Shingai R et al. (2013) Front Behav Neurosci "Evaluation of Head Movement Periodicity and Irregularity during Locomotion of Caenorhabditis elegans."

Furudate M, Iwasaki Y, Shingai R, Hoshi K

[Front Behav Neurosci, 2013]

Caenorhabditis elegans is suitable for studying the nervous system, which controls behavior. C. elegans shows sinusoidal locomotion on an agar plate. The head moves not only sinusoidally but also more complexly, which reflects regulation of the head muscles by the nervous system. The head movement becomes more irregular with senescence. To date, the head movement complexity has not been quantitatively analyzed. We propose two simple methods for evaluation of the head movement regularity on an agar plate using image analysis. The methods calculate metrics that are a measure of how the head end movement is correlated with body movement. In the first method, the length along the trace of the head end on the agar plate between adjacent intersecting points of the head trace and the quasi-midline of the head trace, which was made by sliding an averaging window of 1/2 the body wavelength, was obtained. Histograms of the lengths showed periodic movement of the head and deviation from it. In the second method, the intersections between the trace of the head end and the trace of the 5 (near the pharynx) or 50% (the mid-body) point from the head end in the centerline length of the worm image were marked. The length of the head trace between adjacent intersections was measured, and a histogram of the lengths was produced. The histogram for the 5% point showed deviation of the head end movement from the movement near the pharynx. The histogram for the 50% point showed deviation of the head movement from the sinusoidal movement of the body center. Application of these methods to wild type and several mutant strains enabled evaluation of their head movement periodicity and irregularity, and revealed a difference in the age-dependence of head movement irregularity between the strains. A set of five parameters obtained from the histograms reliably identifies differences in head movement between strains.

Shen Y et al. (2016) Elife "An extrasynaptic GABAergic signal modulates a pattern of forward movement in Caenorhabditis elegans."

Qin Y, Kawano T, Liu H, Zhong C, Samuel AD, Wu M, Xu T, Harris G, Zhang Y, Shen Y, Wen Q

[Elife, 2016]

As a common neurotransmitter in the nervous system, -aminobutyric acid (GABA) modulates locomotory patterns in both vertebrates and invertebrates. However, the signaling mechanisms underlying the behavioral effects of GABAergic modulation are not completely understood. Here, we demonstrate that a GABAergic signal in C. elegans modulates the amplitude of undulatory head bending through extrasynaptic neurotransmission and conserved metabotropic receptors. We show that the GABAergic RME head motor neurons generate undulatory activity patterns that correlate with head bending and the activity of RME causally links with head bending amplitude. The undulatory activity of RME is regulated by a pair of cholinergic head motor neurons SMD, which facilitate head bending, and inhibits SMD to limit head bending. The extrasynaptic neurotransmission between SMD and RME provides a gain control system to set head bending amplitude to a value correlated with optimal efficiency of forward movement.

Ouellette MH et al. (2018) eNeuro "A Gate-and-Switch Model for Head Orientation Behaviors in Caenorhabditis elegans."

Desrochers MJ, Gheta I, Ouellette MH, Ramos R, Hendricks M

[eNeuro, 2018]

The nervous system seamlessly integrates perception and action. This ability is essential for stable representation of and appropriate responses to the external environment. How the sensorimotor integration underlying this ability occurs at the level of individual neurons is of keen interest. In <i>Caenorhabditis elegans</i>, RIA interneurons receive input from sensory pathways and have reciprocal connections with head motor neurons. RIA simultaneously encodes both head orientation and sensory stimuli, which may allow it to integrate these two signals to detect the spatial distribution of stimuli across head sweeps and generate directional head responses. Here, we show that blocking synaptic release from RIA disrupts head orientation behaviors in response to unilaterally presented stimuli. We found that sensory encoding in RIA is gated according to head orientation. This dependence on head orientation is independent of motor encoding in RIA, suggesting a second, posture-dependent pathway upstream of RIA. This gating mechanism may allow RIA to selectively attend to stimuli that are asymmetric across head sweeps. Attractive odor removal during head bends triggers rapid head withdrawal in the opposite direction. Unlike sensory encoding, this directional response is dependent on motor inputs to and synaptic output from RIA. Together, these results suggest that RIA is part of a sensorimotor pathway that is dynamically regulated according to head orientation at two levels: the first is a gate that filters sensory representations in RIA, and the second is a switch that routes RIA synaptic output to dorsal or ventral head motor neurons.

Zhang H et al. (2022) BMC Bioinformatics "Automated recognition and analysis of head thrashes behavior in C. elegans."

Zhang H, Chen W, Gao S

[BMC Bioinformatics, 2022]

BACKGROUND: Locomotive behaviors are a rapid evaluation indicator reflecting whether the nervous system of worms is damaged, and has been proved to be sensitive to chemical toxicity. In many toxicological studies, C. elegans head thrashes is a key indicator of locomotive behaviors to measure the vitality of worms. In previous studies, the number of head thrashes was manually counted, which is time-consuming and labor-intensive. RESULTS: This paper presents an automatic recognition and counting method for head thrashes behavior of worms from experimental videos. First, the image processing algorithm is designed for worm morphology features calculation, mean gray values of head and tail are used to locate the head of worm accurately. Next, the worm skeleton is extracted and divided into equal parts. The angle formulas are used to calculate the bending angle of the head of worm. Finally, the number of head thrashes is counted according to the bending angle of the head in each frame. The robustness of the proposed algorithm is evaluated by comparing the counting results of the manual counting. It is proved that the proposed algorithm can recognize the occurrence of head thrashes of C. elegans of different strains. In addition, the difference of the head thrashes behavior of different worm strains is analyzed, it is proved that the relationship between worm head thrashes behavior and lifespan. CONCLUSIONS: A new method is proposed to automatically count the number of head thrashes of worms. This algorithm makes it possible to count the number of head thrashes from the worm videos collected by the automatic tracking system. The proposed algorithm will play an important role in toxicological research and worm vitality research. The code is freely available at https://github.com/hthana/HTC .

Singh VK et al. (2015) Eur J Med Chem "Synthesis, molecular docking and Brugia malayi thymidylate kinase (BmTMK) enzyme inhibition study of novel derivatives of [6]-shogaol."

Narender T, Doharey PK, Singh VK, Rathaur S, Siddiqi MI, Saxena JK, Kumar V

[Eur J Med Chem, 2015]

[6]-Shogaol (1) was isolated from Zingiber officinale. Twelve novel compounds have been synthesized and evaluated for their Brugia malayi thymidylate kinase (BmTMK) inhibition activity, which plays important role for the DNA synthesis in parasite. [6]-Shogaol (1) and shogaol with thymine head group (2), 5-bromouracil head group (3), adenine head group (4) and 2-amino-3-methylpyridine head group (5) showed potential inhibitory effect on BmTMK activity. Further molecular docking studies were carried out to explore the putative binding mode of compounds 1-5.

Liao W et al. (2010) J Biol Chem "Head of myosin IX binds calmodulin and moves processively toward the plus-end of actin filaments."

Elfrink K, Liao W, Bahler M

[J Biol Chem, 2010]

Mammalian myosin IXb (Myo9b) has been shown to exhibit unique motor properties in that it is a single-headed processive motor and the rate-limiting step in its chemical cycle is ATP hydrolysis. Furthermore, it has been reported to move toward the minus- and the plus-end of actin filaments. To analyze the contribution of the light chain-binding domain to the movement, processivity, and directionality of a single-headed processive myosin, we expressed constructs of Caenorhabditis elegans myosin IX (Myo9) containing either the head (Myo9-head) or the head and the light chain-binding domain (Myo9-head-4IQ). Both constructs supported actin filament gliding and moved toward the plus-end of actin filaments. We identified in the head of class IX myosins a calmodulin-binding site at the N terminus of loop 2 that is unique among the myosin superfamily members. Ca(2+)/calmodulin negatively regulated ATPase and motility of the Myo9-head. The Myo9-head demonstrated characteristics of a processive motor in that it supported actin filament gliding and pivoting at low motor densities. Quantum dot-labeled Myo9-head moved along actin filaments with a considerable run length and frequently paused without dissociating even in the presence of obstacles. We conclude that class IX myosins are plus-end-directed motors and that even a single head exhibits characteristics of a processive motor.

Motomura H et al. (2022) Proc Natl Acad Sci U S A "Head-tail-head neural wiring underlies gut fat storage in Caenorhabditis elegans temperature acclimation."

Motomura H, Ohta A, Ioroi M, Kuhara A, Murakami K

[Proc Natl Acad Sci U S A, 2022]

Animals maintain the ability to survive and reproduce by acclimating to environmental temperatures. We showed here that Caenorhabditis elegans exhibited temperature acclimation plasticity, which was regulated by a head-tail-head neural circuitry coupled with gut fat storage. After experiencing cold, C. elegans individuals memorized the experience and were prepared against subsequent cold stimuli. The cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) regulated temperature acclimation in the ASJ thermosensory neurons and RMG head interneurons, where it modulated ASJ thermosensitivity in response to past cultivation temperature. The PVQ tail interneurons mediated the communication between ASJ and RMG via glutamatergic signaling. Temperature acclimation occurred via gut fat storage regulation by the triglyceride lipase ATGL-1, which was activated by a neuropeptide, FLP-7, downstream of CREB. Thus, a head-tail-head neural circuit coordinated with gut fat influenced experience-dependent temperature acclimation.

Yeon J et al. (2018) PLoS Biol "A sensory-motor neuron type mediates proprioceptive coordination of steering in C. elegans via two TRPC channels."

Kim J, Du EJ, Yeon J, Kim H, Kim DY, Kim K, Moon D, Kang K, Lim HH

[PLoS Biol, 2018]

Animal locomotion is mediated by a sensory system referred to as proprioception. Defects in the proprioceptive coordination of locomotion result in uncontrolled and inefficient movements. However, the molecular mechanisms underlying proprioception are not fully understood. Here, we identify two transient receptor potential cation (TRPC) channels, trp-1 and trp-2, as necessary and sufficient for proprioceptive responses in C. elegans head steering locomotion. Both channels are expressed in the SMDD neurons, which are required and sufficient for head bending, and mediate coordinated head steering by sensing mechanical stretches due to the contraction of head muscle and orchestrating dorsal head muscle contractions. Moreover, the SMDD neurons play dual roles to sense muscle stretch as well as to control muscle contractions. These results demonstrate that distinct locomotion patterns require dynamic and homeostatic modulation of feedback signals between neurons and muscles.

Duke BO (1990) Parasitol Today "Onchocerciasis (river blindness)- can it be eradicated?"

Duke BO

[Parasitol Today, 1990]

Onchocerca volvulus causes a disease of significant socio-economic importance in West Africa, the Arabian Peninsula and regions of South America. Brian Duke explains that, despite the advent of ivermectin, the prospects for the eradication of this potentially highly debilitating infection are remote. Moreover, the logistical problems associated with the control of morbidity caused by the parasite are considerable, and are highly dependent on the ability to sustain financial support and political will over many decades.

Hosono R et al. (1982) J Exp Zool "Mutants of C. elegans with Dumpy and Rounded head phenotype."

Hosono R, Kurihara T, Hirahara K, Kuno S

[J Exp Zool, 1982]

Mutations bearing morphological alterations in both head and body are reported in Caenorhabditis elegans. Although most dumpy mutants so far isolated have shorter bodies with normal head form, the mutants presented in this paper have rounded heads in addition to dumpy bodies. On examination with light- and scanning electron microscopes, defects in organs attached to the tip of head were not detected. The mutations were mapped as alleles of the dpy-20 gene on linkage group IV. Segregation of the head abnormality from dumpy body was not detected upon examination of over 10,000 descendants from heterozygous offspring (F1) produced by crossing mutant hermaphrodites with wild-type males. Revertants of dpy-20(cn142) allele were found to be almost wild-type in both head and other body morphology, supporting the possibility that both phenotypes in these alleles have been produced by a single mutation. Genetic analysis of two other revertants are also presented in this