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.

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.

Piggott, Beverly J. et al. (2009) International Worm Meeting "Dissecting the neural basis for locomotion in freely-behaving worms."

Liu, Jie, Piggott, Beverly J., Feng, Zhaoyang, Xu, X.Z. Shawn

[International Worm Meeting, 2009]

Locomotion represents one of the most basic motor programs in the C. elegans behavioral repertoire. The command interneurons are believed to be the primary drivers of forward and backward locomotion. To better understand the role of these neurons in both sensory and spontaneous behavior, we have developed an automated calcium imaging system that permits simultaneous imaging of neural activity and behavior in freely-moving worms. We have named it the CARIBN system (CAlcium Ratiometric Imaging of Behaving Nematodes). Previous studies have been primarily conducted on restrained or semi-restrained worms that do not exhibit natural behavior. Our system provides a means to temporally examine how neural activity correlates to behavior under standard laboratory conditions where worms freely move on the surface of an NGM plate in an open environment. By using standard laboratory conditions, we can compare our work to the majority of behavioral studies performed by other groups over the past 40 years. We currently focus on the neuron AVA, as it has been implicated as a primary driver of backward locomotion in both spontaneous and sensory induced behaviors. Consistent with other reports, we found that AVA is activated in response to nose touch, osmotic shock, and in spontaneous long reversals. Surprisingly, we do not see a significant AVA activity in spontaneous short reversals. The CARIBN system provides a powerful tool to dissect how genes and neural circuits generate behavior in C. elegans.

Piggott, Beverly J. et al. (2011) International Worm Meeting "Mammalian rhodopsin can functionally substitute for C. elegans photoreceptor to restore light sensitivity in worms."

Piggott, Beverly J., Liu, Jie, Xu, X.Z. Shawn, Gao, Jingwei

[International Worm Meeting, 2011]

We have recently discovered that worms sense light and engage in phototaxis behavior that is essential to their survival. Our work has led to the identification of photoreceptor neurons and molecules in the C. elegans phototransduction pathway. Through electrophysiological interrogation, we discovered that LITE-1 acts in ASJ to transduce light signals through a G protein-mediated process which requires membrane-associated guanylate cyclases. This pathway shares striking similarities to those found in some vertebrate photoreceptor cells. Interestingly, lite-1 belongs to the invertebrate taste receptor family. Discovering that a gustatory receptor could permit light sensation in worms, we wondered if expression of other known light sensing molecules, such as opsins, could function similarly in worms. In other words, could structurally distinct, mammalian opsins, hijack the C. elegans phototransduction machinery to restore photosensory behavior in lite-1 mutants? To this end we made transgenic worms expressing bovine rhodopsin and discovered that it can restore light sensitivity in lite-1 mutants. These findings demonstrate that divergent photoreceptor molecules can share functional homology.

Ward, Alex et al. (2009) International Worm Meeting "Eyeless but not blind: Phototransduction in C. elegans."

Liu, Jie, Kang, Lijun, Decaluwe, Brandon, Gao, Jingwei, Xie, Zhixiong, Ma, Di, Ward, Alex, Yu, Yong, Inada, Hitoshi, Mori, Ikue, Xu, X.Z. Shawn, Nishio, Nana

[International Worm Meeting, 2009]

It has long been assumed that the nematode C. elegans lacks the sense of light, mainly because it lives in the soil and does not have eyes. However, we have recently reported the surprising observation that C. elegans in fact possesses a simple visual system and engages in phototaxis behavior that is mediated by photoreceptor cells and light-sensitive channels [1]. Here we elucidate the phototransduction cascade in C. elegans photoreceptor cells through a combination of electrophysiological and behavioral analysis. As is the case with vertebrate photoreceptor cell rods and cones, C. elegans phototransduction is also mediated by G signaling and cGMP-sensitive CNG channels. Interestingly, instead of signaling through phosphodiesterases (PDEs), light-activated G proteins appear to be coupled to guanylate cyclases that produce cGMP, thereby resulting in opening of CNG channels. Our studies identify a new sensory modality in C. elegans and suggest that animals living in dark environments (e.g. soil and caves) may not be presumed to be blind. Our data also reveal a surprising conservation in phototransduction between vertebrates and C. elegans, indicating that C. elegans represents a powerful genetic model for the study of phototransduction. [1] Ward, A.*, Liu, J.*, Feng, Z., and Xu, X.Z.S. (2008) Light-sensitive neurons and channels mediate phototaxis in C. elegans. Nature Neuroscience 11, 916-22 *co-first authors.

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.