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81.
Assembly of active Fe-hydrogenase in the chloroplasts of the green alga Chlamydomonas reinhardtii requires auxiliary maturases, the S-adenosylmethionine-dependent enzymes HydG and HydE and the GTPase HydF. Genes encoding homologous maturases had been found in the genomes of all eubacteria that contain Fe-hydrogenase genes but not yet in any other eukaryote. By means of proteomic analysis, we identified a homologue of HydG in the hydrogenosomes, mitochondrion-related organelles that produce hydrogen under anaerobiosis by the activity of Fe-hydrogenase, in the pathogenic protist Trichomonas vaginalis. Genes encoding two other components of the Hyd system, HydE and HydF, were found in the T. vaginalis genome database. Overexpression of HydG, HydE, and HydF in trichomonads showed that all three proteins are specifically targeted to the hydrogenosomes, the site of Fe-hydrogenase maturation. The results of Neighbor-Net analyses of sequence similarities are consistent with a common eubacterial ancestor of HydG, HydE, and HydF in T. vaginalis and C. reinhardtii, supporting a monophyletic origin of Fe-hydrogenase maturases in the two eukaryotes. Although Fe-hydrogenases exist in only a few eukaryotes, related Narf proteins with different cellular functions are widely distributed. Thus, we propose that the acquisition of Fe-hydrogenases, together with Hyd maturases, occurred once in eukaryotic evolution, followed by the appearance of Narf through gene duplication of the Fe-hydrogenase gene and subsequent loss of the Hyd proteins in eukaryotes in which Fe-hydrogenase function was lost. 相似文献
82.
Background and Aims
Adventitious sprouting from the hypocotyle and roots in monocarpic herbs has been confirmed in previous experimental studies as a means to avoid bud limitation after severe injury in annual and biennial plants. Data regarding the role of adventitious sprouting in natural populations, however, were lacking. The aim of the present study was to assess whether adventitious sprouting occurs in natural populations and how it is affected by plant size, plant injury, plant cover and environmental characteristics.Methods
Data were sampled from 14 037 individual plants from 389 populations belonging to 22 annual and biennial species. Growth parameters were measured in individual plants, species composition and plant cover in communities were evaluated, and environmental characteristics were estimated using Ellenberg indicator values.Key Results
It was confirmed that adventitious sprouting occurs in natural populations of all but five species examined. Adventitious sprouting was positively affected by plant size and plant injury. Environmental factors including availability of soil nitrogen were not shown to affect adventitious sprouting. Annual and biennial plants did not differ in sprouting, but upright annuals had a lower number of and longer adventitious shoots than prostrate annuals.Conclusions
Adventitious bud formation is used to overcome meristem limitation when stem parts are lost due to injury, and thus resprouting in short-lived monocarps should not be overlooked. 相似文献83.
Lenka Franková Katarína Cibírová Károly Bóka Otília Gašparíková Mikuláš Pšenák 《Biologia》2006,61(1):97-102
Colchicum autumnale L. is a monocotyledonous geophyte with hysteranthous leaves, i.e. flowering and leaf growth occur in different time periods.
Because after the starch, the second prominent storage compound of corm is represented by proteins, we were interested in
nitrogen remobilisation during the annual life cycle of C. autumnale. In this context the content of soluble and insoluble proteins were measured in parallel with determination of some exo-and
endopeptidase activities. Our results indicate that the continual proteolysis occurs in both mother and new daughter corms
during the whole life-cycle of the plant. L-Ala-aminopeptidase and trypsin-like endopeptidase were the most active peptidases
in both mother and daughter corms. As the protein level of mother corm did not change significantly during the development
of the future above-ground part under the soil surface (the first, autumnal developmental stage), the developmental profile
of nitrate reductase activity was estimated followed by evaluation of total nitrogen and amino acid contents. Significant
activity of root nitrate reductase was detected in the roots only in the second, vernal stage. Our results showed that the
stored proteins constituted a relevant nitrogen source partly required by the growth processes of the late autumnal stage,
but mainly by the intensive growth of leaves and reproductive structures during the second, photosynthetically active stage
of the life-cycle. 相似文献
84.
During 2009 and 2010 samples from 251 wild birds (37 species) from nine sites of Slovakia were collected. Blood samples were tested for Plasmodium, Haemoproteus, and Leucocytozoon spp. parasites using both PCR-based and microscopy techniques. The overall prevalence of infection was 56.6%, while prevalence of Haemoproteus a Plasmodium spp. (were evaluated separately from Leucocytozoon) was 46.6% and the prevalence of Leucocytozoon spp. was 33.9%. After microscopic examination of stained blood smears the identification of haemoproteids was performed. There were 14 species of three genera identified, i.e., Haemoproteus parabelopolskyi, H. belopolskyi, H. magnus, H. fallisi, H. fringillae, H. balmorali, H. dolniki, H. tartakovskyi, H. lanii, Leucocytozoon majoris, L. dubreuili, Plasmodium vaughani, P. relictum, P. circumflexum. Except for H. fringillae, H. balmorali, H. belopolskyi, L. majoris and L. dubreuili, the mentioned species of parasites were recorded for the first time in Slovakia. 相似文献
85.
86.
Bopegamage S Precechtelova J Marosova L Stipalova D Sojka M Borsanyiova M Gomolcak P Berakova K Galama JM 《FEMS immunology and medical microbiology》2012,64(2):184-190
Enteroviral infections go usually unnoticed, even during pregnancy, yet some case histories and mouse experiments indicate that these viruses may be transmitted vertically. More frequently, however, transmission occurs by (fecal) contamination during and shortly after birth. The aim of this study was to investigate the effect of maternal infection in mice (1) on gravidity outcome and (2) on subsequent challenge of the offspring with the same virus. CD1 outbred female mice were infected by the oral route with coxsackievirus B4 strain E2 or mock-infected at days 4, 10, or 17 of gestation. Weight and signs of sickness were noted daily. Pups were infected at day 25 after birth (4 days postweaning). Organs (brain, pancreas, and heart) were analyzed for viral RNA and histopathology. We observed that maternal infection at day 4 or day 17 of gestation had little effect on pregnancy outcome, whereas infection at day 10 affected dams and/or offspring. Infection of pups resulted in severe inflammation of the pancreas, but only when dams were previously infected, especially at day 17. The blood glucose levels were elevated. Because no trace of infection was found at the time of challenge, a role for immunopathology is suggested. 相似文献
87.
R Marchetti L Malinovska E Lameignère L Adamova C de Castro G Cioci C Stanetty P Kosma A Molinaro M Wimmerova A Imberty A Silipo 《Glycobiology》2012,22(10):1387-1398
Bacteria from the Burkholderia cepacia complex (Bcc) cause highly contagious pneumonia among cystic fibrosis (CF) patients. Among them, Burkholderia cenocepacia is one of the most dangerous in the Bcc and is the most frequent cause of morbidity and mortality in CF patients. Indeed, it is responsible of "cepacia syndrome", a deadly exacerbation of infection, that is the main cause of poor outcomes in lung transplantation. Burkholderia cenocepacia produces several soluble lectins with specificity for fucosylated and mannosylated glycoconjugates. These lectins are present on the bacterial cell surface and it has been proposed that they bind to lipopolysaccharide epitopes. In this work, we report on the interaction of one B. cenocepacia lectin, BC2L-A, with heptose and other manno configured sugar residues. Saturation transfer difference NMR spectroscopy studies of BC2L-A with different mono- and disaccharides demonstrated the requirement of manno configuration with the hydroxyl or glycol group at C6 for the binding process. The crystal structure of BC2L-A complexed with the methyl-heptoside confirmed the location of the carbohydrate ring in the binding site and elucidated the orientation of the glycol tail, in agreement with NMR data. Titration calorimetry performed on monosaccharides, heptose disaccharides and bacterial heptose-containing oligosaccharides and polysaccharides confirmed that bacterial cell wall contains carbohydrate epitopes that can bind to BC2L-A. Additionally, the specific binding of fluorescent BC2L-A lectin on B. cenocepacia bacterial surface was demonstrated by microscopy. 相似文献
88.
Plant Aurora kinases play a role in maintenance of primary meristems and control of endoreduplication 总被引:1,自引:0,他引:1
Petrovská B Cenklová V Pochylová Z Kourová H Doskočilová A Plíhal O Binarová L Binarová P 《The New phytologist》2012,193(3):590-604
? The conserved family of Aurora kinases has multiple functions during mitosis. The roles of plant Aurora kinases have been characterized using inhibitor treatments. ? We down-regulated Aurora kinases in Arabidopsis thaliana using RNA interference (RNAi). We carried out a detailed phenotypic analysis of Aurora RNAi plants, biochemical and microscopic studies of AtAurora1 kinase together with AtTPX2 (targeting protein for Xklp2) and γ-tubulin. ? Cell division defects were observed in plants with reduced expression of Aurora kinases. Furthermore, the maintenance of primary meristems was compromised and RNAi seedlings entered endoreduplication prematurely. AtAurora1, its activator AtTPX2, and γ-tubulin were associated with microtubules in vitro; they were attached to regrowing kinetochore microtubules and colocalized on spindle microtubules and with a subset of early phragmoplast microtubules. Only the AtAurora1 kinase was translocated to the area of the cell plate. ? RNAi silencing of Aurora kinases showed that, in addition to their function in regulating mitosis, the kinases are required for maintaining meristematic activity and controlling the switch from meristematic cell proliferation to differentiation and endoreduplication. The colocalization and co-fractionation of AtAurora1 with AtTPX2, and γ-tubulin on microtubules in a cell cycle-specific manner suggests that AtAurora1 kinase may function to phosphorylate substrates that are critical to the spatiotemporal regulation of acentrosomal microtubule formation and organization. 相似文献
89.
Vokřál I Bártíková H Prchal L Stuchlíková L Skálová L Szotáková B Lamka J Várady M Kubíček V 《Parasitology》2012,139(10):1309-1316
SUMMARY Haemonchus contortus is one of the most pathogenic parasites of small ruminants (e.g. sheep and goat). The treatment of haemonchosis is complicated because of recurrent resistance of H. contortus to common anthelmintics. The aim of this study was to compare the metabolism of the anthelmintic drug flubendazole (FLU) and the activities of selected biotransformation enzymes towards model xenobiotics in 4 different strains of H. contortus: the ISE strain (susceptible to common anthelmintics), ISE-S (resistant to ivermectin), the BR strain (resistant to benzimidazole anthelmintics) and the WR strain (resistant to all common anthelmintics). H. contortus adults were collected from the abomasums from experimentally infected lambs. The in vitro as well as ex vivo experiments were performed and analysed using HPLC with spectrofluorimetric and mass-spectrometric detection. In all H. contortus strains, 4 different FLU metabolites were detected: FLU with a reduced carbonyl group (FLU-R), glucose conjugate of FLU-R and 2 glucose conjugates of FLU. In the resistant strains, the ex vivo formation of all FLU metabolites was significantly higher than in the susceptible ISE strain. The multi-resistant WR strain formed approximately 5 times more conjugates of FLU than the susceptible ISE strain. The in vitro data also showed significant differences in FLU metabolism, in the activities of UDP-glucosyltransferase and several carbonyl-reducing enzymes between the susceptible and resistant H. contortus strains. The altered activities of certain detoxifying enzymes might protect the parasites against the toxic effect of the drugs as well as contribute to drug-resistance in these parasites. 相似文献
90.
Dagmar Skálová Božena Navrátilová Lenka Richterová Michal Knit Michal Sochor Radim J. Vašut 《Central European Journal of Biology》2012,7(5):931-940
Many populations of high-mountainous relic dioecious willows in Central Europe only consist of female individuals and are
thus limited in their reproductive potential. We completed micropropagation experiments with shoot apexes and nodal segments
of common and endangered willow (Salix) species, which can help to reintroduce autochthonous genotypes to their natural sites. Until recently, cultivation of green
young shoot apexes of S. alba and S. lapponum showed the highest percentage of regeneration. We successfully applied the two-times-sterilisation due to high contamination
of natural explants. The OK medium was the most efficient culture medium. In vitro propagation of willows with unisexual catkins, anther and ovule cultures were tested and optimised. Isolated anthers were
cultivated on selected media and then microcallus and calluses of S. caprea and calluses of S. viminalis were formed on the A medium. Among various tested and optimised media for the ovule culture, the CP medium was the most efficient
one. In this case, only the microcalluses of S. viminalis were observed. We developed biotechnological procedures that can be useful in conserving fragmented populations of high-mountainous
willows. 相似文献