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31.
Norma L. Pucheu Norma L. Kerber Emilio A. Rivas Néstor Cortez Augusto F. Garcia 《Current microbiology》1997,34(3):155-161
Membranes from in vivo labeled cells of Rhodobacter
capsulatus U43[pTX35] grown photosynthetically carried 60% of
the [32P]-Pi in the “heavy” fraction (HM) after
sucrose gradient sedimentation. Metal-chelating chromatography of either
“heavy” or “light” (LM) membrane fractions rendered
similar Bchl-protein complex profiles after octyl-glucoside treatment,
including most of the radioactivity in the same corresponding elution
fraction (F II). Similar labeling distribution of pigment-protein complexes
was obtained for membranes of dark-grown cells induced by lowering oxygen
tension. Fractions derived from HM showed highly labeled LHIα, whereas the
same complex from LM was essentially [32P]-Pi-free, as revealed
by SDS-PAGE followed by autoradiography. Phospholipid analysis showed a
similar pattern for membranes isolated from cells photosynthetically or
semiaerobically grown, being the most abundant: phosphatidylglycerol,
phosphatidylethanolamine, cardiolipin, and phosphatidylcholine. Part of the
phospholipids from HM comigrated with LHIα during SDS-PAGE and dissociated
from the complexes only after solvent extraction and hydrophobic
chromatography. However, a small amount remained always attached to LHIα,
indicating an unusual strong interaction. These results suggest the existence
of two operationally defined membrane regions carrying LHIα complexes
differing in phosphorylation status and protein-phospholipid interaction.
Received: 10 August 1996 / Accepted: 10 September 1996 相似文献
32.
Liu Yewei; Kranias Evangelia G.; Schneider Martin F. 《American journal of physiology. Cell physiology》1997,273(6):C1915
The effects ofphosphorylation status on Ca2+release and Ca2+ removal werestudied in fast-twitch flexor digitorum brevis and slow-twitch soleusskeletal muscle fibers enzymatically isolated from wild-type andphospholamban knockout (PLBko) mice. In all fibers the adenosine3',5'-cyclic monophosphate-dependent protein kinase (PKA)inhibitor H-89 decreased the peak amplitude of the intracellularCa2+ concentration([Ca2+]) transient fora single action potential, and the PKA activator dibutyryl adenosine3',5'-cyclic monophosphate (DBcAMP) reversed this effect,indicating modulation of Ca2+release by phosphorylation status in all fibers. H-89 decreased thedecay rate constant of the[Ca2+] transient andDBcAMP reversed this effect only in phospholamban-expressing fibers(wild-type soleus), indicating modulation ofCa2+ removal only in the presenceof phospholamban. A high basal level of PKA phosphorylation in soleusfibers maintained under our control conditions was indicated bythe lack of effect of direct application of DBcAMP onCa2+ release orCa2+ removal in wild-type or PLBkosoleus fibers and was confirmed by analysis of phospholamban fromwild-type soleus fibers. 相似文献
33.
J.-Y. Roh H.-W. Park Y.-H. Je D.-W. Lee B.-R. Jin H.-W. Oh S. S. Gill & S.-K. Kang 《Letters in applied microbiology》1997,24(6):451-454
Bacillus thuringiensis NTB-1 isolated from soil samples in Korea produces ovoidal parasporal inclusions with proteins of approximately 24–40 kDa in size. Although serological study indicated that the isolate has a flagella (H) antigen identical with subsp. israelensis , it seemed to be non-insecticidal against Lepidoptera and Coleoptera as well as Diptera. To investigate the activity of non-insecticidal B. thuringiensis transformed with insecticidal crystal protein genes, cryIVD and cytA genes of B. thuringiensis subsp. morrisoni PG-14, highly toxic to mosquito larvae, were introduced into the isolate NTB-1. The expression of mosquitocidal crystal protein genes in NTB-1 was characterized by SDS–PAGE analysis and electron microscopy. The results showed that crystalline inclusions of host, CryIVD and CytA were stably expressed in the transformant. However, the mosquitocidal activity of transformant was similar to that of B. thuringiensis subsp. kurstaki Cry− B harbouring cryIVD and cytA genes, demonstrating that a synergistic effect by an interaction of both introduced insecticidal and resident non-insecticidal crystal proteins was not observed. 相似文献
34.
Spectrophotometric quantification of lactic bacteria in alginate and control of cell release with chitosan coating 总被引:3,自引:0,他引:3
Y. Zhou E. Martins A. Groboillot C. P. Champagne & R. J. Neufeld 《Journal of applied microbiology》1998,84(3):342-348
Lactococcus lactis ssp. cremoris was entrapped within a Ca-alginate matrix, and an in situ spectrophotometric method for monitoring cell population in calcium alginate beads described. The intracapsular cell population can be estimated by measuring the optical density of beads containing cells, using cell-free beads as reference, or by measuring absorbance of a liquified bead suspension. Alginate beads, and beads coated with chitosan type I, II, and I and II mixtures, were examined for cell release. Lower viscosity chitosan (type I) coatings reduced cell release by a factor of 100 from105 cfu ml−1 to 103 cfu ml−1 after 6 h of fermentation. Reuse of chitosan I coated alginate beads also showed a reduction in cell release by a factor of 100. Cell loading and initial cell growth within the beads greatly affected cell release. Reducing the initial cell release would lower the overall levels of cell release throughout the fermentation. Compared to non-immobilized cultures, a 20–40% reduction in the lactic acid production rate was observed for alginate beads and chitosan I coated alginate beads, respectively. This reduction can be compensated for by increasing the intracapsular cell loading during immobilization, or before the onset of fermentation. 相似文献
35.
S Chwetzoff S Tsunasawa F Sakiyama A Ménez 《The Journal of biological chemistry》1989,264(22):13289-13297
The venoms of the Naja species are known to be cytotoxic. This toxicity has been attributed to the presence of small nonenzymatic polypeptides of 60 amino acid residues, designated as cardiotoxins or cytotoxins. We investigated the cytotoxic potency of Naja nigricollis venom fractions and isolated another type of cytotoxic component which is even more potent than cardiotoxins. This cytotoxic compound, which was designated as nigexine, was purified to homogeneity and its amino acid sequence was determined. Nigexine is a basic phospholipase A2 consisting of a single chain of 118 amino acids. A detailed investigation of the cytotoxic effects on epithelial FL cells, C-13T neuroblastoma cells, and promyelocytic leukemia HL 60 cells revealed that nigexine not only altered cell viability but also prevented cell proliferation. This is a property that was specific to nigexine since other phospholipases A2 from various sources had no detectable cytotoxic activity. The cytotoxic activity of nigexine was not dependent on the presence of divalent cations, unlike its enzymatic activity. In particular, the cytotoxic activity of nigexine was identical in the presence or absence of either 2 mM Ca2+ or Sr2+, or 6 mM EDTA. We also present evidence based on chemical modifications that cytotoxic activity was not correlated with enzymatic activity. Thus, modification with parabromophenacyl bromide totally abolished the enzymatic activity of nigexine, which nevertheless retained 6-20% of the cytotoxicity of native nigexine. Conversely, treatment with cyanogen bromide gave a compound that retained 7% of the enzymatic activity of the parent molecule but was devoid of detectable cytotoxicity. 相似文献
36.
The ability of bovine intermediate lobe secretory vesicle membrane-associated enzyme(s) and purified, soluble paired basic residue-specific, pro-opiomelanocortin converting enzyme (Loh, Y.P., Parish, D. C., and Tuteja, R. (1985) J. Biol. Chem. 260, 7194-7205) to cleave bovine NH2-terminal pro-opiomelanocortin1-77 (N-POMC 1-77) was investigated. Purified pro-opiomelanocortin converting enzyme and an enzyme activity associated with the secretory vesicle membrane were shown to cleave bovine N-POMC1-77 to two major products: N-POMC1-49 and Lys-gamma 3-melanotropin (MSH), and one minor product, gamma 3-MSH. These products were identified by their retention times on high performance liquid chromatography, immunological characteristics, and for Lys-gamma 3-MSH, amino acid composition. The products generated indicate cleavage preferentially between Arg 49-Lys 50 of bN-POMC1-77 (where b indicates bovine), which is identical to the processing pattern found in the bovine intermediate lobe in situ. The membrane converting activity was shown to be stimulated by 5 mM Ca2+ and has a pH optimum of 4-5 and an inhibitor profile characteristic of an aspartic protease. This suggests that the membrane-associated enzyme involved is very similar or identical to the purified, soluble pro-opiomelanocortin converting enzyme, which has previously been reported to be an acidic, aspartic protease responsible for the initial steps of POMC processing. The results of this study lead to the proposal that the lack of processing of the Arg49-Lys50 site in POMC in the anterior lobe versus the intermediate lobe of the pituitary in vivo may be due to other regulatory mechanisms rather than invoking the existence in the intermediate lobe of another enzyme specific for this site, different from pro-opiomelanocortin converting enzyme. 相似文献
37.
Yixin Zheng Xuejie Fu Qingbai Liu Shengqi Guan Cunchang Liu Chunmei Xiu Tingting Gong Hongting Jin Saijilafu Zunyi Zhang Di Chen Jianquan Chen 《Journal of cellular physiology》2019,234(9):14422-14431
Cre/loxP technology is an important tool for studying cell type-specific gene functions. Cre recombinase mouse lines, including Agc1-CreERT2, Col2a1-Cre; Col2a1-CreERT2, Shh-Cre, Shh-CreERT2, and Osx-Cre, have been proven to be valuable tools to elucidate the biology of long bones, yet the information for their activity in postnatal intervertebral disc (IVD) tissues was very limited. In this study, we used R26-mTmG fluorescent reporter to systematically analyze cell specificity and targeting efficiency of these six mouse lines in IVD tissues at postnatal growing and adult stages. We found that Agc1-CreERT2 is effective to direct recombination in all components of IVDs, including annulus fibrosus (AF), nucleus pulposus (NP), and cartilaginous endplate (CEP), upon tamoxifen induction at either 2 weeks or 2 months of ages. Moreover, Col2a1-Cre targets most of the cells in IVDs, except for some cells in the outer AF (OAF) and NP. In contrast, the activity of Col2a1-CreERT2 is mainly limited to the IAF of IVD tissues at either stage of tamoxifen injection. Similarly, Shh-Cre directs recombination specifically in all NP cells, whereas Shh-CreERT2 is active only in a few NP cells when tamoxifen is administered at either stage. Finally, Osx-Cre targets cells in the CEP, but not in the NP or AF of IVDs tissues at these two stages. Thus, our data demonstrated that all these Cre lines can direct recombination in IVD tissues at postnatal stages with different cell type specificity and/or targeting efficiency, and can, therefore, serve as valuable tools to dissect cell type-specific gene functions in IVD development and homeostasis. 相似文献
38.
Y.-M. D. 《Option/Bio》2018,29(573-574):14
39.
Xiaodong Liu Rui Liu Yongheng Bai Heya Jiang Xinxin Fu Shumei Ma 《Cell biochemistry and function》2020,38(3):283-289
Based on central dogma of genetics, protein is the embodiment and executor of genetic function, post-translational modifications (PTMs) of protein are particularly important and involved in almost all aspects of cell biology and pathogenesis. Studies have shown that ionizing radiation (IR) alters gene expression much more profoundly and a broad variety of cell-process pathways, lots of proteins are modified and activated. Our understanding of the protein in response to ionizing radiation is steadily increasing. Among the various biological processes known to induce radioresistance, PTMs have attracted marked attention in recent years. The present review summarizes the latest knowledge about how PTMs response to ionizing radiation and pathway analysis were conducted. The data provided insights into biological effects of IR and contributing to the development of novel IR-based strategies. 相似文献
40.
Angelica Mendoza Beltran Brian Cox Chris Mutel Detlef P. van Vuuren David Font Vivanco Sebastiaan Deetman Oreane Y. Edelenbosch Jeroen Guinée Arnold Tukker 《Journal of Industrial Ecology》2020,24(1):64-79
Prospective life cycle assessment (LCA) needs to deal with the large epistemological uncertainty about the future to support more robust future environmental impact assessments of technologies. This study proposes a novel approach that systematically changes the background processes in a prospective LCA based on scenarios of an integrated assessment model (IAM), the IMAGE model. Consistent worldwide scenarios from IMAGE are evaluated in the life cycle inventory using ecoinvent v3.3. To test the approach, only the electricity sector was changed in a prospective LCA of an internal combustion engine vehicle (ICEV) and an electric vehicle (EV) using six baseline and mitigation climate scenarios until 2050. This case study shows that changes in the electricity background can be very important for the environmental impacts of EV. Also, the approach demonstrates that the relative environmental performance of EV and ICEV over time is more complex and multifaceted than previously assumed. Uncertainty due to future developments manifests in different impacts depending on the product (EV or ICEV), the impact category, and the scenario and year considered. More robust prospective LCAs can be achieved, particularly for emerging technologies, by expanding this approach to other economic sectors beyond electricity background changes and mobility applications as well as by including uncertainty and changes in foreground parameters. A more systematic and structured composition of future inventory databases driven by IAM scenarios helps to acknowledge epistemological uncertainty and to increase the temporal consistency of foreground and background systems in LCAs of emerging technologies. 相似文献