Transcriptome dynamics of a broad host-range cyanophage and its hosts

Cyanobacteria are highly abundant in the oceans and are constantly exposed to lytic viruses. The T4-like cyanomyoviruses are abundant in the marine environment and have broad host-ranges relative to other cyanophages. It is currently unknown whether broad host-range phages specifically tailor their infection program for each host, or employ the same program irrespective of the host infected. Also unknown is how different hosts respond to infection by the same phage. Here we used microarray and RNA-seq analyses to investigate the interaction between the Syn9 T4-like cyanophage and three phylogenetically, ecologically and genomically distinct marine Synechococcus strains: WH7803, WH8102 and WH8109. Strikingly, Syn9 led a nearly identical infection and transcriptional program in all three hosts. Different to previous assumptions for T4-like cyanophages, three temporally regulated gene expression classes were observed. Furthermore, a novel regulatory element controlled early-gene transcription, and host-like promoters drove middle gene transcription, different to the regulatory paradigm for T4. Similar results were found for the P-TIM40 phage during infection of Prochlorococcus NATL2A. Moreover, genomic and metagenomic analyses indicate that these regulatory elements are abundant and conserved among T4-like cyanophages. In contrast to the near-identical transcriptional program employed by Syn9, host responses to infection involved host-specific genes primarily located in hypervariable genomic islands, substantiating islands as a major axis of phage-cyanobacteria interactions. Our findings suggest that the ability of broad host-range phages to infect multiple hosts is more likely dependent on the effectiveness of host defense strategies than on differential tailoring of the infection process by the phage

Culture of PC12 neuronal cells in GelMA hydrogel for brain tissue engineering

Restoration of brain functions following trauma or degenerative neural diseases is considered among the greatest challenges in neurology due to the fact that the central nervous system (CNS) does not regenerate on its own. Tissue engineering offers a potential solution in developing artificial neural/brain tissues. Numerous hydrogel based biomaterials have been investigated in the field of neural tissue engineering. However, the lack of the optimum combination of mechanical and biological properties in commonly available hydrogels represents a major bottle neck in growing artificial neural tissues. In this study, 3 dimensional cell culture of PC12 neuronal cells have been investigated in methacrylated Gelatin (GelMA) hydrogel for brain tissue engineering. The cell viability and propagation of PC12 neural cell lines on GelMA-based hydrogel was tested revealing its positive effects on these cells. In addition, cytotoxicity was assessed in vivo showing that implantation of GelMA did not show any acute neurotoxic effects in mice exposed to experimental brain injury.Scopu