SEX-LIMITED EXPRESSION OF GENE LOCI CONTROLLING FLAGELLAR MEMBRANE AGGLUTINATION IN THE CHLAMYDOMONAS MATING REACTION

ABSTRACT Mutant strains of Chlamydomonas reinhardi that have lost their ability to undergo sexual agglutination via their flagellar tips have been induced to undergo zygotic cell fusion and meiosis, using a flagellar-directed antiserum. Genetic analysis of antiserum-mediated crosses involving five nonagglutinating mt + mutant strains reveals the following: (1) None of the mutations is linked to the mt locus. (2) All of the mutations are "sex-limited," meaning that they can be carried and transmitted by, but not expressed in, mt - cells. (3) Four of the mutations (imp-2, imp-5, imp-6, imp-7) are either allelic or closely linked to one another, with imp-8 defining a second locus.

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ISOLATION AND GENETIC ANALYSIS OF MUTANT STRAINS OF CHLAMYDOMONAS REINHARDI DEFECTIVE IN GAMETIC DIFFERENTIATION

Genetics ◽

10.1093/genetics/82.2.169 ◽

1976 ◽

Vol 82 (2) ◽

pp. 169-186

Author(s):

Ursula W Goodenough ◽

Carol Hwang ◽

Howard Martin

Keyword(s):

Genetic Analysis ◽

Cell Fusion ◽

Mating Type ◽

Normal Growth ◽

The Other ◽

Genetic Dissection ◽

Structural Studies ◽

Tetrad Analysis ◽

Mating Structure ◽

Mutant Strains

ABSTRACT Impotent mutant strains of Chlamydomonas reinhardi, mating-type (mt) plus, are described that have normal growth and motility but fail to differentiate into normal gametes. Procedures for their isolation and their genetic analysis are described. Five of the imp strains (imp-2, imp-5, imp-6, imp-7, and imp-8) exhibit no flagellar agglutination when mixed with mt - or mt + gametes; these strains have been induced to form rare zygotes with mt - gametes and the mutations are shown to be unlinked to the mt locus (with the possible exception of imp-7). Two of the strains (imp-3 and imp-4) carry leaky mutations that affect cell fusion; neither mutation is found by tetrad analysis to be linked to mt or to the other. Cells of the imp-1 strain agglutinate well with mt - gametes and active agglutination continues for up to 48 hours, but cell fusion occurs only very rarely. Analysis of these rare zygotes indicates that imp-1 is closely linked to the mt + locus, and fine-structural studies reveal that imp-1gametes produce a mutant mating structure involved in zygotic cell fusion. The development of sexuality in C. reinhardi therefore appears amenable to genetic dissection.

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Tipping and mating-structure activation induced in Chlamydomonas gametes by flagellar membrane antisera.

The Journal of Cell Biology ◽

10.1083/jcb.79.3.680 ◽

1978 ◽

Vol 79 (3) ◽

pp. 680-693 ◽

Cited By ~ 53

Author(s):

U W Goodenough ◽

D Jurivich

Keyword(s):

Mating Type ◽

Dynamic Properties ◽

Cross Linking ◽

Mating Types ◽

Vegetative Cells ◽

Sexual Agglutination ◽

Sexual Agglutinability ◽

Flagellar Membrane ◽

Mutant Strains ◽

High Concentrations

Antisera raised against vegetative and gametic flagella of Chlamydomonas reinhardi have been used to probe dynamic properties of the flagellar membranes. The antisera, which agglutinate cells via their flagella, associate with antigens that are present on both vegetative and gametic membranes and on membranes of both mating types (mt+ and mt-). Gametic cells respond to antibody presentation very differently from vegetative cells, mobilizing even high concentrations of antibody towards the flagellar tips; the possibility is discussed that such "tipping" ability reflects a differentiated gametic property relevant to sexual agglutinability. Gametic cells also respond to antibody agglutination by activating their mating structures, the mt+ reaction involving a rapid polymerization of microfilaments. Several impotent mt+ mutant strains that fail to agglutinate sexually are also activated by the antisera and procede to form zygotes with normal mt- gametes. Fusion does not occur between activated cells of like mating type. Monovalent (Fab) preparations of the antibody fail to activate mt+ gametes, suggesting that the cross-linking properties of the antisera are essential for their ability to mimic, or bypass, sexual agglutination.

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Phenotypic and Genetic Analysis of “Chameleon,” a Paramecium Mutant With an Enhanced Sensitivity to Magnesium

Genetics ◽

10.1093/genetics/146.3.871 ◽

1997 ◽

Vol 146 (3) ◽

pp. 871-880

Author(s):

Robin R Preston ◽

Jocelyn A Hammond

Keyword(s):

Genetic Analysis ◽

Single Locus ◽

Behavioral Analysis ◽

Paramecium Tetraurelia ◽

Wild Type ◽

Ion Conductance ◽

Membrane Excitation ◽

Enhanced Sensitivity ◽

Electrophysiological Analysis ◽

Mutant Strains

Three mutant strains of Paramecium tetraurelia with an enhanced sensitivity to magnesium have been isolated. These new “Chameleon” mutants result from partial- or codominant mutations at a single locus, Cha. Whereas the wild type responded to 5 mm Mg2+ by swimming backward for 10–15 sec, Cha mutants responded with ∼30 sec backward swimming. Electrophysiological analysis suggested that this behavior may be caused by slowing in the rate at which a Mg2+-specific ion conductance deactivates following membrane excitation. This would be consistent with an observed increase in the sensitivity of Cha mutants to nickel poisoning, since Ni2+ is also able to enter the cell via this pathway. More extensive behavioral analysis showed that Cha cells also overresponded to Na+, but there was no evidence for a defect in intracellular Ca2+ homeostasis that might account for a simultaneous enhancement of both the Mg2+ and Na+ conductances. The possibility that the Cha locus may encode a specific regulator of the Mg2+- and Na+-permeabilities is considered.

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ISOLATION AND GENETIC ANALYSIS OF MMS-SENSITIVE MUS MUTANTS OF NEUROSPORA

Canadian Journal of Genetics and Cytology ◽

10.1139/g80-060 ◽

1980 ◽

Vol 22 (4) ◽

pp. 535-552 ◽

Cited By ~ 24

Author(s):

E. Käfer ◽

E. Perlmutter

Keyword(s):

Dna Repair ◽

Linkage Group ◽

Genetic Analysis ◽

Double Mutant ◽

Excision Repair ◽

Methylmethane Sulfonate ◽

New Genes ◽

Mutant Strains ◽

Error Prone Repair ◽

Isogenic Strains

With the aim of obtaining mutants that affect DNA repair or recombination, mutants sensitive to methylmethane sulfonate (MMS) have been isolated in the ascomycete Neurospora crassa. Seven of these mutants were backcrossed repeatedly to produce isogenic strains for measurements of relative mutagen sensitivities and for analysis of recombination frequencies. The new mus (mutagen sensitives) were compared to four previously known radiation-sensitive mutants which were shown to be cross-sensitive to MMS. Tests for allelism assigned the mus mutants to five new genes, mus-7 to mus-11, each mapping in a different linkage group. In homozygous crosses all mutants were sterile, except the two alleles of gene mus-10 which occasionally produced some viable ascospores. Complementation tests on MMS-media identified double mutant strains from many intercrosses. Such strains can be used for analysis of interactions between mutant alleles from different genes and of possible epistatic groupings for repair-deficient mutants in Neurospora. Four of these double mutant strains, all containing mus-8 and previously known mutants, were checked for survival on MMS media and their sensitivities were compared to those of their parental single mutant strains. Results indicate that mus-8 may be epistatic to uvs-2 which is deficient in excision repair, but not to mutants like uvs-3 that appear to be deficient in error-prone repair.

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Genetic analysis based on cell fusion.

KAGAKU TO SEIBUTSU ◽

10.1271/kagakutoseibutsu1962.28.647 ◽

1990 ◽

Vol 28 (10) ◽

pp. 647-654

Author(s):

Takahito SUZUKI

Keyword(s):

Genetic Analysis ◽

Cell Fusion

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LINKAGE OF MUTATIONS AFFECTING MINUS FLAGELLAR MEMBRANE AGGLUTINABILITY TO THE mt - MATING-TYPE LOCUS OF CHLAMYDOMONAS

Genetics ◽

10.1093/genetics/99.1.41 ◽

1981 ◽

Vol 99 (1) ◽

pp. 41-47 ◽

Cited By ~ 1

Author(s):

Carol J Hwang ◽

Brian C Monk ◽

Ursula W Goodenough

Keyword(s):

Uv Irradiation ◽

Mating Type ◽

Zygote Formation ◽

Wild Type ◽

Tetrad Analysis ◽

Type Locus ◽

Mating Type Locus ◽

Flagellar Membrane ◽

Mutant Strains

ABSTRACT Two independently isolated mutant strains, imp-10 and imp-12, were obtained by UV irradiation of wild-type mating-type minus (wt-). Each fails to agglutinate sexually with gametes of either mating type, but mating and zygote formation can be elicited by agglutinating either strain to wt+ gametes by means of anti-flagellar antiserum. Tetrad analysis of the resultant zygotes shows that both imp-10 and imp-12 are very closely linked to mt -, with no recombinants observed. Diploid strains constructed between imp-10 or imp-12 and wt+ gametes are wt-, that is, they agglutinate and fuse like normal minus cells. Tetrad analysis of triploids from imp-10 diploid x wt+ haploid crosses shows that only imp-10 and wt+ products are recovered. A model is proposed to account for these results.

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SWI/SNF Binding to the HO Promoter Requires Histone Acetylation and Stimulates TATA-Binding Protein Recruitment

Molecular and Cellular Biology ◽

10.1128/mcb.01849-05 ◽

2006 ◽

Vol 26 (11) ◽

pp. 4095-4110 ◽

Cited By ~ 53

Author(s):

Doyel Mitra ◽

Emily J. Parnell ◽

Jack W. Landon ◽

Yaxin Yu ◽

David J. Stillman

Keyword(s):

Genetic Analysis ◽

Histone Acetylation ◽

Chromatin Immunoprecipitation ◽

Histone Acetyltransferase ◽

Binding Protein ◽

Tata Binding Protein ◽

Gain Of Function ◽

Mutant Strains ◽

Mother Cells ◽

Protein Recruitment

ABSTRACT We use chromatin immunoprecipitation assays to show that the Gcn5 histone acetyltransferase in SAGA is required for SWI/SNF association with the HO promoter and that binding of SWI/SNF and SAGA are interdependent. Previous results showed that SWI/SNF binding to HO was Gcn5 independent, but that work used a strain with a mutation in the Ash1 daughter-specific repressor of HO expression. Here, we show that Ash1 functions as a repressor that inhibits SWI/SNF binding and that Gcn5 is required to overcome Ash1 repression in mother cells to allow HO transcription. Thus, Gcn5 facilitates SWI/SNF binding by antagonizing Ash1. Similarly, a mutation in SIN3, like an ash1 mutation, allows both HO expression and SWI/SNF binding in the absence of Gcn5. Although Ash1 has recently been identified in a Sin3-Rpd3 complex, our genetic analysis shows that Ash1 and Sin3 have distinct functions in regulating HO. Analysis of mutant strains shows that SWI/SNF binding and HO expression are correlated and regulated by histone acetylation. The defect in HO expression caused by a mutant SWI/SNF with a Swi2(E834K) substitution can be partially suppressed by ash1 or spt3 mutation or by a gain-of-function V71E substitution in the TATA-binding protein (TBP). Spt3 inhibits TBP binding at HO, and genetic analysis suggests that Spt3 and TBP(V71E) act in the same pathway, distinct from that of Ash1. We have detected SWI/SNF binding at the HO TATA region, and our results suggest that SWI/SNF, either directly or indirectly, facilitates TBP binding at HO.

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