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101.
The genus Phytophthora, belonging to the class Oomycota, comprises a group of over fifty fungus-like plant pathogens in both managed and unmanaged ecosystems. A unique feature of the oomycete lifecycle is a zoosporic stage in which motile, unicellular propagules, serving as the primary agents of dispersal, are produced and released in the presence of water. In Petri dish suspensions, zoospores frequently exhibit 'pattern swimming', whereby they spontaneously form concentrated swimming masses, visible to the naked eye, even in the absence of a chemical or electrical gradient. The nature of this behaviour is unclear, but is of interest because of the potential for auto-attraction and implications for cohort recruitment during infection. Similar behaviour observed in a variety of motile bacteria, algae, and protists is attributed to 'bioconvection' that results from instability in fluid density due to the organisms' upward-swimming tendency and greater-than-water density. In this investigation, we determined that Phytophthora citricola zoospore 'pattern swimming' is unrelated to phototaxis, surface tension-driven (Marangoni) convection, or auto-attraction and that the observed convective pattern, directional swimming, and depth- and concentration dependence are consistent with bioconvection. 相似文献
102.
103.
Esposito G Scuderi C Valenza M Togna GI Latina V De Filippis D Cipriano M Carratù MR Iuvone T Steardo L 《PloS one》2011,6(12):e28668
Peroxisome proliferator-activated receptor-γ (PPARγ) has been reported to be involved in the etiology of pathological features of Alzheimer's disease (AD). Cannabidiol (CBD), a Cannabis derivative devoid of psychomimetic effects, has attracted much attention because of its promising neuroprotective properties in rat AD models, even though the mechanism responsible for such actions remains unknown. This study was aimed at exploring whether CBD effects could be subordinate to its activity at PPARγ, which has been recently indicated as its putative binding site. CBD actions on β-amyloid-induced neurotoxicity in rat AD models, either in presence or absence of PPAR antagonists were investigated. Results showed that the blockade of PPARγ was able to significantly blunt CBD effects on reactive gliosis and subsequently on neuronal damage. Moreover, due to its interaction at PPARγ, CBD was observed to stimulate hippocampal neurogenesis. All these findings report the inescapable role of this receptor in mediating CBD actions, here reported. 相似文献
104.
Multiple myeloma (MM) is a B cell neoplasm characterized by bone marrow infiltration with malignant plasma cells. IGF-1 signalling has been explored as a therapeutic target in this disease. We analyzed the effect of the IKK2 inhibitor AS602868, in combination with a monoclonal antibody targeting IGF-1 receptor (anti-IGF-1R) in human MM cell lines. We found that anti-IGF-1R potentiated the apoptotic effect of AS602868 in LP1 and RPMI8226 MM cell lines which express high levels of IGF-1R. Anti-IGF-1R enhanced the inhibitory effect of AS602868 on NF-κB pathway signalling and potentiated the disruption of mitochondrial membrane potential caused by AS602868. These results support the role of IGF-1 signalling in MM and suggest that inhibition of this pathway could sensitize MM cells to NF-κB inhibitors. 相似文献
105.
Denitrifying organisms are essential in removing fixed nitrogen pollutants from ecosystems (e.g. sewage sludge). They can be detrimental (e.g. for agricultural soil) and can also produce the greenhouse gas N2O (nitrous oxide). Therefore a more comprehensive understanding of this process has become increasingly important regarding its global environmental impact. Even though bacterial genome sequencing projects may reveal new data, to date the denitrification abilities and features in Gram-positive bacteria are still poorly studied and understood. The present review evaluates current knowledge on the denitrification trait in Gram-positive bacteria and addresses the likely existence of unknown denitrification genes. In addition, current molecular tools to study denitrification gene diversity in pure cultures and environmental samples seem to be highly biased, and additional novel approaches for the detection of denitrifying (Gram-positive) bacteria appear to be crucial in re-assessing the real diversity of denitrifiers. 相似文献
106.
Plants,microorganisms, and soil temperatures contribute to a decrease in methane fluxes on a drained Arctic floodplain 下载免费PDF全文
Min Jung Kwon Felix Beulig Iulia Ilie Marcus Wildner Kirsten Küsel Lutz Merbold Miguel D. Mahecha Nikita Zimov Sergey A. Zimov Martin Heimann Edward A. G. Schuur Joel E. Kostka Olaf Kolle Ines Hilke Mathias Göckede 《Global Change Biology》2017,23(6):2396-2412
As surface temperatures are expected to rise in the future, ice‐rich permafrost may thaw, altering soil topography and hydrology and creating a mosaic of wet and dry soil surfaces in the Arctic. Arctic wetlands are large sources of CH4, and investigating effects of soil hydrology on CH4 fluxes is of great importance for predicting ecosystem feedback in response to climate change. In this study, we investigate how a decade‐long drying manipulation on an Arctic floodplain influences CH4‐associated microorganisms, soil thermal regimes, and plant communities. Moreover, we examine how these drainage‐induced changes may then modify CH4 fluxes in the growing and nongrowing seasons. This study shows that drainage substantially lowered the abundance of methanogens along with methanotrophic bacteria, which may have reduced CH4 cycling. Soil temperatures of the drained areas were lower in deep, anoxic soil layers (below 30 cm), but higher in oxic topsoil layers (0–15 cm) compared to the control wet areas. This pattern of soil temperatures may have reduced the rates of methanogenesis while elevating those of CH4 oxidation, thereby decreasing net CH4 fluxes. The abundance of Eriophorum angustifolium, an aerenchymatous plant species, diminished significantly in the drained areas. Due to this decrease, a higher fraction of CH4 was alternatively emitted to the atmosphere by diffusion, possibly increasing the potential for CH4 oxidation and leading to a decrease in net CH4 fluxes compared to a control site. Drainage lowered CH4 fluxes by a factor of 20 during the growing season, with postdrainage changes in microbial communities, soil temperatures, and plant communities also contributing to this reduction. In contrast, we observed CH4 emissions increased by 10% in the drained areas during the nongrowing season, although this difference was insignificant given the small magnitudes of fluxes. This study showed that long‐term drainage considerably reduced CH4 fluxes through modified ecosystem properties. 相似文献
107.
Studies that have examined pet loss hypothesize that attachment, representations of death, and the belief in an afterlife for animals may influence owners’ bereavement and depressive outcomes. The following instruments were administered to 159 Italian participants recruited through snowball sampling: the Lexington Attachment to Pets Scale (LAPS), the Pet Bereavement Questionnaire (PBQ), the Testoni Death Representation Scale (TDRS), and Beck’s Depression Inventory II (BDI-II). Questions concerning pet euthanasia-related issues and the relationship between owners and veterinarians were also submitted to the participants. A path model was conducted, showing that the representation of death and the attachment to a pet had a direct effect on pet grief, which in turn had a direct effect on depression. The results show a positive correlation between the LAPS and PBQ factors, particularly with the PBQ factor Grief. The LAPS factors positively correlated with the TDRS representation of Death as a Passage and negatively correlated with the TDRS representation of Death as Annihilation. The LAPS People Substituting factor positively correlated with the total score and the Cognitive-Affective factor of the BDI-II. The PBQ factors positively correlated with the BDI-II, whereas only the TDRS Death as Annihilation factor positively correlated with the BDI-II. Belief in a transcendent dimension was associated with higher scores on the PBQ Guilt factor and the TDRS factors of Death as a Passage and Death as Change, whereas these beliefs were associated with lower scores on the TDRS factor Death as Annihilation.
The results indicated that the sensitivity of the veterinarian and a veterinarian who helps owners make conscious and informed decisions for their pet and choose the right time to perform euthanasia are important variables in the management of pet loss. However, these factors are not sufficient and psychological support should be improved to help owners better cope with grief. 相似文献
108.
SiuShing Wong Zachary M Wilmott Saroj Saurya Ines AlvarezRodrigo Felix Y Zhou KwaiYin Chau Alain Goriely Jordan W Raff 《The EMBO journal》2022,41(11)
Mitotic centrosomes are formed when centrioles start to recruit large amounts of pericentriolar material (PCM) around themselves in preparation for mitosis. This centrosome “maturation” requires the centrioles and also Polo/PLK1 protein kinase. The PCM comprises several hundred proteins and, in Drosophila, Polo cooperates with the conserved centrosome proteins Spd‐2/CEP192 and Cnn/CDK5RAP2 to assemble a PCM scaffold around the mother centriole that then recruits other PCM client proteins. We show here that in Drosophila syncytial blastoderm embryos, centrosomal Polo levels rise and fall during the assembly process—peaking, and then starting to decline, even as levels of the PCM scaffold continue to rise and plateau. Experiments and mathematical modelling indicate that a centriolar pulse of Polo activity, potentially generated by the interaction between Polo and its centriole receptor Ana1 (CEP295 in humans), could explain these unexpected scaffold assembly dynamics. We propose that centrioles generate a local pulse of Polo activity prior to mitotic entry to initiate centrosome maturation, explaining why centrioles and Polo/PLK1 are normally essential for this process. 相似文献
109.
Leão SC Bernardelli A Cataldi A Zumarraga M Robledo J Realpe T Mejía GI da Silva Telles MA Chimara E Velazco M Fernandez J Rodrigues PA Guerrero MI León CI Porras TB Rastogi N Goh KS Suffys P da Silva Rocha A dos Santos Netto D Ritacco V López B Barrera L Palomino JC Martin A Portaels F 《Journal of microbiological methods》2005,61(2):193-199
The identification of mycobacterial species in clinical isolates is essential for making patient care decisions. Polymerase chain reaction (PCR) restriction enzyme analysis (PRA) is a simple and rapid identification method, based on amplification of 441 bp of the hsp65 gene and restriction with BstEII and HaeIII. As a contribution to the validation of PRA, a multicenter study was performed in eight laboratories located in Argentina, Brazil, Colombia, Chile, and Guadeloupe. Each laboratory received 18 coded isolates from the collection of the Institute of Tropical Medicine (Antwerp, Belgium), representing duplicates of nine laboratory strains: Mycobacterium terrae CIPT 140320001, Mycobacterium scrofulaceum CIPT 140220031, Mycobacterium flavescens ATCC 14474, Mycobacterium triviale ATCC 23292, Mycobacterium nonchromogenicum ATCC 19530, Mycobacterium chitae ATCC 19627, Mycobacterium abscessus ATCC 19977, Mycobacterium kansasii ATCC 12478, and Mycobacterium peregrinum ATCC 14467. A detailed protocol including amplification, enzymatic digestion, and gel preparation was provided to each laboratory. Two laboratories identified correctly all 18 (100%) isolates, one identified correctly 17 (94.5%), two identified 14 (77.7%), one identified 11 (61%), and two identified 8 (44.4%) isolates. Errors detected in laboratories with more than 77% accuracy were associated with electrophoresis running conditions and an unspecific amplicon produced by a single strain. Lower accuracy was mainly related to inappropriate use of DNA markers and insufficient training in interpretation of patterns. In conclusion, the PRA method was readily implemented in some Latin American and Caribbean laboratories of mycobacteria, but improvements in critical points, as gel running conditions and training in interpretiation of patterns, are needed in order to improve accuracy. In others, improvement in critical points is still necessary. 相似文献
110.
Venzke D Domgall I Köcher T Féthière J Fischer S Böttcher B 《Journal of molecular biology》2005,349(3):659-669
V-ATPases are membrane protein complexes that pump protons in the lumen of various subcellular compartments at the expense of ATP. Proton pumping is done by a rotary mechanism that requires a static connection between the membrane pumping domain (V(0)) and the extrinsic catalytic head (V(1)). This static connection is composed of several known subunits of the V-ATPase, but their location and topological relationships are still a matter of controversy. Here, we propose a model for the V-ATPase of Neurospora crassa on the basis of single-particle analysis by electron microscopy. Comparison of the resulting map to that of the A-ATPase from Thermus thermophilus allows the positioning of two subunits in the static connecting region that are unique to eukaryotic V-ATPases (C and H). These two subunits seem to be located on opposite sides of a semicircular arrangement of the peripheral connecting elements, suggesting a role in stabilizing the stator in V-ATPases. 相似文献