Olimpia Coppellotti

A microworld in Triassic amber

Amber provides an effective medium for conservation of soft-bodied microorganisms, but finds older than 135 million years are very rare and have not so far contained any microbial inclusions. Here we describe 220-million-year-old droplets of amber containing bacteria, fungi, algae and protozoans that are assignable to extant genera. These inclusions provide insight into the evolution and palaeoecology of Lower Mesozoic microorganisms: it seems that the basal levels of food webs of terrestrial communities (biocoenoses) have undergone little or no morphological change from the Triassic to the Recent.

Ciliate colonization of artificial substrates in the Lagoon of Venice

In work performed during the period February–October 1996, about 47 species of ciliates were detected in the communities of Aufwuchs , or periphyton, colonizing glass substrates submerged in three sites in the Lagoon of Venice, two in the urban area of Chioggia and one at a mussel-farming site. The ciliate communities were composed of sessile forms of Peritrichia and Suctoria and of motile ciliates, belonging especially to Hypotrichia and Karyorelictea. Four species of the peritrich Zoothamnium and the suctorians Acineta tuberosa and Ephelota gemmipara are reported here for the first time in the Lagoon of Venice. The richest ciliate communities were recovered at 60 cm from the bottom. Processed by multivariate analysis, data of samplings performed up to day ten from the positioning of glass slides indicated significant differences in biotic and physico-chemical parameters, according to season. The first data did not give definite indications on the possibility of using ciliates colonizing solid surfaces to assess the quality of this peculiar environment.

Response to heavy metals in organisms—I. Excretion and accumulation of physiological and non physiological metals in Euglena gracilis☆

Abstract Euglena gracilis was cultured with different concentrations of an essential metal and a non essential one: Cu and Cd. Cu even at high concentrations did not affect the growth rate, while Cd reduced it according to the concentration used. Cu concentration stayed always lower in the cells than in the medium, instead Cd was accumulated in the cells. From cells and medium of cultures treated with copper a glycopeptide which chelated copper and zinc was isolated. It was present in the control culture too, but it linked only Zn; its molecular weight is lower than 10,000 D. From cells cultured with Cd a compound of a very high molecular weight (higher than 100,000 D) was isolated: it linked Cd and Zn. The concentration of Zn in the medium and in the cells linked to the compounds is also discussed, and a model is proposed for regulation of physiological metals in organisms; it may explain how detoxification relates to regulation of heavy metals.

Novel, Meso-Substituted Cationic Porphyrin Molecule for Photo-Mediated Larval Control of the Dengue Vector Aedes aegypti

Background Control of the mosquito vector population is the most effective strategy currently available for the prevention of dengue fever and the containment of outbreaks. Photo-activated oxidants may represent promising tools for developing effective, safe and ecofriendly novel larvicides. The purpose of this study was to evaluate the potential of the synthetic meso-substituted porphyrin meso-tri(N-methylpyridyl), meso-mono(N-tetradecylpyridyl)porphine (C14) as a photoactivatable larvicide against the dengue vector Aedes (Stegomyia) aegypti. Methodology The photophysical and photochemical properties of the C14 molecule were assessed spectrophotometrically. Photomediated larvicidal efficacy, route of intake and site of action were determined on Ae. aegypti larvae by laboratory bioassays and fluorescence microscopy. Using powdered food pellet for laboratory rodents (a common larval food used in the laboratory) as a carrier for C14, loading-release dynamics, larvicidal efficacy and residual activity of the C14-carrier complex were investigated. Main Findings The C14 molecule was found to exert a potent photosensitizing activity on Ae. aegypti larvae. At irradiation intervals of 12 h and 1 h, at a light intensity of 4.0 mW/cm2, which is 50–100 times lower than that of natural sunlight, LC50 values of 0.1 µM (0.15 mg/l) and 0.5 µM (0.77 mg/l) were obtained, respectively. The molecule was active after ingestion by the larvae and caused irreversible, lethal damage to the midgut and caecal epithelia. The amphiphilic nature of C14 allowed a formulate to be produced that not only was as active against the larvae as C14 in solution, but also possessed a residual activity of at least two weeks, in laboratory conditions. Conclusions The meso-substituted synthetic porphyrin C14, thanks to its photo-sensitizing properties represents an attractive candidate for the development of novel photolarvicides for dengue vector control.

Photosensitization of Colpoda inflata cysts by meso-substituted cationic porphyrins

Colpoda inflata cysts accumulate significantly large amounts of meso-substituted cationic porphyrins, including meso-tetrakis(N-methyl-4-pyridyl)porphine (TMP-C1) and its mono-N-methyldecyl (TMP-C10) and -tetradecyl (TMP-C14) analogues upon incubation for 1 h with 1-48 microM porphyrin concentrations. All three porphyrins at concentrations greater than 10 microM exhibited a significant toxicity toward the cysts, in particular lowering the degree of excystment. Upon visible light irradiation of the porphyrin-loaded cysts, extensive photodamage was observed even in the presence of 1 microM porphyrin, as shown by light microscopy observations and counting of vegetative emerging cells The presence of one decyl or tetradecyl hydrocarbon chain caused about 10-fold enhancement of the phototoxic effects.

Glutathione, cysteine and acid-soluble thiol levels in Euglena gracilis cells exposed to copper and cadmium

Abstract 1. The trend of the total acid-soluble thiols (AST) levels including glutathione (both in reduced form, GSH, and in the oxidized one, GSSG) and free cysteine (CySH) has been studied in Euglena gracilis cells exposed to copper or cadmium up to the fifth day of growth. 2. The copper does not affect the levels of AST and of glutathione. A limited increase of CySH is observed during the first days of growth. This is followed by a gradual depletion for longer times. 3. The exposure to cadmium leads to an increase in the content of AST as well as of glutathione and CySH levels according to the metal dose and to the exposure time. 4. The data are interpreted taking into account the previous observations on the responses of Euglena gracilis to exposure to heavy metals.

Photosensitized inactivation of Acanthamoeba palestinensis in the cystic stage

Aims:  To develop alternative approaches for medical and environmental control of pathogenic Acanthamoeba spp. by means of photodynamic treatment with a tetracationic Zn(II)‐phthalocyanine (RLP068).

Phthalocyanine-photosensitized inactivation of a pathogenic protozoan, Acanthamoeba palestinensis.

Incubation of Acanthamoeba palestinensis cells with a tetracationic phthalocyanine (RLP068) at concentrations ranging between 0.2 and 1.0 microM, caused a ready uptake of the photosensitizer with recoveries of the order of 0.5-2.5 nmol per mg of cell protein. The amount of cell-bound phthalocyanine did not appreciably change with incubation times ranging between 0.5 and 3 h. Fluorescence microscopic investigations showed an obvious accumulation of the phthalocyanine at the level of the vacuolar membranes. A nearly complete photoinduced cell death occurred upon irradiating A. palestinensis cells with 600-700 nm light with a total energy of 15-30 J cm(-2) using 1.0 microM RLP068 in the incubation medium. DAPI staining of the photosensitized cells indicates significant damage of the nucleus. On the other hand, photosensitization of the protozoan cells does not directly involve the mitochondria as shown by the lack of photoinduced decrease in the activity of typical mitochondrial enzymes, such as NADH dehydrogenase and citrate synthase.

Effects of a new photoactivatable cationic porphyrin on ciliated protozoa and branchiopod crustaceans, potential components of freshwater ecosystems polluted by pathogenic agents and their vectors

The increasing use of photosensitized processes for disinfection of microbiologically polluted waters requires a precise definition of the factors controlling the degree of photosensitivity in target and non-target organisms. In this regard, tests with protozoa and invertebrates which have a natural habitat in such waters may be used as first screening methods for the assessment of possible hazards for the ecosystem. A new cationic porphyrin, namely meso-tri(N-methyl-pyridyl)mono(N-dodecyl-pyridyl)porphine (C12), is tested in this work on the protozoan Ciliophora Colpoda inflata and Tetrahymena thermophila and the Crustacea Branchiopoda Artemia franciscana and Daphnia magna. The protocol involved 1 h incubation with porphyrin doses in the 0.1-10.0 μM range and subsequent irradiation with visible light at a fluence rate of 10 mW cm(-2). The results indicate that C12 porphyrin has a significant affinity for C. inflata and T. thermophila; this is also shown by fluorescence microscopic analyses. C. inflata cysts were resistant to the phototreatment up to a porphyrin dose of 0.6 μM. The effects of C12 on cysts have been evaluated at 3 and 24 h after the end of the phototreatment; a delay in the excystment process was observed. T. thermophila was fairly resistant to the phototreatment with C12 porphyrin. The data obtained with the two crustaceans indicated that the effects of dark- and photo-treatment with C12 need to be closely examined for every organism. A. franciscana is more resistant, probably owing to its ability to adapt to extreme conditions, while the high level of photosensitivity displayed by Daphnia magna represents a potential drawback, as this organism is often selected as a reference standard for assessing the environmental safety. Thus, while C12 photosensitisation can represent a useful tool for inducing a microbicidal or larvicidal action on polluted waters, the irradiation protocols must be carefully tailored to the nature of the specific water basin, and in particular to its biotic characteristics.

Description of Uronema marinum (Ciliophora, Scuticociliatida) from the Antarctica and observations on the nuclear events in conjugation

SummaryThe morphology is described of a scuticociliate, isolated from a sediment from Terra Nova Bay, Ross Sea, in the Antarctica. The studies, using light microscopy of silver impregnated specimens and by scanning electron microscopy, permit an assignment to the species, Uronema marinum. The main steps of micronuclear events during conjugation, that appear to be similar to the general plan of Tetrahymena and Paramecium aurelia complex, are shown.