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171.
172.
Viviana Centeno Gabriela Picotto Adriana Pérez Arturo Alisio Nori Tolosa de Talamoni 《Archives of biochemistry and biophysics》2011,(2):191
The role of 1,25(OH)2D3 on the intestinal NCX activity was studied in vitamin D-deficient chicks (-D) as well as the hormone effect on NCX1 protein and gene expression and the potential molecular mechanisms underlying the responses. Normal, -D and -D chicks treated with cholecalciferol or 1,25(OH)2D3 were employed. In some experiments, -D chicks were injected with cycloheximide or with cycloheximide and 1,25(OH)2D3 simultaneously. NCX activity was decreased by -D diet, returning to normal values after 50 IU daily of cholecalciferol/10 days or a dose of 1 μg calcitriol/kg of b.w. for 15 h. Cycloheximide blocked NCX activity enhancement produced by 1,25(OH)2D3. NCX1 protein and gene expression were diminished by -D diet and enhanced by 1,25(OH)2D3. Vitamin D receptor expression was decreased by -D diet, effect that disappeared after 1,25(OH)2D3 treatment. Rapid effects of 1,25(OH)2D3 on intestinal NCX activity were also demonstrated. The abolition of the rapid effects through addition of Rp-cAMPS and staurosporine suggests that non genomic effects of 1,25(OH)2D3 on NCX activity are mediated by activation of PKA and PKC pathways. In conclusion, 1,25(OH)2D3 enhances the intestinal NCX activity in -D chicks through genomic and non genomic mechanisms. 相似文献
173.
Alvarez-Martinez MT Fontes P Zomosa-Signoret V Arnaud JD Hingant E Pujo-Menjouet L Liautard JP 《Biochimica et biophysica acta》2011,1814(10):1305-1317
It is generally accepted that spongiform encephalopathies result from the aggregation into amyloid of a ubiquitous protein, the so-called prion protein. As a consequence, the dynamics of amyloid formation should explain the characteristics of the prion diseases: infectivity as well as sporadic and genetic occurrence, long incubation time, species barriers and strain specificities. The success of this amyloid hypothesis is due to the good qualitative agreement of this hypothesis with the observations. However, a number of difficulties appeared when comparing quantitatively the in vitro experimental results with the theoretical models, suggesting that some differences should hide important discrepancies. We used well defined quantitative models to analyze the experimental results obtained by in vitro polymerization of the recombinant hamster prion protein. Although the dynamics of polymerization resembles a simple nucleus-dependent fibrillogenesis, neither the initial concentration dependence nor off-pathway hypothesis fit with experimental results. Furthermore, seeded polymerization starts after a long time delay suggesting the existence of a specific mechanism that takes place before nucleus formation. On the other hand, polymerization dynamics reveals a highly stochastic mechanism, the origin of which appears to be caused by nucleation heterogeneity. Moreover, the specific structures generated during nucleation are maintained during successive seeding although a clear improvement of the dynamics parameters (polymerization rate and lag time) is observed. We propose that an additional on-pathway reaction takes place before nucleation and it is responsible for the heterogeneity of structures produced during prion protein polymerization in vitro. These amyloid structures behave like prion strains. A model is proposed to explain the genesis of heterogeneity among prion amyloid. 相似文献
174.
175.
Notomista E Pennacchio F Cafaro V Smaldone G Izzo V Troncone L Varcamonti M Di Donato A 《Microbial ecology》2011,61(3):582-594
Novosphingobium sp. PP1Y, isolated from a surface seawater sample collected from a closed bay in the harbour of Pozzuoli (Naples, Italy),
uses fuels as its sole carbon and energy source. Like some other Sphingomonads, this strain can grow as either planktonic
free cells or sessile-aggregated flocks. In addition, this strain was found to grow as biofilm on several types of solid and
liquid hydrophobic surfaces including polystyrene, polypropylene and diesel oil. Strain PP1Y is not able to grow on pure alkanes
or alkane mixtures but is able to grow on a surprisingly wide range of aromatic compounds including mono, bi, tri and tetracyclic
aromatic hydrocarbons and heterocyclic compounds. During growth on diesel oil, the organic layer is emulsified resulting in
the formation of small biofilm-coated drops, whereas during growth on aromatic hydrocarbons dissolved in paraffin the oil
layer is emulsified but the drops are coated only if the mixtures contain selected aromatic compounds, like pyrene, propylbenzene,
tetrahydronaphthalene and heterocyclic compounds. These peculiar characteristics suggest strain PP1Y has adapted to efficiently
grow at the water/fuel interface using the aromatic fraction of fuels as the sole carbon and energy source. 相似文献
176.
Polizzi V Fazzini L Adams A Picco AM De Saeger S Van Peteghem C De Kimpe N 《Microbial ecology》2011,62(4):838-852
A Penicillium decumbens strain was collected from a water-damaged building, and the production of microbial volatile organic compounds (MVOCs) was
investigated by means of headspace solid-phase microextraction, followed by GC-MS analysis. The strain was characterized by
a high production of (+)-thujopsene. The influence of various temperatures, relative humidity (RH) values, substrates, and
inoculum concentrations on fungal growth and (+)-thujopsene production was studied. The optimal temperature and relative humidity
for P. decumbens growth were 30°C and 100% RH, respectively. In general, the more favourable the incubation parameters were for growth, the
faster maximum (+)-thujopsene production was reached. Moreover, the antifungal activity of thujopsene was tested against 16
fungal strains. The growth of five of these fungal strains was negatively affected both by thujopsene alone and when grown
in contact with the MVOCs produced by P. decumbens. Following these results and since growth of P. decumbens itself was also inhibited by thujopsene, an autoregulatory function for this compound was proposed. Few data are present
in the literature about chemical communication between fungi. The present research could, therefore, contribute to understanding
fungal metabolism and behaviour in indoor environments. 相似文献
177.
178.
Traver MK Henry SC Cantillana V Oliver T Hunn JP Howard JC Beer S Pfeffer K Coers J Taylor GA 《The Journal of biological chemistry》2011,286(35):30471-30480
The immunity-related GTPases (IRGs) are a family of proteins induced by interferon-γ that play a crucial role in innate resistance to intracellular pathogens. The M subfamily of IRG proteins (IRGM) plays a profound role in this context, in part because of the ability of its members to regulate the localization and expression of other IRG proteins. We present here evidence that IRGM proteins affect the localization of the guanylate-binding proteins (GBPs), a second family of interferon-induced GTP-binding proteins that also function in innate immunity. Absence of Irgm1 or Irgm3 led to accumulation of Gbp2 in intracellular compartments that were positive for both the macroautophagy (hereafter referred to as autophagy) marker LC3 and the autophagic adapter molecule p62/Sqstm1. Gbp2 was similarly relocalized in cells in which autophagy was impaired because of the absence of Atg5. Both in Atg5- and IRGM-deficient cells, the IRG protein Irga6 relocalized to the same compartments as Gbp2, raising the possibility of a common regulatory mechanism. However, other data indicated that Irga6, but not Gbp2, was ubiquitinated in IRGM-deficient cells. Similarly, coimmunoprecipitation studies indicated that although Irgm3 did interact directly with Irgb6, it did not interact with Gbp2. Collectively, these data suggest that IRGM proteins indirectly modulate the localization of GBPs through a distinct mechanism from that through which they regulate IRG protein localization. Further, these results suggest that a core function of IRGM proteins is to regulate autophagic flux, which influences the localization of GBPs and possibly other factors that instruct cell-autonomous immune resistance. 相似文献
179.
Salem T Mazzella A Barberini ML Wengier D Motillo V Parisi G Muschietti J 《The Journal of biological chemistry》2011,286(6):4882-4891
The tip-growing pollen tube is a useful model for studying polarized cell growth in plants. We previously characterized LePRK2, a pollen-specific receptor-like kinase from tomato (1). Here, we showed that LePRK2 is present as multiple phosphorylated isoforms in mature pollen membranes. Using comparative sequence analysis and phosphorylation site prediction programs, we identified two putative phosphorylation motifs in the cytoplasmic juxtamembrane (JM) domain. Site-directed mutagenesis in these motifs, followed by transient overexpression in tobacco pollen, showed that both motifs have opposite effects in regulating pollen tube length. Relative to LePRK2-eGFP pollen tubes, alanine substitutions in residues of motif I, Ser(277)/Ser(279)/Ser(282), resulted in longer pollen tubes, but alanine substitutions in motif II, Ser(304)/Ser(307)/Thr(308), resulted in shorter tubes. In contrast, phosphomimicking aspartic substitutions at these residues gave reciprocal results, that is, shorter tubes with mutations in motif I and longer tubes with mutations in motif II. We conclude that the length of pollen tubes can be negatively and positively regulated by phosphorylation of residues in motif I and II respectively. We also showed that LePRK2-eGFP significantly decreased pollen tube length and increased pollen tube tip width, relative to eGFP tubes. The kinase activity of LePRK2 was relevant for this phenotype because tubes that expressed a mutation in a lysine essential for kinase activity showed the same length and width as the eGFP control. Taken together, these results suggest that LePRK2 may have a central role in pollen tube growth through regulation of its own phosphorylation status. 相似文献
180.
Laura Chalup Marina Grabiele Viviana Solís Neffa Guillermo Seijo 《Journal of plant research》2014,127(4):469-480
The genome size was surveyed in 13 Notolathyrus species endemic to South America by flow cytometry and analyzed in an evolutionary and biogeographic context. A DNA content variation of 1.7-fold was registered, and four groups of species with different DNA content were determined. Although, the 2C values were correlated with the total chromosome length and intrachromosomal asymmetry index (A1), the karyotype formula remained almost constant. The conservation of the karyotype formula is in agreement with proportional changes of DNA in the chromosome arms. Species with annual life cycle and shorter generation time had the lowest DNA content and the data suggest that changes in DNA content involved reductions of genome size in the perennial to annual transitions. The variation of 2C values was correlated with precipitation of the coldest quarter and, to some extent, with altitude. Additional correlations with other variables were observed when the species were analyzed separately according to the biogeographic regions. In general, the species with higher DNA content were found in more stable environments. The bulk of evidence suggests that changes on genome size would have been one of the most important mechanisms that drove or accompanied the diversification of Notolathyrus species. 相似文献