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981.
We investigated the effect of magnesium supplementation on zinc distribution in rats given excess calcium as carbonate. Rats
were given a control diet (5 g/kg calcium and 0.5 g/kg magnesium), a high calcium diet (HC, 25 g/kg calcium and 0.5 g/kg magnesium)
or the high calcium diet supplied with magnesium (HCM, 25 g/kg calcium and 2.5 g/kg magnesium) for 4 weeks. Calcium carbonate
and magnesium oxide were used for increasing these mineral concentrations in diets. Although feed intake did not differ among
the groups, the excess calcium suppressed feed efficiency, irrespective of dietary magnesium concentration. Femoral magnesium
concentration was lower in the HC group than in the control and the HCM groups. Femoral zinc concentration was higher in the
HC group and the HCM group than in the control group. The zinc concentration in the kidney was lower in the HC group and the
HCM group than in the control group. The excess calcium did not affect zinc concentration in plasma and other tissues such
as the liver, testis, and spleen, irrespective of dietary magnesium. These results suggest that the increasing bone zinc and
the decreasing renal zinc do not result from magnesium insufficiency in rats given excess calcium as carbonate. 相似文献
982.
An H+ ATPase at the plasma-membrane of guard cells is thought to establish an electrochemical gradient that drives K+ and Cl– uptake, resulting in osmotic swelling of the guard cells and stomatal opening. There are, however, conflicting results regarding the effectiveness of the plasma-membrane H+-ATPase inhibitor, vanadate, in inhibiting both H+ extrusion from guard cells and stomatal opening. We found that 1 mM vanadate inhibited light-stimulated stomatal opening in epidermal peels of Commelina communis L. only at KCl concentrations lower than 50 mM. When impermeant n-methylglucamine and HCl (pH 7.2) were substituted for KCl, vanadate inhibition was still not observed at total salt concentrations50 mM. In contrast, in the absence of Cl–, when V2O5 was used to buffer KOH, vanadate inhibition of stomatal opening occurred at K+ concentrations as high as 70 mM. Partial vanadate inhibition was observed in the presence of the impermeant anion, iminodiacetic acid (100 mM KHN(CH2CO2H)2). These results indicate that high concentrations of permeant anions prevent vanadate uptake and consequently prevent its inhibitory effect. In support of this hypothesis, an inhibitor of anion uptake, anthracene-9-carboxylic acid, partially prevented vanadate inhibition of stomatal opening. Other anion-uptake inhibitors (1 mM 4,4-diisothiocyanatostilbene-2,2-disulfonic acid, 1 mM 4-acetamido-4-isothiocyanostilbene-2,2-disulfonic acid, 200 M Zn2+) were not effective. Decreased vanadate inhibition at high Cl–/vanadate ratios may result from competition between vanadate and Cl– for uptake. Unlike metabolic inhibitors, vanadate did not affect the extent of stomatal closure stimulated by darkness, further indicating that the observed action of vanadate represents a specific inhibition of the guard-cell H+ ATPase.Abbreviations DIDS
4,4-diisothiocyanatostilbene-2,2-disulfonic acid
- FC
fusicoccin
- SITS
4-acetamido-4-isothiocyanostilbene-2,2-disulfonic acid
We thank Drs. R.T. Leonard (University of California, Riverside, USA) and K.A, Rubinson (Yellow Springs, Oh., USA) for helpful comments on the research, Janet Sherwood (Harvard University) for excellent plant care, and Angela Ciamarra, Anne Gershenson, Gustavo Lara (Harvard University) and Orit Tal (Hebrew University) for valuable technical assistance. This research was supported by a grant from the National Science Foundation (DCB-8904041) to S.M.A. 相似文献
983.
Siroj Jitprasutwit Wisansanee Thaewpia Veerachat Muangsombut Aroonlug Lulitanond Chanvit Leelayuwat Ganjana Lertmemongkolchai Sunee Korbsrisate 《Journal of microbiology (Seoul, Korea)》2010,48(4):526-532
Burkholderia thailandensis is a close relative of Burkholderia pseudomallei. These organisms are very similar, but B. thailandensis is far less virulent than B. pseudomallei. Nucleotide sequencing and analysis of 14 B. thailandensis isolates revealed variation in the regions coding for the type III secreted BipD protein. The degree of B. thailandensis BipD sequence variation was greater than that found in B. pseudomallei. Western blot analysis indicated that, unlike B. pseudomallei, B. thailandensis type III secreted proteins including BipD and BopE could not be detected in the supernatant of culture medium unless induced
by acidic conditions. In addition, culturing B. thailandensis under acidic growth conditions (pH 4.5) can induce the ability of this bacterium to invade human respiratory epithelial cells
A549. The identification of an environmental stimulus that increases the invasion capability of B. thailandensis invasion is of value for those who would like to use this bacterium as a model to study B. pseudomallei virulence. 相似文献
984.
Rosanne A. Healy Hannah Zurier Gregory Bonito Matthew E. Smith Donald H. Pfister 《Mycorrhiza》2016,26(7):781-792
During a study comparing the ectomycorrhizal root communities in a native forest with those at the Arnold Arboretum in Massachusetts (USA), the European species Tuber borchii was detected on the roots of a native red oak in the arboretum over two successive years. Since T. borchii is an economically important edible truffle native to Europe, we conducted a search of other roots in the arboretum to determine the extent of colonization. We also wanted to determine whether other non-native Tuber species had been inadvertently introduced into this 140-year-old Arboretum because many trees were imported into the site with intact soil and roots prior to the 1921 USDA ban on these horticultural practices in the USA. While T. borchii was not found on other trees, seven other native and exotic Tuber species were detected. Among the North American Tuber species detected from ectomycorrhizae, we also collected ascomata of a previously unknown species described here as Tuber arnoldianum. This new species was found colonizing both native and non-native tree roots. Other ectomycorrhizal taxa that were detected included basidiomycetes in the genera Amanita, Russula, Tomentella, and ascomycetes belonging to Pachyphlodes, Helvella, Genea, and Trichophaea. We clarify the phylogenetic relationships of each of the Tuber species detected in this study, and we discuss their distribution on both native and non-native host trees. 相似文献
985.
Germano Siqueira Adriane MF Milagres Walter Carvalho Gerald Koch André Ferraz 《Biotechnology for biofuels》2011,4(1):7
Background
Lignin and hemicelluloses are the major components limiting enzyme infiltration into cell walls. Determination of the topochemical distribution of lignin and aromatics in sugar cane might provide important data on the recalcitrance of specific cells. We used cellular ultraviolet (UV) microspectrophotometry (UMSP) to topochemically detect lignin and hydroxycinnamic acids in individual fiber, vessel and parenchyma cell walls of untreated and chlorite-treated sugar cane. Internodes, presenting typical vascular bundles and sucrose-storing parenchyma cells, were divided into rind and pith fractions. 相似文献986.
Liangming Chen Zhigang Zhao Xi Liu Linglong Liu Ling Jiang Shijia Liu Wenwei Zhang Yihua Wang Yuqiang Liu Jianmin Wan 《Molecular breeding : new strategies in plant improvement》2011,27(2):247-258
The incomplete fertility of japonica × indica rice hybrids has inhibited breeders’ access to the substantial heterotic potential of these hybrids. As hybrid sterility
is caused by an allelic interaction at a small number of loci, it is possible to overcome it by simple introgression at the
major sterility loci. Here we report the use of marker-assisted backcrossing to transfer into the elite japonica cv. Zhendao88 a photoperiod-sensitive male sterility gene from cv. Lunhui422S (indica) and the yellow leaf gene from line Yellow249 (indica). The microsatellite markers RM276, RM455, RM141 and RM185 were used to tag the fertility genes S5, S8, S7 and S9, respectively. Line 509S is a true-breeding photoperiod-sensitive male sterile plant, which morphologically closely resembles
the japonica type. Genotypic analysis showed that the genome of line 509S comprises about 92% japonica DNA. Nevertheless, hybrids between line 509S and japonica varieties suffer from a level of hybrid sterility, although the line is highly cross-compatible with indica types, with the resulting hybrids expressing a significant degree of heterosis. Together, these results suggest that segment
substitution on fertility loci based on known information and marker-assisted selection are an effective approach for utilizing
the heterosis of rice inter-subspecies. 相似文献
987.
Synthesis of Cell Coat in Normal and Transformed Cells 总被引:6,自引:0,他引:6
THE surface of transformed cells has been a focus of considerable attention recently because some of the properties which distinguish these cells from their precursors, such as decreased cell adhesiveness, altered cell orientation and loss of contact and density dependent inhibition1–3, may relate to changes on their surface. A common feature of vertebrate cells is the cell coat, a glycoprotein structure surrounding the plasma membrane4. Electron microscopy has revealed that transformed cells have a thicker coat than normal cells5 and we have now found that coat synthesis in cells transformed by an oncogenic DNA virus and in cells transformed by a chemical carcinogen occurs faster than in normal controls whereas only in the virus-transformed cells is the coat significantly thicker. 相似文献
988.
Alien chromosome addition lines have been widely used for identifying gene linkage groups, assigning species-specific characters
to a particular chromosome and comparing gene synteny between related species. In plant breeding, their utilization lies in
introgressing characters of agronomic value. The present investigation reports the production of intergeneric somatic hybrids
Brassica
napus (2n = 38) + Orychophragmus violaceus (2n = 24) through asymmetric fusions of mesophyll protoplasts and subsequent development of B. napus-O. violaceous chromosome addition lines. Somatic hybrids showed variations in morphology and fertility and were mixoploids (2n = 51–67) with a range of 19–28 O. violaceus chromosomes identified by genomic in situ hybridization (GISH). After pollinated with B. napus parent and following embryo rescue, 20 BC1 plants were obtained from one hybrid. These exhibited typical serrated leaves of O. violaceus or B. napus-type leaves. All BC1 plants were partially male fertile but female sterile because of abnormal ovules. These were mixoploids (2n = 41–54) with 9–16 chromosomes from O. violaceus. BC2 plants showed segregations for female fertility, leaf shape and still some chromosome variation (2n = 39–43) with 2–5 O. violaceus chromosomes, but mainly containing the whole complement from B. napus. Among the selfed progenies of BC2 plants, monosomic addition lines (2n = 39, AACC + 1O) with or without the serrated leaves of O. violaceus or female sterility were established. The complete set of additions is expected from this investigation. In addition, O. violaceus plants at diploid and tetraploid levels with some variations in morphology and chromosome numbers were regenerated from the
pretreated protoplasts by iodoacetate and UV-irradiation.
Z. Zhao and T. Hu make equal contributions to this work. 相似文献
989.
Wen Wang Yan Zhao Shujuan Yao Xiujuan Cui Wenying Pan Wenqian Huang Jiangang Gao Taotao Dong Shiqian Zhang 《Biochemistry. Biokhimii?a》2017,82(8):933-941
Epithelial ovarian cancer (EOC) has the highest mortality among various types of gynecological malignancies. Most patients die of metastasis and recurrence due to cisplatin resistance. Thus, it is urgent to develop novel therapies to cure this disease. CCK-8 assay showed that nigericin exhibited strong cytotoxicity on A2780 and SKOV3 cell lines. Flow cytometry indicated that nigericin could induce cell cycle arrest at G0/G1 phase and promote cell apoptosis. Boyden chamber assay revealed that nigericin could inhibit migration and invasion in a dose-dependent manner by suppressing epithelial–mesenchymal transition (EMT) in EOC cells. These effects were mediated, at least partly, by the Wnt/β-catenin signaling pathway. Our results demonstrated that nigericin could inhibit EMT during cell invasion and metastasis through the canonical Wnt/β-catenin signaling pathway. Nigericin may prove to be a novel therapeutic strategy that is effective in patients with metastatic EOC. 相似文献
990.
Telomerase expression strongly correlates with the grade of malignancy in glioma with inhibition illustrating a definite increase
in chemosensitivity. This study was designed to investigate the effects of a green tea derivative, epigallocatechin-3-gallate
(EGCG); together with either cisplatin or tamoxifen in glioma, and to investigate whether these effects are mediated through
telomerase suppression. EGCG showed a significant cytotoxic effect on 1321N1 cells after 24 h and on U87-MG cells after 72 h
(P < 0.001) without significantly affecting the normal astrocytes. Treatment with EGCG inhibited telomerase expression significantly
(P < 0.01) and enhanced the effect of cisplatin and tamoxifen in both 1321N1 (P < 0.01) and U87-MG (P < 0.001) cells. EGCG, as a natural product has enormous potential to be an anti-cancer agent capable of enhancing tumour
cell sensitivity to therapy. 相似文献