Nonsense mediated mRNA decay (NMD) is a surveillance mechanism that targets transcripts containing premature stop codons (PTCs) for degradation, and that also regulates up to 10% of the whole transcriptome. During the course of my PhD I set out to identify novel NMD factors by performing a genome-wide RNA interference (RNAi) screen in a transgenic strain of Caenorhabditis elegans carrying an NMD reporter. I identified five novel proteins that are putative NMD factors in worms: NGP-1, NPP-20, AEX-6, PBS-2 and NOAH-2. Knock-down of these proteins led to severe developmental defects: worms were either arrested during various larval stages or died prematurely. The only exception was AEX-6, the knockdown of which led to a milder phenotype. Homology analysis of the novel C. elegans NMD factors showed that these proteins are conserved in human, with the exception of NOAH-2, which only has a homologue in Drosophila melanogaster, NOMPA. By performing an NMD assay in human cells, I demonstrated that GNL2 (NGP-1) and SEC13 (NPP-20) are functionally conserved NMD factors in human. Analysis of the consequences of depletion of GNL2, SEC13, UPF1 or UPF2 on the transcriptome of HeLa cells revealed that these four proteins co-regulate a subset of endogenous NMD targets, whilst also independently regulating the expression of other sets of transcripts. The findings presented in this thesis further our knowledge of the biology of NMD in both nematodes and humans. They demonstrate the existence of further regulators of this surveillance pathway, and add a layer of complexity to this fine-tuned biological process.

"We are using genetic and molecular techniques to study a simple model organism, C. elegans, to determine the cues involved in the formation of the nervous system. Two molecules currently being studied in the laboratory play roles in the formation of the IL2 neurons, a class of sensory neurons in C. elegans. The first gene, dig-1, influences the sensory process or dendrite and is involved in adhesion as well as potentially providing directional information during development. The second gene, mig-10, influences the axon and may be involved in a cell signal cascade. Genetic screens of C. elegans using Ethyl methyl sulfonate (EMS) as a mutagen resulted in the isolation of mutants with defects in the IL2 sensory map; sensory processes followed aberrant paths, appearing to be defasciculated. Complementation tests showed that the mutations failed to complement n1321, a known allele of dig-1; thus, these new mutations were alleles of dig-1 (Ryder unpub. results). Several of these new alleles of dig-1, including nu336 and n1480, have been further studied to elucidate the role of this gene in sensory map formation. A dig-1 candidate gene was identified that encodes a protein that is a member of the immunoglobulin super-family (IgSF). The candidate gene is predicted to be a large gene, with a transcript of approximately 45Kb. The encoded protein contains three distinct regions and is similar to the hyalectan family of proteoglycans. N terminal region 1 contains immunoglobulin and fibronectin-like domains. Central region 2 is an area that is highly repeated with a potential to have GAGs attached. C-terminal region 3 contains domains associated with adhesion. Polymerase chain reaction (PCR) products from alleles nu336 and n1480 were amplified and sequenced from the candidate gene. The DNA lesion present in the candidate gene from both alleles fit the method for how that mutation was generated. The point mutation in allele nu336 removes a potential glycosylation site. The large re-arrangement in allele n1480 truncates the transcript, suggesting that the protein is also truncated. The sequencing results along with rescuing data (R. Proenca, personal communication) showed that the candidate gene for dig-1 was the gene of interest. Each of the alleles was further studied to determine how severe that allele was by looking at the neuronal process aspect and the brood size as well as displacement of the gonad. In general, alleles with severe defects in the nervous system also had severe gonad displacement, suggesting the gene functions similarly in the two tissues. To determine if the gene was expressed at the RNA level, reverse transcriptase polymerase chain reaction (RT-PCR) was used. Most of the RT-PCRs amplified a cDNA of the appropriate size that showed dig-1 was expressed at the RNA level. RT-PCR further suggested that all three regions were in one transcript as well as confirming part of the predicted exon structure to be correct. In addition, northern analysis showed the presence of a large transcript in wildtype worms as well as a smaller truncated transcript from allele n1480. To investigate developmental differences mixed stage of RNA and embryonic RNA from wildtype animals were compared using gene specific primers. The initial RT-PCR showed potential alternative splicing occurring at the 5? end of the gene during development. To examine expression at the protein level, two recombinant proteins from dig-1 were successfully made by cloning cDNA products from the 5?and 3? end of dig-1. The constructs were sequenced and shown to be in frame. The recombinant proteins (Ant1Con1 and Ant3Con3) were mass produced and sent to a commercial source for injection into pre-screened rabbits. Western analysis showed the presence of an antibody in the serum from two of the rabbits. These antibodies should prove useful in future determination of correctness of our models of DIG-1 function. IgSF members have been shown to have many roles in nervous system development. DIG-1 could act in either an attractive or a repellent role to position sensory processes during development. DIG-1 might also change its function over time; early in development DIG-1 could be adhesive and later become repellant as more sugars are added. The gene mig-10 is involved in sensory map formation. To localize MIG-10 expression, several transgenic animals were generated by injection of two constructs that should recombine in the worm to create a MIG-10::GFP fusion protein. Ten transgenic lines were generated and screened by PCR for the presence of the correct recombinant construct. If this construct makes functional, rescuing protein, the GFP expression should reflect the expression pattern of the MIG-10 protein."

Neuronal migration is an essential aspect of nervous system development; improper or incomplete neuronal migration can lead to debilitating disorders. The model organism Caenorhabditis elegans has 302 neurons and is ideal for studying nervous system development. The cytoplasmic adaptor protein, MIG-10, is necessary for the long range anteroposterior migration during embryogenesis of the neurons CAN, ALM, and HSN. Mutations in the mig-10 gene result in incomplete migrations of all three neurons. MIG-10 is a homologue of the vertebrate proteins lamellipodin and RIAM-1, which are involved in directing actin polymerization during axon outgrowth and guidance. RIAM-1 is known to interact with proteins from the Ras GTPase family. The MIG-10 protein has a pleckstrin homology (PH) domain, a Ras-associating (RA) domain, and a proline-rich region. We used a yeast two-hybrid system to investigate which Ras family proteins MIG-10 interacts with. Three isoforms of MIG-10, MIG-10A, MIG-10B, and MIG-10C, as well as the RAPH domain alone, were used as baits. No evidence of interaction was observed for any of the baits used. These results do not reject our hypothesis as the constitutively active Ras clones may need to be used or there may not be a direct interaction between MIG-10 and the Ras family members. We are currently screening a C. elegans cDNA library for interactions with all three isoforms of MIG-10. In the future we plan to investigate how MIG-10 may be involved in the WAVE/SCAR actin nucleation pathway.

An organisms’ diet represents an exogenous influence that often yields colossal effects on long-term health and disease risk. The overconsumption of dietary sugars for example, has contributed to significant increases in obesity and type-2 diabetes; health issues that are costly both economically and in terms of human life. Individuals who are obese or are type-2 diabetic often have compromised oxygen delivery and an increased vulnerability to oxygen-deprivation related complications, such as ischemic strokes, peripheral arterial disease and myocardial infarction. Thus, it is of interest to identify the molecular changes glucose supplementation or hyperglycemia can induce, which ultimately compromise oxygen deprivation responses. By utilizing the Caenorhabditis elegans genetic model system, which is anoxia tolerant, I determined that a glucose-supplemented diet negatively impacts responses to anoxia and that the insulin-like signaling pathway, through fatty acid and ceramide biosynthesis and antioxidant activity, modulates anoxia survival. Additionally, a glucose-supplemented diet induces lipid accumulation. Use of RNA-sequencing analysis to compare gene expression responses in animals fed either a standard or glucose-supplemented diet revealed that glucose impacts the expression of genes involved with multiple cellular processes including lipid and carbohydrate metabolism, stress responses, cell division, and extracellular functions. Several of the genes we identified are homologous to human genes that are differentially regulated in response to metabolic diseases, suggesting that there may be conserved gene expression responses between C. elegans supplemented with glucose and a diabetic and/or obese state observed in humans. These findings support the utility of C. elegans to model specific aspects of the T2D disease process (e.g., glucose-induced sensitivity to oxygen deprivation) and identify potentially novel regulators of common complications seen in hyperglycemic and T2D patients (e.g., macrovascular complications).

Regulation of gene expression is an essential process for all living organisms. Transcriptional regulation, associated with chromatin, is governed by: (1) DNA sequence, which creates regulatory sites (promoters, enhancers and silencers), where sequence motifs and features (e. g. CpG) can attract transcription factors (TFs) and influence chromatin structure or RNA polymerase II (Pol II) binding, initiation and elongation; (2) non-sequence, epigenetic factors - histone modifications, TF binding, chromatin remodelling (histone placement, eviction and reconstitution), and non-coding RNA regulation. These factors interact with each other, creating a complex network of interactions. In this thesis I describe computational studies of heterochromatin factors in regulation of gene and repeat expression, an analysis of active regulatory elements, and global analyses of big datasets in C. elegans. I first show that a team of heterochromatin factors - HPL-2/HP1, LIN-13, LIN-61, LET-418/Mi-2, and H3K9me2 histone methyltransferase MET-2/SETDB1 - collaborates with piRNA and nuclear RNAi pathways to silence repetitive elements and protect the germline. I also found that the TACBGTA motif is particularly enriched on repeats and heterochromatin factors binding sites, and that repeat elements are derepressed in the soma during normal C. elegans ageing. I then describe the work on active regulatory regions. I show that CFP-1/CXXC1 binds CpG dense, nucleosome depleted promoters and, along SET-2, is required for H3K4me3 deposition at these loci. Using expression profiling I determined that the majority of CFP-1 binding targets are not significantly mis-regulated in cfp-1 mutants, but are weakly upregulated in bulk analyses. I also show that CFP-1 functionally interacts with the Sin3S/HDAC complex. In cfp-1 mutant I observed both loss and gain of SIN-3 binding, depending on chromatin context. Finally, I performed a data driven study on a large collection of ChIP-seq profiles using non-parametric sparse factor analyses (NSFA) and compared it to other, unsupervised machine learning algorithms. This study uncovered interactions and structure in genomic datasets. In addition, I present a collection of computational tools and methods I developed to facilitate processing, storage, retrieval, annotation, and analyses of large datasets in genomics.

De acordo com dados da Organização Mundial da Saúde (OMS) estimam-se que os agrotóxicos causam anualmente 70 mil intoxicações agudas e crônicas que evoluem para óbito. Dentre eles, o paraquat (PQ) é o que apresenta maior taxa de mortalidade, sendo responsável por cerca de 13% de todos os casos registrados, principalmente devido a falta de um tratamento efetivo. O principal mecanismo de toxicidade proposto está associado ao ciclo redox do PQ, onde ocorre a formação de espécies reativas (ERs) de oxigênio e nitrogênio, levando ao estresse oxidativo (EO). Na literatura há relatos do uso de antioxidantes para casos de intoxicação do PQ. Dessa maneira, nesse trabalho avaliou-se o uso de melatonina associada a nanocápsulas de núcleo lipídico (Mel-LNC) na proteção contra os danos causados pelo PQ, uma vez que o uso da nanotecnologia melhorou a atividade antioxidante dessa molécula. Para tal utilizou-se o sistema in vitro, linhagem celular de adenocarcinoma pulmonar (A549), e o modelo alternativo in vivo, Caenorhabditis elegans. Mel-LNC e nanocápsulas de núcleo lipídico (LNC) foram preparadas de acordo com o método de deposição do polímero pré-formado. Ambas as formulações foram caracterizadas avaliando tamanho de partícula, potencial zeta e pH, e para Mel-LNC foram determinadas a concentração de melatonina e porcentagem de encapsulação. Os resultados encontrados estão de acordo com os parâmetros já validados para essas formulações. Foi possível verificar que as formulações MEL-LNC e LNC se mantiveram estáveis nos meios de cultura utilizados nos ensaios in vitro e in vivo. No estudo in vitro foi observado que o tratamento com ambas as formulações não causaram diminuição da viabilidade nem dano de DNA na linhagem celular utilizada. Além disso, foi verificado a internalização da Mel-LNC utilizando-se a formulação marcada com rodamina B, sendo possível verificar uma intensa fluorescência vermelha ao redor do núcleo da célula. O pré-tratamento com Mel-LNC foi capaz de aumentar a viabilidade celular e diminuir o dano oxidativo de DNA causado pelo paraquat após 24 horas de exposição, porém isso não ocorreu quando as células foram pré-tratadas com melatonina livre. No estudo com o modelo alternativo C. elegans, foi utilizada uma formulação de Mel-LNC marcada com rodamina B (Mel-LNC-RoB), a fim de verificar a absorção dessa formulação pelo nematoide. Foi possível observar que a internalização da Mel-LNC no C. elegans ocorre principalmente pela via oral, uma vez que se verificou uma intensa fluorescência no intestino do nematoide após o tratamento com a Mel-LNC-RoB e após três horas, essa fluorescência se distribuiu pelo restante do corpo, apresentando inúmeros pontos de fluorescência fora do intestino. Com relação à avaliação do efeito protetor nesse modelo alternativo in vivo, pode-se inferir que o pré-tratamento com Mel-LNC aumentou a sobrevida, diminuiu a produção de espécies reativas (ERs) e manteve o desenvolvimento normal dos nematoides após a exposição ao PQ, sendo que isso não foi verificado quando os mesmos foram pré-tratados com melatonina livre. Além disso, verificou-se que as nanocápsulas de núcleo lipídico (LNC) são seguras para o uso no modelo C. elegans, uma vez que apresentou alto valor para a dose letal 50 (DL50), e alterações no desenvolvimento e produção de ERs somente ocorreram em doses mais elevadas que as utilizadas em nossos experimentos. Dessa maneira, a formulação de Mel-LNC mostrou-se um promissor candidato para estudos futuros nos casos de intoxicação por paraquat. / According to estimations by World Health Organization (WHO), pesticides are responsible for 70 thousand acute intoxication cases that lead to death per year. Among these compounds, paraquat (PQ) presents the highest mortality rate, about 13% of all registered cases, especially for the lack of effective treatment. The major mechanism of toxicity proposed is associated to its redox cycle, in which oxygen and nitrogen reactive species (RS) are generated culminating in oxidative stress (OS). Some reports in the literature support the use of antioxidants for PQ intoxication cases. The present study aimed to evaluate the use of melatonin-loaded lipid-core nanocapsules (Mel-LNC) in the protection against PQ-induced damages, considering that nanotechnology has improved the antioxidant activity of this molecule. For this purpose, an in vitro system composed by lung adenocarcinoma (A549) cell line, and the in vivo alternative model of Caenorhabditis elegans have been utilized. Mel-LNC and unloaded lipid-core nanocapsules were prepared by self-assembly and characterized by particle sizing, zeta potential and pH, and for Mel-LNC formulation it was determined the drug content and encapsulation efficiency. The results are in agreement with the parameters already validated for these formulations. It was possible verify that Mel-LNC and LNC formulations remained stable in the culture medium utilized in in vitro and in vivo experiments. Results from in vitro studies showed that none of the formulations induced reduction in cell viability or DNA damage in treated cells. Besides, it was observed the internalization of Mel-LNC marked with rhodamine B, showing an intense red fluorescence around the cell nucleus. Pretreatment with Mel-LNC was able to enhance cell viability and diminish DNA oxidative damage caused by paraquat after 24h exposure, which could not be observed when cells were pretreated with Mel. In the study with the alternative model C. elegans, a rhodamine (Ro)-linked Mel-LNC formulation was prepared in order to assess the absorption of the formulation by the nematode. Mel-LNC uptake in C. elegans was found to occur mainly by the oral route, once an intense fluorescence was observed in the intestine after treatment with Mel-LNC-RoB, which after 3h distributed to the rest of the body, presenting numerous fluorescence dots outside the intestine. In relation to the evaluation of protection with the in vivo alternative model, results indicate that pretreatment with Mel-LNC increased survival rate, reduced the production of reactive species and maintained the normal development of nematodes after paraquat exposure, while the same observations were not found after pretreatment with free melatonin. In addition, the lipid-core nanocapsules (LNC) were found to be safe in the C. elegans model, due to its high lethal dose (LD50) value, and development alterations and RS production only occurred in the higher doses than those utilized in our experiments. Therefore, the Mel-LNC formulation demonstrated to be a promising candidate for future studies aiming treatment of paraquat intoxication cases.

The advent of sexual reproduction in early evolutionary history had profound effects on the evolution of animals. In most sexually reproducing species, males and females have distinct morphological and behavioral differences that are shaped by the evolutionary imperatives of each sex. Underlying the behavioral differences between males and females are distinct and measurable dimorphisms in the nervous system. These dimorphisms can arise in the form of connectivity, neurotransmitter usage, gene expression or combinations of all three. The androdioecious nematode Caenorhabditis elegans, with its stereotyped development and simple nervous system, offers a remarkably powerful system for studying the conserved mechanisms of sex determination that shape neural development. In this thesis, I present my work on the characterization of several genes that regulate the development of sexual dimorphisms in the nervous system. The first part of the thesis concerns the characterization of the gene ham-3, which codes for a subunit of the C. elegans ortholog of the SWI/SNF chromatin remodeling complex. ham-3 is required for the proper terminal differentiation of the HSN, a serotonergic neuron of the sex-specific nervous system, which it manages by regulating the expression of transcription factors required for crucial steps of migration, axon guidance and serotonergic fate adoption. The second part of the thesis concerns the investigation of sexually dimorphic pruning mechanisms. I show that unc-6/Netrin is subject to direct transcriptional repression in hermaphrodites by tra-1, the master transcriptional regulator of sexual fate determination in C. elegans. This regulation is required for the proper timing of the sexually dimorphic pruning of synapses in the tail region in hermaprhodites. In males, where unc-6 is not repressed by tra-1, unc-6 expression perdures into adulthood and the synapse is maintained. Together, these data provide insight into the ways in which conserved genetic and developmental mechanisms manage the generation differentiation, connectivity, and maintenance of sexually dimorphic nervous systems.

Resumo: A mamona pode ser utilizada para mais de 700 finalidades diferentes, porém a sua toxidez é o limitante principalmente para o uso restrito da torta originada após a extração do óleo. Para as análises utilizou-se um organismo com o modo de reação a medicamentos e toxinas semelhante ao ser humano, o nematóide Caenorhabditis elegans, o qual tem sido amplamente utilizado pela indústria farmacêutica. O trabalho teve inicio com ensaios preliminares os quais se utilizaram culturas de C. elegans. Estas foram expostas às toxinas que foram colocadas em pequenas cavidades no meio de cultura, porém, devido à falta de praticidade do método, à difícil leitura e sua degradação pela E. coli, passou-se a realizar os testes em placas de 24 poços transparentes contendo apenas água, o nematóide e a toxina. Os resultados mostraram que o teste utilizando placas de 24 poços para exposição do nematóide, e a extração feita através da homogeneização, seguida por banho-maria seguida por centrifugação se mostrou eficiente para medir a ricina sendo semelhantes aos obtidos pelos testes de radioimunodifusão e Elisa, testes bastante específicos, porém de custo mais elevado. O presente trabalho teve por objetivo desenvolver um bioensaio para quantificar a ricina tóxica da mamona, pois a relação entre as análises realizadas por diferentes métodos de quantificação existentes, nem sempre refletem a toxidez real, podendo ocorrer que sementes analisadas por estes métodos, apresentem menor teor de ricina, embora sejam mais tóxicas do que outras sementes que tenham maior teor de ricina quando analisada pelo método. Isto se deve aos métodos empregados que medem além da ricina o RCA Ricinus Communis Aglutimina, um composto menos tóxico do que a ricina pura. / Abstract: The castor oil can be used to 700 different products but its toxicity limits mainly the use of the castor bean cake, the product you have after extract the oil. The present reseach developed a bioassay to quantify the ricin content on castor bean seed because the relationship between the analyses performed by different quantifying methods not always reflect the actual toxicity, witch can occur that seeds analysed by these methods have lower ricin levels although are more toxic than other seeds, because when it test not only the ricin but also the complex ricin + RCA Ricinus Communis Algutimin is measured and the RCA is less toxic than the pure ricin. That is why it was used an organism that has similarities in the way the human body reacts to drugs and toxin, choosing to use the Caenorhabditis elegans that has been used to the pharmaceutical industry. This assay started with preliminary assays using C. elegans colonies that were exposed to the toxins placed in small holes did in the media , but it was hard to read and the E. coli degradation, the method changed to the 24 well plates with water, nematode and the ricin. The results showed the method is efficient to measure ricin and very similar to the radio-imuno-diffusion and the Elisa, very specific tests, but expensive with some operational problems. / Orientador: Maurício Dutra Zanotto / Coorientador: Dick Auld / Banca: Rogério Peres Soratto / Banca: Mirina Luiza Myczkowski / Banca: Tammy Aparecida Manabe Kiihl / Banca: José Geraldo Carvalho do Amaral / Doutor

Wnt signalling is indispensible for proper development of organisms and maintaining of adult tissue homeostasis. Its disruption often leads to disease. In nematode Caenorhabditis elegans, Wnt signalling governs vast array of developmental processes, among others also migration of the Q neuroblasts and their descendants. The sole Wnt acting in this process, EGL-20, triggers the canonical β-catenin Wnt signal transduction pathway in QL but not in QR which leads to QL remaining in the posterior while the QR migrates anteriorly. This represents a useful tool for studying Wnt signalling. Recently, mutation of gene cup-4 was found to disrupt migration of the QL neuroblast in a small proportion of the mutant population. cup-4 encodes a ligand-gated ion channel family homologue and it was shown to participate in endocytosis by coelomocytes, specialized phagocytic cells in the C. elegans body cavity. Here, I present the results of my effort to determine the place of CUP-4 action in Wnt signalling and to elucidate the mechanism of its function. I found that CUP-4 acts upstream of PRY- 1/Axin, which is involved in signal transduction in signal receiving cells, and most probably downstream of adaptin AP2, which is important for recycling of Wnt cargo receptor Wntless (Wls) in Wnt producing cell. cup-4 also...

Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2016-04-08T14:59:25Z No. of bitstreams: 1 Daiandra de Almeida Fagundez.pdf: 882174 bytes, checksum: 222c1532958a789b40194f55ea6493d1 (MD5) / Made available in DSpace on 2016-04-08T14:59:26Z (GMT). No. of bitstreams: 1 Daiandra de Almeida Fagundez.pdf: 882174 bytes, checksum: 222c1532958a789b40194f55ea6493d1 (MD5) Previous issue date: 2014-06-27 / Ferro (Fe) é um metal importante para a homeostase do organismo e existe em abundância no ambiente. Níveis moderados de Fe obtidos a partir de alimentos são necessários para a fisiologia celular normal; no entanto, os níveis elevados de Fe(II)/Fe(III) podem causar efeitos citotóxicos através de redução de H2O2 a radical hidroxil (OH •), fenômeno conhecido como Reação de Fenton. Mesmo sendo amplamente utilizado os efeitos efeitos tóxicos do ferro não são bem compreendidos. Buscando modelos experimentais alternativos que possam substituir e oferecer novas possibilidades de ensaios de toxicidade de xenobióticos, o nematoide Caenorhabditis elegans tem sido utilizado como um organismo bioindicador valioso. Assim, este estudo avaliou os efeitos tóxicos de Fe usando C. elegans analisando diferentes parâmetros, a fim de contribuir para a investigação da toxicidade induzida por Fe e validar este modelo visando, em última instância, a busca de alvos terapêuticos mais eficazes do que aqueles usado atualmente. Nosso estudo descreveu que a DL50 Fe em exposição aguda (30min) foi de 1.2 mM. Doses subletais de Fe diminuíram significativamente o tempo de vida dos vermes e sua capacidade reprodutiva em comparação com vermes não-expostos. Também foi observado que os animais expostos ao Fe diminuem a atividade locomotora e a sensibilidade mecânica, o que sugere uma possível disfunção do sistema nervoso. Alterações na expressão de importantes enzimas antioxidantes e o aumento da peroxidação lipídica sugerem que o estresse oxidativo leva a danos neuronais, que podem ser a causa do comportamento alterado e dos demais efeitos encontrados. / Iron (F e) is an important metal to the organism homeostasis and exists abundantly in the environment. Moderate levels of Fe obtained from food are necessary for normal cell physiology; however, abnormally high levels of Fe(II)/Fe(III) can be cytotoxic effects via reducing H2O2 to the highly cytotoxic hydroxyl radical (OH•) (Fenton catalysis). Consequently leading to oxidative stress. Fe is ubiquitous toxicant in the environment and also widely used in food products, however its effects to the nervous system is not well understood. Seeking for alternative experimental models that may substitute and offer new possibilities to assay xenobiotics toxicity, the nematode Caenorhabditis elegans has been found favorable as a valuable bioindicator organism. Hence, this study evaluated the toxic effects of Fe using C. elegans and investigating different parameters in order to contribute to the investigation of Fe-induced toxicity and to validate this model aiming, ultimately, the search for therapeutic targets that are more effective than those currently used. Our study depicted that the Fe LD50 in acute exposure (30min) was 1.2 mM, as we verified that worms can uptake this metal. Furthermore, sublethal Fe concentrations decreased significantly the worms lifespan and brood size compared to non-exposed worms. We also observed that animals exposed to Fe showed decreased locomotor activity and decreased mechanic sensitivity, which suggests possible dysfunction of the nervous system. In agreement, we found cholinergic and dopaminergic alterations in the worms. In summary, we suggest that iron exposure leads to damage of certain neurons, which could be the cause of altered behavior and of the defects of reproduction.