Eberhard, Ralf et al. (2009) International Worm Meeting "How is RNA Pol I involved in DNA damage responses in C. elegans?"

Eberhard, Ralf, Hengartner, Michael, Stergiou, Lilli, Hofmann, Randal

[International Worm Meeting, 2009]

Eukaryotic organisms preserve the integrity of their genome by exhibiting a properly regulated response when DNA is damaged. Failure of DNA lesions to be restored can lead to mutations or large-scale genomic instability, which may implicate tumorigenic potential. The germline tissue of C. elegans is a versatile model to dissect the signaling network that links damage inflicted by chemical or physical agents to cellular key responses; DNA repair, cell cycle arrest, cell death, and - as an integrated output - embryonic survival, can be studied in the context of a living organism. We performed a forward genetic screen for new mutant worm strains that are defective for cellular responses to treatment with UV-light or ionizing radiation. Based on the findings in one mutant, RNA polymerase I appears to be involved in the regulation of DNA-damage induced germ cell apoptosis. It is the topic of our current research to elucidate whether the defective response we observe in this mutant is due to a specific role of the affected RNA Pol I subunit in apoptosis, or whether it results from a more general implication on transcription of ribosomal RNA and on the synthesis of ribosomes. Positioning this novel aspect in relation to known signaling factors, in particular to cep-1, the C. elegans homolog of p53, might extend our genetic model of DNA damage-induced apoptosis by another branch. The elemental transcription apparatus as well as most damage response mechanisms are highly conserved in evolution, which should allow to extrapolate many of our observations and working models to higher organisms including humans.

Sommer RJ et al. (1994) Worm Breeder's Gazette "Evolution of Vulva-Formation: Part II: Species With a Central Vulva"

Sommer RJ, Sternberg PW

[Worm Breeder's Gazette, 1994]

Evolution of vulva-formation: Part II: Species with a central vulva Ralf J. Sommer & Paul W. Sternberg, California Institute of Technology, Division of Biology 156-29, Pasadena, CA 91125

Sommer RJ et al. (1994) Worm Breeder's Gazette "Evolution of Vulva Formation: Part IV: Variation in AC Position Can Cause a Shift of Vulva Formation Towards P(4-6).p."

Sternberg PW, Sommer RJ

[Worm Breeder's Gazette, 1994]

Evolution of vulva formation: Part IV: Variation in AC position can cause a shift of vulva formation towards p(4- 6).p Ralf J. Sommer & Paul W. Sternberg, HHMI & California Institute of Technology, Division of Biology 156-29, Pasadena, CA

Bird, David (2015) International Worm Meeting "A model for feeding-site formation by root-knot nematode."

Bird, David

[International Worm Meeting, 2015]

Root-knot nematode (RKN: Meloidogyne spp.) is an obligate parasite of land plants and causes severe yield reduction in crops world-wide. Characteristic of the parasitic interaction is the induction of a permanent feeding site, composed of several Giant Cells (GC) surrounded by a gall. Interrogation of the M. hapla genome revealed that the nematode encodes replicas of plant peptide hormone families, including 12 CEP, 8 CLE, IDA, RALF, and RGF. In planta, peptide hormones work as powerful developmental and physiological regulators at the cell-to-cell level and as plant-wide signals. These hormones are not found in other animals. Thus, by encoding a full gamut of these peptides, which I term "xenomones," RKN is unique.Based on the assumption that the role played by the M. hapla xenomones will recapitulate that of the cognate, indigenous plant-peptide hormones, I propose a model of infection by RKN. Central is the sequential release of specific xenomones by the nematode to facilitate/execute the necessary plant response:1) Mechanical penetration of root by L2 dauer;2) intercellular migration: secretion of IDA xenomone3) cytokinin release by L2 to initiate development of root stem cells4) induction of cell expansion: secretion of RALF xenomone5) suppression of cytokinesis: secretion of CEP xenomone6) suppression of differentiation: secretion of CLE xenomoneTo establish the relationship of M. hapla xenomones with their receptor(s), we have solved the structure of 8 xenomones to atomic resolution, and modeled their docking onto the 380 predicted Arabidopsis trans-membrane receptors. These docking experiments are double blinded and reveal distinct classes of receptor::ligand relationships.

Berger, Simon et al. (2015) International Worm Meeting "Microfluidic C. elegans immobilization, enabling long-term studies of germline development at a single-cell resolution."

deMello, Andrew, Casadevall i Solvas, Xavier, Berger, Simon, Aegerter-Wilmsen, Tinri, Hengartner, Michael, Eberhard, Ralf, Stavrakis, Stavros, Hajnal, Alex

[International Worm Meeting, 2015]

The germline of C. elegans has extensively been used to study cell proliferation, differentiation, and death. Even though many such studies can be carried out by simply acquiring steady state images of the animals, some require tracing of individual germ cells for extended periods of time. Thus far, it has been challenging to immobilize adult worms and, at the same time, maintain the conditions required for adequate physiological germline function. Germline health soon declines in animals padded on slides, which has significantly limited germline-related developmental studies.In this study we demonstrate a microfluidic platform for the long-term immobilization of adult C. elegans and its application for the imaging of mitotic and apoptotic germ cells at the single cell level. The immobilization platform allows for the efficient trapping, feeding, and imaging of a single worm over an extended period of time, while not disturbing the physiologically essential and sensitive process of egg-laying. The performance of the platform was validated by bright field microscopy, displaying good immobilization and survival of the worms for up to 150 hours and egg production for up to 60 hours. Fluorescence imaging further showed that fertilization occurs normally and germline health is not affected negatively even over extended periods of time. Subsequently the newly developed microfluidic platform was used to monitor the propagation and development of individual germ cells along the gonad. In the future information gained about cell size and state of the nucleus will be used to determine mitotic and apoptotic cells and reconstruct their development in time.

Juan Cabello et al. (2006) European Worm Meeting "The Wnt Pathway Controls Engulfment Of Apoptotic Corpses, Spindle Orientation And Migration Through CED-10/Rac"

Juan Cabello, Ralf Schnabel, Ufuk Gunesdogan

[European Worm Meeting, 2006]

Juan Cabello, Ufuk Gunesdogan and Ralf Schnabel. The recognition and engulfment of apoptotic cell corpses is achieved by at least two parallel pathways in C. elegans. These are defined by the proteins CED-1/SREC, CED-6/GULP, CED-7/ABCA1 and CED-2/CrkII, CED-5/Dock180, CED-12/ELMO. The pathways merge at CED-10, which codes for a Rac small GTPase. CED-1 is a scavenger receptor for the recognition of cell corpses in the first pathway. However, the receptor which regulates the second pathway has long remained elusive. Here we show that the receptor MOM-5, a Frizzled homolog of the Wnt pathway in C. elegans, functions upstream of the second pathway not only in engulfment but also in spindle orientation and gonadal migration. Therefore, in different developmental processes, CED-10/Rac links polar signals mediated by the Wnt pathway to the modulation of the cytoskeleton.

Schnabel H et al. (1994) Worm Breeder's Gazette "New Deficiencies on LGIII."

Schnabel R, Schnabel H

[Worm Breeder's Gazette, 1994]

New deficiencies on LGIII Heinke Schnabel and Ralf Schnabel, Max-Planck-lnstitut fur Biochemie, D-82152 Martinsried, Fed. Rep. of Germany In an attempt to generate new deficiencies on LGIII (which we need to analyze the maternal-effect lethals that we have generated) we mutagenized unc-32(e189)/qC1 worms with 7500R. A total of 5186 F1 animals were picked to single plates and their progeny analyzed for the absence of Unc worms, indicating a lethal mutation linked to unc-32. 904 had to be discarded for various reasons, 923 were sterile or produced only dead eggs. Of the remaining 3359, 21 stable lethals linked to unc-32 were obtained after outcrossing. These lethals were then testcrossed with several markers in order to find putative deficiencies. In this manner, we obtained 4 deficiencies which in addition to being lethal fail to complement mutations in the following genes: deletes tDf5 tDf6 and tDf8 tDf7 dpy- 18, spe-6, bli-5, unc-64 unc-25, unc-71, unc-64, b li- 5 dpy- 18, spe-6 complements vab-7, tra-1 dpy-18, spe-6 bli-5, unc-25, vab- 7 There are three other lethals that each fail to complement mutations in a single gene: dpy-1, dpy-18, or bli-5. These may well be double mutations rather than deficiencies. All of the above will be available from the CGC soon. We thank Michaela Berr for excellent technical assistance.

James P McCarter et al. (2001) International C. elegans Meeting "Genes from Other"

Michael Dante, James P McCarter, John C Martin, Deana Pape, Brandi Chiapelli, Todd N Wylie, Robert H Waterston, Sandra W Clifton

[International C. elegans Meeting, 2001]

To build upon knowledge gained from the genome of C. elegans , we have begun generating Expressed Sequence Tags (ESTs) from parasitic (and free-living) nematodes. This project will generate >225,000 5' ESTs from 14 species by 2003. Additionally, the Sanger Centre and Edinburgh Univ. will complete 80,000 ESTs from 7 species. Through these combined efforts, we anticipate the identification of >80,000 new nematode genes. At the GSC, approximately 35,000 ESTs have been generated to date including sequences from Ancylostoma caninum, Heterodera glycines, Meloidogyne incognita and javanica, Parastrongyloides trichosuri, Pristionchus pacificus, Strongyloides stercoralis and ratti, Trichinella spiralis, and Zeldia punctata . We will report on our progress in sequence analysis, including the creation of the NemaGene gene index for each species by EST clustering and consensus sequence generation, identification of common and rare transcripts, and identification of genes with orthologues in C. elegans and other nematodes. All sequences are publicly available at www.ncbi.nlm.nih.gov/dbEST. NemaGene sequences and project details are available at WWW.NEMATODE.NET. We would like to thank collaborators who have provided materials and ideas for this project including Prema Arasu, David Bird, Rick Davis, Warwick Grant, John Hawdon, Doug Jasmer, Andrew Kloek, Thomas Nutman, Charlie Opperman, Alan Scott, Ralf Sommer, and Mark Viney. This work is funded by NIH-AI-46593, NSF-0077503, and a Merck / Helen Hay Whitney Foundation fellowship.

Jagan Srinivasan et al. (2002) Worm Breeder's Gazette "Towards a Pristionchus genome map II - Microevolutionary analysis of the nematode genus Pristionchus"

Ralf J Sommer, Min Zheng, Isabel Kipping, Arturo Gutierrez, Andre Pires da Silva, Hanh Witte, Jagan Srinivasan

[Worm Breeder's Gazette, 2002]

We describe the molecular characterization of laboratory strains of the nematode genus Pristionchus , which lays a foundation for microevolutionary analyses of vulva development. We isolated 13 laboratory strains of the Pristionchus genus that are derived from natural isolates from around the world. Mating experiments and ITS sequence analysis indicated that these 13 strains represent four different species; the gonochoristic species P. lheritieri and three hermaphroditic species, P. pacificus , P. maupasi and an as yet undescribed species Pristionchus sp., respectively. P. pacificus is represented by five different strains isolated from California, Washington, Hawaii, Ontario and Poland. Our working 'wild type' strain is the California strain. Since polymorphisms are becoming an important tool in modern day genomic analysis, which facilitate cloning of mutations, we decided to search for polymorphisms in the various Pristionchus pacificus strains. We performed amplified restriction fragment length polymorphism (AFLP) analyses of the different P. pacificus strains and found that the American strains are highly polymorphic (Srinivasan et al., 2001). We observed the largest genetic variation between the strain from California on the one hand and Washington and Hawaii on the other hand. In contrast, the developmentally distinct strain from Poland is identical to the Californian strain. Hence, we chose the Washington strain as our polymorphic strain for future experiments. These results provide us a framework for further studies on microevolution in developmental processes. Reference: Srinivasan, J., Pires-daSilva, A.; Gutierrez, A.; Jungblut, B.; Zheng, M.; Witte, H.; Schlak., I. & Ralf J. Sommer, Evolution & Development (2001) 3 : 229-240.

Domeier ME et al. (1997) International C. elegans Meeting "EXPRESSION OF pha-1 DURING EMBRYOGENESIS"

Domeier ME, Mango SE

[International C. elegans Meeting, 1997]

At about the 200 cell stage of embryogenesis, 27 precursors are born that will ultimately produce the 80 cells of the pharynx. Initial studies using a pha-1::lacZ construct determined that pha-1 was expressed at the 200 cell stage, in pharynx and body wall muscle precursors1. To visualize the pharyngeal precursors in living embryos, we created two pha-1::GFP constructs. The first construct was a translational fusion that contained 3.7 kb of upstream sequences plus the entire pha-1 coding domain fused to GFP. The second was a transcriptional fusion carrying pha-1 5! sequences and a nuclear-localized GFP::lacZ cassette. GFP expression was assayed from stable lines in N2 embryos. Surprisingly, both GFP constructs were expressed in multiple cell types in addition to pharynx and body wall muscle precursors. For example, hypodermis, neurons and intestinal cells all expressed pha-1::GFP. Thus, pha-1 may be expressed more globally than first reported. Furthermore, the pha-1::GFP protein fusion was found predominantly in the cytoplasm. This construct was able to rescue pha-1 mutants, suggesting that endogenous PHA-1 may be a cytoplasmic protein as well. To determine the expression pattern of endogenous PHA-1, we are making anti-PHA-1 antibodies. 1.Granato M., Schnabel H. and Schnabel R. (1994) Development 120, 3005-3017. We thank Heinke and Ralf Schnabel for generously sending us alleles of pha-1 as well as pha-1 expression constructs.