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51.
Ramos FP Araripe JR Urményi TP Silva R Cunha e Silva NL Leite Fontes CF da Silveira JF Rondinelli E 《Biochemical and biophysical research communications》2005,333(3):808-817
RAB proteins, which belong to the RAS superfamily, regulate exocytic and endocytic pathways of eukaryotic cells, controlling vesicle docking and fusion. Few RAB proteins have been identified in parasites. Molecular markers for cellular compartments are important to studies concerning about the protein traffic in Trypanosoma cruzi, the causal agent of Chagas disease. In this work, we describe the characterization of TcRABL4, the first RAB-like gene identified in T. cruzi (GenBank Accession No.: ), present as a single-copy gene. TcRABL4 contains all five consensus RAB motifs but lacks cysteine residues at the C terminus, which are essential to isoprenylation, an absolute prerequisite for membrane association of these proteins. TcRABL4 is a functional GTPase that is able to bind and hydrolyze GTP, and its gene is transcribed as a single 1.2 kb mRNA in epimastigotes. TcRABL4 appears to be differentially regulated in the three cell forms of the parasite, and the protein is not associated to membranes, unlike other RAB proteins. It is possible that TcRABL4 may be a member of a novel family of small GTPases. 相似文献
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55.
de Vasconcellos AP Nieto FB Crema LM Diehl LA de Almeida LM Prediger ME da Rocha ER Dalmaz C 《Neurochemical research》2006,31(9):1141-1151
This study evaluated the effects of chronic stress and lithium treatments on oxidative stress parameters in hippocampus, hypothalamus,
and frontal cortex. Adult male Wistar rats were divided into two groups: control and submitted to chronic variate stress,
and subdivided into treated or not with LiCl. After 40 days, rats were killed, and lipoperoxidation, production free radicals,
total antioxidant reactivity (TAR) levels, and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were
evaluated. The results showed that stress increased lipoperoxidation and that lithium decreased free radicals production in
hippocampus; both treatments increased TAR. In hypothalamus, lithium increased TAR and no effect was observed in the frontal
cortex. Stress increased SOD activity in hippocampus; while lithium increased GPx in hippocampus and SOD in hypothalamus.
We concluded that lithium presented antioxidant properties, but is not able to prevent oxidative damage induced by chronic
variate stress. 相似文献
56.
Noindorf L Rego FG Baura VA Monteiro RA Wassem R Cruz LM Rigo LU Souza EM Steffens MB Pedrosa FO Chubatsu LS 《Archives of microbiology》2006,185(1):55-62
Herbaspirillum seropedicae is an endophytic nitrogen-fixing bacterium that colonizes economically important grasses. In this organism, the amtB gene is co-transcribed with two other genes: glnK that codes for a PII-like protein and orf1 that codes for a probable periplasmatic protein of unknown function. The expression of the orf1glnKamtB operon is increased under nitrogen-limiting conditions and is dependent on NtrC. An amtB mutant failed to transport methylammonium. Post-translational control of nitrogenase was also partially impaired in this
mutant, since a complete switch-off of nitrogenase after ammonium addition was not observed. This result suggests that the
AmtB protein is involved in the signaling pathway for the reversible inactivation of nitrogenase in H. seropedicae. 相似文献
57.
Tolerance is the ability of a plant to regrow or reproduce following damage. While experimental studies typically measure
tolerance in response to the intensity of herbivory (i.e., the amount of leaf tissue removed in one attack), the impact of
how many times plants are attacked during a growing season (i.e., the frequency of damage) is virtually unexplored. Using
experimental defoliations that mimicked patterns of attack by leaf-cutter ants (Atta spp.), we examined how the frequency of herbivory influenced plant tolerance traits in six tree species in Brazil’s Cerrado.
For 2 years we quantified how monthly and quarterly damage influenced individual survivorship, relative growth rate, plant
architecture, flowering, and foliar chemistry. We found that the content of leaf nitrogen (N) increased among clipped individuals
of most species, suggesting that Atta influences the allocation of resources in damaged plants. Furthermore, our clipping treatments affected tree architecture
in ways thought to promote tolerance. However, none of our focal species exhibited a compensatory increase in growth (increment
in trunk diameter) in response to herbivory as relative growth rates were significantly lower in clipped than in unclipped
individuals. In addition, the probability of survival was much lower for clipped plants, and lower for plants clipped monthly
than those clipped quarterly. For plants that did survive, simulated herbivory dramatically reduced the probability of flowering.
Our results were similar across a phylogenetically distinct suite of species, suggesting a potential extendability of these
findings to other plant species in this system. 相似文献
58.
Mariza Abreu Miranda Renata Fabiane Jorge Tiossi Mariana Rosa da Silva Kelly Cristina Rodrigues Christian Collins Kuehn Luiz Gustavo Rodrigues Oliveira Sérgio Albuquerque James Dewey McChesney Claudio Manuel Lezama‐Davila Angelica Patricia Isaac‐Marquez Jairo Kenupp Bastos 《化学与生物多样性》2013,10(4):642-648
Leishmaniasis is an infection caused by a protozoan parasite of the genus Leishmania and is the second most prevalent parasitic protozoal disease after malaria in the world. We report the in vitro leishmanicidal activity on promastigote forms of Leishmania amazonensis and cytotoxicity, using LLCMK2 cells, of the glycoalkaloids from the fruits of Solanum lycocarpum, determined by colorimetric methods. The alkaloidic extract was obtained by acid‐base extraction; solamargine and solasonine were isolated by silica‐gel chromatography, followed by reversed‐phase HPLC final purification. The alkaloidic extract, solamargine, solasonine, as well as the equimolar mixture of the glycoalkaloids solamargine and solasonine displayed leishmanicidal activity against promastigote forms of L. amazonensis, whereas the aglycone solasodine was inactive. After 24 and 72 h of incubation, most of the samples showed lower cytotoxicities (IC50 6.5 to 124 μM ) as compared to leishmanicidal activity (IC50 1.1 to 23.6 μM ). The equimolar mixture solamargine/solasonine was the most active with an IC50 value of 1.1 μM , after 72 h. Likewise, solamargine was the most active after 24 h with an IC50 value of 14.4 μM , both in comparison with the positive control amphotericin B. 相似文献
59.
Corinna Wallinger Karin Staudacher Nikolaus Schallhart Eva Peter Philipp Dresch Anita Juen Michael Traugott 《Molecular ecology resources》2013,13(1):75-83
Plant roots represent an important food source for soil‐dwelling animals, but tracking herbivore food choices below‐ground is difficult. Here, we present an optimized PCR assay for the detection of plant DNA in the guts of invertebrates, using general plant primers targeting the trnT‐F chloroplast DNA region. Based on this assay, we assessed the influence of plant identity on the detectability of ingested plant DNA in Agriotes click beetle larvae. Six different plant species were fed to the insects, comprising a grass, a legume and four nonlegume forbs. Moreover, we examined whether it is possible to amplify DNA of decaying plants and if DNA of decayed plant food is detectable in the guts of the larvae. DNA of the ingested roots could be detected in the guts of the larvae for up to 72‐h post‐feeding, the maximum digestion time tested. When fed with living plants, DNA detection rates differed significantly between the plant species. This may be ascribed to differences in the amount of plant tissue consumed, root palatability, root morphology and/or secondary plant components. These findings indicate that plant identity can affect post‐feeding DNA detection success, which needs to be considered for the interpretation of molecularly derived feeding rates on plants. Amplification of plant DNA from decaying plants was possible as long as any tissue could be retrieved from the soil. The consumption of decaying plant tissue could also be verified by our assay, but the insects seemed to prefer fresh roots over decaying plant material. 相似文献
60.
M.C. Macedo T. Lucia G. Rambo E.B. Ferreira Filho A.P. Rosa C. Fabiane M. Cabral J.C. Deschamps 《Animal reproduction science》2010,117(3-4):295-301
In vitro penetration (IVP) of swine oocytes by homologous spermatozoa was evaluated in two experiments using four boars as semen donors. In experiment 1, the IVP rate and the number of penetrating spermatozoa (PSP) were compared using three co-incubation systems for vitrified oocytes and fresh sperm: (1) 35 mL petri dishes in a CO2 incubator, (2) 35 mL petri dishes in bags (submarine system) and (3) glass flasks partially submerged in water bath with the same gas mixture used for the bag system. Mean PSP was 8.2 ± 10.1 and the IVP rate was 90.5%. The PSP differed across all systems (P = 0.0006): 15.5 ± 0.5 for flasks, 6.3 ± 0.4 for CO2, and 3.9 ± 0.4 for bags. The IVP rate for flasks (95.0%) was greater (P = 0.01) than for CO2 and bags (90.8% and 85.0%, respectively), but it did not differ between flasks and CO2 for three boars (P > 0.05). In experiment 2, co-incubation was done as described for glass flasks in experiment 1. The IVP rate and PSP were compared for cryopreserved oocytes: either vitrified in open pulled straws (OPS), or frozen in cryotubes. Mean PSP was 5.4 ± 6.5 and IVP rate was 89.6%. Both PSP and IVP rate were greater (P < 0.0001) for oocytes frozen in cryotubes (7.0 ± 0.3% and 95.8%, respectively) than those frozen in OPS (3.7 ± 0.3% and 83.4%, respectively), with no differences found for three boars (P > 0.05). In summary, successful IVP of swine oocytes by homologous spermatozoa can be achieved using gametes incubated in glass flasks and oocytes frozen in cryotubes. 相似文献