Hoang, Hieu D. et al. (2011) International Worm Meeting "Identifying mechanisms critical for sperm guidance to oocytes."

Prasain, J., Miller, Michael A., Edmonds, Johnathan W., Hoang, Hieu D.

[International Worm Meeting, 2011]

Fertilization is dependent upon fusion of sperm and oocyte. The mechanism(s) by which motile sperm find oocytes within the female reproductive tract is not well understood. Our published data provide strong evidence that C. elegans oocytes secrete F-series prostaglandins that guide sperm to the spermatheca (Kubagawa et al., 2006; Edmonds et al., 2010). Prostaglandins (PGs) are lipid hormones that are targets of nonsteroidal anti-inflammatory drugs, such as aspirin and ibuprofen. Although PG synthesis pathways in mammals have been largely delineated, these pathways in worms are unexplored. The C. elegans genome lacks PG G/H synthase homologs, which catalyze the 1st step in PG synthesis, yet encodes a wide array of predicted PG D, E, and F synthases that act downstream. Our model is that PG synthesis in oocytes initiates by a novel mechanism that generates substrates for conserved PG synthases that in turn generate F-series PG analogs. Consistent with this model, we have identified several predicted PG synthases that are required non-autonomously for sperm guidance (Edmonds et al., 2010). We are using electrospray ionization tandem mass spectrometry, genetic analyses, and in vitro assays to identify roles for these enzymes in PG synthesis. Preliminary data suggest that worms express numerous PG synthases that are essential for synthesizing specific F-series PG types. These enzymes tend to be broadly expressed, raising the possibility that PGs have unknown functions outside of the reproductive system. Another important unanswered question is the mechanism(s) that transduces PG signals in C. elegans sperm, as the genome does not encode obvious homologs of mammalian PG receptors. We have identified mutations in multiple G-protein coupled receptors (GPCRs) that disrupt sperm guidance to the spermatheca. Our data support the hypothesis that these GPCRs function autonomously in sperm. The GPCRs are members of a multi-gene family that is clustered within a chromosomal region enriched in genes important for fertilization (Miller et al., 2004). Mutations in individual GPCRs cause incompletely penetrant defects in sperm guidance, suggesting that their functions partially overlap. We are testing this hypothesis by using the MosDEL transposon-mediated deletion strategy to knock out multiple GPCRs within the cluster. The results may help identify PG receptors in C. elegans.

Pidgeon SE et al. (2017) Bioconjug Chem "Cell Wall Remodeling of Staphylococcus aureus in Live C. elegans."

Pidgeon SE, Pires MM

[Bioconjug Chem, 2017]

Peptidoglycan (PG) scaffolds are critical components of bacterial cell walls. They counter internal turgor pressure to prevent lysis and protect against external insults. It was recently discovered that various types of bacteria release large quantities of PG building blocks (D-amino acids) into their surrounding medium. Cultured bacteria were also found to incorporate D-amino acids (both natural and synthetic) from the medium directly into their PG scaffold. Together, these two processes may potentially function, in concert, to metabolically remodel PG in live host organisms. Yet, demonstration that bacteria can decorate their cell surfaces with exogenous D-amino acids was limited to in vitro culture conditions. We present the first evidence that bacteria remodel their cell wall PG in a live host animal. A tetrazine click partner was conjugated onto the sidechain of a D-amino acid to capture incorporation into the bacterial PG scaffold using a complementary click-reactive fluorophore. Staphylococcus aureus infected Caenorhabditis elegans treated with exogenous D-amino acids readily revealed in vivo PG labeling. These results suggest that extracellular D-amino acids may provide pathogens with a mode of late-stage in vivo cell surface remodeling.

Xu HY et al. (2023) Plant Foods Hum Nutr "Anti-Oxidative and Anti-Aging Effects of Probiotic Fermented Ginseng by Modulating Gut Microbiota and Metabolites in Caenorhabditis elegans."

Zhou WJ, Gong SY, Xu HY, Peng N, Chen ZX, Zhang HB, Li QC, Liu B, Zeng F

[Plant Foods Hum Nutr, 2023]

Antioxidative and antiaging abilities of probiotic fermented ginseng (PG) were evaluated in Caenorhabditis elegans (C. elegans). Lifespan and effect on heat stress and acute oxidative stress in C. elegans were significantly enhanced by PG. Antioxidative enzymes such as T-SOD, GSH-PX, CAT were significantly up-regulated, and MDA, ROS and apoptosis levels were significantly down-regulated. At the same time, PG exerted antioxidant and anti-aging activities by reducing the expression of DAF-2 mRNA and increasing the expression of SKN-1 and SOD-3 mRNA in C. elegans. In addition, the mechanism of antioxidative and antiaging activities of PG was explored through gut microbiota sequencing and untargeted metabolomics. The results of gut microbiota indicated that PG could significantly improve the composition and structure of microbes in the gut of C. elegans, and the relative abundance of beneficial bacteria was up-regulated. Untargeted metabolomic results elucidated that PG modulated antioxidant and antiaging activities through neuroactive ligand-receptor interaction, Citrate cycle (TCA cycle), pyruvate metabolism, ascorbate and aldarate metabolism and D-Arginine and D-ornithine metabolism of C. elegans. These results indicated that PG had excellent antioxidant and anti-aging activities, providing research value for the development of functional foods and improvement of aging-related diseases.

Bennet MD et al. (1983) J Cell Sci "DNA density in mitotic and meiotic metaphase chromosomes of plants and animals."

Ward JP, Smith JB, Bennet MD, Heslop-Harrison JS

[J Cell Sci, 1983]

Studies of chromosome disposition at metaphase using serial thin-sectioning and three-dimensional reconstruction techniques have produced accurate estimates of the total volume of chromosomes per cell in 15 plant and two animal species. Comparing this character with the 4C DNA amount showed no indication of systematic differences in DNA density between either organisms with widely different (>200-fold) C values or different groups or organisms. For example, there was no significant difference between the density of DNA in somatic metaphase chromosomes of man (0.141 pg/um3) and its mean in 14 angiosperm plant species (0.182 pg/um3), or between four dicotyledons (0.180 pg/um3) and 10 monocotyledons (0.182 pg/um3). However, evidence was found showing that DNA density can vary significantly within a species. Thus, although the total chromosome volume per cell was closely correlated (r>0.97) with 4C DNA amount in somatic and meiotic cells, the density of DNA in metaphase chromosomes was significantly lower in meiocytes (0.131 pg/um3) than in somatic metaphase cells (0.179

Kim B et al. (2019) Sci Rep "Differential effects of alkyl gallates on quorum sensing in Pseudomonas aeruginosa."

Choi HY, Kwak JH, Kim B, Kim WG, Park JS

[Sci Rep, 2019]

Virulence factors and biofilms constitute attractive targets for the prevention of infections caused by multidrug-resistant bacteria. Among alkyl gallates, propyl gallate (PG) and octyl gallate (OG) are used as food preservatives. Here we found that alkyl gallates differentially affect virulence, biofilm formation, and quorum sensing (QS) in Pseudomonas aeruginosa. Ethyl gallate (EG), PG, and butyl gallate (BG) inhibited biofilm formation and virulence factors including elastase, pyocyanin, and rhamnolipid, in P. aeruginosa without affecting cell viability by antagonizing the QS receptors LasR and RhlR. PG exhibited the most potent activity. Interestingly, hexyl gallate (HG) inhibited the production of rhamnolipid and pyocyanin but did not affect elastase production or biofilm formation. Notably, OG inhibited the production of rhamnolipid and pyocyanin but stimulated elastase production and biofilm formation. Analysis of QS signaling molecule production and QS gene expression suggested that HG inhibited RhlR, while OG activated LasR but inhibited PqsR. This mechanism was confirmed using QS mutants. Additionally, PG prevented the virulence of P. aeruginosa in Caenorhabditis elegans and a mouse model. This is the first report of the differential effects of alkyl gallates on QS systems and PG has great potential as an inhibitor of the virulence and biofilm formation of P. aeruginosa.

Hu M et al. (2021) Dev Dyn "Mechanisms of TGFB in prostaglandin synthesis and sperm guidance in C. elegans."

Serra R, Prasain JK, Hu M, Tiwary E, Miller M

[Dev Dyn, 2021]

BACKGROUND: The transparent epidermis of C. elegans makes it an attractive model to study sperm motility and migration within an intact reproductive tract. C. elegans synthesize specific F-series prostaglandins (PGFs) that are important for guiding sperm toward the spermatheca. These PGFs are synthesized from polyunsaturated fatty acid (PUFA) precursors, such as arachidonic acid (AA), via a novel pathway, independent of the classical cyclooxygenases (Cox) responsible for most PG synthesis. While the enzyme(s) responsible for PG synthesis has yet to be identified, the DAF-7 TGFB pathway has been implicated in modulating PG levels and sperm guidance. RESULTS: We find that the reduced PGF levels in daf-1 Type I receptor mutants are responsible for the sperm guidance defect. The lower level of PGs in daf-1 mutants is due in part to the inaccessibility of AA. Finally, lipid analysis and assessment of sperm guidance in daf-1;daf-3 double mutants suggest DAF-3 suppresses PG production and sperm accumulation at the spermatheca. Our data suggest that DAF-3 functions in the nervous system, and possibly the germline, to affect sperm guidance. CONCLUSION: The C. elegans TGFB pathway regulates many pathways to modulate PG metabolism and sperm guidance. These pathways likely function in the nervous system and possibly the germline. This article is protected by copyright. All rights reserved.

Panitz D et al. (2015) BMC Pharmacol Toxicol "A C. elegans model of electronic cigarette use: Physiological effects of e-liquids in nematodes."

Swamy H, Panitz D, Nehrke K

[BMC Pharmacol Toxicol, 2015]

BACKGROUND: Electronic cigarettes (e-cigs) have recently become very popular particularly among the younger generation. These nicotine delivery devices are viewed as a preferable alternative to more conventional forms of tobacco use and are thought to reduce the risk of chronic obstructive pulmonary disease, the third leading cause of death worldwide. However, there is very little data available on the consequences of e-cig use, though recently nicotine-independent inflammatory responses have been reported. The genetic model organism Caenorhabditis elegans is a soil nematode whose cell biology is remarkably well conserved with mammals. Here, we used C. elegans to test the physiologic effects of e-liquids used to refill e-cigs. METHODS: Larval worms were exposed from hatching onwards to low concentrations (0.2%) of e-liquids, distilled e-liquid vapor, propylene glycol (PG), or M9 buffer as a negative control. E-liquids tested included grape, menthol, and V2 Red "classic tobacco" flavors. Nicotine (48ppm) was tested as a second level variable. Stereotypical physiological outputs were then measured, including developmental rate, fecundity, locomotion, lifespan, and the induction of canonical stress signaling pathways. RESULTS: A small but significant impairment of developmental rate and brood size was observed for PG and V2 Red treated worms compared to the negative control. Worms treated with e-liquids containing nicotine fared significantly worse than those that did not, but vaporization did not increase toxicity. Finally, both PG and V2 Red e-liquid induced an oxidative stress response in the absence of nicotine. CONCLUSIONS: PG exposure is sufficient to induce an oxidative stress response in nematodes, while nicotine is not. Both PG and nicotine independently influence physiologic measures of health and viability. The e-liquid flavorings did not significantly impact outcomes and there was no evidence for vaporization altering toxicity. These data suggest that the major physiologically significant component of e-liquids besides nicotine is likely the common solvent PG. We conclude that C. elegans are an appropriate model to rapidly assess parameters that may contribute to the basic cell biological effects of e-cigs.

Zhang W et al. (2016) Cell Mol Neurobiol "Shengmai Formula Ameliorates Pathological Characteristics in AD C.elegans."

Zhang W, Zhang Z, Wang X, Wang D, Zhi D, Ren H, Fei D, Zhu H, Li H

[Cell Mol Neurobiol, 2016]

Shengmai (SM) formula, a classical traditional Chinese medicine formula, is composed of Panax ginseng (Pg), Ophiopogon japonicus (Oj), and Schisandra Chinesis (Sc). SM has been clinically used to treat heart failure and ischemic heart disease. Although SM formula has been reported to be potential for fighting against Alzheimer's disease (AD) by previous works, there are many gaps in our knowledge on its usage in AD treatment on an organism level and will then need to be further clarified. In this study, transgenic Caenorhabditis elegans expressing human A1-42 are used to evaluate SM formula efficacy to treat AD phenotype and to investigate its underlying mechanism. The results showed that SM formula ameliorated AD pathological characteristics of paralysis behavior and chemotaxis defect in transgenic C.elegans. With SM treatment, the number of A deposits decreased, the levels of gene expressions of hsp16-2, hsp16-41, ace-1, ace-2, and TNFA1P1 homolog genes were down-regulated. Our results also showed that Oj exhibited more stronger effect on delaying paralysis in worms than Pg and Sc did, and synergistic action was observed between Pg and Oj, and Sc further enhanced the activity of Pg/Oj combination on delaying paralysis behavior. Further, SM with herbs of Pg, Oj, and Sc at a dose proportion of 9:9:6 exhibited superior therapeutic efficacy in comparison with herbs at other dose proportions. After SM formula extracted by ethanol, it delayed AD symptoms on a wider dose from 0.2 to 10.0mg/mL with no toxic effect. These results provided more evidence for SM formula being potential to be used to treat AD.

Sheth, Ujwal et al. (2009) International Worm Meeting "P granule-nuclear pore complexes are principal sites of mRNA export in C. elegans germ cells."

Pitt, Jason, Sheth, Ujwal, Priess, James R

[International Worm Meeting, 2009]

Germline-specific P granules contain numerous RNA-binding proteins, but little detectable mRNA except under quiescent states. P granules are perinuclear during most of development, but are cytoplasmic in oocytes and early embryos. Although functions of cytoplasmic P granules have not been determined, loss of perinuclear P granules is associated with inappropriate expression of at least some "masked" maternal mRNAs and transformation of germ cells into somatic cells [1]. The perinuclear P granules are associated specifically with clusters of nuclear pore complexes (NPCs), representing about 75% of the total NPCs. Here, we wanted to determine whether the NPCs associated with P granules (Pg-NPCs) are active sites of mRNA export, and found that mRNA export factors such as NXF-1 are enriched at the base of the Pg-NPCs under normal growth conditions. We discovered that heat shock could be used to induce expression of transgenic mRNA in late pachytene nuclei, and used this assay to examine mRNAs containing several types of 3''UTRs. These include 3''UTRs from mRNAs that are (a) normally translated in the gonad, (b) not translated in the gonad, or (c) targeted for degradation by RNAi. None of these nascent mRNAs were retained in P granules, and instead each showed a similar, transient accumulation in P granules before entering the general cytoplasm. This transient accumulation depended on P granule proteins such as GLH-1, and was not seen in somatic cells. Thus, Pg-NPCs appear to contain a dynamic population of mRNAs. Although in time-lapse movies Pg-NPCs appear to be stable (>20 mins), we found in photobleaching experiments that P granule components such as PGL-1 are highly dynamic (<20 sec half-recovery times). We conclude that, under normal growth conditions, the Pg-NPCs do not appear to act as storage sites for masked mRNAs although it remains possible that cytoplasmic P granules have a role in storage. Instead, our results support the view that Pg-NPCs are sites of dynamic interactions between proteins and nascent mRNAs. We noted previously that the GLH family of P granule proteins contains numerous FG repeats [2], analogous to FG repeats in core nucleoporins that function in the export of mRNA. Interestingly, we found that a gonad-specific isoform of DDX-19 is highly enriched in FG repeats, and that DDX-19 and a novel C. elegans protein with FG repeats are enriched in P granules. Thus, we hypothesize that these repeats function in the extended export of mRNA/protein past the NPC and through P granules. [1] Ciosk et al., Science 311, 851(2006) [2] Schisa et al., Development 128, 1287 (2001).

Lichty, James et al. (2021) International Worm Meeting "Elucidating Alzheimer's Disease related interactions between amyloid beta and the pathogen P. gingivalis in the model organism C. elegans"

Lichty, James, San Miguel, Adriana

[International Worm Meeting, 2021]

Alzheimer's Disease (AD) is a neurodegenerative disease which causes progressive loss of function in patients. AD affects about 5.8 million people in the US and is currently the sixth leading cause of death, with an estimated 122,000 deaths in 2018. AD is characterized by abnormal, widespread aggregation of the proteins amyloid beta (Abeta) and microtubule-associated protein tau (tau), neurodegeneration, immune system activation, inflammation, and oxidative stress. Abeta localization and aggregation have been linked to a number of AD traits but lack a clear causative role in the disease. Recently, infection by several pathogens have been identified as possible initiators for AD. One pathogen in particular, P. gingivalis (PG), has exhibited a number of features capable of inducing AD-like symptoms but its direct interactions with Abeta are poorly understood. We aim to identify and study these Abeta-PG interactions utilizing a novel Abeta expression system in the model organism C. elegans. This approach uses the C99 fragment of the amyloid precursor protein, the endogenous C. elegans gamma-gamma secretase, and a neuron-derived C. elegans signal peptide. Abeta is expressed as a part of C99, which is directed to the neuron membrane and cleaved, releasing Abeta extracellularly. This strain was compared to an intracellular Abeta expression strain to observe localization-dependent effects of Abeta on the organisms. We then infected the strains with PG, observing neuron health and overall health over the worms' lifespan. We seek to further characterize the detrimental effects, connecting them to AD traits seen in humans. Additionally, we will screen for genes relevant to the Abeta-PG interactions, such as C. elegans immunity pathways.