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| 2. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 4. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 5. |
- Andersson, August, et al.
(författare)
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Regionally-Varying Combustion Sources of the January 2013 Severe Haze Events over Eastern China
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:4, s. 2038-2043
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Tidskriftsartikel (refereegranskat)abstract
- Thick haze plagued northeastern China in January 2013, strongly affecting both regional climate and human respiratory health. Here, we present dual carbon isotope constrained (Delta C-14 and delta C-13) source apportionment for combustion-derived black carbon aerosol (BC) for three key hotspot regions (megacities): North China Plain (NCP, Beijing), the Yangtze River Delta (YRD, Shanghai), and the Pearl River Delta (PRD, Guangzhou) for January 2013. BC, here quantified as elemental carbon (EC), is one of the most health-detrimental components of PM2.5 and a strong climate warming agent. The results show that these severe haze events were equally affected (similar to 30%) by biomass combustion in all three regions, whereas the sources of the dominant fossil fuel component was dramatically different between north and south. In the NCP region, coal combustion accounted for 66% (46-74%, 95% C.I.) of the EC, whereas, in the YRD and PRD regions, liquid fossil fuel combustion (e.g., traffic) stood for 46% (18-66%) and 58% (38-68%), respectively. Taken together, these findings suggest the need for a regionally-specific description of BC sources in climate models and regionally-tailored mitigation to combat severe air pollution events in East Asia.
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| 6. |
- Chen, I-Hua, et al.
(författare)
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Psychometric properties of the Depression, Anxiety, and Stress Scale (DASS-21) among different Chinese populations : A cross-sectional and longitudinal analysis
- 2023
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Ingår i: Acta Psychologica. - : Elsevier. - 0001-6918 .- 1873-6297. ; 240
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Tidskriftsartikel (refereegranskat)abstract
- Given that there is limited evidence concerning the psychometric properties of DASS-21 when applied to primary school students, the present study undertook a comprehensive exploration of the psychometric evidence supporting the use of the DASS-21 within this demographic. The research comprised three studies. In Study 1, the basic psychometric properties of internal consistency and construct validity were examined. A total of 3138 primary school students from three provinces in mainland China participated. The internal reliability of the overall scale was 0.93, and for all the subscales, it was higher than 0.80. Construct validity was partially supported. Both exploratory and confirmatory factor analyses upheld the factorial validity of the original three-factor structure. While convergent validity was established, the results showed unsatisfactory discriminant validity. The bifactor model showed that DASS-21 raw scores predominantly indicated the general factor, evidenced by the high explained common variance and omega-hierarchical values. However, the contributions from the three specific factors were minimal, with their omega hierarchical values all below 0.15. In Study 2, a longitudinal design was adopted, tracking 1366 primary school students from Southwest China over a three-month interval. The results further confirmed that the DASS-21 exhibited scalar time-invariance. The latent mean analysis showed that there were no statistically significant differences in the latent means of depression, anxiety, and stress between Time 1 and Time 2. In Study 3, which included 364 college students and 483 enterprise workers, the results demonstrated that the DASS-21 had measurement invariance across different populations. The latent mean analysis further confirmed that, in terms of the latent mean of all three subscales, both college students and enterprise workers had significantly higher scores than primary school students. Overall, the findings indicated that the DASS-21 is a suitable tool for screening schoolchildren for general psychological distress, but it is not suitable for discerning distinct negative mood state disorders.
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| 7. |
- Chen, Jingxuan, et al.
(författare)
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Regulating Thiol Ligands of p-Type Colloidal Quantum Dots for Efficient Infrared Solar Cells
- 2021
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 6:5, s. 1970-1989
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Tidskriftsartikel (refereegranskat)abstract
- The p-type semiconducting colloidal quantum dot (CQD), working as a hole conductor in CQD solar cells (CQDSCs), is critical for charge carrier extraction and therefore, to large extent, determines the device's photovoltaic performance. However, during the preparation of a p-type CQD solid film on the top of an n-type CQD solid film, forming a p-n heterojunction within the CQDSCs, the optoelectronic properties of the underlayered n-type CQD solid film are significantly affected by conventional 1,2-ethanedithiol (EDT) ligands due to its high reactivity. Herein, a series of thiol ligands are comprehensively studied for p-type CQDs, which suggests that, by finely controlling the interaction between the CQDs and thiol ligands during the preparation of p-type CQD solid films, the n-type CQD solid films can be well protected and avoid destruction induced by thiol ligands. The p-type CQD solid film with 4-aminobenzenethiol (ABT) passivating the CQD surface exhibits better optoelectronic properties than the conventional p-type EDT-based CQD solid films, resulting in an improved photovoltaic performance in CQDSCs.
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| 9. |
- Chen, Lin, et al.
(författare)
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Tetranuclear Iron Complexes Bearing Benzenetetrathiolate Bridges as Four-Electron Transformation Templates and Their Electrocatalytic Properties for Proton Reduction
- 2013
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 52:4, s. 1798-1806
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Tidskriftsartikel (refereegranskat)abstract
- Two tetranuclear iron-sulfur complexes, (mu,mu-pbtt)[Fe-2(CO)(6)](2) (pbtt = benzene-1,2,4,5-tetrathiolato, 3) and (mu,mu-obtt)[Fe-2(CO)(6)](2) (obtt = benzene-1,2,3,4-tetrathiolato, 4), were prepared from reaction of Fe-3(CO)(12) and the corresponding tetramercaptobenzene in THF, respectively. Complexes 5 and 6, (mu,mu-pbtt)[Fe-2(CO)(5)L-1][Fe-2(CO)(5)L-2] (L-1 = CO, L-2 = PPyr(3) (Pyr = N-pyrrolyl), 5; L-1 = L-2 = PPyr(3), 6) were obtained by controlling CO displacement of 3 with PPyr(3). Molecular structures of 3-6 were determined by spectroscopic and single-crystal X-ray analyses. All-CO Fe4S4 complexes 3 and 4 each display four-electron reduction processes in consecutive chemically reversible two-electron reduction events with relatively narrow potential spans in the cyclic voltammograms. Phosphine-substituted Fe4S4 complexes 5 and 6 exhibit two consecutive two-electron reduction events, which are not fully reversible. The electrocatalytic properties of 3 and 4 for proton reduction were studied using a series of carboxylic acids of increasing strength (CH3COOH, CH2ClCOOH, CHCl2COOH, CCl3COOH, and CF3COOH). The mechanisms for electrochemical proton reduction to hydrogen catalyzed by complex 3 as a function of acid strength are discussed.
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| 10. |
- Cheng, Minglun, et al.
(författare)
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Effect of the S-to-S bridge on the redox properties and H-2 activation performance of diiron complexes related to the [FeFe]-hydrogenase active site
- 2016
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Ingår i: Dalton Transactions. - : ROYAL SOC CHEMISTRY. - 1477-9226 .- 1477-9234. ; 45:44, s. 17687-17696
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Tidskriftsartikel (refereegranskat)abstract
- Three biomimetic models of the [FeFe]-hydrogenase active site, namely diiron dithiolates of [(mu-edt){Fe(CO)(3)}{Fe(CO)(kappa(2)-PNP)}] (1, edt = ethane-1,2-dithiolate, PNP = Ph2PCH2N(nPr)CH2PPh2), [(mu bdtMe){Fe(CO)(3)}{Fe(CO)(kappa(2)-PNP)}] (2, bdtMe = 4-methylbenzene-1,2-dithiolate), and [(mu-adtBn){Fe(CO)(3)} {Fe(CO)(kappa(2)-PNP)}] (3, adtBn = N-benzyl-2-azapropane-1,3-dithiolate), were prepared and structurally characterized. These complexes feature the same PNP ligand but different S-to-S bridges. Influence of the S-to-S bridge on the electrochemical properties and chemical oxidation reactivity of 1-3 was studied by cyclic voltammetry and by in situ IR spectroscopy. The results reveal that the S-to-S bridge has a considerable effect on the oxidation reactivity of 1-3 and on the stability of in situ generated single-electron oxidized complexes, [1](+), [2](+), and [3](+). The performances of [1](+) and [2](+) for H-2 activation were explored in the presence of a mild chemical oxidant, while rapid decomposition of [3](+) thwarted the further study of this complex. Gratifyingly, 1 was found to be catalytically active, although in a low turnover number, for H-2 oxidation in the presence of excess mild oxidant and a proton trapper under 1 atm H-2 at room temperature.
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