ABSTRACT
Cadmium chloride (CdCl2) is a salt that has high solubility in water and is frequently adopted as a reference substance in laboratory ecotoxicological assays. Several institutions have been standardizing tests to define toxicity thresholds to protect organisms and ecosystems. Invertebrates are frequently used in these evaluations, and mollusks, the second largest animal group, are suggested as appropriate models. Standardizing ecotoxicological assays with native species is necessary, since in the majority of cases, they are more susceptible to environmental contamination than exotic species, and thus, validating tests with ecological and environmental representativeness in different countries is essential. The objective of this study was to compare and evaluate the sensitivity of the Brazilian native freshwater snail Biomphalaria glabrata (Say, 1818) and the European standard species Lymnaea stagnalis (Linnaeus, 1758), by analyzing the acute toxic effect of CdCl2. The survival of adult’s snails of the species B. glabrata and L. stagnalis was evaluated through 24- hour exposure to concentrations of 0.00; 0.12; 0.25; 0.50; 1.00 and 2.00 mg L-1 of CdCl2. The lethal concentration (LC50) for adult organisms was 0.48 mg L-1 for B. glabrata and 0.33 mg L-1 for L. stagnalis. With the ecotoxicological assays carried out, it was possible to establish physical-chemical parameters and comparatively evaluate the sensitivity of L. stagnalis and B. glabrata, it was possible to show that B. glabrata was responsive and had similar results to L. stagnalis. For standardization procedures in countries that require the regulation of new tests, the comparison between organisms already validated worldwide is an additional motivation to employ them for the implementation of tests with endemic species in countries such as Brazil.
O cloreto de cádmio (CdCl2) é um sal que apresenta alta solubilidade em água e frequentemente utilizado como substância de referência em avaliações ecotoxicológicas laboratoriais. Diversas instituições têm padronizado testes para definir limiares de periculosidade de produtos químicos, bem como a qualidade da água e dos efluentes, que visam proteger os organismos e os ecossistemas. Invertebrados são frequentemente utilizados nessas avaliações, sendo que os moluscos por serem o segundo maior grupo animal são sugeridos como modelos responsivos para diferentes abordagens. O incentivo ao uso de espécies nativas, é devido ao fato de que na maioria dos casos, são organismos mais sensíveis aos poluentes ambientais do que espécies invasoras, desse modo, validar testes com representatividade ecológica e ambiental em diferentes países é essencial. O objetivo deste trabalho foi avaliar comparativamente a sensibilidade do caramujo de água doce nativo Biomphalaria glabrata (Say, 1818) com a espécie holártica normatizada na Europa para ensaios ecotoxicológicos, Lymnaea stagnalis (Linnaeus, 1758), por meio da análise do efeito tóxico agudo da substância de referência CdCl2. Para isso, foram avaliadas a sobrevivência de caramujos adultos das espécies B. glabrata e L. stagnalis através de exposições por 24 horas às concentrações de 0,00; 0,12; 0,25; 0,50; 1,00 e 2,00 mg L-1 de CdCl2. A concentração letal média (CL50) para os organismos adultos foi de 0,48 mg L-1 em B. glabrata e 0,33 mg L-1 em L. stagnalis. Com os ensaios ecotoxicológicos realizados foi possível estabelecer parâmetros físico-químicos e avaliar comparativamente a sensibilidade da espécie L. stagnalis com a espécie B. glabrata e demonstrar que a B. glabrata se mostrou responsiva e com resultados similares aos observados com L. stagnalis. Para os procedimentos de padronização e normatização em países que necessitam de regulamentação de novos ensaios, a comparação entre organismos já validados mundialmente, corroboram com informações para a implementação de ensaios com espécies endêmicas em países como o Brasil.
ABSTRACT
The event of cellular reprogramming into pluripotency is influenced by several factors, such as in vitro culture conditions (e.g., culture medium and oxygen concentration). Herein, bovine iPSCs (biPSCs) were generated in different levels of oxygen tension (5% or 20% of oxygen) and supplementation (bFGF or bFGF + LIF + 2i-bFL2i) to evaluate the efficiency of pluripotency induction and maintenance in vitro. Initial reprogramming was observed in all groups and bFL2i supplementation initially resulted in a superior number of colonies. However, bFL2i supplementation in low oxygen led to a loss of self-renewal and pluripotency maintenance. All clonal lines were positive for alkaline phosphatase; they expressed endogenous pluripotency-related genes SOX2, OCT4 and STELLA. However, expression was decreased throughout the passages without the influence of oxygen tension. GLUT1 and GLUT3 were upregulated by low oxygen. The biPSCs were immunofluorescence-positive stained for OCT4 and SOX2 and they formed embryoid bodies which differentiated in ectoderm and mesoderm (all groups), as well as endoderm (one line from bFL2i in high oxygen). Our study is the first to compare high and low oxygen environments during and after induced reprogramming in cattle. In our conditions, a low oxygen environment did not favor the pluripotency maintenance of biPSCs.