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131.
132.
Buckwalter MR Nga PT Gouilh MA Fiette L Bureau JF Laird ME Buchrieser J Ozden S Cheval J Eloit M Manuguerra JC Gessain A Brey PT Fontanet A Albert ML 《Journal of virology》2011,85(14):6893-6905
Theiler's murine encephalitis viruses (TMEV) are divided into two subgroups based on their neurovirulence. Persistent strains resemble Theiler's original viruses (referred to as the TO subgroup), which largely induce a subclinical polioencephalomyelitis during the acute phase of the disease and can persist in the spinal cord of susceptible animals, inducing a chronic demyelinating disease. In contrast, members of the neurovirulent subgroup cause an acute encephalitis characterized by the rapid onset of paralysis and death within days following intracranial inoculation. We report herein the characterization of a novel neurovirulent strain of TMEV, identified using pyrosequencing technology and referred to as NIHE. Complete coverage of the NIHE viral genome was obtained, and it shares <90% nucleotide sequence identity to known TMEV strains irrespective of subgroup, with the greatest sequence variability being observed in genes encoding the leader and capsid proteins. The histopathological analysis of infected brain and spinal cord demonstrate inflammatory lesions and neuronal necrosis during acute infection with no evidence of viral persistence or chronic disease. Intriguingly, genetic analysis indicates the putative expression of the L protein, considered a hallmark of strains within the persistent subgroup. Thus, the identification and characterization of a novel neurovirulent TMEV strain sharing features previously associated with both subgroups will lead to a deeper understanding of the evolution of TMEV strains and new insights into the determinants of neurovirulence. 相似文献
133.
Mustafa Solak Mujgan Ozdemir Erdogan Saliha Handan Yildiz Kagan Ucok Seref Yuksel Evrim Suna Arıkan Terzi Ahmet Bestepe 《Molecular biology reports》2014,41(11):7381-7386
The aim of this study is to investigate the genetic influence of polymorphisms in fat mass and obesity associated (FTO) gene on a sample of obese subjects and controls. Obesity is an epidemic all over the world. Several polymorphisms in the first intron of FTO gene have been associated with common forms of human obesity. In this research rs1421085 and rs9939609 polymorphisms of FTO gene were genotyped in 190 obese patients with a BMI ≥30 kg/m2 (Body Mass Index) and 97 healthy controls with a BMI of 18.5–24.9. Genotyping of SNPs was performed by real-time polymerase chain reaction. Body composition was established with bioelectric impedance analysis. Waist-to-hip ratio was determined for all participants. There were no significant differences (P > 0.05) between obese cases and controls in terms of genotype frequencies of rs1421085 and rs9939609 polymorphisms in our study. Also there were no significant correlations between genotypes and obesity related (anthropometric-body composition) parameters (P > 0.05). 相似文献
134.
Natália Salazar Mónica Marcela Castiblanco-Valencia Ludmila Bezerra da Silva íris Arantes de Castro Denize Monaris Hana Paula Masuda Angela Silva Barbosa Ana Paula Mattos Arêas 《PloS one》2014,9(11)
Infections caused by Staphylococcus aureus – particularly nosocomial infections - represent a great concern. Usually, the early stage of pathogenesis consists on asymptomatic nasopharynx colonization, which could result in dissemination to other mucosal niches or invasion of sterile sites, such as blood. This pathogenic route depends on scavenging of nutrients as well as binding to and disrupting extracellular matrix (ECM). Manganese transport protein C (MntC), a conserved manganese-binding protein, takes part in this infectious scenario as an ion-scavenging factor and surprisingly as an ECM and coagulation cascade binding protein, as revealed in this work. This study showed a marked ability of MntC to bind to several ECM and coagulation cascade components, including laminin, collagen type IV, cellular and plasma fibronectin, plasminogen and fibrinogen by ELISA. The MntC binding to plasminogen appears to be related to the presence of surface-exposed lysines, since previous incubation with an analogue of lysine residue, ε-aminocaproic acid, or increasing ionic strength affected the interaction between MntC and plasminogen. MntC-bound plasminogen was converted to active plasmin in the presence of urokinase plasminogen activator (uPA). The newly released plasmin, in turn, acted in the cleavage of the α and β chains of fibrinogen. In conclusion, we describe a novel function for MntC that may help staphylococcal mucosal colonization and establishment of invasive disease, through the interaction with ECM and coagulation cascade host proteins. These data suggest that this potential virulence factor could be an adequate candidate to compose an anti-staphylococcal human vaccine formulation. 相似文献
135.
Daniella Arêas Mendes-da-Cruz Anne Colette Brignier Vahid Asnafi Frederic Baleydier Carolina Valen?a Messias Yves Lepelletier Nawel Bedjaoui Amedée Renand Salete Smaniotto Danielle Canioni Pierre Milpied Karl Balabanian Philippe Bousso Stéphane Leprêtre Yves Bertrand Hervé Dombret Norbert Ifrah Mireille Dardenne Elizabeth Macintyre Wilson Savino Olivier Hermine 《PloS one》2014,9(7)
Neuropilins and semaphorins are known as modulators of axon guidance, angiogenesis, and organogenesis in the developing nervous system, but have been recently evidenced as also playing a role in the immune system. Here we describe the expression and role of semaphorin 3F (SEMA3F) and its receptor neuropilin-2 (NRP2) in human T cell precursors. NRP2 and SEMA3F are expressed in the human thymus, in both lymphoid and non-lymphoid compartments. SEMA3F have a repulsive effect on thymocyte migration and inhibited CXCL12- and sphingosine-1-phosphate (S1P)-induced thymocyte migration by inhibiting cytoskeleton reorganization prior to stimuli. Moreover, NRP2 and SEMA3F are expressed in human T-cell acute lymphoblastic leukemia/lymphoma primary cells. In these tumor cells, SEMA3F also blocks their migration induced by CXCL12 and S1P. Our data show that SEMA3F and NRP2 are further regulators of human thymocyte migration in physiological and pathological conditions. 相似文献
136.
Vera A González-Montalbán N Arís A Villaverde A 《Biotechnology and bioengineering》2007,96(6):1101-1106
Protein aggregation is a major bottleneck during the bacterial production of recombinant proteins. In general, the induction of gene expression at sub-optimal growth temperatures improves the solubility of aggregation-prone polypeptides and minimizes inclusion body (IB) formation. However, the effect of low temperatures on the quality of the recombinant protein, especially within the insoluble cell fraction, has been hardly ever explored. In this work, we have examined the conformational status of a recombinant GFP protein when produced in Escherichia coli below 37 degrees C. As expected, the fraction of aggregated protein largely decreased at lower temperatures, while the conformational quality of both soluble and aggregated GFP, as reflected by its specific fluorescence emission, progressively improved. This observation indicates that physicochemical conditions governing protein folding affect concurrently the quality of the soluble and the aggregated forms of a misfolding-prone protein, and that protein misfolding and aggregation are clearly not coincident events. 相似文献
137.
Small molecule inhibitors of cyclin-dependent kinases (CDKs) show high therapeutic potential in various cancer types which are characterized by the accumulation of transformed cells due to impaired apoptotic machinery. Roscovitine, a CDK inhibitor showed to be a potent apoptotic inducer in several cancer cells. Polyamines, putrescine, spermidine and spermine, are biogenic amines involved in many cellular processes, including apoptosis. In this study, we explored the potential role of polyamines in roscovitine-induced apoptosis in HCT116 colon cancer cells. Roscovitine induced apoptosis by activating mitochondrial pathway caspases and modulating the expression of Bcl-2 family members. Depletion of polyamines by treatment with difluoromethylornithine (DFMO) increased roscovitine-induced apoptosis. Transient silencing of ornithine decarboxylase, polyamine biosynthesis enzyme and special target of DFMO also increased roscovitine-induced apoptosis in HCT116 cells. Interestingly, additional putrescine treatment was found pro-apoptotic due to the presence of non-functional ornithine decarboxylase (ODC). Finally, roscovitine altered polyamine catabolic pathway and led to decrease in putrescine and spermidine levels. Therefore, the metabolic regulation of polyamines may dictate the power of roscovitine induced apoptotic responses in HCT116 colon cancer cells. 相似文献
138.
Molecular and morphological diversity of Trebouxia microalgae in sphaerothallioid Circinaria spp. lichens1
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Arántzazu Molins Francisco J. García‐Breijo José Reig‐Armiñana Eva Barreno 《Journal of phycology》2018,54(4):494-504
Three vagrant (Circinaria hispida, Circinaria gyrosa, and Circinaria sp. ‘paramerae’) and one crustose (semi‐vagrant, Circinaria sp. ‘oromediterranea’) lichens growing in very continental areas in the Iberian Peninsula were selected to study the phycobiont diversity. Mycobiont identification was checked using nrITS DNA barcoding: Circinaria sp. ‘oromediterranea’ and Circinaria sp. ‘paramerae’ formed a new clade. Phycobiont diversity was analyzed in 50 thalli of Circinaria spp. using nrITS DNA and LSU rDNA, with microalgae coexistence being found in all the species analyzed by Sanger sequencing. The survey of phycobiont diversity showed up to four different Trebouxia spp. as the primary phycobiont in 20 thalli of C. hispida, in comparison with the remaining Circinaria spp., where only one Trebouxia was the primary microalga. In lichen species showing coexistence, some complementary approaches are needed (454 pyrosequencing and/or ultrastructural analyses). Five specimens were selected for high‐throughput screening (HTS) analyses: 22 Trebouxia OTUs were detected, 10 of them not previously known. TEM analyses showed three different cell morphotypes (Trebouxia sp. OTU A12, OTU S51, and T. cretacea) whose ultrastructure is described here in detail for the first time. HTS revealed a different microalgae pool in each species studied, and we cannot assume a specific pattern between these pools and the ecological and/or morphological characteristics. The mechanisms involved in the selection of the primary phycobiont and the other microalgae by the mycobiont are unknown, and require complex experimental designs. The systematics of the genus Circinaria is not yet well resolved, and more analyses are needed to establish a precise delimitation of the species. 相似文献
139.
One-hundred and fifty different thermophilic bacteria isolated from a volcanic island were screened for detection of an alkane
hydroxylase gene using degenerated primers developed to amplify genes related to the Pseudomonas putida and Pseudomonas oleovorans alkane hydroxylases. Ten isolates carrying the alkJ gene were further characterized by 16s rDNA gene sequencing. Nine out of ten isolates were phylogenetically affiliated with
Geobacillus species and one isolate with Bacillus species. These isolates were able to grow in liquid cultures with crude oil as the sole carbon source and were found to degrade
long chain crude oil alkanes in a range between 46.64% and 87.68%. Results indicated that indigenous thermophilic hydrocarbon
degraders of Bacillus and Geobacillus species are of special significance as they could be efficiently used for bioremediation of oil-polluted soil and composting
processes. 相似文献
140.
Thomas Kitzberger Ezequiel Aráoz Juan H. Gowda Mónica Mermoz Juan M. Morales 《Ecosystems》2012,15(1):97-112
The generalization that plant communities increase in flammability as they age and invariably lead to resilient self-organized
landscape mosaics is being increasingly challenged. Plant communities often exhibit rapidly saturating or even hump-shaped
age-flammability trajectories and landscapes often display strong non-linear behaviors, abrupt shifts, and self-reinforcing
alternative community states. This plethora of fire-landscape interactions calls for a more general model that considers alternative
age-flammability rules. We simulated landscape dynamics assuming communities that (1) increase in flammability with age and
(2) gain flammability up to a certain age followed by a slight and moderate loss to a constant value. Simulations were run
under combinations of ignition frequency and interannual climatic variability. Age-increasing fire probability promoted high
resilience to changes in ignition frequency and climatic variability whereas humpbacked-shaped age-flammability led to strong
non-linear behaviors. Moderate (20%) reductions in mature compared to peak flammability produced the least resilient behaviors.
The relatively non-flammable mature forest matrix intersected by young flammable patches is prone to break up and disintegrate
with slight increases in ignition/climate variability causing large-scale shifts in the fire regime because large fires were
able to sweep through the more continuous young/flammable landscape. Contrary to the dominant perception, fire suppression
in landscapes with positive feedbacks may effectively reduce fire occurrence by allowing less flammable later stage communities
composed of longer lived, obligate seeders to replace earlier stages of light demanding, often more flammable resprouters.
Conversely, increases in anthropogenic ignitions, a common global trend of many forested regions may, in synergism with increased
climate variability, induce abrupt shifts, and large-scale forest degradation. 相似文献