Sustained Protein Kinase D Activation Mediates Respiratory Syncytial Virus-Induced Airway Barrier Disruption

Understanding the regulation of airway epithelial barrier function is a new frontier in asthma and respiratory viral infections. Despite recent progress, little is known about how respiratory syncytial virus (RSV) acts at mucosal sites, and very little is known about its ability to influence airway epithelial barrier function. Here, we studied the effect of RSV infection on the airway epithelial barrier using model epithelia. 16HBE14o- bronchial epithelial cells were grown on Transwell inserts and infected with RSV strain A2. We analyzed (i) epithelial apical junction complex (AJC) function, measuring transepithelial electrical resistance (TEER) and permeability to fluorescein isothiocyanate (FITC)-conjugated dextran, and (ii) AJC structure using immunofluorescent staining. Cells were pretreated or not with protein kinase D (PKD) inhibitors. UV-irradiated RSV served as a negative control. RSV infection led to a significant reduction in TEER and increase in permeability. Additionally it caused disruption of the AJC and remodeling of the apical actin cytoskeleton. Pretreatment with two structurally unrelated PKD inhibitors markedly attenuated RSV-induced effects. RSV induced phosphorylation of the actin binding protein cortactin in a PKD-dependent manner. UV-inactivated RSV had no effect on AJC function or structure. Our results suggest that RSV-induced airway epithelial barrier disruption involves PKD-dependent actin cytoskeletal remodeling, possibly dependent on cortactin activation. Defining the mechanisms by which RSV disrupts epithelial structure and function should enhance our understanding of the association between respiratory viral infections, airway inflammation, and allergen sensitization. Impaired barrier function may open a potential new therapeutic target for RSV-mediated lung diseases.     

A narrow hybrid zone between the grasshoppers Stenobothrus clavatus and Stenobothrus rubicundus (Orthoptera: Gomphocerinae): female preferences for courtship songs

Two grasshopper species, Stenobothrus rubicundus and Stenobothrus clavatus, were previously shown to hybridize in a narrow contact zone on Mount Tomaros in northern Greece. The species are characterized by complex and completely different courtship songs. In the present study, we investigated female preferences for the courtship songs of S. rubicundus, S. clavatus and hybrids in playback experiments. Playback of the courtship songs revealed assortative preferences in females of the parental species: they significantly more often preferred the songs of conspecific males. Hybrid females showed a lower selectivity than parental females, responding somewhat equally eager to playback of the songs of S. clavatus, S. rubicundus, and natural hybrid song, although less actively to the F₁ hybrid song. The results suggest that hybrid males may lose to males of parental species, whereas hybrid females would even have an advantage over parental females. Comparison of responses of females from allopatric populations and Mount Tomaros to different song types shows no evidence for reinforcement. Asymmetry found in female preferences may have implications for the structure of the hybrid zone. © 2013 The Linnean Society of London     

Acclimation-induced changes in cell membrane composition and influence on cryotolerance of in vitro shoots of native plant species

Cell membranes are the primary sites of cryopreservation injury and measuring changes to membrane composition arising from cold acclimation may assist with providing a rationale for optimising cryopreservation methods. Shoot tips from two south-west Western Australian species, Grevillea scapigera and Loxocarya cinerea, and Arabidopsis thaliana (reference species) were subjected to cryopreservation using the droplet vitrification protocol. Two pre-conditioning regimes involving a constant temperature (23 °C, CT with a 12 h light/dark cycle) or an alternating temperature (AT) regime (20/10 °C with a 12 h light/dark cycle) were compared. Soluble sugars, sterols and phospholipids present in the shoot tips were analysed. Use of AT pre-conditioning (acclimation) resulted in a modest decrease in cryotolerance in A. thaliana, increased cryotolerance in G. scapigera, and increased survival in the non-frozen control explants of L. cinerea in comparison to CT pre-conditioning. Increased cryotolerance was accompanied by a higher total sugar sterol and phospholipid content, as well as an increase in strong hydrating phospholipid classes such as phosphatidylcholine. The double bond index of bound fatty acyl chains of phospholipids was greater after AT pre-conditioning, mostly due to a higher amount of monoenes in A. thaliana and trienes in G. scapigera and L. cinerea. These findings suggest that AT pre-conditioning treatments for in vitro plants can have a positive influence on cryotolerance for some plant species and this may be related to observed changes in the overall composition of cell membranes. However, alternative factors (e.g. oxidative stress) may be equally important with other species (e.g. L. cinerea).     

Book review

The Oribatid Genera of the World von J. BALOGH, Verlag Akademiai Kiado, Budapest 1972. 188 S., 71 Tafeln. Preis 42.‐ DM.     

Characterization of the mouse ClC-K1/Barttin chloride channel

Several Cl⁻ channels have been described in the native renal tubule, but their correspondence with ClC-K1 and ClC-K2 channels (orthologs of human ClC-Ka and ClC-Kb), which play a major role in transcellular Cl⁻ absorption in the kidney, has yet to be established. This is partly because investigation of heterologous expression has involved rat or human ClC-K models, whereas characterization of the native renal tubule has been done in mice. Here, we investigate the electrophysiological properties of mouse ClC-K1 channels heterologously expressed in Xenopus laevis oocytes and in HEK293 cells with or without their accessory Barttin subunit. Current amplitudes and plasma membrane insertion of mouse ClC-K1 were enhanced by Barttin. External basic pH or elevated calcium stimulated currents followed the anion permeability sequence Cl⁻ > Br⁻ > NO₃⁻ > I⁻. Single-channel recordings revealed a unit conductance of ~ 40 pS. Channel activity in cell-attached patches increased with membrane depolarization (voltage for half-maximal activation: ~ − 65 mV). Insertion of the V166E mutation, which introduces a glutamate in mouse ClC-K1, which is crucial for channel gating, reduced the unit conductance to ~ 20 pS. This mutation shifted the depolarizing voltage for half-maximal channel activation to ~ + 25 mV. The unit conductance and voltage dependence of wild-type and V166E ClC-K1 were not affected by Barttin. Owing to their strikingly similar properties, we propose that the ClC-K1/Barttin complex is the molecular substrate of a chloride channel previously detected in the mouse thick ascending limb (Paulais et al., J Membr. Biol, 1990, 113:253–260).     

The curious case of Hermodice carunculata (Annelida: Amphinomidae): evidence for genetic homogeneity throughout the Atlantic Ocean and adjacent basins

Over the last few decades, advances in molecular techniques have led to the detection of strong geographic population structure and cryptic speciation in many benthic marine taxa, even those with long‐lived pelagic larval stages. Polychaete annelids, in particular, generally show a high degree of population divergence, especially in mitochondrial genes. Rarely have molecular studies confirmed the presence of ‘cosmopolitan’ species. The amphinomid polychaete Hermodice carunculata was long considered the sole species within its genus, with a reported distribution throughout the Atlantic and adjacent basins. However, recent studies have indicated morphological differences, primarily in the number of branchial filaments, between the East and West Atlantic populations; these differences were invoked to re‐instate Hermodice nigrolineata, formerly considered a junior synonym of H. carunculata. We utilized sequence data from two mitochondrial (cytochrome c oxidase subunit I, 16S rDNA) markers and one nuclear (internal transcribed spacer) marker to examine the genetic diversity of Hermodice throughout its distribution range in the Atlantic Ocean, including the Mediterranean Sea, the Caribbean Sea, the Gulf of Mexico and the Gulf of Guinea. Our analyses revealed generally low genetic divergences among collecting localities and between the East and West Atlantic, although phylogenetic trees based on mitochondrial data indicate the presence of a private lineage in the Mediterranean Sea. A re‐evaluation of the number of branchial filaments confirmed differences between East and West Atlantic populations; however, the differences were not diagnostic and did not reflect the observed genetic population structure. Rather, we suspect that the number of branchial filaments is a function of oxygen saturation in the environment. Our results do not support the distinction between H. carunculata in the West Atlantic and H. nigrolineata in the East Atlantic. Instead, they re‐affirm the older notion that H. carunculata is a cohesive species with a broad distribution across the Atlantic Ocean.     

The impact of paternity on male–infant association in a primate with low paternity certainty

In multimale groups where females mate promiscuously, male–infant associations have rarely been studied. However, recent studies have shown that males selectively support their offspring during agonistic conflicts with other juveniles and that father's presence accelerates offspring maturation. Furthermore, it was shown that males invest in unrelated infants to enhance future mating success with the infant's mother. Hence, infant care might provide fitness gain for males. Here, we investigate male–infant associations in rhesus macaques (Macaca mulatta), a primate with low paternity certainty as females mate with multiple partners and males ensure paternity less efficiently through mate‐guarding. We combined behavioural data with genetic paternity analyses of one cohort of the semi‐free‐ranging population of Cayo Santiago (Puerto Rico) and recorded affiliative and aggressive interactions between focal subjects and adult males from birth to sexual maturation (0–4 years) of focal subjects. Our results revealed that 9.6% of all interactions of focal subjects involved an adult male and 94% of all male–infant interactions were affiliative, indicating the rareness of male–infant aggression. Second and most interestingly, sires were more likely to affiliate with their offspring than nonsires with unrelated infants. This preference was independent of mother's proximity and emphasized during early infancy. Male–infant affiliation rose with infant age and was pronounced between adult males and male rather than female focal subjects. Overall, our results suggest that male–infant affiliation is also an important component in structuring primate societies and affiliation directed towards own offspring presumably represent low‐cost paternal care.