Natalia Buzzi

Extracellular ATP activates MAP kinase cascades through a P2Y purinergic receptor in the human intestinal Caco-2 cell line.

BACKGROUND ATP exerts diverse effects on various cell types via specific purinergic P2Y receptors. Intracellular signaling cascades are the main routes of communication between P2Y receptors and regulatory targets in the cell. METHODS AND RESULTS We examined the role of ATP in the modulation of ERK1/2, JNK1/2, and p38 MAP kinases (MAPKs) in human colon cancer Caco-2 cells. Immunoblot analysis showed that ATP induces the phosphorylation of MAPKs in a time- and dose-dependent manner, peaking at 5 min at 10 microM ATP. Moreover, ATPgammaS, UTP, and UDP but not ADP or ADPbetaS increased phosphorylation of MAPKs, indicating the involvement of, at least, P2Y2/P2Y4 and P2Y6 receptor subtypes. RT-PCR studies and PCR product sequencing supported the expression of P2Y2 and P2Y4 receptors in this cell line. Spectrofluorimetric measurements showed that cell stimulation with ATP induced transient elevations in intracellular calcium concentration. In addition, ATP-induced phosphorylation of MAPKs in Caco-2 cells was dependent on Src family tyrosine kinases, calcium influx, and intracellular Ca2+ release and was partially dependent on the cAMP/PKA and PKC pathways and the EGFR. GENERAL SIGNIFICANCE These findings provide new molecular basis for further understanding the mechanisms involved in ATP functions, as a signal transducer and activator of MAP kinase cascades, in colon adenocarcinoma Caco-2 cells.

Assessment of trace metal accumulation in native mussels (Brachidontes rodriguezii) from a South American temperate estuary

The present work provides the first results in heavy metal bioaccumulation in the autochthonous mussel Brachidontes rodriguezii from the Bahía Blanca Estuary (Argentina), one of the most important coastal environments of South America, subjected to different anthropogenic pressure. The study is based on the detection of Cd, Cu, Pb, Mn, and Fe in mussels’ soft tissue and sediments’ fine fraction by means of inductively coupled plasma atomic emission spectroscopy (ICP-OES), in order to analyze the potential relationship between both components of the aquatic system. Additionally, different indices are calculated with the purpose of obtaining detailed data. The heavy metal burden in mussels varied seasonally, showing a clearer pattern for the stations located in the internal area of the estuary. Metals exhibited maximum values in summer and to a lesser extent in winter, followed by a decrease during spring. Multiple international guideline assessment allowed classifying the area as moderately polluted, including a low range for Cd and medium for Cu and Pb. Moreover, the average detected levels were within the measured ranges in other coastal areas. Regarding human health, trace metal content in mussels met the national and international standards for safe consumption.

Ephemeral parasitism on blooming diatoms in a temperate estuary

Parasites of phytoplankton influence phytoplankton bloom dynamics and may severely affect the type of food available for higher trophic levels. The incidence of parasitic infections generally is expected to increase across ecosystems worldwide under the scenario of global change. Herein we report on a massive parasite infection on two dominant diatoms of the austral winter bloom, namely Thalassiosira pacifica and Chaetoceros diadema, recorded during an extreme precipitation period in the Bahia Blanca Estuary, Argentina. The parasite infection was concomitant with a marked drop in water salinity and affected more than 40% of host cells. Although the parasite on C. diadema was not identified, the parasite on T. pacifica was most likely Pirsonia sp., a nanoflagellate with high host specificity. After the intense rainy period and the parasitic infection, the phytoplankton biomass dropped (by more than 80%) and the community structure shifted to one with smaller species (i.e. Thalassiosira curviseriata, T. hibernalis and T. minima). We discuss the implications that these modifications may have on the food web dynamics and the potential relationship between precipitation-driven modifications in water properties and the emergence of parasitism in coastal eutrophic environments.

Pesticides Reaching the Environment as a Consequence of Inappropriate Agricultural Practices in Argentina

Recent water quality inventories show that agricultural non-point source pollution (NPS) is the leading source of water quality impacts to surveyed rivers and lakes, and also a major contributor to groundwater contamination and wetlands degradation (Blankenberg et al. 2006; Haarstad and Braskerud 2005; Bergstrom 2004; Thiere and Schulz 2004; Schreiber et al. 2001; Huber et al. 2000; Luo and Zhang 2010). Pest management is one of the main scopes of pesticides usage, because more than 45% of annual food production is lost due to pest infestation. In particular, at tropical climates this is enhanced due to prevailing high temperature and humidity. However, the sporadic use has been leading to significant consequences not only to public health but also to food quality resulting in an impact load on the environment and hence the development of pest resistance (Giupponi and Rosato 1999; Luo and Zhang 2010) Through overuse, misuse and losses due to the inappropriate application of pesticides there is considerable waste contributing to the environmental burden (Li et al. 2006; Giupponi and Rosato 1999; Hu et al. 2010; Marco and Kishimba 2007; Luo and Zhang 2010). It is well known that most of the applied pesticides are subject to many transport and conversion processes. Thus, they do not remain at their target site but often enter aquatic environments via soil percolation, air drift or surface run-off, affecting abundance and diversity of nontarget species, producing complex effects on the ecosystems and, altering trophic interactions (Islam and Tanaka, 2004). Pesticides overuse also destroys the healthy pool of bio-control agents that normally co-exist with the vegetation. Simultaneously, some soil biological functions such as the bioavailability of nutrients and organic matter decomposition could also be altered (Hendrix 1996; Guo et al. 2009). For instance, the herbicides can influence soil microbial biomass carbon (MBC) and metabolic quotient (qCO), variables directly related to soil quality (Reis et al. 2009). In addition, agrochemical application on soybean shoots affects the activity of soil microorganisms in the plant rhizosphere (Reis et al. 2009). The bulk of pesticides worldwide used is herbicides and there is almost no knowledge of their impact on potential non-target plant species, especially rare or endemic species