Early Effects of Aβ Oligomers on Dendritic Spine Dynamics and Arborization in Hippocampal Neurons

Alzheimer's disease (AD) is a neurodegenerative disorder that leads to impaired memory and cognitive deficits. Spine loss as well as changes in spine morphology correlates with cognitive impairment in this neurological disorder. Many studies in animal models and ex vivo cultures indicate that amyloid β-peptide (Aβ) oligomers induce synaptic damage early during the progression of the disease. Here, in order to determine the events that initiate synaptic alterations, we acutely applied oligomeric Aβ to primary hippocampal neurons and an ex vivo model of organotypic hippocampal cultures from a mouse after targeted expression of EGFP to allow high-resolution imaging and algorithm-based evaluation of spine changes. Dendritic spines were classified as thin, stubby or mushroom, based on morphology. In vivo, time-lapse imaging showed that the three spine types were relatively stable, although their stability significantly decreased after treatment with Aβ oligomers. Unexpectedly, we observed that the density of total dendritic spines increased in organotypic hippocampal slices treated with Aβ compared to control cultures. Specifically, the fraction of stubby spines significantly increased, while mushroom and thin spines remained unaltered. Pharmacological tools revealed that acute Aβ oligomers induced spine changes through mechanisms involving CaMKII and integrin β1 activities. Additionally, analysis of dendritic complexity based on a 3D reconstruction of the whole neuron morphology showed an increase in the apical dendrite length and branching points in CA1 organotypic hippocampal slices treated with Aβ. In contrast to spines, the morphological changes were affected by integrin β1 but not by CaMKII inhibition. Altogether, these data indicate that the Aβ oligomers exhibit early dual effects by acutely enhancing dendritic complexity and spine density.This study was supported by the Basque Government (IT1203-19 and PIBA PI-2016-1-0009), University of the Basque Country (UPV/EHU; fellowship to CO-S), CIBERNED and MINECO (SAF2016-75292-R, fellowship to AG-B FPU17/04891)

Quantitative live cell imaging of a tauopathy model enables the identification of a polypharmacological drug candidate that restores physiological microtubule interaction

Tauopathies such as Alzheimer’s disease are characterized by aggregation and increased phosphorylation of the microtubule-associated protein tau. Tau’s pathological changes are closely linked to neurodegeneration, making tau a prime candidate for intervention. We developed an approach to monitor pathological changes of aggregation-prone human tau in living neurons. We identified 2-phenyloxazole (PHOX) derivatives as putative polypharmacological small molecules that interact with tau and modulate tau kinases. We found that PHOX15 inhibits tau aggregation, restores tau’s physiological microtubule interaction, and reduces tau phosphorylation at disease-relevant sites. Molecular dynamics simulations highlight cryptic channel-like pockets crossing tau protofilaments and suggest that PHOX15 binding reduces the protofilament’s ability to adopt a PHF-like conformation by modifying a key glycine triad. Our data demonstrate that live-cell imaging of a tauopathy model enables screening of compounds that modulate tau-microtubule interaction and allows identification of a promising polypharmacological drug candidate that simultaneously inhibits tau aggregation and reduces tau phosphorylation

Interplay between phosphorylation and palmitoylation mediates plasma membrane targeting and sorting of GAP43.

Phosphorylation and lipidation provide posttranslational mechanisms that contribute to the distribution of cytosolic proteins in growing nerve cells. The growth-associated protein GAP43 is susceptible to both phosphorylation and S-palmitoylation and is enriched in the tips of extending neurites. However, how phosphorylation and lipidation interplay to mediate sorting of GAP43 is unclear. Using a combination of biochemical, genetic, and imaging approaches, we show that palmitoylation is required for membrane association and that phosphorylation at Ser-41 directs palmitoylated GAP43 to the plasma membrane. Plasma membrane association decreased the diffusion constant fourfold in neuritic shafts. Sorting to the neuritic tip required palmitoylation and active transport and was increased by phosphorylation-mediated plasma membrane interaction. Vesicle tracking revealed transient association of a fraction of GAP43 with exocytic vesicles and motion at a fast axonal transport rate. Simulations confirmed that a combination of diffusion, dynamic plasma membrane interaction and active transport of a small fraction of GAP43 suffices for efficient sorting to growth cones. Our data demonstrate a complex interplay between phosphorylation and lipidation in mediating the localization of GAP43 in neuronal cells. Palmitoylation tags GAP43 for global sorting by piggybacking on exocytic vesicles, whereas phosphorylation locally regulates protein mobility and plasma membrane targeting of palmitoylated GAP43

Tau Structures

Tau is a microtubule-associated protein that plays an important role in axonal stabilization, neuronal development, and neuronal polarity. In this review, we focus on the primary, secondary, tertiary, and quaternary tau structures. We describe the structure of tau from its specific residues until its conformation in dimers, oligomers, and larger polymers in physiological and pathological situations

Katastrofa w Czarnobylskiej Elektrowni Jądrowej a turystyka. Stan i perspektywy rozwoju turystyki na obszarze skażenia promieniotwórczego

The Chernobyl Nuclear Power Plant is located on the territory of Ukraine in the district of Kiev at the border with Belarus (4 km away from the city of Pripyat and 18 km from the city of Chernobyl). The failure of the reactor IV of the Chernobyl power plant on April 26, 1986, caused uncontrolled emission of radioactive substances into the atmosphere. Together with the rescue operation the evacuation of the population from the endangered areas started and the thirty-kilometre exclusion zone was designated around the territories most adversely affected by the results of the disaster. The total number of people displaced from the Exclusion Zone around the Chernobyl Nuclear Power Plant (within a 10-km radius from the power plant the” high risk zone” was established, and within a 30-km radius the zone of „the highest degree of contamination”) measuring approx. 2.5 thousand km2 was nearly 350 thousand people. Taking advantage of the area of radioactive contamination around the Chernobyl Nuclear Power Plant for tourist purposes began at the beginning of the 21st century when, under the pressure of Western countries, in 2000 the authorities of Ukraine shut down the last operating reactor. The permits to enter the Chernobyl Exclusion Zone are issued exclusively by the State Agency of Ukraine on the Exclusion Zone Management. People visiting the area of radioactive contamination around the Chernobyl Nuclear Power Plant must remember that visiting the zone takes place along designated routes which have been recognized as presenting no health hazard as long as appropriate safety measures are taken. Each visitor or group of visitors must also be accompanied by a licensed guide and representative of the zone. Presently, in the Exclusion Zone there are 11 tourist routes: checkpoint „Dytiatky” – Czerewacz village – Zalesie village – city of Chernobyl, city of Chernobyl (place near the St. Elijah Church); city of Chernobyl (the monument „To those who were saving the world”, St. Elijah Church, remembrance complex „The Wormwood Star”); city of Chernobyl – Paryszew village (Opacici village, Kupuwate village); city of Chernobyl – the Chernobyl Nuclear Power Plant – Complex „Vector” (uncontaminated zone) – „Buriakówka” radioactive waste disposal site (uncontaminated zone); city of Chernobyl – the Chernobyl Nuclear Power Plant – the cooler; city of Chernobyl – city of Pripyat; city of Chernobyl – Chernobyl-2; city of Chernobyl – Krasne, city of Chernobyl – Poliśke, city of Chernobyl – „Skazocznyj” (Fairytale) pioneer camp. In 2017 the area of radioactive contamination around the Chernobyl Nuclear Power Plant was visited by more than 50 thousand people, of whom the vast majority were foreigners (over 80%). Among them the most numerous group was: the Japanese, Americans and Germans. According to tour operators foreign tourists who visited the Exclusion Zone around the Chernobyl Nuclear Power Plant Chernobyl in the years 2015-2017 left about 10 million dollars a year in Ukraine.Czarnobylska Elektrownia Jądrowa zlokalizowana jest na terytorium Ukrainy w obwodzie kijowskim, przy granicy z Białorusią (4 km od miasta Prypeć i 18 km od miasta Czarnobyl). Awaria IV reaktora czarnobylskiej elektrowni w dniu 26 kwietnia 1986 r. spowodowała niekontrolowaną emisję substancji promieniotwórczych do atmosfery. Równocześnie z akcją ratunkową rozpoczęto ewakuację ludności z zagrożonych terenów, wyznaczając trzydziestokilometrową zamkniętą strefę wokół terenów najbardziej dotkniętych skutkami katastrofy. Łącznie z zamkniętej Strefy Wykluczenia wokół Czarnobylskiej Elektrowni Jądrowej (w promieniu 10 km od elektrowni utworzono strefę „szczególnego zagrożenia”, a w promieniu 30 km strefę „o najwyższym stopniu skażenia”) mierzącej ok 2,5 tys. km² wysiedlono prawie 350 tys. osób. Wykorzystywanie do celów turystycznych obszaru skażenia promieniotwórczego wokół Czarnobylskiej Elektrowni Jądrowej rozpoczęło się z początkiem XXI w. kiedy to pod naciskiem państw zachodnich władze Ukrainy w 2000 r. zamknęły ostatni czynny reaktor. Pozwolenia na wjazd do Czarnobylskiej Strefy Zamkniętej wydawane są tylko przez Państwową Agencję Ukrainy ds. Zarządzania Strefą Wykluczenia. Osoby zwiedzające obszar skażenia promieniotwórczego wokół Czarnobylskiej Elektrowni Jądrowej muszą pamiętać o tym, że zwiedzanie strefy odbywa się wzdłuż określonych tras, które uznano za niezagrażające zdrowiu przy zachowaniu odpowiednich reguł bezpieczeństwa. Każdemu zwiedzającemu czy też grupie zwiedzających musi towarzyszyć licencjonowany przewodnik oraz przedstawiciel strefy. Obecnie w Strefie Wykluczenia istnieje 11 tras turystycznych: punkt kontrolny „Dytiatki” – wioska Czerewacz – wioska Zalesie – m. Czarnobyl; m. Czarnobyl (miejsce w pobliżu Cerkwi św. Eliasza); m. Czarnobyl (pomnik „Tym, którzy uratowali świat”, Cerkiew św. Eliasza, kompleks pamięci „Gwiazda Piołun”); m. Czarnobyl – wioska Paryszew (wieś Opacici, wieś Kupuwate); m. Czarnobyl – Czarnobylska Elektrownia Jądrowa – Kompleks „Wektor” (strefa czysta) – punkt składowania odpadów radioaktywnych „Buriakówka” (strefa czysta); m. Czarnobyl – Czarnobylska Elektrownia Jądrowa – chłodnica; m. Czarnobyl – m. Prypeć; m. Czarnobyl – Czarnobyl-2; m. Czarnobyl – Krasne; m. Czarnobyl – Poliśke oraz m. Czarnobyl – obóz pionierski „Skazocznyj” (Bajkowy). W 2017 r. obszar skażenia promieniotwórczego wokół Czarnobylskiej Elektrowni Jądrowej odwiedziło ponad 50 tys. osób z czego zdecydowaną większość stanowili obcokrajowcy (ponad 80%). Wśród nich najliczniejszą grupą byli: Japończycy, Amerykanie oraz Niemcy. Według organizatorów wycieczek zagraniczni turyści, którzy odwiedzili Strefę Wykluczenia wokół Czarnobylskiej Elektrowni Jądrowej w latach 2015-2017, zostawili na Ukrainie ok. 10 mln dolarów w skali rocznej

Improved oxidative stability of biodiesel via alternative processing methods using cottonseed oil

Biodiesel from waste cooking oil (WCO) requires antioxidants to meet oxidation stability specifications set forth in ASTM D6751 or EN 14214. In contrast, unrefined cottonseed oil (CSO), containing tocopherols and gossypol, produces biodiesel of higher oxidation stability. However, only a portion of these CSO endogenous antioxidants are suspected to be retained in biodiesel. Because the economics of biodiesel manufacturing rely upon inexpensive sources of triglycerides, emphasis was placed on developing improved alternative processing methods where WCO was the main source of methyl esters (WCOME) and CSO was used as a supplemental source of triglycerides and antioxidants in a 4:1 ratio. This study compared four processing methods for their ability to produce biodiesel of increased oxidative stability prepared from a 4:1 ratio of WCO:CSO. Two novel processing methods developed for this study utilise solvent properties of fatty acid methyl esters and glycerol to avoid additional chemical inventory for biodiesel processors. This study concludes that the two new processing methods resulted in biodiesel that had statistically significant improved oxidation stability when compared to two common industrial processing methods. Another significant finding is that high-shear homogenisation during transesterification reduced reaction time from the published one hour to 16 minutes

Detection of corn adulteration in Brazilian coffee (Coffea arabica) by tocopherol profiling and Near-Infrared (NIR) spectroscopy

Coffee is a high-value commodity that is a target for adulteration, leading to loss of quality and causing significant loss to consumers. Therefore, there is significant interest in developing methods for detecting coffee adulteration and improving the sensitivity and accuracy of these methods. Corn and other lower value crops are potential adulterants, along with sticks and coffee husks. Fourteen pure Brazilian roasted, ground coffee bean samples were adulterated with 1–20% of roasted, ground corn and were analyzed for their tocopherol content and profile by HPLC. They were also analyzed by near-infrared (NIR) spectroscopy. Both proposed methods of detection of corn adulteration displayed a sensitivity of around 5%, thus representing simple and fast analytical methods for detecting adulteration at likely levels of contamination. Further studies should be conducted to verify the results with a much larger sample size and additional types of adulterants

Self-Assembling Multidomain Peptide Fibers with Aromatic Cores

Self-assembling multidomain peptides have been shown to have desirable properties, such as the ability to form hydrogels that rapidly recover following shear-thinning and the potential to be tailored by amino acid selection to vary their elasticity and encapsulate and deliver proteins and cells. Here we describe the effects of substitution of aliphatic hydrophobic amino acids in the central domain of the peptide for the aromatic amino acids phenylalanine, tyrosine, and tryptophan. While the basic nanofibrous morphology is retained in all cases, selection of the particular core residues results in switching from antiparallel hydrogen bonding to parallel hydrogen bonding in addition to changes in nanofiber morphology and in hydrogel rheological properties. Peptide nanofiber assemblies are investigated by circular dichroism polarimetry, infrared spectroscopy, atomic force microscopy, transmission and scanning electron microscopy, oscillatory rheology, and molecular dynamics simulations. Results from this study will aid in designing next generation cell scaffolding materials