| 1. |
- Chen, Yong, et al.
(author)
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A Vps21 endocytic module regulates autophagy
- 2014
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In: Molecular Biology of the Cell. - 1939-4586. ; 25:20, s. 3166-3177
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Journal article (peer-reviewed)abstract
- In autophagy, the double-membrane autophagosome delivers cellular components for their degradation in the lysosome. The conserved Ypt/Rab GTPases regulate all cellular trafficking pathways, including autophagy. These GTPases function in modules that include guanine-nucleotide exchange factor (GEF) activators and downstream effectors. Rab7 and its yeast homologue, Ypt7, in the context of such a module, regulate the fusion of both late endosomes and autophagosomes with the lysosome. In yeast, the Rab5-related Vps21 is known for its role in early- to late-endosome transport. Here we show an additional role for Vps21 in autophagy. First, vps21Δ mutant cells are defective in selective and nonselective autophagy. Second, fluorescence and electron microscopy analyses show that vps21Δ mutant cells accumulate clusters of autophagosomal structures outside the vacuole. Third, cells with mutations in other members of the endocytic Vps21 module, including the GEF Vps9 and factors that function downstream of Vps21, Vac1, CORVET, Pep12, and Vps45, are also defective in autophagy and accumulate clusters of autophagosomes. Finally, Vps21 localizes to PAS. We propose that the endocytic Vps21 module also regulates autophagy. These findings support the idea that the two pathways leading to the lysosome—endocytosis and autophagy—converge through the Vps21 and Ypt7 GTPase modules.
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| 2. |
- Wang, Yutao, et al.
(author)
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Community dynamics of arbuscular mycorrhizal fungi in high-input and intensively irrigated rice cultivation systems.
- 2015
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In: Applied and Environmental Microbiology. - 0099-2240. ; 81:8, s. 2958-2965
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Journal article (peer-reviewed)abstract
- Application of mycorrhizal inoculum could be one way to increase the yield of rice plants, and reduce the application of fertilizer. We therefore studied arbuscular mycorrhizal fungi (AMF) in the roots of wetland rice (Oryza sativa L.) collected at the seedling, tillering, heading and ripening stages in four paddy wetlands that had been under a high-input and intensively irrigated rice cultivation system for more than 20 years. It was found that AMF colonization was mainly established in the heading and ripening stages. The AMF community structure was characterized in rhizosphere soil and root from two of the studied paddy wetlands. A fragment covering partial SSU, the whole ITS and partial LSU rRNA operon region of AMF was amplified, cloned and sequenced from roots and soils. A total of 639 AMF sequences were obtained, and these were finally assigned to 16 phylotypes based on a phylogenetic analysis, including 12 phylotypes from Glomeraceae, one phylotype from Claroideoglomeraceae, two phylotypes from Paraglomeraceae and one unidentified phylotype. The AMF phylotype compositions in the soils were similar between the two surveyed sites, but there was a clear discrepancy between the communities obtained from root and soil. The relatively high number of AMF phylotypes at the surveyed sites suggests that the conditions are suitable for some species of AMF and that they may have an important function in conventional rice cultivation systems. The species richness of root-colonizing AMF increased with growth of rice, and future studies should consider the developmental stages of this crop in the exploration of AMF function in paddy wetlands.
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| 3. |
- Wang, Yutao, et al.
(author)
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Response differences of arbuscular mycorrhizal fungi communities in the roots of an aquatic and a semiaquatic species to various flooding regimes
- 2016
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In: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 403:1-2, s. 361-373
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Journal article (peer-reviewed)abstract
- Background and aims: Arbuscular mycorrhizal fungi (AMF) are ubiquitous in wetland habitats, but their diversity and distribution pattern in these habitats is poorly understood. Under varying hydrological conditions, AMF communities in roots of different wetland species may respond differently due to hydrological and to physiological differences among plants. Here we test this hypothesis.Methods: AMF colonization intensity and community structure in the roots of two wetland plants with different flood tolerance (one aquatic and one semiaquatic) were characterized along a hydrologic gradient. A fragment covering partial SSU, the whole ITS and partial LSU rDNA region of AMF was amplified, cloned and sequenced from the roots of each host species.Results: A total of 528 AMF sequences were obtained and sorted into 15 taxa based on phylogenetic analyses. A total of nine and 13 taxa, respectively, were found from the aquatic and semiaquatic host species; theAMF compositions of both sets of taxa were very similar. Intensive flooding inhibited the AMF colonization and diversity level in both cases, while moderate flooding caused distinctly different effects between thetwo wetland species.Conclusions: AMF diversity level in wetland habitat is not necessarily low, even if few morphological structures of AMF are detected in the roots. The effects of hydrologic conditions on AMF communities in wetlands depend on both the flooding intensity and the adaptations of the wetland hosts.
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| 4. |
- Björn, Lars Olof, et al.
(author)
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Ecological importance of the thermal emissivity of avian eggshells
- 2012
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In: Journal of Theoretical Biology. - : Elsevier BV. - 1095-8541 .- 0022-5193. ; 301, s. 62-66
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Journal article (peer-reviewed)abstract
- Breeding birds have to divide their time between egg incubation and foraging. Particularly in cases when only one parent incubates the eggs, and especially in cold climates, the cooling of the eggs during absence from the nest may be problematic. In the present study we find that the thermal emissivity of eggshells may be ecologically important, and that an evolutionary pressure towards lower emissivity for exposed eggs in cold climates exists. We plan to experimentally compare emissivities among species in a future study. (C) 2012 Elsevier Ltd. All rights reserved.
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| 5. |
- Björn, Lars Olof, et al.
(author)
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Near-surface silica does not increase radiative heat dissipation from plant leaves
- 2011
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 99:2
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Journal article (peer-reviewed)abstract
- It has been suggested that plants are able to increase radiative heat dissipation from their leaves by depositing near-surface silica, in this way increasing emissivity of infrared radiation and lowering leaf temperature. In order to test this theory, we have compared emissivity and radiative dissipation over the mid-infrared range 2.5–22.3 lm of leaves of plants that accumulate silica and plants that do not. Our data do not support the theory that accumulation of silica increases radiative heat dissipation by plant leaves.
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| 6. |
- Björn, Lars Olof, et al.
(author)
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Role of Ultraviolet Radiation in the Origin of Life
- 2015
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In: Photobiology: The Science of Light and Life (3rd ed.). - New York, NY : Springer New York. - 9781493914678 - 9781493914685 ; , s. 415-420
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Book chapter (other academic/artistic)
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| 7. |
- Björn, Lars Olof, et al.
(author)
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Teaching about photosynthesis with simple equipment: analysis of light-induced changes in fluorescence and reflectance of plant leaves
- 2013
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 116:2-3, s. 349-353
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Journal article (peer-reviewed)abstract
- Solar energy absorbed by plants results in either reflection or absorption. The latter results in photosynthesis, fluorescence, or heat. Measurements of fluorescence changes have been used for monitoring processes associated with photosynthesis. A simple method to follow changes in leaf fluorescence and leaf reflectance associated with nonphotochemical quenching and light acclimation of leaves is described. The main equipment needed consists of a green-light emitting laser pointer, a digital camera, and a personal computer equipped with the camera acquisition software and the programs ImageJ and Excel. Otherwise, only commonly available cheap materials are required.
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| 8. |
- Björn, Lars Olof, et al.
(author)
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Thermal emissivity of avian eggshells
- 2016
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In: Journal of Thermal Biology. - : Elsevier BV. - 0306-4565 .- 1879-0992. ; 57, s. 1-5
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Journal article (peer-reviewed)abstract
- The hypothesis has been tested that evolution has resulted in lower thermal emissivity of eggs of birds breeding openly in cold climates than of eggs of birds that nest under protective covering or in warmer climates. Directional thermal emissivity has been estimated from directional–hemispherical reflectance spectra. Due to several methodological difficulties the absolute emissivity is not accurately determined, but differences between species are obvious. Mostnotably, small waders of the genus Calidris, breeding in cold climates on the tundra, and in most cases with uniparental nest attendance, have low directional emissivity of their eggshells, about 0.92 when integration is carried out for wavelengths up to 16 μm. Species belonging to Galloanserinae have the highest directional emissivity, about 0.96, of their eggs. No differences due to climate or breeding conditions were found within this group. Eggs of most other birds tested possess intermediate emissivity, but the values for Pica pica and Corvus corone cornix are as low as for Calidris. Large species-dependent differences in spectral reflectance were found at specific wavelengths. For instance, at 4.259 μm the directional–hemispherical reflectance for galliforms range from 0.05 to 0.09, while for Fratercula arctica and Fulmarus glacialis it is about 0.3.The reflection peaks at 6.5 and 11.3 μm due to calcite are differentially attenuated in differents pecies. In conclusion, the hypothesis that evolution has resulted in lower thermal emissivity of bird-eggs being exposed in cold climates is not supported by our results.The emissivity is not clearly related to nesting habits or climate, and it is unlikely that the small differences observed are ecologically important. The spectral differences between eggs that nevertheless exist should be taken into account when using infrared thermometers for estimating the surface temperature of avian eggs.
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| 9. |
- Gong, Ni, et al.
(author)
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DNA C-values of 20 invasive alien species and 3 native species in South China.
- 2014
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In: Archives of Biological Sciences. - 0354-4664. ; 66:4, s. 1465-1472
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Journal article (peer-reviewed)abstract
- Cultivated fields and forests in South China are experiencing serious damage due to invasive alien plants. We investigated the relation between DNA C-values and invasiveness. The DNA C-values of 23 species ranged from 0.39 pg to 3.37 pg. Herbs, perennials and native species had higher mean DNA C-values than shrubs, annuals and invasive alien species. DNA C-values decreased with increasing invasiveness. Paederia scandens, a harmful native species, has the lowest DNA C-value among the perennials, indicating that native species with low nuclear content may also possess an invasive potential.
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| 10. |
- Jiang, Lei, et al.
(author)
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Arabidopsis RADICAL-INDUCED CELL DEATH1 is involved in UV-B signaling.
- 2009
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In: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 8, s. 838-846
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Journal article (peer-reviewed)abstract
- The Arabidopsis radical-induced cell death1 (rcd1) mutant is sensitive to ozone fumigation and apoplastic superoxide, but tolerant to methyl viologen. In the present article, we report that the rcd1 mutant is also tolerant to supplementary UV-B radiation. The rcd1-1 mutant exhibits less accumulation of TT dimers, increased hypocotyl growth inhibition and higher accumulation of flavonoids under supplemental UV-B radiation. Moreover, the expression of HY5 (ELONGATED HYPOCOTYL5) is increased in the mutant after UV-B treatment. Gene expression downstream of UV-B signaling reveals that COP1 (CONSTITUTIVELY PHOTOMORPHOGENIC1)-regulated genes have an elevated expression in rcd1-1 mutant under UV-B radiation, while expression of UVR8 (UV RESISTANCE LOCUS 8)-regulated and HY5-independent genes are not changed. Interestingly, the expression of RCD1 genes is not significantly changed by UV-B radiation. Previous study has shown that STO protein is interacting with RCD1 in vitro. Here, we found the mRNA level of STO (SALT TOLERANCE) is greatly increased in rcd1-1 mutant after UV-B radiation. However, UV-B-induced HY5 and CHS expression is partially inhibited in sto mutant. Based on the above results, it is deduced that the RCD1, working together with STO, is involved in Arabidopsis UV-B signaling.
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