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51.
Quantifying the climatic niche of symbiont partners in a lichen symbiosis indicates mutualist‐mediated niche expansions
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Gregor Rolshausen Francesco Dal Grande Anna D. Sadowska‐Deś Jürgen Otte Imke Schmitt 《Ecography》2018,41(8):1380-1392
The large distributional areas and ecological niches of many lichenized fungi may in part be due to the plasticity in interactions between the fungus (mycobiont) and its algal or cyanobacterial partners (photobionts). On the one hand, broad‐scale phylogenetic analyses show that partner compatibility in lichens is rather constrained and shaped by reciprocal selection pressures and codiversification independent of ecological drivers. On the other hand, sub‐species‐level associations among lichen symbionts appear to be environmentally structured rather than phylogenetically constrained. In particular, switching between photobiont ecotypes with distinct environmental preferences has been hypothesized as an adaptive strategy for lichen‐forming fungi to broaden their ecological niche. The extent and direction of photobiont‐mediated range expansions in lichens, however, have not been examined comprehensively at a broad geographic scale. Here we investigate the population genetic structure of Lasallia pustulata symbionts at sub‐species‐level resolution across the mycobiont's Europe‐wide range, using fungal MCM7 and algal ITS rDNA sequence markers. We show that variance in occurrence probabilities in the geographic distribution of genetic diversity in mycobiont‐photobiont interactions is closely related to changes in climatic niches. Quantification of niche extent and overlap based on species distribution modeling and construction of Hutchinsonian climatic hypervolumes revealed that combinations of fungal–algal interactions change at the sub‐species level along latitudinal temperature gradients and in Mediterranean climate zones. Our study provides evidence for symbiont‐mediated niche expansion in lichens. We discuss our results in the light of symbiont polymorphism and partner switching as potential mechanisms of environmental adaptation and niche evolution in mutualisms. 相似文献
52.
Identification and characterization of interactions between the vertebrate polycomb-group protein BMI1 and human homologs of polyhomeotic. 总被引:14,自引:5,他引:9
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M J Gunster D P Satijn K M Hamer J L den Blaauwen D de Bruijn M J Alkema M van Lohuizen R van Driel A P Otte 《Molecular and cellular biology》1997,17(4):2326-2335
In Drosophila melanogaster, the Polycomb-group (PcG) genes have been identified as repressors of gene expression. They are part of a cellular memory system that is responsible for the stable transmission of gene activity to progeny cells. PcG proteins form a large multimeric, chromatin-associated protein complex, but the identity of its components is largely unknown. Here, we identify two human proteins, HPH1 and HPH2, that are associated with the vertebrate PcG protein BMI1. HPH1 and HPH2 coimmunoprecipitate and cofractionate with each other and with BMI1. They also colocalize with BMI1 in interphase nuclei of U-2 OS human osteosarcoma and SW480 human colorectal adenocarcinoma cells. HPH1 and HPH2 have little sequence homology with each other, except in two highly conserved domains, designated homology domains I and II. They share these homology domains I and II with the Drosophila PcG protein Polyhomeotic (Ph), and we, therefore, have named the novel proteins HPH1 and HPH2. HPH1, HPH2, and BMI1 show distinct, although overlapping expression patterns in different tissues and cell lines. Two-hybrid analysis shows that homology domain II of HPH1 interacts with both homology domains I and II of HPH2. In contrast, homology domain I of HPH1 interacts only with homology domain II of HPH2, but not with homology domain I of HPH2. Furthermore, BMI1 does not interact with the individual homology domains. Instead, both intact homology domains I and II need to be present for interactions with BMI1. These data demonstrate the involvement of homology domains I and II in protein-protein interactions and indicate that HPH1 and HPH2 are able to heterodimerize. 相似文献
53.
54.
Chambers RJ Abrams K Garceau NY Kamath AV Manley CM Lilley SC Otte DA Scott DO Sheils AL Tess DA Vellekoop AS Zhang Y Lam KT 《Bioorganic & medicinal chemistry letters》2006,16(2):307-310
Oxindole (2) is a potent and selective PDE2 inhibitor with a favorable ADME, physiochemical and pharmacokinetic profile to allow for use as a chemical tool in elucidating the physiological role of PDE2. 相似文献
55.
Industrial Food Animal Production and Global Health Risks: Exploring the Ecosystems and Economics of Avian Influenza 总被引:2,自引:0,他引:2
Jessica H. Leibler Joachim Otte David Roland-Holst Dirk U. Pfeiffer Ricardo Soares Magalhaes Jonathan Rushton Jay P. Graham Ellen K. Silbergeld 《EcoHealth》2009,6(1):58-70
Many emerging infectious diseases in human populations are associated with zoonotic origins. Attention has often focused on
wild animal reservoirs, but most zoonotic pathogens of recent concern to human health either originate in, or are transferred
to, human populations from domesticated animals raised for human consumption. Thus, the ecological context of emerging infectious
disease comprises two overlapping ecosystems: the natural habitats and populations of wild animals, and the anthropogenically
controlled habitats and populations of domesticated species. Intensive food animal production systems and their associated
value chains dominate in developed countries and are increasingly important in developing countries. These systems are characterized
by large numbers of animals being raised in confinement with high throughput and rapid turnover. Although not typically recognized
as such, industrial food animal production generates unique ecosystems—environments that may facilitate the evolution of zoonotic
pathogens and their transmission to human populations. It is often assumed that confined food animal production reduces risks
of emerging zoonotic diseases. This article provides evidence suggesting that these industrial systems may increase animal
and public health risks unless there is recognition of the specific biosecurity and biocontainment challenges of the industrial
model. Moreover, the economic drivers and constraints faced by the industry and its participants must be fully understood
in order to inform preventative policy. In order to more effectively reduce zoonotic disease risk from industrial food animal
production, private incentives for the implementation of biosecurity must align with public health interests. 相似文献
56.
Ricardo J Soares Magalhães Angel Ortiz-Pelaez Kim Lan Lai Thi Quoc Hoang Dinh Joachim Otte Dirk U Pfeiffer 《BMC veterinary research》2010,6(1):10
Background
The structure of contact between individuals plays an important role in the incursion and spread of contagious diseases in both human and animal populations. In the case of avian influenza, the movement of live birds is a well known risk factor for the geographic dissemination of the virus among poultry flocks. Live bird markets (LBM's) contribute to the epidemiology of avian influenza due to their demographic characteristics and the presence of HPAI H5N1 virus lineages. The relationship between poultry producers and live poultry traders (LPT's) that operate in LBM's has not been adequately documented in HPAI H5N1-affected SE Asian countries. The aims of this study were to document and study the flow of live poultry in a poultry trade network in northern Vietnam, and explore its potential role in the risk for HPAI H5N1 during 2003 to 2006. 相似文献57.
Susanne Kammler Marianne Otte Ilona Hauber Jørgen Kjems Joachim Hauber Heiner Schaal 《Retrovirology》2006,3(1):1-20
Background
Of the diverse subtypes of Human Immunodeficiency Virus Type-1 (HIV-1), subtype-C strains cause a large majority of infections worldwide. The reasons for the global dominance of HIV-1 subtype-C infections are not completely understood. Tat, being critical for viral infectivity and pathogenesis, may differentially modulate pathogenic properties of the viral subtypes. Biochemical studies on Tat are hampered by the limitations of the current purification protocols. Tat purified using standard protocols often is competent for transactivation activity but defective for a variety of other biological functions. Keeping this limitation in view, we developed an efficient protein purification strategy for Tat.Results
Tat proteins obtained using the novel strategy described here were free of contaminants and retained biological functions as evaluated in a range of assays including the induction of cytokines, upregulation of chemokine coreceptor, transactivation of the viral promoter and rescue of a Tat-defective virus. Given the highly unstable nature of Tat, we evaluated the effect of the storage conditions on the biological function of Tat following purification. Tat stored in a lyophilized form retained complete biological activity regardless of the storage temperature. To understand if variations in the primary structure of Tat could influence the secondary structure of the protein and consequently its biological functions, we determined the CD spectra of subtype-C and -B Tat proteins. We demonstrate that subtype-C Tat may have a relatively higher ordered structure and be less flexible than subtype-B Tat. We show that subtype-C Tat as a protein, but not as a DNA expression vector, was consistently inferior to subtype-B Tat in a variety of biological assays. Furthermore, using ELISA, we evaluated the anti-Tat antibody titers in a large number of primary clinical samples (n = 200) collected from all four southern Indian states. Our analysis of the Indian populations demonstrated that Tat is non-immunodominant and that a large variation exists in the antigen-specific antibody titers.Conclusion
Our report not only describes a simple protein purification strategy for Tat but also demonstrates important structural and functional differences between subtype-B and -C Tat proteins. Furthermore, this is the first report of protein purification and characterization of subtype-C Tat. 相似文献58.
Identification of farnesoid X receptor beta as a novel mammalian nuclear receptor sensing lanosterol
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59.
Selective interactions between vertebrate polycomb homologs and the SUV39H1 histone lysine methyltransferase suggest that histone H3-K9 methylation contributes to chromosomal targeting of Polycomb group proteins 总被引:9,自引:0,他引:9
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Sewalt RG Lachner M Vargas M Hamer KM den Blaauwen JL Hendrix T Melcher M Schweizer D Jenuwein T Otte AP 《Molecular and cellular biology》2002,22(15):5539-5553
Polycomb group (PcG) proteins form multimeric chromatin-associated protein complexes that are involved in heritable repression of gene activity. Two distinct human PcG complexes have been characterized. The EED/EZH2 PcG complex utilizes histone deacetylation to repress gene activity. The HPC/HPH PcG complex contains the HPH, RING1, BMI1, and HPC proteins. Here we show that vertebrate Polycomb homologs HPC2 and XPc2, but not M33/MPc1, interact with the histone lysine methyltransferase (HMTase) SUV39H1 both in vitro and in vivo. We further find that overexpression of SUV39H1 induces selective nuclear relocalization of HPC/HPH PcG proteins but not of the EED/EZH2 PcG proteins. This SUV39H1-dependent relocalization concentrates the HPC/HPH PcG proteins to the large pericentromeric heterochromatin domains (1q12) on human chromosome 1. Within these PcG domains we observe increased H3-K9 methylation. Finally, we show that H3-K9 HMTase activity is associated with endogenous HPC2. Our findings suggest a role for the SUV39H1 HMTase and histone H3-K9 methylation in the targeting of human HPC/HPH PcG proteins to modified chromatin structures. 相似文献
60.
Erv41p and Erv46p form an integral membrane protein complex that cycles between the endoplasmic reticulum (ER) and Golgi. Both proteins contain a large lumenal domain and short N- and C-terminal tail sequences exposed to the cytosol. The coat protein complex II (COPII) packages the Erv41p-Erv46p complex into ER-derived vesicles for delivery to the Golgi. We determined signals in the Erv41p-Erv46p complex that are required for COPII-dependent export from the ER. Mutants lacking the Erv41p or Erv46p C-terminus accumulated in the ER and were not packaged efficiently into vesicles. We identified an isoleucine-leucine sequence in the Erv41p tail that was required for COPII binding and inclusion of the complex into vesicles. This signal was sufficient for COPII binding but not for ER export. The Erv46p tail contains a phenylalanine-tyrosine sequence required together with the isoleucine-leucine signal in Erv41p for export of the complex. Surprisingly, Erv41p- Erv46p tail-swapped chimeras were not exported from the ER, indicating that signals in both the Erv41p and the Erv46p tail sequences are required in a specific orientation for efficient packaging of the Erv41p-Erv46p complex. 相似文献