Chromosome organization in meiosis revealed by light microscope analysis of silver-stained cores

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 706-712 ◽  
Author(s):  
J. S. Rufas ◽  
J. Gimenez-Abian ◽  
J. A. Suja ◽  
C. Garcia De La Vega
Keyword(s):  
Key Words ◽  
Light Microscope ◽  
Meiotic Chromosome ◽  
Chiasma Formation ◽  
Silver Impregnation ◽  
Meiotic Metaphase ◽  
Chromosome Organization ◽  
Microscope Analysis ◽  
Impregnation Technique ◽  
Metaphase I

Three species of grasshoppers have been analyzed by means of a modified silver impregnation technique that reveals the presence of a chromatid core that identifies chiasmata at first meiotic metaphase. In terms of the behaviour of the chromatid core most of the configurations observed at diplotene with orcein are easily recognized in metaphase I silver-stained bivalents. Some "hidden" configurations, as well as simple chromatin associations, that do not appear to represent chiasmata have also been detected. The disposition and behaviour of the chromatid cores in metaphase I and anaphase I provide grounds to support a reorganization of half-bivalents between first and second division. Key words: chromatid core, meiotic chromosome organization, chiasma formation, insect cytogenetics.

scholarly journals Two types of highly ordered micro- and macrochromosome arrangement in metaphase plates of butterflies (Lepidoptera)

2019 ◽  
Vol 13 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Vladimir A. Lukhtanov
Keyword(s):  
Metaphase Plate ◽  
Meiotic Metaphase ◽  
Chromosome Organization ◽  
Cell Divisions ◽  
Size Groups ◽  
Metaphase I

In karyotype of many organisms, chromosomes form two distinct size groups: macrochromosomes and microchromosomes. During cell divisions, the position of the macro- and microchromosomes is often ordered within metaphase plate. In many reptiles, amphibians, birds, insects of the orthopteran family Tettigoniidae and in some plants, a so called “reptilian” type organization is found, with microchromosomes situated in the center of metaphase plate and with macrochromosomes situated at the periphery. An opposite, “lepidopteran” type is known in butterflies and moths (i.e. in the order Lepidoptera) and is characterized by macrochromosomes situated in the center and by microchromosomes situated at the periphery. The anomalous arrangement found in Lepidoptera was previously explained by holocentric organization of their chromosomes. Here I analyse the structure of meiotic metaphase I plates in ithomiine butterfly, Forbestraolivencia (H. Bates, 1862) (Nymphalidae, Danainae, Ithomiini) which has a clear “reptilian” organization, contrary to previous observations in Lepidoptera. In this species large bivalents (i.e. macrochromosomes) form a regular peripheral circle, whereas the minute bivalents (i.e. microchromosomes) occupy the center of this circle. The reasons and possible mechanisms resulting in two drastically different spatial chromosome organization in butterflies are discussed.

Meiotic chromosome structure. Kinetochores and chromatid cores in standard and B chromosomes of Arcyptera fusca (Orthoptera) revealed by silver staining

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 19-27 ◽  
Author(s):  
J. A. Suja ◽  
J. de la Torre ◽  
J. F. Giménez-Abián ◽  
C. García de la Vega ◽  
J. S. Rufas
Keyword(s):  
Meiotic Division ◽  
Silver Staining ◽  
Chromosome Structure ◽  
Sex Chromosome ◽  
Meiotic Chromosome ◽  
B Chromosomes ◽  
Chromosome Organization ◽  
Autosomal Bivalents ◽  
Metaphase I

The behaviour of two chromosome structures in silver-stained chromosomes was analyzed through the first meiotic division in spermatocytes of the acridoid species Arcyptera fusca. Results showed that at diakinesis kinetochores and chromatid cores are individualized while they associate in bivalents of metaphase I; only kinetochores and distal core spots associate in the sex chromosome. Metaphase I is characterized by morphological and localization changes of both kinetochores and cores which define the onset of anaphase I. These changes analyzed in both autosomes and in the sex chromosome allow us to distinguish among three different substages in metaphase I spermatocytes. B chromosomes may be present as univalents, bivalents, or trivalents. Metaphase I B univalents are characterized by separated cores except at their distal ends and individualized and flat sister kinetochores. At anaphase I sister kinetochores of lagging B chromatids remain connected through a silver-stained strand. The behaviour of cores and kinetochores of B bivalents is identical with that found in the autosomal bivalents. The differences in the morphology of kinetochores of every chromosome shown by B trivalents at metaphase I may be related to the balanced forces acting on the multivalent. The results show dramatic changes in chromosome organization of bivalents during metaphase I. These changes suggest that chromatid cores are not involved in the maintenance of bivalents. Moreover, the changes in morphology of kinetochores are independent of the stage of meiosis but correlate with the kind of division (amphitelic–syntelic) that chromosomes undergo.Key words: kinetochore, chromatid core, B chromosomes, meiosis, chromosome structure, silver staining.

A model of meiotic chromosome association in triploids

Genome ◽  
1989 ◽  
Vol 32 (1) ◽  
pp. 82-98 ◽  
Author(s):  
Charles F. Crane ◽  
David A. Sleper
Keyword(s):  
Genome Analysis ◽  
Meiotic Chromosome ◽  
A Priori ◽  
Chiasma Formation ◽  
Chromosome Association ◽  
Subsequent Formation ◽  
Meiotic Analysis ◽  
Partner Exchange ◽  
Translocation Heterozygosity ◽  
Metaphase I

A model was developed for chromosome association at meiotic metaphase I in triploids. Probabilities were estimated for each pachytene configuration and for subsequent formation of at least one chiasma in each combination of chromosome arms. Long and short arms were allowed to differ, but were related through an effective arm ratio so that the pattern of genomic affinity was the same for both arms. No other a priori assumptions were made about the pattern of genomic affinity. However, the usual assumptions of genome analysis were made including the following: identity of genomic-affinity pattern and chiasma frequency across homeologous groups, freedom from translocation heterozygosity, independence of chromosome arms, and absence of chiasma formation on both sides of a synaptic partner exchange within an arm. The model was statistically overparameterized and, therefore, had multiple solutions that yielded the same expected meiotic analysis. The range of these solutions can be found through repeated optimizations from randomly chosen starting values within the permitted ranges of the variables. It was convenient to express the optimized pattern of genomic affinity in terms of the proportions of metaphase I association due to each pairwise combination of genomes. Genomic affinity was analyzed in 16 triploid hybrids with the aid of the model.Key words: polyploidy, genome analysis, meiotic model.

The orientation of multivalents at meiotic metaphase I: a workshop report

Genome ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 612-620 ◽  
Author(s):  
J. Sybenga ◽  
G. K. Rickards
Keyword(s):  
Data Collection ◽  
Key Words ◽  
Meiotic Metaphase ◽  
Workshop Report ◽  
Key Words Meiosis ◽  
Analytical Procedures ◽  
First Contact ◽  
Final Orientation ◽  
Metaphase I

During a workshop with 13 participants, several aspects of multivalent orientation at meiotic (pro)metaphase were discussed in an attempt to resolve some of the most prominent controversies with respect to terminology, interpretation of observations, and the validity of hypotheses and theories. For several terms and concepts, descriptive definitions were formulated that are recommended for general use. In the analysis of the behaviour of the multivalent in meiosis preprometaphase shape and position as important factors in final orientation were discussed, as well as the first contact between spindle and kinetochores and the role of reorientation. Specific characteristics of different multivalents and expected frequencies of different orientation types were considered. Finally, a few remarks on data collection and analytical procedures were made Key words: meiosis, multivalents, orientation, workshop.

Metaphase I chiasmata in silver-stained cores of bivalents in grasshopper spermatocytes

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 235-238 ◽  
Author(s):  
J. L. Santos ◽  
G. Ciprés ◽  
J. R. Lacadena
Keyword(s):  
Key Words ◽  
Silver Staining ◽  
Chiasma Formation ◽  
Staining Procedure ◽  
Metaphase I

Chiasmata can clearly be observed in proteinaceous scaffold-like structures in condensed metaphase I bivalents of grasshopper spermatocytes by using a highly reproducible silver-staining procedure. Origin and significance of these structures are discussed and the possibility of analyzing several topics related with chiasma formation such as distribution, interference, terminalization, or terminal associations is pointed out. Key words: scaffold, chiasma, silver staining, terminalization, Chorthippus.

A model of meiotic chromosome association in tetraploids

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 691-707 ◽  
Author(s):  
Charles F. Crane ◽  
David A. Sleper
Keyword(s):  
Meiotic Chromosome ◽  
A Priori ◽  
Meiotic Metaphase ◽  
Chromosome Association ◽  
Preferential Pairing ◽  
Subsequent Formation ◽  
Meiotic Analysis ◽  
Basic Assumptions ◽  
The Relationship ◽  
Metaphase I

A model is constructed for chromosome association at meiotic metaphase I in tetraploids. Probabilities are estimated for each pachytene configuration and for subsequent formation of at least one chiasma in each combination of chromosome arms. Long and short arms can differ but are related through an effective arm ratio so as to maintain the same pattern of genomic affinity for both arms. No other a priori assumptions are made about the pattern of genomic affinity, but the same basic assumptions are made as in our preceding model for triploids. The model is statistically overparameterized and therefore has multiple solutions whose range can be found through repeated optimization from different starting points. In some cases the same expected meiotic analysis can arise from quite different genomic structures, which therefore cannot be distinguished on the basis of unmarked chromosomes. Solutions to the model are conveniently expressed in terms of the proportion of metaphase I association due to each pairwise combination of genomes. Interpretation of model solutions is also aided by the use of numerical indices that reflect closeness to 11 particular genomic structures or that reveal properties of the relationship among variables. The model differs from that of Kimber and Alonso in its handling of two chiasmatically bound arms in a randomly pairing homologous group, and frequently as well in its optimized pattern of genomic affinity upon application to 3:1 and 2:1:1 genomic structures. With the aid of the model, genomic affinity is analyzed in 20 individuals, representing hybrids, amphiploids, and species.Key words: polyploidy, genome analysis, preferential pairing, meiotic model.

A rapid silver-impregnation technique on ultra-thin sections for Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 242-243
Author(s):  
K. Chien ◽  
R.C. Heusser ◽  
M.L. Jones ◽  
R.L. Van de Velde
Keyword(s):  
Electron Microscopy ◽  
Silver Nitrate ◽  
Silver Impregnation ◽  
Sodium Borate ◽  
Renal Diseases ◽  
Distilled Water ◽  
Thin Sections ◽  
Impregnation Technique ◽  
Centrifuge Tube ◽  
Simplified Procedure

Silver impregnation techniques have been used for the demonstration of the complex carbohydrates in electron microscopy. However, the silver stains were believed to be technically sensitive and time consumming to perform. Currently, due to the need to more specifically evaluate immune complex for localization in certain renal diseases, a simplified procedure in conjunction with the use of the microwave has been developed and applied to renal and other biopsies. The procedure is as follows:Preparation of silver methenamine solution:1. 15ml graduated, clear polystyrene centrifuge tube (Falcon, No. 2099) was rinsed once with distilled water.2. 3% hexamethylene tetramine (methenamine) was added into the centrifuge tube to the 6ml mark.3. 3% silver nitrate was added slowly to the methenamine to the 7ml mark while agitating. (Solution will instantly turn milky in color and then clear rapidly by mixing. No precipitate should be formed).4. 2% sodium borate was added to the solution to the 8ml mark, mixed and centrifuged before use.

Synaptonemal complex proteins: occurrence, epitope mapping and chromosome disjunction

1994 ◽  
Vol 107 (10) ◽  
pp. 2749-2760 ◽  
Author(s):  
M.J. Dobson ◽  
R.E. Pearlman ◽  
A. Karaiskakis ◽  
B. Spyropoulos ◽  
P.B. Moens
Keyword(s):  
Synaptonemal Complex ◽  
Fusion Proteins ◽  
Epitope Mapping ◽  
Core Protein ◽  
Binding Capacity ◽  
Polyclonal Antibodies ◽  
Meiotic Chromosome ◽  
Immunogold Labelling ◽  
Chromosome Disjunction ◽  
Metaphase I

We have used polyclonal antibodies against fusion proteins produced from cDNA fragments of a meiotic chromosome core protein, Cor1, and a protein present only in the synapsed portions of the cores, Syn1, to detect the occurrence and the locations of these proteins in rodent meiotic prophase chromosomes. The 234 amino acid Cor1 protein is present in early unpaired cores, in the lateral domains of the synaptonemal complex and in the chromosome cores when they separate at diplotene. A novel observation showed the presence of Cor1 axial to the metaphase I chromosomes and substantial amounts of Cor1 in association with pairs of sister centromeres. The centromere-associated Cor1 protein becomes dissociated from the centromeres at anaphase II and it is not found in mitotic metaphase centromeres. The extended presence of Cor1 suggests that it may have a role in chromosome disjunction by fastening chiasmata at metaphase I and by joining sister kinetochores, which ensures co-segregation at anaphase I. Two-colour immunofluorescence of Cor1 and Syn1 demonstrates that synapsis between homologous cores is initiated at few sites but advances rapidly relative to the establishment of new initiation sites. If the rapid advance of synapsis deters additional initiation sites between pairs of homologues, it may provide a mechanism for positive recombination interference. Immunogold epitope mapping of antibodies to four Syn1 fusion proteins places the amino terminus of Syn1 towards the centre of the synaptonemal complex while the carboxyl terminus extends well into the lateral domain of the synaptonemal complex. The Syn1 fusion proteins have a non-specific DNA binding capacity. Immunogold labelling of Cor1 antigens indicates that the lateral domain of the synaptonemal complex is about twice as wide as the apparent width of lateral elements when stained with electron-dense metal ions. Electron microscopy of shadow-cast surface-spread SCs confirms the greater width of the lateral domain. The implication of these dimensions is that the proteins that comprise the synaptic domain overlap with the protein constituents of the lateral domains of the synaptonemal complex more than was apparent from earlier observations. This arrangement suggests that direct interactions might be expected between some of the synaptonemal complex proteins.

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