16 research outputs found
Transition from absolute to quantitative short-day control in Nicotiana tabacum cv. Maryland Mammoth
No full textThe response in vitro of thin cell layers, excised from different stem regions of Nicotiana tabacum cv. Maryland Mammoth plants at various developmental stages, was studied under different photoperiodic treatments. The aim was to determine at which stage of plant development, and in which region of the stem, the absolute short‐day requirement, indispensable for the induction of the flowering process in this genotype, becomes quantitative and whether it remains short‐day. The explants were cultured on a medium suitable for flower neoformation, and were exposed for 30 days to the following treatments: continuous darkness, 8 h light/16 h dark per day, 16 h light/8 h dark per day, and continuous light. The first flowers on explants were observed from plants that were still in the vegetative state, but whose apex showed an accelerated production of axillary vegetative buds, as observed histologically. These explants were excised from the first 10 internodes below the first node with a leaf ≥ 5 cm in length (apical site), and produced flowers only under short‐day treatment. When the apical dome initiated the organization of the terminal flower, the apical site explants developed flowers under both short‐day and long‐day treatments. At the same stage, explants from the 15th to the 20th internode below the first leaf ≥ 5 cm in length also formed flowers, but only under short‐day. When the plant showed a complete inflorescence, flowers were also present on explants from the most basal stem internodes and from the inflorescence branches. At this stage, flower neoformation occurred under all treatments; however, under short‐day the number of explants showing flowers not associated with vegetative buds on the same sample greatly exceeded that observed under other treatments, as did the mean number of flowers per explant (except the basal regions). In conclusion, in the post‐inductive phases of the flowering process, the photoperiodic requirement of this genotype is always short‐day. The superficial tissues of the stem require either absolute or quantitative short‐day treatment, depending on their position on the stem and the stage of evolution of the flowering process in the terminal apex
Auxin, photoperiod and putrescine affect flower neoformation in normal and rolB-transformed tobacco thin cell layers
No full textAuxin, photoperiod and putrescine are factors involved in the control of the reproductive phase of the flowering process in planta. The aim of this study was to investigate whether auxin is able, in the absence of other exogenous hormones, to stimulate flower neoformation in Nicotiana tabacum L, thin cell layers excised from flowering plants, whether an interaction exists between the hormone and the length of the light treatment per day, and whether exogenous putrescine interferes with auxin and light in the realization of the flowering programme. Since tissues transformed with rolB gene show an increased binding capacity of auxin, the response of rolB-explants was compared with that of the wild type. Thin cell layers from floral branches were cultured in the presence of a wide range (0-10 mu M) of indoleacetic acid alone, under various phototreatments (continuous darkness, 8 h light/day, and 16 h light/day). Floral, vegetative and rooting responses were favoured in the transgenic explants. Flower neoformation was stimulated by long days and by exogenous auxin (1 mu M). In rolB-thin cell layers flowering also occurred in the most unfavourable culture conditions (i.e. continuous darkness combined with either hormone-free medium or 10 mu M auxin). Long days and 1 mu M auxin also favoured caulogenesis, though to a lesser extent than flower neoformation. Rhizogenesis occurred in rolB-explants only and was induced by exogenous auxin and favoured by continuous darkness, In both wild type and rolB-explants, exogenous putrescine (1 mM) reduced flower neoformation in the presence of 1 mu M auxin and long days. (C) Elsevier, Paris
INTERRELATIONSHIPS BETWEEN BROWNING AND PHYTOALEXIN ACCUMULATION ELICITED BY ARACHIDONIC-ACID
No full textHypersensitive browning and phytoalexin accumulation were induced in potato tuber (Solanum tuberosum L.) by the elicitor arachidonic acid. Phenylthiourea, an inhibitor of polyphenoloxidases, completely inhibited browning of the tissue induced by the elicitor in old (8 months) but not in young (1-2 months) tubers. Phytoalexin accumulation was not affected by the action of phenylthiourea both in young and old tubers, showing that this aspect of hypersensitive response is not necessarily related to the browning of the tissue. Hydroxyl radical (HO.) induced browning of the tissue but no phytoalexin accumulation. Gas chromatographic-mass spectrometric analyses showed that the rate of metabolization of arachidonic acid was independent of the addition of phenylthiourea and of the age of tubers
Flower formation in vitro in a quantitative short-day tobacco: interrelation between photoperiod and infructescence development.
No full textThe flowering response of thin layers excised from branch internodes of Nicotiana tabacum cv. Maryland Catterton (quantitative short-day plant for induction) was studied under three photoperiodic treatments. The explants were excised from inflorescences bearing flowers only, flowers and green fruits, or from infructescences with green fruits only. The aim of the study was to investigate the post-inductive photoperiodic effects on in vitro flower bud formation in a quantitative short-day tobacco and the relation with infructescence development. Short days quantitatively enhanced the flower bud regeneration capacities of explants in all stages of development, both as number of explants induced to produce flowers and as mean number of flowers per explant. There was no significant difference in flower bud formation on explants of the first two stages, which produced much more flowers than those of the third stage. Observations in planta showed that, during the 20 days separating the second stage from the first stage, there was no significant difference in the number of floral buds and flowers present on the inflorescence; however, the branch internodes lengthened, as did the floral buds and flowers. During the 10 days leading to the third stage, the number of capsules did not change significantly, but a high rate of floral abscission occurred. The present results show that in Nicotiana tabacum cv. Maryland Catterton short day quantitatively controls not only the inductive step of the flowering process, but also affects the capacity to regenerate flower buds during the late post-inductive phases. The responsiveness to the photoperiodic signal decreases only when the plant exhibits only fruits
Ruolo dell'auxina e del fotoperiodo nella neoformazione fiorale da tessuti somatici superficiali di piante di tabacco a determinazione criptica e in piena fioritura
No full textDottorato di ricerca in scienze botaniche. 8. ciclo. A.a. 1992-95Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
San Felipe los Alzati: Michoacán
No full textLa información de esta miniguía se basa en los trabajos de los arqueólogos Otto Schondube Baumbach, Jesús Teja Andrade, Wanda Tomassi de Magrelli y Estela Peña DelgadoEl asentamiento formaba parte de la frontera oriente del señorío tarasco. Se desconoce el nombre prehispánico del lugar; en la época colonial se llamó San Felipe Calvario, y en 1895, éste último se le cambió por el apellido Los Alzati, en honor de los hermanos José María, Marcos y Darío, héroes locales de la época de la intervención francesa. Las exploraciones arqueológicas llevadas a cabo en el sitio han sido escasas, por lo que sólo se ha descubierto una pequeña parte que corresponde a la zona ceremonial, ésta es, el área visitable.</p
The Ecovillage of Pescomaggiore (L'Aquila) Birth and death of a self-determined post-disaster community (2009-2014)
No full textPurpose - The purpose of this paper is to aim at exploring the relationship between community building and the changes occurred in the context of a post-disaster self-built ecovillage (EcoVillaggio Autocostruito (EVA)), spontaneously born after the L'Aquila earthquake in 2009. The community eventually dissolved in 2014, following a series of changes in the organization, that resulted in an increasingly centralized decision-making process, and in individual and community relationships, that were fueled by conflicts and contrasts. Design/methodology/approach - Through a self-ethnography method, the paper provides the insider perspective of the lead author who was a part of EVA since the beginning. Self-ethnography allowed developing a narrative of EVA across its life course. Findings - Findings reveal that the community into EVA was initially pursuing community-building goals through self-construction, sustainability, mutuality and reciprocity relationships out of market. However, several events occurred and changed community goals, organization and decision making. Eventually, individual goals and vertical decision making emerged among the community members, leading to the death of EVA. Research limitations/implications - The paper just considered those main events that marked the collective and individual life of the lead author since the beginning until the end of the ecovillage. Others events, equally important, were not considered due to word length. In addition, self-ethnography is still considered by some authors as a subjective method. Originality/value - The paper is one of the few exploring community experiences into post-disaster ecovillages. Moreover, there are no papers investigating post-disaster ecovillages through a self-ethnography approach. Therefore, the paper offers an innovative and original perspective on the under-investigated topic of post-disaster ecovillages and employs a promising research method in disaster studies
Managing living marine resources in a dynamic environment: The role of seasonal to decadal climate forecasts
No full textRecent developments in global dynamical climate prediction systems have allowed for skillful predictions of climate variables relevant to living marine resources (LMRs) at a scale useful to understanding and managing LMRs. Such predictions present opportunities for improved LMR management and industry operations, as well as new research avenues in fisheries science. LMRs respond to climate variability via changes in physiology and behavior. For species and systems where climate-fisheries links are well established, forecasted LMR responses can lead to anticipatory and more effective decisions, benefiting both managers and stakeholders. Here, we provide an overview of climate prediction systems and advances in seasonal to decadal prediction of marine-resource relevant environmental variables. We then describe a range of climate-sensitive LMR decisions that can be taken at lead-times of months to decades, before highlighting a range of pioneering case studies using climate predictions to inform LMR decisions. The success of these case studies suggests that many additional applications are possible. Progress, however, is limited by observational and modeling challenges. Priority developments include strengthening of the mechanistic linkages between climate and marine resource responses, development of LMR models able to explicitly represent such responses, integration of climate driven LMR dynamics in the multi-driver context within which marine resources exist, and improved prediction of ecosystemrelevant variables at the fine regional scales at which most marine resource decisions are made. While there are fundamental limits to predictability, continued advances in these areas have considerable potential to make LMR managers and industry decision more resilient to climate variability and help sustain valuable resources. Concerted dialog between scientists, LMR managers and industry is essential to realizing this potential.Peer reviewe
Constructions of the gaucho as vagrant and idle and as a born criminal: Portraits of Juan Moreira (Argentina, 19th and 20th centuries)
No full textThis article examines aspects of the discourse of power by which the figure of the Argentine gaucho was labeled as a “vagrant and idle” subject, based on the study of the archetypical Juan Moreira. In particular, the article explores analyses carried out decades after his death, influenced by the theories of Cesare Lombroso and Nicola Pende. Born in 1829 and killed at the hands of the police in 1874, Moreira became an emblematic personality of local folklore. Although his life has been the subject of extensive literary analysis, largely focused on the publication of Eduardo Gutiérrez’s novelistic portrayal, there has not been as much focus on the attempt to validate scientifically his stigmatization using the theories of these Italian thinkers. This text, therefore, explores readings of Juan Moreira carried out during the 20th century by two doctors, José Ingenieros and Nerio Rojas. In methodological terms, triangulation techniques were used, taking as vertices the legislation in place at that time, the interpretations of his life made through his transformation into a literary and film character, and finally, the aforementioned psychodiagnostic evaluations based on the integration of hypothetical environmental and innate characteristics
Chromatin and oxygen sensing in the context of JmjC histone demethylases
No full textResponding appropriately to changes in oxygen availability is essential for multicellular organism survival. Molecularly, cells have evolved intricate gene expression programmes to handle this stressful condition. Although it is appreciated that gene expression is co-ordinated by changes in transcription and translation in hypoxia, much less is known about how chromatin changes allow for transcription to take place. The missing link between co-ordinating chromatin structure and the hypoxiainduced transcriptional programme could be in the form of a class of dioxygenases called JmjC (Jumonji C) enzymes, the majority of which are histone demethylases. In the present review, we will focus on the function of JmjC histone demethylases, and howthese could act as oxygen sensors for chromatin in hypoxia. The current knowledge concerning the role of JmjC histone demethylases in the process of organism development and human disease will also be reviewed. © 2014 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY).</p
