Comparative genomics and functional study of lipid metabolic genes in Caenorhabditis elegans

De novo lipid synthesis and polarized prenylation drive cell invasion through basement membrane

To breach the basement membrane, cells in development and cancer use large, transient, specialized lipid-rich membrane protrusions. Using live imaging, endogenous protein tagging, and cell-specific RNAi during Caenorhabditis elegans anchor cell (AC) invasion, we demonstrate that the lipogenic SREBP transcription factor SBP-1 drives the expression of the fatty acid synthesis enzymes POD-2 and FASN-1 prior to invasion. We show that phospholipid-producing LPIN-1 and sphingomyelin synthase SMS-1, which use fatty acids as substrates, produce lysosome stores that build the AC's invasive protrusion, and that SMS-1 also promotes protrusion localization of the lipid raft partitioning ZMP-1 matrix metalloproteinase. Finally, we discover that HMG-CoA reductase HMGR-1, which generates isoprenoids for prenylation, localizes to the ER and enriches in peroxisomes at the AC invasive front, and that the final transmembrane prenylation enzyme, ICMT-1, localizes to endoplasmic reticulum exit sites that dynamically polarize to deliver prenylated GTPases for protrusion formation. Together, these results reveal a collaboration between lipogenesis and a polarized lipid prenylation system that drives invasive protrusion formation.

Mitochondria UPR stimulation by pelargonidin-3-glucoside contributes to ameliorating lipid accumulation under copper exposure

Intensification of copper pollution in the environment has led to its excessive accumulation in humans, causing oxidative stress and lipid metabolism disorders. It is necessary to look for effective targets and safe methods to alleviate copper toxicity. Pelargonidin-3-glucoside (Pg3G) is a natural anthocyanin with metal ion chelating ability and multiple physiological activities. In this study, lipid accumulation was investigated under copper exposure in Caenorhabditis elegans which can be improved by Pg3G. Transcriptome analysis revealed that differentially expressed genes are enriched in lipid metabolism and protein folding/degradation. Pg3G activated mitochondrial unfold protein response (UPRmt) to mitigate mitochondrial damage caused by copper and regulated the expression of genes involved in lipid absorption, transport, and synthesis, thereby reducing lipid levels in C. elegans. This improvement disappeared in the ubl-5 knockout strain, indicating that ubl-5 is one target of Pg3G. Meanwhile, in HepG2 cells, Pg3G enhanced the cellular antioxidant capacity by activating UPRmt for maintaining mitochondrial homeostasis, followed by inhibition of excessive lipid accumulation. Overall, these results suggested that UPRmt activation can be a strategy for mitigating lipid disorders induced by copper and Pg3G with excellent ability to resist oxidative stress specially targeted for ubl-5 has a promising application in controlling copper contamination.

RNAi-dependent expression of sperm genes in ADL chemosensory neurons is required for olfactory responses in Caenorhabditis elegans

Environmental conditions experienced early in the life of an animal can result in gene expression changes later in its life history. We have previously shown that C. elegans animals that experienced the developmentally arrested and stress resistant dauer stage (postdauers) retain a cellular memory of early-life stress that manifests during adulthood as genome-wide changes in gene expression, chromatin states, and altered life history traits. One consequence of developmental reprogramming in C. elegans postdauer adults is the downregulation of osm-9 TRPV channel gene expression in the ADL chemosensory neurons resulting in reduced avoidance to a pheromone component, ascr#3. This altered response to ascr#3 requires the principal effector of the somatic nuclear RNAi pathway, the Argonaute (AGO) NRDE-3. To investigate the role of the somatic nuclear RNAi pathway in regulating the developmental reprogramming of ADL due to early-life stress, we profiled the mRNA transcriptome of control and postdauer ADL in wild-type and nrde-3 mutant adults. We found 711 differentially expressed (DE) genes between control and postdauer ADL neurons, 90% of which are dependent upon NRDE-3. Additionally, we identified a conserved sequence that is enriched in the upstream regulatory sequences of the NRDE-3-dependent differentially expressed genes. Surprisingly, 214 of the ADL DE genes are considered "germline-expressed", including 21 genes encoding the Major Sperm Proteins and two genes encoding the sperm-specific PP1 phosphatases, GSP-3 and GSP-4. Loss of function mutations in gsp-3 resulted in both aberrant avoidance and attraction behaviors. We also show that an AGO pseudogene, Y49F6A.1 (wago-11), is expressed in ADL and is required for ascr#3 avoidance. Overall, our results suggest that small RNAs and reproductive genes program the ADL mRNA transcriptome during their developmental history and highlight a nexus between neuronal and reproductive networks in calibrating animal neuroplasticity.

LET-767 determines lipid droplet protein targeting and lipid homeostasis

Lipid droplets (LDs) are composed of a core of neutral lipids wrapped by a phospholipid (PL) monolayer containing several hundred proteins that vary between different cells or organisms. How LD proteins target to LDs is still largely unknown. Here, we show that RNAi knockdown or gene mutation of let-767, encoding a member of hydroxysteroid dehydrogenase (HSD), displaced the LD localization of three well-known LD proteins: DHS-3 (dehydrogenase/reductase), PLIN-1 (perilipin), and DGAT-2 (diacylglycerol O-acyltransferase 2), and also prevented LD growth in Caenorhabditis elegans. LET-767 interacts with ARF-1 (ADP-ribosylation factor 1) to prevent ARF-1 LD translocation for appropriate LD protein targeting and lipid homeostasis. Deficiency of LET-767 leads to the release of ARF-1, which further recruits and promotes translocation of ATGL-1 (adipose triglyceride lipase) to LDs for lipolysis. The displacement of LD proteins caused by LET-767 deficiency could be reversed by inhibition of either ARF-1 or ATGL-1. Our work uncovers a unique LET-767 for determining LD protein targeting and maintaining lipid homeostasis.

Sphingolipid profiling reveals differential functions of sphingolipid biosynthesis isozymes of Caenorhabditis elegans

Multiple isozymes are encoded in the Caenorhabditis elegans genome for the various sphingolipid biosynthesis reactions, but the contributions of individual isozymes are characterized only in part. We developed a simple but effective reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) method that enables simultaneous identification and quantification of ceramides (Cer), glucosylceramides (GlcCer), and sphingomyelins (SM) from the same MS run. Validating this sphingolipid profiling method, we show that nearly all 47 quantifiable sphingolipid species found in young adult worms were reduced upon RNA interference (RNAi) of sptl-1 or elo-5, which are both required for synthesis of the id17:1 sphingoid base. We also confirm that HYL-1 and HYL-2, but not LAGR-1, constitute the major ceramide synthase activity with different preference for fatty acid substrates, and that CGT-3, but not CGT-1 and CGT-2, plays a major role in producing GlcCers. Deletion of sms-5 hardly affected SM levels. RNAi of sms-1, sms-2, and sms-3 all lowered the abundance of certain SMs with an odd-numbered N-acyl chains (mostly C21 and C23, with or without hydroxylation). Unexpectedly, sms-2 RNAi and sms-3 RNAi elevated a subset of SM species containing even-numbered N-acyls. This suggests that sphingolipids containing even-numbered N-acyls could be regulated separately, sometimes in opposite directions, from those containing odd-numbered N-acyls, which are presumably monomethyl branched chain fatty acyls. We also find that ceramide levels are kept in balance with those of GlcCers and SMs. These findings underscore the effectiveness of this RPLC-MS/MS method in studies of C. elegans sphingolipid biology.

Diosgenin intervention: targeting lipophagy to counter high glucose diet-induced lipid accumulation and lifespan reduction

Diosgenin (DG), a well-known steroidal sapogenin, is abundantly found in the plants of the Dioscoreaceae family and exhibits diverse pharmacological properties. In our previous study, we demonstrated that DG supplementation protected Caenorhabditis elegans from high glucose-induced lipid deposition, oxidative damage, and lifespan reduction. Nevertheless, the precise biological mechanisms underlying the beneficial effects of DG have not yet been described. In this context, the present study aims to elucidate how DG reduces molecular and cellular declines induced by high glucose, using the powerful genetics of the C. elegans model. Treatment with DG significantly (p < 0.01) prevented fat accumulation and extended lifespan under high-glucose conditions without affecting physiological functions. DG-induced lifespan extension was found to rely on longevity genes daf-2, daf-16, skn-1, glp-1, eat-2, let-363, and pha-4. Specifically, DG regulates lipophagy, the autophagy-mediated degradation of lipid droplets, in C. elegans, thereby inhibiting fat accumulation. Furthermore, DG treatment did not alter the triglyceride levels in the fat-6 and fat-7 single mutants and fat-6;fat-7 double mutants, indicating the significant role of stearoyl-CoA desaturase genes in mediating the reduction of fat deposition by DG. Our results provide new insight into the fat-reducing mechanisms of DG, which might develop into a multitarget drug for preventing obesity and associated health complications; however, preclinical studies are required to investigate the effect of DG on higher models.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-04017-3.

Database construction and comparative genomics analysis of genes involved in nutritional metabolic diseases in fish

Nutritional metabolic diseases in fish frequently arise in the setting of intensive aquaculture. The etiology and pathogenesis of these conditions involve energy metabolic disorders influenced by both internal genetic factors and external environmental conditions. The exploration of genes associated with nutritional and metabolic disorder has sparked considerable interest within both the aquaculture scientific community and the industry. High-throughput sequencing technology offers researchers extensive genetic information. Effectively mining, analyzing, and securely storing this data is crucial, especially for advancing disease prevention and treatment strategies. Presently, the exploration and application of gene databases concerning nutritional and metabolic disorders in fish are at a nascent stag. Therefore, this study focused on the model organism zebrafish and five primary economic fish species as the subjects of investigation. Using information from KEGG, OMIM, and existing literature, a novel gene database associated with nutritional metabolic diseases in fish was meticulously constructed. This database encompassed 4583 genes for Danio rerio, 6287 for Cyprinus carpio, 3289 for Takifugu rubripes, 3548 for Larimichthys crocea, 3816 for Oreochromis niloticus, and 5708 for Oncorhynchus mykiss. Through a comparative systems biology approach, we discerned a relatively high conservation of genes linked to nutritional metabolic diseases across these fish species, with over 54.9 % of genes being conserved throughout all six species. Additionally, the analysis pinpointed the existence of 13 species-specific genes within the genomes of large yellow croaker, tilapia, and rainbow trout. These genes exhibit the potential to serve as novel candidate targets for addressing nutritional metabolic diseases.

Obesogenic potentials of environmental artificial sweeteners with disturbances on both lipid metabolism and neural responses

Artificial sweeteners (ASs) entered the environments after application and emissions. Recent studies showed that some ASs had obesogenic risks. However, it remained unclear whether such risks are common and how they provoke such effects. Presently, the effects of 8 widely used ASs on lipid accumulation were measured in Caenorhabditis elegans. Potential mechanisms were explored with feeding and locomotion behavior, lipid metabolism and neural regulation. Results showed that acesulfame (ACE), aspartame (ASP), saccharin sodium (SOD), sucralose (SUC) and cyclamate (CYC) stimulated lipid accumulation at μg/L levels, showing obesogenic potentials. Behavior investigation showed that ACE, ASP, SOD, SUC and CYC biased more feeding in the energy intake aspect against the locomotion in the energy consumption one. Neotame (NEO), saccharin (SAC) and alitame (ALT) reduced the lipid accumulation without significant obesogenic potentials in the present study. However, all 8 ASs commonly disturbed enzymes (e.g., acetyl-CoA carboxylase) in lipogenesis and those (e.g., carnitine palmitoyl transferase) in lipolysis. In addition, ASs disturbed PPARγ (via expressions of nhr-49), TGF-β/DAF-7 (daf-7) and SREBP (sbp-1) pathways. Moreover, they also interfered neurotransmitters including serotonin (5-HT), dopamine (DA) and acetylcholine (ACh), with influences in Gsα (e.g., via expressions of gsα-1, ser-7), glutamate (e.g., mgl-1), and cGMP-dependent signaling pathways (e.g., egl-4). In summary, environmental ASs commonly disturbed neural regulation connecting behavior and lipid metabolism, and 5 out of 8 showed clear obesogenic potentials. ENVIRONMENTAL IMPLICATION: Artificial sweeteners (ASs) are become emerging pollutants after wide application and continuous emission. Recent studies showed that some environmental ASs had obesogenic risks. The present study employed Caenorhabditis elegans to explore the influences of 8 commonly used ASs on lipid metabolisms and also the underlying mechanisms. Five out of 8 ASs stimulated lipid accumulation at μg/L levels, and they biased energy intake against energy consumption. The other three ASs reduced the lipid accumulation. ASs commonly disturbed lipogenesis and lipolysis via PPARγ, TGF-β and SREBP pathways, and also influenced neurotransmitters with Gsα, glutamate and cGMP-dependent signaling pathways.

A bioinformatics approach to elucidate conserved genes and pathways in C. elegans as an animal model for cardiovascular research

Cardiovascular disease (CVD) is a collective term for disorders of the heart and blood vessels. The molecular events and biochemical pathways associated with CVD are difficult to study in clinical settings on patients and in vitro conditions. Animal models play a pivotal and indispensable role in CVD research. Caenorhabditis elegans, a nematode species, has emerged as a prominent experimental organism widely utilized in various biomedical research fields. However, the specific number of CVD-related genes and pathways within the C. elegans genome remains undisclosed to date, limiting its in-depth utilization for investigations. In the present study, we conducted a comprehensive analysis of genes and pathways related to CVD within the genomes of humans and C. elegans through a systematic bioinformatic approach. A total of 1113 genes in C. elegans orthologous to the most significant CVD-related genes in humans were identified, and the GO terms and pathways were compared to study the pathways that are conserved between the two species. In order to infer the functions of CVD-related orthologous genes in C. elegans, a PPI network was constructed. Orthologous gene PPI network analysis results reveal the hubs and important KRs: pmk-1, daf-21, gpb-1, crh-1, enpl-1, eef-1G, acdh-8, hif-1, pmk-2, and aha-1 in C. elegans. Modules were identified for determining the role of the orthologous genes at various levels in the created network. We also identified 9 commonly enriched pathways between humans and C. elegans linked with CVDs that include autophagy (animal), the ErbB signaling pathway, the FoxO signaling pathway, the MAPK signaling pathway, ABC transporters, the biosynthesis of unsaturated fatty acids, fatty acid metabolism, glutathione metabolism, and metabolic pathways. This study provides the first systematic genomic approach to explore the CVD-associated genes and pathways that are present in C. elegans, supporting the use of C. elegans as a prominent animal model organism for cardiovascular diseases.

Conserved Cardiovascular Network: Bioinformatics Insights into Genes and Pathways for Establishing Caenorhabditis elegans as an Animal Model for Cardiovascular Diseases

Cardiovascular disease (CVD) is a collective term for disorders of the heart and blood vessels. The molecular events and biochemical pathways associated with CVD are difficult to study in clinical settings on patients and in vitro conditions. Animal models play a pivotal and indispensable role in cardiovascular disease (CVD) research. Caenorhabditis elegans , a nematode species, has emerged as a prominent experimental organism widely utilised in various biomedical research fields. However, the specific number of CVD-related genes and pathways within the C. elegans genome remains undisclosed to date, limiting its in-depth utilisation for investigations. In the present study, we conducted a comprehensive analysis of genes and pathways related to CVD within the genomes of humans and C. elegans through a systematic bioinformatic approach. A total of 1113 genes in C. elegans orthologous to the most significant CVD-related genes in humans were identified, and the GO terms and pathways were compared to study the pathways that are conserved between the two species. In order to infer the functions of CVD-related orthologous genes in C. elegans, a PPI network was constructed. Orthologous gene PPI network analysis results reveal the hubs and important KRs: pmk-1, daf-21, gpb-1, crh-1, enpl-1, eef-1G, acdh-8, hif-1, pmk-2, and aha-1 in C. elegans. Modules were identified for determining the role of the orthologous genes at various levels in the created network. We also identified 9 commonly enriched pathways between humans and C. elegans linked with CVDs that include autophagy (animal), the ErbB signalling pathway, the FoxO signalling pathway, the MAPK signalling pathway, ABC transporters, the biosynthesis of unsaturated fatty acids, fatty acid metabolism, glutathione metabolism, and metabolic pathways. This study provides the first systematic genomic approach to explore the CVD-associated genes and pathways that are present in C. elegans, supporting the use of C. elegans as a prominent animal model organism for cardiovascular diseases.

Lipid metabolism analysis providing insights into nonylphenol multi-toxicity mechanism

Nonylphenol (NP), a widely recognized endocrine disruptor, exhibits lipophobic properties that drive its accumulation in adipose tissue, leading to various physiological disruptions. Using Caenorhabditis elegans, this study investigated the effects of NP exposure on lipid homeostasis and physiological indicators. NP exposure increased lipid storage, hindered reproduction and growth, and altered phospholipid composition. Transcriptional analysis revealed NP's promotion of lipogenesis and inhibition of lipolysis. Metabolites related to lipid metabolism like citrate, amino acids, and neurotransmitters, along with lipids, collectively influenced physiological processes. This work elucidates the complex link between lipid metabolism disturbances and NP-induced physiological disruptions, enhancing our understanding of NP's multifaceted toxicity.

Glycerophospholipid Analysis of Optic Nerve Regeneration Models Indicate Potential Membrane Order Changes Associated with the Lipidomic Shifts

Purpose: Optic nerve (ON) injury causes irreversible degeneration, leading to vision loss that cannot be restored with available therapeutics. Current therapies slow further degeneration but do not promote regeneration. New regenerative factors have been discovered that are successful in vivo. However, the mechanisms of efficient long-distance regeneration are still unknown. Membrane expansion by lipid insertion is an essential regenerative process, so lipid profiles for regenerating axons can provide insight into growth mechanisms. This article's analysis aims to add to the increasingly available ON regeneration lipid profiles and relate it to membrane order/properties. Methods: In this study, we present an analysis of glycerophospholipids, one of the largest axonal lipid groups, from three mammalian ON regeneration lipid profiles: Wnt3a, Zymosan + CPT-cAMP, and Phosphatase/Tensin homolog knockout (PTENKO) at 7 and 14 days post crush (dpc). Significant lipid classes, species, and ontological properties were crossreferenced between treatments and analyzed using Metaboanalyst 5.0 and Lipid Ontology (LION). Membrane order changes associated with significant lipid classes were evaluated by C-Laurdan dye and exogenous lipids provided to a neuroblastoma cell line. Results and Conclusions: At 7 dpc, ONs show increased lysoglycerophospholipids and decreased phosphatidylethanolamines (PEs)/negative intrinsic curvature lipids. At 14 dpc, regenerative treatments show divergence: Wnt3a displays higher lysoglycerophospholipid content, while Zymosan and PTENKO decrease lysoglycerophospholipids and increase phosphatidylcholine (PC)-related species. Membrane order imaging indicates lysoglycerophospholipids decreases membrane order while PE and PC had no significant membrane order effects. Understanding these changes will allow therapeutic development targeting lipid metabolic pathways that can be used for vision loss treatments.

Eicosapentaenoic acid influences the pathogenesis of Candida albicans in Caenorhabditis elegans via inhibition of hyphal formation and stimulation of the host immune response

The intake of omega-3 polyunsaturated fatty acids, including eicosapentaenoic acid (EPA), is associated with health benefits due to its anti-inflammatory properties. This fatty acid also exhibits antifungal properties in vitro. In order to determine if this antifungal property is valid in vivo, we examined how EPA affects Candida albicans pathogenesis in the Caenorhabditis elegans infection model, an alternative to mammalian host models. The nematodes were supplemented with EPA prior to infection, and the influence of EPA on C. elegans lipid metabolism, survival and immune response was studied. In addition, the influence of EPA on hyphal formation in C. albicans was investigated. It was discovered that EPA supplementation changed the lipid composition, but not the unsaturation index of C. elegans by regulating genes involved in fatty acid and eicosanoid production. EPA supplementation also delayed killing of C. elegans by C. albicans due to the inhibition of hyphal formation in vivo, via the action of the eicosanoid metabolite of EPA, 17,18-epoxyeicosatetraenoic acid. Moreover, EPA supplementation also caused differential expression of biofilm-related gene expression in C. albicans and stimulated the immune response of C. elegans. This provides a link between EPA and host susceptibility to microbial infection in this model.

Biocompatible Alginate Hydrogel Film Containing Acetic Acid Manifests Broad-Spectrum Antiviral and Anticancer Activities

Acetic acid, a colourless liquid organic acid with a characteristic acrid smell, is obtained naturally and has applications in both the food and pharmaceutical industries. It has been reported to have beneficial uses for lifestyle-related diseases, and its efficient disinfectant properties are well known. In this study, an alginate crosslinked with Ca2+ hydrogel film was treated with acetic acid to explore its biological properties for biomedicine. The results showed that the novel calcium alginate/acetic acid film was biocompatible in vitro using human keratinocyte cells and in vivo with Caenorhabditis elegans. It also had antiviral properties against enveloped and non-enveloped viruses and anticancer properties against melanoma and colon cancer cells. This novel film thus showed promise for the biomedical and pharmaceutical industries, with applications for fabricating broad-spectrum antiviral and anticancer materials.

Protective Effect of Aquilaria crassna Leaf Extract against Benzo[a]pyrene-Induced Toxicity in Neuronal Cells and Caenorhabditis elegans: Possible Active Constituent Includes Clionasterol

Aquilaria crassna (AC) is a beneficial plant widely used to alleviate various health ailments. Nevertheless, the neuroprotection, antiaging, and xenobiotic detoxification against high benzo[a]pyrene induction have not been investigated. This study aimed to investigate the effects of ethanolic extract of AC leaves (ACEE) in vitro using SH-SY5Y cells and in vivo using Caenorhabditis elegans (C. elegans). Neuroprotective activities and cell cycle progression were studied using SH-SY5Y cells. Additionally, C. elegans was used to determine longevity, health span, and transcriptional analysis. Furthermore, ACEE possible active compounds were analyzed by gas chromatograph-mass spectrometry (GC-MS) analysis and the possible active compounds were evaluated using a molecular docking study. First, ACEE possessed neuroprotective effects by normalizing cell cycle progression via the regulation of AhR/CYP1A1/cyclin D1 pathway. Next, ACEE played a role in xenobiotic detoxification in high B[a]P-induced C. elegans by the amelioration of lifespan reduction, and body length and size decrease through the reduction in gene expression in hexokinase (hxk) and CYP35 pathway. Finally, phytochemicals of ACEE were identified and we uncovered that clionasterol was the possible active constituent in powerfully inhibiting both CYP1A1 and hexokinase II receptor. Essentially, ACEE was recognized as a potential alternative medicine to defend against high B[a]P effects on neurotoxicity and xenobiotic detoxification.

Astaxanthin reduces fat storage in a fat-6/fat-7 dependent manner determined using high fat Caenorhabditis elegans

Although astaxanthin has been shown to have high potential for weight loss, the specific action site and signal pathway generally cannot be confirmed in other animal models. This prevents us from finding therapeutic targets. Hence, we further illuminated its efficacy and specific action sites by using Caenorhabditis elegans (C. elegans). In this study, 60 μM astaxanthin supplementation reduced overall fat deposition and triglyceride levels by 21.47% and 22.00% (p < 0.01). The content of large lipid droplets was reversed after astaxanthin treatment, and the ratio of oleic acid/stearic acid (C18:1Δ9/C18:0) decreased significantly, which were essential substrates for triglyceride biosynthesis. In addition, astaxanthin prevented obesity caused by excessive energy accumulation and insufficient energy consumption. Furthermore, the above effects were induced by sbp-1/mdt-15 and insulin/insulin-like growth factor pathways, and finally co-regulated the specific site-fat-6 and fat-7 down-regulation. These results provided insight into therapeutic targets for future astaxanthin as a nutritional health product to relieve obesity.

Biocompatible Alginate Film Crosslinked with Ca2+ and Zn2+ Possesses Antibacterial, Antiviral, and Anticancer Activities

Alginate is a highly promising biopolymer due to its non-toxic and biodegradable properties. Alginate hydrogels are often fabricated by cross-linking sodium alginate with calcium cations and can be engineered with highly desirable enhanced physical and biological properties for biomedical applications. This study reports on the anticancer, antiviral, antibacterial, in vitro, and in vivo toxicity, water absorption, and compound release properties of an alginate hydrogel crosslinked with calcium and different amounts of zinc cations. The results showed that the calcium alginate hydrogel film crosslinked with the highest amount of zinc showed similar water sorption properties to those of calcium alginate and released a suitable amount of zinc to provide anticancer activity against melanoma and colon cancer cells and has antibacterial properties against methicillin-resistant Staphylococcus epidermidis and antiviral activity against enveloped and non-enveloped viruses. This film is non-toxic in both in vitro in keratinocyte HaCaT cells and in vivo in the Caenorhabditis elegans model, which renders it especially promising for biomedical applications.

Effects of moderate static magnetic fields on the lipogenesis and lipolysis in different genders of Caenorhabditis elegans

With the rapid development of magnetic technology, the biological effects of moderate static magnetic fields (SMFs) have attracted increasing research interest due to their potential medical diagnosis and treatment application. The present study explored the effects of moderate SMFs on the lipid metabolism of Caenorhabditis elegans (C. elegans) in different genders including male, female, and hermaphrodite. We found that the fat content was significantly decreased by moderate SMFs in wild-type N₂ worms, which was associated with their development stages. The diameters of lipid droplets in N₂ worms, him-5 worms, and fog-2 worms were greatly decreased by 19.23%, 15.38%, and 23.07% at young adult stage under 0.5 T SMF, respectively. The mRNA levels of lipolysis related genes atgl-1 and nhr-76 were significantly up-regulated by SMF exposure, while the mRNA levels of the lipogenesis related genes fat-6, fat-7, and sbp-1 were down-regulated by SMF, whereas the concentration of β-oxidase was increased. There was a slight effect of SMF on the mRNA levels of β-oxidation related genes. Moreover, the insulin and serotonin pathway were regulated by SMF, instead of the TOR pathway. In wild-type worms, we found that their lifespan was prolonged by exposure to 0.5 T SMF. Our data suggested that moderate SMFs could significantly modify the lipogenesis and lipolysis process in C. elegans in a gender and development stage-dependent manner, which could provide a novel insight into understanding the function of moderate SMFs in living organisms.

Akkermansia muciniphila Cell-Free Supernatant Improves Glucose and Lipid Metabolisms in Caenorhabditis elegans

To explore the mechanism by which Akkermansia muciniphila cell-free supernatant improves glucose and lipid metabolisms in Caenorhabditis elegans, the present study used different dilution concentrations of Akkermansia muciniphila cell-free supernatant as an intervention for with Caenorhabditis elegans under a high-glucose diet. The changes in lifespan, exercise ability, level of free radicals, and characteristic indexes of glucose and lipid metabolisms were studied. Furthermore, the expression of key genes of glucose and lipid metabolisms was detected by qRT-PCR. The results showed that A. muciniphila cell-free supernatant significantly improved the movement ability, prolonged the lifespan, reduced the level of ROS, and alleviated oxidative damage in Caenorhabditis elegans. A. muciniphila cell-free supernatant supported resistance to increases in glucose and triglyceride induced by a high-glucose diet and downregulated the expression of key genes of glucose metabolism, such as gsy-1, pygl-1, pfk-1.1, and pyk-1, while upregulating the expression of key genes of lipid metabolism, such as acs-2, cpt-4, sbp-1, and tph-1, as well as down-regulating the expression of the fat-7 gene to inhibit fatty acid biosynthesis. These findings indicated that A. muciniphila cell-free supernatant, as a postbiotic, has the potential to prevent obesity and improve glucose metabolism disorders and other diseases.

Application of Caenorhabditis elegans in Lipid Metabolism Research

Over the last decade, the development and prevalence of obesity have posed a serious public health risk, which has prompted studies on the regulation of adiposity. With the ease of genetic manipulation, the diversity of the methods for characterizing body fat levels, and the observability of feeding behavior, Caenorhabditis elegans (C. elegans) is considered an excellent model for exploring energy homeostasis and the regulation of the cellular fat storage. In addition, the homology with mammals in the genes related to the lipid metabolism allows many aspects of lipid modulation by the regulators of the central nervous system to be conserved in this ideal model organism. In recent years, as the complex network of genes that maintain an energy balance has been gradually expanded and refined, the regulatory mechanisms of lipid storage have become clearer. Furthermore, the development of methods and devices to assess the lipid levels has become a powerful tool for studies in lipid droplet biology and the regulation of the nematode lipid metabolism. Herein, based on the rapid progress of C. elegans lipid metabolism-related studies, this review outlined the lipid metabolic processes, the major signaling pathways of fat storage regulation, and the primary experimental methods to assess the lipid content in nematodes. Therefore, this model system holds great promise for facilitating the understanding, management, and therapies of human obesity and other metabolism-related diseases.

Neuronal IRE-1 coordinates an organism-wide cold stress response by regulating fat metabolism

Cold affects many aspects of biology, medicine, agriculture, and industry. Here, we identify a conserved endoplasmic reticulum (ER) stress response, distinct from the canonical unfolded protein response, that maintains lipid homeostasis during extreme cold. We establish that the ER stress sensor IRE-1 is critical for resistance to extreme cold and activated by cold temperature. Specifically, neuronal IRE-1 signals through JNK-1 and neuropeptide signaling to regulate lipid composition within the animal. This cold-response pathway can be bypassed by dietary supplementation with unsaturated fatty acids. Altogether, our findings define an ER-centric conserved organism-wide cold stress response, consisting of molecular neuronal sensors, effectors, and signaling moieties, which control adaptation to cold conditions in the organism. Better understanding of the molecular basis of this stress response is crucial for the optimal use of cold conditions on live organisms and manipulation of lipid saturation homeostasis, which is perturbed in human pathologies.

Astaxanthin Induces Transcriptomic Responses Associated with Lifespan Extension in Caenorhabditis elegans

Astaxanthin is a marine xanthophyll carotenoid which effectively prevents intracellular oxidative stress and has beneficial effects against various human diseases. It has been shown that astaxanthin protects Caenorhabditis elegans (C. elegans) from oxidative damages and extends the lifespan of C. elegans possibly by modulating genes involved in insulin/insulin-like growth factor (IGF) signaling (IIS) and the oxidoreductase system, although the exact mechanisms remain elusive. In this study, RNA sequencing analyses were employed to identify the differentially expressed genes in C. elegans in response to astaxanthin treatment. A total of 190 mRNAs and 6 microRNAs (miRNAs) were significantly changed by astaxanthin treatment in C. elegans. Gene ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that the mRNAs and miRNAs significantly altered by astaxanthin mainly function in innate immunity, lipid metabolism and stress responses, a significant portion of which are related to lifespan regulation in C. elegans. The study revealed novel mRNA and miRNA targets of astaxanthin, providing new insights for understanding the anti-aging mechanisms and the biological function of astaxanthin.

Antioxidant Baccharis trimera Leaf Extract Suppresses Lipid Accumulation in C. elegans Dependent on Transcription Factor NHR-49

Obesity is a global public health problem that is associated with oxidative stress. One of the strategies for the treatment of obesity is the use of drugs; however, these are expensive and have numerous side effects. Therefore, the search for new alternatives is necessary. Baccharis trimera is used in Brazilian folk medicine for the treatment of obesity. Here, B. trimera leaf extract (BT) showed antioxidant activity in seven in vitro tests, and it was not toxic to 3T3 murine fibroblasts or Caenorhabditis elegans. Furthermore, BT reduces the intracellular amount of reactive oxygen species and increases C. elegans survival. Moreover, these effects were not dependent on transcription factors. The inhibition of fat accumulation by BT in the C. elegans model was also investigated. BT reduced lipid accumulation in animals fed diets without or with high amount of glucose. Furthermore, it was observed using RNA interference (iRNA) that BT depends on the transcription factor NHR-49 to exert its effect. Phytochemical analysis of BT revealed rutin, hyperoside, and 5-caffeoylquinic acid as the main BT components. Thus, these data demonstrate that BT has antioxidant and anti-obesity effects. However, further studies should be conducted to understand the mechanisms involved in its action.

Pasteurized Akkermansia muciniphila Reduces Fat Accumulation via nhr-49-Mediated Nuclear Hormone Signaling Pathway in Caenorhabditis elegans

Pasteurized Akkermansia muciniphila (p-AKK) is related to lipid metabolism and helps control obesity. The main goal of this study was to investigate the role and mechanism of p-AKK in lipid metabolism using Caenorhabditis elegans. The results showed that p-AKK increased the healthy lifespan of nematodes and helped maintain exercise ability in aging, suggesting a potential increase in energy expenditure. The overall fat deposition and triglyceride level were significantly decreased and the p-AKK anti-oxidative stress helped to regulate fatty acid composition. Additionally, the transcriptome results showed that p-AKK increased the expression of lipo-hydrolase and fatty acid β-oxidation-related genes, including lipl-4, nhr-49, acs-2 and acdh-8, while it decreased the expression of fat synthesis-related genes, including fat-7, elo-2 and men-1. These results partially explain the mechanisms underlying the fact that p-AKK decreases fat accumulation of C. elegans via nhr-49/acs-2-mediated signaling involved in fatty acid β-oxidation and synthesis.

Lysinibacillus sphaericus mediates stress responses and attenuates arsenic toxicity in Caenorhabditis elegans

Exposure to toxic metals alters host response and that leads to disease development. Studies have revealed the effects of metals on microbial physiology, however, the role of metal resistant bacteria on host response to metals is unclear. The hypothesis that xenobiotic interactions between gut microbes and arsenic influence the host physiology and toxicity was assessed in a Caenorhabditis elegans model. The arsenic-resistant Lysinibacillus sphaericus B1CDA was fed to C. elegans to determine the host responses to arsenic in comparison to Escherichia coli OP50 food. L. sphaericus diet extended C. elegans lifespan compared to E. coli diet, with an increased expression of genes involved in lifespan, stress response and immunity (hif-1, hsp-16.2, mtl-2, abf-2, clec-60), as well as reduced fat accumulation. Arsenic-exposed worms fed L. sphaericus also had a longer lifespan than those fed E. coli and had an increased expression of genes involved in cytoprotection, stress resistance (mtl-1, mtl-2) and oxidative stress response (cyp-35A2, isp-1, ctl-2, sod-1), together with a decreased accumulation of reactive oxygen species (ROS). In comparison with E. coli, L. sphaericus B1CDA diet increased C. elegans fitness while detoxifying arsenic induced ROS and extending lifespan.

Chronic exposure to environmentally relevant levels of di(2-ethylhexyl) phthalate (DEHP) disrupts lipid metabolism associated with SBP-1/SREBP and ER stress in C. elegans

DEHP is commonly found in the environment, biota, food, and humans, raising significant health concerns. Whether developmental stage and exposure duration modify the obesogenic effects of DEHP is unclear, especially the underlying mechanisms by which chronic exposure to DEHP as well as its metabolites remain largely unknown. This study investigated the obesogenic effects of chronic DEHP exposure, with levels below environmentally-relevant amounts and provide the mechanism in Caenorhabditis elegans. We show that early-life DEHP exposure resulted in an increased lipid and triglyceride (TG) accumulation mainly attributed to DEHP itself, not its metabolite mono-2-ethylhexyl phthalate (MEHP). In addition, developmental stage and exposure timing influence DEHP-induced TG accumulation and chronic DEHP exposure resulted in the most significant effect. Analysis of fatty acid composition shows that chronic DEHP exposure altered fatty acid composition and TG, resulting in an increased ω-6/ω-3 ratio. The increased TG content by chronic DEHP exposure required lipogenic genes fat-6, fat-7, pod-2, fasn-1, and sbp-1. Moreover, chronic DEHP exposure induced XBP-1-mediated endoplasmic reticulum (ER) stress which might lead to up-regulation of sbp-1. This study suggests the possible involvement of ER stress and SBP-1/SREBP-mediated lipogenesis in chronic DEHP-induced obesogenic effects. Results from this study implies that chronic exposure to DEHP disrupts lipid metabolism, which is likely conserved across species due to evolutionary conservation of molecular mechanisms, raising concerns in ecological and human health.

Integrated ONT Full-Length Transcriptome and Metabolism Reveal the Mechanism Affecting Ovulation in Muscovy Duck (Cairina moschata)

Ovulation is a complicated physiological process that is regulated by a multitude of different pathways. In comparison to mammalian studies, there are few reports of ovulation in Muscovy ducks, and the molecular mechanism of ovarian development remained unclear. In order to identify candidate genes and metabolites related to Muscovy duck follicular ovulation, the study combined Oxford Nanopore Technologies (ONT) full-length transcriptome and metabolomics to analyze the differences in gene expression and metabolite accumulation in the ovaries between pre-ovulation (PO) and consecutive ovulation (CO) Muscovy ducks. 83 differentially accumulated metabolites (DAMs) were identified using metabolomics analysis, 33 of which are related to lipids. Combined with data from previous transcriptomic analyses found that DEGs and DAMs were particularly enriched in processes including the regulation of glycerophospholipid metabolism pathway, arachidonic acid metabolic pathway and the steroid biosynthetic pathway. In summary, the novel potential mechanisms that affect ovulation in Muscovy ducks may be related to lipid metabolism, and the findings provide new insights into the mechanisms of ovulation in waterfowl and will contribute to a better understanding of changes in the waterfowl ovarian development regulatory network.

Caenorhabditis elegans deep lipidome profiling by using integrative mass spectrometry acquisitions reveals significantly altered lipid networks

Lipidomics coverage improvement is essential for functional lipid and pathway construction. A powerful approach to discovering organism lipidome is to combine various data acquisitions, such as full scan mass spectrometry (full MS), data-dependent acquisition (DDA), and data-independent acquisition (DIA). Caenorhabditis elegans (C. elegans) is a useful model for discovering toxic-induced metabolism, high-throughput drug screening, and a variety of human disease pathways. To determine the lipidome of C. elegans and investigate lipid disruption from the molecular level to the system biology level, we used integrative data acquisition. The methyl-tert-butyl ether method was used to extract L4 stage C. elegans after exposure to triclosan (TCS), perfluorooctanoic acid, and nanopolystyrene (nPS). Full MS, DDA, and DIA integrations were performed to comprehensively profile the C. elegans lipidome by Q-Exactive Plus MS. All annotated lipids were then analyzed using lipid ontology and pathway analysis. We annotated up to 940 lipids from 20 lipid classes involved in various functions and pathways. The biological investigations revealed that when C. elegans were exposed to nPS, lipid droplets were disrupted, whereas plasma membrane-functionalized lipids were likely to be changed in the TCS treatment group. The nPS treatment caused a significant disruption in lipid storage. Triacylglycerol, glycerophospholipid, and ether class lipids were those primarily hindered by toxicants. Finally, toxicant exposure frequently involved numerous lipid-related pathways, including the phosphoinositide 3-kinase/protein kinase B pathway. In conclusion, an integrative data acquisition strategy was used to characterize the C. elegans lipidome, providing valuable biological insights into hypothesis generation and validation.

•

Multiple data acquisitions were used to profile the lipidome of C. elegans.

•

940 detected lipids of 20 main classes involved in various pathways.

•

Relevant hypotheses were generated using high-coverable lipidomics and pathways analysis.

Intermittent multi-generational effects of 1-hexyl-3-methylimidazolium nitrate on Caenorhabditis elegans mediated by lipid metabolism

Ionic liquids (ILs) become environmental pollutants. Their environmental toxicities included inhibitory effects, stimulatory ones and hormesis combining both aspects on various organisms. However, the mechanisms still need systematic investigations. Presently, 1-hexyl-3-methylimidazolium nitrate ([Hmim]NO₃) was chosen as one representative IL. Its effects on lifespan and reproduction were studied on C. elegans with lipid metabolism as the potential mechanism. Two types (A and B) intermittent multi-generational exposure arrangements were set up to mimic realistic ILs exposure scenarios. Type A arrangement had exposure in F1, F5 and F9 with recovery in T2-T4, T6-T8 and T10-T12, and type B arrangement had exposure in F1, F3, F5, F7, F9 and F11 with recovery in T2, T4, T6, T8, T10 and T12. In type A exposure, the effects of [Hmim]NO₃ on reproduction were 1.32-, 1.68-, 1.23-, 0.96-, 1.68-, 1.07-, 1.25-, 1.64-, 1.31-, 1.11-, 0.89- and 1.02-fold of the control in F1, T2-T4, F5, T6-T8, F9, T10-T12, respectively. The results showed oscillation between stimulatory and inhibitory effects. In type B exposure, the effects showed fewer inhibitions and more stimulations across generations. Moreover, the effects on reproduction showed trade-off relationships with lifespan, and the trade-off was more obvious in type B exposure. Further biochemical and gene expression analysis showed that lipid metabolism was closely related with lifespan and reproduction in type A exposure, but it was connected with cholesterol synthesis in type B exposure. The results demonstrated different strategies in the biological responses to the two arrangements of intermittent multi-generational exposure.

Rapid Lipid Quantification in Caenorhabditis elegans by Oil Red O and Nile Red Staining

The ability to stain lipid stores in vivo allows for the facile assessment of metabolic status in individuals of a population following genetic and environmental manipulation or pharmacological treatment. In the animal model Caenorhabditis elegans, lipids are stored in and mobilized from intracellular lipid droplets in the intestinal and hypodermal tissues. The abundance, size, and distribution of these lipids can be readily assessed by two staining methods for neutral lipids: Oil Red O (ORO) and Nile Red (NR). ORO and NR can be used to quantitatively measure lipid droplet abundance, while ORO can also define tissue distribution and lipid droplet size. C. elegans are a useful animal model in studying pathways relating to aging, fat storage, and metabolism, as their transparent nature allows for easy microscopic assessment of lipid droplets. This is done by fixation and permeabilization, staining with NR or ORO, image capture on a microscope, and computational identification and quantification of lipid droplets in individuals within a cohort. To ensure reproducibility in lipid measurements, we provide a detailed protocol to measure intracellular lipid dynamics in C. elegans. Graphic abstract: Flow chart depicting the preparation of C. elegans for fat staining protocols.

Graphene Nanoplatelets: In Vivo and In Vitro Toxicity, Cell Proliferative Activity, and Cell Gene Expression

Multi-layer graphene (2–10 layers), also called graphene nanoplatelets (GNPs), is a carbon-based nanomaterial (CBN) type with excellent properties desirable for many biomedical applications. Despite the promising advantages reported of GNPs, nanoscale materials may also present a potential hazard to humans. Therefore, in this study, the in vivo toxicity of these nanomaterials at a wide range of concentrations from 12.5 to 500 µg/mL was evaluated in the Caenorhabditis elegans model for 24 h (acute toxicity) and 72 h (chronic toxicity). Furthermore, their in vitro toxicity (from 0 to 10 µg/mL for 12 and 24 h), proliferative activity at 72 and 96 h, and their effect on the expression of thirteen genes in human keratinocytes HaCaT cells were studied. The physico-chemical and morphological aspects of the GNPs used in this study were analyzed by Raman scattering spectroscopy, electron microscopy, zeta potential as a function of pH, and particle size measurements by dynamic light scattering. The results of this study showed that GNPs showed in vivo non-toxic concentrations of 25 and 12.5 µg/mL for 24 h, and at 12.5 µg/mL for 72 h. Moreover, GNPs present time-dependent cytotoxicity (EC50 of 1.142 µg/mL and 0.760 µg/mL at 12 h and 24 h, respectively) and significant proliferative activity at the non-toxic concentrations of 0.005 and 0.01 μg/mL in the HaCaT cell line. The gene expression study showed that this multi-layer-graphene is capable of up-regulating six of the thirteen genes of human keratinocytes (SOD1, CAT, TGFB1, FN1, CDH1, and FBN), two more genes than other CBNs in their oxidized form such as multi-layer graphene oxide. Therefore, all these results reinforce the promising use of these CBNs in biomedical fields such as wound healing and skin tissue engineering.

Lipidome reveals the alleviation of krill oil on the impairment of acrylamide

Krill oil has rich content of polyunsaturated fatty acids and various biological functions. Previous researches have demonstrated that krill oil is helpful to improve the locomotion via antioxidation and regulation...

Non-Woven Infection Prevention Fabrics Coated with Biobased Cranberry Extracts Inactivate Enveloped Viruses Such as SARS-CoV-2 and Multidrug-Resistant Bacteria

The Coronavirus Disease (COVID-19) pandemic is demanding the rapid action of the authorities and scientific community in order to find new antimicrobial solutions that could inactivate the pathogen SARS-CoV-2 that causes this disease. Gram-positive bacteria contribute to severe pneumonia associated with COVID-19, and their resistance to antibiotics is exponentially increasing. In this regard, non-woven fabrics are currently used for the fabrication of infection prevention clothing such as face masks, caps, scrubs, shirts, trousers, disposable gowns, overalls, hoods, aprons and shoe covers as protective tools against viral and bacterial infections. However, these non-woven fabrics are made of materials that do not exhibit intrinsic antimicrobial activity. Thus, we have here developed non-woven fabrics with antimicrobial coatings of cranberry extracts capable of inactivating enveloped viruses such as SARS-CoV-2 and the bacteriophage phi 6 (about 99% of viral inactivation in 1 min of viral contact), and two multidrug-resistant bacteria: the methicillin-resistant Staphylococcus aureus and the methicillin-resistant Staphylococcus epidermidis. The morphology, thermal and mechanical properties of the produced filters were characterized by optical and electron microscopy, differential scanning calorimetry, thermogravimetry and dynamic mechanical thermal analysis. The non-toxicity of these advanced technologies was ensured using a Caenorhabditis elegans in vivo model. These results open up a new prevention path using natural and biodegradable compounds for the fabrication of infection prevention clothing in the current COVID-19 pandemic and microbial resistant era.

mmBCFA C17iso ensures endoplasmic reticulum integrity for lipid droplet growth

In eukaryote cells, lipid droplets (LDs) are key intracellular organelles that dynamically regulate cellular energy homeostasis. LDs originate from the ER and continuously contact the ER during their growth. How the ER affects LD growth is largely unknown. Here, we show that RNAi knockdown of acs-1, encoding an acyl-CoA synthetase required for the biosynthesis of monomethyl branched-chain fatty acids C15iso and C17iso, remarkably prevented LD growth in Caenorhabditis elegans. Dietary C17iso, or complex lipids with C17iso including phosphatidylcholine, phosphatidylethanolamine, and triacylglycerol, could fully restore the LD growth in the acs-1RNAi worms. Mechanistically, C17iso may incorporate into phospholipids to ensure the membrane integrity of the ER so as to maintain the function of ER-resident enzymes such as SCD/stearoyl-CoA desaturase and DGAT2/diacylglycerol acyltransferase for appropriate lipid synthesis and LD growth. Collectively, our work uncovers a unique fatty acid, C17iso, as the side chain of phospholipids for determining the ER homeostasis for LD growth in an intact organism, C. elegans.

Polysaccharides from Volvariella volvacea inhibit fat accumulation in C. elegans dependent on the aak-2/nhr-49-mediated pathway

Volvariella volvacea has bioactivities in improving immunity, anti-oxidation, and alleviating obesity, which is an excellent functional food. Polysaccharide from Volvariella volvacea (VPS), one of the main bioactive components, exerts a potential fat-lowering effect, but its exact mechanism remains unclear. In this study, the effects and molecular pathways of VPS regulate the fat deposition of Caenorhabditis elegans. Results showed that VPS at low (250 μg/ml), medium (500 μg/ml) and high (750 μg/ml) concentrations all reduced the overall fat, without inhibitory effects on the growth and movement abilities of nematode. VPS at 500 μg/ml could dramatically decrease the triglyceride (TG) level of wild-type nematode, while no significant changes in TG content were observed in mutants deficient in aak-2 (energy receptor), nhr-49 (nuclear transcription factor), fat-5, and fat-7 genes. VPS declines fat storage of C. elegans, largely through the aak-2/nhr-49-mediated fatty acid synthesis pathway, and partially the acs-2-mediated fatty acid oxidation pathway. PRACTICAL APPLICATIONS: A model illustrates the mechanism of polysaccharide from Volvariella volvacea (VPS) inhibiting fat accumulation in Caenorhabditis elegans. VPS may directly or indirectly activate the energy sensor aak-2, which governs lipid metabolism. Results demonstrate that VPS regulates fat metabolism including fatty acid oxidation (FAO) and fatty acid synthesis (FAS), rather than lipolysis. In the FAO, VPS promotes FAO by up-regulating the mRNA and protein levels of acs-2. In FAS, VPS significantly down-regulated the transcriptional regulator nhr-49 and the downstream targets fat-5, fat-6, and fat-7, thereby declining the overall fat deposition. In conclusion, VPS inhibits the fat accumulation of C. elegans largely dependent on an aak-2/nhr-49-mediated FAS pathway.

The Mitochondrial Prohibitin (PHB) Complex in C. elegans Metabolism and Ageing Regulation

The mitochondrial prohibitin (PHB) complex, composed of PHB-1 and PHB-2, is an evolutionarily conserved context-dependent modulator of longevity. This extremely intriguing phenotype has been linked to alterations in mitochondrial function and lipid metabolism. The true biochemical function of the mitochondrial PHB complex remains elusive, but it has been shown to affect membrane lipid composition. Recent work, using large-scale biochemical approaches, has highlighted a broad effect of PHB on the C. elegans metabolic network. Collectively, the biochemical data support the notion that PHB modulates, at least partially, worm longevity through the moderation of fat utilisation and energy production via the mitochondrial respiratory chain. Herein, we review, in a systematic manner, recent biochemical insights into the impact of PHB on the C. elegans metabolome.

Effect of fluensulfone on different functional genes of root-knot nematode Meloidogyne incognita

Meloidogyne incognita is an obligate plant-parasitic nematode causing serious damage to agricultural crops. Major constraints in nematode management arose due to the limited availability of non-fumigant nematicides in conjunction with the considerable ill effects of fumigants on human and non-target organisms. Recently, fluensulfone has been reported to be an effective non-fumigant nematicide against plant-parasitic nematodes and the model nematode Caenorhabditis elegans. The nematicidal efficacy varies according to its concentration at the time of application, exposure timing, nematode species variability, and even across subpopulations within the same species. It interferes with the key physiological processes of nematodes, like motility, behavior, chemosensation, stylet thrusting, infectivity, metabolism, lipid consumption, tissue integrity, oviposition, egg hatching, and survival. However, the molecular basis of these multivariate physiological anomalies is still largely unknown. Quantitative real-time PCR was carried out to understand the acute transcriptional perturbation of 30 functional genes associated with key physiological and life processes in a M. incognita population, following exposure of 10, 50, and 100 ppm of fluensulfone for 5 and 10 hr. The chemical treatment resulted in significant downregulation of all the neuropeptidergic genes, with concomitant repression of majority of genes related to chemosensation, esophageal gland secretion, parasitism, fatty acid metabolism, and G-protein coupled receptors. Collectively, the parasitism genes were found to be perturbed at highest magnitude, followed by the GPCRs and neuropeptidergic genes. These results establish the wide ranging effect of fluensulfone on various metabolic and physiological pathways of nematode.

Azelaic Acid Promotes Caenorhabditis elegans Longevity at Low Temperature Via an Increase in Fatty Acid Desaturation

PURPOSE

Azelaic acid (AzA) is a dicarboxylic acid naturally occurring in various grains having anti-inflammatory and anti-oxidation properties. Recently, AzA is shown to reduce high-fat diet-induced adiposity in animals. However, its physiological role in lipid metabolism and aging in various environmental stresses is unknown.

METHODS AND RESULTS

Using C. elegans as an invertebrate animal model, we demonstrate that AzA suppresses fat accumulation with no effect on lifespan at normal temperatures. Moreover, AzA promotes lifespan at low temperatures by elevation of unsaturated long-chain fatty acids and expression of genes in fatty acid desaturation. We further find that genes encoding fatty acid desaturases such as fat-1, fat-5, fat-6, and fat-7 are crucial for the lifespan-extending effect of AzA at low temperature.

CONCLUSIONS

Taken together, our results suggest that AzA promotes adaption to low temperature in C. elegans via shifting fatty acid profile to unsaturated long-chain fatty acids.

Beyond Proteostasis: Lipid Metabolism as a New Player in ER Homeostasis

Biological membranes are not only essential barriers that separate cellular and subcellular structures, but also perform other critical functions such as the initiation and propagation of intra- and intercellular signals. Each membrane-delineated organelle has a tightly regulated and custom-made membrane lipid composition that is critical for its normal function. The endoplasmic reticulum (ER) consists of a dynamic membrane network that is required for the synthesis and modification of proteins and lipids. The accumulation of unfolded proteins in the ER lumen activates an adaptive stress response known as the unfolded protein response (UPR-ER). Interestingly, recent findings show that lipid perturbation is also a direct activator of the UPR-ER, independent of protein misfolding. Here, we review proteostasis-independent UPR-ER activation in the genetically tractable model organism Caenorhabditis elegans. We review the current knowledge on the membrane lipid composition of the ER, its impact on organelle function and UPR-ER activation, and its potential role in human metabolic diseases. Further, we summarize the bi-directional interplay between lipid metabolism and the UPR-ER. We discuss recent progress identifying the different respective mechanisms by which disturbed proteostasis and lipid bilayer stress activate the UPR-ER. Finally, we consider how genetic and metabolic disturbances may disrupt ER homeostasis and activate the UPR and discuss how using -omics-type analyses will lead to more comprehensive insights into these processes.

Benzo[a]pyrene and Caenorhabditis elegans: defining the genotoxic potential in an organism lacking the classical CYP1A1 pathway

Benzo[a]pyrene (BaP) is bioactivated in most organisms by the cytochrome P450 (CYP) enzymes, mainly CYP1A1, ultimately resulting in the reactive metabolite BaP-7,8-dihydrodiol-9,10-epoxide (BPDE) capable of covalently binding to DNA and forming adducts. This step has been defined as the key process in cancer initiation in humans. However, limited knowledge is available about the consequences of BaP exposure in organisms lacking this classical CYP1A1 pathway, one example is the model nematode Caenorhabditis elegans. The aim of this study was to define the genotoxic potential of BaP in C. elegans and to advance our understanding of xenobiotic processing in the absence of the CYP1A1 pathway. Exposure to high concentrations of BaP (0-40 µM) significantly affected life cycle endpoints of C. elegans, which were manifested by a reduced reproductive output and shortened life span. An optimised comet assay revealed that DNA damage increased in a dose-dependent manner; however, no bulky DNA adducts (dG-N²-BPDE) were observed by ³²P-postlabelling. Global transcriptomic analysis by RNA-Seq identified responsive transcript families, most prominently members of the cyp-35 and UDP-glucuronosyltransferases (UGTs) enzyme families, both of which are linked to xenobiotic metabolism. Strains harbouring mutations in the cyp-35A2 and cyp-35A3 genes were notably less prone to BaP-mediated toxicity, and BaP led to longevity in cyp-35A5 mutants. In summary, BaP induces transcriptional, genotoxic and phenotypic responses in C. elegans, despite the absence of the classical CYP1A1 bioactivation pathway. This provides first evidence that parallel pathways are implicated in BaP metabolism in C. elegans and this seems to be mediated via the cyp-35 pathway.

Tissue-Specific Transcription Footprinting Using RNA PoI DamID (RAPID) in Caenorhabditis elegans

Differential gene expression across cell types underlies development and cell physiology in multicellular organisms. Caenorhabditis elegans is a powerful, extensively used model to address these biological questions. A remaining bottleneck relates to the difficulty to obtain comprehensive tissue-specific gene transcription data, since available methods are still challenging to execute and/or require large worm populations. Here, we introduce the RNA Polymerase DamID (RAPID) approach, in which the Dam methyltransferase is fused to a ubiquitous RNA polymerase subunit to create transcriptional footprints via methyl marks on the DNA of transcribed genes. To validate the method, we determined the polymerase footprints in whole animals, in sorted embryonic blastomeres and in different tissues from intact young adults by driving tissue-specific Dam fusion expression. We obtained meaningful transcriptional footprints in line with RNA-sequencing (RNA-seq) studies in whole animals or specific tissues. To challenge the sensitivity of RAPID and demonstrate its utility to determine novel tissue-specific transcriptional profiles, we determined the transcriptional footprints of the pair of XXX neuroendocrine cells, representing 0.2% of the somatic cell content of the animals. We identified 3901 candidate genes with putatively active transcription in XXX cells, including the few previously known markers for these cells. Using transcriptional reporters for a subset of new hits, we confirmed that the majority of them were expressed in XXX cells and identified novel XXX-specific markers. Taken together, our work establishes RAPID as a valid method for the determination of RNA polymerase footprints in specific tissues of C. elegans without the need for cell sorting or RNA tagging.

Kahweol Reduces Food Intake of Caenorhabditis elegans

The coffee diterpene kahweol may contribute to the anti-obesity effects of coffee but its physiological effects have yet to be elucidated. Caenorhabditis elegans is used as an animal model in obesity research because its lipid metabolism is conserved in humans. The goal was to investigate kahweol's effects on lipid metabolism in C. elegans. Kahweol at 120 μM reduced fat accumulation by 17% compared to the control, which was associated with a reduced food intake. Kahweol did not reduce fat in eat-2 mutants, which have a disrupted pharynx contraction rate, suggesting that the fat-lowering effects of kahweol were dependent on food intake. Lipid metabolism-related gene homologues of tubby protein (tub-1), enoyl-CoA hydratase (ech-1.1), adipose triglyceride lipase (atgl-1), insulin/insulin-like growth receptor (daf-2), and forkhead box O transcription factor (daf-16) were also associated with changes in food intake by kahweol. Therefore, kahweol's fat-lowering effects are due to a reduction of food intake in C. elegans.

In vitro and in vivo lipidomics as a tool for probiotics evaluation

The probiotic bacteria are helpful for nutritional and therapeutic purposes, and they are commercially available in various forms, such as capsules or powders. Increasing pieces of evidence indicate that different growth conditions and variability in manufacturing processes can determine the properties of probiotic products. In recent years, the lipidomic approach has become a useful tool to evaluate the impact that probiotics induce in host physiology. In this work, two probiotic formulations with identical species composition, produced in two different sites, the USA and Italy, were utilized to feed Caenorhabditis elegans, strains and alterations in lipid composition in the host and bacteria were investigated. Indeed, the multicellular organism C. elegans is considered a simple model to study the in vivo effects of probiotics. Nematodes fat metabolism was assessed by gene expression analysis and by mass spectrometry-based lipidomics. Lipid droplet analysis revealed a high accumulation of lipid droplets in worms fed US-made products, correlating with an increased expression of genes involved in the fatty acid synthesis. We also evaluated the lifespan of worms defective in genes involved in the insulin/IGF-1-mediated pathway and monitored the nuclear translocation of DAF-16. These data demonstrated the involvement of the signaling in C. elegans responses to the two diets. Lipidomics analysis of the two formulations was also conducted, and the results indicated differences in phosphatidylglycerol (PG) and phosphatidylcholine (PC) contents that, in turn, could influence nematode host physiology. Results demonstrated that different manufacturing processes could influence probiotics and host properties in terms of lipid composition. KEY POINTS: • Probiotic formulations impact on Caenorhabditis elegans lipid metabolism; • Lipidomic analysis highlighted phospholipid abundance in the two products; • Phosphocholines and phosphatidylglycerols were analyzed in worms fed the two probiotic formulations.

C. elegans ACAT regulates lipolysis and its related lifespan in fasting through modulation of the genes in lipolysis and insulin/IGF-1 signaling

Overly active acyl-coenzyme A: cholesterol acyltransferases (ACATs) are known to contribute to the development of atherosclerosis, cancer cell proliferation and de novo lipogenesis. However, the role of ACAT in systemic lipid metabolism and its consequence of aging is unknown. Using avasimibe, a clinically proven ACAT inhibitor, and mboa-1 mutant strain, a homologous to mammalian ACAT, herein, we found that Ava treatment and mboa-1 mutant exhibited a decreased fat accumulation during feeding and increased lipolysis with extended lifespan of C. elegans during fasting. Our study highlights the essential role of ACAT inhibitor and mboa-1 in fat mobilization and the survival of C. elegans in fasting through the modulation of the genes involved in lipolysis and insulin/IGF-1 signaling.

De novo assembly of transcriptome and genome-wide identification reveal GA3 stress-responsive WRKY transcription factors involved in fiber formation in jute (Corchorus capsularis)

BACKGROUND

WRKY is a group of transcription factors (TFs) that play a vital role in plant growth, development, and stress tolerance. To date, none of jute WRKY (CcWRKY) genes have been identified, even if jute (Corchorus capsularis) is one of the most important natural fiber crops in the world. Little information about the WRKY genes in jute is far from sufficient to understand the molecular mechanism of bast fiber biosynthesis.

RESULTS

A total of 244,489,479 clean reads were generated using Illumina paired-end sequencing. De novo assembly yielded 90,982 unigenes with an average length of 714 bp. By sequence similarity searching for known proteins, 48,896 (53.74%) unigenes were annotated. To mine the CcWRKY TFs and identify their potential function, the search for CcWRKYs against the transcriptome data of jute was performed, and a total of 43 CcWRKYs were identified in this study. The gene structure, phylogeny, conserved domain and three-dimensional structure of protein were analyzed by bioinformatics tools of GSDS2.0, MEGA7.0, DNAMAN5.0, WebLogo 3 and SWISS-MODEL respectively. Phylogenetic analysis showed that 43 CcWRKYs were divided into three groups: I, II and III, containing 9, 28, and 6 members respectively, according to the WRKY conserved domain features and the evolution analysis with Arabidopsis thaliana. Gene structure analysis indicated that the number of exons of these CcWRKYs varied from 3 to 11. Among the 43 CcWRKYs, 10, 2, 2, and 14 genes showed higher expression in leaves, stem sticks, stem barks, and roots at the vigorous vegetative growth stage, respectively. Moreover, the expression of 21 of 43 CcWRKYs was regulated significantly with secondary cell wall biosynthesis genes using FPKM and RT-qPCR by GA₃ stress to a typical GA₃ sensitive dwarf germplasm in comparison to an elite cultivar in jute. The Cis-element analysis showed that promoters of these 21 CcWRKYs had 1 to 4 cis-elements involved in gibberellin-responsiveness, suggesting that they might regulate the development of bast fiber in response to GA₃ stress.

CONCLUSIONS

A total of 43 CcWRKYs were identified in jute for the first time. Analysis of phylogenetic relationship and gene structure revealed that these CcWRKYs might have a functional diversity. Expression analysis showed 21 TFs as GA₃ stress responsive genes. The identification of these CcWRKYs and the characterization of their expression pattern will provide a basis for future clarification of their functions in bast fiber development in jute.

Butein inhibits lipogenesis in Caenorhabditis elegans

Butein, a flavonoid found in annatto seeds and lacquer trees, may be used for many health benefits, including the prevention of obesity. However, its anti-obesity effects are not completely understood; in particular, the effects of butein on the regulation of lipid metabolism have not been explained. Thus, the goal of the current study was to determine the effects of butein on lipid metabolism in Caenorhabditis elegans, which is a multi-organ nematode used as an animal model in obesity research. Butein at 70 μM reduced triglyceride content by 27% compared to the control without altering food intake and energy expenditure. The reduced triglyceride content by butein was associated with the downregulation of sbp-1, fasn-1, and fat-7, the lipogenesis-related homologs of sterol regulatory element-binding proteins, fatty acid synthase and stearoyl-CoA desaturase, respectively. Furthermore, fat-7 and skn-1, a homolog of nuclear respiratory factors, were identified as genetic requirements for butein's effects on triglyceride content in C. elegans. The effects of butein on sbp-1 and fasn-1 were dependent on skn-1, but the downregulation of fat-7 was independent of skn-1. These results suggest that the inhibitory effects of butein on lipogenesis are via SKN-1- and FAT-7-dependent pathways in C. elegans.

Stress sensor Ire1 deploys a divergent transcriptional program in response to lipid bilayer stress

Membrane integrity at the endoplasmic reticulum (ER) is tightly regulated, and its disturbance is implicated in metabolic diseases. Using an engineered sensor that activates the unfolded protein response (UPR) exclusively when normal ER membrane lipid composition is compromised, we identified pathways beyond lipid metabolism that are necessary to maintain ER integrity in yeast and in C. elegans. To systematically validate yeast mutants that disrupt ER membrane homeostasis, we identified a lipid bilayer stress (LBS) sensor in the UPR transducer protein Ire1, located at the interface of the amphipathic and transmembrane helices. Furthermore, transcriptome and chromatin immunoprecipitation analyses pinpoint the UPR as a broad-spectrum compensatory response wherein LBS and proteotoxic stress deploy divergent transcriptional UPR programs. Together, these findings reveal the UPR program as the sum of two independent stress responses, an insight that could be exploited for future therapeutic intervention.

New Roles for the Heterochronic Transcription Factor LIN-29 in Cuticle Maintenance and Lipid Metabolism at the Larval-to-Adult Transition in Caenorhabditis elegans

Temporal regulation of gene expression is a crucial aspect of metazoan development. In the roundworm Caenorhabditis elegans, the heterochronic pathway controls multiple developmental events in a time-specific manner. The most downstream effector of this pathway, the zinc-finger transcription factor LIN-29, acts in the last larval stage (L4) to regulate elements of the larval-to-adult switch. Here, we explore new LIN-29 targets and their implications for this developmental transition. We used RNA-sequencing to identify genes differentially expressed between animals misexpressing LIN-29 at an early time point and control animals. Among 230 LIN-29-activated genes, we found that genes encoding cuticle collagens were overrepresented. Interestingly, expression of lin-29 and some of these collagens was increased in adults with cuticle damage, suggesting a previously unknown function for LIN-29 in adult cuticle maintenance. On the other hand, genes involved in fat metabolism were enriched among 350 LIN-29-downregulated targets. We used mass spectrometry to assay lipid content in animals overexpressing LIN-29 and observed reduced fatty acid levels. Many LIN-29-repressed genes are normally expressed in the intestine, suggesting cell-nonautonomous regulation. We identified several LIN-29 upregulated genes encoding signaling molecules that may act as mediators in the regulation of intestinally expressed genes encoding fat metabolic enzymes and vitellogenins. Overall, our results support the model of LIN-29 as a major regulator of adult cuticle synthesis and integrity, and as the trigger for metabolic changes that take place at the important transition from rapid growth during larval life to slower growth and offspring production during adulthood.

Effects of excess sugars and lipids on the growth and development of Caenorhabditis elegans

Background

Excessive intake of carbohydrates and fats causes over-nutrition, leading to a variety of diseases and complications. Here, we characterized the effects of different types of sugar and lipids on the growth and development of Caenorhabditis elegans.

Methods

We measured the lifespan, reproductive capacity, and length of nematodes after sugars and lipids treatment alone and co-treatment of sugars and lipids. Furthermore, we studied the mechanisms underlying the damage caused by high-sucrose and high-stearic acid on C.elegans by using transcriptome sequencing technology.

Results

The results showed that a certain concentration of sugar and lipid promoted the growth and development of nematodes. However, excessive sugars and lipids shortened the lifespan and length of nematodes and destroyed their reproductive capacity. Based on the results of the orthogonal test, we selected 400 mmol/L sucrose and 500 μg/mL stearic acid to model a high-sugar and high-lipid diet for C. elegans.

Conclusion

High-sugar and high-lipid intake altered the expression of genes involved in biofilm synthesis, genes that catalyze the synthesis and degradation of endogenous substances, and genes involved in innate immunity, resulting in physiological damage. Furthermore, we explored the protective effect of resveratrol on high-sugar and high-lipid damage to nematodes. Resveratrol plays a role in repairing by participating in the metabolism of foreign substances and reducing cellular oxidative stress.