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981.
982.
983.
Weidler GW Dornmayr-Pfaffenhuemer M Gerbl FW Heinen W Stan-Lotter H 《Applied and environmental microbiology》2007,73(1):259-270
Scanning electron microscopy revealed great morphological diversity in biofilms from several largely unexplored subterranean thermal Alpine springs, which contain radium 226 and radon 222. A culture-independent molecular analysis of microbial communities on rocks and in the water of one spring, the "Franz-Josef-Quelle" in Bad Gastein, Austria, was performed. Four hundred fifteen clones were analyzed. One hundred thirty-two sequences were affiliated with 14 bacterial operational taxonomic units (OTUs) and 283 with four archaeal OTUs. Rarefaction analysis indicated a high diversity of bacterial sequences, while archaeal sequences were less diverse. The majority of the cloned archaeal 16S rRNA gene sequences belonged to the soil-freshwater-subsurface (1.1b) crenarchaeotic group; other representatives belonged to the freshwater-wastewater-soil (1.3b) group, except one clone, which was related to a group of uncultivated Euryarchaeota. These findings support recent reports that Crenarchaeota are not restricted to high-temperature environments. Most of the bacterial sequences were related to the Proteobacteria (alpha, beta, gamma, and delta), Bacteroidetes, and Planctomycetes. One OTU was allied with Nitrospina sp. (delta-Proteobacteria) and three others grouped with Nitrospira. Statistical analyses suggested high diversity based on 16S rRNA gene analyses; the rarefaction plot of archaeal clones showed a plateau. Since Crenarchaeota have been implicated recently in the nitrogen cycle, the spring environment was probed for the presence of the ammonia monooxygenase subunit A (amoA) gene. Sequences were obtained which were related to crenarchaeotic amoA genes from marine and soil habitats. The data suggested that nitrification processes are occurring in the subterranean environment and that ammonia may possibly be an energy source for the resident communities. 相似文献
984.
Ana Paula M. Bernardi Natasha Maurmann Sandra B. Rech Gilsane von Poser 《Acta Physiologiae Plantarum》2007,29(2):165-170
Hypericum polyanthemum Klotzsch ex Reichardt, an endemic species of Southern Brazil, was micropropagated on MS medium supplemented with 1.78 μM
BAP. Shoot proliferation and rooting was achieved on hormone-free medium and plantlets survived acclimatization. The bioactive
compounds: 6-isobutyryl-5,7-dimethoxy-2,2-dimethyl-benzopyran (HP1), 7-hydroxy-6-isobutyryl-5-methoxy-2,2-dimethyl-benzopyran
(HP2) and 5-hydroxy-6-isobutyryl-7-methoxy-2,2-dimethyl-benzopyran (HP3) were quantified in the leaves, stems and roots of
propagated and acclimatized plantlets and compared with the field-grown plants. The HPLC analysis revealed that the three
benzopyrans are accumulated in the aerial parts and the concentration varied with the age of the plant whereas the roots were
capable of accumulating only HP3. Greatest yield of HP1 (7.12 mg/g DW) was quantified in the leaves of the acclimatized plantlets,
whereas the flowers of the plants from natural habitat displayed higher amounts of HP2 (11.04 mg/g DW) and HP3 (13.99 mg/g
DW). 相似文献
985.
White matter oligodendrocytes have been shown to actively regulate extracellular glutamate levels in the CNS. Such function has yet not been examined in satellite oligodendrocytes of gray matter. Similar to those in white matter, satellite oligodendrocytes are involved in myelination. In addition, they modulate the activity of surrounding neurons. This study examined whether satellite oligodendrocytes express PACAP and glutamate transporter proteins and whether this expression is influenced by global ischemia. We demonstrated expression of PACAP27 and PACAP38 in a major fraction of satellite oligodendrocytes in normal neocortex and hippocampus of human brain tissues obtained post-mortem. All three glutamate transporters EAAT1, EAAT2 and EAAT3 were expressed in satellite oligodendrocytes from these tissues. Thus, satellite oligodendrocytes may participate in the perineuronal glutamate homeostasis. Following transient global ischemia, the total number of satellite oligodendrocytes expressing PACAP or glutamate transporter proteins was significantly decreased in cerebral neocortex and hippocampus. However, alterations of PACAP and glutamate transporter protein expression were region and time specific. In satellite oligodendrocytes of CA1 an early strong reduction of PACAP and glutamate transporter expression was observed. This contrasted with late reduction of PACAP27, PACAP38 and glutamate transporters EAAT1, EAAT2 and EAAT3 in satellite oligodendrocytes of neocortex. Further studies should clarify whether these alterations in protein expression are primary or secondary to neuronal cell death. 相似文献
986.
Maria Ernfors Karin von Arnold Johan Stendahl Mats Olsson Leif Klemedtsson 《Biogeochemistry》2007,84(2):219-231
Total emissions of N2O from drained organic forest soils in Sweden were estimated using an equation linking the C:N ratio of the soil to N2O emissions. Information on soil C:N ratios was derived from a national database. It was estimated that the emissions from
Histosols amount to 2,820 tonnes N2O a−1. This is almost five times the value calculated for the same soils using the method suggested by the Intergovernmental Panel
on Climate Change: 580 tonnes N2O a−1. The higher value in the present study can mainly be explained by improved accuracy of estimates of N2O emissions from nutrient-rich soils, including former agricultural soils. In Sweden, in addition to 0.94 Mha of drained Histosols,
there are 0.55 Mha of other types of drained organic soils. The annual emissions from these soils were estimated to amount
to 1,890 tonnes of N2O. The total emission value calculated for drained organic forest soils was thus 4,700 tonnes N2O a−1, which, if added, would increase the current estimate of the Swedish anthropogenic N2O source strength by 18%. Of these emissions, 88% occur from sites with C:N ratios lower than 25. The exponential relationship
between C:N ratio and N2O emissions, in combination with a scarcity of data, resulted in large confidence intervals around the estimates. However,
by using the C:N ratio-based method, N2O emission estimates can be calculated from a variable that is readily available in databases. Also, the recent findings that
there are exceptionally large emissions of N2O from the most nitrogen-rich drained organic forest soils are taken into account. 相似文献
987.
Vallez-Chetreanu F Fraisse Ferreira LG Rabe R von Stockar U Marison IW 《Journal of biotechnology》2007,130(3):265-273
The main limitation in the use of spin-filters during perfusion cultures of animal cells was revealed to be filter fouling. This phenomenon involves cell-sieve interactions as well as cell attachment to, and growth on, the filter surface. The cell attachment effect has been analysed in the present study during long-term perfusion simulations with CHO animal cells. It was demonstrated that at low filter acceleration, below 6.2 m/s2, a high perfusion rate of 25 cm/h induced rapid filter pore clogging within 3 days, whereas increasing the filter acceleration to 25 m/s2 increased filter longevity from 3 to 25 days, for filters with a pore size of 8.5 microm. Increasing the filter pore size to 14.5 microm improved filter longevity by 84% with less viable and dead cell deposits on the filter surface. However, it was demonstrated that filter longevity was not necessarily dependent on the amount of cell deposit on the filter surface. In the second part of this study, ultrasonic technology was used to reduce filter fouling. Filter vibration, induced by a piezo actuator, improved filter longevity by 113% during CHO cells perfusion cultures. 相似文献
988.
Kleffmann T von Zychlinski A Russenberger D Hirsch-Hoffmann M Gehrig P Gruissem W Baginsky S 《Plant physiology》2007,143(2):912-923
We have analyzed proteome dynamics during light-induced development of rice (Oryza sativa) chloroplasts from etioplasts using quantitative two-dimensional gel electrophoresis and tandem mass spectrometry protein identification. In the dark, the etioplast allocates the main proportion of total protein mass to carbohydrate and amino acid metabolism and a surprisingly high number of proteins to the regulation and expression of plastid genes. Chaperones, proteins for photosynthetic energy metabolism, and enzymes of the tetrapyrrole pathway were identified among the most abundant etioplast proteins. The detection of 13 N-terminal acetylated peptides allowed us to map the exact localization of the transit peptide cleavage site, demonstrating good agreement with the prediction for most proteins. Based on the quantitative etioplast proteome map, we examined early light-induced changes during chloroplast development. The transition from heterotrophic metabolism to photosynthesis-supported autotrophic metabolism was already detectable 2 h after illumination and affected most essential metabolic modules. Enzymes in carbohydrate metabolism, photosynthesis, and gene expression were up-regulated, whereas enzymes in amino acid and fatty acid metabolism were significantly decreased in relative abundance. Enzymes involved in nucleotide metabolism, tetrapyrrole biosynthesis, and redox regulation remained unchanged. Phosphoprotein-specific staining at different time points during chloroplast development revealed light-induced phosphorylation of a nuclear-encoded plastid RNA-binding protein, consistent with changes in plastid RNA metabolism. Quantitative information about all identified proteins and their regulation by light is available in plprot, the plastid proteome database (http://www.plprot.ethz.ch). 相似文献
989.
von Engelhardt W Dycker Ch Lechner-Doll M 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(6):631-640
In camelids the ventral parts of compartments 1 and 2 (C1/C2) and the total surface of compartment 3 of the forestomach are
lined with tubular glands, whereas in ruminants the surface of the forestomach is composed entirely of stratified, squamous
epithelium. Thus, differences in absorption rates between these foregut fermenters can be expected. In five camels C1/C2 was
temporarily isolated, washed and filled with buffer solutions. Absorption of short-chain fatty acids (SCFA) and net absorption
of sodium and water were estimated relative to Cr-ethylenediaminetetraacetic acid as a fluid marker. SCFA were extensively
absorbed in the forestomach; clearance rates of SCFA with different chain lengths were equal. After lowering the pH of solutions
SCFA absorption rates increased, but much less than the increase of the non-ionized fraction. Absorption of propionate was
lower when acetate had been added. Findings suggest that most of the SCFA in camels are transported in the ionized form, most
likely via an anion exchange mechanism. Net water absorption is closely related to net sodium absorption. Apparently water
absorption results from an iso-osmotic process. Differences between absorption mechanisms of SCFA from the forestomach of
camelids and ruminants are discussed. 相似文献
990.
Nigg AP Zahn S Rückerl D Hölscher C Yoshimoto T Ehrchen JM Wölbing F Udey MC von Stebut E 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(11):7251-7258
Protection against Leishmania major in resistant C57BL/6 mice is mediated by Th1 cells, whereas susceptibility in BALB/c mice is the result of Th2 development. IL-12 release by L. major-infected dendritic cells (DC) is critically involved in differentiation of Th1 cells. Previously, we reported that strain differences in the production of DC-derived factors, e.g., IL-1alphabeta, are in part responsible for disparate disease outcome. In the present study, we analyzed the release of IL-12 from DC in more detail. Stimulated DC from C57BL/6 and BALB/c mice released comparable amounts of IL-12p40 and p70. In the absence of IL-4, BALB/c DC produced significantly more IL-12p40 than C57BL/6 DC. Detailed analyses by Western blot and ELISA revealed that one-tenth of IL-12p40 detected in DC supernatants was released as the IL-12 antagonist IL-12p40 homodimer (IL-12p80). BALB/c DC released approximately 2-fold more IL-12p80 than C57BL/6 DC both in vitro and in vivo. Local injection of IL-12p80 during the first 3 days after infection resulted in increased lesion volumes for several weeks in both L. major-infected BALB/c or C57BL/6 mice, in higher lesional parasite burdens, and decreased Th1-cytokine production. Finally, IL-12p40-transgenic C57BL/6 mice characterized by overexpression of p40 showed increased levels of serum IL-12p80 and enhanced disease susceptibility. Thus, in addition to IL-1alphabeta, strain-dependent differences in the release of other DC-derived factors such as IL-12p80 may influence genetically determined disease outcome. 相似文献