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971.
A molecular phylogeny of Hebeloma species from Europe 总被引:2,自引:1,他引:1
Herbert Boyle Bettina Zimdars Carsten Renker Franois Buscot 《Mycological Research》2006,110(4):369-380
In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section. 相似文献
972.
Faithful recombination and chromosome segregation in meiosis require regulated steps of homolog recognition and association which are monitored by meiotic checkpoints. A recent study in the nematode Caenorhabditis elegans has identified a checkpoint mechanism that monitors chromosome pairing during meiosis. 相似文献
973.
Expansins are involved in the formation of nematode-induced syncytia in roots of Arabidopsis thaliana 总被引:1,自引:0,他引:1
974.
975.
Phosphorylation of phenol by phenylphosphate synthase: role of histidine phosphate in catalysis
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Narmandakh A Gad'on N Drepper F Knapp B Haehnel W Fuchs G 《Journal of bacteriology》2006,188(22):7815-7822
The anaerobic metabolism of phenol proceeds via carboxylation to 4-hydroxybenzoate by a two-step process involving seven proteins and two enzymes ("biological Kolbe-Schmitt carboxylation"). MgATP-dependent phosphorylation of phenol catalyzed by phenylphosphate synthase is followed by phenylphosphate carboxylation. Phenylphosphate synthase shows similarities to phosphoenolpyruvate (PEP) synthase and was studied for the bacterium Thauera aromatica. It consists of three proteins and transfers the beta-phosphoryl from ATP to phenol; the products are phenylphosphate, AMP, and phosphate. We showed that protein 1 becomes phosphorylated in the course of the reaction cycle by [beta-(32)P]ATP. This reaction requires protein 2 and is severalfold stimulated by protein 3. Stimulation of the reaction by 1 M sucrose is probably due to stabilization of the protein(s). Phosphorylated protein 1 transfers the phosphoryl group to phenolic substrates. The primary structure of protein 1 was analyzed by nanoelectrospray mass spectrometry after CNBr cleavage, trypsin digestion, and online high-pressure liquid chromatography at alkaline pH. His-569 was identified as the phosphorylated amino acid. We propose a catalytic ping-pong mechanism similar to that of PEP synthase. First, a diphosphoryl group is transferred to His-569 in protein 1, from which phosphate is cleaved to render the reaction unidirectional. Histidine phosphate subsequently serves as the actual phosphorylation agent. 相似文献
976.
Tropinone reductases (TRs) are essential enzymes in the tropane alkaloid biosynthesis, providing either tropine for hyoscyamine and scopolamine formation or providing pseudotropine for calystegines. Two cDNAs coding for TRs were isolated from potato (Solanum tuberosum L.) tuber sprouts and expressed in E. coli. One reductase formed pseudotropine, the other formed tropine and showed kinetic properties typical for tropine-forming tropinone reductases (TRI) involved in hyoscyamine formation. Hyoscyamine and tropine are not found in S. tuberosum plants. Potatoes contain calystegines as the only products of the tropane alkaloid pathway. Polyclonal antibodies raised against both enzymes were purified to exclude cross reactions and were used for Western-blot analysis and immunolocalisation. The TRI (EC 1.1.1.206) was detected in protein extracts of tuber tissues, but mostly in levels too low to be localised in individual cells. The function of this enzyme in potato that does not form hyoscyamine is not clear. The pseudotropine-forming tropinone reductase (EC 1.1.1.236) was detected in potato roots, stolons, and tuber sprouts. Cortex cells of root and stolon contained the protein; additional strong immuno-labelling was located in phloem parenchyma. In tuber spouts, however, the protein was detected in companion cells. 相似文献
977.
978.
Lutz Auerswald Carsten Pape Dorothee Stübing Andreas Lopata Bettina Meyer 《Journal of experimental marine biology and ecology》2009,381(1):47-56
We investigated the effect of short-term starvation (18 days) on the physiology of adult Euphausia superba from the Lazarev Sea at the onset of summer. Metabolic data, elemental and biochemical composition as well as morphological parameters revealed that, at the beginning of the experiment, krill was in transition from winter to summer physiology, with some features typical for late winter/spring (low lipid reserves, low C:N ratio, elevated O:N ratio) and others for summer (high respiration rates, high MDH activity, large green digestive gland, short intermoult period (IMP) and fast growth).Starvation reduced body reserves drastically by more than 1% C per day. In relative terms, lipids (40%) and glycogen (30%) were reduced most and proteins by 10% of the initial value. Absolute consumption, however, was approximately 4% DM for lipids and proteins each, whereas contribution of glycogen was negligible. Within lipids, triacylglycerols (TAG) and phospholipids (PL) fell most dramatically from already low levels by 84% and 39%, respectively. Phosphatylcholine (PC) constituted 57% of PL and declined by 46%. As a result, proportions of the lipid classes changed with sterols increasing relatively. Metabolite changes were similar in cephalothorax and abdomen, although TAG in the cephalothorax fell more drastically. High metabolic activity at the beginning of starvation was quickly reduced to reach 53% after 18 days, accompanied by a reduction in the abdominal activity of malate dehydrogenase (MDH) by 25%. Our results may provide some explanation why recruitment of some year-classes of krill fails.Despite execution of the experiment in spring (i.e. transitional physiology state) and its short duration, some changes in the activity of metabolic enzymes in the abdomen, representing lipolytic, glycolytic and proteolytic pathways, respectively, were measured. Rising activities of 3-hydroxyacyl-CoA dehydrogenase (HOAD) and glyceralaldehyde-3-phosphate dehydrogenase (GAPDH) indicated increased lipolytic and glycolytic fluxes, respectively, whereas declining glutamate dehydrogenase (GluDH) activity suggests reduced proteolytic flux. Activities of other enzymes from protein catabolism, alanine aminotransferase (AlaAT) and aspartate aminotransferase (AspAT), however, remained unchanged. Ratios calculated from these trends indicated a declining importance of protein use during the course of starvation compared with consumption of lipids and glycogen. These results suggest that constant-proportion enzymes from different catabolic pathways, and calculated ratios thereof, may be useful in detecting shifts between the consumption of different body reserves. 相似文献
979.
Shigeru Itoh Takashi Kozuki Koji Nishida Yoshimasa Fukushima Hisanori Yamakawa Ildikó Domonkos Hajnalka Laczkó-Dobos Mihály Kis Bettina Ughy Zoltán Gombos 《BBA》2012,1817(2):287-297
Functional roles of an anionic lipid phosphatidylglycerol (PG) were studied in pgsA-gene-inactivated and cdsA-gene-inactivated/phycobilisome-less mutant cells of a cyanobacterium Synechocystis sp. PCC 6803, which can grow only in PG-supplemented media. 1) A few days of PG depletion suppressed oxygen evolution of mutant cells supported by p-benzoquinone (BQ). The suppression was recovered slowly in a week after PG re-addition. Measurements of fluorescence yield indicated the enhanced sensitivity of QB to the inactivation by BQ. It is assumed that the loss of low-affinity PG (PGL) enhances the affinity for BQ that inactivates QB. 2) Oxygen evolution without BQ, supported by the endogenous electron acceptors, was slowly suppressed due to the direct inactivation of QB during 10 days of PG depletion, and was recovered rapidly within 10 h upon the PG re-addition. It is concluded that the loss of high-affinity PG (PGH) displaces QB directly. 3) Electron microscopy images of PG-depleted cells showed the specific suppression of division of mutant cells, which had developed thylakoid membranes attaching phycobilisomes (PBS). 4) Although the PG-depletion for 14 days decreased the chlorophyll/PBS ratio to about 1/4, florescence spectra/lifetimes were not modified indicating the flexible energy transfer from PBS to different numbers of PSII. Longer PG-depletion enhanced allophycocyanin fluorescence at 683 nm with a long 1.2 ns lifetime indicating the suppression of energy transfer from PBS to PSII. 5) Action sites of PGH, PGL and other PG molecules on PSII structure are discussed. 相似文献
980.
Zinka B Kandlbinder R Schupfner R Haas G Wolfbeis OS Graw M 《Anthropologischer Anzeiger; Bericht über die biologisch-anthropologische Literatur》2012,69(2):147-157
Reliable determination of time since death in human skeletons or single bones often is limited by methodically difficulties. Determination of the specific activity ratio of natural radionuclides, in particular of 232Th (Thorium), 228Th and 228Ra (Radium) seems to be a new appropriate method to calculate the post mortem interval. These radionuclides are incorporated by any human being, mainly from food. So with an individual's death the uptake of radionuclides ends. But the decay of 232Th produces 228Ra and 228Th due to its decay series, whereas 228Th is continuously built up in the human's bones. Thus, it can be concluded that in all deceased humans at different times after death different activity ratios of 228Th to 228Ra will develop in bone. According to this fact it should be possible to calculate time since death of an individual by first analysing the specific activities of 228Th and 228Ra in bones of deceased and then determining the 228Th/228Ra activity ratio, which can be assigned to a certain post-mortem interval. 相似文献