Braukmann F et al. (2017) RNA Biol "Artificial and natural RNA interactions between bacteria and C. elegans."

Jordan D, Miska E, Braukmann F

[RNA Biol, 2017]

19years after Lisa Timmons and Andy Fire first described RNA transfer from bacteria to C. elegans in an experimental setting [Timmons and Fire, 1998 ] the biological role of this trans-kingdom RNA-based communication remains unknown. Here we summarize our current understanding on the mechanism and potential role of such social RNA.

Satyal P et al. (2013) Nat Prod Commun "Bioactivities and compositional analyses of Cinnamomum essential oils from Nepal: C. camphora, C. tamala, and C. glaucescens."

Pokharel KK, Poudel A, Setzer WN, Satyal P, Dosoky NS, Paudel P

[Nat Prod Commun, 2013]

This work examines the biological activity of essential oils of Cinnamomum camphora leaves, C. glaucescens fruit, and C. tamala root from Nepal. The oils were screened for phytotoxic activity against lettuce and perennial ryegrass, brine shrimp lethality, and antibacterial, antifungal, cytotoxic, insecticidal, and nematicidal activities. C. camphora leaf essential oil was phytotoxic to lettuce, antifungal to Aspergillus niger, and insecticidal, particularly toward midge and butterfly larvae, fruit flies, and fire ants. C. camphora oil was also toxic to brine shrimp and human breast tumor cells. C. glaucescens fruit essential oil showed notable nematicidal activity, as well as termiticidal and mosquito larvicidal activity. The root essential oil of C. tamala was toxic to mosquito larvae and fire ants.

Wang J et al. (2005) Methods Enzymol "RNA interference in Caenorhabditis elegans."

Barr MM, Wang J

[Methods Enzymol, 2005]

RNA interference (RNAi) was first discovered in the nematode Caenorhabditis elegans (Fire et al., 1998; Guo and Kemphues, 1995). The completion of the C. elegans genome in 1998 coupled with the advent of RNAi techniques to knock down gene function ushered in a new age in the field of functional genomics. There are four methods for double-stranded RNA (dsRNA) delivery in C. elegans: (1) injection of dsRNA into any region of the animal (Fire et al., 1998), (2) feeding with bacteria producing dsRNA (Timmons et al., 2001), (3) soaking in dsRNA (Tabara et al., 1998), and (4) in vivo production of dsRNA from transgenic promoters (Tavernarakis et al., 2000). In this chapter, we discuss the molecular genetic mechanisms, techniques, and applications of RNAi in C. elegans.

Stifter H et al. (2022) J Vis Exp "A Flame-Free Method for Sterilizing C. elegans Picks, Spatulas, and Scalpels."

Bauer DE, Stifter H

[J Vis Exp, 2022]

Caenorhabtidis elegans (C. elegans) is an optimal model organism for research and education at primarily undergraduate institutions. Undergraduates can quickly learn the sterile technique required to maintain C. elegans cultures. Sterilization of platinum picks used to transfer worms from one plate to another is traditionally done by holding the pick in a flame from a Bunsen burner or ethanol lantern. However, Bunsen burners require a gas source, and both pieces of equipment pose the risk of accidental fire associated with an open flame. Demonstrated here is a technique for sterilizing worm picks, spatulas, and scalpels using an infrared bacteriological loop micro-incinerator. This equipment requires only an electrical outlet and minimizes potential fire hazards. By lowering risk and gas requirements, this technique is well suited for research and teaching in an undergraduate setting.

Fire A et al. (1998) Nature "Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans."

Fire A, Mello CC, Kostas SA, Montgomery MK, Driver SE, Xu SQ

[Nature, 1998]

Experimental introduction of RNA into cells can be used in certain biological systems to interfere with the function of an endogenous gene. Such effects have been proposed to result from a simple antisense mechanism that depends on hybridization between the injected RNA and endogenous messenger RNA transcripts. RNA interference has been used in the nematode Caenorhabditis elegans to manipulate gene expression. Here we investigate the requirements for structure and delivery of the interfering RNA. To our surprise, we found that double-stranded RNA was substantially more effective at producing interference than was either strand individually. After injection into adult animals, purified single strands had at most a modest effect, whereas double-stranded mixtures caused potent and specific interference. The effects of this interference were evident in both the injected animals and their progeny. Only a few molecules of injected double-stranded RNA were required per affected cell, arguing against stochiometric interference with endogenous mRNA and suggesting that there could be a catalytic or amplification component in the interference process.AD - Carnegie Institution of Washington, Department of Embryology, Baltimore, Maryland 21210, USA. fire@mail1.ciwemb.eduFAU - Fire, AAU - Fire AFAU - Xu, SAU - Xu SFAU - Montgomery, M KAU - Montgomery MKFAU - Kostas, S AAU - Kostas SAFAU - Driver, S EAU - Driver SEFAU - Mello, C CAU - Mello CCLA - engPT - Journal ArticleCY - ENGLANDTA - NatureJID - 0410462RN - 0 (Calmodulin-Binding Proteins)RN - 0 (Helminth Proteins)RN - 0 (Muscle Proteins)RN - 0 (RNA, Antisense)RN - 0 (RNA, Double-Stranded)RN - 0 (twitchin)SB - IM

Mellem JE et al. (2008) Nat Neurosci "Action potentials contribute to neuronal signaling in C. elegans."

Brockie PJ, Madsen DM, Mellem JE, Maricq AV

[Nat Neurosci, 2008]

Small, high-impedance neurons with short processes, similar to those found in the soil nematode Caenorhabditis elegans, are predicted to transmit electrical signals by passive propagation. However, we have found that certain neurons in C. elegans fire regenerative action potentials. These neurons resembled Schmitt triggers, as their potential state appears to be bistable. Transitions between up and down states could be triggered by application of the neurotransmitter glutamate or brief current pulses.

(2021) Development "The people behind the papers - Clement Dubois, Shivam Gupta, Andrew Mugler and Marie-Anne Felix."

[Development, 2021]

Cell migration needs to be precisely regulated during development so that cells stop in the right position. A new paper in Development investigates the robustness of neuroblast migration in the <i>C. elegans</i> larva in the face of both genetic and environmental variation. To hear more about the story, we met the paper's four authors: Clement Dubois and Shivam Gupta, and their respective supervisors Andrew Mugler (currently Assistant Professor at the Department of Physics and Astronomy at the University of Pittsburgh, where his lab recently moved from Purdue University) and Marie-Anne Felix (Principal Investigator at Institut de Biologie de l'Ecole Normale Superieure in Paris and Research Director at CNRS).

Satyal P et al. (2012) Nat Prod Commun "Chemical compositions and biological activities of Amomum subulatum essential oils from Nepal."

Kincer BL, Satyal P, Setzer WN, Dosoky NS

[Nat Prod Commun, 2012]

The essential oils from the seed and rind of Amomum subulatum Roxb. (collected from Nepal) were obtained by hydrodistillation and analyzed by GC-MS. A total of 87 components were identified among the two essential oils accounting for 99.1%, and 99.0% of the oils, respectively. The two essential oils were dominated by the monoterpenoids 1,8-cineole (60.8% and 39.0%), alpha-pinene (6.4% and 4.8%), beta-pinene (8.3% and 17.7%), and alpha-terpineol (9.8% and 12.3%). Allelopathic testing of the seed essential oil showed an inhibition of seed germination of Lactuca sativa and Lolium perenne, with IC50 values of 1583 and 1674 microg/mL, respectively. The seed essential oil demonstrated a stronger seedling growth inhibition of L. perenne than of L. sativa. A. subulatum seed and rind oils also showed moderate brine shrimp lethality (LC50 = 28.1 +/- 3.0 and 15.0 +/- 9.0 microg/mL, respectively). The seed and rind oils were only marginally cytotoxic (20% and 30%% kill on MCF-7 cells at 100 microg/mL, respectively), and antibacterial (MIC &gt; or = 313 microg/mL), but A. subulatum rind oil was appreciably active against the fungus Aspergillus niger (MIC = 19.5 microg/mL). The essential oils of A. subulatum were also screened for nematocidal activity against Caenorhabditis elegans and insecticidal activity against the fruit fly (Drosophila melanogaster) and the red imported fire ant (Solenopsis invicta x richteri). The seed oil was only marginally toxic to the fire ant (LC50 = 1500 microg/mL), but moderately toxic to the nematode and the fruit fly (LC50 = 341 and 441 microg/mL, respectively).

Gao S et al. (2011) Proc Natl Acad Sci U S A "Action potentials drive body wall muscle contractions in Caenorhabditis elegans."

Zhen M, Gao S

[Proc Natl Acad Sci U S A, 2011]

The sinusoidal locomotion exhibited by Caenorhabditis elegans predicts a tight regulation of contractions and relaxations of its body wall muscles. Vertebrate skeletal muscle contractions are driven by voltage-gated sodium channel-dependent action potentials. How coordinated motor outputs are regulated in C. elegans, which does not have voltage-gated sodium channels, remains unknown. Here, we show that C. elegans body wall muscles fire all-or-none, calcium-dependent action potentials that are driven by the L-type voltage-gated calcium and Kv1 voltage-dependent potassium channels. We further demonstrate that the excitatory and inhibitory motoneuron activities regulate the frequency of action potentials to coordinate muscle contraction and relaxation, respectively. This study provides direct evidence for the dual-modulatory model of the C. elegans motor circuit; moreover, it reveals a mode of motor control in which muscle cells integrate graded inputs of the nervous system and respond with all-or-none electrical signals.

Jiang J et al. (2022) Nat Commun "C. elegans enteric motor neurons fire synchronized action potentials underlying the defecation motor program."

Tao L, Liu Q, Zhang R, Jiang J, Li H, Su Y

[Nat Commun, 2022]

C. elegans neurons were thought to be non-spiking until our recent discovery of action potentials in the sensory neuron AWA; however, the extent to which the C. elegans nervous system relies on analog or digital coding is unclear. Here we show that the enteric motor neurons AVL and DVB fire synchronous all-or-none calcium-mediated action potentials following the intestinal pacemaker during the rhythmic C. elegans defecation behavior. AVL fires unusual compound action potentials with each depolarizing calcium spike mediated by UNC-2 followed by a hyperpolarizing potassium spike mediated by a repolarization-activated potassium channel EXP-2. Simultaneous behavior tracking and imaging in free-moving animals suggest that action potentials initiated in AVL propagate along its axon to activate precisely timed DVB action potentials through the INX-1 gap junction. This work identifies a novel circuit of spiking neurons in C. elegans that uses digital coding for long-distance communication and temporal synchronization underlying reliable behavioral rhythm.