Kaplan HS et al. (2018) Neuron "Sensorimotor Integration for Decision Making: How the Worm Steers."

Zimmer M, Kaplan HS

[Neuron, 2018]

Animals' movements actively shape their perception and subsequent decision making. In this issue of Neuron, Liu etal. (2018) show how C.elegans nematodes steer toward an odorant: a dedicated interneuron class integrates oscillatory olfactory signals, generated by head swings, with corollary discharge motor signals.

Ali L et al. (2020) J Cell Biol "Mitochondrial translation, dynamics, and lysosomes combine to extend lifespan."

Ali L, Haynes CM

[J Cell Biol, 2020]

In this issue, Liu et al. (2019. J. Cell. Biol.https://doi.org/10.1083/jcb.201907067) find that the inhibition of mitochondrial ribosomes in combination with impaired mitochondrial fission or fusion increases C. elegans lifespan by activating the transcription factor HLH-30, which promotes lysosomal biogenesis.

Shtessel, Ludmila et al. (2009) International Worm Meeting "Analysis of C. elegans telomere replication mutants."

Ahmed, Shawn, Liu, Yan, Shtessel, Ludmila

[International Worm Meeting, 2009]

The ends of linear chromosomes, termed telomeres, are comprised of canonical repeat tracts that function to promote chromosome stability. RNA primers used by canonical DNA polymerases prevent complete replication of chromosome termini (Watson 1972). Due to this "end replication problem", telomeres ought to progressively shorten with every round of DNA replication. However, the ribonucleoprotein telomerase is an enzyme that combats telomere erosion by adding telomeric repeats onto 3'' telomeric ends via reverse transcription of the telomeric template sequence encoded by the telomerase RNA subunit. In order to elucidate how telomerase functions in multicellular organisms, forward genetic mutagenesis screens to identify mutations that confer progressive telomere shortening in the roundworm C. elegans were performed. Propagation of such mutants for multiple generations results in sterility and in formation of end-to-end chromosome fusions. Large-scale screens have yielded 6 mortal germline mutants with telomere replication defects, one of which corresponds to trt-1, the catalytic subunit of telomerase, as well as others that correspond to DNA damage response proteins. Mapping and characterization of several remaining telomere replication mutants will be presented.

Rahmani, Shapour et al. (2021) MicroPubl Biol

Tuck, Simon, Rahmani, Shapour

[MicroPubl Biol, 2021]

C. elegans males that have come into close proximity of hermaphrodites initiate copulatory behavior comprising at least five different steps termed response, turning, location of vulva, spicule insertion and sperm transfer (Loer and Kenyon 1993, Liu and Sternberg 1995, Chute and Srinivasan 2014). Mutations specifically affecting different steps have been isolated and characterized (Barr and Sternberg 1999, Hajdu-Cronin et al. 2017, Liu et al. 2017). However, our understanding of the molecular mechanisms acting in the neurons controlling copulation is far from complete. During the response step, males that have sensed the presence of a hermaphrodite move backwards in such a way that the males tail fan glides along the surface of the hermaphrodite until the tail reaches the vulva (or head or tail) (Loer and Kenyon 1993, Liu and Sternberg 1995, Sherlekar and Lints 2014). Response behavior is regulated by ciliated neurons in the tail whose dendrites lie in sensory rays within the fan (Liu and Sternberg 1995). If a male reaches the end of the hermaphrodite without having found the vulva, it executes a turn during which the tail bends tightly ventrally so that contact is established between the ventral surface of the fan and the other side of the intended mate (Loer and Kenyon 1993, Liu and Sternberg 1995). The ability to execute turns efficiently is dependent upon serotonergic neurons in the posterior ventral nerve cord (the CP neurons) and on their ability to produce serotonin (Loer and Kenyon 1993, Carnell et al. 2005). Serotonin stimulates the diagonal muscles in the tail to induce curling ventrally by stimulating a serotonin receptor, SER-1 (Loer and Kenyon 1993, Carnell et al. 2005). However, how serotonin affects diagonal muscles and ventral turning is not fully understood.

Kirkwood TB (2013) Cell Metab "Untangling functional declines in the locomotion of aging worms."

Kirkwood TB

[Cell Metab, 2013]

All physiological functions decline with age, but which changes are primary and which are secondary is not always clear. Liu et al. (2013), examining functional changes in the muscles and motor neurons of C. elegans, suggest that when it comes to locomotion, it is the nervous system that shows earlier age-related deterioration.

Pop, C et al. (2005) Cell "The nematode death machine in 3D."

Pop, C, Salvesen, GS

[Cell, 2005]

Regulated apoptosis is part of the development of the nematode Caenorhabditis elegans. In a recent paper in Nature, Yan et al. (2005) describe the in vitro reconstitution of the core components of the worm apoptotic pathway. Based on a structural analysis of the complex between the death activator CED-4 and the antiapoptotic protein CED-9, the authors explain the regulation of activity of CED-4. Intriguingly, CED-4 comprises a AAA+ type ATPase domain yet does not seem to need ATP hydrolysis for activity.

David S Peal et al. (2001) International C. elegans Meeting "Chemical and Genetic Inhibition of Sulfation in C. elegans"

David S Peal, Laura L Kiessling

[International C. elegans Meeting, 2001]

In order to examine the process of sulfation in C. elegans, sulfation was inhibited chemically using sodium chlorate, and genetically using the process of RNA-mediated interference (RNAi). Sodium chlorate inhibition during early larval stages resulted in a dose-dependant developmental delay. BLAST searches of characterized sulfotransferases against the worm genome resulted in the identification of 4 putative sulfotransferases: C34F6.4 and F08B4.6 (previously identified: [1] and [2]), F40H3.5, and Y34B4A.e. RNAi of the putative N-deacetylase/N-sulfotransferase F08B4.6 resulted in "stacking" of eggs in the gonad, along with eggs laid at the 2- and 4-celled stage. RNAi of the putative hexuronic 2-O sulfotransferase C34F6.4 resulted in a shortened, bulbous gonad. These initial results indicate that sulfation may be important during development of C. elegans. [1] Shworak, NW, Liu, J, Fritze, LMS, Schwartz, JJ, Zhang, L, Logeart, D, Rosenberg, RD. JBC 272: 28008-19 (1997). [2] Kobayashi, M, Sugumaran, G, Liu, J, Shworak, NW, Silbert, JE, Rosenberg, RD. JBC 274: 10474-80 (1999).

(2024) Development "The people behind the papers - Alyshia Scholl, Yihong Liu and Geraldine Seydoux."

[Development, 2024]

Germ granules have been hypothesized to deliver mRNAs of germ cell fate determinants to primordial germ cells. Now, a new study in Development finds that many mRNAs enriched in germ granules are not involved in germline development in Caenorhabditis elegans. To find out more about the story behind the paper, we caught up with first author Alyshia Scholl, second author Yihong Liu and corresponding author Geraldine Seydoux, Professor at Johns Hopkins University School of Medicine.

Gary Schindelman et al. (2002) West Coast Worm Meeting "Characterization of the sperm transfer step of male mating behavior of Caenorhabditis elegans ."

Gary Schindelman, Allyson J Whittaker, Shahla Gharib, Paul W Sternberg

[West Coast Worm Meeting, 2002]

C. elegans male mating behavior involves the proper execution of a series of sub-behaviors culminating in the transfer of sperm to the hermaphrodite (Liu, KS and Sternberg, PW. 1995. Neuron 14:79-89). These sub-behaviors are: Response to hermaphrodite, backing, turning, vulval location, spicule insertion and sperm transfer. We are analyzing the genetic control of this stereotyped behavior as it may provide insight into sensory perception and nervous system function.

Leopold, Luciana et al. (2009) International Worm Meeting "Roles for SMG-1 in NMD and DNA damage signaling."

Eckler, Matthew, Leopold, Luciana, Liu, Yan, Lowden, Mia, Ahmed, Shawn

[International Worm Meeting, 2009]

SMG-1 is a phosphatidylinositol kinase-related protein kinase that functions as a key component of the nonsense-mediated RNA decay (NMD) pathway. An allele of smg-1, yp3, was isolated from a mortal germline mutant strain that becomes progressively sterile and displays germline tumors at the non-permissive temperature of 25 deg C. However, the progressive sterility phenotype of this strain is a synthetic effect that occurs as a consequence of an additional mutation. Although outcrossed strains homozygous for smg-1(yp3), or for the null smg-1 alleles r904 and e1228, do not become progressively sterile, these strains do display a low level of germ cell tumors at 25 deg C. Mammalian SMG proteins function in both NMD as well as the S-phase DNA replication checkpoint. Treatment of C. elegans smg-1 mutants with hydroxyurea, which perturbs the S-phase checkpoint, can elicit germ cell tumors at the permissive temperature of 20 deg C, mimicking the effect of growth at 25 deg C. We present evidence that smg-1(yp3) is a separation-of-function mutation that disrupts the S-phase checkpoint, but not NMD. Thus, the DNA damage signaling function of smg-1 can suppress germ cell tumors, and the role of smg-1 in NMD is mechanistically separable from its role in DNA damage signaling.