Heavy Metals Need Assistance: The Contribution of Nicotianamine to Metal Circulation Throughout the Plant and the Arabidopsis NAS Gene Family

Understanding the regulated inter- and intra-cellular metal circulation is one of the challenges in the field of metal homeostasis. Inside organisms metal ions are bound to organic ligands to prevent their uncontrolled reactivity and to increase their solubility. Nicotianamine (NA) is one of the important ligands. This non-proteinogenic amino acid is synthesized by nicotianamine synthase (NAS). NA is involved in mobilization, uptake, transport, storage, and detoxification of metals. Much of the progress in understanding NA function has been achieved by studying mutants with altered nicotianamine levels. Mild and strong Arabidopsis mutants impaired in nicotianamine synthesis have been identified and characterized, namely nas4x-1 and nas4x-2. Arabidopsis thaliana has four NAS genes. In this review, we summarize the structure and evolution of the NAS genes in the Arabidopsis genome. We summarize previous results and present novel evidence that the four NAS genes have partially overlapping functions when plants are exposed to Fe deficiency and nickel supply. We compare the phenotypes of nas4x-1 and nas4x-2 and summarize the functions of NAS genes and NA as deduced from the studies of mutant phenotypes

The role of nicotianamine in the metal homeostasis of Arabidopsis thaliana

The non-proteinogenic amino acid nicotianamine (NA)chelates and transports essential metal ions in plants. The enhancing effect of NA on the bioavailability of metals makes it appealing for biofortification approaches. The goal of this project was the localization of NA activity and the elucidation of a concrete function of NA in Fe and Cu translocation throughout the plant using the model plant Arabidopsis thaliana. Arabidopsis has four NICOTIANAMINE SYNTHASE (NAS) genes. To investigate NA function two quadruple nas mutants, named nas4x-1 and nas4x-2 were analyzed to study NA function in Arabidopsis: nas4x-2 had a full loss of NAS function, was sterile, and suffered from severe chlorosis in young leaves. nas4x-1 had residual NA contents, was still fertile and developed a interveinal leaf chlorosis upon transition from vegetative to reproductive stage. The obtained results indicate that NA participates in the phloem-dependent Fe transport and in the phloem- and xylem-dependent Cu transport in plants. Thereby NA has a distinct function in the phloem unloading process of metals in young growing tissues, reproductive floral organs and seeds. Moreover, NA is required for the remobilization of metals from old leaves to the inflorescence. These findings are fundamental for plant manipulation approaches to increase the amount of bioavailable Fe in seeds through the genetic modification of the NAS genes.Die nicht-proteinogene Aminosäure Nikotianamin (NA)chelatiert und transportiert essentielle Metallionen in Pflanzen. NA hat einen positiven Effekt auf die Bioverfügbarkeit von Metallen und ist deshalb ein attraktives Ziel zur genetischen Modifikation in der Herstellung von verbesserten Kulturpflanzen. Hauptziel dieser Arbeit war die genaue Lokalisierung der NA Aktivität und die Entdeckung ihrer konkreten Funktionen im Fe und Cu Haushalt der Pflanze. Arabidopsis hat vier NICOTIANAMINE SYNTHASE (NAS) Gene. Die Funktion von NA wurde anhand von zwei vierfach nas Mutanten, nas4x-1 und nas4x-2, untersucht. Die fertile nas4x-1 Mutante hatte detektierbare, jedoch stark reduzierte NA Gehalte, was sich in der Entwicklung einer intervenalen Blattchlorose beim Wechsel vom vegetativen zum reproduktiven Wachstumsstadium äußerte. Die NA-freie nas4x-2 Mutante dagegen war steril und entwickelte eine starke intervenale Blattchlorose in jungen Blättern. Die Ergebnisse dieser Arbeit haben gezeigt, dass NA eine wichtige Rolle im Phloem-Fe-Transport und im Phloem- und Xylem-Cu-Transport spielt. Dabei hat NA eine konkrete Funktion in der Phloementladung von Metallen in jungen, wachsenden Geweben, in reproduktiven Blütenorganen und in Samen. Darüber hinaus wird NA in der Remobilisierung von Metallen aus Blättern zur Fe und Cu Versorgung der Infloreszenz gebraucht. Diese Erkenntnisse sind fundamental für die Verbesserung der Fe Bioverfügbarkeit in Samen durch die genetische Modifikation der NAS Gene

Transcriptome analysis by GeneTrail revealed regulation of functional categories in response to alterations of iron homeostasis in Arabidopsis thaliana

<p>Abstract</p> <p>Background</p> <p>High-throughput technologies have opened new avenues to study biological processes and pathways. The interpretation of the immense amount of data sets generated nowadays needs to be facilitated in order to enable biologists to identify complex gene networks and functional pathways. To cope with this task multiple computer-based programs have been developed. GeneTrail is a freely available online tool that screens comparative transcriptomic data for differentially regulated functional categories and biological pathways extracted from common data bases like KEGG, Gene Ontology (GO), TRANSPATH and TRANSFAC. Additionally, GeneTrail offers a feature that allows screening of individually defined biological categories that are relevant for the respective research topic.</p> <p>Results</p> <p>We have set up GeneTrail for the use of <it>Arabidopsis thaliana</it>. To test the functionality of this tool for plant analysis, we generated transcriptome data of root and leaf responses to Fe deficiency and the Arabidopsis metal homeostasis mutant <it>nas4x-1</it>. We performed Gene Set Enrichment Analysis (GSEA) with eight meaningful pairwise comparisons of transcriptome data sets. We were able to uncover several functional pathways including metal homeostasis that were affected in our experimental situations. Representation of the differentially regulated functional categories in Venn diagrams uncovered regulatory networks at the level of whole functional pathways. Over-Representation Analysis (ORA) of differentially regulated genes identified in pairwise comparisons revealed specific functional plant physiological categories as major targets upon Fe deficiency and in <it>nas4x-1</it>.</p> <p>Conclusion</p> <p>Here, we obtained supporting evidence, that the <it>nas4x-1 </it>mutant was defective in metal homeostasis. It was confirmed that <it>nas4x-1 </it>showed Fe deficiency in roots and signs of Fe deficiency and Fe sufficiency in leaves. Besides metal homeostasis, biotic stress, root carbohydrate, leaf photosystem and specific cell biological categories were discovered as main targets for regulated changes in response to - Fe and <it>nas4x-1</it>. Among 258 differentially expressed genes in response to - Fe and <it>nas4x-1 </it>five functional categories were enriched covering metal homeostasis, redox regulation, cell division and histone acetylation. We proved that GeneTrail offers a flexible and user-adapted way to identify functional categories in large-scale plant transcriptome data sets. The distinguished feature that allowed analysis of individually assembled functional categories facilitated the study of the <it>Arabidopsis thaliana </it>transcriptome.</p

Maker Movements, Do-It-Yourself Cultures and Participatory Design: Implications for HCI Research

Falling costs and the wider availability of computational components, platforms and ecosystems have enabled the expansion of maker movements and DIY cultures. This can be considered as a form of democratization of technology systems design, in alignment with the aims of Participatory Design approaches. However, this landscape is constantly evolving, and long-term implications for the HCI community are far from clear. The organizers of this one-day workshop invite participants to present their case studies, experiences and perspectives on the topic with the goal of increasing understanding within this area of research. The outcomes of the workshop will include the articulation of future research directions with the purpose of informing a research agenda, as well as the establishment of new collaborations and networks

Neoliberalism and contemporary school: a problematization of the Conta para Mim program

This article, as a theoretical essay, aims do think our present, focusing on the relation between a neoliberal rationality and the decline of the public sense of education. It diagnoses the acceleration, digital media and performativity invading modes of existence of students and teachers based on a consumption logic, high competition, and large-scale assessment guiding the educative process. Thus, it regards, the Program Conta para Mim, linked to the Literacy National Plan (2019) as a strong symptom of the alliance of a neoliberal discourse that fades the public policies and an uplifting neoconservative discourse, producing this rationality that diminishes the potency of literary reading practices at school as a possibility of an exercise of thought and life.Este artigo trata de um ensaio teórico que busca pensar o nosso presente, enfocando nas relações entre uma racionalidade neoliberal e o enfraquecimento do sentido público da educação. Nesse sentido, diagnostica-se a velocidade, as mídias digitais e a performatividade invadindo os modos de existência de alunos e professores em uma lógica de consumo, de superconcorrência e das avaliações em larga escala pautando os processos educativos. Para tanto, considera o Programa Conta para Mim, vinculado ao Plano Nacional de Alfabetização de 2019, como um forte sintoma da aliança entre um discurso neoliberal que enfraquece as políticas públicas e um discurso neoconservador moralizante, produzindo essa racionalidade que diminui a potência das práticas de leitura literária na escola como possibilidade de exercício de pensamento e de vida.Este artículo trata de un ensayo teórico que busca pensar nuestro presente, focalizando en las relaciones entre una racionalidad neoliberal y el enflaquecimiento del sentido público de la educación. En ese sentido, se diagnostica la velocidad, los medios de comunicaciones digitales y la performatividad invadiendo los modos de existencia de los alumnos y de los profesores en una lógica de consumo, de super concurrencia y de las evaluaciones en amplia escala pautando los procesos educativos. Para tanto, considere el Programa Conta para Mim, vinculado al Plano Nacional de Alfabetização de 2019, como un fuerte síntoma da alianza entre un discurso neoliberal que enflaquece las políticas públicas y un discurso neoconservador moralizante, produciendo esa racionalidad que disminuí la potencia de las prácticas de lectura literaria en la escuela como posibilidad de ejercicio de pensamiento y de vida

New findings in eNOS gene and thalidomide embryopathy suggest pre-transcriptional effect variants as susceptibility factors

Antiangiogenic properties of thalidomide have created an interest in the use of the drug in treatment of cancer. However, thalidomide is responsible for thalidomide embryopathy (TE). A lack of knowledge regarding the mechanisms of thalidomide teratogenesis acts as a barrier in the aim to synthesize a safer analogue of thalidomide. Recently, our group detected a higher frequency of alleles that impair the pro-angiogenic mechanisms of endothelial nitric oxide synthase (eNOS), coded by the NOS3 gene. In this study we evaluated variable number tandem repeats (VNTR) functional polymorphism in intron 4 of NOS3 in individuals with TE (38) and Brazilians without congenital anomalies (136). Haplotypes were estimated for this VNTR with previously analyzed polymorphisms, rs2070744 (−786C>T) and rs1799983 (894T>G), in promoter region and exon 7, respectively. Haplotypic distribution was different between the groups (p=0.007). Alleles −786C (rs2070744) and 4b (VNTR), associated with decreased NOS3 expression, presented in higher frequency in TE individuals (p=0.018; OR=2.57; IC=1.2–5.8). This association was not identified with polymorphism 894T>G (p=0.079), which influences eNOS enzymatic activity. These results suggest variants in NOS3, with pre-transcriptional effects as susceptibility factors, influencing the risk TE development. This finding generates insight for a new approach to research that pursues a safer analogue

Association between Genetic Variants in NOS2 and TNF Genes with Congenital Zika Syndrome and Severe Microcephaly

Zika virus (ZIKV) causes Congenital Zika Syndrome (CZS) in individuals exposed prenatally. Here, we investigated polymorphisms in VEGFA, PTGS2, NOS3, TNF, and NOS2 genes as risk factors to CZS. Forty children with CZS and forty-eight children who were in utero exposed to ZIKV infection, but born without congenital anomalies, were evaluated. Children with CZS were predominantly infected by ZIKV in the first trimester (p < 0.001) and had mothers with lower educational level (p < 0.001) and family income (p < 0.001). We found higher risk of CZS due the allele rs2297518[A] of NOS2 (OR = 2.28, CI 95% 1.17–4.50, p = 0.015). T allele and TT/CT genotypes of the TNF rs1799724 and haplotypes associated with higher expression of TNF were more prevalent in children with CZS and severe microcephaly (p = 0.029, p = 0.041 and p = 0.030, respectively). Our findings showed higher risk of CZS due ZIKV infection in the first trimester and suggested that polymorphisms in NOS2 and TNF genes affect the risk of CZS and severe microcephaly