Glial expression of a steroidogenic enzyme underlies natural variation in hitchhiking behavior.

Phoresy is an interspecies interaction that facilitates spatial dispersal by attaching to a more mobile species. Hitchhiking species have evolved specific traits for physical contact and successful phoresy, but the regulatory mechanisms involved in such traits and their evolution are largely unexplored. The nematode Caenorhabditis elegans displays a hitchhiking behavior known as nictation during its stress-induced developmental stage. Dauer-specific nictation behavior has an important role in natural C. elegans populations, which experience boom-and-bust population dynamics. In this study, we investigated the nictation behavior of 137 wild C. elegans strains sampled throughout the world. We identified species-wide natural variation in nictation and performed a genome-wide association mapping. We show that the variants in the promoter of nta-1, encoding a putative steroidogenic enzyme, underlie differences in nictation. This difference is due to the changes in nta-1 expression in glial cells, which implies that glial steroid metabolism regulates phoretic behavior. Population genetic analysis and geographic distribution patterns suggest that balancing selection maintained two nta-1 haplotypes that existed in ancestral C. elegans populations. Our findings contribute to further understanding of the molecular mechanism of species interaction and the maintenance of genetic diversity within natural populations.

Mass Spectrometry-Driven Discovery of Neuropeptides Mediating Nictation Behavior of Nematodes.

Neuropeptides regulate animal physiology and behavior, making them widely studied targets of functional genetics research. While the field often relies on differential -omics approaches to build hypotheses, no such method exists for neuropeptidomics. It would nonetheless be valuable for studying behaviors suspected to be regulated by neuropeptides, especially when little information is otherwise available. This includes nictation, a phoretic strategy of Caenorhabditis elegans dauers that parallels host-finding strategies of infective juveniles of many pathogenic nematodes. We here developed a targeted peptidomics method for the model organism C. elegans and show that 161 quantified neuropeptides are more abundant in its dauer stage compared with L3 juveniles. Many of these have orthologs in the commercially relevant pathogenic nematode Steinernema carpocapsae, in whose infective juveniles, we identified 126 neuropeptides in total. Through further behavioral genetics experiments, we identify flp-7 and flp-11 as novel regulators of nictation. Our work advances knowledge on the genetics of nictation behavior and adds comparative neuropeptidomics as a tool to functional genetics workflows.

Pandemic and employment: Evidence from COVID-19 in South Korea.

Using two complementary approaches, this study examines the deterioration of the Korean labor market during the first 10 months of the global COVID-19 pandemic. Applying the synthetic control method, we first find that the COVID-19 outbreak has eliminated 1.1 million jobs (4.2% of nonfarm employment) nationwide in April 2020. However, a difference-in-differences approach shows that local variation in COVID-19 intensity, which captures the "regional" effect of the pandemic, explains only 9% of the national shock. The portion of the regional effect remains low until December. This is mainly because the nationwide fear and policies such as social distancing measures also have a "common" effect on local economies. Our findings suggest that the COVID-19 shock may last long in the labor market due to this common effect unless the risk of infection is completely eliminated.

Neurogenetics of nictation, a dispersal strategy in nematodes.

Nictation is a behaviour in which a nematode stands on its tail and waves its head in three dimensions. This activity promotes dispersal of dauer larvae by allowing them to attach to other organisms and travel on them to a new niche. In this review, we describe our understanding of nictation, including its diversity in nematode species, how it is induced by environmental factors, and neurogenetic factors that regulate nictation. We also highlight the known cellular and signalling factors that affect nictation, for example, IL2 neurons, insulin/IGF-1 signalling, TGF-ß signalling, FLP neuropeptides and piRNAs. Elucidation of the mechanism of nictation will contribute to increased understanding of the conserved dispersal strategies in animals.

Comparative connectomics of dauer reveals developmental plasticity.

A fundamental question in neurodevelopmental biology is how flexibly the nervous system changes during development. To address this, we reconstructed the chemical connectome of dauer, an alternative developmental stage of nematodes with distinct behavioral characteristics, by volumetric reconstruction and automated synapse detection using deep learning. With the basic architecture of the nervous system preserved, structural changes in neurons, large or small, were closely associated with connectivity changes, which in turn evoked dauer-specific behaviors such as nictation. Graph theoretical analyses revealed significant dauer-specific rewiring of sensory neuron connectivity and increased clustering within motor neurons in the dauer connectome. We suggest that the nervous system in the nematode has evolved to respond to harsh environments by developing a quantitatively and qualitatively differentiated connectome.

The C. elegans regulatory factor X (RFX) DAF-19M module: A shift from general ciliogenesis to cell-specific ciliary and behavioral specialization.

Cilia are important for the interaction with environments and the proper function of tissues. While the basic structure of cilia is well conserved, ciliated cells have various functions. To understand the distinctive identities of ciliated cells, the identification of cell-specific proteins and its regulation is essential. Here, we report the mechanism that confers a specific identity on IL2 neurons in Caenorhabditis elegans, neurons important for the dauer larva-specific nictation behavior. We show that DAF-19M, an isoform of the sole C. elegans RFX transcription factor DAF-19, heads a regulatory subroutine, regulating target genes through an X-box motif variant under the control of terminal selector proteins UNC-86 and CFI-1 in IL2 neurons. Considering the conservation of DAF-19M module in IL2 neurons for nictation and in male-specific neurons for mating behavior, we propose the existence of an evolutionarily adaptable, hard-wired genetic module for distinct behaviors that share the feature "recognizing the environment."

The Werther effect of celebrity suicides: Evidence from South Korea.

Since 2003 Korea has experienced the highest suicide rate among OECD countries. One of the societal risk factors that triggers suicide is the contagious nature of suicide. This paper empirically examines the effect of celebrity suicide reports on subsequent copycat suicides, using daily suicide data and information of highly publicized suicide stories in Korea from 2005 to 2018. The findings from the Poisson regression model suggest that the number of public suicides soars after media reports on celebrity suicides. On average, the number of suicides in the population increased by 16.4% within just one day after the reports. Further analysis reveals that female and younger subgroups are more likely to be affected by celebrity suicides. Moreover, the public reacts more strongly to suicide incidents of celebrities of the same gender and even imitates the methods of suicide used by celebrities. This paper highlights the significance of careful and responsible media coverage of suicide stories to prevent copycat suicide. For policymakers, it is crucial to implement regulations not only for traditional media but also for new media where younger people can freely access unfiltered information.

A home programme for patients with cognitive dysfunction: a pilot study.

OBJECTIVE: To evaluate the effectiveness of a 12-week individualized home programme of rehabilitation for patients with cognitive impairment. METHODS: Six patients with cognitive dysfunction, after haemorrhagic stroke, participated in this study. A programme was carried out in the home environment that consisted of four mixed training programmes: cognitive remediation therapy, story retelling, cognitive enhancing games and aerobic exercise. The patients performed the home programme for 2 hours a day, 7 days a week, for 12 weeks. The main outcomes were measured using the MMSE, Neurobehavioural Cognitive Status Examination (NCSE), domain-specific computerized neuropsychological test for attention, memory and executive function, the Lowenstein Occupational Therapist Cognitive Assessment (LOTCA), the Modified Barthel Index (MBI) and the Seoul-Instrumental Activity of Daily Living (S-IADL). RESULTS: After completion of a 12-week home programme, the patients' S-IADL scores improved significantly (p < 0.05). The patients' MMSE and NCSE scores improved marginally, with mean score changes of 4.2 (p = 0.058), 4.7 (p = 0.078) and 6.8 (p = 0.068) points, respectively. However, the patients' domain-specific cognitive test and LOTCA scores did not significantly change. CONCLUSION: The results of this study showed that an individualized home programme improved IADL performance in patients with cognitive dysfunction and may have a beneficial effect on cognition, as assessed by general cognitive measures.

Synthesis of 2D Metal Chalcogenide Thin Films through the Process Involving Solution-Phase Deposition.

2D metal chalcogenide thin films have recently attracted considerable attention owing to their unique physicochemical properties and great potential in a variety of applications. Synthesis of large-area 2D metal chalcogenide thin films in controllable ways remains a key challenge in this research field. Recently, the solution-based synthesis of 2D metal chalcogenide thin films has emerged as an alternative approach to vacuum-based synthesis because it is relatively simple and easy to scale up for high-throughput production. In addition, solution-based thin films open new opportunities that cannot be achieved from vacuum-based thin films. Here, a comprehensive summary regarding the basic structures and properties of different types of 2D metal chalcogenides, the mechanistic details of the chemical reactions in the synthesis of the metal chalcogenide thin films, recent successes in the synthesis by different reaction approaches, and the applications and potential uses is provided. In the last perspective section, the technical challenges to be overcome and the future research directions in the solution-based synthesis of 2D metal chalcogenides are discussed.

The genetic basis of natural variation in a phoretic behavior.

Phoresy is a widespread form of commensalism that facilitates dispersal of one species through an association with a more mobile second species. Dauer larvae of the nematode Caenorhabditis elegans exhibit a phoretic behavior called nictation, which could enable interactions with animals such as isopods or snails. Here, we show that natural C. elegans isolates differ in nictation. We use quantitative behavioral assays and linkage mapping to identify a genetic locus (nict-1) that mediates the phoretic interaction with terrestrial isopods. The nict-1 locus contains a Piwi-interacting small RNA (piRNA) cluster; we observe that the Piwi Argonaute PRG-1 is involved in the regulation of nictation. Additionally, this locus underlies a trade-off between offspring production and dispersal. Variation in the nict-1 locus contributes directly to differences in association between nematodes and terrestrial isopods in a laboratory assay. In summary, the piRNA-rich nict-1 locus could define a novel mechanism underlying phoretic interactions.Nematodes use a characteristic set of movements, called nictation, to hitchhike on more mobile animals. Here, Lee et al. identify a genetic locus in the nematode Caenorhabditis elegans that underlies nictation and contributes to successful hitchhiking, but at expense of reduced offspring production.

One-Step Solution Phase Growth of Transition Metal Dichalcogenide Thin Films Directly on Solid Substrates.

Ultrathin transition metal dichalcogenides (TMDs) have exotic electronic properties. With success in easy synthesis of high quality TMD thin films, the potential applications will become more viable in electronics, optics, energy storage, and catalysis. Synthesis of TMD thin films has been mostly performed in vacuum or by thermolysis. So far, there is no solution phase synthesis to produce large-area thin films directly on target substrates. Here, this paper reports a one-step quick synthesis (within 45-90 s) of TMD thin films (MoS2 , WS2 , MoSe2 , WSe2 , etc.) on solid substrates by using microwave irradiation on a precursor-containing electrolyte solution. The numbers of the quintuple layers of the TMD thin films are precisely controllable by varying the precursor's concentration in the electrolyte solution. A photodetector made of MoS2 thin film comprising of small size grains shows near-IR absorption, supported by the first principle calculation, exhibits a high photoresponsivity (>300 mA W-1 ) and a fast response (124 µs). This study paves a robust way for the synthesis of various TMD thin films in solution phases.

Surfactant-free scalable synthesis of Bi2 Te3 and Bi2Se3 nanoflakes and enhanced thermoelectric properties of their nanocomposites.

Surfactant-free nanoflakes of n-type Bi2 Te3 and Bi2 Se3 are synthesized in high yields. Their suspensions are mixed to create nanocomposites with heterostructured nanograins. A maximum ZT (0.7 at 400 K) is achieved with a broad content of 10-15% Bi2 Se3 in the nanocomposites.

Optimization of transesterification of animal fat ester using response surface methodology.

In an effort to optimize the reaction conditions of biodiesel production from lard, response surface methodology was applied, and the effects of five-level-three-factors and their reciprocal interactions were assessed. A total of 20 individual experiments were conducted, and were designed to study reaction temperature, catalyst amount, and oil-to-methanol molar ratio. A statistical model predicted that the highest conversion yield of lard biodiesel would be 98.6%, at the following optimized reaction conditions: a reaction temperature of 65 degrees C, a catalyst amount of 1.26%, and an oil-to-methanol molar ratio of 7.5:1, with a 20-min reaction time. Using these optimal factor values under experimental conditions in three independent replicates, an average content of 97.8+/-0.6% was achieved, and this value was well within the range predicted by the model. The quality of biodiesel produced from lard at the optimum reaction conditions satisfied the relevant quality standards, with the exception of cold filter plugging point.

Synthesis of poly(sorbitan methacrylate) hydrogel by free-radical polymerization.

Hydrogels are materials with the ability to swell in water through the retention of significant fractions of water within their structures. Owing to their relatively high degree of biocompatibility, hydrogels have been utilized in a host of biomedical applications. In an attempt to determine the optimum conditions for hydrogel synthesis by the free-radical polymerization of sorbitan methacrylate (SMA), the hydrogel used in this study was well polymerized under the following conditions: 50% (w/v) SMA as monomer, 1% (w/w) alpha, alpha'-azo-bis(isobutyro-nitrile) as thermal initiator, and 1% (w/w) ethylene glycol dimethacrylate as cross-liking agent. Under these conditions, the moisture content of the polymerized SMA hydrogel was higher than in the other conditions. Moreover, the moisture content of the poly(SMA) hydrogel was also found to be higher than that of the poly(methyl methacrylate [MMA]) hydrogel. When the Fourier transform-infrared spectrum of poly(SMA) hydrogel was compared with that of poly(MMA) hydrogel, we noted a band at 1735-1730/cm, which did not appear in the Fourier transform-infrared spectrum of poly(MMA). The surface of the poly(SMA) hydrogel was visualized through scanning electron microscopy, and was uniform and clear in appearance.