The PsENOD12 Gene Is Expressed at Two Different Sites in Afghanistan Pea Pseudonodules Induced by Auxin Transport Inhibitors

A number of early nodulin genes are expressed in specific cell types as pea (Pisum sativum) root nodules develop. The Pisum sativum early nodulin PsENOD2 is detected only in the uninfected cells of the nodule parenchyma, whereas PsENOD12 is expressed at two spatially removed sites: in root hairs and adjacent cortical cells, both of which can be invaded by Rhizobium entering through infection threads, and in derivatives of newly divided root inner cortical cells that establish the nodule primordium. We tested whether Rhizobium infection is required for triggering PsENOD12 gene expression by inducing nodule-like structures on Afghanistan pea roots with the auxin transport inhibitor N-(1-naphthyl)phthalamic acid (NPA). These nodule-like structures lack infection threads but resemble Rhizobium-induced nodules in other aspects. For one, both PsENOD2 and PsENOD12 transcripts were detected in these structures. PsENOD2 mRNA was localized by in situ hybridization to a zone equivalent to the nodule parenchyma of Rhizobium-induced nodules, whereas PsENOD12 transcripts were detected in a group of cells comparable to the nodule primordium of developing nodules. In addition, PsENOD12 mRNA was detected in uninfected root hairs 48 h after NPA treatment. These results indicate that infection is not a trigger for PsENOD12 gene expression in Afghanistan pea and rather suggest that the expression of the PsENOD2 and PsENOD12 genes is correlated with the differentiation of specific cell types in the developing nodule

Drug delivery by nanoparticles - facing the obstacles

There are numerous concepts of nanoparticle mediated drug delivery. The major advantage will be the option of targeted drug delivery to specific target cells thus avoiding high systemic loads of potentially toxic chemicals. Any kind of drug delivery by nanoparticles relies on delivery of the drug into the cell. In most cases that means drug delivery into the cytoplasm, and in some instances delivery of the drug to extracellular domains of transmembrane signalling molecules. Whenever viable cells are confronted with nanoparticles these are ingested by endocytosis rather then passage through the cell plasma membrane. Once inside endosomal vesicles the nanoparticles or at least their drug payload requires release into the cytoplasm in order to exert it’s biological effect. In order to monitor whether a drug delivered by nanoparticles is biologically active a toxic model drug, disulfiram, was chosen as a payload with micelle and liposome nanoparticles. L929 mouse fibroblasts were incubated with these disulfiram loaded naoparticles and cell viability was determined by quantification of celluar reductase activity. Applied nanoparticles are toxic to the cells. However, with respect to the disulfiram payload a 100-fold higher disulfiram concentration is required in comparison to free disulfiram for a biological effect. Hence, the toxic effect is most likely not due to the disulfiram delivered by the nanoparticles but rather to the amount of free disulfiram that is present in the nanoparticle preparation. Therefore it is advised to carefully characterize the nanoparticle suspension for the amount of free payload molecule