Pellis-van Berkel W et al. (2005) Mol Biol Cell "Requirement of the Caenorhabditis elegans RapGEF pxf-1 and rap-1 for epithelial integrity."

Asahina M, Pellis-van Berkel W, Plasterk R H A, Cuppen E, Verheijen M H G, de Rooij J, Bos J L, Jansen G, Zwartkruis F J T

[Mol Biol Cell, 2005]

The Rap-pathway has been implicated in various cellular processes but its exact physiological function remains poorly defined. Here we show that the Caenorhabditis elegans homologue of the mammalian guanine nucleotide exchange factors PDZ-GEFs, PXF-1, specifically activates Rap1 and Rap2. Green fluorescent protein (GFP) reporter constructs demonstrate that sites of pxf-1 expression include the hypodermis and gut. Particularly striking is the oscillating expression of pxf-1 in the pharynx during the four larval molts. Deletion of the catalytic domain from pxf-1 leads to hypodermal defects, resulting in lethality. The cuticle secreted by pxf-1 mutants is disorganized and can often not be shed during molting. At later stages, hypodermal degeneration is seen and animals that reach adulthood frequently die with a burst vulva phenotype. Importantly, disruption of rap-1 leads to a similar, but less severe phenotype, which is enhanced by the simultaneous removal of rap-2. In addition, the lethal phenotype of pxf-1 can be rescued by expression of an activated version of rap-1. Together these results demonstrate that the pxf-1/rap pathway in C. elegans is required for maintenance of epithelial integrity, in which it probably functions in polarized secretion.

W van Berkel et al. (2001) International Worm Meeting "Genetic analysis of the Rap1-pathway in C. elegans."

R H A Plasterk, M H G Verheijen, G Jansen, J L Bos, W van Berkel, F J T Zwartkruis, J de Rooij

[International Worm Meeting, 2001]

The family of Ras-like GTPases functions in a diversity of signal transduction routes in which they transmit signals received by cell surface receptors to downstream effector molecules. Despite the high level of homology and conservation during evolution, the function of most Ras-like GTPases other than Ras remain poorly defined. This holds also for Rap1, for which functions have been claimed as diverse as antagonzing Ras, regulation of secretion and activation of integrins (1). As a first step in elucidating the function of Rap1in C. elegans, the expression patterns of the homologues of Rap1 (C27B7.8), the related Rap2 (C25D7.7) and of two of their guanine nucleotide exchange factors (GEFs) wer studied using GFP-reproter constructs. Rap1 appears to be expressed in various neurons in the head and tail, in the hypodermis and somatic cells of the gonad. Rap2 is also expressed in various neurons and in the pharynx. Of the tow Rap1-GEFs, pxf-1 (T14G10.2) is widely expressed, whereas the homologue of Epac (T20G5.5) is restrict to neurons in the head and ventral nerve cord. More recently we have begun to make trangenic animals overexpressing constitutively active and dominant negative versions of Rap1 and data from our first analysis of these transgenic animals will be presented. (1) Zwartkruis, F.J. and Bos, J.L. (1999) Ras and Rap1: two highly related small GTPases with distinct function. Exp Cell Res, 253, 157-165.

W van Berkel et al. (2002) European Worm Meeting "Genetic analysis of Ras-like GTPases in C. elegans"

W van Berkel, F J T Zwartkruis, J Riedl, J L Bos, G Jansen, M H G Verheijen, R H A Plasterk, J de Rooij

[European Worm Meeting, 2002]

GTPases from the Ras-like family, including Ras, Ral, Rap1, Rap2 and R-Ras, function as molecular switches in various signal transduction pathways. They have been highly conserved during evolution, but for most of these proteins their exact function has remained elusive. We have started a systematic approach to study all Ras-like GTPases in C. elegans.

W Pellis-van Berkel et al. (2004) European Worm Meeting "GENETIC INTERACTION BETWEEN THE RAP1 AND RAL PATHWAYS"

F Zwartkruis, J Bos, J Riedl, W Pellis-van Berkel, E Cuppen, T Paluch

[European Worm Meeting, 2004]

Ras-like GTPases function in a variety of signal transduction cascades, regulating cellular behavior in response to environmental cues. Its founding member Ras is involved in the control of proliferation and differentiation. Rap1 is a highly homologous GTPase, whose function is less well defined. Using tissue culture cells we have previously shown that Rap1 is activated by various second messengers and functions in the activation of integrins. However, the underlying mechanism remains unknown (1). Candidate effectors for Rap1 have been identified by virtue of their interaction with GTP-bound Rap1 and include guanine nucleotide exchange factors (GEFs) for Ral, a more distinct member of the Ras family. Although RalGEFs bind with high affinity to GTP-bound Rap1, biochemical studies show that Rap1 activation does not stimulate Ral-GEF/Ral activity. However, genetic studies in Drosophila do support a role for the RalGEF RGL as a Rap1 effector (2). Here we studied the relation between rap-1 and rgl-1/ral-1 (F28B4.2/Y53G8AR.3) in C.elegans. First, also the C.elegans homologue of RalGDS, RGL-1, can bind to RAP-1. To test the physiological significance of this interaction, we compared the phenotype of a rap-1 null mutant (see abstract by Zwartkruis et al.), with that of worms subjected to rgl-1 or ral-1 RNAi. In all cases a relatively subtle phenotype is seen in which larval development and especially molting appears delayed and a fraction of the adults die with a burst vulva phenotype. However, rap-1 mutants subjected to rgl-1 or ral-1 RNAi display a synthetic phenotype. This implies that rap-1 and rgl-1/ral-1 do not act in a simple linear pathway. The synthetic phenotype can be used to screen for additional elements of the rgl-1/ral-1 pathway by RNAi screens. The results of such an RNAi screen will be presented. 1. Bos et al. Nat. Rev. Mol. Biol. (2001) 2. Mirey et al. MCB 2003

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).

Wang C et al. (2018) Nat Commun "Author Correction: Small-molecule TFEB pathway agonists that ameliorate metabolic syndrome in mice and extend C. elegans lifespan."

Zhao T, Oswald NW, Li Y, Lin R, Wang C, Jaramillo J, Zhou A, McMillan EA, Douglas PM, MacMillan JB, Huang G, Luo M, Gao J, Mendiratta S, Lin Z, Wang Z, Niederstrasser H, Posner BA, Brekken RA, White MA

[Nat Commun, 2018]

The originally published version of this Article contained an error in the spelling of the author Nathaniel W. Oswald, which was incorrectly given as Nathaniel W. Olswald. This has now been corrected inboth the PDF and HTML versions of the Article.

Nawa Y et al. (1985) Parasite Immunol "Defective protective capacity of W/Wv mice against Strongyloides ratti infection and its reconstitution with bone marrow cells."

Kotani M, Nawa Y, Kiyota M, Korenaga M

[Parasite Immunol, 1985]

The susceptibility of congenitally anemic, and mast cell deficient W/Wv mice to infection with Strongyloides ratti was examined. After a primary infection, W/Wv mice showed greater and more persistent peak larval counts than did normal littermates. Worm expulsion was also slower in W/Wv mice than in +/+ mice. Furthermore, difference in susceptibility was expressed as early as 24 h after infection, suggesting not only that protective mechanisms of the gut but also of the connective tissue were defective in W/Wv mice. Reconstitution with bone marrow or spleen cells from +/+ mice was effective in restoring the protective response in W/Wv mice, whereas thymocytes or mesenteric lymph nodes had no effect. Both connective tissue and mucosal mast cells were repaired in W/Wv mice after marrow reconstitution and infection. Since relatively long incubation period was required for the expression of such reconstituting activities, bone marrow cells seem to contain precursor cells of the effector and/or regulator cells.

Sharma S et al. (2019) Int Microbiol "Lipidomic insights to understand membrane dynamics in response to vanillin in Mycobacterium smegmatis."

Sharma S, Fatima Z, Hameed S

[Int Microbiol, 2019]

Considering the emergence of multidrug resistance (MDR) in prevalent human pathogen, Mycobacterium tuberculosis (MTB), there is parallel spurt in development of novel strategies aimed to disrupt MDR. The cell envelope of MTB comprises a wealth of lipid moieties contributing towards long-term survival of pathogen that could be exploited as efficient antitubercular target owing to advancements made in mass spectrometry-based lipidomics technology. This study aimed to utilize the lipidomics approach to unveil several lipid associated changes in response to natural antimycobacterial compound vanillin (Van) in Mycobacterium smegmatis, a surrogate for MTB. Lipidomic analyses revealed that that Van alters the composition of fatty acid (FA), glycerolipid (GL), glycerophospholipid (GP), and saccharolipids (SL). Furthermore, Van leads to potentiation of ampicillin and displayed additive effect. The differential expressions of various lipid biosynthetic pathway genes by RT-PCR corroborated with the lipidomics data. Lastly, we demonstrated enhanced survival of Mycobacterium-infected Caenorhabditis elegans model in presence of Van. Thus, lipidomics approach provided detailed insight into mechanisms of membrane disruption by Van in Mycobacterium smegmatis. Our work offers the basis of further understanding the regulation of lipid homeostasis in MTB so that better therapeutic targets could be identified to combat MDR.

Casiraghi M et al. (2004) Int J Parasitol "Mapping the presence of Wolbachia pipientis on the phylogeny of filarial nematodes: evidence for symbiont loss during evolution."

Guerrero R, Bandi C, Franceschi A, Pocacqua V, Gardner SL, Casiraghi M, Martin C, Bain O

[Int J Parasitol, 2004]

Wolbachia pipientis is a bacterial endosymbiont associated with arthropods and filarial nematodes. In filarial nematodes, W. pipientis has been shown to play an important role in the biology of the host and in the immuno-pathology of filariasis. Several species of filariae, including the most important parasites of humans and animals (e.g. Onchocerca volvulus, Wuchereria bancrofti and Dirofilaria immitis) have been shown to harbour these bacteria. Other filarial species, including an important rodent species (Acanthocheilonema viteae), which has been used as a model for the study of filariasis, do not appear to harbour these symbionts. There are still several open questions about the distribution of W. pipientis in filarial nematodes. Firstly the number of species examined is still limited. Secondly, it is not clear whether the absence of W. pipientis in negative species could represent an ancestral characteristic or the result of a secondary loss. Thirdly, several aspects of the phylogeny of filarial nematodes are still unclear and it is thus difficult to overlay the presence/absence of W. pipientis on a tree representing filarial evolution. Here we present the results of a PCR screening for W. pipientis in 16 species of filariae and related nematodes, representing different families/subfamilies. Evidence for the presence of W. pipientis is reported for five species examined for the first time (representing the genera Litomosoides, Litomosa and Dipetalonema); original results on the absence of this bacterium are reported for nine species; for the remaining two species, we have confirmed the absence of W. pipientis recently reported by other authors. In the positive species, the infecting W. pipientis bacteria have been identified through 16S rDNA gene sequence analysis. In addition to the screening for W. pipientis in 16 species, we have generated phylogenetic reconstructions based on mitochondrial gene sequences (12S rDNA; COI), including a total of 28 filarial species and related spirurid nematodes. The mapping of the presence/absence of W. pipientis on the trees generated indicates that these bacteria have possibly been lost during evolution along some lineages of filarial nematodes.

Braeckman BP et al. (2002) Aging Cell "Rebuttal to Van Voorhies: 'the influence of metabolic rate on longevity in the nematode Caenorhabditis elegans'."

Braeckman BP, Houthoofd K, Vanfleteren JR

[Aging Cell, 2002]

The papers by Van Voorhies in Free Radical Biology & Medicine (33, 587-596, 2002) and in this journal claim that the major longevity-extending mutations in C. elegans essentially act by reducing metabolic rate as predicted by the rate-of-living theory, and do not alter any metabolically independent mechanism specific to aging. In contrast, we found no evidence of a reduction in metabolic rate in these mutants using different experimental approaches. Now, Van Voorhies challenges the accuracy of our experimental results.