Total Lipid Accumulation Research Articles

Exploring Porphyridium purpureum and Porphyridium aerugineum as alternative resources for phycobiliprotein production

Microalgae not only fix carbon dioxide, but also represent a promising alternative resource for the production of proteins, lipids, and polysaccharides. This study employed two Porphyridium strains to compare their responses under different light qualities. P. purpureum up-regulated the content (up to 69.37 ± 0.92 mg/g DW) and proportion of phycoerythrin to enhance light absorption, which led to the accumulation of total soluble proteins, neutral lipids and exopolysaccharides under blue light. In contrast, P. aerugineum primarily improved the light energy utilization by increasing phycocyanin levels (up to 81.10 ± 0.60 mg/g DW), resulting in the degradation of neutral lipids and the accumulation of exopolysaccharides. Given the biomass, the highest yields of phycoerythrin (169.61 ± 2.90 mg/L) and phycocyanin (216.92 ± 1.90 mg/L) were achieved by P. purpureum and P. aerugineum cultured under white light, respectively. These findings indicate that Porphyridium can serve as a valuable resource for phycobiliprotein production, with biomolecules synthesis being tightly regulated by light quality.

High-throughput optimization of organic carbon provision strategies enables enhanced arachidonic acid production in novel microalgae

BackgroundMicroalgae are potential sustainable resources for the production of value-added chemicals that can be used as biofuels, pharmaceuticals, and nutritional supplements. Arachidonic acid (ARA), a omega-6 fatty acid, plays a crucial role in infant development and immune response, and can be used in cosmetics and pharmaceuticals. Demand for industrial-scale ARA production is continuously increasing because of its broad applicability. To address this demand, there has been a significant shift towards microorganism-based ARA production. To accelerate large-scale ARA production, it is crucial to select suitable strains and establish optimal culture conditions.ResultsHere, we isolated a novel microalga Lobosphaera incisa CFRC-1, a valuable strain that holds promise as a feedstock for ARA production. Optimal cultivation conditions were investigated using a high-throughput screening method to enhance ARA production in this novel strain. Out of 71 candidates, four organic carbon substrates were identified that could be utilized by L. incisa CFRC-1. Through flask-scale verification, fructose was confirmed as the optimal organic carbon substrate for promoting microalgal growth, total lipid accumulation, and ARA production. Subsequently, we investigated appropriate substrate concentration and cultivation temperature, confirming that the optimal conditions were 30 g L− 1 of fructose and 27 ℃ of temperature. Under these optimized conditions, biomass and ARA production reached 13.05 ± 0.40 g L− 1 and 97.98 ± 7.33 mg L− 1, respectively, representing 9.6-fold and 5.3-fold increases compared to the conditions before optimization conditions. These results achieved the highest biomass and ARA production in flask-scale cultivation, indicating that our approach effectively improved both production titer and productivity.ConclusionsThis study presents a novel microalgae and optimized conditions for enhancing biomass and ARA production, suggesting that this approach is a practical way to accelerate the production of valuable microalgae-based chemicals. These findings provide a basis for large-scale production of ARA-utilizing microalgae for industrial applications.

Comparing the obesogenic effect and regulatory mechanisms of long-term exposure to per/polyfluoroalkyl substances with different terminal groups in Caenorhabditis elegans

Per/polyfluoroalkyl substances (PFASs) are ubiquitous, bioaccumulative, and recalcitrant contaminants, posing global exposure and health risks. The effects of chemical structures on toxicities and the mechanisms of their obesogenic effects were largely unclear. This study used the model organism Caenorhabditis elegans to assess the impact of long-term exposure to different PFASs (PFNA, PFOSA, PFBS, PFHxS, 6:2 FTS, 4:2 FTS, PFOA, and PFOS) on growth and lipid metabolism and discussed the obesogenic mechanisms of selected PFASs. The growth assays indicated longer carbon-fluorine (-CF) chains and total fluorine atoms increased developmental toxicity of PFASs, while at 8 –CF chain-length, PFNA (-COOH terminal), PFOS (-SO3 terminal), and PFOSA (-SO2NH2 terminal) exhibited differential growth inhibition. With the toxicity ranking of PFNA > PFOS > PFOSA, all PFASs significantly induced total lipid accumulation and perturbed the lipid composition in C. elegans. All three PFASs significantly induced lipogenesis gene expression and partially suppressed lipolysis genes. The results suggested that the disruption of lipid metabolism of PFOSA depends on sbp-1, while PFNA and PFOS depend on nhr-49. In conclusion, long-term exposure to PFNA, PFOSA, and PFOS triggers obesogenic effects in organisms by distinct molecular mechanisms.

Caffeic acid combined with arabinoxylan or β-glucan attenuates diet-induced obesity in mice via modulation of gut microbiota and metabolites

Polyphenols and dietary fibers in whole grains are important bioactive compounds to reduce risks for obesity. However, whether the combination of the two components exhibits a stronger anti-obesity effect remains unclear. Caffeic acid is a major phenolic acid in cereals, and arabinoxylan and β-glucan are biological macromolecules with numerous health benefits. Here, we investigated the effect of caffeic acid combined with arabinoxylan or β-glucan on glucose and lipid metabolism, gut microbiota, and metabolites in mice fed a high-fat diet (HFD). Caffeic acid combined with arabinoxylan or β-glucan significantly reduced the body weight, blood glucose, and serum free fatty acid concentrations. Caffeic acid combined with β-glucan effectively decreased serum total cholesterol levels and hepatic lipid accumulation, modulated oxidative and inflammatory stress, and improved gut barrier function. Compared with arabinoxylan, β-glucan, and caffeic acid alone, caffeic acid combined with arabinoxylan or β-glucan exhibited a better capacity to modulate gut microbiota, including increased microbial diversity, reduced Firmicutes/Bacteroidetes ratio, and increased abundance of beneficial bacteria such as Bifidobacterium. Furthermore, caffeic acid combined with β-glucan reversed HFD-induced changes in microbiota-derived metabolites involving tryptophan, purine, and bile acid metabolism. Thus, caffeic acid and β-glucan had a synergistic anti-obesity effect by regulating specific gut microbiota and metabolites.

Bisphenol A induces non-alcoholic fatty liver disease by promoting the O-GlcNAcylation of NLRP3

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease. The mechanism by which bisphenol A (BPA) promots NAFLD remains unclear. Palmitic acid (PA) and lipopolysaccharide (LPS) were used to simulate NAFLD in HepG2 cells in vitro. Total cholesterol (TC), triglyceride (TG) content, and lipid accumulation were measured to evaluate lipid metabolism. The caspase-1-stained cells and NLRP3 inflammasome-associated proteins were evaluated for pyroptosis. Western blot analysis was used to detect protein levels and co-immunoprecipitation (Co-IP) was used to detect the association between the proteins. Cycloheximide (CHX) treatment combined with western blot was performed to access protein stability. This data have shown that BPA induces lipid metabolism dysfunction and pyroptosis by upregulating O-GlcNAc transferase (OGT) level. NLRP3 directly interacts with OGT, and elevated OGT enhanced the stability of NLRP3 protein. BPA promoted OGT-mediated O-GlcNAcylation to stabilised NLRP3, thus accelerating NAFLD progress in vitro. Our study reveals that BPA, as an environmental factor, may be involved in the promotion of NAFLD, and that targeting NLRP3 and OGT may inhibit BPA’s induction of NAFLD.

Two Triterpenoids, ARM-2 and RA-5, From Protorhus longifolia Exhibit the Potential to Modulate Lipolysis and Lipogenesis in Cultured 3T3-L1 Adipocytes.

Triterpenoids have been identified as potential novel lipid-lowering drugs for the treatment of hypertriglyceridemia. This study investigated the potential antilipogenic and/or antilipolytic effects of two triterpenoids (ARM-2 and RA-5) isolated from the stem bark of Protorhus longifolia (Benrh.) Engl. Employing a combination of in silico predictions and in vitro assays, the interactions between these triterpenoids and key proteins involved in lipogenesis and lipolysis were investigated. In silico molecular docking analysis predicted a favourable binding affinity of both triterpenoids to PPARγ, SREBP-1, and AMPK, with lower binding affinity to C/EBPα, pancreatic lipase, and hormone-sensitive lipase (HSL). Both triterpenoids exhibited in vitro inhibition of pancreatic lipase with Ki and IC50 values ranging from 28.7 to 52.9 μM and 27.6 to 35.8 μM, respectively. Total and neutral lipid accumulation in differentiated 3T3-L1 adipocytes and the oleic acid-induced HepG2 cell model was inhibited, with ARM-2 showing better inhibition than RA-5. In the HepG2 model, the inhibitory activity of the two triterpenoids (at 25 and 100 μM) was comparable to 50 μM lovastatin, although the latter was cytotoxic, whereas both ARM-2 and RA-2 lacked cytotoxicity. Associated gene expression was similar to the effect of simvastatin where the expression of SREBP-1, PPARγ, C/EBPα, and HSL was reduced and that of AMPK was unchanged. In vitro studies confirmed that ARM-2 and RA-5 also inhibited adipocyte lipolysis, where the reduction in glycerol release by 25 and 100 μM was similar to 50 μM lovastatin and simvastatin. This study identifies that the triterpenoids, ARM-2 and RA-5, have the potential to modulate lipogenesis and lipolysis.

Antioxidant and Anti-Obesity Effects of Juglans mandshurica in 3T3-L1 Cells and High-Fat Diet Obese Rats.

Juglans mandshurica Maxim. walnut (JMW) is well-known for the treatment of dermatosis, cancer, gastritis, diarrhea, and leukorrhea in Korea. However, the molecular mechanism underlying its anti-obesity activity remains unknown. In the current study, we aimed to determine whether JMW can influence adipogenesis in 3T3-L1 preadipocytes and high-fat diet rats and determine the antioxidant activity. The 20% ethanol extract of JMW (JMWE) had a total polyphenol content of 133.33 ± 2.60 mg GAE/g. Considering the antioxidant capacity, the ABTS and DPPH values of 200 μg/ml of JMWE were 95.69 ± 0.94 and 79.38 ± 1.55%, respectively. To assess the anti-obesity activity of JMWE, we analyzed the cell viability, fat accumulation, and adipogenesis-related factors, including CCAAT-enhancer-binding protein alpha (C/EBPα), sterol regulatory element-binding protein-1c (SREBP1c), peroxisome proliferator-activated receptor-gamma (PPARγ), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). We found that total lipid accumulation and triglyceride levels were reduced, and the fat accumulation rate decreased in a dose-dependent manner. Furthermore, JMWE suppressed adipogenesis-related factors C/EBPα, PPARγ, and SREBP1c, as well as FAS and ACC, both related to lipogenesis. Moreover, animal experiments revealed that JMWE could be employed to prevent and treat obesity-related diseases. Hence, JMWE could be developed as a healthy functional food and further explored as an anti-obesity drug.

Glucocorticoid Receptor Antagonism Improves Glucose Metabolism in a Mouse Model of Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is a complex metabolic disorder associated with obesity, insulin resistance, and dyslipidemia. Hyperandrogenism is a major characteristic of PCOS. Increased androgen exposure is believed to deregulate metabolic processes in various tissues as part of the PCOS pathogenesis, predominantly through the androgen receptor (AR). Notably, various metabolic features in PCOS are similar to those observed after excess glucocorticoid exposure. We hypothesized that glucocorticoid receptor (GR) signaling is involved in the metabolic symptoms of PCOS. In a PCOS model of chronic dihydrotestosterone (DHT) exposure in female mice, we investigated whether GR signaling machinery was (de)regulated, and if treatment with a selective GR antagonist alleviated the metabolic symptoms. We observed an upregulation of GR messenger RNA expression in the liver after DHT exposure. In white adipose tissues and liver we found that DHT upregulated Hsd11b1, which encodes for the enzyme that converts inactive into active glucocorticoids. We found that preventive but not therapeutic administration of a GR antagonist alleviated DHT-induced hyperglycemia and restored glucose tolerance. We did not observe strong effects of GR antagonism in DHT-exposed mice on other features like total fat mass and lipid accumulation in various tissues. We conclude that GR activation may play a role in glucose metabolism in DHT-exposed mice.

Adaptive laboratory evolution empowers lipids and biomass overproduction in Chlorella vulgaris for environmental applications

Microalgal strain improvement with commercial features is needed to generate green biological feedstock to produce lipids for bioenergy. Hence, improving algal strain with enhanced lipid content without hindering cellular physiological parameters is pivotal for commercial applications of microalgae. In this report, we demonstrated the adaptive laboratory evolution (ALE) by hypersaline conditions to improve the algal strains for increasing the lipid overproduction capacity of Chlorella vulgaris for environmental applications. The evolved strains (namely E2 and E2.5) without notable impairment in general physiological parameters were scrutinized after 35 cycles. Conventional gravimetric lipid analysis showed that total lipid accumulation was hiked by 2.2-fold in the ALE strains compared to the parental strains. Confocal observation of algal cells stained with Nile-red showed that the abundance of lipid droplets was higher in the evolved strains without any apparent morphological aberrations. Furthermore, evolved strains displayed notable antioxidant potential than the control cells. Interestingly, carbohydrates and protein content were significantly decreased in the evolved cells, indicating that carbon flux was redirected into lipogenesis in the evolved cells. Altogether, our findings demonstrated a potential and feasible strategy for microalgal strain improvement for simultaneous lipids and biomass hyperaccumulation.

Impact of H2O2 on biomass and lipid accumulation in Scenedesmus sp.: Promising species for biofuel production

The economical production of lipids from algae needs to be investigated and optimized. Interestingly, hydrogen peroxide (H2O2) is a stress inducer that enhances lipid accumulation in microalgae. In the present study, the effect of H2O2 along with nutrients variation on total lipid accumulation in Scenedesmus sp. is investigated. Results show, H10N0P0.22 has highest lipid production (156.6 ± 24.3 μg/mg), followed by H0N0P0 (145.2 ± 33.3 μg/mg) and H10N0P0 (139.8 ± 38.1 μg/mg) after 24hrs of H2O2exposure. Gas chromatography analysis showed maximum C16:0 for H0N0P0 (24%), closely followed by H10N0P0.22 (23.4%) and H10N0P0 (23.2%) after 24hrs of H2O2 treatment, though much significant difference was not observed. Increased concentrations of H2O2 led to a decrease in biomass and “chlorophyll a” content. Biodiesel properties such as cetane number, saponification value, degree of unsaturation and Iodine value have also been observed in the current study to understand the impact of combined stress. Further principal component analysis (PCA) amongst various combinations reveals that H10N0P0.22 is a significant contributor to the variance. Thus, Scenedesmus sp. under oxidative stress yield increased accumulation of total lipid with less significant difference after 24 h of H2O2 treatment, thus, this study can be further examined under the various optimized condition to be utilized in large-scale cultivation of biodiesel targeting the ever-increasing energy demands.

Effect of Crocetin on Basal Lipolysis in 3T3-L1 Adipocytes.

Crocetin (CCT) is a natural saffron-derived apocarotenoid that possesses healthy properties such as anti-adipogenic, anti-inflammatory, and antioxidant activities. Lipolysis is enhanced in obesity and correlates with a pro-inflammatory, pro-oxidant state. In this context, we aimed to investigate whether CCT affects lipolysis. To evaluate CCT's possible lipolytic effect, 3T3-L1 adipocytes were treated with CCT10μM at day 5 post-differentiation. Glycerol content and antioxidant activity were assessed using colorimetric assays. Gene expression was measured using qRT-PCR to evaluate the effect of CCT on key lipolytic enzymes and on nitric oxide synthase (NOS) expression. Total lipid accumulation was assessed using Oil Red O staining. CCT10μM decreased glycerol release from 3T3-L1 adipocytes and downregulated adipose tissue triglyceride lipase (ATGL) and perilipin-1, but not hormone-sensitive lipase (HSL), suggesting an anti-lipolytic effect. CCT increased catalase (CAT) and superoxide dismutase (SOD) activity, thus showing an antioxidant effect. In addition, CCT exhibited an anti-inflammatory profile, i.e., diminished inducible NOS (NOS2) and resistin expression, while enhanced the expression of adiponectin. CCT10μM also decreased intracellular fat and C/EBPα expression (a transcription factor involved in adipogenesis), thus revealing an anti-adipogenic effect. These findings point to CCT as a promising biocompound for improving lipid mobilisation in obesity.

Developmental toxicity of perfluorohexane sulfonate at human relevant dose during pregnancy via disruption in placental lipid homeostasis

Perfluorohexyl sulfonate (PFHxS) is the third most abundant per- and polyfluoroalkyl substances and its developmental toxicity remains very poorly understood. Here, pregnant mice exposed to PFHxS at human relevant dose showed increased fetal death incidence in the high-dose PFHxS-H group (P < 0.01). Body distribution analyses suggested that PFHxS crossed the placental barrier reaching the fetus in a dose-dependent manner. Histopathological data demonstrated impairment in the placenta with reduced blood sinus volume, placental labyrinth area as well as thickness of labyrinthine layer. Further lipidomic and transcriptomic data together showed that PFHxS exposure caused significant disruption in placental lipid homeostasis, including total lipid accumulation in the placenta, and dysregulation in phospholipid and glycerol lipid metabolism. Gene expression analyses uncovered elevation in key placental fatty acid transporters including fabp2, whereas protein expression showed transporter specific disruptions following exposure. Together, gestational exposure to human relevant level of PFHxS may increase the incidence of fetal deaths and caused placental dysplasia via disruption in lipid metabolism homeostasis. These findings raise the concern regarding the highly prevalent and persistent chemical towards early sensitive developing stages and provide basis for further understanding of its effects on lipid metabolism and underlying mechanisms.

Characterization of nongxiang- and soy sauce-type distilled grains and their application in enhancing polyunsaturated fatty acid and triacylglyceride production from Chlorella sp. 038F

A sustainable method of handling large quantities of distilled grains in the Chinese baijiu industry is bioconverting these distilled grains into value-added products. We here compared the properties of two distilled grains, soy sauce-type (DGSB) and nongxiang-type (DGNB). Results revealed that DGSB had higher contents of crude protein, crude fat, soluble sugars, free amino acids, and antioxidants than DGNB. Mixotrophic cultivation of Chlorella sp. 038F was performed using aqueous crude extracts of distilled grains. Biomass, total lipid, and fatty acid production with DGSB crude extracts was approximately 2.43, 1.40, and 1.69 times higher than that with photoautotrophic culture, respectively, whereas DGNB crude extracts only improved the biomass by 1.64 times. Detailed profile analysis revealed that DGSB crude extracts remarkably increased the proportions of polyunsaturated fatty acids, especially linoleic and α-linolenic acids, and triacylglycerides in total lipids. Interestingly, DGNB crude extracts did not enhance total lipid accumulation but increased triacylglyceride accumulation. Comparative transcriptomics revealed that genes encoding photosynthetic pigments and proteins were downregulated, suggesting the decreased anabolism of the photosynthetic light reaction. Genes involved in fatty acid biosynthesis, the Calvin cycle, and glycolysis were upregulated, indicating sufficient accumulation of the building blocks acyl-CoA and glycerol-3-phosphate for triacylglyceride biosynthesis. All transcriptional trends of triacylglyceride biosynthesis-related genes were consistent with the triacylglyceride accumulation patterns. This study provides insights into the potential use of microalgae for the bioconversion of distilled grains into high-value products and highlights the role of distilled grains in improving polyunsaturated fatty acid and triacylglyceride production.

Resveratrol supplementation or diet intervention effects on heart-liver axis in prediabetic female rats submitted to high-fat-high-sucrose diet

NAFLD and type 2 diabetes (T2D) share a bidirectional relationship and cardiovascular diseases (CVD) as leading death cause, but this relationship in prediabetes is still poorly known, especially for women which exhibit an exacerbated CVD risk. Here, we evaluated the effects of resveratrol supplementation (RSV) or diet intervention on the heart-liver axis of prediabetic female rats submitted to high-fat-high-sucrose diet (HFS). Forty Female Wistar rats were divided into 4 groups fed for 5 months with: a standard diet (CTRL), HFS diet (HFS), HFS diet supplemented for the last 2 months with RSV (1 mg/kg/day in water) (RSV) or HFS diet for 3 months followed by 2 months of standard diet (RSD). In vivo Magnetic Resonance Imaging was performed to study cardiac morphology/function. Then, tolerance to ischemia-reperfusion injury was investigated ex vivo by simultaneous measurement of cardiac function (RPP, EDP) and energy metabolism by 31P Magnetic Resonance Spectroscopy. Hepatic total lipid and triglycerides (TG) contents along expression of genes involved in lipid metabolism/inflammation were studied. HFS induced glucose intolerance (P < 0.01), increased diastolic left ventricular volume and thickness (P < 0.05) and heart weight to tibia length ratio (HTLR) (P < 0.01). HFS diet also altered myocardial tolerance to IR, with impaired RPP and EDP (P < 0.001) and PCr during reperfusion (P < 0.05). Both treatments improved glucose tolerance (P < 0.05). Importantly, despite maintained HFS diet, RSV restored the elevated diastolic volume and thickness in vivo (P < 0.01 CTRL, RSV vs. HFS, RSD) and HTLR level (P < 0.001 CTRL, RSV vs. HFS, RSD), conversely to RSD. Both treatments improved the tolerance to IR, with increased RPP (P < 0.05 vs. HFS) along with PCr during reperfusion (P < 0.001, P < 0.01 vs. HFS respectively). Only RSV decreased EDP during IR injury (P < 0.05). In the liver HFS diet induced total lipid and TG accumulation (P < 0.01) as well as elevated expression of lipid oxidation/peroxidation genes without effect on lipogenesis and inflammation cytokines genes. Both treatments normalized hepatic total lipid levels. RSD restored TG levels along elevated lipid metabolism gene expressions (P < 0.01) whereas RSV partially reduced the increase (P < 0.05). Despite maintained HFS and moderate hepatic lipid metabolism effects, RSV exhibited better cardioprotection than RSD, suggesting its potential to protect against early cardiac alterations associated with prediabetes and NAFLD, especially for women.

Effect of ethylthiosulfаnylate in combination with vitamin E on certain biochemical blood parameters and hematological indicators in rats under the influence of Cr(VI)

The aim of our study was to investigate the effect of ethylthiosulfаnylate, a representative of the class of thiosulfonate compounds, in combination with vitamin E on certain biochemical blood parameters, hematological indicators and total Chromium content in liver of rats exposed to Cr(VI). Laboratory rats were divided into 8 groups of 5 animals each. Animals of group I (intact control) were injected daily intraperitoneally with 150 μl of physiological saline solution for 7 days. Rats of III/IV groups received intraperitoneal daily administration of K2Cr2O7 (diluted in physiological saline solution at a dose of 2.5 mg Cr(VI)/kg) for 7/14 days. Animals of the II experimental group were injected daily intragastrically with 1000 μl of sunflower oil for 14 days. Rats of V/VI experimental groups were administrated daily intragastrically with 1000 μl of an oil solution of vitamin E (20 mg/kg)/vitamin E (20 mg/kg) in combination with ethylthiosulfаnylate (100 mg/kg) for 14 days. Animals of VII/VIII experimental groups were injected daily intragastrically with 1000 μl of an oil solution of vitamin E (20 mg/kg) in combination with ethylthiosulfаnylate (100 mg/kg) for 14 days, after which a 7-day/14-day period of intraperitoneal K2Cr2O7 administration was performed. Exposure to Cr(VI) led to a decrease in the number of erythrocytes, leukocytes, content of hemoglobin, phospholipids, total protein against the background of the accumulation of total lipids, mono- and diglycerides, non-esterified fatty acids, and creatinine in blood of rats. Chromium concentration significantly increased in the liver of rats after administration of Cr(VI). The combined effect of vitamin E and ethylthiosulfаnylate contributed to the partial compensation of Cr(VI)-induced disturbances of the number of leukocytes and content of total proteins, phospholipids, non-esterified fatty acids in blood of rats. Vitamin E and ethylthiosulfаnylate pretreatment also contributed to the reduction of the percentage accumulation of Chromium in liver of rats injected with Cr(VI).

Efficient use of discarded vegetal residues as cost-effective feedstocks for microbial oil production

BackgroundHorticultural intensive type systems dedicated in producing greenhouse vegetables are one of the primary industries generating organic waste. Towards the implementation of a zero-waste strategy, this work aims to use discarded vegetables (tomato, pepper and watermelon) as feedstock for producing microbial oil using the oleaginous yeast Cryptococcus curvatus.ResultsThe soluble fraction, resulting after crushing and centrifuging these residues, showed C/N ratios of about 15, with a total carbohydrate content (mainly glucose, fructose and sucrose) ranging from 30 g/L to 65 g/L. Using these liquid fractions as substrate under a pulse-feeding strategy with a concentrated glucose solution resulted in an intracellular total lipid accumulation of about 30% (w/w) of the total dry cell weight (DCW). To increase this intracellular lipid content, the initial C/N content was increased from 15 to 30 and 50. Under these conditions, the process performance of the pulse-feeding strategy increased by 20–36%, resulting in a total intracellular lipid concentration of 35–40% DCW (w/w).ConclusionThese results demonstrate the potential of discarded vegetables as a substrate for producing bio-based products such as microbial oil when proper cultivation strategies are available.

Impact of Different Light Characteristics on the Growth and Lipid Content of Diatom &amp;lt;i&amp;gt;Phaeodactylum tricornutum&amp;lt;/i&amp;gt; Transconjugant Strains

Light regulates important metabolic processes in microalgal cells, which can further impact the metabolism and the accumulation of biomolecules such as lipids, carbohydrates, and proteins. Different characteristics of light have been studied on various strains of the model diatom Phaeodactylum tricornutum, but not on transconjugant cells and information on wild-type strains is still limited. Therefore, we studied the impact of different light characteristics such as spectral quality, light intensity and light shift on the growth, and the composition in lipids and fatty acids of P. tricornutum cells to provide a comprehensive context for future applications. Initially, we tested the impact of spectral quality and light intensity on P. tricornutum transformed with an episomal vector (Ptev), harboring the resistance gene Sh ble. Results indicated that Ptev cells accumulated more biomass and overall lipids in spectral quality Red 1 (R1: 34% > 600 nm > 66%) more effectively as compared to Red 2 (R2: 8% > 600 nm > 92%). It was also detected that cell granularity was higher in R1 as compared to R2. Furthermore, by testing two light intensities 65 μmol·m-2·s-1 and 145 μmol·m-2·s-1 light, it was observed that 145 μmol·m-2·s-1 led to an increase in growth trend, total biomass and lipid content. Combining spectral qualities and light intensities, we show that the lipid accumulation raised by 2.8-fold. Studying the light intensity and spectral quality allowed us to optimize the light conditions to R1 spectral quality and light intensity 145 μmol·m-2·s-1. These initial results showed that red light R1 at 145 μmol·m-2·s-1 was the best condition for biomass and total lipids accumulation in Ptev cells. Next, we further combined these two-light optimizations with a third light characteristics, i.e. light shift, where the cultures were shifted during the early stationary phase to a different light environment. We studied Red light shift (Rs) to investigate how light condition variations impacted P. tricornutum transconjugants Ptev and with an episomal vector containing the reporter gene YFP (PtYFP). We observed that Rs induced growth and fatty acid eicosapentaenoic acid (EPA) in Ptev as compared to PtYFP. Altogether, the study shows that red light shift of R1 at 145 μmol·m-2·s-1 promoted biomass and total lipids accumulation in Ptev and PtYFP cells. The study provides a comprehensive approach to using different light characteristics with the aim to optimize growth and lipids, as well as to fatty acid production.

Altered Lysosomal Function Manipulates Cellular Biosynthetic Capacity By Remodeling Intracellular Cholesterol Distribution.

Lysosomes are known to influence cholesterol trafficking into endoplasmic reticulum (ER) membranes. Though intracellular cholesterol levels are known to influence the lipid biosynthetic responses in ER, the specific effects of lysosomal modulation on these outcomes is not known. To demonstrate this, C2C12 cells were treated with chloroquine, a lysosomotropic agent, and its effects on cellular biosynthetic capacity, structural and functional status of ER was determined. In addition to its known effects on autophagy reduction, chloroquine treatment induced accumulation of total cellular lipid and ER-specific cholesterol content. It was also observed that chloroquine caused an increase in smooth-ER content with defects in overall protein turnover. Further, since ER and mitochondria function in close association through ER membrane contact sites, it is likely that lysosomal modulation also brings about associated changes in mitochondria. In this regard, we found that chloroquine reduces mitochondrial membrane potential and mitochondrial dynamics. Collectively, the differential biosynthetic response of rise in lipid content, but not protein content, cannot be accounted by merely considering that chloroquine induced suppression of autophagy causes defects in organelle function. In this defective autophagy scenario, both biosynthetic responses such as lipid and protein synthesis are expected to be reduced rather than only the latter, as observed with chloroquine. These findings suggest that cholesterol trafficking/distribution within cellular organelles could act as an intracellular mediator of differential biosynthetic remodelling in interconnected organelles.

Ginkgolide B alleviates oxidative stress and ferroptosis by inhibiting GPX4 ubiquitination to improve diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end‑stage renal disease. Although Ginkgo biloba extract has a protective effect on DN, the protective effect and mechanism of its active ingredient Ginkgolide B (GB) on DN remain unclear. The aim of the present study was to investigate whether GB improves DN via alleviating oxidative stress and ferroptosis by inhibiting GPX4 ubiquitination in PA-G-induced mouse podocytes and DN mice. The study in vitro showed that GB effectively reduced serum total cholesterol, triglyceride concentrations and lipid accumulation in PA-G-induced MPC5 cells. In addition, GB promoted the expression of ferroptosis markers GPX4 and FTH1, while inhibited the expression of TfR1, fibrosis markers α-SMA and Collagen α1, as well as intracellular iron content and ROS levels. Interference of GPX4 expression with siRNA counteracted the effect of GB. And GB inhibited GPX4 ubiquitination in a dose-dependent manner. In vivo the experimental results showed that GB effectively reduced hyperglycemia, serum total cholesterol and triglyceride concentrations, reduced urinary albumin excretion and the number of renal lipid droplets, and improved changes in renal structure in DN mice. GB inhibited the expression of ferroptosis marker TfR1 and fibrosis markers α-SMA and Collagen α1, while promoted the expression of ferroptosis markers GPX4 and FTH1. In conclusion, the results suggested that GB may improve DN via protecting the kidney from ferroptosis and oxidative stress damage by inhibiting the ubiquitination of GPX4. These findings suggested that GB, a natural medicine, may be an effective therapeutic option for DN.

English

The objective of this work was to analyze the growth of Scenedesmus acutus, Nannochloropsis oculata and Chlorella vulgaris at different temperatures (25, 30 and 38&deg;C) in order to identify changes in lipid content, accumulation of neutral lipids and fatty acids profile. According to the results obtained, the temperature of 30&deg;C does not affect the growth of the microalgae S. acutus, N. oculata and C. vulgaris; however, there is a greater amount of total lipids in S. acutus at 38&deg;C, while for N. oculata and C. vulgaris, temperature variation does not affect the accumulation of total lipids. From the data obtained from the fatty acid profile, we observed a greater accumulation of palmitic acid followed by oleic acid. According to the cetane number, any temperature condition of any evaluated microalgae culture can be used for biodiesel production. The results suggest that a change in temperature during the growth of microalgae could be applied to enhance lipid production and to obtain fatty acids suitable for biodiesel production.&nbsp; &nbsp; Key words: Chlorella vulgaris, Nannochloropsis oculata, Scenedesmus acutus, fatty acids, lipids, temperature.