No abstract

I In nf fl lu ue en nc ce e o of f b be ed d m me ed di ia a c ch ha ar ra ac ct te er ri is st ti ic cs s o on n a am mm mo on ni ia a a an nd d n ni it tr ra at te e r re em mo ov va al l i in n s sh ha al ll lo ow w h ho or ri iz zo on nt ta al l s su ub bs su ur rf fa ac ce e f fl lo ow w c co on ns st tr ru uc ct te ed d w we et tl la an nd ds s Abstract Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4-N m −2 d −1 and 3 g NO3-N m −2 d −1 ) and removal efficiencies (>62% for ammonia, 90-100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrificationdenitrification. The nitrogen loading rate of both ammonia (0.8-2.4 g NH4-N m −2 d −1 ) and nitrate (0.6-3.2 g NO3-N m −2 d −1 ) seem to have influenced the respective removal rates.

The proper design of DNA microarray experiments requires knowledge of biological and technical variation of the studied biological model. For the filamentous fungus Aspergillus niger, a fast, quantitative real-time PCR (qPCR)-based hierarchical experimental design was used to determine this variation. Analysis of variance components determined the contribution of each processing step to total variation: 68% is due to differences in day-to-day handling and processing, while the fermentor vessel, cDNA synthesis, and qPCR measurement each contributed equally to the remainder of variation. The global transcriptional response to D-xylose was analyzed using Affymetrix microarrays. Twenty-four statistically differentially expressed genes were identified. These encode enzymes required to degrade and metabolize D-xylose-containing polysaccharides, as well as complementary enzymes required to metabolize complex polymers likely present in the vicinity of D-xylosecontaining substrates. These results confirm previous findings that the D-xylose signal is interpreted by the fungus as the availability of a multitude of complex polysaccharides. Measurement of a limited number of transcripts in a defined experimental setup followed by analysis of variance components is a fast and reliable method to determine biological and technical variation present in qPCR and microarray studies. This approach provides important parameters for the experimental design of batch-grown filamentous cultures and facilitates the evaluation and interpretation of microarray data.Culturing filamentous organisms such as Aspergillus niger is difficult to reproduce compared to culturing unicellular organisms. Filamentous growth is characterized by the elongation and branching of hyphae, cylindrical cells that increase in length by growth at one end. De novo biosynthesis and active enzyme production occur mainly at the hyphal tips. In regions of distance from the tip, the hyphae age and become biologically less active (38). This hyphal growth is the result of adaption to the habitat of the organism, which enables it to spread over and penetrate surfaces and cross over nutrient-depleted gaps (6). However, under laboratory conditions, attachment of fungal mycelium to fermentor baffles and other extremities introduces heterogeneous growth that can be suppressed only to a certain extent (for instance, by cooling the fermentor headplate). The growing mycelium increases the culture broth viscosity, which reduces the mass transport of nutrients, oxygen, and heat, and affects the mixing characteristics in a fermentor or shake flask over time. Physical agitation and shear stress can cause uncontrolled breakage and fragmentation of the mycelia (37).Recent technologies such as global transcriptome analysis by DNA microarrays or quantitative real-time PCR (qPCR) require the use of replicate biological samples for high-quality data. Given the difficulties in culturing A. niger, obtaining transcript data without wasting resources requires proper experimental design. The k...

The capacity for physiological colour change has long been described in anuran amphibians. Camouflage against predators seems to be the most relevant function of dynamic changes in skin colour of frogs, but key aspects such as the rate at which these changes occur, or the specific colour components involved are not completely clear. Whereas most research on the topic has been reported on tree frogs in laboratory conditions, studies in other anurans or in the field are much scarcer. Here we show a potentially plastic, adaptive response in coloration of common midwife toads, Alytes obstetricans, from a population of central Portugal, whose pigmentation varied with their natural backgrounds. Using quantitative image analysis, we compared hue, saturation and brightness of dorsal skin coloration of toads and the colour of the area of ground immediately around them. We found a positive correlation between coloration of toads and background colour for the three components of the colour. As well as other anuran species, A. obstetricans might adjust skin coloration to match the surrounding environment, thus benefitting from short-term reversible crypsis strategies against predators. A less supported hypothesis would be that toads accurately select matching backgrounds to improve concealment as an antipredatory strategy.

An approach based on Gateway recombination technology to efficiently construct silencing vectors was developed for use in the biotechnologically important fungus Aspergillus niger. The transcription activator of xylanolytic and cellulolytic genes XlnR of A. niger was chosen as target for gene silencing. Silencing was based on the expression vector pXLNRir that was constructed and used in co-transformation. From all the strains isolated (N=77), nine showed poor xylan-degrading activities in two semiquantitative plate assays testing different activities for xylan degradation. Upon induction on D-xylose, transcript levels of xlnR were decreased in the xlnR-silenced strains, compared to a wild-type background. Under these conditions, the transcript levels of xyrA and xynB (two genes regulated by XlnR) were also decreased for these xlnRsilenced strains. These results indicate that the newly developed system for rapid generation of silencing vectors is an effective tool for A. niger, and this can be used to generate strains with a tailored spectrum of enzyme activities or product formation by silencing specific genes encoding, e.g., regulators such as XlnR.

No abstract

During ebb situations in tidal estuaries with high tidal amplitude most of the system is out of water. ln this period intertidal pool formation takes place in very extended areas. These pools differ with respect to intemal nutrient loading, hydraulic conditions, duration, plant coverage, sediment properties such as organic content in the sediment, C/N/P-ratios of the sediment nutrient sources and porewater concentrations of nutrients. Therefore, the objective was to study and compare the nutrient sources and dynamics in different types of intertidal pools of the Mondego estuary. ln each intertidal pool the nutrient dynamics were followed on a seasonal scale by measuring oxygen dynamic, phosphate, ammonia, nitrate besides physical parameters as salinity. temperature, sediment organic matter; sediment total phosphorus, potential phosphate adsorption, total sediment nitrogen, sediment water contento pool volume and pool area The results showed that the nutrient dynamics in shallow intertidal pools are much faster than in subtidal areas. This is most probably due to the shallowness of the systems giving anabolic as well as catabolic processes optimal conditions with respect to light climate, oxygen concentrations, higher concentrations of dissolved inorganic nutrient and higher mean temperature during the growth season. At1ogether; this study indicate that in the Sportino moritimo covered areas the plants are able to control the phosphorus dynamic due to Sportino moritimo take up phosphate for growth purposes, that without plant coverage would have retumed to the watercolumn and that Sportino do also facilitates the increased phosphate adsorption. On the system levei most pools are situated on bare bottom without connection to rooted vegetation, and these leaks with substantial amounts of phosphate. 50 the intertidal pool system of the Mondego estuary at10gether are exporting significant amounts of phosphorus in these years.

A navegação consulta e descarregamento dos títulos inseridos nas Bibliotecas Digitais UC Digitalis, UC Pombalina e UC Impactum, pressupõem a aceitação plena e sem reservas dos Termos e Condições de Uso destas Bibliotecas Digitais, disponíveis em https://digitalis.uc.pt/pt-pt/termos.Conforme exposto nos referidos Termos e Condições de Uso, o descarregamento de títulos de acesso restrito requer uma licença válida de autorização devendo o utilizador aceder ao(s) documento(s) a partir de um endereço de IP da instituição detentora da supramencionada licença.Ao utilizador é apenas permitido o descarregamento para uso pessoal, pelo que o emprego do(s) título(s) descarregado(s) para outro fim, designadamente comercial, carece de autorização do respetivo autor ou editor da obra.Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso. The aim of the present work was to evaluate the importance of nutrient f1uxes across the sediment-water interface to the growth of opportunistic macroalgae (Enteromorpha sp.) within tidal pools of an intertidal estuary. We hypothesised that different tidal pools. in relation with organic matier content in the sediment and the presence/absence of rooted-macrophytes. promote distinct growth responses of Enteromorpha sp. Nutrient dynamics (P04-P, NH4-N and N03-N) and Enteromorpha intestina/is growth were assessed during low-tide period in 4 different places: a sandy bare botiom pool. muddy pools (a bare botiom pool and a Spartina maritima covered pool) and the low-depth subtidal channel. Macroalgal growth in the subtidal area was estimated to compare with results from the tidal pools. Results showed that the growth rate of E. intestina/is was higher in the muddy bare botiom pool and statistically different from growth in the other places. No significant differences were found between macroalgal growth in the S. maritima covered pool. the sandy pool and the channel.The differences are partially explained by different nutrient dynamics between the muddy bare botiom pool and the other places. The availability of NH.-N was higher in the muddy bare botiom pool. followed by the S. maritima covered pool. the channel and the sandy bare botiom pool. N:P atomic ratios of the water suggested that. with the exception of the muddy bare botiom pool. ali the other places showed a potential N-limitation for primary production. Results also suggested that Spartina maritima affect the nutrient dynamics in tidal pools. However in this type of pools. the growth of E. intestina/is may also be affected by shading caused by the rootedmacrophyte presence. ln the channel. other factors (e.g. hydrodynamics) affect macroalgal growth. which determines differences in relation with tidal pools. At the system levei. these results suggest that in terms of nutrient availability. the occurrenc...