High Lipid Accumulation Research Articles

Multi-Factorial-Guided Media Optimization for Enhanced Biomass and Lipid Formation by the Oleaginous Yeast Cutaneotrichosporon oleaginosus.

The non-conventional, oleaginous yeast Cutaneotrichosporon oleaginosus is flagged as an industrial cell factory for generation of oleochemicals and biofuels due to its substrate flexibility and high triglyceride yields. In this study, we employed a computational Response Surface Methodology to guide and streamline the experimental media optimization matrix with 12 nitrogen and 10 carbon sources in order to provide for high biomass and lipid accumulation toward an industrially relevant fermentation process. The resulting data provide new insights into C. oleaginosus physiology under variable nutritional states. Accordingly, the lipid content % (lipid weight/yeast dry weight) is controlled by a defined interplay between carbon and nitrogen. In our experimental setup, the highest biomass (18.4 ± 2.20 g/L) and lipid yield (9 ± 0.34 g/L; 49.74 ± 5.16% g lipid weight/g yeast dry cell weight) were obtained with lactose and yeast extract as carbon and nitrogen sources at an elemental weight ratio of 120:1, respectively. Interestingly, with ammonium salts as a N-source, the intracellularly accumulated triglycerides increasingly contain saturated fatty acids, which provides a new route to generate tailored fatty acid profiles for specific oleochemicals or food applications. Our data indicate that a metabolic ceiling for lipid accumulation in C. oleaginosus is obtained with the correct carbon and nitrogen source mixture.

Optimization of culture conditions for biodiesel production from Egyptian isolate Penicillium commune NRC2016

BackgroundBiodiesel is a type of renewable energy, an ideal substitute for petroleum diesel fuel. The present study concerns about optimization of culture conditions for biodiesel production by Penicillium commune NRC2016.ResultsThe maximum lipid production from P. commune NRC2016 was investigated using basal liquid medium with initial pH 7.0, incubation temperature 20 °C, and after 5 days of incubation time at static condition. Six types of agro-industrial by-products (broken rice, rice straw, wheat bran, corn stalk, sweet sorghum, and bagasse) were separately used as components of semi-solid fermentation media. The highest lipid accumulation was recorded with sweet sorghum 99.1 mg/g as compared with the other by-products. Biodiesel obtained from P. commune NRC2016 was blended “B5” and the physical properties were determined and found to be as follows: density 0.8 g/ml, viscosity 2.1 mm2/s, flash point 77.0 °C, cloud point − 1.5 °C, iodine value 42.3 g I2/100 g, acid value 2.1 mg/g, pour point − 1.7 °C, and cetane number 47.8 min.ConclusionsThis work revealed the optimization of culture conditions for biodiesel production from Egyptian fungal strain P. commune NRC2016.

Production of Oleaginous Organisms or Lipids Using Sewage Water and Industrial Wastewater.

Worldwide, wastewater produced from sewage and industry poses a serious risk to the surrounding environment. As a way to address this problem, an integrated approach for cultivation of oleaginous microorganisms on wastewater leading to effective removal of hazardous components and sustainable production of biodiesel is proposed. Oleaginous yeasts have the unique ability to utilize wastewater as feedstock and accumulate large amounts of triacylglycerols within their cellular compartments at stationary phase (144h). The lipids stored in an oleaginous microbe can be visualized by fluorescence microscopy and converted into biodiesel through transesterification after extraction. Here, we describe the batch cultivation of oleaginous yeast on sewage and industrial wastewater at 25°C. High lipid accumulation with efficient removal of toxic chemicals can be achieved by utilizing this integrated method.

Activated TNF-α/RIPK3 signaling is involved in prolonged high fat diet-stimulated hepatic inflammation and lipid accumulation: inhibition by dietary fisetin intervention.

Increasing evidence indicates that high-fat diet (HFD) is a predisposing factor for metabolic syndrome-associated systemic inflammation and nonalcoholic fatty liver disease (NAFLD). Tumor necrosis factor-α/receptor-interacting protein kinase 3 (TNF-α/RIPK3) axis has recently become regarded as an important regulator and contributor in many inflammation-related diseases. Fisetin (Fn) is a bioactive flavonoid polyphenol with anti-inflammatory and anti-tumor activity. Lately it has gained increasing attention due to its potential advantages in prevention of tumors, metabolic disorders, neuroinflammation and chronic liver injury. However, its role in NAFLD is still not fully understood. Thus, we studied whether prolonged HFD causes TNF-α/RIPK3 activation-associated hepatic steatosis, further evaluating the protective effects of Fn in HFD-fed mice. As expected, HFD promotes metabolic syndrome and pro-inflammatory cytokine generation in serum, enhances liver inflammatory infiltration-related lipid accumulation by increase of TNF-α/RIPK3 activation, ultimately resulting in development of nonalcoholic steatohepatitis. In contrast to this, dietary Fn intervention could suppress metabolic disorder and HFD-triggered hepatic function loss, downregulate TNF-α/RIPK3 signaling-associated hepatic inflammation, balance lipid metabolism-related gene expression, and finally inhibit lipid accumulation and steatohepatitis. Hence, Fn restrains HFD-induced hepatic inflammation and lipid deposition by downregulating metabolic disorder and excessive liver inflammation-associated TNF-α/RIPK3 axis activation.

Identification of optimum stage of fruit harvesting for higher lipid accumulation in fruits and kernels of Jatropha curcas L. for bio-fuel production

Identification of optimum stage of fruit harvesting for higher lipid accumulation in fruits and kernels of Jatropha curcas L. for bio-fuel production

Screening and optimization of some Egyptian soil-born fungi for lipids production as possible source for biofuel

Depletion of fossil fuel is the largest challenge facing human industrial and technological revolution in the current era. Exploration of widely distributed microorganisms for the production of renewable biofuel is the most priority for scientific research in the last decades. In this context, thirteen fungal isolates were collected from Tanta city, El-Gharbia Governorate, Egypt belonging to four genera (Aspergillus, Penicillium, Fusarium and Alternaria) were screened on minimal media for their ability to accumulate lipid in their biomass. The maximum lipid contents were 25.31% for Aspergillus versicolor and 20.15% for Aspergillus niveus. The optimization result showed that pH 4, incubation temperature 32°C, sucrose at concentration of 40g/L, glutamic acid at concentration of 0.5 g/L (C/N ratio at 40:0.5 w/w) after 5 days of incubation with agitation rate of 150 rpm on orbital shaker were the most appropriate conditions for the highest lipid accumulation in the case of Aspergillus versicolor. However, in case of Aspergillus niveus, pH 4, incubation temperature at 32°C, sucrose at concentration of 20 g/L, NaNO3 at concentration of 1.0 g/L (C/N ratio at 20:1.0 w/w) after 11 days of incubation with agitation rate of 150 rpm were the most appropriate for the highest lipid accumulation.

Fisetin attenuates high fat diet-triggered hepatic lipid accumulation: A mechanism involving liver inflammation overload associated TACE/TNF-α pathway

Excess fat-rich diet ingestion predisposes the liver to non-alcoholic fatty liver disease (NAFLD), but the mechanism is complicated. Fisetin (Fn) as a natural flavonoid with many bio-activities was determined in a number of diseases models. TACE (tumor necrosis factor-α-converting enzyme)-combined tumor necrosis factor-α (TACE/TNF-α) signaling played a significant role in inflammation-associated diseases. The study aimed to explore the protective mechanisms of Fn against high fat diet (HFD)-induced nonalcoholic steatohepatitis (NASH), with particular focus on TACE/TNF-α signaling. HFD-fed C57BL/6 mice were used as the metabolic syndrome model to explore the effects of Fn on NASH and to determine whether TACE/TNF-α activation was involved in the process. Indeed, HFD increases systemic metabolic disorder, promotes circulating levels of pro-inflammatory cytokines produce, aggravates development of hepatic inflammation, resulting in inflammation overload-associated excessive activation of TACE/TNF-α, ultimately induces hepatic lipid accumulation and NASH. Fisetin protected against HFD-induced liver inflammation and lipid accumulation by decreasing metabolic disorder and inflammation overload-related TACE/TNF-α activation, inhibiting over-expression of pro-inflammatory cytokines, negatively regulating HFD-triggered abnormal lipid metabolism-related genes expression, finally restricting lipid deposition and hepatic steatosis. Fisetin suppressed HFD-induced liver inflammation and lipid accumulation by decreasing metabolic disorder and hepatic inflammation overload-related TACE/TNF-α activation.

Elucidating the unique physiological responses of halotolerant Scenedesmus sp. cultivated in sea water for biofuel production

Utilization of saline or sea water for large-scale cultivation of microalgae can potentially provide a leap towards the reduction of both cost and sustainability challenges for biofuel production. The present investigation evaluated the temporal changes in carbohydrates and fatty acids of a halotolerant microalga Scenedesmus sp. IITRIND2 grown in natural seawater salinity to delineate the differential physiological response towards salt stress and subsequent potential for biofuel production. The microalga showed remarkable ability to tolerate different salinity environments under given temperature and light conditions. Such tolerance was attributed to the increase in neutral sugars, such as glucose, mannose, galactose, fucose and ribose, associated with both structural and storage (and potentially osmoprotectant) polymeric carbohydrates. The carbohydrate rearrangements may aid in the remodeling of cellular components to circumvent the detrimental effects of high salinity. The observed high carbohydrate and lipid accumulation in this microalga signifies its potential for integrated bioethanol and biodiesel production. This work provides a basic understanding towards high salinity adaption of Scenedesmus sp. IITRIND2, which could further be explored for identifying targets for halotolerance in other microalgal strains.

Screening for Lipomyces strains with high ability to accumulate lipids from renewable resources.

The yeast Lipomyces accumulates triacylglycerols (TAGs) as intracellular fat globules, and these TAGs can be used as source materials for biodiesel production. In this study, we aimed to use this yeast to produce lipids from renewable resources. Using plate culture and micrograph methods, strains with a high lipid-accumulation ability were screened from 15,408 types of systems combining renewable resources, strains, and culture temperatures. The lipid-accumulation ability of the strains was estimated from the fat globule volume, which was calculated using a micrograph. The reliability of this method was examined, and strains with a high lipid-accumulation ability were identified for each renewable resource. Seventy-seven Lipomyces strains (7 deposit, 68 wild-type, 2 mutants) with a high lipid-accumulation ability were selected. A few strains possessed the ability to accumulate large amounts of TAGs from more than four different renewable resources. We found that strains with a high lipid-accumulation ability could efficiently convert consumed carbon sources into TAGs, which could be easily recovered from the fat globules of these strains through physical disruption.

Changes in biochemical composition and fatty acid accumulation of Nannochloropsis oculata in response to different iron concentrations

In this research, standard growth medium of Nannochloropsis oculata was manipulated with 5-, 10-, 15- and 20-fold increased (15.8, 31.6, 47 and 63 mg/L) and decreased (0.63, 0.316, 0.21, and 0.15 mg/L) chelated FeCl3. The standard medium (control group) contained 3.16 mg/L FeCl3. The results revealed that the highest iron concentration (63 mg/L) partially restricted photosynthetic efficiency (0.67 µg/L). Also, increasing in Fe concentration from 3.16 (control) to 63 mg/L led to significant increase in the total carotenoid contents. The highest lipid accumulation was measured in the cultured algae at 0.15 mg/L FeCl3 (p < 0.05). The highest C16:0 and C18:2 fatty acids values were obtained at 0.316 and 0.15 mg/L Fe concentrations, respectively. C18:1 and C18:3 fatty acid had the maximum value in the media at 0.21 and 0.15 mg/L Fe-depletion (p < 0.05). Moreover, the C20:5 (EPA) had the highest value (24.21%) at 0.63 mg/L FeCl3. The highest and lowest triacylglycerol values were obtained in 0.316 and 63 mg/L FeCl3. These results suggest that Fe limitation in N. oculata growth media with 10- and 20-fold decrease (0.316 and 0.15 mg/L) was the most effective in improving lipid and fatty acid accumulation.

Maternal cinnamon intake during lactation led to visceral obesity and hepatic metabolic dysfunction in the adult male offspring.

Studies with foods, known to promote health benefits in addition to the nutritive value, show that their consumption by pregnant and/or lactating females could induce negative outcomes to the offspring. It is well characterized that cinnamon intake promotes benefits to energy homeostasis. The present study aimed to analyze the effects of the consumption of an aqueous extract of cinnamon by lactating female rats on the endocrine-metabolic outcomes in the adult offspring. Lactating dams (Wistar rats) were supplemented with cinnamon aqueous extract (400 mg/kg body weight/day) for the entire lactating period. The male adult offspring were evaluated at 180 days old (CinLac). The offspring presented visceral obesity (P = 0.001), hyperleptinemia (P = 0.002), and hyperinsulinemia (P = 0.016). In the liver, CinLac exhibited reduced p-IRβ (P = 0.018) suggesting insulin resistance. However, phosphorylation of IRS1 (P = 0.041) and AKT (P = 0.050) were increased. JAK2 (P = 0.030) and p-STAT3 (P = 0.015) expressions were higher, suggesting that the activation of IRS1/AKT in the CinLac group could have resulted from the increased activation of leptin signaling. Although we observed no changes in the gluconeogenic pathway, the CinLac group exhibited lower hepatic glycogen content (P = 0.005) accompanied by increased p-GSK3β (P = 0.011). In addition, the CinLac group showed increased hepatic triacylglycerol content (P = 0.049) and a mild steatosis (P = 0.001), accompanied by reduced PPARα mRNA expression (P = 0.005). We conclude that maternal intake of aqueous extract of cinnamon induces long-term molecular, metabolic, and hormonal changes in the adult progeny, including visceral obesity, higher lipid accumulation, and lower glycogen content in the liver.

Bioremediation of chromium contaminated water by diatoms with concomitant lipid accumulation for biofuel production

Hexavalent chromium compounds such as chromate and dichromate, commonly designated as Cr (VI) compounds, are widely used heavy metals in different industries and are considered highly toxic to most life forms. Unfortunately, they have become a major pollutant of groundwater and rivers around dichromate using industries. Bioremediation is widely used to decrease the amount of dichromate in wastewater but requires large amounts of precious fresh water. Here we tested two marine micro-algal species, Phaeodactylum tricornutum strain CCY0033 and Navicula pelliculosa strain CCMP543, for their ability of dichromate bioremediation and concomitantly producing lipids that can serve as biofuel. Dichromate tolerance of the strains was investigated under different growth conditions in order to obtain high biomass yields, high lipid accumulation and high dichromate removal from the medium. Both algal strains grew well and produced high biomass in media containing up to 1 mg of dichromate per liter. Variations in growth conditions revealed that dichromate removal from the medium correlated positively with biomass yield. Dichromate removal using living cells was in the same order of magnitude as with autoclaved dead cells or when using extracted extracellular polymeric substances (EPS). This suggests biosorption of dichromate to cell-associated polymeric substances as the major mechanism of the bioremediation process. For both strains, optimal dichromate removal and lipid production were achieved at a light intensity of 55 μmol m−2s−1 and at a sodium nitrate concentration of 3 mM. The optimal temperature for dichromate removal and lipid production was 23 °C for P. tricornutum and 27 °C for N. pelliculosa. Compared to P. tricornutum strain CCY0033, N. pelliculosa strain CCMP543 produced an overall higher lipid yield under these conditions.

Dill-normalized liver lipid accumulation, oxidative stress, and low-density lipoprotein receptor levels in high cholesterol fed hamsters.

BACKGROUNDHigh lipid accumulation in hepatocyte and blood vessels can lead to non-alcoholic fatty liver disease (NAFLD) and heart diseases, respectively. These disorders are the main reasons of mortality in various countries. In this experiment, we evaluated the effect of leaf extracts of Anethum graveolens (AG), also known as Dill, and AG tablet on expression of low-density lipoprotein receptor (LDLR) and liver lipid in hypercholesterolemic hamsters.METHODSIn this experimental study, 36 male golden hamsters were divided into 6 groups: 1) standard diet + 0.5% cholic acid + 2% cholesterol [high cholesterol diet (HCD)], 2) HCD + 100 mg/kg hydroalcoholic extract of Dill, 3) HCD + 200 mg/kg hydroalcoholic extract of Dill, 4) HCD + 100 mg/kg Dill tablet, 5) HCD + 200 mg/kg Dill tablet, 6) chow. At the end of study (30th day), hamsters were anesthetized and blood sample and liver tissue were collected. Biochemical factors and antioxidant parameters were determined. LDLR messenger ribonucleic acid (mRNA) level was measured using real time polymerase chain reaction (RT-PCR). Histopathological change of liver was determined using light microscope.RESULTSCompared to HCD group, blood lipids (P < 0.0010) and liver enzymes (P < 0.0010) markedly reduced in AG-treated groups. The expression of LDLR did not change significantly in animals which received low dose of hydroalcoholic extract or AG tablet, but it increased in animals receiving high dose of extract or tablet (P < 0.0100). Liver antioxidant significantly increased by AG (P < 0.0010). Liver histopathological changes were normalized by AG.CONCLUSIONAG can significantly increase LDLR gene expression in HCD animals. This study showed that both AG extract and AG tablet had potential antioxidant and hypolipidemic effects in hamsters.

Enhancement of lipid production from algal biomass through various growth parameters

Algal lipids are prospective sustainable and economic resources for biodiesel. In this study, growth parameters i.e. lipid, biomass, and total chlorophyll contents of the two algal consortia S1 and S16 were optimized at varied pH microenvironment, different nutrient media and NaNO3 concentrations. Results obtained from the present study revealed that optimum growth of the consortia S1 in terms of lipid, biomass, and total chlorophyll was observed at pH 7 while for S16 it was at pH 8. Optimum protein contents for S1 and S16 were obtained at pH 6 and 5, respectively. For both the consortia, BG-11 was found to be the best-suited medium for biomass, total chlorophyll and protein contents, whereas the highest lipid accumulation was favored by the Bold Basal Medium. The present study demonstrated that nitrogen deprivation in the medium would favor high lipid accumulation. About 1.0 g L−1 of sodium nitrate (NaNO3) was found to be suitable for enhancing the biomass yield and total chlorophyll while the concentration required for optimum lipid and protein content was observed to be 10 folds lower at 0.1 g L−1. Consequently, under nitrate stress, the lipid content of S1 was observed to increase by 55.5% as compared to control. Surface morphology of algal cells was explored with the help of Scanning Electron Microscopy (SEM) under normal as well as stress conditions (0.1 g L−1 NaNO3). Nitrate stress was found to exert significant effects on cell morphologies of both the algal consortia. Fourier Transform Infrared (FTIR) spectra of both the consortia revealed the presence of various functional groups corresponding to lipid, carbohydrate, and protein under normal and stress conditions.

Enhanced Lipid Production in Chlamydomonas reinhardtii by Co-culturing With Azotobacter chroococcum.

The green algae, Chlamydomonas reinhardtii, is one of the model species used to study lipid production, although research has focused on nitrogen-deficient cultures, that inhibit the development of biomass by C. reinhardtii and limit lipid production. In this study, Azotobacter chroococcum was added to the algal culture to improve lipid accumulation and productivity of C. reinhardtii. The maximum lipid content and production of C. reinhardtii in the co-culture were 65.85% and 387.76 mg/L, respectively, which were 2.3 and 5.9 times the control's levels of 29.11% and 65.99 mg/L, respectively. The maximum lipid productivity of C. reinhardtii in the co-culture was 141.86 mg/(L·day), which was 19.4 times the control's levels of 7.33 mg/(L·day). These increases were attributed to the enhanced growth and biomass and the change in the activity of enzymes related to lipid regulation (ACCase, DGAT, and PDAT). Compared to the conventional strategy of nitrogen deprivation, A. chroococcum added to the culture of C. reinhardtii resulted in higher lipid accumulation and activity, greater efficiency in the conversion of proteins to lipids, higher biomass, and increased growth of C. reinhardtii. Therefore, using A. chroococcum to improve the growth and biomass of C. reinhardtii is an efficient, rapid, and economically viable strategy for enhancing lipid production in C. reinhardtii.

Engineering lipid droplet assembly mechanisms for improved triacylglycerol accumulation in Saccharomyces cerevisiae

Production of triacylglycerols (TAGs) through microbial fermentation is an emerging alternative to plant and animal-derived sources. The yeast Saccharomyces cerevisiae is a preferred organism for industrial use but has natively a very poor capacity of TAG production and storage. Here, we engineered S. cerevisiae for accumulation of high TAG levels through the use of structural and physiological factors that influence assembly and biogenesis of lipid droplets. First, human and fungal perilipin genes were expressed, increasing TAG content by up to 36% when expressing the human perilipin gene PLIN3. Secondly, expression of the FIT2 homologue YFT2 resulted in a 26% increase in TAG content. Lastly, the genes ERD1 and PMR1 were deleted in order to induce an endoplasmic reticulum stress response and stimulate lipid droplet formation, increasing TAG content by 72% for Δerd1. These new approaches were implemented in previously engineered strains that carry high flux of fatty acid biosynthesis and conversion of acyl-CoA into TAGs, resulting in improvements of up to 138% over those high-producing strains without any substantial growth effects or abnormal cell morphology. We find that these approaches not only represent a significant improvement of S. cerevisiae for TAG production, but also highlight the importance of lipid droplet dynamics for high lipid accumulation in yeast.

Ganoderic Acid A improves high fat diet-induced obesity, lipid accumulation and insulin sensitivity through regulating SREBP pathway

Obesity and its major co-morbidity, type 2 diabetes, have been an alarming epidemic prevalence without an effective treatment available. Sterol regulatory element-binding proteins (SREBPs) are major transcription factors regulating the expression of genes involved in biosynthesis of cholesterol, fatty acid and triglyceride. Therefore, inhibition of SREBP pathway may be a useful strategy to treat obesity with type 2 diabetes. Here, we identify a small molecule, Ganoderic Acid A (GAA), inhibits the SREBP expression and decreases the cellular levels of cholesterol and fatty acid in vitro. GAA also ameliorates body weight gain and fat accumulation in liver or adipose tissues, and improves serum lipid levels and insulin sensitivity in high fat diet (HFD)-induced obese mice. Consistently, GAA regulates SREBPs target genes and metabolism associated genes in liver or adipose tissues, which may directly contribute to the lower lipid level and improvement of insulin resistance. Taken together, GAA could be a potential leading compound for development of drugs for the prevention of obesity and insulin resistance.

Selection of oleaginous yeasts capable of high lipid accumulation during challenges from inhibitory chemical compounds

A two-stage selection process was applied to eight oleaginous yeast strains from the Lipomyces genera. In the primary selection stage, a nitrogen-limited mineral medium (-NMM) that contained a mixture of glucose and xylose as a carbon source was used to evaluate the lipid-accumulating abilities of the yeast strains. The strains L. doorenjongii, L. orientalis, and L. starkeyi were selected as the potential strains in the primary selection. These three strains exhibited a remarkable ability to simultaneously assimilate glucose and xylose and achieved a cell biomass of more than 30 g/L. The values for lipid content in the selected strains were 57.89 ± 1.92, 56.38 ± 1.93, and 77.14 ± 1.55% for L. doorenjongii, L. orientalis, and L. starkeyi, respectively. In the secondary selection, when the -NMM medium contained an inhibitory chemical compound (ICC), the selected strains showed a different tolerance level against each of the typical inhibitor compounds. However, L. starkeyi accumulated the highest lipid content and yield at 68.24 ± 2.48% and 0.19 ± 0.00 (w/w), respectively. L. starkeyi accumulated high levels of intracellular lipid and tolerated the ICC. The composition of fatty acid methyl esters (FAMEs) was unaltered by the presence of ICC and the major FAMEs consisted of oleic, palmitic, stearic, palmitoleic and linoleic acids.

Phytochemicals-induced hormesis protects Caenorhabditis elegans against α-synuclein protein aggregation and stress through modulating HSF-1 and SKN-1/Nrf2 signaling pathways

Mild stress activates the adaptive cellular response for the subsequent severe stress called hormesis. Hormetic stress plays a vital role to activate multiple stress-responsive genes for the benefit of an organism. In tropical regions of world, tubers of Dioscorea spp. has been extensively used in folk medicine and also consumed as food. In this study, we report that the phytochemicals of Dioscorea alata L., tubers extends the lifespan of nematode model Caenorhabditis elegans by hormetic mechanism. We showed that the low dose of tubers extract at 200 and 300 μg/mL extends the mean lifespan of wild-type worms, whereas higher doses are found to be toxic. Supplementation of tubers extract slightly increased the intracellular ROS in second-day adult worms and it might activate the adaptive stress response, which protects the worms from oxidative and thermal stress. Transgenic reporter gene expression assay showed that extract treatment enhanced the expression of stress protective genes such as hsp-16.2, hsp-6, hsp-60 and gst-4. Further studies proved that the transcription factors HSF-1 and SKN-1/Nrf2 were implicated in hormetic stress response of the worms. Moreover, pretreatment of extract reduced the high glucose-mediated lipid accumulation by enhancing the expression of glyoxalase-1. It was also found that the aggregation of Parkinson’s related protein α-synuclein reduced in the transgenic strain NL5901 and extended its lifespan. Finally, our results concluded that the presences of hormetic dietary phytochemicals in tubers might drive the stress response in C. elegans via HSF-1 and SKN-1/Nrf2 signaling pathways.

The Role of Diacylglycerol Acyltransferase (DGAT) 1 and 2 in Cardiac Metabolism and Function

It is increasingly recognized that synthesis and turnover of cardiac triglyceride (TG) play a pivotal role in the regulation of lipid metabolism and function of the heart. The last step in TG synthesis is catalyzed by diacylglycerol:acyltransferase (DGAT) which esterifies the diacylglycerol with a fatty acid. Mammalian heart has two DGAT isoforms, DGAT1 and DGAT2, yet their roles in cardiac metabolism and function remain poorly defined. Here, we show that inactivation of DGAT1 or DGAT2 in adult mouse heart results in a moderate suppression of TG synthesis and turnover. Partial inhibition of DGAT activity increases cardiac fatty acid oxidation without affecting PPARα signaling, myocardial energetics or contractile function. Moreover, coinhibition of DGAT1/2 in the heart abrogates TG turnover and protects the heart against high fat diet-induced lipid accumulation with no adverse effects on basal or dobutamine-stimulated cardiac function. Thus, the two DGAT isoforms in the heart have partially redundant function, and pharmacological inhibition of one DGAT isoform is well tolerated in adult hearts.