Domenico Davolos

Isolation by distance in equilibrium and nonequilibrium populations of four talitrid species in the Mediterranean Sea.

Abstract Allozymic variation at 21–23 loci was studied in 28 populations of Talitrus saltator, 23 populations of Orchestia montagui, 13 populations of O. stephenseni, and five populations of Platorchestia platensis from the Mediterranean Basin. Different levels of gene flow (Nmθ) were detected within each species at the scale of the whole Mediterranean: O. montagui and P. platensis had low population structure, with levels of Nmθ 1, whereas the T. saltator and O. stephenseni populations have values of Nmθ < 1. The relationship between Nmθ and geographic distance was analyzed to test for the presence of an isolation by distance pattern in the spatial genetic variation within each species. A model of isolation by distance is useful to describe the pattern of genetic structuring of study species at the scale of the whole Mediterranean: geographic distance explained from 28% to 70% of the variation in gene flow. In the Aegean area all species showed an island model of genetic structuring regardless of the levels of gene flow.

Phylogenetic analysis on the arsenic-resistant bacteria isolated from three different freshwater environments

Several aquatic environments are arsenic (As)-contaminated by geochemical sources and by residues derived from industrial and agricultural activities. In the current study, arsenic-resistant bacterial strains were isolated from Lake Albano, the Tiber River and a freshwater well (Bassano Romano), three sites located in the Latium region, central Italy, in which volcanic formations and aquifers containing As contribute to water As contamination. Bacteria capable of either oxidising As(III) or reducing As(V) belonged, on the basis of the 16S rRNA gene sequences, to the Proteobacteria, Firmicutes and Bacteroidetes. Moreover, phylogenetic analysis conducted on the gene codifying the ArsB, an As(III) efflux membrane protein pump related to the arsenic resistance, suggested the occurrence of horizontal arsB transfer events for some of the examined environmental strains, even among taxa belonging to taxonomically distant bacteria. Overall, these results showed that in each of the environments investigated, bacteria related to the redox of As coexisted, confirming important roles of microbial populations in the speciation of As and increasing the knowledge in view of the bioremoving of As compounds.

Arsenic removal from naturally contaminated waters: a review of methods combining chemical and biological treatments

The presence of arsenic (As) in aquatic environments is often attributable to geogenic processes occurring within aquifers. Arsenic exists in two prevalent oxidation states, with the trivalent arsenite [As(III)] exerting stronger toxicity effects on the aquatic biota than the pentavalent arsenate [As(V)]. The review evaluates the literature available on the main arsenic removal technologies and the application of combined chemical and biological treatments. We provide a synthetic outlook on the potential strategies of biological As(III) oxidation to As(V) by means of cell-detoxifying mechanisms or metabolic processes with the aim to enhance As removal efficiency. Furthermore, the role of microorganisms in the mobility of arsenic in natural systems as well as the distribution of As-resistant bacteria, potentially suitable for arsenic removal, is discussed in the context of a case study carried out in Latium region (Italy), which is known for arsenic contamination of waters.

A molecular and bioinformatic study on the ochratoxin A (OTA)-producing Aspergillus affinis (section Circumdati)

Aspergillus affinis (section Circumdati) is a novel ochratoxin A (OTA)-producing species found in submerged riparian decomposing leaves. However, very little is known about its role on the breakdown of plant debris and its ability to degrade carbohydrate polymers. Moreover, its OTA biosynthetic pathway has not yet been explored. In the present paper, we investigated the gene encoding the extracellular alpha-amylase (amyAa) of A. affinis within the evolution of the Aspergillus lineages in relation to the possible use of this enzyme in starch processing. The novel amyAa, despite being related to branches of the Aspergillus species of the sections Terrei and Flavi, formed a distinct phylogenetic branch, which may be of outstanding importance from a biotechnological point of view. Moreover, we identified the polyketide synthase gene (pks) putatively required for the first step of OTA biosynthesis in A. affinis. This otapks was examined in relation to a limited number of orthologous genes available from Aspergillus species of the sections Circumdati and Nigri. Our study highlights the importance of otapks as target genes in the treatment of ochratoxigenic Aspergillus species on a more comprehensive evolutionary basis.

Arsenic-contaminated freshwater: assessing arsenate and arsenite toxicity and low-dose genotoxicity in Gammarus elvirae (Crustacea; Amphipoda)

Arsenic (As) contamination of freshwater is largely due to geogenic processes, but As is also released into the environment because of improper anthropic activities. The European regulatory limits in drinking water are of 10 μg L−1 As. However, knowledge of the genotoxic effects induced by low doses of As in freshwater environments is still scanty. This study was designed to investigate arsenate (As(V)) and arsenite (As(III)) toxicity and low-dose genotoxicity in Gammarus elvirae, which has proved to be a useful organism for genotoxicity assays in freshwater. As(V) and As(III) toxicity was assessed on the basis of the median lethal concentration, LC(50), while estimates of DNA damage were based on the Comet assay. The G. elvirae LC (50–240 h) value we calculated was 1.55 mg L−1 for As(V) and 1.72 mg L−1 for As(III). Arsenic exposure (240 h) at 5, 10, and 50 µg L−1 of As in assays with either arsenate or arsenite-induced DNA damage in hemocytes of G. elvirae in a concentration-dependent manner. Our study provides a basis for future genotoxic research on exposure to freshwater that contains low levels of arsenic.

Molecular and phylogenetic analysis on bacterial strains isolated from a PAHs wastewater treatment plant

In this contribution we summarize results of molecular and phylogenetic analysis conducted on hydrocarbon degrading bacteria sampled from a polycyclic aromatic hydrocarbons (PAHs) wastewater treatment plant in Italy. The bacterial strains showed high 16S rRNA gene sequence identity to described taxa from the GenBank (NCBI) belonging to the Achromobacter, Acinetobacter, Bacillus, Cellulosimicrobium, Gordonia and Pseudomonas genera. Moreover, catabolic genes for the hydrocarbon metabolism were investigated through PCR amplification and DNA sequencing. Finally, for the Achromobacter sp. strain LU6 and Pseudomonas sp. strains LU7 and LU9 phylogenetic inferences were obtained on the genes encoding NOx reductases of the denitrification pathway. The obtained molecular data are addressed to design oligonucleotides for the simultaneous detection by DNA microarray screening of specific genes in hydrocarbon-degrading bacteria.

Cryptorchestia ruffoi sp. n. from the island of Rhodes (Greece), revealed by morphological and phylogenetic analysis (Crustacea, Amphipoda, Talitridae)

Abstract A new Cryptorchestia species, Cryptorchestia ruffoi Latella & Vonk, sp. n. from the island of Rhodes in south-eastern Greece, can be distinguished on the basis of morphological and phylogenetic data. Morphological analysis and DNA sequencing of mitochondrial and nuclear protein-coding genes indicated that this species is related to Cryptorchestia cavimana (Cyprus) and Cryptorchestia garbinii (Mediterranean regions, with a recent northward expansion). Results supported a genetic separation between the Cryptorchestia species of the east Mediterranean regions and those of the northeast Atlantic volcanic islands examined in this study (Cryptorchestia canariensis, Cryptorchestia gomeri, Cryptorchestia guancha, and Cryptorchestia stocki from the Canary islands, Cryptorchestia monticola from Madeira, and Cryptorchestia chevreuxi from the Azores). The Mediterranean and Atlantic Cryptorchestia species appear to be also morphologically distinct. Cryptorchestia ruffoi sp. n., Cryptorchestia cavimana, Cryptorchestia garbinii, and Cryptorchestia kosswigi (Turkish coast) clearly have a small lobe on the male gnathopod 1 merus. This character was the main diagnostic difference between Cryptorchestia (sensu Lowry, 2013) and Orchestia. However, among the six northeast Atlantic island Cryptorchestia species only Cryptorchestia stocki has a small lobe on the merus of gnathopod 1. Reduction or loss of the lobe in the Atlantic Island species cannot be ruled out; however, molecular phylogenetic analysis leads us to presume that this lobe independently evolved between the east Mediterranean Cryptorchestia species and Cryptorchestia stocki from Gran Canaria.

The name of a model species: the case of Orchestia cavimana (Crustacea: Amhipoda: Talitridae)

Abstract The species commonly known as Orchestia cavimana belonging to the Talitridae family (Amphipoda) has been used as crustacean model species. Here, we point out that this talitrid amphipod species is related to species in the genus Orchestia but now falls under what is described as Cryptorchestia garbinii, which is a different species from the nominal species Cryptorchestia cavimana endemic to the Island of Cyprus. It is therefore important that future basic research and applied studies involving this model organism refer to it as C. garbinii. Its old assignment O. cavimana, or even C. cavimana, as still reported in the National Center for Biotechnology Information (NCBI) GenBank and in recent papers, may lead to confusion.

On the molecular and morphological evolution of continental and insular Cryptorchestia species, with an additional description of C. garbinii (Talitridae)

Abstract Semi-terrestrial talitrid amphipods of the genus Cryptorchestia (sensu Lowry and Fanini 2013) associated with freshwater-soaked leaf litter were known to occur in inland lakes of Turkey and at the shores of the Black Sea. Before 2013 they had been reported as Orchestiacavimana and later as Cryptorchestiacavimana. In our phylogenetic tree, inferred from a mitochondrial and nuclear gene dataset (cytochrome oxidase I (COI), and histone H3 (H3), respectively), we show that these Turkish populations belong to Cryptochestiagarbinii, a common and widespread continental species, which is closely related to C.cavimana (endemic to Cyprus) and C.ruffoi (endemic to Rhodes). For the Turkish and European populations of C.garbinii, we found low levels of both genetic differentiation and morphological variation, and an age-related size variability (increasing at each moult) of the small lobe in the male gnathopod I merus, the main taxonomically diagnostic character for Cryptorchestia. A mainland (C.garbinii) versus insular isolation and in situ speciation (C.cavimana, and C.ruffoi) in the two east Mediterranean islands of Cyprus and Rhodes is discussed in relation to terrestrial Cryptorchestia species endemic to North East Atlantic volcanic islands (Azores, Canary Islands, and Madeira). The incorporation of five Mediterranean and Atlantic Orchestia species in the Bayesian analysis of the two genes (COI, and H3) indicated that both genera Orchestia and Cryptorchestia are not monophyletic.