No abstract

During the last decade, the Palmones River estualy has undergone severe eutrophication followed by a green tide episode; two species ofUlva, rotundata Blid. and Ulva curvata (Kutz.) De Toni, were the main macroalgae responsible for this bloom. From November 1993 to December 1994, we followed the biomass, the growth dynamics, and tissue elemental composition (C:N:P) of Ulva species, as well as some physicochemical variables in the estualy. Maximum biomass (up to 375 g dly wt.m-2 in some spots, corresponding to a thallus area index of nearly 17 m2 Ulva m-2 sediment) were observed in June and December. However, the biomass vaned among the sampling stations. Water nitrate, ammonia, and phosphate showed high concentrations throughout the year, with extremely high transient pulses, sustaining the high growth rates obseroed. Growth rates were estimated directly i n the field. The rates were generally higher i n Ulva discs maintained in net cages than those estimated by changes in biomass standing stock between two consecutive samplings. The dqerence between both estimates was used to quantijj the importance of the processes causing loss of biomass, which were attrib utable to grazing, exported biomass, and thallus decomposition under anaerobic conditions resulting from extreme selfshading. Maximum chlor@hyll content was found in winter, whereas the minimum was in spring. Atomic N:P ratios were generally higher in the algae than in the water, However, the absolute concentrations of tissue N and P were always higher than the cn'tical h e l s for maximum growth, which suggests that growth was not limited by inorganic N or P availability. The results suggested that the increase in nutrient loading in the river may have triggered the massive development of green algae and that light limitation and temperature stress in summer seem to be the main factors controlling the abundance of Ulva in the estualy. I n addition to light availability and thermal stress, the different loss processes may have a decisive role in the dynamics of Ulva biomass. K q index words: eutrophication; growth; primaly p r e duction; Ulva Local proliferations of masses of green algae are often found in estuaries and coastal waters of areas undergoing eutrophication (Geertz-Hansen et al.

The present study assessed the effect of seawater ammonium enrichment on survival and growth of the seagrass Zostera noltii Hornem. Ammonium enrichment had an inhibitory effect on shoot, rhizome and root elongation rates, as well as on primary production. The inhibitory effect was partially alleviated by phosphate addition. The frequency of ammonium pulses also affected growth negatively, with a maximum effect at both low and high pulse frequencies. Similar results were obtained when the experiment was run in the field during a winter trial. However, when the field experiment was repeated in spring at higher mean temperature and irradiance levels, opposite results were obtained, with ammonium enrichment causing a substantial increase in growth rates and productivity. These responses were related to the internal balance of non-structural carbohydrates (especially sucrose) with respect to C and N cell metabolism. Thus, there was a mobilisation of sucrose in both above-and belowground tissues to meet C increased demands arising from ammonium assimilation in winter, with sucrose concentrations reaching critical levels in relation to the total internal C pool. In contrast, sucrose accumulated in the tissues when ammonium pulses were applied in spring, indicating an enhanced C turnover that was able to meet the increased demands arising from ammonium assimilation into organic N compounds.

No abstract

Protein Kinase CK2 is a serine-threonine kinase frequently deregulated in many human tumors. Here, we hypothesized that a peptide binder to the CK2 phosphoacceptor site could exhibit anticancer properties in vitro, in tumor animal models, and in cancer patients. By screening a random cyclic peptide phage display library, we identified the CIGB-300 (formerly P15-Tat), a cyclic peptide which abrogates the CK2 phosphorylation by blocking recombinant substrates in vitro. Interestingly, synthetic CIGB-300 led to a dose-dependent antiproliferative effect in a variety of tumor cell lines and induced apoptosis as evidenced by rapid caspase activation. Importantly, CIGB-300 elicited significant antitumor effect both by local and systemic administration in murine syngenic tumors and human tumors xenografted in nude mice. Finally, we performed a First-in-Man trial with CIGB 300 in patients with cervical malignancies. The peptide was found to be safe and well tolerated in the dose range studied. Likewise, signs of clinical benefit were clearly identified after the CIGB-300 treatment as evidenced by significant decrease of the tumor lesion area and histological examination. Our results provide an early proof-of-principle of clinical benefit by using an anti-CK2 approach in cancer. Furthermore, this is the first clinical trial where an investigational drug has been used to target the CK2 phosphorylation domain.