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41.
Extrusomes in ciliates: diversification, distribution, and phylogenetic implications 总被引:3,自引:0,他引:3
Exocytosis is, in all likelihood, an important communication method among microbes. Ciliates are highly differentiated and specialized micro-organisms for which versatile and/or sophisticated exocytotic organelles may represent important adaptive tools. Thus, in ciliates, we find a broad range of different extrusomes, i.e ejectable membrane-bound organelles. Structurally simple extrusomes, like mucocysts and cortical granules, are widespread in different taxa within the phylum. They play the roles in each case required for the ecological needs of the organisms. Then, we find a number of more elaborate extrusomes, whose distribution within the phylum is more limited, and in some way related to phylogenetic affinities. Herein we provide a survey of literature and our data on selected extrusomes in ciliates. Their morphology, distribution, and possible function are discussed. The possible phylogenetic implications of their diversity are considered. 相似文献
42.
43.
The role of adult faeces in juvenile nutrition of two isopod species, Proasellus coxalis s.l. and Asellus aquaticus (L.),
with similar trophic strategies and different reproductive output, has been studied in laboratory. Our aim was to consider
the possible competitive mechanisms occurring at the beginning of the species coexistence using allopatric populations in
single and mixed species experiments. Two series of competition experiments were performed. In the first, adult specimens
were used for breeding and feeding trials. Both population dynamics and the percentage of ovigerous females and juveniles
were evaluated during 10 months. Adult densities and juvenile percentage of A.aquaticus were lower in the presence of P. coxalis
s.l. than when alone. At the end of the breeding experiments the dietary preferences of adults on a set of fungally conditioned
leaf discs were not different among treatments. In the second series of experiments, the influence of coexistence on the feeding
rates of young asellids and the relative importance of faeces and decaying plant material in their diet were investigated.
Individual consumption by wild juveniles in multiple-choice laboratory experiments was measured by radioisotopes (32
2P). Juveniles of P. coxalis s.l. showed the highest ingestion rates. In co-occurrence, contrary to A.aquaticus, they were
able to further increase feeding on parental faeces. The role of parental faeces in the diet of the two species juveniles
and the competitive dominance of P. coxalis s.l. are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
44.
Ali Munaim Yousif Michele Minopoli Katia Bifulco Vincenzo Ingangi Gioconda Di Carluccio Francesco Merlino Maria Letizia Motti Paolo Grieco Maria Vincenza Carriero 《PloS one》2015,10(5)
The receptor for the urokinase-type plasminogen activator (uPAR) is a widely recognized master regulator of cell migration and uPAR88-92 is the minimal sequence required to induce cell motility. We and others have previously documented that the uPAR88-92 sequence, even in the form of synthetic linear peptide (SRSRY), interacts with the formyl peptide receptor type 1 (FPR1), henceforth inducing cell migration of several cell lines, including monocytes. FPR1 is mainly expressed by mammalian phagocytic leukocytes and plays a crucial role in chemotaxis. In this study, we present evidence that the cyclization of the SRSRY sequence generates a new potent and stable inhibitor of monocyte trafficking. In rat basophilic leukaemia RBL-2H3/ETFR cells expressing high levels of constitutively activated FPR1, the cyclic SRSRY peptide ([SRSRY]) blocks FPR1 mediated cell migration by interfering with both internalization and ligand-uptake of FPR1. Similarly to RBL-2H3/ETFR cells, [SRSRY] competes with fMLF for binding to FPR1 and prevents agonist-induced FPR1 internalization in human monocyte THP-1 cells. Unlike scramble [RSSYR], [SRSRY] inhibits fMLF-directed migration of monocytes in a dose-dependent manner, with IC50 value of 0.01 nM. PMA-differentiated THP-1 cell exposure to fMLF gradient causes a marked cytoskeletal re-organization with the formation of F-actin rich pseudopodia that are prevented by the addition of [SRSRY]. Furthermore, [SRSRY] prevents migration of human primary monocytes and trans-endothelial migration of monocytes. Our findings indicate that [SRSRY] is a new FPR1 inhibitor which may suggest the development of new drugs for treating pathological conditions sustained by increased motility of monocytes, such as chronic inflammatory diseases. 相似文献
45.
46.
Most people prefer smoothly curved shapes over more angular shapes. We investigated the origin of this effect using abstract shapes and implicit measures of semantic association and preference. In Experiment 1 we used a multidimensional Implicit Association Test (IAT) to verify the strength of the association of curved and angular polygons with danger (safe vs. danger words), valence (positive vs. negative words) and gender (female vs. male names). Results showed that curved polygons were associated with safe and positive concepts and with female names, whereas angular polygons were associated with danger and negative concepts and with male names. Experiment 2 used a different implicit measure, which avoided any need to categorise the stimuli. Using a revised version of the Stimulus Response Compatibility (SRC) task we tested with a stick figure (i.e., the manikin) approach and avoidance reactions to curved and angular polygons. We found that RTs for approaching vs. avoiding angular polygons did not differ, even in the condition where the angles were more pronounced. By contrast participants were faster and more accurate when moving the manikin towards curved shapes. Experiment 2 suggests that preference for curvature cannot derive entirely from an association of angles with threat. We conclude that smoothly curved contours make these abstract shapes more pleasant. Further studies are needed to clarify the nature of such a preference. 相似文献
47.
Most infections are caused by bacteria, many of which are ever-evolving and resistant to nearly all available antibiotics. β-Lactams and glycopeptides are used to combat these infections by inhibiting bacterial cell-wall synthesis. This mechanism remains an interesting target in the search for new antibiotics in light of failed genomic approaches and the limited input of major pharmaceutical companies. Several strategies have enriched the pipeline of bacterial cell-wall inhibitors; examples include combining screening strategies with lesser-explored microbial diversity, or reinventing known scaffolds based on structure-function relationships. Drugs developed using novel strategies will contribute to the arsenal in fight against the continued emergence of bacterial resistance. 相似文献
48.
Trincavelli ML Cuboni S Catena Dell'osso M Maggio R Klotz KN Novi F Panighini A Daniele S Martini C 《Purinergic signalling》2010,6(4):373-381
A(2A) adenosine receptors are considered an excellent target for drug development in several neurological and psychiatric disorders. It is noteworthy that the responses evoked by A(2A) adenosine receptors are regulated by D(2) dopamine receptor ligands. These two receptors are co-expressed at the level of the basal ganglia and interact to form functional heterodimers. In this context, possible changes in A(2A) adenosine receptor functional responses caused by the chronic blockade/activation of D(2) dopamine receptors should be considered to optimise the therapeutic effectiveness of dopaminergic agents and to reduce any possible side effects. In the present paper, we investigated the regulation of A(2A) adenosine receptors induced by antipsychotic drugs, commonly acting as D(2) dopamine receptor antagonists, in a cellular model co-expressing both A(2A) and D(2) receptors. Our data suggest that the treatment of cells with the classical antipsychotic haloperidol increased both the affinity and responsiveness of the A(2A) receptor and also affected the degree of A(2A)-D(2) receptor heterodimerisation. In contrast, an atypical antipsychotic, clozapine, had no effect on A(2A) adenosine receptor parameters, suggesting that the two classes of drugs have different effects on adenosine-dopamine receptor interaction. Modifications to A(2A) adenosine receptors may play a significant role in determining cerebral adenosine effects during the chronic administration of antipsychotics in psychiatric diseases and may account for the efficacy of A(2A) adenosine receptor ligands in pathologies associated with dopaminergic system dysfunction. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11302-010-9201-z) contains supplementary material, which is available to authorized users. 相似文献
49.
D'Abrosca B Fiorentino A Pacifico S Cefarelli G Uzzo P Letizia M Monaco P 《Bioorganic & medicinal chemistry letters》2007,17(15):4135-4139
Nine novel natural feruloyl monoglyceride (MGs) macrocycles have been isolated from the leaves of Carex distachya, an herbaceous plant growing in the Mediterranean maquis. All the structures have been elucidated on the basis of their spectroscopic features, especially two-dimensional NMR (DQ-COSY, TOCSY, NOESY, ROESY, HSQC, HMBC, HSQC-TOCSY) and ESI-MS. All the compounds have been assayed as protecting factors against the radical damage of the lipids by using different antioxidant tests. 相似文献
50.
Debiaggi M Canducci F Terulla C Sampaolo M Marinozzi MC Alessandrino PE Colombo AA Caldera D Bragotti LZ Migliavacca R Bianchi E Romero E Clementi M 《The new microbiologica》2007,30(3):255-258
From October 2004 through October 2006 a study was performed to evaluate the prevalence of human Metapneumovirus (hMPV) infection in adult hematopoietic stem cell transplant (HSCT) recipients. Sequential nasopharyngeal aspirates (NPA) were collected independently from respiratory symptoms and evaluated for hMPV-RNA by polymerase chain reaction (PCR) and sequence analysis. Results indicate epidemiological and molecular differences between the 2004-2005 and 2005-2006 periods and that hMPV seems not to symptomatically affect HSCT patients or cause late respiratory sequelae. In addition, data collected suggest a hospital origin of hMPV infection in most HSCT patients during the 2004-2005 period. 相似文献