Phylogeny of Myrmeleontiformia based on larval morphology (Neuropterida: Neuroptera)

The suborder Myrmeleontiformia is a derived lineage of lacewings (Insecta: Neuroptera) including the families Psychopsidae, Nemopteridae, Nymphidae, Ascalaphidae and Myrmeleontidae. In particular, Myrmeleontidae (antlions) are the most diverse neuropteran family, representing a conspicuous component of the insect fauna of xeric environments. We present the first detailed quantitative phylogenetic analysis of Myrmeleontiformia, based on 107 larval morphological and behavioural characters for 36 genera whose larvae are known (including at least one representative of all the subfamilies of the suborder). Four related families were used as outgroups to polarize character states. Phylogenetic analyses were conducted using both parsimony and Bayesian methods. The reconstructions resulting from our analyses corroborate the monophyly of Myrmeleontiformia. Within this clade, Psychopsidae are recovered as the sister family to all the remaining taxa. Nemopteridae (including both subfamilies Nemopterinae and Crocinae) are recovered as monophyletic and sister to the clade comprising Nymphidae + (Myrmeleontidae + Ascalaphidae). Nymphidae consist of two well‐supported clades corresponding to the subfamilies Nymphinae and Myiodactylinae. Our results suggest that Ascalaphidae may not be monophyletic, as they collapse into an unresolved polytomy under the Bayesian analysis. In addition, the recovered phylogenetic relationships diverge from the traditional classification scheme for ascalaphids. Myrmeleontidae are reconstructed as monophyletic, with the subfamilies Stilbopteryginae, Palparinae and Myrmeleontinae. We retrieved a strongly supported clade comprising taxa with a fossorial habit of the preimaginal instars, which represents a major antlion radiation, also including the monophyletic pit‐trap building species.     

The Secondary Metabolite Euplotin C Induces Apoptosis-Like Death in the Marine Ciliated Protist Euplotes vannus

ABSTRACT. The sesquiterpenoid euplotin C is a secondary metabolite produced by the ciliated protist Euplotes crassus and provides a mechanism for damping populations of potential competitors. Indeed, E. crassus is virtually resistant to its own product while different non-producer species representing an unbiased sample of the marine, interstitial, ciliate diversity are sensitive. For instance, euplotin C exerts a marked disruption of different homeostatic mechanisms in Euplotes vannus . We demonstrate by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay that euplotin C quickly decreases viability and mitochondrial function of E. vannus with a very high efficacy and at micromolar potency. In addition, euplotin C induces apoptosis in E. vannus as 4,6-diamino-2-phenylindole and terminal transferase dUTP nick end labeling staining show the rapid condensation and fragmentation of nuclear material in cells treated with euplotin C. These effects occur without detectable permeabilisation or rupture of cell membranes and with no major changes in the overall morphology, although some traits, such as vacuolisation and disorganized microtubules, can be observed by transmission electron microscopy. In particular, E. vannus show profound changes of the mitochondrial ultrastructure. Finally, we also show that caspase activity in E. vannus is increased by euplotin C. These data elucidate the pro-apoptotic role of euplotin C and suggest a mechanism for its impact on natural selection.     

LARGER FORAMINIFERA FROM THE UPPER OLIGOCENE OF THE VENETIAN AREA, NORTH-EAST ITALY

Abstract:  A moderately diverse larger foraminiferal fauna from the north-east Italian 'Arenarie e calcari di S. Urbano' formation with important stratigraphic, palaeoecological and palaeobiogeographical implications is described with respect to its position in the Western Tethys area. The fauna is dominated by hyaline perforated and porcellaneous forms including Amphistegina , Archaias , Austrotrillina , Miogypsinoides , Neoplanorbulinella , Neorotalia , Nummulites , Operculina and Spiroclypeus. The presence of Miogypsinoides complanatus allows the age of the formation to be determined as late Chattian (Shallow Benthic Zone SBZ 23). The palaeoenvironmental setting is interpreted as a shallow ramp environment ranging from (1) well lit, highly translucent, shallowest part of the photic zone characterized by Archaias and Austrotrillina , the deeper part of the inner ramp with Nummulites , to (2) the shallow part of the middle ramp with Spiroclypeus and miogypsinids and Operculina , to (3) a deeper middle-ramp setting dominated by coralline rhodoliths along with lepidocylinids. The presence of Archaias hensoni Smout and Eames shows that members of much more diverse Middle Eastern associations of shallow-water larger porcellaneous foraminifera are also present in the north-western parts of the Western Tethys, and reveals a corresponding diversity gradient among larger foraminiferal faunas in the Western Tethys, which is related to a decrease in temperature.     

Population genetic structure of Plasmopara viticola after 125 years of colonization in European vineyards

To examine the within- and among-population genetic structure of Plamopara viticola oosporic populations in Europe, 8991 lesions from 32 vineyard plots were collected and analysed. Four multi-allelic microsatellite markers were used to genotype the pathogen. All populations had high levels of gene and genotypic diversity. Most populations were in Hardy–Weinberg equilibrium and thus randomly mating. Among P. viticola populations, significant low to moderate genetic differentiation was observed, even between geographically close populations. This genetic differentiation was also evident in the neighbour-joining phylogenetic genetic distance tree, showing clear substructure and distinguishing mainly five clusters based on geographical origin. Significant isolation by distance was found in central European P. viticola populations, suggesting a step-wise migration model. No significant isolation by distance was found within Greek populations, most probably owing to natural geographical barriers such as the sea and mountains, as well as the frequent population bottlenecks occurring in these populations, preventing natural migration among populations. The high variability of P. viticola provides explanation for its successful infestation of the heterogeneous European vineyards in the last 125 years after its introduction.     

Taxon‐biased diet preference in the ‘generalist’ beetle‐hunting wasp Cerceris rubida provides insights on the evolution of prey specialization in apoid wasps

Opportunism and specialization appear to be widespread in apoid wasps, although the factors affecting the diet preference (and thus explaining the degree of specialization) are still largely unknown. Four hypotheses that stressed the importance of the size, sex, habitat, and taxonomic identity of prey of the beetle‐hunting digger wasp, Cerceris rubida, were formulated and tested. The wasp population hunted for phytophagous beetles belonging to abundant families around the wasp nesting site. In practice, the prey appeared to be hunted only in two cultivated fields, thus habitat accounted for a majority of the observed diet. The size of wasps was furthermore correlated with the size of their prey, and thus this also accounted for the frequencies of hunted prey and the strong individual specialization for both taxa and size. However, in the exploited habitat, some species were significantly over‐hunted than expected and some other significantly avoided by the wasps, causing an unexpected major role of prey taxon on the probability of being hunted, over the other explanatory variables (body size, body shape, sex, availability). This contrasts to that found in other wasp species, which appear to select prey basing essentially on their ecology and size or their relative abundance (opportunism). The results obtained in the present study show that even an apparent ‘generalist’ predator may turn out to be taxonomically specialized. Together with a re‐evaluation of previous studies, our results further suggest that the effect of size constraints and the developmental plan of prey (holometaboulous versus hemimetabolous) may have promoted either taxonomic opportunism or specialization in different lineages of apoid wasps. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 544–558.     

Eutrophication and macroalgal blooms in temperate and tropical coastal waters: nutrient enrichment experiments with Ulva spp.

Receiving coastal waters and estuaries are among the most nutrient‐enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast‐growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosphorus (P), the two main potential growth‐limiting nutrients, influence macroalgal growth in temperate and tropical coastal waters ranging from low‐ to high‐nutrient supplies. We carried out N and P enrichment field experiments on Ulva spp. in seven coastal systems, with one of these systems represented by three different subestuaries, for a total of nine sites. We showed that rate of growth of Ulva spp. was directly correlated to annual dissolved inorganic nitrogen (DIN) concentrations, where growth increased with increasing DIN concentration. Internal N pools of macroalgal fronds were also linked to increased DIN supply, and algal growth rates were tightly coupled to these internal N pools. The increases in DIN appeared to be related to greater inputs of wastewater to these coastal waters as indicated by high δ¹⁵N signatures of the algae as DIN increased. N and P enrichment experiments showed that rate of macroalgal growth was controlled by supply of DIN where ambient DIN concentrations were low, and by P where DIN concentrations were higher, regardless of latitude or geographic setting. These results suggest that understanding the basis for macroalgal blooms, and management of these harmful phenomena, will require information as to nutrient sources, and actions to reduce supply of N and P in coastal waters concerned.     

Action Mechanisms of the Secondary Metabolite Euplotin C: Signaling and Functional Role in Euplotes

ABSTRACT. Among secondary metabolites, the acetylated hemiacetal sesquiterpene euplotin C has been isolated from the marine, ciliated protist Euplotes crassus, and provides an effective mechanism for reducing populations of potential competitors through its cytotoxic properties. However, intracellular signaling mechanisms and their functional correlates mediating the ecological role of euplotin C are largely unknown. We report here that, in E. vannus (an Euplotes morphospecies that does not produce euplotin C and shares with E. crasssus the same interstitial habitat), euplotin C rapidly increases the intracellular concentration of both Ca²⁺ and Na⁺, suggesting a generalized effect of this metabolite on cation transport systems. In addition, euplotin C does not induce oxidative stress, but modulates the electrical properties of E. vannus through an increase of the amplitude of graded action potentials. These events parallel the disassembling of the ciliary structures, the inhibition of cell motility, the occurrence of aberrant cytoplasmic vacuoles, and the rapid inhibition of phagocytic activity. Euplotin C also increases lysosomal pH and decreases lysosomal membrane stability of E. vannus. These results suggest that euplotin C exerts a marked disruption of those homeostatic mechanisms whose efficiency represents the essential prerequisite to face the challenges of the interstitial environment.     

Interaction Between TRPC Channel Subunits in Endothelial Cells

Transient Receptor Potential Canonical (TRPC) proteins have been identified in mammals as a family of plasma membrane calcium-permeable channels activated by different kinds of stimuli in several cell types. We have studied TRPC subunit expression in bovine aortic endothelial (BAE-1) cells, where stimulation with basic fibroblast growth factor (bFGF), a potent angiogenetic factor, induces calcium entry carried at least partially by TRPC1 channels. By means of a RT-PCR approach, we have found that, in addition to TRPC1, only TRPC4 is expressed, both at the mRNA and protein level, as confirmed by immunoblotting and immunocytochemical analysis. Because functional TRPC channels are formed by assembly of four subunits in either homo- or heterotetrameric structures, we have carried out immunoprecipitation experiments and showed that TRPC1 and TRPC4 interact to form heteromers in these cells, independently from culture conditions (high or low percent of fetal calf serum, stimulation with bFGF). Moreover, the data show that TRPC subunits are not tyrosine-phosphorylated after bFGF stimulation and they do not co-immunoprecipitate with the type 1 FGF receptor. These results suggest that BAE-1 cells are a suitable model to study function and regulation of endogenous TRPC1/TRPC4 heteromers.