Dynamics of crowing development in the domestic Japanese quail (Coturnix coturnix japonica)

Species-specific behaviours gradually emerge, via incomplete patterns, to the final complete adult form. A classical example is birdsong, a learned behaviour ideally suited for studying the neural and molecular substrates of vocal learning. Young songbirds gradually transform primitive unstructured vocalizations (subsong, akin to human babbling) into complex, stereotyped sequences of syllables that constitute adult song. In comparison with birdsong, territorial and mating calls of vocal non-learner species are thought to exhibit little change during development. We revisited this issue using the crowing behaviour of domestic Japanese quail (Coturnix coturnix japonica). Crowing activity was continuously recorded in young males maintained in social isolation from the age of three weeks to four months. We observed developmental changes in crow structure, both the temporal and the spectral levels. Speed and trajectories of these developmental changes exhibited an unexpected high inter-individual variability. Mechanisms used by quails to transform sounds during ontogeny resemble those described in oscines during the sensorimotor phase of song learning. Studies on vocal non-learners could shed light on the specificity and evolution of vocal learning.     

Breeding bird species diversity across gradients of land use from forest to agriculture in Europe

Loss, fragmentation and decreasing quality of habitats have been proposed as major threats to biodiversity world‐wide, but relatively little is known about biodiversity responses to multiple pressures, particularly at very large spatial scales. We evaluated the relative contributions of four landscape variables (habitat cover, diversity, fragmentation and productivity) in determining different components of avian diversity across Europe. We sampled breeding birds in multiple 1‐km² landscapes, from high forest cover to intensive agricultural land, in eight countries during 2001?2002. We predicted that the total diversity would peak at intermediate levels of forest cover and fragmentation, and respond positively to increasing habitat diversity and productivity; forest and open‐habitat specialists would show threshold conditions along gradients of forest cover and fragmentation, and respond positively to increasing habitat diversity and productivity; resident species would be more strongly impacted by forest cover and fragmentation than migratory species; and generalists and urban species would show weak responses. Measures of total diversity did not peak at intermediate levels of forest cover or fragmentation. Rarefaction‐standardized species richness decreased marginally and linearly with increasing forest cover and increased non‐linearly with productivity, whereas all measures increased linearly with increasing fragmentation and landscape diversity. Forest and open‐habitat specialists responded approximately linearly to forest cover and also weakly to habitat diversity, fragmentation and productivity. Generalists and urban species responded weakly to the landscape variables, but some groups responded non‐linearly to productivity and marginally to habitat diversity. Resident species were not consistently more sensitive than migratory species to any of the landscape variables. These findings are relevant to landscapes with relatively long histories of human land‐use, and they highlight that habitat loss, fragmentation and habitat‐type diversity must all be considered in land‐use planning and landscape modeling of avian communities.     

Mucociliary Clearance Defects in a Murine In Vitro Model of Pneumococcal Airway Infection

Mucociliary airway clearance is an innate defense mechanism that protects the lung from harmful effects of inhaled pathogens. In order to escape mechanical clearance, airway pathogens including Streptococcus pneumoniae (pneumococcus) are thought to inactivate mucociliary clearance by mechanisms such as slowing of ciliary beating and lytic damage of epithelial cells. Pore-forming toxins like pneumolysin, may be instrumental in these processes. In a murine in vitro airway infection model using tracheal epithelial cells grown in air-liquid interface cultures, we investigated the functional consequences on the ciliated respiratory epithelium when the first contact with pneumococci is established. High-speed video microscopy and live-cell imaging showed that the apical infection with both wildtype and pneumolysin-deficient pneumococci caused insufficient fluid flow along the epithelial surface and loss of efficient clearance, whereas ciliary beat frequency remained within the normal range. Three-dimensional confocal microscopy demonstrated that pneumococci caused specific morphologic aberrations of two key elements in the F-actin cytoskeleton: the junctional F-actin at the apical cortex of the lateral cell borders and the apical F-actin, localized within the planes of the apical cell sides at the ciliary bases. The lesions affected the columnar shape of the polarized respiratory epithelial cells. In addition, the planar architecture of the entire ciliated respiratory epithelium was irregularly distorted. Our observations indicate that the mechanical supports essential for both effective cilia strokes and stability of the epithelial barrier were weakened. We provide a new model, where - in pneumococcal infection - persistent ciliary beating generates turbulent fluid flow at non-planar distorted epithelial surface areas, which enables pneumococci to resist mechanical cilia-mediated clearance.     

Immunoelectron microscopy of Bacillus subtilis cells secreting human interferon α1 or staphylokinase

Uptake of 14C-labelled chlorhexidine diacetate (14C-CHA) by wild-type and envelope mutant strains of Escherichia coli and Pseudomonas aeruginosa was very rapid. Maximum uptake was observed within a contact time of 20 s with no additional binding on increased contact, and was concentration-dependent. In contrast to this rapid binding of 14C-CHA, bactericidal studies revealed that the lethal activity of low concentrations of unlabelled CHA was slow, although higher concentrations had a rapid effect. Comparison of a wild-type strain with its envelope mutants indicated that there was little difference in 14C-CHA uptake, in minimal inhibitory concentrations or in bactericidal activity. Azolectin was found to be an effective neutralising agent of biguanide action, but in in vitro agar tests and in reducing or removing the amount of 14C-CHA taken up by the cells.     

Morphogenesis and nature of the pigment granules in the adult human retinal pigment epithelium

Summary The pigment epithelial cells of the retina are a layer of highly specialized melanocytes. Beginning in the early embryonic period they produce melanin throughout the entire life. The Golgi apparatus plays a key role in the biosynthesis of melanin. The following steps can be distinguished morphologically: (a) Golgi-vesicles, (b) intermediate vesicles, (c) melanosomes, (d) melanin granules. Structures with a ringlike appearance that are described as lipofuscin granules in the literature prove to be altered intermediate vesicles and melanosomes.This investigation was carried out in part at the Francis I. Proctor Foundation for Research in Ophthalmology, San Francisco, California, U.S.A., and supported by United States Public Health Service Program Project Grant EY 00310, and Deutsche Forschungsgemeinschaft, Training Grant Nr. Sp 102/1.     

Improving yeast two-hybrid screening systems.

Yeast two-hybrid (Y2H) screening methods are an effective means for the detection of protein-protein interactions. Optimisation and automation has increased the throughput of the method to an extent that allows the systematic mapping of protein-protein interactions on a proteome-wide scale. Since two-hybrid screens fail to detect a great number of interactions, parallel high-throughput approaches are needed for proteome-wide interaction screens. In this review, we discuss and compare different approaches for adaptation of Y2H screening to high-throughput, the limits of the method and possible alternative approaches to complement the mapping of organism-wide protein-protein interactions.     

The monoclonal antibody mAB 1A binds to the excitation--contraction coupling domain in the II-III loop of the skeletal muscle calcium channel alpha(1S) subunit

Interactions of the II-III loop of the voltage-gated Ca(2+) channel alpha(1S) subunit with the Ca(2+) release channel (RyR1) are essential for skeletal-type excitation-contraction (EC) coupling. Here, we characterized the binding site of the monoclonal alpha(1S) antibody mAB 1A and used it to probe the structure of the II-III loop in chimeras with different EC coupling properties. Phage-display epitope mapping of mAB 1A revealed a minimal consensus binding sequence X-P-X-X-D-X-P. Immunofluorescence labeling of (1S), alpha(1C), alpha(1D), and of II-III loop chimeras expressed in dysgenic myotubes established that mAB 1A reacted specifically with amino acids 737-744 in the II-III loop of alpha(1S), which is within the domain (D734-L764) critical for bidirectional coupling with RyR1. Comparing mAB 1A immunoreactivity with known structural and functional properties of II-III loop chimeras in which the non-conserved skeletal residues were systematically mutated to their cardiac counterparts indicated a correlation of mAB 1A immunoreactivity and skeletal-type EC coupling.