Taxonomy,phylogeography and climate relations of the Western Palaearctic spurge hawkmoth (Lepidoptera,Sphingidae, Macroglossinae)

Hundsdoerfer, AK., Mende, MB., Kitching, IJ. & Cordellier, M. (2011). Taxonomy, phylogeography and climate relations of the Western Palaearctic spurge hawkmoth (Lepidoptera, Sphingidae, Macroglossinae). —Zoologica Scripta, 40, 403–417. The primary aim of this study was to analyse mitochondrial genetic variability within the Hyles euphorbiae lineage in the Western Palaearctic, where observations of morphology have indicated much greater differentiation than is implied by the current taxonomy. The scope of the study is broadened further by including an analysis of the possible influences of climatic factors on lineage distributions. Mitochondrial sequences from three genes totalling an unambiguous alignment of 2284 bp were obtained for 356 individuals of the H. euphorbiae complex (HEC) s.s. Genetic admixture, network and climatic factor analyses were used to analyse the data. Unexpected mitochondrial variability was uncovered within the distribution range of H. euphorbiae in southern Europe, with two additional distinct clusters being found, both with rather patchy occurrences. The results of the genetic analysis presented here confirm a distinct H. cretica on Crete and the Dodecanese Islands and a distinct H. robertsi in Iran that hybridises with H. euphorbiae. Comparison of the molecular data with larval morphology shows only limited correlation of genetic clusters with pattern elements. The genetic network of the HEC s.s. shows strong incongruence with traditional taxonomy. Ecological niche modelling based on climate data revealed that the three best‐sampled clusters (H. tithymali, the well‐known H. euphorbiae lineage from Europe, and the previously unknown mitochondrial H. euphorbiae lineage that occurs mainly in Italy) could all occur in southern Italy and on the Mediterranean Islands. Biotic interactions appear to explain the observed ranges better than abiotic factors alone.     

Diversification of Bacillus subtilis during experimental evolution on Arabidopsis thaliana and the complementarity in root colonization of evolved subpopulations

The soil bacterium Bacillus subtilis is known to suppress pathogens as well as promote plant growth. However, in order to fully exploit the potential as natural fertilizer, we need a better understanding of the interactions between B. subtilis and plants. Here, B. subtilis was examined for root colonization through experimental evolution on Arabidopsis thaliana. The populations evolved rapidly, improved in root colonization and diversified into three distinct morphotypes. In order to better understand the adaptation that had taken place, single evolved isolates from the final transfer were randomly selected for further characterization, revealing changes in growth and pellicle formation in medium supplemented with plant polysaccharides. Intriguingly, certain evolved isolates showed improved root colonization only on the plant species they evolved on, but not on another plant species, namely tomato, suggesting A. thaliana specific adaption paths. Finally, the mix performed better than the sum of its constituents in monoculture, which was demonstrated to be caused by complementarity effects. Our results suggest that genetic diversification occurs in an ecological relevant setting on plant roots and proves to be a stable strategy for root colonization.     

The candidate gene approach in plant genetics: a review

The candidate gene (CG) approach has been applied in plant genetics in the past decade for the characterisation and cloning of Mendelian and quantitative trait loci (QTLs). It constitutes a complementary strategy to map-based cloning and insertional mutagenesis. The goal of this paper is to present an overview of CG analyses in plant genetics. CG analysis is based on the hypothesis that known-function genes (the candidate genes) could correspond to loci controlling traits of interest. CGs refer either to cloned genes presumed to affect a given trait (`functional CGs') or to genes suggested by their close proximity on linkage maps to loci controlling the trait (`positional CGs'). In plant genetics, the most common way to identify a CG is to look for map co-segregation between CGs and loci affecting the trait. Statistical association analyses between molecular polymorphisms of the CG and variation in the trait of interest have also been carried out in a few studies. The final validation of a CG will be provided through physiological analyses, genetic transformation and/or sexual complementation. Theoretical and practical applications of validated CGs in plant genetics and breeding are discussed.     

Pseudomonas fluorescens MFE01 delivers a putative type VI secretion amidase that confers biocontrol against the soft-rot pathogen Pectobacterium atrosepticum

The type VI secretion system (T6SS) is a contractile nanomachine widespread in Gram-negative bacteria. The T6SS injects effectors into target cells including eukaryotic hosts and competitor microbial cells and thus participates in pathogenesis and intermicrobial competition. Pseudomonas fluorescens MFE01 possesses a single T6SS gene cluster that confers biocontrol properties by protecting potato tubers against the phytopathogen Pectobacterium atrosepticum (Pca). Here, we demonstrate that a functional T6SS is essential to protect potato tuber by reducing the pectobacteria population. Fluorescence microscopy experiments showed that MFE01 displays an aggressive behaviour with an offensive T6SS characterized by continuous and intense T6SS firing activity. Interestingly, we observed that T6SS firing is correlated with rounding of Pectobacterium cells, suggesting delivery of a potent cell wall targeting effector. Mutagenesis coupled with functional assays then revealed that a putative T6SS secreted amidase, Tae3^Pf, is mainly responsible for MFE01 toxicity towards Pca. Further studies finally demonstrated that Tae3^Pf is toxic when produced in the periplasm, and that its toxicity is counteracted by the Tai3^Pf inner membrane immunity protein.     

Die Organisation des optischen Feldes bei der Biene. I.

Ohne Zusammenfassung     

Zur Physiologie des Formen- und Bewegungssehens. III

Zusammenfassung Für die Biene sind Abhebung, Gliederung, verschiedene Verteilung der Konturen und mit Ortsveränderung verbundene Bewegung selbständige figurale Eigenschaften, die sich in reziproken Dressuren gegeneinander ausspielen lassen. Die Dressur auf eine mit Ortsveränderung bewegte Figur gegenüber einer identischen, ruhenden ist nicht gelungen, wohl aber die auf die ruhende gegenüber der bewegten. Dagegen gelingen reziproke Dressuren, wenn der eine Partner eine stark abgehobene geschlossene und der andere Partner eine schwächer abgehobene, gegliederte Figur ist, nahezu rein an mehreren Figurenpaaren, bei denen zum Teil eine primäre Überlegenheit des einen über den anderen Partner besteht. Ebenso gelingen reziproke Dressuren bei einem Figurenpaar, dessen Partner dem gleichen figuralen Typus C angehören und die gleiche Abhebung und ungefähr den gleichen Konturreichtum besitzen, bei einer drastisch verschiedenen Verteilung der Konturen. Diese Beobachtungen warnen davor, auf der Häufigkeit und dem Ausmaß des Reizwechsels eine Tropismenlehre aufbauen zu wollen, die nur Zwangsreaktionen kennt.