The Effect of Fat Intake with Increased Omega-6-to-Omega-3 Polyunsaturated Fatty Acid Ratio in Animal Models of Early and Late Alzheimer's Disease-like Pathogenesis.

This work aims to clarify the effect of dietary polyunsaturated fatty acid (PUFA) intake on the adult brain affected by amyloid pathology. McGill-R-Thy1-APP transgenic (Tg) rat and 5xFAD Tg mouse models that represent earlier or later disease stages were employed. The animals were exposed to a control diet (CD) or an HFD based on corn oil, from young (rats) or adult (mice) ages for 24 or 10 weeks, respectively. In rats and mice, the HFD impaired reference memory in wild-type (WT) animals but did not worsen it in Tg, did not cause obesity, and did not increase triglycerides or glucose levels. Conversely, the HFD promoted stronger microglial activation in Tg vs. WT rats but had no effect on cerebral amyloid deposition. IFN-γ, IL-1ß, and IL-6 plasma levels were increased in Tg rats, regardless of diet, while CXCL1 chemokine levels were increased in HFD-fed mice, regardless of genotype. Hippocampal 3-nitrotyrosine levels tended to increase in HFD-fed Tg rats but not in mice. Overall, an HFD with an elevated omega-6-to-omega-3 ratio as compared to the CD (25:1 vs. 8.4:1) did not aggravate the outcome of AD regardless of the stage of amyloid pathology, suggesting that many neurobiological processes relevant to AD are not directly dependent on PUFA intake.

Longterm Increased S100B Enhances Hippocampal Progenitor Cell Proliferation in a Transgenic Mouse Model.

(1) The neurotrophic protein S100B is a marker of brain injury and has been associated with neuroregeneration. In S100Btg mice rendering 12 copies of the murine S100B gene we evaluated whether S100B may serve as a treatment option. (2) In juvenile, adult, and one-year-old S100Btg mice (female and male; n = 8 per group), progenitor cell proliferation was quantified in the subgranular zone (SGZ) and the granular cell layer (GCL) of the dentate gyrus with the proliferative marker Ki67 and BrdU (50 mg/kg). Concomitant signaling was quantified utilizing glial fibrillary acidic protein (GFAP), apolipoprotein E (ApoE), brain-derived neurotrophic factor (BDNF), and the receptor for advanced glycation end products (RAGE) immunohistochemistry. (3) Progenitor cell proliferation in the SGZ and migration to the GCL was enhanced. Hippocampal GFAP was reduced in one-year-old S100Btg mice. ApoE in the hippocampus and frontal cortex of male and BDNF in the frontal cortex of female S100Btg mice was reduced. RAGE was not affected. (4) Enhanced hippocampal neurogenesis in S100Btg mice was not accompanied by reactive astrogliosis. Sex- and brain region-specific variations of ApoE and BDNF require further elucidations. Our data reinforce the importance of this S100Btg model in evaluating the role of S100B in neuroregenerative medicine.

Análise de fenótipos de resistência e suscetibilidade ao desenvolvimento de encefalomielite autoimune experimental: Importância do background genético no delineamento experimental de um estudo

Despite advances in science and technology in the search for alternative methods to replace animals in research, they are still indispensable for the evolution of scientific research and public health. For the refinement of research in animals, several models and genetic editing techniques were developed, which allow changes in the characteristics or properties of living organisms, generating reliable models of human systems and diseases in animals, contributing to the elucidation of illnesses mechanism and treatment. Experimental models developed through bidirectional genetic selection are valuable tools for the study of gene expression and modulation of multifactorial characters, allowing the concentration of genes of interest to the phenotypic character studied. The Experimental Autoimmune Encephalomyelitis (EAE) model is widely used for a better understanding of the mechanisms involved in the development and progression of Multiple Sclerosis, a currently uncurable disease. This project aims to evaluate the importance of genetic background in the development of EAE, in strains genetically selected for maximum (AIRmax) and minimum (AIRmin) inflammatory response. The results demonstrate that the AIRmax animals are susceptible to the disease, as well as the strain classically used in the literature to develop the EAE model, C57BL/6. The AIRmin animals do not develop any clinical motor alterations, confirming the resistance factor of this strain to the development of EAE. Global genetic analysis showed that signaling pathways related to this disease are inhibited in AIRmin animals. Thus, we can suggest that these pathways play a key role in the development of EAE, and these animals could be used to assess the importance of these pathways and the modulating genes involved in this process. Given the importance of the genetic background for the reduction and refinement of the animals use, we can suggest that the collaborative work between biotherists and researchers can be extremely relevant for a scientific project experimental design.

Apesar dos avanços da ciência e tecnologia na busca de métodos alternativos para substituição dos animais na pesquisa, estes ainda são indispensáveis para a evolução da saúde pública. Para o refinamento das pesquisas foram desenvolvidas diversos modelos e técnicas de edição genética, que permitem alterações de características ou propriedades dos organismos vivos, gerando modelos fidedignos de sistemas e doenças humanas em animais, que contribuem para a elucidação do mecanismo e tratamento de doenças. Modelos experimentais desenvolvidos através de seleção genética bidirecional são ferramentas valiosas para o estudo da expressão e modulação gênica de caracteres multifatoriais, permitindo concentrar os genes de interesse ao caráter fenotípico estudado. O modelo de Encefalomielite Autoimune Experimental (EAE) é um modelo animal amplamente utilizado para uma melhor compreensão dos mecanismos de desenvolvimento e progressão da Esclerose Múltipla, doença atualmente sem cura. Este projeto objetiva avaliar a importância do background genético no desenvolvimento da EAE, em linhagens geneticamente selecionadas para máxima (AIRmax) e mínima (AIRmin) resposta inflamatória aguda. Os resultados demonstram que os animais AIRmax apresentam suscetibilidade à doença, assim como a linhagem classicamente utilizada na literatura para desenvolvimento do modelo de EAE, C57BL/6. Já a linhagem AIRmin não desenvolve nenhuma alteração clínica motora, confirmando o fator de resistência desta seleção ao desenvolvimento de EAE. A análise global gênica demostrou que vias de sinalização relacionadas a esta doença estão inibidas nos animais AIRmin. Assim, podemos sugerir que estas vias têm um papel fundamental no desenvolvimento da EAE, e estes animais poderiam ser utilizados para avaliar a importância destas vias e de genes moduladores deste processo. Dada a importância do background genético para a redução e refinamento da utilização de animais, podemos sugerir que o trabalho colaborativo entre bioteristas e pesquisadores pode ser de extrema relevância para um delineamento/desenho experimental de um projeto científico.

Mucin 2 (MUC2) promoter characterization: an overview.

Transgenic livestock have been studied with a well-known interest in improving quantitative and qualitative traits. In order to direct heterologous gene expression, it is indispensable to identify and characterize a promoter suitable for directing the expression of the gene of interest (GOI) in a tissue-specific way. The gastrointestinal tract is a desirable target for gene expression in several mammalian models. Throughout the surface of the intestinal epithelium, there is an intricate polymer network, formed by gel-forming mucins (especially MUC2 and MUC5AC, of which MUC2 is the major one), which plays a protective role due to the formation of a physical, chemical and immunological barrier between the organism and the environment. The characterization of the gel-forming mucins is difficult because of their large size and repetitive DNA sequences and domains. The main mucin in the small and large intestine, mucin 2 (MUC2), is expressed specifically in goblet cells. MUC2 plays an important role in intestinal homeostasis and its disruption is associated with several diseases and carcinomas. This mucin is also an important marker for elucidating mechanisms that regulate differentiation of the secretory cell lineage. This review presents the state of the art of MUC2 promoter structure and functional characterization.

Gene Manipulation Strategies to Identify Molecular Regulators of Axon Regeneration in the Central Nervous System.

Limited axon regeneration in the injured adult mammalian central nervous system (CNS) usually results in irreversible functional deficits. Both the presence of extrinsic inhibitory molecules at the injury site and the intrinsically low capacity of adult neurons to grow axons are responsible for the diminished capacity of regeneration in the adult CNS. Conversely, in the embryonic CNS, neurons show a high regenerative capacity, mostly due to the expression of genes that positively control axon growth and downregulation of genes that inhibit axon growth. A better understanding of the role of these key genes controlling pro-regenerative mechanisms is pivotal to develop strategies to promote robust axon regeneration following adult CNS injury. Genetic manipulation techniques have been widely used to investigate the role of specific genes or a combination of different genes in axon regrowth. This review summarizes a myriad of studies that used genetic manipulations to promote axon growth in the injured CNS. We also review the roles of some of these genes during CNS development and suggest possible approaches to identify new candidate genes. Finally, we critically address the main advantages and pitfalls of gene-manipulation techniques, and discuss new strategies to promote robust axon regeneration in the mature CNS.

Animal models of hyperandrogenism and ovarian morphology changes as features of polycystic ovary syndrome: a systematic review.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder, affecting 9-18% of women in reproductive age that causes hyperandrogenism and infertility due to dysfunctional follicular maturation and anovulation. The etiology of PCOS is still poorly known, and information from experimental animal models may help improve current understanding of the mechanisms of PCOS initiation and development. Therefore, we conducted a systematic review of currently available methods for simulation of PCOS in experimental models, focusing on two main endocrine traits: ovarian morphology changes and circulating levels of sex hormones and gonadotropins.We searched the MEDLINE database for articles in English or Spanish published until October 2016. Of 933 studies identified, 39 were included in the systematic review. One study compared interventions with androgens versus estrogens, 18 used androgen-induced stimulation, 9 used estrogens or drugs with estrogen action, including endocrine disruptors, to induce PCOS-like models, and 12 used miscellaneous interventions. Broad differences were found among the studies concerning hormonal interventions, animal species, and developmental stage at the time of the experiments, and most models resulted in ovarian morphology changes, mainly increases in the number of cystic and antral follicles and decreases in the corpus luteum. Hyperandrogenism was produced by using androgens and other drugs as the stimulatory agent. However, studies using drugs with estrogenic effect did not observe changes in circulating androgens.In conclusion, medium- or long-term testosterone administration in the pre- and postnatal periods performed best for induction of a PCOS-like phenotype, in rhesus macaque and rat models respectively. In rats, postnatal exposure to androgens results in reprogramming of the hypothalamic-pituitary-ovarian-axis. Thus, comparisons between different intervention models may be useful to define the timing of reproductive PCOS phenotypes in experimental animal models.

Evolution of transcriptional enhancers and animal diversity.

Deciphering the genetic bases that drive animal diversity is one of the major challenges of modern biology. Although four decades ago it was proposed that animal evolution was mainly driven by changes in cis-regulatory DNA elements controlling gene expression rather than in protein-coding sequences, only now are powerful bioinformatics and experimental approaches available to accelerate studies into how the evolution of transcriptional enhancers contributes to novel forms and functions. In the introduction to this Theme Issue, we start by defining the general properties of transcriptional enhancers, such as modularity and the coexistence of tight sequence conservation with transcription factor-binding site shuffling as different mechanisms that maintain the enhancer grammar over evolutionary time. We discuss past and current methods used to identify cell-type-specific enhancers and provide examples of how enhancers originate de novo, change and are lost in particular lineages. We then focus in the central part of this Theme Issue on analysing examples of how the molecular evolution of enhancers may change form and function. Throughout this introduction, we present the main findings of the articles, reviews and perspectives contributed to this Theme Issue that together illustrate some of the great advances and current frontiers in the field.

Animales transgénicos: usos y limitaciones en la medicina del siglo XXI / Transgenic animals: uses and limitations in the 21st century medicine

Uno de los avances biotecnológicos más importantes de las últimas décadas fue el desarrollo de los animales transgénicos. En este artículo seanaliza por qué los animales transgénicos son excelentes modelos para estudiar la función y regulación de los genes y para buscar nuevas estrategias terapéuticas para las enfermedades humanas. Se discute su uso como biorreactores para producir productos farmacológicos para el tratamiento de enfermedades y la posibilidad de generar cerdos transgénicos como fuente alternativa a la donación de órganos.(AU)

One of the most important advances in biotechnology during the last decades was the development of transgenic animals. In this article, I discuss why transgenic animals are excellentmodels to analyze gen function and regulation, and to look for new therapeutic strategies for human diseases. Moreover, their use as bioreactors to produce pharmaceutical products for the treatment of human diseases, and the possibility of generating transgenic pigs as analternative source of organ donors for humans is also discussed.(AU)

Animales transgénicos: usos y limitaciones en la medicina del siglo XXI / Transgenic animals: uses and limitations in the 21st century medicine

Uno de los avances biotecnológicos más importantes de las últimas décadas fue el desarrollo de los animales transgénicos. En este artículo seanaliza por qué los animales transgénicos son excelentes modelos para estudiar la función y regulación de los genes y para buscar nuevas estrategias terapéuticas para las enfermedades humanas. Se discute su uso como biorreactores para producir productos farmacológicos para el tratamiento de enfermedades y la posibilidad de generar cerdos transgénicos como fuente alternativa a la donación de órganos.

One of the most important advances in biotechnology during the last decades was the development of transgenic animals. In this article, I discuss why transgenic animals are excellentmodels to analyze gen function and regulation, and to look for new therapeutic strategies for human diseases. Moreover, their use as bioreactors to produce pharmaceutical products for the treatment of human diseases, and the possibility of generating transgenic pigs as analternative source of organ donors for humans is also discussed.

Transfection of Gametes: A Method to Generate Transgenic Animals / Transfección de Gametos: Un Método para Generar Animales Transgénicos

The production of transgenic animals (TA) using transfected spermatozoa or eggs is commented. Different methods have been employed to introduce transgenes into the gametes of several vertebrates and invertebrates. Methods for the transfection of gametes have employed naked DNA, viral vectors, DNA/Liposome complexes, electroporation or high velocity microprojectiles. Spermatozoa and oocytes or eggs have showed a good transfection efficience (80% in some cases), and microscopical observations demonstrated that the transgenes appeared localized in the nucleus. Gametes have shown to be naturally protected against the entrance of foreign genes because some semino plasma or plasma membrane proteins block the entrance of foreign genes in spermatozoa. In the female this blockage is undertaken by the egg covers (the zona pellucida in mammals and the perivitelline coat in mollusks). In several cases the production of TA has been described after using the transfected gametes for in vitro fertilization or inseminations. Sometimes, larger percentages of TA were observed (85% in salmon). Nevertheless, these TA were mainly chimeric for the transgene and they were not capable to establish transgenic lines. It seems probable that TA produced by gamete transfections are different from those originated by the conventional microinjection procedures. Furthermore, gametes would develop some kind of mechanisms that modify the integration/expression of transgenes, or that block the integration of transgenes in the germinal line.

Se comentan algunos aspectos sobre la transfección de gametos y su empleo para la producción de animales transgénicos (AT). Para la transfección de gametos han sido empleados ADN desnudo, vectores virales, complejos ADN-Liposomas, electroporación, o microproyectiles de alta velocidad. En general, se han obtenido altos porcentajes de transfección (hasta del 80% en espermatozoides) y se ha observado que los transgenes se localizan en el interior del núcleo. Se ha constatado que los gametos están naturalmente protegidos frente a la entrada de genes extraños: en espermatozoides esta función la cumplen diversas proteínas presentes en los fluidos seminales o en su membrana plasmática; mientras que en los gametos femeninos son las envolturas del huevo (zona pelúcida en mamíferos o membrana perivitelina en moluscos) las que desarrollan esta labor. En muchos casos, los gametos transfectados se han utilizado en fecundaciones in vitro o en inseminaciones a fin de crear AT. En algunos casos, los porcentajes de estos AT han sido altos, como en el salmón (85%). Pero los AT, así creados, han sido en su mayoría quimeras y no han sido capaces de producir líneas transgénicas. Se sugiere que los AT producidos por gametos transfectados, son diferentes a los producidos por el método convencional de microinyección. Es probable que los gametos posean mecanismos, aún no descritos, capaces de modificar la integración/expresión de los transgenes, o que impedirían la integración de los transgenes en la línea germinal.