Seed conservation in ex situ genebanks - genetic studies on longevity in barley

Recognizing the danger due to a permanent risk of loss of the genetic variability of cultivated plants and their wild relatives in response to changing environmental conditions and cultural practices, plant ex situ genebank collections were created since the beginning of the last century. World-wide more than 6 million accessions have been accumulated of which more than 90% are stored as seeds. Research on seed longevity was performed in barley maintained for up to 34 years in the seed store of the German ex situ genebank of the Leibniz-Institute of Plant Genetics and Crop Plant Research in Gatersleben. A high intraspecific variation was detected in those natural aged accessions. In addition three doubled haploid barley mapping populations being artificial aged were investigated to study the inheritance of seed longevity. Quantitative trait locus (QTL) mapping was based on a transcript map. Major QTLs were identified on chromosomes 2H, 5H (two) and 7H explaining a phenotypic variation of up to 54%. A sequence homology search was performed to derive the putative function of the genes linked to the QTLs

Controls on the 129I/I ratio of deep-seated marine interstitial fluids: 'Old' organic versus fissiogenic 129-iodine

Iodine and its radioisotope 129I have been successfully used to trace the origin of pore waters in submarine fluid escape structures because of their close association with organic material in deeply buried sediments. We report here halogen concentrations and 129I/I ratios for fluids of five mud volcanoes sampled along an E–W transect across the Gulf of Cadiz in the NE Atlantic Ocean. Concentrations of iodide and bromide increase consistently seaward accompanied by a decrease in 129I/I ratios from 6490 × 10− 15 to 663 × 10− 15. The exceptionally high 129I/I ratios at the near-shore locations reflect the presence of fissiogenic 129I, produced in situ by spontaneous fission of 238U within terrigenous sediments and released into pore water during clay mineral diagenetic processes. The observed 129I/I and halogen trends, together with similar changes in 87Sr/86Sr ratios, indicate a progressive seaward transition from inorganic-terrigenous to organic-marine fluid sources. Comparison of our results with literature data for varying geological settings reveals a general relationship between fissiogenic 129I, radiogenic 87Sr and the lithology or provenance of rocks and sediments, respectively. While 129I/I ratios in continental rock-hosted aquifers and terrigenous sedimentary systems are dominated by in situ production of fissiogenic 129I, iodine isotopes in oceanic settings or volcanogenic marine sediments reflect the release of ‘old’ iodine from deeply buried organic matter. The Gulf of Cadiz represents the full transition between these continental and oceanic 129I/I and 87Sr/86Sr end members. This is the first systematic investigation of fissiogenic 129I production in marine sedimentary environments

Die subjektive Belastung pflegender Ehepartner von Demenzkranken: Hinweise zur Validität der deutschen Version des Zarit Burden Interviews

Zusammenfassung: Trotz der Vielzahl europäischer Studien über pflegende Angehörige von Demenzkranken gibt es bis heute keine veröffentlichte validierte deutsche Version des am häufigsten angewandten Instruments zur Erfassung der Belastung familiärer Pflegepersonen (Zarit Burden Interview, ZBI). Primäres Ziel dieser Studie war die Analyse der teststatistischen Gütekriterien der deutschen Version des ZBI (G-ZBI). Die Stichprobe bestand aus 37älteren Paaren (n=74), bei denen der Ehemann von einer Demenzerkrankung betroffen war und die Ehefrau den Großteil der Pflege des kranken Partners übernommen hatte. Das G-ZBI weist eine hohe psychometrische Qualität (Cronbachsα=0,91) sowie überzeugende korrelative Zusammenhänge als Validitätshinweise auf (z.B. Wohlbefinden der Pflegeperson, Pflegebedürftigkeit und neuropsychiatrische Symptome des Demenzkranken). Eine Faktorenanalyse als Maß der Konstruktvalidität zeigt uneindeutige Befunde, unterstützt aber die in der Literatur häufig angenommene Eindimensionalität des Instruments. Die psychometrischen Gütekriterien legen nahe, dass das G-ZBI die Qualität eines reliablen und validen Instruments zur Erfassung der subjektiven Belastung pflegender Ehepartner von Demenzkranken besitzt. Die Anwendung des G-ZBI hat praktische und klinische Relevanz bei der Identifikation besonders belasteter und gefährdeter familiärer Pflegepersone