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201.
Sterin-Borda Leonor Cremaschi Graciela Genaro Ana Maria Echagüe Agustina Vila Goin Juan Carlos Borda Enri 《Molecular and cellular biochemistry》1996,162(1):75-82
We have already demonstrated the presence of antibodies in the sera of chagasic patients with the ability to interact with neurotransmitter receptors triggering several intracellular pathways of transduction signals. Here we show that, chagasic IgG induced protein kinase C (PKC) translocation to rat cardiac membranes and this effect was inhibited by muscarinic cholinergic blockers atropine and AF-DX 116 pointing to the participation of M2 receptors in this effect. It was also able to stimulate nitric oxide synthase (NOS) activity and this action was blunted by phospholipase C (PLC) and PKC inhibitors indicating that the production of nitric oxide (NO) would be the consequence of the cascade of enzymatic pathways triggered by mAChR activation. PKC and NOS activities were involved in chagasic IgG negative inotropic actions on rat isolated myocardium as its effects were blunted by staurosporine and L-N-monomethyl arginine. Furthermore, low concentrations of chagasic IgG inhibited the cardiac mechanical action of carbachol in a non-competitive manner. These data suggested that PKC activation in myocardium by chagasic IgG would be involved in its physiological actions by modulating NOS activity. The participation of PKC-mediated phosphorylation of mAChR leading to receptor desensitization as one of the causes of dysautonomia is also discussed. 相似文献
202.
Patricio Morales Teresa Socias Jacqueline Cortez Miguel N. Llanos 《Molecular reproduction and development》1994,38(2):222-230
The effect of chymotrypsin inhibitors and substrates on the human sperm acrosome reaction stimulated by the human zonae pellucidae or follicular fluid were evaluated. Motile spermatozoa, selected by a Percoll gradient, were incubated at 1 × 107 cells/ml, 37°C, and 5% CO2, After 4.5 hr, the chymotrypsin inhibitor TPCK (N-Tosyl-L-Phenylalanine-Chloromethyl Ketone) or the substrate ATEE (N-Acetyl-L-Tyrosine Ethyl Ester) were added for 30 min. Then, four oocytes were added and the percentage of acrosome-reacted spermatozoa on the zona was determined. TPCK and ATEE inhibited the zona pellucida-induced acrosome reaction. The chymotrypsin inhibitors TPCK and chymostatin and the chymotrypsin substrates ATEE, BTEE (N-Benzoyl-L-Tyrosine Ethyl Ester), Succinyl-Ala-Ala-Phe-7-Amido-4-Methyl-Coumarin (Suc-Ala-Ala-Phe-AMC), and Succinyl-Leu-Leu-Val-Tyr-7-Amido-4-Methyl-Coumarin (Suc-Leu-Leu-Val-Tyr-AMC) inhibited the human follicular fluid-induced acrosome reaction. Sperm extracts exhibited hydrolytic activity toward Suc-Ala-Ala-Phe-AMC and Suc-Leu-Leu-Val-Tyr-AMC. This enzyme activity was abolished by TPCK and chymostatin, was independent of Ca2+, and was not modified by 1,10 phenanthroline. In addition, the activity was present in the supernatant after the acrosome reaction was induced with calcium ionophore and in epididymal spermatozoa recovered from the cauda region. Electron microscopic observations indicated that the inhibitors prevented the membrane events of the acrosome reaction. These data suggest an association between human spermatozoa and chymotrypsin-like activity with a possible role in the acrosome reaction. © 1994 Wiley-Liss, Inc. 相似文献
203.
Provenzano Lucas Bortolussi Silva González Sara J. Postuma Ian Protti Nicoletta Portu Agustina Olivera Maria Silvina Rodriguez Luis Miguel Fregenal Daniel Altieri Saverio 《Radiation and environmental biophysics》2019,58(2):237-245
Radiation and Environmental Biophysics - Osteosarcoma is the most common primary malignant tumour of bone in young patients. The survival of these patients has largely been improved due to adjuvant... 相似文献
204.
Postnatal growth is an important life‐history trait that varies widely across avian species, and several equations with a sigmoidal shape have been used to model it. Classical three‐parameter models have an inflection point fixed at a percentage of the upper asymptote which could be an unrealistic assumption generating biased fits. The Richards model emerged as an interesting alternative because it includes an extra parameter that determines the location of the inflection point which can move freely along the growth curve. Recently, nonlinear mixed models (NLMM) have been used in modeling avian growth because these models can deal with a lack of independence among data as typically occurs with multiple measurements on the same individual or on groups of related individuals. Here, we evaluated the usefulness of von Bertalanffy, Gompertz, logistic, U4 and Richards's equations modeling chick growth in the imperial shag Phalacrocorax atriceps. We modelled growth in commonly used morphological traits, including body mass, bill length, head length and tarsus length, and compared the performance of models by using NLMM. Estimated adult size, age at maximum growth and maximum growth rates markedly differed across models. Overall, the most consistent performance in estimated adult size was obtained by the Richards model that showed deviations from mean adult size within 5%. Based on AICc values, the Richards equation was the best model for all traits analyzed. For tarsus length, both Richards and U4 models provided indistinguishable fits because the relative inflection value estimated from the Richards model was very close to that assumed by the U4 model. Our results highlight the bias incurred by three‐parameter models when the assumed inflection placement deviates from that derived from data. Thus, the application of the Richards equation using the NLMM framework represents a flexible and powerful tool for the analysis of avian growth. 相似文献
205.
Improved Detection of Citrus psorosis virus and Coat Protein‐Derived Transgenes in Citrus Plants: Comparison Between RT‐qPCR and TAS‐ELISA
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Agustina De Francesco Norma Costa María I. Plata María L. García 《Journal of Phytopathology》2015,163(11-12):915-925
Citrus is one of the most economically important fruit crops in the world. Citrus psorosis is a serious disease affecting mainly oranges and mandarins in Argentina and Uruguay. The causal agent is Citrus psorosis virus (CPsV), an ophiovirus with a tripartite ssRNA genome of negative polarity. The coat protein (CP), the most abundant viral protein in infected plants, has been used to detect CPsV by TAS‐ELISA, but only biological indexing, requiring 1 year, is the current and validated technique for diagnosis of citrus psorosis. In this study, a SYBR Green RT‐qPCR protocol was developed, with primers designed to the most conserved region of the cp gene. We tested their specificity and sensitivity in comparison with TAS‐ELISA. This RT‐qPCR was applied successfully to field samples from Argentina, to a variety of isolates from different countries maintained in the greenhouse, to young seedlings and old trees from a psorosis natural transmission plot, and to transgenic citrus expressing the cp gene of CPsV or a fragment thereof. This method allowed accurate quantification of viral titer and cp gene expression in transgenic plants, which could not be detected previously. The sensitivity and reliability of quantitative CPsV detection were improved with greater speed using commercial reagents, and the sensitivity was three orders of magnitude higher than that of TAS‐ELISA. All these data encourage its validation. 相似文献
206.
Agustina Novillo M. Fernanda Cuevas Agustina A Ojeda Ramiro J. A Ovejero Mosca Torres M. Eugenia Ricardo A Ojeda 《Acta theriologica》2017,62(3):219-227
Habitat partitioning is considered one of the main mechanisms of coexistence among small mammals. This is especially evident in arid environments where resources are particularly scarce. Habitat characteristics such as vegetation heterogeneity and complexity are expected to increase species coexistence, increasing the number of microhabitats that can be occupied by species with different requirements. The Andean foothills can be considered as an ecotone between the Monte and Altoandina phytogeographic provinces as they harbor species from both. Consequently more species are thought to coexist in this area. The objectives of this study were to assess the macro- and microhabitat selection of the small mammal assemblage inhabiting the Andean foothills during wet and dry season and to determine how animals segregate environmental resources to ensure their coexistence. We found that habitat selection occurs at both scales in the Andean foothills. Two species, Eligmodontia moreni and Phyllotis xanthophygus, were capable of distinguishing among macrohabitat types, whereas all species showed habitat selection at the microhabitat scale. We registered selection during both seasons, with some overlap of resource selection during the wet season and the greatest segregation of microhabitat resources during the dry season. Therefore, this work evidence that the assembly of small mammals is sensitive to habitat structure especially in dry seasons where resources are constraints due to arid conditions of Andean foothills. 相似文献
207.
Agustina P. Porrino Andrés S. Martínez José M. Villacide Maité Masciocchi 《Entomologia Experimentalis et Applicata》2024,172(1):50-57
Dispersal is a multifactorial process which may influence, among several others, population dynamics, inbreeding likelihood, and mate competition. For species that disperse by flight, many studies have suggested that life-history traits, such as body size or nutritional condition, could promote variation in flight capabilities and, consequently, on dispersal behavior. Eusocial hymenopterans are likely to experience high densities of related reproductive individuals near their nests, thus increasing probabilities of inbred matings and kin competition. Spatial segregation resulting from differences in flight capabilities of Vespula germanica (Fabricius) (Hymenoptera: Vespidae) nestmate drones could reduce interactions with kin, thus decrease inbreeding and kin competition. Our aim was to characterize, in the laboratory, flight capabilities of sibling drones and elucidate traits that could affect it, focusing on the relevance of carbohydrate intake (diets with different sugar concentration) during early adulthood. Our results indicate that in tethered flight mill assays, V. germanica drones have highly variable flight capabilities within and between nests, with most drones likely to remain relatively close to their nest of origin. The observed flight capabilities are affected by nutrition, with those individuals better nurtured (i.e., with higher nutritional index), flying farther distances. Additionally, diets with variable carbohydrate concentration provided during early adulthood did not affect flight capabilities (only those exposed to a carbohydrate-free diet had reduced flight distances and speeds), suggesting that nutrition during larval stages is determinant for flight. Our findings contribute to the understanding of the mechanisms underlying V. germanica drone dispersal behavior which, in turn, might influence inbreeding likelihood in the species. 相似文献
208.
Summary A twenty-four hour rhythm is described in the variations of mitotic activity, dry weight, and water content of the regenerating liver of mice hepatectomized about noon. These variables have their maximal value at the onset of the rest periods in the morning and their minimal values at the initiation of the body activity periods in the evening. The rhythm is well defined on the second day and is repeated on the third day on a higher level.We acknowledge the assistance of Mrs. R. Cavoura in performing the hepatectomies and that of Mrs. M. A. V. Albornoz in making the histologic slides.The present work was carried out with the help of grants from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and Liga Mendocina de Lucha contra el Cáncer. 相似文献
209.
210.