Novel Virulent and Broad-Host-Range Erwinia amylovora Bacteriophages Reveal a High Degree of Mosaicism and a Relationship to Enterobacteriaceae Phages

A diverse set of 24 novel phages infecting the fire blight pathogen Erwinia amylovora was isolated from fruit production environments in Switzerland. Based on initial screening, four phages (L1, M7, S6, and Y2) with broad host ranges were selected for detailed characterization and genome sequencing. Phage L1 is a member of the Podoviridae, with a 39.3-kbp genome featuring invariable genome ends with direct terminal repeats. Phage S6, another podovirus, was also found to possess direct terminal repeats but has a larger genome (74.7 kbp), and the virus particle exhibits a complex tail fiber structure. Phages M7 and Y2 both belong to the Myoviridae family and feature long, contractile tails and genomes of 84.7 kbp (M7) and 56.6 kbp (Y2), respectively, with direct terminal repeats. The architecture of all four phage genomes is typical for tailed phages, i.e., organized into function-specific gene clusters. All four phages completely lack genes or functions associated with lysogeny control, which correlates well with their broad host ranges and indicates strictly lytic (virulent) lifestyles without the possibility for host lysogenization. Comparative genomics revealed that M7 is similar to E. amylovora virus ΦEa21-4, whereas L1, S6, and Y2 are unrelated to any other E. amylovora phage. Instead, they feature similarities to enterobacterial viruses T7, N4, and ΦEcoM-GJ1. In a series of laboratory experiments, we provide proof of concept that specific two-phage cocktails offer the potential for biocontrol of the pathogen.     

Predictive algorithms for adjuvant therapy: TransATAC

Estrogen receptor (ER) positive primary breast cancers have a wide range of clinical outcomes. Prediction of the likely course of the disease aids treatment decision-making. In the translational arm of the ATAC (anastrozole or tamoxifen alone or combined) trial (TransATAC) we have assessed individual and multiparameter biomarkers for their prediction of overall and distant recurrence. None of the biomarkers identified differential benefit for anastrozole versus tamoxifen. Each of ER, PgR, HER2 and Ki67 was associated with risk of recurrence. A combination of these to create a single predictor IHC4 was as informative as the 21-gene recurrence score (RS). Integration of each of these molecular profiles with classical clinicopathologic variables provided the most accurate prediction of outcome.     

Modelling topoisomerase I inhibition by minor groove binders

Topoisomerase inhibition is an extremely useful target for anticancer and antimicrobial drugs, and an undesirable side effect of some drugs targeting other proteins. Published modelling studies are sparse, and have used small data sets with relatively low molecular diversity. Given the important role of minor groove binding in the mechanism of topoisomerase I inhibition, we have conducted the first 3D QSAR study of topoisomerase I inhibition of a large, diverse set of minor groove binders using the minor groove binding conformation as the alignment template. The highly significant QSAR models resulting from this alignment identify the roles played by molecular features, most importantly the hydrogen bond donor properties.     

Quantitative analysis of the interaction strength and dynamics of human IgG4 half molecules by native mass spectrometry

Native mass spectrometry (MS) is a powerful technique for studying noncovalent protein-protein interactions. Here, native MS was employed to examine the noncovalent interactions involved in homodimerization of antibody half molecules (HL) in hinge-deleted human IgG4 (IgG4Δhinge). By analyzing the concentration dependence of the relative distribution of monomer HL and dimer (HL)(2) species, the apparent dissociation constant (K(D)) for this interaction was determined. In combination with site-directed mutagenesis, the relative contributions of residues at the CH3-CH3 interface to this interaction could be characterized and corresponding K(D) values quantified over a range of 10(-10)-10(-4) M. The critical importance of this noncovalent interaction in maintaining the intact dimeric structure was also proven for the full-length IgG4 backbone. Using time-resolved MS, the kinetics of the interaction could be measured, reflecting the dynamics of IgG4 HL exchange. Hence, native MS has provided a quantitative view of local structural features that define biological properties of IgG4.     

Female Canaries (Serinus canaria) Associate more with Males that Contrast Strongly against the Background

Male birds with bright plumage colors which entail production costs and increased predation risks should be able to emphasize the handicap function of their ornaments when they present themselves against a contrasting background. Contrast with the background may accentuate the signal's costliness and make the male more conspicuous to predators. Both effects should contribute to increase male attractiveness. It is therefore conceivable that the extent to which the male plumage contrasts against the background modifies female choice behavior as it improves the discrimination of mates. We tested this hypothesis in domesticated canaries (Serinus canaria). In the first experiment, yellow females could choose between two yellow males presented in front of a yellow and a white background, respectively. In the second experiment we replaced the yellow males with white ones. In experiment 1 females associated significantly more with yellow males which contrasted strongly against the white background. In experiment 2 there was at least a trend for preferred associations with the white male in front of the yellow background. We found no support that male properties per se were chosen. We could further clarify that females associated with the contrasting male and not with a particular background color. Thus, our study demonstrates that not only inherent properties of the sender but also the interaction of bird color with the signaling environment may influence mate choice.     

A preliminary revision of the genus Plecotus (Chiroptera, Vespertilionidae) based on genetic and morphological results

The phylogenetic relationships within the genus Plecotus were assessed using molecular as well as morphological methods. With only three species missing, our study is based on an almost comprehensive taxonomic sampling. The genetic analysis comprised 151 individuals from throughout the range. Sequences of two mitochondrial sections, parts of the 16S rRNA gene (16S) and of the control region (CR) were analysed. The morphological analysis of cranial and external characters comprised 697 individuals, including 10 holotypes and one lectotype. Data from 15 craniometric characters of 442 specimens were used in the multivariate analyses. The molecular data identified nine primary clades representing 11 species, 10 of which could be assigned to described taxa, whereas one was described as a new species, Plecotus strelkovi Spitzenberger sp. nov. The tree based on 16S revealed two major lineages, one consisting of only one primary clade restricted to the Mediterranean, the other consisting of eight primary clades representing Eurasian taxa. The morphological analysis revealed five additional species, two of them not described. Together with the recently described P. taivanus, P. sardus and P. balensis, which were not included in our analysis, the genus Plecotus comprises at least 19 more or less cryptic species. Phylogenetic and phenetic analyses resulted in similar but not completely concordant arrangements of the species. The proposed classification relies mainly on the tree based on 16S sequences. The current distribution indicates that 16 species can be linked to arboreal refugia, three to eremial refugia. We assume that speciation within the gleaning, rather slow flying long‐eared bats is due to a multitude of disruption and isolation processes within a formerly continuous range of the broad‐leaved Arcto‐Tertiary forest in which Plecotus probably originated. An exact calibrated molecular dating of the splits is not possible. The Early Oligocene age of the presumed ancestor of the Plecotini and a correlation of the molecular diversifications with palaeogeographic reconstructions suggest that the divergence of the two major lineages may have occurred already during the Middle Miocene, 14.5 Mya.     

Brood parasitism of White-rumped Swallows by Shiny Cowbirds

ABSTRACT.   Swallows and martins are infrequent hosts of the generalist brood parasite Shiny Cowbird ( Molothrus bonariensis ). We monitored 50 nesting attempts by White-rumped Swallows ( Tachycineta leucorrhoa ) over a two-year period in Argentina and detected low rates of brood parasitism (three nests, or 6%). Of the three nests parasitized, cowbirds ( N = 1 per nest) successfully fledged from two. Eight of 13 swallow eggs in these three nests were punctured by cowbirds, and all but one swallow nesting starved at the two parasitized nests. At least two factors may contribute to the low frequency of parasitism of White-rumped Swallows by Shiny Cowbirds, including the inability of the larger cowbirds to enter some nest cavities and the aggressive nest defense behavior of adult swallows.     

Antigenic targeting of the human mannose receptor induces tumor immunity

Pattern recognition receptors are preferentially expressed on APCs allowing selective uptake of pathogens for the initiation of antimicrobial immunity. In particular, C-type lectin receptors, including the mannose receptor (MR), facilitate APC-mediated adsorptive endocytosis of microbial glyconjugates. We have investigated the potential of antigenic targeting to the MR as a means to induce Ag-specific humoral and cellular immunity. hMR transgenic (hMR Tg) mice were generated to allow specific targeting with the anti-hMR Ab, B11. We show that hMR targeting induced both humoral and cellular antigenic specific immunity. Immunization of hMR Tg mice with B11 mAbs induced potent humoral responses independent of adjuvant. Injection of hMR Tg mice with mouse anti-hMR Ab clone 19.2 elicited anti-Id-specific humoral immunity while non-Tg mice were unresponsive. B11-OVA fusion proteins (B11-OVA) were efficiently presented to OVA-specific CD4 and CD8 T cells in MR Tg, but not in non-Tg, mice. Effector differentiation of responding T cells in MR Tg mice was significantly enhanced with concomitant immunization with the TLR agonist, CpG. Administration of both CpG and B11-OVA to hMR Tg mice induced OVA-specific tumor immunity while WT mice remained unprotected. These studies support the clinical development of immunotherapeutic approaches in cancer using pattern recognition receptor targeting systems for the selective delivery of tumor Ags to APCs.