Rosistilla oblonga gen. nov., sp. nov. and Rosistilla carotiformis sp. nov., isolated from biotic or abiotic surfaces in Northern Germany, Mallorca, Spain and California, USA

Planctomycetes are ubiquitous bacteria with fascinating cell biological features. Strains available as axenic cultures in most cases have been isolated from aquatic environments and serve as a basis to study planctomycetal cell biology and interactions in further detail. As a contribution to the current collection of axenic cultures, here we characterise three closely related strains, Poly24$^{T}$, CA51$^{T}$ and Mal33, which were isolated from the Baltic Sea, the Pacific Ocean and the Mediterranean Sea, respectively. The strains display cell biological features typical for related Planctomycetes, such as division by polar budding, presence of crateriform structures and formation of rosettes. Optimal growth was observed at temperatures of 30–33 °C and at pH 7.5, which led to maximal growth rates of 0.065–0.079 h$^{-1}$, corresponding to generation times of 9–11 h. The genomes of the novel isolates have a size of 7.3–7.5 Mb and a G + C content of 57.7–58.2%. Phylogenetic analyses place the strains in the family Pirellulaceae and suggest that Roseimaritima ulvae and Roseimaritima sediminicola are the current closest relatives. Analysis of five different phylogenetic markers, however, supports the delineation of the strains from members of the genus Roseimaritima and other characterised genera in the family. Supported by morphological and physiological differences, we conclude that the strains belong to the novel genus Rosistilla gen. nov. and constitute two novel species, for which we propose the names Rosistilla carotiformis sp. nov. and Rosistilla oblonga sp. nov. (the type species). The two novel species are represented by the type strains Poly24$^{T}$ (= DSM 102938$^{T}$ = VKM B-3434$^{T}$ = LMG 31347$^{T}$ = CECT 9848$^{T}$) and CA51$^{T}$ (= DSM 104080$^{T}$ = LMG 29702$^{T}$), respectively

The Microbiome of Posidonia oceanica Seagrass Leaves Can Be Dominated by Planctomycetes

Seagrass meadows are ubiquitous, fragile and endangered marine habitats, which serve as fish breeding grounds, stabilize ocean floor substrates, retain nutrients and serve as important carbon sinks, counteracting climate change. In the Mediterranean Sea, seagrass meadows are mostly formed by the slow-growing endemic plant Posidonia oceanica (Neptune grass), which is endangered by global warming and recreational motorboating. Despite its importance, surprisingly little is known about the leaf surface microbiome of P. oceanica. Using amplicon sequencing, we here show that species belonging to the phylum Planctomycetes can dominate the biofilms of young and aged P. oceanica leaves. Application of selective cultivation techniques allowed for the isolation of two novel planctomycetal strains belonging to two yet uncharacterized genera

Alternate wiring of a KNOXI genetic network underlies differences in leaf development of A. thaliana and C. hirsuta

Two interrelated problems in biology are understanding the regulatory logic and predictability of morphological evolution. Here, we studied these problems by comparing Arabidopsis thaliana, which has simple leaves, and its relative, Cardamine hirsuta, which has dissected leaves comprising leaflets. By transferring genes between the two species, we provide evidence for an inverse relationship between the pleiotropy of SHOOTMERISTEMLESS (STM) and BREVIPEDICELLUS (BP) homeobox genes and their ability to modify leaf form. We further show that cis-regulatory divergence of BP results in two alternative configurations of the genetic networks controlling leaf development. In C. hirsuta, ChBP is repressed by the microRNA164A (MIR164A)/ChCUP-SHAPED COTYLEDON (ChCUC) module and ChASYMMETRIC LEAVES1 (ChAS1), thus creating cross-talk between MIR164A/CUC and AS1 that does not occur in A. thaliana. These different genetic architectures lead to divergent interactions of network components and growth regulation in each species. We suggest that certain regulatory genes with low pleiotropy are predisposed to readily integrate into or disengage from conserved genetic networks influencing organ geometry, thus rapidly altering their properties and contributing to morphological divergence

Characterization of iCell cardiomyocytes using single-cell RNA-sequencing methods

IntroductionHuman induced pluripotent stem cell (hiPSC)-derived cardiomyocytes are being evaluated for their use in pharmacological and toxicological testing, particularly for electrophysiological side effects. However, little is known about the composition of the commercially available iCell cardiomyocyte (Fuijifilm Cellular Dynamics) cultures and the transcriptomic phenotype of individual cells.MethodsWe characterized iCell cardiomyocytes (assumed to be a mixture of nodal-, atrial-, and ventricular-like cardiomyocytes together with potential residual non-myocytes) using bulk RNA-sequencing, followed by investigation of cellular heterogeneity using two different single-cell RNA-sequencing platforms.ResultsBulk RNA-sequencing identified key cardiac markers (TNNT2, MYL7) as well as fibroblast associated genes (P4HB, VIM), and cardiac ion channels in the iCell cardiomyocyte culture. High-resolution single cell RNA-sequencing demonstrated that both, cardiac and fibroblast-related genes were co-expressed throughout the cell population. This approach resolved two cell clusters within iCell cardiomyocytes. Interestingly, these clusters could not be associated with known cardiac subtypes. However, transcripts of ion channels potentially useful as functional markers for cardiac subtypes were below the detection limits of the single-cell approaches used. Instead, one cluster (10.8% of the cells) is defined by co-expression of cardiac and cell cycle-related genes (e.g. TOP2A). Incorporation of bromodeoxyuridine further confirmed the capability of iCell cardiomyocytes to enter cell cycle.DiscussionThe co-expression of cardiac related genes with cell cycle or fibroblast related genes may be interpreted either as aberrant or as an immature feature. However, this excludes the presence of a non-cardiomyocyte sub-population and indicates that some cardiomyocytes themselves enter cell cycle.publishe

Église Saint Jean-Baptiste : étude archéologique d'une église piévane de l'Alta Rocca : Corse, Corse-du-Sud (2A), Sainte-Lucie-de-Tallano: Rapport de fouille

L’église de Saint Jean Baptiste, a été bâtie sur les terres du hameau de Poggio qui dépend de la commune de Sainte Lucie de Tallano, au lieu dit Pieve e San Giovani. Construite sur les terres de l’ancienne piève d’Attalà,, elle est isolée et éloignée des villages alentours. Le cours d’eau du Rizzanese, coule en contrebas de l’église à environ 500 m. L’édifice est construit sur un promontoire « poggio », au sommet aplani, représentant une surface d’environ 400 m² culminant à environ 325 m..Le cadre historique de cette fouille s’inscrit dans ce que les textes du bas-Moyen Âge désignent comme l’Au-delà des Monts (A Tirra Dila Da Monti) et qui correspond à l’actuel département de Corse-du-Sud. C’est à l’intérieur de cet espace historique intimement lié à la géographie physique que prend place cette étude.San Ghuvan Battista est traditionnellement datée de la période pisane (XIIe siècle) et s’inscrit dans une politique de construction et de reconstruction sur l’ensemble du territoire initiée par la commune de Pise et réalisée sous le contrôle de l’église.L’église San Ghuvan Battista, adopte le plan d’une église à nef unique, sans transept avec une seule abside semi circulaire et chœur en cul de four. Le matériau employé : le granit, est une source dont l’approvisionnement est manifestement local, bien qu’il paraisse de prime abord exogène au substrat local qui se caractérise plus souvent par un granit à gros grains visible dans de nombreuses constructions. Le grain fin du matériau, sa composition minérale et son apparente homogénéité chromatique donnent à l’édifice la vision d’une construction harmonieuse.L’observation du bâti a montré un problème de stabilité de l’édifice qui semble existé depuis sa construction. En effet, on observe sur le parement externe du mur gouttereau nord, une césure verticale, qui marque une rupture dans le bâtiment se caractérisant par un élargissement anormal des joints.A travers l’étude des quelques sources écrites, l’analyse du bâti et des deux campagnes de fouilles (2013 et 2014) menées à l’extérieur et dans le chœur de l’église, il a été possible de retracer une partie de l’histoire du site de Saint Jean Baptiste. De plus, cette histoire s’est largement enrichie d’une importante étude anthropologique.Peu d’églises de piève ont été fouillées en Corse et l’exemple de Saint Jean Baptiste permet de documenter un type de site qui a joué un rôle important dans la gestion de l’île de Corse.L’église comme bâtiment est un monument signe architecturalement, mais pas seulement. Elle est aussi le marqueur fort en Corse de la présence pisane et de l’église sur un territoire nouvellement conquis ou au moins « pacifié ».Ces fouilles ont permis d’étudier une partie de la construction et de proposer une évolution de celle-ci. La provenance locale des matériaux, et la mise en œuvre que l’on retrouve dans beaucoup d’autres édifices contemporains sont les signes d’un savoir-faire insulaire, couplé à une architecture très caractéristique venant des rivages orientaux de la mer Tyrrhénienne. Elle est la marque de la présence italienne sur la Corse, qui imprégnera l’île de ses modèles architecturaux tout au long du Moyen Âge et de l’époque moderne

Developing techniques for the utilization of Planctomycetes as producers of bioactive molecules

Planctomycetes are conspicuous, ubiquitous, environmentally important bacteria. They can attach to various surfaces in aquatic habitats and form biofilms. Their unique FtsZ-independent budding cell division mechanism is associated with slow growth and doubling times from six hours up to one month. Despite this putative disadvantage in the struggle to colonize surfaces, Planctomycetes are frequently associated with aquatic phototrophic organisms such as diatoms, cyanobacteria or kelp, whereby Planctomycetes can account for up to 50 % of the biofilm-forming bacterial population. Consequently, Planctomycetes were postulated to play an important role in carbon utilization, for example as scavengers after phototrophic blooms. However, given their observed slow growth, such findings are surprising since other faster- growing heterotrophs tend to colonize similar ecological niches. Accordingly, Planctomycetes were suspected to produce antibiotics for habitat protection in response to the attachment on phototrophs. Recently, we demonstrated their genomic potential to produce nonribosomal peptides, polyketides, bacteriocins, and terpenoids that might have antibiotic activities. In this study, we describe the development of a pipeline that consists of tools and procedures to cultivate Planctomycetes for the production of antimicrobial compounds in a chemically- defined medium and a procedure to chemically mimic their interaction with bacteria such as for example Cyanobacteria. We evaluated and adjusted screening assays to allow the hunt for planctomycetal antibiotics. As proof of principle, we demonstrate antimicrobial activities of planctomycetal extracts from Planctopirus limnophila DSM 3776, Rhodopirellula baltica DSM 10527, and the recently isolated strain Pan216. By combining UV/Vis and high resolution mass spectrometry data from High-Performance Liquid Chromatography fractionations with growth inhibition of indicator strains, we were able to assign the antibiotic activity to candidate peaks related to planctomycetal antimicrobial compounds. The MS analysis points towards the production of novel bioactive molecules with novel structures. Consequently, we developed a large scale cultivation procedure to allow future structural elucidation of such compounds.Our findings might have implications for the discovery of novel antibiotics as Planctomycetes represent a yet untapped resource that could be developed by employing the tools and methods described in this study