Browsing by Subject "Transport"

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Regulation of ammonium transport in Arabidopsis thaliana
(2022) Ganz, Pascal; Ludewig, Uwe
The overarching question of this thesis deals with how plants ensure the selective uptake of ammonium while maintaining ion and pH homeostasis. A key component of this is ammonium transporters (AMTs) with high affinity towards their substrate, which are at the same time part of a multilayered protection system against uncontrolled ammonium influx. Conserved protein sequences inside the transporter were analyzed as well as the regulatory system based on post-translational modification of the transporter.
Simulating the spread and establishment of alien species along aquatic and terrestrial transport networks: A multi‐pathway and high‐resolution approach
(2022) Bagnara, Maurizio; Nowak, Larissa; Boehmer, Hans Juergen; Schöll, Franz; Schurr, Frank M.; Seebens, Hanno
The introduction and further spread of many alien species have been a result of trade and transport. Consequently, alien species are often found close to traffic infrastructure and urban areas. To contain and manage the spread of alien species, it is essential to identify and predict major routes of spread, which cannot be obtained by applying common modelling approaches such as species distribution models. Here, we present a new model called CASPIAN to simulate the dispersal of alien species along traffic infrastructure and the establishment of populations along these routes. The model simulates simultaneous spread of species of up to eight different modes of transport along roads, railways and waterways. We calibrated and validated the model using two species that spread within Germany as case studies: the terrestrial plant Senecio inaequidens and the freshwater clam Corbicula fluminea, and performed a shortest path analysis to quantify the relative importance of individual routes for spread. The application of the model yielded detailed predictions of dispersal and establishment for >600,000 segments of the traffic network throughout Germany. Once calibrated, the model captured the general spread dynamics of the two species with higher accuracy for the freshwater environment due to the higher quality of data available for the aquatic species. The quantification of spread routes using the shortest path analysis revealed a clear backbone of major routes of spread, which varied depending on the type of traffic network and the starting points considered. Major routes of spread aligned with high traffic intensities, but high traffic per se did not necessarily result in high spread intensities. Synthesis and application. By simulating the spreading dynamics of alien species along transport networks across multiple pathways, CASPIAN enables the identification of major spread routes along different dispersal pathways and quantification of their relative importance, which helps prioritising pathways of introduction as required by international biodiversity goals such as the CBD Aichi targets.
The AtIREGs - characterization of a new family of metal transporters in Arabidopsis thaliana
(2009) Kirchner, Silvia; von Wirén, Nicolaus
Essential transition metals are required in all plant cells for the activities of numerous metal-dependent enzymes and proteins, but can become toxic when present in excess. For the detoxification of heavy metals and to adjust to changes in micronutrient concentrations in the environment, plants possess a tightly controlled metal homeostasis network. In this regard, transition metal transporters are of central importance. Many metal transporters have already been identified, but a large number of candidates for heavy metal transport proteins still have to be analyzed at the biochemical level and within the plant metal homeostasis network. Based on the description of the animal IREG1 metal transporter as an iron exporter in vertebrates, a phylogenetic analysis of eukaryote and prokaryote sequences with similarity to IREG1 showed three homologous genes in Arabidopsis, which were named AtIREG1, AtIREG2 and AtIREG3. As these AtIREG family members were candidates for yet uncharacterized metal transporters, the main objective of this thesis was to investigate the physiological function of this newly identified transporter family in plants.
The wheat AMT2 (AMmonium Transporter) family, possible functions in ammonium uptake and pathogenic/symbiotic interactions
(2023) Porras‐Murillo, Romano; Zhao, Yufen; Hu, Jinling; Ijato, Toyosi; Retamal, Joseline Palafox; Ludewig, Uwe; Neuhäuser, Benjamin
Ammonium uptake into wheat roots relies primarily on two AMmonium Transporters of subfamily one, while the wheat genome comprises 4 to 6 AMT2 type transporters. Plant AMT2s generally show functions in root‐to‐shoot translocation or pathogenic and symbiotic plant–microorganism interactions. We addressed the activity of TaAMT2s in ammonium transport. Nitrogen‐dependent expression implicated a physiological function in ammonium uptake for TaAMT2;1 and in ammonium distribution for TaAMT2;2‐6.