Petersen, Carola et al. (2019) International Worm Meeting "Preconditioning with natural microbiota bacteria can directly influence C. elegans behavior."

Petersen, Carola, Pees, Barbara, Leippe, Matthias

[International Worm Meeting, 2019]

In nature C. elegans is often found in microbe-rich decomposing plant material. It is well established that C. elegans is able to recognize food bacteria and to distinguish between beneficial and harmful bacteria. However, while C. elegans behavior has mainly been studied in the context of foraging and pathogen avoidance, the influence of the C. elegans natural microbiota on behavior has not been examined. Here, we assessed choice behavior of 11 natural C. elegans isolates and the N2 strain towards 4 natural microbiota bacteria and E. coli OP50. We found that the natural C. elegans isolate MY2079 changed its choice behavior towards the microbiota bacterium Ochrobactrum sp. MYb71 over time: C. elegans MY2079 chose MYb71 in equal quantities compared to the other offered bacteria after 2 h, but avoided MYb71 after 24 h. No such difference was found for N2. We could exclude that the change in MY2079 behavior was due to differences in bacterial density or due to the other offered bacteria. However, preconditioning of MY2079 with MYb71 caused fast avoidance (2 h) of MYb71 indicating that microbiota bacteria can directly influence C. elegans behavior. Whether this influence depends on colonization of the C. elegans intestine by the microbiota bacterium remains to be tested.

Kademci, Aylin et al. (2010) C. elegans: Development and Gene Expression, EMBL, Heidelberg, Germany "Role of a selected caenopore in the defence of Caenorhabditis elegans"

Leippe, Matthias, Kademci, Aylin, Stanisak, Mareike

[C. elegans: Development and Gene Expression, EMBL, Heidelberg, Germany, 2010]

Caenopores are antimicrobial and pore-forming peptides, which are needed by C. elegans to cope with bacteria. One member of the multifarious caenopore family, Caenopore-12 (SPP-12), is of special interest in this study. We purified recombinant SPP-12 and found that it is antimicrobially active against gram-positive bacteria and yeast, but not against gram-negative bacteria and that it has pore-forming activity. We also showed that spp-12 is exclusively expressed in two pharyngeal neurons and that the spp-12 mutant is more susceptible to infection with the intestinal pathogen Bacillus thuringiensis . However, on relatively non-pathogenic E. coli OP50 the spp-12 mutant has a longer lifespan than the wild-type. This result suggests that Caenopore-12 is important for the defence of C. elegans against B. thuringiensis , whereas in the absence of a pathogen it has detrimental effects.

Pees, Barbara et al. (2019) International Worm Meeting "Role of antimicrobial proteins in shaping Caenorhabditis elegans microbial associations."

Petersen, Carola, Treitz, Christian, Tholey, Andreas, Leippe, Matthias, Pees, Barbara

[International Worm Meeting, 2019]

The identification of the native C. elegans microbiota and interacting host factors has only recently begun despite of the worm's microbe-rich natural habitat and its bacteriovorus lifestyle. Several protein families have been identified to be involved in digestion of food bacteria and in immune defenses against pathogenic bacteria. Yet, the interaction of host factors with microbiota bacteria has not been evaluated. Hence, we aim at characterizing the role of antimicrobial proteins (AMPs) in shaping microbial associations with C. elegans. Comparative proteome analyses revealed that two families of AMPs, lysozymes (ILYS, LYS) and caenopores (SPP), were differently abundant in worms exposed to microbiota bacteria. Members of both protein families have previously been demonstrated to compromise bacterial cells walls. The expression of selected AMP encoding genes was primarily localized to the intestine of C. elegans as reporter strains could show. Further, in ilys knock-out mutants exposure to microbiota bacteria resulted in an increased bacterial colonization and also changes in fertility. We are currently trying to knock-out whole gene clusters of both, caenopore and lysozyme genes, to understand the role of these clusters on microbiota bacteria in vivo. Additionally, we are characterizing recombinantly expressed ILYS and SPP proteins regarding their potential interaction with microbiota bacteria in vitro. Our results may provide a first insight into the function of AMPs shaping microbial associations of bacteriovorus C. elegans.

Bjoern Biedermann et al. (2006) European Worm Meeting "Germline Totipotency and the worm teratoma"

Bjoern Biedermann, Rafal Ciosk, Mathias Senften

[European Worm Meeting, 2006]

Bjoern Biedermann, Matthias Senften and Rafal Ciosk. Teratomas (derived from teraton, the Greek word for monster) are germ cell tumors that contain a mixture of somatic tissue such as hair or bone. These tumors are thought to result from abnormal somatic differentiation of germ cells, but very little is known about the molecular mechanisms that normally maintain germ cell totipotency. Two conserved translational repressors, MEX-3 and GLD-1, have been recently found to maintain totipotency in the C. elegans germline (Ciosk et al., Science 311, 851, 2006). In mex-3 gld-1 mutants, germ cells transdifferentiate into various somatic cell types such as muscles or neurons. This worm teratoma requires the entry into meiosis and coincides with the disappearance of germline-specific P granules. To understand MEX-3/GLD-1 role in maintaining totipotency, we want to identify the proteins that normally need to be repressed by MEX-3 and GLD-1. Genetic and biochemical strategies will be discussed at the meeting.

Martin Gutternigg et al. (2006) European Worm Meeting "Glycosidases of Caenorhabditis elegans involved in N-glycan processing"

Martin Gutternigg, Matthias Hackl, Ute Stemmer, Iain B. H. Wilson, Petra Geier, Gunter Lochnit, Ramona Ranftl, Katharina Paschinger, Verena Jantsch, Dorothea Lubich

[European Worm Meeting, 2006]

Martin Gutternigg, Dorothea Lubich, Matthias Hackl, Katharina Paschinger, Ute Stemmer, Verena Jantsch1, Gnter Lochnit2, Ramona Ranftl, Petra Geier and Iain B. H. Wilson. Recent data indicates that in addition to the Golgi ?-mannosidases, the model nematode Caenorhabditis elegans also possesses, like insects, an N-acetylhexosaminidase activity putatively involved in N-glycan processing in the Golgi. The presence of such an activity is invoked, not just on the basis of the detected enzyme activity, but also to explain the absence of terminal N-acetylglucosamine residues on structures which require the prior action of N-acetylglucosaminyltransferase I during their biosynthesis. In order to understand the genetic basis for these activities, we have cloned cDNAs encoding members of both glycohydrolase families 20 and 38 from the worm. The encoded glycosidases were expressed in the yeast Pichia pastoris as soluble forms lacking putative cytoplasmic and transmembrane domains. Four glycohydrolase family 20 members were shown to cleave p-nitrophenyl-?-N-acetylglucosaminide and/or p-nitrophenyl-?-N-acetylgalactosaminide, but showed contrasting specificities with regard to N-glycan substrates. On the other hand, one glycohydrolase family 38 member was shown to be active using p-nitrophenyl-?-mannoside as a substrate and, in addition, had mannosidase II activity. Analysis of the glycans of the relevant mutant showed large-scale changes in the N-glycosylation spectrum. These, therefore, are the first data on the activity of Caenorhabditis glycosidases towards N-glycan substrates and should aid the further elucidation of N-glycan processing in this organism.