Greater energy stores enable flightless moulting geese to increase resting behaviour

Many species of waterfowl undergo a post‐breeding simultaneous flight feather moult (wing moult) which renders them flightless and vulnerable to predation for up to 4 weeks. Here we present an analysis of the correlations between individual time‐budgets and body mass states in 13 captive Barnacle Geese Branta leucopsis throughout an entire wing moult. The daily percentage of time spent resting was positively correlated with initial body mass at the start of wing moult. Behaviour of individual birds during wing moult is dependent on initial physiological state, which may in turn be dependent on foraging ability; the storage of energy before the start of wing moult will help birds to reduce exposure to the dangers of predation.     

Environmental Vibrio parahaemolyticus DNA signatures validation

Insignia is a novel DNA computational system which uses highly efficient algorithms to compare bacterial genomes and to identify specific DNA signatures to distinguish a target bacterium, or group of bacteria, from all other known bacterial species. It is currently being validated using different bacterial groups, including Vibrio spp. In this study, the genomic analysis by Insignia was conducted on Vibrio parahaemolyticus, a halophilic gram-negative bacteria which constitutes a leading cause of seafood-borne disease. Insignia was used to identify 37 V. parahaemolyticus-specific signatures and to design PCR assays to validate the representative signature sequences by TaqMan essays. The 37 assays targeted loci distributed around the genome and detected genes coding for hypothetical proteins and for proteins involved in adhesion, starvation and virulence. A panel of V. parahaemolyticus environmental strains isolated from the North Adriatic Sea (Italy) and from the Black Sea (Georgia) was used to validate the selected signatures. The signature assays revealed both sensitive and specific and the method allowed a more accurate identification of the tested bacterial strains at the species level when compared to biochemical and PCR standard methods. Using Insignia, it was possible to distinguish two different groups among the strains previously identified as V. parahaemolyticus: most of the strains were included in a "V. parahaemolyticus-like group" showing nearly all of the signatures assayed while a small group of 10 strains contained only a few of the signatures tested. By sequencing the 16S rDNA of this latter group, it was confirmed that they were not V. parahaemolyticus but in fact belonged to other Vibrio species. No significant genome-wide differences were detected between the strains isolated in Italy and in Georgia though the very different geographical origin.     

Stage-specific effects of Campoletis sonorensis parasitism on Heliothis virescens development and prothoracic glands

Abstract The ichneumonid endoparasitoid Campoletis sonorensis Cameron (Hymenoptera: Ichneumonidae) injects a polydnavirus when it oviposits into a host. We compared the development of Heliothis virescens (F.) (Lepidoptera: Noctuidae) larvae parasitized in the penultimate (fourth) stadium with those parasitized in the last (fifth) stadium by C.sonorensis and show that hosts stung in the fifth stadium exhibited arrested or delayed development compared to the controls. Parasitoids developed normally to the point of emergence in larvae stung in the fifth stadium but most did not successfully emerge from the host. The prothoracic glands in all successfully parasitized fifth stadium hosts and most unsuccessfully parasitized fifth stadium hosts showed some degree of virally-induced degeneration. Larvae stung in the fourth stadium developed more slowly than controls and either did not moult or developed to a fifth and sometimes a supernumerary sixth stadium before parasitoid emergence. Unsuccessfully parasitized hosts were delayed in their development but eventually moulted to the fifth and, in some cases, a supernumerary sixth stadium before pupating. Hosts stung in the fourth stadium showed no signs of prothoracic gland degeneration whether successfully parasitized or not. In addition, calyx fluid injections into early fourth stadium hosts did not cause prothoracic gland degeneration even after these hosts moulted to the fifth stadium, suggesting that degeneration induced by polydnavirus is specific to the last stadium of the host.     

Genome-wide miRNA signatures of human longevity

Little is known about the functions of miRNAs in human longevity. Here, we present the first genome-wide miRNA study in long-lived individuals (LLI) who are considered a model for healthy aging. Using a microarray with 863 miRNAs, we compared the expression profiles obtained from blood samples of 15 centenarians and nonagenarians (mean age 96.4 years) with those of 55 younger individuals (mean age 45.9 years). Eighty miRNAs showed aging-associated expression changes, with 16 miRNAs being up-regulated and 64 down-regulated in the LLI relative to the younger probands. Seven of the eight selected aging-related biomarkers were technically validated using quantitative RT-PCR, confirming the microarray data. Three of the eight miRNAs were further investigated in independent samples of 15 LLI and 17 younger participants (mean age 101.5 and 36.9 years, respectively). Our screening confirmed previously published miRNAs of human aging, thus reflecting the utility of the applied approach. The hierarchical clustering analysis of the miRNA microarray expression data revealed a distinct separation between the LLI and the younger controls (P-value < 10(-5) ). The down-regulated miRNAs appeared as a cluster and were more often reported in the context of diseases than the up-regulated miRNAs. Moreover, many of the differentially regulated miRNAs are known to exhibit contrasting expression patterns in major age-related diseases. Further in silico analyses showed enrichment of potential targets of the down-regulated miRNAs in p53 and other cancer pathways. Altogether, synchronized miRNA-p53 activities could be involved in the prevention of tumorigenesis and the maintenance of genomic integrity during aging.     

A tropical bird can use the equatorial change in sunrise and sunset times to synchronize its circannual clock

At higher latitudes, most organisms use the periodic changes in day length to time their annual life cycle. At the equator, changes in day length are minimal, and it is unknown which cues organisms use to synchronize their underlying circannual rhythms to environmental conditions. Here, we demonstrate that the African stonechat (Saxicola torquatus axillaris)-an equatorial songbird-can use subtle solar cues for the annual timing of postnuptial moult, a reliable marker of the circannual cycle. We compared four groups that were kept over more than 3 years: (i) a control group maintained under constant equatorial day length, (ii) a 12-month solar time group maintained under equatorial day length, but including a simulation of the annual periodic change in sunrise and sunset times (solar time), (iii) a 14-month solar time group similar to the previous group but with an extended solar time cycle and (iv) a group maintained under a European temperate photoperiod. Within all 3 years, 12-month solar time birds were significantly more synchronized than controls and 14-month solar time birds. Furthermore, the moult of 12-month solar time birds occurred during the same time of the year as that of free-living Kenyan conspecifics. Thus, our data indicate that stonechats may use the subtle periodic pattern of sunrise and sunset at the equator to synchronize their circannual clock.     

Environmental adaptation of Francisella tularensis

Concerns over weaponizable bacteria have recently prompted considerable interest in Francisella tularensis (Ft). In addition to its potential illicit use, Ft occurs naturally in diverse ecological niches including mammals, arthropods, and fresh water protozoans. Here we review the current knowledge of Ft adaptation which has ramifications for both basic and applied research.     

Accounting for linkage disequilibrium in genome scans for selection without individual genotypes: The local score approach

Detecting genomic footprints of selection is an important step in the understanding of evolution. Accounting for linkage disequilibrium in genome scans increases detection power, but haplotype‐based methods require individual genotypes and are not applicable on pool‐sequenced samples. We propose to take advantage of the local score approach to account for linkage disequilibrium in genome scans for selection, cumulating (possibly small) signals from single markers over a genomic segment, to clearly pinpoint a selection signal. Using computer simulations, we demonstrate that this approach detects selection with higher power than several state‐of‐the‐art single‐marker, windowing or haplotype‐based approaches. We illustrate this on two benchmark data sets including individual genotypes, for which we obtain similar results with the local score and one haplotype‐based approach. Finally, we apply the local score approach to Pool‐Seq data obtained from a divergent selection experiment on behaviour in quail and obtain precise and biologically coherent selection signals: while competing methods fail to highlight any clear selection signature, our method detects several regions involving genes known to act on social responsiveness or autistic traits. Although we focus here on the detection of positive selection from multiple population data, the local score approach is general and can be applied to other genome scans for selection or other genomewide analyses such as GWAS.     

Sexes in gynodioecious Geranium sylvaticum do not differ in their isotopic signature or photosynthetic capacity

• In gynodioecious plants, females are expected to produce more or better seeds than hermaphrodites in order to be maintained within the same population. Even though rarely measured, higher seed production can be achieved through differences in physiology.
• In this work, we measured sexual dimorphism in several physiological traits in the gynodioecious plant Geranium sylvaticum. Photosynthetic rate, stomatal conductance, transpiration rate, WUE and isotopic signatures were measured in plants growing in two habitats differing in light availability.
• Females have been reported to produce more seeds than hermaphrodites. However, we did not observe any significant difference in seed output between the sexes in these experimental populations. Similarly, the sexes did not differ in any physiological trait measured. Seed production was strongly limited by light availability. Likewise, differences between plants growing in full light versus low light were detected in most physiological parameters measured.
• Our results show that the sexes in G. sylvaticum do not show any evidence of sexual dimorphism in physiology, which concurred with a lack of sexual differences in seed output.