Adenovirus Type 9 Fiber Knob Binds to the Coxsackie B Virus-Adenovirus Receptor (CAR) with Lower Affinity than Fiber Knobs of Other CAR-Binding Adenovirus Serotypes

The coxsackie B virus and adenovirus (Ad) receptor (CAR) functions as an attachment receptor for multiple Ad serotypes. Here we show that the Ad serotype 9 (Ad9) fiber knob binds to CAR with much reduced affinity compared to the binding by Ad5 and Ad12 fiber knobs as well as the knob of the long fiber of Ad41 (Ad41L). Substitution of Asp222 in Ad9 fiber knob with a lysine that is conserved in Ad5, Ad12, and Ad41L substantially improved Ad9 fiber knob binding to CAR, while the corresponding substitution in Ad5 (Lys442Asp) significantly reduced Ad5 binding. The presence of an aspartic acid residue in Ad9 therefore accounts, at least in part, for the reduced CAR binding affinity of the Ad9 fiber knob. Site-directed mutagenesis of CAR revealed that CAR residues Leu73 and Lys121 and/or Lys123 are critical contact residues, with Tyr80 and Tyr83 being peripherally involved in the binding interaction with the Ad5, Ad9, Ad12, and Ad41L fiber knobs. The overall affinities and the association and dissociation rate constants for wild-type CAR as well as Tyr80 and Tyr83 CAR mutants differed between the serotypes, indicating that their binding modes, although similar, are not identical.     

Reducing the Native Tropism of Adenovirus Vectors Requires Removal of both CAR and Integrin Interactions

The development of tissue-selective virus-based vectors requires a better understanding of the role of receptors in gene transfer in vivo, both to rid the vectors of their native tropism and to introduce new specificity. CAR and alphav integrins have been identified as the primary cell surface components that interact with adenovirus type 5 (Ad5)-based vectors during in vitro transduction. We have constructed a set of four vectors, which individually retain the wild-type cell interactions, lack CAR binding, lack alphav integrin binding, or lack both CAR and alphav integrin binding. These vectors have been used to examine the roles of CAR and alphav integrin in determining the tropism of Ad vectors in a mouse model following intrajugular or intramuscular injection. CAR was found to play a significant role in liver transduction. The absence of CAR binding alone, however, had little effect on the low level of expression from Ad in other tissues. Binding of alphav integrins appeared to have more influence than did binding of CAR in promoting the expression in these tissues and was also found to be important in liver transduction by Ad vectors. An effect of the penton base modification was a reduction in the number of vector genomes that could be detected in several tissues. In the liver, where CAR binding is important, combining defects in CAR and alphav integrin binding was essential to effectively reduce the high level of expression from Ad vectors. While there may be differences in Ad vector tropism among species, our results indicate that both CAR and alphav integrins can impact vector distribution in vivo. Disruption of both CAR and alphav integrin interactions may be critical for effectively reducing native tropism and enhancing the efficacy of specific targeting ligands in redirecting Ad vectors to target tissues.     

Temporal Persistence of Resource Polymorphism in Brook Charr, Salvelinus Fontinalis

Resource polymorphisms are believed to be an important intermediate step in competitive sympatric speciation. Reports of resource polymorphisms in fishes are becoming more common, but tests of the temporal persistence of resource polymorphisms remain scarce. We examined the temporal persistence of a body shape dimorphism reported previously for stream dwelling young-of-the-year brook charr, Salvelinus fontinalis, inhabiting slow vs. fast running water. In the year of our study, we found no difference in body shape between individuals in slow vs. fast flowing water, although fish in fast flowing water were of greater standard length than those in slower flowing water. We conclude that the resource polymorphism reported earlier for brook charr in streams is not stable temporally.     

Heteropolarity in unicellular cyanobacteria: structure and development ofCyanocystis violacea

Cyanocystis violacea isolated from a marine rock sample conforms with the diagnosis ofDermocarpa violacea Crouan in all significant characteristics. The distinct heteropolarity of the cells and simultaneous cell divisions, are stable characters in culture. Development and growth of cells, simultaneous cell division and nanocyte formation have been documented by single-cell slide cultures and fine structural studies. The reddish violet color of the cytoplasm is due to the abundance of phycoerythrin.This paper is dedicated to Prof. DrLothar Geitler, whose monumental contribution to the knowledge of blue-green algae will remain the basis for future studies on these organisms for many years to come. One of us (EIF) was fortunate enough to have had Prof.Geitler as his major professor. All of us consider Prof.Geitler our teacher.     

Postsynaptic GABABRs Inhibit L-Type Calcium Channels and Abolish Long-Term Potentiation in Hippocampal Somatostatin Interneurons

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HETEROCOCCUS ENDOLITHICUS SP. NOV. (XANTHOPHYCEAE) AND OTHER TERRESTRIAL HETEROCOCCUS SPECIES FROM ANTARCTICA: MORPHOLOGICAL CHANGES DURING LIFE HISTORY AND RESPONSE TO TEMPERATURE1

Strains of Heterococcus endolithicus sp. nov., H. pleurococcoides Pitschmann, H. caespitosus Vischer, and H. protonematoides Vischer isolated from terrestrial habitats in Antarctica were studied in culture. Morphology of the algae changes with stage in life history. The characteristic branching patterns are not present in very young or old cultures. Filament formation is suppressed when cultures are grown outside their optimal temperature range.     

Cladocerans as indicators in the importance of passive nature conservation

The aim of our study was to verify the effectiveness of passive nature conservation with regard to the preservation of species, by examining a typical mesozooplankton community. We investigated five oxbow lakes which were similar to each other in terms of size, depth and close-to-each, but which differed markedly from one to another in terms of lake management. One is under passive protection, the others are under different forms of management. Based on the NMDS (Non-metric Dimensional Scaling) analysis, we identified the variable (transparency) which is responsible for the segregation. In the case of rare species IndVal (Indicator Value) analysis was used to evaluate the occurrence and significance of indicator species. We also found marked differences in the species composition; seven species showed indicator values for the protected oxbow lake, five of which were significant (p <?0.001). In contrast, in the case of the other four oxbow lakes, a total of one species showed an indicator value. Finally, regression tree analysis was used to distinguish the oxbow lakes from each other for both common and mass-occurring species. Among the mass-occurring species, the protected oxbow lake is characterized by a large number of Acropreus harpae (Baird, 1835), while in case of the other, non-protected, oxbow lakes Alona guttata (Sars, 1862) and Alonella excisa (Fischer, 1854) are the basis for the separate classification. There is a positive effect of passive protection regarding the quantitative and qualitative occurrence of the zooplankton community. Our study highlights the importance of this kind of passive protection in the life of a particular water body and advocates that their protection should be maintained.