Lysosomal and pseudocoelom routing protects Caenorhabditis elegans from ricin toxicity

Nematology ◽  
2003 ◽  
Vol 5 (3) ◽  
pp. 339-350 ◽  
Author(s):  
August Coomans ◽  
Myriam Claeys ◽  
Gaëtan Borgonie ◽  
Christopher Link
Keyword(s):  
Caenorhabditis Elegans ◽  
Intestinal Cells ◽  
Progeny Production ◽  
Nematode Caenorhabditis Elegans ◽  
Surface Receptors ◽  
C Elegans ◽  
Transmission Electron ◽  
A Chain ◽  
Golgi Network ◽  
Ricin A

AbstractThe resistance of the nematode Caenorhabditis elegans towards the highly potent toxin ricin has been studied. Incubation of C. elegans in ricin did not affect life span or progeny production. However, micro-injection of the ricin A-chain into the distal, syncitial gonad caused degeneration and sterility in test specimens, confirming that C. elegans ribosomes are sensitive. Using transmission electron microscopy, it was observed that ricin is effectively internalised into the intestinal cells. When pre-labelled with gold, the toxin reached only the lysosomes. When native toxin was used, the toxin was either routed to the lysosomes or underwent transcytosis to the pseudocoelomatic cavity and incorporation into embryos. None of the ricin reached either the trans Golgi network or the Golgi apparatus, considered essential for toxicity. The observed oral non-toxicity is therefore due to alternate sorting of the toxin, a mechanism not previously observed. The data indicate that, although ricin can opportunistically bind to, and be internalised by, cell surface receptors, these receptors are not sufficient to elicit toxicity.

scholarly journals Sperm Competition in the Absence of Fertilization in Caenorhabditis elegans

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 201-208 ◽  
Author(s):  
Andrew Singson ◽  
Katherine L Hill ◽  
Steven W L’Hernault
Keyword(s):  
Caenorhabditis Elegans ◽  
Sperm Competition ◽  
Sperm Function ◽  
Sperm Precedence ◽  
Wild Type ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Normal Sperm ◽  
Self Fertilization ◽  
Competition Assays

Abstract Hermaphrodite self-fertilization is the primary mode of reproduction in the nematode Caenorhabditis elegans. However, when a hermaphrodite is crossed with a male, nearly all of the oocytes are fertilized by male-derived sperm. This sperm precedence during reproduction is due to the competitive superiority of male-derived sperm and results in a functional suppression of hermaphrodite self-fertility. In this study, mutant males that inseminate fertilization-defective sperm were used to reveal that sperm competition within a hermaphrodite does not require successful fertilization. However, sperm competition does require normal sperm motility. Additionally, sperm competition is not an absolute process because oocytes not fertilized by male-derived sperm can sometimes be fertilized by hermaphrodite-derived sperm. These results indicate that outcrossed progeny result from a wild-type cross because male-derived sperm are competitively superior and hermaphrodite-derived sperm become unavailable to oocytes. The sperm competition assays described in this study will be useful in further classifying the large number of currently identified mutations that alter sperm function and development in C. elegans.

scholarly journals Genetic, Behavioral and Environmental Determinants of Male Longevity in Caenorhabditis elegans

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1597-1610 ◽  
Author(s):  
David Gems ◽  
Donald L Riddle
Keyword(s):  
Caenorhabditis Elegans ◽  
Life Span ◽  
Wild Type ◽  
Neuronal Function ◽  
Nematode Caenorhabditis Elegans ◽  
Wild Isolate ◽  
Young Males ◽  
C Elegans ◽  
Single Sex ◽  
Solitary Males

Abstract Males of the nematode Caenorhabditis elegans are shorter lived than hermaphrodites when maintained in single-sex groups. We observed that groups of young males form clumps and that solitary males live longer, indicating that male-male interactions reduce life span. By contrast, grouped or isolated hermaphrodites exhibited the same longevity. In one wild isolate of C. elegans, AB2, there was evidence of copulation between males. Nine uncoordinated (unc) mutations were used to block clumping behavior. These mutations had little effect on hermaphrodite life span in most cases, yet many increased male longevity even beyond that of solitary wild-type males. In one case, the neuronal function mutant unc-64(e246), hermaphrodite life span was also increased by up to 60%. The longevity of unc-4(e120), unc-13(e51), and unc-32(e189) males exceeded that of hermaphrodites by 70–120%. This difference appears to reflect a difference in sex-specific life span potential revealed in the absence of male behavior that is detrimental to survival. The greater longevity of males appears not to be affected by daf-2, but is influenced by daf-16. In the absence of male-male interactions, median (but not maximum) male life span was variable. This variability was reduced when dead bacteria were used as food. Maintenance on dead bacteria extended both male and hermaphrodite longevity.

scholarly journals A genetic mapping system in Caenorhabditis elegans based on polymorphic sequence-tagged sites.

Genetics ◽  
1992 ◽  
Vol 131 (3) ◽  
pp. 609-624 ◽  
Author(s):  
B D Williams ◽  
B Schrank ◽  
C Huynh ◽  
R Shownkeen ◽  
R H Waterston
Keyword(s):  
Caenorhabditis Elegans ◽  
Genetic Mapping ◽  
Physical Map ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Sequence Tagged Sites ◽  
Mapping System ◽  
Polymerase Chain ◽  
Tc1 Element ◽  
Single Reaction

Abstract We devised an efficient genetic mapping system in the nematode Caenorhabditis elegans which is based upon the differences in number and location of the transposable element Tc1 between the Bristol and Bergerac strains. Using the nearly completed physical map of the C. elegans genome, we selected 40 widely distributed sites which contain a Tc1 element in the Bergerac strain, but not in the Bristol strain. For each site a polymerase chain reaction assay was designed that can distinguish between the Bergerac Tc1-containing site and the Bristol "empty" site. By combining appropriate assays in a single reaction, one can score multiple sites within single worms. This permits a mutation to be rapidly mapped, first to a linkage group and then to a chromosomal subregion, through analysis of only a small number of progeny from a single interstrain cross.

scholarly journals Specific collagens maintain the cuticle permeability barrier in Caenorhabditis elegans

Genetics ◽  
2021 ◽  
Author(s):  
Anjali Sandhu ◽  
Divakar Badal ◽  
Riya Sheokand ◽  
Shalini Tyagi ◽  
Varsha Singh
Keyword(s):  
Transcription Factor ◽  
Caenorhabditis Elegans ◽  
Barrier Function ◽  
Permeability Barrier ◽  
Nematode Caenorhabditis Elegans ◽  
Zinc Finger Transcription Factor ◽  
Outermost Layer ◽  
C Elegans ◽  
Receptor Mutant ◽  
Antioxidant Machinery

Abstract Collagen enriched cuticle forms the outermost layer of skin in nematode Caenorhabditis elegans. The nematode’s genome encodes 177 collagens, but little is known about their role in maintaining the structure or barrier function of the cuticle. In this study, we found six permeability determining (PD) collagens. Loss of any of these PD collagens- DPY-2, DPY-3, DPY-7, DPY-8, DPY-9, and DPY-10- led to enhanced susceptibility of nematodes to paraquat (PQ) and antihelminthic drugs levamisole and ivermectin. Upon exposure to paraquat, PD collagen mutants accumulated more PQ and incurred more damage and death despite the robust activation of antioxidant machinery. We find that BLMP-1, a zinc finger transcription factor, maintains the barrier function of the cuticle by regulating the expression of PD collagens. We show that the permeability barrier maintained by PD collagens acts in parallel to FOXO transcription factor DAF-16 to enhance survival of insulin-like receptor mutant, daf-2. In all, this study shows that PD collagens regulate cuticle permeability by maintaining the structure of C. elegans cuticle and thus provide protection against exogenous toxins.

scholarly journals Microtubules and microtubule-associated proteins from the nematode Caenorhabditis elegans: periodic cross-links connect microtubules in vitro.

1986 ◽  
Vol 103 (1) ◽  
pp. 23-31 ◽  
Author(s):  
E J Aamodt ◽  
J G Culotti
Keyword(s):  
Caenorhabditis Elegans ◽  
Apparent Molecular Weight ◽  
Cross Link ◽  
Nematode Caenorhabditis Elegans ◽  
Microtubule Associated Proteins ◽  
C Elegans ◽  
Associated Proteins ◽  
Cross Links ◽  
The Cross

The nematode Caenorhabditis elegans should be an excellent model system in which to study the role of microtubules in mitosis, embryogenesis, morphogenesis, and nerve function. It may be studied by the use of biochemical, genetic, molecular biological, and cell biological approaches. We have purified microtubules and microtubule-associated proteins (MAPs) from C. elegans by the use of the anti-tumor drug taxol (Vallee, R. B., 1982, J. Cell Biol., 92:435-44). Approximately 0.2 mg of microtubules and 0.03 mg of MAPs were isolated from each gram of C. elegans. The C. elegans microtubules were smaller in diameter than bovine microtubules assembled in vitro in the same buffer. They contained primarily 9-11 protofilaments, while the bovine microtubules contained 13 protofilaments. The principal MAP had an apparent molecular weight of 32,000 and the minor MAPs were 30,000, 45,000, 47,000, 50,000, 57,000, and 100,000-110,000 mol wt as determined by SDS-gel electrophoresis. The microtubules were observed, by electron microscopy of negatively stained preparations, to be connected by stretches of highly periodic cross-links. The cross-links connected the adjacent protofilaments of aligned microtubules, and occurred at a frequency of one cross-link every 7.7 +/- 0.9 nm, or one cross-link per tubulin dimer along the protofilament. The cross-links were removed when the MAPs were extracted from the microtubules with 0.4 M NaCl. The cross-links then re-formed when the microtubules and the MAPs were recombined in a low salt buffer. These results strongly suggest that the cross-links are composed of MAPs.

lag-1, a gene required for lin-12 and glp-1 signaling in Caenorhabditis elegans, is homologous to human CBF1 and Drosophila Su(H)

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1373-1383 ◽  
Author(s):  
S. Christensen ◽  
V. Kodoyianni ◽  
M. Bosenberg ◽  
L. Friedman ◽  
J. Kimble
Keyword(s):  
Caenorhabditis Elegans ◽  
Binding Sites ◽  
Feedback Loop ◽  
Target Genes ◽  
Sequence Similarity ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Downstream Target ◽  
Binding Factor ◽  
Flanking Regions

The homologous receptors LIN-12 and GLP-1 mediate diverse cell-signaling events during development of the nematode Caenorhabditis elegans. These two receptors appear to be functionally interchangeable and have sequence similarity to Drosophila Notch. Here we focus on a molecular analysis of the lag-1 gene (lin-12 -and glp-1), which plays a central role in LIN-12 and GLP-1-mediated signal transduction. We find that the predicted LAG-1 protein is homologous to two DNA-binding proteins: human C Promoter Binding Factor (CBF1) and Drosophila Suppressor of Hairless (Su(H)). Furthermore, we show that LAG-1 binds specifically to the DNA sequence RTGGGAA, previously identified as a CBF-1/Su(H)-binding site. Finally, we report that the 5′ flanking regions and first introns of the lin-12, glp-1 and lag-1 genes are enriched for potential LAG-1-binding sites. We propose that LAG-1 is a transcriptional regulator that serves as a primary link between the LIN-12 and GLP-1 receptors and downstream target genes in C. elegans. In addition, we propose that LAG-1 may be a key component of a positive feedback loop that amplifies activity of the LIN-12/GLP-1 pathway.

scholarly journals A novel member of the GCN5-related N-acetyltransferase superfamily from Caenorhabditis elegans preferentially catalyses the N-acetylation of thialysine [S-(2-aminoethyl)-L-cysteine]

2004 ◽  
Vol 384 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Benjamin ABO-DALO ◽  
Dieudonne NDJONKA ◽  
Francesco PINNEN ◽  
Eva LIEBAU ◽  
Kai LÜERSEN
Keyword(s):  
Caenorhabditis Elegans ◽  
Reversed Phase ◽  
Open Reading Frame ◽  
Side Chain ◽  
Homologous Gene ◽  
Reversed Phase Hplc ◽  
Nematode Caenorhabditis Elegans ◽  
Reading Frame ◽  
Considerable Similarity ◽  
C Elegans

The putative diamine N-acetyltransferase D2023.4 has been cloned from the model nematode Caenorhabditis elegans. The 483 bp open reading frame of the cDNA encodes a deduced polypeptide of 18.6 kDa. Accordingly, the recombinantly expressed His6-tagged protein forms an enzymically active homodimer with a molecular mass of approx. 44000 Da. The protein belongs to the GNAT (GCN5-related N-acetyltransferase) superfamily, and its amino acid sequence exhibits considerable similarity to mammalian spermidine/spermine-N1-acetyltransferases. However, neither the polyamines spermidine and spermine nor the diamines putrescine and cadaverine were efficiently acetylated by the protein. The smaller diamines diaminopropane and ethylenediamine, as well as L-lysine, represent better substrates, but, surprisingly, the enzyme most efficiently catalyses the N-acetylation of amino acids analogous with L-lysine. As determined by the kcat/Km values, the C. elegans N-acetyltransferase prefers thialysine [S-(2-aminoethyl)-L-cysteine], followed by O-(2-aminoethyl)-L-serine and S-(2-aminoethyl)-D,L-homocysteine. Reversed-phase HPLC and mass spectrometric analyses revealed that N-acetylation of L-lysine and L-thialysine occurs exclusively at the amino moiety of the side chain. Remarkably, heterologous expression of C. elegans N-acetyltransferase D2023.4 in Escherichia coli, which does not possess a homologous gene, results in a pronounced resistance against the anti-metabolite thialysine. Furthermore, C. elegans N-acetyltransferase D2023.4 exhibits the highest homology with a number of GNATs found in numerous genomes from bacteria to mammals that have not been biochemically characterized so far, suggesting a novel group of GNAT enzymes closely related to spermidine/spermine-N1-acetyltransferase, but with a distinct substrate specificity. Taken together, we propose to name the enzyme ‘thialysine Nε-acetyltransferase’.

scholarly journals Isolation, characterization and epistasis of fluoride-resistant mutants of Caenorhabditis elegans.

Genetics ◽  
1994 ◽  
Vol 136 (1) ◽  
pp. 145-154
Author(s):  
I Katsura ◽  
K Kondo ◽  
T Amano ◽  
T Ishihara ◽  
M Kawakami
Keyword(s):  
Caenorhabditis Elegans ◽  
Brood Size ◽  
Normal Growth ◽  
Fluoride Ion ◽  
Wild Type ◽  
Signal Transduction System ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Class 1 ◽  
Resistant Mutants

Abstract We have isolated 13 fluoride-resistant mutants of the nematode Caenorhabditis elegans. All the mutations are recessive and mapped to five genes. Mutants in three of the genes (class 1 genes: flr-1 X, flr-3 IV, and flr-4 X) are resistant to 400 micrograms/ml NaF. Furthermore, they grow twice as slowly as and have smaller brood size than wild-type worms even in the absence of fluoride ion. In contrast, mutants in the other two genes (class 2 genes: flr-2 V and flr-5 V) are only partially resistant to 400 micrograms/ml NaF, and they have almost normal growth rates and brood sizes in the absence of fluoride ion. Studies on the phenotypes of double mutants showed that class 2 mutations are epistatic to class 1 mutations concerning growth rate and brood size but hypostatic with respect to fluoride resistance. We propose two models that can explain the epistasis. Since fluoride ion depletes calcium ion, inhibits some protein phosphatases and activates trimeric G-proteins, studies on these mutants may lead to discovery of a new signal transduction system that controls the growth of C. elegans.

Broad oxygen tolerance in the nematode Caenorhabditis elegans

2000 ◽  
Vol 203 (16) ◽  
pp. 2467-2478 ◽  
Author(s):  
W.A. Van Voorhies ◽  
S. Ward
Keyword(s):  
Caenorhabditis Elegans ◽  
Metabolic Rate ◽  
Developmental Stages ◽  
Small Body ◽  
Metabolic Cost ◽  
Soil Nematode ◽  
Nematode Caenorhabditis Elegans ◽  
Oxygen Levels ◽  
C Elegans ◽  
Short Period

This study examined the effects of oxygen tensions ranging from 0 to 90 kPa on the metabolic rate (rate of carbon dioxide production), movement and survivorship of the free-living soil nematode Caenorhabditis elegans. C. elegans requires oxygen to develop and survive. However, it can maintain a normal metabolic rate at oxygen levels of 3.6 kPa and has near-normal metabolic rates at oxygen levels as low as 2 kPa. The ability to withstand low ambient oxygen levels appears to be a consequence of the small body size of C. elegans, which allows diffusion to supply oxygen readily to the cells without requiring any specialized respiratory or metabolic adaptations. Thus, the small size of this organism pre-adapts C. elegans to living in soil environments that commonly become hypoxic. Movement in C. elegans appears to have a relatively minor metabolic cost. Several developmental stages of C. elegans were able to withstand up to 24 h of anoxia without major mortality. Longer periods of anoxia significantly increased mortality, particularly for eggs. Remarkably, long-term exposure to 100 % oxygen had no effect on the metabolic rate of C. elegans, and populations were able to survive for a least 50 generations in 100 % (90 kPa) oxygen. Such hyperoxic conditions are fatal to most organisms within a short period.

scholarly journals Embryonic extracts derived from the nematode Caenorhabditis elegans remove uracil from DNA by the sequential action of uracil-DNA glycosylase and AP (apurinic/apyrimidinic) endonuclease

2002 ◽  
Vol 365 (2) ◽  
pp. 547-553 ◽  
Author(s):  
Andrea SHATILLA ◽  
Dindial RAMOTAR
Keyword(s):  
Caenorhabditis Elegans ◽  
Excision Repair ◽  
Specific Inhibitor ◽  
Dna Glycosylase ◽  
Dependent Manner ◽  
Nematode Caenorhabditis Elegans ◽  
Uracil Dna Glycosylase ◽  
Ap Endonuclease ◽  
C Elegans ◽  
Ap Site

DNA bases continuously undergo modifications in response to endogenous reactions such as oxidation, alkylation or deamination. The modified bases are primarily removed by DNA glycosylases, which cleave the N-glycosylic bond linking the base to the sugar, to generate an apurinic/apyrimidinic (AP) site, and this latter lesion is highly mutagenic. Previously, no study has demonstrated the processing of these lesions in the nematode Caenorhabditis elegans. Herein, we report the existence of uracil-DNA glycosylase and AP endonuclease activities in extracts derived from embryos of C. elegans. These enzyme activities were monitored using a defined 5′-end 32P-labelled 42-bp synthetic oligonucleotide substrate bearing a single uracil residue opposite guanine at position 21. The embryonic extract rapidly cleaved the substrate in a time-dependent manner to produce a 20-mer product. The extract did not excise adenine or thymine opposite guanine, although uracil opposite either adenine or thymine was processed. Addition of the highly specific inhibitor of uracil-DNA glycosylase produced by Bacillus subtilis to the extract prevented the formation of the 20-mer product, indicating that removal of uracil is catalysed by uracil-DNA glycosylase. The data suggest that the 20-mer product was generated by a sequential reaction, i.e., removal of the uracil base followed by 5′-cleavage of the AP site. Further analysis revealed that product formation was dependent upon the presence of Mg2+, suggesting that cleavage of the AP site, following uracil excision, is carried out by a Mg2+-dependent AP endonuclease. It would appear that these activities correspond to the first two steps of a putative base-excision-repair pathway in C. elegans.

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