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181.
Graciela L. Salerno 《Plant science》1985,42(1):5-8
The presence of sucrose and the enzymes related to sucrose metabolism, i.e. sucrose synthase (SS) (UDP-glucose: D-fructose-2-glucosyl transferase, EC 2.4.1.13), sucrose phosphate synthase (SPS) (UDP-glucose: D-fructose-6-phosphate-2-glucosyl transferase, EC 2.4.1.14) and invertase (β-D-fructofuranoside fructohydrolase, EC 3.2.1.26) was demonstrated in Prototheca zopfii, a colorless alga. The levels of enzyme activities were lower than those obtained in Chlorella vulgaris, which is generally considered the photosynthetic counterpart of P. zopfii. Whem enzyme activities were measured in bleached cells of C. vulgaris, the levels were of the same order than those found in P. zopfii. These results would indicate that the sucrose metabolizing enzymes are not related to the algae ability to carry on photosynthesis. 相似文献
182.
Vanesa Amarelle Federico Rosconi Juan Manuel Lázaro-Martínez Graciela Buldain Francisco Noya Mark R. O’Brian Elena Fabiano 《Biometals》2016,29(2):333-347
Ensifer meliloti is a nitrogen-fixing symbiont of the alfalfa legume able to use heme as an iron source. The transport mechanism involved in heme acquisition in E. meliloti has been identified and characterized, but the fate of heme once inside the cell is not known. In silico analysis of E. meliloti 1021 genome revealed no canonical heme oxygenases although two genes encoding putative heme degrading enzymes, smc01518 and hmuS, were identified. SMc01518 is similar to HmuQ of Bradyrhizobium japonicum, which is weakly homologous to the Staphylococcus aureus IsdG heme-degrading monooxygenase, whereas HmuS is homolog to Pseudomonas aeruginosa PhuS, a protein reported as a heme chaperone and as a heme degrading enzyme. Recombinant HmuQ and HmuS were able to bind hemin with a 1:1 stoichiometry and displayed a Kd value of 5 and 4 µM, respectively. HmuS degrades heme in vitro to the biliverdin isomers IX-β and IX-δ in an equimolar ratio. The HmuQ recombinant protein degrades heme to biliverdin IX-δ only. Additionally, in this work we demonstrate that humS and hmuQ gene expression is regulated by iron and heme in a RirA dependent manner and that both proteins are involved in heme metabolism in E. meliloti in vivo. 相似文献
183.
184.
Carlos Villegas-Gabutti Gisela E. Pennacchio Graciela A. Jahn Marta Soaje 《Neurochemical research》2016,41(12):3344-3355
Estrogen action is necessary for evidencing the stimulatory action of mifepristone and naloxone on prolactin (PRL) secretion during late pregnancy. Our aim is to determine the mechanism mediating this facilitator action of estrogens. To investigate the hypothalamic mechanisms involved in estrogen actions in PRL secretion at the end of pregnancy, we measured the effect of pretreatment with the estrogen antagonist tamoxifen on the expression of tyrosine hydroxylase (TH), hormone receptors (ERα and β, PRs, PRLR(long)), and μ- and κ- opioid receptors (ORs) at mRNA (by semiquantitative RT-PCR) and protein (by western blot for TH, PRLR(long), ERα, PRs, μ- and ORs) levels in extracts of medial basal hypothalamus (MBH) and serum PRL, E2 and P4 levels (by RIA) in mifepristone- and naloxone-treated rats. Tamoxifen administration partially prevented PRL release induced by the combined treatment. TH expression diminished and ERα expression increased in mifepristone-treated rats at mRNA and protein levels and tamoxifen partially prevented these changes with no effect on PRs expression. Mifepristone increased PRLR(long) mRNA levels; this increase was blocked by tamoxifen. Combined tamoxifen and mifepristone treatment decreased μ- and k-ORs mRNA but not protein levels. In conclusion, E2 induces neuroadaptive mechanisms necessary to facilitate PRL release preceding delivery. Acting through ERα, E2 modulates hypothalamic dopaminergic neurons activity, regulating TH, μ- and κ-ORs and PRLR(long) expression, and is necessary for evidencing the effects of P4 withdrawal. Its presence on days 14 and 15 of pregnancy is crucial to facilitate the opioid system modulation of PRL secretion at the end of pregnancy in the rat. 相似文献
185.
Hydrolysis of Pork Muscle Sarcoplasmic Proteins by Lactobacillus curvatus and Lactobacillus sake 总被引:4,自引:0,他引:4
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Silvina Fadda Yolanda Sanz Graciela Vignolo M.-Concepcin Aristoy Guillermo Oliver Fidel Toldr 《Applied microbiology》1999,65(2):578-584
Lactobacillus curvatus CECT 904 and Lactobacillus sake CECT 4808 were selected on the basis of their proteolytic activities against synthetic substrates. Further, the effects of whole cells, cell extracts, and a combination of both enzymatic sources on muscle sarcoplasmic proteins were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and reverse-phase high-performance liquid chromatography analyses. Strains of both species displayed proteinase activities on five sarcoplasmic proteins. The inoculation of whole cells caused a degradation of peptides, whereas the addition of cell extracts resulted in the generation of both hydrophilic and hydrophobic peptides. This phenomenon was remarkably more pronounced when L. curvatus was involved. Whole cells also consumed a great amount of free amino acids, while the addition of intracellular enzymes contributed to their generation. L. sake accounted for a greater release of free amino acids. In general, cell viability and also proteolytic events were promoted when cell suspensions were provided with cell extracts as an extra source of enzymes. 相似文献
186.
Alejandra Marcela Ortiz Germán Robledo Guillermo Seijo José Francisco Montenegro Valls Graciela Inés Lavia 《Journal of plant research》2017,130(5):791-807
Rhizomatosae is a taxonomic section of the South American genus Arachis, whose diagnostic character is the presence of rhizomes in all its species. This section is of particular evolutionary interest because it has three polyploid (A. pseudovillosa, A. nitida and A. glabrata, 2n?=?4x?=?40) and only one diploid (A. burkartii, 2n?=?2x?=?20) species. The phylogenetic relationships of these species as well as the polyploidy nature and the origin of the tetraploids are still controversial. The present study provides an exhaustive analysis of the karyotypes of all rhizomatous species and six closely related diploid species of the sections Erectoides and Procumbentes by cytogenetic mapping of DAPI/CMA heterochromatin bands and 5S and 18–26S rDNA loci. Chromosome banding showed variation in the DAPI heterochromatin distribution pattern, which, together with the number and distribution of rDNA loci, allowed the characterization of all species studied here. The bulk of chromosomal markers suggest that the three rhizomatous tetraploid species constitute a natural group and may have at least one common diploid ancestor. The cytogenetic data of the diploid species analyzed evidenced that the only rhizomatous diploid species—A. burkartii—has a karyotype pattern different from those of the rhizomatous tetraploids, showing that it is not likely the genome donor of the tetraploids and the non-monophyletic nature of the section Rhizomatosae. Thus, the tetraploid species should be excluded from the R genome, which should remain exclusively for A. burkartii. Instead, the karyotype features of these tetraploids are compatible with those of different species of the sections Erectoides and Procumbentes (E genome species), suggesting the hypothesis of multiple origins of these tetraploids. In addition, the polyploid nature and the group of diploid species closer to the tetraploids are discussed. 相似文献
187.
Néstor Ríos Carmen Bouza Verónica Gutiérrez Graciela García 《Environmental Biology of Fishes》2017,100(9):1047-1067
The Neotropical catfish genus Rhamdia inhabits rivers and lakes from Mexico to Argentina. Previous studies have found that the taxonomy of this genus, as well as that of R. quelen, remains controversial. The present study aims to contribute to the understanding of Rhamdia systematics by delimiting putative species, and to elucidate the pattern of genetic differentiation of Rhamdia at different geographic levels within the cis-andean region. Species boundaries were defined by Generalized Mixed Yule Coalescent and Automatic Barcode Gap Discovery methods, and by phylogenetic analyses of cytochrome b (cyt b) sequences. Moreover, we performed phylogeographic analyses based on cyt b sequences and microsatellite markers. Patterns of differentiation were analyzed at three nested geographic levels: in the main cis-andean basins (macrogeographic scale); in the second major Neotropical basin system (mesogeographic scale), which encompasses La Plata basin, Patos-Merin basin, and the coastal lagoons draining to SW Atlantic Ocean; and finally, in the three most important coastal lagoons for artisanal fisheries in Uruguay (microgeographic scale). Sixteen species were found within Rhamdia, divided into two clades (cis- and trans-andean clades), each composed of eight putative species. Cis-andean Rhamdia species have probably diverged due to vicariance events occurring between and within basins since late Miocene-Pleistocene. Microgeographic scale analysis based on cyt b and microsatellite data revealed a high genetic structuring among the studied coastal lagoons. Mitochondrial and microsatellite markers enabled to identify three different populations, corresponding to the three coastal lagoons analyzed, which would have diverged recently and could be considered as different Management Units. 相似文献
188.
Mariana?Mazza Graciela?O.?Davel Constanza?G.?Taverna Nicolás?Refojo Cristina?E.?Canteros Nadia?S.?Bueno Guillermina?Isla Ruben?A.?Abrantes Alejandra?I.?Hevia Adriana?I.?Toranzo National Mycology Laboratory Network of Argentina 《Current fungal infection reports》2017,11(4):209-219
Purpose of Review
Cryptococcal meningitis is the most common fungal infection of the central nervous system and the third most frequent neurological complication in AIDS patients. To understand the Argentinean epidemiology of cryptococcosis, several efforts have been made by the National Reference Laboratory in Clinical Mycology.Recent Findings
In Argentina, reports of distribution and frequency of Cryptococcus neoformans and Cryptococcus gattii isolates are scarce and very little is known about its circulating genotypes and mating types. The National Mycology Laboratory Network and the National Reference Laboratory in Clinical Mycology joined forces to estimate the prevalence of cryptococcosis and to obtain and to analyse epidemiological data of this important fungal infection.Summary
Data presented here were recovered from 1998 to 2016 and represents an approximation to the actual situation of cryptococcosis in Argentina. These results could be useful to design future investigations.189.
Synthesis of a novel superabsorbent hydrogel by copolymerization of acrylamide and cashew gum modified with glycidyl methacrylate 总被引:5,自引:0,他引:5
Marcos R. Guilherme Adriano V. Reis Sulen H. Takahashi Adley F. Rubira Judith P.A. Feitosa Edvani C. Muniz 《Carbohydrate polymers》2005,61(4):464-471
Novel superabsorbent hydrogels were manufactured using chemically modified cashew gum (CGMA) and acrylamide (AAm) as reactants. The route for the synthesis was feasible due to the incorporation of glycidyl methacrylate (GMA) into structure of cashew gum (CG) to form the cashew gum-methacrylated (CGMA), in an appropriate mixture water-DMSO, as solvent, and using TEMED as catalyst. Thereafter, the CGMA was copolymerized with AAm yielding (CGMA-co-AAm) hydrogels. The main characteristics of raw and the modified materials are reported in this paper. 13C NMR, 1H NMR and FTIR spectroscopies confirmed the incorporation of vinyl groups, from GMA, into CG structure. By the spectrophotometry analyses, it was found that, ca. 82% of GMA was incorporated to the CG after 24 h of reaction. The cross-linking of CGMA or co-polymerization of CGMA with acrylamide leads to a hydrogel formation. Their gelation was characterized by FT-IR analysis. Alkaline hydrolysis at 40 °C for 3 and 4.5 h increased the water uptake (WU) capacity. Hydrolyzed CGMA-co-AAm hydrogels present higher values of WU (up to 1500) and may be classified as water superabsorbent material. Applications in agriculture, as soil conditioner, and in biomedical field, as biomaterial (scaffold) are being investigated. 相似文献
190.
Jean Guy LeBlanc Florence Ledue-Clier Martine Bensaada Graciela Savoy de Giori Theodora Guerekobaya Fernando Sesma Vincent Juillard Sylvie Rabot Jean-Christophe Piard 《BMC microbiology》2008,8(1):22