclude that omega+ is located between C321 (RIB-1) and E514 (RIB-3). 3. The marker E514 (RIB-3) has been localized on a DNA segment of 3800 bp, and the markers E354, E553 and cs23 (RIB-2) on a DNA segment of 1100 base pairs; both these segments overlap the 21S rRNA cistron. The marker C321 (RIB-1) has been localized within a segment of 240 bp which also overlaps the 21S rRNA cistron, and we infer on the basis of indirect evidence that this marker lies within this cistron. 4. In all our rho+ as well as rho- strains there is a one-to-one correlation between the omega+ phenotype, the ability to transmit the omega+ allele and the presence of a mtDNA segment of about 1000 bp long, located between sequences specifying RIB-3 and sequences corresponding to the loci RIB-1 and RIB-2. This segment may be inserted at this same position into omega- mtDNA by recombination. 5. The role which the different allelic forms of omega may play in the polarity of recombination is discussed.

DNA, Mitochondrial↗