Toxicity mitigation by N-acetylcysteine and synergistic toxic effect of nano and bulk ZnO to Panagrellus redivivus

To better understand the nanosize-relevant toxic effects and underlying mechanisms, N-acetylcysteine (NAC), as a mitigation agent, an ionic form of Zn (ZnCl2), and the binary mixture of ZnO with different particle sizes (15 nm and 140 nm), was used in toxicity assays with the nematode Panagrellus redivivus. The ZnCl2 concentrations were applied to show the amount of dissolved Zn ions present in the test system. Reactive oxygen species (ROS) measuring method was developed to fit the used test system. Our studies have shown that NAC can mitigate the toxic effects of both studied particle sizes. In the applied concentrations, ZnCl2 was less toxic than both of the ZnO particles. This finding indicates that not only ions and ROS produced by the dissolution are behind the toxic effects of the ZnO NPs, but also other particle size-dependent toxic effects, like the spontaneous ROS generation, are also relevant. When the two materials were applied in binary mixtures, the toxic effects increased significantly, and the dissolved zinc content and the ROS generation also increased. It is assumed that the chemical and physical properties of the materials have been mutually reinforcing to form a more reactive mixture that is more toxic to the P. redivivus test organism. Our findings demonstrate the importance of using mitigation agent and mixtures to evaluate the size-dependent toxicity of the ZnO. Graphical abstract

Analysis of major sperm proteins in two nematode species from two classes, Enoplus brevis (Enoplea, Enoplida) and Panagrellus redivivus (Chromadorea, Rhabditida), reveal similar localization, but less homology of protein sequences than expected for Nematoda phylum

Major sperm proteins (MSP) are a nematode-specific system of motor proteins required for amoeboid sperm movement. A number of MSP genes vary in different nematode species, but encoded protein sequences reveal high homology between these proteins. In fact, all studies of MSPs localization and functions are based exclusively on the representatives of the order Rhabditida belonging to the nematode class Chromadorea, while MSP-driven sperm movement in Enoplea, another major clade of the phylum Nematoda is still unconfirmed. In this study, we found out the presence of MSPs in the enoplean nematode Enoplus brevis (Enoplida) and compared MSP localization in sperm of this species with the chromadorean nematode Panagrellus redivivus (Rhabditida). Then, we analyzed the putative MSP sequences of both species. Our results indicate that MSPs are presented in E. brevis spermatozoa and form filamentous structures after sperm activation, which may be considered as the evidence of their motor functions similar to those in the spermatozoa of chromadorean nematodes. We found that E. brevis MSPs show lower homology to known proteins of rhabditids which species reveal hyper-conservatism in MSP protein sequences. It reflects evidently more distant evolutionary relationships of Enoplea and Chromadorea than exist within Rhabditida order. Our data denote necessity of reconsideration of view on MSP evolution within Nematoda.

TOXICIDAD DE CINCO EXTRACTOS ACUOSOS BOTÁNICOS SOBRE PANAGRELLUS REDIVIVUS (NEMATODA: PANAGROLAIMIDAE), DAPHNIA MAGNA (CRUSTACEA: DAPHNIIDAE), LEMNA MINOR (ARACEAE) Y RAPHANUS SATIVUS (BRASSICACEAE)

El impacto toxicológico de extractos botánicos en el ambiente acuático y terrestre es un área de investigación emergente a nivel global. Cinco extractos botánicos de eucalipto (Eucalyptus globulus, Myrtaceae), ruda (Ruta graveolens, Rutaceae), ortiga (Urtica urens, Urticaceae), muña (Minthostachys mollis, Lamiaceae) e higuerilla (Ricinus communis, Euphorbiaceae) con potencial para el control de plagas fueron evaluados sobre el microgusano de la avena Panagrellus redivivus, la pulga del agua Daphnia magna, la lenteja de agua Lemna minor y el rábano Raphanus sativus en bioensayos toxicológicos bajo condiciones de laboratorio. Daphnia magna en términos de CL a 48 h de exposición 50 fue más sensible a E. globulus y a R. communis. P. redivivus a 96 h de exposición fue más sensible a R. communis. La clorosis de L. minor a 96 h de exposición y la inhibición de la germinación en términos de CE a 96 h de exposición sobre R. sativus fueron más sensibles a R. graveolens. Minthostachys mollis 50 ocasionó la menor toxicidad en los cuatro modelos biológicos. Los extractos botánicos de eucalipto e higuerilla causan una mayor toxicidad en el ambiente acuático y en el ambiente terrestre el extracto acuoso de ruda produjo mayor efecto tóxico.