by Keyword: IncHI

Mattotti, M., Alvarez, Z., Delgado, L., Mateos-Timoneda, M. A., Aparicio, C., Planell, J. A., Alcántara, S., Engel, E., (2017). Differential neuronal and glial behavior on flat and micro patterned chitosan films Colloids and Surfaces B: Biointerfaces 158, 569-577

Chitosan is a biodegradable natural polysaccharide that has been widely studied for regenerative purposes in the central nervous system. In this study we assessed the in vitro glial and neuronal cells response to chitosan either flat or patterned with grooves in the micrometric range. Chitosan demonstrated to be a good substrate for the attachment and growth of both neurons and glial cells. Chitosan micropatterns promoted glial cell maturation, suggesting astroglial activation. Nevertheless, those mature/reactive glial cells were permissive for axonal growth. Axons aligned and organized along the patterned grooves and the size of the linear topographic patterns is also affecting neurite and cell response. Patterns with 10 μm width induced fasciculation of axons, which can be useful for CNS tissue engineering substrates when precise orientation of the axonal outgrowth is desired.

JTD Keywords: Brain, Chitosan, Glia, Micropattern, Neuron

Tassinari, E., Aznar, S., Urcola, I., Prieto, A., Hüttener, M., Juárez, A., (2016). The incC sequence is required for R27 plasmid stability Frontiers in Microbiology 7, (6), Article 629

IncHI plasmids account for multiple antimicrobial resistance in Salmonella and other enterobacterial genera. These plasmids are generally very stable in their bacterial hosts. R27 is the archetype of IncHI1 plasmids. A high percentage of the R27-encoded open reading frames (ORFs) (66.7%) do not show similarity to any known ORFs. We performed a deletion analysis of all non-essential R27 DNA sequences to search for hitherto non-identified plasmid functions that might be required for plasmid stability. We report the identification of a short DNA sequence (incC) that is essential for R27 stability. That region contains several repeats (incC repeats), belongs to one of the three-plasmid replicons (R27 FIA-like) and is targeted by the R27 E protein. Deletion of the incC sequence drastically reduces R27 stability both in Escherichia coli and in Salmonella, the effect being more pronounced in this latter species. Interfering with incC-E protein interaction must lead to a reduced IncHI1 plasmid stability, and may represent a new approach to combat antimicrobial resistance.

JTD Keywords: Antimicrobial resistance, E protein, IncC, IncHI1 plasmids, Plasmid R27, Plasmid stability

Gilbert, M., Juárez, A., Madrid, C., Balsalobre, C., (2013). New insights in the role of HtdA in the regulation of R27 conjugation Plasmid International Society for Plasmid Biology Meeting , Elsevier (Santander, Spain) 70 (1), 61-68

R27 is the prototype of the IncHI group of conjugative plasmids, which are associated with multidrug resistance in several relevant pathogens. The transfer of this plasmid is thermodependent and all transfer-related genes are encoded in six operons (tra operons). Very little is known about the factors involved in the regulation of the R27 conjugation. This report describes transcriptional studies of the six tra operons. Our results indicate that HtdA, encoded in the R27 plasmid, is involved in the transcriptional repression of four tra operons (F, H, AC and Z). Although HtdA plays a pivotal role in the transcriptional regulation of those operons, it does not exert its effect as a classical repressor. The data indicate the existence of a crosstalk between HtdA and other unknown regulatory factors. The HtdA-mediated regulation of conjugation is independent of the R27 H-NS protein.

JTD Keywords: Plasmid conjugation, IncHI, R27, tra Operons regulation, HtdA