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排序方式: 共有157条查询结果,搜索用时 15 毫秒
111.
112.
Guadalupe De la Rosa Alejandro Martínez-Martínez Helvia Pelayo José R Peralta-Videa Blanca Sanchez-Salcido Jorge L Gardea-Torresdey 《Plant Physiology and Biochemistry》2005,43(5):491-498
Tumbleweed (Salsola kali) is a desert plant species that has shown to be a potential Cd hyperaccumulator. In this study, the production of low-molecular weight thiols (LMWT) as a response to cadmium stress was determined in hydroponically grown seedlings exposed to 0, 45, 89, and 178 microM Cd(2+). The treatment of 89 microM Cd(2+) was tested alone and supplemented with an equimolar concentration of ethylenediaminetetraacetic acid (EDTA) to determine the effect of this chelating agent on Cd uptake and thiols production. After 6 days of growth, the Cd concentration in plant tissues was determined by using inductively coupled plasma/optical emission spectroscopy (ICP/OES). Results indicated that Cd uptake by plants was concentration-dependent. Plants treated with 178 microM Cd(2+), had 10+/-0.62, 9.7+/-1.4, and 4.3+/-0.83 mmol Cd kg(-1) dry tissue in roots, stems, and leaves, respectively. The production of thiols was dependent on Cd concentration in tissues. According to the stoichiometry performed, plants treated with Cd concentrations up to 178 muM produced 0.131+/-0.02, and 0.087+/-0.012 mmol SH per mmol Cd present in roots and stems. In leaves, the production of thiols decreased at the highest Cd concentration tested. Thus, up to 89 microM Cd in the media, 0.528+/-0.004 mmol SH per mmol Cd in leaf tissues were produced. EDTA equimolar to Cd reduced both Cd uptake and thiols production. Catalase activity (CAT) (EC 1.11.1.6) was significantly depressed at the lowest Cd concentration. None of the conditions tested affected biomass or plant elongation. 相似文献
113.
H Castillo-Michel J G Parsons J R Peralta-Videa A Martínez-Martínez K M Dokken J L Gardea-Torresdey 《Plant Physiology and Biochemistry》2007,45(6-7):457-463
Arsenite (As(III)) and arsenate (As(V)) uptake by peas was investigated using inductively coupled plasma/optical emission spectroscopy (ICP-OES) at pH below 4 and at pH 5.8. Additionally, total amylolitic activity and alpha-amylase (1,4-alpha-d-glucan glucanohydrolase; EC 3.2.1.1) activity was assayed in plants exposed to arsenic treatments. At pH below 4, the uptake for As(III) and As(V) in roots was 137 and 124 mg As kg(-1) dry weight (d wt), respectively. Translocation of arsenic to the aerial part was relatively low ( approximately 5mg As kg(-1) d wt). The uptake for As(III) and As(V) in roots at pH 5.8 was about 43 and 30 mg As kg(-1) d wt, respectively, and translocation of As to the aerial part was not detectable. None of the arsenic treatments affected the total amylolitic activity in roots; however, the shoots from all treatments showed an increase in the total amylolitic activity. Alpha-amylase activity in the pea leaves was not significantly affected by arsenic treatments. X-ray absorption spectroscopy (XAS) studies showed a reduction of As(V) to As(III) in the roots. From linear combination X-ray absorption near edge structure (LC-XANES) fittings, it was determined that arsenic was present as a mixture of As(III) oxide and sulfide in pea roots. 相似文献
114.
RNA polymerase II primes Polycomb‐repressed developmental genes throughout terminal neuronal differentiation
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115.
Previous investigations on the monkey kidney COS cell line demonstrated the
weak expression of fucosylated cell surface antigens and presence of
endogenous fucosyltransferase activities in cell extracts. RT-PCR analyses
have now revealed expression of five homologs of human fucosyltransferase
genes, FUT1, FUT4, FUT5, FUT7, and FUT8, in COS cell mRNA. The enzyme in
COS cell extracts acting on unsialylated Type 2 structures is closely
similar in its properties to the alpha1,3- fucosyltransferase encoded by
human FUT4 gene and does not resemble the product of the FUT5 gene.
Although FUT1 is expressed in the COS cell mRNA, it has not been possible
to demonstrate alpha1,2- fucosyltransferase activity in cell extracts but
the presence of Le(y) and blood-group A antigenic determinants on the cell
surface imply the formation of H-precursor structures at some stage. The
most strongly expressed fucosyltransferase in the COS cells is the
alpha1,6-enzyme transferring fucose to the innermost N -acetylglucosamine
unit in N - glycan chains; this enzyme is similar in its properties to the
product of the human FUT8 gene. The enzymes resembling the human FUT4 and
FUT8 gene products both had pH optima of 7.0 and were resistant to 10 mM
NEM. The incorporation of fucose into asialo-fetuin was optimal at 5.5 and
was inhibited by 10 mM NEM. This result initially suggested the presence of
a third fucosyltransferase expressed in the COS cells but we have now shown
that triantennary N- glycans with terminal nonreducing galactose units,
similar to those present in asialo-fetuin, are modified by a weak
endogenous beta-galactosidase in the COS cell extracts and thereby rendered
suitable substrates for the alpha1,6- fucosyltransferase.
相似文献
116.
M Kale R Ramsey-Goldman S Bernatsky MB Urowitz D Gladman PR Fortin M Petri E Yelin S Manzi S Edworthy O Nived S-C Bae D Isenberg A Rahman JG Hanly C Gordon S Jacobsen E Ginzler DJ Wallace GS Alarcón MA Dooley L Gottesman K Steinsson A Zoma J-L Senécal S Barr G Sturfelt L Dreyer L Criswell J Sibley JL Lee AE Clarke 《Arthritis research & therapy》2012,14(Z3):A15
117.
118.
119.
Marija Cvijović Daniel Dalevi Elizabeth Bilsland Graham JL Kemp Per Sunnerhagen 《BMC bioinformatics》2007,8(1):295
Background
The translational efficiency of an mRNA can be modulated by upstream open reading frames (uORFs) present in certain genes. A uORF can attenuate translation of the main ORF by interfering with translational reinitiation at the main start codon. uORFs also occur by chance in the genome, in which case they do not have a regulatory role. Since the sequence determinants for functional uORFs are not understood, it is difficult to discriminate functional from spurious uORFs by sequence analysis. 相似文献120.