Effects of irradiance, temperature, nutrients, and pCO2 on the growth and biochemical composition of cultivated Ulva fenestrata

Ulva fenestrata is an economically and ecologically important green algal species with a large potential in seaweed aquaculture due to its high productivity, wide environmental tolerance, as well as interesting functional and nutritional properties. Here, we performed a series of manipulative cultivation experiments in order to investigate the effects of irradiance (50, 100, and 160\ua0μmol photons m−2\ua0s−1), temperature (13 and 18\ua0\ub0C), nitrate (< 5, 150, and 500\ua0μM), phosphate (< 1 and 50\ua0μM), and pCO2 (200, 400, and 2500\ua0ppm) on the relative growth rate and biochemical composition (fatty acid, protein, phenolic, ash, and biochar content) in indoor tank cultivation of Swedish U. fenestrata. High irradiance and low temperature were optimal for the growth of this northern hemisphere U. fenestrata strain, but addition of nutrients or changes in pCO2 levels were not necessary to increase growth. Low irradiance resulted in the highest fatty acid, protein, and phenolic content, while low temperature had a negative effect on the fatty acid content but a positive effect on the protein content. Addition of nutrients (especially nitrate) increased the fatty acid, protein, and phenolic content. High nitrate levels decreased the total ash content of the seaweeds. The char content of the seaweeds did not change in response to any of the manipulated factors, and the only significant effect of changes in pCO2 was a negative relationship with phenolic content. We conclude that the optimal cultivation conditions for Swedish U. fenestrata are dependent on the desired biomass traits (biomass yield or biochemical composition)

Cultivation conditions affect the monosaccharide composition in Ulva fenestrata

In recent years, the interest in using seaweed for the sustainable production of commodities has been increasing as seaweeds contain many potentially worthwhile compounds. Thus, the extraction and refining processes of interesting compounds from seaweeds is a hot research topic but has been found to have problems with profitability for novel applications. To increase the economic potential of refining seaweed biomass, the content of the compounds of interest should be maximized, which can potentially be achieved through optimization of cultivation conditions. In this study, we studied how the monosaccharide composition of the green seaweed species Ulva fenestrata is influenced by the abiotic factors; irradiance, temperature, nitrate, phosphate, and pCO2. It was evident that lower nitrate concentration and cultivation at elevated temperature increased monosaccharide contents. A 70% increase in iduronic acid and a 26% increase in rhamnose content were seen under elevated irradiance and temperature conditions, though the absolute differences in monosaccharide concentration were small. Irradiance and nitrate impacted the ratio between iduronic and rhamnose, which is an indicator of the ulvan structure. These results could potentially be utilized to coax the ulvan towards specific bioactivities, and thus have a considerable impact on a potential biorefinery centered around Ulva.\ua0\ua9 2020, The Author(s)

Extensive Adaptive Changes Occur in the Transcriptome of Streptococcus agalactiae (Group B Streptococcus) in Response to Incubation with Human Blood

To enhance understanding of how Streptococcus agalactiae (group B streptococcus, GBS) adapts during invasive infection, we performed a whole-genome transcriptome analysis after incubation with whole human blood. Global changes occurred in the GBS transcriptome rapidly in response to blood contact following shift from growth in a rich laboratory medium. Most (83%) of the significantly altered transcripts were down-regulated after 30 minutes of incubation in blood, and all functional categories of genes were abundantly represented. We observed complex dynamic changes in the expression of transcriptional regulators and stress response genes that allow GBS to rapidly adapt to blood. The transcripts of relatively few proven virulence genes were up-regulated during the first 90 minutes. However, a key discovery was that genes encoding proteins involved in interaction with the host coagulation/fibrinolysis system and bacterial-host interactions were rapidly up-regulated. Extensive transcript changes also occurred for genes involved in carbohydrate metabolism, including multi-functional proteins and regulators putatively involved in pathogenesis. Finally, we discovered that an incubation temperature closer to that occurring in patients with severe infection and high fever (40°C) induced additional differences in the GBS transcriptome relative to normal body temperature (37°C). Taken together, the data provide extensive new information about transcriptional adaptation of GBS exposed to human blood, a crucial step during GBS pathogenesis in invasive diseases, and identify many new leads for molecular pathogenesis research

The Interaction of Canine Plasminogen with Streptococcus pyogenes Enolase: They Bind to One Another but What Is the Nature of the Structures Involved?

For years it has been clear that plasminogen from different sources and enolase from different sources interact strongly. What is less clear is the nature of the structures required for them to interact. This work examines the interaction between canine plasminogen (dPgn) and Streptococcus pyogenes enolase (Str enolase) using analytical ultracentrifugation (AUC), surface plasmon resonance (SPR), fluorescence polarization, dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and simple pull-down reactions. Overall, our data indicate that a non-native structure of the octameric Str enolase (monomers or multimers) is an important determinant of its surface-mediated interaction with host plasminogen. Interestingly, a non-native structure of plasminogen is capable of interacting with native enolase. As far as we can tell, the native structures resist forming stable mixed complexes

Porphyromonas gingivalis initiates coagulation and secretes polyphosphates : A mechanism for sustaining chronic inflammation?

BACKGROUND: Periodontitis is a chronic inflammation resulting in destruction of tooth-supporting bone. Chronic inflammation is characterized by extravascular fibrin deposition. Fibrin is central to destruction of bone; monocytes bind to fibrin and form osteoclasts, thus providing a link between coagulation and the tissue destructive processes in periodontitis. The oral microbiome is essential to oral health. However, local ecological changes, such as increased biofilm formation, result in a dysbiotic microbiome characterized by an increase of protease-producing species e.g. Porphyromonas gingivalis. Proteases initiate inflammation and may cleave coagulation factors. Polyphosphates (polyP) may also provide bacteria with procoagulant properties similar to platelet-released polyP. P. gingivalis has also been found in remote locations related to vascular pathology and Alzheimer's disease. OBJECTIVES: The aim of this study was to investigate procoagulant activity of ten different species of oral bacteria present in oral health and disease as well as presence of polyP and fibrin formation in planktonic and biofilm bacteria. METHODS: Oral bacteria were studied for protease production and procoagulant activity. The presence of polyP and formation of fibrin was observed using confocal microscopy. RESULTS: P. gingivalis showed strong protease activity and was the only species exerting procoagulant activity. Confocal microscopy showed polyP intracellularly in planktonic bacteria and extracellularly after biofilm formation. Fibrin formation emanated from planktonic bacteria and from both bacteria and polyP in biofilm cultures. CONCLUSIONS: The procoagulant activity of P. gingivalis could explain its role in chronic inflammation, locally in oral tissues as well as in remote locations

Porphyromonas gingivalis initiates coagulation and secretes polyphosphates : A mechanism for sustaining chronic inflammation?

BACKGROUND: Periodontitis is a chronic inflammation resulting in destruction of tooth-supporting bone. Chronic inflammation is characterized by extravascular fibrin deposition. Fibrin is central to destruction of bone; monocytes bind to fibrin and form osteoclasts, thus providing a link between coagulation and the tissue destructive processes in periodontitis. The oral microbiome is essential to oral health. However, local ecological changes, such as increased biofilm formation, result in a dysbiotic microbiome characterized by an increase of protease-producing species e.g. Porphyromonas gingivalis. Proteases initiate inflammation and may cleave coagulation factors. Polyphosphates (polyP) may also provide bacteria with procoagulant properties similar to platelet-released polyP. P. gingivalis has also been found in remote locations related to vascular pathology and Alzheimer's disease. OBJECTIVES: The aim of this study was to investigate procoagulant activity of ten different species of oral bacteria present in oral health and disease as well as presence of polyP and fibrin formation in planktonic and biofilm bacteria. METHODS: Oral bacteria were studied for protease production and procoagulant activity. The presence of polyP and formation of fibrin was observed using confocal microscopy. RESULTS: P. gingivalis showed strong protease activity and was the only species exerting procoagulant activity. Confocal microscopy showed polyP intracellularly in planktonic bacteria and extracellularly after biofilm formation. Fibrin formation emanated from planktonic bacteria and from both bacteria and polyP in biofilm cultures. CONCLUSIONS: The procoagulant activity of P. gingivalis could explain its role in chronic inflammation, locally in oral tissues as well as in remote locations

Reduced Gingival Fluid Flow : a Peripheral Marker of the Pharmacological Effect of Roquinimex

OBJECTIVE: Roquinimex is a drug with effects on inflammation and tumors. The pharmacological effect is not fully understood, and the molecular mechanism most characterized in vitro is an increase of plasminogen activator inhibitor type 2 (PAI-2) in human peripheral blood monocytes. The aims were to investigate peripheral pharmacological effects of roquinimex on peripheral blood monocytes and dog gingival fluid (GCF). DESIGN: Six dogs were used in a cross-over study. The amount of GCF was determined with a Periotron. The PAI-2 concentration in GCF was determined with ELISA. Monocytes were isolated from peripheral blood. RESULTS: Dogs treated with the drug had significantly lower GCF flow values and the PAI-2 concentration in GCF was higher, but no effect was seen on peripheral monocytes. CONCLUSION: Roquinimex treatment led to a consistently decreased flow rate of GCF and a higher local concentration of PAI-2 in GCF