Helminth parasites of the Eurasian otter Lutra lutra in southwest Europe

The helminth fauna in 109 Eurasian otters (Lutra lutra L.) from France, Portugal and Spain was analysed, together with 56 faecal samples collected in Portugal and 23 fresh stools from otters included in a reintroduction programme. Seven helminth species were found in L. lutra in southwest Europe: Phagicola sp. (Trematoda), Aonchotheca putorii, Eucoleus schvalovoj, Strongyloides lutrae, Anisakis (third stage larvae) and Dirofilaria immitis (Nematoda), and Gigantorhynchus sp. (Acanthocephala). Eucoleus schvalovoj was the dominant species throughout southwest Europe. Strongyloides lutrae was significantly more prevalent in the Iberian Peninsula than in France. Apart from these two dominant nematodes and A. putorii, the other helminth species were incidental parasites of L. lutra in southwest Europe. The helminth fauna of L. lutra in southwest Europe is, in general, poorer than that reported in eastern Europe and in all other aquatic mustelids in southwest Europe. Phagicola specimens are reported for the first time in a non-marine wild carnivore in Europe. The prevalences of E. schvalovoj and S. lutrae obtained by necropsy were higher than those observed by coprological analysis using a formalin-ether concentration method (Ritchie). Nevertheless, the culture of fresh faeces appears to be the best method to study infection of L. lutra by Strongyloides.     

Nemo is an inducible antagonist of Wingless signaling during Drosophila wing development

The cellular events that govern patterning during animal development must be precisely regulated. This is achieved by extrinsic factors and through the action of both positive and negative feedback loops. Wnt/Wg signals are crucial across species in many developmental patterning events. We report that Drosophila nemo (nmo) acts as an intracellular feedback inhibitor of Wingless (Wg) and that it is a novel Wg target gene. Nemo antagonizes the activity of the Wg signal, as evidenced by the finding that reduction of nmo rescues the phenotypic defects induced by misexpression of various Wg pathway components. In addition, the activation of Wg-dependent gene expression is suppressed in wing discs ectopically expressing nmo and enhanced cell autonomously in nmo mutant clones. We find that nmo itself is a target of Wg signaling in the imaginal wing disc. nmo expression is induced upon high levels of Wg signaling and can be inhibited by interfering with Wg signaling. Finally, we observe alterations in Arm stabilization upon modulation of Nemo. These observations suggest that the patterning mechanism governed by Wg involves a negative feedback circuit in which Wg induces expression of its own antagonist Nemo.     

Enhancement of adenovirus-mediated gene delivery to rheumatoid arthritis synoviocytes and synovium by fiber modifications: role of arginine-glycine-aspartic acid (RGD)- and non-RGD-binding integrins

Rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) do not express the coxsackie-adenovirus (Ad) receptor and are poorly permissive to Ad serotype 5 (Ad5). Genetically modified, coxsackie-Ad receptor-independent Ad5 vectors were studied for gene delivery in human RA FLS and synovium explants and murine collagen-induced arthritis. Short-fiber Ad5 vectors with seven fiber shaft repeats Ad5GFP-R7-knob, Ad5GFP-R7-arginine-glycine-aspartic acid (RGD) (RGD-liganded), and Ad5GFPDeltaknob (knob-deleted) were compared with Ad5GFP-FiWT, a conventional wild-type (WT) Ad5 vector. Gene transfer by Ad5GFP-R7-knob and Ad5GFP-R7-RGD was 40- to 50-fold and 25-fold higher, respectively, than Ad5GFP-FiWT in FLS. Ad5GFPDeltaknob was more efficacious than its knob-bearing version Ad5GFP-R7-knob in FLS transduction. Virus attachment and entry required RGD- and LDV-binding integrins including alpha(v), alpha(v)beta3, a(v)beta5, and beta1. Ad5GFP-R7-knob infection of FLS was partially neutralized by synovial fluid (SF), but remained 30- to 40-fold higher than Ad5GFP-FiWT in the presence of SF. Ad5GFPDeltaknob was partially neutralized by SF at low virus input, but escaped viral neutralization by SF at higher virus input. Gene transfer to human synovium ex vivo explants and murine collagen-induced arthritis in vivo was also more efficient with short fiber-modified vectors (with and without the knob domain) than Ad5GFPFiWT. Gene transfer by short fiber-modified vectors was enhanced by inflammatory cytokines in vitro and in the presence of inflammation in murine synovium in vivo. Our data indicated that the highly efficient gene delivery RA was mediated by RGD- and non-RGD-binding integrins and enhanced by inflammation. Short fiber modifications with knob ablation may be a strategy to enhance gene delivery, reducing vector dose and vector-induced inflammation and toxicity.     

Differential environmental response of plant functional types in hedgerow habitats

Classifying species into functional groups reacting similar to multiple environmental factors based on shared biological characteristics forms a major challenge faced by present-day ecologists. Based on data of a hedgerow plant community, this study uses a multivariate approach to analyse if trait-based emergent species groups have real functional significance, i.e. if these groups are characterised by specific response profiles to a wide range of environmental factors. First, the influence of explanatory variable groups (abiotic environmental conditions, management variables, structural aspects, historical background and spatial configuration of the hedgerow network) on distribution patterns of individual plant species was analysed with partial logistic regression. Significant relationships were found between the ecological characteristics of a species and the relative importance of variable groups affecting the distribution of that species within a hedgerow network landscape. Next, a trait-based classification of hedgerow plant species was constructed using a hierarchical clustering procedure. Woody species segregated into two distinct groups, with differences predominantly associated with generative traits, herbaceous species in four groups differing mainly in vegetative traits and habitat preferences. Clear differences in response to multiple environmental factors between the emergent species groups demonstrated the functional significance of the constructed classification. Relationships between the trait- and response profile were examined and their ecological relevance discussed. With respect to the woody species groups, zoochorous species were affected more strongly by hedgerow structure and landscape context than anemochorous species. For the herbaceous species clustering, a relatively strong impact was found, amongst others, of historical variables on species with woodland preference in comparison with other species groups.

Zusammenfassung

Die Klassifizierung von Arten in funktionelle Gruppen, die aufgrund von gemeinsamen biologischen Eigenschaften in gleicher Weise auf multiple Umweltfaktoren reagieren, ist eine große Herausforderung, vor der heutige Ökologen stehen. Auf der Grundlage von Daten einer Heckenpflanzen-Lebensgemeinschaft folgt diese Untersuchung einer multivariaten Vorgehensweise, um zu analysieren, ob die auftretenden Artengruppen auf der Basis von Merkmalen eine wirkliche funktionelle Bedeutung haben, d. h. ob diese Gruppen durch spezifische Antwortprofile auf eine große Auswahl von Umweltfaktoren charakterisiert sind. Zuerst wurde der Einfluss von Gruppen erklärender Variablen (abiotische Umweltbedingungen, Managementvariablen, strukturelle Aspekte, geschichtlicher Hintergrund und räumliche Anordnung des Heckennetzes) auf die Verteilungsmuster einzelner Pflanzenarten mit partiellen logistischen Regressionen analysiert. Signifikante Beziehungen wurden zwischen den ökologischen Eigenschaften einer Art und der relativen Wichtigkeit von Variablengruppen gefunden, die die Verbreitung der Art innerhalb der Heckennetzlandschaft beeinflussen. Im Anschluss wurde eine merkmalsbasierte Klassifikation der Heckenpflanzenarten unter der Verwendung einer hierarchischen Gruppierungsprozedur konstruiert. Aufgrund von Unterschieden, die vor allem mit den Fortpflanzungsmerkmalen einhergingen, trennten sich die holzigen Arten in zwei verschiedene Gruppen auf. Krautige Arten trennten sich in vier Gruppen auf, die sich vor allem in den vegetativen Merkmalen und Habitatpräferenzen unterschieden. Klare Unterschiede in den Reaktionen auf multiple Umweltfaktoren zwischen den entstandenen Artengruppen demonstrierten die funktionelle Bedeutung der konstruierten Klassifikation. Die Beziehungen zwischen den Merkmals- und Antwortprofilen wurden untersucht und ihre ökologische Relevanz diskutiert. In Bezug auf die holzigen Artengruppen waren die zoochoren Arten stärker von der Heckenstruktur und dem Landschaftskontext beeinflusst als anemochore Arten. Für die krautigen Artencluster wurde unter anderem ein relativ starker Einfluss von historischen Variablen auf die Arten mit Waldpräferenz im Vergleich zu anderen Artengruppen gefunden.     

Patterns in size and shedding of Fasciola hepatica eggs by naturally and experimentally infected murid rodents

Using samples collected on the island of Corsica, a comparative study was done of the morphometry of Fasciola hepatica eggs shed by cattle and by naturally and experimentally infected murid rodents (wild Mus musculus and Rattus rattus and Rattus norvegicus Wistar laboratory strain). Eggs shed by murids are smaller in size than those shed by naturally infected cattle. A second study analyzed the number of F. hepatica eggs shed in murid feces at different time intervals, i.e., months, days, and 6-hr periods, by the Kato-Katz technique. Both experimentally and naturally infected black rats (R. rattus) were used, and Wistar rats were experimentally infected and included for comparison. The present studies prove that black rats R. rattus are able to shed eggs independently from the liver fluke isolate and that egg shedding occurs throughout the life of this host species, uninterrupted during all the months analyzed in a 2-yr period. Moreover, the results suggest that this shedding is continuous, with eggs appearing in the feces daily. The results on egg shedding by wild black rats R. rattus reach their maximum shedding in spring and autumn and a maximum during twilight hr. These chronobiological patterns appear to favor parasite transmission, both seasonally and daily.     

High cryptic diversity and persistent lineage segregation in endemic Romecytheridea (Crustacea,Ostracoda) from the ancient Lake Tanganyika (East Africa)

Ostracods form a substantial part of the endemic fauna of ancient lakes. Here, we have investigated the phylogenetic and phylogeographic patterns and genetic diversities of species of the endemic genus Romecytheridea from the Southern and Central part of Lake Tanganyika. We found that ostracod populations from four different localities are genetically highly differentiated from each other when analyzing the mitochondrial 16S region, while they are almost identical with genetic markers from the nuclear genome (D1-D2 from the large ribosomal subunit (LSU) and ITS). The criteria of the K/θ method for the evolutionary species concepts are fulfilled when analyzing 16S DNA sequence data, indicating that these populations are in fact different (cryptic) species with allopatric distribution. We discuss various hypotheses on how this high diversity could have originated. The complete lineage segregation can partly be explained by geographic isolation during periods of low lake level stands. But, other factors must have contributed to genetic isolation and speciation, as the two closest populations (Chimba and Katoto) from shallow parts of the Southern basin of Tanganyika are also geographically fully segregated.