Genome sequencing of evolved aspergilli populations reveals robust genomes, transversions in A. flavus, and sexual aberrancy in non-homologous end-joining mutants

BACKGROUND: Aspergillus spp. comprises a very diverse group of lower eukaryotes with a high relevance for industrial applications and clinical implications. These multinucleate species are often cultured for many generations in the laboratory, which can unknowingly propagate hidden genetic mutations. To assess the likelihood of such events, we studied the genome stability of aspergilli by using a combination of mutation accumulation (MA) lines and whole genome sequencing. RESULTS: We sequenced the whole genomes of 30 asexual and 10 sexual MA lines of three Aspergillus species (A. flavus, A. fumigatus and A. nidulans) and estimated that each MA line accumulated mutations for over 4000 mitoses during asexual cycles. We estimated mutation rates of 4.2 × 10-11 (A. flavus), 1.1 × 10-11 (A. fumigatus) and 4.1 × 10-11 (A. nidulans) per site per mitosis, suggesting that the genomes are very robust. Unexpectedly, we found a very high rate of GC → TA transversions only in A. flavus. In parallel, 30 asexual lines of the non-homologous end-joining (NHEJ) mutants of the three species were also allowed to accumulate mutations for the same number of mitoses. Sequencing of these NHEJ MA lines gave an estimated mutation rate of 5.1 × 10-11 (A. flavus), 2.2 × 10-11 (A. fumigatus) and 4.5 × 10-11 (A. nidulans) per base per mitosis, which is slightly higher than in the wild-type strains and some ~ 5-6 times lower than in the yeasts. Additionally, in A. nidulans, we found a NHEJ-dependent interference of the sexual cycle that is independent of the accumulation of mutations. CONCLUSIONS: We present for the first time direct counts of the mutation rate of filamentous fungal species and find that Aspergillus genomes are very robust. Deletion of the NHEJ machinery results in a slight increase in the mutation rate, but at a rate we suggest is still safe to use for biotechnology purposes. Unexpectedly, we found GC→TA transversions predominated only in the species A. flavus, which could be generated by the hepatocarcinogen secondary metabolite aflatoxin. Lastly, a strong effect of the NHEJ mutation in self-crossing was observed and an increase in the mutations of the asexual lines was quantifiedEspaña, MINECO grant number BIO2015-6714

An ectomycorrhizal fungus alters sensitivity to jasmonate, salicylate, gibberellin, and ethylene in host roots.

The phytohormones jasmonate, gibberellin, salicylate, and ethylene regulate an interconnected reprogramming network integrating root development with plant responses against microbes. The establishment of mutualistic ectomycorrhizal symbiosis requires the suppression of plant defense responses against fungi as well as the modification of root architecture and cortical cell wall properties. Here, we investigated the contribution of phytohormones and their crosstalk to the ontogenesis of ectomycorrhizae (ECM) between grey poplar (Populus tremula x alba) roots and the fungus Laccaria bicolor. To obtain the hormonal blueprint of developing ECM, we quantified the concentrations of jasmonates, gibberellins, and salicylate via liquid chromatography-tandem mass spectrometry. Subsequently, we assessed root architecture, mycorrhizal morphology, and gene expression levels (RNA sequencing) in phytohormone-treated poplar lateral roots in the presence or absence of L. bicolor. Salicylic acid accumulated in mid-stage ECM. Exogenous phytohormone treatment affected the fungal colonization rate and/or frequency of Hartig net formation. Colonized lateral roots displayed diminished responsiveness to jasmonate but regulated some genes, implicated in defense and cell wall remodelling, that were specifically differentially expressed after jasmonate treatment. Responses to salicylate, gibberellin, and ethylene were enhanced in ECM. The dynamics of phytohormone accumulation and response suggest that jasmonate, gibberellin, salicylate, and ethylene signalling play multifaceted roles in poplar L. bicolor ectomycorrhizal development

Acquisition of host-derived carbon in biomass of the ectomycorrhizal fungus Pisolithus microcarpus is correlated to fungal carbon demand and plant defences

Ectomycorrhizal (ECM) fungi are key players in forest carbon (C) sequestration, receiving a substantial proportion of photosynthetic C from their forest tree hosts in exchange for plant growth-limiting soil nutrients. However, it remains unknown whether the fungus or plant controls the quantum of C in this exchange, nor what mechanisms are involved. Here, we aimed to identify physiological and genetic properties of both partners that influence ECM C transfer. Using a microcosm system, stable isotope tracing, and transcriptomics, we quantified plant-to-fungus C transfer between the host plant Eucalyptus grandis and nine isolates of the ECM fungus Pisolithus microcarpus that range in their mycorrhization potential and investigated fungal growth characteristics and plant and fungal genes that correlated with C acquisition. We found that C acquisition by P. microcarpus correlated positively with both fungal biomass production and the expression of a subset of fungal C metabolism genes. In the plant, C transfer was not positively correlated to the number of colonized root tips, but rather to the expression of defence- and stress-related genes. These findings suggest that C acquisition by ECM fungi involves individual fungal demand for C and defence responses of the host against C drain

Generation of homogeneous midbrain organoids with in vivo-like cellular composition facilitates neurotoxin-based Parkinson\u27s disease modeling

Recent studies have demonstrated the generation of midbrain-like organoids (MOs) from human pluripotent stem cells. However, the low efficiency of MO generation and the relatively immature and heterogeneous structures of the MOs hinder the translation of these organoids from the bench to the clinic. Here we describe the robust generation of MOs with homogeneous distribution of midbrain dopaminergic (mDA) neurons. Our MOs contain not only mDA neurons but also other neuronal subtypes as well as functional glial cells including astrocytes and oligodendrocytes. Furthermore, our MOs exhibit mDA neuron-specific cell death upon treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, indicating that MOs could be a proper human model system for studying the in vivo pathology of Parkinson\u27s disease (PD). Our optimized conditions for producing homogeneous and mature MOs might provide an advanced patient-specific platform for in vitro disease modeling as well as for drug screening for PD

Factors Affecting the Adoption of Gamified Smart Tourism Applications: An Integrative Approach

Considering that the core concerns in sustainability are threats to the survival of humankind and the ecosystems that humans depend on, changing the consumption and production behaviors of individuals and society is inevitable. However, people are reluctant to change their own behavior in support of sustainability goals. This tendency seems to be especially strong in tourism because the main value of tourism is hedonic utility. Thus, the tourism industry is now introducing gamification and smart tourism to shift tourist behavior toward sustainability, but most of studies and practices only focus on the performance and application of gamification without considering customer adoption patterns and perceptions during the process. This study empirically investigated what factors affect the adoption of smart tourism applications that incorporate game elements, using the Google Maps tourist guide program. As an initial approach, we incorporated diverse theoretical approaches: perceived usefulness; perceived ease of use; perceived enjoyment from technology acceptance model; information and interaction motivations from the uses and gratifications theory; the network effect; distributive justice; flow as responses to the game characteristics of smart tourism applications; and information privacy concerns as a negative factor for diffusion. The result showed that hedonic characteristics of the gamified smart tourism application (GSTA) are strong in adoption. Perceived enjoyment had a significant influence on the intention to use, but information quality, related to cognitive experience, did not. The flow and perceived distributive justice associated with the game content were not significant, but the interaction motivation was significant in the research model. The results of this study show that individuals regard a GSTA as a low-level game tool. Also, it is important to preoccupy the smart tourism application market in terms of marketing strategy because the network effect is relevant to both perceived usefulness and perceived enjoyment. We also found that the need to provide personal information would negatively affect the adoption of a gamified smart tourism application

Marinifilum fragile gen. nov., sp. nov., isolated from tidal flat sediment

A facultatively anaerobic, moderately halophilic, Gram-negative, filamentous bacterium, designated JC2469(T), was isolated from tidal flat sediment in Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate belonged to the phylum Bacteroidetes and its closest taxonomic relative was Cytophaga fermentans NCIMB 2218(T) (89.6% sequence similarity). Cells appeared as filaments during exponential growth, but became fragmented to rods at stationary phase. Spherical cells were also observed in aged cultures. Strain JC2469(T) contained iso-C(15:0) (56.2%) and MK-7 as the predominant fatty acid and respiratory quinone, respectively. On the basis of evidence from this polyphasic study, the isolate showed substantial differences from other genera. The phylogenetic and physiological data of the present study strongly suggest that the isolate represents a novel genus and species, for which the name Marinifilum fragile gen. nov., sp. nov. is proposed. The type strain of Marinifilum fragile is JC2469(T) (=IMSNU 14138(T) =KCTC 22488(T) =JCM 15579(T)).

Large-Scale Synthesis of MOF-Derived Superporous Carbon Aerogels with Extraordinary Adsorption Capacity for Organic Solvents

© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Carbon aerogels (CAs) with 3D interconnected networks hold promise for application in areas such as pollutant treatment, energy storage, and electrocatalysis. In spite of this, it remains challenging to synthesize high-performance CAs on a large scale in a simple and sustainable manner. We report an eco-friendly method for the scalable synthesis of ultralight and superporous CAs by using cheap and widely available agarose (AG) biomass as the carbon precursor. Zeolitic imidazolate framework-8 (ZIF-8) with high porosity is introduced into the AG aerogels to increase the specific surface area and enable heteroatom doping. After pyrolysis under inert atmosphere, the ZIF-8/AG-derived nitrogen-doped CAs show a highly interconnected porous mazelike structure with a low density of 24 mg cm−3, a high specific surface area of 516 m2 g−1, and a large pore volume of 0.58 cm−3 g−1. The resulting CAs exhibit significant potential for application in the adsorption of organic pollutants

Comparative approach to capture bacterial diversity of coastal waters

Despite the revolutionary advancements in DNA sequencing technology and cultivation techniques, few studies have been done to directly compare these methods. In this study, a 16S rRNA gene-based, integrative approach combining culture-independent techniques with culture-dependent methods was taken to investigate the bacterial community structure of coastal seawater collected from the Yellow Sea, Korea. For culture-independent studies, we used the latest model pyrosequencer, Roche/454 Genome Sequencer FLX Titanium. Pyrosequencing captured a total of 52 phyla including 27 candidate divisions from the water column, whereas the traditional cloning approach captured only 15 phyla including 2 candidate divisions. In addition, of 878 genera retrieved, 92.1% of the sequences were unique to pyrosequencing. For culture-dependent analysis, plate culturing, plate washing, enrichment, and high-throughput culturing (HTC) methods were applied. Phylogenetic analysis showed that the plate-washing clones formed a cluster devoid of any previously cultured representatives within the family Rhodobacteraceae. One HTC isolate (SF293) fell into the OM182 clade, which was not recovered by other culturing methods described here. By directly comparing the sequences obtained from cultures with those from culture-independent work, we found that only 33% of the culture sequences were identical to those from clone libraries and pyrosequences. This study presents a detailed comparison of common molecular and cultivation techniques available in microbial ecology. As different methods yielded different coverage, we suggest choosing the approach after carefully examining the scientific questions being asked.

Thermomagnetic properties and magnetocaloric effect of FeCoNiCrAl-type high-entropy alloys

In this work, we investigate the effects of substituting Ni/Al for Cr on the thermomagnetic and magnetocaloric properties of FeCoNiCrAl-type high entropy alloys (HEAs). Ni and Al appear to prefer the BCC phase, and increases in the Al composition appear to stabilize the BCC phase. In contrast to Al, Ni content yields an increase in the FCC phase fraction, resulting in a drop off in magnetization. The phase transformation from BCC to FCC was intensified at annealing temperatures of 800 °C and higher due to increased diffusion rates and the resulting spinodal decomposition. A magnetic phase transition around 150 K was found in the FeCoNi1.5Cr0.5Al annealed alloy potentially corresponding to the FCC phase, and a very broad magnetic phase transition was observed in the annealed FeCoNiCrAl alloy, resulting in a high refrigerant capacity of RCFWHM = 242.6 J⋅kg-1 near room temperature. A peak magnetic entropy change of −ΔSM = 0.674 J⋅kg-1⋅K-1 was also obtained at applied fields of ∼70 kOe at 290 K in the FeCoNiCrAl HEA. These magnetocaloric values are comparable to Fe-based metallic glasses such as Fe-Tm-B-Nb and Fe-Zr-B-Co alloys, with a similar transition near room temperature

Influence of Shape Anisotropy and Temperature on Magnetostrictive Behaviors in Single Crystal Galfenol Alloys

Fe-Ga (Galfenol) is a rare-earth-free alloy with useful magnetostrictive properties of nominal cost with robust mechanical properties advantageous for sensing, actuating and energy harvesting. Magnetostriction in the polycrystalline form is enhanced by abnormal grain growth of Goss texture (110) [100] by rolling and recrystallization of thin sheets. Prior research shows that magnetostriction of Fe81Ga19 was maximized when introduced to a uniform compressive stress in an external field, yielding an increase in magnetostriction with increasing stress as well as increasing magnetic susceptibility, which corresponds to a larger d33 transduction coefficient. Temperature-dependence of magnetostriction and magnetization was also previously investigated, resulting in a 12.9% decrease in magnetostriction from −21°C to +80°C and a corresponding 3.6% decrease in magnetization, demonstrating minimal dependence at low temperatures. Understanding magnetostriction and magnetization behaviors under stresses at the extended temperature ranges from −40°C to 300°C introduces the potential of harsh environment applications of magnetostrictive non-contact torque sensor for use in aerospace rotorcraft designs which operate at extreme temperatures. Galfenol thin patches have the potential to operate in engines and rotator shafts, but device performance at these temperature ranges has not been studied. Thus, in this work, we investigate simultaneous effects of temperature and external stresses on magnetic and magnetostrictive behaviors at temperatures from −40°C to 300°C for single crystal Fe-Ga samples. Prior to these works, (001)-oriented Galfenol single crystals with different shapes were examined for evaluating magnetostrictive performance when magnetized. Preliminary data from a Vibrating Sample Magnetometer (VSM) produced linear regions of magnetostriction versus normalized magnetization for a rectangular single crystal Fe80.2Ga19.8 sample of different orientations through a range of applied fields, as shown in Fig. 1. Figure 1(b) more closely illustrates the largest linear portion from normalized magnetism of about 0.35 to 0.8 of the sample corresponding to applied fields along the short direction and likewise Figure 1(c) more closely illustrates the largest linear portions of normalized magnetism of about 0.55 to 0.8 for the long direction orientation. For a circular Fe Fe82.5Ga17.5 sample, the linear region of normalized magnetism extends from 0 to around 0.7, as shown in Fig. 2. This data indicates that shape anisotropy effects are most evident in the circular sample and the rectangular sample aligned along the short direction with a parallel applied field, based on increased dλ/dH and thus faster magnetization from external fields, H. This proportionality between magnetostriction and normalized magnetism suggests a higher magnetic susceptibility corresponding to high shape anisotropy, an important relationship for sensing applications. Building upon this observation, this work attempts to relate temperature-dependence and shape anisotropy to determine the effect on magnetic susceptibility at extreme temperatures. To study this dependence, an insulated thermal chamber enclosing a heat source and pre-stress device will constrain the rectangular single crystal Fe80.2Ga19.8 sample. Despite a larger dλ/dH for the circular sample the testing of stress requires a rectangular single crystal Galfenol sample, which is oriented in the (001) plane with a magnetostriction value of about ~260 ppm. The sample will be subjected to various temperatures up to ~300 °C where simultaneous magnetostriction and magnetization values will be acquired. Based on previously observed models, a Magnetic Optic Kerr Effect (MOKE) system will confirm hypothesized effects of shape anisotropy and observed magnetic susceptibility by illustrating magnetic domain wall rotation throughout the procedure. Understanding the roles of extreme temperatures and compressive stress on magnetostrictive alloys will provide an enhanced understanding of the material properties and thus allow a wider range of beneficial applications