No Evidence of Enemy Release in Pathogen and Microbial Communities of Common Wasps (Vespula vulgaris) in Their Native and Introduced Range

When invasive species move to new environments they typically experience population bottlenecks that limit the probability that pathogens and parasites are also moved. The invasive species may thus be released from biotic interactions that can be a major source of density-dependent mortality, referred to as enemy release. We examined for evidence of enemy release in populations of the common wasp (Vespula vulgaris), which attains high densities and represents a major threat to biodiversity in its invaded range. Mass spectrometry proteomic methods were used to compare the microbial communities in wasp populations in the native (Belgium and England) and invaded range (Argentina and New Zealand). We found no evidence of enemy release, as the number of microbial taxa was similar in both the introduced and native range. However, some evidence of distinctiveness in the microbial communities was observed between countries. The pathogens observed were similar to a variety of taxa observed in honey bees. These taxa included Nosema, Paenibacillus, and Yersina spp. Genomic methods confirmed a diversity of Nosema spp., Actinobacteria, and the Deformed wing and Kashmir bee viruses. We also analysed published records of bacteria, viruses, nematodes and fungi from both V. vulgaris and the related invader V. germanica. Thirty-three different microorganism taxa have been associated with wasps including Kashmir bee virus and entomophagous fungi such as Aspergillus flavus. There was no evidence that the presence or absence of these microorganisms was dependent on region of wasp samples (i.e. their native or invaded range). Given the similarity of the wasp pathogen fauna to that from honey bees, the lack of enemy release in wasp populations is probably related to spill-over or spill-back from bees and other social insects. Social insects appear to form a reservoir of generalist parasites and pathogens, which makes the management of wasp and bee disease difficult.     

Improved production of potato microtubers using a temporary immersion system

A temporary immersion system for potato microtuber production was designed using 4-l vessels. This culture technique showed several advantages compared to solid cultures: i.e., three fold increase in shoot length, more internodes per plant and improved vigor. In the tuber induction stage, microtubers can be induced at all plant nodes, indicating that the tuberization is not restricted to specific regions. For both cultivars tested, Desiree and Atlantic, an average of 3.1 and 2.8 tubers per single node cutting was achieved after 9 weeks in culture. The size and weight of the tubers were higher than on solid media. Scale up was performed with cv. Atlantic in 10-l polycarbonate flasks and 12 units were mounted containing 150 single nodal cuttings each. An average of 2.6 tubers per inoculated cutting was obtained, with 1.3 g fresh weight per microtuber. Temporary immersion is a valuable option for potato microtuber production, as well as for shoot production during the planting season. This revised version was published online in June 2006 with corrections to the Cover Date.     

The SLO-1 BK channel of Caenorhabditis elegans is critical for muscle function and is involved in dystrophin-dependent muscle dystrophy

The Caenorhabditis elegans SLO-1 channel belongs to the family of calcium-activated large conductance BK potassium channels. SLO-1 has been shown to be involved in neurotransmitter release and ethanol response. Here, we report that SLO-1 also has a critical role in muscles. Inactivation of the slo-1 gene in muscles leads to phenotypes similar to those caused by mutations of the dystrophin homologue dys-1. Notably, slo-1 mutations result in a progressive muscle degeneration when put into a sensitized genetic background. slo-1 localization was observed by gfp reporter gene in both the M-line and the dense bodies (Z line) of the C.elegans body-wall muscles. Using the inside-out configuration of the patch clamp technique on body-wall muscle cells of acutely dissected wild-type worms, we characterized a Ca2+-activated K+ channel that was identified unambiguously as SLO-1. Since neither the abundance nor the conductance of SLO-1 was changed significantly in dys-1 mutants compared to wild-type animals, it is likely that the inactivation of dys-1 causes a misregulation of SLO-1. All in all, these results indicate that SLO-1 function in C.elegans muscles is related to the dystrophin homologue DYS-1.     

Molecular origin of the self-assembly of lanreotide into nanotubes: a mutational approach

Lanreotide, a synthetic, therapeutic octapeptide analog of somatostatin, self-assembles in water into perfectly hollow and monodisperse (24-nm wide) nanotubes. Lanreotide is a cyclic octapeptide that contains three aromatic residues. The molecular packing of the peptide in the walls of a nanotube has recently been characterized, indicating four hierarchical levels of organization. This is a fascinating example of spontaneous self-organization, very similar to the formation of the gas vesicle walls of Halobacterium halobium. However, this unique peptide self-assembly raises important questions about its molecular origin. We adopted a directed mutation approach to determine the molecular parameters driving the formation of such a remarkable peptide architecture. We have modified the conformation by opening the cycle and by changing the conformation of a Lys residue, and we have also mutated the aromatic side chains of the peptide. We show that three parameters are essential for the formation of lanreotide nanotubes: i), the specificity of two of the three aromatic side chains, ii), the spatial arrangement of the hydrophilic and hydrophobic residues, and iii), the aromatic side chain in the β-turn of the molecule. When these molecular characteristics are modified, either the peptides lose their self-assembling capability or they form less-ordered architectures, such as amyloid fibers and curved lamellae. Thus we have determined key elements of the molecular origins of lanreotide nanotube formation.     

Afghan Hindu Kush: Where Eurasian Sub-Continent Gene Flows Converge

Despite being located at the crossroads of Asia, genetics of the Afghanistan populations have been largely overlooked. It is currently inhabited by five major ethnic populations: Pashtun, Tajik, Hazara, Uzbek and Turkmen. Here we present autosomal from a subset of our samples, mitochondrial and Y- chromosome data from over 500 Afghan samples among these 5 ethnic groups. This Afghan data was supplemented with the same Y-chromosome analyses of samples from Iran, Kyrgyzstan, Mongolia and updated Pakistani samples (HGDP-CEPH). The data presented here was integrated into existing knowledge of pan-Eurasian genetic diversity. The pattern of genetic variation, revealed by structure-like and Principal Component analyses and Analysis of Molecular Variance indicates that the people of Afghanistan are made up of a mosaic of components representing various geographic regions of Eurasian ancestry. The absence of a major Central Asian-specific component indicates that the Hindu Kush, like the gene pool of Central Asian populations in general, is a confluence of gene flows rather than a source of distinctly autochthonous populations that have arisen in situ: a conclusion that is reinforced by the phylogeography of both haploid loci.     

Optimized Multilocus Sequence Typing (MLST) Scheme for Trypanosoma cruzi

Trypanosoma cruzi, the aetiological agent of Chagas disease possess extensive genetic diversity. This has led to the development of a plethora of molecular typing methods for the identification of both the known major genetic lineages and for more fine scale characterization of different multilocus genotypes within these major lineages. Whole genome sequencing applied to large sample sizes is not currently viable and multilocus enzyme electrophoresis, the previous gold standard for T. cruzi typing, is laborious and time consuming. In the present work, we present an optimized Multilocus Sequence Typing (MLST) scheme, based on the combined analysis of two recently proposed MLST approaches. Here, thirteen concatenated gene fragments were applied to a panel of T. cruzi reference strains encompassing all known genetic lineages. Concatenation of 13 fragments allowed assignment of all strains to the predicted Discrete Typing Units (DTUs), or near-clades, with the exception of one strain that was an outlier for TcV, due to apparent loss of heterozygosity in one fragment. Monophyly for all DTUs, along with robust bootstrap support, was restored when this fragment was subsequently excluded from the analysis. All possible combinations of loci were assessed against predefined criteria with the objective of selecting the most appropriate combination of between two and twelve fragments, for an optimized MLST scheme. The optimum combination consisted of 7 loci and discriminated between all reference strains in the panel, with the majority supported by robust bootstrap values. Additionally, a reduced panel of just 4 gene fragments displayed high bootstrap values for DTU assignment and discriminated 21 out of 25 genotypes. We propose that the seven-fragment MLST scheme could be used as a gold standard for T. cruzi typing, against which other typing approaches, particularly single locus approaches or systematic PCR assays based on amplicon size, could be compared.