K Omata et al. (1999) International C. elegans Meeting "Characterization of the neural circuit of C. elegans: model analysis of the touch response"

F Yonezawa, K Omata, K Kawamura

[International C. elegans Meeting, 1999]

In order to characterize the neural circuit of C. elagans, we construct a simple model by making use of the data table completed recently by Oshio et al . [1]. We assume that the signal of a neuron is calculated by the product of the signals from the neighboring neurons, and we investigate the touch sensitivity to continuous stimuli described by sinusoidal functions as defined in the rage from 0.0 to 1.0. We calculate the responses of the motor neurons by changing the frequencies of the stimuli. In our calculations, we change only the frequency w PLM for the input signal to the sensory neuron PLM, while the frequency for the other sensory neurons ALM, AVM and PVM is fixed to be a same value w 0 . We show that the output signals from the motor neurons A and B oscillate in time. We measure the minima of the oscillation for each w PLM value. The plot of the minima versus w PLM shows different hehaviors for the case of the neuron A and B. As for the signals from the neuron A, the values of the minima are widely distributed between 0.0 and 1.0 for all w PLM . As for the signals from the neuron B, on the other hand, the features are different for different w PLM values. (a) In the high frequency region of w PLM / w 0 0.4, the oscillation is simple harmonic and there exists only one minimum value (I min = 0.0). (b) As w PLM / w 0 is decreased, another minimum appears at a certain frequency, and the bifurcation takes place discontinuously. This behavior is different from usual continuous bifurcation observed in nonlinear systems. After a few discontinuous branching occur, signals with five periods can be seen in the intermediate frequency region of 0.3 w PLM / w 0 w PLM / w 0 [1] K. Oshio et al. ; C. elegans synaptic connectivity data'', Technical Report, CCEP, Keio Future No.1 (1998).

Leon-Guerrero, Victoria et al. (2021) International Worm Meeting "Characterization of a third SHC adaptor protein in Caenorhabditis elegans"

Hardy, W. Rod, Di Bernardo, Mercedes, Leon-Guerrero, Victoria, MacNeil, Lesley T.

[International Worm Meeting, 2021]

SHC proteins are a family of adaptor proteins that play an important role in signal transduction, they are characterized by three crucial domains: the phosphotyrosine binding (PTB) domain, a Src2 homology (SH2) domain and a less conserved collagen homolog (CH1) domain. Two Caenorhabditis elegans SHC proteins have been described: SHC-1 and SHC-2. We have identified a third SHC protein, K11E4.2, that is intestinally expressed. Our analysis revealed that K11E4.2 null mutant animals suffer from a diet-dependent change in fat accumulation and increased sensitivity to starvation and oxidative stress. C. elegans shc-1 plays a role in stress response and lifespan regulation through the insulin signaling pathway. Our data suggest that shc-1 and K11E4.2 do not act redundantly to regulate stress or starvation response, but rather each plays a distinct role in these processes.

Ransom D et al. (1995) International C. elegans Meeting "DISRUPTIVE MYOSIN HEADS"

De Stasio E, Ransom D, Sharp S, Alberico C

[International C. elegans Meeting, 1995]

smg-dependent dominant alleles of unc-54 are hypothesized to produce truncations of myosin head domains responsible for disrupted muscle organization. Our goal is to test this hypothesis. We used PCR-directed mutagenesis to create successive stop codons at specific sites in the myosin head domain. Sites chosen include the head/rod junction, the carboyx-terminal end of a highly conserved domain at amino acid 519, and amino acid 417 which mimics a non-dominant unc-54 null allele (negative control). PCR products were cloned into a low copy vector which lacks rod-encoding sequences.

Christian E Rocheleau et al. (2005) International Worm Meeting "UBC-25 promotes Ras mediated excretory duct cell fate specification"

Christian E Rocheleau, Kevin Cullison, Yelena Bernstein, Meera V Sundaram

[International Worm Meeting, 2005]

cnk-1 encodes a putative adaptor/scaffold for the Ras pathway that promotes the LIN-45 Raf activation. Mutations in cnk-1 do not display Ras phenotypes, but display strong synergistic phenotypes in a sensitized genetic background in which Ras signaling is partially compromised. For example, cnk-1 mutations enhance the rod-like larval lethal phenotype of ksr-1 from <1% to >90%. To understand how CNK-1 promotes LIN-45 Raf activation we want to identify additional factors that function with CNK-1. Genes that strongly enhance the rod-like larval lethality of ksr-1 will be candidates for functioning with cnk-1. We identified ubc-25 in a RNAi screen for enhancers of ksr-1 rod-like lethality (see abstract by Rocheleau et al). ubc-25(RNAi); ksr-1 animals resemble let-60 ras mutations in that the excretory duct cell is absent as determined with a GFP marker. ubc-25 encodes a putative ubiquitin conjugating enzyme. We recently obtained two deletion alleles of ubc-25. Like cnk-1, the ubc-25 deletions do not display any Ras phenotypes, but strongly enhance the rod-like lethality of ksr-1. We are using these ubc-25 deletions to genetically characterize the role of ubc-25 in Ras signaling and determine if ubc-25 functions closely with cnk-1 or at another step of the pathway.

Craig Stone et al. (2006) Development & Evolution Meeting "Novel Genes required in Ras-mediated Development and/or Function of the Excretory System"

Meera Sundaram, Craig Stone

[Development & Evolution Meeting, 2006]

Ras signaling is critical for normal development and growth, and is implicated in many forms of human cancer. In C. elegans, Ras signaling is responsible for development of the excretory duct cell, vulva, and other tissues. Animals who lack the duct cell fill up with fluid and die with a distinct rod-like phenotype during the L1 stage. To find additional genes that act in the duct cell, I performed an EMS mutagenesis screen for rod-like lethal mutants. Two such mutants, cs73 and mls-2, correspond to genes with no prior known role in the Ras pathway. cs73 has highly penetrant rod-like lethality. It maps near bli-3 on the left arm of chromosome I. The lethality is suppressed by both a Ras (let-60) gain-of-function mutant, as well an Ets (lin-1) loss-of function mutant, suggesting that cs73 acts upstream of Ras. Interestingly, cs73 rod-like larvae have the duct cell, but have short and fluid-filled excretory canals. This defect is rescued in the cs73; let-60(gf) double-mutant, indicating a potential novel role for Ras signaling in excretory cell morphogenesis and/or function. cs73 may also act in the vulva in addition to the excretory cell, as it and another allele of this gene suppress the muv phenotype of lin-1(e1275). These data seemingly contradict the epistasis data for rod-like lethality, in which cs73 appears to act upstream of let-60. Our current thinking is that this gene functions in parallel with let-60 at the level of lin-1. mls-2 is a homeobox domain transcription factor with a known role in fate specification M lineage derived cells (Jiang et al., 05). mls-2 has weak rod-like lethality, which is enhanced by hypomorphic alleles of Ras pathway genes. These data suggest that mls-2 positively regulates Ras signaling output. The majority of mls-2 L1 rods lack the duct cell. Similar to cs73 mutants, fluid-filled mls-2 L1 larvae also contain short, fluid-filled excretory canals. However, the exact cause of lethality in both cs73 and mls-2 has yet to be resolved.

Ishmail Abdus-Saboor et al. (2008) Development & Evolution Meeting "MLS-2 Functions with Ras Signaling to Promote the Excretory Duct Cell Fate"

Ishmail Abdus-Saboor, Craig Stone, Meera Sundaram

[Development & Evolution Meeting, 2008]

The Ras-stimulated Raf-Mek-Erk kinase cascade is used repeatedly during development to control the specification of multiple cell fates. In C.elegans, Ras is required for organismal viability and the specification of multiple cell types, one of which is the excretory duct cell. The excretory duct cell is one of four critical cells in the simple renal system of C.elegans. Animals lacking the duct cell fill up with fluid and die in the first larval stage with a rod-like morphology.Though the core constituents of the Ras pathway are known, factors acting downstream of Ras signaling to promote the specification of distinct cell types are largely unknown. To identify factors that promote the duct cell fate we performed an EMS mutagenesis screen for rod-like lethal mutants. In this screen we identified an allele of the homeodomain transcription factor MLS-2. Approximately 15% of mls-2mutants lack an excretory duct, as assessed via rod-like lethality and an excretory duct cell marker. Additionally, the mls-2 mutation enhances the rod-like lethality of various Ras pathway mutants. Genetic epistasis data place mls-2 downstream or in parallel to the LIN-1 ETS transcription factor, which is itself a target of Ras signaling. Preliminary expression data generated via Pmls-2MLS-2::GFP and an MLS-2 antibody suggest that MLS-2 is expressed in the duct cell at the time of its specification. These data are consistent with MLS-2 being a novel target of the Ras pathway or alternatively in a parallel pathway to promote the duct cell fate.

Kyunghee Koh et al. (2002) East Coast Worm Meeting "A screen for suppressors of rod-like lethality of lin-1 eor-1 double mutants"

Meera Sundaram, Kyunghee Koh

[East Coast Worm Meeting, 2002]

Ras/MAPK signaling pathway regulates several aspects of C. elegans development, including development of the excretory system and the vulva. Loss or reduction of ras-mediated signaling input causes rod-like larval lethality or a vulvaless phenotype. In an attempt to identify new components of Ras signaling pathway, we have initiated a genetic screen for suppressors of rod-like lethality of lin-1 eor-1 double mutants. lin-1 encodes an ETS transcription factor and is best known for its negative role in Ras signaling pathway as evidenced by a multi-vulva phenotype in loss-of-function mutants. eor-1 encodes a BTB/Zinc finger protein, similar to human promyelocytic leukemia zinc finger protein (hPLZF), and has a positive role in Ras signaling. 1 eor-1 was identified in a genetic screen for enhancers of a weak lin-45 raf mutation, and loss-of-function mutations result in a low percentage of egg-laying defects and rod-like lethality.2 Surprisingly, lin-1 eor-1 double mutants show fully-penetrant rod-like larval lethality, suggesting lin-1 may have a positive role in Ras-mediated signal transduction.1 We mutagenized a strain of lin-1(e1275) eor-1(cs28) double mutants rescued for lethality by a wild-type eor-1 transgene. In our initial screens of approximately 1500 EMS mutagenized genomes, we have isolated three candidate suppressors of lin-1 eor-1 lethality. cs56 V is a dominant suppressor: heterozygous cs56 worms survive in lin-1(e1275) eor-1(cs28) background, and homozygotes in lin-1(+) eor-1(+) background either arrest as late larvae or become sterile adults. cs57 IV is a recessive suppressor, and is linked to lin-1 and eor-1: its phenontype in lin-1(+) eor-1(+) background has not yet been determined. cs58 IV is a dominant suppressor: heterozygous cs58 worms survive in lin-1(e1275) eor-1(cs28) background, and cs58 lin-1(e1275) eor-1(cs28) triple mutants arrest as lumpy, non-rod-like L2-stage larvae. Further characterization and cloning of these mutations are underway.

Pamela E Hoppe et al. (2002) Mid-west Worm Meeting "Differential requirement for the myosin rod and nonhelical tailpiece in body wall muscle"

Payal D Parikh, Rebecca C Andrews, Pamela E Hoppe

[Mid-west Worm Meeting, 2002]

Myosin heavy chain (MHC) is a large, multi-domain protein important for both cellular structure and contraction. To examine the functional role of two C-terminal domains, the end of the coiled-coil rod and the nonhelical tailpiece, we have generated C-terminally truncated MHC constructs and examined their behavior in C. elegans striated muscle. Genetic tests demonstrate that MHC lacking only tailpiece residues is competent to support the timely onset of embryonic contractions, and therefore viability, in animals lacking full-length MHC. Antibody staining experiments show that this truncated molecule localizes as wild type in early stages of development, but may be defective in processes important for thick filament organization later in embryogenesis. Ultrastructural analysis reveals thick filaments of normal morphology in disorganized arrangement, as well as occasional abnormal assemblages. In contrast, truncated molecules lacking both the tailpiece and four residues of coiled coil fail to rescue animals lacking endogenous MHC, and exhibit delayed localization and delayed function during early embryogenesis. Thus, even small deletions within the rod C-terminus severely disrupt early assembly events in vivo. Our results suggest that these two MHC domains, the rod and the tailpiece, are required for distinct steps during muscle development.

Mantilla Galindo, Alejandra et al. (2021) International Worm Meeting "Evaluacion del efecto del extracto etanolico de Witheringia coccoloboides sobre agregados de alpha- sinucleína en la cepa NL5901 de Caenorhabditis elegans"

Mantilla Galindo, Alejandra, Sanchez Mora, Ruth Melida, Gonzalez Devia, Johanna Lizeth, Hidalgo Pulido, Karen Lorena

[International Worm Meeting, 2021]

Neurodegenerative diseases (ND) are a public health problem, cause permanent disability and a high cost in health systems. People affected with Parkinson disease have protein deposits of alpha-synuclein (alpha-syn) in brain cells. The use of biological models such as Caenorhabditis elegans (C. elegans) can answer questions that arise day by day for the development of new therapeutic targets for ND. The transgenic strain NL5901 of C. elegans is characterized to have alpha-syn aggregates labeled with yellow fluorescent protein (YFP), which allows to evaluate compounds effect on the physiological characteristics and / or the reduction of protein aggregates alpha-syn in this model. On the other hand, Witheringia coccoloboides (W. coccoloboides) has been described as a promising plant in the palliative treatment of ND and therefore of interest in ethnopharmacology due to its possible neuroprotective action. Therefore, the main objective of this study was to evaluate the effect of the ethanolic extract of leaves of W. coccoloboides on the physiological characteristics and protein aggregates of alpha-syn in the mutant strain NL5901 of C. elegans. The results of the present work show that the ethanolic extract of leaves of W. coccoloboides has a reducing effect of protein aggregates alpha-syn, improving the physiological characteristics of reproduction and motility, as well as, decreasing the levels of Reactive Oxygen Species (ROS) in strain NL5901 of C. elegans. Therefore, it is possible to suggest that the ethanolic extract of leaves of W. coccoloboides has a protective effect on strain NL5901 of C. elegans, probably attributed to the presence of sterols and / or terpenes, flavonoids and alkaloids, which in turn, it is generate a recovery of muscular activity in the egg lay and locomotion, probably all linked, to synergistic interaction of the phytocompounds present in the ethanolic extract of leaves of W. Coccoloboides. Keywords: Witheringia coccoloboides, alpha-synuclein, Parkinson disease, Caenorhabditis elegans

Christian E Rocheleau et al. (2005) International Worm Meeting "Chromatin remodeling and RISC-like complexes cooperate with Ras signaling to specify the excretory duct cell fate"

Meera V Sundaram, Christian E Rocheleau, Yelena Bernstein

[International Worm Meeting, 2005]

Ras signaling is required for multiple cell fate decisions during C. elegans development including specification of the excretory duct cell. Strong mutations in let-60 ras result in a distinct rod-like larval lethal phenotype due to a loss of the excretory duct cell. Mutations in Ras pathway scaffolds ksr-1 and ksr-2 display little or no rod-like lethality (<1%), but ksr-2; ksr-1 double mutants display >90% rod-like larval lethal phenotype. To identify positive regulators of Ras signaling, we are performing a RNAi screen for enhancers of ksr-1 rod-like lethality (ekls). Based on their molecular identities, most of the ekls fall into two functional groups. The first group are components of a chromatin remodeling complex; some of these are Synmuv genes that antagonize Ras signaling during vulval cell fate specification. The second group are either required for RNAi or related to genes required for RNAi; these include an Argonaute, a RNA-directed RNA Polymerase, and a Dicer-related helicase. Interestingly, one of the chromatin remodeling complex components is also required for RNAi suggesting that both groups function together to promote Ras signaling during excretory duct cell fate specification. The RISC-like complex may be distinct from that required for RNAi or miRNA function as a number of genes required for these processes are not ekl genes. The ekls may be promoting Ras signaling by affecting the chromatin state (and hence transcription) of genes in the Ras pathway or genes that are transcriptional targets of the Ras pathway. ksr-2 is an excellent candidate target because, like all the ekls tested, ksr-2 strongly enhances ksr-1 mutants, but not mutations in other components of the Ras pathway. However, this would imply that the RISC-like complex is positively regulating ksr-2.