Atomic force microscopy (AFM) was used in concert with transmission electron microscopy (TEM) to image magnetotactic bacteria (Magnetospirillum gryphiswaldense MSR-1 and Magnetospirillum magneticum AMB-1), magnetosomes, and purified Mms6 proteins. Mms6 is a protein that is associated with magnetosomes in M. magneticum AMB-1 and is believed to control the synthesis of magnetite (Fe(3)O(4)) withi...

The identification of a family of NAR2-type genes in higher plants showed that there was a homolog in Arabidopsis (Arabidopsis thaliana), AtNAR2.1. These genes encode part of a two-component nitrate high-affinity transport system (HATS). As the Arabidopsis NRT2 gene family of nitrate transporters has been characterized, we tested the idea that AtNAR2.1 and AtNRT2.1 are partners in a two-compone...

The transcription factor AtMYB2 binds to two sequence motifs in the promoter of the Arabidopsis ADH1 gene. The binding to the GT-motif (5'-TGGTTT-3') is essential for induction of ADH1 by low oxygen, while binding to the second motif, MBS-2, is not essential for induction. We show that AtMYB2 is induced by hypoxia with kinetics compatible with a role in the regulation of ADH1. Like ADH1, AtMYB2...

In eukaryotes, manganese superoxide dismutase is a nuclear-encoded protein that scavenges superoxide radicals in the mitochondrial matrix. We have isolated two manganese superoxide dismutase genes from Nicotiana plumbaginifolia L. and fused the 5' upstream regulatory region of these genes to the beta-glucuronidase reporter gene. The two gene fusions displayed a differential tissue specificity i...

Intragenic complementation has been observed between apoenzyme nitrate reductase-deficient mutants (nia) of Nicotiana plumbaginifolia. In vivo as in vitro, the NADH-nitrate reductase (NR) activity in plants heterozygous for two different nia alleles was lower than in the wild type plant, but the plants were able to grow on nitrate as a sole nitrogen source. NR activity, absent in extracts of ho...

Sucrose (Suc):Suc 1-fructosyltransferase (1-SST) is the key enzyme in plant fructan biosynthesis, since it catalyzes de novo fructan synthesis from Suc. We have cloned 1-SST from onion (Allium cepa) by screening a cDNA library using acid invertase from tulip (Tulipa gesneriana) as a probe. Expression assays in tobacco (Nicotiana plumbaginifolia) protoplasts showed the formation of 1-kestose fro...