Search

BackgroundExposure of critically ill patients to antibiotics lead to intestinal dysbiosis, which often manifests as antibiotic-associated diarrhoea. Faecal microbiota transplantation restores gut microbiota and may lead to faster resolution of diarrhoea.MethodsInto this prospective, multi-centre, randomized controlled trial we will enrol 36 critically ill patients with antibiotic-associated diarrhoea. We will exclude patients with ongoing sepsis, need of systemic antibiotics, or those after recent bowel surgery or any other reason that prevents the FMT. Randomisation will be in 1:1 ratio. Patients in the control group will receive standard treatment based on oral diosmectite. In the intervention group, patients will receive, in addition to the standard of care, faecal microbiota transplantation via rectal tube, in the form of a preparation mixed from 7 thawed aliquots (50 mL) made from fresh stool of 7 healthy unrelated donors and quarantined deep frozen for 3 to 12 months. Primary outcome is treatment failure defined as intervention not delivered or diarrhoea persisting at day 7 after randomisation. Secondary outcomes include safety measures such as systemic inflammatory response, adverse events, and also diarrhoea recurrence within 28 days. Exploratory outcomes focus on gut barrier function and composition of intestinal microbiota.DiscussionFaecal microbiota transplantation has been effective for dysbiosis in non-critically ill patients with recurrent C. difficile infections and it is plausible to hypothesize that it will be equally effective for symptoms of dysbiosis in the critically ill patients. In addition, animal experiments and observational data suggest other benefits such as reduced colonization with multi-drug resistant bacteria and improved gut barrier and immune function. The frozen faeces from unrelated donors are immediately available when needed, unlike those from the relatives, who require lengthy investigation. Using multiple donors maximises graft microbiota diversity. Nonetheless, in vulnerable critically ill patients, Faecal microbiota transplantation might lead to bacterial translocation and unforeseen complications. From growing number of case series it is clear that its off label use in the critically ill patients is increasing and that there is a burning need to objectively assess its efficacy and safety, which this trial aims.Trial registrationwww.clinicaltrials.gov (NCT05430269).

Pollen germination and subsequent pollen tube elongation are essential for successful land plant reproduction. These processes are achieved through well-documented activation of membrane trafficking and cell metabolism. Despite this, our knowledge of the dynamics of cellular phospholipids remains scarce. Here we present the turnover of the glycerolipid composition during the establishment of cell polarity and elongation processes in tobacco pollen and show the lipid composition of pollen plasma membrane-enriched fraction for the first time. To achieve this, we have combined several techniques, such as lipidomics, plasma membrane isolation, and live-cell microscopy, and performed a study with different time points during the pollen germination and pollen tube growth. Our results showed that tobacco pollen tubes undergo substantial changes in their whole-cell lipid composition during the pollen germination and growth, finding differences in most of the glycerolipids analyzed. Notably, while lysophospholipid levels decrease during germination and growth, phosphatidic acid increases significantly at cell polarity establishment and continues with similar abundance in cell elongation. We corroborated these findings by measuring several phospholipase activities in situ. We also observed that lysophospholipids and phosphatidic acid are more abundant in the plasma membrane-enriched fraction than that in the whole cell. Our results support the important role for the phosphatidic acid in the establishment and maintenance of cellular polarity in tobacco pollen tubes and indicate that plasma membrane lysophospholipids may be involved in pollen germination.

The heterooctameric vesicle-tethering complex exocyst is important for plant development, growth, and immunity. Multiple paralogs exist for most subunits of this complex; especially the membrane-interacting subunit EXO70 underwent extensive amplification in land plants, suggesting functional specialization. Despite this specialization, most Arabidopsis exo70 mutants are viable and free of developmental defects, probably as a consequence of redundancy among isoforms. Our in silico data-mining and modeling analysis, corroborated by transcriptomic experiments, pinpointed several EXO70 paralogs to be involved in plant biotic interactions. We therefore tested corresponding single and selected double mutant combinations (for paralogs EXO70A1, B1, B2, H1, E1, and F1) in their two biologically distinct responses to Pseudomonas syringae, root hair growth stimulation and general plant susceptibility. A shift in defense responses toward either increased or decreased sensitivity was found in several double mutants compared to wild type plants or corresponding single mutants, strongly indicating both additive and compensatory effects of exo70 mutations. In addition, our experiments confirm the lipid-binding capacity of selected EXO70s, however, without the clear relatedness to predicted C-terminal lipid-binding motifs. Our analysis uncovers that there is less of functional redundancy among isoforms than we could suppose from whole sequence phylogeny and that even paralogs with overlapping expression pattern and similar membrane-binding capacity appear to have exclusive roles in plant development and biotic interactions.

The regulation of developmental pathways in cultured microspores of tobacco ( Nicotiana tabacum L) and snapdragon ( Antirrhinum majus L) by medium pH is described for the first time. Unicellular tobacco and snapdragon microspores developed into normal, fertile pollen when cultured in media T1 and AT3 at pH 7.0 and 25°C for 6 and 8 days, respectively. First, pollen mitosis was asymmetric and mature pollen grains were filled with starch granules and germinated upon transfer to a germination medium. However, when tobacco and snapdragon microspores were cultured in media T1 and AT3, respectively, at pH 8.0?8.5 for 4?6 days at 25 °C, the frequency of symmetric division increased significantly with the formation two nuclei of equal size, and the gametophytic pathway was blocked, as seen by the lack of starch accumulation and the inhibition of pollen germination. The transfer of these microspores to embryogenesis medium AT3 at pH 6.5 resulted in the formation of multicellular structures in both species and, in tobacco, in the formation of embryos and plants. In order to understand the possible mechanisms of the action of high pH, sucrose metabolism was analysed in isolated microspores of tobacco cultured at various pH values. Invertase (EC 3.2.1.26) activity in microspores was maximal at pH 5.0 and strongly decreased at higher pH, leading to a slow-down of sucrose cleavage. At the same time the incorporation of 14C-labelled sucrose from the medium into microspores was drastically reduced at high pH. These data suggest that isolated microspores are not able to metabolise carbohydrates at high pH and thus undergo starvation stress, which was shown earlier to block the gametophytic pathway and trigger sporophytic development. [ABSTRACT FROM AUTHOR]