S.M. Ferreira

The effect of different primary producers on Hydrobia ulvae population dynamics: a case study in a temperate intertidal estuary

The effect of macroalgal blooms and the consequent disappearance of Zostera noltii meadows on Hydrobia ulvae population dynamics and production was studied in the Mondego estuary based on data obtained from January 1993 to September 1995. Sampling was carried out at a non-eutrophicated area, covered with Z. noltii, and also at an eutrophicated area, where seasonal Enteromorpha spp. blooms occur. Stable populations represented by individuals of all age classes were found only at the Z. noltii meadows throughout the study period. On the contrary, at the eutrophicated area, during most of the time, solely juveniles were present, with adults appearing only during the macroalgal bloom (>1.5 mm width). During the algal bloom (e.g. 1993), H. ulvae population density was clearly higher in the eutrophicated area due to the combined effect of stronger benthic recruitments (99% of veliger larvae newly recruited) and dispersion of juveniles proceeding from the Z. noltii meadows to this area. On the other hand, in the absence of macroalgae (spring of 1994), 98.9% of veliger larvae was recruited in the Z. noltii meadows. Therefore, H. ulvae seems to respond rapidly to macroalgal dynamics and its presence at the eutrophicated area depends on the existence of green macroalgae. H. ulvae presented the same benthic recruitment pattern at the two sampling areas, with new cohorts being produced in March, June, July and September. Depending on the time of the year in which the recruitment took place, cohorts showed different growth rhythms. However, after 12 months they reached a similar size. A three-generation life cycle involving a short-lived (16 months), fast growing spring generation, a medium growing (17–19 months) summer generation and a longer-lived (20 months) slower growing generation that overwinters is identified. As a general trend, productivity and mean population standing biomass were higher at the Z. noltii meadows, during the entire study, except for a short period, during the macroalgal bloom, when production was higher at the eutrophicated area. On the contrary, P/B ratios were higher at the eutrophicated area. According to our results, H. ulvae population structure and yearly productivity are clearly affected by eutrophication, namely by the dynamics of macroalgal blooms. In the long run, we may infer that, following the disappearance of the Z. noltii meadows, due to eutrophication, H. ulvae would also tend to disappear, since reproductive adults were almost exclusively found in this area.

The influence of cadmium contamination and salinity on the survival, growth and phytoremediation capacity of the saltmarsh plant Salicornia ramosissima

The major aim of this study was to evaluate the capacity of Salicornia ramosissima on Cadmium phytoremediation under distinct salinities and, consequently, the toxic effects on the plants development. A greenhouse experiment was performed, using two Cd concentrations (50 and 100 μg l(-1)) in different salinities (0, 5 and 10). Mortality and weight variation, observed at the end of the experiment, showed significant differences between some treatments, meaning that these variables were affected by the salinity and Cd concentrations. The highest Cd accumulation was detected in the roots, and decreased with the increase of salinity and Cd concentration. S. ramosissima is a potential candidate for Cd phytoremediation at salinities close to 0 and its capabilities in Cd phytoaccumulation and phytoestabilization proved to be quite interesting. The optimization of phytoremediation processes by S. ramosissima could turn possible the use of this plant in the recovery of contaminated ecosystems.

The faunal role in the degradation of the common intertidal salt marsh plant Scirpus maritimus

The aim of this work was to evaluate the role of different environmental conditions (oxic and anoxic), and the presence of macrofauna and/or meiofauna during the different steps of Scirpus maritimus L. decomposition/mineralization under controlled laboratory conditions. The results showed no significant differences between the anaerobic and the aerobic degradation of plant material, under the presence of bacteria or meiofauna. Nevertheless, under anoxic conditions sediment mineralization was enhanced, with an increase concentration of phosphorus and ammonium in the water phase. Concerning the presence of fauna, results show that, although bacterial activity was responsible for 70% of the S. maritimus leaves degradation, the presence of macrofauna together with meiofauna enhanced the leaves mineralization up to 90%. Moreover, the presence of macrofauna together with meiofauna significantly affected the decomposition of phosphorus and of nitrogen, as well as the leaves lesser labile structural parts, by increasing the mineralization of plant carbon, and raised the nutrient turnover within the system.The present study reinforces the functional link between fauna levels on the nutrient dynamics in salt marshes ecosystems, namely at the vegetation detritus/water column interface.

Trematode fauna of Hydrobia ulvae (Gastropoda: Prosobranchia) in a eutrophic temperate estuary

Digenean trematodes infecting the mud snail Hydrobia ulvae were studied at two key sites of the Mondego Estuary (Portugal), from January 1993 to September 1995: a mud flat covered by the seagrass Zostera noltii , and a bare sand flat where seasonal macroalgal blooms occurred as a result of eutrophication. Digeneans belonging to Microphallidae, Notocotylidae, Haploporidae and Heterophyidae were recorded in snails from both sites whereas representatives from Echinostomatidae were only found in snails from the seagrass bed. The density of infected snails was higher at the seagrass bed than at the eutrophic area partly reflecting the difference in population structure of H. ulvae between sites. The Zostera noltii bed supports an abundant and well-structured mud snail population, with all size-classes represented, in contrast to a less abundant and juvenile dominated population in the eutrophic area. In the Z. noltii bed no clear seasonal and interannual patterns emerged in the infection densities. In the eutrophic area, the density of infected individuals increased in the presence of algae, and decreased during the occurrence of occasional flood events. Small scale spatial and temporal patterns in the prevalence of digenean trematodes in mud snails were therefore demonstrated within the Mondego Estuary that has experienced a mixture of anthropogenic impact and climate instability.

Infection characteristics of a trematode in an estuarine isopod: influence of substratum

The estuarine isopod Cyathura carinata is a second intermediate host to microphallid trematodes, which use mud snails Hydrobia spp. and shorebirds as respectively first intermediate and final hosts. To identify processes responsible for infection patterns observed in C. carinata, a short-term microcosm experiment was conducted with both macroinvertebrates and one of their common parasites – Maritrema subdolum. Fine sand collected from two different shallow water sites was used to test if sediment type could affect infection rates. After 7 days at 25 °C, C. carinata from the substratum with the highest proportion of particles <125 μm were more surface active and obtained significantly more M. subdolum individuals than isopods from the other sediment type. No parasite-induced effects on the hosts were found during this short-term experiment. The distribution pattern of microphallid cysts and mesocercariae inside the isopods revealed that M. subdolum cercariae primarily penetrated through the pleopods and afterwards located themselves in the middle-posterior region of the host’s body. Even if it was not possible to identify the factor responsible for the observed infection patterns (cercariae production and/or host behaviour), the results of this experiment indicate that small-scale factors, such as differences in substratum and associated features, may have considerable impact on infections of host populations.

The presence of cadmium in the intertidal environments of a moderately impacted coastal lagoon in western Portugal (Óbidos Lagoon)—spatial and seasonal evaluations

A seasonal environmental monitoring program was carried out (winter 2009 to summer 2010) to evaluate the spatial and seasonal cadmium concentrations in the intertidal environments of the Óbidos Lagoon (Portugal). Also, some environmental parameters were monitored at each sampling station. Both the water and the sediment samples were contaminated, although to different degrees. In general, cadmium contamination appears to be mostly focused on the inner areas of the lagoon, namely, in Barrosa’s arm, which receives a small tributary contaminated by agro-industrial activities. Only cadmium concentration in sediment showed to be significantly influenced by seasons. Some environmental parameters presented spatial and temporal heterogeneity which influenced, to some extent, cadmium bioavailability. The results of this study allow a better understanding of the environmental quality of this ecosystem regarding cadmium contamination and may assist in the definition of future coastal management measures specifically targeted to trace metal contamination and pollution monitoring.

Abstract 2603: Cancer stem cells and dedifferentiation: the stromal match-point.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Bypassing all the research advances in the last decades, cancer remains as a major public health problem affecting more than 1.5 million (M) new individuals each year just in the USA, and killing more than 0.5 M. Recent research emphasized the major role of cancer stem cells (CSCs) in the metastatic disease, the main cause of cancer patients mortality. CSCs drive tumorigenesis and differentiation, contributing to tumors’ heterogeneity and to their relative chemo- and radiotherapy resistance and eventually relapse. Following CSCs identification, targeted therapeutic approaches have been developed to abolish them. However, CSCs can reemerge through dedifferentiation of tumor-committed stromal cells condemning this therapeutics. The mechanisms behind dedifferentiation are still unclear and are the main focus of our investigation. Lung cancer is one of the main causes of cancer-related deaths worldwide. Its prevalence is increasing due to the widespread smoking habits and increasing accumulation of atmosphere pollutants. In this work hexavalent chromium [Cr(VI)] was selected as a model of cancer carcinogenesis mainly due to is increasing occupational relevance. The non-malignant human bronchial epithelial cell line BEAS-2B was malignantly transformed into the RenG2 system using low density culture in the presence of Cr(VI). A parallel control cell line (Cont1) was produced under the same conditions, though, in the absence of Cr(VI). Two additional cell lines (DRenG2 and DDRenG2) were attained following serial rounds of injection in nude mice. Metabolic studies using [18F]fluoro-2-deoxyglucose) and nuclear magnetic resonance spectroscopy performed in all the cell lines revealed a more glycolytic phenotype for the derivatives (DRenG2 and DDRenG2), compatible with a quiescent phenotype. Subsequent karyotype and real time PCR-based cellular characterization identified different cellular sub-populations within each cell line, strengthening the hypothesis on the CSCs presence. The sphere-formation assay, used to search for CSCs presence, revealed the presence of CSCs only DRenG2 and in DDRenG2 cell lines. This suggested that a dedifferentiation process featured the formation of CSCs during RenG2 derivation in nude mice. The involvement of mice stroma in this process was uncovered by surgical isolation of mouse stromal cells of the subcutaneous compartment and subsequent co-culture with RenG2 cells for 30-60 days (time needed to induce tumors in mice with RenG2), which resulted in the emergence of a CSCs sub-population. A cytokine multiplex array analysis performed in the conditioned medium of the co-cultured cells in parallel with comparative genome hybridization array (aCGH) analysis performed in all the cell lines under study revealed a panel of potential paracrine orchestrators of this stromal-induced dedifferentiation process. Citation Format: Carlos F. Rodrigues, Mariana Val, Ines P. Rodrigues, Susana Ferreira, Filomena Botelho, Jose Ramalho, Anatoly Zhitkovich, Isabel M. Carreira, Carmen Alpoim. Cancer stem cells and dedifferentiation: the stromal match-point. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2603. doi:10.1158/1538-7445.AM2013-2603