Project description:Sphingolipids are important lipids and integral members of membranes, where they form small microdomains called lipid rafts. These rafts are enriched in cholesterol and sphingolipids, which influences biophysical properties. Interestingly, the membranes of the biomedical model organism Caenorhabditis elegans contain only low amounts of cholesterol. Sphingolipids in C. elegans are based on an unusual C17iso branched sphingoid base. In order to analyze and the sphingolipidome of C. elegans in more detail, we performed fractionation of lipid extracts and depletion of glycero- and glycerophospholipids together with in-depth analysis using UPLC-UHR-ToF-MS. In total we were able to detect 82 different sphingolipids from different classes, including several isomeric species.
Project description:The nematode Caenorhabditis elegans has evolutionarily conserved EV signaling pathways. In this study, we apply a recently published method for high specificity purification of EVs from C. elegans to carry out target-independent proteomic and RNA analysis of EVs from C. elegans. Our experiments uncovered diverse coding and non-coding RNA transcripts as well as protein cargo types commonly found in human EVs.
Project description:SEIPIN, an evolutionary conserved protein, plays pivotal roles during lipid droplet (LD) biogenesis and is associated with various human diseases with unclear mechanisms. Here, we analyzed C. elegans mutants deleted of the sole SEIPIN gene, seip-1. Homozygous seip-1 mutants displayed penetrant embryonic lethality, which is caused by the disruption of the lipid-rich permeability barrier, the innermost layer of the C. elegans embryonic eggshell. In C. elegans oocytes and embryos, SEIP-1 is associated with LDs and crucial for controlling LD size and lipid homeostasis. The seip-1 deletion mutants reduced the ratio of polyunsaturated fatty acids (PUFAs) in their embryonic fatty acid pool. Interestingly, dietary supplementation of selected n-6 PUFAs rescued the embryonic lethality and defective permeability barrier. Accordingly, we propose that SEIP-1 may maternally regulate LD biogenesis and lipid homeostasis to orchestrate the formation of the permeability barrier for eggshell synthesis during embryogenesis. A lipodystrophy allele of seip-1 resulted in embryonic lethality as well and could be rescued by PUFA supplementation. These experiments support a great potential for using C. elegans to model seipin-associated human diseases.
Project description:Lipid identification is a major bottleneck in high-throughput lipidomics studies. We combined the in silico fragmentation tool MetFrag with LipidMaps lipid-class specific classifiers which calculate probabilities for lipid class assignments. The LipidFrag approach was then applied to MS/MS spectra of lipid extracts of the nematode Caenorhabditis elegans.
Project description:Much of posttranscriptional mRNA regulation occurs through cis-acting sequences in mRNA 3´ untranslated regions (UTRs), which interact with specific proteins and ribonucleoprotein complexes that modulate translation, mRNA stability and subcellular localization. Studies in Caenorhabditis elegans have revealed indispensable roles for 3´UTR-mediated gene regulation, yet most C. elegans genes have lacked annotated 3´UTRs. Here we describe a high-throughput method to reliably identify 3´ ends of polyadenylated RNAs. This method, called poly(A)-position profiling by sequencing (3P-Seq), was used to determine the UTRs of C. elegans. Compared to standard methods also recently applied to C. elegans UTRs, 3P-Seq identified 8775 additional UTRs while excluding thousands of shorter UTR isoforms that do not appear to be authentic. Analysis of this expanded and corrected dataset indicated that the high A/U content of C. elegans 3´UTRs facilitated genome compaction, since the elements specifying cleavage and polyadenylation, which are A/U-rich, can more readily emerge in A/U rich regions. Indeed, 30% of the protein-coding genes have mRNAs with alternative, partially overlapping end regions that generate another 10,000 cleavage and polyadenylation sites that had gone largely unnoticed and represent potential evolutionary intermediates of progressive UTR shortening. Moreover, a third of the convergently transcribed genes utilize palindromic arrangements of bidirectional elements to specify UTRs with convergent overlap, which also contributes to genome compaction by eliminating regions between genes. Although nematode 3´UTRs have median length only one-sixth that of mammalian 3´UTRs, they have twice the density of conserved microRNA sites, in part because additional types of seed-complementary sites are preferentially conserved. These findings reveal the influence of cleavage and polyadenylation on the evolution of genome architecture and provide resources for studying posttranscriptional gene regulation. Nine samples (10 sequencing runs) from various mixed and specific stages of wild-type Caenorhabditis elegans and glp-4 mutant adults.