Abstracts - Deutsche Zoologische Gesellschaft

Physiology Posters 189P PH.5 - ENDifferential gene expression in the tardigrade Milnesium tardigradum duringanhydrobiosisMarkus Grohme 1 , Brahim Mali 1 , Martina Schnölzer 2 , Thomas Dandekar 3 , Dirk Reuter 4 , RalphSchill 5 , Marcus Frohme 11University of Applied Sciences Wildau; 2 German Cancer Research Center, Heidelberg 3 Universityof Würzburg; 4 Oncoscience AG; 5 University of StuttgartIn a functional genomics approach utilizing subtractive techniques and microarrays we are exploringdifferential gene expression in the tardigrade Milnesium tardigradum during anhydrobiosis. Expressedsequence tags (ESTs) are being bioinformatically analysed to identify stress response genesbut also to elucidate potential anhydrobiotic regulatory pathways. Regulated transcripts betweendifferent stages that might play a role in cryptobiotic survival are being identified using cDNArepresentational difference analysis (cDNA-RDA). RDA, like other PCR based subtractive methodsdoes not rely on prior sequence knowledge and can therefore be applied in parallel while sequencedatabases are being established. Furthermore we will perform microarray experiments and complementthem with RDA-derived probe-sequences to identify additional candidate genes. Followingtheir discovery some years ago it has been shown that microRNAs (miRNA) play an importantregulatory role in many physiological and developmental processes. Therefore we attempt to clonetardigrade specific miRNAs to test whether gene expression is regulated by this type of noncodingRNAs during anhydrobiosis. Resulting data from RDA, microarrays and miRNAs together will helpto gain deeper insight into differential gene expression during anhydrobiosis. Establishing this tardigradespecies as a cryptobiotic model organism will help to develop new ways of preserving variousbiological samples from degradation.P PH.6 - ENEvidence of the epithelial sodium channel delta subunit in human nasal epitheliumNadine Bangel-Ruland, Kristina Kusche-Vihrog, Hanna Langhorst, Dominik Kentrup, Wolf-Michael WeberInstitute of Animal Physiology, University of MünsterThe epithelial sodium channel (ENaC) mediates the first step in Na + reabsorption in epithelial cellssuch as kidney, lung, and colon and may consist of four homologous subunits (α, β, γ, δ). Predominantly,the α-subunit is expressed in these epithelia and it usually forms functional channels with theβ- and γ-subunit. The δ-subunit was first found in human brain and kidney but the expression wasalso detected in human cell lines of lung, pancreatic and colonic origin. When co-expressed with βand γ accessory subunits in heterologous systems the two known isoforms of the δ-ENaC subunit(δ1 and δ2) can build amiloride-sensitive Na + channels. In the present study we investigated the expressionof the δ-subunit in human nasal epithelium. We cloned and sequenced the full-length cDNAof the ENaC δ-subunit and showed that in nasal tissue at least isoform 1 is expressed. Furthermore,we carried out Western blot and immunofluorescence analyses to study the expression of the δ-ENaC in human nasal epithelium. Additionally, we showed a functional expression of the δ-ENaCsubunit with measurements in modified Ussing chambers. Thereby, we demonstrated that Evansblue, a δ-subunit-specific antagonist, inhibits the activity of δ-ENaC in human nasal epithelium.These findings raise the question if the δ-subunit possesses important regulatory function and if itinteracts with other ENaC subunits or members of the DEG/ ENaC family in the human respiratoryepithelium.