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991.
Since the emergence of the ‘microbial loop’ concept, heterotrophic flagellates have received particular attention as grazers
in aquatic ecosystems. These microbes have historically been regarded incorrectly as a homogeneous group of bacterivorous
protists in aquatic systems. More recently, environmental rDNA surveys of small heterotrophic flagellates in the pelagic zone
of freshwater ecosystems have provided new insights. (i) The dominant phyla found by molecular studies differed significantly
from those known from morphological studies with the light microscope, (ii) the retrieved phylotypes generally belong to well-established
eukaryotic clades, but there is a very large diversity within these clades and (iii) a substantial part of the retrieved sequences
cannot be assigned to bacterivorous but can be assigned instead to parasitic and saprophytic organisms, such as zoosporic
true fungi (chytrids), fungus-like organisms (stramenopiles), or virulent alveolate parasites (Perkinsozoa and Amoebophrya sp.). All these microorganisms are able to produce small zoospores to assure dispersal in water during their life-cycles.
Based on the existing literature on true fungi and fungus-like organisms, and on the more recently published eukaryotic rDNA
environmental studies and morphological observations, we conclude that previously overlooked microbial diversity and related
ecological potentials require intensive investigation (i) for an improved understanding of the roles of heterotrophic flagellates
in pelagic ecosystems and (ii) to properly integrate the concept of ‘the microbial loop’ into modern pelagic microbial ecology. 相似文献
992.
Mendoza Muñoz DF Algecira Enciso NA Córdoba Ruiz H Barrera Avellaneda LA 《Biotechnology letters》2008,30(10):1727-1734
A simple structured model is proposed for the methanol production phase of the iduronate 2-sulphate sulfatase recombinant enzyme (IDShr) in Pichia patoris Mut(+). The model is mainly focused in oxidative stress phenomenon due to methanol consumption and based on extracellular experimental information and the basic knowledge of methanol metabolism in Pichia pastoris yeast (P. pastoris). The model's prediction shows a reasonable accuracy as compared with the experimental data. Likewise, it was proved that this model is able to simulate the production of other recombinant protein in P. pastoris. 相似文献
993.
María C. Manca de Nadra Carlos A. Nadra Chaud Aida Pesce de Ruiz Holgado Dr. Guillermo Oliver 《Current microbiology》1986,13(3):155-158
Lactobacillus leichmannii ATCC 4797 metabolizes arginine via the arginine dihydrolase pathway producing ornithine, ammonia, carbon dioxide, and ATP. The specific activities of arginine deiminase and ornithine transcarbamylase were two-or threefold lower (stationary growth phase) in galactose-grown cells. The addition of arginine increased the specific activities of these two enzymes with all growth sugars. When glucose was virtually exhausted from the medium, maximum activities of both enzymes were achieved. The formation of two first enzymes of the arginine dihydrolase pathway inL. leichmannii ATCC 4797 seems to be under the control of two processes: induction by arginine and repression of the induced synthesis by glucose.Dedicated to Dr. Luis F. Leloir on the occasion of his 80th birthday, 6 September 1986. 相似文献
994.
Proteomic profiling of integral membrane proteins associated to pathogenicity in Vibrio parahaemolyticus strains 下载免费PDF全文
Jesús A. Pérez‐Acosta Marcel Martínez‐Porchas José M. Elizalde‐Contreras Juan Manuel Leyva Eliel Ruiz‐May Teresa Gollas‐Galván Luis R. Martínez‐Córdova José Ángel Huerta‐Ocampo 《Microbiology and immunology》2018,62(1):14-23
Vibrio parahaemolyticus has been recognized as the causal agent of early mortality syndrome and is currently considered an emerging shrimp disease causing losses of millions in the aquaculture industry. Integral membrane proteins are widely recognized as pathogenicity factors involved in essential mechanisms for V. parahaemolyticus infection, which makes them attractive as therapeutic targets. However, their physico‐chemical properties and weak expression has resulted in under‐representation of these proteins in conventional bottom‐up proteomics, making integral membrane proteomics a challenging task. Integral membrane proteins from a bacterial strain isolated from the hepatopancreases of white shrimp with early mortality syndrome and identified by 16S rRNA sequencing as V. parahaemolyticus and an ATCC strain that is pathogenic for humans were obtained by a sequential extraction method and subjected to relative quantification and identification by isobaric Tags for Relative and Absolute Quantitation. A homology database search resulted in identification of more than two hundred proteins, 35 of which are recognized as pathogenic factors showed statistically significant differential accumulation between the strains. These proteins are mainly associated with adherence, secretion systems, cell division, transport, lysogenization, movement and virulence. Identification of pathogenicity‐related proteins in V. parahaemolyticus provides valuable information for developing strategies based on molecular mechanisms that inhibit these proteins, which may be useful therapeutic targets for assisting the shrimp and aquaculture industry. 相似文献
995.
Carlos Ruiz de Alegría Puig Jesús Agüero-Balbín Carlos Fernández-Mazarrasa Luis Martínez-Martínez 《Revista iberoamericana de micología》2018,35(3):130-133
Background
Matrix-assisted laser desorption-time of flight mass spectrometry (MALDI-TOF-MS) represents a revolution in the identification of microorganisms of clinical interest. Many studies have confirmed the accuracy and fastness of this tool with routine strains.Aims
To identify clinical isolates of Candida from patients diagnosed with candidemia.Methods
Vitek-MS? system was used with a collection of 298 blood isolates of the genus Candida represented by 9 different species. Sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA cluster was used as the reference method.Results
The results of Vitek-MS? were concordant with those obtained with the reference method for 279 (93.62%) isolates (Kappa coefficient (κ) = 0.91). Vitek-MS? misidentified 10 (3.36%) isolates and did not identify 9 (3.02%) isolates.Conclusions
This study determines the potential of Vitek-MS? in yeast identification, being a reliable and fast alternative in the clinical laboratory, with an acceptable sensitivity of 82% (IC 95%: 70–90.6%), in comparison with a 100% (IC 95%: 92.9–100%) sensitivity of the conventional methods. 相似文献996.
Juan Diego Ibáñez‐Álamo Magdalena Ruiz‐Rodríguez Juan José Soler 《Journal of avian biology》2014,45(4):354-358
Nestlings of many bird species produce fecal sacs, excrements encapsulated within a mucous covering. Although it facilitates parents' removal of feces from nests, which would improve hygienic conditions for developing nestlings, no functional (i.e. adaptive) explanation of fecal sac production has been previously investigated. We propose that the mucous covering would isolate enteric pathogenic bacteria, thereby preventing contamination of nestlings and parents. This antimicrobial hypothesis therefore predicts that density of bacteria would be drastically reduced from the inside to the outside of nestlings' droppings, and that the fecal sac covering would inhibit other bacterial grow. We tested these predictions by means of culturing bacteria obtained from different parts of the sac and inhibition tests. In accordance with the hypothesis, bacterial loads of the outside of fecal sacs were significantly lower than those estimated from the inside of the covering. In addition, we did not find evidence of antimicrobial activity of the covering, which suggests that the hypothesized bacterial isolation function is accomplished by a physical rather than a chemical protection. Bacterial density of the liquid that permeates out after 23 min does not differ with that estimated for the inside of the sac, suggesting short‐term effects of fecal sacs as bacterial barrier. These findings highlight the major role of bacterial infections as a selective pressure for explaining the evolution of traits that, as the covering of fecal sacs, facilitate nest sanitation in this group of animals. 相似文献
997.
Ramirez-Espain X Ruiz L Martin-Malpartida P Oschkinat H Macias MJ 《Journal of molecular biology》2007,373(5):1255-1268
Formin homology 1 (FH1), is a long proline-rich region of formins, shown to bind to five WW containing proteins named formin binding proteins (FBPs). FH1 has several potential binding regions but only the PPLPx motif and its interaction with FBP11WW1 has been characterized structurally. To detect whether additional motifs exist in FH1, we synthesized five peptides and investigated their interaction with FBP28WW2, FBP11WW1 and FBP11WW2 domains. Peptides of sequence PTPPPLPP (positive control), PPPLIPPPP and PPLIPPPP (new motifs) interact with the domains with micromolar affinity. We observed that FBP28WW2 and FBP11WW2 behave differently from FBP11WW1 in terms of motif selection and affinity, since they prefer a doubly interrupted proline stretch of sequence PPLIPP. We determined the NMR structure of three complexes involving the FBP28WW2 domain and the three ligands. Depending on the peptide under study, the domain interacts with two proline residues accommodated in either the XP or the XP2 groove. This difference represents a one-turn displacement of the domain along the ligand sequence. To understand what drives this behavior, we performed further structural studies with the FBP11WW1 and a mutant of FBP28WW2 mimicking the XP2 groove of FBP11WW1. Our observations suggest that the nature of the XP2 groove and the balance of flexibility/rigidity around loop 1 of the domain contribute to the selection of the final ligand positioning in fully independent domains. Additionally, we analyzed the binding of a double WW domain region, FBP11WW1-2, to a long stretch of FH1 using fluorescence spectroscopy and NMR titrations. With this we show that the presence of two consecutive WW domains may also influence the selection of the binding mode, particularly if both domains can interact with consecutive motifs in the ligand. Our results represent the first observation of protein-ligand recognition where a pair of WW and two consecutive motifs in a ligand participate simultaneously. 相似文献
998.
Alonso A Fernández R Moreno M Ordóñez P Díaz F González C 《Experimental biology and medicine (Maywood, N.J.)》2007,232(4):542-549
It has been widely shown that there is a complex interaction between sex steroids and leptin effects on body weight. In this sense, the absence of female sex steroids is linked to a significant increase in body weight, which seems to be related to an impairment of the central actions of leptin. The present study was designed to elucidate the effects of two different treatments with 17beta-estradiol on leptin receptor and serum leptin levels in ovariectomized rats, a model of postmenopausal condition. Our results have shown that plasma leptin levels in ovariectomized rats were lower than in estradiol-treated animals, thereby supporting a positive effect of this steroid. Recent information has extended leptin actions to peripheral tissues, mainly to insulin-dependent tissues, this effect being related to metabolic actions. To better understand the peripheral effects of leptin and their possible regulation by estradiol treatment, we have analyzed leptin receptor expression in the skeletal muscle and the adipose tissue. Our results showed a tissue-specific regulation of this protein: Ob-Rb expression in the adipose tissue decreased when the time of treatment or the dose of estradiol administered increased, suggesting less sensitivity to leptin in this tissue, whereas in the skeletal muscle the changes in this protein followed the same profile as the plasma leptin levels. We think that this specific regulation could ensure a different response of each tissue toward the same serum leptin level. Further studies to clarify this situation are ongoing. 相似文献
999.
Juan J. Ríos Begoña Blasco Luís M. Cervilla María M. Rubio-Wilhelmi Juan M. Ruiz Luis Romero 《Plant Growth Regulation》2008,56(1):43-51
Selenium (Se) is considered an essential trace element for animals because of its nutritional and clinical value, including
its special relevance in cancer prevention, and thus Se is at present used in biofortification programmes. However, possible
effects of Se application on S metabolism and plant growth are still not clear. Thus, we analysed the effect that Se application
in two different forms (selenate versus selenite) exerts on the S metabolism in lettuce plants grown for 66 days. Our results
indicate that the application of selenite as opposed to selenate does not affect the foliar concentration of S. With respect
to different enzymes in charge of sulphate (SO42−) assimilation, the ATP-sulphurylase activity varies only with the application of different rates of selenate, while the activity
of O-acetylserine(thiol)lyase (OAS-TL) and serine-acetyltransferase (SAT) increase in activity mainly when selenite is applied.
Finally, the concentration of cysteine (Cys) and total thiols (SH-total), fundamentally in the selenate treatments, increased
with shoot biomass. In conclusion, this study confirms that the form and application rate of Se affects S assimilation, selenate
being the more suitable form to improve effectiveness of the biofortification programme with this trace element. 相似文献
1000.
P Joshi E Turola A Ruiz A Bergami D D Libera L Benussi P Giussani G Magnani G Comi G Legname R Ghidoni R Furlan M Matteoli C Verderio 《Cell death and differentiation》2014,21(4):582-593
Alzheimer''s disease (AD) is characterized by extracellular amyloid-β (Aβ) deposition, which activates microglia, induces neuroinflammation and drives neurodegeneration. Recent evidence indicates that soluble pre-fibrillar Aβ species, rather than insoluble fibrils, are the most toxic forms of Aβ. Preventing soluble Aβ formation represents, therefore, a major goal in AD. We investigated whether microvesicles (MVs) released extracellularly by reactive microglia may contribute to AD degeneration. We found that production of myeloid MVs, likely of microglial origin, is strikingly high in AD patients and in subjects with mild cognitive impairment and that AD MVs are toxic for cultured neurons. The mechanism responsible for MV neurotoxicity was defined in vitro using MVs produced by primary microglia. We demonstrated that neurotoxicity of MVs results from (i) the capability of MV lipids to promote formation of soluble Aβ species from extracellular insoluble aggregates and (ii) from the presence of neurotoxic Aβ forms trafficked to MVs after Aβ internalization into microglia. MV neurotoxicity was neutralized by the Aβ-interacting protein PrP and anti-Aβ antibodies, which prevented binding to neurons of neurotoxic soluble Aβ species. This study identifies microglia-derived MVs as a novel mechanism by which microglia participate in AD degeneration, and suggest new therapeutic strategies for the treatment of the disease. 相似文献