Potential of fructans as natural cryoprotectant agents in plant cryopreservation: concept validation on Arabidopsis thaliana L.

BACKGROUND: Today, synthetic chemicals are used in vitrification solutions for cryopreservation studies to mimic natural cryoprotectants that supply tolerance to organisms in nature against freezing stress. In the case of plants, PVS2, containing glycerol, dimethyl sulfoxide (Me2SO), ethylene glycol and sucrose, is considered as the golden standard for successful cryopreservation. However, Me2SO can generally cause toxicity to certain plant cells, adversely affecting viability after freezing and/or thawing. Hence, the replacement (or substantial reduction) of Me2SO by cheap, non-toxic and natural cryoprotectants became a matter of high priority to vitrification solutions or reducing their content gained escalating importance for the cryopreservation of plants. Fructans, sucrose derivatives mainly consisting of fructose residues, are candidate cryoprotectants. OBJECTIVE: Inspired by their protective role in nature, we here explored, for the first time, the potential of an array of 8 structurally different fructans as cryoprotectants in plant cryopreservation. MATERIALS AND METHODS: Arabidopsis thaliana L. seedlings were used as a model system with a one-step vitrification method. PVS2 solutions with different Me2SO and fructan contents were evaluated. RESULTS: It was found that branched low DP graminan, extracted from milky stage wheat kernels, led to the highest recovery (85%) among tested fructans with 12.5% Me2SO after cryopreservation, which was remarkably close to the viability (90%) observed with the original PVS2 containing 15% Me2SO. Moreover, its protective efficacy could be further optimized by addition of vitamin C acting as an antioxidant. CONCLUSION: Such novel formulations offer great perspectives for cryopreservation of various crop species. Doi.org/10.54680/fr24410110512.

Fructanogenic traits in halotolerant Bacillus licheniformis OK12 and their predicted functional significance.

AIMS: Isolating a novel bacterial source of fructan from a saltern and analysis of its genome to better understand the possible roles of fructans in hypersaline environments. METHODS AND RESULTS: Bacteria were isolated from crude salt samples originating from Çamalti Saltern in Western Turkey and screened for fructanogenic traits in high-salt and sucrose-rich selective medium. Exopolysaccharide accumulated in the presence of sucrose by isolate OK12 was purified and chemically characterized via HPLC, FT-IR and NMR, which revealed that it was a levan-type fructan (ß-2,6 linked homopolymer of fructose). The isolate was taxonomically classified as Bacillus licheniformis OK12 through 16S rRNA gene and whole-genome sequencing methods. Strain OK12 harbours one levansucrase and two different levanase genes, which altogether were predicted to significantly contribute to intracellular glucose and fructose pools. The isolate could withstand 15% NaCl, and thus classified as a halotolerant. CONCLUSIONS: Fructanogenic traits in halotolerant B. licheniformis OK12 are significant due to predicted influx of glucose and fructose as a result of levan biosynthesis and levan hydrolysis, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Fructans from the residents of hypersaline habitats are underexplored compounds and are expected to demonstrate physicochemical properties different from their non-halophilic counterparts. Revealing fructanogenic traits in the genome of a halotolerant bacterium brings up a new perspective in physiological roles of fructans.

Brevibacillus themoruber: a promising microbial cell factory for exopolysaccharide production.

AIMS: This study aims to identify a high level exopolysaccharide (EPS) producer thermophile that in turn could be used as a model organism to study the biological mechanisms and whole genome organization of EPS-producing thermophilic bacteria. METHODS AND RESULTS: Thermophilic isolates were screened, and then growth and EPS production of the best producer Brevibacillus thermoruber strain 423 were investigated under different carbon and nitrogen sources, temperature, pH and agitation rates. Rheological characterization revealed that the EPS behaved like a typical Newtonian fluid and viscosity of the EPS solution increased with increasing Ca(2+) ion concentration. Chemical characterization by TLC, GC-MS, FT-IR and NMR suggested a heteropolymer structure with glucose as major monomer unit. High biocompatibility of pure EPS fractions suggested their potential use in biomedical applications. CONCLUSIONS: This study reports on the comprehensive description of microbial production conditions as well as chemical, rheological and biological characterization of the EPS produced by B. thermoruber strain 423. The bioreactor cultures were found to reach two times higher yields and three times higher productivities when compared with literature. SIGNIFICANCE AND IMPACT OF THE STUDY: Brevibacillus thermoruber strain 423 combined the advantages of its nonpathogenicity with the advantages of fast productivity and hence proved to be a very promising model organism and cell factory for microbial EPS production.

High BNP level as risk factor for acute kidney injury and predictor of all-cause mortality in STEMI patients.

OBJECTIVES: The aim of this study was to evaluate the predictive value of brain natriuretic peptide (BNP) in the development of acute kidney injury (AKI) and 6-month all-cause mortality after primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) in a modest-risk population. BACKGROUND: The prognostic value of BNP has been well documented in patients with acute coronary syndrome. However, its value in development of AKI and 6-month all-cause mortality in patients with STEMI undergoing primary PCI remains unclear. METHODS: We prospectively enrolled 424 consecutive STEMI patients (mean age 53.6 ± 12.1 years) undergoing primary PCI. The population was divided into two groups: a high (n = 110) and a low (n = 314) admission BNP group according to the cut-off value (> 88.7 pg/ml) determined by ROC analysis to have the best predictive accuracy for 6-month all-cause mortality. The clinical characteristics as well as the in-hospital and 6-month outcomes of patients undergoing primary PCI were analyzed. RESULTS: Cox multivariate analysis showed that a high-admission BNP value (> 88.7 pg/ml) was an independent predictor of AKI development (odds ratio, 1.002; 95 % confidence interval, 1.000­1.003; p = 0.02) and 6-month all-cause mortality (odds ratio, 1.003; 95 % confidence interval; 1.001­1.004; p = 0.004). CONCLUSION: These results suggest that a high-admission BNP level is associated with an increased risk of AKI development and 6-month all-cause mortality in patients with STEMI undergoing primary PCI.

Effect of bioprocess conditions on growth and alkaline protease production by halotolerant Bacillus licheniformis BA17.

The effect of bioprocess conditions (pH and temperature) on the growth and alkaline protease production of halotolerant Bacillus licheniformis BA17 bioreactor cultures have been systematically analyzed using response surface methodology in order to assess the importance of these generally disregarded parameters. Two models were proposed differing by the choice of response variable. Under optimized bioprocess conditions, whole alkaline protease activity was about 3 fold higher than the activities obtained in the preliminary studies. Results of this study not only highlight the importance of pH and temperature for further engineering purposes but also serve as basis for understanding the true mechanism lying under the relation between these process parameters and growth and whole alkaline protease production.

Effects of verapamil and adenosine in an adjunct to tirofiban on resolution and prognosis of noreflow phenomenon in patients with acute myocardial infarction.

AIM: We aimed to investigate the effects of verapamil and adenosine in an adjunct to intravenous tirofiban on management and prognosis of no-reflow phenomenon during primary percutaneous coronary intervention (PPCI) and to compare their efficacies on reversing of no-reflow phenomenon and short and midterm survival. METHODS: We included 46 patients with acute ST-segment elevation myocardial infarction (STEMI) and occurrence of no-reflow phenomenon after PPCI. All patients received intravenous tirofiban and then randomized into one of the following 3 groups: intracoronary adenosine (N.=16), intracoronary verapamil (N.=15) or placebo (N.=15). RESULTS: Intracoronary verapamil therapy had significant effect in restoring impaired coronary blood flow by decreasing thrombolysis in myocardial infarction (TIMI) frame count from 73±44 to 52±48 (P=0.024). However, adenosine and serum physiologic administration were not found to be so effective in decreasing TIMI frame count (from 81±35 to 71±46, P=0.084; from 74±32 to 71±37, P=0.612, respectively). In-hospital and 6-month survival rates were similar among groups. CONCLUSION: In conclusion, intracoronary verapamil restored the impaired coronary blood flow more effectively than adenosine or placebo. However, none of them has changed the clinical course in the first 6 months.

Unbiased estimation of the calcaneus volume using the Cavalieri principle on computed tomography images.

The size and shape of tarsal bones are especially relevant when considering some orthopedic diseases such as clubfoot. For this reason, the measurements of the tarsal bones have been the subject of many studies, none of which has used stereological methods to estimate the volume. In the present stereological study, we estimated the volume of calcaneal bone of normal feet and dry bones. We used a combination of the Cavalieri principle and computer tomographic scans taken from eight males and nine dry calcanei to estimate the volumes of calcaneal bones. The mean volume of dry calcaneal bones was estimated, producing mean results using the point-counting method and Archimedes principle being 49.11+/-10.7 or 48.22+/-11.92 cm(3), respectively. A positive correlation was found between anthropometric measurements and the volume of calcaneal bones. The findings of the present study using the stereological methods could provide data for the evaluation of normal and pathological volumes of calcaneal bones.