Zebrafish: chiasmata and interference

Genome ◽  
2006 ◽  
Vol 49 (3) ◽  
pp. 205-208 ◽  
Author(s):  
Peter B Moens
Keyword(s):  
Danio Rerio ◽  
Random Distribution ◽  
Immunofluorescence Microscopy ◽  
Centromeric Region ◽  
Genetic Recombination ◽  
Protein A ◽  
Mlh1 Foci ◽  
Distal Localization ◽  
Single Focus ◽  
Chiasma Interference

With immunofluorescence microscopy, the positions of centromeres and MLH1 (MutL homolog) foci representing the sites of presumptive chiasmata are shown for zebrafish (Danio rerio Hamilton 1822) synaptonemal complexes (SCs) in spermatocyte nuclei at meiotic prophase. Most SCs have a single focus and a few (7 of 140) have 2 chiasmata. MLH1 foci tend to be in the distal regions of SCs, with progressively fewer occurring towards the middle of the SCs. This non-random distribution suggests chiasma interference. Synaptic initiation, as well as replication protein A (RPA) foci at the chromosome ends, correlates with the distal localization of MLH1 foci. These observations may provide the physical basis for the reported limited genetic recombination in the centromeric region of androgenetic offspring of a male.Key words: zebrafish, recombination, chiasmata, interference, MLH1, RPA.

The time course and chromosomal localization of recombination-related proteins at meiosis in the mouse are compatible with models that can resolve the early DNA-DNA interactions without reciprocal recombination

2002 ◽  
Vol 115 (8) ◽  
pp. 1611-1622 ◽  
Author(s):  
Peter B. Moens ◽  
Nadine K. Kolas ◽  
Madalena Tarsounas ◽  
Edyta Marcon ◽  
Paula E. Cohen ◽  
...  
Keyword(s):  
Time Course ◽  
Protein A ◽  
Homology Search ◽  
Early Prophase ◽  
Dna Interactions ◽  
Recombination Nodules ◽  
Reciprocal Recombination ◽  
Recombination Protein ◽  
Mlh1 Foci ◽  
Related Proteins

During mouse meiosis, the early prophase RAD51/DMC1 recombination protein sites, which are associated with the chromosome cores and which serve as markers for ongoing DNA-DNA interactions, are in ten-fold excess of the eventual reciprocal recombinant events. Most, if not all, of these early interactions are eliminated as prophase progresses. The manner in which these sites are eliminated is the focus of this investigation. We report that these sites acquire replication protein A, RPA and the Escherichia coliMUTS homologue, MSH4p, and somewhat later the Bloom helicase, BLM, while simultaneously losing the RAD51/DMC1 component. Eventually the RPA component is also lost and BLM sites remain. At that time, the MUTL homologue, MLH1p,which is essential for reciprocal recombination in the mouse, appears in numbers and locations that correspond to the distribution of reciprocal recombination events. However, the MLH1 foci do not appear to coincide with the remaining BLM sites. The MLH1p is specifically localized to electron-microscope-defined recombination nodules. We consider the possibility that the homology-search RAD51/DMC1 complexes are involved in homologous chromosome synapsis but that most of these early DNA-DNA interactions are later resolved by the anti-recombination RPA/MSH4/BLM-topoisomerase complex,thereby preventing the formation of superfluous reciprocal recombinant events.

scholarly journals Recombination suppression by heterozygous Robertsonian chromosomes in the mouse.

Genetics ◽  
1993 ◽  
Vol 133 (3) ◽  
pp. 649-667
Author(s):  
M T Davisson ◽  
E C Akeson
Keyword(s):  
Genetic Markers ◽  
Centromeric Region ◽  
Genetic Recombination ◽  
Underlying Mechanism ◽  
Meiotic Pairing ◽  
Linkage Studies ◽  
Recombination Suppression ◽  
Telocentric Chromosomes ◽  
Mechanical Interference ◽  
Structural Differences

Abstract Robertsonian chromosomes are metacentric chromosomes formed by the joining of two telocentric chromosomes at their centromere ends. Many Robertsonian chromosomes of the mouse suppress genetic recombination near the centromere when heterozygous. We have analyzed genetic recombination and meiotic pairing in mice heterozygous for Robertsonian chromosomes and genetic markers to determine (1) the reason for this recombination suppression and (2) whether there are any consistent rules to predict which Robertsonian chromosomes will suppress recombination. Meiotic pairing was analyzed using synaptonemal complex preparations. Our data provide evidence that the underlying mechanism of recombination suppression is mechanical interference in meiotic pairing between Robertsonian chromosomes and their telocentric partners. The fact that recombination suppression is specific to individual Robertsonian chromosomes suggests that the pairing delay is caused by minor structural differences between the Robertsonian chromosomes and their telocentric homologs and that these differences arise during Robertsonian formation. Further understanding of this pairing delay is important for mouse mapping studies. In 10 mouse chromosomes (3, 4, 5, 6, 8, 9, 10, 11, 15 and 19) the distances from the centromeres to first markers may still be underestimated because they have been determined using only Robertsonian chromosomes. Our control linkage studies using C-band (heterochromatin) markers for the centromeric region provide improved estimates for the centromere-to-first-locus distance in mouse chromosomes 1, 2 and 16.

scholarly journals Purification and properties of transgelin: a transformation and shape change sensitive actin-gelling protein.

1993 ◽  
Vol 121 (5) ◽  
pp. 1065-1073 ◽  
Author(s):  
C Shapland ◽  
J J Hsuan ◽  
N F Totty ◽  
D Lawson
Keyword(s):  
Ionic Strength ◽  
Actin Filaments ◽  
Random Distribution ◽  
Shape Change ◽  
Protein A ◽  
Amino Acid Residues ◽  
Cell Permeabilization ◽  
Purification And Properties ◽  
Evolutionarily Conserved ◽  
Positively Charged

We have purified the transformation and shape change sensitive isoform of an actin associated polypeptide doublet previously described by us (Shapland, C., P. Lowings, and D. Lawson. 1988. J. Cell Biol. 107:153-161) and have shown that it is evolutionarily conserved as far back as yeast. The purified protein: (a) binds directly to actin filaments at a ratio of 1:6 actin monomers, with a binding constant (Ka) of approximately 7.5 x 10(5) M-1; and (b) causes actin filament gelation within 2 min. Although these activities are controlled by ionic strength (and may be mediated by positively charged amino acid residues) the molecule remains as a monomer irrespective of ionic conditions. EM reveals that the addition of this protein to actin filaments converts them from a loose, random distribution into a tangled, cross-linked meshwork within 1 min, and discrete tightly aggregated foci after 10 min. By use of an "add-back" cell permeabilization system we can rebind this molecule specifically to actin filaments in cells from which it has previously been removed. Since the protein is transformation sensitive and gels actin, we have named it transgelin.

scholarly journals Fluorescent Nanoparticle-Based Indirect Immunofluorescence Microscopy for Detection ofMycobacterium tuberculosis

2007 ◽  
Vol 2007 ◽  
pp. 1-9 ◽  
Author(s):  
Dilan Qin ◽  
Xiaoxiao He ◽  
Kemin Wang ◽  
Xiaojun Julia Zhao ◽  
Weihong Tan ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Silica Nanoparticles ◽  
Indirect Immunofluorescence ◽  
Rapid Detection ◽  
Immunofluorescence Microscopy ◽  
Protein A ◽  
Clinical Samples ◽  
Fluorescent Nanoparticles ◽  
Indirect Immunofluorescence Microscopy ◽  
Fluorescent Nanoparticle

A method of fluorescent nanoparticle-based indirect immunofluorescence microscopy (FNP-IIFM) was developed for the rapid detection ofMycobacterium tuberculosis. An anti-Mycobacterium tuberculosisantibody was used as primary antibody to recognizeMycobacterium tuberculosis, and then an antibody binding protein (Protein A) labeled with Tris(2,2-bipyridyl)dichlororuthenium(II) hexahydrate (RuBpy)-doped silica nanoparticles was used to generate fluorescent signal for microscopic examination. Prior to the detection, Protein A was immobilized on RuBpy-doped silica nanoparticles with a coverage of∼5.1×102molecules/nanoparticle. With this method,Mycobacterium tuberculosisin bacterial mixture as well as in spiked sputum was detected. The use of the fluorescent nanoparticles reveals amplified signal intensity and higher photostability than the direct use of conventional fluorescent dye as label. Our preliminary studies have demonstrated the potential application of the FNP-IIFM method for rapid detection ofMycobacterium tuberculosisin clinical samples.

scholarly journals Molecular Analysis of Sequence Heterogeneity among Genes Encoding Decorin Binding Proteins A and B of Borrelia burgdorferi Sensu Lato

1998 ◽  
Vol 66 (11) ◽  
pp. 5275-5285 ◽  
Author(s):  
William C. Roberts ◽  
Brian A. Mullikin ◽  
Raju Lathigra ◽  
Mark S. Hanson
Keyword(s):  
Borrelia Burgdorferi ◽  
Genetic Recombination ◽  
Protein A ◽  
Borrelia Burgdorferi Sensu Lato ◽  
Gene Products ◽  
Protective Epitope ◽  
Chromosomal Markers ◽  
Genes Encoding ◽  
Sequence Elements ◽  
Conserved Epitope

ABSTRACT Immunization of mice with Borrelia burgdorferi decorin binding protein A (DbpA), one of two gene products of thedbpBA locus, has been shown recently to confer protection against challenge. Hyperimmune DbpA antiserum killed a large number of B. burgdorferi sensu lato isolates of diverse phylogeny and origin, suggesting conservation of the protective epitope(s). In order to evaluate the heterogeneity of DbpA and DbpB and to facilitate defining the conserved epitope(s) of these antigens, the sequences of the dbpA genes from 29 B. burgdorferi sensu lato isolates and of the dbpBgenes from 15 B. burgdorferi sensu lato isolates were determined. The predicted DbpA sequences were fairly heterogeneous among the isolates (58.3 to 100% similarity), but DbpA sequences with the highest similarity tended to group into species previously defined by well-characterized chromosomal markers. In contrast, the predicted DbpB sequences were highly conserved (96.3 to 100% similarity). Substantial diversity in DbpA sequence was seen among isolates previously shown to be killed by antiserum against a single DbpA, suggesting that one or more conserved protective epitopes are composed of noncontiguous amino acids. The observation of individual dbpA alleles with sequence elements characteristic of more than one B. burgdorferi sensu lato species was consistent with a role for genetic recombination in the generation of dbpAdiversity.

PUMA1: a novel protein that associates with the centrosomes, spindle and centromeres in the nematode Parascaris

1998 ◽  
Vol 111 (6) ◽  
pp. 723-735
Author(s):  
M.R. Esteban ◽  
G. Giovinazzo ◽  
A. de la Hera ◽  
C. Goday
Keyword(s):  
Immunofluorescence Microscopy ◽  
Centromeric Region ◽  
Coiled Coil ◽  
Structural Features ◽  
Holocentric Chromosomes ◽  
Expression Library ◽  
Mitotic Apparatus ◽  
Reading Frame ◽  
Spindle Apparatus ◽  
Novel Protein

We have identified a 227 kDa spindle- and centromere-associated protein in Parascaris, designated PUMA1 (Parascaris univalens mitotic apparatus), using a monoclonal antibody (mAb403) generated against Parascaris embryonic extracts. PUMA1 distribution was studied by immunofluorescence microscopy in mitotic and meiotic Parascaris cells, where centromere organization differs greatly. In mitosis, PUMA1 associates throughout cell division with the centrosomes and kinetochore-microtubules, and it concentrates at the continuous centromere region of the holocentric chromosomes. PUMA1 also localizes to the spindle mid-zone region during anaphase and at the midbody during telophase. In meiosis, PUMA1 associates with the centrosomes and with the discrete centromeric regions lacking kinetochore structures. The analysis of colchicine-treated embryos indicated that the association of PUMA1 with the centromeric region depends on microtubule integrity. mAb403 also recognizes spindle components in Drosophila. A series of overlapping cDNAs encoding the gene were isolated from a Parascaris embryonic expression library. Analysis of the nucleotide sequence identified an open reading frame capable of encoding a protein of 227 kDa. Analysis of the protein sequence indicated that PUMA1 is predicted to be a coiled-coil protein containing a large central alpha-helical domain flanked by nonhelical terminal domains. The structural features and cellular distribution of PUMA1 suggest that it may play a role in the organization of the spindle apparatus and in its interaction with the centromere in Parascaris.

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