Stable thrombus formation on irradiated microvascular endothelial cells under pulsatile flow: Pre-testing annexin V-thrombin conjugate for treatment of brain arteriovenous malformations

© 2018 Elsevier Ltd Background: Our goal is to develop a vascular targeting treatment for brain arteriovenous malformations (AVMs). Externalized phosphatidylserine has been established as a potential biomarker on the endothelium of irradiated AVM blood vessels. We hypothesize that phosphatidylserine could be selectively targeted after AVM radiosurgery with a ligand-directed vascular targeting agent to achieve localized thrombosis and rapid occlusion of pathological AVM vessels. Objective: The study aim was to establish an in vitro parallel-plate flow chamber to test the efficacy of a pro-thrombotic conjugate targeting phosphatidylserine. Methods: Conjugate was prepared by Lys-Lys cross-linking of thrombin with the phosphatidylserine-targeting ligand, annexin V. Cerebral microvascular endothelial cells were irradiated (5, 15, and 25 Gy) and after 1 or 3 days assembled in a parallel-plate flow chamber containing whole human blood and conjugate (1.25 or 2.5 μg/mL). Confocal microscopy was used to assess thrombus formation after flow via binding and aggregation of fluorescently-labelled platelets and fibrinogen. Results and conclusions: The annexin V-thrombin conjugate induced rapid thrombosis (fibrin deposition) on irradiated endothelial cells under shear stress in the parallel-plate flow device. Unconjugated, non-targeting thrombin did not induce fibrin deposition. A synergistic interaction between radiation and conjugate dose was observed. Thrombosis was greatest at the highest combined doses of radiation (25 Gy) and conjugate (2.5 μg/mL). The parallel-plate flow system provides a rapid method to pre-test pro-thrombotic vascular targeting agents. These findings validate the translation of the annexin V-thrombin conjugate to pre-clinical studies

The C-terminus of MIP-T3 protein is required for ubiquitin-proteasome-mediated degradation in human cells.

The intraflagellar transport (IFT) complex is essential for the formation and functional maintenance of eukaryotic cilia which play a vital role in development and tissue homeostasis. However, the biochemical characteristics and precise functions of IFT proteins remain unknown. Here, we report that MIP-T3, a human microtubule-interacting protein recently identified as a novel conserved component of the IFT complex, is an easily degradable protein in human cell lines. Protein degradation is mediated by the ubiquitin-proteasome system, and the C-terminus is required for ubiquitination and proteasome-mediated degradation of MIP-T3 protein. This study provides the first evidence for regulation of IFT protein stability

The PhanSST global database of Phanerozoic sea surface temperature proxy data

Paleotemperature proxy data form the cornerstone of paleoclimate research and are integral to understanding the evolution of the Earth system across the Phanerozoic Eon. Here, we present PhanSST, a database containing over 150,000 data points from five proxy systems that can be used to estimate past sea surface temperature. The geochemical data have a near-global spatial distribution and temporally span most of the Phanerozoic. Each proxy value is associated with consistent and queryable metadata fields, including information about the location, age, and taxonomy of the organism from which the data derive. To promote transparency and reproducibility, we include all available published data, regardless of interpreted preservation state or vital effects. However, we also provide expert-assigned diagenetic assessments, ecological and environmental flags, and other proxy-specific fields, which facilitate informed and responsible reuse of the database. The data are quality control checked and the foraminiferal taxonomy has been updated. PhanSST will serve as a valuable resource to the paleoclimate community and has myriad applications, including evolutionary, geochemical, diagenetic, and proxy calibration studies

Bacterial Gut Symbionts Contribute to Seed Digestion in an Omnivorous Beetle

Obligate bacterial symbionts alter the diets of host animals in numerous ways, but the ecological roles of facultative bacterial residents that colonize insect guts remain unclear. Carabid beetles are a common group of beneficial insects appreciated for their ability to consume insect prey and seeds, but the contributions of microbes to diet diversification in this and similar groups of facultative granivores are largely unknown.Using 16S rRNA gene clone libraries and terminal restriction fragment (tRF) length polymorphism analyses of these genes, we examined the bacterial communities within the guts of facultatively granivorous, adult Harpalus pensylvanicus (Carabidae), fed one of five dietary treatments: 1) an untreated Field population, 2) Seeds with antibiotics (seeds were from Chenopodium album), 3) Seeds without antibiotics, 4) Prey with antibiotics (prey were Acheta domesticus eggs), and 5) Prey without antibiotics. The number of seeds and prey consumed by each beetle were recorded following treatment. Harpalus pensylvanicus possessed a fairly simple gut community of approximately 3-4 bacterial operational taxonomic units (OTU) per beetle that were affiliated with the Gammaproteobacteria, Bacilli, Alphaproteobacteria, and Mollicutes. Bacterial communities of the host varied among the diet and antibiotic treatments. The field population and beetles fed seeds without antibiotics had the closest matching bacterial communities, and the communities in the beetles fed antibiotics were more closely related to each other than to those of the beetles that did not receive antibiotics. Antibiotics reduced and altered the bacterial communities found in the beetle guts. Moreover, beetles fed antibiotics ate fewer seeds, and those beetles that harbored the bacterium Enterococcus faecalis consumed more seeds on average than those lacking this symbiont.We conclude that the relationships between the bacterium E. faecalis and this factultative granivore's ability to consume seeds merit further investigation, and that facultative associations with symbiotic bacteria have important implications for the nutritional ecology of their hosts

The primary cilium as a dual sensor of mechanochemical signals in chondrocytes

The primary cilium is an immotile, solitary, and microtubule-based structure that projects from cell surfaces into the extracellular environment. The primary cilium functions as a dual sensor, as mechanosensors and chemosensors. The primary cilia coordinate several essential cell signaling pathways that are mainly involved in cell division and differentiation. A primary cilium malfunction can result in several human diseases. Mechanical loading is sense by mechanosensitive cells in nearly all tissues and organs. With this sensation, the mechanical signal is further transduced into biochemical signals involving pathways such as Akt, PKA, FAK, ERK, and MAPK. In this review, we focus on the fundamental functional and structural features of primary cilia in chondrocytes and chondrogenic cells

The PhanSST global database of Phanerozoic sea surface temperature proxy data

Paleotemperature proxy data form the cornerstone of paleoclimate research and are integral to understanding the evolution of the Earth system across the Phanerozoic Eon. Here, we present PhanSST, a database containing over 150,000 data points from five proxy systems that can be used to estimate past sea surface temperature. The geochemical data have a near-global spatial distribution and temporally span most of the Phanerozoic. Each proxy value is associated with consistent and queryable metadata fields, including information about the location, age, and taxonomy of the organism from which the data derive. To promote transparency and reproducibility, we include all available published data, regardless of interpreted preservation state or vital effects. However, we also provide expert-assigned diagenetic assessments, ecological and environmental flags, and other proxy-specific fields, which facilitate informed and responsible reuse of the database. The data are quality control checked and the foraminiferal taxonomy has been updated. PhanSST will serve as a valuable resource to the paleoclimate community and has myriad applications, including evolutionary, geochemical, diagenetic, and proxy calibration studies

Architecture of a nascent viral fusion pore

Enveloped viruses use specialized protein machinery to fuse the viral membrane with that of the host cell during cell invasion. In influenza virus, hundreds of copies of the haemagglutinin (HA) fusion glycoprotein project from the virus surface. Despite intensive study of HA and its fusion activity, the protein's modus operandi in manipulating viral and target membranes to catalyse their fusion is poorly understood. Here, the three-dimensional architecture of influenza virus–liposome complexes at pH 5.5 was investigated by electron cryo-tomography. Tomographic reconstructions show that early stages of membrane remodeling take place in a target membrane-centric manner, progressing from punctate dimples, to the formation of a pinched liposomal funnel that may impinge on the apparently unperturbed viral envelope. The results suggest that the M1 matrix layer serves as an endoskeleton for the virus and a foundation for HA during membrane fusion. Fluorescence spectroscopy monitoring fusion between liposomes and virions shows that leakage of liposome contents takes place more rapidly than lipid mixing at pH 5.5. The relation of ‘leaky' fusion to the observed prefusion structures is discussed