Liu X et al. (2007) Radiat Environ Biophys "Effects induced by keV low-energy ion irradiation in the nematode Caenorhabditis elegans."

Cai K, Feng H, Kong M, Liu X, Wu Y, Yuan H, Wu L, Yu Z

[Radiat Environ Biophys, 2007]

The nematode Caenorhabditis elegans is an excellent model organism with which to study the biological effects and mechanisms of ionizing irradiation. In this study, using C. elegans as a model, the effects of keV low-energy argon ion irradiation were investigated, by examining cuticle damage, worm survival, brood size, life span, and germ cell death. The surface etching of worm cuticle after ion impact was investigated by trypan blue staining and SEM microscopy. The degree of damage increased with ion fluence (2 x 10(14) to 7 x 10(14) ions cm(-2)) and energy (5-25 keV). The survival rates, as compared to vacuum control, of ion-bombarded worm larvae at different developmental stages (L1-L4) decreased with increasing ion fluence. L1 larvae were found to be more sensitive to ion bombardment than larvae at other stages. The mean brood size in ion-bombarded groups decreased with increasing ion fluence and energy. Furthermore, keV argon ions caused a significant increase in the number of apoptotic germ cells. However, average lifespan was not significantly affected.

Geromanos SJ et al. (2012) Anal Bioanal Chem "Using ion purity scores for enhancing quantitative accuracy and precision in complex proteomics samples."

Vissers JP, Ciavarini S, Geromanos SJ, Langridge JI, Hughes C

[Anal Bioanal Chem, 2012]

To accurately determine the quantitative change of peptides and proteins in complex proteomics samples requires knowledge of how well each ion has been measured. The precision of each ions' calculated area is predicated on how uniquely it occupies its own space in m/z and elution time. Given an initial assumption that prior to the addition of the "heavy" label, all other ion detections are unique, which is arguably untrue, an initial attempt at quantifying the pervasiveness of ion interference events in a representative binary SILAC experiment was made by comparing the centered m/z and retention time of the ion detections from the "light" variant to its "heavy" companion. Ion interference rates were determined for LC-MS data acquired at mass resolving powers of 20 and 40 K with and without ion mobility separation activated. An ion interference event was recorded, if present in the companion dataset was an ion within +/- its mass at half-height, +/-15 s of its apex retention time and if utilized by +/-1 drift bin. Data are presented illustrating a definitive decrease in the frequency of ion interference events with each additional increase in selectivity of the analytical workflow. Regardless of whether the quantitative experiment is a composite of labeled samples or label free, how well each ion is measured can be determined given knowledge of the instruments mass resolving power across the entire m/z scale and the ion detection algorithm reporting both the centered m/z and mass at half-height for each detected ion. Given these measurements, an effective resolution can be calculated and compared with the expected instrument performance value providing a purity score for the calculated ions' area based on mass resolution. Similarly, chromatographic and drift purity scores can be calculated. In these instances, the error associated to an ions' calculated peak area is estimated by examining the variation in each measured width to that of their respective experimental median. Detail will be disclosed as to how a final ion purity score was established, providing a first measure of how accurately each ions' area was determined as well as how precise the calculated quantitative change between labeled or unlabelled pairs were determined. Presented is how common ion interference events are in quantitative proteomics LC-MS experiments and how ion purity filters can be utilized to overcome and address them, providing ultimately more accurate and precise quantification results across a wider dynamic range.

Zhou W et al. (2021) IEEE Trans Ultrason Ferroelectr Freq Control "Ultrasound activation of mechanosensory ion channels in Caenorhabditis elegans."

Niu L, Wang X, Zhou W, Wang K, Meng L, Farooq U, Kang L

[IEEE Trans Ultrason Ferroelectr Freq Control, 2021]

Ultrasound is capable of non-invasive transcranial focusing and activating the targeted neurons in brain regions, receiving increasing attention. Ion channel, acting as a nano-ionic switch, enables to modulate the ion flow across cellular membranes and it is of importance to control the firing frequency of a neuron. In this letter, we demonstrate the behavioral response of the Caenorhabditis elegans (C. elegans) in response to ultrasound stimulation is mediated by the activation of mechanical sensitive MEC-4 and MEC-6 ion channels. By specific mutation of MEC-4 and MEC-6 ion channel, mutant worms show a significant decrease in the percentage of reversal behavior (30 +/- 10.5% and 10 +/- 6.9%, respectively), compared with wild type (85 +/- 8.2%). Furthermore, ALM and PLM neurons expressing MEC-4 and MEC-6 ion channels could be evoked directly by ultrasound stimulation, indicating MEC-4 and MEC-6 may pave a new way for sonogenetics.

Chen L et al. (2018) DNA Repair (Amst) "Induction of reproductive cell death in Caenorhabditis elegans across entire linear-energy-transfer range of carbon-ion irradiation."

Wu L, Dai Z, Zhou L, Wang T, Chen L, Tang H, Bian P, Du Y

[DNA Repair (Amst), 2018]

Heavy-ion radiation has attracted extensive attention as an effective cancer therapy because of the varying energy deposition along its track and its high cell-killing effect. Reproductive cell death (RCD), also known as clonogenic death, is an important mode of death of the cancer cells after radiotherapy. Although RCD induced by heavy-ion irradiation with various linear energy transfers has been demonstrated using clonogenic assay in vitro, little is known about the distribution of RCD across the range of heavy-ion irradiation at the level of whole organisms. In this study, a vulval tissue model of Caenorhabditis elegans was for the first time used to assess RCD in vivo induced by carbon-ion irradiation. A polymethyl methacrylate wedge was designed to provide a gradually varying thickness of shielding, so worms could be exposed to the entire range of carbon-ion irradiation. The carbon-ion irradiation led to a significant induction of RCD over the entire range in a dose-dependent manner. The biological peak did not correspond to the physical Bragg peak and moved forward, rather than spread forward, as radiation dose increased. The degree and shape of the range-distribution of RCD were also affected by the developmental stages of the worms. The gene mutations in DNA-damage checkpoints did not affect the responses of mutant worms positioned in biological peaks, compared to wild-type worms, but decreased radio-sensitivity in the entrance region. An increased induction of RCD was observed in the worms impaired in homologous recombination (HR), but not in non-homologous end jointing pathway, suggesting a crucial role of HR repair in vulval cells of C. elegans in dealing with the carbon-ion-induced DNA damage. These unique manifestations of RCD in vivo in response to carbon-ion irradiation might provide new clues for further investigating the biological effects of heavy-ion irradiation.

Adlimoghaddam A et al. (2014) J Exp Biol "Localization of K, H, Na and Ca fluxes to the excretory pore in Caenorhabditis elegans: application of scanning ion-selective microelectrodes."

O'Donnell MJ, Adlimoghaddam A, Weihrauch D

[J Exp Biol, 2014]

Although Caenorhabditis elegans is commonly used as a model organism for studies of cell biology, development and physiology, the small size of the worm has impeded measurements of ion transport by the excretory cell and hypodermis. Here, we use the scanning ion-selective microelectrode technique to measure efflux and influx of K(+), H(+), Na(+) and Ca(2+) in intact worms. Transport of ions into, or out of, immobilized worms produces small gradients in ion concentration in the unstirred layer near the surface of the worm. These gradients are readily detectable with ion-selective microelectrodes and the corresponding ion fluxes can be estimated using the Fick equation. Our data show that effluxes of K(+), H(+), Na(+) and Ca(2+) are localized to the region of the excretory pore, consistent with release of these ions from the excretory cell, and that effluxes increase after experimental preloading with Na(+), K(+) or Ca(2+). In addition, the hypodermis is a site of Na(+) influx.

Short B (2022) J Gen Physiol "Worms find PEZO-1's function easy to swallow."

Short B

[J Gen Physiol, 2022]

JGP study finds that the C. elegans orthologue of the PIEZO family is a mechanosensitive ion channel that regulates pharyngeal pumping and food sensation.

Jones AK et al. (2007) Invert Neurosci "The nicotinic acetylcholine receptor gene family of the nematode Caenorhabditis elegans: an update on nomenclature."

Jones AK, Davis P, Hodgkin J, Sattelle DB

[Invert Neurosci, 2007]

The simple nematode, Caenorhabditis elegans, possesses the most extensive known gene family of nicotinic acetylcholine receptor (nAChR)-like subunits. Whilst all show greatest similarity with nAChR subunits of both invertebrates and vertebrates, phylogenetic analysis suggests that just over half of these (32) may represent other members of the cys-loop ligand-gated ion channel superfamily. We have introduced a novel nomenclature system for these "Orphan" subunits, designating them as lgc genes (ligand-gated ion channels of the cys-loop superfamily), which can also be applied in future to unnamed and uncharacterised members of the cys-loop ligand-gated ion channel superfamily. We present here the resulting updated version of the C. elegans nAChR gene family and related ligand-gated ion channel genes.

Tu YH et al. (2018) Science "An evolutionarily conserved gene family encodes proton-selective ion channels."

Teng B, Chang RB, Ye W, Turner HN, Mulhall EM, Smith AD, Tu YH, Artiga DJ, Cooper AJ, Liman ER

[Science, 2018]

Ion channels form the basis for cellular electrical signaling. Despite the scores of genetically identified ion channels selective for other monatomic ions, only one type of proton-selective ion channel has been found in eukaryotic cells. By comparative transcriptome analysis of mouse taste receptor cells, we identified Otopetrin1 (OTOP1), a protein required for development of gravity-sensing otoconia in the vestibular system, as forming a proton-selective ion channel. We found that murine OTOP1 is enriched in acid-detecting taste receptor cells and is required for their zinc-sensitive proton conductance. Two related murine genes, <i>Otop2</i> and <i>Otop3</i>, and a <i>Drosophila</i> ortholog also encode proton channels. Evolutionary conservation of the gene family and its widespread tissue distribution suggest a broad role for proton channels in physiology and pathophysiology.

Milani, M et al. (2005) Scanning "Read-out of soft X-ray contact microscopy microradiographs by focused ion beam/scanning electron microscope."

Zrimec, A, Drobne, D, Tatti, F, Batani, D, Orsini, F, Poletti, G, Zullini, A, Milani, M

[Scanning, 2005]

A novel focused ion beam-based technique is presented for the read-out of microradiographs of Caenorhabditis elegans nematodes generated by soft x-ray contact microscopy (SXCM). In previous studies, the read-out was performed by atomic force microscopy (AFM), but in our work SXCM microradiographs were imaged by scanning ion microscopy (SIM) in a focused ion beam/scanning electron microscope (FIB/SEM). It allows an ad libitum selection of a sample region for gross morphologic to nanometric investigations, with a sequence of imaging and cutting. The FIB/SEM is less sensitive to height variation of the relief, and sectioning makes it possible to analyse the sample further. The SXCM can be coupled to SIM in a more efficient and faster way than to AFM. Scanning ion microscopy is the method of choice for the read-out of microradiographs of small multicellular organisms.

Yamanashi T et al. (2019) Sci Rep "Quantitation of the neural silencing activity of anion channelrhodopsins in Caenorhabditis elegans and their applicability for long-term illumination."

Tsukamoto T, Kojima K, Yamanaka A, Shibukawa A, Maki M, Sudo Y, Yamanashi T, Takagi S, Chowdhury S

[Sci Rep, 2019]

Ion pumps and channels are responsible for a wide variety of biological functions. Ion pumps transport only one ion during each stimulus-dependent reaction cycle, whereas ion channels conduct a large number of ions during each cycle. Ion pumping rhodopsins such as archaerhodopsin-3 (Arch) are often utilized as light-dependent neural silencers in animals, but they require a high-density light illumination of around 1mW/mm². Recently, anion channelrhodopsins -1 and -2 (GtACR1 and GtACR2) were discovered as light-gated anion channels from the cryptophyte algae Guillardia theta. GtACRs are therefore expected to silence neural activity much more efficiently than Arch. In this study, we successfully expressed GtACRs in neurons of the nematode Caenorhabditis elegans (C. elegans) and quantitatively evaluated how potently GtACRs can silence neurons in freely moving C. elegans. The results showed that the light intensity required for GtACRs to cause locomotion paralysis was around 1W/mm², which is three orders of magnitude smaller than the light intensity required for Arch. As attractive features, GtACRs are less harmfulness to worms and allow stable neural silencing effects under long-term illumination. Our findings thus demonstrate that GtACRs possess a hypersensitive neural silencing activity in C. elegans and are promising tools for long-term neural silencing.