An eye for detail: selective sexual imprinting in zebra finches

To investigate the idea that sexual imprinting creates incipient reproductive isolation between phenotypically diverging populations, I performed experiments to determine whether colony-reared zebra finches would imprint on details of artificial white crests. In the first experiment, adults in one breeding colony wore white crests with a vertical black stripe, while in another colony adults wore crests having a horizontal black stripe; except for their crests, breeders possessed wild-type plumage and conformation. Offspring of both sexes reared in these colonies developed mate preferences for opposite-sexed birds wearing the crest type with which they were reared; neither sex developed a social preference for crested individuals of the same sex. In a second experiment, females reared by crested parents preferred crested males versus males with red leg bands, while control females (reared in a colony of wild-type, uncrested birds) preferred red-banded males in the same test. Results of a third experiment that used sexually dimorphic crest phenotypes indicate that both sexes of offspring imprinted on maternal crest patterns. Results support the hypothesis that sexual imprinting can facilitate isolation both by engendering a preference for population-typical traits and by prioritizing such an imprinting-based preference over species-typical preferences for other traits used in mate choice. Comparison with results of other recent studies indicates that imprinting tendencies of both sexes vary with the characteristics of traits presented as an imprinting stimuli. Tendency to imprint may vary with the perceived information content (e.g., kin, sex, or population indicator) of parental traits, a process dubbed selective sexual imprinting.     

Crystal structure of phosphatidylglycerophosphatase (PGPase), a putative membrane-bound lipid phosphatase, reveals a novel binuclear metal binding site and two "proton wires"

Phosphatidylglycerophosphatase (PGPase), an enzyme involved in lipid metabolism, catalyzes formation of phosphatidylglycerol from phosphatidylglycerophosphate. Phosphatidylglycerol is a multifunctional phospholipid, found in the biological membranes of many organisms. Here, we report the crystal structure of Listeria monocytogenes PGPase at 1.8 A resolution. PGPase, an all-helical molecule, forms a homotetramer. Each protomer contains an independent active site with two metal ions, Ca(2+) and Mg(2+), forming a hetero-binuclear center located in a hydrophilic cavity near the surface of the molecule. The binuclear center, conserved ligands, metal-bound water molecules, and an Asp-His dyad form the active site. The catalytic mechanism of this enzyme is likely to proceed via binuclear metal activated nucleophilic water. The binuclear metal-binding active-site environment of this structure should provide insights into substrate binding and metal-dependent catalysis. A long channel with inter-linked linear water chains, termed "proton wires," is observed at the tetramer interface. Comparison of similar water chain structures in photosynthetic reaction centers (RCs), Cytochrome f, gramicidin, and bacteriorhodopsin, suggests that PGPase may conduct protons via proton wires.     

Influence of colour-banding on the conspecific preferences of zebra finches

Male and female zebra finches are affected by the colour of plastic leg bands worn by opposite-sex conspecifics. They find certain colours more attractive, and others less attractive, than the natural unbanded condition. Females prefer red-banded males over unbanded ones, and avoid light-blue and light-green banded males. Males prefer black and pink banded females and avoid those wearing light-blue or light-green bands. These findings may have utility for the study of mate choice in monogramous species; they also raise important questions about a widely used experimental technique.     

A global quantitative synthesis of local and landscape effects on wild bee pollinators in agroecosystems

Bees provide essential pollination services that are potentially affected both by local farm management and the surrounding landscape. To better understand these different factors, we modelled the relative effects of landscape composition (nesting and floral resources within foraging distances), landscape configuration (patch shape, interpatch connectivity and habitat aggregation) and farm management (organic vs. conventional and local‐scale field diversity), and their interactions, on wild bee abundance and richness for 39 crop systems globally. Bee abundance and richness were higher in diversified and organic fields and in landscapes comprising more high‐quality habitats; bee richness on conventional fields with low diversity benefited most from high‐quality surrounding land cover. Landscape configuration effects were weak. Bee responses varied slightly by biome. Our synthesis reveals that pollinator persistence will depend on both the maintenance of high‐quality habitats around farms and on local management practices that may offset impacts of intensive monoculture agriculture.     

Impact of amino acid mutations in PB2, PB1-F2, and NS1 on the replication and pathogenicity of pandemic (H1N1) 2009 influenza viruses

Here, we assessed the effects of PB1-F2 and NS1 mutations known to increase the pathogenicity of influenza viruses on the replication and pathogenicity in mice of pandemic (H1N1) 2009 influenza viruses. We also characterized viruses possessing a PB1-F2 mutation that was recently identified in pandemic (H1N1) 2009 influenza virus isolates, with and without simultaneous mutations in PB2 and NS1. Our results suggest that some NS1 mutations and the newly identified PB1-F2 mutation have the potential to increase the replication and/or pathogenicity of pandemic (H1N1) 2009 influenza viruses.     

X-ray structures of two proteins belonging to Pfam DUF178 revealed unexpected structural similarity to the DUF191 Pfam family

Background  

Pfam is a comprehensive collection of protein domains and families, with a range of well-established information including genome annotation. Pfam has two large series of functionally uncharacterized families, known as Domains of Unknown Function (DUFs) and Uncharacterized Protein Families (UPFs).