Recombination nodules and chiasma localization in two orthoptera

Chromosoma ◽  
1986 ◽  
Vol 93 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Cecilia Bernelot-Moens ◽  
Peter B. Moens
Keyword(s):  
Recombination Nodules ◽  
Chiasma Localization

scholarly journals Meiosis in Mesostoma ehrenbergii ehrenbergii. IV. Recombination nodules in spermatocytes and a test of the correspondence of late recombination nodules and chiasmata.

Genetics ◽  
1989 ◽  
Vol 121 (2) ◽  
pp. 255-262
Author(s):  
J A Croft ◽  
G H Jones
Keyword(s):  
Three Dimensional ◽  
Chiasma Formation ◽  
Ultrastructural Level ◽  
Male Meiosis ◽  
Light Microscope Level ◽  
Recombination Nodules ◽  
Chiasma Localization ◽  
Dimensional Reconstruction ◽  
Electron Microscopical ◽  
Metaphase I

Abstract Male meiosis in Mesostoma ehrenbergii ehrenbergii (2x = 10) is characterized by extreme restriction of chiasma formation; 3 pairs of chromosomes form bivalents at metaphase I which are associated by single very distally localized chiasma, while two pairs of chromosomes remain as unpaired univalents. Electron microscopical three-dimensional reconstruction analysis of serial sections has been applied to 20 pachytene spermatocyte nuclei. In each nucleus three short stretches of synaptonemal complex (SC) were found, confined to a localized branched lobe of the nucleus, confirming the findings of an earlier study. The majority of reconstructed nuclei show that each of the three SC segments has a single prominent recombination nodule ("late" RN) associated with it. Late RNs in this system therefore show an excellent correspondence with metaphase I chiasmata, in contrast to a previous report. M.e. ehrenbergii is therefore not an exception to the hypothesis that meiotic exchange requires a functional late RN. A few nuclei had two, one or no RNs; these presumably represent nuclei that are not at the stage of maximum RN presence. Although M. e. ehrenbergii shows pronounced chiasma localization at the light microscope level, at the ultrastructural level RNs are widely distributed along the 5-10 microns of SC formed in each bivalent, indicating that genetic exchange are not restricted to particular localized sites but occur at a large number of DNA sequence.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

Integrating Genetic Linkage Maps With Pachytene Chromosome Structure in Maize

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1923-1933 ◽  
Author(s):  
Lorinda K Anderson ◽  
Naser Salameh ◽  
Hank W Bass ◽  
Lisa C Harper ◽  
W Z Cande ◽  
...  
Keyword(s):  
Genetic Linkage ◽  
Chromosome Structure ◽  
Single Copy ◽  
Chromosome 9 ◽  
Linkage Maps ◽  
Cytogenetic Map ◽  
Recombination Nodules ◽  
Novel Approach ◽  
Genetic Linkage Maps ◽  
High Degree

Abstract Genetic linkage maps reveal the order of markers based on the frequency of recombination between markers during meiosis. Because the rate of recombination varies along chromosomes, it has been difficult to relate linkage maps to chromosome structure. Here we use cytological maps of crossing over based on recombination nodules (RNs) to predict the physical position of genetic markers on each of the 10 chromosomes of maize. This is possible because (1) all 10 maize chromosomes can be individually identified from spreads of synaptonemal complexes, (2) each RN corresponds to one crossover, and (3) the frequency of RNs on defined chromosomal segments can be converted to centimorgan values. We tested our predictions for chromosome 9 using seven genetically mapped, single-copy markers that were independently mapped on pachytene chromosomes using in situ hybridization. The correlation between predicted and observed locations was very strong (r2 = 0.996), indicating a virtual 1:1 correspondence. Thus, this new, high-resolution, cytogenetic map enables one to predict the chromosomal location of any genetically mapped marker in maize with a high degree of accuracy. This novel approach can be applied to other organisms as well.

scholarly journals Synaptonemal complex antigen location and conservation.

1987 ◽  
Vol 105 (1) ◽  
pp. 93-103 ◽  
Author(s):  
P B Moens ◽  
C Heyting ◽  
A J Dietrich ◽  
W van Raamsdonk ◽  
Q Chen
Keyword(s):  
Chromosome Pairing ◽  
Meiotic Prophase ◽  
Structural Integrity ◽  
Genetic Recombination ◽  
Positive Control ◽  
Western Blots ◽  
Lateral Element ◽  
Homologous Chromosomes ◽  
Recombination Nodules ◽  
Grain Distribution

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)

Synaptic behaviour and recombination nodules in the human XY pair

Genetica ◽  
1988 ◽  
Vol 77 (2) ◽  
pp. 149-158 ◽  
Author(s):  
Alberto J. Solari
Keyword(s):  
Recombination Nodules

scholarly journals Chiasma Localization in Four South African Grasshopper Species (Acridinae: Orthoptera)

Caryologia ◽  
1990 ◽  
Vol 43 (3-4) ◽  
pp. 257-265
Author(s):  
A. Fossey ◽  
H. Liebenberg
Keyword(s):  
South African ◽  
Grasshopper Species ◽  
Chiasma Localization

Changes in protein composition of meiotic nodules during mammalian meiosis

1998 ◽  
Vol 111 (4) ◽  
pp. 413-423 ◽  
Author(s):  
A.W. Plug ◽  
A.H. Peters ◽  
K.S. Keegan ◽  
M.F. Hoekstra ◽  
P. de Boer ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Protein A ◽  
Reca Protein ◽  
Protein Composition ◽  
Homologous Chromosomes ◽  
E Coli ◽  
Recombination Nodules ◽  
Chromosome Synapsis ◽  
Repair Protein ◽  
Mismatch Repair Protein

Homologous chromosome synapsis and meiotic recombination are facilitated by several meiosis-specific structures: the synaptonemal complex (SC), and two types of meiotic nodules: (1) early meiotic nodules (MNs), also called zygotene nodules or early recombination nodules, and (2) late recombination nodules (RNs). The former are thought to be nucleoprotein complexes involved in the check for homology preceding, or accompanying synapsis, while the latter have been shown to be involved in reciprocal recombination. We have examined by immunocytochemistry the meiotic localization of a series of proteins at sites along the asynapsed axial elements prior to homologous synapsis and at sites along the SCs following synapsis. Several of the proteins examined have been implicated in repair/recombination and include RAD51, a mammalian homolog of the Escherichia coli RecA protein; Replication Protein-A (RPA), a single-strand DNA binding protein; and MLH1, a mismatch repair protein which is a homolog of the E. coli MutL protein. In addition two proteins were examined that have been implicated in meiotic checkpoints: ATM, the protein mutated in the human disease Ataxia Telangiectasia, and ATR, another member of the same family of PIK kinases. We present evidence that these proteins are all components of meiotic nodules and document changes in protein composition of these structures during zygonema and pachynema of meiotic prophase in mouse spermatocytes. These studies support the supposition that a subset of MNs are converted into RNs. However, our data also demonstrate changes in protein composition within the context of early MNs, suggesting a differentiation of these nodules during the process of synapsis. The same changes in protein composition occurred on both the normal X axis, which has no homologous pairing partner in spermatocytes, and on the axes of aberrant chromosomes that nonhomologously synapse during synaptic adjustment. These findings suggest that DNA sequences associated with MNs still must undergo an obligatory processing, even in the absence of interactions between homologous chromosomes.

The Form of Bivalent Chromosomes in Newt Oocytes at First Metaphase of Meiosis

1963 ◽  
Vol s3-104 (66) ◽  
pp. 281-295
Author(s):  
I. D. WATSON ◽  
H. G. CALLAN
Keyword(s):  
Genetic Recombination ◽  
Great Majority ◽  
Meiotic Metaphase ◽  
Gene Products ◽  
Lampbrush Chromosomes ◽  
Female Sex ◽  
Chiasma Localization

Lampbrush chromosomes in the ovarian oocytes of newts are associated as bivalents. Some connexions between lampbrush chromosomes are chiasmata; others are known to be fusions of gene products; yet others, namely reflected, centromere, and telomere fusions, do not appear to be due simply to the fusion of gene products. Whether chiasmata are involved in reflected, centromere, and telomere fusions cannot be decided from examination of the chromosomes at the lampbrush stage. Bivalents from oocytes at first meiotic metaphase were therefore studied. The oocytes of newts reach first meiotic metaphase after ovulation, whilst they are free in the coelome. Reflected, centromere, and the great majority of telomere fusions do not persist to first meiotic metaphase: thus chiasmata are not involved in them. In oocyte bivalents of Triturus helveticus chiasmata are not restricted in their distribution, whereas in spermatocyte bivalents of this species chiasmata are proterminally localized. In oocyte bivalents of 3 subspecies of T. cristatus chiasmata are procentrically localized, whereas in spermatocyte bivalents of these subspecies chiasmata are not restricted in their distribution. Thus in T. helveticus meiosis in the female sex is mainly responsible for genetic recombination, whereas in T. cristatus the situation is reversed. We conclude that to base genetical and evolutionary inferences on information drawn from the meiosis of one sex only is unjustified, and we doubt the validity of the claim that chiasma localization has arisen so as to restrict genetic recombination.

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.

Sign in / Sign up

Export Citation Format

Share Document