Lampbrush Chromosome

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Alla Krasikova - One of the best experts on this subject based on the ideXlab platform.

J C Lacroix - One of the best experts on this subject based on the ideXlab platform.

  • cytogenetic maps of Lampbrush Chromosomes of newts of the genus pleurodeles an algorithm of Lampbrush Chromosome identification inpleurodeles waltl by immunocytochemical staining of landmark loops with polyclonal anti ro52 antisera
    Russian Journal of Genetics, 2004
    Co-Authors: N M Vishnyakova, J C Lacroix, A V Rodionov
    Abstract:

    Our work was aimed at developing a simple and effective method of identification of most or all Chromosomes of Pleurodelesnewts. To this end, we used DAPI staining of the chromomeres of newt Lampbrush Chromosomes and immunochemical reactions between the ribonucleoproteins of landmark lateral loops and polyclonal antibodies against human zinc-finger protein Ro52 (52-kDa Ro/SS-A). A method has been developed to obtain Lampbrush Chromosome preparations in newts of the genes Pleurodeles. Cytological maps of P. waltl Chromosomes (Spanish population/subspecies) showing distributions of chromomeres and marker landmark loops along the Chromosome length were constructed.

  • A zinc-binding domain is required for targeting the maternal nuclear protein PwA33 to Lampbrush Chromosome loops.
    Rockefeller University Press, 1995
    Co-Authors: Michel Bellini, J C Lacroix, J G Gall
    Abstract:

    In oocytes of the newt Pleurodeles waltl, the maternal nuclear protein PwA33 occurs on the Lampbrush Chromosomes and in some nucleoplasmic particles of the germinal vesicle. PwA33 is a modular protein and we used site-directed mutagenesis to alter the sequences encoding two metal-binding regions, the C3HC4 (or RING finger) and B-box motifs. Several mutant clones were generated and their synthetic transcripts were injected into Pleurodeles oocytes for in vivo analysis. In the oocyte, all translation products localized in the germinal vesicle. Proteins encoded by RING finger mutant clones were distributed in a pattern identical to that of the wild type protein, but when His266 of the B-box was mutated, PwA33 failed to localize in the Lampbrush Chromosomes and the nucleoplasmic particles. Using an in vitro colorimetric assay, we demonstrated that PwA33 is a zinc-binding protein and that mutations in the RING finger and B-Box altered its metal-binding properties. The RING finger motif bound two Zn2+ ions and the binding ratios of several mutants were consistent with the tertiary structure recently proposed for this motif. The B-box coordinated one Zn2+ and this binding was inhibited by the His266 mutation. The failure of the His266 mutation to bind zinc and to localize properly within the germinal vesicle suggests that an intact B-box is required for normal functioning of the PwA33 protein in the oocyte.

  • localization of antigens pwa33 and la on Lampbrush Chromosomes and on nucleoplasmic structures in the oocyte of the urodele pleurodeles waltl light and electron microscopic immunocytochemical studies
    Chromosoma, 1994
    Co-Authors: Chandra K Pyne, Francoise Simon, M T Loones, G Geraud, Michael Bachmann, J C Lacroix
    Abstract:

    Monoclonal antibodies A33/22 and La11G7 have been used to study the distribution of the corre-sponding antigens, PwA33 and La, on the Lampbrush Chromosome loops and nucleoplasmic structures of P. waltl oocytes, using immunofluorescence, confocal laser scanning microscopy and immunogold labeling. The results obtained with these antibodies have been compared with those obtained with the Sm-antigen-specific monoclonal antibody Y12. All these monoclonal antibodies (mAbs) labeled the matrices of the majority of normal loops along their whole length. Nucleoplasmic RNP granules showed a strong staining with the mAbs La11G7 and Y12 throughout their mass, but with the mAb A33/22, they showed only a weak peripheral labeling in the form of patches on their surface. This patchy labeling was confirmed by confocal laser scanning microscopy. Electron microscopy revealed that this patchy labeling might be due to a hitherto undescribed type of submicroscopic granular structure, around 100 nm in either dimension, formed by 10-nm particles. Such granules were observed either attached to the RNP granules or free in the nucleoplasm, but rarely in relation with the normal loop matrices. These 100-nm granules may have a role in the movement of proteins and snRNPs inside the oocyte nuclei for storage, recycling, and/or degradation. Our results also suggest that all the microscopically visible free RNP granules of the nucleoplasm of P. waltl oocytes correspond to B snurposomes. The granules forming the B (globular) loops showed a labeling pattern similar to that of B snurposomes; their possible relationship is discussed.

  • A putative zinc-binding protein on Lampbrush Chromosome loops.
    The EMBO journal, 1993
    Co-Authors: Michel Bellini, J C Lacroix, J G Gall
    Abstract:

    We used mAb A33/22, which recognizes a nuclear protein on the loops of amphibian Lampbrush Chromosomes, to select cDNA clone PwA33 from an expression library of the newt Pleurodeles waltl. A myc-tagged transcript of clone PwA33 was injected into Pleurodeles oocytes. The translation product localized in the germinal vesicle (GV) and was distributed on the Lampbrush loops in a pattern identical to that of the endogenous protein. PwA33 encodes a 71 kDa protein with three distinct domains: a region rich in Cys/His residues that may form zinc fingers, a coiled-coil domain with potential for dimerization and a third 'rfp-like' domain that is shared by several other nuclear proteins. The putative zinc fingers and the coiled-coil domain resemble features in known nucleic acid-binding regulatory proteins. These structures, coupled with a distinctive pattern of expression in embryonic tissues, suggest that A33 may function as a regulatory protein during early development. It is unlikely that the large store of A33 in the GV is bound to DNA. Instead, its association with the nascent transcripts on the Lampbrush Chromosome loops suggests a role in pre-mRNA synthesis or processing.

Joseph G Gall - One of the best experts on this subject based on the ideXlab platform.

  • Corresponding author:
    2016
    Co-Authors: Joseph G Gall
    Abstract:

    Abbreviations: GV, germinal vesicle; LBC, Lampbrush Chromosome; pol II, polymerase II; TU, transcription unit. 2 Lampbrush Chromosomes (LBCs) are transcriptionally active Chromosomes found in the germinal vesicle (GV) of large oocytes of many vertebrate and invertebrate animals and also in the giant single-celled alga Acetabularia. These cells are all in prophase of the first meiotic division. Nevertheless, many meiotic cells do not develop LBCs, arguing that LBCs are not an essential feature of meiosis. LBCs probably represent the most active transcriptional state that can be attained by cells that must give rise to diploid progeny. Polyploidy permits cells to reach higher rates of transcription per nucleus but precludes a return to diploidy. In this sense LBCs represent a relatively inefficient transcriptional compromise employed by large meiotic cells. These considerations help to explain why transcriptionally active GVs develop LBCs, but they do not explain why LBCs have never been seen in somatic cells, diploid or otherwise. If LBCs are truly limited to germ cells, then some of their unusual features may reflect reprogramming of the genome. If this is the case, LBCs provide unique opportunities to study reprogramming at the level of the individual transcription unit

  • Interview by the Author
    2005
    Co-Authors: Ji-long Liu, Joseph G Gall
    Abstract:

    GV: germinal vesicle LBC: Lampbrush Chromosome Pol II: RNA polymerase 2 Pol III: RNA polymerase 3 RNP: ribonucleoprotein PVP: polyvinylpyrrolidone snRNP: small nuclear ribonucleoprotein 3 We previously demonstrated that sperm heads from amphibians (Xenopus and Rana) and zebrafish (Danio) could form giant Lampbrush Chromosomes when injected into the nucleus of amphibian oocytes. However, similar experiments with mammalian sperm heads were unsuccessful. Here we describe a slightly modified procedure and demonstrate that human sperm heads can form giant Lampbrush Chromosomes when injected into the oocyte nucleus of the frog Xenopus laevis or the newt Notophthalmus viridescens. Human and other mammalian Chromosomes do not form recognizable Lampbrush Chromosomes in their own oocytes or in any somatic cells. These experiments thus demonstrate that the Lampbrush condition is an inducible state and that the amphibian oocyte nucleus contains all factors required to remodel the inactive chromatin of a mammalian sperm into a transcriptionally active state. They also demonstrate that absence of Lampbrush Chromosomes from human oocytes must relate to specific features of mammalian oogenesis, not to permanent genetic or epigenetic changes in the chromatin

  • transcription on Lampbrush Chromosome loops in the absence of u2 snrna
    Molecular Biology of the Cell, 1992
    Co-Authors: A Tsvetkov, Christine Murphy, Michael F. Jantsch, Joseph G Gall
    Abstract:

    The five small nuclear RNAs (snRNAs) involved in splicing occur on the loops of amphibian Lampbrush Chromosomes and in hundreds to thousands of extrachromosomal granules called B snurposomes. To assess the role of these snRNAs during transcription and to explore possible relationships between the loops and B snurposomes, we injected single-stranded antisense oligodeoxynucleotides (oligos) against U1 and U2 snRNA into toad and newt oocytes. As shown before, antisense U1 and U2 oligos caused truncation of U1 and complete destruction of U2 snRNAs, respectively. However, injection of any oligo, regardless of sequence, brought on dramatic cytological changes, including shortening of the Chromosomes and retraction of the lateral loops, with concomitant shutdown of polymerase II transcription, as well as disappearance of some or all of the B snurposomes. When injected oocytes were incubated for 12 h or longer in physiological saline, these changes were reversible; that is, the Chromosomes lengthened, transcription (detected by 3H-UTP incorporation) resumed on newly extended lateral loops, and B snurposomes reappeared. In situ hybridization showed that loops and B snurposomes had negligible amounts of U2 snRNA after recovery from injection of the anti-U2 oligo, whereas these structures had normal levels of U2 snRNA after recovery from a control oligo. Thus, the morphological integrity of B snurposomes and Lampbrush Chromosome loops is not dependent on the presence of U2 snRNA. Because transcription occurs in the absence of U2 snRNA, we conclude that splicing is not required for transcription on Lampbrush Chromosome loops.

  • Assembly and localization of the Ul-specific snRNP C protein in the amphibian oocyte
    1992
    Co-Authors: Michael E Jantsch, Joseph G Gall
    Abstract:

    Abstract. To study the intranuclear localization of the Ul-specific snRNP C protein and its assembly into U1 snRNPs, we injected transcripts encoding a myctagged C protein into amphibian oocytes. The distribution of protein translated from the injected RNA was essentially the same in continuous and pulse-label experiments. In both cases the C protein localized within the germinal vesicle in those structures known to contain U1 snRNPs, namely the Lampbrush Chromosome loops and hundreds of extrachromosomal granules called snurposomes. Oocytes were also injected with an antisense oligodeoxynucleotide that caused truncation of U1 snRNA at the 5 ' end. In these oocytes, myc-tagged C protein localized normally in the germinal vesicle and could be immunoprecipitated togethe

  • small nuclear ribonucleoproteins and heterogeneous nuclear ribonucleoproteins in the amphibian germinal vesicle loops spheres and snurposomes
    Journal of Cell Biology, 1991
    Co-Authors: Christine Murphy, H. G. Callan, Joseph G Gall
    Abstract:

    We have examined the distribution of snRNPs in the germinal vesicle (GV) of frogs and salamanders by immunofluorescent staining and in situ nucleic acid hybridization. The major snRNAs involved in pre-mRNA splicing (U1, U2, U4, U5, and U6) occur together in nearly all loops of the Lampbrush Chromosomes, and in hundreds to thousands of small granules (1-4 microns diameter) suspended in the nucleoplasm. The loops and granules also contain several antigens that are regularly associated with snRNAs or spliceosomes (the Sm antigen, U1- and U2-specific antigens, and the splicing factor SC35). A second type of granule, often distinguishable by morphology, contains only U1 snRNA and associated antigens. We propose the term "snurposome" to describe the granules that contain snRNPs ("snurps"). Those that contain only U1 snRNA are A snurposomes, whereas those that contain all the splicing snRNAs are B snurposomes. GVs contain a third type of snRNP granule, which we call the C snurposome. C snurposomes range in size from less than 1 micron to giant structures greater than 20 microns in diameter. Usually, although not invariably, they have B snurposomes on their surface. They may also contain from one to hundreds of inclusions. Because of their remarkably spherical shape, C snurposomes with their associated B snurposomes have long been referred to as spheres or sphere organelles. Most spheres are free in the nucleoplasm, but a few are attached to Chromosomes at specific Chromosome loci, the sphere organizers (SOs). The relationship of sphere organelles to other snRNP-containing structures in the GV is obscure. We show by immunofluorescent staining that the Lampbrush loops and B snurposomes also react with antibodies against heterogeneous nuclear ribonucleoproteins (hnRNPs). Transcription units on the loops are uniformly stained by anti-hnRNP and anti-snRNP antibodies, suggesting that nascent transcripts are associated with hnRNPs and snRNPs along their entire length, perhaps in the form of a unitary hnRNP/snRNP particle. That B snurposomes contain so many components involved in pre-mRNA packaging and processing suggests that they may serve as sites for assembly and storage of hnRNP/snRNP complexes destined for transport to the nascent transcripts on the Lampbrush Chromosome loops.

Elena Gaginskaya - One of the best experts on this subject based on the ideXlab platform.

  • Avian Lampbrush Chromosomes: a Powerful Tool for Exploration of Genome Expression
    2016
    Co-Authors: Cytogenet Genome Res, Alla Krasikova, Elena Gaginskaya, T. Kulikova, Key Words
    Abstract:

    some specific features: very long transcription units, deregu-lated termination, and transcription of non-coding satellite repeats. Here, based on the modern view on a role of RNA interference machinery in regulation of genome expression, we suggest a mechanism of initiation of satellite DNA tran-scription and offer a novel interpretation of the ‘classical ’ hy-pothesis that sought to explain the significance of wide-spread transcription during oocyte growth. Copyright © 2009 S. Karger AG, Basel The investigation of genome structure and function has been greatly helped by studies of model systems such as polytene and Lampbrush Chromosomes that facilitate exploration of gene activity in vivo. In this respect, giant Lampbrush Chromosomes (LBCs) deserve special atten-tion. They represent a special form of meiotic chromo-somes, which is assumed during oocyte growth in most animals other than mammals [Callan, 1986; Macgregor, 1987, 2002] except for some monotremes [Lintern-Moore et al., 1976]. LBCs were first observed in 1882 by W. Flemming in amphibian oocytes and investigated in detail by J. Rück-ert in shark oocytes in 1892. Actually, we owe the name ‘Lampbrush Chromosome ’ to J. Rückert, who compared them with bristled brushes for cleaning oil lamps. The history of discovery and early studies of amphibian LBC

  • RESEARCH ARTICLE Tandem 41-bp repeats in chicken and Japanese quail
    2007
    Co-Authors: Transcription Analysis, Alla Krasikova, Svetlana Deryusheva, Tatiana Kulikova, Elena Gaginskaya
    Abstract:

    on Lampbrush Chromosome

  • Cohesion proteins are present in centromere protein bodies associated with avian Lampbrush Chromosomes
    Chromosome Research, 2005
    Co-Authors: Alla Krasikova, Jose Luis Barbero, Elena Gaginskaya
    Abstract:

    Proteins of sister chromatid cohesion are important for maintenance of meiotic Chromosome structure and retention of homologous Chromosomes in bivalents during diplotene. Localization of the cohesion proteins within nuclei of growing oocytes merits special attention, particularly in avian oocytes, in which diplotene Chromosomes assume the form of Lampbrush Chromosomes (LBCs). We performed indirect immunostaining using antibodies against cohesins SMC1α, SMC1β, SMC3, Rad21, and the SA/STAG family on chaffinch, pigeon and duck LBCs spreads, and frozen ovary sections. On LBCs spreads, antibodies to the majority of cohesins showed punctate staining on Chromosome axes. LBC lateral loops, where sister chromatids are separated, did not show cohesin components. The spherical entities attached to the LBCs centromeres in avian germinal vesicles, the so-called protein bodies (PBs), were enriched in SMC1α, SMC3, Rad21, STAG1 and STAG2. The synaptonemal complex component SYCP3, which also participates in cohesion, was detected in the axes of avian Lampbrush bivalents and, to a greater degree, in the PBs. In vitellogenic oocytes, cohesion proteins persist in the PBs associated with condensing bivalents when they concentrate into the karyosphere. These results indicate that cohesion proteins accumulate in centromere PBs in avian oocytes and are involved into structural maintenance of Lampbrush Chromosome axes.

  • Precise identification of chicken Chromosomes in the Lampbrush form using Chromosome painting probes
    Chromosome Research, 2003
    Co-Authors: Svetlana Derjusheva, Alla Krasikova, Anna Kurganova, Alsu Saifitdinova, Felix A. Habermann, Elena Gaginskaya
    Abstract:

    Chromosome painting probes specific for macroChromosomes 1, 2, 3, 4, 5, and Z were applied to both mitotic and Lampbrush Chromosomes of the chicken ( Gallus gallus domesticus ). Five autosomal macrobivalents and sex Chromosome Z in the Lampbrush phase were identified and their correspondence to the target Chromosomes in the metaphase of mitosis was shown. Nascent transcripts on lateral loops of the target Lampbrush Chromosome were intensively labelled when the hybridization was performed without RNase A treatment according to the DNA/(DNA+RNA) hybridization protocol.

  • a novel structure associated with a Lampbrush Chromosome in the chicken gallus domesticus
    Journal of Cell Science, 1992
    Co-Authors: Irina Solovei, Elena Gaginskaya, Terence D Allen, Herbert C. Macgregor
    Abstract:

    At a site near the end of the short arms of Lampbrush bivalent 2 in the chicken (Gallus domesticus) there is always a marker structure that appears in the phase-contrast light microscope as a solid object with diffuse edges measuring about 4 microns across. When examined by transmission electron microscopy in thin section, this object appears as a loose bundle of fibres. In some preparations individual fibres appear 15–16 nm thick, smooth in outline and solid in cross-section. In other preparations they are 32–38 nm thick, rougher in outline and ring-like in cross-section. High-resolution scanning electron micrographs of the Chromosome 2 marker show it to be a loose bundle of spaghetti-like fibres that is quite unlike anything previously seen on a Lampbrush Chromosome of any organism. As with the sectioned material, fibres in some preparations were smooth and 15–16 nm in diameter, whereas those in others were more knobbly and about 35 nm thick. The fibres appear to branch and in some cases it is clear that the daughter strands of a branch have the same dimensions as the parent strand. Free ends are rare. Total length of fibre material present at one marker locus is estimated to be between 500 and 2000 microns. Similar structures are not present on the Lampbrush Chromosomes of quail, wood pigeon or chaffinch. The nature of this fibrous marker, referred to in this paper as the “spaghetti marker”, is discussed in relation to Lampbrush Chromosome function and to events that take place during the Lampbrush phase of oogenesis in chicken. Evidence is discussed in relation to the possibility that the Chromosome 2 marker represents a novel form of nuclear RNP or the specific association of some structural protein with one Chromosome locus.

Garry T. Morgan - One of the best experts on this subject based on the ideXlab platform.

  • Review Lampbrush Chromosomes and associated bodies: new insights into principles of nuclear structure and function
    2016
    Co-Authors: Garry T. Morgan
    Abstract:

    The Lampbrush Chromosomes and assorted nuclear bodies of amphibian and avian oocytes provide uniquely advantageous and amenable experimental material for cell biologists to study the structure and function of the eukaryotic nucleus, and in particular to address the processes of nuclear gene expression. Recent ¢ndings discussed here include the molecular analysis of the actively elongating RNA polymerase complexes associated with Lampbrush Chromosome loops and of the association between loop nascent transcripts and RNA processing components. In addition, several types of Chromosome struc-ture that do not outwardly resemble simple extended loops and that may house novel nuclear functions have recently been studied in detail. Among these a type of chromosomal body that can also exist free in the oocyte nucleus, the Cajal body, has been shown to possess a range of characteristics that suggest it is involved in the assembly of macromolecular complexes required for gene expression. Homologous struc-tures have also been described in somatic nuclei. Fundamental aspects of the looped organization exhibited by Lampbrush as well as other Chromosomes have also been addressed, most notably by the application of a technique for de-novo Chromosome assembly

  • Localized co-transcriptional recruitment of the multifunctional RNA-binding protein CELF1 by Lampbrush Chromosome transcription units
    Chromosome Research, 2007
    Co-Authors: Garry T. Morgan
    Abstract:

    The highly-extended transcription units of Lampbrush Chromosomes (LBCs) offer unique opportunities to study the co-transcriptional events occurring on nascent transcripts. Using LBCs from amphibian oocytes, I investigated whether CELF1, an RNA binding protein involved in the regulation of alternative splicing, mRNA stability and translation, is localized to active transcription units. Antibodies raised against mammalian (CUG-BP1) and amphibian (EDEN-BP) CELF1 were used to immunostain LBC spreads prepared from several species, including Xenopus laevis and the axolotl Ambystoma mexicanum . Up to about 50 separate LBC loci were convincingly immunostained and it was clear that CELF1 was present in the nascent RNPs of lateral loops. Furthermore, myc -tagged CUG-BP1 expressed in microinjected axolotl oocytes was specifically targeted to nascent transcripts of loops that recruit endogenous CELF1. In many active transcription units CELF1 was distinctly localized, being first recruited by nascent transcripts only far downstream of the transcription start site and remaining associated until the end of transcription. Overall it appears possible that the multiple functions of CELF1 in regulating posttranscriptional gene expression could all be predetermined during transcription by virtue of a region-specific binding to the nascent transcripts of target genes.

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