Inoculating and Observing Arbuscular Mycorrhizal Cultures on Superabsorbent Polymer-Based Autotrophic Systems.

Arbuscular mycorrhizal (AM) fungi are difficult to manipulate and observe due to their permanent association with plant roots and propagation in the rhizosphere. Typically, AM fungi are cultured under in vivo conditions in pot culture with an autotrophic host or under in vitro conditions with Ri Transfer-DNA transformed roots (heterotrophic host) in a Petri dish. Additionally, the cultivation of AM fungi in pot culture occurs in an opaque and non-sterile environment. In contrast, in vitro culture involves the propagation of AM fungi in a sterile, transparent environment. The superabsorbent polymer-based autotrophic system (SAP-AS) has recently been developed and shown to combine the advantages of both methods while avoiding their respective limitations (opacity and heterotrophic host, sterility). Here, we present a detailed protocol for easy preparation, single spore inoculation, and observation of AM fungi in SAP-AS. By modifying the Petri dishes, high-resolution photographic and video observations were possible on living specimens, which would have been difficult or impossible with current in vivo and in vitro techniques.

Draft genome sequences of Chryseobacterium sp. MHB01, Rhodococcus qingshengii MHB02, and Agrobacterium tumefaciens MHB03 isolated from superabsorbent polymer granules inoculated with an arbuscular mycorrhizal fungus.

Chryseobacterium sp. MHB01, Rhodococcus qingshengii MHB02, and Agrobacterium tumefaciens MHB03 were isolated from superabsorbent polymer granules cultured with an arbuscular mycorrhizal fungus. Whole-genome sequencing of these three strains revealed genome sizes of 4.57 Mb, 7.13 Mb, and 5.49 Mb with G + C contents of 36.9%, 62.5%, and 58.2%, respectively.

Transcriptomic landscape of posterior regeneration in the annelid Platynereis dumerilii.

BACKGROUND: Restorative regeneration, the capacity to reform a lost body part following amputation or injury, is an important and still poorly understood process in animals. Annelids, or segmented worms, show amazing regenerative capabilities, and as such are a crucial group to investigate. Elucidating the molecular mechanisms that underpin regeneration in this major group remains a key goal. Among annelids, the nereididae Platynereis dumerilii (re)emerged recently as a front-line regeneration model. Following amputation of its posterior part, Platynereis worms can regenerate both differentiated tissues of their terminal part as well as a growth zone that contains putative stem cells. While this regeneration process follows specific and reproducible stages that have been well characterized, the transcriptomic landscape of these stages remains to be uncovered. RESULTS: We generated a high-quality de novo Reference transcriptome for the annelid Platynereis dumerilii. We produced and analyzed three RNA-sequencing datasets, encompassing five stages of posterior regeneration, along with blastema stages and non-amputated tissues as controls. We included two of these regeneration RNA-seq datasets, as well as embryonic and tissue-specific datasets from the literature to produce a Reference transcriptome. We used this Reference transcriptome to perform in depth analyzes of RNA-seq data during the course of regeneration to reveal the important dynamics of the gene expression, process with thousands of genes differentially expressed between stages, as well as unique and specific gene expression at each regeneration stage. The study of these genes highlighted the importance of the nervous system at both early and late stages of regeneration, as well as the enrichment of RNA-binding proteins (RBPs) during almost the entire regeneration process. CONCLUSIONS: In this study, we provided a high-quality de novo Reference transcriptome for the annelid Platynereis that is useful for investigating various developmental processes, including regeneration. Our extensive stage-specific transcriptional analysis during the course of posterior regeneration sheds light upon major molecular mechanisms and pathways, and will foster many specific studies in the future.

Rhizophagus irregularis, the model fungus in arbuscular mycorrhiza research, forms dimorphic spores.

Rhizophagus irregularis is the model species for arbuscular mycorrhizal fungi (AMF) research and the most widely propagated species for commercial plant biostimulants. Using asymbiotic and symbiotic cultivation systems initiated from single spores, advanced microscopy, Sanger sequencing of the glomalin gene, and PacBio sequencing of the partial 45S rRNA gene, we show that four strains of R. irregularis produce spores of two distinct morphotypes, one corresponding to the morphotype described in the R. irregularis protologue and the other having the phenotype of R. fasciculatus. The two spore morphs are easily distinguished by spore colour, thickness of the subtending hypha, thickness of the second wall layer, lamination of the innermost layer, and the dextrinoid reaction of the two outer spore wall layers to Melzer's reagent. The glomalin gene of the two spore morphs is identical and that of the PacBio sequences of the partial SSU-ITS-LSU region (2780 bp) obtained from single spores of the R. cf fasciculatus morphotype has a median pairwise similarity of 99.8% (SD = 0.005%) to the rDNA ribotypes of R. irregularis DAOM 197198. Based on these results, we conclude that the model AMF species R. irregularis is dimorphic, which has caused taxonomic confusion in culture collections and possibly in AMF research.

FVIII regulates the molecular profile of endothelial cells: functional impact on the blood barrier and macrophage behavior.

Hemophilia A is an inherited X-linked recessive bleeding disorder caused by deficient activity of blood coagulation factor VIII (FVIII). In addition, hemophilia patients show associated diseases including osteopenia, altered inflammation and vascular fragility which may represent the consequence of recurrent bleeding or may be related to the direct FVIII deficiency. Nowadays, recombinant FVIII is proposed to treat hemophilia patients with no circulating FVIII inhibitor. Initially described as a coenzyme to factor IXa for initiating thrombin generation, there is emerging evidence that FVIII is involved in multiple biological systems, including bone, vascular and immune systems. The present study investigated: (i) the functional activities of recombinant human FVIII (rFVIII) on endothelial cells, and (ii) the impact of rFVIII activities on the functional interactions of human monocytes and endothelial cells. We then investigated whether rFVIII had a direct effect on the adhesion of monocytes to the endothelium under physiological flow conditions. We observed that direct biological activities for rFVIII in endothelial cells were characterized by: (i) a decrease in endothelial cell adhesion to the underlying extracellular matrix; (ii) regulation of the transcriptomic and protein profiles of endothelial cells; (iii) an increase in the vascular tubes formed and vascular permeability in vitro; and (iv) an increase in monocyte adhesion activated endothelium and transendothelial migration. By regulating vascular permeability plus leukocyte adhesion and transendothelial migration, the present work highlights new biological functions for FVIII.