Taylor KA et al. (1990) J Parasitol "The effect of oxygen and carbon dioxide on the development of the free-living stages of Strongyloides ratti in axenic culture."

Weinstein PP, Taylor KA

[J Parasitol, 1990]

The effect of oxygen and carbon dioxide concentration on the development of the free-living stages of Strongyloides ratti in axenic culture was examined. Hatching of S. ratti eggs was inhibited at very low oxygen levels. Development of all organisms was inhibited in medium gassed with less than 4% O2 in 0.03% CO2 with the remainder N2. Between 8 and 21% O2 there was no significant difference in the percentage developing directly to filariform larvae, free-living females, or free-living males. Cultures gassed with CO2 concentrations greater than 1% in 21% O2 with the remainder N2 manifested inhibited development to filariform larvae, whereas concentrations between 5 and 7.5% enhanced development to free-living females. There was a positive effect on increasing the CO2 concentration from 0.03% to 5% on development to filariform larvae and male worms at levels of 1% and 2% oxygen in nitrogen, respectively. Direction of development, either directly to the filariform larva or to the free-living female, was influenced by CO2 and O2 concentrations encountered by the egg or the newly hatched larva of the parasitic female in axenic culture. The axenic culture system permits an important experimental approach to the study of factors modulating the differentiation of the free-living stages of Strongyloides.

Wei JZ et al. (2017) Appl Environ Microbiol "An Enterotoxin-like Binary Protein from Pseudomonas protegens with Potent Nematicidal Activity."

Oral J, Wu G, Siehl DL, Rosen B, Wei JZ, Hou Z, Taylor CG

[Appl Environ Microbiol, 2017]

Soil microbes are a major food source for free-living soil nematodes. It is known that certain soil bacteria have evolved systems to combat predation. We identified the nematode-antagonistic Pseudomonas protegens strain 15G2 from screening of microbes. Through protein purification we identified a binary protein, designated as Pp-ANP, that is responsible for the nematicidal activity. This binary protein inhibits Caenorhabditis elegans growth and development by arresting larvae at L1 stage and killing older staged worms. The two subunits, Pp-ANP1a and Pp-ANP2a are active when reconstituted from separate expression in Escherichia coli The binary toxin also shows strong nematicidal activity against three other free-living nematodes, Pristionchus pacificus, Panagrellus redivivus, and Acrobeloides sp., but no activity was found for insects and fungi under test conditions, indicating specificity for nematodes. Pp-ANP1a has no significant homology to any known proteins, while Pp-ANP2a shows 30% homology to E. coli heat-labile enterotoxin (LT) subunit A and cholera toxin (CT) subunit A. Protein modeling indicates Pp-ANP2a is structurally similar to CT/LT and likely acts as a ADP-ribosyltransferase. Despite the similarity, Pp-ANP shows several characteristics distinct from CT/LT toxins. Our results indicate that Pp-ANP is a new enterotoxin-like binary toxin with potent and specific activity to nematodes. The potency and specificity of Pp-ANP suggests applications in controlling parasitic nematodes and opens an avenue for further research on its mechanism of action and role in bacterium-nematode interaction.IMPORTANCE This study reports the discovery of a new enterotoxin-like binary protein, Pp-ANP from a Pseudomonas protegens strain. Pp-ANP shows strong nematicidal activity against Caenorhabditis elegans larvae and older staged worms. It also shows strong activity on other free-living nematodes, Pristionchus pacificus, Panagrellus redivivus, and Acrobeloides sp. The two subunits, Pp-ANP1a and Pp-ANP2a, can be expressed separately and reconstituted to form the active complex when mixed together. Pp-ANP shows some distinct characteristics when compared with other toxins, including Escherichia coli enterotoxin and cholera toxin. The present study indicates that Pp-ANP is a novel binary toxin and that it has potential applications in controlling parasitic nematodes and in studying toxin-host interaction.

Bottjer KP et al. (1985) Comparative Biochemistry and Physiology "Effects of an azasteroid on growth, development and reproduction of the free-living nematodes C. briggsae and Panagrellus redivivus."

Bottjer KP, Weinstein PP, Thompson MJ

[Comparative Biochemistry and Physiology, 1985]

The azasteroid, 25-azacoprostane (ASA-6), was evaluated for its effects on the growth, development and reproduction of the free- living nematodes, Caenorhabditis briggsae and Panagrellus redivivus. The axenic culture medium for either species of nematode consisted of Caenorhabditis briggsae Maintenance Medium (CbMM): formalin-killed Escherichia coli (1:1) with or without the addition of 5 micrograms cholesterol per ml and/or 25 micrograms ASA-6 per ml medium. All cultures also contained 50 micrograms Tween 80 per ml medium. After two generations of growth in sterol-deficient media, both species displayed a decrease in mean length, a decrease in the percent development to the adult stage and an inhibition of reproductive capability. These effects were more apparent in the sterol-deficient medium containing ASA-6. In the presence of cholesterol and ASA-6, growth and reproduction of C. briggsae, but not of P. redivivus, was inhibited after five generations. Morphologic abnormalities of azasteroid-inhibited worms were similar to those shown by worms cultured in sterol-deficient medium. These results suggest that different species of nematodes may exhibit different responses to azasteroid and that sterol utilization and metabolism may vary between nematode species. In addition, the similarities between the known effects of azasteroid inhibition in insects and those presented in this study on nematodes suggest a similar mechanism of action by the inhibitor in both groups of

Fujimoto S et al. (2016) Biochem J "The PP-motif in luminal loop 2 of ZnT transporters plays a pivotal role in TNAP activation."

Kambe T, Nishito Y, Masuda S, Fu D, Sekler I, Tsuji T, Merriman C, Fukue K, Miyamae Y, Hoch E, Fujiwara T, Nagao M, Fukunaka A, Takeda TA, Fujimoto S

[Biochem J, 2016]

Secretory and membrane bound, zinc-requiring enzymes are thought to be activated by binding zinc in the early secretory pathway. One such enzyme, tissue-nonspecific alkaline phosphatase (TNAP), is activated through a two-step mechanism, via protein stabilization and subsequent enzyme activation through metalation, by ZnT5-ZnT6 heterodimers or ZnT7 homodimers. However, little is known about the molecular basis underlying the activation process. Here, we found that the di-proline motif (PP-motif) in luminal loop 2 of ZnT5 and ZnT7 is important for TNAP activation. TNAP activity was significantly reduced in cells lacking ZnT5-ZnT6 heterodimers and ZnT7 homodimers (triple knockout (TKO) cells). The decreased TNAP activity was restored by expressing hZnT5 with hZnT6 or hZnT7, but significantly less so (almost 90% less) by expressing mutants thereof in which the PP-motif was mutated to alanine (PP-AA). In TKO cells, over-expressed hTNAP was not completely activated, and it was converted less efficiently to the holo form by expressing a PP-AA mutant of hZnT5 with hZnT6, whose defects were not restored by zinc supplementation. The zinc transport activity of hZnT7 was not significantly impaired by the PP-AA mutation, indicating that the PP-motif is involved in the TNAP maturation process, although it does not control zinc transport activity. The PP-motif is highly conserved in ZnT5 and ZnT7 orthologs, and its importance for TNAP activation is conserved in the Caenorhabditis elegans hZnT5 ortholog CDF5. These results provide novel molecular insights into the TNAP activation process in the early secretory pathway.

Dong R et al. (2020) Food Chem "Composition of bound polyphenols from carrot dietary fiber and its in vivo and in vitro antioxidant activity."

Xie M, Chen Y, Liu S, Hu X, He Z, Dong R, Nie S, Xie J, Yu Q, Liao W

[Food Chem, 2020]

Qualitative analysis of bound polyphenols from carrot dietary fiber (CDF-PP) was performed by ultra-performance liquid chromatography equipped with an electrospray ionization and quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS/MS). Eleven organic acids, nine hydroxybenzoic acids and derivatives, six hydroxycinnamic acids and derivatives, four phenolic alcohols and derivatives, three flavonoids and derivatives, seven esters and derivatives, two other compounds, were detected by matching their retention times, secondary mass spectrometry fragment information with authentic standards or literature data. Furthermore, in vitro antioxidant activity was determined by different kinds of assays, including DPPH, ORAC, PSC, demonstrated that CDF-PP could scavenge radicals in a dose dependent manner. Moreover, CDF-PP exhibited significantly reactive oxygen species (ROS) scavenging activity in living Caenorhabditis elegans. To our knowledge, this is the first comprehensive research to investigate composition and in vitro/in vivo antioxidant activity of bound polyphenols in CDF, which implied that CDF-PP could be a promising source of antioxidants.

Schiemer F (1983) Oikos "Comparative aspects of food dependence and energetics of freeliving nematodes."

Schiemer F

[Oikos, 1983]

Life history data, population parameter ("r") and energetics obtained at a wide range of food supply are compared for two species of bacterivorous nematodes. Caenorhabditis briggsae (Cb) is representative for saprobic environments. Plectus palustris (Pp) and related species are known from heterogeneous habitats of higher predictability in food supply but lower bacterial biomass. In Cb the larval phase is short and maximal reproduction is attained immediately after maturation. Pp has a longer prereproductive period and a prolonged phase of egg production rates. Considerably higher rmax and production rates in Cb are linked to greater maintenance costs. Its food threshold is shifted to higher food densities compared to Pp. Differences in the functional response, thresholds and maximal performance of various parameters are contrasted with different qualities of food availability (overall density; heterogeneity; predictability) in the respective habitats of the two species. Short term, unpredictable conditions (i.e. saprobic environments) are expoited by species with high production performances and rmax. The high level of standard metabolism sets constraints at conditions of lower food availability. Heterogeneous environments of higher predictability in food supply call for homeostatic abilities: in Pp this is expressed in lower maintenance requirements, endurance of starvation and a prolonged reproductive phase.

Gerhard AP et al. (2021) Pharmaceuticals (Basel) "Pharyngeal Pumping and Tissue-Specific Transgenic P-Glycoprotein Expression Influence Macrocyclic Lactone Susceptibility in Caenorhabditis elegans."

Gerhard AP, Charvet CL, Harmache A, Krucken J, von Samson-Himmelstjerna G, Neveu C

[Pharmaceuticals (Basel), 2021]

Macrocyclic lactones (MLs) are widely used drugs to treat and prevent parasitic nematode infections. In many nematode species including a major pathogen of foals, <i>Parascaris univalens</i>, resistance against MLs is widespread, but the underlying resistance mechanisms and ML penetration routes into nematodes remain unknown. Here, we examined how the <i>P</i>-glycoprotein efflux pumps, candidate genes for ML resistance, can modulate drug susceptibility and investigated the role of active drug ingestion for ML susceptibility in the model nematode <i>Caenorhabditis elegans</i>. Wildtype or transgenic worms, modified to overexpress <i>P. univalens</i> PGP-9 (<i>Pun</i>-PGP-9) at the intestine or epidermis, were incubated with ivermectin or moxidectin in the presence (bacteria or serotonin) or absence (no specific stimulus) of pharyngeal pumping (PP). Active drug ingestion by PP was identified as an important factor for ivermectin susceptibility, while moxidectin susceptibility was only moderately affected. Intestinal <i>Pun</i>-PGP-9 expression elicited a protective effect against ivermectin and moxidectin only in the presence of PP stimulation. Conversely, epidermal <i>Pun</i>-PGP-9 expression protected against moxidectin regardless of PP and against ivermectin only in the absence of active drug ingestion. Our results demonstrate the role of active drug ingestion by nematodes for susceptibility and provide functional evidence for the contribution of <i>P</i>-glycoproteins to ML resistance in a tissue-specific manner.

Aguiar Cordeiro R et al. (2018) Future Microbiol "-lactam antibiotics & vancomycin increase the growth & virulence of Candida spp."

Souza Collares Maia Castelo-Branco D, Silva Franco JD, Aguiar Cordeiro R, Sales JA, de Jesus Evangelista AJ, Serpa R, Colares de Andrade AR, Nogueira Brilhante RS, Leite Mendes PB, Gadelha Rocha MF, Costa Sidrim JJ, de Oliveira JS, Carneiro Camara LM, de Alencar LP

[Future Microbiol, 2018]

AIM: To investigate the direct effect of antibiotics on growth and virulence of the major Candida species associated with invasive infections. MATERIALS &amp; METHODS: Cefepime, imipenem, meropenem, amoxicillin and vancomycin were tested at twofold the peak plasma concentration (2x PP) and the peak plasma concentration (PP). The effects of antibiotics on Candida albicans, Candida parapsilosis, Candida krusei and Candida tropicalis were investigated by colony counting, flow cytometry, proteolytic activity and virulence in Caenorhabditis elegans. RESULTS: Antibiotics increase growth and proteolytic activity of Candida spp; In addition, amoxicillin potentiates virulence ofC. krusei and C. tropicalis against Caenorhabditis elegans. CONCLUSION: These results suggest that antimicrobial therapy may have a direct effect on the pathophysiology of invasive fungal infections in patients at risk.

Weaver BP et al. (2016) Genes Dev "Time to move the fat."

Han M, Sewell AK, Weaver BP

[Genes Dev, 2016]

In this issue of Genes &amp; Development, Dowen and colleagues (pp. 1515-1528) elegantly unify two previously unconnected aspects of physiology. The investigators provide significant genetic evidence to support a critical link between developmental timing decisions and the regulation of lipid mobilization at the transition to adulthood in Caenorhabditis elegans This novel connection involves cross-tissue signaling from the hypodermis (epidermis) to the intestine to promote reproductive success in the germline.

Zhou T et al. (2023) Environ Res "Microplastics released from disposable medical devices and their toxic responses in Caenorhabditis elegans."

Zhao Y, Zhou T, Xu A, Hu X, Wu J, Cao Z, Liu Y, Ding Y, Yang B, Li Y

[Environ Res, 2023]

Owing to accelerated urbanization and industrialization, many plastic products have been manufactured and discharged into the environment, causing environmental and public health problems. Plastics in environmental media are further degraded by prolonged exposure to light, heat, mechanical friction, and other factors to form new pollutants called microplastics (MPs). Medical plastics have become a crucial source of plastics in environmental media. However, the release profiles of MPs from medical plastics and their potential ecological and health risks remain unclear. We used optical photothermal infrared spectroscopy to explore the release profiles of eight typical disposable medical devices (DMDs) under high-temperature steam disinfection (HSD). We also evaluated the toxicity of DMD-derived MPs in Caenorhabditis elegans (C. elegans). Our results showed that the changes in the surface morphology and modification of the DMDs were mainly associated with the material. Polypropylene (PP) and polystyrene (PS) materials exhibited high aging phenomena (e.g., bumps, depressions, bulges and cracks), and HSD broke their oxygen-containing functional groups and carbon chains. By contrast, minor changes in the chemical and physical properties were observed in the polyvinyl chloride (PVC)-prepared DMDs under the same conditions. Further physicochemical characterization indicated that the amount of MPs released from PP-prepared DMDs (P4: 1.27&#x202f;&#xb1;&#x202f;0.34&#x202f;&#xd7;&#x202f;10⁶) was greater than that from PVC-prepared DMDs (P7: 1.08&#x202f;&#xb1;&#x202f;0.14&#x202f;&#xd7;&#x202f;10⁵). The particle size of the released MPs was the opposite, PVC-prepared DMDs (11.45&#x202f;&#xb1;&#x202f;1.79&#x202f;&#x3bc;m)&#x202f;&gt;&#x202f;PP-prepared DMDs (7.18&#x202f;&#xb1;&#x202f;0.52&#x202f;&#x3bc;m). Toxicity assessment revealed that DMDs-released MPs significantly increased germ cell apoptosis from 2.45&#x202f;&#xb1;&#x202f;0.05 to 3.10&#x202f;&#xb1;&#x202f;0.09-3.95&#x202f;&#xb1;&#x202f;0.26 in C. elegans. Moreover, MPs from PP-prepared DMDs disrupted the intestinal barrier of worms, decreasing their lifespan. Our findings provided novel information regarding the profiles and mechanisms of MP release from DMDs and revealed their potential risks to ecological environment.