Heterologous production of resveratrol in bacterial hosts: current status and perspectives.

The polyphenol resveratrol (3,5,4'-trihydroxystilbene) is a well-known plant secondary metabolite, commonly used as a medical ingredient and a nutritional supplement. Due to its health-promoting properties, the demand for resveratrol is expected to continue growing. This stilbene can be found in different plants, including grapes, berries (blackberries, blueberries and raspberries), peanuts and their derived food products, such as wine and juice. The commercially available resveratrol is usually extracted from plants, however this procedure has several drawbacks such as low concentration of the product of interest, seasonal variation, risk of plant diseases and product stability. Alternative production processes are being developed to enable the biotechnological production of resveratrol by genetically engineering several microbial hosts, such as Escherichia coli, Corynebacterium glutamicum, Lactococcus lactis, among others. However, these bacterial species are not able to naturally synthetize resveratrol and therefore genetic modifications have been performed. The application of emerging metabolic engineering offers new possibilities for strain and process optimization. This mini-review will discuss the recent progress on resveratrol biosynthesis in engineered bacteria, with a special focus on the metabolic engineering modifications, as well as the optimization of the production process. These strategies offer new tools to overcome the limitations and challenges for microbial production of resveratrol in industry.

The bone degenerative processes in senile fishes from Holocene Brazilian shell mounds.

Zooarchaeological collections from shell mounds in Rio de Janeiro (2,470-4,632 cal BP) contain a high prevalence of swollen fish bones belonging to the Atlantic spadefish (Chaetodipterus faber), crevalle jack (Caranx hippos) and fat snook (Centropomus parallelus). Given the lack of knowledge of the bone degenerative process in senile fishes, this study analysed hyperostotic bone in zooarchaeological and modern specimens to obtain high-resolution morphology and microstructure reconstruction. We used microCT as well as X-ray diffraction to characterize the crystallographic changes associated with fish senility. Our results showed that trabecular microstructures in hyperostotic bones were consistent with estimated values of the per cent bone volume-to-total volume ratio (BV/TV) and were greater than 60% in cortical bone. Hyperostotic bones indicated a high radiograph density, and X-ray diffractograms showed a decrease in hydroxyapatite [Ca10 (PO4 )6 (OH)2 ] and calcite (CaCO3 ) neocrystallization. These crystalline and density changes revealed an advanced stage of fish senile and indicate the vulnerability of ageing fish populations.

Myogenic oscillations in rabbit ocular vasculature are very low frequency.

BACKGROUND/AIMS: In a previously described model of isolated rabbit eye, we detected myogenic intrinsic vascular tone of unknown origin in the ophthalmic artery. In order to better understand the origin of these low frequency oscillations, we analyzed their spectral characteristics using fast Fourier. METHODS: Hybrid New Zealand rabbits of either sex (n = 24) were used; they were divided into 2 groups according to age. The spectral characteristics of the myogenic behaviour of the rabbit external ophthalmic artery were analyzed using the fast Fourier algorithm. RESULTS: The frequency of the oscillations of the myogenic activity seen in the rabbit external ophthalmic artery varied between 0.033 and 0.066 Hz (mean 0.045 ± 0.012 Hz), all in the region of very low frequency (VLF) oscillations (VLF <0.07 Hz for the rabbit). The frequency of spontaneous oscillations was higher in younger animals. CONCLUSION: Fast Fourier analysis proved to be an adequate mathematical tool to analyze the myogenic tone oscillations, which were all in the range of VLF in the model we used. These results indicate that myogenic vascular function of ocular blood flow is composed of VLF oscillations, and they provide a new explanation for the origin of VLF in arterial spectra. They also suggest that the ocular local myogenic vascular function observed is more efficient in younger animals.

Optimization of culture conditions to improve Helicobacter pylori growth in Ham's F-12 medium by response surface methodology.

Helicobacter pylori is a gastroduodenal pathogen that colonizes the human stomach and is the causal agent of gastric diseases. From the clinical and epidemiological point of view, enhancing and improving the growth of this bacterium in liquid media is an important goal to achieve in order to allow the performance of accurate physiological studies. The aim of this work was to optimize three culture conditions that influence the growth of H. pylori in the defined medium Ham s F-12 supplemented with 5 percent fetal bovine serum by using response surface methodology as a statistical technique to obtain the optimal conditions. The factors studied in this experimental design (Box-Behnken design) were the pH of the medium, the shaking speed (rpm) and the percentage of atmospheric oxygen, in a total of 17 experiments. The biomass specific growth rate was the response measured. The model was validated for pH and shaking speed. The percentage of atmospheric oxygen did not influence the growth for the range of values studied. At the optimal values found for pH and shaking speed, 8 and 130 rpm, respectively, a specific growth rate value of 0.164 h-1, corresponding to a maximal concentration of approximately 1.5x108 CFU/ml, was reached after 8 h. The experimental design strategy allowed, for the first time, the optimization of H. pylori growth in a semi-synthetic medium, which may be important to improve physiological and metabolic studies of this fastidious bacterium.

Evaluation of the effects of hyperbaric oxygen therapy for spinal cord lesion in correlation with the moment of intervention.

STUDY DESIGN: Experimental, controlled, animal study. OBJECTIVES: To evaluate the functional effect of hyperbaric oxygen therapy administered shortly, one day after, and no intervention (control) in standardized experimental spinal cord lesions in Wistar rats. SETTING: São Paulo, Brazil. METHODS: In all, 30 Wistar rats with spinal cord lesions were divided into three groups: one group was submitted to hyperbaric oxygen therapy beginning half an hour after the lesion and with a total of 10 one-hour sessions, one session per day, at 2 atm; the second received the same treatment, but beginning on the day after the lesion; and the third received no treatment (control). The Basso, Beattie and Bresnahan scales were used for functional evaluation on the second day after the lesion and then weekly, until being killed 1 month later. RESULTS: There were no significant differences between the groups in the functional analysis on the second day after the lesion. There was no functional difference comparing Groups 1 and 2 (treated shortly after or one day after) in any evaluation moment. On the 7th day, as well as on the 21st and 28th postoperative days, the evaluation showed that groups 1 and 2 performed significantly better than the control group (receiving no therapy). CONCLUSION: Hyperbaric chamber therapy is beneficial in the functional recovery of spinal cord lesions in rats, if it is first administered just after spinal cord injury or within 24 h.

Flower morphology and plant-bee pollinator interactions are related to stamen dimorphism in Melastomataceae.

Approximately 20,000 species of flowering plant offer mainly pollen to their pollinators, generally bees. Stamen dimorphism, a floral trait commonly present in some pollen flowers, is thought to be associated with exclusive pollen provision for highly effective bee pollinators. Notwithstanding, little is known about how stamen dimorphism is related to other floral morphological traits and, consequently, plant-pollinator interactions at the community scale. Here we investigated the relationship between stamen dimorphism and other floral morphological traits, as well as the interactions with pollinators in plants of Melastomataceae. We characterized each plant species as stamen dimorphic or stamen isomorphic according to differences in size and shape between stamen sets. Data on interactions between the plants and their bee pollinators were analysed as quantitative bipartite networks. We found that petal and style size and shape were correlated to stamen dimorphism. Stamen dimorphic species present larger flowers and less variable style shapes than stamen isomorphic species. Furthermore, stamen dimorphism is associated with higher richness of visiting bees, i.e. higher ecological generalization. During the evolutionary history of Melastomataceae, the dependence on pollinators for fruit set has possibly favoured the evolution of larger flowers with dimorphic stamens, which in turn are able to make use of a larger spectrum of pollen-collecting bees, leading to ecological generalization.

L-arginine and L-nitroarginine methylester effects on vasomotion in isolated rabbit eyes.

BACKGROUND/AIMS: Although nitric oxide (NO) has been shown to be essential for maintaining the basal blood flow in the retina and optic nerve head, its exact role in vasomotion is still controversial. This study investigated L-arginine (L-Arg) and N-nitro-L-arginine methylester (L-NAME) effects on vascular reactivity in a model of isolated rabbit eye. METHODS: Rabbit external ophthalmic arteries (n = 12) in a head-mounted preparation were cannulated and perfused with warmed Tyrode solution. The effect of intraluminal pressure as a measure of total vascular resistance was assessed. Response curves to intra-arterial injections of 3 growing concentrations of L-Arg (n = 6) and L-NAME (n = 6) were obtained. RESULTS: Without any drug administration, spontaneous oscillations were observed in all the models. L-Arg (NO precursor) induced vasodilation and decreased both frequency and amplitude of the periodic oscillations. L-NAME (NO synthase inhibitor) produced a strong vasoconstrictor tone and stimulated vasomotion, causing a faster rate of pulsatility. CONCLUSION: L-Arg and L-NAME acted as modulators of ocular vascular tone. L-Arg elicited vasodilation and decreased vasomotion while L-NAME produced a strong vasoconstrictor tone and caused a faster rate of pulsatility. These findings justify the need to investigate NO precursors and antagonists as possible alternative therapeutics in vascular eye diseases.

Antioxidative therapy in contusion spinal cord injury.

INTRODUCTION: Some studies have made use of the antioxidative capabilities of high doses of vitamins C and E with the aim of neutralizing the noxious effects of free radicals following spinal cord lesion. OBJECTIVES: To evaluate the effects of vitamins C and E, separately and together, on the functional performance of rats that were subjected to standardized spinal cord contusion. MATERIALS AND METHODS: Forty male Wistar rats were used, divided into four groups of 10 animals each. Group 3 received vitamin C 100 mg kg(-1) day(-1) intraperitoneally; Group 2 received vitamin E 100 mg kg(-1) day(-1) orally; Group 1 received vitamins C and E, at the same dosages; and Group 4 was the control. The vitamin therapy was administered for 1 month and then the animals were killed. A direct contusional injury was caused and functional evaluation was performed using the Basso, Beattie and Bresnahan rating scale. The rats were evaluated on the second postoperative day and weekly thereafter, until the end of the experiment. RESULTS: The results were evaluated by means of the one-tailed, non-paired and non-parametric Mann-Whitney test, comparing the groups two by two. No significant difference in functional performance was observed between the groups. CONCLUSION: The use of vitamins C and E in these rats did not improve their neurological performance. However, histopathological examination showed that the inflammatory response was less intense following administration of the combination of vitamins C and E.

Monitoring of fed-batch E. coli fermentations with software sensors.

Accurate monitoring and control of industrial bioprocess requires the knowledge of a great number of variables, being some of them not measurable with standard devices. To overcome this difficulty, software sensors can be used for on-line estimation of those variables and, therefore, its development is of paramount importance. An Asymptotic Observer was used for monitoring Escherichia coli fed-batch fermentations. Its performance was evaluated using simulated and experimental data. The results obtained showed that the observer was able to predict the biomass concentration profiles showing, however, less satisfactory results regarding the estimation of glucose and acetate concentrations. In comparison with the results obtained with an Extended Kalman Observer, the performance of the Asymptotic Observer in the fermentation monitoring was slightly better.

Leptoceridae (Insecta, Trichoptera) from Serra da Canastra Mountain Range, Southeast Brazil: Diversity, Distribution, and Description of Two New Species.

The Brazilian savanna, also known as Cerrado, is one of the world's biodiversity hotspots, covering about 22% of the country. Nevertheless, this region has been suffering an accelerated process of degradation due to the agribusiness expansion. This study contributes to increasing knowledge on the Leptoceridae fauna of the Serra da Canastra Mountains at the Minas Gerais State, Brazil. Herein, we illustrate and describe two new species of Leptoceridae, Notalina franciscana sp. nov. and Oecetis catagua sp. nov., and provide additional data on the richness and distribution of Leptoceridae species in the Parque Nacional da Serra da Canastra and surrounding areas. Furthermore, ten species are firstly recorded from Minas Gerais State, increasing the number of Leptoceridae species recorded in the state from 30 to 42.

Effect of stimulation of sublobule IX-b of the cerebellar vermis on cardiac function.

Activation of sublobule IX-b of the cerebellar vermis evokes hypotension, bradycardia and decrease of the phrenic nerve activity in the anesthetized animal. Cardiac performance during the isovolumic phases of systole and relaxation can be evaluated by dP/dtmax, Vpm, dP/dt/DP40 and tau, respectively. In the present study, we evaluated the changes on cardiac function evoked by the stimulation of sublobule IX-b. New Zealand white rabbits were anesthetized, paralyzed and artificially ventilated. A posterior craniotomy was made to reveal and stimulate the cerebellar uvula (4 s train; 50 Hz; 1 ms; 20 microA). The femoral artery and veins were cannulated and a Swan-Ganz catheter was advanced in the upper abdominal aorta to control afterload when inflating the balloon. The left ventricle was catheterized with a Millar catheter. Blood pressure, heart rate, left ventricular pressure were monitored. Results showed a significant decrease on sublobule IX-b stimulation of all the indices of systolic function and an increase of tau indicating a decrease in the speed of the relaxation. These data provide the first evidence of the influence of sublobule IX-b on cardiac function. They may contribute to the understanding of the origin the cardiovascular changes that were observed in two patients with vermian and paravermian hemorrhage.

Gabapentin decreases microglial cells and reverses bilateral hyperalgesia and allodynia in rats with chronic myositis.

In the present work, we investigated the antinociceptive effect of gabapentin in a chronic myositis model and its interference in spinal glial cells. Chronic myositis was induced by injection of Complete Freund Adjuvant (CFA) into the right gastrocnemius (GS) muscle of rats and tests for evaluating mechanical hyperalgesia, thermal hyperalgesia and tactile allodynia were performed. Pharmacological treatment with gabapentin was administrated intrathecally and 100µg and 200µg doses were tested. For analyzing astrocytes and microglia in the spinal cord, immunochemistry assay was performed. It was found that gabapentin 200µg reverted CFA-induced chronic muscle pain bilaterally, in all applied tests and it was able to attenuate microglial but not astrocytes activation in the dorsal horn of spinal cord. In conclusion, gabapentin was able to inhibit hyperalgesia and allodynia in chronic myositis and also to attenuate spinal microglial activation. Therefore, gabapentin could be used as treatment for targeting chronic muscle pain.

Expression of Kir4.1 and Kir5.1 inwardly rectifying potassium channels in oligodendrocytes, the myelinating cells of the CNS.

The inwardly rectifying K+ channel subtype Kir5.1 is only functional as a heteromeric channel with Kir4.1. In the CNS, Kir4.1 is localised to astrocytes and is the molecular basis of their strongly negative membrane potential. Oligodendrocytes are the specialised myelinating glia of the CNS and their resting membrane potential provides the driving force for ion and water transport that is essential for myelination. However, little is known about the ion channel profile of mature myelinating oligodendrocytes. Here, we identify for the first time colocalization of Kir5.1 with Kir4.1 in oligodendrocytes in white matter. Immunolocalization with membrane-bound Na+/K+-ATPase and western blot of the plasma membrane fraction of the optic nerve, a typical CNS white matter tract containing axons and the oligodendrocytes that myelinate them, demonstrates that Kir4.1 and Kir5.1 are colocalized on oligodendrocyte cell membranes. Co-immunoprecipitation provides evidence that oligodendrocytes and astrocytes express a combination of homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels. Genetic knock-out and shRNA to ablate Kir4.1 indicates plasmalemmal expression of Kir5.1 in glia is largely dependent on Kir4.1 and the plasmalemmal anchoring protein PSD-95. The results demonstrate that, in addition to astrocytes, oligodendrocytes express both homomeric Kir4.1 and heteromeric Kir4.1/Kir5.1 channels. In astrocytes, these channels are essential to their key functions of K+ uptake and CO2/H+ chemosensation. We propose Kir4.1/Kir5.1 channels have equivalent functions in oligodendrocytes, maintaining myelin integrity in the face of large ionic shifts associated with action potential propagation along myelinated axons.

Antiviral Activity of Ctn[15-34], A Cathelicidin-Derived Eicosapeptide, Against Infectious Myonecrosis Virus in Litopenaeus vannamei Primary Hemocyte Cultures.

The shrimp farming has been converted into a mature aquaculture industry dealing with over millions of metric tonnes of processed commodities. Nevertheless, the global shrimp productions are constantly threatened by disease outbreaks, mainly triggered by rapidly disseminating viruses. Infectious myonecrosis virus (IMNV) is one of these epizootic agents affecting shrimp production in Brazil, of which no treatment exists. Herein, the antiviral activity against IMNV of an eicosapeptide, named Ctn[15-34], derived from a member of the cathelicidin family of antimicrobial peptides, was demonstrated. Cultures of hemocytes from Litopenaeus vannamei were established that support IMNV replication and infectivity titration. The cytotoxic effect of IMNV in culture and the in vitro anti-IMNV activity of Ctn[15-34] were assessed using a high-sensitive fluorescent-based method in combination with quantitative PCR. The Ctn[15-34] (<12.5 µM) neutralized the toxic effects of IMNV at loads sufficient to kill 50% of shrimp hemocytes. This study reported for the first time the replication of IMNV in vitro and the employment of a straightforward methodology to assess cell viability and viral/antiviral activities. In addition, it provided the basis for the development of the anti-infective multi-effector Ctn[15-34] eicosapeptide and analogs as components of antiviral formulations against shrimp viral diseases.

Molecular characterization and crystallization of Diocleinae lectins.

Molecular characterization of seven Diocleinae lectins was assessed by sequence analysis, determination of molecular masses by mass spectrometry, and analytical ultracentrifugation equilibrium sedimentation. The lectins show distinct pH-dependent dimer-tetramer equilibria, which we hypothesize are due to small primary structure differences at key positions. Lectins from Dioclea guianensis, Dioclea virgata, and Cratylia floribunda seeds have been crystallized and preliminary X-ray diffraction analyses are reported.

Early measles vaccination in bone marrow transplant recipients.

Measles vaccination has been recommended after the second year following bone marrow transplant (BMT) in patients not receiving immunosuppressive drugs. During a measles outbreak, we vaccinated all patients after the first year of transplant, and conducted a prospective trial to evaluate safety, effectiveness and sustained immunity after early vaccination. Patients received attenuated virus vaccine between 9 and 18 months after BMT. A total of 51 patients were evaluated and 27 of them (52.9%) were receiving immunosuppressive drugs. Only mild adverse reactions were noted. Nine patients (17.6%) were susceptible (IgG< or =100 mIU/ml) at vaccination, and all seroconverted. In those immune at vaccination, a four-fold increase in measles IgG titers was found in one of 34 patients (2.9%) with specific IgG> or =200 mIU/ml compared to 14 of 17 (82.3%) with IgG<200 mIU/ml (P< 0.0001). Sustained immunity after 24 months was more likely to occur in patients with specific IgG levels< or =200 or > or =500 mIU/mL (83.4 and 100%, respectively) in comparison to patients with 200

The benefit of influenza vaccination after bone marrow transplantation.

Influenza vaccine is recommended yearly for recipients after the sixth month of BMT. Although a higher risk of complications of influenza is expected to occur in BMT patients, no study has addressed the clinical efficacy of influenza vaccination in this setting. Focusing on the clinical benefits of influenza vaccination, we evaluated the risk factors for influenza infection in a cohort of 177 BMT recipients followed up for 1 year. Influenza was diagnosed in 39 patients. Multivariate analyses showed that seasonal exposure and more aggressive conditioning regimens were independently associated with increased risk for influenza. Influenza vaccination and steroid use showed a protective role. Of the 43 patients who had received BMT longer than 6 months, 19 were vaccinated (compliance rate = 44.2%) and vaccine efficacy was 80%. We conclude that influenza vaccination plays an important role in protecting BMT recipients against influenza and all efforts should be made to ensure good compliance with vaccination.

Development and application of efficient pathway enumeration algorithms for metabolic engineering applications.

Metabolic Engineering (ME) aims to design microbial cell factories towards the production of valuable compounds. In this endeavor, one important task relates to the search for the most suitable heterologous pathway(s) to add to the selected host. Different algorithms have been developed in the past towards this goal, following distinct approaches spanning constraint-based modeling, graph-based methods and knowledge-based systems based on chemical rules. While some of these methods search for pathways optimizing specific objective functions, here the focus will be on methods that address the enumeration of pathways that are able to convert a set of source compounds into desired targets and their posterior evaluation according to different criteria. Two pathway enumeration algorithms based on (hyper)graph-based representations are selected as the most promising ones and are analyzed in more detail: the Solution Structure Generation and the Find Path algorithms. Their capabilities and limitations are evaluated when designing novel heterologous pathways, by applying these methods on three case studies of synthetic ME related to the production of non-native compounds in E. coli and S. cerevisiae: 1-butanol, curcumin and vanillin. Some targeted improvements are implemented, extending both methods to address limitations identified that impair their scalability, improving their ability to extract potential pathways over large-scale databases. In all case-studies, the algorithms were able to find already described pathways for the production of the target compounds, but also alternative pathways that can represent novel ME solutions after further evaluation.

Late vagal inhibition in neurons of the ventrolateral medulla oblongata in the rat.

Stimulation of cervical vagal afferents elicits long-lasting inhibitory effects in a variety of neuronal populations, although little is known concerning the cellular mechanisms that are involved in these effects. In the present study, the electrophysiological characteristics of responses elicited by cumulative activation of vagal afferents were examined in neurons of the rostral ventrolateral medulla oblongata, which play an important role in the coordination of cardiovascular and other visceral activities. The study has focused on the late-onset, slow inhibitory component of vagal responses, which is likely to affect the temporal modulation of postsynaptic effects. Vagal stimulation elicited four distinct response patterns in intracellularly penetrated neurons (n = 78): excitation, inhibition, excitation-inhibition and inhibition-inhibition. The late inhibitory component was encountered in 43 (55%) of the cells, including five putative medullospinal neurons. It was due to a postsynaptic hyperpolarization which reversed at potentials more negative than -83 mV. The voltage dependency, as well as the average onset latency (93+/-3.0 ms), duration (270+/-16.5 ms) and amplitude (1.3+/-0.2 mV as measured at resting membrane potentials), of late inhibition were clearly different from those of the short-latency inhibitory response. The differences in the voltage dependency and time-course of the short-latency responses and the late inhibition indicate that they are mediated by different central relays. In the majority of neurons, late inhibition could be elicited by stimulating only myelinated vagal afferents. The magnitude of the response was, however, significantly enhanced in 63% of the examined cells when the intensity of stimulation was raised to recruit further myelinated and non-myelinated fibres. This indicates that late vagal inhibition is often elicited by a cumulative activation of convergent afferent inputs. The intracellularly labelled vagally responsive neurons were present at all rostrocaudal levels of the rostral ventrolateral medulla, with an accumulation in the region of the lateral paragigantocellular nucleus. Neurons that exhibited late vagal inhibition were dominant in the juxtafacial region of this nucleus. Due to its slow time-course, late vagal inhibition may contribute to a tonic modulation of the activity of neurons in the rostral ventrolateral medulla oblongata. It is proposed that late vagal inhibition plays an important role in the temporal integration of sensory inputs in neurons of the rostral ventrolateral medulla oblongata. The time-course and strength of this modulatory effect are related to the level of activity in those visceral sensory inputs that converge onto the inhibitory interneurons that mediate late inhibition to rostral ventrolateral medulla oblongata neurons.