Endogenous expression of ASLV viral proteins in specific pathogen free chicken embryos: relevance for the developmental biology research field

Background  

The use of Specific Pathogen Free (SPF) eggs in combination with RCAS retrovirus, a member of the Avian Sarcoma-Leukosis Virus (ASLV) family, is of standard practice to study gene function and development. SPF eggs are certified free of infection by specific pathogen viruses of either exogenous or endogenous origin, including those belonging to the ASLV family. Based on this, SPF embryos are considered to be free of ASLV viral protein expression, and consequently in developmental research studies RCAS infected cells are routinely identified by immunohistochemistry against the ASLV viral proteins p19 and p27. Contrary to this generally accepted notion, observations in our laboratory suggested that certified SPF chicken embryos may endogenously express ASLV viral proteins p19 and p27. Since these observations may have significant implications for the developmental research field we further investigated this possibility.     

Toll-Like Receptor Expression and Induction of Type I and Type III Interferons in Primary Airway Epithelial Cells

Interferons (IFNs) are a critical component of the first line of antiviral defense. The activation of Toll-like receptors (TLRs) expressed by dendritic cells triggers different signaling cascades that result in the production of large amounts of IFNs. However, the functional consequences of TLR activation and differential IFN production in specific cell populations other than antigen-presenting cells have not yet been fully elucidated. In this study, we investigated TLR expression and polarization in airway epithelial cells (AECs) and the consequences of TLR agonist stimulation for the production of type I (IFN-α/β) and type III (IFN-λ) IFNs. Our results show that the pattern of expression and polarization of all TLRs in primary AEC cultures mirrors that of the human airways ex vivo and is receptor specific. The antiviral TLRs (TLR3, TLR7, and TLR9) are mostly expressed on the apical cell surfaces of epithelial cells in the human trachea and in primary polarized AECs. Type III IFN is the predominant IFN produced by the airway epithelium, and TLR3 is the only TLR that mediates IFN production by AECs, while all TLR agonists tested are capable of inducing AEC activation and interleukin-8 production. In response to influenza virus infection, AECs can produce IFN-λ in an IFNAR- and STAT1-independent manner. Our results emphasize the importance of using primary well-differentiated AECs to study TLR and antiviral responses and provide further insight into the regulation of IFN production during the antiviral response of the lung epithelium.     

Vultures acquire information on carcass location from scavenging eagles

Vultures are recognized as the scroungers of the natural world, owing to their ecological role as obligate scavengers. While it is well known that vultures use intraspecific social information as they forage, the possibility of inter-guild social information transfer and the resulting multi-species social dilemmas has not been explored. Here, we use data on arrival times at carcasses to show that such social information transfer occurs, with raptors acting as producers of information and vultures acting as scroungers of information. We develop a game-theoretic model to show that competitive asymmetry, whereby vultures dominate raptors at carcasses, predicts this evolutionary outcome. We support this theoretical prediction using empirical data from competitive interactions at carcasses. Finally, we use an individual-based model to show that these producer–scrounger dynamics lead to vultures being vulnerable to declines in raptor populations. Our results show that social information transfer can lead to important non-trophic interactions among species and highlight important potential links among social evolution, community ecology and conservation biology. With vulture populations suffering global declines, our study underscores the importance of ecosystem-based management for these endangered keystone species.     

Kinetics and mechanism of the sensitized photodegradation of lignin model compounds.

The kinetics of the sensitized photodegradation of a variety of well-defined lignin model compounds was studied to determine the mechanisms responsible for lignin's photochemically-mediated oxidation. Monomeric and dimeric models representing lignin's phenolic end groups and nonphenolic dimers representing its inner core were studied. It was determined that the rate constants for the reaction of the deprotonated phenolic models with singlet oxygen (1O2) range from 0.96 to 7.2 x 10(7) M(-1) s(-1). The models were substituted with zero, one, or two electron-donating methoxy groups on both aryl rings and, while the rate constants showed little dependence on the substitution of the nonphenolic ring, the rate constants increased dramatically with increasing methoxy substitution of the phenol. Reaction between these deprotonated models and 1O2 is thus proposed to occur at the phenolate ring. Under neutral conditions, it was observed that the phenolic models react with excited state sensitizer, with this reaction also occuring at the phenol ring. The sum of the rate constants for quenching of and reaction with excited state sensitizer by lignin model compound ranges from 5.4 to 75 x 10(7) M(-1) s(-1). This study corrects previous reports that attribute the sensitized degradation of neutral lignin model compounds to reaction with 1O2. A nonphenolic aromatic ketone inner-core model was observed to undergo direct photolysis, and its reduced analog was not degraded by direct photolysis or reaction with 1O2 or excited state sensitizer. The oxidized inner-core model was also shown to be able to act as a sensitizer for the degradation of a phenolic lignin model compound.     

Interaction between X-ray and alpha-particle damage in V79 cells

V79 cells have been exposed to X-rays or 238Pu alpha-particles or to X-rays following priming alpha-particle doses of 0.5, 2 or 2.5 Gy. The survival curve for exposure to alpha-particles was exponential with a D0 of 0.89 Gy. Following exposure to priming alpha-particle doses the resulting X-ray survival curves had the same slope as the single dose X-ray curve, but a reduced shoulder. For alpha-particle priming doses of 0.5 and 2 Gy this reduction was the same as for the same X-ray doses. 2.5 Gy alpha-particles reduced the subsequent X-ray curve Dq to almost zero. alpha-particles do cause damage capable of interacting with X-ray damage.