Genetic signatures of population change in the British golden eagle (<Emphasis Type="Italic">Aquila chrysaetos</Emphasis>)

The golden eagle (Aquila chrysaetos) was once widely distributed in the uplands of the British Isles, but is now extinct in Ireland, and largely confined to the highlands and islands of Scotland. As the precise extent and severity of the reduction in population size are unclear, it is important to understand how the population was affected by the decline. We therefore genotyped 13 polymorphic microsatellite loci in 172 individuals from the contemporary British population and compared their genetic diversity to 70 British and 9 Irish museum specimens. Despite the recent population decline, there is only slight evidence for a concomitant loss of genetic variation. Instead, two likelihood-based Bayesian methods provided evidence for a severe ancient genetic bottleneck, possibly caused by the fragmentation of a large mainland European population and/or the founding effects of colonising the British Isles. As the population persisted despite this ancient bottleneck, our conclusion is that there is limited need for intervention to augment the present-day genetic diversity. The main short-term objective of conservation measures should be to increase population sizes by continuous safeguarding of individuals and habitat management. Finally, we also confirmed that, for management purposes, the species should be considered a single population unit and that the extinct Irish population was not differentiated from the British one.     

In vitro antimicrobial activity and mechanism of action of novel carbohydrate fatty acid derivatives against Staphylococcus aureus and MRSA

Aims: This study investigates the antimicrobial activity and mode of action of novel carbohydrate fatty acid (CFA) derivatives against Staphylococcus aureus and methicillin‐resistant Staph. aureus (MRSA). Methods and Results: Minimum inhibitory concentrations (MICs) and the effect of CFA derivatives on lag phase were determined using a broth microdilution method. Lauric acid carbohydrate esters and corresponding ether analogues showed the greatest antimicrobial activity with MIC values between 0·04 and 0·16 mmol l^?1. Leakage studies at 260 nm following exposure to CFA derivatives at 4× MIC showed a significant increase in membrane permeability for all compounds, after c. 15 min exposure except for the lauric beta ether CFA derivative. Further assessment using both BacLight and luminescence ATP assays confirmed that an increase in membrane permeability and reduced metabolic activity was associated with CFA treatment. Conclusions: All strains were significantly inhibited by the novel compounds studied, and efficacy was related to specific structural features. Cell‐membrane permeabilization was associated with CFA treatment and may account for at least a component of the mode of action of these compounds. Significance and Impact of the Study: This study reports the antimicrobial action of CFA compounds against a range of Staph. aureus and MRSA strains, and provides insights into their mode of action.     

Fine‐scale spatial genetic structure of common and declining bumble bees across an agricultural landscape

Land‐use changes have threatened populations of many insect pollinators, including bumble bees. Patterns of dispersal and gene flow are key determinants of species' ability to respond to land‐use change, but have been little investigated at a fine scale (<10 km) in bumble bees. Using microsatellite markers, we determined the fine‐scale spatial genetic structure of populations of four common Bombus species (B. terrestris, B. lapidarius, B. pascuorum and B. hortorum) and one declining species (B. ruderatus) in an agricultural landscape in Southern England, UK. The study landscape contained sown flower patches representing agri‐environment options for pollinators. We found that, as expected, the B. ruderatus population was characterized by relatively low heterozygosity, number of alleles and colony density. Across all species, inbreeding was absent or present but weak (F_IS = 0.01–0.02). Using queen genotypes reconstructed from worker sibships and colony locations estimated from the positions of workers within these sibships, we found that significant isolation by distance was absent in B. lapidarius, B. hortorum and B. ruderatus. In B. terrestris and B. pascuorum, it was present but weak; for example, in these two species, expected relatedness of queens founding colonies 1 m apart was 0.02. These results show that bumble bee populations exhibit low levels of spatial genetic structure at fine spatial scales, most likely because of ongoing gene flow via widespread queen dispersal. In addition, the results demonstrate the potential for agri‐environment scheme conservation measures to facilitate fine‐scale gene flow by creating a more even distribution of suitable habitats across landscapes.     

Molecular phylogeny of the Myzorhynchella Section of Anopheles (Nyssorhynchus) (Diptera: Culicidae): genetic support for recently described and resurrected species

Phylogenetic relationships among species of the Myzorhynchella Section of Anopheles (Nyssorhynchus) were investigated using the nuclear ribosomal DNA second internal transcribed spacer (ITS2), the nuclear whitegene and mitochondrial cytochrome oxidase subunit I (COI) regions. The recently described Anopheles pristinus and resurrected Anopheles guarani were also included in the study. Bayesian phylogenetic analyses found Anopheles parvus to be the most distantly related species within the Section, a finding that is consistent with morphology. An. pristinus and An. guarani were clearly resolved from Anopheles antunesi and Anopheles lutzii, respectively. An. lutzii collected in the same mountain range as the type locality were found within a strongly supported clade, whereas individuals from the southern state of Rio Grande do Sul, tentatively identified as An. lutzii based on adult female external morphology, were distinct from An. lutzii, An. antunesi and from each other, and may therefore represent two new sympatric species. A more detailed examination of An. lutzii sensu latoalong its known geographic range is recommended to resolve these anomalous relationships.     

Vaccinia virus protein C6 is a virulence factor that binds TBK-1 adaptor proteins and inhibits activation of IRF3 and IRF7

Recognition of viruses by pattern recognition receptors (PRRs) causes interferon-β (IFN-β) induction, a key event in the anti-viral innate immune response, and also a target of viral immune evasion. Here the vaccinia virus (VACV) protein C6 is identified as an inhibitor of PRR-induced IFN-β expression by a functional screen of select VACV open reading frames expressed individually in mammalian cells. C6 is a member of a family of Bcl-2-like poxvirus proteins, many of which have been shown to inhibit innate immune signalling pathways. PRRs activate both NF-κB and IFN regulatory factors (IRFs) to activate the IFN-β promoter induction. Data presented here show that C6 inhibits IRF3 activation and translocation into the nucleus, but does not inhibit NF-κB activation. C6 inhibits IRF3 and IRF7 activation downstream of the kinases TANK binding kinase 1 (TBK1) and IκB kinase-ε (IKKε), which phosphorylate and activate these IRFs. However, C6 does not inhibit TBK1- and IKKε-independent IRF7 activation or the induction of promoters by constitutively active forms of IRF3 or IRF7, indicating that C6 acts at the level of the TBK1/IKKε complex. Consistent with this notion, C6 immunoprecipitated with the TBK1 complex scaffold proteins TANK, SINTBAD and NAP1. C6 is expressed early during infection and is present in both nucleus and cytoplasm. Mutant viruses in which the C6L gene is deleted, or mutated so that the C6 protein is not expressed, replicated normally in cell culture but were attenuated in two in vivo models of infection compared to wild type and revertant controls. Thus C6 contributes to VACV virulence and might do so via the inhibition of PRR-induced activation of IRF3 and IRF7.     

Observations on orchid seed mycorrhizae

Summary In the natural germination of orchid seeds, the fungus undoubtedly contributes sugars, auxins, and growth factors in stimulating the growth of the embryo. However, none of these factors alone are as successful in stimulating germination as they are when combined. No single factor can be identified as the specific germination agent in the mycorrhizal relationship. Seeds can germinate, although poorly and slowly, without added sugars or auxins. Rather, a combination of factors promoting vigorous aerobic respiration provides the cellular environment necessary for germination. Fungus infection in nature, or artificial media in the lab, can provide these conditions: either rapidly by providing exogenous substrates and growth factors for respiration; or slowly by stimulating the utilization of endogenous lipid seed reserves. In either case, cell division and synthesis of chlorophyll follow. A speculatory metabolic pathway is outlined.     

Enrichment from Birth Accelerates the Functional and Cellular Development of a Motor Control Area in the Mouse

Background

There is strong evidence that sensory experience in early life has a profound influence on the development of sensory circuits. Very little is known, however, about the role of experience in the early development of striatal networks which regulate both motor and cognitive function. To address this, we have investigated the influence of early environmental enrichment on motor development.

Methodology/Principal Findings

Mice were raised in standard or enriched housing from birth. For animals assessed as adults, half of the mice had their rearing condition reversed at weaning to enable the examination of the effects of pre- versus post-weaning enrichment. We found that exclusively pre-weaning enrichment significantly improved performance on the Morris water maze compared to non-enriched mice. The effects of early enrichment on the emergence of motor programs were assessed by performing behavioural tests at postnatal day 10. Enriched mice traversed a significantly larger region of the test arena in an open-field test and had improved swimming ability compared to non-enriched cohorts. A potential cellular correlate of these changes was investigated using Wisteria-floribunda agglutinin (WFA) staining to mark chondroitin-sulfate proteoglycans (CSPGs). We found that the previously reported transition of CSPG staining from striosome-associated clouds to matrix-associated perineuronal nets (PNNs) is accelerated in enriched mice.

Conclusions/Significance

This is the first demonstration that the early emergence of exploratory as well as coordinated movement is sensitive to experience. These behavioural changes are correlated with an acceleration of the emergence of striatal PNNs suggesting that they may consolidate the neural circuits underlying these behaviours. Finally, we confirm that pre-weaning experience can lead to life long changes in the learning ability of mice.     

An ultra-dense integrated linkage map for hexaploid chrysanthemum enables multi-allelic QTL analysis

Key message

We constructed the first integrated genetic linkage map in a polysomic hexaploid. This enabled us to estimate inheritance of parental haplotypes in the offspring and detect multi-allelic QTL.

Abstract

Construction and use of linkage maps are challenging in hexaploids with polysomic inheritance. Full map integration requires calculations of recombination frequency between markers with complex segregation types. In addition, detection of QTL in hexaploids requires information on all six alleles at one locus for each individual. We describe a method that we used to construct a fully integrated linkage map for chrysanthemum (Chrysanthemum × morifolium, 2n = 6x = 54). A bi-parental F1 population of 406 individuals was genotyped with an 183,000 SNP genotyping array. The resulting linkage map consisted of 30,312 segregating SNP markers of all possible marker dosage types, representing nine chromosomal linkage groups and 107 out of 108 expected homologues. Synteny with lettuce (Lactuca sativa) showed local colinearity. Overall, it was high enough to number the chrysanthemum chromosomal linkage groups according to those in lettuce. We used the integrated and phased linkage map to reconstruct inheritance of parental haplotypes in the F1 population. Estimated probabilities for the parental haplotypes were used for multi-allelic QTL analyses on four traits with different underlying genetic architectures. This resulted in the identification of major QTL that were affected by multiple alleles having a differential effect on the phenotype. The presented linkage map sets a standard for future genetic mapping analyses in chrysanthemum and closely related species. Moreover, the described methods are a major step forward for linkage mapping and QTL analysis in hexaploids.