| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
RESEARCH |
Genetics and Biochemistry Branch, NIDDK, National Institutes of Health, 5 Memorial Drive, Bethesda, Maryland 20892, USA
Correspondence should be addressed to R D Camerini-Otero; Email: camerini{at}ncifcrf.gov
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResults and discussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and discussionReferences |
|---|
Apart from its catalytic function, Spo11 may play a structural role in chromosome pairing (Romanienko & Camerini-Otero 2000, Prieler et al. 2005). Pairing of homologous chromosomes, but not synapsis, was observed in yeast with a catalytically inactive Spo11 mutant, while complete deletion of the Spo11 gene eliminates this homolog pairing (Cha et al. 2000). Furthermore, in yeast, Spo11 foci were abundant in some pachytene cells where formation of DSBs are completed and during pachytene, most Spo11 foci touched or overlapped with Zip1 – the central element component of the SC (Prieler et al. 2005). Spo11 may also negatively regulate exit from the bouquet stage, a cell-wide regulatory transition accompanying global chromosome movements, via non-catalytic function in Sordaria macrospora at zygotene/pachytene stage (Storlazzi et al. 2003). In mouse, Spo11 localizes to discrete foci early in meiosis, which is consistent with catalytic function of Spo11 in leptotene, and later to the regions of homologous chromosome synapsis that suggested an additional structural role for Spo11 (Romanienko & Camerini-Otero 2000). Taken together, these findings indicate that Spo11 may have a role in the progression of meiotic prophase independent of DSBs.
Knockout of the mouse Spo11 prevents formation of DSBs and SC during meiosis and leads to the meiotic arrest of spermatocytes at zygotene (Baudat et al. 2000, Romanienko & Camerini-Otero 2000). The arrested cells undergo apoptosis. As a result, Spo11–/ –homozygous male mice are sterile and have small, underdeveloped testes. A growing body of information indicates that mouse knockouts of genes with many different functions in meiosis, such as Msh4 (DNA mismatch repair protein), Dmc1 (meiotic recombination and repair protein), Hop2 (proper homologous chromosome pairing protein), Sycp3 (structural component of the axial/lateral element of SC) and Mei1 (a possible partner of Spo11) have a similarly arrested meiotic phenotype (de Rooij & de Boer 2003, Petukhova et al. 2003). These mutant mice have spermatocytes that do not develop beyond zygotene and are sterile in the homozygous state (de Rooij & de Boer 2003, Petukhova et al. 2003). A common feature for all these mutant spermatocytes is the failure to synapse homologous chromosomes (Pittman et al. 1998, Yoshida et al. 1998, Kneitz et al. 2000, Yuan et al. 2000, Libby et al. 2002, 2003, Petukhova et al. 2003). It is not clear how this failure in chromosome synapsis leads to the arrest in meiosis and subsequent apoptosis. It might be the result of the action of a pachytene checkpoint (Roeder & Bailis 2000) as has been observed for budding yeast or the transcriptional silencing imposed at pachytene on unsynapsed meiotic chromosomes (Turner et al. 2005). The latter might be sufficient in its own. In other words, the transcriptional inactivation of genes essential for meiotic progression may precipitate meiotic arrest before pachytene in the absence of a checkpoint as such. A comparative analysis of gene expression in mutant and wild-type mouse testes may yield new information about the general mechanisms leading to meiotic arrest and uncover new genes, which participate in meiosis, meiotic checkpoint and spermatogenesis.
We used cDNA microarray analysis to measure gene expression levels in adult and juvenile Spo11–/ –testes. Differentially expressed genes were further characterized by their functional classification and by the tissue specificity of their expression. Analysis of gene expression of juvenile Spo11–/ –testes has allowed us to recognize genes whose expression depends on Spo11.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and discussionReferences |
|---|
Total RNA isolation
Testes were surgically removed from mice and stored at –80 °C until total RNA was isolated using a Trizol solution (Life Technologies). Total RNA then was treated with RNase-free DNase (Promega) at room temperature for 15 min. RNA concentration was determined by UV spectrophotometry and RNA integrity was confirmed using agarose gel electrophoresis. Total RNAs (10 µg) were used as templates in reverse transcription (RT) reactions.
Microarray procedures
Amino-allyl modified cDNA was synthesized using SuperScript II RNase H-RT (Invitrogen) oligo (dT) (Life Technologies) and amino-allyl modified dUTP (Sigma), followed by labeling with fluorescent dyes Cy3 or Cy5 (Amersham). Labeled products were purified with QIAquick PCR Purification Kit (Qiagen). The hybridizations were performed on glass slide microarrays Mouse NIA 15K (Keck Biotechnology Resource Lab, Yale University, New Haven, CT, USA) containing 15 000 mouse genes according to the manufacturer’s protocol. Microarray experiments were performed in quadruplicate with different mouse pairs and dye-reversed hybridizations. The chips were scanned using the GenePix 4000A scanner (Axon Instruments, Union City, CA, USA) and primary data were analyzed using the Genepix 3.0 software (Axon Instruments). Microarray data are available under the GEO accession numbers GSE1138
[NCBI GEO]
and GSE3436
[NCBI GEO]
.
Data analysis
Primary data were flagged using four default parameters set in the Genepix 3.0 program. For further analysis, the data were imported into Excel (Microsoft) and normalized by the Median Centering Method. We performed the statistical analysis using a modified t-test implemented in SAM software (http://www-stat.stanford.edu/~tibs/SAM/) (Tusher et al. 2001). We defined differentially expressed genes at a 1% false discovery rate confidence level and a cutoff for differential expression equal to 1.5 for juvenile Spo11–/ –and 2.0 for adult Spo11–/ –, juvenile wild-type microarray experiments and for analysis of testis specificity. Gene clustering was performed with the K-means method and a hierarchical clustering package based on the Pearson correlation coefficient, using the average linkage of the log2 ratio (Eisen et al. 1998).
To functionally characterize genes, expressed early and late in spermatogenesis, we used the gene ontology mining tool eGOn (www.egon.com), a web-based tool for mapping microarray data onto the gene ontology structure. We performed the Target–Master test, where a given gene set (the target gene list) was compared with the master list, contained all the genes printed on the slide. The total number of genes in the target list divided by the total number of genes in the master list was called the overall proportion. The Target–Master test determined gene ontology (GO) classes where the proportion of the number of genes in a target list divided by the number of genes in the master list is different from the overall proportion with P<0.05. A two-sided one sample binomial test was implemented.
Quantitative RT-PCR
For the 3'-most 500 bp of the full-length mRNA sequence primer pairs were designed using the web-based program Primer version 3.0 (Rozen & Skaletsky 2000) to yield a short (120–150 bp) PCR fragment with a melting temperature of about 60 °C. For each reaction, 1 µl of diluted cDNA (4 µg/ml) was mixed with 300 pmol of each primer in 25 µl (final volume) of SYBR Green Master Mix (Applied Biosystems, Foster City, CA, USA). RT-PCR was performed in an ABI 7000 (Applied Biosystems). All amplifications were run in triplicate.
|
Results and discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and discussionReferences |
|---|
). We found that about 4000 genes changed their expression in Spo11–/ –testes more than twofold (Fig. 1a). To validate the microarray data, we performed quantitative RT-PCR for selected genes (Fig. 1c). Differential expression ratios obtained by microarray analysis and quantitative RT-PCR were in qualitative agreement for all genes tested, although we found some quantitative differences.
|
These developmental abnormalities of Spo11–/ –testes can be verified by analyzing the expression levels of cell type-specific genes. Recently, Shima et al.(2004) defined genes that are expressed predominantly in spermatogonia, pachytene spermatocytes and rounded spermatids on a genome-wide scale. We calculated the average expression levels of genes from each cell type in our experiments (Table 1) and found that genes expressed in spermatocytes and spermatids have more than twofold lower expression level in Spo11–/ –adult testis on average. On the other hand, spermatogonia-expressed genes are slightly enriched.
|
, lanes S and W). The majority of the genes for those transcripts depleted in Spo11–/ –adult testis are also depleted in juvenile testis, and similarly enriched transcripts in Spo11–/ –are also enriched in juvenile testis. A cumulative analysis of genes expressed in individual cell populations of testis shows the same trends as for Spo11–/ –testis (Table 1
). The average level of transcripts of genes expressed in pachytene spermatocytes and rounded spermatids was at least twofold less in Spo11–/ –and juvenile testis when compared to adult wild-type testis (Table 1). Despite the almost identical expression pattern of transcripts in Spo11–/ –and juvenile testis, we found some interesting differences. These differences are discussed in detail later.
|
). We divided genes into nine clusters based on the similarity of their expression profiles as a function of time using K-means clustering. We found that transcripts that are more abundant in Spo11–/ –testis are associated with clusters of genes that reach their maximum of expression in testis before 14 days after birth (clusters 6, 7 and 8, see Fig. 2). The majority of transcripts depleted in Spo11–/ –testis increase their expression in testis on or after day 14 after birth (e.g. cluster 3). Therefore, in our microarray analysis, we can consider genes whose transcripts are enriched in Spo11–/ –testes as genes expressed in spermatogonia and early spermatocytes, while genes, whose transcripts are depleted in Spo11–/ –testis are expressed later in meiosis and spermatogenesis. We call the first group of genes, ‘early’ genes and the second group ‘late’ genes.
Functional characterization of ‘early’ and ‘late’ genes in the expression profile of Spo11–/ –adult and wild-type juvenile testis
To characterize those genes expressed early or late in spermatogenesis and to integrate expression specificity with functional annotation, we performed gene ontology mining using the web-based tool eGOn (www.egon.com). Differentially expressed genes were divided into six clusters based on their regulation pattern in either Spo11–/ –or juvenile testes (Fig. 3). Cluster 1 includes genes, whose transcripts are enriched only in Spo11–/ –testes; cluster 2 – common early genes; cluster 3 – early genes only in 15 day wild-type testes; cluster 4 – genes, whose transcripts are depleted only in Spo11–/ –testes; cluster 5 – common late genes and cluster 6 – genes expressed late only in juvenile testes (see Fig. 3). Although gene expression patterns in adult Spo11–/ –and juvenile wild-type testis have high similarity, there is a profound difference observed in the expression level of early genes. This difference is due to the apoptosis of arrested spermatocytes in Spo11–/ –testes and the enrichment in Spo11–/ –testes of Leydig cells that are the primary producers of steroid hormones in males. Therefore, the largest cluster for early genes (genes, whose transcripts are enriched only in Spo11–/ –testis) is over-represented with GO classes, such as steroid biosynthesis, fatty acid metabolism, proteolysis and peptidolysis, response to external stimuli, immune response and cytolysis (Table 2, Table 4 which can be viewed at: http://www.reproduction-online.org/supplemental/). The first cluster contains main intracellular effectors of apoptosis: caspases 9 and 6, Gadd45 g (growth arrest and DNA-damage-inducible 45 gamma) and the members of the Bcl-2 family of proteins that promote the mitochondria-dependent apoptotic pathway (Green & Kroemer 2004) (Fig. 3, Table 2, Table 4, which can be viewed at: http://www.reproduction-online.org/supplemental/). The appearance of cytolysis and immune response among over-represented GO classes reflects the intensive apoptosis, which occurs in adult Spo11–/ –testes.
|
|
, Table 4, which can be viewed at: http://www.reproduction-online.org/supplemental/). Smc1l1 (structural maintenance of chromosomes 1-like 1) and cell-cycle regulators such as Cdk5 (cyclin-dependent kinase 5), Ccna2 (cyclin A2) and Anapc4, 7 (anaphase promoting complex subunit 4 and 7) are in this cluster. Consistent with the fact that the normal development of spermatogenesis is accompanied by DNA repair and apoptosis, and corresponding genes are induced before or in early stage of meiosis, we find in cluster 2 Msh2 (DNA mismatch repair protein), Rad21 (DBSs repair protein), Casp3 (apoptosis related cysteine protease or caspase 3) and Pdcd8 (programmed cell death 8- apoptosis-inducing factor). Cluster 3 (early genes in 15 day wild-type testes only) show as a positive association with such GO classes as meiosis, cell proliferation, cell cycle and nuclear division. Some of the genes found in this cluster include Mlh3 (establishing and/or maintaining crossovers), Sycp1 (major structural protein of the central element in SC), Rad51 (eukaryotic RecA homolog); E2f6 (transcriptional regulation of various genes implicated in chromatin remodeling), Anapc1 (anaphase promoting complex subunit 1) and Dazl (translation regulator). The observation that these genes are highly expressed only in juvenile wild-type testis is consistent with the normal development of meiosis in juvenile wild-type testis (Table 4, which can be viewed at: http://www.reproduction-online.org/supplemental/). It is interesting to note that in contrast to Anapc4 and Anapc7, the Anapc1 (meiotic check point regulator) is induced only in 15-day wild-type testis and might be critical for the zygotene/ pachytene transition.
The difference between late genes in Spo11–/ –and juvenile testis is not as profound as the difference between early genes (Fig. 3). The majority of genes whose transcripts are depleted in both Spo11–/ –and juvenile testis belong to cluster 5 (common late genes). As expected, we found a positive association of genes from cluster 5 with processes that occur late in male meiosis and spermatogenesis. These GO classes include gametogenesis (Rad23b, Mea1, Zfp35, Tce1), meiosis (Tsga2, Hop2, Rpa1, Stag3), chromatin remodeling (Morf4l1, Brd6) and chromosome segregation (Ccnb2, Chc1, Cdc25A, Cdc25C) (Table 2, Table 4, which can be viewed at: http://www.reproduction-online.org/supplemental/).
The relatively small cluster 4 (gene transcripts depleted only in adult Spo11–/ –testis) is enriched with genes involved in mitotic cell cycle, covalent chromatin modification, transcription initiation and regulation of translational initiation (Table 2). We can speculate that the lack of expression of these genes was the consequence of the meiotic arrest and induction of apoptosis in Spo11–/ –testis. Interestingly, in this cluster, we find important meiotic recombination proteins involved in the processing of DSBs, such as Mre11 (a major DSB repair protein) and Brca2 (breast cancer 2). In a mutant Brca2–/ –mouse carrying a human BRCA2 transgene (the Brca2 null mutation is embryonic lethal for mice) spermatocytes undergo normal DSBs formation but fail to complete recombination and do not progress beyond zygotene (Sharan et al. 2004). In our study, the observed depletion of Brca2 could be a consequence of the absence of DSBs in Spo11 knockout testis.
The last cluster, cluster 6 contains late genes, whose transcripts are depleted only in 15-day wild-type testis and these genes are implicated in spermatogenesis, steroid biosynthesis and lipid metabolism. The presence of these last two categories reflects the incomplete establishment of hormone production in juvenile testis.
The majority of testis-specific genes are expressed in late stages of meiosis and spermatogenesis
To further characterize genes differentially expressed in Spo11–/ –adult testes, we determined the distribution of mouse testis-specific genes among early and late genes in the gene expression profiles of Spo11–/ –testes. We performed cDNA microarray analysis, where we compared gene expression in adult mouse testes to reference RNA. Reference RNA included samples of total RNA from 11 different mouse tissues. We classified genes as testis-specific, if their expression level in testes is at least twofold more than in reference RNA. K (K=9) means clustering of microarray data obtained from a comparison between Spo11–/ –and wild-type testes, and wild-type adult testes and reference RNA showed that 90% of testis-specific genes mapped to the cluster of genes expressed in the late stages of meiosis and spermatogenesis (Fig. 2, lanes S and T). This conclusion was also confirmed if we used the other criteria of testis specificity based on the abundance of clones in Unigene cDNA libraries and publicly available Affymetrix data of mouse gene expression in different tissues (Khil et al. 2004). We found only 10% of testis-specific genes in the ’early’ cluster of gene expression in Spo11 testis. In addition, GO analysis of testis-specific genes determined from a comparison of wild-type testes and reference RNA showed a statistically significant association with the same GO classes that were observed in cluster 5 (genes transcripts, depleted in both Spo11 –/ –adult and 15 days testis) (Fig. 2, Table 2).
The effect of Spo11 knockout on gene expression in the testes of juvenile mice
Previously, we found that the major effect of Spo11 knockout is the disruption of the normal development of testes. To focus on genes involved in meiosis I, we compared gene expression profiles of Spo11 –/ –and wild-type testes from 12- and 15-days mice. On day 12, most of wild-type spermatocytes (about 85%) are in leptotone/zygotene stages and at 15 days, they are entering pachytene (Goetz et al. 1984). Comparing Spo11–/ –and wild-type mice at this age may allow us to focus on genes expressed in early meiotic prophase I that are more clearly dependent on the formation of DSBs. These genes include those involved in meiotic recombination, homologous pairing, SC formation and meiotic checkpoints. The use of this relatively early time point helps to eliminate from the analysis, genes expressed in later stages of spermatogenesis and apoptotic genes that are induced in response to the meiotic arrest of Spo11–/ –spermatocytes.
Apart from a few genes, including Mnd1, the microarray analysis did not reveal any significant differences in gene expression between Spo11 KO and wild-type testis at 12 day of age (Table 5, which can be viewed at: http://www.reproduction-online.org/supplemental/). On day 15, we found that only 250 genes have changed their expression level more than 1.5-fold in Spo11–/ –compared to wild-type testis (Fig. 1b, Table 5 available online). First of all, this selection includes some genes critical for meiotic recombination (Table 3, Table 5 available online). Among them are Hop2, Brca2, Mnd1, FancG (Fanconi anemia (group G) (Yang et al. 2001, Petukhova et al. 2003, 2005, Chen et al. 2004, Gudmundsdottir & Ashworth 2004). According to a current model, Brca2 is involved in delivering Rad51 and Dmc1 to repair DSBs by initiating strand exchange (Gudmundsdottir & Ashworth 2004). In Spo11–/ –spermatocytes, programmed DSBs are not formed and this function of Brca2 would not be required. Indeed, we found a 1.5-fold depletion of Brca2 transcripts in juvenile Spo11–/ –testis. Furthermore, we observed a twofold decrease in the level of expression FancG transcripts in Spo11 –/ –spermatocytes. FancG protein is capable of binding to two separate sites in the Brca2 protein (Hussain et al. 2003). It is co-immunoprecipitated with Brca2 from human cells and co-localized in nuclear foci with both Brca2 and Rad51 following DNA damage with mitomycin C (Hussain et al. 2003). Without doubt, FancG protein also participates in meiosis because the FancG–/ –mice have germ cell defects and decreased fertility (Yang et al. 2001). One of the most interesting observations is a twofold decrease in the transcription level of Hop2, another abundant meiotic protein closely associated with the Dmc1 and Rad51 in meiosis (Petukhova et al. 2003, 2005, Chen et al. 2004). It has been shown in yeast and mice that the Mnd1/Hop2 heterodimeric protein complex is required for the homologous pairing of chromosomes during meiosis and that these proteins act by promoting Rad51 or Dmc1 activity during the formation of the first recombination intermediates in meiosis (Petukhova et al. 2003, 2005, Chen et al. 2004). The dramatic decrease in the expression of Hop2 in Spo11–/ –juvenile testes may be the reflection of the absence of DSBs and the lack of the need for Hop2 under these circumstances. We could not find a satisfactory explanation for increased transcription of Mnd1 in Spo11–/ –juvenile testes because the function of Mnd1, besides the role in forming a complex with Hop2 that stimulates Rad51 and Dmc1, is unclear.
|
). Therefore, our gene expression data support the conclusion of previous study that cohesin cores can form independently of DSB formation and homologous pairing in mice (James et al. 2002). Spo11–/ –spermatocytes are arrested at zygotene in meiotic prophase I. Little is known about the mechanisms of cell cycle control and checkpoint prior to pachytene. It is interesting in this regard that we found that the meiosis-specific Ccnb2 (cyclin B2) and the Cks2 (CDC28 protein kinase regulatory subunit 2) are twofold downregulated in 15-day Spo11–/ –testis. The Cks2 modulates substrate recognition by a Cdk1 that is part of the meiotic cell cycle regulatory complex Ccnb2/Cdk1 (Patra & Dunphy 1998, Spruck et al. 2003, Murray 2004). Although in Cks2-deficient mice, meiosis arrests at metaphase I (Spruck et al. 2003) and Ccnb2–/ –mice are fertile (the function of cyclin B2 is probably rescued by cyclin B1 (Ccnb1) (Brandeis et al. 1998), the cyclin B2 and Cks2 may be key components of the machinery that controls meiotic progression from zygotene to pachytene. Although cyclin B1 can substitute cyclin B2 and the expression level of cyclin B1 did not change in 15-day Spo11 testes, still Ccnb1/Cdk1 complex can be compromised by downregulation of the expression of some genes. Among them, we found calmodulin, a gene that can affect cyclinB1/Cdk1 (also known as Cdc2) through its partner, the testis-specific heat-shock protein Hsp70-2 (Zhu et al. 1997, Moriya et al. 2004). Hsp-70-2 deficient mice exhibit failed meiosis (Dix et al. 1996) and it has been suggested that Hsp-70-2 functions as a molecular chaperone for the Ccnb1/Cdk1 (Cdc2) complex (Zhu et al. 1997).
Among other genes that might play an essential role in meiotic progression, we can emphasize Ddx4, the mouse homologue of the Drosophila gene Vasa, that controls the initiation of translation (Carrera et al. 2000) and those expression is a twofold depleted in Spo11–/ –juvenile testes (Table 5, which can be viewed at: http://www.reproduction-online.org/supplemental/). The mouse Vasa transcript is bound by Dazl (Reynolds et al. 2005), and knockouts of either Dazl or Ddx4 lead to meiotic arrest of mouse spermatocytes at a zygotene-like stage similar to that found in the Spo11–/ –knockout (Tanaka et al. 2000, Saunders et al. 2003).
Other promising candidates potentially involved in meiotic checkpoint, meiotic recombination and SC formation may be found among the 53 genes with unknown function differentially expressed in juvenile Spo11–/ –testis. Based on the expression data obtained from the GEO profile database (http://www.ncbi.nlm.nih.gov/geo/), we determined that the majority of unknown genes downregulated in young Spo11–/ –testis increase their expression on day 14 after birth (Table 6 which can be viewed online at: http://www.reproduction-online.org/supplemental/). We found that some unknown proteins contain conserved domains involved in DNA recombination, microtubule-based process and regulation of developmental pathways (Table 6 available online).
In summary, microarray analysis of gene expression in adult Spo11–/ –testes reveals that the Spo11 mutation causes dramatic changes in the gene expression pattern of Spo11–/ –mouse testis. Spo11 knockout activates meiotic arrest in zygotene spermatocytes and, as a consequence, the disruption of spermatogenesis and normal testis development. Spo11–/ –testes are enriched with spermatogonia and spermatocytes in early stages of meiosis. Therefore, Spo11–/ –testes are a useful model for studies of gene expression in spermatogonia and early spermatocytes. Using the GO mining tool eGOn, we determined the relevant biological processes for genes expressed early and late in spermatogenesis. A comparative analysis of gene expression in juvenile Spo11–/ –mouse testes showed a dramatic decrease in the expression level of genes involved in meiotic recombination, meiotic checkpoints, but an absence of significant changes in the expression of genes encoding proteins for SC. This analysis also revealed about 50 genes of unknown function specifically induced or repressed in Spo11–/ –testes. Such genes are very likely to be specifically involved in meiosis and spermatogenesis and to be affected by disruption of the Spo11 gene. Studies of these novel proteins may shed a new light on our understanding of the function of Spo11 protein in meiosis and may help to find more partners of Spo11 in mammals.
|
Footnotes |
|---|
P J Romanienko is now at Developmental Biology Program, Mouse Genetics Core, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York 10021, USA
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResults and discussionReferences |
|---|
Baarends WM, van der Laan R & Grootegoed JA 2001 DNA repair mechanisms and gametogenesis. Reproduction 121 31–39.[Abstract]
Bannister LA & Schimenti JC 2004 Homologous recombinational repair proteins in mouse meiosis. Cytogenetic and Genome Research 107 191–200.[CrossRef][Web of Science][Medline]
Baudat F, Manova K, Yuen JP, Jasin M & Keeney S 2000 Chromosome synapsis defects and sexually dimorphic meiotic progression in mice lacking Spo11. Molecular Cell 6 989–998.[CrossRef][Web of Science][Medline]
Bishop DK, Park D, Xu L & Kleckner N 1992 DMC1: a meiosis-specific yeast homolog of E. coli recA required for recombination, synaptonemal complex formation, and cell cycle progression. Cell 69 439–456.[CrossRef][Web of Science][Medline]
Brandeis M, Rosewell I, Carrington M, Crompton T, Jacobs MA, Kirk J, Gannon J & Hunt T 1998 Cyclin B2-null mice develop normally and are fertile whereas cyclin B1-null mice die in utero. PNAS 95 4344–4349.
Carrera P, Johnstone O, Nakamura A, Casanova J, Jackle H & Lasko P 2000 VASA mediates translation through interaction with a Drosophila yIF2 homolog. Molecular Cell 5 181–187.[CrossRef][Web of Science][Medline]
Cha RS, Weiner BM, Keeney S, Dekker J & Kleckner N 2000 Progression of meiotic DNA replication is modulated by inter-chromosomal interaction proteins, negatively by Spo11p and positively by Rec8p. Genes and Development 14 493–503.
Chen YK, Leng CH, Olivares H, Lee MH, Chang YC, Kung WM, Ti SC, Lo YH, Wang AH, Chang CS et al. 2004 Heterodimeric complexes of Hop2 and Mnd1 function with Dmc1 to promote meiotic homolog juxtaposition and strand assimilation. PNAS 101 10572–10577.
de Rooij DG & de Boer P 2003 Specific arrests of spermatogenesis in genetically modified and mutant mice. Cytogenetic and Genome Research 103 267–276.[CrossRef][Web of Science][Medline]
Dernburg AF, McDonald K, Moulder G, Barstead R, Dresser M & Villeneuve AM 1998 Meiotic recombination in C. elegans initiates by a conserved mechanism and is dispensable for homologous chromosome synapsis. Cell 94 387–398.[CrossRef][Web of Science][Medline]
Dix DJ, Allen JW, Collins BW, Mori C, Nakamura N, Poorman-Allen P, Goulding EH & Eddy EM 1996 Targeted gene disruption of Hsp70-2 results in failed meiosis, germ cell apoptosis, and male infertility. PNAS 93 3264–3268.
Eisen MB, Spellman PT, Brown PO & Botstein D 1998 Cluster analysis and display of genome-wide expression patterns. PNAS 95 14863–14868.
Goetz P, Chandley A & Speed R 1984 Morphological and temporal sequence of meiotic prophase development at puberty in the male mouse. Journal of Cell Science 65 249–263.[Abstract]
Green DR & Kroemer G 2004 The pathophysiology of mitochondrial cell death. Science 305 626–629.
Grelon M, Vezon D, Gendrot G & Pelletier G 2001 AtSPO11-1 is necessary for efficient meiotic recombination in plants. EMBO Journal 20 589–600.[CrossRef][Web of Science][Medline]
Gudmundsdottir K & Ashworth A 2004 BRCA2 in meiosis: turning over a new leaf. Trends in Cell Biology 14 401–404.[CrossRef][Web of Science][Medline]
Henderson KA & Keeney S 2004 Tying synaptonemal complex initiation to the formation and programmed repair of DNA double-strand breaks. PNAS 101 4519–4524.
Hussain S, Witt E, Huber PA, Medhurst AL, Ashworth A & Mathew CG 2003 Direct interaction of the Fanconi anaemia protein FANCG with BRCA2/FANCD1. Human Molecular Genetics 12 2503–2510.
James RD, Schmiesing JA, Peters AH, Yokomori K & Disteche CM 2002 Differential association of SMC1alpha and SMC3 proteins with meiotic chromosomes in wild-type and SPO11-deficient male mice. Chromosome Research 10 549–560.[CrossRef][Web of Science][Medline]
Keeney S 2001 Mechanism and control of meiotic recombination initiation. Current Topics in Developmental Biology 52 1–53.[Web of Science][Medline]
Keeney S, Giroux CN & Kleckner N 1997 Meiosis-specific DNA double-strand breaks are catalyzed by Spo11, a member of a widely conserved protein family. Cell 88 375–384.[CrossRef][Web of Science][Medline]
Khil PP, Smirnova NA, Romanienko PJ & Camerini-Otero RD 2004 The mouse X chromosome is enriched for sex-biased genes not subject to selection by meiotic sex chromosome inactivation. Nature Genetics 36 642–646.[CrossRef][Web of Science][Medline]
Kneitz B, Cohen PE, Avdievich E, Zhu L, Kane MF, Hou H Jr, Kolodner RD, Kucherlapati R, Pollard JW & Edelmann W 2000 MutS homolog 4 localization to meiotic chromosomes is required for chromosome pairing during meiosis in male and female mice. Genes & Development 14 1085–1097.
Leu JY, Chua PR & Roeder GS 1998 The meiosis-specific Hop2 protein of S. cerevisiae ensures synapsis between homologous chromosomes. Cell 94 375–386.[CrossRef][Web of Science][Medline]
Libby BJ, De La Fuente R, O’Brien MJ, Wigglesworth K, Cobb J, Inselman A, Eaker S, Handel MA, Eppig JJ & Schimenti JC 2002 The mouse meiotic mutation mei1 disrupts chromosome synapsis with sexually dimorphic consequences for meiotic progression. Developmental Biology 242 174–187.[CrossRef][Web of Science][Medline]
Libby BJ, Reinholdt LG & Schimenti JC 2003 Positional cloning and characterization of Mei1, a vertebrate-specific gene required for normal meiotic chromosome synapsis in mice. PNAS 100 15706–15711.
Lichten M 2001 Meiotic recombination: breaking the genome to save it. Current Biology 11 R253–R256.[CrossRef][Web of Science][Medline]
McKim KS & Hayashi-Hagihara A 1998 mei-W68 in Drosophila melanogaster encodes a Spo11 homolog: evidence that the mechanism for initiating meiotic recombination is conserved. Genes & Development 12 2932–2942.
Moriya M, Ochiai M, Yuasa HJ, Suzuki N & Yazawa M 2004 Identification of Ca2+-dependent calmodulin-binding proteins in rat spermatogenic cells as complexes of the heat-shock proteins. Molecular Reproduction and Development 69 316–324.[CrossRef][Web of Science][Medline]
Murray AW 2004 Recycling the cell cycle: cyclins revisited. Cell 116 221–234.[CrossRef][Web of Science][Medline]
Patra D & Dunphy WG 1998 Xe-p9, a Xenopus Suc1/Cks protein, is essential for the Cdc2-dependent phosphorylation of the anaphase- promoting complex at mitosis. Genes and Development 12 2549–2559.
Petukhova GV, Romanienko PJ & Camerini-Otero RD 2003 The Hop2 protein has a direct role in promoting interhomolog interactions during mouse meiosis. Developmental Cell 5 927–936.[CrossRef][Web of Science][Medline]
Petukhova GV, Pezza RJ, Vanevski F, Ploquin M, Masson JY & Camerini-Otero RD 2005 The Hop2 and Mnd1 proteins act in concert with Rad51 and Dmc1 in meiotic recombination. Nature Structural & Molecular Biology.
Pittman DL, Cobb J, Schimenti KJ, Wilson LA, Cooper DM, Brignull E, Handel MA & Schimenti JC 1998 Meiotic prophase arrest with failure of chromosome synapsis in mice deficient for Dmc1, a germline-specific RecA homolog. Molecular Cell 1 697–705.[CrossRef][Web of Science][Medline]
Prieler S, Penkner A, Borde V & Klein F 2005 The control of Spo11’s interaction with meiotic recombination hotspots. Genes and Development 19 255–269.
Rabitsch KP, Toth A, Galova M, Schleiffer A, Schaffner G, Aigner E, Rupp C, Penkner AM, Moreno-Borchart AC, Primig M et al.2001 A screen for genes required for meiosis and spore formation based on whole-genome expression. Current Biology 11 1001–1009.[CrossRef][Web of Science][Medline]
Reynolds N, Collier B, Maratou K, Bingham V, Speed RM, Taggart M, Semple CA, Gray NK & Cooke HJ 2005 Dazl binds in vivo to specific transcripts and can regulate the pre-meiotic translation of Mvh in germ cells. Human Molecular Genetics 14 3899–3909.
Roeder GS & Bailis JM 2000 The pachytene checkpoint. Trends in Genetics 16 395–403.[CrossRef][Web of Science][Medline]
Romanienko PJ & Camerini-Otero RD 1999 Cloning, characterization, and localization of mouse and human SPO11. Genomics 61 156–169.[CrossRef][Web of Science][Medline]
Romanienko PJ & Camerini-Otero RD 2000 The mouse Spo11 gene is required for meiotic chromosome synapsis. Molecular and Cellular Proteomics 6 975–987.
Rozen S & Skaletsky HJ 2000 Primer 3 on the WWW for general users and for biologist programmers. In Bioinformatics Methods and Protocols: Methods in Molecular Biology. pp 365–386. Ed, S Krawetz & S Misner. Totowa, NJ, USA: Humana Press.
Russell LD, Ettlin RA, Sinha Hikim AP & Clegg ED 1990 Histological and Histopathological Evaluation of the Testis, edn 1 pp 62–194. Clearwater, FL, USA:Cache River Press.
Saunders PT, Turner JM, Ruggiu M, Taggart M, Burgoyne PS, Elliott D & Cooke HJ 2003 Absence of mDazl produces a final block on germ cell development at meiosis. Reproduction 126 589–597.[Abstract]
Schultz N, Hamra FK & Garbers DL 2003 A multitude of genes expressed solely in meiotic or postmeiotic spermatogenic cells offers a myriad of contraceptive targets. PNAS 100 12201–12206.
Sharan SK, Pyle A, Coppola V, Babus J, Swaminathan S, Benedict J, Swing D, Martin BK, Tessarollo L, Evans JP et al. 2004 BRCA2 deficiency in mice leads to meiotic impairment and infertility. Development 131 131–142.
Shima JE, McLean DJ, McCarrey JR & Griswold MD 2004 The murine testicular transcriptome: characterizing gene expression in the testis during the progression of spermatogenesis. Biology of Reproduction 71 319–330.
Spruck CH, de Miguel MP, Smith AP, Ryan A, Stein P, Schultz RM, Lincoln AJ, Donovan PJ & Reed SI 2003 Requirement of Cks2 for the first metaphase/anaphase transition of mammalian meiosis. Science 300 647–650.
Storlazzi A, Tesse S, Gargano S, James F, Kleckner N & Zickler D 2003 Meiotic double-strand breaks at the interface of chromosome movement, chromosome remodeling, and reductional division. Genes & Development 17 2675–2687.
Tanaka SS, Toyooka Y, Akasu R, Katoh-Fukui Y, Nakahara Y, Suzuki R, Yokoyama M & Noce T 2000 The mouse homolog of Drosophila Vasa is required for the development of male germ cells. Genes and Development 14 841–853.
Tsubouchi H & Roeder GS 2002 The Mnd1 protein forms a complex with hop2 to promote homologous chromosome pairing and meiotic double-strand break repair. Molecular and Cellular Biology 22 3078–3088.
Turner JM, Mahadevaiah SK, Fernandez-Capetillo O, Nussenz-weig A, Xu X, Deng CX & Burgoyne PS 2005 Silencing of unsynapsed meiotic chromosomes in the mouse. Nature Genetics 37 41–47.[Web of Science][Medline]
Tusher VG, Tibshirani R & Chu G 2001 Significance analysis of microarrays applied to the ionizing radiation response. PNAS 98 5116–5121.
Villeneuve AM & Hillers KJ 2001 Whence meiosis? Cell 106 647–650.[CrossRef][Web of Science][Medline]
Yang Y, Kuang Y, De Oca RM, Hays T, Moreau L, Lu N, Seed B & D’Andrea AD 2001 Targeted disruption of the murine Fanconi anemia gene, Fancg/Xrcc9. Blood 98 3435–3440.
Yoshida K, Kondoh G, Matsuda Y, Habu T, Nishimune Y & Morita T 1998 The mouse RecA-like gene Dmc1 is required for homologous chromosome synapsis during meiosis? Molecular Cell 1 707–718.[CrossRef][Web of Science][Medline]
Yuan L, Liu JG, Zhao J, Brundell E, Daneholt B & Hoog C 2000 The murine SCP3 gene is required for synaptonemal complex assembly, chromosome synapsis, and male fertility. Molecular Cell 5 73–83.[CrossRef][Web of Science][Medline]
Zhu D, Dix DJ & Eddy EM 1997 HSP70-2 is required for CDC2 kinase activity in meiosis I of mouse spermatocytes. Development 124 3007–3014.[Abstract]
This article has been cited by other articles:
 |
|
 |
|
  M.-S. Shiao, P. Khil, R. D. Camerini-Otero, T. Shiroishi, K. Moriwaki, H.-T. Yu, and M. Long Origins of New Male Germ-line Functions from X-Derived Autosomal Retrogenes in the Mouse Mol. Biol. Evol., October 1, 2007; 24(10): 2242 - 2253. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
