Publications by authors named "Giuseppe Nascetti"

69 Publications

Investigating the genetic structure of the parasites Anisakis pegreffii and A. berlandi (Nematoda: Anisakidae) in a sympatric area of the southern Pacific Ocean waters using a multilocus genotyping approach: first evidence of their interspecific hybridization.

Infect Genet Evol 2021 Aug 30;92:104887. Epub 2021 Apr 30.

Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Laboratory affiliated to "Istituto Pasteur Italy - Fondazione Cenci-Bolognetti", P.le Aldo Moro 5, 00185 Rome, Italy. Electronic address:

The southern Pacific Ocean, off the New Zealand coast, has been reported as one sympatric area of the two parasite species Anisakis pegreffii and A. berlandi. Here, a multilocus genotyping approach, based on a panel of eleven DNA microsatellite (SSR) loci plus the sequences analysis of the nuclear nas10 nDNA and the mitochondrial mtDNA cox2 gene loci, was applied to a total of N = 344 adults and larvae of Anisakis spp. from cetacean and fish species, respectively. Out of the newly scored SSR loci, Anisl 15 and Anisl 2 showed fixed alternative alleles between A. pegreffii and A. berlandi resulting as 100% diagnostic loci. Out of SSRs Anisl 00314 and Anisl 7 previously disclosed, two additional loci, i.e., Anisl 4 and Anisl 22, were found to be sex-linked. The Bayesian genotypes clustering approach (STRUCTURE) allowed identification, with a 100% of probability value, N = 208 specimens to the "pure parental" A. pegreffii, N = 133 to the "pure parental" A. berlandi, while one adult and two larval stages showed mixed ancestry between the two groups having, in all cases, a Q-value = 0.50. NEWHYBRIDS analysis assigned (100% of probability) those specimens to their F1 hybrid category. This represents the first evidence of contemporary hybridization between the two parasite species in a sympatric area. The pairwise F values estimated at intraspecific and interspecific level, inferred from both SSR loci and mitochondrial mtDNA cox2 sequences, have also demonstrated the existence of two distinct panmictic units in this study area, corresponding respectively to A. pegreffii and A. berlandi. The results obtained support the useful application of a multilocus approach in the identification of sibling species and their hybrid categories in sympatric areas. The possible use of sex-linked SSR loci of the two species of the A. simplex (s. l.), for sex determination of their larval stages, is also suggested.
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http://dx.doi.org/10.1016/j.meegid.2021.104887DOI Listing
August 2021

A novel nuclear marker and development of an ARMS-PCR assay targeting the metallopeptidase 10 (nas 10) locus to identify the species of the Anisakis simplex (s. l.) complex (Nematoda, Anisakidae).

Parasite 2020 26;27:39. Epub 2020 May 26.

Department of Public Health and Infectious Diseases, Section of Parasitology, "Sapienza - University of Rome", Piazzale Aldo Moro 5, 00185 Rome, Italy.

The genus Anisakis represents one of the most widespread groups of ascaridoid nematodes in the marine ecosystem. Three closely related taxa are recognized in the Anisakis simplex (s. l.) complex: A. pegreffii, A. simplex (s. s.) and A. berlandi. They are widely distributed in populations of their intermediate/paratenic hosts (fish and squids) and definitive hosts (cetaceans). A novel nuclear gene locus, metallopeptidase 10 (nas 10) (451 bp), was sequenced and validated on a total of 219 specimens of the three species of Anisakis, collected in fish and cetacean hosts from allopatric areas included in their ranges of distribution. The specimens of Anisakis were first identified by allozymes and sequence analysis of the mtDNA cox2 and EF1α-1 nDNA. The novel nuclear marker has shown fixed alternative nucleotide positions in the three species, i.e. diagnostic at 100%, permitting the species determination of a large number of specimens analyzed in the present study. In addition, primers to be used for amplification-refractory mutation system (ARMS) PCR of the same gene locus were designed at these nucleotide positions. Thus, direct genotyping determination, by double ARMS, was developed and validated on 219 specimens belonging to the three species. Complete concordance was observed between the tetra-primer ARMS-PCR assays and direct sequencing results obtained for the nas 10 gene locus. The novel nuclear diagnostic marker will be useful in future studies on a multi-locus genotyping approach and also to study possible hybridization and/or introgression events occurring between the three species in sympatric areas.
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http://dx.doi.org/10.1051/parasite/2020033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249699PMC
December 2020

Differences in Gene Expression Profiles of Seven Target Proteins in Third-Stage Larvae of (Sensu Stricto) by Sites of Infection in Blue Whiting ().

Genes (Basel) 2020 05 17;11(5). Epub 2020 May 17.

Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, 00185 Rome, Italy.

The third-stage larvae of the parasitic nematode genus tend to encapsulate in different tissues including the musculature of fish. Host tissue penetration and degradation involve both mechanic processes and the production of proteins encoded by an array of genes. Investigating larval gene profiles during the fish infection has relevance in understanding biological traits in the parasite's adaptive ability to cope with the fish hosts' defense responses. The present study aimed to investigate the gene expression levels of some proteins in L3 of (s.s.) infecting different tissues of blue whiting , a common fish host of the parasite in the NE Atlantic. The following genes encoding for spp. proteins were studied: Kunitz-type trypsin inhibitor (), hemoglobin (), glycoprotein (), trehalase (), zinc metallopeptidase 13 (), ubiquitin-protein ligase () and sideroflexin 2 (). Significant differences in gene transcripts (by quantitative real-time PCR, qPCR) were observed in larvae located in various tissues of the fish host, with respect to the control. ANOVA analysis showed that relative gene expression levels of the seven target genes in the larvae are linked to the infection site in the fish host. Genes encoding some of the target proteins seem to be involved in the host tissue migration and survival of the parasite in the hostile target tissues of the fish host.
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http://dx.doi.org/10.3390/genes11050559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7288290PMC
May 2020

Genetic identification and insights into the ecology of Contracaecum rudolphii A and C. rudolphii B (Nematoda: Anisakidae) from cormorants and fish of aquatic ecosystems of Central Italy.

Parasitol Res 2020 Apr 2;119(4):1243-1257. Epub 2020 Apr 2.

Department of Ecological and Biological Sciences, Tuscia University, Viale dell'Università s/n, 01100, Viterbo, Italy.

Contracaecum rudolphii (s. l.) is a complex of sibling species of anisakid nematodes having the fish-eating birds belonging to the Family Phalacrocoracidae as final hosts. The great cormorant Phalacrocorax carbo sinensis is parasitized by C. rudolphii A and C. rudolphii B. Adults and L4 specimens of C. rudolphii (s. l.) (N = 3282) were collected in cormorants from brackish and freshwater ecosystems of Central Italy. Third-stage larvae of Contracaecum (N = 882) were obtained from the fish species Dicentrarchus labrax, Anguilla anguilla, Aphanius fasciatus, Atherina boyeri, Leuciscus cephalus, Barbus barbus, and Carassius carassius captured in the same geographical areas of cormorants' standings. Contracaecum rudolphii A and C. rudolphii B were identified by a multilocus genetic approach: allozymes, sequences analysis of the mtDNA cox2, and ITS region of rDNA gene loci. Differential distribution of the two parasite species was observed in different aquatic environments. Contracaecum rudolphii B outnumbered C. rudolphii A in wintering cormorants from freshwater ecosystems; the opposite trend was found in cormorants from brackish water. Analogously, C. rudolphii A larvae were more prevalent in brackish water fish, while C. rudolphii B larvae were found infecting only freshwater fish. The findings seem to confirm that C. rudolphii A and C. rudolphii B would have a life-cycle adapted to brackish and freshwater environments, respectively. A differential feeding behavior of wintering cormorants, the ecology of the infected fish species, and abiotic factors related to early stages of the parasites are supposed to maintain the distinctiveness of the two parasite species' life cycles in the two different aquatic ecosystems.
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http://dx.doi.org/10.1007/s00436-020-06658-8DOI Listing
April 2020

Cross-species utility of microsatellite loci for the genetic characterisation of Anisakis berlandi (Nematoda: Anisakidae).

Parasite 2020 11;27. Epub 2020 Feb 11.

Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza-University of Rome, P.le Aldo Moro 5, 00185 10 Rome, Italy.

Eight microsatellite loci, recently developed in the species Anisakis pegreffii, were successfully amplified in Anisakis berlandi, sibling species of the A. simplex (s. l.) complex. They were validated on adult specimens (n = 46) of the parasite species, collected from two individuals of the definitive host, the long-finned pilot whale Globicephala melas from New Zealand waters. Among the eight loci scored, one, Anisl 07132, had null alleles in A. berlandi and was thus excluded from the subsequent genetic analysis. Two loci, Anisl 00314 and Anisl 10535, were monomorphic. In addition, as also previously detected in the other species of the A. simplex (s. l.) complex, the Anisl 7 locus was seen to be sex-linked, showing hemizygosity in male specimens. Differential allele frequency distributions of A. berlandi, with respect to those previously observed in A. pegreffii and A. simplex (s. s.), were found at some microsatellite loci. The Anisl 7 locus provided 100% diagnosis between A. berlandi and A. pegreffii, while others resulted in 99% diagnosis between A. berlandi and the other two species. Simple sequence repeat (SSR) loci also allowed us to estimate the genetic differentiation of A. berlandi from A. pegreffii (F  ≈ 0.45, Dc = 0.82) and A. simplex (s. s.) (F  ≈ 0.57, Dc = 0.73). The results suggest that SSRs provide a set of candidate markers for population genetics analysis of A. berlandi, as well as for the investigation, through a multi-locus genotyping approach, of possible patterns of hybridisation/introgression events between A. berlandi and the other two Anisakis species in sympatric conditions.
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http://dx.doi.org/10.1051/parasite/2020004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7011781PMC
September 2020

Gene expression profiles of antigenic proteins of third stage larvae of the zoonotic nematode Anisakis pegreffii in response to temperature conditions.

Parasite 2019 23;26:52. Epub 2019 Aug 23.

Department of Public Health and Infectious Diseases, Section of Parasitology, and "Umberto I" Academic Hospital "Sapienza - University of Rome", P.le Aldo Moro, 5, 00185 Rome, Italy.

Anisakis pegreffii, a recognised etiological agent of human anisakiasis, is a parasite of homeothermic hosts at the adult stage and of ectothermic hosts at the third larval stage. Among distinct factors, temperature appears to be crucial in affecting parasite hatching, moulting and to modulate parasite-host interaction. In the present study, we investigated the gene transcripts of proteins having an antigenic role among excretory secretory products (ESPs) (i.e., a Kunitz-type trypsin inhibitor, A.peg-1; a glycoprotein, A.peg-7; and the myoglobin, A.peg-13) after 24 h, in A. pegreffii larvae maintained in vitro, under controlled temperature conditions. Temperatures were 37 °C and 20 °C, resembling respectively homeothermic and ectothermic hosts conditions, and 7 °C, the cold stress condition post mortem of the fish host. Primers of genes coding for these ESPs to be used in quantitative real-time PCR were newly designed, and qRT-PCR conditions developed. Expression profiles of the genes A.peg-1 and A.peg-13 were significantly up-regulated at 20 °C and 37 °C, with respect to the control (larvae kept at 2 °C for 24 h). Conversely, transcript profiles of A.peg-7 did not significantly change among the chosen temperature conditions. In accordance with the observed transcript profiles, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of the three target ESPs at 37 °C, while only A.peg-13 was observed at 7 °C. The results suggest that temperature conditions do regulate the gene expression profiles of A.peg-1 and A.peg-13 in A. pegreffii larvae. However, regulation of the glycoprotein A.peg-7 is likely to be related to other factors such as the host's immune response.
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http://dx.doi.org/10.1051/parasite/2019055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707101PMC
December 2019

Novel polymorphic microsatellite loci in and (s. s.) (Nematoda: Anisakidae): implications for species recognition and population genetic analysis.

Parasitology 2019 09 28;146(11):1387-1403. Epub 2019 Jun 28.

Department of Ecological and Biological Sciences, Tuscia University, Viale dell'Università s/n 01100 Viterbo, Italy.

The species of Anisakis constitute one of the most widespread groups of ascaridoid nematodes in the marine ecosystem. Three closely related taxa are recognised in the A. simplex (s. l.) complex, i.e. A. pegreffii, A. simplex (s. s.) and A. berlandi. They are distributed in populations of their intermediate/paratenic (fish and squids) and definitive (cetaceans) hosts. A panel of seven microsatellite loci (Anisl 05784, Anisl 08059, Anisl 00875, Anisl 07132, Anisl 00314, Anisl 10535 and Anisl 00185), were developed and validated on a total of N = 943 specimens of A. pegreffii and A. simplex (s. s.), collected in fish and cetacean hosts from allopatric areas within the range of distribution of these parasite species. In addition, the locus Anisl 7, previously detected in those Anisakis spp., was investigated. The parasites were first identified by sequence analysis of the EF1 α-1 nDNA. The panel of the microsatellites loci here developed have allowed to: (i) detect diagnostic microsatellite loci between the two species; (ii) identify specimens of the two species A. pegreffii, A. simplex (s. s.) in a multi-marker nuclear genotyping approach; (iii) discover two sex-linked loci in both Anisakis species and (iv) estimate levels of genetic differentiation at both the inter- and intra-specific level.
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http://dx.doi.org/10.1017/S003118201900074XDOI Listing
September 2019

Hybridization and extensive mitochondrial introgression among fire salamanders in peninsular Italy.

Sci Rep 2018 09 4;8(1):13187. Epub 2018 Sep 4.

Tuscia University, Department of Ecological and Biological Sciences, Viterbo, 01100, Italy.

Discordance between mitochondrial and nuclear patterns of population genetic structure is providing key insights into the eco-evolutionary dynamics between and within species, and their assessment is highly relevant to biodiversity monitoring practices based on DNA barcoding approaches. Here, we investigate the population genetic structure of the fire salamander Salamandra salamandra in peninsular Italy. Both mitochondrial and nuclear markers clearly identified two main population groups. However, nuclear and mitochondrial zones of geographic transition between groups were located 600 km from one another. Recent population declines in central Italy partially erased the genetic imprints of past hybridization dynamics. However, the overall pattern of genetic variation, together with morphological and fossil data, suggest that a rampant mitochondrial introgression triggered the observed mitonuclear discordance, following a post-glacial secondary contact between lineages. Our results clearly show the major role played by reticulate evolution in shaping the structure of Salamandra salamandra populations and, together with similar findings in other regions of the species' range, contribute to identify the fire salamander as a particularly intriguing case to investigate the complexity of mechanisms triggering patterns of mitonuclear discordance in animals.
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http://dx.doi.org/10.1038/s41598-018-31535-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123427PMC
September 2018

Variability in the "stereotyped" prey capture sequence of male cuttlefish (Sepia officinalis) could relate to personality differences.

Anim Cogn 2018 Nov 3;21(6):773-785. Epub 2018 Sep 3.

Ichthyogenic Experimental Marine Centre (CISMAR), Department of Ecological and Biological Sciences, University of Tuscia, Tarquinia, Viterbo, Italy.

Studies of animal personality have shown consistent between-individual variation in behaviour in many social and non-social contexts, but hunting behaviour has been overlooked. Prey capture sequences, especially in invertebrates, are supposed to be quite invariant. In cuttlefish, the attack includes three components: attention, positioning, and seizure. The previous studies indicated some variability in these components and we quantified it under the hypothesis that it could relate to personality differences. We, therefore, analysed predation sequences of adult cuttlefish to test their association with personality traits in different contexts. Nineteen subjects were first exposed to an "alert" and a "threat" test and then given a live prey, for 10 days. Predation sequences were scored for components of the attack, locomotor and postural elements, body patterns, and number of successful tentacle ejections (i.e. seizure). PCA analysis of predatory patterns identified three dimensions accounting for 53.1%, 15.9%, and 9.6% of the variance and discriminating individuals based on "speed in catching prey", "duration of attack behaviour", and "attention to prey". Predation rate, success rate, and hunting time were significantly correlated with the first, second, and third PCA factors, respectively. Significant correlations between capture patterns and responsiveness in the alert and threat tests were found, highlighting a consistency of prey capture patterns with measures of personality in other contexts. Personality may permeate even those behaviour patterns that appear relatively invariant.
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http://dx.doi.org/10.1007/s10071-018-1209-8DOI Listing
November 2018

Molecular Epidemiology of Anisakis and Anisakiasis: An Ecological and Evolutionary Road Map.

Adv Parasitol 2018 6;99:93-263. Epub 2018 Mar 6.

Tuscia University, Viterbo, Italy.

This review addresses the biodiversity, biology, distribution, ecology, epidemiology, and consumer health significance of the so far known species of Anisakis, both in their natural hosts and in human accidental host populations, worldwide. These key aspects of the Anisakis species' biology are highlighted, since we consider them as main driving forces behind which most of the research in this field has been carried out over the past decade. From a public health perspective, the human disease caused by Anisakis species (anisakiasis) appears to be considerably underreported and underestimated in many countries or regions around the globe. Indeed, when considering the importance of marine fish species as part of the everyday diet in many coastal communities around the globe, there still exist significant knowledge gaps as to local epidemiological and ecological drivers of the transmission of Anisakis spp. to humans. We further identify some key knowledge gaps related to Anisakis species epidemiology in both natural and accidental hosts, to be filled in light of new 'omic' technologies yet to be fully developed. Moreover, we suggest that future Anisakis research takes a 'holistic' approach by integrating genetic, ecological, immunobiological, and environmental factors, thus allowing proper assessment of the epidemiology of Anisakis spp. in their natural hosts, in human populations, and in the marine ecosystem, in both space and time.
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http://dx.doi.org/10.1016/bs.apar.2017.12.001DOI Listing
July 2019

Publisher Correction: Quaternary history, population genetic structure and diversity of the cold-adapted Alpine newt Ichthyosaura alpestris in peninsular Italy.

Sci Rep 2018 Mar 6;8(1):4214. Epub 2018 Mar 6.

Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, Viale dell'Università s.n.c., I-01100, Viterbo, Italy.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
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http://dx.doi.org/10.1038/s41598-018-21905-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5840353PMC
March 2018

Fast and accurate identification of cryptic and sympatric mayfly species of the Baetis rhodani group.

BMC Res Notes 2018 Jan 8;11(1). Epub 2018 Jan 8.

Dipartimento di Scienze Ecologiche e Biologiche, Università degli Studi della Tuscia, Viale dell'Università s.n.c., 01100, Viterbo, Italy.

Objective: Species of the Baetis rhodani group are among the most widespread mayflies of the Palearctic region. However, frequent occurrence of morphologically cryptic species complicates the identification of sympatric species. Here, we proposed and tested a method for the fast, accurate, and cost-effective assignment of a large number of individuals to their putative species, based on high resolution melting profiles of a standard mitochondrial gene fragment. We tested this method using a system of three recently identified cryptic species inhabiting the Tyrrhenian Islands (western Mediterranean basin).

Results: Highly species-specific high resolution melting profiles were obtained, allowing the unequivocal attribution of each individual to the respective species. This assay provides a convenient and easily customizable alternative to traditional barcoding approaches, provided that the mayfly taxa occurring within the geographic area of interest have been previously identified and their high resolution melting profiles assessed.
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http://dx.doi.org/10.1186/s13104-017-3115-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5759225PMC
January 2018

The role of habitat choice in micro-evolutionary dynamics: An experimental study on the Mediterranean killifish (Cyprinodontidae).

Ecol Evol 2017 12 1;7(24):10536-10545. Epub 2017 Nov 1.

Department of Ecological and Biological Sciences Ichthyogenic Experimental Marine Center (CISMAR) Tuscia University Tarquinia VT Italy.

Habitat choice is defined as a nonrandom distribution of genotypes in different microhabitats. Therefore, it could exert a great impact on the genetic variance of natural populations by promoting genetic divergence, local adaptation, and may even lead to sympatric speciation. Despite this potential role in micro- and macro-evolutionary processes, there is little empirical evidence that the various genotypes within a population may differ in habitat choice-related behaviors. Here, we tested whether habitat choice may have contributed to genetic divergence within a local population of the Mediterranean killifish , which emerged between groups inhabiting microhabitats with different oxygen concentrations during previous field studies. In a first experiment, we studied the distribution of individuals in conditions of hypoxia and normoxia to test whether they had a different ability to shy away from a hypoxic environment; in a second experiment, we analyzed the individual behavior of fish separately in the two conditions, to verify whether they showed peculiar behavioral responses linked to a possible differential distribution. We then analyzed the six allozyme loci, whose allelic and genotypic frequencies were significantly divergent in the previous studies. In the first test, we found that the distribution of the two homozygote genotypes of the glucose-6-phosphate isomerase-1 locus (GPI-1) was significantly different between the hypoxic and the normoxic conditions. During the second test, all individuals were more active in hypoxic conditions, but the two GPI-1 homozygotes showed a significant difference in time spent performing surface breathing, which was consistent with their distribution observed in the first experiment. These results provide evidence that individual behavioral traits, related to genetic features, may lead to a nonrandom distribution of genotypes in heterogeneous although contiguous microhabitats and, consequently, that habitat choice can play a significant role in driving the micro-evolutionary dynamics of this species.
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http://dx.doi.org/10.1002/ece3.3540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743487PMC
December 2017

Dietary antioxidants, food deprivation and growth affect differently oxidative status of blood and brain in juvenile European seabass (Dicentrarchus labrax).

Comp Biochem Physiol A Mol Integr Physiol 2018 02 4;216:1-7. Epub 2017 Nov 4.

Department of Ecological and Biological Science, Ichthyogenic Experimental Marine Center (CISMAR), Tuscia University, Borgo Le Saline, 01016 Tarquinia, VT, Italy.

Compensatory growth may increase molecular oxidative damage, which may be mitigated through the intake of dietary antioxidants. However, dietary antioxidants may also reduce concentration of antioxidant enzymes, which have a key role in regulating the oxidative status. Here we investigated whether feeding on a diet rich in antioxidants (vitamin E) enables juvenile European seabass (Dicentrarchus labrax) to catch up after a period of food deprivation with negligible effects on the oxidative stress to blood and brain as compared to fish feeding on a normal diet (i.e., not enriched in antioxidants). The results show that a higher intake in antioxidants favoured compensatory growth, but this came at a cost in terms of increased oxidative damage. Increased intake of antioxidants also resulted in changes in the activity of enzymatic antioxidant defences and increased protein oxidative damage in both brain and blood. In addition, food deprivation caused increased protein oxidative damage in brain. Our findings show that the beneficial effects of dietary antioxidants on growth may be offset by hidden detrimental effects and that different early life events affect different components of oxidative status of a given tissue.
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http://dx.doi.org/10.1016/j.cbpa.2017.10.032DOI Listing
February 2018

Invasive anisakiasis by the parasite Anisakis pegreffii (Nematoda: Anisakidae): diagnosis by real-time PCR hydrolysis probe system and immunoblotting assay.

BMC Infect Dis 2017 08 1;17(1):530. Epub 2017 Aug 1.

Department of Ecological and Biological Sciences, "Tuscia University", Largo dell'Università s/n, 01100, Viterbo, Italy.

Background: Anisakiasis is a fish-borne zoonosis caused by Anisakis spp. larvae. One challenging issue in the diagnosis of anisakiasis is the molecular detection of the etiological agent even at very low quantity, such as in gastric or intestinal biopsy and granulomas. Aims of this study were: 1) to identify three new cases of invasive anisakiasis, by a species-specific Real-time PCR probe assay; 2) to detect immune response of the patients against the pathogen.

Methods: Parasite DNA was extracted from parasites removed in the three patients. The identification of larvae removed at gastric and intestinal level from two patients was first obtained by sequence analysis of mtDNA cox2 and EF1 α-1 of nDNA genes. This was not possible in the third patient, because of the very low DNA quantity obtained from a single one histological section of a surgically removed granuloma. Real-time PCR species-specific hydrolysis probe system, based on mtDNA cox2 gene, was performed on parasites tissue of the three cases. IgE, IgG and IgG immune response against antigens A. pegreffii by Immunoblotting assay was also studied.

Results: According to the mtDNA cox2 and the EF1 α - 1 nDNA sequence analysis, the larvae from stomach and intestine of two patients were assigned to A. pegreffii. The Real-time PCR primers/probe system, showed a fluorescent signal at 510 nm for A. pegreffii, in all the three cases. In Immunoblotting assay, patient CC1 showed IgE, IgG reactivity against Ani s 13-like and Ani s 7-like; patient CC2 revealed only IgG reactivity against Ani s 13-like and Ani s 7-like; while, the third patient showed IgE and IgG reactivity against Ani s 13-like, Ani s 7-like and Ani s 1-like.

Conclusion: The Real-time PCR assay, a more sensitive method than direct DNA sequencing for the accurate and rapid identification of etiological agent of human anisakiasis, was successfully assessed for the first time. The study also highlights the importance to use both molecular and immunological tools in the diagnosis of human anisakiasis, in order to increase our knowledge about the pathological findings and immune response related to the infection by zoonotic species of the genus Anisakis.
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http://dx.doi.org/10.1186/s12879-017-2633-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5539894PMC
August 2017

Quaternary history, population genetic structure and diversity of the cold-adapted Alpine newt Ichthyosaura alpestris in peninsular Italy.

Sci Rep 2017 06 7;7(1):2955. Epub 2017 Jun 7.

Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, Viale dell'Università s.n.c., I-01100, Viterbo, Italy.

Mediterranean peninsulas are major biodiversity hotspots, and cold-adapted species are an important component of this biodiversity. However, cold-adapted species contributed surprisingly little to our knowledge of the intimate links between Quaternary environmental changes, species' responses to these changes, and current patterns of intraspecific biodiversity. Here, we investigated the genetic structure and evolutionary history of a cold-adapted amphibian, the Alpine newt Ichthyosaura alpestris, within the Italian peninsula. Nuclear and mitochondrial markers consistently identified three distinct genetic lineages, whose divergence dates to the Early Pleistocene (1.9 and 0.8 million years ago). Our results show that the Italian peninsula provided multiple Pleistocene refugia to this cold-adapted species, and suggest that allopatric fragmentation followed by secondary admixture have been key events in the formation of its current pattern of genetic diversity. Indeed, estimates of population genetic diversity clearly identified contact populations as those achieving the highest levels of diversity. Such concordance among cold-adapted and temperate species in terms of processes triggering the formation of regional patterns of genetic diversity provides strong support for the hypothesis that gene exchange between divergent lineages, rather than long-term stability of refugial populations, has been the main step toward the formation of hotspots of intraspecific biodiversity.
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http://dx.doi.org/10.1038/s41598-017-03116-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462806PMC
June 2017

Climate change promotes hybridisation between deeply divergent species.

PeerJ 2017 23;5:e3072. Epub 2017 Mar 23.

Department of Ecological and Biological Science, Università degli Studi della Tuscia , Viterbo , Italy.

Rare hybridisations between deeply divergent animal species have been reported for decades in a wide range of taxa, but have often remained unexplained, mainly considered chance events and reported as anecdotal. Here, we combine field observations with long-term data concerning natural hybridisations, climate, land-use, and field-validated species distribution models for two deeply divergent and naturally sympatric toad species in Europe ( and species groups). We show that climate warming and seasonal extreme temperatures are conspiring to set the scene for these maladaptive hybridisations, by differentially affecting life-history traits of both species. Our results identify and provide evidence of an ultimate cause for such events, and reveal that the potential influence of climate change on interspecific hybridisations goes far beyond closely related species. Furthermore, climate projections suggest that the chances for these events will steadily increase in the near future.
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http://dx.doi.org/10.7717/peerj.3072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5366042PMC
March 2017

Cryptic diversity and multiple origins of the widespread mayfly species group (Ephemeroptera: Baetidae) on northwestern Mediterranean islands.

Ecol Evol 2016 Nov 11;6(21):7901-7910. Epub 2016 Oct 11.

Dipartimento di Scienze Ecologiche e Biologiche Università della Tuscia Viterbo Italy.

How the often highly endemic biodiversity of islands originated has been debated for decades, and it remains a fervid research ground. Here, using mitochondrial and nuclear gene sequence analyses, we investigate the diversity, phylogenetic relationships, and evolutionary history of the mayfly on the three largest northwestern Mediterranean islands (Sardinia, Corsica, Elba). We identify three distinct, largely co-distributed, and deeply differentiated lineages, with divergences tentatively dated back to the Eocene-Oligocene transition. Bayesian population structure analyses reveal a lack of gene exchange between them, even at sites where they are syntopic, indicating that these lineages belong to three putative species. Their phylogenetic relationships with continental relatives, together with the dating estimates, support a role for three processes contributing to this diversity: (1) vicariance, primed by microplate disjunction and oceanic transgression; (2) dispersal from the continent; and (3) speciation within the island group. Thus, our results do not point toward a prevailing role for any of the previously invoked processes. Rather, they suggest that a variety of processes equally contributed to shape the diverse and endemic biota of this group of islands.
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http://dx.doi.org/10.1002/ece3.2465DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6093170PMC
November 2016

Species composition and infection dynamics of ascaridoid nematodes in Barents Sea capelin (Mallotus villosus) reflecting trophic position of fish host.

Parasitol Res 2016 Nov 29;115(11):4281-4291. Epub 2016 Jul 29.

Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza - University of Rome, Rome, Italy.

Capelin (Mallotus villosus) is among the most abundant fish species in the Barents Sea, and represents a critical food source for many predators in the area including Atlantic cod and harp seal. In Norway, the fish is of economic importance since whole capelin and roe are valuable export products. Despite its economic and ecological importance, the parasites of Barents Sea capelin are poorly known. However, the presence of parasites in the edible parts may adversely affect product quality and consumer safety. During the main annual catching seasons of 2009-2012, we investigated the diversity and infection dynamics of ascaridoid nematodes in capelin (n = 620) from the southern Barents Sea. Three anisakid species were identified by genetic or molecular methods; Anisakis simplex (s.s.), Contracaecum osculatum sp. B, and Hysterothylacium aduncum, with C. osculatum sp. B as the most prevalent and abundant species. The present findings suggest that the ascaridoid species composition in capelin reflects its trophic position in the Barents Sea ecosystem. There appears to be a link between infection level of the nematode species and the preferred prey organisms of the different developmental phases of capelin. Thus, the higher abundance of C. osculatum sp. B compared to A. simplex (s.s.) and H. aduncum may be related to more extensive feeding on calanoid copepods over a wider ontogenetic size range including adolescence, while the main intermediate hosts of the latter nematode species, i.e. euphausiids and amphipods, appear to be the preferred prey of larger capelin.
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http://dx.doi.org/10.1007/s00436-016-5209-9DOI Listing
November 2016

The Tangled Evolutionary Legacies of Range Expansion and Hybridization.

Trends Ecol Evol 2016 09 20;31(9):677-688. Epub 2016 Jul 20.

Department of Ecological and Biological Science, University of Tuscia, 01100 Viterbo, Italy.

Spatial sorting of dispersal-enhancing traits has been implicated in substantial directional changes in the phenotypic and genotypic makeup of populations undergoing range expansion. We explore here the evolutionary consequences of such changes when two divergent lineages come into secondary contact. We combine instances from the study of contemporary range expansions and historical hybridizations, and highlight links between dispersal, sexual, and physiological traits during the non-equilibrium conditions imposed by range expansions. We argue that a stronger research focus on processes of spatial sorting of multiple traits will improve our understanding of subsequent hybridization dynamics and their evolutionary outcomes, including genomic introgression and speciation.
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http://dx.doi.org/10.1016/j.tree.2016.06.010DOI Listing
September 2016

Cyanobacteria biennal dynamic in a volcanic mesotrophic lake in central Italy: Strategies to prevent dangerous human exposures to cyanotoxins.

Toxicon 2016 Jun 4;115:28-40. Epub 2016 Mar 4.

Department of the Environment and Primary Prevention - Istituto Superiore di Sanità, Viale Regina Elena 299, Rome, Italy. Electronic address:

Vico Lake, a volcanic meso-eutrophic lake in Central Italy, whose water is used for drinking and recreational activities, experienced the presence of the microcystins (MC) producing cyanobacterium Planktothrix rubescens. In order to assess the human health risks and to provide the local health authorities with a scientific basis for planning tailored monitoring activities, we studied P. rubescens ecology and toxicity for two years. P. rubescens generally dominated the phytoplankton community, alternating with Limnothrix redekei, potentially toxic. P. rubescens was distributed throughout the water column during winter; in summer it produced intense blooms where drinking water is collected (-20 m); here MC were detected all year round (0.5-5 μg/L), with implications for drinking water quality. In surface waters, MC posed no risk for recreational activities in summer, while in winter surface blooms and foams (containing up to 56 μg MC/L) can represent a risk for people and children practicing water sports and for animals consuming raw water. Total phosphorus, phosphate and inorganic nitrogen were not relevant to predict densities nor toxicity; however, a strong correlation between P. rubescens density and aminopeptidase ectoenzymatic activity, an enzyme involved in protein degradation, suggested a role of organic nitrogen for this species. The fraction of potentially toxic population, determined both as mcyB(+)/16SrDNA (10-100%) and as the MC/mcyB(+) cells (0.03-0.79 pg MC/cell), was much more variable than usually observed for P. rubescens. Differently from other Italian and European lakes, the correlation between cell density or the mcyB(+) cells and MC explained only ∼50 and 30% of MC variability, respectively: for Vico Lake, monitoring only cell or the mcyB(+) cell density is not sufficient to predict MC concentrations, and consequently to protect population health. Finally, during a winter bloom one site has been sampled weekly, showing that monthly sampling during such a phase could greatly underestimate the 'hazard'. Our results highlight the need to adopt a stepwise monitoring activity, considering the lake and the cyanobacteria specific features. This activity should be complemented with communication to the public and involvement of stakeholders.
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http://dx.doi.org/10.1016/j.toxicon.2016.03.004DOI Listing
June 2016

Temporal stability of parasite distribution and genetic variability values of Contracaecum osculatum sp. D and C. osculatum sp. E (Nematoda: Anisakidae) from fish of the Ross Sea (Antarctica).

Int J Parasitol Parasites Wildl 2015 Dec 22;4(3):356-67. Epub 2015 Oct 22.

Department of Ecological and Biological Sciences, Tuscia University, Viterbo, 01100, Italy.

The Ross Sea, Eastern Antarctica, is considered a "pristine ecosystem" and a biodiversity "hotspot" scarcely impacted by humans. The sibling species Contracaecum osculatum sp. D and C. osculatum sp. E are anisakid parasites embedded in the natural Antarctic marine ecosystem. Aims of this study were to: identify the larvae of C. osculatum (s.l.) recovered in fish hosts during the XXVII Italian Expedition to Antarctica (2011-2012); perform a comparative analysis of the contemporary parasitic load and genetic variability estimates of C. osculatum sp. D and C. osculatum sp. E with respect to samples collected during the expedition of 1993-1994; to provide ecological data on these parasites. 200 fish specimens (Chionodraco hamatus, Trematomus bernacchii, Trematomus hansoni, Trematomus newnesi) were analysed for Contracaecum sp. larvae, identified at species level by allozyme diagnostic markers and sequences analysis of the mtDNA cox2 gene. Statistically significant differences were found between the occurrence of C. osculatum sp. D and C. osculatum sp. E in different fish species. C. osculatum sp. E was more prevalent in T. bernacchii; while, a higher percentage of C. osculatum sp. D occurred in Ch. hamatus and T. hansoni. The two species also showed differences in the host infection site: C. osculatum sp. D showed higher percentage of infection in the fish liver. High genetic variability values at both nuclear and mitochondrial level were found in the two species in both sampling periods. The parasitic infection levels by C. osculatum sp. D and sp. E and their estimates of genetic variability showed no statistically significant variation over a temporal scale (2012 versus 1994). This suggests that the low habitat disturbance of the Antarctic region permits the maintenance of stable ecosystem trophic webs, which contributes to the maintenance of a large populations of anisakid nematodes with high genetic variability.
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http://dx.doi.org/10.1016/j.ijppaw.2015.10.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4683570PMC
December 2015

Persistence, isolation and diversification of a naturally fragmented species in local refugia: the case of Hydromantes strinatii.

PLoS One 2015 24;10(6):e0131298. Epub 2015 Jun 24.

Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, Viterbo, Italy.

The study of the European plethodontid salamander Hydromantes strinatii using allozyme and mitochondrial markers showed a strong geographical genetic structure. This was likely the outcome of different evolutionary mechanisms leaving their signature despite the effects of the genetic drift due to the low population size typical of this species. Two highly divergent clades were identified in the eastern and central-western part of the range, with further geographic sub-structure. Nuclear and mitochondrial markers substantially recovered the same population groups but were conflicting in reconstructing their relationships. This apparent incongruence highlighted the action of different mechanisms such as secondary contacts and incomplete lineage sorting in originating the observed genetic variation. The troglophilic habit of this species provided the opportunity to show the importance of caves as local refugia in maintaining the genetic diversity through the persistence of local populations. Accordingly, high nucleotide and haplotype diversity, strong geographic genetic structuring and lack of expansion were evidenced. This signature was found in the populations from the Ligurian and Maritime Alps, in agreement with the complex orography and paleoclimatic history of this Mediterranean hotspot.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131298PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4479377PMC
April 2016

Genetic identification and distribution of the parasitic larvae of Anisakis pegreffii and Anisakis simplex (s. s.) in European hake Merluccius merluccius from the Tyrrhenian Sea and Spanish Atlantic coast: implications for food safety.

Int J Food Microbiol 2015 Apr 29;198:1-8. Epub 2014 Nov 29.

Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Italy. Electronic address:

The consumption of the hake Merluccius merluccius is widespread in European countries, where this fish has a high commercial value. To date, different larval species of Anisakis have been identified as parasites in M. merluccius from European waters, Anisakis pegreffii and Anisakis simplex (s. s.) being the two most common. The aim of the study is to present data on the occurrence of Anisakis spp. larvae in the viscera and flesh of M. merluccius. Consequently, the distribution and infection rates of different species of Anisakis in different sites (viscera, and dorsal and ventral fillets) were investigated in hake caught in the central Tyrrhenian Sea (FAO 37.1.3) and the NE Atlantic Ocean (FAO 27 IXa). A sample of N=65 fish individuals (length>26 cm) was examined parasitologically from each fishing ground. The fillets were examined using the pepsin digestion method. A large number (1310) of Anisakis specimens were identified by multilocus allozyme electrophoresis (MAE) and mtDNA cox2 sequence analysis; among these, 814 larvae corresponded to A. simplex (s. s.) and 476 to A. pegreffii. They were found to infect both the flesh and the viscera. The two species co-infected the same individual fish (both in the viscera and in the flesh) from the FAO 27 area, whereas only A. pegreffii was found in hake from the Tyrrhenian Sea. The average parasite burden of A. pegreffii in hake from the Tyrrhenian Sea was significantly lower to that observed from hake off the Atlantic coast of Spain, both in prevalence and in abundance. In addition, whereas no significant difference in overall prevalence values was recorded between the two Anisakis species in the viscera of the FAO 27 sample, significant differences were found in the abundance levels observed between these species in the flesh, with A. simplex (s. s.) exhibiting significantly higher levels than that observed for A. pegreffii (p<0.001). Given that the pathogenic role in relation to man is known for these two species of Anisakis, both the flesh inspection and the infection rates of the different anisakid species assume particular importance in terms of assessing the risk they pose to humans.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2014.11.019DOI Listing
April 2015

Speciation history and widespread introgression in the European short-call tree frogs (Hyla arborea sensu lato, H. intermedia and H. sarda).

Mol Phylogenet Evol 2015 Feb 4;83:143-55. Epub 2014 Dec 4.

Laboratory of Molecular Ecology, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Rumburská 89, 277 21 Liběchov, Czech Republic. Electronic address:

European tree frogs (Hyla) characterized by short temporal parameters of the advertisement call form six genetically differentiated but morphologically cryptic taxa, H. arborea sensu stricto, H. orientalis and H. molleri from across Europe to western Asia (together referred to as H. arborea sensu lato), two putative taxa within H. intermedia (Northern and Southern) from the Italian Peninsula and Sicily, and H. sarda from Sardinia and Corsica. Here, we assess species limits and phylogenetic relationships within these 'short-call tree frogs' based on mitochondrial DNA and nuclear protein-coding markers. The mitochondrial and nuclear genes show partly incongruent phylogeographic patterns, which point to a complex history of gene flow across taxa, particularly in the Balkans. To test the species limits in the short-call tree frogs and to infer the species tree, we used coalescent-based approaches. The monophyly of H. arborea sensu lato is supported by the mtDNA as well as by the all-gene species tree. The Northern and Southern lineages of H. intermedia have been connected by nuclear gene flow (despite their deep mtDNA divergence) and should be treated as conspecific. On the contrary, the parapatric taxa within H. arborea sensu lato should be considered distinct species (H. arborea, H. orientalis, H. molleri) based on the coalescent analysis, although signs of hybridization were detected between them (H. arborea×H. orientalis; H. arborea×H. molleri). A mitochondrial capture upon secondary contact appears to explain the close mtDNA relationship between the geographically remote Iberian H. molleri and H. orientalis from around the Black Sea. Introgressive hybridization occurred also between the Balkan H. arborea and northern Italian H. intermedia, and between the Minor Asiatic H. orientalis and Arabian H. felix arabica (the latter belonging to a different acoustic group/clade). Our results shed light on the species limits in the European short-call tree frogs and show that introgression played an important role in the evolutionary history of the short-call tree frogs and occurred even between taxa supported as distinct species.
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http://dx.doi.org/10.1016/j.ympev.2014.11.012DOI Listing
February 2015

Extensive unidirectional introgression between two salamander lineages of ancient divergence and its evolutionary implications.

Sci Rep 2014 Oct 1;4:6516. Epub 2014 Oct 1.

Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia. Viale dell'Università s.n.c., I-01100 Viterbo, Italy.

Hybridization and introgression, contrary to previous beliefs, are now considered to be widespread processes even among animal species. Nonetheless, the range of their possible outcomes and roles in moulding biodiversity patterns are still far from being fully appraised. Here we investigated the pattern of hybridization and introgression between Salamandrina perspicillata and S. terdigitata, two salamanders endemic to the Italian peninsula. Using a set of diagnostic or differentiated genetic markers (9 nuclear and 1 mitochondrial), we documented extensive unidirectional introgression of S. terdigitata alleles into the S. perspicillata gene pool in central Italy, indicating that barriers against hybridization were permeable when they came into secondary contact, and despite their ancient divergence. Nonetheless, purebred S. terdigitata, as well as F1, F2, and backcrosses were not found within the hybrid zone. Moreover, Bayesian analyses of population structure identified admixed populations belonging to a differentiated gene pool with respect to both parental populations. Overall, the observed genetic structure, together with their geographic pattern of distribution, suggests that Salamandrina populations in central Italy could have entered a distinct evolutionary pathway. How far they have gone along this pathway will deserve future investigation.
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http://dx.doi.org/10.1038/srep06516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5377473PMC
October 2014

Anthropogenics: human influence on global and genetic homogenization of parasite populations.

J Parasitol 2014 Dec;100(6):756-72

Agricultural Research Service, Animal Parasitic Diseases Lab, Beltsville, Maryland 20705.

The distribution, abundance, and diversity of life on Earth have been greatly shaped by human activities. This includes the geographic expansion of parasites; however, measuring the extent to which humans have influenced the dissemination and population structure of parasites has been challenging. In-depth comparisons among parasite populations extending to landscape-level processes affecting disease emergence have remained elusive. New research methods have enhanced our capacity to discern human impact, where the tools of population genetics and molecular epidemiology have begun to shed light on our historical and ongoing influence. Only since the 1990s have parasitologists coupled morphological diagnosis, long considered the basis of surveillance and biodiversity studies, with state-of-the-art tools enabling variation to be examined among, and within, parasite populations. Prior to this time, populations were characterized only by phenotypic attributes such as virulence, infectivity, host range, and geographical location. The advent of genetic/molecular methodologies (multilocus allozyme electrophoresis, polymerase chain reaction-DNA [PCR-DNA] fragments analysis, DNA sequencing, DNA microsatellites, single nucleotide polymorphisms, etc.) have transformed our abilities to reveal variation among, and within, populations at local, regional, landscape, and global scales, and thereby enhanced our understanding of the biosphere. Numerous factors can affect population structure among parasites, e.g., evolutionary and ecological history, mode of reproduction and transmission, host dispersal, and life-cycle complexity. Although such influences can vary considerably among parasite taxa, anthropogenic factors are demonstrably perturbing parasite fauna. Minimal genetic structure among many geographically distinct (isolated) populations is a hallmark of human activity, hastened by geographic introductions, environmental perturbation, and global warming. Accelerating environmental change now plays a primary role in defining where hosts, parasites, and other pathogens occur. This review examines how anthropogenic factors serve as drivers of globalization and genetic homogenization of parasite populations and demonstrates the impact that human intervention has had on the global dissemination of parasites and the accompanying diseases.
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http://dx.doi.org/10.1645/14-622.1DOI Listing
December 2014

Metazoan parasite infection in the swordfish, Xiphias gladius, from the Mediterranean Sea and comparison with Atlantic populations: implications for its stock characterization.

Parasite 2014 25;21:35. Epub 2014 Jul 25.

Department of Ecological and Biological Sciences, Tuscia University, Viale dell'Università s/n, 01100 Viterbo, Italy.

Thirteen parasite taxa were identified in the Mediterranean swordfish by morphological and genetic/molecular methods. The comparison of the identified parasite taxa and parasitic infection values observed in the Mediterranean swordfish showed statistically significant differences with respect to those reported for its Atlantic populations. A stepwise Linear Discriminant Analysis of the individual fish examined showed a separation among three groups: one including fish from the Mediterranean Sea (CTS, STS, and IOS); one consisting of fish from the Central South (CS), Eastern Tropical (ET), and Equatorial (TEQ) Atlantic; and a third comprising the fish sampled from the North-West Atlantic (NW); the CN Atlantic sample was more similar to the first group rather than to the other Atlantic ones. The nematodes Hysterothylacium petteri and Anisakis pegreffii were the species that contributed most to the characterization of the Mediterranean swordfish samples with respect to these Atlantic ones. Anisakis brevispiculata, A. physeteris, A. paggiae, Anisakis sp. 2, Hysterothylacium incurvum, Hepatoxylon trichiuri, Sphyriocephalus viridis, and their high infection levels were associated with the swordfish from the Central and the Southern Atlantic areas. Finally, H. corrugatum, A. simplex (s.s.), Rhadinorhynchus pristis, and Bolbosoma vasculosum were related to the fish from the North-West (NW) Atlantic area. These results indicate that some parasites, particularly Anisakis spp. larvae identified by genetic markers, could be used as "biological tags" and support the existence of a Mediterranean swordfish stock.
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http://dx.doi.org/10.1051/parasite/2014036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4109596PMC
January 2015

Hybridization, natural selection, and evolution of reproductive isolation: a 25-years survey of an artificial sympatric area between two mosquito sibling species of the Aedes mariae complex.

Evolution 2014 Oct 18;68(10):3030-8. Epub 2014 Aug 18.

Department of Environmental Biology, University of Rome "La Sapienza", Rome, Italy.

Natural selection can act against maladaptive hybridization between co-occurring divergent populations leading to evolution of reproductive isolation among them. A critical unanswered question about this process that provides a basis for the theory of speciation by reinforcement, is whether natural selection can cause hybridization rates to evolve to zero. Here, we investigated this issue in two sibling mosquitoes species, Aedes mariae and Aedes zammitii, that show postmating reproductive isolation (F1 males sterile) and partial premating isolation (different height of mating swarms) that could be reinforced by natural selection against hybridization. In 1986, we created an artificial sympatric area between the two species and sampled about 20,000 individuals over the following 25 years. Between 1986 and 2011, the composition of mating swarms and the hybridization rate between the two species were investigated across time in the sympatric area. Our results showed that A. mariae and A. zammitii have not completed reproductive isolation since their first contact in the artificial sympatric area. We have discussed the relative role of factors such as time of contact, gene flow, strength of natural selection, and biological mechanisms causing prezygotic isolation to explain the observed results.
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http://dx.doi.org/10.1111/evo.12490DOI Listing
October 2014

What triggers the rising of an intraspecific biodiversity hotspot? Hints from the agile frog.

Sci Rep 2014 May 23;4:5042. Epub 2014 May 23.

Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia. Viale dell'Università s.n.c., I-01100 Viterbo, Italy.

Hotspots of genetic diversity are regions of utmost importance for species survival and conservation, and their intimate link with the geographic location of glacial refugia has been well established. Nonetheless, the microevolutionary processes underlying the generation of hotspots in such regions have only recently become a fervent field of research. We investigated the phylogeographic and population genetic structure of the agile frog, Rana dalmatina, within its putative refugium in peninsular Italy. We found this region to harbour far more diversity, phylogeographic structure, and lineages of ancient origin than that by the rest of the species' range in Europe. This pattern appeared to be well explained by climate-driven microevolutionary processes that occurred during both glacial and interglacial epochs. Therefore, the inferred evolutionary history of R. dalmatina in Italy supports a view of glacial refugia as 'factories' rather than as repositories of genetic diversity, with significant implications for conservation strategies for hotspots.
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http://dx.doi.org/10.1038/srep05042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4031470PMC
May 2014