Die tiefgefrorene Lederhose. Sensationelle Geschichten aus dem Gletscher-Eis (von Elisabeth Brückner)

Das Schnidejoch ist ein Gebirgspass 2700 Meter hoch in den Berner Alpen, seit tausenden Jahren von Eis bedeckt. Mittlerweile ist fast alles Eis infolge der globalen Klimaerwärmung geschmolzen. SWR2 Kontext-Radiosendung von Elisabeth Brückner.

Gletscherarchäologie. Steinzeitfunde aus dem Eis (von Elisabeth Brückner)

Der Ötzi ist kein Einzelfall. Immer mehr Hinterlassenschaften der Vorzeit kommen ans Tageslicht, seit die globale Erwärmung nach und nach die alpinen Gletscher zum Schmelzen bringt. Insbesondere am Schnidejoch im Berner Oberland sind Archäologen fündig geworden: Das Eis, das hier jahrtausendelang den Bergsattel bedeckte, ist mittlerweile bis auf einen kleinen Eisfleck geschmolzen und hat rund 900 Artefakte freigegeben. Darunter eine 6.800 Jahre alte Schüssel aus Ulmenholz, eine komplette Jägerausrüstung, römische Schuhnägel aus dem Mittelalter. Und das große Schmelzen geht weiter ...

Amino Acid Export in Developing Arabidopsis Seeds Depends on UmamiT Facilitators

Essential amino acids cannot be synthesized by humans and animals. They often are limiting in plant-derived foods and determine the nutritional value of a given diet [1]. Seeds and fruits often represent the harvestable portion of plants. In order to improve the amino acid composition of these tissues, it is indispensable to understand how these substrates are transported within the plant. Amino acids result from nitrogen assimilation, which often occurs in leaves, the source tissue. They are transported via the vasculature, the xylem, and the phloem into the seeds, the so-called sink tissue, where they are stored or consumed. In seeds, several tissues are symplasmically isolated [2, 3], i.e., not connected by plasmodesmata, channels in the cell walls that enable a cytoplasmic continuum in plants [4]. Consequently, amino acids must be exported from cells into the apoplast and re-imported many times to support seed development. Several amino acid importers are known, but exporters remained elusive [5, 6]. Here, we characterize four members of the plant-specific UmamiT transporter family from Arabidopsis, related to the amino acid facilitator SIAR1 and the vacuolar auxin transporter WAT1 [7, 8]. We show that the proteins transport amino acids along their (electro)chemical potential across the plasma membrane. In seeds, they are found in tissues from which amino acids are exported. Loss-of-function mutants accumulate high levels of free amino acids in fruits and produce smaller seeds. Our results strongly suggest a crucial role for the UmamiTs in amino acid export and possibly a means to improve yield quality.