Fatty acids, membrane permeability, and sugars of stored potato tubers

The relationships of potato (Solanum tuberosum L.) tuber membrane permeability and membrane lipid composition to sugar accumulation were examined. Tubers from four potato cultivars were stored for 40 weeks at 3°C and 9°C. Rates of tuber membrane electrolyte leakage, total fatty acid composition, free fatty acid composition, and sugar content were measured throughout the storage period. Storage of tubers at 3°C caused dramatic increases in total fatty acid unsaturation, membrane permeability, and sugar content compared to tubers stored at 9°C. Cultivars with higher levels of fatty acid unsaturation had lower rates of membrane electrolyte leakage and lower sugar contents. We propose that high initial levels or high induced levels of membrane lipid unsaturation mitigate increases in tuber membrane permeability during storage, thus positively influencing the processing quality of stored potato tubers.     

Salt hardiness and dye reduction by potato tissue and mitochondrial fractions as influenced by previous storage of the tubers

Oxygen uptake and tetrazolium reduction occurred at higher rates in discs from potato tubers (Solanum tuberosum L.) stored at 0° than in discs from tubers stored at 12.8°. Tetrazolium reduction was at a higher rate in mitochondrial fractions from tubers stored at 0° than in mitochondrial fractions from tubers stored at 12.8°. These physiological activities were more resistant to hypertonic KCl treatments in tissue and mitochondrial fractions from tubers stored at 0° than in tissue and mitochondrial fractions from tubers stored at 12.8°. Inhibition of O₂ uptake and tetrazolium reduction progressively increased with increasing concentrations of KCl for tissue and mitochondrial fractions from tubers stored at 0 and 12.8°, but inhibition was more severe and occurred at lower concentrations of KCl for the material from tubers stored at 12.8°. Tissue from tubers stored at 0° was at the same time more sensitive to hypotonic solutions and more resistant to hypertonic solutions than corresponding tissue from tubers stored at 12.8°. Adaptive changes brought on in the tubers by the stress of cold storage were demonstrated in the discs and mitochondrial fractions prepared from cold-stored tubers.     

Translucent Tissue Defects in Solanum tuberosum L: I. Alterations in Amyloplast Membrane Integrity, Enzyme Activities, Sugars, and Starch Content

Kennebec (cv) potatoes randomly developed translucent areas in their centrally located pith-parenchymal cells during storage. These defective areas were characterized as having reduced starch concentration and increased levels of free sugars (i. e. sucrose and glucose) and inorganic phosphate. Electron micrographs of potato tubers stored at 10° ± 1°C for 8 months indicated that the amyloplast membrane was still intact and continuous around starch granules in both normal and prematurely sweetened tissue. The total activities of phosphorylase and sucrose-6-P synthase were elevated 5.4- and 3.8-fold, respectively, in the defective tissue compared to healthy nonsweetened tubers while there were no significant differences in the levels of sucrose synthase, UDPglucose pyrophosphorylase, invertase, or α-amylase. Total and specific activities of acid phosphatase were only slightly elevated in translucent tissue but their increase was significant (P < 0.05, t test) over that seen in healthy tubers. The premature sweetening in storage may have been indirectly triggered by moisture and heat stress experienced during development. Translucency eventually led to physical deterioration of the tissue.     

Potential Role of Pyrophosphate:Fructose 6-Phosphate Phosphotransferase in Carbohydrate Metabolism of Cold Stored Tubers of Solanum tuberosum cv Bintje

To gain a better understanding of the mechanism of cold induced sweetening, sugar accumulation in potato, Solanum tuberosum cv Bintje, was compared to the maximum activity of inorganic pyrophosphate (PPi):fructose 6-phosphate 1-phosphotransferase (EC 2.7.1.90) and the concentration of two regulatory metabolites. Mature tubers accumulated reducing sugars and sucrose at an almost linear rate of 13.4 and 5.2 micromole per day per gram dry weight at 2°C and 4.5 and 1.3 micromole per day per gram dry weight, respectively, at 4°C. During storage at 8°C sugar accumulation was nil. Sugar accumulation was preceded by a lag phase of about 4 days. The accumulation of reducing sugars persisted for at least 4 weeks, whereas sucrose accumulation declined after 2 weeks of storage. The ratio of glucose:fructose changed concomitantly with sugar increase from 65:35 to equimolarity. The maximum activity of PPi:fructose 6-phosphate 1-phosphotransferase was 2.51 and 2.25 units per gram dry weight during storage at 2 and 8°C, respectively. The temperature coefficient of this enzyme from potatoes kept at 2 or 8°C was 2.12 and 2.48, respectively. The endogenous concentration of fructose 2,6-biphosphate increased from 0.15 to 1 nanomole per gram dry weight during storage at 2 and 4°C but remained the same throughout storage at 8°C. After exposure to 2°C an initial increase in the concentration of PPi was observed from 4.0 to 5.6 nanomoles per gram dry weight. Pyrophosphate concentration did not change during storage at 4°C but decreased slightly at 8°C. All observed changes became annulled after transfer of cold stored tubers to 18°C. These data strongly indicate that PPi:fructose 6-phosphate 1-phosphotransferase can be fully operational in cold stored potato tubers and the lack of increase in PPi concentration supports the functioning of this enzyme during sugar accumulation.     

Effects of Low-Temperature Acclimation and Oxygen Stress on Tocopheron Production in Euglena gracilis Z

The effects of low-temperature acclimation and oxygen stress on tocopheron production were examined in the unicellular phytoflagellate Euglena gracilis Z. Cells were cultured photoheterotrophically at 27.5 ± 1°C with 5% carbon dioxide-95% air and 740 microeinsteins m⁻² s⁻¹ (photosynthetically active radiation) and served as controls. Low-temperature acclimation (12.5 ± 1°C) and high-oxygen stress (5% carbon dioxide-95% oxygen) were individually examined in the mass culturing of the algae. Chromatographic analyses demonstrated a six-to sevenfold enhancement of α-tocopherol production in temperature-stressed cells, along with a concomitant decline in the levels of α-tocotrienol and the absence of other tocopherol homologs. Oxygen-stressed cultures demonstrated the presence of high levels of α-tocopherylquinone; α-tocopheron and its homologs and precursors were absent or declined markedly. These findings are discussed in terms of the feasibility of microbial production of natural tocopherols. In addition, these results lend themselves to speculation regarding the biological role(s) of tocopherols as antioxidants and free radical scavengers in reducing photo-induced oxidative damage or lipid peroxidation toxicities or both in photosynthetically active E. gracilis Z.     

Alleviation of low temperature sweetening in potato by expressing Arabidopsis pyruvate decarboxylase gene and stress-inducible rd29A: A preliminary study

The acceptability of potatoes for processing chips and French fries is largely dependent on the color of the finished product. Most potato cultivars and varieties stored at temperatures below 9–10 °C are subjected to low temperature sweetening (LTS) which result in the production of bitter-tasting, dark colored chips and French fries which are unacceptable to consumers. However, storing tubers at low temperatures (i.e., <10 °C) has many advantages such as lowered weight loss during storage, natural control of sprouting, and reduction/elimination of chemical sprout inhibitors. Our earlier research results on LTS suggested a role for pyruvate decarboxylase (PDC) in LTS-tolerance. In the present study, the role of PDC was examined whereby the potato variety Snowden was transformed with Arabidopsis cold-inducible pyruvate decarboxylase gene 1 (AtPDC1) under the control of promoter rd29A. Two transgenic plants were selected and storage studies were conducted on tubers harvested from one of the transgenic lines grown under green house conditions. Transgenic tubers showed higher Agtron chip color score indicating lighter chip and lower reducing sugar and sucrose concentrations compared to the untransformed tubers during the storage periods studied at 12 °C and 5 °C. These results suggest that overexpression of pyruvate decarboxylase gene resulted in low temperature sweetening tolerance in the transgenic Snowden.     

Oxylipin profile and antioxidant status of potato tubers during extended storage at room temperature

Potato tubers (cv. Bintje) (Solanum tuberosum L.) were stored under extreme conditions at 20 °C for 350 days without sprout inhibitors in order to assess whether aging- and/or senescence-related processes occurred. Under these extreme storage conditions, multiple sprouting followed by the formation of daughter tubers occurs. At the same time, an increase in respiration intensity, as evidenced by cytochrome c oxidase activity (E.C. 1.9.3.1), is observed, leading to a potential increase in reactive oxygen species (ROS) production. As polyunsaturated fatty acids are priority targets of oxidative attacks, the damage to lipids was assessed by oxylipin profiling in both free and esterified forms. Oxylipin profiling showed a predominance of linoleic acid-derived oxylipins and of 9-hydroxy and 9-hydroperoxy fatty acids in both free and esterified forms. No significant accumulation of individual oxylipin was observed 350 days after harvest. To further understand the absence of lipid breakdown products accumulation, the main enzymatic and non-enzymatic antioxidants were assessed. Antioxidant enzyme activities [superoxide dismutase (E.C. 1.15.1.1), catalase (E.C. 1.11.1.6.), ascorbate peroxidase (E.C. 1.11.1.11)] were enhanced during the advanced phase of aging. The main non-enzymatic antioxidant compound, ascorbate, decreased markedly in the early stages of storage, followed by a slower decline. Total radical scavenging activity was also maintained at the end of the storage period. Our results indicate that the enhanced aging process occurring during storage at room temperature does not seem to be associated with the changes classically encountered during leaf senescence or seed aging and that the observed degenerative processes do not surpass the protective potential of the tubers.     

Deleterious consequences of antioxidant supplementation on lifespan in a wild-derived mammal

While oxidative damage owing to reactive oxygen species (ROS) often increases with advancing age and is associated with many age-related diseases, its causative role in ageing is controversial. In particular, studies that have attempted to modulate ROS-induced damage, either upwards or downwards, using antioxidant or genetic approaches, generally do not show a predictable effect on lifespan. Here, we investigated whether dietary supplementation with either vitamin E (α-tocopherol) or vitamin C (ascorbic acid) affected oxidative damage and lifespan in short-tailed field voles, Microtus agrestis. We predicted that antioxidant supplementation would reduce ROS-induced oxidative damage and increase lifespan relative to unsupplemented controls. Antioxidant supplementation for nine months reduced hepatic lipid peroxidation, but DNA oxidative damage to hepatocytes and lymphocytes was unaffected. Surprisingly, antioxidant supplementation significantly shortened lifespan in voles maintained under both cold (7 ± 2°C) and warm (22 ± 2°C) conditions. These data further question the predictions of free-radical theory of ageing and critically, given our previous research in mice, indicate that similar levels of antioxidants can induce widely different interspecific effects on lifespan.     

Oxidative stress,growth factor production and budding in potato tubers during cold storage

In order to verify the role played by oxidation in the budding of potato tubers (Solanum tuberosum L. cv. Kennebec), the physiological events occurring below bud at 4°C have been studied for a period of 6 months. The low temperature storage induced an increase in the degree of unsaturation and a decrease in the ratio of saturated/unsaturated fatty acids of membrane polar lipids with a subsequent increase of lipid hydroperoxides (LOOH). Cold stress increased both enzymatic antioxidative activities (superoxide dismutase, SOD, E.C.1.15.1.1; catalase, CAT, E.C. 1.11.1.6), and α-tocopherol levels thus protecting membrane's polyunsaturated lipids. Between 0 and 15 days of storage SOD/CAT ratio, α-tocopherol, LOOH levels and the degree of lipid unsaturation showed strong variations. After 30 to 120/150 days the antioxidative system seemed to reach a homeostasis different from that of time 0, accompanied by a constant increase of indole-3-acetic acid (IAA) after 60 days. The antioxidative system, after 150 days, lost its efficiency while LOOH levels were maintained higher than time 0 and IAA concentration was sufficient to allow sprouting.     

Edaravone protects human peripheral blood lymphocytes from γ-irradiation-induced apoptosis and DNA damage

Radiation-induced cellular injury is attributed primarily to the harmful effects of free radicals, which play a key role in irradiation-induced apoptosis. In this study, we investigated the radioprotective efficacy of edaravone, a licensed clinical drug and a powerful free radical scavenger that has been tested against γ-irradiation-induced cellular damage in cultured human peripheral blood lymphocytes in studies of various diseases. Edaravone was pre-incubated with lymphocytes for 2 h prior to γ-irradiation. It was found that pretreatment with edaravone increased cell viability and inhibited generation of γ-radiation-induced reactive oxygen species (ROS) in lymphocytes exposed to 3 Gy γ-radiation. In addition, γ-radiation decreased antioxidant enzymatic activity, such as superoxide dismutase and glutathione peroxidase, as well as the level of reduced glutathione. Conversely, treatment with 100 μM edaravone prior to irradiation improved antioxidant enzyme activity and increased reduced glutathione levels in irradiated lymphocytes. Importantly, we also report that edaravone reduced γ-irradiation-induced apoptosis through downregulation of Bax, upregulation of Bcl-2, and consequent reduction of the Bax:Bcl-2 ratio. The current study shows edaravone to be an effective radioprotector against γ-irradiation-induced cellular damage in lymphocytes in vitro. Finally, edaravone pretreatment significantly reduced DNA damage in γ-irradiated lymphocytes, as measured by comet assay (% tail DNA, tail length, tail moment, and olive tail moment) (p < 0.05). Thus, the current study indicates that edaravone offers protection from radiation-induced cytogenetic alterations.     

Quantitative study of natural antioxidant systems for cellular nitrofurantoin toxicity

The toxicity of nitrofurantoin was studied on human WI-38 fibroblasts: this chemical was lethal when added at concentrations higher than 5·10⁻⁵ M in the culture medium. The protection afforded by anitoxidants was then tested: α-tocopherol gave at 10⁻⁴ M a light protection in contrast to ascorbic acid which even became toxic at high concentrations. We also tested catalase, superoxide dismutase and glutathione peroxidase introduced intracellularly by the microinjection technique. On a molecular basis, glutathione peroxidase was 23-times more efficient than catalase and 3000-times more than superoxide dismutase. The results also showed that a similar range of enzyme concentrations was found for the protection against high oxygen pressure. This suggests that, in the case of both oxygen and nitrofurantoin toxicity, the peroxide derivatives are the most toxic intermediates of the free radical attacks.     

Molecular and biochemical investigations on the effect of quercetin on oxidative stress induced by cisplatin in rat kidney

The present study was aimed to investigate the ability of quercetin (QE) to ameliorate adverse effects of cisplatin (Cis.) on the renal tissue antioxidants by investigating the kidney antioxidant gene expression and the antioxidant enzymes activity. Forty rats divided into. Control rats. QE treated rats were orally administered 100 mg QE/kg for successive 30 days. Cis. injected rats were administered i.p. Cis. (12 mg/kg b.w.) for 5 mutual days. Cis. + QE rats were administered Cis. i.p. (12 mg/kg) and orally administered 100 mg QE/kg for consecutive 30 days. The obtained results indicated that Cis. induced oxidative stress in the renal tissue. That was through induction of free radical production, inhibition of the activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR) as well their genes expression. At the same time, vitamin E, vitamin C and reduced glutathione (GSH) levels were decreased. QE had the ability to overcome cisplatin-induced oxidative stress through the reduction of free radical levels. The antioxidant genes expression and antioxidant enzymes activity were induced. Finally the vitamin E, vitamin C and GSH levels were increased. Our work, proved the renoprotective effects of QE against oxidative stress induced by cisplatin.     

PKGIα is activated by metal-dependent oxidation in vitro but not in intact cells

Type I cGMP-dependent protein kinases (PKGIs) are important components of various signaling pathways and are canonically activated by nitric oxide– and natriuretic peptide–induced cGMP generation. However, some reports have shown that PKGIα can also be activated in vitro by oxidizing agents. Using in vitro kinase assays, here, we found that purified PKGIα stored in PBS with Flag peptide became oxidized and activated even in the absence of oxidizing agent; furthermore, once established, this activation could not be reversed by reduction with DTT. We demonstrate that activation was enhanced by addition of Cu²⁺ before storage, indicating it was driven by oxidation and mediated by trace metals present during storage. Previous reports suggested that PKGIα Cys⁴³, Cys¹¹⁸, and Cys¹⁹⁶ play key roles in oxidation-induced kinase activation; we show that activation was reduced by C118A or C196V mutations, although C43S PKGIα activation was not reduced. In contrast, under the same conditions, purified PKGIβ activity only slightly increased with storage. Using PKGIα/PKGIβ chimeras, we found that residues throughout the PKGIα-specific autoinhibitory loop were responsible for this activation. To explore whether oxidants activate PKGIα in H9c2 and C2C12 cells, we monitored vasodilator-stimulated phosphoprotein phosphorylation downstream of PKGIα. While we observed PKGIα Cys⁴³ crosslinking in response to H₂O₂ (indicating an oxidizing environment in the cells), we were unable to detect increased vasodilator-stimulated phosphoprotein phosphorylation under these conditions. Taken together, we conclude that while PKGIα can be readily activated by oxidation in vitro, there is currently no direct evidence of oxidation-induced PKGIα activation in vivo.     

β-Glucan from Saccharomyces cerevisiae alleviates oxidative stress in LPS-stimulated RAW264.7 cells via Dectin-1/Nrf2/HO-1 signaling pathway

β-Glucan from Saccharomyces cerevisiae has been described to be effective antioxidants, but the specific antioxidation mechanism of β-glucan is unclear. The objectives of this research were to determine whether the β-glucan from Saccharomyces cerevisiae could regulate oxidative stress through the Dectin-1/Nrf2/HO-1 signaling pathway in lipopolysaccharides (LPS)-stimulated RAW264.7 cells. In this study, we examined the effects of β-glucan on the enzyme activity or production of oxidative stress indicators in LPS-stimulated RAW264.7 cells by biochemical analysis and the protein expression of key factors of Dectin-1/Nrf2/HO-1 signaling pathway by immunofluorescence and western blot. The biochemical analysis results showed that β-glucan increased the LPS-induced downregulation of enzyme activity of intracellular heme oxygenase (HO), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) while decreasing the production of reactive oxygen species (ROS) and malondialdehyde (MDA). Furthermore, immunofluorescence results showed that β-glucan can activate the nuclear factor erythroid 2-related factor 2 (Nrf2). The antioxidant mechanism study indicated that β-glucan activated dendritic-cell-associated C-type lectin 1 (Dectin-1) receptors mediated Nrf2/HO-1 signaling pathway, thereby downregulating the production of ROS and thus produced the antioxidant effects in LPS-stimulated RAW 264.7 cells. In conclusion, these results indicate that β-glucan potently alleviated oxidative stress via Dectin-1/Nrf2/HO-1 in LPS-stimulated RAW 264.7 cells.     

Ultrastructural Changes in Potato Tuber Pith Cells during Brown Center Development

Electron microscopy revealed that subjecting `Russet Burbank' potato (Solanum tuberosum L.) plants to 2 days of cool temperature growing conditions (18°C days/10°C nights) did not produce visible damage or changes in tuber pith tissue when compared to warm-grown tubers (23°C days/18°C nights). However, damage to some tuber pith cells was observed after 5 days of cool treatment. Eight days of cool treatment produced extensive alterations in cell structure. The cytoplasm of the cool-treated tuber pith cells had become highly vesiculated and there was evidence of complete destruction of amyloplast membranes and tonoplasts. In many cases the starch grains appeared to be undergoing hydrolysis suggesting total disruption of normal cell function. Sixteen days of cool treatment were sufficient to produce visible brown center development in all cool-grown tubers examined. Electron microscopy of these tissues revealed that, although some organelles were still present, the cytoplasm had become extremely vesiculated and lacked any resemblance to that of tissue from warm-grown tubers. Gross, irregular thickening of cell walls was also detected.     

Elevated seasonal temperature disrupts prooxidant-antioxidant homeostasis and promotes cellular apoptosis in the American oyster,Crassostrea virginica,in the Gulf of Mexico: a field study

One of the major impacts of climate change has been the marked rise in global temperature. Recently, we demonstrated that high temperatures (1-week exposure) disrupt prooxidant-antioxidant homeostasis and promote cellular apoptosis in the American oyster. In this study, we evaluated the effects of seasonal sea surface temperature (SST) on tissue morphology, extrapallial fluid (EPF) conditions, heat shock protein-70 (HSP70), dinitrophenyl protein (DNP, an indicator of reactive oxygen species, ROS), 3-nitrotyrosine protein (NTP, an indicator of RNS), catalase (CAT), superoxide dismutase (SOD) protein expressions, and cellular apoptosis in gills and digestive glands of oysters collected on the southern Texas coast during the winter (15 °C), spring (24 °C), summer (30 °C), and fall (27 °C). Histological observations of both tissues showed a notable increase in mucus production and an enlargement of the digestive gland lumen with seasonal temperature rise, whereas biochemical analyses exhibited a significant decrease in EPF pH and protein concentration. Immunohistochemical analyses showed higher expression of HSP70 along with the expression of DNP and NTP in oyster tissues during summer. Intriguingly, CAT and SOD protein expressions exhibited significant upregulation with rising seasonal temperatures (15 to 27 °C), which decreased significantly in summer (30 °C), leaving oysters vulnerable to oxidative and nitrative damage. qRT-PCR analysis revealed a significant increase in HSP70 mRNA levels in oyster tissues during the warmer seasons. In situ TUNNEL assay showed a significant increase in apoptotic cells in seasons with high temperature. These results suggest that elevated SST induces oxidative/nitrative stress through the overproduction of ROS/RNS and disrupts the antioxidant system which promotes cellular apoptosis in oysters.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12192-021-01232-2.     

Isolation and Antigenic Characterization of Corn Mitochondrial F(1)-ATPase

Corn mitochondrial F₁-ATPase was purified from submitochondrial particles by chloroform extraction. Enzyme stored in ammonium sulfate at 4°C was substantially activated by ATP, while enzyme stored at −70°C in 25% glycerol was not. Enzyme in glycerol remained fully active (8-9 micromoles P_i released per minute per milligram), while the ammonium sulfate preparations steadily lost activity over a 2-month storage period. The enzyme was cold labile, and inactived by 4 minutes at 60°C. Treatment with octylglucoside resulted in complete loss of activity, while vanadate had no effect on activity. The apparent subunit molecular weights of corn mitochondrial F₁-ATPase were determined by SDS-polyacrylamide gel electrophoresis to be 58,000 (α), 55,000 (β), 35,000 (γ), 22,000 (δ), and 12,000 (ε). Monoclonal and polyclonal antibodies used in competitive binding assays demonstrated that corn mitochondrial F₁-ATPase was antigenically distinct from the chloroplastic CF₁-ATPases of corn and spinach. Monoclonal antibodies against antigenic sites on spinach CF₁-ATPase β and γ subunits were used to demonstrate that those sites were either changed substantially or totally absent from the mitochondrial F₁-ATPase.     

Wine grape pomace flour improves blood pressure,fasting glucose and protein damage in humans: a randomized controlled trial

Background

The Mediterranean diet is a healthy diet with positive scientific evidence of preventing chronic diseases. Bioactive components support the healthy properties of the Mediterranean diet. Antioxidants and fiber, two components of the Mediterranean diet, are key functional nutrients for healthy eating and nutrition. Wine grape pomace is a rich source of these dietary constituents and may be beneficial for human health. Our hypothesis was that the intake of red wine grape pomace flour (WGPF) prepared from red wine grapes (Cabernet Sauvignon variety) reduced the metabolic syndrome in humans. To evaluate the effect of WGPF on components of metabolic syndrome we design a 16-week longitudinal intervention study. Thirty-eight males, 30–65 years of age, with at least one component of metabolic syndrome, were randomly assigned to either the intervention group (n = 25) or the control group (n = 13). At lunch, the intervention group was given 20 g of WGPF per day, which contained 10 g of dietary fiber, 822 mg of polyphenols and an antioxidant capacity of 7258 ORAC units. Both groups were asked to maintain their regular eating habits and lifestyles. Clinical evaluation, anthropometric measurements and biochemical blood analyses were done at the beginning and the end of the study.

Results

WGPF intake significantly decreased systolic and diastolic blood pressure as well as fasting glucose levels. Plasma γ-tocopherol and δ-tocopherol increased and carbonyl group in plasma protein decreased in WGPT group, significantly. No significant effect was observed for waist circumference, HDL cholesterol, triglycerides, total antioxidant capacity and vitamin C in and between groups. The group-dependent magnitude of the differences between the baseline and final postprandial insulin values and γ-tocopherol concentrations was statistically significant.

Conclusions

The consumption of WGPF-rich in fiber and polyphenol antioxidants, as a food supplement in a regular diet improves blood pressure, glycaemia and postprandial insulin. In addition, increased antioxidant defenses and decreased oxidative protein damage indicating attenuation of oxidative stress. WGPF might be a useful food ingredient for health promotion and chronic disease prevention.     

Storage Temperature Alters the Expression of Differentiation-Related Genes in Cultured Oral Keratinocytes

Purpose

Storage of cultured human oral keratinocytes (HOK) allows for transportation of cultured transplants to eye clinics worldwide. In a previous study, one-week storage of cultured HOK was found to be superior with regard to viability and morphology at 12°C compared to 4°C and 37°C. To understand more of how storage temperature affects cell phenotype, gene expression of HOK before and after storage at 4°C, 12°C, and 37°C was assessed.

Materials and Methods

Cultured HOK were stored in HEPES- and sodium bicarbonate-buffered Minimum Essential Medium at 4°C, 12°C, and 37°C for one week. Total RNA was isolated and the gene expression profile was determined using DNA microarrays and analyzed with Partek Genomics Suite software and Ingenuity Pathway Analysis. Differentially expressed genes (fold change > 1.5 and P < 0.05) were identified by one-way ANOVA. Key genes were validated using qPCR.

Results

Gene expression of cultures stored at 4°C and 12°C clustered close to the unstored control cultures. Cultures stored at 37°C displayed substantial change in gene expression compared to the other groups. In comparison with 12°C, 2,981 genes were differentially expressed at 37°C. In contrast, only 67 genes were differentially expressed between the unstored control and the cells stored at 12°C. The 12°C and 37°C culture groups differed most significantly with regard to the expression of differentiation markers. The Hedgehog signaling pathway was significantly downregulated at 37°C compared to 12°C.

Conclusion

HOK cultures stored at 37°C showed considerably larger changes in gene expression compared to unstored cells than cultured HOK stored at 4°C and 12°C. The changes observed at 37°C consisted of differentiation of the cells towards a squamous epithelium-specific phenotype. Storing cultured ocular surface transplants at 37°C is therefore not recommended. This is particularly interesting as 37°C is the standard incubation temperature used for cell culture.     

Effects of calcium lactate on postharvest quality of bitter gourd fruit during cold storage

This study was aimed to assess the effects of calcium lactate (CL) on quality, shelf-life and storage physiology of bitter gourd. Fruits were dipped in the aqueous solution of CL (50, 75, and 100 mM) and stored at 10 °C and 85–95% relative humidity (RH). The changes in physical, biochemical and enzymological parameters were recorded at five days interval. The results showed that in CL@100 mM treated fruit, physiological loss in weight (PLW) and decay incidence were minimized. Conversely, their firmness, total phenolics, antioxidants and total chlorophyll retained at higher side. The CL @ 75 mM was able to retain higher ascorbic acid up to 20 days while CL@100 mM was effective in controlling pectin methylesterase (PME) activity and increasing the inhibitory activity of α-amylase and α-glucosidase. Therefore, our observations suggested that by applying CL@100 mM, 5 days extra (20 days) shelf-life of bitter gourd fruit can be achieved with notable retention of biochemical compounds over untreated fruit (15 days with poor retention of important nutrients).