Self‐Emergent Protocells Generated in an Aqueous Solution with Binary Macromolecules through Liquid‐Liquid Phase Separation

生体内の高分子混雑に着目した新規の細胞モデルの創成に成功. 京都大学プレスリリース. 2020-12-16.Recently, liquid–liquid phase separation (LLPS) has attracted considerable attention among researchers in the life sciences as a plausible mechanism for the generation of microstructures inside cells. LLPS occurs through multiple nonspecific interactions and does not always require a lock‐and‐key interaction with a binary macromolecular solution. The remarkable features of LLPS include the non‐uniform localization and concentration of solutes, resulting in the ability to isolate certain chemical systems and thereby parallelize multiple chemical reactions within the limited space of a living cell. We report that, by using the macromolecules, poly(ethylene glycol) (PEG) and dextran, that exhibit LLPS in an aqueous solution, cell‐sized liposomes are spontaneously formed therein in the presence of phospholipids. In this system, LLPS is generated through the depletion effect of macromolecules. The results showed that cell‐like microdroplets entrapping DNA wrapped by a phospholipid layer emerge in a self‐organized manner

DNA topoisomerase II interacts with Lim15/Dmc1 in meiosis

Lim15/Dmc1 is a meiosis specific RecA-like protein. Here we propose its participation in meiotic chromosome pairing-related events along with DNA topoisomerase II. Analysis of protein–protein interactions using in vitro binding assays provided evidence that Coprinus cinereus DNA topoisomerase II (CcTopII) specifically interacts with C.cinereus Lim15/Dmc1 (CcLim15). Co-immunoprecipitation experiments also indicated that the CcLim15 protein interacts with CcTopII in vivo. Furthermore, a significant proportion of CcLim15 and CcTopII could be shown to co-localize on chromosomes from the leptotene to the zygotene stage. Interestingly, CcLim15 can potently activate the relaxation/catenation activity of CcTopII in vitro, and CcTopII suppresses CcLim15-dependent strand transfer activity. On the other hand, while enhancement of CcLim15's DNA-dependent ATPase activity by CcTopII was found in vitro, the same enzyme activity of CcTopII was inhibited by adding CcLim15. The interaction of CcLim15 and CcTopII may facilitate pairing of homologous chromosomes

Intention to return to the town of Tomioka in residents 7 years after the accident at Fukushima Daiichi Nuclear Power Station: a cross-sectional study

The aim of our study was to identify the factors associated with intention to return (ITR) in residents of Tomioka town, Fukushima Prefecture. We contacted approximated 8000 residents aged 20 years or older who lived in Tomioka. We invited them to take part in a written survey on ITR. In all, 1749 residents\u27 replies were included in the analysis. We asked about ITR in former residents of Tomioka town. We also asked about relevant factors and about risk perception in relation to the health effects of radiation exposure. Of those contacted, 469 (26.8%) had an ITR. Logistic regression analysis revealed that being male (OR = 1.6, 95% Cl: 1.24-1.96, P < 0.001),the anticipation of improving shopping in the town (OR = 1.5, 95% Cl: 1.26-1.67, P < 0.001) and requests for individual consultation with experts on the health effects of radiation (OR = 2.7, 95% Cl: 2.10-3.48, P <0.001) were associated with the ITR (+), and living with children under 18 years of age (OR = 0.7, 95% Cl: 0.51-0.95, P = 0.023), reluctance to drink tap water (OR = 0.5, 95% Cl: 0.36-0.69, P < 0.001) and anxiety regarding genetic effects of radiation in the next generation (OR = 0.6, 95% Cl: 0.45-079, P <0.001) were associated with the ITR (-) to Tomioka town, independent of other covariates. To allay the anxieties of residents who have an ITR to their hometown, careful risk communication, including information on the potential effects of radiation on health, is important

<i>Drosophila</i> Temperature Preference Rhythms: An Innovative Model to Understand Body Temperature Rhythms

Human body temperature increases during wakefulness and decreases during sleep. The body temperature rhythm (BTR) is a robust output of the circadian clock and is fundamental for maintaining homeostasis, such as generating metabolic energy and sleep, as well as entraining peripheral clocks in mammals. However, the mechanisms that regulate BTR are largely unknown. Drosophila are ectotherms, and their body temperatures are close to ambient temperature; therefore, flies select a preferred environmental temperature to set their body temperature. We identified a novel circadian output, the temperature preference rhythm (TPR), in which the preferred temperature in flies increases during the day and decreases at night. TPR, thereby, produces a daily BTR. We found that fly TPR shares many features with mammalian BTR. We demonstrated that diuretic hormone 31 receptor (DH31R) mediates Drosophila TPR and that the closest mouse homolog of DH31R, calcitonin receptor (Calcr), is essential for mice BTR. Importantly, both TPR and BTR are regulated in a distinct manner from locomotor activity rhythms, and neither DH31R nor Calcr regulates locomotor activity rhythms. Our findings suggest that DH31R/Calcr is an ancient and specific mediator of BTR. Thus, understanding fly TPR will provide fundamental insights into the molecular and neural mechanisms that control BTR in mammals

Characterization of Entamoeba histolytica adenosine 5′-phosphosulfate (APS) kinase; validation as a target and provision of leads for the development of new drugs against amoebiasis

BACKGROUND: Amoebiasis, caused by Entamoeba histolytica infection, is a global public health problem. However, available drugs to treat amoebiasis are currently limited, and no effective vaccine exists. Therefore, development of new preventive measures against amoebiasis is urgently needed. METHODOLOGY/PRINCIPAL FINDINGS: Here, to develop new drugs against amoebiasis, we focused on E. histolytica adenosine 5\u27-phosphosulfate kinase (EhAPSK), an essential enzyme in Entamoeba sulfolipid metabolism. Fatty alcohol disulfates and cholesteryl sulfate, sulfolipids synthesized in Entamoeba, play important roles in trophozoite proliferation and cyst formation. These processes are closely associated with clinical manifestation and severe pathogenesis of amoebiasis and with disease transmission, respectively. We validated a combination approach of in silico molecular docking analysis and an in vitro enzyme activity assay for large scale screening. Docking simulation ranked the binding free energy between a homology modeling structure of EhAPSK and 400 compounds. The 400 compounds were also screened by a 96-well plate-based in vitro APSK activity assay. Among fifteen compounds identified as EhAPSK inhibitors by the in vitro system, six were ranked by the in silico analysis as having high affinity toward EhAPSK. Furthermore, 2-(3-fluorophenoxy)-N-[4-(2-pyridyl)thiazol-2-yl]-acetamide, 3-phenyl-N-[4-(2-pyridyl)thiazol-2-yl]-imidazole-4-carboxamide, and auranofin, which were identified as EhAPSK inhibitors by both in silico and in vitro analyses, halted not only Entamoeba trophozoite proliferation but also cyst formation. These three compounds also dose-dependently impaired the synthesis of sulfolipids in E. histolytica. CONCLUSIONS/SIGNIFICANCE: Hence, the combined approach of in silico and in vitro-based EhAPSK analyses identified compounds that can be evaluated for their effects on Entamoeba. This can provide leads for the development of new anti-amoebic and amoebiasis transmission-blocking drugs. This strategy can also be applied to identify specific APSK inhibitors, which will benefit research into sulfur metabolism and the ubiquitous pathway terminally synthesizing essential sulfur-containing biomolecules