Polyketides can selleck compound also be extracted from different algae, dinoflagellates and plants (Hopwood & Sherman, 1990; Austin & Noel, 2003), for which those compounds apparently serve as defensive substances against natural enemies (Manojlovic et al., 2000; Choi et al., 2004).

The probably most diverse group of polyketide producers are marine organisms like sponges, tunicates, and bryozoans. Such animals are a source of natural compounds with strong cytotoxic properties that are extremely interesting from a medical point of view (Piel, 2004, 2006; Moore, 2005, 2006; Piel et al., 2005). These substances belong to the pederin family, which currently comprises 36 members from eight different invertebrate animal genera (Narquizian & Kocienski, 2000; Simpson et al., 2000; Vuong et al., 2001; Paul et al., 2002). MLN0128 solubility dmso Polyketides are produced by hitherto uncultured, highly adapted bacterial endosymbionts. Cultivation of the pederin-producing bacterial endosymbionts of female Paederus rove beetles is not yet possible, and although chemical synthesis of pederin has been successfully reported by some groups

(Matsuda et al., 1988; Kocienski et al., 2000; Takemura et al., 2002; Jewett & Rawal, 2007), its low availability represents a serious impediment to drug development (Munro et al., 1999; Piel, 2002, 2004, 2006). Thus, tools are required for custom tailoring growth media for the enrichment and isolation of Paederus endosymbionts. Kellner (1999, 2001a, b, 2002a) demonstrated that a Pseudomonas-like endosymbiont is associated with the transfer of pederin production capabilities to the female progeny of Paederus beetles via endosymbiont-harbouring eggs. Analysis of metagenomic DNA from Paederus fuscipes beetles revealed the existence of a mixed modular polyketide synthase (pks)-gene cluster that is responsible for pederin biosynthesis (Piel, 2002). Specific PCR primers were designed from conserved regions of single cluster modules and utilized for the amplification of pks-gene fragments from endosymbionts in beetle or egg specimens (Piel, 2002).

However, direct evidence for the localization of Pseudomonas-like endosymbionts on eggs is lacking, and it is still unresolved, where such endosymbionts are located within Paederus beetles. FISH is an appropriate tool Farnesyltransferase for the in situ localization of specific phylogenetically defined groups of bacteria (Amann et al., 2001; Amann & Fuchs, 2008). Thus, the objectives were to (1) design and evaluate a specific 16S rRNA gene-targeted oligonucleotide probe for Pseudomonas-like Paederus riparius endosymbiont detection; (2) localize endosymbionts within serial egg thin-sections by FISH; and (3) determine where within the host symbionts are transferred to eggs by surface comparison of different egg stadiums using electron microscopy and pks-targeted PCR.