Search

Rain-fed granite rock pools are geological landforms with a worldwide distribution. However, their role as habitats for microorganisms has been barely explored. We carried out a detailed morphological inventory of the ciliated protists in the sediments of three granite rain-fed rock pools from a Spanish National Park. The ciliate seed bank in the rock pools comprised 54 morphospecies. The species number inferred for each pool by rarefaction analysis was similar to that observed by microscopy. The most representative species were small bacterivorous ciliates, although the distribution of ciliate groups was significantly different in each rock pool. Testate amoebae were also found to be rich in species. This study demonstrates the existence of a diverse ciliate community adapted to persist in these ephemeral and extreme rock pool habitats through species resistance structures, many of which have not been described previously. The presence of competitive species in dormant stages prevents local extinctions through a sequential excystation over time. Our results provide a benchmark for studying protist and microbial biodiversity within rain-fed granite rock pools, a unique habitat that merits bio- and geo- conservation.

A comparative analysis of toxicities of both arsenic forms (arsenite and arsenate) in the model eukaryotic microorganism Tetrahymena thermophila (ciliate protozoa) has shown the presence of various detoxification mechanisms and cellular effects comparable to those of animal cells under arsenic stress. In the wild type strain SB1969 arsenate is almost 2.5 times more toxic than arsenite. According to the concentration addition model used in binary metallic mixtures their toxicities show an additive effect. Using fluorescent assays and flow cytometry, it has been detected that As(V) generates elevated levels of ROS/RNS compared to As(III). Both produce the same levels of superoxide anion, but As(V) also causes greater increases in hydrogen peroxide and peroxynitrite. The mitochondrial membrane potential is affected by both As(V) and As(III), and electron microscopy has also revealed that mitochondria are the main target of both arsenic ionic forms. Fusion/fission and swelling mitochondrial and mitophagy, together with macroautophagy, vacuolization and mucocyst extruction are mainly associated to As(V) toxicity, while As(III) induces an extensive lipid metabolism dysfunction (adipotropic effect). Quantitative RT-PCR analysis of some genes encoding antioxidant proteins or enzymes has shown that glutathione and thioredoxin metabolisms are involved in the response to arsenic stress. Likewise, the function of metallothioneins seems to be crucial in arsenic detoxification processes, after using both metallothionein knockout and knockdown strains and cells overexpressing metallothionein genes from this ciliate. The analysis of the differential toxicity of As(III) and As(V) shown in this study provides cytological and molecular tools to be used as biomarkers for each of the two arsenic ionic forms.

This is a retrospective single-center study of patients with neovascular age-related macular degeneration whose follow-up was delayed due to COVID-19 pandemic with at least three months between visits in Madrid, Spain. The purpose of the study was to evaluate best corrected visual acuity (BCVA) changes and try to identify features in optical coherence tomography (OCT) that could be related to more profound visual loss. It included 270 eyes. The two last visits before lockdown were used for comparison with the visit after lockdown. BCVA changed from 60.2 ± 18.2 to 55.9 ± 20.5 ETDRS letters. 29% of the eyes lost more than 5 letters. OCT was active in 67% of eyes before lockdown and in 80.4% after lockdown. Multiple lineal analysis showed that patients whose OCT before lockdown presented with a combination of intra and subretinal fluid were more likely to suffer a greater visual loss (p = 0.002). These patients should be encouraged to not miss any visits in case a new lockdown is imposed.

Consequences of the COVID-19 pandemic on medical care have been extensively analyzed. Specifically, in ophthalmology practice, patients suffering age-related macular degeneration (AMD) represent one of the most affected subgroups. After reporting the acute consequences of treatment suspension in neovascular AMD, we have now evaluated these same 242 patients (270 eyes) to assess if prior functional and anatomical situations can be restored after twelve months of regular follow-up and treatment. We compared data from visits before COVID-19 outbreak and the first visit after lockdown with data obtained in subsequent visits, until one year of follow-up was achieved. For each patient, rate of visual loss per year before COVID-19 pandemic, considered “natural history of treated AMD”, was calculated. This rate of visual loss significantly increased during the lockdown period and now, after twelve months of regular follow-up, is still higher than before COVID outbreak (3.1 vs. 1.6 ETDRS letters/year, p < 0.01). Percentage of OCT images showing active disease is now lower than before the lockdown period (51% vs. 65.3%, p = 0.0017). Although anatomic deterioration, regarding signs of active disease, can be apparently fully restored, our results suggest that functional consequences of temporary anti-VEGF treatment suspension are not entirely reversible after 12 months of treatment, as BCVA remains lower and visual loss rate is still higher than before the COVID-19 pandemic.

To investigate long-term effect (96 months) of intravitreal ranibizumab administered for exudative age-related macular degeneration (AMD) on retinal nerve fiber layer (RNFL) thickness when used following a pro re nata regimen. In this prospective study, 20 eyes of 20 patients diagnosed with exudative AMD were included. Contralateral non-exudative AMD eyes of nine of these patients were included as controls. Data on intraocular pressure (IOP) and number of injections were recorded. Spectralis optic coherence tomography (OCT) of the circumpapillary RNFL was performed under dilation when diagnosis was made and before the three loading injections. “Follow-up” software was selected to accurately compare baseline with subsequent images through the 8 years of the study. Baseline IOP was 14.1 mmHg both in study (standard deviation, SD: 0.8) and control eyes (SD: 0.9) and remained unchanged during the study. Mean number of injections was 21 (SD: 2.8) at the end of the study. Mean average thickness of RNFL in the study eye group at the end of the study was 96.5 μm (SD: 2.1). Mean loss for the study period was 5.3 μm (SD: 0.7; p

espanol"Parablechnum" es el genero mas diverso de las Blechnaceae (ca. 65 especies), con una distribucion pantropical y dos centros de diversidad, en America y en la region austro-pacifica. Las especies son dimorfas, con rizomas normalmente erguidos y escamas rizomaticas, frondas pinnadas, con hoja truncada en la base, de apice conforme y pinnas pecioluladas. Este grupo presenta muchos problemas taxonomicos, por lo que se necesitan estudios mas detallados para resolver conflictos de separacion entre especies. Este trabajo trata del complejo americano de P. cordatum en el que se incluyen las especies P. cordatum, P. schiedeanum, P. chilense, P. falciforme y Blechnum varians. Se ha llevado a cabo un analisis biometrico de los esporangios y las esporas, estructuras taxonomicamente importantes en la distincion de los helechos. Los datos se sometieron a un analisis unidireccional de la varianza y a un analisis discriminante. Ademas, las esporas se observaron bajo un microscopio electronico de barrido para estudiar su ornamentacion. De los caracteres que hemos estudiado, el grosor del arco, el numero de celulas en el arco, el numero de celulas en el hipostomio y el diametro mayor ecuatorial de la espora han apoyado estadisticamente su importancia taxonomica y, por lo tanto, son utiles para la separacion de especies. English"Parablechnum" is the most diverse genus of Blechnaceae (ca. 65 species), with a pantropical distribution and two centers of diversity, in America and in the Austro-Pacific region. The species are dimorphic, with often erect rhizomes and rhizomatic scales, 1-pinnate fronds, with truncate blade at base, conform apex and stalked pinnae. This group presents many taxonomic problems, needing more detailed studies to resolve these conflicts of separation between species. This work deals with the American complex of P. cordatum in which the species P. cordatum, P. schiedeanum, P. chilense, P. falciforme and Blechnum varians are included. A biometric analysis of sporangia and spores, important taxonomic structures in the distinction of ferns, has been carried out. The data were subjected to a one-way analysis of variance and a discriminant analysis. In addition, the spores were observed under a scanning electron microscope to study their ornamentation. Of the characters we have studied thickness of the arcus, number of cells in the arcus, number of cells in the hypostome and major equatorial diameter of the spore have statisticalParablechnum is the most diverse genus of Blechnaceae (ca. 65 species), with a pantropical distribution and two centers of diversity, in America and in the Austro-Pacific region. The species are dimorphic, with often erect rhizomes and rhizomatic scales, 1-pinnate fronds, with truncate blade at base, conform apex and stalked pinnae. This group presents many taxonomic problems, needing more detailed studies to resolve these conflicts of separation between species. This work deals with the American complex of P. cordatum in which the species P. cordatum, P. schiedeanum, P. chilense, P. falciforme and Blechnum varians are included. A biometric analysis of sporangia and spores, important taxonomic structures in the distinction of ferns, has been carried out. The data were subjected to a one-way analysis of variance and a discriminant analysis. In addition, the spores were observed under a scanning electron microscope to study their ornamentation. Of the characters we have studied thickness of the arcus, number of cells in the arcus, number of cells in the hypostome and major equatorial diameter of the spore have statistically supported taxonomic significance and are therefore useful for species separation.

Nowadays, functional traits are widely used to study autoecological aspects in plant species. The analysis of these traits among climatic gradients allows us to know the strategy that plants follow depending on resource availability. Referring to plants, the traits measured in the leaves have a special importance; among these traits we can find SLA (Specific Leaf Area), LDMC (Leaf Dry- Matter Content) and LT (Leaf Thickness). In this work, these traits are measured in four species of the genus Asplenium. As extremes of a climatic gradient, we have focused our study in both bioclimatic regions existing in the Iberian Peninsula. Taking into account the differences referring to the resource availability for the species in each region, the main goal of this work is analyzing the variations of the three functional traits mentioned in the four species in both locations and associate these variations to macroclimatic variables. To this aim, fronds from the four species were collected in populations of each bioclimatic region to determine the fresh weight, dry weight and the foliar area. From these variables, we calculated the three functional traits. The results have shown that ferns adopt higher productive yields in the Mediterranean region (higher SLA values) and lower LDMC and LT values than in the Eurosiberian region. As to the climate variables effects, the average of the maximum temperatures in the warmest month (TMAX) is the variable that better explains the differences in the productive yield that the plants adopt in each region. On the other hand, annual precipitation seems not to play an important role on any of the functional traits in any of the species. Finally, we didn’t find a generalized tendency in the effects of the extern variables: frozen period, minimum temperatures in the coolest month and arid period.

Las pilas representan un tipo de forma presente en casi todos los ambientes climáticos. El trabajo estudia el papel de los ciclos térmicos como un agente importante del modelado y asimetría que presentan las paredes de las pilas en un clima Mediterrá- neo templado - frío. El estudio se ha realizado en el macizo granítico de la Pedriza de Manzanares, zona protegida de gran valor ambiental, incluida en el Parque Nacional de la Sierra de Guadarrama (Madrid, España). El análisis de la variabilidad térmica mediante modelos de regresión perió- dica múltiple, pone de manifiesto la influencia de los ciclos diario y anual en función de las orientaciones norte y sur de las paredes de las pilas. Un modelo matemático de regresión lineal muestra cómo la variabilidad térmica diaria influye en la alteración de las paredes de las pilas, generando superficies planas o de concavidad más o menos pronunciada. El trabajo también establece relaciones entre el grado de alteración de las diferentes partes de las pilas, con la presencia de líquenes y dureza relativa de la roca. Los resultados avalan la hipótesis de relación causal entre la variabilidad térmica y alteración de las paredes de las pilas según su orientación norte o sur.

Rain fed granite rock basins are ancient geological landforms of worldwide distribution and structural simplicity. They support habitats that can switch quickly from terrestrial to aquatic along the year. Diversity of animals and plants, and the connexion between communities in different basins have been widely explored in these habitats, but hardly any research has been carried out on microorganisms. The aim of this study is to provide the first insights on the diversity of eukaryotic microbial communities from these environments. Due to the ephemeral nature of these aquatic environments, we predict that the granitic basins should host a high proportion of dormant microeukaryotes. Based on an environmental DNA diversity survey, we reveal diverse communities with representatives of all major eukaryotic taxonomic supergroups, mainly composed of a diverse pool of low abundance OTUs. Basin communities were very distinctive, with alpha and beta diversity patterns non-related to basin size or spatial distance respectively. Dissimilarity between basins was mainly characterised by turnover of OTUs. The strong microbial eukaryotic heterogeneity observed among the basins may be explained by a complex combination of deterministic factors (diverging environment in the basins), spatial constraints, and randomness including founder effects. Most interestingly, communities contain organisms that cannot coexist at the same time because of incompatible metabolic requirements, thus suggesting the existence of a pool of dormant organisms whose activity varies along with the changing environment. These organisms accumulate in the pools, which turns granitic rock into high biodiversity microbial islands whose conservation and study deserve further attention.

The original version of this article contained an erratum of omission in the Acknowledgments section.

Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy, specifically forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.

Stomata are crucial structures for plants to better adapt themselves to the environment, in relation to many ecological variables. In this sense, it is widely accepted that (a) stomatal size is much more genetically fixed than density, which can be dynamically modified in new leaves to adjust them to changing conditions and (b) density is expected to increase with light and to decrease with water availability. These statements come from research done mainly for the angiosperms and gymnosperms, whilst ferns remain highly understudied. The main objective of this work is to investigate the relationship between morphological traits of fern stomata and light and water environments. We selected 15 species of different ecological preferences, representing contrasted habitats of light and water. Fifteen to twenty individuals of each species were sampled, and from each one, we chose three different adult fronds. One measurement of density and five measurements of stomata length were done under OM in each frond. The functional variable potential conductance index (PCI) has been calculated from length and density and used as a proxy of transpiration area. This study allows extending the knowledge of ecomorphology of stomata in temperate fern species. Generally speaking, these ferns behave in similar ways to other known plant groups: length has more genetic significance, whilst density is usually modified depending on the environment. However, temperate ferns seem to modify density by modifying ordinary epidermal cells instead of size of stomata, a fact that is known only for a small number of angiosperms. Species that inhabit low water availability environments (exposed rocks, crevices and cliffs) developed significant shorter stomata, but at higher densities and with higher potential conductance, species from low light availability environments (shadowed rocks and forests) have longer stomata and lower density. These results increase the knowledge on how temperate ferns can adapt their bodies to occupy different ecological niches.

Plant dispersal is a very important ecological phenomenon, as it can enable species to move away from the parent plant. This contributes to shaping communities, determining patterns of distribution, landscape configuration, plant invasions and evolutionary processes. Measuring dispersal distance directly is difficult and thus, diaspore morphology can be used to make estimates. Previous research on the topic often resorts to analysing the diaspore's morphology as if it was a bi-dimensional structure; when in many cases, diaspores have three-dimensional qualities. In this study, we show how estimates of wind dispersal potential of Ailanthus altissima can be considerably improved using morphological variables that succeed in describing the three-dimensional nature of samaras. We suggest that this reasoning could be extensively applied to research involving not only other species, but also multi-specific scenarios with a wide range of diaspore morphologies. Publicado

The data presented in this paper is supporting the research article “Estimating wind dispersal potential in Ailanthus altissima: The need to consider the three-dimensional structure of samaras” [1]. We analyzed the estimation of samara's wind dispersal potential through a group of morphological variables that succeed in describing the three-dimensional nature of samaras. We present here a dataset containing 8 morphological variables of 200 samaras belonging to 5 different individuals of the invasive tree Ailanthus altissima (Mill.) Swingle. Additionally, we present the average descent velocity of each of the samaras, which was recorded by releasing 5 times each samara under controlled and reproducible conditions. The data set is structured in a single spreadsheet where we also included the samara and the individual identity code of the tree. Keywords: Ailanthus altissima, Diaspore morphology, Samara, Three-dimensional structure, Wind dispersal potential

Stomata are very conserved structures in plants, which allows and control the gas exchange. This ecophysiological fact appears to be critical in the ecology and adaptation of plants to environment. Plant individuals can, among other issues, adjust size and density of the stomata to adapt themselves to hydric, thermic and light regimes. In turn, this led to the reduction of transpiration and control of water losses, which is crucial in areas with Mediterranean climate. The fern Osmunda regalis has populations in both biogeographical regions of the Iberian Peninsula (Eurosiberian and Mediterranean regions), but when locations are highly continental the populations are scarce and isolated. The objective of this study is to characterize the stomatal morphological traits in both regions, to detect possible adaptations in individuals occurring in Mediterranean locations. 26 individuals of 17 different populations were sampled. Applying microscopic techniques, 4447 observations of length and width, and 234 of density and PCI were done. The sampling spots were characterized by two bioclimatic indices of Emberger and Gorzynski, and also mean maximum and minimum temperature values were obtained. All the information was included in a dataset that was statistically analyzed with the software SPSS. Our results show that Osmunda regalis fronds have higher PCI and density values in the Eurosiberian region, as expected. Gorczynski continentality index (K), and the mean maximum and minimum annual temperatures influences over stomatal traits. This is clearly informing that in the Mediterranean region, the temperature is an important factor that triggers stomatal adaptations of O. regalis to continental locations with higher levels of environmental stress. On the contrary, Emberger pluviometric index (Q) seems to be less explicative by its own. Perhaps this is related with the habitat of O. regalis in soils with high freatic level, fact which could...

During the transition from S phase to mitosis, vertebrate neuroepithelial cells displace their nuclei and subsequently migrate from the basal membrane to the apical surface of the neuroepithelium, a phenomenon termed interkinetic nuclear movement (INM). Here we provide evidence that cycling neuroepithelial cells pass through a neurogenic state in which they are situated apically, as defined by the capacity to express Notch1, Delta1, and Neurogenin2 (Ngn2). Based on this scenario, we have developed a mathematical model to analyze the influence of INM on neurogenesis. In the absence of INM, the model predicted an increase in the rate of neurogenesis due to the reduction in the influence of inhibitory signals on cells in the neurogenic state. This exacerbation in neurogenesis led to the diminished growth of the neuroepithelium and a reduction in the later production of neurons. Pharmacological perturbation of the stereotypical distribution of precursors along the orthogonal axis of the neuroepithelium resulted in an excess of neurogenesis, as seen by the expression of Ngn2, and of the neuronal marker RA4 in the retina. These findings suggest that INM might be important for the efficient and continued production of neurons in G0, since it is involved in defining a proneural cluster in the ventricular part of the neuroepithelium that contains precursors at stages of the mitotic cycle compatible with neuronal differentiation.

The benefit obtained by a selfish robot by cheating in a real multirobotic system can be represented by the random variable X n,q : the number of cheating interactions needed before all the members in a cooperative team of robots, playing a TIT FOR TAT strategy, recognize the selfish robot. Stability of cooperation depends on the ratio between the benefit obtained by selfish and cooperative robots. In this paper, we establish the probability model for X n,q . If the values of the parameters n and q are known, then this model allows us to make predictions about the stability of cooperation. Moreover, if these parameters are modifiable, it is possible to tune them to guarantee the viability of cooperation.

13 p.-1 fig.-2 tab., A proliferating population of cells may be considered complex when its proliferative or growth fraction P is lower than 1 and/or when it is formed by subpopulations with different mean cycle times. The present paper shows that in such complex populations exponential growth is consistent with a steady-state distribution of cells. Obviously, when P = 1 then cell distribution is only a function of cell age. An analytical model has been developed to study complex populations including both quiescent fractions formed by cells with unreplicated genome (G0 cells) and cells with fully duplicated chromosomes (Q2 cells). The model also considers those quasi-quiescent cells in their last transit through G1 and S (Q1 and Qs cells) before becoming quiescent. In order to solve the difficulties of a direct analysis of the whole population, its kinetic parameters have been obtained by studying the negative exponential distribution of two subpopulations: one formed by the proliferating cells and another formed by the quasi-quiescent cells. Additionally, the model could be applied when quiescence is initiated at any other cycle phase different from G1 and G2, for instance, cells in the process of replicating their DNA or being at any other mitotic phases. The utility of the method was illustrated in populations which constitute the root meristems of both Allium cepa L. and Pisum sativum L. Three facts should be stressed: (1) the method seems to be rather powerful because it can be carried out from different sets of experimentally measured parameters; (2) the rate of division and, therefore, the population doubling time can be easily estimated by this method; and (3) it also allows the determination of the amount of cells that had become quiescent either before they had replicated their DNA (G0) or after having completed their replication (Q2), as well as those quasi-quiescent cells which are progressing throughout their last pre-replicative and replicative periods (thus Q1 and Qs, respectively). © 2002 Elsevier Science Ltd. All rights reserved., This work has been partially supported by the Direccio! n General de Ensen* anza Superior e Investigacio! n Cient!ıfica del Ministerio de Educacio! n y Cultura from Spain (Projects PB96-0909 and PB97-0909, by the CSIC-Universidad de Chile joint Project (99 CL-0009) and by the European Union (BIO6-CT96-0275). We thank Mr J. L. Marcilla and Ms M. Carrascosa for excellent technical assistance.

Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velocity of constriction) in a large sample of younger and older adults (N = 97), in mesopic conditions. Subjects were exposed to a single light stimulus at four different wavelengths: white (5600° K), blue (450 nm), green (510 nm), and red (600 nm). Data was analyzed appropriately, and, when applicable, using the General Linear Model (GLM), Randomized Complete Block Design (RCBD), Student's t-test and/or ANCOVA. Across all subjects, pupillary response to light had the greatest amplitude and shortest latency in white and green light conditions. In regards to age, older subjects (46-78 years) showed an increased latency in white light and decreased velocity of constriction in green light compared to younger subjects (18-45 years old). This study provides data patterns on parameters of wavelength-dependent pupil reflexes to light in adults and it contributes to the large body of pupillometric research. It is hoped that this study will add to the overall evaluation of cephalic autonomic nervous system integrity.

We propose a model, based on the Gompertz equation, to describe the growth of yeasts colonies on agar medium. This model presents several advantages: (i) one equation describes the colony growth, which previously needed two separate ones (linear increase of radius and of the squared radius); (ii) a similar equation can be applied to total and viable cells, colony area or colony radius, because the number of total cells in mature colonies is proportional to their area; and (iii) its parameters estimate the cell yield, the cell concentration that triggers growth limitation and the effect of this limitation on the specific growth rate. To elaborate the model, area, total and viable cells of 600 colonies of Saccharomyces cerevisiae, Debaryomyces fabryi, Zygosaccharomyces rouxii and Rhodotorula glutinis have been measured. With low inocula, viable cells showed an initial short exponential phase when colonies were not visible. This phase was shortened with higher inocula. In visible or mature colonies, cell growth displayed Gompertz-type kinetics. It was concluded that the cells growth in colonies is similar to liquid cultures only during the first hours, the rest of the time they grow, with near-zero specific growth rates, at least for 3 weeks.Mathematical models used to predict microbial growth are based on liquid cultures data. Models describing growth on solid surfaces, highlighting the differences with liquids cultures, are scarce. In this work, we have demonstrated that a single Gompertz equation describes accurately the increase of the yeast colonies, up to the point where they reach their maximum size. The model can be used to quantify the differences in growth kinetics between solid and liquid media. Moreover, as all its parameters have biological meaning, it could be used to build secondary models predicting yeast growth on solid surfaces under several environmental conditions.

Microorganisms colonize surfaces and develop biofilms through interactions that are not yet thoroughly understood, with important implications for water and wastewater systems. This study investigated the interactions between N-acyl homoserine lactone (AHL)-producing bacteria, yeasts and protists, and their contribution to biofilm development. Sixty-one bacterial strains were isolated from activated sludge and screened for AHL production, with Aeromonas sp. found to be the dominant AHL producer. Shewanella xiamenensis, Aeromonas allosaccharophila, Acinetobacter junii and Pseudomonas aeruginosa recorded the highest adherence capabilities, with S. xiamenensis being the most effective in surface colonization. Additionally, highly significant interactions (i.e. synergic or antagonistic) were described for dual and multistrain mixtures of bacterial strains (P. aeruginosa, S. xiamenensis, A. junii and Pseudomonas stutzeri), as well as for strongly adherent bacteria co-cultured with yeasts. In this last case, the adhered biomass in co-cultures was lower than the monospecific biofilms of bacteria and yeast, with biofilm observations by microscopy suggesting that bacteria had an antagonist effect on the whole or part of the yeast population. Finally, protist predation by Euplotes sp. and Paramecium sp. on Aeromonas hydrophila biofilms not only failed to reduce biofilm formation, but also recorded unexpected results leading to the development of aggregates of high density and complexity.Single- and multi-species microbial biofilms developed by different prokaryotic/eukaryotic microorganisms were investigated in order to study the interactions across populations and their contribution to biofilm development.Single- and multi-species microbial biofilms developed by different prokaryotic/eukaryotic microorganisms were investigated in order to study the interactions across populations and their contribution to biofilm development.

The quality of the sludge in Wastewater Treatment Plants (WWTPs) depends on the suitable colonization of the flocs by microorganisms. Due to the functional importance of these biological constituents, several biological or biological-related parameters have been commonly used for the control of depuration efficiency. According to national and international water regulation recommendations, interlaboratory studies have a great relevance to determine which parameters are more reliable for their extensive application in routine control. However, these studies are also very useful to demonstrate consistency in results from multiple laboratories and to develop reliable and reproducible methodologies which might be necessary for protocol validation and also for accreditation issues to meet regulatory environmental requirements. The main purpose of this work was to assess the results obtained in consecutive interlaboratory assays in order to determine the concordance degree in the application of biological parameters by participating laboratories. Following the international recommendations about these studies, a common working protocol was proposed. Statistical tests indicated that Sludge Index and several routine physical–chemical analyses [V30, Mixed Liquor Suspended Solids (MLSS), Mixed Liquor Volatile Solids (MLVS) and Sludge Volumetric Index (SVI)] show low variability and therefore are suitable tools for laboratory control. Shannon Index and Sludge Biotic Index also presented low variability although a more precise protocol would be necessary, in particular the methodology to count small flagellates. The abundance and identification of protist species showed low concordance among laboratories and three factors were responsible for the low reliability of data: population density, size and morphological distinguishable characters of the specimens.

Background: The resurgence of home hemodialysis (HHD) underlines the importance of educational pro- grams. Brainstorming is a powerful tool for innovation, widely employed in industry but seldom used in medi- cine. The aim of this study was to define an e-learning Web platform for HHD patients via a brainstorming ap- proach. Methods: Four brainstorming sessions were held 2-6 weeks apart. Twelve people were involved: 2 dialysis physicians, 2 nurses, 2 HHD patients, 2 caregivers, a filmmaker, 2 computer experts (1 with a psychology de- gree) and a senior engineer. Each session was summa- rized as the starting point for the following one. The top- ics discussed were the platform structure and its logo. Results: For the platform, the following requirements were defined: teaching should be extensive and tai- lored to different levels of knowledge; all available teaching tools (tutorials, demonstrations, recorded and written materials) should be used; films enhance emotional participation and can be used to reduce fears; the contents should include general information on chronic kidney disease, details of all types of renal replacement therapy (RRT) (how and why), dialysis ac- cidents, blood and imaging tests, laws and reimburse- ments, direct experiences and history of RRT. Remote monitoring and visual interactions are important for reassurance about HHD and should be provided. The requirements for the logo were that it be innovative, related to daily life, representative of a holistic ap- proach and convey happiness. The logo "Hom-e-hem" was created, playing on the assonance between the religious term Om and the word home, with the e of electronic linking it with hem, short for hemodialysis. Conclusion: Brainstorming sessions can be used to design patient-tailored educational interventions. The key message, "self-care is a bridge from illness back to life," may apply to a wider context

The rat facial whiskers form a high-resolution sensory apparatus for tactile information coding and are used by these animals for the exploration and perception of their environment. Previous work on the rat vibrissae system obtained evidence for vibration-based feature extraction by the whiskers, texture classification by the cortical neurons, and "low-pass", "high-pass", and "band-pass" filtering properties in both thalamic and cortical neurons. However, no data are available for frequency-dependent information processing in the brainstem sensory trigeminal complex (STC), the first relay station of the vibrissae pathway. In the present paper, we studied the frequency-dependent processing characteristics of the STC nuclei that mainly project to the thalamus, nuclei principalis, and interpolaris. This is the first time that STC nuclei have been studied together via a wide range of stimulation frequencies (1-40 Hz), four different and complementary metrics, and the same experimental protocol. Moreover, the role of corticofugal projection to these nuclei as well as the influence of input from the whiskers has been analyzed. We show that both nuclei perform frequency-dependent coding of tactile information: low pass and band-pass filtering occurs for the spiking rate in short post-stimuli time intervals, high-pass and band-pass filtering occurs for the spiking rate in long trains of stimuli, and an increase of response latencies and low pass filtering occurs for phase-locked stimuli. These information-processing characteristics are neither imposed by the sensorimotor cortex nor introduced by the afferent fibres. The sensorimotor cortex exerts a distinct modulatory effect on each nucleus.

Algorithms for artificial neural networks are usually developed assuming in the most of the models that information propagates fordward and backward across the neural network. Fordwards propagation is modeled easily in ANN and biologically plausible in biological neurons, however for backwards propagation the plausibility of the algorithms developed for ANN seems remote in biological neurons. Based on the presynaptic changes induced by the arachidonic acid released by postsynaptic neurons during long-term potentiation (LTP) in the dentate gyrus, we show a computer simulation model where a backward feedback is performed across local synapses by arachidonic acid. Our simulation model shows how arachidonic acid could be playing the role of retrograde messenger during LTP.

In this paper we develop an approximation to the expectation of a random variable implied in cooperation stability, presented in a previous work. This approximation is obtained by means of a continuous monotonous function that upper bounds the expectation. Finally, we analyze the quality of this approximation.

Optimization of performance in collective systems often requires altruism. The emergence and stabilization of altruistic behaviors are difficult to achieve because the agents incur a cost when behaving altruistically. In this paper, we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism. This strategy in conjunction with learning capabilities make altruistic agents cooperate only between themselves, thus preventing their exploitation by selfish agents, if future benefits are greater than the current cost of altruistic acts. Our multi-agent system is made up of agents with a behavior-based architecture. Agents learn the most suitable cooperative strategy for different environments by means of a reinforcement learning algorithm. Each agent receives a reinforcement signal that only measures its individual performance. Simulation results show how the multi-agent system learns stable altruistic behaviors, so achieving optimal (or near-to-optimal) performances in unknown and changing environments.

Optimization of performance in collective systems often requires altruism. Emergence and stabilization of altruistic behaviors are difficult because the agents incur a cost when behaving altruistically. In this paper we propose a biologically inspired strategy to learn stable altruistic behaviors in artificial multi-agent systems, namely reciprocal altruism. Our multi-agent system is made up of autonomous agents with a behavior-based architecture. Agents learn the most suitable cooperative strategy for different environments by means of a reinforcement learning algorithm. Each agent receives a reinforcement signal that only measures its individual performance. Simulation results show how the multi-agent system learns stable altruistic behaviors, so reaching optimal (or near-to-optimal) performances in unknown and changing environments.