Neue linguistische Methoden und arbeitstechnische Verfahren in der Erschliessung der ägyptischen Grammatik

15 páginas, 1 tabla, 6 figuras.Does diversity beget diversity? Diversity includes a diversity of concepts because it is linked to variability in and of life and can be applied to multiple levels. The connections between multiple levels of diversity are poorly understood. Here, we investigated the relationships between genetic, bacterial, and chemical diversity of the endangered Atlanto-Mediterranean sponge Spongia lamella. These levels of diversity are intrinsically related to sponge evolution and could have strong conservation implications. We used microsatellite markers, denaturing gel gradient electrophoresis and quantitative polymerase chain reaction, and high performance liquid chromatography to quantify genetic, bacterial, and chemical diversity of nine sponge populations. We then used correlations to test whether these diversity levels covaried. We found that sponge populations differed significantly in genetic, bacterial, and chemical diversity. We also found a strong geographic pattern of increasing genetic, bacterial, and chemical dissimilarity with increasing geographic distance between populations. However, we failed to detect significant correlations between the three levels of diversity investigated in our study. Our results suggest that diversity fails to beget diversity within a single species and indicates that a diversity of factors regulates a diversity of diversities, which highlights the complex nature of the mechanisms behind diversityResearch funded by grants from the Agence Nationale de la Recherche (ECIMAR), from the Spanish Ministry of Science and Technology SOLID (CTM2010-17755) and Benthomics (CTM2010-22218-C02-01) and the BIOCAPITAL project (MRTN-CT-2004-512301) of the European Union. This is a contribution of the Consolidated Research Group ‘‘Grupo de Ecologı´a Bento´nica,’’ SGR2009-655.Peer reviewe

Modulation of β-Catenin Signaling by Glucagon Receptor Activation

The glucagon receptor (GCGR) is a member of the class B G protein–coupled receptor family. Activation of GCGR by glucagon leads to increased glucose production by the liver. Thus, glucagon is a key component of glucose homeostasis by counteracting the effect of insulin. In this report, we found that in addition to activation of the classic cAMP/protein kinase A (PKA) pathway, activation of GCGR also induced β-catenin stabilization and activated β-catenin–mediated transcription. Activation of β-catenin signaling was PKA-dependent, consistent with previous reports on the parathyroid hormone receptor type 1 (PTH1R) and glucagon-like peptide 1 (GLP-1R) receptors. Since low-density-lipoprotein receptor–related protein 5 (Lrp5) is an essential co-receptor required for Wnt protein mediated β-catenin signaling, we examined the role of Lrp5 in glucagon-induced β-catenin signaling. Cotransfection with Lrp5 enhanced the glucagon-induced β-catenin stabilization and TCF promoter–mediated transcription. Inhibiting Lrp5/6 function using Dickkopf-1(DKK1) or by expression of the Lrp5 extracellular domain blocked glucagon-induced β-catenin signaling. Furthermore, we showed that Lrp5 physically interacted with GCGR by immunoprecipitation and bioluminescence resonance energy transfer assays. Together, these results reveal an unexpected crosstalk between glucagon and β-catenin signaling, and may help to explain the metabolic phenotypes of Lrp5/6 mutations

Metagenomic discovery of polybrominated diphenyl ether biosynthesis by marine sponges

Naturally produced polybrominated diphenyl ethers (PBDEs) pervade the marine environment and structurally resemble toxic man-made brominated flame retardants. PBDEs bioaccumulate in marine animals and are likely transferred to the human food chain. However, the biogenic basis for PBDE production in one of their most prolific sources, marine sponges of the order Dysideidae, remains unidentified. Here, we report the discovery of PBDE biosynthetic gene clusters within sponge-microbiome-associated cyanobacterial endosymbionts through the use of an unbiased metagenome-mining approach. Using expression of PBDE biosynthetic genes in heterologous cyanobacterial hosts, we correlate the structural diversity of naturally produced PBDEs to modifications within PBDE biosynthetic gene clusters in multiple sponge holobionts. Our results establish the genetic and molecular foundation for the production of PBDEs in one of the most abundant natural sources of these molecules, further setting the stage for a metagenomic-based inventory of other PBDE sources in the marine environment

Abundance and bioactivity of cultured sponge-associated bacteria from the Mediterranean Sea

In this study, the search for new antibiotics was combined with quantitative ecological studies. The cultured fraction of the associated bacterial communities from ten different Mediterranean sponge species was investigated. To obtain quantitative and qualitative data of sponge-associated bacterial communities and to expand the cultured diversity, different media were used. The largest morphological diversity and highest yield of isolates was obtained by using oligotrophic media, which consisted of natural habitat seawater amended with (1% additional carbon sources. The dominant bacterial morphotypes were determined and bacterial isolates were tested for antimicrobial activity and identified using 16S rDNA sequencing. The sponge-associated most abundant morphotypes were all affiliated to the Alphaproteobacteria and showed antimicrobial activity against at least one of the tested strains. In contrast, the ambient seawater was dominated by Gammaproteobacteria. One single alphaproteobacterium, which was related to Pseudovibrio denitrificans, was shown to dominate the cultured community of at least six of the sponges. This designated MBIC3368-like alphaproteobacterium has been isolated from sponges before and seems to be restricted to associations with members of the phylum Porifera. It displays a weak and unstable antimicrobial activity, which gets easily lost during cultivation. However, this bioactive bacterium was present in the sponges by up to 106 cells per gram wet-weight sponge tissue and dominated the cultured fraction with up to 74%. The association of this alphaproteobacterium with sponges is probably evolutionary young and facultative and possibly involves biologically active secondary metabolites. Besides a demonstrated vertical transfer, additional horizontal transfer between the sponges is assumed. Members of the genus Bacillus displaying antimicrobial activity were found regularly, too. However, actinomycetes, which are known for their production of bioactive substances, were present in very low abundance