Genetic Diversity of the Cestode Echinococcus multilocularis in Red Foxes at a Continental Scale in Europe

Background

Alveolar echinococcosis (AE) is a severe helminth disease affecting humans, which is caused by the fox tapeworm Echinococcus multilocularis. AE represents a serious public health issue in larger regions of China, Siberia, and other regions in Asia. In Europe, a significant increase in prevalence since the 1990s is not only affecting the historically documented endemic area north of the Alps but more recently also neighbouring regions previously not known to be endemic. The genetic diversity of the parasite population and respective distribution in Europe have now been investigated in view of generating a fine-tuned map of parasite variants occurring in Europe. This approach may serve as a model to study the parasite at a worldwide level.

Methodology/Principal Findings

The genetic diversity of E. multilocularis was assessed based upon the tandemly repeated microsatellite marker EmsB in association with matching fox host geographical positions. Our study demonstrated a higher genetic diversity in the endemic areas north of the Alps when compared to other areas.

Conclusions/Significance

The study of the spatial distribution of E. multilocularis in Europe, based on 32 genetic clusters, suggests that Europe can be considered as a unique global focus of E. multilocularis, which can be schematically drawn as a central core located in Switzerland and Jura Swabe flanked by neighbouring regions where the parasite exhibits a lower genetic diversity. The transmission of the parasite into peripheral regions is governed by a “mainland–island” system. Moreover, the presence of similar genetic profiles in both zones indicated a founder event.     

Structure and ultrastructure of the silk glands and spinneret of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

This study provides comprehensive documentation of silk production in the pest moth Helicoverpa armigera from gland secretion to extrusion of silk thread. The structure of the silk glands, accessory structures and extrusion apparatus are reported. The general schema of the paired silk glands follows that found for Lepidoptera. Morphology of the duct, silk press, muscle attachments and spigot are presented as a three-dimensional reconstruction and the cuticular crescent-shaped profile of the silk press is demonstrated in both open and closed forms with attendant muscle blocks, allowing advances in our knowledge of how the silk press functions to regulate the extrusion of silk. Growth of the spigot across instars is documented showing a distinctive developmental pattern for this extrusion device. Its shape and structure are related to use and load-bearing activity.     

Electrophoretic Mobility of Amylase in Drosophilids Indicates Adaptation to Ecological Diversity

Understanding the significance of electrophoretic variation is of interest for both ecological and evolutionary genetics. Although there has been a very active neutralist–selectionist debate about the patterns of electrophoretic variation in natural populations, it is only recently that charged amino acids have been shown to be important in enzyme adaptation. In this study we carried out a broad electrophoretic survey of amylase variation in 150 species of Drosophilids. The distribution of amylase electromorphs was found to be correlated with the geographical origin of the flies. Generally the faster migrating variants are found in warmer temperatures. There is also a correlation with the feeding habits of the species, in particular, fungus feeders consistently showed a deviating pattern of electrophoretic mobility. These correlations between ecological diversity and electrophoretic patterns indicate that at least some of the changes in charged amino acids are adaptive, and result from selection to cope with specific environments.     

Novel mechanism for high-altitude adaptation in hemoglobin of the Andean frog Telmatobius peruvianus

In contrast to birds and mammals, no information appears to be available on the molecular adaptations for O(2) transport in high-altitude ectothermic vertebrates. We investigated Hb of the aquatic Andean frog Telmatobius peruvianus from 3,800-m altitude as regards isoform differentiation, sensitivity to allosteric cofactors, and primary structures of the alpha- and beta-chains, and we carried out comparative O(2)-binding measurements on Hb of lowland Xenopus laevis. The three T. peruvianus isoHbs show similar functional properties. The high O(2) affinity of the major component results from an almost complete obliteration of chloride sensitivity, which correlates with two alpha-chain modifications: blockage of the NH(2)-terminal residues and replacement by nonpolar Ala of polar residues Ser and Thr found at position alpha131(H14) in human and X. leavis Hbs, respectively. The data indicate adaptive significance of alpha-chain chloride-binding sites in amphibians, in contrast to human Hb where chloride appears mainly to bind in the cavity between the beta-chains. The findings are discussed in relation to other strategies for high-altitude adaptations in amphibians.     

Mutational spectrum of the iduronate-2-sulfatase (IDS) gene in 36 unrelated Russian MPS II patients

We present a mutational analysis of the iduronate-2-sulfatase (IDS) gene of 36 Russian patients with Hunter syndrome. Among 29 mutant alleles, there were 19 missense mutations, 1 nonsense mutation, 6 mutations affecting splice sites, and 3 major structural alterations resulting in deletions. Of the 25 different mutations, 15 are novel and unique. Most of the missense mutations result in intermediate or severe phenotypes. Received: 1 June 1998 / Accepted: 27 July 1998     

Genetically controlled 2″-O-glycosylation of isovitexin in the petals of Melandrium album

The genetically controlled O-glycosylation of the 6-C-glucosyl residue of isovitexin in the petals of Melandrium album has been shown to take place in the 2″-position, by MS of the corresponding permethylated isovitexin glycosides.     

Isolation and purification of cell wall-associated arginine carboxypeptidase fromStreptococcus mitis ATCC 15909

An arginine carboxypeptidase was isolated from the cell walls ofStreptococcus mitis ATCC 15909 by mutanolysin extraction of the walls. The enzyme was purified 32-fold by gel filtration on Sephacryl S-300, affinity chromatography on Arginine-Sepharose 4B and by rechromatography on Sephacryl S-300. The molecular mass of the enzyme was calculated to 122 kDa by gel filtration. The enzyme released arginine from the carboxy terminal of hippurylarginine and, at a low rate, lysine from furylacryloylalanyl-lysine and hippuryl-lysine. The carboxypeptidase seemed firmly bound to the cell wall because SDS treatment of the walls did not release measurable amounts of activity.