Functional monomer impurity affects adhesive performance

Objective The functional monomer 10-MDP has been considered as one of the best performing functional monomers for dental adhesives. Different adhesives containing 10-MDP are commercially available, among which many so-called ‘universal’ adhesives. We hypothesize that the quality of the functional monomer 10-MDP in terms of purity may affect bonding performance. Methods We therefore characterized three different 10-MDP versions (10-MDP_KN provided by Kuraray Noritake; 10-MDP_PCM provided by PCM; 10-MDP_DMI provided by DMI) using NMR, and analyzed their ability to form 10-MDP_Ca salts on dentin using XRD. The ‘immediate’ and ‘aged’ micro-tensile bond strength (μTBS) to dentin of three experimental 10-MDP primers was measured. The resultant interfacial adhesive-dentin ultra-structure was characterized using TEM. Results NMR disclosed impurities and the presence of 10-MDP dimer in 10-MDP_PCM and 10-MDP_DMI. 10-MDP_PCM and 10-MDP_DMI appeared also sensitive to hydrolysis. 10-MDP_KN, on the contrary, contained less impurities and dimer, and did not undergo hydrolysis. XRD revealed more intense 10-MDP_Ca salt deposition on dentin induced by 10-MDP_KN. The adhesive based on the experimental 10-MDP_KN primer resulted in a significantly higher ‘immediate’ bond strength that remained stable upon aging; the μTBS of the experimental 10-MDP_PCM and 10-MDP_DMI adhesives significantly dropped upon aging. TEM revealed thicker hybridization and more intense nano-layering for 10-MDP_KN.publisher: Elsevier articletitle: Functional monomer impurity affects adhesive performance journaltitle: Dental Materials articlelink: http://dx.doi.org/10.1016/j.dental.2015.09.019 content_type: article copyright: Copyright © 2015 Published by Elsevier Ltd.status: publishe

On the alleged origin of geminiviruses from extrachromosomal DNAs of phytoplasmas

<p>Abstract</p> <p>Background</p> <p>Several phytoplasmas, wall-less phloem limited plant pathogenic bacteria, have been shown to contain extrachromosomal DNA (EcDNA) molecules encoding a replication associated protein (Rep) similar to that of geminiviruses, a major group of single stranded (ss) DNA plant viruses. On the basis of that observation and of structural similarities between the capsid proteins of geminiviruses and the <it>Satellite tobacco necrosis virus</it>, it has been recently proposed that geminiviruses evolved from phytoplasmal EcDNAs by acquiring a capsid protein coding gene from a co-invading plant RNA virus.</p> <p>Results</p> <p>Here we show that this hypothesis has to be rejected because (i) the EcDNA encoded Rep is not of phytoplasmal origin but has been acquired by phytoplasmas through horizontal transfer from a geminivirus or its ancestor; and (ii) the evolution of geminivirus capsid protein in land plants implies missing links, while the analysis of metagenomic data suggests an alternative scenario implying a more ancient evolution in marine environments.</p> <p>Conclusion</p> <p>The hypothesis of geminiviruses evolving in plants from DNA molecules of phytoplasma origin contrasts with other findings. An alternative scenario concerning the origin and spread of Rep coding phytoplasmal EcDNA is presented and its implications on the epidemiology of phytoplasmas are discussed.</p

Phytoplasma effectors and pathogenicity factors

For the study and the management of phytoplasma-associated diseases, the most relevant knowledge needed is the one related to their pathogenicity. After the availability of full and draft genome sequences of some of the phytoplasmas, a mining search allowed identifying a number of possible virulence factors. Their possible pathogenic action was verified mainly by their expression in transgenic plants such as Arabidopsis spp. and Nicotiana spp. Several possible pathogenicity factors such as TENGU and SAP11 and/or effector molecules were shown to be related to metabolic and or phenotypic modifications indistinguishable from those present in the phytoplasma-infected plants such as phyllody and witches\u2019 broom. The possible pathogenicity factors or disease effectors studied enclosing extrachromosomal DNAs, phloem structural modifications, and very recently miRNAs are also described