The untapped potential of plant thin cell layers

Thin cell layers (TCLs), which contain a small number of cells or tissues, are explants excised from different organs (stems, leaves, roots, inflorescences, flowers, cotyledons, hypocotyls/epicotyls, and embryos). After almost 45 years of research, this culture system has been used for several monocotyledonous and dicotyledonous plants of commercial importance, and for model plants. The limited amount of cells in a TCL is of paramount importance because marker molecules/genes of differentiation can be easily localized in situ in the target/responsive cells. Thus, the use of TCLs has allowed, and continues to allow, for the expansion of knowledge in plant research in a practical and applied manner into the fields of tissue culture and micropropagation, cell and organ genetics, molecular biology, biochemistry, and development. Starting from a brief historical background, the actual and potential uses of the TCL system are briefly reviewed

Developing College Ready First Generation College Students: Using Student Experiences to Envision a Practicable Approach to Studying and Addressing the Problem

Background: First generation college students, whose parents’ highest earned degree is a high school diploma, go on to earn postsecondary degrees less often than their peers whose parents have a college degree. A current approach to addressing this problem is making sure “first gens” are ready to succeed in college. Purpose: There are three extant bodies of scholarship that are potentially useful to researchers and educators who want to think and reason about first gen college readiness. However, leveraging these literatures is difficult because each focuses on a distinct dimension and fails to precisely define its core concepts. The purpose of this study is to coalesce the literatures into an initial framework and, by putting this framework into dialogue with students’ lived experiences, synthesize and conceptually clarify the research scholarship underlying the framework. Research Design: In this study, I compare five in-depth qualitative case studies of first gen (n = 3) and non-first gen (n = 2) students who attend the same early college program. I collect data through interviews with the students contextualized by interviews with their teachers and advisors. Using structured, focused cross-case comparisons, I discern in what ways the participating first gen students and non-first gen students do and do not differ in how they (a) conceive of college readiness and (b) experience its development. I then map the students’ conceptions onto the framework. Findings: The study’s framework brings together from the literature three dimensions for understanding first gen college readiness: (a) student capacities that constitute readiness as well as the ways that (b) educational contexts and (c) students’ communities affect the development of readiness. These dimensions fit the experiences of the first gens in this study, thereby substantiating the framework’s broad foci. Mapping the first gens’ narratives onto the framework also (a) exemplifies how we can think cohesively about all three dimensions and (b) concretely visualizes the core concepts of each dimension. However, research foregrounding first gens’ transitions to college raise additional critical questions about institutional conceptions of college readiness and the roles such conceptions might play in shaping first gens’ postsecondary experiences. These questions bring attention to: (a) an educational program’s cultural norms that first gen students must adapt to; and (b) the ways in which first gen students make sense of their own cultures and identities as they enter into an educational program’s culture. Implications: The conceptual ideas captured in the resulting framework have the potential to bracket and focus the work of researchers and educators, pointing them to student capacities, contextual elements, and community factors that can be important to understanding first gens’ development of college readiness. And yet, this study also concludes with equally important questions about whose cultural norms drive conceptualizations of college readiness and how colleges can be more culturally and practically ‘student ready’ for first gens.PHDEducational StudiesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163224/1/jdellar_1.pd

EIN2 and COI1 control the antagonism between ethylene and jasmonate in adventitious rooting of Arabidopsis thaliana thin cell layers

Auxins induce adventitious roots (ARs) in numerous culture-systems, and indole-3-butyric acid (IBA) is frequently the best AR-inducer. Vitamin requirements vary according to species, explant, and culture-conditions. Arabidopsis thaliana thin cell layers (AtTCLs) are uncapable of AR-formation on hormone-free medium containing thiamine and myo-inositol, whereas ARs are induced when IBA (10 μM), with/without kinetin (Kin, 0.1 μM), is added. The research frst aim was to determine whether a synergism between IBA and myo-inositol and thiamine was necessary for AR-formation. Results showed that IBA induced AR-formation without myo-inositol and thiamine, but better when both vitamins were also present. Deciphering hormonal action on AR formation under optimal vitamin content would be essential for improving the AR process. Ethylene (ET)/jasmonic acid (JA) signaling cross-talk has been demonstrated as being involved in AR-formation in IBA+Kincultured AtTCLs, by using ein3eil1 and coi1-16 mutants. ETHYLENE INSENSITIVE3 (EIN3)/EIN3-LIKE1 (EIL1) are positive regulators of ethylene (ET)-signaling, whereas CORONATINE INSENSITIVE1 (COI1) is involved in JA-signaling. The ETHYLENE INSENSITIVE2 (EIN2) protein activates EIN3/EIL1 in ET-presence. To understand whether EIN2 was also involved, the AR-response of ein2-1 and coi1-16 TCLs was evaluated adding the ET-precursor 1-aminocyclopropane1-carboxylic acid (ACC, 0.1 μM) and/or the JA-donor methyl jasmonate (JAMe, 0.01 μM) to IBA+vitamins-containing medium. AR-formation was enhanced by JAMe, reduced by ACC, but unchanged by JAMe+ACC in the wild type TCLs, whereas remained similarly low in ein2-1 and coi1-16 under all treatments. Collectively, these results demonstrate that the antagonism between JA and ET in AR-formation from AtTCLs involves a cross-talk by EIN2 and COI1

Indole-3-butyric acid induces ectopic formation of metaxylem in the hypocotyl of Arabidopsis thaliana without conversion into indole-3-acetic acid and with a positive interaction with ethylene

The role of the auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) and of the auxin-interacting phytohormone ethylene, on the ectopic formation of primary xylem (xylogenesis in planta) is still little known. In particular, auxin/ethylene-target tissue(s), modality of the xylary process (trans-differentiation vs. de novo formation), and the kind of ectopic elements formed (metaxylem vs. protoxylem) are currently unknown. It is also unclear whether IBA may act on the process independently of conversion into IAA. To investigate these topics, histological analyses were carried out in the hypocotyls of Arabidopsis wild type seedlings and ech2ibr10 and ein3eil1 mutants, which are blocked in IBA-to-IAA conversion and ethylene signalling, respectively. The seedlings were grown under darkness with either IAA or IBA, combined or not with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. Adventitious root formation was also investigated because this process may compete with xylogenesis. Our results show that ectopic formation of protoxylem and metaxylem occurred as an indirect process starting from the pericycle periclinal derivatives of the hypocotyl basal part. IAA favoured protoxylem formation, whereas IBA induced ectopic metaxylem with ethylene cooperation through the EIN3EIL1 network. Ectopic metaxylem differentiation occurred independently of IBA-to-IAA conversion as mediated by ECH2 and IBR10, and in the place of IBA-induced adventitious root formation

Jasmonic acid methyl ester induces xylogenesis and modulates auxin-induced xylary cell identity with NO Involvement

In Arabidopsis basal hypocotyls of dark-grown seedlings, xylary cells may form from the pericycle as an alternative to adventitious roots. Several hormones may induce xylogenesis, as Jasmonic acid (JA), as well as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) auxins, which also affect xylary identity. Studies with the ethylene (ET)-perception mutant ein3eil1 and the ET-precursor 1-aminocyclopropane-1-carboxylic acid (ACC), also demonstrate ET involvement in IBA-induced ectopic metaxylem. Moreover, nitric oxide (NO), produced after IBA/IAA-treatments, may affect JA signalling and interact positively/negatively with ET. To date, NO-involvement in ET/JA-mediated xylogenesis has never been investigated. To study this, and unravel JA-effects on xylary identity, xylogenesis was investigated in hypocotyls of seedlings treated with JA methyl-ester (JAMe) with/without ACC, IBA, IAA. Wild-type (wt) and ein3eil1 responses to hormonal treatments were compared, and the NO signal was quantified and its role evaluated by using NO-donors/scavengers. Ectopic-protoxylem increased in the wt only after treatment with JAMe(10 μM), whereas in ein3eil1 with any JAMe concentration. NO was detected in cells leading to either xylogenesis or adventitious rooting, and increased after treatment with JAMe(10 μM) combined or not with IBA(10 μM). Xylary identity changed when JAMe was applied with each auxin. Altogether, the results show that xylogenesis is induced by JA and NO positively regulates this process. In addition, NO also negatively interacts with ET-signalling and modulates auxin-induced xylary identity

Nitric oxide alleviates cadmium- but not arsenic-induced damages in rice roots

Nitric oxide (NO) has signalling roles in plant stress responses. Cadmium (Cd) and arsenic (As) soil pollutants alter plant development, mainly the root-system, by increasing NO-content, triggering reactive oxygen species (ROS), and forming peroxynitrite by NO-reaction with the superoxide anion. Interactions of NO with ROS and peroxynitrite seem important for plant tolerance to heavy metal(oid)s, but the mechanisms underlying this process remain unclear. Our goal was to investigate NO-involvement in rice (Oryza sativa L.) root-system after exposure to Cd or As, to highlight possible differences in NO-behaviour between the two pollutants. To the aim, morpho-histological, chemical and epifluorescence analyses were carried out on roots of different origin in the root-system, under exposure to Cd or As, combined or not with sodium nitroprusside (SNP), a NO-donor compound. Results show that increased intracellular NO levels alleviate the root-system alterations induced by Cd, i.e., inhibition of adventitious root elongation and lateral root formation, increment in lignin deposition in the sclerenchyma/endodermis cell-walls, but, even if reducing As-induced endodermis lignification, do not recover the majority of the As-damages, i.e., enhancement of AR-elongation, reduction of LR-formation, anomalous tissue-proliferation. However, NO decreases both Cd and As uptake, without affecting the pollutants translocation-capability from roots to shoots. Moreover, NO reduces the Cd-induced, but not the As-induced, ROS levels by triggering peroxynitrite production. Altogether, results highlight a different behaviour of NO in modulating rice root-system response to the toxicity of the heavy metal Cd and the metalloid As, which depends by the NO-interaction with the specific pollutant

Mabon: l'opensource e il web al servizio dei beni culturali

Progetto - descritto in Linguaggio di Modellazione Unificato (UML2) - di un software per la schedatura e catalogazione del materiale fotografico contenuto presso la Fototeca della Soprintendenza BAPPSAE per le Province di Pisa e Livorno, per il framework Zope3

Cadmium and arsenic affect root development in Oryza sativa L. negatively interacting with auxin

Cadmium (Cd) and arsenic (As), non essential, but toxic, elements for animals and plants are frequently present in paddy fields. Oryza sativa L., a staple food for at least the half of world population, easily absorbs As and Cd by the root, and in this organ the pollutants evoke consistent damages, reducing/modifying the root system. Auxins are key hormones in regulating all developmental processes, including root organogenesis. Moreover, plants respond to environmental stresses, such as those caused by Cd and As, by changing levels and distribution of endogenous phytohormones. Even though the effects of Cd and As on the roots have been investigated in some species, it remains necessary to deepen the knowledge about the cross-talk between these toxic elements and auxin during root formation and development, in particular in agronomically important plants, such as rice. Hence, the research goal was to investigate the interactions between Cd and As, alone or combined, and auxin during the development of rice roots. To reach the aim, morphological, histological and histochemical analyses were carried out on seedlings, exposed or not to Cd and/or As, belonging to the wild type and transgenic lines useful for monitoring indole-3-acetic acid (IAA) localization, i.e., OsDR5:GUS, and IAA cellular influx and efflux, i.e., OsAUX1:GUS and OsPIN5b:GUS. Moreover, the transcript levels of the YUCCA2 and ASA2, IAA biosynthetic genes were also monitored in Cd and/or As exposed wild type seedlings. The results highlight that As and Cd affect cyto-histology and morphology of the roots. In particular, they alter the lateral root primordia organization and development with negative consequences on root system architecture. This is due to a disturbance of IAA biosynthesis and transport, as indicated by the altered expression of both ASA2 and YUCCA2 biosynthetic genes, and AUX1 and PIN5b transporter genes

ESTUDO SOBRE SEGURANÇA E PRIVACIDADE NA INTERNET DAS COISAS (IOT)

The article aims to study security and privacy in the Internet of Things (IoT). A bibliographic research was carried out on the subject and it was observed that IoT evolved rapidly and its applications are used in various areas. The study reveals that often, due to hardware limitations, security and privacy become an obstacle to be overcome in IoT, but with new efforts, such as the creation of standards and rules documents by international organizations, these problems tend to affect their applications less and less.El artículo tiene como objetivo estudiar la seguridad y la privacidad en el Internet de las Cosas (IoT). Se realizó una investigación bibliográfica sobre el tema y se observó que IoT evolucionó rápidamente y sus aplicaciones se utilizan en diversas áreas. El estudio revela que a menudo, debido a las limitaciones de hardware, la seguridad y la privacidad se convierten en un obstáculo a superar en IoT, pero con nuevos esfuerzos, como la creación de estándares y documentos de reglas por parte de organizaciones internacionales, estos problemas tienden a afectar cada vez menos a sus aplicaciones.O artigo tem por objetivo estudar sobre a segurança e a privacidade na Internet das Coisas (IoT). Foi realizada uma pesquisa bibliográfica sobre o tema e observou-se que a IoT evoluiu de forma rápida e suas aplicações são utilizadas em áreas variadas. O estudo revela que muitas vezes, por limitações de hardware, a segurança e privacidade se tornam um obstáculo a ser vencido em IoT, mas, com novos esforços, como a criação de documentos de padrões e regras por parte de organizações internacionais, estes problemas tendem a afetar cada vez menos suas aplicações.O artigo tem por objetivo estudar sobre a segurança e a privacidade na Internet das Coisas (IoT). Foi realizada uma pesquisa bibliográfica sobre o tema e observou-se que a IoT evoluiu de forma rápida e suas aplicações são utilizadas em áreas variadas. O estudo revela que muitas vezes, por limitações de hardware, a segurança e privacidade se tornam um obstáculo a ser vencido em IoT, mas, com novos esforços, como a criação de documentos de padrões e regras por parte de organizações internacionais, estes problemas tendem a afetar cada vez menos suas aplicações

Nitric oxide cooperates with auxin to mitigate the alterations in the root system caused by cadmium and arsenic

Oryza sativa L. is a worldwide food-crop frequently growing in cadmium (Cd)/arsenic (As) polluted soils, with its root-system as the first target of the pollutants. Root-system development involves the establishment of optimal indole-3-acetic acid (IAA) levels, also requiring the conversion of the IAA natural precursor indole-3-butyric acid (IBA) into IAA, causing nitric oxide (NO) formation. Nitric oxide is a stress-signaling molecule. In rice, a negative interaction of Cd or As with endogenous auxin has been demonstrated, as some NO protective effects. However, a synergism between the natural auxins (IAA and/or IBA) and NO was not yet determined and might be important for ameliorating rice metal(oid)-tolerance. With this aim, the stress caused by Cd/As toxicity in the root cells and the possible recovery by either NO or auxins (IAA/IBA) were evaluated after Cd or As (arsenate) exposure, combined or not with the NO-donor compound sodium-nitroprusside (SNP). Root fresh weight, membrane electrolyte leakage, and H2O2 production were also measured. Moreover, endogenous IAA/IBA contents, transcription-levels of OsYUCCA1 and OsASA2 IAA-biosynthetic-genes, and expression of the IAA-influx-carrier OsAUX1 and the IAA-responsive DR5::GUS construct were analyzed, and NO-epifluorescence levels were measured. Results showed that membrane injury by enhanced electrolyte leakage occurred under both pollutants and was reduced by the treatment with SNP only in Cd-presence. By contrast, no membrane injury was caused by either exogenous NO or IAA or IBA. Cd- and As-toxicity also resulted into a decreased root fresh weight, mitigated by the combination of each pollutant with either IAA or IBA. Cd and As decreased the endogenous NO-content, increased H2O2 formation, and altered auxin biosynthesis, levels and distribution in both adventitious (ARs) and mainly lateral roots (LRs). The SNP-formed NO counteracted the pollutants’ effects on auxin distribution/levels, reduced H2O2 formation in Cd-presence, and enhanced AUX1-expression, mainly in As-presence. Each exogenous auxin, but mainly IBA, combined with Cd or As at 10 µM, mitigated the pollutants’ effects by increasing LR-production and by increasing NO-content in the case of Cd. Altogether, results demonstrate that NO and auxin(s) work together in the rice root system to counteract the specific toxic-effects of each pollutant