Metabolites of Bacterial-Feeding Nematodes Stimulate Bacterial Indole-3-Acetic Acid (IAA) Synthesis

Abstract Interorganismal metabolites play significant roles in regulating behaviors and communications between organisms. Nematodes are the most abundant animals on earth, and function well in soil ecosystem due to their interactions with microbes. Bacterial-feeding nematodes stimulate the activity of indole-3-acetic acid (IAA)-producing bacteria and increase the content of IAA in soil. However, we do not fully understand how bacterial-feeding nematodes interact with bacteria and affect IAA synthesis. In this study, the model nematode Caenorhabditis elegans and three species of soil-dwelling IAA-producing bacteria ( Bacillus amyloliquefaciens JX1, Arthrobacter pascens ZZ21 and A. chlorphenolicus L4) were employed to determine the effect of nematodes on the IAA biosynthesis of bacteria. Then the metabolites and extracts of C. elegans were tested the effect on three bacterial IAA synthesis (but only A. pascens ZZ21 for the extracts). Lastly, two soil-dwelling bacterial-feeding nematodes ( Mesorhabditis sp. and Acrobeloides sp.) and two IAA-producing bacteria ( B. amyloliquefaciens JX1 and A. pascens ZZ21) were subsequently used to explore the universality of this interaction. Our results showed that the metabolites or extracts of nematodes could promote the IAA biosynthesis of IAA-producing bacteria, and implied this stimulatory effect maybe widely spread in metabolites of bacterial-feeding nematodes and IAA-producing bacteria, but vary with nematodes and bacteria species. Our findings indicate that bacterial-feeding nematodes could mediate the interaction between nematodes and bacteria by their metabolites, except for their feeding behavior, and offer insights into the ecological function of the metabolites of nematodes.

Download Full-text

Phylogenetic, expression, and functional analyses of anoctamin homologs in Caenorhabditis elegans

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00303.2012 ◽

2013 ◽

Vol 305 (11) ◽

pp. R1376-R1389 ◽

Cited By ~ 10

Author(s):

Ying Wang ◽

Tashrique Alam ◽

Katherine Hill-Harfe ◽

Alejandro J. Lopez ◽

Chi K. Leung ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Epithelial Transport ◽

Phylogenetic Analyses ◽

Membrane Excitability ◽

Nematode Caenorhabditis Elegans ◽

C Elegans ◽

Sensory Mode ◽

Sensory Cilia ◽

And Function ◽

Functional Analyses

Ca2+-activated Cl− channels (CaCCs) are critical to processes such as epithelial transport, membrane excitability, and signal transduction. Anoctamin, or TMEM16, is a family of 10 mammalian transmembrane proteins, 2 of which were recently shown to function as CaCCs. The functions of other family members have not been firmly established, and almost nothing is known about anoctamins in invertebrates. Therefore, we performed a phylogenetic analysis of anoctamins across the animal kingdom and examined the expression and function of anoctamins in the genetically tractable nematode Caenorhabditis elegans. Phylogenetic analyses support five anoctamin clades that are at least as old as the deuterostome/protosome ancestor. This includes a branch containing two Drosophila paralogs that group with mammalian ANO1 and ANO2, the two best characterized CaCCs. We identify two anoctamins in C. elegans (ANOH-1 and ANOH-2) that are also present in basal metazoans. The anoh-1 promoter is active in amphid sensory neurons that detect external chemical and nociceptive cues. Within amphid neurons, ANOH-1::GFP fusion protein is enriched within sensory cilia. RNA interference silencing of anoh-1 reduced avoidance of steep osmotic gradients without disrupting amphid cilia development, chemotaxis, or withdrawal from noxious stimuli, suggesting that ANOH-1 functions in a sensory mode-specific manner. The anoh-2 promoter is active in mechanoreceptive neurons and the spermatheca, but loss of anoh-2 had no effect on motility or brood size. Our study indicates that at least five anoctamin duplicates are evolutionarily ancient and suggests that sensory signaling may be a basal function of the anoctamin protein family.

Download Full-text

Sperm Competition in the Absence of Fertilization in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/152.1.201 ◽

1999 ◽

Vol 152 (1) ◽

pp. 201-208 ◽

Cited By ~ 2

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.

Download Full-text

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

Genetics ◽

10.1093/genetics/154.4.1597 ◽

2000 ◽

Vol 154 (4) ◽

pp. 1597-1610 ◽

Cited By ~ 1

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.

Download Full-text

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

Genetics ◽

10.1093/genetics/131.3.609 ◽

1992 ◽

Vol 131 (3) ◽

pp. 609-624 ◽

Cited By ~ 13

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.

Download Full-text

Specific collagens maintain the cuticle permeability barrier in Caenorhabditis elegans

Genetics ◽

10.1093/genetics/iyaa047 ◽

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.

Download Full-text

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

The Journal of Cell Biology ◽

10.1083/jcb.103.1.23 ◽

1986 ◽

Vol 103 (1) ◽

pp. 23-31 ◽

Cited By ~ 35

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.

Download Full-text

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 ◽

10.1242/dev.122.5.1373 ◽

1996 ◽

Vol 122 (5) ◽

pp. 1373-1383 ◽

Cited By ~ 12

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.

Download Full-text

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]

Biochemical Journal ◽

10.1042/bj20040789 ◽

2004 ◽

Vol 384 (1) ◽

pp. 129-137 ◽

Cited By ~ 13

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’.

Download Full-text

Highly Efficient Biosynthesis of Indole-3-acetic acid by Enterobacter xiangfangensis BHW6

10.21203/rs.3.rs-54635/v1 ◽

2020 ◽

Author(s):

Bi-Xian Zhang ◽

Ying-Ying Wang ◽

Xiaomei Hu

Keyword(s):

Acetic Acid ◽

Economic Value ◽

Pyruvate Decarboxylase ◽

Genomic Analysis ◽

Rrna Gene ◽

H Nmr ◽

Gene Coding ◽

Key Enzyme ◽

Indole 3 Acetic Acid ◽

Iaa Biosynthesis

Abstract Background: Indole-3-acetic acid (IAA) plays an important role in the growth and development of plants. Various bacteria in the rhizosphere are capable to produce IAA that acts as a signaling molecule for the communication between plants and microbes to promote the plant growth. Due to the low IAA content and various interfering analogs, it is difficult to detect and isolate IAA from microbial secondary metabolites. Results: A predominant strain with a remarkable capability to secrete IAA was identified as Enterobacter xiangfangensis BHW6 based on 16S rRNA gene sequence, the determination of average nucleotide identity (ANI) and digital DDH (dDDH). The maximum IAA content (134-1129 μg/mL) was found with the addition of 0.2-15 g/L of L-tryptophan at pH 5 for 6 days, which was 4-40 fold higher than that in the absence of L-tryptophan. The highest yield of IAA was obtained at the stationary phase of bacterial growth. An acidic culture medium was preferred for the IAA biosynthesis of the strain. The strain was tolerant and stable to produce IAA in the presence 2.5%-5% (w/v) of NaCl. IAA was then isolated through column chromatography with a mobile phase of hexane/ethyl acetate (1/2, v/v) and characterized by 1H Nuclear Magnetic Resonance (1H NMR). Conclusions: A remarkable IAA production was obtained from E. xiangfangensis BHW6 that was tryptophan–dependent. According to genomic analysis, the ipdC gene coding for the key enzyme (indole-3-pyruvate decarboxylase) was identified indicating that IAA biosynthesis was mainly through the indole-3-pyruvia acid (IPyA) pathway, which was further confirmed by intermediate assay. E. xiangfangensis BHW6 with an important economic value has great prospect in agricultural and industrial application.

Download Full-text

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

Genetics ◽

10.1093/genetics/136.1.145 ◽

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.

Download Full-text