Disrupted phylogeographical microsatellite and chloroplast DNA patterns indicate a vicariance rather than long‐distance dispersal origin for the disjunct distribution of the Chilean endemic Dioscorea biloba (Dioscoreaceae) around the Atacama Desert

Aim The Chilean endemic Dioscorea biloba (Dioscoreaceae) is a dioecious geophyte that shows a remarkable 600 km north–south disjunction in the peripheral arid area of the Atacama Desert. Its restricted present‐day distribution and probable Neogene origin indicate that its populations have a history linked to that of the Atacama Desert, making this an ideal model species with which to investigate the biogeography of the region. Location Chile, Atacama Desert and peripheral arid area. Methods Two hundred and seventy‐five individuals from nine populations were genotyped for seven nuclear microsatellite loci, and plastid trnL–F and trnT–L sequences were obtained for a representative subset of these. Analyses included the estimation of genetic diversity and population structure through clustering, Bayesian and analysis of molecular variance analyses, and statistical parsimony networks of chloroplast haplotypes. Isolation by distance was tested against alternative dispersal hypotheses. Results Microsatellite markers revealed moderate to high levels of genetic diversity within populations, with those from the southern Limarí Valley showing the highest values and northern populations showing less exclusive alleles. Bayesian analysis of microsatellite data identified three genetic groups that corresponded to geographical ranges. Chloroplast phylogeography revealed no haplotypes shared between northern and southern ranges, and little haplotype sharing between the two neighbouring southern valleys. Dispersal models suggested the presence of extinct hypothetical populations between the southern and northern ranges. Main conclusions Our results are consistent with prolonged isolation of the northern and southern groups, mediated by the life‐history traits of the species. Significant isolation was revealed at both large and moderate distances as gene flow was not evident even between neighbouring valleys. Bayesian analyses of microsatellite and chloroplast haplotype diversity identified the southern area of Limarí as the probable area of origin of the species. Our data do not support recent dispersal of D. biloba from the southern range into Antofagasta, but indicate the fragmentation of an earlier wider range, concomitant with the Pliocene–Pleistocene climatic oscillations, with subsequent extinctions of the Atacama Desert populations and the divergence of the peripheral ones as a consequence of genetic drift.     

Two-dimensional Fourier analysis of the spongy medullary keratin of structurally coloured feather barbs

We conducted two-dimensional (2D) discrete Fourier analyses of the spatial variation in refractive index of the spongy medullary keratin from four different colours of structurally coloured feather barbs from three species of bird: the rose-faced lovebird, Agapornis roseicollis (Psittacidae), the budgerigar, Melopsittacus undulatus (Psittacidae), and the Gouldian finch, Poephila guttata (Estrildidae). These results indicate that the spongy medullary keratin is a nanostructured tissue that functions as an array of coherent scatterers. The nanostructure of the medullary keratin is nearly uniform in all directions. The largest Fourier components of spatial variation in refractive index in the tissue are of the appropriate size to produce the observed colours by constructive interference alone. The peaks of the predicted reflectance spectra calculated from the 2D Fourier power spectra are congruent with the reflectance spectra measured by using microspectrophotometry. The alternative physical models for the production of these colours, the Rayleigh and Mie theories, hypothesize that medullary keratin is an incoherent array and that scattered waves are independent in phase. This assumption is falsified by the ring-like Fourier power spectra of these feathers, and the spacing of the scattering air vacuoles in the medullary keratin. Structural colours of avian feather barbs are produced by constructive interference of coherently scattered light waves from the optically heterogeneous matrix of keratin and air in the spongy medullary layer.     

Ocean Acidification and Increased Temperature Have Both Positive and Negative Effects on Early Ontogenetic Traits of a Rocky Shore Keystone Predator Species

The combined effect of ocean acidification and warming is expected to have significant effects on several traits of marine organisms. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal habitats of southern Chile (39°S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits. The individuals were exposed long-term (5.8 months) to contrasting pCO₂ (ca. 500 and 1400 μatm) and temperature (15 and 19°C) levels. After this period we compared body growth traits, dislodgement resistance, predator-escape response, self-righting and metabolic rates. With respect to these traits there was no evidence of a synergistic interaction between pCO₂ and temperature. Shell growth was negatively affected by high pCO₂ levels only at 15°C. High pCO₂ levels also had a negative effect on the predator-escape response. Conversely, dislodgement resistance and self-righting were positively affected by high pCO₂ levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO₂ levels on other important defensive traits such as shell size and escape behaviour. We conclude that climate change might produce in C. concholepas positive and negative effects in physiology and behaviour. In fact, some of the behavioural responses might be a consequence of physiological effects, such as changes in chemosensory capacity (e.g. predator-escape response) or secretion of adhesive mucous (e.g. dislodgement resistance). Moreover, we conclude that positive behavioural responses may assist in the adaptation to negative physiological impacts, and that this may also be the case for other benthic organisms.     

Substantivity of zinc salts used as rinsing solutions and their effect on the inhibition of Streptococcus mutans

The antimicrobial efficacy of zinc (Zn) salts (sulfate and acetate) against Streptococcus mutans (S. mutans) present in the oral cavity was tested in this study. The substantivity of Zn salts was assessed by determining the concentration of Zn in whole, unstimulated saliva and by measuring the magnitude of suppression of salivary S. mutans, 2h after rinsing. The concentration of Zn was measured by atomic absorption spectrometry (AAS) with electrothermal atomization (ET AAS) in saliva sampled before (basal) and 24h after mouth rinsing with different concentrations of Zn (0.1%, 0.5% and 1%) administrated as sulfate and acetate. The estimation of Zn levels in samples collected 30, 60, 90 and 120 min after rinsing was carried out by AAS with flame atomization (FAAS). Immediately after rinsing, the concentration of Zn in saliva sharply increased with respect to the baseline values (0.055+/-0.017 mg/L), followed by a sustained decrease, probably due to clearance of salivary flow or swallowing during sampling. A significant reduction (>87%) in the total mean S. mutans counts was found 2h after rinsing either with sulfate or acetate solutions, as evidence of the high substantivity and effectiveness of the Zn salts tested. A statistically significant inverse relationship (p<0.001 and the Pearson correlation coefficients between -34% and -50%) was found between Zn levels and the respective pH values measured in the samples collected 60 and 120 min after rinsing, sustaining the theory of bacterial glycolysis inhibition.     

Multilocus and morphological analysis of south-eastern Iberian Wall lizards (Squamata,Podarcis)

The phylogenetic relationships among the wall lizards of the Podarcis hispanicus complex that inhabit the south-east (SE) of the Iberian Peninsula and other lineages of the complex remain unclear. In this study, four mitochondrial and two nuclear markers were used to study genetic relationships within this complex. The phylogenetic analyses based on mtDNA gene trees constructed with ML and BI, and a species tree using *BEAST support three divergent clades in this region: the Valencia, Galera and Albacete/Murcia lineages. These three lineages were also corroborated in species delimitation analyses based on mtDNA using bPTP, mPTP, GMYC, ABGD and BAPS. Bayesian inference species delimitation method (BPP) based on both nuclear data and a combined data set (mtDNA + nuclear) showed high posterior probabilities for these three SE lineages (≥0.94) and another Bayesian analysis (STACEY) based on combined data set recovered the same three groups in this region. Divergence time dating of the species tree provided an estimated divergence of the Galera lineage from the other SE group (Podarcis vaucheri, (Albacete/Murcia, Valencia)) at 12.48 Ma. During this period, the Betic–Rifian arc was isolated, which could have caused the isolation of the Galera form distributed to the south of the Betic Corridor. Although lizards from the Albacete/Murcia and Galera lineage are morphologically similar, they clearly represent distinct genetic lineages. The noteworthy separation of the Galera lineage enables us to conclude that this lineage must be considered as a new full species.     

Biological characterization of the lytic cycle of actinophage φA7 in Streptomyces antibioticus

Some basic parameters of the lytic development of phage phi A7 in Streptomyces antibioticus are described. One-step growth experiments demonstrated that at 28 degrees C phi A7 has a latent period of about 60 min and an exponential growth period of about 35 min. The average burst size ranged from 70-100 plaque forming units per infected cell. At the same temperature 50% of the virions were adsorbed to germ tubes of S. antibioticus in about 10 min. This corresponds to an adsorption constant of 6.5 x 10(-10) ml/min. The phage was unable to adsorb the host at other stages of the life cycle (spores or mycelium). Divalent cations are not required for phi A7 stability but Ca2+ proved to be essential for adsorption and also for a later stage of the vegetative development of the phage.     

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 2.

Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described.     

Recursive use of evolutionary conservation data in molecular modeling of membrane proteins A model of the multidrug H+ antiporter emrE.

Membrane proteins are currently the most biomedically important family of proteins, serving as targets for the majority of pharmaceutical agents. It is also clear that they are invariably abundant in all of the genomes sequence so far, representing up to a third of all open reading frames. Finally, and regrettably, it is clear that they are highly resistant to structural elucidation, representing less than 0.2% of the Protein Data Bank. Recent accomplishments in genome sequencing efforts, however, may help offset this imbalance through the availability of evolutionary conservation data. Herein, we develop a novel approach, utilizing a combination of evolutionary conservation data and global searching molecular dynamics simulations to model membrane proteins, deriving a model for the multidrug H+ antiporter EmrE, a transmembrane four-helix bundle. Structures resulting from an extensive, rotational molecular dynamics search, were evaluated by comparing the residue specific interaction energy and the evolutionary conservation data. Subsequent rounds of molecular dynamics, in which confinement of the search space was undertaken in order to achieve a self consistent result, point to a structure that best satisfies the evolutionary conservation data. As the conservation patterns calculated for each of the helices suggested that the different conservation pattern for helix 3 (as well as being the most conserved) might be due to the oligomeric nature of EmrE, a dodecamer of helices was constructed based on the result of a search of helix 3 as a trimer. The resulting interaction energy per residue in the final model is in reasonable agreement with the evolutionary data and consistent with recent site directed mutagenesis experiments, pointing to the strength of this method as a general tool.     

Relative Dominance Affects Use of Scent-Marked Areas in Male Snow Voles Chionomys nivalis

We conducted a laboratory experiment to examine whether dominance status affects the use of locations occupied (i.e. scent-marked) by same-sex conspecifics among wild-caught snow vole males ( Chionomys nivalis ). Given that the costs of invading scent-marked areas should partially depend on the intruder's competitive ability, we hypothesised that, once a dominance relationship has been established with the owner of marks, the use of these areas by males would vary differently between dominant and subordinate individuals. Before any previous experience with the owner, scented substrates and nests were highly attractive to all males, indicating a general preference for recently occupied areas. However, after relative social status was established through direct interaction the subsequent response of males was altered differently, subordinate individuals reducing the use of marked areas to a much greater extent than dominants. Competitive relationships between male C. nivalis were found to be influenced by differences in body weight, larger males tending to display a more dominant pattern of behaviour. Our results reveal that male C. nivalis may require some direct experience with potential opponents to modulate their response towards occupied locations. Additionally, we suggest that the ability of males to conditionally respond to social signals from particular competing conspecifics might be used to lower the costs of prospective agonistic interactions.