Odunuga OO et al. (2012) Protein Expr Purif "Caenorhabditis elegans Hsp70-1 expresses highly in bacteria, is sufficiently soluble, and has a catalytic constant similar to Hsc70 and BiP."

Bollinger SA, Odunuga OO, Choi KH, Polvadore EI

[Protein Expr Purif, 2012]

Caenorhabditis elegans has been used as a model organism to study the roles of molecular chaperones in cellular processes. C. elegans heat shock protein 70-1 (CeHsp70-1) is the first of the 13-member Hsp70 family genes identified so far in the organism. The protein product of this gene, CeHsp70-1, has been shown to play an important role in conferring thermo-tolerance and longevity on C. elegans. Here, we present the results of the first work to over-express, purify and characterize the ATP hydrolyzing activity of a member of the C. elegans Hsp70s. Recombinant CeHsp70-1 was found to be highly expressed and sufficiently soluble in Escherichia coli. The protein was purified to homogeneity using a combination of nickel affinity, ion exchange and size-exclusion chromatography. Kinetic properties of the basal ATPase activity of the enzyme in a low-salt buffer were determined using a colorimetric assay. The specific activity (V(max) per mg protein), K(m) and k(cat) values obtained for CeHsp70-1 were 25 nmol/min/mg, 50 M and 0.28 min, respectively. The catalytic constant (k(cat)) of the protein was found to be similar to that of heat shock cognate 70 (Hsc70) and binding immunoglobulin protein (BiP). At low concentrations, CeHsp70-1 existed mostly in its monomeric form. This work provides a platform for kinetic studies of other members of the C. elegans Hsp70 molecular chaperones.

Gu JQ et al. (2005) Z Naturforsch C "Identification of nematicidal fatty acids and triglycerides from seeds of Jubaea chilensis by GC-EI-MS and chemical transformation methods."

Timmins SD, Eppler CM, Gu JQ, Montenegro G, Timmermann BN

[Z Naturforsch C, 2005]

Nematicidal bioassay-guided fractionation of the n-hexane extract of the seeds of Jubaea chilensis led to the identification of eight known fatty acids and a mixture of triglycerides, reported for the first time for this species. In addition, their corresponding methyl esters were identified to be artifacts generated during the extraction and isolation procedures by using GC-EI-MS and chemical transformation methods. The fatty acid composition of the triglycerides was analyzed by GC-EI-MS and chemical transformation techniques. Among the 17 compounds, only lauric acid and myristic acid exhibited significant inhibitory effects on the movement of Caenorhabditis elegans with minimum inhibitory concentrations (MIC) of 75 microg/ml.

Wang Q et al. (2023) Toxics "A New Method for Ecological Risk Assessment of Combined Contaminated Soil."

Zhu Y, Hou H, Feng X, Wang X, Wang Q, Wang J, Cheng J, Geng J

[Toxics, 2023]

Ecological risk assessment of combined polluted soil has been conducted mostly on the basis of the risk screening value (<i>RSV</i>) of a single pollutant. However, due to its defects, this method is not accurate enough. Not only were the effects of soil properties neglected, but the interactions among different pollutants were also overlooked. In this study, the ecological risks of 22 soils collected from four smelting sites were assessed by toxicity tests using soil invertebrates (<i>Eisenia fetida</i>, <i>Folsomia candida</i>, <i>Caenorhabditis elegans</i>) as subjects. Besides a risk assessment based on RSVs, a new method was developed and applied. A toxicity effect index (<i>EI</i>) was introduced to normalize the toxicity effects of different toxicity endpoints, rendering assessments comparable based on different toxicity endpoints. Additionally, an assessment method of ecological risk probability (<i>RP</i>), based on the cumulative probability distribution of <i>EI</i>, was established. Significant correlation was found between <i>EI</i>-based <i>RP</i> and the <i>RSV</i>-based Nemerow ecological risk index (<i>NRI</i>) (<i>p</i> &lt; 0.05). In addition, the new method can visually present the probability distribution of different toxicity endpoints, which is conducive to aiding risk managers in establishing more reasonable risk management plans to protect key species. The new method is expected to be combined with a complex dose-effect relationship prediction model constructed by machine learning algorithm, providing a new method and idea for the ecological risk assessment of combined contaminated soil.

Haegerbaeumer A et al. (2019) Ecotoxicol Environ Saf "Comparing the effects of fludioxonil on non-target soil invertebrates using ecotoxicological methods from single-species bioassays to model ecosystems."

Traunspurger W, Hoss S, Haegerbaeumer A, Raschke R, Reiff N

[Ecotoxicol Environ Saf, 2019]

The lower tier toxicity tests used for risk assessment of plant protection products are conducted with single species, only regarding direct effects of the tested substances. However, it is not clear, if lower tier tests are able to protect in situ soil communities, as these tests are not able to account for direct and indirect effects of chemicals on multi-species systems in natural soil communities. This knowledge gap between single-species tests and field studies can be bridged using model ecosystems (microcosms), which allow for the assessment of direct and indirect effects of the compounds under evaluation. In the present study, single-species toxicity tests and soil-spiked microcosms were used to comparatively investigate the toxicity of the non-systemic fungicide fludioxonil (FDO) on non-target soil organisms, with nematodes being the test organisms of choice. The potential effects of FDO on nematodes were investigated in two different test systems: (i) standardized toxicity tests using Caenorhabditis elegans exposed to FDO-spiked soil (FDO concentrations 50-1207mg/kg soil dry weight) and (ii) in situ nematode communities sampled from microcosms containing FDO-spiked soil (FDO concentrations 75-600mg/kg soil dry weight). FDO dose-dependently inhibited the reproduction of C. elegans, with an effect concentration (EC50) of 209.9mg FDO/kg soil dry weight and a no observed effect concentration (NOEC) of 63.0mg FDO/kg soil dry weight. In the microcosms, FDO significantly affected trait-based indices, such as the Maturity Index (MI25) and the Enrichment Index (EI), which responded already at FDO concentrations of 14.3 and 62.4mg/kg dry soil. Overall, this study provides new insights into the impact of the non-systemic fungicide FDO on non-target soil organisms and demonstrates the suitability of nematode-based tools, that allow for a quick and cost-effective lower and higher tier risk assessment of plant protection products.