381 research outputs found
In vitro clonal behavior of Olea europaea L., variety Galega vulgar
A multiplicação clonal da cultivar de oliveira Galega vulgar por estacaria semi-lenhosa,
é impedida pelas baixas taxas de enraizamento, as quais, segundo alguns autores, não
ultrapassam os 10%, originando assim desequilíbrios entre a procura e a oferta bem
como preços de mercado mais elevados face a outras cultivares de fácil enraizamento.
A micropropagação por rebentação axilar surge como uma técnica alternativa de
clonagem, por originar rejuvenescimento das plantas e taxas de enraizamento in vitro
próximas ou iguais a 100%. Utilizando estacas de árvores adultas do pomar clonal de
Galega vulgar existente na ESAS, anterior e parcialmente caracterizado por outras
Instituições para a) presença de vírus; b) taxas de enraizamento; c) rendimento em
azeite, introduziram-se aleatoriamente 39 clones in vitro, existindo actualmente 15
clones in vitro. Sendo raras as publicações sobre estudos de diferenças clonais no
comportamento in vitro na oliveira e noutras espécies, este trabalho apresenta os
resultados obtidos nos estudos efectuados desde 2003 para 15 clones, respeitantes à
1) introdução de material vegetal; 2) controlo de bacterioses sistémicas; 3)
caracterização da variação interclonal nas taxas de multiplicação, enraizamento e
aclimatação.Clonal multiplication of olive variety Galega vulgar trough leafy steam cuttings is
impeded by low rooting rates, according to some authors do not overcome 10% of
success. Those situations originates imbalances between plant offer and market
demand as well as higher prices of plants face others varieties. Micropropagation
trough adventitious multiplication is a technical proceeding able for cloning
recalcitrant woody plants. Trough rejuvenation of plants, rates of 100% in rooting is
achieved. Using cuttings from adult trees of a clonal orchard of Galega vulgar in ESAS,
previously and partially characterized for a) presence of virus; b) rooting rates of
cuttings; c) olive oil yield, 39 clones where randomly introduced in vitro for an actual
collection of 15 in vitro clones. Published papers concerning in vitro clonal behavior for olive or other species are rare, thus, this work presents the obtained results since 2003
for 1) introduction of clones; 2) systemic bacterioses control; 3) clonal variation in
multiplication, rooting and acclimatizatio
p53 Interaction with JMJD3 Results in Its Nuclear Distribution during Mouse Neural Stem Cell Differentiation
Conserved elements of apoptosis are also integral components of cellular differentiation. In this regard, p53 is involved in neurogenesis, being required for neurite outgrowth in primary neurons and for axonal regeneration in mice. Interestingly, demethylases regulate p53 activity and its interaction with co-activators by acting on non-histone proteins. In addition, the histone H3 lysine 27-specific demethylase JMJD3 induces ARF expression, thereby stabilizing p53 in mouse embryonic fibroblasts. We hypothesized that p53 interacts with key regulators of neurogenesis to redirect stem cells to differentiation, as an alternative to cell death. Specifically, we investigated the potential cross-talk between p53 and JMJD3 during mouse neural stem cell (NSC) differentiation. Our results demonstrated that JMJD3 mRNA and protein levels were increased early in mouse NSC differentiation, when JMJD3 activity was readily detected. Importantly, modulation of JMJD3 in NSCs resulted in changes of total p53 protein, coincident with increased ARF mRNA and protein expression. ChIP analysis revealed that JMJD3 was present at the promoter and exon 1 regions of ARF during neural differentiation, although without changes in H3K27me3. Immunoprecipitation assays demonstrated a direct interaction between p53 and JMJD3, independent of the C-terminal region of JMJD3, and modulation of p53 methylation by JMJD3-demethylase activity. Finally, transfection of mutant JMJD3 showed that the demethylase activity of JMJD3 was crucial in regulating p53 cellular distribution and function. In conclusion, JMJD3 induces p53 stabilization in mouse NSCs through ARF-dependent mechanisms, directly interacts with p53 and, importantly, causes nuclear accumulation of p53. This suggests that JMJD3 and p53 act in a common pathway during neurogenesis
Analysis of the seismic performance of a two storey log house
The dearth of knowledge on the load resistance mechanisms of log houses and the need for developing numerical models that are capable of simulating the actual behaviour of these structures has pushed efforts to research the relatively unexplored aspects of log house construction. The aim of the research that is presented in this paper is to build a working model of a log house that will contribute toward understanding the behaviour of these structures under seismic loading. The paper presents the results of a series of shaking table tests conducted on a log house and goes on to develop a numerical model of the tested house. The finite element model has been created in SAP2000 and validated against the experimental
results. The modelling assumptions and the difficulties involved in the process have been described and,
finally, a discussion on the effects of the variation of different physical and material parameters on the
results yielded by the model has been drawn up.The research leading to these results has received funding from the European Union‘s Seventh Framework Programme [FP7/2007-2013] under grant agreement n°227887 (SERIES)
Three little pieces for computer and relativity
Numerical relativity has made big strides over the last decade. A number of
problems that have plagued the field for years have now been mostly solved.
This progress has transformed numerical relativity into a powerful tool to
explore fundamental problems in physics and astrophysics, and I present here
three representative examples. These "three little pieces" reflect a personal
choice and describe work that I am particularly familiar with. However, many
more examples could be made.Comment: 42 pages, 11 figures. Plenary talk at "Relativity and Gravitation:
100 Years after Einstein in Prague", June 25 - 29, 2012, Prague, Czech
Republic. To appear in the Proceedings (Edition Open Access). Collects
results appeared in journal articles [72,73, 122-124
Comparison in the Trichoderma longibrachiatum xyloglucanase production using tamarind (Tamarindus indica) and jatobá (Hymenaea courbaril) seeds: factorial design and immobilization on ionic supports
in the control of the stretching and expansion of the plant cell wall. There are five types of enzymes known to be capable of cleaving the linear chain of xyloglucan, the most famous of them being the xyloglucanase (XEG). The immobilization can be used to solve problems related to stability, besides the economic benefits brought by the possibility of repeated use and recovery, decreasing the costs of production. Therefore, this study aims the optimization of the production of a xyloglucanase from Trichoderma longibrachiatum, with the aid of factorial design, using tamarind (Tamarindus indica) and jatobá (Hymenaea courbaril) seeds as carbon source; and the immobilization of the enzyme on ionic supports, such as MANAE (monoamino-N-aminoethyl), DEAE (diethylaminoethyl)-cellulose, CM (carboxymethyl)-cellulose and PEI (polyethyleneimine). High concentrations of carbon source in the culture medium, especially tamarind seeds, were the most favorable conditions for the greater activity of the xyloglucanase from T. longibrachiatum. The scaling up from Erlenmeyer flasks to the bioreactor was an essential strategy to increase the content of secreted enzyme. Regarding the biochemical characterization of the crude extract, the optimal temperature was 50-55 °C and the optimal pH 5.0.
Regarding the stabilities to pH and to temperature, the enzyme was not stable for prolonged periods, which was crucial for the performing of immobilization on ionic resins (CM-cellulose, DEAE-cellulose, MANAE, and PEI), being the first time described in literature the immobilization of a xyloglucanase on these supports.We thank the Fundação de Amparo à Pesquisa do estado de São Paulo (process 2018/07522-6; 2014/50884-5), and Conselho Nacional de Dsenvolvimento Científico (process 301963/2017-7; 465319/2014-9).info:eu-repo/semantics/publishedVersio
Low-Weight Primes for Lightweight Elliptic Curve Cryptography on 8-bit AVR Processors
Small 8-bit RISC processors and micro-controllers based on the AVR instruction set architecture are widely used in the embedded domain with applications ranging from smartcards over control systems to wireless sensor nodes. Many of these applications require asymmetric encryption or authentication, which has spurred a body of research into implementation aspects of Elliptic Curve Cryptography (ECC) on the AVR platform. In this paper, we study the suitability of a special class of finite fields, the so-called Optimal Prime Fields (OPFs), for a "lightweight" implementation of ECC with a view towards high performance and security. An OPF is a finite field Fp defined by a prime of the form p = u*2^k + v, whereby both u and v are "small" (in relation to 2^k) so that they fit into one or two registers of an AVR processor. OPFs have a low Hamming weight, which allows for a very efficient implementation of the modular reduction since only the non-zero words of p need to be processed. We describe a special variant of Montgomery multiplication for OPFs that does not execute any input-dependent conditional statements (e.g. branch instructions) and is, hence, resistant against certain side-channel attacks. When executed on an Atmel ATmega processor, a multiplication in a 160-bit OPF takes just 3237 cycles, which compares favorably with other implementations of 160-bit modular multiplication on an 8-bit processor. We also describe a performance-optimized and a security-optimized implementation of elliptic curve scalar multiplication over OPFs. The former uses a GLV curve and executes in 4.19M cycles (over a 160-bit OPF), while the latter is based on a Montgomery curve and has an execution time of approximately 5.93M cycles. Both results improve the state-of-the-art in lightweight ECC on 8-bit processors
Middle Segment Pancreatectomy: A Useful Tool in the Management of Pancreatic Neoplasms
Small, benign, or low-grade malignant tumors located in the neck of the pancreas are usually treated with enucleation. However, if enucleation is too risky because of possible damage of the main pancreatic duct, standard pancreatic resections are performed. Such operations can lead to impaired long-term exocrine–endocrine function. Middle segment pancreatectomy consists of a limited resection of the midportion of the pancreas and can be performed in selected patients affected by tumors of the pancreatic neck. Middle segment pancreatectomy is a safe and feasible procedure for treating tumors of the pancreatic neck; in experienced hands it is associated with no mortality but with high morbidity, even if the rate of “clinical” pancreatic fistula is about 20%. Moreover, it allows a surgeon to preserve pancreatic parenchyma and consequently long-term endocrine and exocrine pancreatic function
Cultivares de milho para o nordeste brasileiro: ensaios realizados no ano de 1997.
bitstream/item/79807/1/CPATC-COM.-TEC.-15-98.pd
Moxifloxacin enhances antiproliferative and apoptotic effects of etoposide but inhibits its proinflammatory effects in THP-1 and Jurkat cells
Etoposide (VP-16) is a topoisomerase II (topo II) inhibitor chemotherapeutic agent. Studies indicate that VP-16 enhances proinflammatory cytokines secretion from tumour cells, including IL-8, a chemokine associated with proangiogenic effects. Fluoroquinolones inhibit topo II activity in eukaryotic cells by a mechanism different from that of VP-16. The fluoroquinolone moxifloxacin (MXF) has pronounced anti-inflammatory effects in vitro and in vivo. We studied the effects of MXF and VP-16 on purified human topo II activity and further analysed their combined activity on proliferation, apoptosis and caspase-3 activity in THP-1 and Jurkat cells. Moxifloxacin alone slightly inhibited the activity of human topo II; however, in combination with VP-16 it led to a 73% reduction in enzyme activity. VP-16 inhibited cell proliferation in a time and dose-dependent manner. The addition of moxifloxacin for 72 h to low-dose VP-16 doubled its cytotoxic effect in THP-1 and Jurkat cells (1.8- and 2.6-fold decrease in cell proliferation, respectively) (P<0.004). Moxifloxacin given alone did not induce apoptosis but enhanced VP-16-induced apoptosis in THP-1 and Jurkat cells (1.8- and two-fold increase in annexin V positive cells and caspase-3 activity, respectively) (P<0.04). VP-16 induced the release of IL-8 in a time and dose-dependent manner from THP-1 cells. Moxifloxacin completely blocked the enhanced release of IL-8 induced by 0.5 and 1 μg ml−1 VP-16, and decreased IL-8 release from cells incubated for 72 h with 3 μg ml−1 VP-16 (P<0.001). VP-16 enhanced the release of IL-1β and TNF-α from THP-1 cells, whereas the addition of MXF prevented the enhanced cytokine secretion (P<0.001). We conclude that MXF significantly enhances VP-16 cytotoxicity in tumour-derived cells while preventing VP-16-induced proinflammatory cytokine release. This unique combination may have clinical benefits and cytotoxic drug ‘sparing effect' and should be further studied in vivo
Basal forebrain atrophy along the Alzheimer's disease continuum in adults with Down syndrome
Background: Basal forebrain (BF) degeneration occurs in Down syndrome (DS)-associated Alzheimer's disease (AD). However, the dynamics of BF atrophy with age and disease progression, its impact on cognition, and its relationship with AD biomarkers have not been studied in DS. Methods: We included 234 adults with DS (150 asymptomatic, 38 prodromal AD, and 46 AD dementia) and 147 euploid controls. BF volumes were extracted from T-weighted magnetic resonance images using a stereotactic atlas in SPM12. We assessed BF volume changes with age and along the clinical AD continuum and their relationship to cognitive performance, cerebrospinal fluid (CSF) and plasma amyloid/tau/neurodegeneration biomarkers, and hippocampal volume. Results: In DS, BF volumes decreased with age and along the clinical AD continuum and significantly correlated with amyloid, tau, and neurofilament light chain changes in CSF and plasma, hippocampal volume, and cognitive performance. Discussion: BF atrophy is a potentially valuable neuroimaging biomarker of AD-related cholinergic neurodegeneration in DS
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