Clinanthus microstephium,an Amaryllidaceae Species with Cholinesterase Inhibitor Alkaloids: Structure−Activity Analysis of Haemanthamine Skeleton Derivatives

Plants of the Amaryllidaceae family are well‐known (not only) for their ornamental value but also for the alkaloids that they produce. In this report, the first phytochemical study of Clinanthus genus was carried out. The chemical composition of alkaloid fractions from Clinanthus microstephium was analyzed by GC/MS and NMR. Seven known compounds belonging to three structural types of Amaryllidaceae alkaloids were identified. An epimeric mixture of a haemanthamine‐type compound (6‐hydroxymaritidine) was tested as an inhibitor against acetyl‐ and butyrylcholinesterase enzymes (AChE and BChE, respectively), two enzymes relevant in the treatment of Alzheimer's disease, with good results. Structure–activity relationships through molecular docking studies with this alkaloid and other structurally related compounds were discussed.     

Cyclooxygenase-2 deficiency leads to intestinal barrier dysfunction and increased mortality during polymicrobial sepsis

Sepsis remains the leading cause of death in critically ill patients, despite modern advances in critical care. Intestinal barrier dysfunction may lead to secondary bacterial translocation and the development of the multiple organ dysfunction syndrome during sepsis. Cyclooxygenase (COX)-2 is highly upregulated in the intestine during sepsis, and we hypothesized that it may be critical in the maintenance of intestinal epithelial barrier function during peritonitis-induced polymicrobial sepsis. COX-2(-/-) and COX-2(+/+) BALB/c mice underwent cecal ligation and puncture (CLP) or sham surgery. Mice chimeric for COX-2 were derived by bone marrow transplantation and underwent CLP. C2BBe1 cells, an intestinal epithelial cell line, were treated with the COX-2 inhibitor NS-398, PGD(2), or vehicle and stimulated with cytokines. COX-2(-/-) mice developed exaggerated bacteremia and increased mortality compared with COX-2(+/+) mice following CLP. Mice chimeric for COX-2 exhibited the recipient phenotype, suggesting that epithelial COX-2 expression in the ileum attenuates bacteremia following CLP. Absence of COX-2 significantly increased epithelial permeability of the ileum and reduced expression of the tight junction proteins zonula occludens-1, occludin, and claudin-1 in the ileum following CLP. Furthermore, PGD(2) attenuated cytokine-induced hyperpermeability and zonula occludens-1 downregulation in NS-398-treated C2BBe1 cells. Our findings reveal that absence of COX-2 is associated with enhanced intestinal epithelial permeability and leads to exaggerated bacterial translocation and increased mortality during peritonitis-induced sepsis. Taken together, our results suggest that epithelial expression of COX-2 in the ileum is a critical modulator of tight junction protein expression and intestinal barrier function during sepsis.     

Different bioreactor configurations for the decolourisation of the azo dye reactive black 5 by Geotrichum sp. CCMI 1019

Decolourisation of the azo dye Reactive Black 5 by Geotrichum sp. CCMI 1019 was studied using stirred tank reactors (STR) and two types of bubble columns (porous plate (PP) bubble column and aeration tube (AT) bubble column). For the bubble columns, the k_La increased with the gas fractional hold-up (ε_G) and the aeration rate. A linear relationship between ε_G and superficial gas velocity was obtained for all reactors. At same aeration rates, the PP bubble columns showed higher k_La and hold-up values than the AT bubble column. In the STRs, large and dense aggregates were formed which adhered to surfaces whereas bubble columns gave smaller and less compact pellets.

Manganese peroxidase and laccase were detected in the extracellular media in all reactors. However, laccase was only detected after the onset of decolourisation, suggesting that additional enzymes may be involved. Mn peroxidase activity was detected (about 46 U/ml) in both the STRs and AT bubble columns but higher values (110 U/ml) were obtained with the PP bubble columns.

Out of the three reactor systems studied, the AT bubble columns gave the most favourable results for Reactive Black 5 decolourisation. Rapid and complete colour removal was obtained throughout the visible spectrum. Bubble columns are simple in design as well as operation and may be useful for the bioremediation of textile wastewater.     

Flocculation in ale brewing strains of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>: re-evaluation of the role of cell surface charge and hydrophobicity

Flocculation is an eco-friendly process of cell separation, which has been traditionally exploited by the brewing industry. Cell surface charge (CSC), cell surface hydrophobicity (CSH) and the presence of active flocculins, during the growth of two (NCYC 1195 and NCYC 1214) ale brewing flocculent strains, belonging to the NewFlo phenotype, were examined. Ale strains, in exponential phase of growth, were not flocculent and did not present active flocculent lectins on the cell surface; in contrast, the same strains, in stationary phase of growth, were highly flocculent (>98%) and presented a hydrophobicity of approximately three to seven times higher than in exponential phase. No relationship between growth phase, flocculation and CSC was observed. For comparative purposes, a constitutively flocculent strain (S646-1B) and its isogenic non-flocculent strain (S646-8D) were also used. The treatment of ale brewing and S646-1B strains with pronase E originated a loss of flocculation and a strong reduction of CSH; S646-1B pronase E-treated cells displayed a similar CSH as the non-treated S646-8D cells. The treatment of the S646-8D strain with protease did not reduce CSH. In conclusion, the increase of CSH observed at the onset of flocculation of ale strains is a consequence of the presence of flocculins on the yeast cell surface and not the cause of yeast flocculation. CSH and CSC play a minor role in the auto-aggregation of the ale strains since the degree of flocculation is defined, primarily, by the presence of active flocculins on the yeast cell wall.     

Isolation of high-lipid content strains of the marine microalga <Emphasis Type="Italic">Tetraselmis suecica</Emphasis> for biodiesel production by flow cytometry and single-cell sorting

Biodiesel from algae is considered an alternative for a third generation of biofuels. However, most microalgae are not lipogenic during fast growth periods, but high-lipid content occurs at resting stages. Microalgae biomass production for biodiesel needs continuous high volumetric and aerial yields and large amount of neutral lipid in the biomass. These requirements are similar to demanding a marathon runner to be obese. We show that by using cell sorting capabilities of flow cytometers, in combination with the lipid-soluble fluorescent dye Nile Red, we can isolate and select cells with a high and stable lipid content. In our study, we were able to select the equivalent of a stable “fat marathon runner” through three sorting events obtained from wild populations of Tetraselmis suecica.     

Effector and memory CD8+ T cells can be generated in response to alloantigen independently of CD4+ T cell help

There is now considerable evidence suggesting that CD8(+) T cells are able to generate effector but not functional memory T cells following pathogenic infections in the absence of CD4(+) T cells. We show that following transplantation of allogeneic skin, in the absence of CD4(+) T cells, CD8(+) T cells become activated, proliferate, and expand exclusively in the draining lymph nodes and are able to infiltrate and reject skin allografts. CD44(+)CD8(+) T cells isolated 100 days after transplantation rapidly produce IFN-gamma following restimulation with alloantigen in vitro. In vivo CD44(+)CD8(+) T cells rejected donor-type skin allografts more rapidly than naive CD8(+) T cells demonstrating the ability of these putative memory T cells to mount an effective recall response in vivo. These data form the first direct demonstration that CD8(+) T cells are able to generate memory as well as effector cells in response to alloantigen during rejection in the complete absence of CD4(+) T cells. These data have important implications for the design of therapies to combat rejection and serve to reinforce the view that CD8(+) T cell responses to allografts require manipulation in addition to CD4(+) T cell responses to completely prevent the rejection of foreign organ transplants.     

Commensal Pseudomonas protect Arabidopsis thaliana from a coexisting pathogen via multiple lineage-dependent mechanisms

Plants are protected from pathogens not only by their own immunity but often also by colonizing commensal microbes. In Arabidopsis thaliana, a group of cryptically pathogenic Pseudomonas strains often dominates local populations. This group coexists in nature with commensal Pseudomonas strains that can blunt the deleterious effects of the pathogens in the laboratory. We have investigated the interaction between one of the Pseudomonas pathogens and 99 naturally co-occurring commensals, finding plant protection to be common among non-pathogenic Pseudomonas. While protective ability is enriched in one specific lineage, there is also a substantial variation for this trait among isolates of this lineage. These functional differences do not align with core-genome phylogenies, suggesting repeated gene inactivation or loss as causal. Using genome-wide association, we discovered that different bacterial genes are linked to plant protection in each lineage. We validated a protective role of several lineage-specific genes by gene inactivation, highlighting iron acquisition and biofilm formation as prominent mechanisms of plant protection in this Pseudomonas lineage. Collectively, our work illustrates the importance of functional redundancy in plant protective traits across an important group of commensal bacteria.Subject terms: Microbial ecology, Plant ecology