Use of siRNAs and antisense oligonucleotides against survivin RNA to inhibit steps leading to tumor angiogenesis

The antiapoptotic protein survivin is an attractive target in cancer therapy because it is expressed differently in tumors and normal tissues and it is potentially required for cancer cells to remain viable. Given that survivin is also overexpressed in endothelial cells (ECs) of newly formed blood vessels found in tumors, its RNA targeting might compromise EC viability and interfere with tumor angiogenesis. We used two antisense strategies against survivin expression, antisense oligonucleotides (aODN) and small interfering RNA (siRNA), to study in ECs the contribution of survivin in various steps leading to tumor angiogenesis. A 21-mer phosphorothioate aODN and two siRNA oligonucleotides against survivin mRNA were designed to downregulate survivin expression. Survivin targeting caused (1) a strong growth-inhibitory effect, (2) a 4-fold increase in apoptosis, (3) an accumulation of cells in the S phase and a decrease in G2/M phase, (4) a dose-dependent inhibition of EC migration on Vitronectin, and (5) a decrease in capillary formation. Control oligonucleotides, an unrelated oligonucleotide, and one with four mismatches, had no significant effect. All these results show that survivin is a suitable target in cancer therapy because its inhibition in EC causes both a proapoptotic effect and an interruption of tumor angiogenesis. The two strategies used, classic aODN and siRNA technology, were very effective. Moreover, the latter can be used in the low nanomolar range, thus increasing the sensitivity of the treatment.     

Are Antarctic suspension-feeding communities different from those elsewhere in the world?

This paper reviews the trophic ecology of benthic suspension feeders in Antarctic shelf communities, studied within SCAR's EASIZ Programme, in comparison with published information from other seas. Dense benthic suspension-feeder communities capture large quantities of particles and may directly regulate primary, and indirectly, secondary production in littoral food chains. Most work has been performed in temperate and tropical seas; however, little is known about suspension feeders in cold environments. Recent studies on Antarctic littoral benthic suspension feeders suggest the period of winter inactivity may last only a few weeks. This contrasts with the hypothesis that in Antarctic communities there is a prolonged period of minimal activity lasting at least 6 months during the austral winter. Results from other oceans may explain how dense benthic communities could develop under such conditions. Alternative food sources, i.e. the "fine fraction", sediment resuspension, lateral advection and efficient food assimilation may play a significant role in the development of suspension-feeder dominated, very diversified, high biomass and three-dimensionally structured communities on the Antarctic shelf.     

Seasonal energetic constraints in Mediterranean benthic suspension feeders: effects at different levels of ecological organization

The aim of this work is to examine the role of food as a constraining factor at different levels of ecological organization in benthic littoral ecosystems. In the search for patterns in ecological systems, it has recently been documented that seasonality in the dynamics of benthic suspension feeders (BSF) in the Mediterranean Sea is characterized by summer dormancy. We review recent studies on seston availability in the water column and feeding and respiration by BSF in the Mediterranean. The objective is to assess whether a pattern across particular studies exists that could provide evidence of food as a constraining factor. A pattern emerges from these organism‐level studies, one which indicates the seasonal occurrence of an energy shortage in the taxa exhibiting summer dormancy. This energy shortage is closely related to low food availability and suggests that an energetic constraint underlie the summer dormancy phenomenon. The seasonal occurrence of summer energy shortage also appears to affect the dynamics of BSF at population and community level. In this sense, in late summer 1999, a mass mortality event of BSF affected several hundreds of kilometers in the Ligurian Sea (NW Mediterranean). The fact that the mass mortality event occurred in late summer and especially affected the taxa that exhibit energy shortage – such as anthozoans and sponges – suggests, that energetic constraints may contribute to the understanding of the mass mortality event. The energy shortage phenomenon may provide a mechanism to understand how the occurrence of anomalous climatic conditions may have induced the mass mortality of some BSF taxa. This review points out the existence of a common energy shortage phenomenon mainly related to low food availability as an important determinant of the dynamics of most BSF taxa at organism level in the Mediterranean. But this determinant also affects the dynamics of BSF at population and community level. Therefore, the extant data point up the crucial role of food as a constraining factor for benthic littoral ecosystems in oligotrophic areas like the Mediterranean, with important seasonal variations in seston abundance and composition.     

Recurrent partial mortality events in winter shape the dynamics of the zooxanthellate coral <Emphasis Type="Italic">Oculina patagonica</Emphasis> at high latitude in the Mediterranean

Global warming has many biological effects on corals and plays a central role in the regression of tropical coral reefs; therefore, there is an urgent need to understand how some coral species have adapted to environmental conditions at higher latitudes. We examined the effects of temperature and light on the growth of the zooxanthellate coral Oculina patagonica (Scleractinia, Oculinidae) at the northern limit of its distribution in the eastern Iberian Peninsula (western Mediterranean) by transplanting colonies onto plates and excluding them from space competition over a ~4-yr period. Each year, most of the colonies (~70%) exhibited denuded skeletons with isolated polyps persisting on approximately half of the coral surface area. These recurrent episodes of partial coral mortality occurred in winter, and their severity appeared to be related to colony exposure to cold but not to light. Although O. patagonica exhibited high resistance to stress, coral linear extension did not resume until the coenosarc regenerated. The resumption of linear extension was related to the dissociation of the polyps from the coenosarc and the outstanding regenerative capacity of this species (10.3 mm² d^?1). These biological characteristics allow the species to survive at high latitudes. However, the recurrent and severe pattern of denuded skeletons greatly affects the dynamics of the species and may constrain population growth at high latitudes in the Mediterranean.     

Cycle of gonadal development in Eunicella singularis (Cnidaria: Octocorallia): trends in sexual reproduction in gorgonians

Abstract. Eunicella singularis is a gorgonian species whose members are abundant in hard-bottom sublittoral communities of the Mediterranean Sea. The reproductive biology in this species has been examined to better understand the ability in this species to recover from recent mass mortality events. Eunicella singularis is a stable, gonochoric, iteroparous species that reproduces annually and exhibits a seasonal pattern of gametogenesis characterized by a single annual maturation of the gametes. The sex ratio did not significantly differ from 1:1. Oogenesis lasted 13–17 months, beginning between February and June, and ending with the release of 0.7 planula larvae per polyp between late May and July of the following year. The diameter of mature oocytes ranged 450–860 μm. Spermatogenesis was much shorter than oogenesis and occurred over 5–6 months. Gonadal production of both sexes increased in spring and culminated with the spawning of male colonies in late May–June. Fertilization of oocytes and development of the planula larvae occurred within the polyps of female colonies. Planula release was observed in June and July. The patterns emerging from this and previous studies on sexual reproduction of Mediterranean gorgonians suggest that investment in gonad development appears to be related to resource availability.