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.

Liu J et al. (1996) Science "Interaction between a putative mechanosensory membrane channel and a collagen."

Schrank B, Waterston RH, Liu J

[Science, 1996]

The degenerin family of proteins in Caenorhabditis elegans is homologous to subunits of the mammalian amiloride-sensitive epithelial sodium channels. Mutations in nematode degenerins cause cell death, probably because of defects in channel function. Genetic evidence was obtained that the unc-105 gene product represents a degenerin homolog affecting C. elegans muscles and that this putative channel interacts with type IV collagen in the extracellular matrix underlying the muscle cell. This interaction may serve as a mechanism of stretch-activated muscle contraction, and this system could provide a molecular model for the activation of mechanosensitive ion channels.AD - Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA.FAU - Liu, JAU - Liu JFAU - Schrank, BAU - Schrank BFAU - Waterston, R HAU - Waterston RHLA - engSI - GENBANK/J04694SI - GENBANK/M23704SI - GENBANK/M67507SI - GENBANK/U07224SI - GENBANK/U07888SI - GENBANK/U22327SI - GENBANK/X56979SI - GENBANK/X76730SI - GENBANK/Y00706ID - GM23883/GM/NIGMSPT - Journal ArticleCY - UNITED STATESTA - ScienceJID - 0404511RN - 0 (Helminth Proteins)RN - 0 (Sodium Channels)RN - 0 (Unc-105 protein)RN - 9007-34-5 (Collagen)SB - IMSB - S

Kimura KD et al. (1997) Science "daf-2, an insulin receptor-like gene that regulates longevity and diapause in Caenorhabditis elegans."

Liu YX, Kimura KD, Ruvkun GB, Tissenbaum HA

[Science, 1997]

A C. elegans neurosecretory signaling system regulates whether animals enter the reproductive life cycle or arrest development at the long-lived dauer diapause stage. daf-2, a key gene in the genetic pathway that mediates this endocrine signaling, encodes an insulin receptor family member. Decreases in DAF-2 signaling induce metabolic and developmental changes, as in mammalian metabolic control by the insulin receptor. Decreased DAF-2 signaling also causes an increase in life-span. Life-span regulation by insulin-like metabolic control is analogous to mammalian longevity enhancement induced by caloric restriction, suggesting a general link between metabolism, diapause, and longevity.AD - Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.FAU - Kimura, K DAU - Kimura KDFAU - Tissenbaum, H AAU - Tissenbaum HAFAU - Liu, YAU - Liu YFAU - Ruvkun, GAU - Ruvkun GLA - engSI - GENBANK/AF012437ID - RO1AG14161/AG/NIAPT - Journal ArticleCY - UNITED STATESTA - ScienceJID - 0404511RN - 0 (DAF-2 protein)RN - 0 (Phosphatidylinositol Phosphates)RN - 0 (insulin receptor-related receptor)RN - 0 (phosphatidylinositol 3,4,5-triphosphate)RN - 11061-68-0 (Insulin)RN - 50-99-7 (Glucose)RN - EC 2.7.1 (Phosphotransferases (Alcohol Group Acceptor))RN - EC 2.7.1.137 (1-Phosphatidylinositol 3-Kinase)RN - EC 2.7.11.- (Receptor, IGF Type 1)RN - EC 2.7.11.- (Receptor, Insulin)SB - IM

Liu H et al. (2021) STAR Protoc "Protocols for electrophysiological recordings and electron microscopy at C.elegans neuromuscular junction."

Richmond JE, Krout M, Chen J, Sheoran S, Liu H, Hu Z, Li L, Zhao Q

[STAR Protoc, 2021]

Release of neurotransmitters by synaptic vesicle exocytosis at presynaptic terminals is critical for neuronal communication within the nervous system. Electrophysiology and electron microscopy are powerful and complementary approaches used to evaluate the function of synaptic proteins in synaptic transmission. Here, we provide a protocol detailing the use of these two approaches at C.elegans neuromuscular junctions, including steps for worm picking and dissection, in vivo electrophysiological recording, and sample preparation for electron microscopy, followed by imaging and analysis. For complete details on the use and execution of this protocol, please refer to Liu etal. (2021) and Li etal. (2021).

Chen, Lili et al. (2020) MicroPubl Biol

Wang, Ya, Chen, Lili, Gao, Shangbang

[MicroPubl Biol, 2020]

The action potential (AP) is the basic signaling unit in various crucial physiological processing, for instance, in neurotransmission, muscle contraction, and glandular secretion (Koch, 1990). The classic model animal, Caenorhabditis elegans (or C. elegans), with a simple and compact nervous system, conservatively employs the calcium-mediated all-or-none APs for odor response in AWA olfactory neurons (Liu et al., 2018), as well as for muscle contraction in either body wall muscles (Gao and Zhen, 2011; Liu et al., 2011) and pharyngeal muscles (Davis et al., 1999). Plateau potentials were also observed in ASE and RMD neurons (Goodman et al., 1998; Mellem et al., 2008; Lockery et al., 2009; Lockery and Goodman, 2009), though the underlying roles in specific behavior are still elusive. Either in neurons or in muscles, the action potential firing is dependent on the excitatory pre-synaptic vesicles release. The minimum number of the presynaptic vesicles to elicit a single action potential in C. elegans has not been reported before. Here, by the combination of optogenetics with in-vivo patch clamping technology, we demonstrated that at least approximately 37 excitatory acetylcholinergic vesicles are required for the initiation of an action potential at post-synaptic body wall muscles.

Liu J et al. (2024) STAR Protoc "Protocol for survival assay of Caenorhabditis elegans to Pseudomonas aeruginosa PA14 infection."

Wang M, Liu J, Lei M, Tu H, Chen S

[STAR Protoc, 2024]

The nematode Caenorhabditis elegans is a powerful model organism for studying the molecular and cellular mechanisms of innate immunity governed by the intestine. Here, we present a protocol to perform C. elegans survival assays to infection by the bacterial pathogen Pseudomonas aeruginosa PA14. Specifically, we describe steps for preparing C. elegans strains and PA14 bacteria for survival assays. This protocol will assist researchers to study genes involved in intestinal innate immunity and gut defense against pathogen infection. For complete details on the use and execution of this protocol, please refer to Liu et al.¹ and Zheng et al.².

Teramoto T et al. (2006) Cell Calcium "Intestinal calcium waves coordinate a behavioral motor program in C. elegans."

Iwasaki K, Teramoto T

[Cell Calcium, 2006]

Periodic behavioral motor patterns are normally controlled by neural circuits, such as central pattern generators. We here report a novel mechanism of motor pattern generation by non-neural cells. The defecation motor program in Caenorhabditis elegans consists of three stereotyped motor steps with precise timing and this behavior has been studied as a model system of a ultradian biological clock [J.H. Thomas, Genetic analysis of defecation in C. elegans, Genetics 124 (1990) 855-872; D.W. Liu, J.H. Thomas, Regulation of a periodic motor program in C. elegans, J. Neurosci. 14 (1994) 1953-1962; K. Iwasaki, D.W. Liu, J.H. Thomas, Genes that control a temperature-compensated ultradian clock in Caenorhabditis elegans, Proc. Natl. Acad. Sci. USA 92 (1995), 10317-10321]. It was previously implied that the inositol-1,4,5-trisphosphate (IP3) receptor in the intestine was necessary for this periodic behavior [P. Dal Santo, M.A. Logan, A.D. Chisholm, E.M. Jorgensen, The inositol trisphosphate receptor regulates a 50s behavioral rhythm in C. elegans, Cell 98 (1999) 757-767]. Therefore, we developed a new assay system to study a relationship between this behavioral timing and intestinal Ca(2+) dynamics. Using this assay system, we found that the timing between the first and second motor steps is coordinated by intercellular Ca(2+)-wave propagation in the intestine. Lack of the Ca(2+)-wave propagation correlated with no coordination of the motor steps in the CaMKII mutant. Also, when the Ca(2+)-wave propagation was blocked by the IP3 receptor inhibitor heparin at the mid-intestine in wild type, the second/third motor steps were eliminated, which phenocopied ablation of the motor neurons AVL and DVB. These observations suggest that an intestinal Ca(2+)-wave propagation governs the timing of neural activities that controls specific behavioral patterns in C. elegans.

Lee, Jongsun et al. (2020) MicroPubl Biol

Lee, Seung-Jae V., Lee, Jongsun, Kim, Sieun S.

[MicroPubl Biol, 2020]

Mechanistic target of rapamycin (mTOR), a serine/threonine protein kinase, regulates biological processes in response to changes in nutrients or metabolites (Reviewed in Liu and Sabatini, 2020). Inhibition of mTOR signaling delays aging and increases lifespan in multiple organisms by downregulating substrates, including S6 kinase (S6K) that phosphorylates ribosomal subunit 6 (Reviewed in Kennedy and Lamming, 2016). Genetic inhibition of RSKS-1, the Caenorhabditis elegans S6 kinase, extends lifespan via decreasing protein synthesis and upregulating longevity-promoting factors (Reviewed in Johnson et al., 2013; Lee et al. 2015). However, the longevity phenotypes of previously characterized loss-of-function rsks-1 mutants are variable and greatly affected by environmental factors, such as temperatures (Seo et al., 2013; Miller et al., 2017). Here, we aimed at identifying rsks-1 mutants whose lifespan phenotypes are robust and reproducible at 20C, the standard temperature for C. elegans lifespan assays.