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1.
Distribution of Antagonistic Streptomyces griseoviridis in Rhizosphere and Nonrhizosphere Sand 总被引:1,自引:0,他引:1
The ability of Streptomyces griseoviridis to colonize roots was studied on turnip rape (Brassica rapa ssp. oleifera) and carrot (Daucus carota) using the sand-tube method. The biofungicide Mycostop or a spore suspension of S. griseoviridis was mixed in sterile and in non-sterile sand. Population densities of the antagonist in the rhizosphere were significantly higher than in non-rhizosphere and in root-free sand. There was no significant difference between the plant species and root depths on distrubution of the antagonist. Higher rates of detection were achieved when root segments were placed on petri plates of agar than when homogenized and subsequently dilution plated. Homogenization of sand samples increased the detected population densities of S. griseoviridis. Muramic acid assay with HPLC indicated higher densities in the rhizosphere compared with non-rhizosphere and rootfree sand. Distribution of S. griseoviridis in the rhizosphere was observed using scanning electron microscopy. The antagonist produced high spore densities in the root-hair zone of turnip rape. S. griseoviridis mixed in sterile and non-sterile sand survives in the rhizosphere, non-rhizosphere and root-free sand where it probably exists both as spores and mycelia. 相似文献
2.
Despite their ecological relevance, field studies of the extraradical mycelia of ectomycorrhizal (ECM) fungi are rare. Here we examined in situ interactions between ECM mycelia and host vigour. Ectomycorrhizal mycelia were harvested with in-growth mesh bags buried under Norway spruce (Picea abies) clones planted in 1994 in a randomized block design. Mycelial biomass was determined and fungal species were identified by denaturing gradient gel electrophoresis (DGGE) and sequencing of the internal transcribed spacer 1 (ITS1) region. Microbial community structure in the mycelium was investigated by phospholipid fatty acid (PLFA) profiling. Compared to slow-growing spruce clones, fast-growing clones tended to support denser mycelia where the relative proportions of Atheliaceae fungi and PLFAs indicative of Gram-positive bacteria were higher. Ascomycetes and PLFAs representative of Gram-negative bacteria were more common with slow-growing clones. In general, the ECM mycelial community was similar to the ECM root-tip community. Growth rate of the hosts, the ECM mycelial community and the microbes associated with the mycelium were related, suggesting multitrophic interactions between trees, fungi and bacteria. 相似文献
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Marie C. Nyman Annele O. Sainio Mirka M. Pennanen Riikka J. Lund Sanna Vuorikoski Jari T. T. Sundstr?m Hannu T. J?rvel?inen 《The journal of histochemistry and cytochemistry》2015,63(9):710-720
Decorin is generally recognized as a tumor suppressing molecule. Nevertheless, although decorin has been shown to be differentially expressed in malignant tissues, it has often remained unclear whether, in addition to non-malignant stromal cells, cancer cells also express it. Here, we first used two publicly available databases to analyze the current information about decorin expression and immunoreactivity in normal and malignant human colorectal tissue samples. The analyses demonstrated that decorin expression and immunoreactivity may vary in cancer cells of human colorectal tissues. Therefore, we next examined decorin expression in normal, premalignant and malignant human colorectal tissues in more detail using both in situ hybridization and immunohistochemistry for decorin. Our results invariably demonstrate that malignant cells within human colorectal cancer tissues are devoid of both decorin mRNA and immunoreactivity. Identical results were obtained for cells of neuroendocrine tumors of human colon. Using RT-qPCR, we showed that human colon cancer cell lines are also decorin negative, in accordance with the above in vivo results. Finally, we demonstrate that decorin transduction of human colon cancer cell lines causes a significant reduction in their colony forming capability. Thus, strategies to develop decorin-based adjuvant therapies for human colorectal malignancies are highly rational. 相似文献
5.
Tiina Rajala Mikko Peltoniemi Jarkko Hantula Raisa Mäkipää Taina Pennanen 《Fungal Ecology》2011,4(6):437-448
Current knowledge of the succession of fungi in decaying wood is mostly based on fruit bodies and in vitro culture. Here, we investigated the changing community of metabolically active fungi during the decomposition of fallen Picea abies logs by directly extracting and barcode sequencing precursor rRNA. We also compared rRNA-derived amplicons of the 18S and ITS regions in 21 isolates and discuss the use of RNA as a marker of metabolically active fungi. The richness of active fungi, revealed as separated bands in DGGE, peaked in logs at an advanced stage of decay. Soft-rot fungi were common in the early stages but white- and brown-rot fungi became dominant as decay progressed. Ectomycorrhizal fungi were detected at an early stage, and they became the most abundant group in the late stages of succession. A comparison of rRNA-derived amplicons revealed that although ITS was detected in the form of precursor rRNA, introns within 18S rDNA were already spliced. As such, rRNA- and rDNA-derived amplicons would yield different profiles of active and total communities if profiling method is affected by amplicon length. 相似文献
6.
Impaired spatial reference memory and increased exploratory behavior in P301L tau transgenic mice 总被引:2,自引:0,他引:2
The neuropathological hallmark shared between Alzheimer's disease (AD) and familial frontotemporal dementia (FTDP-17) are neurofibrillary tangles (NFT) which are composed of filamentous aggregates of the microtubule-associated protein tau. Their formation has been reproduced in transgenic mice, which express the FTDP-17-associated mutation P301L of tau. In these mice, tau aggregates are found in many brain areas including the hippocampus and the amygdala, both of which are characterized by NFT formation in AD. Previous studies using an amygdala-specific test battery revealed an increase in exploratory behavior and an accelerated extinction of conditioned taste aversion in these mice. Here, we assessed P301L mice in behavioral tests known to depend on an intact hippocampus. Morris water maze and Y-maze revealed intact spatial working memory but impairment in spatial reference memory at 6 and 11 months of age. In addition, a modest disinhibition of exploratory behavior at 6 months of age was confirmed in the open field and the elevated O-maze and was more pronounced during aging. 相似文献
7.
Lu-Min Vaario Taina Pennanen Tytti Sarjala Eira-Maija Savonen Jussi Heinonsalo 《Mycorrhiza》2010,20(7):511-518
This study aimed to test the ability of Tricholoma matsutake isolates to form mycorrhizas with aseptic seedlings of Pinus sylvestris L. and Picea abies (L.) Karst. Germinated seedlings of Scots pine and Norway spruce were separately inoculated with either isolates originating from Finland
or Japan. Eight months after inoculation, the Finnish isolate had formed a sheath and Hartig net on both host species. Ectomycorrhizal
Scots pine seedlings inoculated with the Finnish isolate showed the same shoot height and dry mass as the controls. Ectomycorrhizal
Norway spruce seedlings inoculated with the Finnish isolate had similar shoot height but slightly less dry mass than the control
seedlings. For both tree species, inoculation with the Finnish isolate resulted in reduced total nitrogen content per seedling,
but carbon content was unaffected. Inoculation with the Japanese isolate resulted in an initial Hartig net-like structure
in pine but not in spruce. No typical Hartig net was observed on either tree species. Furthermore, seedlings of both species
inoculated with the Japanese isolate showed significantly reduced growth, dry mass, nitrogen, and carbon content per seedling
and shoot height (in spruce) compared to the controls. This study documents and describes the in vitro ectomycorrhization
between T. matsutake and Scots pine or Norway spruce and the variable mycorrhizal structures that matsutake isolates can form. 相似文献
8.
Joseph C. V. Vu Jeffrey T. Baker Arja H. Pennanen L. Hartwell Allen Jr George Bowes Kenneth J. Boote 《Physiologia plantarum》1998,103(3):327-339
Rice (Oryza sativa[L.] cv. IR-72) was grown for a season in sunlit, controlled-environment chambers at 350 or 700 µmol CO2 mol?1 under continuously flooded (unstressed) or drought-imposed periods at panicle initiation (stressed). The midday canopy photosynthetic rates (Pn), measured at the CO2 concentration ([CO2]) used for growth, were enhanced by high [CO2] but reduced by drought. High [CO2] increased Pn by 18 to 34% for the unstressed plants, and 6 to 12% for the stressed plants. In the unstressed plants, CO2 enrichment increased water-use efficiency (WUE) by 26%, and reduced evapotranspiration (ET) by 8 to 14%. Both high [CO2] and severe drought decreased the activity and content of ribulose bisphosphate carboxylase-oxygenase (Rubisco). High-CO2-unstressed plants had 6 to 22% smaller content and 5 to 25%, lower activity of Rubisco than ambient-CO2-unstressed plants. Under severe drought, reductions of Rubisco were 53 and 27% in activity and 40 and 12% in content, respectively, for ambient- and high-CO2 treatments. The apparent catalytic turnover rate (Kcat) of midday fully activated Rubisco was not altered by high [CO2], but severe drought reduced Kcat by 17 to 23%. Chloroplasts of the high-CO2 leaves contained more, and larger starch grains than those of the ambient CO2 leaves. High [CO2] did not affect the leaf sucrose content of unstressed plants. In contrast, severe drought reduced the leaf starch and increased the sucrose content in both CO2 treatments. The activity of leaf sucrose phosphate synthase of unstressed plants was not affected by high [CO2], whereas that of ambient-CO2-grown plants was reduced 45% by severe drought. Reduction in ET and enhancements in both Pn and WUE for rice grown under high [CO2] helped to delay the adverse effects of severe drought and allowed the stressed plants to assimilate CO2 for an extra day. Thus, rice grown in the next century may utilize less water, use water more efficiently, and be able to tolerate drought better under some situations. 相似文献
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Talis Gaitnieks Darta Klavina Indrikis Muiznieks Taina Pennanen Sannakajsa Velmala Rimvydas Vasaitis Audrius Menkis 《Mycorrhiza》2016,26(5):465-473
We examined differences in fine root morphology, mycorrhizal colonisation and root-inhabiting fungal communities between Picea abies individuals infected by Heterobasidion root-rot compared with healthy individuals in four stands on peat soils in Latvia. We hypothesised that decreased tree vitality and alteration in supply of photosynthates belowground due to root-rot infection might lead to changes in fungal communities of tree roots. Plots were established in places where trees were infected and in places where they were healthy. Within each stand, five replicate soil cores with roots were taken to 20 cm depth in each root-rot infected and uninfected plot. Root morphological parameters, mycorrhizal colonisation and associated fungal communities, and soil chemical properties were analysed. In three stands root morphological parameters and in all stands root mycorrhizal colonisation were similar between root-rot infected and uninfected plots. In one stand, there were significant differences in root morphological parameters between root-rot infected versus uninfected plots, but these were likely due to significant differences in soil chemical properties between the plots. Sequencing of the internal transcribed spacer of fungal nuclear rDNA from ectomycorrhizal (ECM) root morphotypes of P. abies revealed the presence of 42 fungal species, among which ECM basidiomycetes Tylospora asterophora (24.6 % of fine roots examined), Amphinema byssoides (14.5 %) and Russula sapinea (9.7 %) were most common. Within each stand, the richness of fungal species and the composition of fungal communities in root-rot infected versus uninfected plots were similar. In conclusion, Heterobasidion root-rot had little or no effect on fine root morphology, mycorrhizal colonisation and composition of fungal communities in fine roots of P. abies growing on peat soils. 相似文献
10.
Outi Priha Susan J. Grayston Taina Pennanen Aino Smolander 《FEMS microbiology ecology》1999,30(2):187-199