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Symbiotic System (symbiotic + system)
Selected AbstractsCospeciation in the triplex symbiosis of termite gut protists (Pseudotrichonympha spp.), their hosts, and their bacterial endosymbiontsMOLECULAR ECOLOGY, Issue 6 2007S. NODA Abstract A number of cophylogenetic relationships between two organisms namely a host and a symbiont or parasite have been studied to date; however, organismal interactions in nature usually involve multiple members. Here, we investigated the cospeciation of a triplex symbiotic system comprising a hierarchy of three organisms , termites of the family Rhinotermitidae, cellulolytic protists of the genus Pseudotrichonympha in the guts of these termites, and intracellular bacterial symbionts of the protists. The molecular phylogeny was inferred based on two mitochondrial genes for the termites and nuclear small-subunit rRNA genes for the protists and their endosymbionts, and these were compared. Although intestinal microorganisms are generally considered to have looser associations with the host than intracellular symbionts, the Pseudotrichonympha protists showed almost complete codivergence with the host termites, probably due to strict transmissions by proctodeal trophallaxis or coprophagy based on the social behaviour of the termites. Except for one case, the endosymbiotic bacteria of the protists formed a monophyletic lineage in the order Bacteroidales, and the branching pattern was almost identical to those of the protists and the termites. However, some non-codivergent evolutionary events were evident. The members of this triplex symbiotic system appear to have cospeciated during their evolution with minor exceptions; the evolutionary relationships were probably established by termite sociality and the complex microbial community in the gut. [source] Euplotes daidaleos and its endocytobiontsTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2005SERGEI I. FOKIN Among almost 200 endocytobiotic associations between freshwater ciliates and Chlorella -like algae (A) one Euplotes species,E. daidaleos Diller, Kounaris, 1966 is existing. It was not so far under particular investigation. Comparative study of cell morphology and behavior of "green" and derived from it "white" stocks of the ciliate (C), collected in Italy and Russia were carried out, using light and electron microscopy. The green C usually maintain 30,80 units of A and some bacteria (B), belonging to the different types,Polynucleobacter -like bacterium, ,-subgroup of Proteobacteria (size about 2,10 × 0.4,0.5 ,m) and another eubacterium (size 1,2 × 0.6,0.8 ,m). The number of the first B was much higher in the white C, but could vary between different host cells. According to data obtained with fluorescent microscopy it looks like these B can produce long chains, which consisted of quite short individuals with only one nucleoid. Association between Euplotes and Chlorella within the system is rather a close one: loss of the A after long time cultivation of C in darkness usually did not happen. The majority of the ciliates (96,100%) kept A, but this number often dropped down, apparently as a result of digestion by C of some of the A. Positive phototaxis is almost absent in green E. daidaleos in comparison with that of Paramecium bursaria,Chlorella association. The rate of division was not significantly deviated according to A presence. Moreover, cells of the green Euplotes did not like high level of illumination and in any cases needed some additional food. This situation is also quite opposite to the P. bursaria,Chlorella system. In between 2 and 3 months of cultivation, the main part of the white stocks have lost its viability partly because of disturbance in the cirral pattern. In about 90% of cells some frontal, ventral, transversal and caudal cirri disappeared in different combinations. It is the first indication on some connection between A-symbionts and host morphogenesis. Large food vacuoles almost all time presented in such cells show some kind of problems with digestion as well. E. daidaleos could be considered as three-lateral symbiotic system, promising for further investigations. [source] The symbiotic system CH Cygni: An analysis of the shocked nebulae at different epochsASTRONOMISCHE NACHRICHTEN, Issue 8 2009M. Contini Abstract We analyse the line and continuum spectra of the symbiotic system CH Cygni. We adopt the colliding-wind model to explain the symbiotic system at different phases. Peculiar observed features such as flickering, radio variation, X-ray emission, as well as the distribution of the nebulae and shells throughout the system are investigated by modelling the spectra at different epochs. The models account consistently for shock and photoionization and are constrained by absolute fluxes. We find that the reverse shock between the stars leads to the broad lines observed during the active phases, as well as to radio and hard X-ray emission, while the expanding shock is invoked to explain the data particularly during the transition phases (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Two-step counterdiffusion protocol for the crystallization of haemoglobin II from Lucina pectinata in the pH range 4,9ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2010Carlos A. Nieves-Marrero Lucina pectinata haemoglobin II (HbII) transports oxygen in the presence of H2S to the symbiotic system in this bivalve mollusc. The composition of the haem pocket at the distal site includes TyrB10 and GlnE7, which are very common in other haem proteins. Obtaining crystals of oxyHbII at various pH values is required in order to elucidate the changes in the conformations of TyrB10 and GlnE7 and structural scenarios induced by changes in pH. Here, the growth of crystals of oxyHbII using the capillary counterdiffusion (CCD) technique at various pH values using a two-step protocol is reported. In the first step, a mini-screen was used to validate sodium formate as the best precipitating reagent for the growth of oxyHbII crystals. The second step, a pH screen typically used for optimization, was used to produce crystals in the pH range 4,9. Very well faceted prismatic ruby-red crystals were obtained at all pH values. X-ray data sets were acquired using synchrotron radiation of wavelength 0.886,Å (for the crystals obtained at pH 5) and 0.908,Å (for those obtained at pH 4, 8 and 9) to maximum resolutions of 3.30, 1.95, 1.85 and 2.00,Å for the crystals obtained at pH 4, 5, 8 and 9, respectively. All of the crystals were isomorphous and belonged to space group P42212. [source] | ||||||||||