21 research outputs found
Embedded Interests and the Managerial Local State: Methanol Fuel-Switching in China
This paper analyzes the determinants of alternative automobile fuel regulation and development support with a particular focus on methanol fuel. We find that embedded interests, bureaucratic reforms, and political circumstances in the Chinese national, provincial, and municipal governments have all shaped policy outcomes in this area. The paper seeks to explain why at, the national level, support for alternative fuels has waned and finds that the concerns of state oil majors and disorganization during the process of national bureaucratic restructuring have been the deciding factors. Interestingly, at the sub-national level promotion of methanol continues unabated in some places. At the local level, business relationships as well as the embedded economic and personal interests of local leaders help to explain managerial local government behavior and sheds light on why government officials actively create and manage methanol fuel business opportunities through local standardization, subsidies, and hands-on management of SOE opposition. The switch towards methanol fuel was more successful in localities where individuals, either government officials or enterprise managers, formed an alliance and made this their 'pet projects'. The analysis draws on 55 interviews conducted between June and October 2010 in Shanxi, a major coal-producing province which has supported methanol fuel-switching programs for over ten years. The findings contribute to debates about the condition of the local state in China. The argument put forward in this paper is that because of limited state capacity at the central level and insufficient concerns for the development of alternative fuels in the short-term, some sub-national governments with strong embedded interests promote certain alternative fuels by taking on active managerial roles, adopting creative and ad-hoc strategies to fill in the national level policy gap at the local level
Key concepts of the <i>C. albicans</i> wall proteome.
<p>Center: TEM picture of the cell wall and its proteins (courtesy of Iuliana V. Ene and Alistair J.P. Brown, Aberdeen). (A) Domain structure of the Hyr/Iff family (adapted from <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003050#ppat.1003050-Boisrame1" target="_blank">[7]</a>). From left to right: N-terminal signal peptide; white box, conserved domain; dark grey box, Ser/Thr-rich region; light grey box, Asp/Gly-rich region; black box, GPI-anchor addition signal. (B) Wall proteins implicated in iron acquisition from host proteins. Membrane and wall-bound CFEM proteins are able to bind hemoglobin, while Als3 is the receptor for ferritin. It is unknown if there exists a receptor for transferrin. Bound hemoglobin is taken up by endocytosis, while iron from ferritin and transferrin is sequestered via the reductive iron uptake system. (C) Effect of yeast-to-hypha transition on the wall proteome with yeast-associated (top; open squares), morphotype-independent (middle; grey squares) and hypha-associated (bottom; black squares) proteins <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003050#ppat.1003050-Heilmann1" target="_blank">[2]</a>. (D) Interaction of wall proteins with the immune system. Wall-resident superoxide dismutases (Sods) detoxify reactive oxygen species (ROS) to H<sub>2</sub>O<sub>2</sub>, which is subsequently converted into H<sub>2</sub>O and O<sub>2</sub> by catalase activity <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003050#ppat.1003050-Frohner1" target="_blank">[20]</a>. Proteins of the Hyr/Iff family confer resistance to neutrophil and phagocyte killing through an unknown mechanism <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003050#ppat.1003050-Luo1" target="_blank">[12]</a>. Possibly, like in <i>S. cerevisiae</i>, proteases situated on the cell wall process the trans-membrane signaling protein Msb2 and liberate the extracellular domain Msb2*. Msb2* is able to bind to antimicrobial peptides (AMPs) in a dose-dependent manner and confers resistance <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003050#ppat.1003050-SzafranskiSchneider1" target="_blank">[21]</a>.</p
An A643T Mutation in the Transcription Factor Upc2p Causes Constitutive ERG11 Upregulation and Increased Fluconazole Resistance in Candida albicans ▿
The zinc cluster transcription factor Upc2p mediates upregulation of ergosterol biosynthesis genes in response to ergosterol depletion in the fungal pathogen Candida albicans. One mechanism of acquired resistance to the antifungal drug fluconazole, which inhibits ergosterol biosynthesis, is constitutively increased expression of the ERG11 gene encoding the drug target enzyme. A G648D mutation in Upc2p has recently been shown to cause hyperactivity of the transcription factor, resulting in overexpression of ergosterol biosynthesis genes and increased fluconazole resistance. In order to investigate if gain-of-function mutations in Upc2p are a common mechanism of ERG11 upregulation and fluconazole resistance, we sequenced the UPC2 alleles of four ERG11-overexpressing, fluconazole-resistant C. albicans isolates and matched susceptible isolates from the same patients. In three of the isolate pairs, no differences in the UPC2 alleles were found, suggesting that mechanisms other than Upc2p mutations can cause ERG11 overexpression. One resistant isolate had become homozygous for a UPC2 allele containing a G1927A substitution that caused an alanine-to-threonine exchange at amino acid position 643 of Upc2p. Replacement of one of the endogenous UPC2 alleles in a fluconazole-susceptible strain by the UPC2A643T allele resulted in ERG11 overexpression and increased fluconazole resistance, which was further elevated when the A643T mutation was also introduced into the second UPC2 allele. These results further establish gain-of-function mutations in UPC2, which can be followed by loss of heterozygosity for the mutated allele, as a mechanism of ERG11 overexpression and increased fluconazole resistance in C. albicans, but other mechanisms of ERG11 upregulation also exist
A truncated lamin A in the Lmna mouse line: Implications for the understanding of laminopathies
During recent years a number of severe clinical syndromes, collectively termed laminopathies, turned out to be caused by various, distinct mutations in the human LMNA gene. Arising from this, remarkable progress has been made to unravel the molecular pathophysiology underlying these disorders. A great benefit in this context was the generation of an A-type lamin deficient mouse line (Lmna) by Sullivan and others,1 which has become one of the most frequently used models in the field and provided profound insights to many different aspects of A-type lamin function. Here, we report the unexpected finding that these mice express a truncated Lmna gene product on both transcriptional and protein level. Combining different approaches including mass spectrometry, we precisely define this product as a C-terminally truncated lamin A mutant that lacks domains important for protein interactions and post-translational processing. Based on our findings we discuss implications for the interpretation of previous studies using Lmna mice and the concept of human laminopathies
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Role of retrograde trafficking in stress response, host cell interactions, and virulence of Candida albicans.
In Saccharomyces cerevisiae, the vacuolar protein sorting complexes Vps51/52/53/54 and Vps15/30/34/38 are essential for efficient endosome-to-Golgi complex retrograde transport. Here we investigated the function of Vps15 and Vps51, representative members of these complexes, in the stress resistance, host cell interactions, and virulence of Candida albicans. We found that C. albicans vps15Δ/Δ and vps51Δ/Δ mutants had abnormal vacuolar morphology, impaired retrograde protein trafficking, and dramatically increased susceptibility to a variety of stressors. These mutants also had reduced capacity to invade and damage oral epithelial cells in vitro and attenuated virulence in the mouse model of oropharyngeal candidiasis. Proteomic analysis of the cell wall of the vps51Δ/Δ mutant revealed increased levels of the Crh11 and Utr2 transglycosylases, which are targets of the calcineurin signaling pathway. The transcript levels of the calcineurin pathway members CHR11, UTR2, CRZ1, CNA1, and CNA2 were elevated in the vps15Δ/Δ and vps51Δ/Δ mutants. Furthermore, these strains were highly sensitive to the calcineurin-specific inhibitor FK506. Also, deletion of CHR11 and UTR2 further increased the stress susceptibility of these mutants. In contrast, overexpression of CRH11 and UTR2 partially rescued their defects in stress resistance, but not host cell interactions. Therefore, intact retrograde trafficking in C. albicans is essential for stress resistance, host cell interactions, and virulence. Aberrant retrograde trafficking stimulates the calcineurin signaling pathway, leading to the increased expression of Chr11 and Utr2, which enables C. albicans to withstand environmental stress
Role of Retrograde Trafficking in Stress Response, Host Cell Interactions, and Virulence of Candida albicans
In Saccharomyces cerevisiae, the vacuolar protein sorting complexes Vps51/52/53/54 and Vps15/30/34/38 are essential for efficient endosome-to-Golgi complex retrograde transport. Here we investigated the function of Vps15 and Vps51, representative members of these complexes, in the stress resistance, host cell interactions, and virulence of Candida albicans. We found that C. albicans vps15Δ/Δ and vps51Δ/Δ mutants had abnormal vacuolar morphology, impaired retrograde protein trafficking, and dramatically increased susceptibility to a variety of stressors. These mutants also had reduced capacity to invade and damage oral epithelial cells in vitro and attenuated virulence in the mouse model of oropharyngeal candidiasis. Proteomic analysis of the cell wall of the vps51Δ/Δ mutant revealed increased levels of the Crh11 and Utr2 transglycosylases, which are targets of the calcineurin signaling pathway. The transcript levels of the calcineurin pathway members CHR11, UTR2, CRZ1, CNA1, and CNA2 were elevated in the vps15Δ/Δ and vps51Δ/Δ mutants. Furthermore, these strains were highly sensitive to the calcineurin-specific inhibitor FK506. Also, deletion of CHR11 and UTR2 further increased the stress susceptibility of these mutants. In contrast, overexpression of CRH11 and UTR2 partially rescued their defects in stress resistance, but not host cell interactions. Therefore, intact retrograde trafficking in C. albicans is essential for stress resistance, host cell interactions, and virulence. Aberrant retrograde trafficking stimulates the calcineurin signaling pathway, leading to the increased expression of Chr11 and Utr2, which enables C. albicans to withstand environmental stress
Hyphal induction in the human fungal pathogen Candida albicans reveals a characteristic wall protein profile
The ability of Candida albicans to switch from yeast to hyphal growth is essential for its virulence. The walls and especially the covalently attached wall proteins are involved in the primary host-pathogen interactions. Three hyphal induction methods were compared, based on fetal calf serum, the amino sugar N-acetylglucosamine (GlcNAc) and the mammalian cell culture medium Iscove’s modified Dulbecco’s medium (IMDM). GlcNAc and IMDM were preferred, allowing stable hyphal growth over a prolonged period without significant reversion to yeast growth and with high biomass yields. We employed Fourier transform-MS combined with a 15N-metabolically labelled reference culture as internal standard for relative quantification of changes in the wall proteome upon hyphal induction. A total of 21 wall proteins were quantified. Our induction methods triggered a similar response characterized by (i) a category of wall proteins showing strongly increased incorporation levels (Als3, Hwp2, Hyr1, Plb5 and Sod5), (ii) another category with strongly decreased levels (Rhd3, Sod4 and Ywp1) and (iii) a third one enriched for carbohydrate-active enzymes (including Cht2, Crh11, Mp65, Pga4, Phr1, Phr2 and Utr2) and showing only a limited response. This is, to our knowledge, the first systematic, quantitative analysis of the changes in the wall proteome of C. albicans upon hyphal induction. Finally, we propose new wall-protein-derived candidates for vaccine development