MODIFICATIONS ON LEAF ANATOMY OF BANANA DURING THE MICROPROPAGATION PROCESS

The study and understanding of alterations taking place during the micropropagation process can provide valuable information about this technology. The objective of this work was to evaluate the anatomical modifications in leaves of micropropagated banana (Musa spp.) plants during their adaptation to ex vitro conditions. Aseptic axillary shoots of `Preciosa` cultivar (AAAB) were rooted for 24 days in MS medium containing NAA (1mg.l(-1)) and agar (6g.l(-1)), and acclimatized for 120 days. The treatments consisted of leaves at different stages of development: T1 - leaves from plants at the end of in vitro rooting phase, T2 persistent leaves from plants after 30 days of acclimatization, T3 - new leaves from plants after 30 days of acclimatization (transition leaves). T4 - transition leaves from plants after 60 days, T5 - new leaves from plants after 60 days of acclimatization, and T6 - new leaves from plants after 120 days of acclimatization. A higher degree of differentiation and, thereby, better adaptation took place in leaves from leaf primordial differentiated in ex vitro conditions. The acclimatization phase is crucial for a greater thickness and differentiation of spongy and palisade parenchyma, and to correct the modifications of plants developed in vitro. The study of leaf anatomy provides a better understanding of alterations occurring in micropropagated banana plants.

Variants of temporal defeasible logics for modelling norm modifications

This paper proposes some variants of Temporal Defeasible Logic (TDL) to reason about normative modifications. These variants make it possible to differentiate cases in which, for example, modifications at some time change legal rules but their conclusions persist afterwards from cases where also their conclusions are blocked.

Post translational modifications of recombinant human Papillomavirus type 6b major capsid protein

We have determined the post-translational modifications of the major capsid protein, L1 of human papillomavirus (HPV) type 6b. Since this virus cannot be cultured in the laboratory to obtain sufficient material for a study, a recombinant L1 protein produced in a vaccinia virus expression system was used in this investigation. Our results show that this protein is phosphorylated at serine residues and is also glycosylated. No myristoylation or palmitoylation was detected. The fraction of L1 protein incorporated into virus-like particles was not glycosylated. Since recombinant L1 protein is a potential human vaccine candidate, knowledge of the post-translation modifications of this protein may prove useful for the design of anti-HPV vaccines. (C) 1999 Elsevier Science B.V. All rights reserved.

On modifications to the long-term survival mixture model in the presence of competing risks

A mixture model for long-term survivors has been adopted in various fields such as biostatistics and criminology where some individuals may never experience the type of failure under study. It is directly applicable in situations where the only information available from follow-up on individuals who will never experience this type of failure is in the form of censored observations. In this paper, we consider a modification to the model so that it still applies in the case where during the follow-up period it becomes known that an individual will never experience failure from the cause of interest. Unless a model allows for this additional information, a consistent survival analysis will not be obtained. A partial maximum likelihood (ML) approach is proposed that preserves the simplicity of the long-term survival mixture model and provides consistent estimators of the quantities of interest. Some simulation experiments are performed to assess the efficiency of the partial ML approach relative to the full ML approach for survival in the presence of competing risks.

C-13-NMR, H-1-NMR, and FT-Raman study of radiation-induced modifications in radiation dosimetry polymer gels

H-1- and C-13-NMR spectroscopy and FT-Raman spectroscopy are used to investigate the properties of a polymer gel dosimeter post-irradiation. The polymer gel (PACT) is composed of acrylamide, N,N'-methylene-bisacrylamide, gelatin, and water. The formation of a polyacrylamide network within the gelatin matrix follows a dose dependence nonlinearly correlated to the disappearance of the double bonds from the dissolved monomers within the absorbed dose range of 0-50 Gy. The signal from the gelatin remains constant with irradiation. We show that the NMR spin-spin relaxation times (T-2) of PAGs irradiated to up to 50 Gy measured in a NMR spectrometer and a clinical magnetic resonance imaging scanner can be modeled using the spectroscopic intensity of the growing polymer network. More specifically, we show that the nonlinear T-2 dependence against dose can be understood in terms of the fraction of protons in three different proton pools. (C) 2000 John Wiley & Sons, Inc.

Posttranslational mechanisms associated with reduced NHE3 activity in adult vs. young prehypertensive SHR

Crajoinas RO, Lessa LMA, Carraro-Lacroix LR, Davel APC, Pacheco BPM, Rossoni LV, Malnic G, Girardi ACC. Posttranslational mechanisms associated with reduced NHE3 activity in adult vs. young prehypertensive SHR. Am J Physiol Renal Physiol 299:F872-F881, 2010. First published July 14, 2010; doi:10.1152/ajprenal.00654.2009.-Abnormalities in renal proximal tubular (PT) sodium transport play an important role in the pathophysiology of essential hypertension. The Na(+)/H(+) exchanger isoform 3 (NHE3) represents the major route for sodium entry across the apical membrane of renal PT cells. We therefore aimed to assess in vivo NHE3 transport activity and to define the molecular mechanisms underlying NHE3 regulation before and after development of hypertension in the spontaneously hypertensive rat (SHR). NHE3 function was measured as the rate of bicarbonate reabsorption by means of in vivo stationary microperfusion in PT from young prehypertensive SHR (Y-SHR; 5-wk-old), adult SHR (A-SHR; 14-wk-old), and age-matched Wistar Kyoto (WKY) rats. We found that NHE3-mediated PT bicarbonate reabsorption was reduced with age in the SHR (1.08 +/- 0.10 vs. 0.41 +/- 0.04 nmol/cm(2)xs), while it was increased in the transition from youth to adulthood in the WKY rat (0.59 +/- 0.05 vs. 1.26 +/- 0.11 nmol/cm(2)xs). Higher NHE3 activity in the Y-SHR compared with A-SHR was associated with a predominant microvilli confinement and a lower ratio of phosphorylated NHE3 at serine-552 to total NHE3 (P-NHE3/total). After development of hypertension, P-NHE3/total increased and NHE3 was retracted out of the microvillar microdomain along with the regulator dipeptidyl peptidase IV (DPPIV). Collectively, our data suggest that the PT is playing a role in adapting to the hypertension in the SHR. The molecular mechanisms of this adaptation possibly include an increase of P-NHE3/total and a redistribution of the NHE3-DPPIV complex from the body to the base of the PT microvilli, both predicted to decrease sodium reabsorption.

Technical modifications in stabilisers and in bar removal in the Nuss procedure

Pectus excavatum is a congenital deformity that can require surgical treatment. Since Nuss proposed a correction technique, several modifications have been proposed in order to achieve more safety and efficiency in the placement and removal of both bars. Our objective is to describe the technique of placing and removing the bars by proposing three technical modifications: two in bar placement and one in the bar removal. We describe two cases where Nuss bars were placed and one case where the bar was removed as per the technical modification proposed herein. According to the original technique, bar stabilisers. were placed close to the lateral bar edges. We propose a more medial position in order to reduce bar displacement. New stabilisers were designed with central grooves in the posterior surface, which allow better sliding. The technical modification suitable for bar removal was the use of a protective film around the bars to protect the surrounding tissues from the sharp edges, and thereby minimise the risk of injuries. All the proposed modifications were performed without any additional surgical risk or perioperative complication. These three technical modifications can be easily and safety performed, and seem to reduce the risk of bleeding with no additional perioperative complications. (C) 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

Evidences of a Role for Eukaryotic Translation Initiation Factor 5A (eIF5A) in Mouse Embryogenesis and Cell Differentiation

Eukaryotic translation initiation factor 5A (eIF5A) has a unique character: the presence of an unusual amino acid, hypusine, which is formed by post-translational modifications. Even before the identification of hypusination in eIF5A, the correlation between hypusine formation and protein synthesis, shifting cell proliferation rates, had already been observed. Embryogenesis is a complex process in which cellular proliferation and differentiation are intense. In spite of the fact that many studies have described possible functions for eIF5A, its precise role is under investigation, and to date nothing has been reported about its participation in embryonic development. In this study we show that eIF5A is expressed at all mouse embryonic post-implantation stages with increase in eIF5A mRNA and protein expression levels between embryonic days E10.5 and E13.5. Immunohistochemistry revealed the ubiquitous presence of eIF5A in embryonic tissues and organs at E13.5 day. Interestingly, stronger immunoreactivity to eIF5A was observed in the stomodeum, liver, ectoderm, heart, and eye, and the central nervous system; regions which are known to undergo active differentiation at this stage, suggesting a role of eIF5A in differentiation events. Expression analyses of MyoD, a myogenic transcription factor, revealed a significantly higher expression from day E12.5 on, both at the mRNA and the protein levels suggesting a possible correlation to eIF5A. Accordingly, we next evidenced that inhibiting eIF5A hypusination in mouse myoblast C2C12 cells impairs their differentiation into myotubes and decreases MyoD transcript levels. Those results point to a new functional role for eIF5A, relating it to embryogenesis, development, and cell differentiation. J. Cell. Physiol. 225: 500-505, 2010. (C) 2010 Wiley-Liss, Inc.

Proposed modifications to metabolic model for glycogen-accumulating organisms under anaerobic conditions

Filipe et al. (2001) proposed an anaerobic metabolic model for glycogen-accumulating organisms (GAO) in which the succinate-propionate pathway was used to describe the production of propionyl-CoA. However, propionyl-CoA is only an intermediate product in the above pathway. Stopping at propionyl-CoA instead of propionate (the end product of the pathway) results in the consumption of one ATP from succinate to succinyl-CoA, which was not accounted for in the model of Filipe et al. (2001). This resulted in significant errors in the stoichiometric coefficients in the final metabolic model. A modified model is presented in this communication and is shown to fit the experimental data significantly better than the original model. (C) 2002 Wiley Periodicals, Inc.

Structural, physical, and chemical modifications induced by microwave heating on native agar-like galactans

Native agars from Gracilaria vermiculophylla produced in sustainable aquaculture systems (IMTA) were extracted under conventional (TWE) and microwave (MAE) heating. The optimal extracts from both processes were compared in terms of their properties. The agars’ structure was further investigated through Fourier transform infrared and NMR spectroscopy. Both samples showed a regular structure with an identical backbone, β-D-galactose (G) and 3,6-anhydro-α-L-galactose (LA) units; a considerable degree of methylation was found at C6 of the G units and, to a lesser extent, at C2 of the LA residues. The methylation degree in the G units was lower for MAEopt agar; the sulfate content was also reduced. MAE led to higher agar recoveries with drastic extraction time and solvent volume reductions. Two times lower values of [η] and Mv obtained for the MAEopt sample indicate substantial depolymerization of the polysaccharide backbone; this was reflected in its gelling properties; yet it was clearly appropriate for commercial application in soft-texture food products.

Lipid extractions from marine deep-sea invertebrates : modifications to the Bligh & Dyer method to increase lipid yields

The deep-sea environment is difficult to sample, and often only small quantities of samples can be obtained when using less destructive methods than dredging. When working with marine animals that are difficult to sample and with limited quantities of tissue to extract lipids, it is essential to ensure that the used method extracts the maximum possible quantity of lipids. This study evaluates the efficiency of introducing modifications to the method originally described by Bligh & Dyer (1959). This lipid extraction method is broadly used with modifications, although these usually lack proper description and evaluation of increment in lipids. In this study we consider the improvement in terms of amount of lipids extracted by changing the method. Lipid content was determined by gravimetric measurements in eight invertebrates from the deep-sea, including deep-sea hydrothermal vents animals, using three different approaches. Results show increases of 14% to 30% in lipid contents obtained from hydrothermal vent invertebrate tissues and whole animals by placing the samples in methanol for 24 hours before applying the Bligh & Dyer mixture. Efficiency of the extractions using frozen and freeze-dried samples was also compared. For large sponges, the use of lyophilized materials resulted in increases of 3 to 7 times more lipids extracted when compared with extractions using frozen samples.

Long-term modifications of coastal defences enhance marine biodiversity

Realization that hard coastal infrastructures support lower biodiversity than natural habitats has prompted a wealth of research seeking to identify design enhancements offering ecological benefits. Some studies showed that artificial structures could be modified to increase levels of diversity. Most studies, however, only considered the short-term ecological effects of such modifications, even though reliance on results from short-term studies may lead to serious misjudgements in conservation. In this study, a sevenyear experiment examined how the addition of small pits to otherwise featureless seawalls may enhance the stocks of a highly-exploited limpet. Modified areas of the seawall supported enhanced stocks of limpets seven years after the addition of pits. Modified areas of the seawall also supported a community that differed in the abundance of littorinids, barnacles andmacroalgae compared to the controls. Responses to different treatments (numbers and size of pits) were speciesspecific and, while some species responded directly to differences among treatments, others might have responded indirectly via changes in the distribution of competing species. This type of habitat enhancement can have positive long-lasting effects on the ecology of urban seascapes.Understanding of species interactions could be used to develop a rule-based approach to enhance biodiversity.

Modifications of MCM-22 zeolite through sequential post-synthesis treatments. Implications on the acidic and catalytic behaviour

Desilication and a combination of alkaline followed by acid treatment were applied to MCM-22 zeolite using two different base concentrations. The samples were characterised by powder X-ray diffraction, Al-27 and Si-29 MAS-NMR spectroscopy, SEM, TEM and low temperature N-2 adsorption. The acidity of the samples was study through pyridine adsorption followed by FTIR spectroscopy and by the analyses of the hydroxyl region. The catalytic behaviour, anticipated by the effect of post-synthesis treatments on the acidity and space available inside the two internal pore systems was evaluated by using the model reaction of m-xylene transformation. The generation of mesoporosity was achieved upon alkaline treatment with 0.05 M NaOH solution and practically no additional gain was obtained when the more concentrate solution, 0.1 M, was used. Instead, Al extraction takes place along with Si, as shown by Si-29 and Al-27 MAS-NMR data, followed by Al deposition as extraframework species. Samples submitted to alkaline plus acid treatments present distinct behaviour. When the lowest NaOH solution was used no relevant effect was observed on the textural characteristics. Additionally, when the acid treatment was performed on an already fragilized MCM-22 structure, due to previous desilication with 0.1 M NaOH solution, the extraction of Al from both internal pore systems promotes their interconnection, evolving from a 2-D to a 3-D porous structure. This transformation has a marked effect in the catalytic behaviour, allowing an increase of m-xylene conversion as a consequence of an easier and faster molecular traffic in the 3-D structure. On the other hand, the continuous deposition of extraframework Al species inside the pores leads to a shape selective effect that privileges the formation of the more valuable isomer p-xylene.