In this study, cocoons and degummed silk samples of Bombyx mori and twenty Saturniidae species of the genera Actias, Attacus, Argema, Antheraea, Caligula, Callosamia, Cricula, Epiphora, Hyalophora, ...Loepa, Samia and Saturnia are studied to gain an insight into their morphology, chemical composition and physical structure. For this purpose, silk samples are characterized by optical microscopy and FTIR spectroscopy in attenuated total reflection mode (ATR-FTIR spectroscopy). Furthermore, degummed silk samples are analyzed for their amino acid (AA) composition by GC-FID. In the course of method development, various degumming methods are tested using alkalis, citric acid, enzymes and detergents. A mixture of 0.1% sodium carbonate and 2.5% ethylenediamine proves to be an effective agent for degumming Saturniidae and B. mori cocoons. After hydrolysis of the fibroin filaments with 6 N hydrochloric acid and derivatization with propyl chloroformate, fifteen AAs are identified and qualified. This method shows a satisfactory overall analytical performance with an average recovery rate of 95% at the medium concentration level. The chemical composition of the different silks was considered comparatively. Within a genus, the analyses usually show a high degree of similarity in AA composition and the resulting structural indices, whereas differences are found between genera.
Introduction
Depending on their terpenoid and phenolic constituents plant resins can be classified as diterpenoid, triterpenoid or phenolic resins; thereby the profile of diterpenes and triterpenes ...is considered as genus‐ or even species‐specific.
Objectives
We aimed to develop a simple, rapid, inexpensive, sensitive and specific method for the identification of resin‐specific triterpenoid and phenolic compounds in plant resins using (HP)TLC (high‐performance) thin‐layer chromatography combined with APCI‐MS (atmospheric pressure chemical ionisation mass spectrometry) and post‐chromatographic detection reactions.
Methods
Twenty resin samples from different plant species were analysed. Different extraction procedures, post‐chromatographic detection reagents as well as various sorbents and solvents for planar chromatography were tested. To evaluate the potential of the optimised (HP)TLC‐APCI‐MS methods, parameter such as limit of detection (LOD) was determined for selected marker compounds.
Results
Our protocol enabled qualitative analyses of chemotaxonomic molecular markers in natural resins such as dammar, mastic, olibanum and benzoin. For the first time, the application of thionyl chloride‐stannic chloride reagent for a specific post‐chromatographic detection of triterpenes is reported, sometimes even allowing discrimination between isomers based on their characteristic colour sequences. For triterpene acids, triterpene alcohols and phenolic compounds, detection limits of 2–20 ng/TLC zone and a system precision with a relative standard deviation (RSD) in the range of 3.9%–7.0% were achieved by (HP)TLC‐APCI‐MS. The applicability of the method for the analysis of resin‐based varnishes was successfully tested on a mastic‐based varnish. Thus, the method we propose is a helpful tool for the discrimination of resins and resin‐based varnishes with respect to their botanical origin.
In this study, we developed a simple, rapid, cost‐effective, sensitive and specific method for the identification of chemotaxonomic molecular markers in plant resins such as dammar, mastic, olibanum and benzoin using (HP)TLC combined with APCI‐MS and post‐chromatographic detection reactions. For the first time, the application of thionyl chloride‐stannic chloride reagent for a specific post‐chromatographic detection of triterpenes is reported, sometimes even allowing discrimination between isomers based on their characteristic color sequences.
Mitochondria are key organelles for cellular energetics, metabolism, signaling, and quality control and have been linked to various diseases. Different views exist on the composition of the human ...mitochondrial proteome. We classified >8,000 proteins in mitochondrial preparations of human cells and defined a mitochondrial high-confidence proteome of >1,100 proteins (MitoCoP). We identified interactors of translocases, respiratory chain, and ATP synthase assembly factors. The abundance of MitoCoP proteins covers six orders of magnitude and amounts to 7% of the cellular proteome with the chaperones HSP60-HSP10 being the most abundant mitochondrial proteins. MitoCoP dynamics spans three orders of magnitudes, with half-lives from hours to months, and suggests a rapid regulation of biosynthesis and assembly processes. 460 MitoCoP genes are linked to human diseases with a strong prevalence for the central nervous system and metabolism. MitoCoP will provide a high-confidence resource for placing dynamics, functions, and dysfunctions of mitochondria into the cellular context.
Display omitted
•Human mitochondrial high-confidence proteome with >1,100 proteins (MitoCoP)•Mitochondria-specific protein copy numbers and half-lives•Interactors of protein translocases and oxidative phosphorylation assembly factors•>40% of mitochondrial proteome linked to human diseases
Mitochondria are crucial for cellular energy metabolism and human health. Morgenstern et al. present a high-confidence protein compendium of human mitochondria including mitochondria-specific protein copy numbers and half-lives. They identify interactors of key mitochondrial protein machineries and link >40% of the mitochondrial proteome to human diseases.
Middle East respiratory syndrome coronavirus (MERS-CoV) infection is associated with a high case-fatality rate, and the potential pandemic spread of the virus is a public health concern. The spike ...protein of MERS-CoV (MERS-S) facilitates viral entry into host cells, which depends on activation of MERS-S by cellular proteases. Proteolytic activation of MERS-S during viral uptake into target cells has been demonstrated. However, it is unclear whether MERS-S is also cleaved during S protein synthesis in infected cells and whether cleavage is required for MERS-CoV infectivity. Here, we show that MERS-S is processed by proprotein convertases in MERSS-transfected and MERS-CoV-infected cells and that several RXXR motifs located at the border between the surface and transmembrane subunit of MERS-S are required for efficient proteolysis. However, blockade of proprotein convertases did not impact MERS-S-dependent transduction of target cells expressing high amounts of the viral receptor, DPP4, and did not modulate MERS-CoV infectivity. These results show that MERS-S is a substrate for proprotein convertases and demonstrate that processing by these enzymes is dispensable for S protein activation. Efforts to inhibit MERS-CoV infection by targeting host cell proteases should therefore focus on enzymes that process MERS-S during viral uptake into target cells.
Scholarly publishing lives on traditioned terminology that gives meaning to subjects such as authors, inhouse editors and external guest editors, artifacts such as articles, journals, special issues, ...and collected editions, or practices of acquisition, selection, and review. These subjects, artifacts, and practices ground the constitution of scholarly discourse. And yet, the meaning ascribed to each of these terms shifts, blurs, or is disguised as publishing culture shifts, which becomes manifest in new digital publishing technology, new forms of publishing management, and new forms of scholarly knowledge production. As a result, we may come to over- or underestimate changes in scholarly communication based on traditioned but shifting terminology. In this article, we discuss instances of scholarly publishing whose meaning shifted. We showcase the cultural shift that becomes manifest in the new, prolific guest editor. Though the term suggests an established subject, this editorial role crystallizes a new cultural setting of loosened discourse communities and temporal structures, a blurring of publishing genres and, ultimately, the foundations of academic knowledge production.
PDF
