Unravelling the importance of mycorrhiza for plant nitrogen nutrition and transfer into the networks

Most terrestrial plants establish symbiotic associations with fungi called mycorrhiza, like ectomycorrhizas (EM) and arbuscular mycorrhizas (AM), for accessing limiting plant nutrients. For improving N nutrition, some plant species may establish EM-AM dual-mycorrhizal associations, either within the same root system or at different plant’s ontogenetic stages. Furthermore, EM and AM associations may interconnect plants via a common mycorrhiza network (CMN) for N exchange. However, available studies fail to provide univocal evidence on the advantage to a host plant of exploiting a dual association, compared to a single one for N acquisition, as well as to demonstrate the potential effects of the CMN networks mediating resource partitioning between connected plants, since transfer can occur via several routes simultaneously. In addition, quantification of the amount of possible nutrients transferred has also shown to be challenging, leading to doubts regarding the importance of the CMN in inter-plant partitioning. With this in mind, I have developed two novel experiments to prove and distinguish the contribution of the CMN for N transfer between connected plants as well as to evaluate nutritional advantages of dual vs single mycorrhizal plants. The first experiment aimed to respond two main objectives: (A) to evaluate N nutrition benefits in plants associated with single EM or AM versus dual associations and (B) to evaluate the potential of a dually associated plant as N donor via a CMN with receiver plants bearing single EM or AM associations. For this purpose, I have designed a novel multi-chamber mesocosm where a central split-rooted donor, able to associate with both AM and EM simultaneously, shares an AM or EM network with one neighbour plant simultaneously. Since only dually mycorrhized donor plants had access to both fungi type, it is possible to access different N nutrition of single colonized neighbours compared to central dual mycorrhizal plant. In addition, by applying 15N labeled solution to central dual mycorrhizal plant, I could track the preferential N allocation via AM vs EM network. At my knowledge, such evaluation was never made before. I hypothesized that (1) host plants establishing dual mycorrhiza associations will exhibit an enhanced N nutrition, compared to those depending on single associations. I further hypothesized (2) that dual mycorrhizal plants will preferentially share more N to plants bearing an EM association, due to its larger mycelium proliferation. Lastly, I hypothesized that (3) such mycelium proliferation might act as a sink for C, requiring higher C allocation from host plant. The data obtained demonstrate a nutritional advantage regarding N uptake for host plants holding dual mycorrhizal association, compared to single colonized plants. However, no transfer of N occurred between donor and receiver plants. Therefore, I concluded that CMN functioning for N transfer might occur only under specific situations, such as for particular plant–fungus combination, the characteristics of connected plants or abiotic conditions. For the second experiment, I aimed to quantify the direct transfer of N via the mycelial network in comparison to indirect pathways. I hypothesized that: (1) N transfer between connected plants occurs genuinely through hyphal connection rather than indirect pathways; (2) the proportion of N allocated from donor to receiver plants through mycorrhiza hyphae connections is significant and may improve neighboring plant nutrition and (3) by shading donor plant, N transferred to receiver plants is increased, once it might be able to produce more C to be exchanged by transported N. The data demonstrated a higher 15N transfer to ram1-1 receiver plants. The highest 15N found in the ram1-1 plant summed with the highest root biomass observed in this plant which increasing its area of nutrients absorption, highlighting the importance of indirect pathways for resources allocations in our system. Also in opposite to what was previously hypothesized, shading treatment did not increased 15N transfer. With this, it is possible to conclude that CMN are important, but most likely by other means than discussed in the literature

Sexual and reproductive health: the science behind supplementation in aging

Abstract in proceedings of the Fourth International Congress of CiiEM: Health, Well-Being and Ageing in the 21st Century, held at Egas Moniz’ University Campus in Monte de Caparica, Almada, from 3–5 June 2019.This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.info:eu-repo/semantics/publishedVersio

Sexual and reproductive health : the science behind supplementation in aging

Abstract of the communication presented at the 4th International Congress of CiiEM - "Health, Well-being and Ageing in the XXI Century." 2-5 June 2019, Campus Egas Moniz, Monte de Caparica, Portugal.N/

Cognitive accounts of second language acquisition: critical period and age effects

According to previous framework, the main hypothesis is that language could be acquired with accuracy just in a critical period, until puberty. The critical period effects are present both in first and second language acquisition situations. However the mastery and native-like competence believed as a classic achievement by the youngest learners (infants), could be compromised for several other maturational constraints which are not favourable. In the scope of PhD research, is been developed a battery, in electronic format, to observe differences, at phonological processing and other cognitive levels in the second-language field, between children, adolescents and adults. According to theories and findings in the neuroplasticity area, it was objective to analyse the metalinguistic competence and cognitive processes involved in it, considering age, gender and also nationality and mother tongues of the individual. Here will be presented and discussed implications of some results regarding performance in the dichotic hearing test

Enfisema bolhoso associado a consumo de drogas

AbstractBullous emphysema is characterized by permanent enlargement of airspaces distal to the terminal bronchiole accompanied by destruction of alveolar walls. Several aetiologies have been described, namely deficiency of α1-antitrypsin and the consumption of tobacco. With the exception of the deficiency of α1-antitrypsin, some cases of bullous emphysema in the young adult continue without known aetiology. Some cases of bullous emphysema have been described, emphasising the relationship between the disease and drug consumption. The association possibly creates the conditions for the development of large lung bullae, with particular exuberance for the superior lobes. The authors describe two clinical cases of young patients, with history of consumption of smoked substance abuse and bullous emphysema.Rev Port Pneumol 2010; XVI (1): 157-16