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101.
Erick R. James Noriko Okamoto Fabien Burki Rudolf H. Scheffrahn Patrick J. Keeling 《PloS one》2013,8(3)
The parabasalian symbionts of lower termite hindgut communities are well-known for their large size and structural complexity. The most complex forms evolved multiple times independently from smaller and simpler flagellates, but we know little of the diversity of these small flagellates or their phylogenetic relationships to more complex lineages. To understand the true diversity of Parabasalia and how their unique cellular complexity arose, more data from smaller and simpler flagellates are needed. Here, we describe two new genera of small-to-intermediate size and complexity, represented by the type species Cthulhu macrofasciculumque and Cthylla microfasciculumque from Prorhinotermes simplex and Reticulitermes virginicus, respectively (both hosts confirmed by DNA barcoding). Both genera have a single anterior nucleus embeded in a robust protruding axostyle, and an anterior bundle flagella (and likely a single posterior flagellum) that emerge slightly subanteriorly and have a distinctive beat pattern. Cthulhu is relatively large and has a distinctive bundle of over 20 flagella whereas Cthylla is smaller, has only 5 anterior flagella and closely resembles several other parababsalian genera. Molecular phylogenies based on small subunit ribosomal RNA (SSU rRNA) show both genera are related to previously unidentified environmental sequences from other termites (possibly from members of the Tricercomitidae), which all branch as sisters to the Hexamastigitae. Altogether, Cthulhu likely represents another independent origin of relatively high cellular complexity within parabasalia, and points to the need for molecular characterization of other key taxa, such as Tricercomitus. 相似文献
102.
Sabrina Briefer Freymond Elodie F. Briefer Rudolf Von Niederh?usern Iris Bachmann 《PloS one》2013,8(1)
Horses are often kept in individual stables, rather than in outdoor groups, despite such housing system fulfilling many of their welfare needs, such as the access to social partners. Keeping domestic stallions in outdoor groups would mimic bachelor bands that are found in the wild. Unfortunately, the high level of aggression that unfamiliar stallions display when they first encounter each other discourages owners from keeping them in groups. However, this level of aggression is likely to be particularly important only during group integration, when the dominance hierarchy is being established, whereas relatively low aggression rates have been observed among stable feral bachelor bands. We investigated the possibility of housing breeding stallions owned by the Swiss National Stud in groups on a large pasture (5 stallions in 2009 and 8 stallions in 2010). We studied the pattern of agonistic, ritual and affiliative interactions after group integration (17–23 days), and the factors influencing these interactions (time after group integration, dominance rank, age or experience of group housing). We found that stallions displayed generally more ritual than agonistic and than affiliative interactions. The frequency of agonistic and ritual interactions decreased quickly within the first three to four days. The frequency of affiliative interactions increased slowly with time before decreasing after 9–14 days. A stable hierarchy could be measured after 2–3 months. The highest-ranking males had less ritual interactions than the lowest-ranking. Males had also less agonistic, ritual and affiliative interactions if they had already been housed in a group the previous year. Therefore, we found that breeding stallions could be housed together on a large pasture, because the frequency of agonistic interactions decreased quickly and remained at a minimal level from the fourth day following group integration. This housing system could potentially increase horse welfare and reduce labour associated with horse management. 相似文献
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104.
To perform their diverse biological functions the adhesion activities of the cell adhesion molecules of the immunoglobulin superfamily (IgCAMs) might be regulated by local clustering, proteolytical shedding of their ectodomains or rapid recycling to and from the plasma membrane. Another form of regulation of adhesion might be obtained through flexible ectodomains of IgCAMs which adopt distinct conformations and which in turn modulate their adhesion activity. Here, we discuss variations in the conformation of the extracellular domains of CEACAM1 and CAR that might influence their binding and signaling activities. Furthermore, we concentrate on alternative splicing of single domains and short segments in the extracellular regions of L1 subfamily members that might affect the organization of the N-terminal located Ig-like domains. In particular, we discuss variations of the linker sequence between Ig-like domains 2 and 3 (D2 and D3) that is required for the horseshoe conformation. 相似文献
105.
Christin M. Bennke Thomas R. Neu Bernhard M. Fuchs Rudolf Amann 《Systematic and applied microbiology》2013
The degradation of diatoms is mainly catalyzed by Bacteroidetes and this process is of global relevance for the carbon cycle. In this study, a combination of catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) and fluorescent lectin binding analysis (FLBA) was used to identify and map glycoconjugates involved in the specific interactions of Bacteroidetes and diatoms, as well as detritus, at the coastal marine site Helgoland Roads (German Bight, North Sea). The study probed both the presence of lectin-specific extracellular polymeric substances (EPS) of Bacteroidetes for cell attachment and that of glycoconjugates on diatoms with respect to binding sites for Bacteroidetes. Members of the clades Polaribacter and Ulvibacter were shown to form microcolonies within aggregates for which FLBA indicated the presence of galactose containing slime. Polaribacter spp. was shown to bind specifically to the setae of the abundant diatom Chaetoceros spp., and the setae were stained with fucose-specific lectins. In contrast, Ulvibacter spp. attached to diatoms of the genus Asterionella which bound, among others, the mannose-specific lectin PSA. The newly developed CARD-FISH/FLBA protocol was limited to the glycoconjugates that persisted after the initial CARD-FISH procedure. The differential attachment of bacteroidetal clades to diatoms and their discrete staining by FLBA provided evidence for the essential role that formation and recognition of glycoconjugates play in the interaction of bacteria with phytoplankton. 相似文献
106.
Nina M. Pollak Martina Schweiger Doris Jaeger Dagmar Kolb Manju Kumari Renate Schreiber Stephanie Kolleritsch Philipp Markolin Gernot F. Grabner Christoph Heier Kathrin A. Zierler Thomas Rülicke Robert Zimmermann Achim Lass Rudolf Zechner Guenter Haemmerle 《Journal of lipid research》2013,54(4):1092-1102
Cardiac triacylglycerol (TG) catabolism critically depends on the TG hydrolytic activity of adipose triglyceride lipase (ATGL). Perilipin 5 (Plin5) is expressed in cardiac muscle (CM) and has been shown to interact with ATGL and its coactivator comparative gene identification-58 (CGI-58). Furthermore, ectopic Plin5 expression increases cellular TG content and Plin5-deficient mice exhibit reduced cardiac TG levels. In this study we show that mice with cardiac muscle-specific overexpression of perilipin 5 (CM-Plin5) massively accumulate TG in CM, which is accompanied by moderately reduced fatty acid (FA) oxidizing gene expression levels. Cardiac lipid droplet (LD) preparations from CM of CM-Plin5 mice showed reduced ATGL- and hormone-sensitive lipase-mediated TG mobilization implying that Plin5 overexpression restricts cardiac lipolysis via the formation of a lipolytic barrier. To test this hypothesis, we analyzed TG hydrolytic activities in preparations of Plin5-, ATGL-, and CGI-58-transfected cells. In vitro ATGL-mediated TG hydrolysis of an artificial micellar TG substrate was not inhibited by the presence of Plin5, whereas Plin5-coated LDs were resistant toward ATGL-mediated TG catabolism. These findings strongly suggest that Plin5 functions as a lipolytic barrier to protect the cardiac TG pool from uncontrolled TG mobilization and the excessive release of free FAs. 相似文献
107.
Chandramohan Chitraju Martin Tr?tzmüller Jürgen Hartler Heimo Wolinski Gerhard G. Thallinger Guenter Haemmerle Rudolf Zechner Robert Zimmermann Harald C. K?feler Friedrich Spener 《Journal of lipid research》2013,54(8):2185-2194
We showed earlier that nutritional stress like starvation or high-fat diet resulted in phenotypic changes in the lipidomes of hepatocyte lipid droplets (LDs), representative for the pathophysiological status of the mouse model. Here we extend our former study by adding genetic stress due to knockout (KO) of adipocyte triglyceride lipase (ATGL), the rate limiting enzyme in LD lipolysis. An intervention trial for 6 weeks with male wild-type (WT) and ATGL-KO mice was carried out; both genotypes were fed lab chow or were exposed to short-time starvation. Isolated LDs were analyzed by LC-MS/MS. Triacylglycerol, diacylglycerol, and phosphatidylcholine lipidomes, in that order, provided the best phenotypic signatures characteristic for respective stresses applied to the animals. This was evidenced at lipid species level by principal component analysis, calculation of average values for chain-lengths and numbers of double bonds, and by visualization in heat maps. Structural backgrounds for analyses and metabolic relationships were elaborated at lipid molecular species level. Relating our lipidomic data to nonalcoholic fatty liver diseases of nutritional and genetic etiologies with or without accompanying insulin resistance, phenotypic distinction in hepatocyte LDs dependent on insulin status emerged. Taken together, lipidomes of hepatocyte LDs are sensitive responders to nutritional and genetic stress. 相似文献
108.
Shuning Wang Haiyan Huang J?rg Kahnt Alexander P. Mueller Michael K?pke Rudolf K. Thauer 《Journal of bacteriology》2013,195(19):4373-4386
Flavin-based electron bifurcation is a recently discovered mechanism of coupling endergonic to exergonic redox reactions in the cytoplasm of anaerobic bacteria and archaea. Among the five electron-bifurcating enzyme complexes characterized to date, one is a heteromeric ferredoxin- and NAD-dependent [FeFe]-hydrogenase. We report here a novel electron-bifurcating [FeFe]-hydrogenase that is NADP rather than NAD specific and forms a complex with a formate dehydrogenase. The complex was found in high concentrations (6% of the cytoplasmic proteins) in the acetogenic Clostridium autoethanogenum autotrophically grown on CO, which was fermented to acetate, ethanol, and 2,3-butanediol. The purified complex was composed of seven different subunits. As predicted from the sequence of the encoding clustered genes (fdhA/hytA-E) and from chemical analyses, the 78.8-kDa subunit (FdhA) is a selenocysteine- and tungsten-containing formate dehydrogenase, the 65.5-kDa subunit (HytB) is an iron-sulfur flavin mononucleotide protein harboring the NADP binding site, the 51.4-kDa subunit (HytA) is the [FeFe]-hydrogenase proper, and the 18.1-kDa (HytC), 28.6-kDa (HytD), 19.9-kDa (HytE1), and 20.1-kDa (HytE2) subunits are iron-sulfur proteins. The complex catalyzed both the reversible coupled reduction of ferredoxin and NADP+ with H2 or formate and the reversible formation of H2 and CO2 from formate. We propose the complex to have two functions in vivo, namely, to normally catalyze CO2 reduction to formate with NADPH and reduced ferredoxin in the Wood-Ljungdahl pathway and to catalyze H2 formation from NADPH and reduced ferredoxin when these redox mediators get too reduced during unbalanced growth of C. autoethanogenum on CO (E0′ = −520 mV). 相似文献
109.
110.