Development of a nano-size off-grid energy system using renewables and IoT technologies at the Meteoria visitor center: A Finnish case study.

The increased utilization of non-renewable energy during the last century has influenced the climate, with increased carbon dioxide emissions and elevated temperature as a result. Thus, the need to develop and demonstrate new sustainable solutions regarding both energy supply and consumption, but also energy system optimization, is obvious. This case study presents the nano-size off-grid energy system at the Meteoria visitor center in Ostrobothnia, Finland, and the real-time measuring techniques that have been installed to follow up the energy production and consumption. The Meteoria consists of several buildings, which are open to the public from April to October. The case site is operated by energy derived from wind power, solar power, and a diesel generator (as a backup), with batteries for energy storage. The Internet of Things (IoT) has been retrofitted to the existing energy system to enable energy measurements and follow various electrical parameters in real-time. In addition, a graphical visualization platform open to the public has been developed. In this study, the completeness of data sampling and the IoT system was checked, and the results show high availability of data. Furthermore, various errors/limitations regarding the IoT system were identified. The energy supply/demand at the Meteoria in 2021 was monitored and the challenges regarding the existing energy system in a cold climate zone are discussed as well as the potential role of the Meteoria to function as a living lab.

Membranes and mammalian glycolipid transferring proteins.

Glycolipids are synthesized in and on various organelles throughout the cell. Their trafficking inside the cell is complex and involves both vesicular and protein-mediated machineries. Most important for the bulk lipid transport is the vesicular system, however, lipids moved by transfer proteins are also becoming more characterized. Here we review the latest advances in the glycolipid transfer protein (GLTP) and the phosphoinositol 4-phosphate adaptor protein-2 (FAPP2) field, from a membrane point of view.

The intermembrane ceramide transport catalyzed by CERT is sensitive to the lipid environment.

The in vitro activity of the ceramide transporter, CERT has been studied using a fluorescence assay. CERT is responsible for the in vivo non-vesicular trafficking of ceramide between the endoplasmic reticulum and Golgi. In this study we have examined how the membrane environment surrounding the ceramide substrate, the membrane packing density and the membrane charge, are affecting the ceramide transfer activity. To examine this we have used an anthrylvinyl-labeled ceramide analogue. We found that if ceramide is in a tightly packed environment such as in sphingomyelin or dipalmitoylphosphatidylcholine containing membranes, the CERT transfer activity is markedly reduced. Ceramide in fluid membranes on the other hand are available for CERT mediated transfer. CERT also favors membranes that contain phosphatidylinositol 4-monophospate, due to its binding capacity of the pleckstrin homology domain towards phosphatidylinositol 4-monophospate. From this study we conclude that the membrane matrix surrounding ceramide, that is ceramide miscibility, is largely affecting the transfer activity of CERT.

The glycolipid transfer protein interacts with the vesicle-associated membrane protein-associated protein VAP-A.

The glycolipid transfer protein (GLTP) is a cytoplasmic protein with an ability to bind glycolipids and catalyze their in vitro transfer. In this study, we have found a FFAT-like motif in GLTP. The FFAT (two phenylalanines in an acidic tract) motif in lipid-binding proteins has previously been shown to interact with the VAPs (vesicle-associated membrane protein-associated proteins) in the endoplasmic reticulum. Here we used glutathione S-transferase pull-down experiments to confirm that GLTP and VAP-A interact. By displacing different amino acids in the motif we clearly show that the interaction is dependent on the FFAT-like motif in GLTP. The potential role of GLTP in the endoplasmic reticulum association is discussed.

Human glycolipid transfer protein--intracellular localization and effects on the sphingolipid synthesis.

Glycolipid transfer proteins (GLTPs) are small proteins that specifically transfer glycolipids from one bilayer membrane to another in vitro. However, the precise biological function is still unknown. In this study the intracellular distribution of GLTP was determined. We have used several independent methods, including differential and discontinuous density gradient centrifugation, plasma membrane permeabilization and confocal microscopy imaging, and we demonstrate that GLTP has a cytosolic location. The GLTP is not located in the Golgi apparatus, endoplasmic reticulum, nucleus, lysosomes, mitochondria or peroxisomes in HeLa cells. We have also used a fluorescence resonance energy transfer assay to detect transfer of fluorescently labeled BODIPY-glucosylceramide in the cytosolic fraction from both wild-type and GLTP-overexpressing HeLa cells. Furthermore, we have studied de novo sphingolipid changes in cells overexpressing GLTP using sphinganine metabolic labeling. The results show a significant increase in the synthesis of glucosylceramide (GlcCer) and a decrease in the sphingomyelin (SM) synthesis. However, no changes were detected in the de novo sphingolipid synthesis in GLTP-knockdown cells compared to control cells. We propose that GLTP is not likely involved in the de novo synthesis of glycosphingolipids, but could rather have a role as a glycolipid sensor for the cellular levels of glucosylceramide.

Characterization of SCP-2 from Euphorbia lagascae reveals that a single Leu/Met exchange enhances sterol transfer activity.

Sterol carrier protein-2 (SCP-2) is a small intracellular basic protein domain implicated in peroxisomal beta-oxidation. We extend our knowledge of plant SCP-2 by characterizing SCP-2 from Euphorbia lagascae. This protein consists of 122 amino acids including a PTS1 peroxisomal targeting signal. It has a molecular mass of 13.6 kDa and a pI of 9.5. It shares 67% identity and 84% similarity with SCP-2 from Arabidopsis thaliana. Proteomic analysis revealed that E. lagascae SCP-2 accumulates in the endosperm during seed germination. It showed in vitro transfer activity of BODIPY-phosphatidylcholine (BODIPY-PC). The transfer of BODIPY-PC was almost completely inhibited after addition of phosphatidylinositol, palmitic acid, stearoyl-CoA and vernolic acid, whereas sterols only had a very marginal inhibitory effect. We used protein modelling and site-directed mutagenesis to investigate why the BODIPY-PC transfer mediated by E. lagascae SCP-2 is not sensitive to sterols, whereas the transfer mediated by A. thaliana SCP-2 shows sterol sensitivity. Protein modelling suggested that the ligand-binding cavity of A. thaliana SCP-2 has four methionines (Met12, 14, 15 and 100), which are replaced by leucines (Leu11, 13, 14 and 99) in E. lagascae SCP-2. Changing Leu99 to Met99 was sufficient to convert E. lagascae SCP-2 into a sterol-sensitive BODIPY-PC-transfer protein, and correspondingly, changing Met100 to Leu100 abolished the sterol sensitivity of A. thaliana SCP-2.

Plants express a lipid transfer protein with high similarity to mammalian sterol carrier protein-2.

This is the first report describing the cloning and characterization of sterol carrier protein-2 (SCP-2) from plants. Arabidopsis thaliana SCP-2 (AtSCP-2) consists of 123 amino acids with a molecular mass of 13.6 kDa. AtSCP-2 shows 35% identity and 56% similarity to the human SCP-2-like domain present in the human D-bifunctional protein (DBP) and 30% identity and 54% similarity to the human SCP-2 encoded by SCP-X. The presented structural models of apo-AtSCP-2 and the ligand-bound conformation of AtSCP-2 reveal remarkable similarity with two of the structurally known SCP-2s, the SCP-2-like domain of human DBP and the rabbit SCP-2, correspondingly. The AtSCP-2 models in both forms have a similar hydrophobic ligand-binding tunnel, which is extremely suitable for lipid binding. AtSCP-2 showed in vitro transfer activity of BODIPY-phosphatidylcholine (BODIPY-PC) from donor membranes to acceptor membranes. The transfer of BODIPY-PC was almost completely inhibited after addition of 1-palmitoyl 2-oleoyl phosphatidylcholine or ergosterol. Dimyristoyl phosphatidic acid, stigmasterol, steryl glucoside, and cholesterol showed a moderate to marginal ability to lower the BODIPY-PC transfer rate, and the single chain palmitic acid and stearoyl-coenzyme A did not affect transfer at all. Expression analysis showed that AtSCP-2 mRNA is accumulating in most plant tissues. Plasmids carrying fusion genes between green fluorescent protein and AtSCP-2 were transformed with particle bombardment to onion epidermal cells. The results from analyzing the transformants indicate that AtSCP-2 is localized to peroxisomes.