Preliminary investigation on the impact of engineered PVP-capped and uncapped silver nanoparticles on Eudrilus eugeniae, a terrestrial ecosystem model.

Recently, the production of silver nanoparticles and their commercial products has generated increased concern and caused a hazardous impact on the ecosystem. Therefore, the present study examines the toxic effect of chemically engineered silver nanoparticles (SNPs) and polyvinylpyrrolidone-capped silver nanoparticles (PVP-SNPs) on the earthworm Eudrilus eugeniae (E. eugeniae). The SNPs and PVP-SNPs were synthesized, and their characterization was determined by UV-vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. The toxicity of SNPs and PVP-SNPs was evaluated using E. eugeniae. The present result indicates that the lethal concentration (LC50) of SNPs and PVP-SNPs were achieved at 22.66 and 43.27 µg/mL, respectively. The activity of antioxidant enzymes including superoxide dismutase (SOD) and catalase (CAT) was increased in SNPs compared to PVP-SNPs. Importantly, we have noticed that the E. eugeniae can amputate its body segments after exposure to SNPs and PVP-SNPs. This exciting phenomenon is named "autotomy," which describes a specific feature of E. eugeniae to escape from the toxic contaminants and predators. Accordingly, we have suggested this unique behavior may facilitate to assess the toxic effect of SNPs and PVP-SNPs in E. eugeniae.

Exploiting the unique phenotypes of the earthworm Eudrilus eugeniae to evaluate the toxicity of chemical substances.

Both the evaluation and the determination of toxicity of chemical substances present in the environment have implications in human health. In this present study, the natural phenomenon named autotomy, a self-defense mechanism employed by several animals against the toxic chemical contaminants, was considered to assess the toxicity of different chemical substances. We investigated the effects of glucose, sodium chloride, kanamycin, mercuric chloride, arsenic trioxide, and lead oxide on the phenotypes of earthworm Eudrilus eugeniae. Depending on the concentration of different chemicals, worms exhibit unique phenotypes. These phenotypes can be used to identify the toxicity as well as the toxic concentration of the chemicals. Upon exposure to toxic chemicals, worms use different mechanical forces at the site of cleavage furrow to detach its segments. During the detachment, there is no apparent blood loss at both the ends of the worm. Our results show that the mercuric chloride is toxic at the concentration above 5 µg when compared to other chemicals. Based on our findings, the toxic effects of a chemical and the toxic concentration of a chemical can be evaluated in both cost and time-efficient manner; in addition, these chemicals can be classified into the following categories: (1) mercuric chloride is extreme-toxic, (2) arsenic trioxide and lead oxide is toxic, (3) kanamycin and sodium chloride is low-toxic, and (4) glucose is non-toxic.

Function of translationally controlled tumor protein (TCTP) in Eudrilus eugeniae regeneration.

TCTP (Translationally Controlled Tumour Protein) is a multifunctional protein that plays a role in the development, immune system, tumour reversion, and maintenance of stem cells. The mRNA of the Tpt1 gene is over-expressed during liver regeneration. But, the function of the protein in regeneration is not known. To study the role of the protein in regeneration, the earthworm Eudrilus eugeniae was chosen. First, the full length cDNA of the Tpt1 gene was sequenced. The size of the cDNA is 504 bp and the protein has 167 amino acids. The highest level of TCTP expression was documented in the worm after three days of regeneration. The protein was found to be expressed specifically in the epithelial layer of the skin. During regeneration, the protein expression was found to be the highest at the tip of blastema. The pharmacological suppression of TCTP using nutlin-3 and TCTP RNAi experiments resulted in the failure of the regeneration process. The suppression of TCTP caused the arrest of proliferation in posterior amputated worms. The severe cell death was documented in the amputated region of nutlin-3 injected worm. The silencing of TCTP has blocked the modification of clitellar segments. The experiments confirm that TCTP has major functions in the upstream signalling of cell proliferation in the early regeneration process in E. eugeniae.

Studies on regeneration of central nervous system and social ability of the earthworm Eudrilus eugeniae.

Earthworms are segmented invertebrates that belong to the phylum Annelida. The segments can be divided into the anterior, clitellar and posterior parts. If the anterior part of the earthworm, which includes the brain, is amputated, the worm would essentially survive even in the absence of the brain. In these brain amputee-derived worms, the nerve cord serves as the primary control center for neurological function. In this current work, we studied changes in the expression levels of anti-acetylated tubulin and serotonin as the indicators of neuro-regenerative processes. The data reveal that the blastemal tissues express the acetylated tubulin and serotonin from day four and that the worm amputated at the 7th segment takes 30 days to complete the regeneration of brain. The ability of self-assemblage is one of the specific functions of the earthworm's brain. The brain amputee restored the ability of self-assemblage on the eighth day.