Biomedical subjects

Taizo Hogetsu

Publications and source records attributed to Taizo Hogetsu.

9 recordsLinked to original sources

PubMed2006

An improved technique for isolating codominant compound microsatellite markers.

An approach for developing codominant polymorphic markers (compound microsatellite (SSR) markers), with substantial time and cost savings, is introduced in this paper. In this technique, fragments flanked by a compound SSR sequence at one end were amplified from the constructed DNA library using compound SSR primer (AC)6(AG)5 or (TC)6(AC)5 and an adaptor primer for the suppression-PCR. A locus-specific primer was designed from the sequence flanking the compound SSR. The primer pairs of the locus-specific and compound SSR primers were used as a compound SSR marker. Because only one locus-specific primer was needed for design of each marker and only a common compound SSR primer was needed as the fluorescence-labeled primer for analyzing all the compound SSR markers, this approach substantially reduced the cost of developing codominant markers and analyzing their polymorphism. We have demonstrated this technique for Dendropanax trifidus and easily developed 11 codominant markers with high polymorphism for D. trifidus. Use of the technique for successful isolation of codominant compound SSR markers for several other plant species is currently in progress.

Araliaceae↗

PubMed2006

Tricholoma matsutake in a natural Pinus densiflora forest: correspondence between above- and below-ground genets, association with multiple host trees and alteration of existing ectomycorrhizal communities.

Tricholoma matsutake (matsutake) is an ectomycorrhizal (ECM) fungus that produces economically important mushrooms in Japan. Here, we use microsatellite markers to identify genets of matsutake sporocarps and below-ground ECM tips, as well as associated host genotypes of Pinus densiflora. We also studied ECM fungal community structure inside, beneath and outside the matsutake fairy rings, using morphological and internal transcribed spacer (ITS) polymorphism analysis. Based on sporocarp samples, one to four genets were found within each fairy ring, and no genetic differentiation among six sites was detected. Matsutake ECM tips were only found beneath fairy rings and corresponded with the genotypes of the above-ground sporocarps. We detected nine below-ground matsutake genets, all of which colonized multiple pine trees (three to seven trees per genet). The ECM fungal community beneath fairy rings was species-poor and significantly differed from those inside and outside the fairy rings. We conclude that matsutake genets occasionally establish from basidiospores and expand on the root systems of multiple host trees. Although matsutake mycelia suppress other ECM fungi during expansion, most of them may recover after the passage of the fairy rings.

Basidiomycota↗

PubMed2005

Genetic structure of Cenococcum geophilum populations in primary successional volcanic deserts on Mount Fuji as revealed by microsatellite markers.

Polymorphic simple sequence repeat (SSR) markers were used to investigate the genetic structure in a Cenococcum geophilum population associated with Salix reinii in an early successional volcanic desert at Gotenba, on the south-eastern slope of Mount Fuji in Japan, and in three other populations associated with the same host at more developed sites on the mountain, one at Fujinomiya and two at Subashiri. The genotype richness of C. geophilum tended to be higher in more developed vegetation patches as well as in more developed sites, suggesting that genotype richness increased with advanced succession because new genotypes might have been introduced into these sites over time. High genotypic similarity was observed between the Gotenba and Fujinomiya populations but not between the Gotenba and Subashiri populations, suggesting that C. geophilum genotypes in Gotenba were introduced from the direction of Fujinomiya. Genotypes in the Gotenba population were clearly distinguishable into two groups. The absence of any intermediate genotype suggests the absence of frequent recombination in this C. geophilum population associated with early successional vegetation.

Ascomycota↗

PubMed2004

Root hydraulic conductivity and whole-plant water balance in tropical saplings following a shade-to-sun transfer.

We hypothesized that pioneer and late successional species show different morphological and physiological responses in water use after gap formation. The magnitude of the responses was compared between two pioneer species (Macaranga gigantea and Trema orientalis) and four late successional species (Shorea sp.), in an experiment in which saplings were transferred from shade to sun. Although transpiration demand increased following the transfer, root hydraulic conductivity (Lp(r)) decreased. Lp(r) was sensitive to brief treatments with HgCl(2) (a specific inhibitor of aquaporins). This allows Lp(r) to be divided into two components: cell-to-cell and apoplastic pathways. The Lp(r) of cell-to-cell pathway decreased in all species following the transfer, relating to aquaporin depression in roots. Following the transfer, leaf osmotic potentials at full hydration decreased and both leaf mass per area [leaf mass/leaf area (LMA)] and fine-root surface area/leaf surface area (root SA/leaf SA) increased in almost all species, allowing saplings to compensate for the decrease in Lp(r). Physiologically, pioneer species showed larger decreases in Lp(r) and more effective osmotic adjustment than late successional species, and morphologically, pioneer species showed larger increases in root SA/leaf SA and LMA. Water balance at the whole-plant level should be regulated by coupled responses between the aboveground and the belowground parts. Interspecific differences in responses after gap formation suggest niche differentiation in water use between pioneer and late successional species in accordance with canopy-gap size.

Analysis of Variance↗

PubMed2003

High somatic instability of a microsatellite locus in a clonal tree, Robinia pseudoacacia.

Robinia pseudoacacia L. is a clonal tree species. To investigate a mutation within eight microsatellite loci of R. pseudoacacia, we analyzed DNA samples obtained from different leaf samples within each ramet, leaves from ramets within the genet, and seeds. Of the eight loci, locus Rops15 (AG motif) displayed hypermutability. The mutation rates of Rops15 within each ramet, among ramets within the genet, and offspring were 6.27% (ranging from 0 to 31.1%), 6.11% (from 0 to 25.0%) and 3.78% (from 0 to 10.9%), respectively. The mutation rate increased with allele size (13-71 repeat units). The mutation patterns observed in Rops15 were distinctive in two ways. First, there was a significant bias toward additions over deletions, and both addition and deletion of single repeats were dominant at alleles with lengths less than 232 bp (63 repeats). Second, for the longest allele of 248 bp (71 repeats), the number of losses was higher than the number of gains. These observations suggest that the mutation patterns of microsatellites in R. pseudoacacia may follow a generalized stepwise mutation model, and that the tendency of long alleles to mutate to shorter lengths acts to prevent infinite growth. Finally, the observation of somatic hypermutability at locus Rops15 highlights the need for caution when using highly polymorphic microsatellites for population genetic structure and paternity analysis in tree species.

DNA Primers↗

PubMed2003

Genetic structure and reproduction dynamics of Salix reinii during primary succession on Mount Fuji, as revealed by nuclear and chloroplast microsatellite analysis.

The early stage of volcanic desert succession is underway on the southeastern slope of Mount Fuji. We used markers of nuclear microsatellites (simple sequence repeats; SSR) and chloroplast microsatellites (cpSSR) to investigate the population genetic structure and reproduction dynamics of Salix reinii, one of the dominant pioneer shrubs in this area. The number of S. reinii genets in a patch and the area of the largest genet within the patch increased with patch area, suggesting that both clonal growth and seedling recruitment are involved in the reproduction dynamics of S. reinii. Five polymorphic cpSSR markers were developed for S. reinii by sequencing the noncoding regions between universal sequences in the chloroplast genome. Nineteen different cpSSR haplotypes were identified, indicating that S. reinii pioneer genets were created by the long-distance dispersal of seeds originating from different mother genets around the study site, where all vegetation was destroyed during the last eruption. Furthermore, the clustered distributions of different haplotypes within each patch or plot suggested that newly colonized genets tended to be generated from seeds dispersed near the initially established mother genets. These results revealed that the establishment of the S. reinii population on the southeastern slope of Mount Fuji involved two sequential modes of seed dispersal: long-distance dispersal followed by short-distance dispersal.

Cell Nucleus↗

PubMed2003

Patch establishment and development of a clonal plant, Polygonum cuspidatum, on Mount Fuji.

Microsatellite analysis was used to investigate the patch establishment and development of Polygonum cuspidatum Sieb. et Zucc, a clonal herbaceous plant that dominates the primary succession on the southeast slope of Mount Fuji. Genotypes of P. cuspidatum in 155 patches at the study site differed from each other. This indicates that P. cuspidatum patches are initially established by seed dispersed on the bare scoria field, and not by clonal rhizome extension. Genetic differentiation was estimated using the FST values between subpopulations at the study site. There was almost no genetic differentiation between subpopulations, indicating the presence of massive gene flow. The pollen fathers of seeds and maternal genets of current-year seedlings were inferred from the microsatellite allele composition by a simple exclusion method. The wide, random distribution of pollen fathers suggests that pollen dispersal occurs over a broad area. Maternal analysis showed a tendency for seed dispersal to be biased to the area nearby and down slope from the mother plants. Patch establishment under massive gene flow may result from such pollen and seed dispersal. To understand the process of patch development, aerial photographs taken from 1962 to 1999 were compared, and then genets in each of 36 patches were identified from the microsatellite genotypes of P. cuspidatum shoots. The comparison of aerial photographs showed that most of the patches enlarged each year and that some neighbouring patches combined during growth. Genet analysis demonstrated a high correlation between patch area and the area of the largest genet within it, and that new genets were recruited at the patch periphery. These findings indicate that both vegetative and sexual reproduction, i.e. rhizome extension and the establishment of new seedlings, contribute to the development of P. cuspidatum patches.

Environment↗

PubMed2002

Development of microsatellite markers from an ectomycorrhizal fungus, Tricholoma matsutake, by an ISSR-suppression-PCR method.

An inter-simple sequence repeat (ISSR)-suppression-PCR technique established to develop microsatellite markers of plant species was applied to an ectomycorrhizal fungus, Tricholoma matsutake. Six polymorphic SSR markers were developed. All six polymorphic SSR markers were single-locused and co-dominant. Alleles produced by these six single-locused markers ranged from two to nine per locus and the expected heterozygosities were calculated as values from 0.098 to 0.803. The results indicated that the ISSR-suppression-PCR technique was effective and applicable to the development of microsatellite markers from ectomycorrhizal fungi. Furthermore, the six microsatellite loci did not amplify DNA from any other ectomycorrhizal species investigated, except for Tricholoma nauseosum (Swedish matsutake) and Tricholoma fulvocastaneum, suggesting that population genetics and reproduction of T. matsutake could be investigated by the SSR markers developed in the present study.

Basidiomycota↗

PubMed2002

Spatiotemporal transfer of carbon-14-labelled photosynthate from ectomycorrhizal Pinus densiflora seedlings to extraradical mycelia.

Seedlings of Pinus densiflora colonized by an unidentified ectomycorrhizal fungus (T01) were labelled photosynthetically with 14C. Movement of 14C-labelled photosynthates within the underground part of the seedlings was investigated by temporal autoradiography using an imaging plate. Within 1 day, 14C was transferred from the shoot to the underground part that included roots, mycorrhizae, and the extraradical mycelium; within 3 days, the 14C in the underground part reached its maximum density. Mycorrhizae and actively growing root tips were large C sinks. Three days after 14C labelling, counts of 14C radioactivity in the underground part of the mycorrhizal seedlings were 2.6 times those of nonmycorrhizal seedlings. The mycorrhizae of mycorrhizal plants accumulated 5.2 times the 14C counts in the short-root tips of nonmycorrhizal plants. 14C counts in various areas of the extraradical mycelium demonstrated that all 14C-photosynthate transfer from the host root to the extraradical mycelium occurred within 3 days after 14C labelling, and that there was only a short lag of < 1 day between 14C accumulation in the basal and distal parts of the mycelium. Although more 14C accumulated in the distal than in the basal parts, 14C counts per unit hyphal biomass were similar between the two. These results suggest that 14C spread rapidly throughout the entire mycelium. Thirteen days after 14C labelling, we estimated 14C allocation to extraradical mycelia by taking autoradiographs after removing host roots. About 24% of 14C counts in the underground part of the mycorrhizal seedlings had been allocated to extraradical mycelia in this system, indicating that the fugal mycelium is an important sink for photosynthates.

Autoradiography↗