A Hypomorphic Mutant of PHD Domain Protein Male Meiocytes Death 1

Meiosis drives reciprocal genetic exchanges and produces gametes with halved chromosome number, which is important for the genetic diversity, plant viability, and ploidy consistency of flowering plants. Alterations in chromosome dynamics and/or cytokinesis during meiosis may lead to meiotic restitution and the formation of unreduced microspores. In this study, we isolated an Arabidopsis mutant male meiotic restitution 1 (mmr1), which produces a small subpopulation of diploid or polyploid pollen grains. Cytological analysis revealed that mmr1 produces dyads, triads, and monads indicative of male meiotic restitution. Both homologous chromosomes and sister chromatids in mmr1 are separated normally, but chromosome condensation at metaphase I is slightly affected. The mmr1 mutant displayed incomplete meiotic cytokinesis. Supportively, immunostaining of the microtubular cytoskeleton showed that the spindle organization at anaphase II and mini-phragmoplast formation at telophase II are aberrant. The causative mutation in mmr1 was mapped to chromosome 1 at the chromatin regulator Male Meiocyte Death 1 (MMD1/DUET) locus. mmr1 contains a C-to-T transition at the third exon of MMD1/DUET at the genomic position 2168 bp from the start codon, which causes an amino acid change G618D that locates in the conserved PHD-finger domain of histone binding proteins. The F1 progenies of mmr1 crossing with knockout mmd1/duet mutant exhibited same meiotic defects and similar meiotic restitution rate as mmr1. Taken together, we here report a hypomorphic mmd1/duet allele that typically shows defects in microtubule organization and cytokinesis.

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Characterization of a New Arabidopsis Mutant Exhibiting Enhanced Disease Resistance

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1999.12.12.1053 ◽

1999 ◽

Vol 12 (12) ◽

pp. 1053-1063 ◽

Cited By ~ 33

Author(s):

Herman Silva ◽

Keiko Yoshioka ◽

Hugo K. Dooner ◽

Daniel F. Klessig

Keyword(s):

Disease Resistance ◽

Fungal Pathogens ◽

Constitutive Expression ◽

Signal Transduction Pathway ◽

Chromosome 1 ◽

Recessive Trait ◽

Pr Genes ◽

Enhanced Resistance ◽

Arabidopsis Mutant ◽

Plant Pathogen Interactions

In many plant-pathogen interactions, resistance is associated with the synthesis and accumulation of salicylic acid (SA) and pathogenesis-related (PR) proteins. At least two general classes of mutants with altered resistance to pathogen attack have been identified in Arabidopsis. One class exhibits increased susceptibility to pathogen infection; the other class exhibits enhanced resistance to pathogens. In an attempt to identify mutations in resistance-associated loci, we screened a population of T-DNA tagged Arabidopsis thaliana ecotype Wassilewskija (Ws) for mutants showing constitutive expression of the PR-1 gene (cep). A mutant was isolated and shown to constitutively express PR-1, PR-2, and PR-5 genes. This constitutive phenotype segregated as a single recessive trait in the Ws genetic background. The mutant also had elevated levels of SA, which are responsible for the cep phenotype. The cep mutant spontaneously formed hypersensitive response (HR)-like lesions on the leaves and cotyledons and also exhibited enhanced resistance to virulent bacterial and fungal pathogens. Genetic analyses of segregating progeny from outcrosses to other ecotypes unexpectedly revealed that alterations in more than one gene condition the constitutive expression of PR genes in the original mutant. One of the mutations, designated cpr20, maps to the lower arm of chromosome 4 and is required for the cep phenotype. Another mutation, which has been termed cpr21, maps to chromosome 1 and is often, but not always, associated with this phenotype. The recessive nature of the cep trait suggests that the CPR20 and CPR21 proteins may act as negative regulators in the disease resistance signal transduction pathway.

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IDENTIFICATION OF GENOMIC REGIONS CARRYING A CAUSAL MUTATION IN UNORDERED GENOMES

10.1101/026856 ◽

2015 ◽

Author(s):

Pilar Corredor-Moreno ◽

Ed Chalstrey ◽

Carlos A Lugo ◽

Dan MacLean

Keyword(s):

High Throughput Sequencing ◽

Chromosome 1 ◽

Causative Mutation ◽

Genetic Screens ◽

Distribution Method ◽

Forward Genetic Screens ◽

Causal Mutation ◽

Genomic Regions ◽

User Friendly ◽

Mapping By Sequencing

Whole genome sequencing using high-throughput sequencing (HTS) technologies offers powerful opportunities to study genetic variation. Mapping the mutations responsible for different phenotypes is generally an involved and time-consuming process so researchers have developed user-friendly tools for mapping-by-sequencing, yet they are not applica- ble to organisms with non-sequenced genomes. We introduce SDM (SNP Distribution Method), a reference independent method for rapid discovery of mutagen-induced muta- tions in typical forward genetic screens. SDM aims to order a disordered collection of HTS reads or contigs such that the fragment carrying the causative mutation can be identified. SDM uses typical distributions of homozygous SNPs that are linked to a phenotype-altering SNP in a non-recombinant region as a model to order the fragments. To implement and test SDM, we created model genomes with an idealised SNP density based on Arabidop- sis thaliana chromosome 1 and analysed fragments with size distribution similar to reads or contigs assembled from HTS sequencing experiments. SDM groups the contigs by their normalised SNP density and arranges them to maximise the fit to the expected SNP distribution. We tested the procedure in existing datasets by examining SNP distributions in recent out-cross and back-cross experiments in Arabidopsis thaliana backgrounds. In all the examples we analysed, homozygous SNPs were normally distributed around the causal mutation. We used the real SNP densities obtained from these experiments to prove the efficiency and accuracy of SDM. The algorithm was able to successfully identify small sized (10-100 kb) genomic regions containing the causative mutation.

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High Temperature-induced Spindle Destabilization Results in Aborted Pollen Production in Populus

10.21203/rs.3.rs-940050/v1 ◽

2021 ◽

Author(s):

Zhiqun Li ◽

Yifan Zhao ◽

Xuetong Cheng ◽

Bo Kong ◽

Yaru Sang ◽

...

Keyword(s):

High Temperature ◽

Chromosome Segregation ◽

2N Gametes ◽

Male Flower ◽

Pollen Grains ◽

Pollen Abortion ◽

Duration Of Treatment ◽

Male Gametes ◽

Microtubular Cytoskeleton ◽

Spindle Microtubules

Abstract High temperature can induce the production of 2n gametes and aborted pollen during microsporogenesis in Populus canescens. However, the mechanism by which high temperature induces pollen abortion remains unknown. Here, pollen abortion was induced by exposing male flower buds of P. canescens to 38 and 41 °C; pollen morphology, meiotic abnormalities, defects of the meiotic microtubular cytoskeleton, and tapetum development were characterized, and expression analysis of the Actin gene was conducted. We found that the dominant meiotic stage, temperature, and duration of treatment significantly affected the percentage of high temperature-induced aborted pollen. Damaged spindle microtubules and depolymerized microtubular cytoskeletons were observed, which resulted in many lagging chromosomes at anaphase Ⅰ and Ⅱ, as well as aneuploid male gametes and micronuclei, generating aborted pollen grains. Tapetum disintegration was also delayed. However, the anther dehisced normally, and some viable pollen grains were released, suggesting that the delayed degradation of the tapetum was not responsible for pollen abortion. A significant reduction in PtActin gene expression was detected in treated cells, indicating that spindle actin was disrupted. The spindle actin appeared to protect cells against chromosome segregation errors during meiosis.

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Disturbances in microsporogenesis and pollen grain development in Gagea lutea (L.) Ker. Gaw.

Acta Agrobotanica ◽

10.5586/aa.2006.007 ◽

2012 ◽

Vol 59 (1) ◽

pp. 71-82 ◽

Cited By ~ 2

Author(s):

Ewa Szczuka ◽

Jerzy Bohdanowicz ◽

Joanna Świerczyńska ◽

Jolanta Sobieska ◽

Jacek Pietrusiewicz

Keyword(s):

Abiotic Factors ◽

Pollen Grains ◽

Pollen Grain ◽

External Factors ◽

Grain Development ◽

Excitation Light ◽

Gagea Lutea ◽

Microtubular Cytoskeleton ◽

Sterile Pollen ◽

Autumn And Winter

The meiotic division of microsporocytes and pollen grain development in <i>Gagea lutea</i> (L.) Ker.-Gaw. (Liliaceae) with fluorescence microscope (excitation light 400 nm) was observed after squashing the anthers in DAPI solution (fluorochrom dying DNA). Up to 70% of microsporocytes and pollen grains during the microsporogenesis and pollen grain development take a regular course. In the remaining microsporocytes and pollen grains (30%) the disturbances in course of both processes were observed. The most often observed disturbances are "late" chromosomes and a presence of micronuclei. The divisions of microsporocytes in the anther loculi show a big asynchrony, which, like the disturbances during the course of microsporogenesis and pollen grain development, may be caused by the external factors. The microsporogenesis takes place during autumn and winter months: the pollen grains develop in winter. At this time the dividing microsporocytes and developing pollen grains are under the influence of abiotic factors as low temperature and a lack of water. These factors disturb the formation of microtubular cytoskeleton of the dividing microsporocytes and pollen grains, which causes the formation of sterile pollen grains.

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Variation in the Caprine KAP24-1 Gene Affects Cashmere Fibre Diameter

Animals ◽

10.3390/ani9010015 ◽

2019 ◽

Vol 9 (1) ◽

pp. 15 ◽

Cited By ~ 5

Author(s):

Jiqing Wang ◽

Huitong Zhou ◽

Yuzhu Luo ◽

Mengli Zhao ◽

Hua Gong ◽

...

Keyword(s):

Dna Sequences ◽

Fibre Diameter ◽

Pcr Amplification ◽

Pcr Primers ◽

Single Strand Conformation Polymorphism ◽

Chromosome 1 ◽

Start Codon ◽

Nucleotide Polymorphisms ◽

Coding Region ◽

Cashmere Goats

The keratin-associated proteins (KAPs) are structural components of cashmere fibres. The gene encoding the high-sulphur (HS)-KAP24-1 (KRTAP24-1) has been identified in humans and sheep, but it has not been described in goats. In this study, we report the identification of caprine KRTAP24-1, describe variation in this gene, and investigate the effect of this variation on cashmere traits. A search for sequences orthologous to the ovine gene in the goat genome revealed a 774 bp open reading frame on chromosome 1, which could encode an HS-KAP. Based on this goat genome sequence and comparison with ovine KRTAP24-1 sequences, polymerase chain reaction (PCR) primers were designed to amplify an 856 bp fragment that would contain the entire coding region of the putative caprine KRTAP24-1. Use of this PCR amplification with subsequent single-strand conformation polymorphism (SSCP) analysis of the amplicons identified four distinct patterns of DNA bands on gel electrophoresis, with these representing four different DNA sequences (A to D), in 340 Longdong cashmere goats reared in China. The variant sequences had the highest similarity to KRTAP24-1 sequences from sheep and humans, suggesting that they are variants of caprine KRTAP24-1. Nine single-nucleotide polymorphisms (SNPs) were detected in the gene, including four non-synonymous SNPs and an SNP in proximity to the ATG start codon. Of the three common genotypes (AA, AB, and BB) found in these Longdong cashmere goats, cashmere fibres from goats of genotype AA had lower mean fibre diameter (MFD) than did those of genotype AB, and cashmere fibres from goats of genotype AB had lower MFD than did those from goats of genotype BB.

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Ethylnitrosourea-Induced Mutation in Mice Leads to the Expression of a Novel Protein in the Eye and to Dominant Cataracts

Genetics ◽

10.1093/genetics/157.3.1313 ◽

2001 ◽

Vol 157 (3) ◽

pp. 1313-1320 ◽

Cited By ~ 1

Author(s):

Jochen Graw ◽

Norman Klopp ◽

Jana Löster ◽

Dian Soewarto ◽

Helmut Fuchs ◽

...

Keyword(s):

Amino Acids ◽

Polyclonal Antibodies ◽

Chromosome 1 ◽

Start Codon ◽

Eye Lens ◽

The Novel ◽

Specific Expression ◽

Induced Mutation ◽

Encoding Gene ◽

Novel Protein

Abstract A novel ENU-induced mutation in the mouse leading to a nuclear and zonular opacity of the eye lens (Aey1) was mapped to chromosome 1 between the markers D1Mit303 and D1Mit332. On the basis of the chromosomal position, the γ-crystallin encoding gene cluster (Cryg) and the βA2-crystallin encoding gene Cryba2 were tested as candidate genes. An A → T mutation destroys the start codon of the Cryge gene in the mutants; this mutation was confirmed by the absence of a restriction site for NcoI in the corresponding genomic fragment of homozygous mutants. The next in-frame start codon is 129 bp downstream; this predicted truncated γE-crystallin consists of 131 amino acids, resulting in a molecular mass of 14 kD. However, another open reading frame was observed just 19 bp downstream of the regular Cryge start codon, resulting in a protein of 119 amino acids and a calculated molecular weight of 13 kD. Western blot analysis using polyclonal antibodies against γ-crystallins or the novel Aey1-specific protein demonstrated the specific expression of the Aey1 protein in the cataractous lenses only; the truncated form of the γE-crystallin could not be detected. Therefore, it is concluded that the novel protein destroys the sensitive cellular structure of the eye lens.

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Case Report: Partial Uniparental Disomy Unmasks a Novel Recessive Mutation in the LYST Gene in a Patient With a Severe Phenotype of Chédiak-Higashi Syndrome

Frontiers in Immunology ◽

10.3389/fimmu.2021.625591 ◽

2021 ◽

Vol 12 ◽

Author(s):

Mireia Boluda-Navarro ◽

Mariam Ibáñez ◽

Alessandro Liquori ◽

Clara Franco-Jarava ◽

Mónica Martínez-Gallo ◽

...

Keyword(s):

Uniparental Disomy ◽

Chromosome 1 ◽

Causative Mutation ◽

Recessive Mutation ◽

Homozygous Mutation ◽

Telomeric Region ◽

Severe Phenotype ◽

Immune Disorder ◽

Snp Arrays ◽

Chediak Higashi Syndrome

Chédiak-Higashi syndrome (CHS) is a rare autosomal recessive (AR) immune disorder that has usually been associated to missense, nonsense or indels mutations in the LYST gene. In this study, we describe for the first time the case of a CHS patient carrying a homozygous mutation in the LYST gene inherited as a result of a partial uniparental isodisomy (UPiD) of maternal origin. Sanger sequencing of the LYST cDNA and single nucleotide polymorphism (SNP)-arrays were performed to identify the causative mutation and to explain the molecular mechanism of inheritance, respectively. Partial-UPiD leads to a copy neutral loss of heterozygosity (CN-LOH) of the telomeric region of chromosome 1 (1q41q44), unmasking the potential effect of the mutation detected. The mutation (c.8380dupT) is an insertion located in exon 32 of the LYST gene resulting in a premature stop codon and leading to the loss of all the conserved domains at the C-terminal of the LYST protein. This would account for the severe phenotype observed. We also reviewed the only two previously reported cases of CHS as a result of a uniparental disomy. In this study, we show that the combination of different strategies, including the use of SNP-arrays, is pivotal to fine-tune the diagnosis of rare AR disorders, such as CHS. Moreover, this case highlights the relevance of uniparental disomy as a potential mechanism of CHS expression in non-consanguineous families.

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Isolation and characterization of a novel pollen-specific promoter in maize (Zea mays L.)

Genome ◽

10.1139/gen-2016-0089 ◽

2017 ◽

Vol 60 (6) ◽

pp. 485-495 ◽

Cited By ~ 5

Author(s):

He Wang ◽

Mingxia Fan ◽

Guohong Wang ◽

Chunyu Zhang ◽

Lei Shi ◽

...

Keyword(s):

Specific Activity ◽

Pollen Grains ◽

Start Codon ◽

Serine Threonine Kinase ◽

Kinase Gene ◽

Pollen Maturation ◽

Threonine Kinase ◽

Cis Element ◽

Isolation And Characterization

ZmSTK2_USP, located on the long arm of chromosome 4, belongs to the serine/threonine kinase gene in maize. The sequence analysis of 2100 bp upstream from the start codon ATG has shown that it contains cis-element motifs and two types of anther/pollen-specific promoter elements (GTGA and AGAAA), suggesting that it is the pollen-specific promoter. To investigate the function of ZmSTK2_USP promoter, the GUS gene fusion system was employed. In proZmSTK2_USP-GUS genetically modified plants, GUS activity was detected in mature pollen grains and pollen tubes but not found in other floral and vegetative tissues. These results show that proZmSTK2_USP is the pollen-specific promoter and drives pollen-specific activity during the middle stage of pollen development until pollen maturation.

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Resolution of Channels in the Exine by Translocation of Colloidal Iron

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065808 ◽

1971 ◽

Vol 29 ◽

pp. 352-353

Author(s):

John R. Rowley

Keyword(s):

Phosphate Buffer ◽

Pollen Development ◽

Osmium Tetroxide ◽

Pollen Grains ◽

Deionized Water ◽

Colloidal Iron ◽

Fixed Material ◽

Epilobium Angustifolium ◽

Untreated Material ◽

Microspore Mitosis

The morphology of the exine of many pollen grains, at the time of flowering, is such that one can suppose that transport of substances through the exine occurred during pollen development. Holes or channels, microscopic to submicroscopic, are described for a large number of grains. An inner part of the exine of Epilobium angustifolium L. and E. montanum L., which may be referred to as the endexine, has irregularly shaped channels early in pollen development although by microspore mitosis there is no indication of such channeling in chemically fixed material. The nucleus in microspores used in the experiment reported here was in prophase of microspore mitosis and the endexine, while lamellated in untreated grains, did not contain irregularly shaped channels. Untreated material from the same part of the inflorescence as iron treated stamens was examined following fixation with 0.1M glutaraldehyde in cacodylate-HCl buffer at pH 6.9 (315 milliosmoles) for 24 hrs, 4% formaldehyde in phosphate buffer at pH 7.2 (1,300 milliosmoles) for 12 hrs, 1% glutaraldehyde mixed with 0.1% osmium tetroxide for 20 min, osmium tetroxide in deionized water for 2 hrs and 1% glutaraldehyde mixed with 4% formaldehyde in 0.1M cacodylate-HCl buffer at pH 6.9 for two hrs.

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Freeze-substitution of rye grass and ragweed pollen grains

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160984 ◽

1990 ◽

Vol 48 (3) ◽

pp. 686-687

Author(s):

Liza B. Martinez ◽

Susan M. Wick

Keyword(s):

Cell Function ◽

Pollen Grains ◽

Freeze Substitution ◽

Cell Types ◽

Rapid Freezing ◽

Rye Grass ◽

Acrylic Resins ◽

Allergenic Proteins ◽

Cold Embedding ◽

Structural Preservation

Rapid freezing and freeze-substitution have been employed as alternatives to chemical fixation because of the improved structural preservation obtained in various cell types. This has been attributed to biomolecular immobilization derived from the extremely rapid arrest of cell function. These methods allow the elimination of conventionally used fixatives, which may have denaturing or “masking” effects on proteins. Thus, this makes them ideal techniques for immunocytochemistry, in which preservation of both ultrastructure and antigenicity are important. These procedures are also compatible with cold embedding acrylic resins which are known to increase sensitivity in immunolabelling.This study reveals how rapid freezing and freeze-substitution may prove to be useful in the study of the mobile allergenic proteins of rye grass and ragweed. Most studies have relied on the use of osmium tetroxide to achieve the necessary ultrastructural detail in pollen whereas those that omitted it have had to contend with poor overall preservation.

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