Morphological Changes Induced by Titanium Dioxide Nanoparticles (nano-TiO 2 ) during the Development of the Tropical Sea Urchin Lytechinus variegatus (Lamarck, 1816).

Author(s)

Leticia Palmeira Pinto

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2021-07-01

Examining board members

Jose Roberto Machado Cunha da Silva; Marisa Narciso Fernandes; Camilo Dias Seabra Pereira; Chao Yun Irene Yan

• Advisor: Jose Roberto Machado Cunha da Silva; Luis Fernando Marques dos Santos

Abstract

Nanoparticles (NPs) are a major and growing environmental concerns for coastal marine environments. Among them, titanium dioxide (nano-TiO 2 ) are widely present in numerous products for everyday use as well as for human consumption, and can be occur at higher concentrations in marine coastal waters (<1mg/L), where they represent a risk to the organisms. Sea urchins are considered excellent bioindicators of environmental and anthropogenic stressors, such as climate change and marine pollutants, respectively, especially during their embryonic development. Exposure to NPs in the early life stages mainly implies larval malformations and developmental arrest, which may compromise the recruitment of these species. The present study aimed to evaluate the effects of nano-TiO 2 (0.005, 0.05, 0.5 and 5 g/mL) on the fertilization, embryonic and larval development of the sea urchin Lytechinus variegatus. The toxicity of nano-TiO 2 was evaluated through fertilization capacity and development toxicity tests, taking into account changes in fertilization and developmental rates, morphological (investigated by TEM - transmission electron microscopy), morphometric parameters and presence of malformations (conventional microscopy). A decrease in fertilization rate was observed only at the highest concentration (5 g/mL). During the development of the gastrulae, nano-TiO 2 induced higher toxicity at the low environmentally relevant concentration of 0.005 g/mL, with a large number of embryos with arrested development. In the development of larvae, the highest concentration was more toxic, with a large number of arrested development larvae (EC 50 > 5 g/mL). The measurements showed that nano-TiO 2 induced a decrease in the size of the post-oral arms of the larva pluteus, especially at the highest concentrations (0.5 and 5 g/mL). Large nano-TiO 2 agglomerates were observed around the larvae body. Taking into account that larvae are filter-feeding organisms, they could interact more easily with agglomerate-shaped NPs, resulting in a greater impact on development and growth. In conclusion, we showed the toxicity potential of nano-TiO 2 to the tropical sea urchin L. Variegatus, with deleterious effects on fertilization rate and malformations and delays in the development of embryos and larvae, in concentrations ranging from environmentally- relevant to acute exposure scenarions. (AU)

• FAPESP's process: 17/25568-0 - Evaluation of morphological and molecular changes induced by titanium dioxide nanoparticles (nano-TiO2) in embryos of the tropical sea urchin Lytechinus variegatus (Lamarck, 1816)
• Grantee: Letícia Palmeira Pinto
• Support Opportunities: Scholarships in Brazil - Master