Identification of lipid droplet structure-like/resident proteins in Caenorhabditis elegans.

The lipid droplet (LD) is a cellular organelle that stores neutral lipids in cells and has been linked with metabolic disorders. Caenorhabditis elegans has many characteristics which make it an excellent animal model for studying LDs. However, unlike in mammalian cells, no LD structure-like/resident proteins have been identified in C. elegans, which has limited the utility of this model for the study of lipid storage and metabolism. Herein based on three lines of evidence, we identified that MDT-28 and DHS-3 previously identified in C. elegans LD proteome were two LD structure-like/resident proteins. First, MDT-28 and DHS-3 were found to be the two most abundant LD proteins in the worm. Second, the proteins were specifically localized to LDs and we identified the domains responsible for this targeting in both proteins. Third and most importantly, the depletion of MDT-28 induced LD clustering while DHS-3 deletion reduced triacylglycerol content (TAG). We further characterized the proteins finding that MDT-28 was ubiquitously expressed in the intestine, muscle, hypodermis, and embryos, whereas DHS-3 was expressed mainly in intestinal cells. Together, these two LD structure-like/resident proteins provide a basis for future mechanistic studies into the dynamics and functions of LDs in C. elegans.

Integrated omics study delineates the dynamics of lipid droplets in Rhodococcus opacus PD630.

Rhodococcus opacus strain PD630 (R. opacus PD630), is an oleaginous bacterium, and also is one of few prokaryotic organisms that contain lipid droplets (LDs). LD is an important organelle for lipid storage but also intercellular communication regarding energy metabolism, and yet is a poorly understood cellular organelle. To understand the dynamics of LD using a simple model organism, we conducted a series of comprehensive omics studies of R. opacus PD630 including complete genome, transcriptome and proteome analysis. The genome of R. opacus PD630 encodes 8947 genes that are significantly enriched in the lipid transport, synthesis and metabolic, indicating a super ability of carbon source biosynthesis and catabolism. The comparative transcriptome analysis from three culture conditions revealed the landscape of gene-altered expressions responsible for lipid accumulation. The LD proteomes further identified the proteins that mediate lipid synthesis, storage and other biological functions. Integrating these three omics uncovered 177 proteins that may be involved in lipid metabolism and LD dynamics. A LD structure-like protein LPD06283 was further verified to affect the LD morphology. Our omics studies provide not only a first integrated omics study of prokaryotic LD organelle, but also a systematic platform for facilitating further prokaryotic LD research and biofuel development.

Oxygen absorbers in food preservation: a review.

The preservation of packaged food against oxidative degradation is essential to establish and improve food shelf life, customer acceptability, and increase food security. Oxygen absorbers have an important role in the removal of dissolved oxygen, preserving the colour, texture and aroma of different food products, and importantly inhibition of food spoilage microbes. Active packaging technology in food preservation has improved over decades mostly due to the sealing of foods in oxygen impermeable package material and the quality of oxygen absorber. Ferrous iron oxides are the most reliable and commonly used oxygen absorbers within the food industry. Oxygen absorbers have been transformed from sachets of dried iron-powder to simple self-adhesive patches to accommodate any custom size, capacity and application. Oxygen concentration can be effectively lowered to 100 ppm, with applications spanning a wide range of food products and beverages across the world (i.e. bread, meat, fish, fruit, and cheese). Newer molecules that preserve packaged food materials from all forms of degradation are being developed, however oxygen absorbers remain a staple product for the preservation of food and pharmaceutical products to reduce food wastage in developed nations and increased food security in the developing & third world.

Proliferative activity of a blend of Echinacea angustifolia and Echinacea purpurea root extracts in human vein epithelial, HeLa, and QBC-939 cell lines, but not in Beas-2b cell lines.

Echinacea is used for its immunostimulating properties and may have a role in modulating adverse immune effects of chemotherapy (i.e., use of 5-fluorouracil (5-FU); fluorouracil and its immunosuppressive effect). Patients may seek herbal remedies such as Echinacea (Echinacea angustifolia and Echinacea purpurea) for immune stimulation. Echinacea extracts have been prescribed to supplement cancer chemotherapy for their immune-supportive effects; however, the extracts may also influence tumourgenesis. Our study aimed to determine the proliferative effect of the ethanolic blend of E. angustifolia and E. purpurea on various cancer cervical and bile duct cell lines, including HELA and QBC-939. Various cancer cells (HeLa and QBC-939) and human vein epithelial cells (HUVEC) were treated with the Echinacea blend sample that was evaporated and reconstituted in Dimethyl sulfoxide (DMSO). As the extract concentration of Echinacea was increased from 12.5 µg/mL to 25 µg/mL, there was an increase in cell inhibition up to 100%, which then reduced to 90% over the next three concentrations, 50 µg/mL, 100 µg/mL, and 200 µg/mL, in HeLa cells; further inhibitory effects were observed in QBC-939 cells, from 9% inhibition at a concentration of 25 µg/mL up to 37.96% inhibition at 100 µg/mL concentration. Moreover, this is the first study to report the growth-promoting effects of this Echinacea blend in HUVEC, up to 800% at a dose concentration of 200 µg/mL. Previous studies have suggested that chicoric acid of Echinacea spp. is responsible for the increased cell growth. The results of this study show that the hydroethanolic extract of Echinacea herbal medicine promotes the growth of HeLa cells and QBC-939 cancer cell proliferation, and may interfere with cancer treatment (i.e., chemotherapy drugs such as 5-fluorouracil and Cisplatin (DDP)). However, the Echinacea blend shows potential in neurodegenerative diseases with growth-promoting effects in HUVEC. Further animal trials (in vivo effect) measuring dose toxicology are necessary to demonstrate the interaction of this blend with body and tumor growth, and also any positive synergistic or adverse interaction with chemotherapeutic drugs listed, so as to confirm the current observation and epithelial tissue growth or regeneration in a neurodegenerative disease model.

Morphologically and Functionally Distinct Lipid Droplet Subpopulations.

Lipid droplet (LD), a multi-functional organelle, is often found to associate with other cellular membranous structures and vary in size in a given cell, which may be related to their functional diversity. Here we established a method to separate LD subpopulations from isolated CHO K2 LDs into three different size categories. The subpopulation with smallest LDs was nearly free of ER and other membranous structures while those with larger LDs contained intact ER. These distinct subpopulations of LDs differed in their protein composition and ability to recruit proteins. This method was also applicable to LDs obtained from other sources, such as Huh7 cells, mouse liver and brown adipose tissue, et al. We developed an in vitro assay requiring only isolated LDs, Coenzyme A, and ATP to drive lipid synthesis. The LD subpopulation nearly depleted of ER was able to incorporate fatty acids into triacylglycerol and phospholipids. Together, our data demonstrate that LDs in a given cell are heterogeneous in size and function, and suggest that LDs are one of cellular lipid synthetic organelles.

Skeletal intramyocellular lipid metabolism and insulin resistance.

Lipids stored in skeletal muscle cells are known as intramyocellular lipid (IMCL). Disorders involving IMCL and its causative factor, circulatory free fatty acids (FFAs), induce a toxic state and ultimately result in insulin resistance (IR) in muscle tissue. On the other hand, intramuscular triglyceride (IMTG), the most abundant component of IMCL and an essential energy source for active skeletal muscle, is different from other IMCLs, as it is stored in lipid droplets and plays a pivotal role in skeletal muscle energy homeostasis. This review discusses the association of FFA-induced ectopic lipid accumulation and IR, with specific emphasis on the relationship between IMCL/IMTG metabolism and IR.

Effects of Two Traditional Chinese Cooking Oils, Canola and Pork, on pH and Cholic Acid Content of Faeces and Colon Tumorigenesis in Kunming Mice.

Faecal pH and cholate are two important factors that can affect colon tumorigenesis, and can be modified by diet. In this study, the effects of two Chinese traditional cooking oils (pork oil and canola/rapeseed oil) on the pH and the cholic acid content in feces, in addition to colon tumorigenesis, were studied in mice. Kunming mice were randomized into various groups; negative control group (NCG), azoxymethane control group (ACG), pork oil group (POG), and canola oil Ggroup (COG). Mice in the ACG were fed a basic rodent chow; mice in POG and COG were given 10% cooking oil rodent chow with the respective oil type. All mice were given four weekly AOM (azoxymethane) i.p. injections (10 mg/kg). The pH and cholic acid of the feces were examined every two weeks. Colon tumors, aberrant crypt foci and organ weights were examined 32 weeks following the final AOM injection. The results showed that canola oil significantly decreased faecal pH in female mice (P<0.05), but had no influence on feces pH in male mice (P>0.05). Pork oil significantly increased the feces pH in both male and female mice (P<0.05). No significant change was found in feces cholic acid content when mice were fed 10% pork oil or canola oil compared with the ACG. Although Kunming mice were not susceptible to AOM-induced tumorigenesis in terms of colon tumor incidence, pork oil significantly increased the ACF number in male mice. Canola oil showed no influence on ACF in either male or female mice. Our results indicate that cooking oil effects faecal pH, but does not affect the faecal cholic acid content and thus AOM-induced colon neoplastic ACF is modified by dietary fat.

Proliferative and Inhibitory Activity of Siberian ginseng (Eleutherococcus senticosus) Extract on Cancer Cell Lines; A-549, XWLC-05, HCT-116, CNE and Beas-2b.

Siberian ginseng (Eleutherococcus senticosus) is used primarily as an adaptogen herb and also for its immune stimulant properties in Western herbal medicine. Another closely related species used in East Asian medicine systems i.e. Kampo, TCM (Manchuria, Korea, Japan and Ainu of Hokkaido) and also called Siberian ginseng (Acanthopanax senticosus) also displays immune-stimulant and anti-cancer properties. These may affect tumour growth and also provide an anti-fatigue effect for cancer patients, in particular for those suffering from lung cancer. There is some evidence that a carbohydrate in Siberian ginseng may possess not only immune stimulatory but also anti-tumour effects and also display other various anti-cancer properties. Our study aimed to determine the inhibitory and also proliferative effects of a methanol plant extract of Siberan ginseng (E. senticosus) on various cancer and normal cell lines including: A-549 (small cell lung cancer), XWLC-05 (Yunnan lung cancer cell line), CNE (human nasopharyngeal carcinoma cell line), HCT-116 (human colon cancer) and Beas-2b (human lung epithelial). These cell lines were treated with an extract from E. senticosus that was evaporated and re- constituted in DMSO. Treatment of A-549 (small cell lung cancer) cells with E. senticosus methanolic extract showed a concentration-dependent inhibitory trend from 12.5 - 50µg/mL, and then a plateau, whereas at 12.5 and 25 µg/mL, there is a slight growth suppression in QBC-939 cells, but then a steady suppression from 50, 100 and 200µg/mL. Further, in XWLC-05 (Yunnan lung cancer cell line), E. senticosus methanolic extract displayed an inhibitory effect which plateaued with increasing dosage. Next, in CNE (human nasopharyngeal carcinoma cell line) there was a dose dependent proliferative response, whereas in Beas-2 (human lung epithelial cell line), an inhibitory effect. Finally in colon cancer cell line (HCT-116) we observed an initially weak inhibitory effect and then plateau.

Canola oil influence on azoxymethane-induced colon carcinogenesis, hypertriglyceridemia and hyperglycemia in Kunming mice.

Azoxymethane (AOM) is a potent genotoxic carcinogen which specifically induces colon cancer. Hyperlipidemia and diabetes have several influences on colon cancer development, with genetic and environmental exposure aspects. Here, we investigated plasma lipid and glucose concentrations in Kunming mice randomized into four groups; control (no AOM or oil exposure), AOM control, AOM + pork oil, and AOM + canola oil. Aberrant crypt foci (ACF), plasma cholesterol, plasma triglyceride, plasma glucose and organ weight were examined 32 weeks after AOM injection. Results revealed that AOM exposure significantly increased ACF number, plasma triglyceride and glucose level. Further, male mice displayed a much higher plasma triglyceride level than female mice in the AOM control group. Dietary fat significantly inhibited AOM-induced hypertriglyceridemia, and canola oil had stronger inhibitory effect than pork oil. AOM-induced hyperglycemia had no sex-difference and was not significantly modified by dietary fat. However, AOM itself not change plasma cholesterol level. AOM significantly increased liver and spleen weight in male mice, but decreased kidney weight in female mice. On the other hand, mice testis weight decreased when fed canola oil. AOM could induce colorectal carcinogenesis, hypertriglyceridemia and hyperglycemia in Kunming mice at the same time, with subsequent studies required to investigate their genome association.

Microorganism lipid droplets and biofuel development.

Lipid droplet (LD) is a cellular organelle that stores neutral lipids as a source of energy and carbon. However, recent research has emerged that the organelle is involved in lipid synthesis, transportation, and metabolism, as well as mediating cellular protein storage and degradation. With the exception of multi-cellular organisms, some unicellular microorganisms have been observed to contain LDs. The organelle has been isolated and characterized from numerous organisms. Triacylglycerol (TAG) accumulation in LDs can be in excess of 50% of the dry weight in some microorganisms, and a maximum of 87% in some instances. These microorganisms include eukaryotes such as yeast and green algae as well as prokaryotes such as bacteria. Some organisms obtain carbon from CO2 via photosynthesis, while the majority utilizes carbon from various types of biomass. Therefore, high TAG content generated by utilizing waste or cheap biomass, coupled with an efficient conversion rate, present these organisms as bio-tech 'factories' to produce biodiesel. This review summarizes LD research in these organisms and provides useful information for further LD biological research and microorganism biodiesel development.

Proteomic studies of isolated lipid droplets from bacteria, C. elegans, and mammals.

Lipid droplets (LDs) are an intracellular organelle, consisting of a neutral lipid core covered by a monolayer of phospholipids and proteins. It primarily mediates lipid storage, metabolism, and transportation. Recently, research of LDs has emerged as a rapidly developing field due to the strong linkage between ectopic lipid accumulation and metabolic syndromes. Recently, more than 30 proteomic studies of isolated LDs have identified many important LD proteins that have highlighted and have also predicted the potential biological roles of the organelle, motivating the field to develop quite rapidly. This chapter summarizes methods used in proteomic studies for three representative species reported and discusses their advantages and disadvantages. We believe that this chapter provides useful information and methods for future LD proteomic studies especially for LDs in other species.