1,720,987 research outputs found
Polyphasic characterization of three Leptolyngbya-like strains from the Giant Cave (Trieste, Italy)
No full textThe polyphasic characterization of three Leptolyngbya-like cyanobacteria collected from the Giant Cave (Trieste, Italy) is reported
Phytoplancton de la lagune de Venise. II-Bassin Central (Avril 1989-Mars 1990).
No full textTo continue the research on the lagoonal phytoplanktonic communities, we carried out monthly samplings (from April 1989 to March 1990) on four sampling stations, located in the central basin (Malamocco basin) of the Venice lagoon, during the flood and the ebb tide. The same methods were used during the present work and the previous research to compare the results.
Environmental parameters showed the influence of the sea water also in the inner areas. Phytoplankton was influenced by the environment: there were many eupelagic species; the freshwater species, instead, were not abundant. Phytoplankton was constituted by 258 taxa, 75% of them were diatoms. During the summer the phytoplanktonic densities were often higher than 5x105 cells/ml; during the cold season, we registered high density values only in March, due to a bloom of Skeletonema costatum. This diatom was very abundant during the same period also in the Northern and in the Southern basins of the lagoon. Diatoms were present during all the year with fluctuations different among the stations. Microflagellates sometimes were more abundant than diatoms; the other groups, included Dinoflagellates and Euglenophyceans did not show significant density values
Cicli nictemerali stagionali nella Laguna di Venezia, bacino di Chioggia (Idrologia e fitoplancton).
No full textDuring four different seasonal periods, samplings were carried out in 24 hours in a sampling station located in the Southern basin of the Venice Lagoon to study the variability of the environmental parameters and the quali-quantitative composition of the phytoplankton.
This study was carried out also to compare the results with those obtained during other samplings as far as the flood and ebb tides.
In the study area the results did not follow the cyclicity expected by the tide trend: anomalies and irregularities confirm that in the sampling stations involved in the water transit and during the syzygy, running and rip water mainly influence not only the abiotic parameters but also the phytoplanktonic communities of these environments
A new cryptic species of the unicellular red algal genus Dixoniella (Rhodellophyceae, Proteorhodophytina): Dixoniella giordanoi.
No full textDuring samplings aimed at isolating microalgal strains, a coccoid greyish-green alga was collected along the North Adriatic coasts (Mediterranean Sea, Italy) and grown in culture. The microalgal strain (named strain B1A) was then subjected to an integrative taxonomy approach in order to correctly identify it. Morphological and ultrastructural observations and phycobiliprotein content analysis were carried out, as well as molecular analyses based on the 18S rRNA, rbcL, psbA and plastid-encoded 23S rRNA genes. Phylogenetic placement and ultrastructural observations clearly indicated that strain B1A is a member of the red microalgal genus Dixoniella (Rhodellophyceae, Proteorhodophytina) and is distinct from the only species so far described for this taxon. Therefore, a new species was described to encompass the isolate from the North Adriatic Sea and another isolate from Japan (MF-G2), which was phylogenetically related to strain B1A: Dixoniella giordanoi sp. nov
Temperature effects on growth, metabolome, lipidic profile and photosynthetic pigment content of Microglena antarctica (chlorophyceae): A comprehensive analysis.
Full text linkAntarctic microalgae have evolved a wide range of adaptations to survive at extreme environmental conditions.
This study aimed to explore the physiological and biochemical processes occurring in Microglena antarctica
(Chlorophyceae) in response to changes in temperature. M. antarctica cultivated at three distinct temperatures
(4 ◦C, 8 ◦ C and 16 ◦C) exhibited variations in growth patterns, metabolomes, fatty acid methyl esters (FAMEs)
profile and photosynthetic pigment concentrations. Our results highlighted a decrease in growth at 16 ◦C,
confirming the cryophilic nature of this species. The growth rates at the exponential phase were observed to
decrease progressively with an initial rate of (0.29 ± 0.05 d 1) at the culturing temperature of 4 ◦C, followed by
8 ◦C (0.24 ± 0.09 d 1), and further reduction at 16 ◦C (0.16 ± 0.05 d 1). An integrative untargeted metab-
olomics approach combining mass spectral libraries and novel in–silico tools was employed to improve feature
annotation and to provide additional information on features chemical classes. Significant differences in
M. antarctica annotated compounds, chemical classes and whole metabolomes were observed among 4, 8 and
16 ◦ C. Finally, targeted analyses were performed to evaluate changes in lipid profiles and photosynthetic pigment
content. Higher percentages of polyunsaturated fatty acids (PUFAs) were observed at 4 and 8 ◦C, approximately
65.00 % of total FAMEs, and decreased to 60.71 % at 16 ◦ C. Monounsaturated fatty acids (MUFAs) significantly
increased at 16 ◦C, reaching up to 10.96 % of total FAMEs, in contrast to 4 ◦C and 8 ◦C, where the content of
MUFAs was around 5.00 %. Additionally, chlorophyll a and carotenoid content increased by 50–100 % at 16 ◦C
compared to lower temperatures. The present work highlights temperature–related responses in M. antarctica
biochemical profile, combining untargeted and targeted approaches, and physiology, by growth analysis
Morpho-physiological responses by Isochrysis galbana Parke to different concentrations of oxytetracycline
No full textThis work highlights for the first time the effects of oxytetracycline on the morpho-physiology of the microalga Isochrysis galbana Parke
An insight into the cryptic diversity of Fragilariaceae (Bacillariophyta), with the description of a new Antarctic species, Gedaniella antarctica sp. nov.
No full textFragilariaceae is a paraphyletic family of araphid diatoms commonly used as bio-indicators, in environmental assessments and in paleoenvironmental reconstructions, and with various potential industrial applications. Recent molecular taxonomic research has highlighted significant limitations in traditional morphology-based investigations of these diatom species. Most descriptions of species and genera of the Fragilariaceae present broad morphological character definitions and many diagnostic characters are indistinguishable by light microscopy. In this sense, taxon misidentification is common and could have serious implications for environmental surveys and laboratory experiments. To better understand the diversity of the Fragilariaceae, we (1) performed phylogenetic analyses of the small subunit ribosomal RNA (18S rRNA), rbcL and psbC gene sequences, (2) inferred a cladogram from key morphological features used in the traditional identification of Fragilariaceae, (3) tested if the topologies of the tree recovered from the molecular phylogeny, of the tree based on morphology and of the trees constraining to monophyly the genera Sarcophagodes, Pseudostaurosira and Nanofrustulum (together and separately) were significantly different and (4) mapped morphological character states on the ML tree and inferred their evolution based on maximum parsimony. Our results supported the monophyly of a group of Fragilariaceae within small araphid diatoms including the genera Cratericulifera, Plagiostriata, Castoridens, Opephora, Staurosira, Staurosirella, Punctastriata, Psammotaenia, Hendeyella, Stauroforma, Pseudostaurosira sensu Li, Nanofrustulum sensu Li, Serratifera sensu Li and Gedaniella sensu Li. Molecular phylogeny and topology tests suggested that the latest circumscriptions of the genera Sarcophagodes, Pseudostaurosira and Nanofrustulum sensu Morales were not monophyletic. Analyses of the Antarctic strain IMA070A collected during the XXXIV Italian Antarctic Expedition using fine structural features of the frustule and molecular data revealed that this diatom belongs to a distinct lineage within Gedaniella, which we describe here as Gedaniella antarctica sp. nov
Influenza della marea sul fitoplancton e su alcune variabili ambientali in Valle di Brenta (Laguna di Venezia)
No full textDuring eight seasonal samplings, samples of phytoplankton were collected near the channels feeding the Valle di Brenta, located in the Southern area of the Lagoon of Venice.
The microalgal composition was varied: the Diatoms were present in all seasons, and irregularly but sometimes quantitatively abundant also Euglenophyceae, Cryptophyceae and Chlorophyceae were found. The Dinophyceae, living mostly in the seawater, underwent a great regression. The microflagellates, characterized by organisms belong to different classes and difficult to identify for their small sizes, were abundantly present.
A high specific diversity was always registered with rare blooms. A constant correspondence between phytoplanktonic abundance and direction of tide current was not observed. The different phytoplankton values registered in the sampling stations were due to the different water origin and, consequently to the environmental conditions
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