Transformation of potato using mannopine and cucumopine strains of Agrobacterium rhizogenes

Mannopine and cucumopine strains of Agrobacterium rhizogenes were used for genetic transformation in two cultivars of potato (Solanum tuberosum L.). An overnight pretreatment of stem fragments with NAA prior to bacterial infection was necessary to induce root formation, otherwise very few roots were produced. Whatever the potato cultivar used, rhizogenesis induced by NAA pretreament depended on the bacterial strain. In fact, when explants from both potato cultivars were pretreated with 26.5 M NAA, on average 84.4% and 71.9% produced roots after inoculation with the strains 2659 and 2659 GUS respectively. On the contrary, few rhizogenic responses (2.0–17.0%) or no response at all (0.0%) were obtained with the strains 15834 and 8196 GUS whatever NAA concentration used. Tests for confirming stable transformation of plant explants by examining both -glucuronidase activity and the presence of opines showed that 85% of the selected roots were cotransformed. Most of the transformed roots were highly branched and grew rapidly, compared to non-transformed roots with no branching and poor growth. Transgenic plants were readily regenerated with a frequency reaching 80% of total explants tested for both potato cultivars.Abbreviations BA 6-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - df degree of freedom - F F distribution - GA₃ gibberellic acid - MS Murashige and Skoog basal medium - NAA -naphthaleneacetic acid - P probability - T-DNA transferred DNA     

Endothelial cell junctions

In the course of a freeze-cleave study on intercellular junctions in the regenerating rat liver, we observed an unusual array of intramembranous particles located in regions of contact between endothelial cells lining the hepatic sinusoids. These arrays were characterized by an accumulation of particles which resembled a zonula occludens in their linear deployment but differed in that the contact regions were composed of individual particles which remained separated from each other by regular particle-free intervals.     

Target highlights in CASP13: Experimental target structures through the eyes of their authors

The functional and biological significance of selected CASP13 targets are described by the authors of the structures. The structural biologists discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP13 experiment.