The Experts below are selected from a list of 1179 Experts worldwide ranked by ideXlab platform
Godeleine Faugeron - One of the best experts on this subject based on the ideXlab platform.
-
Histone H1 is dispensable for methylation-associated gene silencing in Ascobolus immersus and essential for long life span.
Molecular and Cellular Biology, 2000Co-Authors: Jose L. Barra, Jean-luc Rossignol, Laïla Rhounim, Godeleine FaugeronAbstract:A gene encoding a protein that shows sequence similarity with the histone H1 family only was cloned in Ascobolus immersus. The deduced peptide sequence presents the characteristic three-domain structure of metazoan linker histones, with a central globular region, an N-terminal tail, and a long positively charged C-terminal tail. By constructing an artificial duplication of this gene, named H1, it was possible to methylate and silence it by the MIP (methylation induced premeiotically) process. This resulted in the complete loss of the Ascobolus H1 histone. Mutant strains lacking H1 displayed normal methylation-associated gene silencing, underwent MIP, and showed the same methylation-associated chromatin modifications as did wild-type strains. However, they displayed an increased accessibility of micrococcal nuclease to chromatin, whether DNA was methylated or not, and exhibited a hypermethylation of the methylated genome compartment. These features are taken to imply that Ascobolus H1 histone is a ubiquitous component of chromatin which plays no role in methylation-associated gene silencing. Mutant strains lacking histone H1 reproduced normally through sexual crosses and displayed normal early vegetative growth. However, between 6 and 13 days after germination, they abruptly and consistently stopped growing, indicating that Ascobolus H1 histone is necessary for long life span. This constitutes the first observation of a physiologically important phenotype associated with the loss of H1.
-
Masc2, a gene from Ascobolus encoding a protein with a DNA‐methyltransferase activity in vitro, is dispensable for in vivo methylation
Molecular Microbiology, 1999Co-Authors: Fabienne Malagnac, Christophe Goyon, Jean-luc Rossignol, Annie Grégoire, Godeleine FaugeronAbstract:We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
-
masc2 a gene from Ascobolus encoding a protein with a dna methyltransferase activity in vitro is dispensable for in vivo methylation
Molecular Microbiology, 1999Co-Authors: Fabienne Malagnac, Christophe Goyon, Jean-luc Rossignol, Annie Grégoire, Godeleine FaugeronAbstract:We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
-
NATIVE DNA REPEATS AND METHYLATION IN Ascobolus
Nucleic Acids Research, 1996Co-Authors: Christophe Goyon, Jean-luc Rossignol, Godeleine FaugeronAbstract:We identified two classes of native dispersed DNA repeats in the Ascobolus genome. The first class consisted of several kilobase long, methylated repeats. These repeats, named Mars (methylated Ascobolus repeated sequences), fell in one family of LINE-like elements and in three families of LTR-containing retrotransposable elements. The methylation features of Mars elements were those expected if they were natural targets for the MIP (methylation induced premeiotically) previously discovered in Ascobolus. The second class consisted of short repeats, approximately 100 bp long, corresponding to 5S rRNA and tRNA genes. As expected from their size, which was too small to allow MIP to occur, they were unmethylated, as were 26 kb of unique sequences tested. These observations are consistent with the hypothesis that MIP is targeted at natural DNA repeats and constitutes a defensive process against the detrimental consequences of the spreading of mobile elements throughout the genome. The 9 kb tandem repeats harbouring the 28S, 18S and 5.8S rRNA genes displayed methylation features suggesting that rDNA methylation proceeds through a process other than MIP.
-
Native DNA repeats and methylation in Ascobolus
1996Co-Authors: Christophe Goyon, Jean-luc Rossignol, Godeleine FaugeronAbstract:We identified two classes of native dispersed DNA repeats in the Ascobolus genome. The first class consisted of several kilobase long, methylated repeats. These repeats, named Mars (methylated Ascobolus repeated sequences), fell in one family of LINE-like elements and in three families of LTR-containing retrotransposable elements. The methylation features of Mars elements were those expected if they were natural targets for the MIP (methylation induced premeiotically) previously discovered in Ascobolus. The second class consisted of short repeats, ∼100 bp long, corresponding to 5S rRNA and tRNA genes. As expected from their size, which was too small to allow MIP to occur, they were unmethylated, as were 26 kb of unique sequences tested. These observations are consistent with the hypothesis that MIP is targeted at natural DNA repeats and constitutes a defensive process against the detrimental consequences of the spreading of mobile elements throughout the genome. The 9 kb tandem repeats harbouring the 28S, 18S and 5.8S rRNA genes displayed methylation features suggesting that rDNA methylation proceeds through a process other than MIP
Jean-luc Rossignol - One of the best experts on this subject based on the ideXlab platform.
-
Histone H1 is dispensable for methylation-associated gene silencing in Ascobolus immersus and essential for long life span.
Molecular and Cellular Biology, 2000Co-Authors: Jose L. Barra, Jean-luc Rossignol, Laïla Rhounim, Godeleine FaugeronAbstract:A gene encoding a protein that shows sequence similarity with the histone H1 family only was cloned in Ascobolus immersus. The deduced peptide sequence presents the characteristic three-domain structure of metazoan linker histones, with a central globular region, an N-terminal tail, and a long positively charged C-terminal tail. By constructing an artificial duplication of this gene, named H1, it was possible to methylate and silence it by the MIP (methylation induced premeiotically) process. This resulted in the complete loss of the Ascobolus H1 histone. Mutant strains lacking H1 displayed normal methylation-associated gene silencing, underwent MIP, and showed the same methylation-associated chromatin modifications as did wild-type strains. However, they displayed an increased accessibility of micrococcal nuclease to chromatin, whether DNA was methylated or not, and exhibited a hypermethylation of the methylated genome compartment. These features are taken to imply that Ascobolus H1 histone is a ubiquitous component of chromatin which plays no role in methylation-associated gene silencing. Mutant strains lacking histone H1 reproduced normally through sexual crosses and displayed normal early vegetative growth. However, between 6 and 13 days after germination, they abruptly and consistently stopped growing, indicating that Ascobolus H1 histone is necessary for long life span. This constitutes the first observation of a physiologically important phenotype associated with the loss of H1.
-
Masc2, a gene from Ascobolus encoding a protein with a DNA‐methyltransferase activity in vitro, is dispensable for in vivo methylation
Molecular Microbiology, 1999Co-Authors: Fabienne Malagnac, Christophe Goyon, Jean-luc Rossignol, Annie Grégoire, Godeleine FaugeronAbstract:We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
-
masc2 a gene from Ascobolus encoding a protein with a dna methyltransferase activity in vitro is dispensable for in vivo methylation
Molecular Microbiology, 1999Co-Authors: Fabienne Malagnac, Christophe Goyon, Jean-luc Rossignol, Annie Grégoire, Godeleine FaugeronAbstract:We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
-
Suppression of crossing-over by DNA methylation in Ascobolus
Genes & Development, 1998Co-Authors: Laurent Maloisel, Jean-luc RossignolAbstract:Homologous recombination between dispersed DNA repeats creates chromosomal rearrangements that are deleterious to the genome. The methylation associated with DNA repeats in many eukaryotes might serve to inhibit homologous recombination and play a role in preserving genome integrity. We have tested the hypothesis that DNA methylation suppresses meiotic recombination in the fungus Ascobolus immersus. The natural process of methylation-induced premeiotically (MIP) was used to methylate the b2 spore color gene, a 7.5-kb chromosomal recombination hot spot. The frequency of crossing-over between two markers flanking b2 was reduced several hundredfold when b2 was methylated on the two homologs. This demonstrates that DNA methylation strongly inhibits homologous recombination. When b2 was methylated on one homolog only, crossing-over was still reduced 50-fold, indicating that the effect of methylation cannot be limited to the blocking of initiation of recombination on the methylated homolog. On the basis of these and other observations, we propose that DNA methylation perturbs pairing between the two intact homologs before recombination initiation and/or impairs the normal processing of recombination intermediates.
-
NATIVE DNA REPEATS AND METHYLATION IN Ascobolus
Nucleic Acids Research, 1996Co-Authors: Christophe Goyon, Jean-luc Rossignol, Godeleine FaugeronAbstract:We identified two classes of native dispersed DNA repeats in the Ascobolus genome. The first class consisted of several kilobase long, methylated repeats. These repeats, named Mars (methylated Ascobolus repeated sequences), fell in one family of LINE-like elements and in three families of LTR-containing retrotransposable elements. The methylation features of Mars elements were those expected if they were natural targets for the MIP (methylation induced premeiotically) previously discovered in Ascobolus. The second class consisted of short repeats, approximately 100 bp long, corresponding to 5S rRNA and tRNA genes. As expected from their size, which was too small to allow MIP to occur, they were unmethylated, as were 26 kb of unique sequences tested. These observations are consistent with the hypothesis that MIP is targeted at natural DNA repeats and constitutes a defensive process against the detrimental consequences of the spreading of mobile elements throughout the genome. The 9 kb tandem repeats harbouring the 28S, 18S and 5.8S rRNA genes displayed methylation features suggesting that rDNA methylation proceeds through a process other than MIP.
Christophe Goyon - One of the best experts on this subject based on the ideXlab platform.
-
Masc2, a gene from Ascobolus encoding a protein with a DNA‐methyltransferase activity in vitro, is dispensable for in vivo methylation
Molecular Microbiology, 1999Co-Authors: Fabienne Malagnac, Christophe Goyon, Jean-luc Rossignol, Annie Grégoire, Godeleine FaugeronAbstract:We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
-
masc2 a gene from Ascobolus encoding a protein with a dna methyltransferase activity in vitro is dispensable for in vivo methylation
Molecular Microbiology, 1999Co-Authors: Fabienne Malagnac, Christophe Goyon, Jean-luc Rossignol, Annie Grégoire, Godeleine FaugeronAbstract:We have shown previously that masc1, a gene encoding a putative C5-DNA-methyltransferase (MTase), was necessary for the de novo 'Methylation Induced Premeiotically' (MIP) process and sexual reproduction in Ascobolus, whereas it was dispensable for maintenance methylation. A second MTase gene from Ascobolus, masc2, encodes a protein, Masc2, which possesses the large amino-terminal part characteristic of eukaryotic maintenance MTases. In vitro assays have shown that Masc2 displays a methylation activity, suggesting that it might be the MTase responsible for maintenance methylation. To check its function in vivo, we engineered a disruption of the masc2 gene. The resulting mutant strains did not exhibit any particular phenotype during either vegetative growth or sexual reproduction. Neither the masc2 mutation nor the double masc1 masc2 mutation had any detectable effect upon the maintenance of the pre-existing methylation of single gene copies previously subjected to MIP, natural retroelement-like repeats and tandemly repeated rDNA. The masc2 mutation did not alter either MIP or the other de novo methylation process that operates in vegetatives cells. Nor did it impair the meiotic process of methylation transfer. These results suggest that at least a third MTase gene responsible for maintenance and vegetative de novo methylation is present in Ascobolus.
-
NATIVE DNA REPEATS AND METHYLATION IN Ascobolus
Nucleic Acids Research, 1996Co-Authors: Christophe Goyon, Jean-luc Rossignol, Godeleine FaugeronAbstract:We identified two classes of native dispersed DNA repeats in the Ascobolus genome. The first class consisted of several kilobase long, methylated repeats. These repeats, named Mars (methylated Ascobolus repeated sequences), fell in one family of LINE-like elements and in three families of LTR-containing retrotransposable elements. The methylation features of Mars elements were those expected if they were natural targets for the MIP (methylation induced premeiotically) previously discovered in Ascobolus. The second class consisted of short repeats, approximately 100 bp long, corresponding to 5S rRNA and tRNA genes. As expected from their size, which was too small to allow MIP to occur, they were unmethylated, as were 26 kb of unique sequences tested. These observations are consistent with the hypothesis that MIP is targeted at natural DNA repeats and constitutes a defensive process against the detrimental consequences of the spreading of mobile elements throughout the genome. The 9 kb tandem repeats harbouring the 28S, 18S and 5.8S rRNA genes displayed methylation features suggesting that rDNA methylation proceeds through a process other than MIP.
-
Native DNA repeats and methylation in Ascobolus
1996Co-Authors: Christophe Goyon, Jean-luc Rossignol, Godeleine FaugeronAbstract:We identified two classes of native dispersed DNA repeats in the Ascobolus genome. The first class consisted of several kilobase long, methylated repeats. These repeats, named Mars (methylated Ascobolus repeated sequences), fell in one family of LINE-like elements and in three families of LTR-containing retrotransposable elements. The methylation features of Mars elements were those expected if they were natural targets for the MIP (methylation induced premeiotically) previously discovered in Ascobolus. The second class consisted of short repeats, ∼100 bp long, corresponding to 5S rRNA and tRNA genes. As expected from their size, which was too small to allow MIP to occur, they were unmethylated, as were 26 kb of unique sequences tested. These observations are consistent with the hypothesis that MIP is targeted at natural DNA repeats and constitutes a defensive process against the detrimental consequences of the spreading of mobile elements throughout the genome. The 9 kb tandem repeats harbouring the 28S, 18S and 5.8S rRNA genes displayed methylation features suggesting that rDNA methylation proceeds through a process other than MIP
-
Cloning and sequence of the Ascobolus immersus S-adenosyl-L-methionine synthetase-encoding gene.
Gene, 1996Co-Authors: Mario R. Mautino, Christophe Goyon, Alberto L. RosaAbstract:Abstract The structural gene encoding S-adenosyl- l -methionine synthetase (SAM-S) in the fungus Ascobolus immersus has been cloned and sequenced. It contains a 1179-bp ORF, interrupted by three introns, encoding a 393-amino-acid protein (42 978 Da) that is 90% homologous to the SAM-S of the filamentous fungus Neurospora crassa, indicating that these fungi are closely related species
Yasin Uzun - One of the best experts on this subject based on the ideXlab platform.
-
New Ascomycete records for Turkish macromycota
Turkish Journal of Botany, 2012Co-Authors: Ilgaz Akata, Abdullah Kaya, Yasin UzunAbstract:Ascobolus stercorarius (Bull.) J.Schrot. (Ascobolaceae), Cheilymenia fimicola (De Not. & Bagl.) Dennis (Pyronemataceae), Plectania melastoma (Sowerby) Fuckel, and P. rhytidia (Berk.) Nannf. & Korf (Sarcosomataceae) are given as new records at the genus level for the macromycota of Turkey.
-
Türkiye makromikotası için yeni Askomiset kayıtları
2012Co-Authors: Ilgaz Akata, Abdullah Kaya, Yasin UzunAbstract:Ascobolus stercorarius (Bull.) J.Schröt. (Ascobolaceae), Cheilymenia fimicola (De Not. & Bagl.) Dennis (Pyronemataceae), Plectania melastoma (Sowerby) Fuckel ve P. rhytidia (Berk.) Nannf. & Korf (Sarcosomataceae) cins düzeyinde Türkiye makromikotası için yeni kayıt olarak verilmiştir.Ascobolus stercorarius (Bull.) J.Schröt. (Ascobolaceae), Cheilymenia fimicola (De Not. & Bagl.) Dennis (Pyronemataceae), Plectania melastoma (Sowerby) Fuckel ve P. rhytidia (Berk.) Nannf. & Korf (Sarcosomataceae) cins düzeyinde Türkiye makromikotası için yeni kayıt olarak verilmiştir
J. Van Brummelen - One of the best experts on this subject based on the ideXlab platform.
-
Notes on cup-fungi—4. On two rare species of Ascobolus
2016Co-Authors: J. Van BrummelenAbstract:Rijksherbarium, Leiden Ascobolus carletonii is recorded and studied from Brazil and A. hawaiiensis from Pakistan. Both are described and comparedwith authentic collections. Ascobolus carletonii Boud. — Fig. 1 H a b i t a t.—On dung of Capybara hydrochaeris. Also known from dung ofcapercaillie and grouse in Scodand. Specimens examin e d.—GREAT BRITAIN, Scotland, 'Inverness ' (probably Perthshire ac-cording to Richardson (1972)), Dunkeld, on dung of capercaillie ( Tetrao urogalli), 18.X.1912, C. Rea (type, PC). — BRAZIL, Pirai near Rio de Janeiro, on dung of Capybara hydrochaeris in moist chamber, 17.XI.1989, E.Jahn s.n. (L). The above description is based on the collection from Brazil, kindly sent by Mr E. Jahn. Ascobolus carletonii is a little known species and has not previously been recorded from Ascobolus carletonii Boud. in Trans. Br. mycol. Soc. 4: 62, pi. 2 fig. 1. 1913. Apothecia solitary or in small groups, superficial, sessile, 0.5-2 mm wide, 0.5-1 mm high. Receptacle at first subglobular and closed, then opening and cup-shaped, finally ex
-
Two rare coprophilous ascomycetes from Norway
Persoonia, 1998Co-Authors: J. Van Brummelen, R. KristiansenAbstract:Two uncommon coprophilous ascomycetes, Ascobolus cervinus and Caccobius minusculus, only recorded once, each from two different continents, are reported for the first time from Norway. Both are provided with new descriptions and compared with authentic material.
-
Notes on cup-fungi—4. On two rare species of Ascobolus
Persoonia, 1990Co-Authors: J. Van BrummelenAbstract:Ascobolus carletonii is recorded and studied from Brazil and A. hawaiiensis from Pakistan. Both are described and compared with authentic collections.
-
notes on cup fungi 4 on two rare species of Ascobolus
Persoonia, 1990Co-Authors: J. Van BrummelenAbstract:Ascobolus carletonii is recorded and studied from Brazil and A. hawaiiensis from Pakistan. Both are described and compared with authentic collections.