101
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Lawrence CJ, Schaeffer ML, Seigfried TE, Campbell DA, Harper LC. MaizeGDB's new data types, resources and activities. Nucleic Acids Res 2007; 35:D895-900. [PMID: 17202174 PMCID: PMC1899092 DOI: 10.1093/nar/gkl1048] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
MaizeGDB is the Maize Genetics and Genomics Database. Available at MaizeGDB are diverse data that support maize research including maps, gene product information, loci and their various alleles, phenotypes (both naturally occurring and as a result of directed mutagenesis), stocks, sequences, molecular markers, references and contact information for maize researchers worldwide. Also available through MaizeGDB are various community support service bulletin boards including the Editorial Board's list of high-impact papers, information about the Annual Maize Genetics Conference and the Jobs board where employment opportunities are posted. Reported here are data updates, improvements to interfaces and changes to standard operating procedures that have been made during the past 2 years. MaizeGDB is freely available and can be accessed online at http://www.maizegdb.org.
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Affiliation(s)
- Carolyn J Lawrence
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Ames, IA 50011-3260, USA.
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102
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Lhuissier FGP, Offenberg HH, Wittich PE, Vischer NOE, Heyting C. The mismatch repair protein MLH1 marks a subset of strongly interfering crossovers in tomato. THE PLANT CELL 2007; 19:862-76. [PMID: 17337626 PMCID: PMC1867368 DOI: 10.1105/tpc.106.049106] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 01/30/2007] [Accepted: 02/09/2007] [Indexed: 05/14/2023]
Abstract
In most eukaryotes, the prospective chromosomal positions of meiotic crossovers are marked during meiotic prophase by protein complexes called late recombination nodules (LNs). In tomato (Solanum lycopersicum), a cytological recombination map has been constructed based on LN positions. We demonstrate that the mismatch repair protein MLH1 occurs in LNs. We determined the positions of MLH1 foci along the 12 tomato chromosome pairs (bivalents) during meiotic prophase and compared the map of MLH1 focus positions with that of LN positions. On all 12 bivalents, the number of MLH1 foci was approximately 70% of the number of LNs. Bivalents with zero MLH1 foci were rare, which argues against random failure of detecting MLH1 in the LNs. We inferred that there are two types of LNs, MLH1-positive and MLH1-negative LNs, and that each bivalent gets an obligate MLH1-positive LN. The two LN types are differently distributed along the bivalents. Furthermore, cytological interference among MLH1 foci was much stronger than interference among LNs, implying that MLH1 marks the positions of a subset of strongly interfering crossovers. Based on the distances between MLH1 foci or LNs, we propose that MLH1-positive and MLH1-negative LNs stem from the same population of weakly interfering precursors.
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Affiliation(s)
- Franck G P Lhuissier
- Wageningen University and Research Centre, Molecular Genetics Group, NL-6703BD Wageningen, The Netherlands.
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103
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de Boer E, Dietrich AJJ, Höög C, Stam P, Heyting C. Meiotic interference among MLH1 foci requires neither an intact axial element structure nor full synapsis. J Cell Sci 2007; 120:731-6. [PMID: 17298983 DOI: 10.1242/jcs.003186] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
During meiosis, homologous chromosomes (homologs) perform reciprocal exchanges (crossovers) at a high frequency. Crossovers display interference, i.e. their spacing is more even than would be expected if they were placed randomly along the chromosomes. Concomitantly with crossover formation, synaptonemal complexes (SCs) appear between homologs: each chromosome forms an axial structure, the axial element (AE); the AEs of homologs align, and numerous transverse filaments connect the AEs to form an SC. Both the AE and the SC have been implicated in the imposition of interference. We investigated whether intact AEs or SCs are required for crossover interference in the mouse, using a mutant lacking AE protein SYCP3, which displays structurally abnormal AEs and incomplete synapsis. We estimated the level of interference from the spacing of immunofluorescent MLH1 foci, which mark almost all crossover sites in the mouse, along the SCs. The levels of interference among MLH1 foci in wild-type and Sycp3(-/-) mice were comparable, implying that neither an intact AE structure nor full synapsis is required for wild-type levels of interference.
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Affiliation(s)
- Esther de Boer
- Wageningen University, Molecular Genetics group, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands
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104
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Belonogova NM, Karamysheva TV, Biltueva LS, Perepelov EA, Minina JM, Polyakov AV, Zhdanova NS, Rubtsov NB, Searle JB, Borodin PM. Identification of all pachytene bivalents in the common shrew using DAPI-staining of synaptonemal complex spreads. Chromosome Res 2006; 14:673-9. [PMID: 16964574 DOI: 10.1007/s10577-006-1079-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 06/21/2006] [Accepted: 06/21/2006] [Indexed: 10/24/2022]
Abstract
A major problem in studies of synaptonemal complexes (SC) is the difficulty in distinguishing individual chromosomes. This problem can be solved combining SC immunostaining with FISH of chromosome-specific sequences. However, this procedure is expensive, time-consuming and applicable only to a very limited number of species. In this paper we show how a combination of SC immunostaining and DAPI staining can allow identification of all chromosome arms in surface-spreads of the SC of the common shrew (Sorex araneus L.). Enhancement of brightness and contrast of the images with photo editing software allowed us to reveal clear DAPI-positive and negative bands with relative sizes and positions similar to DAPI landmarks on mitotic metaphase chromosomes. Using FISH with DNA probes prepared from chromosome arms m and n we demonstrated correct recognition of the chromosomes mp and hn on the basis of their DAPI pattern. We show that the approach we describe here may be applied to other species and can provide an important tool for identification of individual bivalents in pachytene surface-spreads.
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Affiliation(s)
- N M Belonogova
- Institute of Cytology and Genetics, Siberian Department of the Russian Academy of Sciences, Novosibirsk 630090, Russia
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105
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Calderón PL, Pigozzi MI. MLH1-focus mapping in birds shows equal recombination between sexes and diversity of crossover patterns. Chromosome Res 2006; 14:605-12. [PMID: 16964567 DOI: 10.1007/s10577-006-1059-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 04/15/2006] [Accepted: 04/15/2006] [Indexed: 01/17/2023]
Abstract
Using immunolocalization of the mismatch-repair protein MLH1 in oocytes and spermatocytes of the Japanese quail and the zebra finch, we estimated the average amount of recombination in each sex of both species. In each case the number of MLH1 foci is statistically equivalent in males and females and the resulting sex-averaged map lengths are 2800 cM in the Japanese quail and 2275 cM in the zebra finch. In the Japanese quail the MLH1 foci are regularly distributed along the macrobivalents and recombination rates per Mb pair are somewhat lower compared to the chicken. In the zebra finch the MLH1 foci on the macrobivalents are substantially reduced in number relative to the Japanese quail and they show remarkable localization in both sexes. It is proposed that the lack of sex-dependent differences in recombination might be an extended feature among birds and that the different recombination patterns observed here reflect different controls of crossing over in spite of similarities regarding karyotypic asymmetry and DNA content. We discussed possible causes of the differences between birds and mammals, which show sex-dependent recombination differences.
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Affiliation(s)
- P L Calderón
- Centro de Investigaciones en Reproducción, Facultad de Medicina, Paraguay 2155-piso 10, C1121ABG, Buenos Aires, Argentina
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106
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Ye CJ, Stevens JB, Liu G, Ye KJ, Yang F, Bremer SW, Heng HHQ. Combined multicolor-FISH and immunostaining. Cytogenet Genome Res 2006; 114:227-34. [PMID: 16954658 DOI: 10.1159/000094205] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Accepted: 02/16/2006] [Indexed: 01/14/2023] Open
Abstract
The combination of multicolor-FISH and immunostaining produces a powerful visual method to analyze in situ DNA-protein interactions and dynamics. Representing one of the major technical improvements of FISH technology, this method has been used extensively in the field of chromosome and genome research, as well as in clinical studies, and serves as an important tool to bridge molecular analysis and cytological description. In this short review, the development and significance of this method will be briefly summarized using a limited number of examples to illustrate the large body of literature. In addition to descriptions of technical considerations, future applications and perspectives have also been discussed focusing specifically on the areas of genome organization, gene expression and medical research. We anticipate that this versatile method will play an important role in the study of the structure and function of the dynamic genome and for the development of potential applications for medical research.
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Affiliation(s)
- C J Ye
- SeeDNA Biotech Inc, Windsor, Ontario, Canada
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107
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Ashley T, Gaeth AP, Inagaki H, Seftel A, Cohen MM, Anderson LK, Kurahashi H, Emanuel BS. Meiotic recombination and spatial proximity in the etiology of the recurrent t(11;22). Am J Hum Genet 2006; 79:524-38. [PMID: 16909390 PMCID: PMC1559541 DOI: 10.1086/507652] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 07/10/2006] [Indexed: 01/27/2023] Open
Abstract
Although balanced translocations are among the most common human chromosomal aberrations, the constitutional t(11;22)(q23;q11) is the only known recurrent non-Robertsonian translocation. Evidence indicates that de novo formation of the t(11;22) occurs during meiosis. To test the hypothesis that spatial proximity of chromosomes 11 and 22 in meiotic prophase oocytes and spermatocytes plays a role in the rearrangement, the positions of the 11q23 and 22q11 translocation breakpoints were examined. Fluorescence in situ hybridization with use of DNA probes for these sites demonstrates that 11q23 is closer to 22q11 in meiosis than to a control at 6q26. Although chromosome 21p11, another control, often lies as close to 11q23 as does 22q11 during meiosis, chromosome 21 rarely rearranges with 11q23, and the DNA sequence of chromosome 21 appears to be less susceptible than 22q11 to double-strand breaks (DSBs). It has been suggested that the rearrangement recurs as a result of the palindromic AT-rich repeats at both 11q23 and 22q11, which extrude hairpin structures that are susceptible to DSBs. To determine whether the DSBs at these sites coincide with normal hotspots of meiotic recombination, immunocytochemical mapping of MLH1, a protein involved in crossing over, was employed. The results indicate that the translocation breakpoints do not coincide with recombination hotspots and therefore are unlikely to be the result of meiotic programmed DSBs, although MRE11 is likely to be involved. Previous analysis indicated that the DSBs appear to be repaired by a mechanism similar to nonhomologous end joining (NHEJ), although NHEJ is normally suppressed during meiosis. Taken together, these studies support the hypothesis that physical proximity between 11q23 and 22q11--but not typical meiotic recombinational activity in meiotic prophase--plays an important role in the generation of the constitutional t(11;22) rearrangement.
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Affiliation(s)
- Terry Ashley
- Genetics Department, School of Medicine, Yale University, New Haven, USA
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108
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Abstract
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.
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Affiliation(s)
- Peter B Moens
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.
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109
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Liebe B, Petukhova G, Barchi M, Bellani M, Braselmann H, Nakano T, Pandita TK, Jasin M, Fornace A, Meistrich ML, Baarends WM, Schimenti J, de Lange T, Keeney S, Camerini-Otero RD, Scherthan H. Mutations that affect meiosis in male mice influence the dynamics of the mid-preleptotene and bouquet stages. Exp Cell Res 2006; 312:3768-81. [PMID: 17010969 DOI: 10.1016/j.yexcr.2006.07.019] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 07/20/2006] [Accepted: 07/22/2006] [Indexed: 01/15/2023]
Abstract
Meiosis pairs and segregates homologous chromosomes and thereby forms haploid germ cells to compensate the genome doubling at fertilization. Homologue pairing in many eukaryotic species depends on formation of DNA double strand breaks (DSBs) during early prophase I when telomeres begin to cluster at the nuclear periphery (bouquet stage). By fluorescence in situ hybridization criteria, we observe that mid-preleptotene and bouquet stage frequencies are altered in male mice deficient for proteins required for recombination, ubiquitin conjugation and telomere length control. The generally low frequencies of mid-preleptotene spermatocytes were significantly increased in male mice lacking recombination proteins SPO11, MEI1, MLH1, KU80, ubiquitin conjugating enzyme HR6B, and in mice with only one copy of the telomere length regulator Terf1. The bouquet stage was significantly enriched in Atm(-/-), Spo11(-/-), Mei1(m1Jcs/m1Jcs), Mlh1(-/-), Terf1(+/-) and Hr6b(-/-) spermatogenesis, but not in mice lacking recombination proteins DMC1 and HOP2, the non-homologous end-joining DNA repair factor KU80 and the ATM downstream effector GADD45a. Mice defective in spermiogenesis (Tnp1(-/-), Gmcl1(-/-), Asm(-/-)) showed wild-type mid-preleptotene and bouquet frequencies. A low frequency of bouquet spermatocytes in Spo11(-/-)Atm(-/-) spermatogenesis suggests that DSBs contribute to the Atm(-/-)-correlated bouquet stage exit defect. Insignificant changes of bouquet frequencies in mice with defects in early stages of DSB repair (Dmc1(-/-), Hop2(-/-)) suggest that there is an ATM-specific influence on bouquet stage duration. Altogether, it appears that several pathways influence telomere dynamics in mammalian meiosis.
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Affiliation(s)
- B Liebe
- Max-Planck-Inst. for Molecular Genetics, Ihnestr. 73, D-14195 Berlin, Germany
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110
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de Boer E, Stam P, Dietrich AJJ, Pastink A, Heyting C. Two levels of interference in mouse meiotic recombination. Proc Natl Acad Sci U S A 2006; 103:9607-12. [PMID: 16766662 PMCID: PMC1475796 DOI: 10.1073/pnas.0600418103] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
During meiosis, homologous chromosomes (homologs) undergo recombinational interactions, which can yield crossovers (COs) or noncrossovers. COs exhibit interference; they are more evenly spaced along the chromosomes than would be expected if they were placed randomly. The protein complexes involved in recombination can be visualized as immunofluorescent foci. We have analyzed the distribution of such foci along meiotic prophase chromosomes of the mouse to find out when interference is imposed and whether interference manifests itself at a constant level during meiosis. We observed strong interference among MLH1 foci, which mark CO positions in pachytene. Additionally, we detected substantial interference well before this point, in late zygotene, among MSH4 foci, and similarly, among replication protein A (RPA) foci. MSH4 foci and RPA foci both mark interhomolog recombinational interactions, most of which do not yield COs in the mouse. Furthermore, this zygotene interference did not depend on SYCP1, which is a transverse filament protein of mouse synaptonemal complexes. Interference is thus not specific to COs but may occur in other situations in which the spatial distribution of events has to be controlled. Differences between the distributions of MSH4/RPA foci and MLH1 foci along synaptonemal complexes might suggest that CO interference occurs in two successive steps.
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Affiliation(s)
- Esther de Boer
- *Molecular Genetics Group, Wageningen University and Research Centre, Arboretumlaan 4, 6703 BD, Wageningen, The Netherlands
| | - Piet Stam
- Laboratory of Plant Breeding, Wageningen University and Research Centre, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands
| | - Axel J. J. Dietrich
- Department of Human Genetics, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands; and
| | - Albert Pastink
- Department of Toxicogenetics, Leiden University Medical Centre, P.O. Box 9600, 2300 RC, Leiden, The Netherlands
| | - Christa Heyting
- *Molecular Genetics Group, Wageningen University and Research Centre, Arboretumlaan 4, 6703 BD, Wageningen, The Netherlands
- To whom correspondence should be addressed. E-mail:
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111
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Zakharova KV, Galkina SA, Lukina NA, Rodionov AV. Crossing over in chicken (Gallus gallus domesticus) oogenesis: Periodic arrangement of chiasmata over chromosomes. RUSS J GENET+ 2006. [DOI: 10.1134/s1022795406060159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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112
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de Boer E, Heyting C. The diverse roles of transverse filaments of synaptonemal complexes in meiosis. Chromosoma 2006; 115:220-34. [PMID: 16523321 DOI: 10.1007/s00412-006-0057-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 01/30/2006] [Accepted: 01/30/2006] [Indexed: 10/24/2022]
Abstract
In most eukaryotes, homologous chromosomes (homologs) are closely apposed during the prophase of the first meiotic division by a ladderlike proteinaceous structure, the synaptonemal complex (SC) [Fawcett, J Biophys Biochem Cytol 2:403-406, 1956; Moses, J Biophys Biochem Cytol 2:215-218, 1956]. SCs consist of two proteinaceous axes, which each support the two sister chromatids of one homolog, and numerous transverse filaments (TFs), which connect the two axes. Organisms that assemble SCs perform meiotic recombination in the context of these structures. Although much information has accumulated about the composition of SCs and the pathways of meiotic crossing over, several questions remain about the role of SCs in meiosis, in particular, about the role of the TFs. In this review, we focus on possible role(s) of TFs. The interest in TF functions received new impulses from the recent characterization of TF-deficient mutants in a number of species. Intriguingly, the phenotypes of these mutants are very different, and a variety of TF functions appear to be hidden behind a façade of morphological conservation. However, in all TF-deficient mutants a specific class of crossovers that display interference is affected. TFs appear to create suitable preconditions for the formation of these crossovers in most species, but are most likely not directly involved in the interference process itself. Furthermore, TFs are important for full-length homolog alignment.
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Affiliation(s)
- Esther de Boer
- Botanical centre, Molecular genetics group, Wageningen University, Arboretumlaan 4, 6703 BD, Wageningen, The Netherlands
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113
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Sun F, Ko E, Martin RH. Is there a relationship between sperm chromosome abnormalities and sperm morphology? Reprod Biol Endocrinol 2006; 4:1. [PMID: 16436209 PMCID: PMC1395314 DOI: 10.1186/1477-7827-4-1] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Accepted: 01/25/2006] [Indexed: 02/01/2023] Open
Abstract
This review explores the relationship between sperm chromosomal constitution and morphology. With the advent of techniques for obtaining information on the chromosome complements of spermatozoa, this relationship has been studied in fertile men and in men with a high frequency of chromosomal abnormalities. Using human sperm karyotype analysis, no relationship between sperm chromosome abnormalities and morphology was found in fertile men, translocation carriers or post-radiotherapy cancer patients. Fluorescence in situ hybridization (FISH) analysis has not generally revealed a specific association between morphologically abnormal sperm and sperm chromosome abnormalities, but has indicated that teratozoospermia, like other forms of abnormal semen profiles (aesthenozoospermia, oligozoospermia) is associated with a modest increase in the frequency of sperm chromosome abnormalities. However, FISH studies on some infertile men and mouse strains have suggested that certain types of morphologically abnormal spermatozoa, such as macrocephalic multitailed spermatozoa, are associated with a very significantly increased frequency of aneuploidy. Thus, there may be an association between sperm morphology and aneuploidy in infertile men with specific abnormalities.
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Affiliation(s)
- Fei Sun
- Department of Medical Genetics, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Department of Genetics, Alberta Children's Hospital, Calgary, Alberta T2T 5C7, Canada
| | - Evelyn Ko
- Department of Genetics, Alberta Children's Hospital, Calgary, Alberta T2T 5C7, Canada
| | - Renée H Martin
- Department of Medical Genetics, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Department of Genetics, Alberta Children's Hospital, Calgary, Alberta T2T 5C7, Canada
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114
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Lawrence CJ, Seigfried TE, Bass HW, Anderson LK. Predicting chromosomal locations of genetically mapped loci in maize using the Morgan2McClintock Translator. Genetics 2005; 172:2007-9. [PMID: 16387866 PMCID: PMC1456272 DOI: 10.1534/genetics.105.054155] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Morgan2McClintock Translator permits prediction of meiotic pachytene chromosome map positions from recombination-based linkage data using recombination nodule frequency distributions. Its outputs permit estimation of DNA content between mapped loci and help to create an integrated overview of the maize nuclear genome structure.
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Affiliation(s)
- Carolyn J Lawrence
- USDA-ARS, Corn Insect and Crop Genetics Research Unit, Iowa State University, Ames 50011, USA.
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115
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Gruetzner F, Ashley T, Rowell DM, Marshall Graves JA. How did the platypus get its sex chromosome chain? A comparison of meiotic multiples and sex chromosomes in plants and animals. Chromosoma 2005; 115:75-88. [PMID: 16344965 DOI: 10.1007/s00412-005-0034-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2005] [Revised: 09/24/2005] [Accepted: 09/28/2005] [Indexed: 11/26/2022]
Abstract
The duck-billed platypus is an extraordinary mammal. Its chromosome complement is no less extraordinary, for it includes a system in which ten sex chromosomes form an extensive meiotic chain in males. Such meiotic multiples are unprecedented in vertebrates but occur sporadically in plant and invertebrate species. In this paper, we review the evolution and formation of meiotic multiples in plants and invertebrates to try to gain insights into the origin of the platypus meiotic multiple. We describe the meiotic hurdles that translocated mammalian chromosomes face, which make longer chains disadvantageous in mammals, and we discuss how sex chromosomes and dosage compensation might have affected the evolution of sex-linked meiotic multiples. We conclude that the evolutionary conservation of the chain in monotremes, the structural properties of the translocated chromosomes and the highly accurate segregation at meiosis make the platypus system remarkably different from meiotic multiples in other species. We discuss alternative evolutionary models, which fall broadly into two categories: either the chain is the result of a sequence of translocation events from an ancestral pair of sex chromosomes (Model I) or the entire chain came into being at once by hybridization of two populations with different chromosomal rearrangements sharing monobrachial homology (Model II).
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Affiliation(s)
- Frank Gruetzner
- Research School of Biological Sciences, Australian National University, Canberra, ACT, 2601, Australia.
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116
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Danzmann RG, Cairney M, Davidson WS, Ferguson MM, Gharbi K, Guyomard R, Holm LE, Leder E, Okamoto N, Ozaki A, Rexroad CE, Sakamoto T, Taggart JB, Woram RA. A comparative analysis of the rainbow trout genome with 2 other species of fish (Arctic charr and Atlantic salmon) within the tetraploid derivative Salmonidae family (subfamily: Salmoninae). Genome 2005; 48:1037-51. [PMID: 16391673 DOI: 10.1139/g05-067] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We updated the genetic map of rainbow trout (Oncorhynchus mykiss) for 2 outcrossed mapping panels, and used this map to assess the putative chromosome structure and recombination rate differences among linkage groups. We then used the rainbow trout sex-specific maps to make comparisons with 2 other ancestrally polyploid species of salmonid fishes, Arctic charr (Salvelinus alpinus) and Atlantic salmon (Salmo salar) to identify homeologous chromosome affinities within each species and ascertain homologous chromosome relationships among the species. Salmonid fishes exhibit a wide range of sex-specific differences in recombination rate, with some species having the largest differences for any vertebrate species studied to date. Our current estimate of female:male recombination rates in rainbow trout is 4.31:1. Chromosome structure and (or) size is associated with recombination rate differences between the sexes in rainbow trout. Linkage groups derived from presumptive acrocentric type chromosomes were observed to have much lower sex-specific differences in recombination rate than metacentric type linkage groups. Arctic charr is karyotypically the least derived species (i.e., possessing a high number of acrocentric chromosomes) and Atlantic salmon is the most derived (i.e., possessing a number of whole-arm fusions). Atlantic salmon have the largest female:male recombination ratio difference (i.e., 16.81:1) compared with rainbow trout, and Arctic charr (1.69:1). Comparisons of recombination rates between homologous segments of linkage groups among species indicated that when significant experiment-wise differences were detected (7/24 tests), recombination rates were generally higher in the species with a less-derived chromosome structure (6/7 significant comparisons). Greater similarity in linkage group syntenies were observed between Atlantic salmon and rainbow trout, suggesting their closer phylogenetic affinities, and most interspecific linkage group comparisons support a model that suggests whole chromosome arm translocations have occurred in the evolution of this group. However, some possible exceptions were detected and these findings are discussed in relation to their influence on segregation distortion patterns. We also report unusual meiotic segregation patterns in a female parent involving the duplicated (homeologous) linkage group pair 12/16 and discuss several models that may account for these patterns.Key words: linkage analysis, genetic markers, polyploidy, tetrasomic inheritance, segregation distortion, recombination rate.
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Affiliation(s)
- Roy G Danzmann
- Department of Integrative Biology, University of Guelph, ON, Canada.
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117
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Kolas NK, Svetlanov A, Lenzi ML, Macaluso FP, Lipkin SM, Liskay RM, Greally J, Edelmann W, Cohen PE. Localization of MMR proteins on meiotic chromosomes in mice indicates distinct functions during prophase I. ACTA ACUST UNITED AC 2005; 171:447-58. [PMID: 16260499 PMCID: PMC2171243 DOI: 10.1083/jcb.200506170] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mammalian MutL homologues function in DNA mismatch repair (MMR) after replication errors and in meiotic recombination. Both functions are initiated by a heterodimer of MutS homologues specific to either MMR (MSH2-MSH3 or MSH2-MSH6) or crossing over (MSH4-MSH5). Mutations of three of the four MutL homologues (Mlh1, Mlh3, and Pms2) result in meiotic defects. We show herein that two distinct complexes involving MLH3 are formed during murine meiosis. The first is a stable association between MLH3 and MLH1 and is involved in promoting crossing over in conjunction with MSH4-MSH5. The second complex involves MLH3 together with MSH2-MSH3 and localizes to repetitive sequences at centromeres and the Y chromosome. This complex is up-regulated in Pms2-/- males, but not females, providing an explanation for the sexual dimorphism seen in Pms2-/- mice. The association of MLH3 with repetitive DNA sequences is coincident with MSH2-MSH3 and is decreased in Msh2-/- and Msh3-/- mice, suggesting a novel role for the MMR family in the maintenance of repeat unit integrity during mammalian meiosis.
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Affiliation(s)
- Nadine K Kolas
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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118
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de Vries FAT, de Boer E, van den Bosch M, Baarends WM, Ooms M, Yuan L, Liu JG, van Zeeland AA, Heyting C, Pastink A. Mouse Sycp1 functions in synaptonemal complex assembly, meiotic recombination, and XY body formation. Genes Dev 2005; 19:1376-89. [PMID: 15937223 PMCID: PMC1142560 DOI: 10.1101/gad.329705] [Citation(s) in RCA: 333] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In meiotic prophase, synaptonemal complexes (SCs) closely appose homologous chromosomes (homologs) along their length. SCs are assembled from two axial elements (AEs), one along each homolog, which are connected by numerous transverse filaments (TFs). We disrupted the mouse gene encoding TF protein Sycp1 to analyze the role of TFs in meiotic chromosome behavior and recombination. Sycp1(-/-) mice are infertile, but otherwise healthy. Sycp1(-/-) spermatocytes form normal AEs, which align homologously, but do not synapse. Most Sycp1(-/-) spermatocytes arrest in pachynema, whereas a small proportion reaches diplonema, or, exceptionally, metaphase I. In leptotene Sycp1(-/-) spermatocytes, gammaH2AX (indicative of DNA damage, including double-strand breaks) appears normal. In pachynema, Sycp1(-/-) spermatocytes display a number of discrete gammaH2AX domains along each chromosome, whereas gammaH2AX disappears from autosomes in wild-type spermatocytes. RAD51/DMC1, RPA, and MSH4 foci (which mark early and intermediate steps in pairing/recombination) appear in similar numbers as in wild type, but do not all disappear, and MLH1 and MLH3 foci (which mark late steps in crossing over) are not formed. Crossovers were rare in metaphase I of Sycp1(-/-) mice. We propose that SYCP1 has a coordinating role, and ensures formation of crossovers. Unexpectedly, Sycp1(-/-) spermatocytes did not form XY bodies.
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Affiliation(s)
- Femke A T de Vries
- Department of Toxicogenetics, Leiden University Medical Centre, The Netherlands
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119
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Page SL, Hawley RS. The Drosophila meiotic mutant mei-352 is an allele of klp3A and reveals a role for a kinesin-like protein in crossover distribution. Genetics 2005; 170:1797-807. [PMID: 15965253 PMCID: PMC1449747 DOI: 10.1534/genetics.105.041194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Accepted: 05/30/2005] [Indexed: 01/31/2023] Open
Abstract
The semisterile meiotic mutant mei-352 alters the distribution of meiotic exchanges without greatly affecting their total frequency. We show that the mei-352 mutation is an allele of the klp3A gene, which encodes a kinesin-like protein of the Kinesin-4 family. The semisterility observed in mei-352 females results from a known defect of klp3A oocytes in mediating pronuclear fusion. Interestingly, other klp3A alleles also exhibit defects in meiotic recombination similar to those of mei-352. Finally, we show that the Klp3A protein localizes within the oocyte nucleus during meiotic prophase, the time at which exchange distribution is established, and extensively colocalizes with DNA. The parallel of the klp3A phenotype with a meiotic defect observed for kar3 mutants in yeast suggests a role for kinesins in early meiosis and might reflect a previously suggested role for this class of kinesins in chromosome condensation.
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Affiliation(s)
- Scott L Page
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
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120
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Pinton A, Faraut T, Yerle M, Gruand J, Pellestor F, Ducos A. Comparison of male and female meiotic segregation patterns in translocation heterozygotes: a case study in an animal model (Sus scrofa domestica L.). Hum Reprod 2005; 20:2476-82. [PMID: 15878917 DOI: 10.1093/humrep/dei067] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The comparison of male and female meiotic segregation patterns for individuals carrying identical reciprocal translocations has been rarely reported in mammalian species. The main comparative study involving males and females with comparable genetic background has been performed in the mouse. Swine is another relevant animal model species for meiotic studies. Here we present the segregation patterns determined for sows carrying one of the two following reciprocal translocations: 38, XX, rcp(3;15)(q27;q13), and 38, XX, rcp(12;14)(q13;q21). These segregation data were compared to those previously obtained for closely related boars carrying the same balanced chromosomal rearrangements. METHODS Dual colour in situ hybridization of whole chromosome painting probes was carried out on metaphases of in vitro-matured oocytes II. Segregation results were obtained for 118 and 206 metaphases II respectively for the two translocations. RESULTS Significant differences between sexes were demonstrated for both rearrangements. For instance, for the 3/15 translocation, the chromosomally unbalanced gametes were of different origin: preponderance of the adjacent-I segregation in the male (31.4%), and of the adjacent-II (14.3%) and 3:1 (14.3%) segregations in females. For the 12/14 translocation, the proportion of balanced gametes was greater in males than in females (75.9 and 59.4% respectively). CONCLUSION This study is a new scientific contribution to compare the segregation patterns of male and female carriers of identical chromosomal rearrangements. The results obtained are consistent with those previously reported in mice. Hypotheses to interpret the observed differences between the two translocations, as well as between the male and female segregation patterns, are formulated and discussed.
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Affiliation(s)
- A Pinton
- UMR INRA-ENVT Cytogénétique des Populations Animales, Toulouse, France.
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121
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THOMAS MEIKE, IHLE SONJA, RAVAOARIMANANA IARY, KRAECHTER SUSANNE, WIEHE THOMAS, TAUTZ DIETHARD. Microsatellite variability in wild populations of the house mouse is not influenced by differences in chromosomal recombination rates. Biol J Linn Soc Lond 2005. [DOI: 10.1111/j.1095-8312.2005.00459.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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122
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Anderson LK, Stack SM. Recombination nodules in plants. Cytogenet Genome Res 2005; 109:198-204. [PMID: 15753577 DOI: 10.1159/000082400] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 03/28/2004] [Indexed: 11/19/2022] Open
Abstract
The molecular events of recombination are thought to be catalyzed by proteins present in recombination nodules (RNs). Therefore, studying RN structure and function should give insights into the processes by which meiotic recombination is regulated in eukaryotes. Two types of RNs have been identified so far, early (ENs) and late (LNs). ENs appear at leptotene and persist into early pachytene while LNs appear in pachytene and remain into early diplotene. ENs and LNs can be distinguished not only on their time of appearance, but also by such characteristics as shape and size, relative numbers, and association with unsynapsed and/or synapsed chromosomal segments. The function(s) of ENs is not clear, but they may have a role in searching for DNA homology, synapsis, gene conversion and/or crossing over. LNs are well correlated with crossing over. Here, the patterns of ENs and LNs during prophase I in plants are reviewed.
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Affiliation(s)
- L K Anderson
- Department of Biology, Colorado State University, Fort Collins, CO 80523-1878, USA.
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123
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Huang SW, Friedman R, Yu N, Yu A, Li WH. How strong is the mutagenicity of recombination in mammals? Mol Biol Evol 2005; 22:426-31. [PMID: 15496551 DOI: 10.1093/molbev/msi025] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It is commonly believed that a high recombination rate such as that in a pseudoautosomal region (PAR) greatly increases the mutation rate because a 170-fold increase was estimated for the mouse PAR region. However, sequencing PAR and non-PAR introns of the Fxy gene in four Mus taxa, we found an increase of only twofold to fivefold. Furthermore, analyses of sequence data from human and orangutan PAR and X-linked regions and from autosomal regions showed a weak effect of recombination on mutation rate (a slope of less than 0.2% per cM/Mb), although a much stronger effect on GC content (1% to 2% per cM/Mb). Because typical recombination rates in mammals are much lower than those in PARs, the mutagenicity of recombination is weak or, at best, moderate, although its effect on GC% is much stronger. In addition, contrary to a previous study, we found no Fxy duplicate in Mus spretus.
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Affiliation(s)
- Shiao-Wei Huang
- Department of Ecology and Evolution, University of Chicago, Chicago, USA
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124
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White EJ, Cowan C, Cande WZ, Kaback DB. In vivo analysis of synaptonemal complex formation during yeast meiosis. Genetics 2005; 167:51-63. [PMID: 15166136 PMCID: PMC1470843 DOI: 10.1534/genetics.167.1.51] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During meiotic prophase a synaptonemal complex (SC) forms between each pair of homologous chromosomes and is believed to be involved in regulating recombination. Studies on SCs usually destroy nuclear architecture, making it impossible to examine the relationship of these structures to the rest of the nucleus. In Saccharomyces cerevisiae the meiosis-specific Zip1 protein is found throughout the entire length of each SC. To analyze the formation and structure of SCs in living cells, a functional ZIP1::GFP fusion was constructed and introduced into yeast. The ZIP1::GFP fusion produced fluorescent SCs and rescued the spore lethality phenotype of zip1 mutants. Optical sectioning and fluorescence deconvolution light microscopy revealed that, at zygotene, SC assembly was initiated at foci that appeared uniformly distributed throughout the nuclear volume. At early pachytene, the full-length SCs were more likely to be localized to the nuclear periphery while at later stages the SCs appeared to redistribute throughout the nuclear volume. These results suggest that SCs undergo dramatic rearrangements during meiotic prophase and that pachytene can be divided into two morphologically distinct substages: pachytene A, when SCs are perinuclear, and pachytene B, when SCs are uniformly distributed throughout the nucleus. ZIP1::GFP also facilitated the enrichment of fluorescent SC and the identification of meiosis-specific proteins by MALDI-TOF mass spectroscopy.
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Affiliation(s)
- Eric J White
- Department of Microbiology and Molecular Genetics, UMDNJ-Graduate School of Biomedical Sciences, UMDNJ-New Jersey Medical School, International Center for Public Health, Newark, New Jersey 07101-1709, USA
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125
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Anderson LK, Salameh N, Bass HW, Harper LC, Cande WZ, Weber G, Stack SM. Integrating genetic linkage maps with pachytene chromosome structure in maize. Genetics 2005; 166:1923-33. [PMID: 15126409 PMCID: PMC1470829 DOI: 10.1534/genetics.166.4.1923] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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 (r(2) = 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.
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Affiliation(s)
- Lorinda K Anderson
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523, USA.
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126
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Russell LB, Hunsicker PR, Kerley M, Pyle A, Saxton AM. Etoposide exposure during male mouse pachytene has complex effects on crossing-over and causes nondisjunction. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2004; 565:61-77. [PMID: 15576240 DOI: 10.1016/j.mrgentox.2004.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 09/20/2004] [Accepted: 09/20/2004] [Indexed: 10/26/2022]
Abstract
In experiments involving different germ-cell stages, we had previously found meiotic prophase of the male mouse to be vulnerable to the induction of several types of genetic damage by the topoisomerase-II inhibitor etoposide. The present study of etoposide effects involved two end points of meiotic events known to occur in primary spermatocytes--chromosomal crossing-over and segregation. By following assortment of 13 microsatellite markers in two chromosomes (Ch 7 and Ch 15) it was shown that etoposide significantly affected crossing-over, but did not do so in a uniform fashion. Treatment generally changed the pattern for each chromosome, leading to local decreases in recombination, a distal shift in locations of crossing-over, and an overall decrease in double crossovers; at least some of these results might be interpreted as evidence for increased interference. Two methods were used to explore etoposide effects on chromosome segregation: a genetic experiment capable of detecting sex-chromosome nondisjunction in living progeny; and the use of FISH (fluorescence in situ hybridization) technology to score numbers of Chromosomes X, Y, and 8 in spermatozoa. Taken together these two approaches indicated that etoposide exposure of pachytene spermatocytes induces malsegregation, and that the findings of the genetic experiment probably yielded a marked underestimate of nondisjunction. As indicated by certain segregants, at least part of the etoposide effect could be due to disrupted pairing of achiasmatic homologs, followed by precocious sister-centromere separation. It has been shown for several organisms that absent or reduced levels of recombination, as well as suboptimally positioned recombination events, may be associated with abnormal segregation. Etoposide is the only chemical tested to date for which living progeny indicates an effect on both male meiotic crossing-over and chromosome segregation. Whether, however, etoposide-induced changes in recombination patterns are direct causes of the observed malsegregation requires additional investigation.
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Affiliation(s)
- Liane B Russell
- Life Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6420, USA.
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127
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Sun F, Trpkov K, Rademaker A, Ko E, Martin RH. Variation in meiotic recombination frequencies among human males. Hum Genet 2004; 116:172-8. [PMID: 15578224 DOI: 10.1007/s00439-004-1215-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 10/13/2004] [Indexed: 01/20/2023]
Abstract
Meiotic recombination is essential for the segregation of homologous chromosomes and the formation of normal haploid gametes. Little is known about patterns of meiotic recombination in human germ cells or the mechanisms that control these patterns. Here, newly developed immunofluorescence techniques, based on the detection of MLH1 (a DNA mismatch repair protein) foci on synaptonemal complexes (SCs) at prophase I of meiosis, were used to examine recombination in human spermatocytes. The mean number of MLH1 foci per cell in all donors was 48.0 with range from 21 to 65. Remarkable variation in the recombination frequency was noted among 11 normal individuals: the mean frequencies of chromosomal recombination foci ranged from a low of 42.5 to a high of 55.0 exchanges. Donor age did not contribute to this variation. There was no correlation between this variation and the frequency of gaps (discontinuities) or splits (unpaired chromosome regions) in the SCs. The mean percentage of cells with gaps was 35% (range: 20% to 58%) and with splits was 7% (range: 0% to 37%). Bivalents without a recombination focus were rare, with a frequency of only 0.3%. Thus, achiasmate chromosomes appear to be rare in human male meiosis.
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Affiliation(s)
- Fei Sun
- Department of Medical Genetics, University of Calgary, Calgary, T2N 4N1, Canada
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128
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Abstract
As recently as 20 years ago, there was relatively little information about the number and distribution of recombinational events in human meiosis, and we knew virtually nothing about factors affecting patterns of recombination. However, the generation of a variety of linkage-based genetic mapping tools and, more recently, cytological approaches that enable us to directly visualize the recombinational process in meiocytes, have led to an increased understanding of human meiosis. In this review, we discuss the different approaches used to study meiotic recombination in humans, our understanding of factors that affect the number and location of recombinational events, and clinical consequences of variation in the recombinational process.
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Affiliation(s)
- Audrey Lynn
- Department of Genetics and Center for Human Genetics, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, Ohio 44106, USA.
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129
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Koehler KE, Millie EA, Cherry JP, Schrump SE, Hassold TJ. Meiotic exchange and segregation in female mice heterozygous for paracentric inversions. Genetics 2004; 166:1199-214. [PMID: 15082541 PMCID: PMC1470797 DOI: 10.1534/genetics.166.3.1199] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Inversion heterozygosity has long been noted for its ability to suppress the transmission of recombinant chromosomes, as well as for altering the frequency and location of recombination events. In our search for meiotic situations with enrichment for nonexchange and/or single distal-exchange chromosome pairs, exchange configurations that are at higher risk for nondisjunction in humans and other organisms, we examined both exchange and segregation patterns in 2728 oocytes from mice heterozygous for paracentric inversions, as well as controls. We found dramatic alterations in exchange position in the heterozygotes, including an increased frequency of distal exchanges for two of the inversions studied. However, nondisjunction was not significantly increased in oocytes heterozygous for any inversion. When data from all inversion heterozygotes were pooled, meiotic nondisjunction was slightly but significantly higher in inversion heterozygotes (1.2%) than in controls (0%), although the frequency was still too low to justify the use of inversion heterozygotes as a model of human nondisjunction.
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Affiliation(s)
- Kara E Koehler
- Department of Genetics and the Center for Human Genetics, Case Western Reserve University and the University Hospitals of Cleveland, Cleveland, Ohio 44106-4955, USA.
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130
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Tease C, Hultén MA. Inter-sex variation in synaptonemal complex lengths largely determine the different recombination rates in male and female germ cells. Cytogenet Genome Res 2004; 107:208-15. [PMID: 15467366 DOI: 10.1159/000080599] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Accepted: 06/15/2004] [Indexed: 11/19/2022] Open
Abstract
Meiotic chromosomes in human oocytes are packaged differently than in spermatocytes at the pachytene stage of meiosis I, when crossing-over takes place. Thus the meiosis-specific pairing structure, the synaptonemal complex (SC), is considerably longer in oocytes in comparison to spermatocytes. The aim of the present study was to examine the influence of this length factor on meiotic recombination in male and female human germ cells. The positions of crossovers were identified by the DNA mismatch repair protein MLH1. Spermatocytes have approximately 50 crossovers per cell in comparison to more than 70 in oocytes. Analyses of inter-crossover distances (and presumptively crossover interference) along SCs suggested that while there might be inter-individual variation, there was no consistent difference between sexes. Thus the higher rate of recombination in human oocytes is not a consequence of more closely spaced crossovers along the SCs. The rate of recombination per unit length of SC is higher in spermatocytes than oocytes. However, when the so-called obligate chiasma is excluded from the analysis, then the rates of recombination per unit length of SC are essentially identical in the two sexes. Our analyses indicate that the inter-sex difference in recombination is largely a consequence of the difference in meiotic chromosome architecture in the two sexes. We propose that SC length per se, and therefore the size of the physical platform for crossing-over (and not the DNA content) is the principal factor determining the difference in rate of recombination in male and female germ cells. A preliminary investigation of SC loop size by fluorescence in situ hybridization (FISH) indicated loops may be shorter in oocytes than in spermatocytes.
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Affiliation(s)
- C Tease
- Department of Biological Sciences, University of Warwick, Coventry, UK
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131
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Kolas NK, Cohen PE. Novel and diverse functions of the DNA mismatch repair family in mammalian meiosis and recombination. Cytogenet Genome Res 2004; 107:216-31. [PMID: 15467367 DOI: 10.1159/000080600] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Accepted: 06/02/2004] [Indexed: 11/19/2022] Open
Abstract
The mismatch repair (MMR) family is a highly conserved group of proteins that function in genome stabilization and mutation avoidance. Their role has been particularly well studied in the context of DNA repair following replication errors, and disruption of these processes results in characteristic microsatellite instability, repair defects and, in mammals, susceptibility to cancer. An additional role in meiotic recombination has been described for several family members, as revealed by extensive studies in yeast. More recently, the role of the mammalian MMR family in meiotic progression has been elucidated by the phenotypic analysis of mice harboring targeted mutations in the genes encoding several MMR family members. This review will discuss the phenotypes of the various mutant mouse lines and, drawing from our knowledge of MMR function in yeast meiosis and in somatic cell repair, will attempt to elucidate the significance of MMR activity in mouse germ cells. These studies highlight the importance of comparative analysis of MMR orthologs across species, and also underscore distinct sexually dimorphic characteristics of mammalian recombination and meiosis.
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Affiliation(s)
- N K Kolas
- Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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132
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Codina-Pascual M, Kraus J, Speicher MR, Oliver-Bonet M, Murcia V, Sarquella J, Egozcue J, Navarro J, Benet J. Characterization of all human male synaptonemal complexes by subtelomere multiplex-FISH. Cytogenet Genome Res 2004; 107:18-21. [PMID: 15305051 DOI: 10.1159/000079566] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2004] [Accepted: 05/26/2004] [Indexed: 11/19/2022] Open
Abstract
During meiotic prophase I, homologous chromosomes synapse and recombine. Both events are of vital importance for the success of meiosis. When homologous chromosomes synapse, a proteinaceous structure called synaptonemal complex (SC) appears along the pairing axis and meiotic recombination takes place. The existence of immunolabeling techniques for SC proteins (SCP1, SCP2 and SCP3) and for DNA mismatch repair proteins present in late recombination nodules (MLH1) allow analyses of both synapsis and meiotic recombination in the gametocyte I. In situ hybridization methods can be applied afterwards because chromatin is preserved during cell fixation for immunoanalysis. The combination of both methodologies allows the analysis of synapsis and the creation of recombination maps for each bivalent. In this work we apply the seven-fluorochrome subtelomere-specific multiplex FISH assay (stM-FISH) to human male meiotic cells previously labeled by immunofluorescence (SCP1, SCP3, MLH1, CENP) to assess its utility for human SC karyotyping. This FISH method consists of microdissected subtelomeric probes labeled combinatorially with seven different fluorochromes. Results prove its usefulness for the identification of all human SCs. Furthermore, by labeling subtelomeric regions this one-single-step method enables the characterization of interstitial and terminal SC fragments and SC delineation even if superposition is present in pachytene spreads.
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Affiliation(s)
- M Codina-Pascual
- Unitat Biologia, Facultat Medicina, Dept. Biologia Cel.lular, Fisiologia i Immunologia, UAB, Bellaterra, Spain.
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133
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Sun F, Trpkov K, Rademaker A, Ko E, Barclay L, Mikhaail-Philips M, Martin RH. The effect of cold storage on recombination frequencies in human male testicular cells. Cytogenet Genome Res 2004; 106:39-42. [PMID: 15218239 DOI: 10.1159/000078558] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Accepted: 02/10/2004] [Indexed: 11/19/2022] Open
Abstract
Meiotic recombination is essential for the segregation of homologous chromosomes and formation of normal haploid gametes. Decreased recombination is associated with the production of aneuploid sperm in humans. MLH1, a DNA mismatch repair protein, was recently found to mark the sites of recombination in humans. Newly developed immunofluorescence techniques to identify MLH1 foci on synaptonemal complexes (SCs) in pachytene cells from testicular tissue have opened up a new avenue of research on meiotic recombination. Future studies on normal and abnormal recombination in early meiosis will further research in human reproduction and genetics. However, the availability of testicular material will always be a major limiting factor in this kind of study. In order to obtain an adequate number of samples and samples of particular research interest, it is often of benefit to obtain samples from distant regions. Therefore, it is necessary to determine whether the quality of samples and accuracy of MLH1 frequencies change after transporting testicular samples from a distance. In the present study, we examined the recombination frequencies (numbers of MLH1 foci using immunofluorescence techniques) in 6 normal testicular samples. Each sample was split and analyzed in the fresh state and after storage on ice for two days, mimicking overnight courier air transport. The results showed no significant difference in the quality of the SC preparations or in the number of MLH1 foci between these two groups. These results demonstrate that testicular specimens may be shipped on ice without compromising data on chromosome pairing and recombination in early meiosis.
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Affiliation(s)
- F Sun
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
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134
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Anderson LK, Doyle GG, Brigham B, Carter J, Hooker KD, Lai A, Rice M, Stack SM. High-resolution crossover maps for each bivalent of Zea mays using recombination nodules. Genetics 2004; 165:849-65. [PMID: 14573493 PMCID: PMC1462767 DOI: 10.1093/genetics/165.2.849] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Recombination nodules (RNs) are closely correlated with crossing over, and, because they are observed by electron microscopy of synaptonemal complexes (SCs) in extended pachytene chromosomes, RNs provide the highest-resolution cytological marker currently available for defining the frequency and distribution of crossovers along the length of chromosomes. Using the maize inbred line KYS, we prepared an SC karyotype in which each SC was identified by relative length and arm ratio and related to the proper linkage group using inversion heterozygotes. We mapped 4267 RNs on 2080 identified SCs to produce high-resolution maps of RN frequency and distribution on each bivalent. RN frequencies are closely correlated with both chiasma frequencies and SC length. The total length of the RN recombination map is about twofold shorter than that of most maize linkage maps, but there is good correspondence between the relative lengths of the different maps when individual bivalents are considered. Each bivalent has a unique distribution of crossing over, but all bivalents share a high frequency of distal RNs and a severe reduction of RNs at and near kinetochores. The frequency of RNs at knobs is either similar to or higher than the average frequency of RNs along the SCs. These RN maps represent an independent measure of crossing over along maize bivalents.
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Affiliation(s)
- Lorinda K Anderson
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523, USA.
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135
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Kauppi L, Jeffreys AJ, Keeney S. Where the crossovers are: recombination distributions in mammals. Nat Rev Genet 2004; 5:413-24. [PMID: 15153994 DOI: 10.1038/nrg1346] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Liisa Kauppi
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK.
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136
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Anderson LK, Salameh N, Bass HW, Harper LC, Cande WZ, Weber G, Stack SM. Integrating Genetic Linkage Maps With Pachytene Chromosome Structure in Maize. Genetics 2004. [DOI: 10.1093/genetics/166.4.1923] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
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.
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Affiliation(s)
- Lorinda K Anderson
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Naser Salameh
- Department of Plant Breeding and Biotechnology, University of Hohenheim, D-70593 Stuttgart, Germany
| | - Hank W Bass
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306
| | - Lisa C Harper
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - W Z Cande
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Gerd Weber
- Department of Plant Breeding and Biotechnology, University of Hohenheim, D-70593 Stuttgart, Germany
| | - Stephen M Stack
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523
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137
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Merico V, Pigozzi MI, Esposito A, Merani MS, Garagna S. Meiotic recombination and spermatogenic impairment in Mus musculus domesticus carrying multiple simple Robertsonian translocations. Cytogenet Genome Res 2004; 103:321-9. [PMID: 15051955 DOI: 10.1159/000076820] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Accepted: 10/06/2003] [Indexed: 11/19/2022] Open
Abstract
We quantitatively analyzed the spermatogenic process, including evaluation of seminiferous tubules with defective cycles, rates of germ cell death and sperm morphology, in adult male mice with standard telocentric chromosomes (2n = 40, CD1 strain), homozygous (2n = 24, Mil II population) and heterozygous (2n = 24 x 40) for Robertsonian (Rb) rearrangements. The animals were analyzed at three different ages: three, five and seven months after birth. The number and position of crossover events were also determined by chiasmata counting and immunostaining with an antibody against mouse MLH1 protein. Our analysis of spermatogenesis confirms the impairment of the spermatogenic process in multiple simple heterozygotes due to both germ cell and abnormal sperm morphology. The detrimental effects exerted by Rb heterozygosities were found to be at least partially buffered with time: the frequency of defective tubules was lower and germ cell survival and sperm morphology better in 7-month-old animals than in the 3- and 5-month-old mice. While there are previously published data on germ cell death in multiple simple heterozygotes, this is the first report of a partial rescue of spermatogenesis with time. The mean frequency of MLH1 foci was lower in Rb homozygous and heterozygous mice than in mice carrying all telocentric chromosomes. The lower number of foci in Rb mice can be ascribed to a decrease in the number of multiple chiasmata and the maintenance of single chiasmata preferentially located in the terminal region of both the telocentric and metacentric chromosomes.
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Affiliation(s)
- V Merico
- Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia Animale, Università degli Studi di Pavia, Pavia, Italia
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138
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Abstract
A central event in sexual reproduction is the reduction in chromosome number that occurs at the meiosis I division. Most eukaryotes rely on crossing over between homologs, and the resulting chiasmata, to direct meiosis I chromosome segregation, yet make very few crossovers per chromosome pair. This indicates that meiotic recombination must be tightly regulated to ensure that each chromosome pair enjoys the crossover necessary to ensure correct segregation. Here, we investigate control of meiotic crossing over in Caenorhabditis elegans, which averages only one crossover per chromosome pair per meiosis, by constructing genetic maps of end-to-end fusions of whole chromosomes. Fusion of chromosomes removes the requirement for a crossover in each component chromosome segment and thereby reveals a propensity to restrict the number of crossovers such that pairs of fusion chromosomes composed of two or even three whole chromosomes enjoy but a single crossover in the majority of meioses. This regulation can operate over physical distances encompassing half the genome. The meiotic behavior of heterozygous fusion chromosomes further suggests that continuous meiotic chromosome axes, or structures that depend on properly assembled axes, may be important for crossover regulation.
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Affiliation(s)
- Kenneth J Hillers
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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139
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Qin J, Richardson LL, Jasin M, Handel MA, Arnheim N. Mouse strains with an active H2-Ea meiotic recombination hot spot exhibit increased levels of H2-Ea-specific DNA breaks in testicular germ cells. Mol Cell Biol 2004; 24:1655-66. [PMID: 14749381 PMCID: PMC344187 DOI: 10.1128/mcb.24.4.1655-1666.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We devised a sensitive method for the site-specific detection of rare meiotic DNA strand breaks in germ cell-enriched testicular cell populations from mice that possess or lack an active recombination hot spot at the H2-Ea gene. Using germ cells from adult animals, we found an excellent correlation between the frequency of DNA breaks in the 418-bp H2-Ea hot spot and crossover activity. The temporal appearance of DNA breaks was also studied in 7- to 18-day-old mice with an active hot spot during the first waves of spermatogenesis. The number of DNA breaks detected rose as leptotene and zygotene spermatocytes populate the testis with a peak at day 14 postpartum, when leptotene, zygotene, and early pachytene spermatocytes are the most common meiotic prophase I cell types. The number of DNA breaks drops precipitously 1 day later, when middle to late pachytene spermatocytes become the dominant subtype. The recombination-related breaks in the hot spot likely reflect SPO11-induced double-strand breaks and/or recombination intermediates containing free 3' hydroxyl groups.
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Affiliation(s)
- Jian Qin
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles, California 90089-1340, USA
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140
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Sun F, Oliver-Bonet M, Liehr T, Starke H, Ko E, Rademaker A, Navarro J, Benet J, Martin RH. Human male recombination maps for individual chromosomes. Am J Hum Genet 2004; 74:521-31. [PMID: 14973780 PMCID: PMC1182265 DOI: 10.1086/382138] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Accepted: 12/12/2003] [Indexed: 11/03/2022] Open
Abstract
Meiotic recombination is essential for the segregation of chromosomes and the formation of normal haploid gametes, yet we know very little about the meiotic process in humans. We present the first (to our knowledge) recombination maps for every autosome in the human male obtained by new immunofluorescence techniques followed by centromere-specific multicolor fluorescence in situ hybridization in human spermatocytes. The mean frequency of autosomal recombination foci was 49.8+/-4.3, corresponding to a genetic length of 2,490 cM. All autosomal bivalents had at least one recombination focus. In contrast, the XY bivalent had a recombination focus in 73% of nuclei, suggesting that a relatively large proportion of spermatocytes may be at risk for nondisjunction of the XY bivalent or elimination by meiotic arrest. There was a very strong correlation between mean length of the synaptonemal complex (SC) and the number of recombination foci per SC. Each bivalent presented a distinct distribution of recombination foci, but in general, foci were near the distal parts of the chromosome, with repression of foci near the centromere. The position of recombination foci demonstrated positive interference, but, in rare instances, foci were very close to one another.
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Affiliation(s)
- Fei Sun
- Department of Medical Genetics, University of Calgary, and Department of Genetics, Alberta Children's Hospital, Canada
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141
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Kleckner N, Storlazzi A, Zickler D. Coordinate variation in meiotic pachytene SC length and total crossover/chiasma frequency under conditions of constant DNA length. Trends Genet 2004; 19:623-8. [PMID: 14585614 DOI: 10.1016/j.tig.2003.09.004] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Nancy Kleckner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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142
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Saitta SC, Harris SE, Gaeth AP, Driscoll DA, McDonald-McGinn DM, Maisenbacher MK, Yersak JM, Chakraborty PK, Hacker AM, Zackai EH, Ashley T, Emanuel BS. Aberrant interchromosomal exchanges are the predominant cause of the 22q11.2 deletion. Hum Mol Genet 2003; 13:417-28. [PMID: 14681306 PMCID: PMC2836129 DOI: 10.1093/hmg/ddh041] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chromosome 22q11.2 deletions are found in almost 90% of patients with DiGeorge/velocardiofacial syndrome (DGS/VCFS). Large, chromosome-specific low copy repeats (LCRs), flanking and within the deletion interval, are presumed to lead to misalignment and aberrant recombination in meiosis resulting in this frequent microdeletion syndrome. We traced the grandparental origin of regions flanking de novo 3 Mb deletions in 20 informative three-generation families. Haplotype reconstruction showed an unexpectedly high number of proximal interchromosomal exchanges between homologs, occurring in 19/20 families. Instead, the normal chromosome 22 in these probands showed interchromosomal exchanges in 2/15 informative meioses, a rate consistent with the genetic distance. Meiotic exchanges, visualized as MLH1 foci, localize to the distal long arm of chromosome 22 in 75% of human spermatocytes tested, also reflecting the genetic map. Additionally, we found no effect of proband gender or parental age on the crossover frequency. Parental origin studies in 65 de novo 3 Mb deletions (including these 20 patients) demonstrated no bias. Unlike Williams syndrome, we found no chromosomal inversions flanked by LCRs in 22 sets of parents of 22q11 deleted patients, or in eight non-deleted patients with a DGS/VCFS phenotype using FISH. Our data are consistent with significant aberrant interchromosomal exchange events during meiosis I in the proximal region of the affected chromosome 22 as the likely etiology for the deletion. This type of exchange occurs more often than is described for deletions of chromosomes 7q11, 15q11, 17p11 and 17q11, implying a difference in the meiotic behavior of chromosome 22.
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Affiliation(s)
- Sulagna C. Saitta
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104 USA
| | - Stacy E. Harris
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
| | - Ann P. Gaeth
- Department of Genetics, Yale University School of Medicine, New Haven, CT, 06520 USA
| | - Deborah A. Driscoll
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104 USA
- Department of Obstetrics and Gynecology, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104 USA
| | - Donna M. McDonald-McGinn
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
| | - Melissa K. Maisenbacher
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
| | - Jill M. Yersak
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
| | - Prabir K. Chakraborty
- Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - April M. Hacker
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
| | - Elaine H. Zackai
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104 USA
- Department of Obstetrics and Gynecology, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104 USA
| | - Terry Ashley
- Department of Genetics, Yale University School of Medicine, New Haven, CT, 06520 USA
| | - Beverly S. Emanuel
- Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104 USA
- Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, 19104 USA
- To whom correspondence should be addressed at: Division of Human Genetics, The Children’s Hospital of Philadelphia, 3615 Civic Center Blvd, ARC 1002, Philadelphia, PA 19104, USA. Tel: +1 2155903856; Fax: +1 2155903764;
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143
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Marcon E, Moens P. MLH1p and MLH3p Localize to Precociously Induced Chiasmata of Okadaic-Acid-Treated Mouse Spermatocytes. Genetics 2003; 165:2283-7. [PMID: 14704203 PMCID: PMC1462919 DOI: 10.1093/genetics/165.4.2283] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
With the phosphatase inhibitor, okadaic acid, we induce the precocious onset of the chiasmate stage and under those conditions show that the recombination nodules, MLH1 and MLH3 foci, are localized to the chiasmata. It is concluded that MLH1/3 foci are appropriate markers for the studies of crossovers/chiasmata development and distribution at late meiotic prophase.
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Affiliation(s)
- Edyta Marcon
- Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
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144
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Oliver-Bonet M, Liehr T, Nietzel A, Heller A, Starke H, Claussen U, Codina-Pascual M, Pujol A, Abad C, Egozcue J, Navarro J, Benet J. Karyotyping of human synaptonemal complexes by cenM-FISH. Eur J Hum Genet 2003; 11:879-83. [PMID: 14571274 DOI: 10.1038/sj.ejhg.5201067] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The purpose of this work was to adapt the recently described centromere-specific multicolour (cenM-) FISH technique to human meiotic cells, and evaluate the usefulness of this multiplex fluorescence method for karyotyping human synaptonemal complex (SC), previously analysed by immunocytogenetic approaches. The results obtained demonstrate that cenM-FISH is a reliable one-single-step method, which allows for the identification of all SC present in pachytene spreads. Moreover, when cenM-FISH is applied after immunocytogenetic analysis, the number and distribution of MLH1 foci per chromosome can be established and recombination analysis for each chromosome can be performed easily.
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Affiliation(s)
- Maria Oliver-Bonet
- Unitat de Biologia, Facultat de Medicina, Departament de Biologia Cel.lular, Fisiologia i d'Immunologia, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
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