Krieg, Michael et al. (2015) International Worm Meeting "Shaping neurons by twist-tension coupling in chiral cytoskeleton networks."

Krieg, Michael, Shen, Kang, Cueva, Juan G., Spilker, Kerry, Goodman, Miriam B., Dunn, Alexander R.

[International Worm Meeting, 2015]

All animals and plants, even protozoa, have evolved specialized molecular sensors that convert mechanical stress into behavioral responses. The touch receptor neurons (TRNs) in Caenorhabditis elegans respond to gentle body touch and are especially well characterized on a physiological and ultrastructural level, a knowledge which is unavailable in other animals. Moreover, C. elegans is a unique model organism to study the mechanics of neurons due to their simple shapes, the known wiring diagram and a rich repertoire of simple behaviors, thus permitting a systems perspective on cell function.As in other animals, neuron morphology is critical for function in C. elegans. Some neurons are highly branched and curved, while others are extremely straight. We have previously shown that a functional, pre-stressed spectrin network is critical for mechanosensation and neuron stability under body-evoked forces (Krieg, Nat Cell Bio, 2014). How the constituent molecules of these different neurons establish a functional organization and how nanometer sized molecules can determine cell shape in the millimeter scale is still not understood. To establish this paradigm, we first compared different neurons and classified their shapes. We then used electron and STED microscopy to investigate how the organization of microtubule bundles and spectrin network determines neuron morphology. We found that TRNs with defective organization in both cytoskeletal elements undergo deformations highly similar to a twisted rod under compression. These experimental results, together with mechanical modeling of the neuron, suggest that spectrin tension and microtubule bundle mechanics are crucial for stabilizing chiral cytoskeletal networks and produce a specialized cell shape that we propose is critical for mechanosensation.

Krieg, Michael et al. (2013) International Worm Meeting "A Pre-Stressed UNC-70 b-Spectrin Network Governs the Sense of Touch."

Krieg, Michael, Goodman, Miriam B, Dunn, Alexander R

[International Worm Meeting, 2013]

Many somatosensory neurons have evolved specialized molecular sensors that convert mechanical stress into behavioral responses. The genetics, development and physiology of the touch receptor neurons (TRNs) in Caenorhabditis elegans nematodes are especially well characterized and this animal has the particular advantage that the TRNs can be studied both in living animals and dissociated in culture. Like other somatosensory neurons, the TRNs use ion channels to convert mechanical stress into electrical signals and ultimately appropriate behaviors. Whereas the protein partners that form these mechanosensitive channels have been known for some time, the nature of the molecular machine important for efficient force transmission from skin to touch receptor neurite is essentially unknown. Here we show that sensation of mechanical forces depends on a continuous, pre-strained spectrin cytoskeleton inside neurons. We observed that mutations in the tetramerization domain of C. elegans b-spectrin (UNC-70), an actin-membrane crosslinker, lead to defective neuron morphologies under compressive stresses in moving animals. We performed AFM force spectroscopy experiments on isolated neurons, laser axotomy and FRET imaging to measure force across single cells and molecules. Our data indicate that spectrin is held under constitutive tension in living animals, which contributes to an elevated pre-stress in TRNs. Based on these results and data obtained from optogenetic and mechanical stimulation on b-spectrin mutants, we suggest that b-spectrin-dependent pre-tension is required for efficient responses to external mechanical stimuli.

Colonnello A et al. (2020) Neurotox Res "Correction to: Comparing the Neuroprotective Effects of Caffeic Acid in Rat Cortical Slices and Caenorhabditis elegans: Involvement of Nrf2 and SKN-1 Signaling Pathways."

Tunez I, Rubio-Lopez LC, Aguilera-Portillo G, Silva-Palacios A, Evaristo-Priego Y, Santamaria A, Galvan-Arzate S, Cortez-Nunez S, Aschner M, Rangel-Lopez E, Chen P, Colonnello A, Robles-Banuelos B, Garcia-Contreras R

[Neurotox Res, 2020]

One of the authors has incorrect family name spelling in the original article_. Michael Ashner should read as Michael Aschner.

Hengartner MO et al. (1992) Worm Breeder's Gazette "unc-50, a Gene Required for Acetylcholine Receptor Function, Encodes an Unfamiliar Protein"

Horvitz HR, Tsung N, Hengartner MO, Lewis JA

[Worm Breeder's Gazette, 1992]

unc-50, a gene requiired for acetylcholine receptor function, encodes an unfamiliar protein Michael Hengartner, Nancy Tsung, Jim Lewist, and Bob Horvitz HHMI, Dept. Biology, MIT, Cambridge, MA 02139, USA. t Division of Life Sciences, U. of Texas at San Antonio, San Antonio, IX 78249

Holway AH et al. (2007) J Cell Biol "Checkpoint silencing during the DNA damage response in Caenorhabditis elegans embryos"

Kim SH, Michael WM, La Volpe A, Holway AH

[J Cell Biol, 2007]

After publication of this manuscript, the authors noticed that two images (Fig. 4 B, top left and middle) had been duplicated from a previous publication (Holway, A.H., C. Hung, and W.M. Michael. 2005. Genetics. 169:14511460). Here we provide new images corresponding to these control experiments. The authors apologize for this oversight.

Zhou MH et al. (1996) Worm Breeder's Gazette "Liquid Culture of the Worms with a Fermentor"

Zhou MH, Yang H, Walthall WW

[Worm Breeder's Gazette, 1996]

The yield of C. elegans and their food (E.coli) are relatively low in the large liquid cultures growth (Koelle et al.,1994) and the whole growth process is tedious. Here we report the successful growth of C.elegans with a fermentor. The following protocol is based on the protocol by Michael Koelle and Tory Herman (1994) from Internet.

Michael WM (2017) MicroPubl Biol "Asymmetric distribution of cyb-3 in 4-cell stage embryos."

Michael WM

[MicroPubl Biol, 2017]

Early embryos were fixed and stained with Mab F2F4 (green), shown to recognize CYB-3 (Michael, 2016), and DAPI, to illuminate the DNA (blue). Either wild type or par-4 mutant embryos were examined, after 24-hour incubation at 25C (the non-permissive temperature for the it47 allele of par-4). Anterior is to the left in all images. The data presented here reveals previously not shown data that depicts CYB-3 as asymmetrically distributed at the 4-cell stage. These data further support reported findings in Michael, 2016. There is more CYB-3 in the AB cell relative to its sister P1. In 4-cell embryos there is more CYB-3 in the EMS cell relative to its sister, P2. Thus, during P-lineage divisions, CYB-3 is asymmetrically distributed such that the somatic precursor receives more than its germline precursor sister cell. This asymmetry is abolished in par-4 mutant embryos, where all blastomeres contain equivalent amounts of CYB-3.

Sanfeliu-Cerdan, Neus et al. (2021) International Worm Meeting "Transducing touch by a titin-related protein in the worm"

Sanfeliu-Cerdan, Neus, Catala-Castro, Frederic, Krieg, Michael, Porta-de-la-Riva, Montserrat

[International Worm Meeting, 2021]

Of the five traditional senses, touch is the first one available to us when we are born. Despite being a relatively little investigated sensory modality, touch governs our daily lives, from walking and feeding to kissing and cuddling. How mechanical forces reach the mechanoelectrical transduction channels remains an open question. To address this knowledge gap, we study the mechanotransduction pathway of C. elegans' gentle touch, which relies on the six touch receptor neurons that tile the body into two receptive fields. We showed that a protein-protein interaction motif at the MEC-2 C-terminus is critical for mechanosensation, without interfering with its localization. To understand the function of MEC-2 C-terminus in touch, we conditionally coupled it to different components of the cytoskeleton. This artificial coupling was able to recover nearly wildtype functions of MEC-2, implying a role in force transfer. We then combined genetic engineering, microfluidics, and FRET-based molecular tension microscopy and found that MEC-2 is under tension when a force is applied to the body wall of the worm. To uncover an endogenous binding partner of MEC-2, we performed a neuronal RNAi screening. Surprisingly, interference of unc-89/obscn, which encodes for a protein related to the giant human titin, led to decreased touch response and colocalizes with wt but not mutant MEC-2 in TRNs. In summary, our study sheds light into how mechanical forces propagate to the mechanosensitive channels and show the first example for titin in neuronal mechanotransduction.

Porta de la Riva, Montserrat et al. (2021) International Worm Meeting "Functional photon-based neurotransmission in a nociceptive avoidance circuit"

Sanfeliu Cerdan, Neus, Porta de la Riva, Montserrat, Krieg, Michael, Catala Castro, Frederic, Gonzalez, Adriana

[International Worm Meeting, 2021]

Communication between cells is essential during development, homeostasis and nervous system function. The distribution of information is carried out by secreted chemicals, which are released and perceived by different cells. Defects in neurotransmission can lead to neurological disorders and lack of adaptation of the surrounding environment. Here, we have developed a synthetic, photon-based signaling system that we used to overcome synaptic transmission defects in C. elegans, restoring the communication between nervous cells. In particular, we have replaced a conditional defect for glutamate release in the nociceptor neuron ASH with a calcium sensitive light emitting enzyme (enhanced Nanolantern). To prove functionality, we built an optimized microscope capable of detecting how cellular calcium increase triggers light production in vivo. Subsequently, light emission is coupled to downstream interneurons (AVA, AIB) expressing an ultrasensitive light-gated ion channel (Channelrhodopsin-XXL). Finally, we developed a new microfluidic device, which we call Trap'N'Slap, with the aim to deliver mechanical stimuli directly to ASH, while recording calcium transients (by means of Genetically Encoded Calcium Indicators) directly from AVA and AIB. This, together with behavioral nose touch assays, proved that quantum release from ASH, is able to recover functional communication between neurons in an endogenous circuit.

Vairoletti F et al. (2019) Medchemcomm "Synthesis of bicyclic 1,4-thiazepines as novel anti-Trypanosoma brucei brucei agents."

Medeiros A, Fontan P, Jancik V, Melendrez J, Saiz C, Vairoletti F, Tabarez C, Mahler G, Franco J, Salinas G, Comini MA, Saldana J

[Medchemcomm, 2019]

1,4-Thiazepines derivatives are pharmacologically important heterocycles with different applications in medicinal chemistry. In the present work, we describe the preparation of new bicyclic thiazolidinyl-1,4-thiazepines <b>3</b> by reaction between azadithiane compounds and Michael acceptors. The reaction scope was explored and the yields were optimized. The activity of the new compounds was evaluated against <i>Nippostrongylus brasiliensis</i> and <i>Caenorhabditis elegans</i> as anthelmintic models and <i>Trypanosoma brucei brucei.</i> The most active compound was <b>3l</b>, showing an EC₅₀ = 2.8 +/- 0.7 M against <i>T. b. brucei</i> and a selectivity index &gt;71.