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111.
Jacqueline A. Aitkenhead-Peterson Jess E. Alexander Jana Albrechtová Pavel Krám Barrett Rock Pavel Cudlín Jakub Hruška Zuzana Lhotaková Ryan Huntley Filip Oulehle Tomáš Polák William H. McDowell 《Plant and Soil》2006,283(1-2):187-201
Dissolved organic carbon and nitrogen (DOC and DON) produced in the forest floor are important for ecosystem functions such
as microbial metabolism, pedogenesis and pollutant transport. Past work has shown that both DOC and DON production are related
to litterfall and standing stocks of C and N in the forest floor. This study, conducted in spring, 2003, investigated variation
in forest floor water extractable DOC (WEDOC) and DON (WEDON) and forest floor C and N as a function of lignin, cellulose
and N contained in live canopy foliage across eight Picea abies [L.] Karst stands in northern Bohemia. Based on Near Infrared Spectroscopy (NIR) analysis of foliar materials, lignin:N and
cellulose:N content of the youngest needles (those produced in 2002) were positively and significantly related to WEDOC (R2 = 0.82–0.97; P<0.01) and to forest floor C:N ratio (R = 0.72–0.78; P<0.01). Foliar N was strongly and negatively related to WEDOC and C:N ratio (R = −0.91 and 0.72; P<0.05) among our study sites. WEDON was positively correlated to foliar lignin:N (R = 0.48; P<0.05; n=40). Forest floor C pools were not positively correlated with foliar lignin and cellulose and forest floor N pools were not
positively correlated with foliar N. Instead, a significant negative correlation was found between forest floor N pools and
foliar cellulose (R=−0.41; P<0.05), and between forest floor C pools and foliar N (R = −0.44; P<0.05). From a remote sensing standpoint, our results are important because canopy reflectance properties are primarily influenced
by the most recent foliage, and it was the chemistry of the most recently produced needles that showed a stronger relationship
with forest floor WEDOC and C:N ratio suggesting forest floor production of WEDOC can be calculated regionally with remote
sensing. 相似文献
112.
113.
Vojtechová M Senigl F Sloncová E Tuhácková Z 《Archives of biochemistry and biophysics》2006,455(2):136-143
Active, wild-type v-Src and its kinase-dead double Y416F-K295N mutant were expressed in hamster fibroblasts. Expression of the active v-Src induced activation of endogenous c-Src and increased general protein-tyrosine phosphorylation in the infected cells. Expression of the kinase-dead mutant induced hypophosphorylation of Tyr416 of the endogenous c-Src. The inactivation of c-Src was reversible, as confirmed by in vitro kinase activity of c-Src immunoprecipitated from the kinase-dead v-Src-expressing cells. Both activation and inactivation of c-Src may be explained by direct interaction of the v-Src and c-Src that may either facilitate transphosphorylation of the regulatory Tyr416 in the activation loop, or prevent it by formation of transient dead-end complexes of the Y416F-K295N mutant with c-Src. The interaction was also indicated by co-localization of v- and c-Src proteins in immunofluorescent images of the infected cells. These results suggest that dimerization of Src plays an important role in the regulation of Src tyrosine kinase activity. 相似文献
114.
Heleen Nailis Tom Coenye Filip Van Nieuwerburgh Dieter Deforce Hans J Nelis 《BMC molecular biology》2006,7(1):25-9
Background
Candida albicans biofilms are commonly found on indwelling medical devices. However, the molecular basis of biofilm formation and development is not completely understood. Expression analysis of genes potentially involved in these processes, such as the ALS (Agglutinine Like Sequence) gene family can be performed using quantitative PCR (qPCR). In the present study, we investigated the expression stability of eight housekeeping genes potentially useful as reference genes to study gene expression in Candida albicans (C. albicans) biofilms, using the geNorm Visual Basic Application (VBA) for Microsoft Excel. To validate our normalization strategies we determined differences in ALS1 and ALS3 expression levels between C. albicans biofilm cells and their planktonic counterparts. 相似文献115.
116.
Torres AG Fabani MM Vigorito E Williams D Al-Obaidi N Wojciechowski F Hudson RH Seitz O Gait MJ 《Nucleic acids research》2012,40(5):2152-2167
Anti-miRs are oligonucleotide inhibitors complementary to miRNAs that have been used extensively as tools to gain understanding of specific miRNA functions and as potential therapeutics. We showed previously that peptide nucleic acid (PNA) anti-miRs containing a few attached Lys residues were potent miRNA inhibitors. Using miR-122 as an example, we report here the PNA sequence and attached amino acid requirements for efficient miRNA targeting and show that anti-miR activity is enhanced substantially by the presence of a terminal-free thiol group, such as a Cys residue, primarily due to better cellular uptake. We show that anti-miR activity of a Cys-containing PNA is achieved by cell uptake through both clathrin-dependent and independent routes. With the aid of two PNA analogues having intrinsic fluorescence, thiazole orange (TO)-PNA and [bis-o-(aminoethoxy)phenyl]pyrrolocytosine (BoPhpC)-PNA, we explored the subcellular localization of PNA anti-miRs and our data suggest that anti-miR targeting of miR-122 may take place in or associated with endosomal compartments. Our findings are valuable for further design of PNAs and other oligonucleotides as potent anti-miR agents. 相似文献
117.
Hemocyanin (Hc) is a type-3 copper protein, containing dioxygen-binding active sites consisting of paired copper atoms. In the present study the thermal unfolding of the Hc from the marine mollusc Rapana thomasiana (RtH) has been investigated by combining differential scanning calorimetry, Fourier transform infrared (FTIR) and UV-vis absorption spectroscopy. Two important stages in the unfolding pathway of the Hc molecule were discerned. A first event, with nonmeasurable heat absorption, occurring around 60°C, lowers the binding of dioxygen to the type-3 copper groups. This pretransition is reversible and is ascribed to a slight change in the tertiary structure. In a second stage, with midpoint around 80°C, the protein irreversibly unfolds with a loss of secondary structure and formation of amorphous aggregates. Experiments with the monomeric structural subunits, RtH1 and RtH2, indicated that the heterogeneity in the process of thermal denaturation can be attributed to the presence of multiple 50kDa functional units with different stability. In accordance, the irreversible unfolding of a purified functional unit (RtH2-e) occurred at a single transition temperature. At slightly alkaline pH (Tris buffer) the C-terminal β-sheet rich domain of the functional unit starts to unfold before the α-helix-rich N-terminal (copper containing) domain, triggering the collapse of the global protein structure. Even around 90°C some secondary structure is preserved as shown by the FTIR spectra of all investigated samples, confirming the high thermostability of molluscan Hc. 相似文献
118.
Cyclic AMP binds to the HCN channel C terminus and variably stabilizes its open state. Using isothermal titration calorimetry, we show that cAMP binds to one subunit of tetrameric HCN2 and HCN4 C termini with high affinity (~0.12 μM) and subsequently with low affinity (~1 μM) to the remaining three subunits. Changes induced by high affinity binding already exist in both a constrained HCN2 tetramer and the unconstrained HCN1 tetramer. Natural "preactivation" of HCN1 may explain both the smaller effect of cAMP on stabilizing its open state and the opening of unliganded HCN1, which occurs as though already disinhibited. 相似文献
119.
Hollenstein M Wojciechowski F Leumann CJ 《Bioorganic & medicinal chemistry letters》2012,22(13):4428-4430
Pyrene-deoxynucleoside triphosphates (dPTPs), varying by the positioning of the aromatic system, were synthesized. Their ability to function as substrates for the Klenow fragment of Escherichia coli DNA polymerase I and the TdT polymerase was assessed. The dPTPs are all equally well tolerated by the Klenow fragment, and lead to elongation of up to 5 extra nucleotides of a ssDNA primer in a TdT-mediated reaction. The tailing efficiency of the dPTPs compares favorably to other less drastically modified dNTPs. 相似文献
120.
Joling KJ van Marwijk HW Smit F van der Horst HE Scheltens P van de Ven PM Mittelman MS van Hout HP 《PloS one》2012,7(1):e30936