Probing the structure and function of viral RNA genomes

The majority of human, animal and plant viral pathogens possess genomes composed of RNA. The strategies evolved for expression and replication of viral RNA genomes can differ significantly from those utilized for expression and replication of host-cell genetic material. Consequently, knowledge of the molecular details of these strategies can lead to a clearer understanding of the origin, evolution and control of viral pathogens. We describe recent progress in identifying important structural and functional domains of the RNA genomes and associated replicative enzymes for two very different viruses: vesicular stomatitis virus, which possesses a single-stranded RNA genome of negative polarity, and wound tumor virus, which contains a genome composed of 12 discrete segments of double-stranded RNA.     

Artifical rearrangements of insect ooplasm caused by fixation,and their microkymographic recording

Summary Time-lapse photomicrographs of eggs from the Ichneumonid waspPimpla and from the gall midgeWachtliella reveal that during fixation the ooplasm performs excessive streaming movements when conventional fluids such as Bouin's or Dubosq-Brasil's are used. InWachtliella, intravitelline cleavage may continue for two mitotic cycles during fixation. The cytoplasm of individual egg regions may become displaced up to 45% of the egg's length inPimpla, and up to 14% of the egg's length inWachtliella. Therefore fixed preparations may grossly misrepresent the distribution of egg components in the living state. The changes can be traced back by microkymographic registration of movements during fixation. Microkymograms for this purpose were obtained by projecting a time-lapse film through a slit onto photosensitive material mounted on a rotating drum.The shifting of egg components and the mitotic activity of nuclei fail to occur when the egg is treated with a buffered solution of OsO₄ (1%, 1 min). Subsequent fixation with glutaraldehyde results in satisfactory preservation of microtubules.     

Molecular phylogeny,larval case architecture,host–plant associations and classification of European Coleophoridae (Lepidoptera)

Bauer, F., Stübner, A., Neinhuis, C. & Nuss, M. (2012). Molecular phylogeny, larval case architecture, host–plant associations and classification of European Coleophoridae (Lepidoptera). —Zoologica Scripta, 41, 248–265. Several attempts based on adult morphology have aimed at classifying the megadiverse Coleophoridae, either by defining species groups or by splitting the large genus Coleophora into many smaller genera. A previous cladistic analysis focussing on larvae suggests monophyly of some case type groups as well as host–plant associations with a preference for certain plant tissues and growth forms. Here, a first molecular phylogeny for Coleophoridae is presented to test these partly contradicting hypotheses. Bayesian statistics is applied to different partitioning strategies of a COI + wingless data set (1815 bp) for 105 European species, revealing eight monophyletic species groups. A broader defined Coleophora with internal groups is better supported than the division into many genera. Goniodoma Zeller, 1849 syn. rev. and Metriotes Herrich‐Schäffer, 1853 syn. n. are nested within Coleophora Hübner, 1822. Seven species are transferred to Coleophora: C. auroguttella ( Zeller, 1849 ) comb. rev., C. limoniella Stainton, 1884 comb. rev., C. millierella (Ragonot, 1882) comb. n., C. nemesi (C?pu?e, 1970) comb. n., C. sinica (Li & Zheng, 2002) comb. n. (from Goniodoma) as well as C. jaeckhi (Baldizzone, 1985) comb. n. and C. lutarea (Haworth, 1828) comb. n. (from Metriotes). None of the formerly suggested case types is synapomorphic for any of the recovered clades. In contrast, cases built from glossy silk that turns black or dark brown is synapomorphic for the vibicella group. Some clades have radiated on certain plant taxa along with a specialisation in specific tissues, for example, the clade containing the saturatella (leaf miners) and frischella (seed miners) groups is associated with Fabaceae, the albella group (seed miners) with Caryophyllales and the serpylletorum group (leaf miners) with Lamiaceae. Calculating an index of host specificity for all studied species confirms significant differences between seed and leaf feeders on herbaceous plants, but not between leaf feeders on herbaceous and woody plants.