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41.
Background
For the cultivation of Escherichia coli in bioreactors trace element solutions are generally designed for optimal growth under aerobic conditions. They do normally not contain selenium and nickel. Molybdenum is only contained in few of them. These elements are part of the formate hydrogen lyase (FHL) complex which is induced under anaerobic conditions. As it is generally known that oxygen limitation appears in shake flask cultures and locally in large-scale bioreactors, function of the FHL complex may influence the process behaviour. Formate has been described to accumulate in large-scale cultures and may have toxic effects on E. coli. 相似文献42.
The Wnt gene family, which encodes secreted growth and differentiation factors, has been implicated in kidney organogenesis. The Wnts control both ureteric bud development and signaling, but they also serve as inductive factors to regulate nephrogenesis in the mesenchcymal cells. Several of the Wnt genes are expressed in the developing kidney, and gene knock-out studies have revealed specific developmental functions for these. Consistent with this, changes in Wnt ligands and pathway components are associated with many kidney diseases, including kidney cancers, renal fibrosis, cystic kidney diseases, acute renal failure, diabetic nephropathy and ischaemic injury. It is these associations of the Wnt signaling system with kidney development and kidney diseases that form to topic of this review.Key words: Wnt signaling, tubule induction, ureter development, kidney diseases, kidney cancer 相似文献
43.
Hakulinen J Sankkila L Sugiyama N Lehti K Keski-Oja J 《Journal of cellular biochemistry》2008,105(5):1211-1218
Membrane type 1 matrix metalloproteinase (MT1-MMP, MMP14) is an efficient extracellular matrix (ECM) degrading enzyme that plays important roles in tissue homeostasis and cell invasion. Like a number of type I membrane proteins, MT1-MMP can be internalized from the cell surface through early and recycling endosomes to late endosomes, and recycled to the plasma membrane. Late endosomes participate in the biogenesis of small (30-100 nm) vesicles, exosomes, which redirect plasma membrane proteins for extracellular secretion. We hypothesized that some of the endosomal MT1-MMP could be directed to exosomes for extracellular release. Using cultured human fibrosarcoma (HT-1080) and melanoma (G361) cells we provide evidence that both the full-length 60 kDa and the proteolytically processed 43 kDa forms of MT1-MMP are secreted in exosomes. The isolated exosomes were identified by their vesicular structure in electron microscopy and by exosomal marker proteins CD9 and tumor susceptibility gene (TSG101). Furthermore, exosomes contained beta1-integrin (CD29). The exosomes were able to activate pro-MMP-2 and degrade type 1 collagen and gelatin, suggesting that the exosomal MT1-MMP was functionally active. The targeting of MT1-MMP in exosomes represents a novel mechanism for cancer cells to secrete membrane type metalloproteolytic activity into the extracellular space. 相似文献
44.
Jorma A Määttä Kaisa Olli Tiina Henttinen Minna T Tuittila Klaus Elenius Markku Salmivirta 《BMC cell biology》2009,10(1):5-7
Background
Nuclear localization of proteolytically formed intracellular fragment of ErbB4 receptor tyrosine kinase has been shown to promote cell survival, and nuclear localization of ErbB4 receptor has been described in human breast cancer. Tumor necrosis factor alpha converting enzyme (TACE) initiates the proteolytic cascade leading to ErbB4 intracellular domain formation. Interactions between matrix metalloproteases and heparan sulfate have been described, but the effect of cell surface heparan sulfate on TACE activity has not been previously described. 相似文献45.
Mervi Laaksonen Kaisa Murdoch Juha Siitonen Gergely Várkonyi 《Journal of Insect Conservation》2010,14(1):89-98
The beetle genus Agathidium is the largest insect group documented that principally feeds on slime moulds. Agathidium pulchellum, one of the rarest Agathidium species in Europe, is listed in the EU’s Habitats Directive. We studied the habitat associations of A. pulchellum in 44 sites located in old-growth and managed forests in eastern Finland. Agathidium pulchellum occurred exclusively on the slime-mould species Trichia decipiens. The host was associated with mid-decayed aspen, spruce and birch logs, and its incidence grew with both increasing log diameter
and stand-level log density of spruce and aspen. We also observed that even if its host was present, the beetle was absent
from sites with less than 80 aspen and spruce logs per hectare. All sites with A. pulchellum were natural forests of high conservation value. Our results show that it is possible to systematically survey the occurrence
of A. pulchellum. 相似文献
46.
47.
Suvi Vartiainen Shanjun Chen Jack George Tea Tuomela Kaisa R. Luoto Kevin M. C. O’Dell Howard T. Jacobs 《Disease models & mechanisms》2014,7(6):635-648
A point mutation in the Drosophila gene that codes for the major adult isoform of adenine nuclear translocase (ANT) represents a model for human diseases that are associated with ANT insufficiency [stress-sensitive B1 (sesB1)]. We characterized the organismal, bioenergetic and molecular phenotype of sesB1 flies then tested strategies to compensate the mutant phenotype. In addition to developmental delay and mechanical-stress-induced seizures, sesB1 flies have an impaired response to sound, defective male courtship, female sterility and curtailed lifespan. These phenotypes, excluding the latter two, are shared with the mitoribosomal protein S12 mutant, tko25t. Mitochondria from sesB1 adults showed a decreased respiratory control ratio and downregulation of cytochrome oxidase. sesB1 adults exhibited ATP depletion, lactate accumulation and changes in gene expression that were consistent with a metabolic shift towards glycolysis, characterized by activation of lactate dehydrogenase and anaplerotic pathways. Females also showed downregulation of many genes that are required for oogenesis, and their eggs, although fertilized, failed to develop to the larval stages. The sesB1 phenotypes of developmental delay and mechanical-stress-induced seizures were alleviated by an altered mitochondrial DNA background. Female sterility was substantially rescued by somatic expression of alternative oxidase (AOX) from the sea squirt Ciona intestinalis, whereas AOX did not alleviate developmental delay. Our findings illustrate the potential of different therapeutic strategies for ANT-linked diseases, based on alleviating metabolic stress.KEY WORDS: Adenine nucleotide translocase, Mitochondrial disease, Mitochondrial biogenesis, Alternative oxidase 相似文献
48.
T. R. Kaisa 《Journal of nematology》2000,32(4):403-410
Three Ektaphelenchus species with unusual spicules are redescribed. Ektaphelenchus obtusus and E. riograndensis are redescribed from newly discovered material in the collection of the USDA Forest Service RMRS. Lectotype slides are designated for both species. Ektaphelenchus obtusus is characterized by a set-off head, lips of unequal size, double rows of oocytes and spermatocytes, and a hooked spicule terminus. Ektaphelenchus riograndensis is distinguished by a rounded head with six equal lips, and spicules with a large, rounded apex, and recurved terminus. A bursa and gubernaculum are absent in both species. Ektaphelenchus scolyti is redescribed from type material deposited in the collection of Rothamsted Experimental Station. It is characterized by a well set-off head, double rows of oocytes and spermatocytes, and spicules with a hooked terminus. A bursa and gubernaculum are absent. 相似文献
49.
Kärkönen A Koutaniemi S Mustonen M Syrjänen K Brunow G Kilpeläinen I Teeri TH Simola LK 《Physiologia plantarum》2002,114(3):343-353
Activity of a number of enzymes related to lignin formation was measured in a Picea abies (L) Karsten suspension culture that is able to produce native-like lignin into the nutrient medium. This cell culture is an attractive model for studying lignin formation, as the process takes place independently of the complex macromolecular matrix of the native apoplast. Suspension culture proteins were fractionated into soluble cellular proteins, ionically and covalently bound cell wall proteins and nutrient medium proteins. The nutrient medium contained up to 5.3% of total coniferyl alcohol peroxidase (EC 1.11.1.7) activity and a significant NADH oxidase activity that is suggested to be responsible for hydrogen peroxide (H2O2) production. There also existed some malate dehydrogenase (EC 1.1.1.37) activity in the apoplast of suspension culture cells (in ionically and covalently bound cell wall protein fractions), possibly for the regeneration of NADH that is needed for peroxidase-catalysed H2O2 production. However, there is no proof of the existence of NADH in the apoplast. Nutrient medium peroxidases could be classified into acidic, slightly basic and highly basic isoenzyme groups by isoelectric focusing. Only acidic peroxidases were found in the covalently bound cell wall protein fraction. Several peroxidase isoenzymes across the whole pI range were detected in the protein fraction ionically bound to cell walls and in the soluble cellular protein fraction. One laccase-like isoenzyme with pI of approximately 8.5 was found in the nutrient medium that was able to form dehydrogenation polymer from coniferyl alcohol in the absence of H2O2. The total activity of this oxidase towards coniferyl alcohol was, however, several orders of magnitude smaller than that of peroxidases in vitro. According to 2D 1H-13C correlation NMR spectra, most of the abundant structural units of native lignin and released suspension culture lignin are present in the oxidase produced dehydrogenation polymer but in somewhat different amounts compared to peroxidase derived synthetic lignin preparations. A coniferin beta-glucosidase (EC 3.2.1.21) was observed to be secreted into the culture medium. 相似文献