HSP70-2 is required for desynapsis of synaptonemal complexes during meiotic prophase in juvenile and adult mouse spermatocytes

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4595-4603 ◽  
Author(s):  
D.J. Dix ◽  
J.W. Allen ◽  
B.W. Collins ◽  
P. Poorman-Allen ◽  
C. Mori ◽  
...  
Keyword(s):  
Meiotic Prophase ◽  
Spermatogenic Cells ◽  
Targeted Disruption ◽  
Late Pachytene ◽  
Homologous Chromosomes ◽  
Synaptonemal Complexes ◽  
Tissue Sections ◽  
Adult Mice ◽  
Pachytene Spermatocytes ◽  
Prophase Of Meiosis

Spermatogenic cells synthesize a unique 70-kDa heat shock protein (HSP70-2) during prophase of meiosis I, and targeted disruption of the Hsp70-2 gene has shown that this protein is required for spermatogenic cell differentiation in adult mice. HSP70-2 is associated with synaptonemal complexes formed between paired homologous chromosomes during meiotic prophase. The present study focuses on the nearly synchronous first wave of spermatogenesis in 12- to 28-day old juvenile mice to determine more precisely when HSP70-2 is required and what meiotic processes are affected by its absence. Spermatogenesis in homozygous mutant mice (Hsp70-2[−/−]) proceeded normally until day 15 when increasing numbers of pachytene spermatocytes became apoptotic and differentiation of cells beyond the pachytene stage began to falter. Synaptonemal complexes assembled in Hsp70-2(−/−) mice and spermatocytes developed through the final pachytene substage. However, synaptonemal complexes failed to desynapse and normal diplotene spermatocytes were not observed. Metaphase spermatocytes were not seen in tissue sections from testes of Hsp70-2(−/−) mice, and expression of mRNAs and antigens characteristic of late pachytene spermatocytes (e.g., cyclin A1) and development of spermatids did not occur. Thus, HSP70-2 is required for synaptonemal complex desynapsis, and its absence severely impairs the transition of spermatogenic cells through the late meiotic stages and results in apoptosis beginning with the first wave of germ cell development in juvenile mice.

Synapsis in grasshopper bivalents heterozygous for centric shifts

Genome ◽  
1995 ◽  
Vol 38 (3) ◽  
pp. 616-622 ◽  
Author(s):  
A. L. del Cerro ◽  
J. L. Santos
Keyword(s):  
Chiasma Formation ◽  
The Other ◽  
Homologous Chromosomes ◽  
Synaptonemal Complexes ◽  
Chiasma Distribution ◽  
Centric Shift ◽  
Heterochromatin Polymorphism ◽  
Pachytene Spermatocytes ◽  
Surface Spread ◽  
Surface Spreading

Analysis of surface-spread synaptonemal complexes of zygotene and pachytene spermatocytes was carried out on centric-shift heterozygotes of grasshoppers. These rearrangements affected the M7 chromosome in Chorthippus vagans and the M6 and S8 chromosomes in Chorthippus apricarius. The shifts in the latter two chromosomes were also associated with C-heterochromatin variations between homologous chromosomes. Rearranged chromosomes proceeded directly to heterosynapsis without an apparent intervening homosynaptic phase in M7 bivalents of Ch. vagans and M6 bivalents of Ch. apricarius. In the latter case, axial equalization of the heterochromatin polymorphism was also achieved. On the other hand, asynapsis of the intercentromeric regions throughout pachytene was the rule in the centric shift involving the S8 chromosome of Ch. apricarius. In the three cases analysed, the production of unbalanced gametes in the heterozygotes is precluded either by the lack of chiasma formation in heterosynapsed rearranged segments or by the lack of pairing between such segments. Chiasmata were limited to the homologous regions of the heteromorphic bivalents.Key words: synapsis, surface spreading, centric shift, chiasma distribution, meiosis.

Presence of abnormal synaptonemal complexes in heterothallic species of Neurospora

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 697-709 ◽  
Author(s):  
Maja Bojko
Keyword(s):  
Synaptonemal Complex ◽  
Meiotic Prophase ◽  
Low Frequency ◽  
Chiasma Formation ◽  
Lateral Component ◽  
Late Pachytene ◽  
Synaptonemal Complexes ◽  
Neurospora Intermedia ◽  
Heterothallic Species ◽  
Type Strains

Synaptonemal complex abnormalities are frequent in reconstructed meiotic prophase nuclei of Neurospora crassa and Neurospora intermedia. Three kinds of synaptonemal complex anomalies were seen: lateral component splits, lateral component junctions, and multiple complexes. The anomalies apparently are formed during or after the pairing process, as they were not seen in the largely unpaired early zygotene chromosomes. Their presence at all the other substages from mid-zygotene to late pachytene indicates that they are not eliminated before the synaptonemal complex decomposes at diplotene. Abnormal synaptonemal complexes were seen in all 19 crosses of N. crassa and N. intermedia that were examined, including matings between standard laboratory strains, inversions, Spore killers, and strains collected from nature. The frequency of affected nuclei and degree of abnormality within a nucleus varied in different matings. No abnormalities were present in the homothallic species Neurospora africana and Neurospora terricola. Structural chromosome aberrations, introgression, and heterozygosity have been eliminated as causes for pairing disorder. The abnormal synaptonemal complexes seemingly do not interfere with normal ascus development and ascospore formation. The affected nuclei are not aborted during meiotic prophase, nor are they eliminated by abortion of mature asci. The abnormal meiocytes do not lead to aneuploidy, as judged by the low frequency of white ascospores in crosses between wild type strains that have many abnormalities. Thus, the abnormal synatonemal complexes do not appear to prevent chiasma formation between homologues.Key words: Neurospora, meiosis, synaptonemal complex.

HUMAN MALE MEIOSIS: CHROMOSOME BEHAVIOUR AT PRE-MEIOTIC AND MEIOTIC STAGES OF SPERMATOGENESIS

1971 ◽  
Vol 13 (3) ◽  
pp. 536-549 ◽  
Author(s):  
Alan McDermott
Keyword(s):  
Metaphase Chromosome ◽  
Meiotic Prophase ◽  
Male Meiosis ◽  
Chromosome Behaviour ◽  
Late Pachytene ◽  
Homologous Chromosomes ◽  
Human Male ◽  
Spermatogonial Metaphase

Normal testicular material was obtained from 53 men. The morphology and behaviour of the chromosomes during pre-meiotic and meiotic stages of spermatogenesis are described in detail. Three types of spermatogonial metaphase chromosome have been identified; they are thought to be from spermatogonia of different generations. Homologous chromosomes appear to be paired at the beginning of spermatogonial prophase, and at the onset of the meiotic prophase (leptotene). Bivalents assume a "lampbrush" appearance during mid- to late pachytene.

Synaptonemal complexes in the mosquito Culex quinquefasciatus

1978 ◽  
Vol 36 (2) ◽  
pp. 212-213
Author(s):  
Annelise Fiil
Keyword(s):  
Nuclear Membrane ◽  
Culex Quinquefasciatus ◽  
Meiotic Prophase ◽  
Crossing Over ◽  
Serial Sections ◽  
Homologous Chromosomes ◽  
Synaptonemal Complexes ◽  
Meiosis I

The presence of synaptonemal complexes between the paired homologous chromosomes at meiotic prophase is a prerequisite for meiotic crossing over, and it may be important for the regular disjunctions of the chromosomes at meiosis I (Moses, 1968; Westergaard and von Wettstein, 1972; Gillies, 1975). Reconstructions of nuclei during zygotene and pachytene have shown that the ends of the synaptonemal complexes in many organisms are attached to the nuclear membrane, often in a polarized fashion (Moens, 1969; Rasmussen, 1976); such a bouquet arrangement of the chromosomes is found in Culex.Materials and MethodsOvaries from Culex quinquefasciatus were fixed in glutaraldehyde, followed by 0s04, and embedded in Epon. The synaptonemal complexes were reconstructed from serial sections.Results and DiscussionCulex has 3 pairs of very long metacentric or slightly submetacentric chromosomes which during pachytene loop around the nucleus several times (Fig. 1). The centromeric regions are fused, and the synaptonemal complexes do not continue through the structure.

scholarly journals Gene Conversion of Major Histocompatibility Complex Genes in the Mouse Spermatogenesis is a Premeiotic Event

1997 ◽  
Vol 8 (12) ◽  
pp. 2511-2517 ◽  
Author(s):  
Kari Högstrand ◽  
Jan Böhme
Keyword(s):  
Major Histocompatibility Complex ◽  
Gene Conversion ◽  
Molecular Genetic ◽  
Spermatogenic Cells ◽  
Major Histocompatibility ◽  
Adult Mice ◽  
Histocompatibility Complex ◽  
Specific Fragment ◽  
Pachytene Spermatocytes ◽  
Old Mice

The molecular genetic mechanism of gene conversion in higher eukaryotes remains unknown. We find it of considerable interest to determine when during spermatogenesis gene conversion occurs. We have therefore purified pachytene spermatocytes and haploid spermatocytes from adult mice and analyzed these fractions for the presence of gene conversion products resulting from the transfer between the major histocompatibility complex class II genes Ebd and Abk in a polymerase chain reaction assay. We have further isolated spermatogenic cells from prepubescent mice and analyzed them for the presence of the same gene conversion products. We can detect gene conversion products in testis cells as early as in 8-d-old mice where the only existing spermatogenic cells are spermatogonia. The frequency of gene conversion products remains the same as the cells reach meiosis in 18-d-old mice, and is unchanged after meiosis is completed in haploid spermatocytes. Gene conversion of this specific fragment therefore appears to be a premeiotic event and, consequently, relies on genetic mechanisms other than normal meiotic recombination.

The Fine Structure of Meiotic Chromosome Pairing in Natural and Artificial Lilium Polyploids

1970 ◽  
Vol 7 (1) ◽  
pp. 55-63
Author(s):  
P. B. MOENS
Keyword(s):  
Fine Structure ◽  
Chromosome Pairing ◽  
Meiotic Prophase ◽  
Meiotic Chromosome ◽  
Lilium Longiflorum ◽  
Structural Level ◽  
Hereditary Material ◽  
Homologous Chromosomes ◽  
Synaptonemal Complexes ◽  
Meiotic Chromosome Pairing

In the autotetraploid Lilium longiflorum (4n = 48), there are 12 sets of 4 homologous chromosomes. Within each set of 4 homologues, switches of pairing partners and crossovers occur at meiotic prophase. At the fine-structural level, the behaviour of the chromosomes is reflected in the switches between the axial cores of the homologous chromosomes. The normal synaptonemal complexes of the autotetraploid are compared with the complexes of the allotriploid L. tigrinum, which have synaptonemal complexes with abnormal lateral elements. The possibility that the deformed lateral elements are the products of heteromorphisms between‘homologues’ is explored in the discussion. The observations on the chromosome cores are interpreted as support for the notion that the cores may be associated with the recombinationally active hereditary material during meiotic prophase.

Follistatin-like immunoreactivity in the cytoplasm and nucleus of spermatogenic cells in the rat

1997 ◽  
pp. 523-529 ◽  
Author(s):  
K Ogawa ◽  
O Hashimoto ◽  
M Kurohmaru ◽  
T Mizutani ◽  
H Sugino ◽  
...  
Keyword(s):  
Spermatogenic Cells ◽  
Related Protein ◽  
Nuclear Condensation ◽  
Adult Rats ◽  
Late Pachytene ◽  
Rat Testis ◽  
Stage Of Development ◽  
Reducing Conditions ◽  
Sds Page ◽  
Pachytene Spermatocytes

Immunohistochemistry using an antiserum raised against the synthetic follistatin peptide (residues 123-134) was used, in the present study, to detect the stage-specific appearance of immunoreactive follistatin in the rat testis. Follistatin immunoreactivity was not found in Sertoli and Leydig cells, while it was clearly detected in spermatogenic cells. Follistatin-like immunoreactivity was detected in the cytoplasm and nucleus of late pachytene spermatocytes. Although the reaction in the cytoplasm disappeared after meiosis, it continued to be intense in the nucleus from pachytene spermatocytes to round spermatids. This finding indicated that follistatin or its closely related peptide produced in late pachytene spermatocytes migrates from the cytoplasm to the nucleus. We subjected rat testis homogenate to affinity chromatography on a sulfate-cellulofine and anti-follistatin Cys (123-134)-Affi-Gel Hz column followed by reverse-phase HPLC and analyzed the resulting fractions by Western blotting using follistatin antiserum. Three major bands at 57, 45 and 39 kDa or four bands at 52, 44, 39 and 34 kDa were detected in crude preparations from rat testis homogenate, under reducing or non-reducing SDS-PAGE respectively. The protein from rat testis, which was recognized by anti-follistatin (123-134) antiserum, exhibited a characteristic pattern for follistatin on SDS-PAGE, i.e. slower migration under reducing conditions than under non-reducing conditions, suggesting that it was follistatin or its closely related protein. Follistatin or its closely related protein may be a stage-specific modulator of spermatogenesis. Since follistatin-like immunoreactivity was not found in oocytes in any stage of development from embryonic to adult rats, it may act in an event specific to spermatogenesis, such as nuclear condensation.

scholarly journals Lateral Elements Inside Synaptonemal Complex-Like Polycomplexes in ndt80 Mutants of Yeast Bind DNA

Genetics ◽  
2003 ◽  
Vol 163 (2) ◽  
pp. 539-544 ◽  
Author(s):  
Hasanuzzaman Bhuiyan ◽  
Gunilla Dahlfors ◽  
Karin Schmekel
Keyword(s):  
In Situ Hybridization ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Immunoelectron Microscopy ◽  
Meiotic Prophase ◽  
Lateral Element ◽  
Homologous Chromosomes ◽  
Meiotic Prophase I ◽  
Dna Antibodies

Abstract The synaptonemal complex (SC) keeps the synapsed homologous chromosomes together during pachytene in meiotic prophase I. Structures that resemble stacks of SCs, polycomplexes, are sometimes found before or after pachytene. We have investigated ndt80 mutants of yeast, which arrest in pachytene. SCs appear normal in spread chromosome preparations, but are only occasionally found in intact nuclei examined in the electron microscope. Instead, large polycomplexes occur in almost every ndt80 mutant nucleus. Immunoelectron microscopy using DNA antibodies show strong preferential labeling to the lateral element parts of the polycomplexes. In situ hybridization using chromosome-specific probes confirms that the chromosomes in ndt80 mutants are paired and attached to the SCs. Our results suggest that polycomplexes can be involved in binding of chromosomes and possibly also in synapsis.

scholarly journals Dynamics of intracellular calcium induced by lactate and glucose in rat pachytene spermatocytes and round spermatids

Reproduction ◽  
2002 ◽  
pp. 701-710 ◽  
Author(s):  
JG Reyes ◽  
E Herrera ◽  
L Lobos ◽  
K Salas ◽  
N Lagos ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Carbohydrate Metabolism ◽  
Adenine Nucleotides ◽  
Differential Modulation ◽  
Glycolytic Metabolism ◽  
Spermatogenic Cells ◽  
Lactate Metabolism ◽  
The Media ◽  
Hexose Phosphorylation ◽  
Pachytene Spermatocytes

Glycolytic metabolism in meiotic and post-meiotic spermatogenic cells shows differentiation-related changes. The developmental and physiological significance of these metabolic changes is not known. The aim of the present study was to test the hypothesis that glucose and lactate metabolism can modulate intracellular calcium [Ca2+](i) in spermatogenic cells in an opposing and dynamic manner. Fluorescent probes were used to measure [Ca2+](i) and pH(i), and HPLC was used to measure intracellular adenine nucleotides and mitochondrial sensing of ATP turnover. [Ca2+](i) in pachytene spermatocytes and round spermatids was modulated by changes in lactate and glucose concentrations in the media. The kinetics and magnitude of the [Ca2+](i) changes induced by lactate and glucose were different in meiotic and post-meiotic spermatogenic cells. The presence of glucose in the medium induced a decrease in pH(i) in spermatogenic cells. This glucose-induced pH(i) decrease occurred later than the changes in [Ca2+](i), which were also observed when the pH(i) decrease was inhibited, indicating that the glucose-induced [Ca2+](i) increase was not a consequence of pH(i) changes. Hexose phosphorylation in glycolysis was part of the mechanism by which glucose metabolism induced a [Ca2+](i) increase in spermatogenic cells. The sensitivity of [Ca2+](i) to carbohydrate metabolism was higher in round spermatids than in pachytene spermatocytes. Thus, differentiation-related changes in carbohydrate metabolism in spermatogenic cells determine a dynamic and differential modulation of their [Ca2+](i) by glucose and lactate, two substrates secreted by the Sertoli cells.

An Ultrastructural and Radioautographic Study of Early Oogenesis in the Toad Xenopus Laevis

1973 ◽  
Vol 12 (1) ◽  
pp. 71-93
Author(s):  
LESLEY WATSON COGGINS
Keyword(s):  
Electron Microscope ◽  
Xenopus Laevis ◽  
Thymidine Incorporation ◽  
Ultrastructural Level ◽  
Extrachromosomal Dna ◽  
Late Pachytene ◽  
Synaptonemal Complexes ◽  
Round Nucleus ◽  
A Cell ◽  
Major Period

Early oogenesis in the toad Xenopus laevis has been investigated at the ultrastructural level, with particular reference to the formation of extrachromosomal DNA. Thymidine incorporation was localized by electron microscope radioautography. In oogonia, the nucleus is irregular in outline and may contain several nucleoli. Oocytes, from premeiotic interphase to late pachytene, are found in cell nests which are estimated to consist of about 16 cells each. Adjacent oocytes within a nest are connected by intercellular bridges and develop synchronously. Each premeiotic interphase-leptotene oocyte has a round nucleus which contains one or two centrally located, spherical nucleoli. Electron-microscope radioautography showed that all nuclei in a cell nest incorporate thymidine synchronously during premeiotic S-phase. In zygotene oocytes, axial cores and synaptonemal complexes are observed in the nucleus and abut against the inner nuclear membrane in the region nearest the centre of the cell nest. The nucleolus is still more-or-less round in outline, but is asymmetrically positioned in the nucleus. It lies near the nuclear envelope on the side of the nucleus furthest away from the attachment of the chromosome ends, that is, nearest the outside of the cell nest. Each nucleolus is surrounded by a fibrillar ‘halo’ of nucleolus-associated chromatin into which a low level of thymidine incorporation occurs during zygotene. This is thought to represent the start of the major period of amplification of the ribosomal DNA. Pachytene is characterized by the presence of synaptonemal complexes in the nucleus. The nucleolus becomes very irregular in outline. The fibrillar area around it, which represents the extrachromosomal DNA, increases in size and thymidine is incorporated over the whole of this region. In late pachytene, many small fibrogranular bodies, the multiple nucleoli, are formed in it. The members of a cell nest become separated from one another at this time and begin to develop asynchronously. In diplotene, synaptonemal complexes are no longer observed in the nucleus. The most prominent structures in the nucleus are now the multiple nucleoli, which increase greatly in number in early diplotene. A large increase in cytoplasmic volume occurs and the oocyte grows in size.

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