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241.
M. K. Pradhan L. Nayak P. N. Joshi P. K. Mohapatra L. Patro B. Biswal U. C. Biswal 《Photosynthetica》2008,46(3):370-377
Alterations in photosynthetic capacity of primary leaves of wheat seedlings in response to ultraviolet-B (UV-B; 280–320 nm;
60 μmol m−2 s−1) exposure alone and in combination with photosynthetically active radiation (PAR; 400–800 nm; 200 μmol m−2 s−1) during different phases of leaf growth and development were assessed. UV-B exposure resulted in a phase-dependent differential
loss in photosynthetic pigments, photochemical potential, photosystem 2 (PS2) quantum yield, and in vivo O2 evolution. UV-B exposure induced maximum damage to the photosynthetic apparatus during senescence phase of development. The
damages were partially alleviated when UV-B exposure was accompanied by PAR. UV-B induced an enhancement in accumulation of
flavonoids during all phases of development while it caused a decline in anthocyanin content during senescence. The differential
changes in these parameters demonstrated the adaptation ability of leaves to UV-B stress during all phases of development
and the ability was modified in UV-B+ PAR exposed samples. 相似文献
242.
Nakazawa H Okada K Kobayashi R Kubota T Onodera T Ochiai N Omata N Ogasawara W Okada H Morikawa Y 《Applied microbiology and biotechnology》2008,81(4):681-689
The genes encoding the catalytic domains (CD) of the three endoglucanases (EG I; Cel7B, EG II; Cel5A, and EG III; Cel12A)
from Trichoderma reesei QM9414 were expressed in Escherichia coli strains Rosetta-gami B (DE3) pLacI or Origami B (DE3) pLacI and were found to produce functional intracellular proteins.
Protein production by the three endoglucanase transformants was evaluated as a function of growth temperature. Maximal productivity
of EG I-CD at 15°C, EG II-CD at 20°C and EG III at 37°C resulted in yields of 6.9, 72, and 50 mg/l, respectively. The endoglucanases
were purified using a simple purification method based on removing E. coli proteins by isoelectric point precipitation. Specific activity toward carboxymethyl cellulose was found to be 65, 49, and
15 U/mg for EG I-CD, EG II-CD, and EG III, respectively. EG II-CD was able to cleave 1,3–1,4-β-d-glucan and soluble cellulose derivatives. EG III was found to be active against cellulose, 1,3–1,4-β-d-glucan and xyloglucan, while EG I-CD was active against cellulose, 1,3–1,4-β-d-glucan, xyloglucan, xylan, and mannan. 相似文献
243.
S Silver 《Journal of industrial microbiology & biotechnology》1998,20(1):1-12
Bacterial chromosomes have genes for transport proteins for inorganic nutrient cations and oxyanions, such as NH4
+, K+, Mg2+, Co2+, Fe3+, Mn2+, Zn2+ and other trace cations, PO4
3-, SO4
2- and less abundant oxyanions. Together these account for perhaps a few hundred genes in many bacteria. Bacterial plasmids
encode resistance systems for toxic metal and metalloid ions including Ag+ AsO2
-, AsO4
3-, Cd2+, Co2+, CrO4
2−, Cu2+, Hg2+, Ni2+, Pb2+, TeO3
2−, TI+ and Zn2+. Most resistance systems function by energy-dependent efflux of toxic ions. A few involve enzymatic (mostly redox) transformations.
Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. The Cd2+-resistance cation pump of Gram-positive bacteria is membrane P-type ATPase, which has been labeled with 32P from [γ-32P]ATP and drives ATP-dependent Cd2+ (and Zn2+) transport by membrane vesicles. The genes defective in the human hereditary diseases of copper metabolism, Menkes syndrome
and Wilson’s disease, encode P-type ATPases that are similar to bacterial cadmium ATPases. The arsenic resistance system transports
arsenite [As(III)], alternatively with the ArsB polypeptide functioning as a chemiosmotic efflux transporter or with two polypeptides,
ArsB and ArsA, functioning as an ATPase. The third protein of the arsenic resistance system is an enzyme that reduces intracellular
arsenate [As(V)] to arsenite [As(III)], the substrate of the efflux system. In Gram-negative cells, a three polypeptide complex
functions as a chemiosmotic cation/protein exchanger to efflux Cd2+, Zn2+ and Co2+. This pump consists of an inner membrane (CzcA), an outer membrane (CzcC) and a membrane-spanning (CzcB) protein that function
together.
Received 08 August 1997/ Accepted in revised form 01 November 1997 相似文献
244.
Yoonjung Kho∗ Sungchan Kim∗ Byung Sun Yoon∗ Jai-Hee Moon Sungwook Kwak Gyuman Park 《Animal biotechnology》2013,24(2):89-103
In this study, we show that expression of the Westmead DMBA8 nonmetastatic cDNA 1 (WDNM1) gene was increased upon SFM and/or TNFα treatment, with a corresponding increase in apoptotic cells, and gradually decreased following re-stimulation with serum in HC11 mammary epithelial cells. TNFα induced WDNM1 expression showed the NFκB-dependent mechanism since it's expression was abrogated in IκBαM (super-repressor of NFκB)-transfected cells, but not those transfected with control vector. Furthermore, overexpression of WDNM1 suppressed growth and differentiation, and accelerated apoptosis of HC11 cells. Thus, our results demonstrate that WDNM1 gene expression, regulated by the TNFα-NFκB signal pathway, is associated with HC11 cell apoptosis. 相似文献
245.
Jens Christian Brasen Lars Folke OlsenMaurice B. Hallett 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2011,1813(8):1446-1452
In order to establish whether non-mitochondrial oxidase activity in human neutrophils is tightly related to cytosolic Ca2+ concentration, we simultaneously measured Ca2+ oscillations induced by ATP and oxidant production in single adherent neutrophils using confocal microscopy. ATP induced fast damped Ca2+ spikes with a period of 15 s and slower irregular spikes with a period greater than 50 s. Spikes in Ca2+ occurred in the absence of Ca2+ influx, but the amplitude was damped by inhibition of Ca2+ influx. Using the oxidation of hydroethidine as a cytosolic marker of oxidant production, we show that the generation of reactive oxygen species by neutrophils adherent to glass was accelerated by ATP. The step-up in NADPH oxidase activity followed the first elevation of cytosolic Ca2+ but, despite subsequent spikes in Ca2+ concentration, no oscillations in oxidase activity could be detected. ATP induced spikes in Ca2+ in a very reproducible way and we propose that the Ca2+ signal is an on-switch for oxidase activity, but the activity is apparently not directly correlated with spiking activity in cytosolic Ca2+. 相似文献
246.
Elham Safaei Masoume Mohseni Kabir Zvonko Jagli?i? Yong-Ill Lee 《Inorganica chimica acta》2011,366(1):275-282
A series of novel copper(II) complexes, L2Cu with newly synthesized 3,5--salicylaldimine (or 5--salicylaldimine) ligands derived from 2,4-di-tert-butyl phenol (or 4-tert-butyl phenol) and alkyl (aryl) amines have been prepared and their spectroscopic (IR, UV-Vis, ESI-MS), X-ray, magnetic and redox properties have been investigated. The X-ray crystallography analysis shows that all complexes are monomeric and their copper(II) centers are surrounded by phenolate oxygens and imine nitrogen atoms. Therefore, the coordination sphere around the copper atoms is N2O2 as seen in galactose oxidase active site. In addition, the geometric configurations of all complexes are square planar or slightly distorted square planar. The crystal system for all complexes is monoclinic, except for which is orthorhombic. The temperature dependence of magnetic susceptibility of complexes confirms the mononuclear structure of complexes. Oxidation of the Cu(II) complexes yielded the corresponding Cu(II)-phenoxyl radical species during the cyclic voltammetry experiments. 相似文献
247.
248.
Yuichi Takashi Shun Sawatsubashi Itsuro Endo Yukiyo Ohnishi Masahiro Abe Munehide Matsuhisa Daiji Kawanami Toshio Matsumoto Seiji Fukumoto 《Biochemistry and Biophysics Reports》2021
Fibroblast growth factor (FGF) 23 produced by the bone is the principal hormone to regulate serum phosphate level. Serum FGF23 needs to be tightly regulated to maintain serum phosphate in a narrow range. Thus, we hypothesized that the bone has some phosphate-sensing mechanism to regulate the production of FGF23. Previously we showed that extracellular phosphate induces the phosphorylation of FGF receptor 1 (FGFR1) and FGFR1 signaling regulates the expression of Galnt3, whose product works to increase FGF23 production in vitro. In this study, we show the significance of FGFR1 in the regulated FGF23 production and serum phosphate level in vivo. We generated late-osteoblast/osteocyte-specific Fgfr1-knockout mice (Fgfr1fl/fl; OcnCre/+) by crossing the Ocn-Cre and the floxed Fgfr1 mouse lines. We evaluated serum phosphate and FGF23 levels, the expression of Galnt3 in the bone, the body weight and life span. A selective ablation of Fgfr1 aborted the increase of serum active full-length FGF23 and the enhanced expression of Galnt3 in the bone by a high phosphate diet. These mice showed more pronounced hyperphosphatemia compared with control mice. In addition, these mice fed with a control diet showed body weight loss after 23 weeks of age and shorter life span. These results reveal a novel significance of FGFR1 signaling in the phosphate metabolism and normal life span. 相似文献
249.
Xiumei Tao 《Critical reviews in biotechnology》2019,39(2):249-257
2-O-α-d-glucopyranosyl-l-ascorbic acid (AA-2G) is one of the most important l-ascorbic acid derivatives because of its resistance to reduction and oxidation and its easy degradation by α-glucosidase to release l-ascorbic acid and glucose. Thus, AA-2G has commercial uses in food, medicines and cosmetics. This article presents a review of recent studies on the enzymatic production of AA-2G using cyclodextrin glycosyltransferase. Reaction mechanisms with different donor substrates are discussed. Protein engineering, physical and biological studies of cyclodextrin glycosyltransferase are introduced from the viewpoint of effective AA-2G production. Future prospects for the production of AA-2G using cyclodextrin glycosyltransferase are reviewed. 相似文献
250.