Emanuela Moschin

Diatoms and dinoflagellates in Terra Nova Bay (Ross Sea-Antarctica) during austral summer 1990

During January/February 1990 the floristic composition and biomass of diatoms and dinoflagellates in Terra Nova Bay (Ross Sea) were investigated. The study area included eight stations, seven of which were inshore and one offshore. Of the 94 taxa identified, 58 were diatoms and 34 were dinoflagellates. Cell densities were higher in surface layers and particularly at two stations, one located at the centre of the bay, and the other to the south of the Terra Nova station. While density data showed that the diatoms predominated over the dinoflagellates and over Phaeocystis sp., the biomass values were largely made up of the dinoflagellates contribution.

Colonization by diatoms and antirheumatic activity of thermal mud.

We have identified diatoms among other thermophilic microorganisms as the main agents for the colonization of thermal mud resulting in a ‘maturation’ which renders the mud suitable to be used for mud‐pack treatment of osteoarthrosis patients. The main effects of the diatom growth are the progressive enrichment of mud extracts in chlorophyll a parallel to the building up of a sulfoglycolipid endowed with an anti‐inflammatory action. The sulfoglycolipid was also produced by diatoms isolated from the mud and cultivated in vitro. Copyright

Pyramimonas australis sp. nov. (Prasinophyceae, Chlorophyta) from Antarctica : fine structure and molecular phylogeny

An undescribed marine Pyramimonas, P. australis Andreoli et Moro, sp. nov., forming a bloom in a hole of Terra Nova Bay (Ross Sea, Antarctica) sea ice, was collected, but could not be cultured. Consequently, the description of this new species is based on light and electron microscope observations on samples that were fixed or stored at −80  °C, and its phylogenetic position inferred from nuclear-encoded small-subunit ribosomal DNA (SSU rDNA) and chloroplast-encoded rbcL gene sequences. This is the third Antarctic species described for this genus. The ultrastructure of the cell is consistent with species of the subgenus Trichocystis McFadden, but differs in that it has unique body and cyst scales, and a different encystment procedure. The outermost layer of body scales is formed by flat box scales with peripheral perforations oriented parallel to the four edges and with a further eight central perforations oriented perpendicular to the peripheral ones. Crown scales, which in many other species of the genus form the outermost layer over the entire cell body, were observed in this species in the flagellar pit over the box scales. The flagella are covered by a pentagonal underlayer of scales and by limuloid scales with two subsidiary spines, in addition to the central one. Encystment begins in the flagellate form resulting in a cyst with an irregular wall bearing spine scales. Ultrastructural and molecular data confirm that P. australis belongs to the subgenus Trichocystis.

Morpho-physiological effects of ibuprofen on Scenedesmus rubescens

The pollution of aquatic bodies by drugs is an emerging environmental problem, because of their extensive use in animal and human context. Ibuprofen, 2-[4-(2-methylpropyl)phenyl]propanoic acid, is the non-steroidal anti-inflammatory drug mainly present both in wastewater and in rivers and lakes in Europe. Since in literature there is little information about the effects of ibuprofen on microalgae, in this paper we presented the results on the effects of this molecule at different concentrations (62.5μgL(-1), 250μgL(-1) and 1000μgL(-1)) on cultures of the freshwater microalga Scenedesmus rubescens (P.J.L. Dangeard) E. Kesslet et al. Ibuprofen effects on the alga were assayed at first through analyses of the growth curve. Moreover, analyses of cell morphology, ultrastructure, and photosynthetic pigments were additionally performed. The first negative effect of the drug was on the microalga growth, suggesting a drug action dose-dependent mechanism type, more evident at the concentration of 1000μgL(-1) ibuprofen and in the last phase of the growth curve. In support of this, following ibuprofen exposure, the cells exhibited morphological and ultrastructural alterations, mainly consisting in large cytoplasmic inclusions, probably of lipids and/or carotenoids. The decrease of chlorophyll amounts and, on the contrary, the increase of carotenoids were correlated with a stressful condition induced by drug.

RESULTATS PRELIMINAIRES SUR LES DIATOMEES BENTHIQUES DE SUBSTRATS MEUBLES DANS LA LAGUNE DE VENISE, ITALIE (MARS 1994–JANVIER 1995)

Research on samples from the Venice lagoon was carried out to determine a suitable method for the quali-quantitative evolution of diatoms living within the sediments. From March 1994 to March 1995, surface sediment samples were collected monthly from a station located in the southern basin of the lagoon. Samples were observed using both light and scanning electron microscope. A list of the taxa found during this research is reported; counts of diatoms present in a volume of sediment were also carried out. Values for cell numbers ranged from 0.2 × 106 to 1.8 × 106 cells/cm3; higher values were recorded in spring/summer and lower values in autumn/winter. Many species belonged to the nannophytobenthos (< 30 μm), which better adapted to move among the grains of sediment than larger species. Benthic taxa, belonging to the centric group of diatoms, were also found.

DISTRIBUTION DES DIATOMÉES BENTHIQUES DE SUBSTRATS MEUBLES DANS LE BASSIN SUD DE LA LAGUNE DE VENISE, ITALIE

The following work points out the results on the microalgae living in the sediments of three sampling stations located at a different distance from the opening of Chioggia harbour-channel (south basin of Venice lagoon). The three examinated areas are characterized by a different granulometry and are differently interested by the supplies of both sea and continental waters. The samplings were made seasonally (March, June, September, December) by taking samples of sediments, from which sub samples were obtained at several levels (0 cm, −6 cm, −12 cm). Besides the identification and the counting (cells mm−3) of the microalgae, almost all belonged to Diatoms, the chlorophyll a concentration as well as the quantity of organic matter and the biomass were determined. The obtained results demonstrated the role of the grain sizes of the solid matrix on the colonization by Diatoms; density values, ranged from 18 to 700 cells mm−3, were higher in the sediments having a reduced granulometry and characterized by high organic matter values. This is important for those species living in the sediments and able to survive in absence of light, using metabolic adaptations that allow the shift to a heterotrophic nutrition. The most important species were Achnanthes delicatula, Amphora exigua, Cocconeis molesta, C. scutellum, Navicula cryptocephala and N. cincta. The comparison among chlorophyll a concentrations as well as biomass values with density data seem to be very difficult to compare.

Cryptic Cyanobacterial Diversity in the Giant Cave (Trieste, Italy): The New Genus Timaviella (Leptolyngbyaceae)

Abstract The microflora of hypogean environments has been studied increasingly worldwide. However, some sites have hardly been examined or not studied at all; this is the case for the Giant Cave, a Karst show cave located near Trieste, Italy. In the present study we began characterizing the Giant Cave Lampenflora by using a polyphasic approach, focusing, in particular, on three Leptolyngbya-like strains named GR2, GR4, and GR13. Light and electron microscopic observations were carried out and the water-soluble pigment composition was analysed. Phylogenetic reconstruction, based on the 16S rRNA gene and the 16S-23S ITS region, was performed to better understand the taxonomic position of these strains, complemented by 16S-23S ITS secondary structure analysis. Ecological and geographical data for the investigated strains and for the other cyanobacterial strains grouping with them in the phylogenetic reconstructions were also considered. Based on the results, strain GR2 was ascribed to the species Heteroleibleinia purpurascens (Hansgirg) Anagnostidis & Komárek; strains GR4 and GR13 were attributed to a new genus of the family Leptolyngbyaceae, Timaviella Sciuto & Moro, gen. nov., and represented two distinct species: Timaviella circinata Sciuto & Moro and Timaviella karstica Sciuto & Moro.

Three pennate diatoms from Ischia Thermal District (Naples, Italy).

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Further surveys of Pseliodinium vaubanii Sournia (Pirrophyta) in the Adriatic sea

Abstract The presence, in the North Adriatic sea and in the Chioggia and Marano lagoons, of Pseliodinium vaubanii a rare dinoflagellate species, is reported. Our results showed that Pseliodinium vaubanii is a very frequent and abundant species in these environments.