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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
431

Utilizace trehalózy u orchidejí: evoluce genů trehalázy / Utilization of trehalose in orchids: evolution of trehalase genes

Šoch, Jan January 2017 (has links)
All orchid species studied so far have been shown to participate in orchideoid mycorrhizal symbiosis. Morover, this symbiosis is absolutely vital component of their life cycle. Exchange of nutrients occurs between symbionts where the fungi provides the orchid with energy and carbon supply at least in its early developmental stages. This study focuses on the possible role of trehalose in this transfer. In vitro experiments have showed in five species from three different subfamilies of Orchidaceae family that they can utilize trehalose comparably with sucrose and glucose. Thus, the ability of trehalose utilization seems to be conserved among orchids. Trehalase enzyme activity was localized histochemically in orchid mycorrhizas. The activity strongly colocalized with colonized tissue supporting a hypothesis that trehalose transfer occurs in this site and is mediated by trehalase. Using bioinformatic methods, trehalase gene duplications were identified in many taxons of Embryophyta including three orchid species. Interestingly, highest number of trehalase gene copies was identified in genome of orchid Dactylorhiza majalis. Trehalose utilization, high trehalase activity in mycorrhizas and trehalase gene duplications in some orchids together indicate that trehalose transfer in orchid myccorhizas...
432

Vliv invazních a nativních rostlin na abiotické a biotické vlastnosti půdy / The effect of invasive and native plants on abiotic and biotic soil properties

Hanzelková, Věra January 2019 (has links)
Invasive plants represent an important topic of study in current ecology because of their effects on whole ecosystems. The plants interact with the soil including soil biota, with the other plants in the community and with other organisms, eg. herbivores. Invasive plants often differ from non- invasive plants in nutrient utilization and can thus affect soil pH as well. They may also differ in the way they interact with mycorrhizal fungi that help the plants with nutrient uptake. In this study, the effect of invasive and native plants on soil properties is compared. Congeneric pairs of species, where one species is native and the other invasive, are compared. The native species are chosen so that they are dominant and therefore comparable to the invasive plants in the new environment. The evaluated soil properties are pH value and content of elemental nutrients from abiotic properties, and the amount of mycorrhizal fungi propagules and their spreading rate in soil from the biotic properties. In this study, the invasive and native plants differ only in the content of exchangeable phosphorus and potassium. Content of these two nutrients and one of the indicators of mycorrhizal fungi differ within the pairs of species as well. For most soil properties, the genus of the plant plays the main role, not...
433

Orchideje jako model studia ekofyziologických adaptací mykoheterotrofních rostlin / Orchids as a model for research in ecophysiological adaptations of mycoheterotropic plants

Ponert, Jan January 2018 (has links)
Perhaps all orchids are mycotrophic at early developmental stages, while majority of species photosynthesize at adulthood and only about 200 species remain fully mycotrophic for the whole life. Mycotrophy affects orchids at many levels. In this thesis, I focus on four aspects of orchid biology, which could be connected with mycotrophy: (i) systematics, (ii) genome size and endoreduplication, (iii) regulation of seed germination and (iv) mechanism of transfer of carbon and energy from fungi to orchids. There are over 27,000 recently recognized orchid species, nevertheless new ones are still discovering and old ones are revisiting. In this work I present a description of new species, Cleisostoma yersinii, and its morphological, anatomical, ecological and systematic characterization. Phylogeny reconstruction confirmed relationship with C. birmanicum. In the subtribe Podochileae, I reappraised the genus Campanulorchis to establish monophyletic but also morphologically defined group. For both abovementioned genera I prepared the artificial identification key. In the genus Dactylorhiza I revised taxa present in our country and I prepared an identification key which firstly mentions D. maculata subsp. elodes from Czech Republic. Orchid species diversity is probably reflected in genome structure. Results...
434

Inter-organizational Symbiotic Relationships : Key Factors for Success / Sa​marbetsformer för industriell symbios : Nyckelfaktorer för framgång

Hållstedt, Ulrika January 2016 (has links)
This report focuses on governance mechanisms for industrial symbiosis (IS). The study takes an organizational approach on material and energy exchanges between different organizations (or different parts in the same organization) leading to increased regional resource efficiency. This project explores different strategies for governance mechanisms and analyzes how these affect trust. Significant factors for initiating and keeping a collaboration successful are also analyzed. Representatives from 24 Swedish cases of symbiotic arrangements are interviewed and ten themes affecting IS collaborations are identified. The themes are governance structure, shared vision, previous collaboration, local conditions, initiating a collaboration, activities to build trust, conflicts, transaction-based or goal-oriented approach, indicators and distribution of costs and benefits. Among the governance structures used are hierarchy (collaboration between different parts of the same organization), joint venture, strategic alliance and different types of agreements. Common is a 10-15 years agreement, sometimes combined with a strategic discussion about the development of the collaboration. Three factors particularly affecting collaborations are identified: strategic meetings, indicators related to the collaboration and fair profit distribution. The factor strategic meetings is about combining long term agreements with innovation. Long term agreements might be necessary when a project requires investments. Meanwhile, this can suppress innovation by supporting outdated solutions. The paradox of needing both long term agreements and continued innovation may be solved by the practice of having strategic meetings and contract surveillance. Another significant factor for successful collaborations is the use of jointly evaluated indicators. To jointly evaluate a project according to predetermined indicators gives all parties the opportunity to know when a collaboration is successful. The third significant factor is fair profit distribution. Unfair profit distribution may delay or stop a project. It may also decrease trust in an ongoing project. A fair profit distribution is a key factor for enabling long term relationships. / Den här rapporten studerar samarbetsformer för industriell symbios (IS). Fokus för den här studien är material- och energiutbyten mellan organisationer eller mellan olika delar i samma organisation som leder till regional resurseffektivisering. Val och implementering av samarbetsform analyseras i relation till förtroende mellan organisationer och lyckade samarbeten. Viktiga faktorer för att lyckas starta och bibehålla ett symbiossamarbete analyseras också. Representanter från 24 svenska fall av symbiotiska samarbeten intervjuas och deras svar analyseras utifrån tio teman: samarbetsform, gemensam vision, tidigare samarbete, lokala förutsättningar, att starta ett samarbete, aktiviteter för att bygga förtroende, konflikter, transaktionsbaserat eller målinriktat förhållningssätt, indikatorer och vinstfördelning. Bland de samarbetsformer som används återfinns hierarki (samarbete mellan olika delar i samma organisation), joint venture, strategisk allians och olika typer av avtal. Vanligt är avtal på 10-15 år, ibland kombinerat med en strategisk diskussion om samarbetets utveckling. Tre faktorer identifieras som extra viktiga vid symbiotiska samarbeten: strategiska möten, indikatorer relaterade till samarbetet och rättvis vinstfördelning. Strategiska möten handlar om att kombinera långsiktiga avtal med innovation. Långsiktiga avtal behövs ofta i symbiossamarbeten för att kunna göra investeringar. Samtidigt kan detta låsa fast utdaterade lösningar och försvåra innovation och utveckling. Att ha avtalsbevakning och en strategisk diskussion kring utveckling av samarbetet har identifierats som ett sätt att lösa detta på. En annan betydande faktor för lyckade samarbeten är gemensamma indikatorer relaterade till samarbetet. Att gemensamt utvärdera samarbetet enligt uppsatta indikatorer ger alla parter möjlighet att veta när ett samarbete lyckats. Den tredje identifierade faktorn är rättvis vinstfördelning. Orättvis vinstfördelning kan stoppa eller försena ett samarbete. Det kan också urholka parternas förtroende till varandra. En rättvis vinstfördelning kan däremot skapa förtroende och är en nyckelfaktor till ett långsiktigt samarbete.
435

Analyse comparative des mécanismes de différenciation des bactéroïdes au cours des symbioses Bradyrhizobium Aeschynomene / Comparative analysis of bacteroid differentiation mechanisms in Aeschynomene-Bradyrhizobium symbioses

Lamouche, Florian 01 February 2019 (has links)
En cas de carence azotée, les légumineuses sont capables de mettre en place une symbiose avec des bactéries du sol fixatrices d’azote appelées rhizobia. Cette symbiose a lieu dans un organe appelé nodosité où les bactéries sont endocytées et appelées bactéroïdes. Certains clades de légumineuses imposent un processus de différenciation à leurs bactéroïdes qui agrandissent considérablement et deviennent polyploïdes, menant à des morphotypes bactériens allongés ou sphériques. Au cours de cette thèse, j’ai étudié la différenciation des bactéroïdes de Bradyrhizobium spp. en association avec Aeschynomene spp.. Les bactéroïdes de ces plantes présentent des degrés de différenciation distincts qui dépendent de l’espèce hôte. Mes données suggèrent que les bactéroïdes les plus différenciés sont aussi les plus efficaces. J’ai cherché à savoir quels facteurs procaryotes pourraient être impliqués dans les adaptations des bactéroïdes au processus de différenciation et à leurs divers hôtes, le tout en lien avec cette différence d’efficacité symbiotique au travers d’approches globales sans a priori de type -omiques. Les conditions considérées sont des bactéroïdes de différents morphotypes et des cultures libres de référence. Les fonctions activées en conditions symbiotiques ont été identifiées, ainsi que les gènes spécifiques d’un hôte donné. Des analyses fonctionnelles des gènes d’intérêt ont également été menées. Les mutants bactériens n’ont toutefois pas présenté de phénotype symbiotique drastique, montrant ainsi l’existence de réseaux de gènes complexes menant à la résilience des génomes de rhizobia. / In case of nitrogen starvation, legume plants establish a symbiotic interaction with nitrogen-fixing soil bacteria called rhizobia. This interaction takes place in nodules where the symbionts are internalized and become bacteroids. Some legume clades also impose a differentiation process onto the bacteroids which become enlarged and polyploid, leading to elongated or spherical morphotypes. During my PhD work, I have studied bacteroid differentiation of Bradyrhizobium species in association with Aeschynomene spp.. These bacteroids display distinct differentiation levels depending on the plant host, and my analyses suggest that the most differentiated ones are also the most efficient. I investigated the bacterial factors potentially involved in the adaptations to differentiation and host-specificity, and related to the higher efficiency of the most differentiated bacteroids using global-omics approaches without a priori. The analyzed conditions were bacteroids of distinct morphotypes and free-living reference cultures. Activated functions under symbiotic conditions were identified, as well as host-specific ones. Functional analyses were performed on genes of interest. However, the bacterial mutants did not display drastic symbiotic phenotypes, showing the existence of complex gene networks leading to high resilience of rhizobial genomes.
436

Plant nuclear envelope-associated proteins function in development and symbiosis.

Anna, Newman-Griffis Hare January 2018 (has links)
No description available.
437

The Unknown and the Unnamed

Lyon, Calista 30 September 2019 (has links)
No description available.
438

Valorizing waste through collaborations : A road map to expand the possibilities of a circular company / Valorisering av avfall genom samarbeten : En roadmap för att expandera möjligheterna för ett cirkulärt företag

Jacobsson, Antonia, Larsson, Alice January 2023 (has links)
When increasing the amount of recycled material in production the input materials are rarely homogenous which results in unavoidable waste streams. Utilizing this waste is of high importance when moving towards a Circular Economy and for firms to keep their circular identity. However, to achieve this, collaborations between firms are crucial. The purpose of this single case study is to develop a road map for how firms can create collaboration to strategically valorize waste streams from circular processes. Through a qualitative study based on 23 semi structured interviews the subject was investigated. The interviews were held in three phases with respondents from four different groups: the case company, potential collaborators, other firms with waste streams as well as subject experts. The interviews were transcribed and analyzed through a thematic analysis resulting in five themes. Moreover, this study resulted in a road map with three gears and multiple steps that companies should follow to create collaboration for valorizing waste streams. The three gears are: Gear 1: Internal preparation, Gear 2: Finding the right partner and Gear 3: Forming the collaboration. The study fills the gap in existing literature regarding the lack of a firm perspective of a concrete road map by which companies can go from producing a waste stream to creating a collaboration to valorize it. Both the managers of a company as well as an assigned person responsible for waste streams can benefit from the road map. Although the road map contains three consecutive gears, the containing steps can be considered individually or partly depending on the company’s circumstances. In addition, companies without circular processes can be inspired from the road map in their work of becoming more sustainable. / När mängden återvunnet material ökar i produktioner är ingångsmaterialen sällan homogena vilket resulterar i oönskade restströmmar. För att röra sig mot en cirkulär ekonomi och för att företag ska behålla sin cirkulära identitet är det av stor vikt att ta tillvara på avfallet. För att uppnå detta är samarbeten mellan företag mycket viktiga. Syftet med denna enfallsstudie är att utveckla en roadmap över hur företag kan skapa samarbeten för att strategiskt valorisera restströmmar från cirkulära processer. Genom en kvalitativ studie baserad på 23 semistrukturerade intervjuer undersöktes området. Intervjuerna genomfördes i tre faser med respondenter från fyra olika grupper: fallstudieföretaget, potentiell samarbetspartner, andra företag med restströmmar samt ämnesexperter. Intervjuerna transkriberades och analyserades genom en tematisk analys som resulterade i fem teman. Studien resulterade därmed i en roadmap bestående av tre växlar och flera steg vilka företag kan följa för att skapa samarbeten för att valorisera sina restströmmar. De tre växlarna är: Växel 1: Interna förberedelser, Växel 2: Hitta den rätta samarbetspartnern och Växel 3: Utforma samarbetet. Studien fyller gapet i den existerande litteraturen då företagsperspektivet i en konkret roadmap som beskriver hur företag kan gå från att producera en restström till att skapa samarbeten för att valorisera den saknas. Ledarna i ett företag samt en designerad person ansvarig för restströmmarna kan få nytta av av roadmapen. Trots att roadmapen består av tre påföljande varandra växlar kan de olika växlarna i roadmapen nyttjas individuellt eller delvis beroende på företagets omständigheter. Därtill kan även företag utan cirkulära processer inspireras av roadmapen i deras arbete att bli mer hållbara.
439

Cirkulär hydroponi : Från urbant avfall till odlingssubstrat / Circular hydroponics : From urban waste to growing media

Karlsson, Izabella, Spencer, Maya January 2022 (has links)
Dagens samhälle är fullt av utmaningar vad gäller hållbarhet. En av de viktigaste frågeställningarna är hur mänskligheten kan tänka om jordbruket för att anpassa sig till den förväntade ökningen i efterfrågan på mat, och samtidigt göra jordbruket mer miljövänligt. Ett tänkbart steg mot mer hållbarhet inom jordbruket är hydroponi. Ändå står hydroponiska system inför sina egna hållbarhetsproblem; ett av problemen är de konventionella substraten som används. De nuvarande konventionella substraten härrör ofta från torv, stenull, perlit och kokosfibrer. Det finns dock möjligheter att implementera industriella symbiotiska nätverk i vilka en sektors avfall är en annans resurs, detta skulle kunna bidra till en minskning av miljöpåverkan jämfört med de konventionella substraten.  Syftet med projektet är att undersöka drivkrafter och hinder som finns för att förbättra hydroponiska stadsodlingars miljöprestanda gällande odlingssubstrat, genom att använda recirkulerade avfallsströmmar från närliggande kommersiella och kommunala verksamheter i stället för konventionella odlingssubstrat. I detta projekt intervjuades tre företag som odlar hydroponiskt i Stockholm för att ytterligare förstå kritiska egenskaper hos substraten, och vilka faktorer som realistiskt måste beaktas när man undersöker brukandet av urbana avfallsströmmar i motsats till konventionella substrat. Detta följs av en litteraturgenomgång som fokuserar på egenskaperna hos både konventionella substrat och de avfallsbaserade substraten. Genom forskningen blev det uppenbart att recirkulering av avfallsströmmar är ett genomförbart alternativ inom hydroponi, och har potential att minska miljöpåverkan från substraten i branschen. Det krävs dock utan tvekan ytterligare forskning på området. Potential för mellanhänder mellan den avfallsproducerande aktören och de hydroponiska odlingarna är ett nästa avgörande steg i utvecklingen av hållbara odlingssubstrat, men för lite forskning finns i dagsläget vilket begränsar möjligheterna inom området. / Today’s society is riddled with challenges regarding sustainability. One of the main concerns is how humanity can rethink farming in order to adapt to the projected demand for food in the near future, whilst also making farming more environmentally friendly. A possible step towards the sustainability of farming is hydroponics. Even so, current hydroponic systems are facing their own sustainability issues; one of which is the growing media used. The current, conventional growing media is often derived from peat, rock wool, perlite, and coconut coir. There are, however, opportunities to implement industrial symbiotic networks in which one processes waste can be used as another’s resource, this would contribute to a reduction in environmental impact compared to the conventional growing mediums.  The aim of this project is to examine the possibilities and barriers that exist regarding the improvement of environmental performance of growing media in hydroponics through the recirculation of urban waste streams from nearby commercial and municipal operations instead of using conventional growing media. In this project three hydroponic farming companies in Stockholm were interviewed to further understand the competition factor of growing mediums, and what factors realistically need to be accounted for when looking into the usage of urban waste streams as opposed to conventional growing media. This is followed by a literature review focusing on the characteristics of both conventional growing media and waste stream derived growing media. It became apparent through the research that recirculating waste streams is a feasible option within hydroponics, and has potential to reduce the environmental impact of growing media in the industry. However, further research is undoubtedly required in the field. Areas such as potential for middlemen between the waste producing actor and hydroponic farms are the next feasible step in the development of sustainable growing media, yet little to no research has currently been done on the matter.
440

Orchideje jako model studia ekofyziologických adaptací mykoheterotrofních rostlin / Orchids as a model for research in ecophysiological adaptations of mycoheterotropic plants

Ponert, Jan January 2018 (has links)
Perhaps all orchids are mycotrophic at early developmental stages, while majority of species photosynthesize at adulthood and only about 200 species remain fully mycotrophic for the whole life. Mycotrophy affects orchids at many levels. In this thesis, I focus on four aspects of orchid biology, which could be connected with mycotrophy: (i) systematics, (ii) genome size and endoreduplication, (iii) regulation of seed germination and (iv) mechanism of transfer of carbon and energy from fungi to orchids. There are over 27,000 recently recognized orchid species, nevertheless new ones are still discovering and old ones are revisiting. In this work I present a description of new species, Cleisostoma yersinii, and its morphological, anatomical, ecological and systematic characterization. Phylogeny reconstruction confirmed relationship with C. birmanicum. In the subtribe Podochileae, I reappraised the genus Campanulorchis to establish monophyletic but also morphologically defined group. For both abovementioned genera I prepared the artificial identification key. In the genus Dactylorhiza I revised taxa present in our country and I prepared an identification key which firstly mentions D. maculata subsp. elodes from Czech Republic. Orchid species diversity is probably reflected in genome structure. Results...

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