Lan W et al. (2023) Sci Total Environ "Physiochemical responses of C. elegans under exposure to lanthanum and cerium affected by bacterial metabolism."

Chen J, Xiao X, Zhang X, Lan W, Nian J, Zhang Y, Sun S, Lin J, Hong G, Zhang F

[Sci Total Environ, 2023]

The increasing demand for rare earth elements (REEs) in modern applications has drawn significant attention. REEs can be introduced into the environment through REE-containing fertilizers, abandoned REE-rich equipment, and mining, persisting and impacting soil quality, nutrient cycles, and plant growth. Scientists have raised concerns about REEs entering the food chain from the environment and eventually accumulating in organisms. Decades of experimental evidence have shown that these effects include inhibited growth, impaired liver function, and alterations in children's intelligence quotients. However, there exists a paucity of research that has elucidated the metabolic-level biological impacts of REEs. In our study, Caenorhabditis elegans (C. elegans) was used as a model organism to investigate physiological and inherent metabolic changes under exposure to different concentrations of REEs. The diet bacteria of nematodes play a key role in their life and development. Therefore, we investigated the influence of bacterial activity on the nematodes' response to REE exposure. We observed a concentration-dependent accumulation of REEs in nematodes, which consequently led to a reduction in lifespan and alterations in body length. Exposure to a mixed solution of REEs, in comparison to a single REE solution, resulted in greater toxicity toward nematodes. The metabolic results showed that the above changes were closely related to REE-induced amino acid metabolism disorder, membrane disturbance, DNA damage, and oxidative stress. Of note, the presence of living bacteria elicits REE effects in C. elegans. These findings highlight the potential intrinsic metabolic changes occurring in nematodes under REE exposure. Our study raises awareness of the exposure risks associated with REEs, provides valuable insight into the metabolic-level biological impacts of REEs and contributes to the development of effective mitigation strategies to reduce potential risks to human health.

Xu T et al. (2017) Chemosphere "Behavioral deficits and neural damage of Caenorhabditis elegans induced by three rare earth elements."

Bao J, Lei L, Wu S, Xu T, Hu J, Li Z, Zhang M, He D, Wu T

[Chemosphere, 2017]

Rare earth elements (REEs) are widely used in industry, agriculture, medicine and daily life in recent years. However, environmental and health risks of REEs are still poorly understood. In this study, neurotoxicity of trichloride neodymium, praseodymium and scandium were evaluated using nematode Caenorhabditis elegans as the assay system. Median lethal concentrations (48h) were 99.9, 157.2 and 106.4mg/L for NdCl3, PrCl3 and ScCl3, respectively. Sublethal dose (10-30mg/L) of these trichloride salts significantly inhibited body length of nematodes. Three REEs resulted in significant declines in locomotor frequency of body bending, head thrashing and pharyngeal pumping. In addition, mean speed and wavelength of crawling movement were significantly reduced after chronic exposure. Using transgenic nematodes, we found NdCl3, PrCl3 and ScCl3 resulted in loss of dendrite and soma of neurons, and induced down-expression of dat-1::GFP and unc-47::GFP. It indicates that REEs can lead to damage of dopaminergic and GABAergic neurons. Our data suggest that exposure to REEs may cause neurotoxicity of inducing behavioral deficits and neural damage. These findings provide useful information for understanding health risk of REE materials.

Zhang H et al. (2010) Metallomics "Ecotoxicological assessment of lanthanum with Caenorhabditis elegans in liquid medium."

Zhang H, Zhao Y, Bai W, He X, Guo X, Zhang Z, Chai Z

[Metallomics, 2010]

With their widespread applications in industry, agriculture and many other fields, more and more rare earth elements (REEs) are getting into the environment, especially the aquatic systems. Therefore, understanding the aquatic ecotoxicity of REEs has become more and more important. In the present work, Caenorhabditis elegans (C. elegans) was used as a test organism and life-cycle endpoints were chosen along with elemental assay to evaluate the aquatic toxicity of lanthanum (La), a representative of REEs. The results show La+ had significant adverse effects on the growth and reproduction of worms above a concentration of 10 mol L. The elemental mapping by microbeam synchrotron radiation X-ray fluorescence (-SRXRF) illustrated how La treatment disturbed the metals distribution in the whole body of a single tiny nematode at lower levels. Our results suggested that the high-level REEs in some polluted water bodies would lead to an aquatic ecological crisis. The assessment we performed in the present work could be developed as a standardized test design for aquatic toxicological research.

Bichai F et al. (2009) Water Res "Protection against UV disinfection of E. coli bacteria and B. subtilis spores ingested by C. elegans nematodes."

Barbeau B, Bichai F, Payment P

[Water Res, 2009]

Nematodes, which occur abundantly in granular media filters of drinking water treatment plants and in distribution systems, can ingest and transport pathogenic bacteria and provide them protection against chemical disinfectants. However, protection against UV disinfection had not been investigated to date. In this study, Caenorhabditis elegans nematodes (wild-type strain N2) were allowed to feed on Escherichia coli OP50 and Bacillus subtilis spores before being exposed to 5 and 40 mJ/cm(2) UV fluences, using a collimated beam apparatus (LP, 254 nm). Sonication (15 W, 60s) was used to extract bacteria from nematode guts following UV exposure in order to assess the amount of ingested bacteria that resisted the UV treatment using a standard culture method. Bacteria located inside the gut of C. elegans were shown to benefit from a significant protection against UV. Approximately 15% of the applied UV fluence of 40 mJ/cm(2) (as typically used in WTP) was found to reach the bacteria located inside nematode guts based on the inactivation of recovered bacteria (2.7 log reduction of E. coli bacteria and 0.7 log reduction of B. subtilis spores at 40 mJ/cm(2)). To our knowledge, this study is the first demonstration of the protection effect of bacterial internalization by higher organisms against UV treatment, using the specific case of E. coli and B. subtilis spores ingested by C. elegans.

Comley JC et al. (1989) Int J Parasitol "Colorimetric quantitation of filarial viability."

Comley JC, Turner CH, Rees MJ, Jenkins DC

[Int J Parasitol, 1989]

A simple three-step colorimetric assay based on the tetrazolium salt MTT (3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) has been developed for quantifying filarial viability. Living (but not dead) filariae take up MTT and rapidly reduce it to formazan, so staining themselves dark blue. This colour change which is easily seen provides a rapid qualitative test for filarial viability. Quantitative data can be obtained by solubilizing formazan out of the worm with DMSO and measuring the absorbance of the resulting solution at 510 nm. To date the technique has been demonstrated in several species of filariae including Onchocerca volvulus. MTT reduction is thought to be selective for NADH-dependent dehydrogenase activity in viable worms. The reaction occurs readily in all developmental stages of Dipetalonema viteae including fragments of filarial tissue. Enzyme activity in viable intact D. viteae appears to be primarily associated with the hypodermis/muscle cells, with minimal formazan formation in the gut and reproductive tracts. The application of this MTT assay as a parameter for quantifying in vitro drugs effects is described. Assay procedures have been developed and optimized with D. viteae and Brugia pahangi for the assessment of effects of macrofilariae and microfilarial release, and the activity of a range of antifilarial standards reported. Several potential applications of the technique to studies on filarial biology are discussed.

Comley JC et al. (1989) Trop Med Parasitol "The further application of MTT-formazan colorimetry to studies on filarial worm viability."

Dobinson A, Rees MJ, Townson S, Comley JC

[Trop Med Parasitol, 1989]

Experiments have confirmed that MTT-formazan colorimetry in its simplest form (incubation of intact worms with MTT and direct visualisation of any formazan formed) can be readily applied to several species of filariae including Onchocerca volvulus. Data is presented which will assist the development of quantitative MTT reduction viability tests for a selection of the smaller filarial species. Assays of pieces of Onchocerca gutturosa and O. volvulus females have led us to tentatively conclude that the tips of filariae, particularly the anterior ends, may well be metabolically the most active part of the worm. Selective sampling of these regions for Onchocerca might therefore be a useful indicator for the viability of the parasite. An example of how MTT-formazan colorimetry has been applied to yield additional data to support motility observations on the in vitro survival of male O. gutturosa is also given. The in vitro timecourse of worm death caused by 10 microM CGP 20376 on Acanthocheilonema viteae females has been examined by MTT reduction and compared with 6 other non-subjective parameters. The results suggests that the parameters examined could be divided into two groups according to the time taken for CGP 20376 to cause 50% inhibition (t50) of the parameter. Fast response parameters had t50's between 1 and 6 h (motility indices, 14CO2 evolution, adenine uptake and leucine uptake), they are more sensitive measures of viability and indicate possible worm damage which may or may not be reversible. Slow response parameters had t50's between 34 and 48.5 h (lactate output, MTT reduction and adenine leakage), and are probably linked with severe degenerative changes and are indicative of worm death.(ABSTRACT TRUNCATED AT 250 WORDS)

Han GC et al. (2021) Toxicology "Effects of lanthanum nitrate on behavioral disorder, neuronal damage and gene expression in different developmental stages of Caenorhabditis elegans."

Li ZN, Gao S, Han GC, Jing HM, Zhang WJ, Zhang GY, Zhang N, Ning JY, Li GJ

[Toxicology, 2021]

Rare earth elements (REEs) are widely used in the industry, agriculture, biomedicine, aerospace, etc, and have been shown to pose toxic effects on animals, as such, studies focusing on their biomedical properties are gaining wide attention. However, environmental and population health risks of REEs are still not very clear. Also, the REEs damage to the nervous system and related molecular mechanisms needs further research. In this study, the L1 and L4 stages of the model organism Caenorhabditis elegans were used to evaluate the effects and possible neurotoxic mechanism of lanthanum(III) nitrate hexahydrate (La(NO3)3-6H2O). For the L1 and L4 stage worms, the 48-h median lethal concentrations (LC50s) of La(NO3)3-6H2O were 93.163 and 648.0 mg/L respectively. Our results show that La(NO3)3-6H2O induces growth inhibition and defects in behavior such as body length, body width, body bending frequency, head thrashing frequency and pharyngeal pumping frequency at the L1 and L4 stages in C. elegans. The L1 stage is more sensitive to the toxicity of lanthanum than the L4 stage worms. Using transgenic strains (BZ555, EG1285 and NL5901), we found that La(NO3)3-6H2O caused the loss or break of soma and dendrite neurons in L1 and L4 stages; and α-synuclein aggregation in L1 stage, indicating that Lanthanum can cause toxic damage to dopaminergic and GABAergic neurons. Mechanistically, La(NO3)3-6H2O exposure inhibited or activated the neurotransmitter transporters and receptors (glutamate, serotonin and dopamine) in C. elegans, which regulate behavior and movement functions. Furthermore, significant increase in the production of reactive oxygen species (ROS) was found in the L4 stage C. elegans exposed to La(NO3)3-6H2O. Altogether, our data show that exposure to lanthanum can cause neuronal toxic damage and behavioral defects in C. elegans, and provide basic information for understanding the neurotoxic effect mechanism and environmental health risks of rare earth elements.

Tabish M et al. (1999) Biochem J "Organization and alternative splicing of the Caenorhabditis elegans cAMP-dependent protein kinase catalytic-subunit gene (kin-1)."

Tabish M, Clegg RA, Rees HH, Fisher MJ

[Biochem J, 1999]

The cAMP-dependent protein kinase (protein kinase A, PK-A) is multifunctional in nature, with key roles in the control of diverse aspects of eukaryotic cellular activity. In the case of the free-living nematode, Caenorhabditis elegans, a gene encoding the PK-A catalytic subunit has been identified and two isoforms of this subunit, arising from a C-terminal alternative-splicing event, have been characterized [Gross, Bagchi, Lu and Rubin (1990) J. Biol. Chem. 265, 6896-6907]. Here we report the occurrence of N-terminal alternative-splicing events that, in addition to generating a multiplicity of non-myristoylatable isoforms, also generate the myristoylated variant(s) of the catalytic subunit that we have recently characterized [Aspbury, Fisher, Rees and Clegg (1997) Biochem. Biophys. Res. Commun. 238, 523-527]. The gene spans more than 36 kb and is divided into a total of 13 exons. Each of the mature transcripts contains only 7 exons. In addition to the already characterized exon 1, the 5'-untranslated region and first intron actually contain 5 other exons, any one of which may be alternatively spliced on to exon 2 at the 5' end of the pre-mRNA. This N-terminal alternative splicing occurs in combination with either of the already characterized C-terminal alternative exons. Thus, C. elegans expresses at least 12 different isoforms of the catalytic subunit of PK-A. The significance of this unprecedented structural diversity in the family of PK-A catalytic subunits is discussed.

Oral R et al. (2018) Ecotoxicol Environ Saf "Soil pollution and toxicity in an area affected by emissions from a bauxite processing plant and a power plant in Gardanne (southern France)."

Palumbo A, Di Nunzio A, Pagano G, Thomas PJ, Guida M, Toscanesi M, Gravina M, Tommasi F, Siciliano A, Oral R, Trifuoggi M, Lyons DM, Buric P

[Ecotoxicol Environ Saf, 2018]

Soil pollution and toxicity have been investigated in the Gardanne area (southern France) at a range of sites around a recognized pollution source, a bauxite processing plant (BPP), and a power plant (PP). Soil samples were submitted to inorganic and organic analyses and tested for toxicity in two invertebrate models. Inorganic analysis was based on determining elemental concentrations by ICP-MS, encompassing a total of 26 elements including 13 rare earth elements (REEs), of the soil samples and their leachates after 24 or 48h in seawater. Organic analyses were performed by measuring the sums of 16 polycyclic aromatic hydrocarbons (PAHs) and of total hydrocarbons (C-10 to C-40). Bioassays were carried out on the early life stages of three sea urchin species (Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis), and on a nematode (Caenorhabditis elegans). Sea urchin bioassays were evaluated by the effects of soil samples (0.1-0.5% dry wt/vol) on developing embryos and on sperm, and scored as: a) % developmental defects, b) inhibition of sperm fertilization success and offspring damage, and c) frequencies of mitotic aberrations. C. elegans 24h-mortality assay showed significant toxicity associated with soil samples. The effects of soil samples showed heightened toxicity at two groups of sites, close to the BPP main entrance and around the PP, which was consistent with the highest concentrations found for metals and PAHs, respectively. Total hydrocarbon concentrations displayed high concentrations both close to BPP main entrance and to the PP. Further studies of the health effects of such materials in Gardanne are warranted.