| 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. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Jiang, Lei, et al.
(author)
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Does cell cycle arrest occur in plant under solar UV-B radiation?
- 2011
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In: Plant Signalling & Behavior. - : Informa UK Limited. - 1559-2316 .- 1559-2324. ; 6:6, s. 892-894
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Journal article (peer-reviewed)abstract
- UV-B radiation (280–315 nm) is an integral part of solar radiation and has many harmful effects on plant growth and development. However, the molecular mechanism for the inhibition of plant growth by UV-B remains largely unknown. UV-B radiation induces various responses such as growth inhibition, DNA damage and changes of gene expression. Recently, by using synchronous root tip culture, we found that UV-B modulates the expression of cell cycle regulatory genes through DNA damage. Western blotting analysis revealed that UV-B induced G1-to-S arrest did not correlate with the protein abundance of CDKB1;1 and CYCD3;1 gene regulating proteins, but may with the posttranslational control. We extended the expression analysis of cell cycle related genes based on the published microarray data and the results strengthen our assumption that cell cycle arrest could occur in plant under solar UV-B radiation. Further study is needed to elucidate the relationship between cell cycle regulation and protective pathway induced by low dose of UV-B radiation and the fundamental molecular mechanism for how plants respond to solar UV-B radiation.
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| 7. |
- Jiang, Lei, et al.
(author)
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UV-B-induced DNA damage mediates expression changes of cell cycle regulatory genes in Arabidopsis root tips
- 2011
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In: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 233:4, s. 831-841
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Journal article (peer-reviewed)abstract
- Even though a number of studies have shown that UV-B radiation inhibits plant growth and regulates the cell cycle progress, little is known about the molecular and cellular mechanisms. Here, we developed a synchronous root-tip cell system to investigate expression changes of cell cycle marker genes and DNA damage under UV-B radiation. Expression analysis of cell cycle marker genes revealed that G1-to-S transition in root-tip cells was accomplished within 6 h. In the in vivo synchronous root-tip cells, high level of UV-B radiation (0.45 W m(-2)) induced expression changes of the cell cycle regulatory genes. Genes involved in G1-to-S transition, Histone H4 and E2Fa, were down-regulated by UV-B radiation during 2-6 h; whereas transcripts for KRP2, a negative regulator of G1-to-S transition, were up-regulated by UV-B at 2 h. The peak time for transcript level of CYCD3;1, a positive factor in G1-to-S transition, was delayed by UV-B radiation. Interestingly, a medium level of UV-B radiation (0.25 W m(-2)) did not change the expression of these genes in root tip cells from wild type. However, cell cycle regulatory genes were greatly affected in uvh1 mutant, which exhibited higher content of cyclobutane pyrimidine dimers (CPDs). Ascorbic acid treatment did not change the expression pattern of cell cycle regulatory genes that were affected by high-level UV-B. Our results implied that UV-B-induced DNA damage results in the delay of G1-to-S transition of plant cell cycle. UV-B-induced G1-to-S arrest may be a protective mechanism that prevents cells with damaged DNA from dividing and may explain the plant growth inhibition under increased solar UV-B radiation.
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