High Lipid Accumulation Research Articles

Analysis and model delineation of marine microalgae growth and lipid accumulation in flat-plate photobioreactor

A quantitative description of its growth and the “trade-off” between biomass production and lipid accumulation will provide a kinetic insight of the dependency of biomass and components on growth conditions and the interplays between lipid/protein production and N-limitation. The examination of the dependency of Isochrysis galbana growth on initial concentration of sodium nitrate (NaNO3) in a flat-plate photobioreactor (FPPBR) revealed that the maximal lipid 106mgL−1 is produced at 25mgL−1 NaNO3 and whereas the accumulation of biomass, protein and starch increases as NaNO3 increases to 100mgL−1. The analysis and model fitting results indicate that I. galbana growth and production of lipids in a FPPBR can be quantitatively described by Baranyi-Roberts & logistic equation, and Luedeking-Piret model in a satisfactory manner, respectively. 25–75mgL−1 was found to be proper level of NaNO3 to achieve a good trade-off balance to produce both high quantities of biomass and lipids. Based on the predictions of growth model, after culturing middle stationary phase under the high nitrogen medium, switching of culture for algal cells to a nitrogen-free medium and/or high illumination intensity might be preferable strategy to achieve high level accumulation of lipids.

Lipid quantification techniques for screening oleaginous species of microalgae for biofuel production

This review examines the available literature on quantifying lipids in microalgae suitable for biofuels research. It discusses their advantages and disadvantages, their prevalence in the literature, and draws conclusions about the best way to approach choosing a suitable lipid measurement technique for microalgal biofuels research. We conclude that the method must be chosen based on the following key criteria: (1) the level of detail required in the results, and (2) the amount of biomass that can be spared for the assay. This review establishes that no method can be used as a “golden standard” for all microalgae. However, we present a systematic decision chart to choose the best measurement method or combination of methods to provide a guide to those wishing to understand the differences between the myriad of lipid measurement techniques.Practical applications: This review will allow researchers new to the field to choose the most appropriate techniques for quantifying lipids in the microalgal species under study. The review is also intended to act as a gateway to the wider literature and will enable researchers to look in depth at a particular technique before carrying out experimental work.These two figures show contrasting results obtained from one set of samples using esterification with GC (left hand figure), and Nile Red staining with fluorescence measurement (right hand figure). The Nile Red method indicates a high accumulation of lipids over time in 0.3 M NaCl, whereas the GC method indicates the opposite pattern of decreasing FAME content over time in the high salt conditions (green line in each figure). The contrasting results highlight the problem of accuracy in lipid measurement, and how it is possible to be misled if only one experimental technique is used.

Hydraulic retention time effects on wastewater nutrient removal and bioproduct production via rotating algal biofilm reactor

Rotating algal biofilm reactor (RABR) technology was successfully employed in an effective strategy to couple the removal of wastewater nutrients with accumulation of valuable bioproducts by grown algae. A secondary stage municipal wastewater was fed to the developed system and the effects of the hydraulic retention time (HRT) parameter on both nutrient removal and bioproduct production were evaluated under fed-batch operation mode. Two sets of bench scale RABRs were designed and operated with HRTs of 2 and 6days in order to provide competitive environment for algal growth. The HRT significantly affected nitrogen and phosphorus uptakes along with lipid and starch accumulations by microalgae in harvested biofilms. Domination of nitrogen removal in 2-day HRT with higher lipid accumulation (20% on dried weight basis) and phosphorus removal in 6-day HRT with higher starch production (27% on dried weight basis) was observed by comparing the performances of the RABRs in duplicate runs.

Interleukin-15-mediated inflammation promotes non-alcoholic fatty liver disease

Interleukin-15 (IL-15) is essential for the homeostasis of lymphoid cells particularly memory CD8+ T cells and NK cells. These cells are abundant in the liver, and are implicated in obesity-associated pathogenic processes. Here we characterized obesity-associated metabolic and cellular changes in the liver of mice lacking IL-15 or IL-15Rα. High fat diet-induced accumulation of lipids was diminished in the livers of mice deficient for IL-15 or IL-15Rα. Expression of enzymes involved in the transport of lipids in the liver showed modest differences. More strikingly, the liver tissues of IL15-KO and IL15Rα-KO mice showed decreased expression of chemokines CCl2, CCL5 and CXCL10 and reduced infiltration of mononuclear cells. In vitro, IL-15 stimulation induced chemokine gene expression in wildtype hepatocytes, but not in IL15Rα-deficient hepatocytes. Our results show that IL-15 is implicated in the high fat diet-induced lipid accumulation and inflammation in the liver, leading to fatty liver disease.

Docosahexaenoic Acid Ameliorates Fructose-Induced Hepatic Steatosis Involving ER Stress Response in Primary Mouse Hepatocytes.

The increase in fructose consumption is considered to be a risk factor for developing nonalcoholic fatty liver disease (NAFLD). We investigated the effects of docosahexaenoic acid (DHA) on hepatic lipid metabolism in fructose-treated primary mouse hepatocytes, and the changes of Endoplasmic reticulum (ER) stress pathways in response to DHA treatment. The hepatocytes were treated with fructose, DHA, fructose plus DHA, tunicamycin (TM) or fructose plus 4-phenylbutyric acid (PBA) for 24 h. Intracellular triglyceride (TG) accumulation was assessed by Oil Red O staining. The mRNA expression levels and protein levels related to lipid metabolism and ER stress response were determined by real-time PCR and Western blot. Fructose treatment led to obvious TG accumulation in primary hepatocytes through increasing expression of fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC), two key enzymes in hepatic de novo lipogenesis. DHA ameliorates fructose-induced TG accumulation by upregulating the expression of carnitine palmitoyltransferase 1A (CPT-1α) and acyl-CoA oxidase 1 (ACOX1). DHA treatment or pretreatment with the ER stress inhibitor PBA significantly decreased TG accumulation and reduced the expression of glucose-regulated protein 78 (GRP78), total inositol-requiring kinase 1 (IRE1α) and p-IRE1α. The present results suggest that DHA protects against high fructose-induced hepatocellular lipid accumulation. The current findings also suggest that alleviating the ER stress response seems to play a role in the prevention of fructose-induced hepatic steatosis by DHA.

Characterization of the growth, chlorophyll content and lipid accumulation in a marine microalgae Dunaliella tertiolecta under different nitrogen to phosphorus ratios

Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production. In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth, chlorophyll content and accumulation of lipids in Dunaliella tertiolecta, experiments were carried out in modified microalgal medium with inorganic nitrogen (nitrate-nitrogen) or organic nitrogen (urea-nitrogen) as the sole nitrogen source at initial N:P ratios ranging from 1:1 to 32:1. The favorable N:P of 16:1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate. Decrease in chlorophyll content were observed at the N:P of 4:1 in both nitrate-N and urea-N cultures. It was also observed that the maximum lipids concentration was obtained at the N:P of 4:1 in both nitrate and urea nutrient medium. The lipid productivity and lipid content of cultures in the urea-N medium at the N:P of 4:1were markedly higher than those from cultures with other N:P ratios (p < 0.05). The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D. tertiolecta. Conversely, higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitrogen to phosphorus. The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumulation in D. tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.

Multiple Roles of Curcumin Attenuate High Fat Diet- Induced Kidney Cortex Derangement

The urgency to develop renoprotective strategies sets the eyes in compounds as curcumin which prevents high fat diet-induced lipid accumulation and improves lipid profile in clinical studies. The present work aims to investigate the effect of curcumin on experimental nonalcoholic pattern kidney disease via histopathological, histochemical and immunohistochemical studies. Sixty Wister male rats weighing approximately 100 -120 grams were divided into 4 groups. Group I: 10 rats were served as control group and group II: 50 rats were received high fat diet for 12 weeks. Post histopathological confirmation of fatty kidney, this second group was subdivided into the following groups: Group III: 20 rats were injected intraperitoneally (I.P) with 1 /kg body weight dimethylsulfoxide (DMSO) day after day for 8 weeks. Group IV: 20 rats were injected I.P with 50 mg /kg body weight curcumin dissolved in DMSO, day after day for 8 weeks. The rest 10 rats in group II were sacrificed after 12 weeks from the beginning of experiment .Our histopathological results showed that renal structures of rats fed a high fat diet for 12 weeks had a dilatation in blood vessels and Bowman's space, mono nuclear cell infiltration, degeneration in nephrons and tubular defects. On the other hand rats treated with curcumin had nearly normal morphology of the kidney. Histochemical & immunohistochemical results showed decreased catalase (CAT) activity (96.08 ± 2.74) and decreased nuclear factor-kappa B (122.82 ± 5.44), endothelial nitric oxide synthase (eNOS) (128.23 ± 2.37) and inducible nitric oxide synthase (iNOS) (75.97 ± 6.29) in fatty rats improved after using curcumin (124.55 ± 18.82), (135.69 ± 6.39), (156.23 ± 4.94) and (95.39 ± 4.21) respectively. In conclusion, curcumin attenuates high fat diet induced kidney cortex derangement.

Application of high-content image analysis for quantitatively estimating lipid accumulation in oleaginous yeasts with potential for use in biodiesel production

Biodiesel from oleaginous microorganisms is a viable substitute for a fossil fuel. Current methods for microorganism lipid productivity evaluation do not analyze lipid dynamics in single cells. Here, we described a high-content image analysis (HCA) as a promising strategy for screening oleaginous microorganisms for biodiesel production, while generating single-cell lipid dynamics data in large cell density. Rhodotorula slooffiae yeast were grown in standard (CTL) or lipid trigger medium (LTM), and lipid droplet (LD) accumulation was analyzed in deconvolved confocal microscopy images of cells stained with the lipophilic fluorescent Nile red (NR) dye using automated cell and LD segmentation. The ‘vesicle segmentation’ method yielded valid morphometric results for limited lipid accumulation in smaller LDs (CTL samples) and for high lipid accumulation in larger LDs (LTM samples), and detected LD localization changes. Thus, HCA can be used to analyze the lipid accumulation patterns likely to be encountered in screens for biodiesel production.

90 LIPID CONTENT OF IN VIVO- AND IN VITRO-PRODUCED JERSEY AND HOLSTEIN CATTLE EMBRYOS AND THE EFFECT OF FORSKOLIN ON EMBRYO LIPID REDUCTION

Jersey embryos have been suggested to have higher lipid content and lower tolerance to cryopreservation. In addition, in vitro-produced (IVP) bovine embryos have darker cytoplasm as a consequence of higher lipid accumulation than in vivo-derived embryos, associated with impaired embryo quality and reduced cryotolerance. Forskolin is an adenylate cyclase activator that regulates cAMP levels in cells and has been shown to induce lipolysis in IVP embryos. We hypothesised that the lipid content of in vivo-produced and IVP Jersey embryos is higher than respective Holstein embryos and that forskolin would reduce lipid content of IVP embryos. The objectives of this experiment were (1) to analyse lipid content of in vivo and IVP Jersey and Holstein cattle embryos and (2) to evaluate the effect of forskolin added to IVP culture media. The factorial experimental design used two breeds (Holstein and Jersey) and three embryo production methods (in vivo, IVP, and IVP + forskolin). IVP embryos (n = 27 blastocysts) were collected from super-stimulated donors by routine procedures 7.5 days after AI. IVP embryos (n = 259 blastocysts) were produced by standard procedures; briefly, oocytes were aspirated from 2- to 8-mm follicles from slaughterhouse ovaries and matured for 24 h in SMM medium (BoviPro, MOFA Global, Verona, WI, USA). Matured oocytes were fertilized using semen from two different bulls for each breed, and embryos were cultured in BBH7 medium (BoviPro, MOFA Global) alone or with the addition of forskolin (10 µM) at Day 5 of culture at 38.5°C in 5% O2, 5% CO2, and 90% N2. The lipid content of embryos was quantified by staining Day 7 blastocysts with 1 μg mL–1 Nile red dye (580–596 nm), after which a digital photograph of the equatorial part of the embryo was taken at 40×, and fluorescence intensity (FI) was measured with Image Pro software. Data (Table 1) were analysed by ANOVA, and means were compared using Tukey’s HSD. Jersey and Holstein IVP embryos had higher lipid content than Holstein in vivo-produced embryos (P &lt; 0.05), but were not different than Jersey in vivo-derived embryos (P &gt; 0.1). Forskolin lowered the lipid content (P &lt; 0.05) of both IVP Jersey and Holstein embryos and was not different (P &gt; 0.1) than in vivo-produced embryos. Addition of forskolin to embryo culture media has the potential to lower embryo lipid accumulation and possibly improve embryo viability and cryotolerance of IVP embryos. Further studies including cryopreservation and transfer of IVP + forskolin embryos to recipients are necessary to corroborate the findings of the present study. Table 1.Fluorescence intensity of in vivo-produced and IVP Jersey and Holstein embryos

RETRACTED ARTICLE: An alternative high-throughput staining method for detection of neutral lipids in green microalgae for biodiesel applications

A simple and high-throughput method for determining in situ intracellular neutral lipid accumulation in Chlorella ellipsoidea and Chlorococcum infusionum with flow cytometry and confocal microscopy was established by employing different solvents and a lipophilic dye, Nile red. Seven different organic solvents, acetic acid, dimethyl sulfoxide (DMSO), acetone, methanol, ethanol, n-hexane, and chloroform at different concentrations ranging from 0 to 80% (v/v) were tested. The fluorescence signal for neutral lipids was collected with a 586/42 emission filter (PE-A) and the maximum fluorescence intensity (% grandparent) was measured as 74.01 ± 4.82% for Chlorella and 70.1 ± 5.52% for Chlorococcum at 30% acetic acid (v/v). The statistical analysis of Nile red-stained cells showed a high coefficient of variation (CV), standard deviation (SD), mean, and median values in the acetic acid-based staining method, followed by DMSO, n-hexane and chloroform. Confocal microscopy revealed a high rate of accumulation of cytosolic neutral lipids when stained with Nile red and other organic solvents. Higher lipid accumulation in Fesupplemented conditions was also detected and a maximum lipid content of 57.36 ± 0.41% (4-fold) in Chlorella and 48.20 ± 0.43% (4-fold) in Chlorococcum were measured at 0.001 g/L of ferrous sulfate (FeSO4). High fluorescence intensity (75.16 ± 0.24% in Chlorella and 72.24 ± 1.07% in Chlorococcum) in Fe-treated cells confirmed the efficiency of the staining procedure.

Complete Genome Sequence of a High Lipid-Producing Strain of Mucor circinelloides WJ11 and Comparative Genome Analysis with a Low Lipid-Producing Strain CBS 277.49.

The genome of a high lipid-producing fungus Mucor circinelloides WJ11 (36% w/w lipid, cell dry weight, CDW) was sequenced and compared with that of the low lipid-producing strain, CBS 277.49 (15% w/w lipid, CDW), which had been sequenced by Joint Genome Institute. The WJ11 genome assembly size was 35.4 Mb with a G+C content of 39.7%. The general features of WJ11 and CBS 277.49 indicated that they have close similarity at the level of gene order and gene identity. Whole genome alignments with MAUVE revealed the presence of numerous blocks of homologous regions and MUMmer analysis showed that the genomes of these two strains were mostly co-linear. The central carbon and lipid metabolism pathways of these two strains were reconstructed and the numbers of genes encoding the enzymes related to lipid accumulation were compared. Many unique genes coding for proteins involved in cell growth, carbohydrate metabolism and lipid metabolism were identified for each strain. In conclusion, our study on the genome sequence of WJ11 and the comparative genomic analysis between WJ11 and CBS 277.49 elucidated the general features of the genome and the potential mechanism of high lipid accumulation in strain WJ11 at the genomic level. The different numbers of genes and unique genes involved in lipid accumulation may play a role in the high oleaginicity of strain WJ11.

Life history traits influence in gonad composition of two sympatric species of flatfish

AbstractParalichthys orbignyanus and Paralichthys patagonicus are flatfish with different life history traits, having in common the condition of breeding in seawater. Paralichthys patagonicus remain their whole life in open seawater and Paralichthys orbignyanus are sometimes found in brackish water bodies. As marine and estuarine food webs have different fatty acid (FA) compositions, the aim of this study was to characterize the gonadal maturation of P. orbignyanus and P. patagonicus females through the analysis of lipid content and FA profile in order to understand to what extent life history traits are reflected in the ovarian composition. During gonadal maturation lipid content increased and FA profiles changed in both species, but the lipid increase was greater in P. orbignyanus. The N-3FA and n-3HUFA proportions increased in both species but were higher in P. orbignyanus. The differences between the lifestyles of these species were reflected in the ovarian FA profile mainly as a result of differences in their FA metabolism, causing a greater accumulation of n-3FA and n-3HUFA in P. orbignyanus than in P. patagonicus. The higher lipid accumulation in P. orbignyanus’ ovaries could indicate that this species, feeding in brackish water bodies, has the possibility of storing more energy than P. patagonicus.

PhotoBiobox: A tablet sized, low-cost, high throughput photobioreactor for microalgal screening and culture optimization for growth, lipid content and CO2 sequestration

Microbial screening and culture optimization is a laborious, multifaceted and expensive procedure often taking years and millions to identify the ideal strain for specific use. In this study, a high throughput, tablet-sized, low cost photobioreactor, herein referred as “PhotoBiobox”, was fabricated and tested for screening and culture optimization of microalgae suitable for biomass and biodiesel production, and CO2 sequestration. PhotoBiobox is equipped with a LED array and photo gradient filter offering different light intensities. PhotoBiobox was fabricated to screen and cultivate several microbial strains in 96-well plate in wide temperature range and CO2 atmosphere. To test its efficacy, a total of 12 microalgal strains were isolated from Korean freshwaters, identified and screened for high growth and lipid accumulation potential. Among the 12 strains, Parachlorella sp., JD076 showed highest growth rate, remarkable stability and tolerance to different temperature regimes. Optimization experiments using PhotoBiobox revealed that this strain had optimum temperature range and light intensity of 24–25°C and 400μmolm−2s−1, respectively, with high growth rate and lipid content in 5% CO2 condition. The screening and optimization of culture conditions using PhotoBiobox took just 15 days, in total, which could radically reduce both screening costs and time. PhotoBiobox can be used as a screening and optimization reactor in several areas of microbiology and cell biology, while serving as a prototype for furthering research on miniaturization in this field.

Alcohol-independent beneficial cardiometabolic profile of individuals with hyper-HDL cholesterolemia in Japanese men and women

There is limited information on characterization of individuals with hyper-high-density lipoprotein (HDL) cholesterolemia. The purpose of this study was to investigate the cardiometabolic profile of individuals with hyper-HDL cholesterolemia in comparison with the profile of individuals with normo-HDL cholesterolemia. The subjects were Japanese men and women who had hyper-HDL cholesterolemia (≥100 mg/dL) and their control subjects who had normal HDL cholesterol levels (≥40 and <80 mg/dL) and were matched for age or age and alcohol consumption. The cardiometabolic profiles were compared between the hyper- and normo-HDL cholesterolemic groups. Both in men and women, body mass index, waist-to-height ratio, triglycerides, low-density lipoprotein cholesterol, and hemoglobin A1c were significantly lower in subjects with hyper-HDL cholesterolemia than in subjects with normo-HDL cholesterolemia, whereas systolic and diastolic blood pressure levels were not significantly different between the 2 groups. In generalized estimating equation with adjustment for smoking and regular exercise, odds ratios of the hyper- vs normo-HDL cholesterolemic groups were significantly lower than the reference level of 1.00 for high body mass index, high waist-to-height ratio, hypertriglyceridemia, hyper-low-density lipoprotein cholesterolemia, high lipid accumulation product, and metabolic syndrome. The previously mentioned results were obtained both in age-matched analysis and in age- and alcohol intake-matched analysis, although the percentage of regular drinkers was significantly higher in the hyper-HDL cholesterolemic group than in the age-matched control group. Hyper-HDL cholesterolemia was inversely associated with obesity, dyslipidemia, and metabolic syndrome in the analysis using alcohol intake-matched subject groups. Therefore, the association of hyper-HDL cholesterolemia with lower cardiometabolic risk is thought to be independent of habitual alcohol drinking.

Seasonal changes in the population structure of dominant planktonic copepods collected using a sediment trap moored in the western Arctic Ocean

Winter ice cover of the Arctic Ocean makes year-round zooplankton sampling by plankton net a difficult task. Therefore, the collection of copepods with a sediment trap can be a powerful tool. In the present study, we analysed the seasonal changes in the population structures of five dominant planktonic copepods (Oncaea parila, Calanus hyperboreus, Metridia longa, Paraeuchaeta glacialis and Heterorhabdus norvegicus), which were collected using a sediment trap rotated at 10–15 day intervals moored at 184–260 m in the Northwind Abyssal Plain (75°00′N, 162°00′W) of the western Arctic Ocean from October 2010 to September 2012. Oncaea parila C6F with egg sacs occurred throughout the year, and the total abundance and composition of early copepodid stages (C1−C3) had two peaks each year. Calanus hyperboreus was dominated by C6F throughout the year, and their maturation was observed during February to May. Metridia longa C6F had a clear seasonality in lipid accumulation and gonad maturation: high lipid accumulation was observed from October to February, whereas gonad maturation occurred from March to September. Paraeuchaeta glacialis C6F also showed seasonality in lipid accumulation and gonad maturation, although their seasonal patterns varied from those of M. longa: high lipid individuals were abundant from February to April and mature individuals dominated from October to November. Heterorhabdus norvegicus showed seasonal changes in population structure as well: C1, C5, and C6M dominated from April to May, November to February and August to October, respectively. The life cycle patterns of these species are compared with those reported from other areas. While the results obtained by a sediment trap are inevitably subject to collection bias (i.e. passive collection at a fixed depth), a sediment trap should be considered as a powerful tool for the evaluation of the life cycle of planktonic copepods, especially in ice-covered oceans.

Influence of bovine serum albumin and fetal bovine serum supplementation during in vitro maturation on lipid and mitochondrial behaviour in oocytes and lipid accumulation in bovine embryos.

Proper oocyte maturation is crucial for subsequent embryo development; however, oocyte mitochondrial and lipid-droplet behaviour are still poorly understood. Although excessive lipid accumulation during in vitro production (IVP) of bovine embryos has been linked with impaired cryotolerance, lipid oxidation is essential for adequate energy supply. Fetal bovine serum (FBS) and bovine serum albumin (BSA) are supplements used during IVP, containing high and low lipid content, respectively. This study aimed to understand how these supplements influence oocyte mitochondrial and lipid behaviour during in vitro maturation (IVM) in comparison to in vivo maturation, as well as their influence on development rates and embryo lipid accumulation during IVP. We demonstrate that only in vivo-matured oocytes maintained correlation between lipid content and active mitochondria. IVM media containing FBS increased total lipid content 18-fold and resulted in higher lipid accumulation in oocytes when compared with media with BSA. IVM using a lower FBS concentration combined with BSA resulted in satisfactory maturation and embryo development and also reduced lipid accumulation in blastocysts. In conclusion, IVM causes changes in mitochondrial and lipid dynamics, which may have negative effects on oocyte development rates and embryo lipid accumulation. Moreover, decreasing FBS concentrations during IVM may reduce embryo lipid accumulation without affecting production rates.

Growth and lipid accumulation of microalgae from fluctuating brackish and sea water locations in South East Queensland-Australia.

One challenge constraining the use of microalgae in the food and biofuels industry is growth and lipid accumulation. Microalgae with high growth characteristics are more likely to originate from the local environment. However, to be commercially effective, in addition to high growth microalgae must also have high lipid productivities and contain the desired fatty acids for their intended use. We isolated microalgae from intertidal locations in South East Queensland, Australia with adverse or fluctuating conditions, as these may harbor more opportunistic strains with high lipid accumulation potential. Screening was based on a standard protocol using growth rate and lipid accumulation as well as prioritizing fatty acid profiles suitable for biodiesel or nutraceuticals. Using these criteria, an initial selection of over 50 local microalgae strains from brackish and sea water was reduced to 16 strains considered suitable for further investigation. Among these 16 strains, the ones most likely to be effective for biodiesel feedstock were Nitzschia sp. CP3a, Tetraselmis sp. M8, Cymbella sp. CP2b, and Cylindrotheca closterium SI1c, reaching growth rates of up to 0.53 day−1 and lipid productivities of 5.62 μg mL−1day−1. Omega-3 fatty acids were found in some strains such as Nitzschia sp. CP2a, Nitzschia sp. CP3a and Cylindrotheca closterium SI1c. These strains have potential for further research as commercial food supplements.

Hypothalamic AgRP‐mediated energy metabolism in skeletal muscle is a critical regulatory system in feeding rhythm‐induced insulin resistance

Hypothalamic control of peripheral energy metabolism is an important regulatory system in whole body energy homeostasis, although whether feeding rhythm affect the hypothalamic regulation system of energy metabolism has not elucidated. In this study C57BL/6J mice were separated for 3 feeding scheduled groups; given lab chows freely during dark phase (ZT12‐24; Control group), first 4‐hour in dark phase (ZT12‐16; Morning group), and last 4‐hour in dark phase (ZT20‐24; Evening group) for 8weeks. Mice in Evening group showed impaired whole body insulin sensitivity while mice in Morning group showed normal insulin sensitivity compared to Control group. We observed that higher lipid accumulation and impaired insulin signals in skeletal muscle in Evening group compared to other group. On the other hand, mRNA expression of agouti‐related protein (AgRP) was increased in hypothalamus in Evening group. We found that intracerebroventricular injection of AgRP increased gene expression of lipid accumulation in skeletal muscle of mice in Control group. Inhibition of central AgRP expression by antisense oligo improved insulin resistance in skeletal muscle of Evening group. These results indicate that usual energy ingestion mainly after the evening impairs insulin sensitivity in skeletal muscle mediated by hypothalamic AgRP.

Targeted Disruption of Ig-Hepta/Gpr116 Causes Emphysema-like Symptoms That Are Associated with Alveolar Macrophage Activation

Ig-Hepta/GPR116 is a member of the G protein-coupled receptor family predominantly expressed in the alveolar type II epithelial cells of the lung. Previous studies have shown that Ig-Hepta is essential for lung surfactant homeostasis, and loss of its function results in high accumulation of surfactant lipids and proteins in the alveolar space. Ig-Hepta knock-out (Ig-Hepta(-/-)) mice also exhibit emphysema-like symptoms, including accumulation of foamy alveolar macrophages (AMs), but its pathogenic mechanism is unknown. Here, we show that the bronchoalveolar lavage fluid obtained from Ig-Hepta(-/-) mice contains high levels of inflammatory mediators, lipid hydroperoxides, and matrix metalloproteinases (MMPs), which are produced by AMs. Accumulation of reactive oxygen species was observed in the AMs of Ig-Hepta(-/-) mice in an age-dependent manner. In addition, nuclear factor-κB (NF-κB) is activated and translocated into the nuclei of the AMs of Ig-Hepta(-/-) mice. Release of MMP-2 and MMP-9 from the AMs was strongly inhibited by treatment with inhibitors of oxidants and NF-κB. We also found that the level of monocyte chemotactic protein-1 is increased in the embryonic lungs of Ig-Hepta(-/-) mice at 18.5 days postcoitum, when AMs are not accumulated and activated. These results suggest that Ig-Hepta plays an important role in regulating macrophage immune responses, and its deficiency leads to local inflammation in the lung, where AMs produce excessive amounts of reactive oxygen species and up-regulate MMPs through the NF-κB signaling pathway.

Nobiletin Attenuates High Glucose‐induced Lipid Accumulation in HepG2 Hepatocytes through Activation of AMP‐activated Protein Kinase‐dependent Signaling

Nobiletin, a citrus polymethoxyflavonoid with six methoxy groups, is found abundantly in the peels of citrus fruits. Although nobiletin has been reported to display anti‐inflammatory, anti‐tumor, and anti‐diabetes activities, its effect on lipid modulation remained unclear. In the present study, we investigated the effect of nobiletin on hepatic lipogenesis in high glucose‐induced HepG2 cells. HepG2 cells were incubated in either normal (5.5 mmol/L) or high (25 mmol/L) glucose and subsequently treated with different concentrations of nobiletin (5, 25 and 50 μM). The results revealed that nobiletin markedly inhibited hepatic lipid accumulation in HepG2 cells. Nobiletin also reduced the expression of lipogenic factors, including sterol regulatory element‐binding protein 1c (SREBP‐1c) and fatty acid synthase (FAS). Moreover, nobiletin significantly increased AMP‐activated protein kinase (AMPK) phosphorylation and acetyl‐CoA carboxylase (ACC) phosphorylation. Pretreatment with compound C, an AMPK inhibitor, abolished the inhibitory effects of nobiletin on SREBP‐1c and FAS expressions. These results suggest that nobiletin may attenuate the high glucose‐induced lipid accumulation in HepG2 hepatocytes through modulation of AMPK signaling pathway, therefore preventing hepatic steatosis.