Distribution of arabinogalactan protein (AGP) epitopes on the anther derived embryoid cultures of Brassica napus

The anther-derived embryoid cultures of Brassica napus is stably embryogenic and has an extracellular matrix (ECM) layer covering the surface of the developing embryoids. In this study, the distribution of arabinogalactan protein (AGP) epitopes in the ECM layer and the embryogenic tissue of winter oilseed rape were investigated by immuno-labelling with anti-AGP monoclonal antibodies (mAb JIM4, JIM8, and JIM 13). There was no labelling by the JIM4 and JIM8 mAbs in the ECM layer, unlike what was reported in other plant species. JIM 13 epitope is developmentally regulated because it was only present in the ECM layer of the mature embryogenic tissue. These observations indicate a possible variability in the AGP epitopes present in the ECM layer among the different plant species. JIM8 and JIM 13 epitopes were found in some epidermal cells of embryogenic tissue, but not in the non-embryogenic tissue, implying that AGPs might have a specific role in embryogenic competency or determining the cell fate of the B. napus embryogenic cell

Extracellular localization of napin in the embryogenic tissues of Brassica napus spp. oleifera

Napin, a storage protein, has been reported to be transcribed abundantly during the pre-embryogenic stage and associated with the induction of Brassica napus secondary embryogenesis. In this study, we studied the distribution pattern of napin in the winter oilseed rape embryogenic tissue in comparison to that of the non-embryogenic tissue using the indirect immunofluorescence localisation coupled with the ultrastructural immunogold labelling techniques. Immunolocalisation studies revealed that the extracellular matrix layer outside the outer epidermal cell wall of B. napus embryogenic tissues contained napin. This is the first study to report the extracellular localisation of napin. In addition, we have also further characterised the expression pattern of Eg1 that encodes for napin in the B. napus embryogenic tissue

An endogenous nanomineral chaperones luminal antigen and peptidoglycan to intestinal immune cells.

In humans and other mammals it is known that calcium and phosphate ions are secreted from the distal small intestine into the lumen. However, why this secretion occurs is unclear. Here, we show that the process leads to the formation of amorphous magnesium-substituted calcium phosphate nanoparticles that trap soluble macromolecules, such as bacterial peptidoglycan and orally fed protein antigens, in the lumen and transport them to immune cells of the intestinal tissue. The macromolecule-containing nanoparticles utilize epithelial M cells to enter Peyer's patches, small areas of the intestine concentrated with particle-scavenging immune cells. In wild-type mice, intestinal immune cells containing these naturally formed nanoparticles expressed the immune tolerance-associated molecule 'programmed death-ligand 1', whereas in NOD1/2 double knockout mice, which cannot recognize peptidoglycan, programmed death-ligand 1 was undetected. Our results explain a role for constitutively formed calcium phosphate nanoparticles in the gut lumen and show how this helps to shape intestinal immune homeostasis