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961.
Cunha Joana T. Costa Carlos E. Ferraz Luís Romaní Aloia Johansson Björn Sá-Correia Isabel Domingues Lucília 《Applied microbiology and biotechnology》2018,102(10):4589-4600
Applied Microbiology and Biotechnology - Acetic acid tolerance and xylose consumption are desirable traits for yeast strains used in industrial biotechnological processes. In this work,... 相似文献
962.
The nuclear envelope has a stereotypic morphology consisting of a flat double layer of the inner and outer nuclear membrane, with interspersed nuclear pores. Underlying and tightly linked to the inner nuclear membrane is the nuclear lamina, a proteinous layer of intermediate filament proteins and associated proteins. Physiological, experimental or pathological alterations in the constitution of the lamina lead to changes in nuclear morphology, such as blebs and lobulations. It has so far remained unclear whether the morphological changes depend on the differentiation state and the specific lamina protein. Here we analysed the ultrastructural morphology of the nuclear envelope in intestinal stem cells and differentiated enterocytes in adult Drosophila flies, in which the proteins Lam, Kugelkern or a farnesylated variant of LamC were overexpressed. Surprisingly, we detected distinct morphological features specific for the respective protein. Lam induced envelopes with multiple layers of membrane and lamina, surrounding the whole nucleus whereas farnesylated LamC induced the formation of a thick fibrillary lamina. In contrast, Kugelkern induced single-layered and double-layered intranuclear membrane structures, which are likely be derived from infoldings of the inner nuclear membrane or of the double layer of the envelope. 相似文献
963.
964.
Mark Stettner Jennifer Zenker Fabian Klingler Fabian Szepanowski Hans-P. Hartung Anne K. Mausberg Christoph Kleinschnitz Roman Chrast Bernd C. Kieseier 《Cellular and molecular neurobiology》2018,38(2):487-496
The protein component of the myelin layer is essential for all aspects of peripheral nerves, and its deficiency can lead to structural and functional impairment. The presence of peripheral myelin protein 2 (P2, PMP2, FABP8, M-FABP) in Schwann cells has been known for decades and shown recently to be involved in the lipid homeostasis in the peripheral neural system. However, its precise role during de- and remyelination has yet to be elucidated. To this end, we assessed remyelination after sciatic nerve crush injury in vivo, and in an experimental de/remyelination ex vivo myelinating culture model in P2-deficient (P2 ?/? ) and wild-type (WT) animals. In vivo, the nerve crush paradigm revealed temporal structural and functional changes in P2 ?/? mice as compared to WT animals. Concomitantly, P2 ?/? DRG cultures demonstrated the presence of shorter internodes and enlarged nodes after ex vivo de/remyelination. Together, these data indicate that P2 may play a role in remyelination of the injured peripheral nervous system, presumably by affecting the nodal and internodal configuration. 相似文献
965.
966.
Landscape attributes governing local transmission of an endemic zoonosis: Rabies virus in domestic dogs
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Kirstyn Brunker Philippe Lemey Denise A. Marston Anthony R. Fooks Ahmed Lugelo Chanasa Ngeleja Katie Hampson Roman Biek 《Molecular ecology》2018,27(3):773-788
Landscape heterogeneity plays an important role in disease spread and persistence, but quantifying landscape influences and their scale dependence is challenging. Studies have focused on how environmental features or global transport networks influence pathogen invasion and spread, but their influence on local transmission dynamics that underpin the persistence of endemic diseases remains unexplored. Bayesian phylogeographic frameworks that incorporate spatial heterogeneities are promising tools for analysing linked epidemiological, environmental and genetic data. Here, we extend these methodological approaches to decipher the relative contribution and scale‐dependent effects of landscape influences on the transmission of endemic rabies virus in Serengeti district, Tanzania (area ~4,900 km2). Utilizing detailed epidemiological data and 152 complete viral genomes collected between 2004 and 2013, we show that the localized presence of dogs but not their density is the most important determinant of diffusion, implying that culling will be ineffective for rabies control. Rivers and roads acted as barriers and facilitators to viral spread, respectively, and vaccination impeded diffusion despite variable annual coverage. Notably, we found that landscape effects were scale‐dependent: rivers were barriers and roads facilitators on larger scales, whereas the distribution of dogs was important for rabies dispersal across multiple scales. This nuanced understanding of the spatial processes that underpin rabies transmission can be exploited for targeted control at the scale where it will have the greatest impact. Moreover, this research demonstrates how current phylogeographic frameworks can be adapted to improve our understanding of endemic disease dynamics at different spatial scales. 相似文献
967.
Luis Filipe Costa‐Machado Roberto Martín‐Hernández Miguel Ángel Sanchez‐Luengo Katharina Hess Claudia Vales‐Villamarin Marta Barradas Cian Lynch Daniel de la Nava Alberto Diaz‐Ruiz Rafael de Cabo Marta Cañamero Lola Martinez Marta Sanchez‐Carbayo Daniel Herranz Manuel Serrano Pablo J Fernandez‐Marcos 《EMBO reports》2018,19(9)
The NAD+‐dependent deacetylase SIRT1 can be oncogenic or tumor suppressive depending on the tissue. Little is known about the role of SIRT1 in non‐small cell lung carcinoma (NSCLC), one of the deadliest cancers, that is frequently associated with mutated K‐RAS. Therefore, we investigated the effect of SIRT1 on K‐RAS‐driven lung carcinogenesis. We report that SIRT1 protein levels are downregulated by oncogenic K‐RAS in a MEK and PI3K‐dependent manner in mouse embryo fibroblasts (MEFs), and in human lung adenocarcinoma cell lines. Furthermore, Sirt1 overexpression in mice delays the appearance of K‐RasG12V‐driven lung adenocarcinomas, reducing the number and size of carcinomas at the time of death and extending survival. Consistently, lower levels of SIRT1 are associated with worse prognosis in human NSCLCs. Mechanistically, analysis of mouse Sirt1‐Tg pneumocytes, isolated shortly after K‐RasG12V activation, reveals that Sirt1 overexpression alters pathways involved in tumor development: proliferation, apoptosis, or extracellular matrix organization. Our work demonstrates a tumor suppressive role of SIRT1 in the development of K‐RAS‐driven lung adenocarcinomas in mice and humans, suggesting that the SIRT1–K‐RAS axis could be a therapeutic target for NSCLCs. 相似文献
968.
Structural intermediates in the assembly of taxoid-induced microtubules and GDP-tubulin double rings: time-resolved X-ray scattering. 总被引:1,自引:1,他引:0
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We have studied the self-association reactions of purified GDP-liganded tubulin into double rings and taxoid-induced microtubules, employing synchrotron time-resolved x-ray solution scattering. The experimental scattering profiles have been interpreted by reference to the known scattering profiles to 3 nm resolution and to the low-resolution structures of the tubulin dimer, tubulin double rings, and microtubules, and by comparison with oligomer models and model mixtures. The time courses of the scattering bands corresponding to the different structural features were monitored during the assembly reactions under varying biochemical conditions. GDP-tubulin essentially stays as a dimer at low Mg(2+) ion activity, in either the absence or presence of taxoid. Upon addition of the divalent cations, it associates into either double-ring aggregates or taxoid-induced microtubules by different pathways. Both processes have the formation of small linear (short protofilament-like) tubulin oligomers in common. Tubulin double-ring aggregate formation, which is shown by x-ray scattering to be favored in the GDP- versus the GTP-liganded protein, can actually block microtubule assembly. The tubulin self-association leading to double rings, as determined by sedimentation velocity, is endothermic. The formation of the double-ring aggregates from oligomers, which involves additional intermolecular contacts, is exothermic, as shown by x-ray and light scattering. Microtubule assembly can be initiated from GDP-tubulin dimers or oligomers. Under fast polymerization conditions, after a short lag time, open taxoid-induced microtubular sheets have been clearly detected (monitored by the central scattering and the maximum corresponding to the J(n) Bessel function), which slowly close into microtubules (monitored by the appearance of their characteristic J(0), J(3), and J (n) - (3) Bessel function maxima). This provides direct evidence for the bidimensional assembly of taxoid-induced microtubule polymers in solution and argues against helical growth. The rate of microtubule formation was increased by the same factors known to enhance taxoid-induced microtubule stability. The results suggest that taxoids induce the accretion of the existing Mg(2+)-induced GDP-tubulin oligomers, thus forming small bidimensional polymers that are necessary to nucleate the microtubular sheets, possibly by binding to or modifying the lateral interaction sites between tubulin dimers. 相似文献
969.
Two cold-inducible genes encoding lipid transfer protein LTP4 from barley show differential responses to bacterial pathogens 总被引:7,自引:0,他引:7
A. Molina I. Diaz P. Carbonero F. García-Olmedo I. K. Vasil 《Molecular & general genetics : MGG》1996,252(1-2):162-168
The barley genesHvLtp4.2 andHvLtp4.3 both encode the lipid transfer protein LTP4 and are less than 1 kb apart in tail-to-tail orientation. They differ in their non-coding regions from each other and from the gene corresponding to a previously reportedLtp4 cDNA (nowLtp4.1). Southern blot analysis indicated the existence of three or moreLtp4 genes per haploid genome and showed considerable polymorphism among barley cultivars. We have investigated the transient expression of genesHvLtp4.2 andHvLtp4.3 following transformation by particle bombardment, using promoter fusions to the-glucuronidase reporter sequence. In leaves, activities of the two promoters were of the same order as those of the sucrose synthase (Ss1) and cauliflower mosaic virus 35S promoters used as controls. Their expression patterns were similar, except thatLtp4.2 was more active thanLtp4.3 in endosperm, andLtp4.3 was active in roots, whileLtp4.2 was not. The promoters of both genes were induced by low temperature, both in winter and spring barley cultivars. Northern blot analysis, using theLtp4-specific probe, indicated thatXanthomonas campestris pv.translucens induced an increase over basal levels ofLtp4 mRNA, whilePseudomonas syringae pv.japonica caused a decrease. TheLtp4.3-Gus promoter fusion also responded in opposite ways to these two compatible bacterial pathogens, whereas theLtp4.2-Gus construction did not respond to infection. 相似文献
970.
Metabolism of methylated osmolytes by aerobic bacteria from Mono Lake, a moderately hypersaline, alkaline environment 总被引:2,自引:0,他引:2
Abstract: Three strains of aerobic bacteria were isolated from water and sediment samples of Mono Lake, a moderately hypersaline (90 ppt), alkaline (pH 9.7) lake in California. The organisms, Gram-negative rods, grew fastest at about pH 9.7 with no growth or much slower growth at pH 7.0. All three isolates grew on glycine betaine (GB) and respirometric experiments indicated that catabolism was by sequential demethylation with dimethyl glycine and sarcosine as intermediates. Two of the isolates also grew on dimethylsulfoniopropionate (DMSP), one with cleavage of the DMSP to yield dimethyl sulfide (DMS) and acrylate, and the other by demethylation with 3-methiolpropionate (MMPA) as an intermediate and the production of methanethiol from MMPA. The methylated osmolytes supported growth at salinities similar to those in Mono Lake, but, at higher salinities, catabolism was suppressed and GB and DMSP functioned as osmolytes. GB and DMSP probably originate from cyanobacteria and/or phytoplankton in Mono Lake and this report is the first indication of both the DMS and demethylation/methanethiol-producing pathways for DMSP degradation in a nonmarine environment. 相似文献