Micro-players for macro-roles: aquatic microbes in deep lakes

Despite their relative low volume on a global scale, lakes represent a valuable reserve of accessible freshwaters. Any increase in our understanding of their functioning is a step towards their better exploitation and preservation. Microorganisms drive the metabolic processes that regulate the biogeochemical cycles in lakes; here, I will focus on Archaea and Cyanobacteria as micro-players playing macro-roles in lake ecosystems. In particular, I will present two examples to demonstrate the importance of prokaryotes in lakes: picocyanobacteria and mesophilic archaea. The role of prokaryotes in lakes will be discussed in relation to their taxonomy, dynamics and ecology using these two examples. The challenge, now, is to better understand the relationship between the diversity and the physiology of various ecotypes, how these interact with each other and with environmental factors allowing the proliferation of the most competitive genotypes

Archaeology and public works: an example from Iran

The contrast, often dramatic, between the needs of the economic development in the protection of our cultural heritage concerns mainly those countries which are endowed with a glorious past full of historical remains, among them there is Iran as well. In this country, one of the fields that stands for one of the main risk for the protection of the cultural heritage is represented by the ambitious plan to build several dams in order to solve the country water and energy problems. The author shows one of the project worked out by the Iranian Office for the Cultural Heritage, whose goal is to cope with such emergencies. This project refers to archaeological surveys carried out in the area which should be flooding by the Sinvand dam, not so far from the ancient centre of Pasargade, in the Fars area: this project presents an additional interest since it is based on a international collaboration totally new for the Moslem Republic. An "archaeological mission" of the Ravenian branche of the Alma Mater Studiorum (Facoltà di Conservazione dei Beni Culturali), shas taken part to this valuable program, and as explored two rural settlements of Achemenide and Post-achemenide Age (VIth-Ist century B.C.) age, in collaboration with the Iranian Centre for the Archaeological Researches. The results of these three excavations performed, represent the first proof of the region occupation belonging to this period, outside the big dynastic complexes of palaces

Single cells and microcolonies of freshwater picocyanobacteria: a common ecology

Picocyanobacteria (Pcy) single-cells and microcolonies are common in lakes throughout the world, and abundant across a wide spectrum of trophic conditions. The single-celled Pcy populations tend to be predominant in large, deep oligo-mesotrophic lakes, while the microcolonies find optimal conditions in warmer, shallower and more nutrient rich lakes. Microcolonies of different size (from 5 to 50 cells) constitute a gradient without a net separation from single-celled types. Considering microcolonies as transitional forms from single-cells to colonial morphotypes it is conceivable to propose a common ecology where local communities are not isolated but linked by dispersal of multiple, potentially interactive, species. In this review abiotic forcing and biotic regulation of Pcy community structure and dynamics are examined to offer an updated view of Pcy ecology

Daphnia and ciliates: who is the prey?

The fortuitous observation of a Daphnia infested by Gymnostomatida led us to hypothesize that egg predation by ciliates could be an important mechanism regulating cladoceran population dynamics. In light of this hypothesis we reanalysed data on the dynamics of Daphnia eggs and of one Gymnostomatida species from Lago Maggiore (1996). This communication is mainly a plea to examine data where both cladocerans and Gymnostomatida were collected, to verify if the occurrence of this yet undescribed eggvoricity is widespread. Further research is needed to investigate the ecological significance of this phenomenon

Susceptibility of bacterioplankton to nutrient enrichment of oligotrophic and ultraoligotrophic lake waters

We carried out laboratory experiments in one ultraoligotrophic pristine Andean lake (Lake Guti?rrez, Argentina) and in one subalpine lake that is now at the edge of the oligo- to mesotrophic condition (Lake Maggiore, Italy). Lake water was amended with phosphorus (+P), organic carbon (+C), alone or in combination (+CP), to test for short-term changes (48 hours) in bacteria activity and community structure (CARD FISH). Experiments were carried out in spring and summer. Results showed that bacterial production increased in the +CP treatment in both lakes, and in the +P treatment in the ultroligotrophic lake. In both lakes the bacterial activity increased more rapidly in summer (within 24 hours). Bacteria composition changed in both seasons in all the treatments. At the beginning of the experiments the subclass of ?-Proteobacteria dominated both lakes, while ?-Proteobacteria showed higher percentage in spring in Lake Maggiore and in summer in Lake Guti?rrez. After incubation, in spring and in particular in the +CP treatment, we observed an increase in the relative importance of ?-Proteobacteria in both lakes, whereas in Lake Maggiore this group declined in the summer experiments following an increase in ?-Proteobacteria. All our results indicate the different response of bacterioplankton in systems at the edges of the oligotrophic range

Picocyanobacterial community structure and space-time dynamics in the subalpine Lake Maggiore (N. Italy)

We investigated the community structure of freshwater picocyanobacteria (Pcy) in the oligotrophic subalpine Lake Maggiore (Northern Italy) using the least conserved sequences of the Internal Transcribed Spacer (ITS-1) fragment. The aim was to characterize the succession of Pcy Operational Taxonomic Units (OTUs) during a seasonal cycle at two environmental niches with distinctive light, temperature and mixing characteristics. ITS fragment length outlined a succession of OTUs from spring to summer, even in the absence of a pronounced spring peak. The vertical partitioning of Pcy OTUs down the water column, more evident in summer, indicates different community composition at the two depths. Redundancy Data Analysis (RDA) was carried out using temperature, pH and depth of mixing layer (Zm), which passed the Monte Carlo test (p<0.05). A correlation between axis 1 and temperature, pH and Zm of respectively 0.85, 0.64 and 0.61 was found. Our results indicate that lake thermal structure, defined by temperature and Zm, has a significant influence on the succession of Pcy OTUs and on their dynamics in colonizing different ecological niches in the vertical gradient

Does a barcoding gap exist in Prokaryotes? Evidences from species delimitation in Cyanobacteria

The amount of information that is available on 16S rRNA sequences for prokaryotes thanks to high-throughput sequencing could allow a better understanding of diversity. Nevertheless, the application of predetermined threshold in genetic distances to identify units of diversity (Operative Taxonomic Units, OTUs) may provide biased results. Here we tests for the existence of a barcoding gap in several groups of Cyanobacteria, defining units of diversity according to clear differences between within-species and among-species genetic distances in 16S rRNA. The application of a tool developed for animal DNA taxonomy, the Automatic Barcode Gap Detector (ABGD), revealed that a barcoding gap could actually be found in almost half of the datasets that we tested. The identification of units of diversity through this method provided results that were not compatible with those obtained with the identification of OTUs with threshold of similarity in genetic distances of 97% or 99%. The main message of our results is a call for caution in the estimate of diversity from 16S sequences only, given that different subjective choices in the method to delimit units could provide different results

Il Carbonio organico nel Lago Maggiore: tendenza evolutiva, origine e caratteristiche qualitative

Not availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2013. Il Carbonio organico nel Lago Maggiore: tendenza evolutiva, origine e caratteristiche qualitative. TOC (Total Organic Carbon). TEP (Transparent Exopolymeric Particels). CDOM (Chromophoric Dissolved Organic Matter

Beyond high-resolution geometry in 3D Cultural Heritage: enhancing visualization realism in interactive contexts

La tesi, nell’ambito della computer graphics 3D interattiva, descrive la definizione e sviluppo di algoritmi per un migliore realismo nella visualizzazione di modelli tridimensionali di grandi dimensioni, con particolare attenzione alle applicazioni di queste tecnologie di visualizzazione 3D ai beni culturali

Planificación neodesarrollista y rigidez de la matriz productiva

El proceso de transformación del Estado Neoliberal al Estado Neodesarrollista, modifica a su paso el efecto de las políticas públicas sobre los distintos sectores económicos y sociales, y reestructura las formas que asumen las relaciones al interior de la sociedad. En otros términos, fue mutando el sentido de la estatalidad, y la percepción que la comunidad tiene de ello, en tanto que, a partir de una visión diferente surgen también demandas de nuevo tipo a las instituciones estatales, sea a las existentes u otras nuevas que deben crearse.https://rdu.unc.edu.ar/handle/11086/2768Fil: Callieri, Claudio. Universidad Nacional de Córdoba. Facultad de Ciencias Económicas; Argentina.Administración Públic