The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Jouko Rikkinen - One of the best experts on this subject based on the ideXlab platform.
-
relationships between mycobiont identity photobiont specificity and ecological preferences in the lichen genus peltigera ascomycota in estonia northeastern europe
Fungal Ecology, 2019Co-Authors: Inga Juriado, Ulla Kaasalainen, Maarit Johanna Jylha, Jouko RikkinenAbstract:Abstract We studied the genotype diversity of cyanobacterial symbionts in the predominately terricolous cyanolichen genus Peltigera (Peltigerales, Lecanoromycetes) in Estonia. Our sampling comprised 252 lichen specimens collected in grasslands and forests from different parts of the country, which represented all common Peltigera taxa in the region. The cyanobacteria were grouped according to their tRNALeu (UAA) intron sequences, and mycobiont identities were confirmed using fungal ITS sequences. The studied Peltigera species associated with 34 different “Peltigera-type” Nostoc trnL genotypes. Some Peltigera species associated with one or a few trnL genotypes while others associated with a much wider range of genotypes. Mycobiont identity was the primary factor that determined the presence of the specific Nostoc genotype within the studied Peltigera thalli. However, the species-specific patterns of cyanobiont selectivity did not always reflect phylogenetic relationships among the studied fungal species but correlated instead with habitat preferences. Several taxa from different sections of the genus Peltigera were associated with the same Nostoc genotype or with genotypes in the same habitat, indicating the presence of functional guild structure in the photobiont community. Some Nostoc trnL genotypes were only found in the Peltigera species of moist and mesic forest environments, while another set of Nostoc genotypes was typically found in the Peltigera species of xeric habitats. Some Nostoc trnL genotypes were only found in the Peltigera taxa that are common on alvars and may have specialized to living in this unusual and threatened habitat type.
-
microcystin production in the tripartite cyanolichen peltigera leucophlebia
Molecular Plant-microbe Interactions, 2009Co-Authors: Ulla Kaasalainen, Jouni Jokela, David P Fewer, Kaarina Sivonen, Jouko RikkinenAbstract:We show that the cyanobacterial symbionts of a tripartite cyanolichen can produce hepatotoxic microcystins in situ. Microcystins were detected with high-performance liquid chromatography mass spectrometry both from cephalodia of the tripartite cyanolichen Peltigera leucophlebia and from a symbiotic Nostoc strain isolated from the same lichen specimen. Genetic identities of symbiotic Nostoc strains were studied by amplifying and sequencing the 16S rRNA gene. Also, the presence of the microcystin synthetase gene mcyE was confirmed by sequencing. Three highly toxic microcystins were detected from the lichen specimen. Several different Nostoc 16S rRNA haplotypes were present in the lichen sample but only one was found in the toxin-producing cultures. In culture, the toxin-producing Nostoc strain produced a total of 19 different microcystin variants. In phylogenetic analysis, this cyanobacterium and related strains from the lichen thallus grouped together with a previously known microcystin-producing Nostoc st...
-
discovery of rare and highly toxic microcystins from lichen associated cyanobacterium Nostoc sp strain io 102 i
Applied and Environmental Microbiology, 2004Co-Authors: Ilona Oksanen, Jouko Rikkinen, Jouni Jokela, David P Fewer, Matti Wahlsten, Kaarina SivonenAbstract:The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. Here we show that a terrestrial cyanobacterium Nostoc sp. strain IO-102-I isolated from a lichen association produces six different microcystins. Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp. strain 152. The dominant microcystin produced by Nostoc sp. strain IO-102-I was the highly toxic [ADMAdda 5 ]microcystin-LR, which accounted for ca. 80% of the total microcystins. We assigned a structure of [DMAdda 5 ]microcystin-LR and [D-Asp 3 ,ADMAdda 5 ]microcystin-LR and a partial structure of three new [ADMAdda 5 ]-XR type of microcystin variants. Interestingly, Nostoc spp. strains IO-102-I and 152 synthesized only the rare ADMAdda and DMAdda subfamilies of microcystin variants. Phylogenetic analyses demonstrated congruence between genes involved directly in microcystin biosynthesis and the 16S rRNA and rpoC1 genes of Nostoc sp. strain IO-102-I. Nostoc sp. strain 152 and the Nostoc sp. strain IO-102-I are distantly related, revealing a sporadic distribution of toxin production in the genus Nostoc. Nostoc sp. strain IO-102-I is closely related to Nostoc punctiforme PCC 73102 and other symbiotic Nostoc strains and most likely belongs to this species. Together, this suggests that other terrestrial and aquatic strains of the genus Nostoc may have retained the genes necessary for microcystin biosynthesis.
-
Genetic Diversity of Nostoc Symbionts Endophytically Associated with Two Bryophyte Species
Applied and Environmental Microbiology, 2001Co-Authors: José Luis Costa, Jouko Rikkinen, Per Paulsrud, Peter LindbladAbstract:The diversity of the endophytic Nostoc symbionts of two thalloid bryophytes, the hornwort Anthoceros fusiformis and the liverwort Blasia pusilla, was examined using the tRNALeu (UAA) intron sequence as a marker. The results confirmed that many different Nostoc strains are involved in both associations under natural conditions in the field. The level of Nostoc diversity within individual bryophyte thalli varied, but single DNA fragments were consistently amplified from individual symbiotic colonies. Some Nostoc strains were widespread and were detected from thalli collected from different field sites and different years. These findings indicate a moderate level of spatial and temporal continuity in bryophyte-Nostoc symbioses.
-
cyanobiont specificity in some Nostoc containing lichens and in a peltigera aphthosa photosymbiodeme
New Phytologist, 1998Co-Authors: Per Paulsrud, Jouko Rikkinen, Peter LindbladAbstract:The cyanobacterial symbionts in some Nostoc-containing lichens were investigated using the nucleotide sequence of the highly variable cyanobacterial tRNALeu (UAA) intron. When comparing different Nostoc-containing lichens, identical intron sequences were found in different samples of the same lichen species collected from two remote areas. This was true for all species where this comparison was made (Peltigera aphthosa (L.) Willd., P. canina (L.) Willd. and Nephroma arcticum (L.) Torss.). With one exception, a specific intron sequence was never found in more than one lichen species. However, for two of the species, Peltigera aphthosa and Nephroma arcticum, two different cyanobionts were found in different samples. By examining a P. aphthosa photosymbiodeme it could be shown that the same Nostoc is present in both bipartite and tripartite lobes of this lichen. It is thus possible for one cyanobiont/Nostoc to form the physiologically different symbioses that are found in bipartite and tripartite lichens. The connection between photobiont identity and secondary chemistry is discussed, as a correlation between differences in secondary chemistry and different cyanobionts/Nostocs in the species Peltigera neopolydactyla (Gyeln.) Gyeln. was observed. It is concluded that more knowledge concerning the photobiont will give us valuable information on many aspects of lichen biology.
Peter Lindblad - One of the best experts on this subject based on the ideXlab platform.
-
quantitative overview of n2 fixation in Nostoc punctiforme atcc 29133 through cellular enrichments and itraq shotgun proteomics
Journal of Proteome Research, 2009Co-Authors: Saw Yen Ow, Peter Lindblad, Karin Stensjö, Josselin Noirel, Tanai Cardona, Arnaud Taton, Phillip C WrightAbstract:Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the capacity to fix atmospheric N2. Its ability to mediate this process is similar to that described for Nostoc sp. PCC 7120, where vegetative cells differentiate into heterocysts. Quantitative proteomic investigations at both the filament level and the heterocyst level are presented using isobaric tagging technology (iTRAQ), with 721 proteins at the 95% confidence interval quantified across both studies. Observations from both experiments yielded findings confirmatory of both transcriptional studies, and published Nostoc sp. PCC 7120 iTRAQ data. N. punctiforme exhibits similar metabolic trends, though changes in a number of metabolic pathways are less pronounced than in Nostoc sp. PCC 7120. Results also suggest a number of proteins that may benefit from future investigations. These include ATP dependent Zn-proteases, N-reserve degraders and also redox balance proteins. Complementary proteomic data sets from both organisms present key...
-
Genetic Diversity of Nostoc Symbionts Endophytically Associated with Two Bryophyte Species
Applied and Environmental Microbiology, 2001Co-Authors: José Luis Costa, Jouko Rikkinen, Per Paulsrud, Peter LindbladAbstract:The diversity of the endophytic Nostoc symbionts of two thalloid bryophytes, the hornwort Anthoceros fusiformis and the liverwort Blasia pusilla, was examined using the tRNALeu (UAA) intron sequence as a marker. The results confirmed that many different Nostoc strains are involved in both associations under natural conditions in the field. The level of Nostoc diversity within individual bryophyte thalli varied, but single DNA fragments were consistently amplified from individual symbiotic colonies. Some Nostoc strains were widespread and were detected from thalli collected from different field sites and different years. These findings indicate a moderate level of spatial and temporal continuity in bryophyte-Nostoc symbioses.
-
Transcriptional regulation of Nostoc uptake hydrogenase
Fems Microbiology Letters, 1999Co-Authors: Rikard Axelsson, Fredrik Oxelfelt, Peter LindbladAbstract:Filamentous, heterocystous cyanobacteria may contain both an uptake hydrogenase (encoded by hupSL) and a bidirectional enzyme (encoded by hoxFUYH). The present study identifies three strains (Anabaena variabilis, Nostoc muscorum and Nostoc sp. strain PCC 73102) with a contiguous hupL in both vegetative cells and heterocysts. The two Nostoc strains differ in either containing a bidirectional enzyme (N. muscorum) or lacking this enzyme (N. PCC 73102). Transcriptional studies, using reverse transcriptase-polymerase chain reaction, demonstrated an induction of a hupL transcript approximately 24 h after a shift from non-nitrogen-fixing to nitrogen-fixing conditions (in parallel with the induction of an in vivo light-dependent H2-uptake activity) in N. muscorum. However, the level of hoxH transcripts did not change significantly during the induction of the H2-uptake activity.
-
Nostoc PCC 73102 and H2
BioHydrogen, 1998Co-Authors: Peter Lindblad, Paula Tamagnini, Fredrik Oxelfelt, Alfred Hansel, Olga TroshinaAbstract:In N2-fixing cyanobacteria, at least three enzymes may be involved in H2 metabolism: (a) nitrogenase, evolving H2 during N2 fixation; (b) an uptake hydrogenase, reutilizing this H2; and (c) a bidirectional (reversible) hydrogenase. Our studies focus on the hydrogen metabolism of the filamentous, heterocystous cyanobacterium Nostoc PCC 73102, a free-living strain originally isolated from coralloid roots of the Australian cycad, Macrozamia. Immunological studies using polyclonal antisera directed against hydrogenases purified from several different microorganisms indicated the presence of two native enzymes/forms in N2-fixing cells of Nostoc PCC 73102, with at least one common subunit of approximately 58 kDa. Moreover, a cellular localization in both the N2-fixing heterocysts and the vegetative cells was observed. Measurements with an H2 electrode revealed the presence of a light-stimulated in vivo H2 uptake in N2-fixing cells of Nostoc PCC 73102. We have identified and sequenced genes encoding an uptake hydrogenase (hupSL) in Nostoc PCC 73102. They are highly homologous to corresponding genes in Anabaena PCC 7120. However, there is no rearrangement within hupL. Using both molecular and physiological techniques, it was not possible to demonstrate any evidence of the presence of either hox genes or corresponding bidirectional enzyme activities in Nostoc PCC 73102. This fact, together with the availability of the genes encoding an uptake hydrogenase, makes Nostoc PCC 73102 an interesting candidate for further molecular studies of its hydrogen metabolism.
-
cyanobiont specificity in some Nostoc containing lichens and in a peltigera aphthosa photosymbiodeme
New Phytologist, 1998Co-Authors: Per Paulsrud, Jouko Rikkinen, Peter LindbladAbstract:The cyanobacterial symbionts in some Nostoc-containing lichens were investigated using the nucleotide sequence of the highly variable cyanobacterial tRNALeu (UAA) intron. When comparing different Nostoc-containing lichens, identical intron sequences were found in different samples of the same lichen species collected from two remote areas. This was true for all species where this comparison was made (Peltigera aphthosa (L.) Willd., P. canina (L.) Willd. and Nephroma arcticum (L.) Torss.). With one exception, a specific intron sequence was never found in more than one lichen species. However, for two of the species, Peltigera aphthosa and Nephroma arcticum, two different cyanobionts were found in different samples. By examining a P. aphthosa photosymbiodeme it could be shown that the same Nostoc is present in both bipartite and tripartite lobes of this lichen. It is thus possible for one cyanobiont/Nostoc to form the physiologically different symbioses that are found in bipartite and tripartite lichens. The connection between photobiont identity and secondary chemistry is discussed, as a correlation between differences in secondary chemistry and different cyanobionts/Nostocs in the species Peltigera neopolydactyla (Gyeln.) Gyeln. was observed. It is concluded that more knowledge concerning the photobiont will give us valuable information on many aspects of lichen biology.
Phillip C Wright - One of the best experts on this subject based on the ideXlab platform.
-
quantitative overview of n2 fixation in Nostoc punctiforme atcc 29133 through cellular enrichments and itraq shotgun proteomics
Journal of Proteome Research, 2009Co-Authors: Saw Yen Ow, Peter Lindblad, Karin Stensjö, Josselin Noirel, Tanai Cardona, Arnaud Taton, Phillip C WrightAbstract:Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the capacity to fix atmospheric N2. Its ability to mediate this process is similar to that described for Nostoc sp. PCC 7120, where vegetative cells differentiate into heterocysts. Quantitative proteomic investigations at both the filament level and the heterocyst level are presented using isobaric tagging technology (iTRAQ), with 721 proteins at the 95% confidence interval quantified across both studies. Observations from both experiments yielded findings confirmatory of both transcriptional studies, and published Nostoc sp. PCC 7120 iTRAQ data. N. punctiforme exhibits similar metabolic trends, though changes in a number of metabolic pathways are less pronounced than in Nostoc sp. PCC 7120. Results also suggest a number of proteins that may benefit from future investigations. These include ATP dependent Zn-proteases, N-reserve degraders and also redox balance proteins. Complementary proteomic data sets from both organisms present key...
Karin Stensjö - One of the best experts on this subject based on the ideXlab platform.
-
Diversity and transcription of proteases involved in the maturation of hydrogenases in Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133
BMC Microbiology, 2020Co-Authors: Karin Stensjö, Ellenor DevineAbstract:Diversity and transcription of proteases involved in the maturation of hydrogenases in Nostoc sp. strain PCC 7120 and Nostoc punctiforme ATCC 29133
-
quantitative overview of n2 fixation in Nostoc punctiforme atcc 29133 through cellular enrichments and itraq shotgun proteomics
Journal of Proteome Research, 2009Co-Authors: Saw Yen Ow, Peter Lindblad, Karin Stensjö, Josselin Noirel, Tanai Cardona, Arnaud Taton, Phillip C WrightAbstract:Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the capacity to fix atmospheric N2. Its ability to mediate this process is similar to that described for Nostoc sp. PCC 7120, where vegetative cells differentiate into heterocysts. Quantitative proteomic investigations at both the filament level and the heterocyst level are presented using isobaric tagging technology (iTRAQ), with 721 proteins at the 95% confidence interval quantified across both studies. Observations from both experiments yielded findings confirmatory of both transcriptional studies, and published Nostoc sp. PCC 7120 iTRAQ data. N. punctiforme exhibits similar metabolic trends, though changes in a number of metabolic pathways are less pronounced than in Nostoc sp. PCC 7120. Results also suggest a number of proteins that may benefit from future investigations. These include ATP dependent Zn-proteases, N-reserve degraders and also redox balance proteins. Complementary proteomic data sets from both organisms present key...
Saw Yen Ow - One of the best experts on this subject based on the ideXlab platform.
-
quantitative overview of n2 fixation in Nostoc punctiforme atcc 29133 through cellular enrichments and itraq shotgun proteomics
Journal of Proteome Research, 2009Co-Authors: Saw Yen Ow, Peter Lindblad, Karin Stensjö, Josselin Noirel, Tanai Cardona, Arnaud Taton, Phillip C WrightAbstract:Nostoc punctiforme ATCC 29133 is a photoautotrophic cyanobacterium with the capacity to fix atmospheric N2. Its ability to mediate this process is similar to that described for Nostoc sp. PCC 7120, where vegetative cells differentiate into heterocysts. Quantitative proteomic investigations at both the filament level and the heterocyst level are presented using isobaric tagging technology (iTRAQ), with 721 proteins at the 95% confidence interval quantified across both studies. Observations from both experiments yielded findings confirmatory of both transcriptional studies, and published Nostoc sp. PCC 7120 iTRAQ data. N. punctiforme exhibits similar metabolic trends, though changes in a number of metabolic pathways are less pronounced than in Nostoc sp. PCC 7120. Results also suggest a number of proteins that may benefit from future investigations. These include ATP dependent Zn-proteases, N-reserve degraders and also redox balance proteins. Complementary proteomic data sets from both organisms present key...
