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51.
Host specificity between local Frankia strains and native alders [Alnus incana (L.) Moench and A. glutinosa (L.) Gaertn.] was evaluated in inoculation experiments. Pure cultures of Frankia , whether originating from A. incana or A. glutinosa , were infective and effective on both host species. These pure cultures were isolated from spore-negative (Sp− ) nodules. From spore-positive (Sp+ ) nodules no Frankia isolates were obtained. This strain type resisted all our isolation attempts and therefore crushed nodules had to be used for Sp+ type inoculations.
The Sp+ type Frankia populations differed in their host specificity. Sp+ nodules from A. glutinosa were effective on both alder species, but Sp+ nodules from A. incana induced effective nodules only on the original host; on A. glutinosa only small (1-3mm) prenodule-like structures were found. Such A. glutinosa plants died on N-free medium, thus showing that these nodules were ineffective. In the effective nodules the middle cortex was dominated by infected cells filled with vesicle clusters. In the ineffective nodules only a few cortical cells were infected and sporangia predominated in these cells. Surprisingly enough they also contained vesicle-like structures as demonstrated in electron micrographs. 相似文献
The Sp
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When an autophagosome or an amphisome fuse with a lysosome, the resulting compartment is referred to as an autolysosome. Some people writing papers on the topic of autophagy use the terms “autolysosome” and “autophagolysosome” interchangeably. We contend that these words should be used to denote 2 different compartments, and that it is worthwhile maintaining this distinction—the autophagolysosome has a particular origin in the process of xenophagy that makes it distinct from an autolysosome. 相似文献
54.
Links between plant community composition,soil organic matter quality and microbial communities in contrasting tundra habitats 总被引:6,自引:0,他引:6
Plant communities, soil organic matter and microbial communities are predicted to be interlinked and to exhibit concordant
patterns along major environmental gradients. We investigated the relationships between plant functional type composition,
soil organic matter quality and decomposer community composition, and how these are related to major environmental variation
in non-acid and acid soils derived from calcareous versus siliceous bedrocks, respectively. We analysed vegetation, organic
matter and microbial community compositions from five non-acidic and five acidic heath sites in alpine tundra in northern
Europe. Sequential organic matter fractionation was used to characterize organic matter quality and phospholipid fatty acid
analysis to detect major variation in decomposer communities. Non-acidic and acidic heaths differed substantially in vegetation
composition, and these disparities were associated with congruent shifts in soil organic matter and microbial communities.
A high proportion of forbs in the vegetation was positively associated with low C:N and high soluble N:phenolics ratios in
soil organic matter, and a high proportion of bacteria in the microbial community. On the contrary, dwarf shrub-rich vegetation
was associated with high C:N and low soluble N:phenolics ratios, and a high proportion of fungi in the microbial community.
Our study demonstrates a strong link between the plant community composition, soil organic matter quality, and microbial community
composition, and that differences in one compartment are paralleled by changes in others. Variation in the forb-shrub gradient
of vegetation may largely dictate variations in the chemical quality of organic matter and decomposer communities in tundra
ecosystems. Soil pH, through its direct and indirect effects on plant and microbial communities, seems to function as an ultimate
environmental driver that gives rise to and amplifies the interactions between above- and belowground systems.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
55.
Eskelinen EL 《Molecular aspects of medicine》2006,27(5-6):495-502
The lysosomal membrane proteins LAMP-1 and LAMP-2 are estimated to contribute to about 50% of all proteins of the lysosome membrane. Surprisingly, mice deficient in either LAMP-1 or LAMP-2 are viable and fertile. However, mice deficient in both LAMP-1 and LAMP-2 have an embryonic lethal phenotype. These results show that these two major lysosomal membrane proteins share common functions in vivo. However, LAMP-2 seems to have more specific functions since LAMP-2 single deficiency has more severe consequences than LAMP-1 single deficiency. Mutations in LAMP-2 gene cause a lysosomal glycogen storage disease, Danon disease, in humans. LAMP-2 deficient mice replicate the symptoms found in Danon patients including accumulation of autophagic vacuoles in heart and skeletal muscle. In embryonic fibroblasts, mutual disruption of both LAMPs is associated with an increased accumulation of autophagic vacuoles and unesterified cholesterol, while protein degradation rates are not affected. These results clearly show that the LAMP proteins fulfil functions far beyond the initially suggested roles in maintaining the structural integrity of the lysosomal compartment. 相似文献
56.
Wang C Kovanen V Raudasoja P Eskelinen S Pospiech H Myllylä R 《Journal of cellular and molecular medicine》2009,13(3):508-521
Lysyl hydroxylase (LH) isoform 3 is a post-translational enzyme possessing LH, collagen galactosyltransferase (GT) and glucosyltransferase (GGT) activities. We have demonstrated that LH3 is found not only intracellularly, but also on the cell surface and in the extracellular space, suggesting additional functions for LH3. Here we show that the targeted disruption of LH3 by siRNA causes a marked reduction of both glycosyltransferase activities, and the overexpression of LH3 in HT-1080 cells increases hydroxylation of lysyl residues and the subsequent galactosylation and glucosylation of hydroxylysyl residues. These data confirm the multi-functionality of LH3 in cells. Furthermore, treatment of cells in culture medium with a LH3 N-terminal fragment affects the cell behaviour, rapidly leading to arrest of growth and further to lethality if the fragment is glycosyltransferase-deficient, and leading to stimulation of proliferation if the fragment contains LH3 glycosyltransferase activities. The effect is reversible, the cells recovering after removal of the glycosyltransferase-deficient fragment. The findings were confirmed by overexpressing the full-length LH3 in native or mutated forms in the cells. The data indicate that the increase in proliferation depends on the glycosyltransferase activity of LH3. The overexpression of a glycosyltransferase-deficient mutant or targeted disruption of LH3 by siRNA in cells results in abnormal cell morphology followed by cell death. Our data clearly indicate that the deficiency of LH3 glycosyltransferase activities, especially in the extracellular space, causes growth arrest revealing the importance of the glycosyltransferase activities of LH3 for cell growth and viability, and identifying LH3 as a potential target for medical applications, such as cancer therapy. 相似文献
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Reggiori Fulvio Gabius Hans-Joachim Aureli Massimo Römer Winfried Sonnino Sandro Eskelinen Eeva-Liisa 《Glycoconjugate journal》2021,38(5):625-647
Glycoconjugate Journal - Glycans have been shown to function as versatile molecular signals in cells. This prompted us to look at their roles in endocytosis, endolysosomal system and autophagy. We... 相似文献
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The sarcoplasmic reticulum Ca2+-ATPase (SERCA1a) pumps Ca2+ and countertransport protons. Proton pathways in the Ca2+ bound and Ca2+-free states are suggested based on an analysis of crystal structures to which water molecules were added. The pathways are indicated by chains of water molecules that interact favorably with the protein. In the Ca2+ bound state Ca2E1, one of the proposed Ca2+ entry paths is suggested to operate additionally or alternatively as proton pathway. In analogs of the ADP-insensitive phosphoenzyme E2P and in the Ca2+-free state E2, the proton path leads between transmembrane helices M5 to M8 from the lumenal side of the protein to the Ca2+ binding residues Glu-771, Asp-800 and Glu-908. The proton path is different from suggested Ca2+ dissociation pathways. We suggest that separate proton and Ca2+ pathways enable rapid (partial) neutralization of the empty cation binding sites. For this reason, transient protonation of empty cation binding sites and separate pathways for different ions are advantageous for P-type ATPases in general. 相似文献