Gastropod first intermediate hosts for two species of Monorchiidae Odhner, 1911 (Trematoda): I can’t believe it’s not bivalves!

The trematode superfamily Monorchioidea comprises three families of teleost parasites: the Monorchiidae Odhner, 1911, Lissorchiidae Magath, 1917, and Deropristidae Cable & Hunninen, 1942. All presently known lissorchiid and deropristid life cycles have gastropods as first intermediate hosts, whereas those of monorchiids involve bivalves. Here, we report an unexpected intermediate host for monorchiids; two species of Hurleytrematoides Yamaguti, 1954 use gastropods as first intermediate hosts. Sporocysts and cercariae were found infecting two species of the family Vermetidae, highly specialised sessile gastropods that form calcareous tubes, from two locations off the coast of Queensland, Australia. These intramolluscan infections broadly corresponded morphologically to those of known monorchiids in that the cercariae have a spinous tegument, oral and ventral suckers, a simple tail and distinct eye-spots. Given the simplified morphology of intramolluscan infections, genetic data provided a definitive identification. ITS2 rDNA and cox1 mtDNA sequence data from the gastropod infections were identical to two species of Hurleytrematoides, parasites of butterflyfishes (Chaetodontidae); Hurleytrematoides loi McNamara & Cribb, 2011 from Moreton Bay (south-eastern Queensland) and Heron Island (southern Great Barrier Reef) and Hurleytrematoides morandi McNamara & Cribb, 2011 from Heron Island. Notably, species of Hurleytrematoides are positioned relatively basal in the phylogeny of the Monorchiidae and are a sister lineage to that of species known to infect bivalves. Thus, the most parsimonious evolutionary hypothesis to explain infection of gastropods by these monorchiids is that basal monorchiids (in our analyses, species of Cableia Sogandares-Bernal, 1959, Helicometroides Yamaguti, 1934 and Hurleytrematoides) will all prove to infect gastropods, suggesting a single host switching event into bivalves for more derived monorchiids (17 other genera in our phylogenetic analyses). A less parsimonious hypothesis is that the infection of vermetids will prove to be restricted to species of Hurleytrematoides, as an isolated secondary recolonisation of gastropods from a bivalve-infecting lineage. Regardless of how their use arose, vermetids represent a dramatic host jump relative to the rest of the Monorchiidae, one potentially enabled by their specialised feeding biology.     

Dientamoeba fragilis in the North-East of Italy: Prevalence study and treatment

Dientamoeba fragilis is an intestinal protozoan, an inhabitant of the human gastrointestinal tract, with a worldwide distribution. The reported prevalence of D. fragilis varies worldwide in different populations between 0.3% and 82.9%, and its role as a pathogen is still unclear. The parasite has been identified in the faeces of asymptomatic patients and with different acute and chronic symptoms, like abdominal pain, diarrhoea, flatulence, nausea and vomiting.The aims of this study were to evaluate the prevalence of D. fragilis in the North-East of Italy, and the clinical improvement of symptoms after recommended treatment with paromomycin or metronidazole. Furthermore, a literature review of D. fragilis prevalence studies in Italy was carried out to show the Italian situation.Of 575 enrolled people, 85 (14.8%) were positive for D. fragilis. The most prevalent symptoms were abdominal pain 28.2%, anal itching 27.1%, watery diarrhoea 18.8%, meteorism 16.5% and nausea/lack of appetite 14.1%. The high rate of anal itching was unexpected, because it wasn't a common symptom. 32 patients were co-infected with B. hominis (37.7%) and three with G. lamblia (3.5%).Our study showed paromomycin had a high efficacy for treatment of D. fragilis infections 100.0% (45/45), while caution must be used when using metronidazole 53.3% (24/40). We recommend paromomycin for empirical treatment, given its great effectiveness in our population.     

Phytoplankton and Zooplankton Associations in a Set of Alpine High Altitude Lakes: Geographic Distribution and Ecology

Species composition and interactions, biomass dominance, geographic distribution and driving variables were investigated for two key elements of the pelagic food web of Alpine lakes, the phytoplankton and the zooplankton, based on a single sampling campaign during summer 2000. Altogether, 70 lakes were surveyed, 49 of which located in three different lake districts of the west and eastern Italian Alps and 21 in the central Austrian Alps (within the uppermost Danube catchment). In addition to the analysis of environmental variables affecting distribution and species structure of the two planktonic compartments, a brief review of the main research lines and hypotheses adopted in the past for the study of phytoplankton and zooplankton in high Alpine lakes is given. The lakes, investigated partly within the European project EMERGE (EVK1-CT-1999-00032) and partly within a regional project in the eastern Alps, comprise a wide range of morphological, chemical and trophic conditions. The phytoplankton communities were found to be diverse and mostly dominated by flagellates (chrysophytes, cryptophytes and dinoflagellates), and only to a lesser extent by non-motile green algae, desmids and centric diatoms. The zooplankton communities were mainly dominated by Alpine cladocerans and copepod species, while rotifers were abundant within one group of Italian lakes (sampled in early summer). The multivariate statistical analyses (CCA) showed that catchment features (i.e. percentage of vegetation cover and geochemical composition) and nitrate concentration are essential drivers for the phytoplankton, whereas for zooplankton also trophic status of the lakes and phytoplankton structure are important. The combined variance analysis of the lake clusters outlined by the multivariate analyses on phytoplankton and zooplankton data, respectively, allowed the identification of four principal lake types (three located on siliceous and one on carbonaceous bedrock), each one characterised by a certain combination of habitat features, which in their turn influence trophic state, and phytoplankton and zooplankton species composition and functionality.     

The wintering of migrant Dunnocks Prunella modularis in two Mediterranean habitats after fire

Migrant Dunnocks Prunella modularis are common winter visitors to the Mediterranean area. In a burnt forest, Dunnocks were present from October to April. They occupied definite individual home ranges of 0.18 ha on average (n = 83), at a density of 30 birds/10 ha in the fifth winter and 18 birds/10 ha in the sixth winter following a fire. Birds used visible posts and uttered ‘tseep’ calls often. Counter-calling was particularly frequent in the winter with the highest population density. In a burnt maquis, Dunnocks showed return rates (15%) and median recapture distances (62.5 m) not significantly different from those of territorial wintering Robins Erithacus rubecula. We suggest that Dunnock ranges can be regarded as ‘feeding territories’, promoted by an abundant, predictible and renewable food supply of rock-rose Cistus spp. seeds, characteristic of early Mediterranean successions. Ownership might be proclaimed by ‘tseep’ calls, recalling the behaviour of female Dunnocks during prebreeding territorial conflicts. Further research using colour-ringed birds may confirm Dunnock winter territoriality, exceptional for a migrant and mostly granivorous passerine.     

Development of nine new microsatellite loci for the American beaver, Castor canadensis (Rodentia: Castoridae), and cross-species amplification in the European beaver, Castor fiber

We developed nine new nuclear dinucleotide microsatellite loci for Castor canadensis. All loci were polymorphic, except for one. The number of alleles ranged from two to four and from five to 12 in populations from Arizona and Wisconsin, respectively. Average heterozygosity ranged from 0.13 to 0.86 per locus. Since cross-species amplification in Castor fiber was successful only in four loci, we tested also nine recently published C. canadensis loci in the Eurasian species. Eight of the published loci amplified; however, three were monomorphic. The number of alleles was lower in C. fiber than in C. canadensis at all loci tested.     

Molecular crosstalks in Leishmania-sandfly-host relationships

Sandflies (Diptera: Phlebotominael are vectors of Leishmania parasites, causative agents of important human and animal diseases with diverse manifestations. This review summarizes present knowledge about the vectorial part of Leishmania life cycle and parasite transmission to the vertebrate host. Particularly, it focuses on molecules that determine the establishment of parasite infection in sandfly midgut. It describes the concept of specific versus permissive sandfly vectors, explains the epidemiological consequences of broad susceptibility of permissive sandflies and demonstrates that genetic exchange may positively affect Leishmania fitness in the vector. Last but not least, the review describes recent knowledge about circulating antibodies produced by hosts in response to sandfly bites. Studies on specificity and kinetics of antibody response revealed that anti-saliva IgG could be used as a marker of host exposure to sandflies, i.e. as a useful tool for evaluation of vector control.     

Digestive function of lysozyme in synanthropic acaridid mites enables utilization of bacteria as a food source

The activity of lysozyme, the enzyme that hydrolyzes peptidoglycan in G⁺ bacterial cell walls, was detected in whole mite extracts (WME) and in spent growth medium extracts (SGME) of 14 species of synanthropic mites (Acari: Acaridida). The adaptation of lysozyme for digestive activity and bacteriophagy was based on: (i) high lysozyme activity in SGME, and (ii) the correlation of maximum lysozyme activity at acidic pH values, corresponding to pH in the ventriculus and caeca. We show that the digestion of fluorescein-labeled Micrococcus lysodeikticus cells began in ventriculus and continued during the passage of a food bolus through the gut. The fluorescein was absorbed by midgut cells and penetrated to parenchymal tissues. Eight species showed a higher rate of population growth on a M. lysodeikticus diet than on a control diet. The lysozyme activity in SGME was positively correlated to the standardized rate (r _s) of population growth, although no correlation was found between r _s and lysozyme activity in WME. The lysozyme activity in WME was negatively correlated to that in SGME. The highest activity of digestive lysozyme was found in Lepidoglyphus destructor, Chortoglyphus arcuatus and Dermatophagoides farinae. All of these findings indicate that lysozyme in acaridid mites possesses both defensive and digestive functions. The enzymatic properties of mite lysozyme are similar to those of the lysozymes present in the ruminant stomach and in the insect midgut.     

A lipophosphoglycan-independent development of Leishmania in permissive sand flies

Leishmaniases are serious parasitic diseases the etiological organisms of which are transmitted by insect vectors, phlebotominae sand flies. Two sand fly species, Phlebotomus papatasi and P. sergenti, display remarkable specificity for Leishmania parasites they transmit in nature, but many others are broadly permissive to the development of different Leishmania species. Previous studies have suggested that in 'specific' vectors the successful parasite development is mediated by parasite surface glycoconjugates and sand fly lectins, however we show here that interactions involving 'permissive' sand flies utilize another molecules. We did find that the abundant surface glycoconjugate lipophosphoglycan, essential for attachment of Leishmania major in the specific vector P. papatasi, was not required for parasite adherence or survival in the permissive vectors P. arabicus and Lutzomyia longipalpis. Attachment in several permissive sand fly species instead correlated with the presence of midgut glycoproteins bearing terminal N-acetyl-galactosamine and with the occurrence of a lectin-like activity on Leishmania surface. This new binding modality has important implications for parasite transmission and evolution. It may contribute to the successful spreading of Leishmania due to their adaptation into new vectors, namely transmission of L. infantum by Lutzomyia longipalpis; this event led to the establishment of L. infantum/chagasi in Latin America.