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.

Autonomic and cardiac evaluation upon sub-therapeutic doxorubicin administration

 

Doxorubicin (DOX) is a chemotherapeutic agent that improves the survival and quality of life of patients with solid tumours. However, these improvements are counterbalanced by various dose-dependent side effects including cardiac dysfunction, which may occur in a subset of patients leading to treatment discontinuation. In addition, despite overall insufficiently studied, available data clearly show that women are more susceptible to drugs toxicity due to sex differences in drug metabolism or sensitivity. Regarding doxorubicin, apart its acute toxicity, women are also more vulnerable to late cardiotoxicity. Currently, there are no robust clinical imaging techniques or biomarkers available to detect DOX-cardiotoxicity before functional decline and, despite treatment personalization, subclinical signs of toxicity are not yet well identified.

Thus, in the present work, we sought to characterize the toxic effects of a sub-therapeutic dose of doxorubicin upon cardiovascular and autonomic function. For that, adult healthy female wistar rats (n=14), aged >3 months, were intraperitoneally treated with doxorubicin (2 mg/kg) at weekly intervals for up to 4 weeks. A control (Ctrl, n=7) group received saline solution 0,9% NaCl as a vehicle. Rats underwent an echocardiographic evaluation at 4 weeks. Blood pressure, heart rate and respiratory frequency were assessed in an acute experiment. Cardiovascular variability studies in the time-frequency domain (LF, HF and LF/HF calculation) and cardiorespiratory reflexes assessment were performed. T-Student test for paired observations was applied (level significance p<0.05)

DOX-treated animals showed a severe bradypnea and hypotension, significant decrease in ejection fraction and fractional shortening, sympatho-inhibition and reduced baroreceptor reflex gain and chemoreflex sensitivity. Our functional results might be due to cellular respiratory dysfunction and vascular adaptations induced by doxorubicin via TNF alpha actions at central nervous system (CNS) and peripheral level.

In fact, peripheral TNF alpha release elicits NO production, which through vasodilation will induce hypotension and baroreceptor reflex adjustments. Reinforcing these actions, and despite doxorubicin low ability to pass BBB, TNF alpha acting at CNS induces neuronal apoptosis and impairment of mitochondrial function which might also contribute to affect autonomic and respiratory function, expressed by a decreased chemoreflex sensitivity and sympathetic tone.

In conclusion, sub-therapeutic doses of doxorubicin are able to produce per se the impairment of autonomic and cardiac functions. Thus, a tight monitoring of these functions in patients treated with therapeutic doses of doxorubicin is highly recommended.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fundação para a Ciência e a Tecnologia

Encapsulation of Pseudomonas libanensis in alginate beads to sustain bacterial viability and inoculation of Vigna unguiculata under drought stress

Conventional agricultural practices based on the application of synthetic fertilizers are increasingly considered as unsustainable. Under a forecasted scenario of drought for the next decades, there is a global demand for innovative and sustainable approaches to ameliorate plant performance. Here, encapsulating beneficial microbes (BMs) to promote plant growth is gaining attention. This study evaluates bacterial encapsulation using polymeric beads of alginate, testing the survival of Pseudomonas libanensis TR1 stored up to 90 days. Produced beads were subjected to different treatments (fresh, air-dried and pulverized), which resulted in a variable size range (1200-860 µm). After storage, bacterial viability was maintained, and air-dried beads displayed a higher number of colony-forming units (2 × 107). Then, a glasshouse experiment investigated the drought resistance (plant growth, biomass, and photosynthetic responses) of Vigna unguiculata plants inoculated with these alginate beads. After 10 days of complete water restriction, turgidity and relative water content of V. unguiculata were still high under drought stress (> 80%). Leaf and root growth and biomass did not evidence significant changes after water restriction even after P. libanensis inoculation. Plant photosynthetic parameters (stomatal conductance, net photosynthetic rate, leaf CO2 concentration, or F v'/F m') were slightly affected due to inoculation but the level of stress-induced minimal plant responses. In our experiment, water restriction might have been insufficient to downregulate photosynthetic efficiency and reduce plant growth, limiting our understanding of the role of P. libanensis inoculation in alleviating drought stress in V. unguiculata, but highlighting the important relationship between the stress level and agricultural benefits of using encapsulated BMs.

Measuring Mental Health Literacy : Adaptation and Validation of the Portuguese Version of the Mental Health Literacy Scale (MHLS)

Understanding mental health literacy is essential for promoting empowerment and proactivity in patients, reducing stigma, and increasing population awareness. The constitutive dimensions of mental health literacy are still being researched, and instruments’ research can shed light on the involved processes. The Mental Health Literacy Scale (MHLS) is a self-report measure of mental health literacy. This study aimed to adapt the MHLS to Portuguese and evaluate mental health literacy in a broad sample. A broad sample of 337 individuals participated in the adaptation. Besides filling out the MHLS, the participants were invited to fill out a general lifestyle measure. The global results reveal a good internal consistency of the MHLS. A three-factor structure (i.e., attitudes towards mental illness, knowledge about mental illness, and the ability to recognize symptoms) explained 35% of the total variance. Despite not finding an association with the general lifestyle measure, the MHLS scored higher in women and individuals with higher schooling, as expected. The results reinforce the role of MHLS as a useful measure of mental health literacy. The identified structure is discussed in light of the current understanding and implications of this essential process.

Using microbial seed coating for improving cowpea productivity under a low-input agricultural system

BACKGROUND

Plant-growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal (AM) fungi have the ability to enhance the growth, fitness, and quality of various agricultural crops, including cowpea. However, field trials confirming the benefits of microbes in large-scale applications using economically viable and efficient inoculation methods are still scarce. Microbial seed coating has a great potential for large-scale agriculture through the application of reduced amounts of PGPR and AM fungi inocula. Thus, in this study, the impact of seed coating with PGPR, Pseudomonas libanensis TR1 and AM fungus, Rhizophagus irregularis (single or multiple isolates) on grain yield and nutrient content of cowpea under low-input field conditions was evaluated.

RESULTS

Seed coating with P. libanensis + multiple isolates of R. irregularis (coatPMR) resulted in significant increases in shoot dry weight (76%), and in the number of pods and seeds per plant (52% and 56%, respectively) and grain yield (56%), when compared with non-inoculated control plants. However, seed coating with P. libanensis + R. irregularis single-isolate (coatPR) did not influence cowpea grain yield. Grain lipid content was significantly higher (25%) in coatPMR plants in comparison with control. Higher soil organic matter and lower pH were observed in the coatPMR treatment.

CONCLUSIONS

Our findings indicate that cowpea field productivity can be improved by seed coating with PGPR and multiple AM fungal isolates under low-input agricultural systems. © 2019 Society of Chemical Industry.

Seed Coating: A Tool for Delivering Beneficial Microbes to Agricultural Crops

Plant beneficial microbes (PBMs), such as plant growth-promoting bacteria, rhizobia, arbuscular mycorrhizal fungi, and Trichoderma, can reduce the use of agrochemicals and increase plant yield, nutrition, and tolerance to biotic-abiotic stresses. Yet, large-scale applications of PBM have been hampered by the high amounts of inoculum per plant or per cultivation area needed for successful colonization and consequently the economic feasibility. Seed coating, a process that consists in covering seeds with low amounts of exogenous materials, is gaining attention as an efficient delivery system for PBM. Microbial seed coating comprises the use of a binder, in some cases a filler, mixed with inocula, and can be done using simple mixing equipment (e.g., cement mixer) or more specialized/sophisticated apparatus (e.g., fluidized bed). Binders/fillers can be used to extend microbial survival. The most reported types of seed coating are seed dressing, film coating, and pelleting. Tested in more than 50 plant species with seeds of different dimensions, forms, textures, and germination types (e.g., cereals, vegetables, fruits, pulses, and other legumes), seed coating has been studied using various species of plant growth-promoting bacteria, rhizobia, Trichoderma, and to a lesser extent mycorrhizal fungi. Most of the studies regarding PBM applied via seed coating are aimed at promoting crop growth, yield, and crop protection against pathogens. Studies have shown that coating seeds with PBM can assist crops in improving seedling establishment and germination or achieving high yields and food quality, under reduced chemical fertilization. The right combination of biological control agents applied via seed coating can be a powerful tool against a wide number of diseases and pathogens. Less frequently, studies report seed coating being used for adaptation and protection of crops under abiotic stresses. Notwithstanding the promising results, there are still challenges mainly related with the scaling up from the laboratory to the field and proper formulation, including efficient microbial combinations and coating materials that can result in extended shelf-life of both seeds and coated PBM. These limitations need to be addressed and overcome in order to allow a wider use of seed coating as a cost-effective delivery method for PBM in sustainable agricultural systems.

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.

Intraocular Pressure Variability in the Anesthetized Rat: A Spectral Analysis

Purpose

Intraocular pressure (IOP) is a measure of the balance between the inflow and outflow of the aqueous humor, being in close relationship with the venous ocular blood flow. But the influence of the autonomic nervous system upon this variable is not well understood. One of the most frequently used mathematical tools for the evaluation of the autonomic nervous system in the frequency domain is the fast Fourier algorithm (FFT) applied to the analysis of heart rate (HR) and arterial blood pressure (BP). For these variables, a power spectrum has been built showing the major bands: very low frequency, lower frequency, and higher frequency (HF). The range of these bands depends on the animal species. In this study, the authors used FFT to analyze the variability of IOP in anesthetized rats.

Methods

BP and electrocardiogram were acquired at 2 KHz in all animals before and following muscle blockade and artificial ventilation at the same frequency as the spontaneous ventilation. Also, in this last condition, IOP was recorded before and after the application of atropine in the eye.

Results

Results show three bands in the IOP spectrum, a similar profile to those observed in the HR and BP spectra, with HF band modified after atropine application

Discussion

The discussion calls attention to the influence of the autonomic nervous system on IOP and suggests the possibility of clinical application of this methodology on diagnosis and therapeutic efficacy.

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.

Increased protein content of chickpea (Cicer arietinum L.) inoculated with arbuscular mycorrhizal fungi and nitrogen-fixing bacteria under water deficit conditions

BACKGROUND

Chickpea (Cicer arietinum L.) is a widely cropped pulse and an important source of proteins for humans. In Mediterranean regions it is predicted that drought will reduce soil moisture and become a major issue in agricultural practice. Nitrogen (N)-fixing bacteria and arbuscular mycorrhizal (AM) fungi have the potential to improve plant growth and drought tolerance. The aim of the study was to assess the effects of N-fixing bacteria and AM fungi on the growth, grain yield and protein content of chickpea under water deficit.

RESULTS

Plants inoculated with Mesorhizobium mediterraneum or Rhizophagus irregularis without water deficit and inoculated with M. mediterraneum under moderate water deficit had significant increases in biomass. Inoculation with microbial symbionts brought no benefits to chickpea under severe water deficit. However, under moderate water deficit grain crude protein was increased by 13%, 17% and 22% in plants inoculated with M. mediterraneum, R. irregularis and M. mediterraneum + R. irregularis, respectively.

CONCLUSION

Inoculation with N-fixing bacteria and AM fungi has the potential to benefit agricultural production of chickpea under water deficit conditions and to contribute to increased grain protein content. © 2017 Society of Chemical Industry.

Arbuscular mycorrhizal fungi are an alternative to the application of chemical fertilizer in the production of the medicinal and aromatic plant Coriandrum sativum L

The widespread use of agrochemicals is detrimental to the environment and may exert harmful effects on human health. The consumer demand for organic food plants has been increasing. There is thus a rising need for alternatives to agrochemicals that can foster sustainable plant production. The aim of this study was to evaluate the potential use of an arbuscular mycorrhizal (AM) fungus as an alternative to application of chemical fertilizer for improving growth performance of the medicinal and aromatic plant Coriandrum sativum. Plants were inoculated with the AM fungus Rhizophagus irregularis BEG163 and/or supplemented with a commercial chemical fertilizer (Plant Marvel, Nutriculture Bent Special) in agricultural soil. Plant growth, nutrition, and development of AM fungus were assessed. Plants inoculated with R. irregularis and those supplemented with chemical fertilizer displayed significantly improved growth performances when compared with controls. There were no significant differences in total fresh weight between plants inoculated with R. irregularis or those supplemented with chemical fertilizer. Leaf chlorophyll a + b (82%), shoot nitrogen (44%), phosphorus (254%), and potassium (27%) concentrations increased in plants inoculated with R. irregularis compared to controls. Application of chemical fertilizer inhibited root mycorrhizal colonization and the length of the extraradical mycelium of R. irregularis. Inoculation with R. irregularis was equally or more efficient than application of chemical fertilizer in promoting growth and nutrition of C. sativum. AM fungi may thus contribute to improve biologically based production of food plants and reduce the dependence on agrochemicals in agriculture.

Seed coating with arbuscular mycorrhizal fungi as an ecotechnologicalapproach for sustainable agricultural production of common wheat (Triticum aestivum L.)

The exploitation of arbuscular mycorrhizal (AM) fungi has become of great interest in agriculture due to their potential roles in reducing the need for agrochemicals, while improving plant growth and nutrition. Nevertheless, the application of AM fungi by dispersing inocula in granular form to open agricultural fields is not feasible because nontargeted spreading of inocula over large surface areas results in high cost per plant. Seed coating has the potential to significantly reduce the amount of inoculum needed, resulting in cost reduction and increased efficiency. The aim of this study was to assess whether seed coating with AM fungal inoculum is a feasible delivery system for production of common wheat (Triticum aestivum L.). Wheat seeds were coated with inoculum of Rhizophagus irregularis BEG140 and grown under different fertilization conditions: (1) none, (2) partial, or (3) complete. Data indicated that mycorrhizal inoculation via seed coating significantly increased the dry weight of shoot and seed spikes of wheat associated with reduced fertilization. Assessment of nutritional status of wheat showed that plants inoculated with R. irregularis via seed coating displayed enhanced stem concentrations of potassium (K), sulfur (S), and zinc (Zn). There were no significant differences in root colonization between plants conventionally inoculated with R. irregularis in soil and those inoculated via seed coating. Seed coating with AM fungi may be as effective as conventional soil inoculation and may contribute to reduce the utilization of chemical fertilizers. The application of AM via seed coating is proposed as an ecotechnological approach for sustainable agricultural wheat production.

The hyperaccumulator Sedum plumbizincicola harbors metal-resistant endophytic bacteria that improve its phytoextraction capacity in multi-metal contaminated soil

Endophyte-assisted phytoremediation has recently been suggested as a successful approach for ecological restoration of metal contaminated soils, however little information is available on the influence of endophytic bacteria on the phytoextraction capacity of metal hyperaccumulating plants in multi-metal polluted soils. The aims of our study were to isolate and characterize metal-resistant and 1-aminocyclopropane-1-carboxylate (ACC) utilizing endophytic bacteria from tissues of the newly discovered Zn/Cd hyperaccumulator Sedum plumbizincicola and to examine if these endophytic bacterial strains could improve the efficiency of phytoextraction of multi-metal contaminated soils. Among a collection of 42 metal resistant bacterial strains isolated from the tissues of S. plumbizincicola grown on Pb/Zn mine tailings, five plant growth promoting endophytic bacterial strains (PGPE) were selected due to their ability to promote plant growth and to utilize ACC as the sole nitrogen source. The five isolates were identified as Bacillus pumilus E2S2, Bacillus sp. E1S2, Bacillus sp. E4S1, Achromobacter sp. E4L5 and Stenotrophomonas sp. E1L and subsequent testing revealed that they all exhibited traits associated with plant growth promotion, such as production of indole-3-acetic acid and siderophores and solubilization of phosphorus. These five strains showed high resistance to heavy metals (Cd, Zn and Pb) and various antibiotics. Further, inoculation of these ACC utilizing strains significantly increased the concentrations of water extractable Cd and Zn in soil. Moreover, a pot experiment was conducted to elucidate the effects of inoculating metal-resistant ACC utilizing strains on the growth of S. plumbizincicola and its uptake of Cd, Zn and Pb in multi-metal contaminated soils. Out of the five strains, B. pumilus E2S2 significantly increased root (146%) and shoot (17%) length, fresh (37%) and dry biomass (32%) of S. plumbizincicola as well as plant Cd uptake (43%), whereas Bacillus sp. E1S2 significantly enhanced the accumulation of Zn (18%) in plants compared with non-inoculated controls. The inoculated strains also showed high levels of colonization in rhizosphere and plant tissues. Results demonstrate the potential to improve phytoextraction of soils contaminated with multiple heavy metals by inoculating metal hyperaccumulating plants with their own selected functional endophytic bacterial strains.

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.

Inoculation with Metal-Mobilizing Plant-Growth-Promoting Rhizobacterium Bacillus sp. SC2b and Its Role in Rhizoremediation

A plant growth-promoting bacterial (PGPB) strain SC2b was isolated from the rhizosphere of Sedum plumbizincicola grown in lead (Pb)/zinc (Zn) mine soils and characterized as Bacillus sp. based on (1) morphological and biochemical characteristics and (2) partial 16S ribosomal DNA sequencing analysis. Strain SC2b exhibited high levels of resistance to cadmium (Cd) (300 mg/L), Zn (730 mg/L), and Pb (1400 mg/L). This strain also showed various plant growth-promoting (PGP) features such as utilization of 1-aminocyclopropane-1-carboxylate, solubilization of phosphate, and production of indole-3-acetic acid and siderophore. The strain mobilized high concentration of heavy metals from soils and exhibited different biosorption capacity toward the tested metal ions. Strain SC2b was further assessed for PGP activity by phytagar assay with a model plant Brassica napus. Inoculation of SC2b increased the biomass and vigor index of B. napus. Considering such potential, a pot experiment was conducted to assess the effects of inoculating the metal-resistant PGPB SC2b on growth and uptake of Cd, Zn and Pb by S. plumbizincicola in metal-contaminated agricultural soils. Inoculation with SC2b elevated the shoot and root biomass and leaf chlorophyll content of S. plumbizincicola. Similarly, plants inoculated with SC2b demonstrated markedly higher Cd and Zn accumulation in the root and shoot system, indicating that SC2b enhanced Cd and Zn uptake by S. plumbizincicola through metal mobilization or plant-microbial mediated changes in chemical or biological soil properties. Data demonstrated that the PGPB Bacillus sp. SC2b might serve as a future biofertilizer and an effective metal mobilizing bioinoculant for rhizoremediation of metal polluted soils.

Serpentine bacteria influence metal translocation and bioconcentration of Brassica juncea and Ricinus communis grown in multi-metal polluted soils

The aim of this study was to assess the effects of inoculation of rhizosphere or endophytic bacteria (Psychrobacter sp. SRS8 and Pseudomonas sp. A3R3, respectively) isolated from a serpentine environment on the plant growth and the translocation and accumulation of Ni, Zn, and Fe by Brassica juncea and Ricinus communis on a multi-metal polluted serpentine soil (SS). Field collected SS was diluted to 0, 25, 50, and 75% with pristine soil in order to obtain a range of heavy metal concentrations and used in microcosm experiments. Regardless of inoculation with bacteria, the biomass of both plant species decreased with increase of the proportion of SS. Inoculation of plants with bacteria significantly increased the plant biomass and the heavy metal accumulation compared with non-inoculated control in the presence of different proportion of SS, which was attributed to the production of plant growth promoting and/or metal mobilizing metabolites by bacteria. However, SRS8 showed a maximum increase in the biomass of the test plants grown even in the treatment of 75% SS. In turn, A3R3 showed maximum effects on the accumulation of heavy metals in both plants. Regardless of inoculation of bacteria and proportion of SS, both plant species exhibited low values of bioconcentration factor (<1) for Ni and Fe. The inoculation of both bacterial strains significantly increased the translocation factor (TF) of Ni while decreasing the TF of Zn in both plant species. Besides this contrasting effect, the TFs of all metals were <1, indicating that all studied bacteria-plant combinations are suitable for phytostabilization. This study demonstrates that the bacterial isolates A3R3 and SRS8 improved the growth of B. juncea and R. communis in SS soils and have a great potential to be used as inoculants in phytostabilization scenarios of multi-metal contaminated soils.

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.

Social determinants of mental health and policy implications

Introduction

WHO has defined the social determinants of mental health (2008) as “social justice is a matter of life or death. Affects how people live, their propensity for disease and risk of premature death”. Underlies that health is not only determined by biological, but by social factors that can be divided into: Economic, Gender and Cultural.

Objectives

The author proposes to do a literature review focusing on a consensus on the social determinants of mental health, and the implications on the policies of various countries.

Aims and methods

We performed a literature review using textbooks and research papers (Medline, Pubmed, 1997–2010).

Results

Topics about Social Determinants of Mental Health often establish, the social gradient, situations of stress, childhood development, poverty, drug dependence, conditions at work, unemployment, social support, food, transportation policies, gender and cultural determinants.

The Global Movement for Mental Health should play an important role in public health activities, focusing on global mental illness. To do this effectively, the mental health professionals need to confront global poverty, its relationship with the political and economic developments as well as the consequences for common mental illnesses.

Conclusions

In a public health perspective, evidence of the mechanisms of this relationship can be used to consider a variety of primary and secondary preventive strategies with regard to mental health.

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.

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.

Wavelet analysis of autonomic outflow of normal subjects on head-up tilt, cold pressor test, Valsalva manoeuvre and deep breathing

Non-invasive autonomic evaluation has used fast Fourier transform (FFT) to assign a range of low (LF) and high frequencies (HF) as markers of sympathetic and parasympathetic influences, respectively. However, FFT cannot be applied to brief transient phenomena, such as those observed on performing autonomic tests where the acute changes of cardiovascular signals (blood pressure and heart rate) that represent the first and most important stage of the autonomic performance towards a new state of equilibrium occur. Wavelet analysis has been proposed as a method to overcome and complement information taken exclusively in the frequency domain. With discrete wavelet transform (DWT), a time-frequency analysis can be done, allowing the visualization in time of the contribution of LF and HF to the observed changes of a particular signal. In this study, we evaluate with wavelets the acute changes in R-R intervals and systolic blood pressure that are observed in normal subjects during four classical autonomic tests: head-up tilt (HUT), cold pressor test (CPT), deep breathing (DB) and Valsalva manoeuvre (VM). Continuous monitoring of ECG and blood presure was performed. Also LF, HF and LF/HF were calculated. Consistent with previous interpretations, data showed an increase of sympathetic activity in HUT, CPT and VM. On DB, results reflected an increase in parasympathetic activity and frequencies. In conclusion, when compared with FFT, wavelet analysis allows the evaluation of autonomic variability during short and non-stationary periods of time and may constitute a useful advance in the assessment of autonomic function in both physiological and pathological conditions.

Estimation of multiple biomass growth rates and biomass concentration in a class of bioprocesses

In this paper, an approach to the estimation of multiple biomass growth rates and biomass concentration is proposed for a class of aerobic bioprocesses characterized by on-line measurements of dissolved oxygen and carbon dioxide concentrations, as well as off-line measurements of biomass concentration. The approach is based on adaptive observer theory and includes two steps. In the first step, an adaptive estimator of two out of three biomass growth rates is designed. In the second step, the third biomass growth rate and the biomass concentration are estimated, using two different adaptive estimators. One of them is based on on-line measurements of dissolved oxygen concentration and off-line measurement of biomass concentrations, while the other needs only on-line measurements of the carbon dioxide concentration. Simulations demonstrated good performance of the proposed estimators under continuous and batch-fed conditions.

Enhancement of carotid chemoreceptor reflex and cardiac chemosensitive reflex in the acute phase of myocardial infarction of the anesthetized rabbit

In the acute phase of cardiac ischemia there is an imbalance of the autonomic outflow with a depression of the baroreceptor reflex. Carotid chemoreceptor stimulation evokes an increase on arterial blood pressure and bradycardia in the anesthetized and paralyzed animal. The activation of cardiac chemosensitive fibers elicit the Bezold-Jarisch reflex comprising a decrease of arterial blood pressure and bradycardia. In the present study, we studied the modifications of the carotid chemoreceptor reflex and the Bezold-Jarisch reflex elicited during the acute phase of myocardial infarction (MI) in the anesthetized and paralyzed rabbit. Rabbits were anesthetized with pentobarbitone, paralyzed and artificially ventilated. The carotid sinus region was exposed and a cannula was inserted retrogradely through the external carotid artery into the carotid bifurcation; the carotid body was stimulated by a lobeline injection. A catheter was advanced, via the right carotid artery, to the origin of the aorta and the Bezold-Jarisch reflex was evoked by an injection of ATP. The baroreflex was provoked by an increase in after-load or by clamping the common carotid artery. Heart ischemia was provoked by ligation of the descending coronary artery. Arterial blood pressure, carotid artery pressure, heart rate and electrocardiogram were monitored. Stimulation of cardiovascular and cardiac receptors was performed before and after coronary ligation. Results show an overall increase in the cardiovascular reflex responses elicited by stimulation of chemically activated receptors and an overall decrease of the baroreceptor responses after MI. In conclusion, these data show the existence of an enhancement of the reflex cardiovascular responses to carotid chemoreceptor and cardiac chemosensitive receptors stimulation and confirmed the depression of baroreceptor reflexes following heart ischemia that could account for the imbalance of the autonomic output observed in the acute phase of myocardial infarction.

Effect on urinary bladder function and arterial blood pressure of the activation of putative purine receptors in brainstem areas

The effect on bladder function and arterial blood pressure of adenosine-5'-triphosphate (ATP) and its synthetic analogue, alpha,beta-methylene ATP (alpha,beta-meATP) applied by microinjection to brainstem areas was assessed in the anaesthetised, paralysed and artificially ventilated female rat. Recordings of bladder pressure, changes in the pelvic nerve activity, arterial blood pressure and heart rate were evaluated. The purinergic drugs were microinjected into two brainstem areas the periaqueductal grey matter (PAG) and the area of the Barrington nucleus/locus coeruleus (LC) - only after electrical stimulation (50 Hz, 1 ms, 30-50 microA; n(PAG) = 17; n(LC) = 18) and the microinjection of glutamate (2 mM, pH 7.4+/-0.1; n(PAG) = 16; n(LC) = 16) had shown increases of bladder pressure and/or rate of bladder contractions and/or pelvic nerve activity at specific sites. Electrical and glutamate activation of PAG evoked an increase of arterial blood pressure. Microinjections of ATP (20 mM, pH 7.4+/-0.1; n(PAG) = 11; n(LC) = 11) and alpha,beta-meATP (2 mM, pH 7.4+/-0.1; n(PAG) = 10; n(LC) = 9) both evoked consistent increases of bladder pressure and/or pelvic nerve activity. Stimulation with ATP elicited a biphasic change of arterial blood pressure characterised by an increase followed by a decrease which was accompanied by a rise of heart rate. Microinjection of alpha,beta-meATP into PAG did not elicit a consistent response: a decrease of arterial blood pressure was evoked in five rats, while in two other rats an increase occurred. Electrical stimulation and glutamate activation of Barrington's nucleus/LC evoked an increase of arterial blood pressure, but a decrease was observed after microinjection of both ATP and alpha,beta-meATP. At some sites (n = 8) the effect of alpha,beta-meATP after a pre-injection at the same site of the P2 purino receptor antagonist, suramin (20 mM, pH 7.4+/-0.1) was smaller than the control. At three sites within PAG and two within LC located more medially to sites where an excitatory response had been observed, electrical stimulation evoked a small decrease or no change in bladder pressure. Following the stimulus, a rise in bladder pressure was preceded by an increase of pelvic nerve activity. A similar effect of glutamate was observed in one case. These data suggest that activation of P2 purine receptors in both PAG and Barrington's nucleus/LC is implicated in the neuronal mechanisms that generate patterns of activity in the parasympathetic innervation of the bladder and that purines also act at this level to modify sympathetic outflow to the cardiovascular system.

Interaction of the Bezold-Jarisch reflex with the urinary bladder function

OBJECTIVES

The Bezold-Jarisch reflex involves a marked increase in vagal (parasympathetic) efferent discharge to the heart. During micturition, there is a marked increase in parasympathetic activity to the bladder (pelvic nerve activity) and this coincides with periods of phasic bladder contractions. In recent studies, we have shown that regions of the CNS that modulate pelvic nerve activity also affect cardiovascular variables. Recent anatomical studies have shown neuronal connections between the areas of the CNS that modulate both reflexes. Accordingly, in the present study we investigate if during the Bezold-Jarisch reflex there are simultaneous changes in pelvic nerve activity.

METHODS

Experiments were performed in Wistar female rats, anaesthetised with alpha-chloradose i.p. (80 micrograms/Kg) supplemented i.v. as required. Arterial blood pressure, ECG heart rate, urinary bladder pressure and pelvic nerve activity were recorded.

RESULTS

Stimulation of cardiac chemosensitive nerve endings with veratridine evoked a decrease in arterial blood pressure from 88.6 +/- 1.72 to 66.1 +/- 2.50 mmHg (n = 30; p < 0.0001) and of heart rate from 420.3 +/- 5.56 to 248.8 +/- 17.58 bpm (n = 13; p < 0.0001) There were simultaneous changes of pelvic nerve activity that preceded an increase in urinary bladder pressure from 10.2 +/- 0.28 to 26.3 +/- 1.52 cmH2O (n = 30; p < 0.0001) and bladder contractions. We believe that the reflex changes resulted from activation of cardiac chemosensory nerve endings, as equivalent injections of warm saline into the left ventricle produced no changes in either cardiovascular variables or pelvic nerve activity.

CONCLUSIONS

These observations suggest a significant role for cardiac afferents in modulating bladder contractions. The integration and functional significance of these inputs remain to be elucidated. The clinical importance of this physiological result may contribute to a better understanding of the mechanism of some semiologic findings, notably the association of urgency to micturate with myocardial ischemia and myocardial infarction.