Biology subjects

Hayashi, T.

Publications and source records attributed to Hayashi, T..

At least 73 records · Page 4Linked to original sources

bioRxiv2022

Tiling mechanisms of the compound eye through geometrical tessellation

Tilling patterns are observed in many biological structures. Hexagonal tilling, commonly observed in the compound eyes of wild-type Drosophila, is dominant in nature; this dominance can probably be attributed to physical restrictions such as structural robustness, minimal boundary length, and space filling efficiency. Surprisingly, tetragonal tiling patterns are also observed in some Drosophila small eye mutants and aquatic crustaceans. Herein, geometrical tessellation is shown to determine the ommatidial tiling patterns. In small eye mutants, the hexagonal pattern is transformed into a tetragonal pattern as the relative positions of neighboring ommatidia are stretched along the dorsal-ventral axis. Hence, the regular distribution of ommatidia and their uniform growth collectively play an essential role in the establishment of tetragonal and hexagonal tiling patterns in compound eyes.

developmental biology↗

bioRxiv2021

LIFELONG CYTOMEGALOVIRUS AND EARLY-LIFE IRRADIATION SYNERGISTICALLY POTENTIATE AGE-RELATED DEFECTS IN RESPONSE TO VACCINATION AND INFECTION

A popular "DNA-damage theory" of aging posits that unrepaired DNA damage leads to cellular (and organismal) senescence. Indeed, some hallmarks of immune aging are more prevalent in individuals exposed to Whole-Body Irradiation (WBI). To test this hypothesis in a model relevant to human immune aging, we examined separate and joint effects of lifelong latent Murine Cytomegalovirus (MCMV) and early-life WBI (i) over the course of the lifespan; (ii) in response to a West Nile virus (WNV) live attenuated vaccine; and (iii) following lethal WNV challenge subsequent to vaccination. We recently published that a single dose of non-lethal WBI in youth, on its own, was not sufficient to accelerate aging of the murine immune system despite causing widespread DNA damage and repopulation stress in hematopoietic cells. However, 4Gy sub-lethal WBI caused manifest reactivation of MCMV. Following vaccination and challenge with WNV in the old age, MCMV-infected animals experiencing 4Gy, but not lower, dose of sub-lethal WBI in youth had reduced survival. By contrast, old irradiated mice lacking MCMV and MCMV-infected, but not irradiated, mice were both protected to the same high level as the old non-irradiated, uninfected controls. Analysis of the quality and quantity of anti-WNV immunity showed that higher mortality in MCMV-positive WBI mice correlated with increased levels of MCMV-specific immune activation during WNV challenge. Moreover, we demonstrate that infection, including that by WNV, led to MCMV reactivation. Our data suggest that MCMV reactivation may be an important determinant of increased late-life mortality following early-life irradiation and late-life acute infection.

immunology↗

bioRxiv2021

Mushroom body input connections form independently of sensory activity in Drosophila melanogaster

Associative brain centers, such as the insect mushroom body, need to represent sensory information in an efficient manner. In Drosophila melanogaster, the Kenyon cells of the mushroom body integrate inputs from a random set of olfactory projection neurons, but some projection neurons -- namely those activated by a few ethologically meaningful odors -- connect to Kenyon cells more frequently than others. This biased and random connectivity pattern is conceivably advantageous, as it enables the mushroom body to represent a large number of odors as unique activity patterns while prioritizing the representation of a few specific odors. How this connectivity pattern is established remains largely unknown. Here, we test whether the mechanisms patterning the connections between Kenyon cells and projection neurons depend on sensory activity or whether they are hardwired. We mapped a large number of mushroom body input connections in anosmic flies -- flies lacking the obligate odorant co-receptor Orco -- and in wildtype flies. Statistical analyses of these datasets reveal that the random and biased connectivity pattern observed between Kenyon cells and projection neurons forms normally in the absence of most olfactory sensory activity. This finding supports the idea that even comparatively subtle, population-level patterns of neuronal connectivity can be encoded by fixed genetic programs and are likely to be the result of evolved prioritization of ecologically and ethologically salient stimuli.

neuroscience↗

bioRxiv2021

Fluctuation of cellular differentiation in limb regeneration is regulated by Pde4b in urodele amphibians

Urodele amphibians, Pleurodeles waltl and Ambystoma mexicanum, have organ-level regeneration capability, such as limb regeneration. Multipotent cells are induced by an endogenous mechanism in amphibian limb regeneration. It is well known that dermal fibroblasts receive regenerative signals and turn into multipotent cells, called blastema cells. However, the induction mechanism of the blastema cells from matured dermal cells was unknown. We previously found that BMP2, FGF2, and FGF8 (B2FF) could play sufficient roles in blastema induction in urodele amphibians. Here, we show that B2FF treatment can induce dermis-derived cells that can participate in multiple cell lineage in limb regeneration. We first established a newt dermis-derived cell line and confirmed that B2FF treatment on the newt cells provided plasticity in cellular differentiation in limb regeneration. Interspecies comparative analysis clarified that Pde4b upregulation by B2FF specifically took place in the newt cells. Blocking PDE4B signaling by Rolipram suppressed dermis-to-cartilage transformation and the mosaic knockout animals showed consistent results. Our results are a valuable insight into how dermal fibroblasts acquire multipotency during the early phase of limb regeneration via an endogenous program in amphibian limb regeneration.

developmental biology↗

bioRxiv2021

Transmit Field Bias Correction of T1w/T2w Myelin Maps

T1-weighted divided by T2-weighted (T1w/T2w) myelin maps were initially developed for neuroanatomical analyses such as identifying cortical areas, but they are increasingly used in statistical comparisons across individuals and groups with other variables of interest. Existing T1w/T2w myelin maps contain radiofrequency transmit field (B1+) biases, which may be correlated with these variables of interest, leading to potentially spurious results. Here we propose two empirical methods for correcting these transmit field biases using either explicit measures of the transmit field or alternatively a pseudo-transmit approach that is highly correlated with the transmit field at 3T. We find that the resulting corrected T1w/T2w myelin maps are both better neuroanatomical measures (e.g., for use in cross-species comparisons), and more appropriate for statistical comparisons of relative T1w/T2w differences across individuals and groups (e.g., sex, age, or body-mass-index) within a consistently acquired study at 3T. We recommend that investigators who use the T1w/T2w approach for mapping cortical myelin use these B1+ transmit field corrected myelin maps going forward.

neuroscience↗

bioRxiv2021

Imaging and single cell sequencing analyses of super-enhancer activation mediated by NF-κB in B cells

The transcription factor NF-{kappa}B, which plays an important role in cell fate determination, is involved in the activation of super-enhancers (SEs). However, the biological functions of the NF-{kappa}B SEs in gene control are not fully elucidated. We investigated the characteristics of NF-{kappa}B-mediated SE activity using fluorescence live-cell imaging of RelA, single-cell transcriptome, and chromatin accessibility analyses in anti-IgM-stimulated B cells. Cell stimulation induced nuclear foci formation of RelA and gene expression in a switch-like manner. The gained SEs induced a higher fold-change expression and enhanced cell-to-cell variability in transcriptional response. These properties were correlated with the number of gained cis-regulatory interactions, while switch-like gene induction was associated with the number of NF-{kappa}B binding sites in SE. Our study suggests that NF-{kappa}B SEs have unique roles for quantitative control of gene expression through direct binding to accessible DNA and enhanced DNA contacts.

molecular biology↗

bioRxiv2021

Dasabuvir inhibits human norovirus infection in human intestinal enteroids

Human noroviruses (HuNoVs) are acute viral gastroenteritis pathogens that affect all age groups, yet no approved vaccines and drugs to treat HuNoV infection are available. In this study, with a human intestinal enteroid (HIE) culture system where HuNoVs are able to replicate reproducibly, we screened an antiviral compound library to identify compound(s) showing anti-HuNoV activity. Dasabuvir, which has been developed as an anti-hepatitis C virus agent, was found to inhibit HuNoV infection in HIEs at micromolar concentrations. Dasabuvir also inhibited severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and human A rotavirus (RVA) infection in HIEs. To our knowledge, this is the first study to screen an antiviral compound library for HuNoV using HIEs and we successfully identified dasabuvir as a novel anti-HuNoV inhibitor that warrants further investigation.

microbiology↗

bioRxiv2021

Identification of the CoA-ester intermediates and genes involved in the cleavage and degradation of the steroidal C-ring by Comamonas testosteroni TA441

Comamonas testosteroni TA441 degrades steroids aerobically via aromatization of the A-ring accompanied by B-ring cleavage, followed by D- and C-ring cleavage. We previously revealed major enzymes and intermediate compounds in A,B-ring cleavage, {beta}-oxidation cycle of the cleaved B-ring, and partial C,D-ring cleavage process. Here, we elucidated the C-ring cleavage and the {beta}-oxidation cycle that follows. ScdL1L2, a 3-ketoacid Coenzyme A (CoA) transferase which belongs to the SugarP_isomerase superfamily, was thought to cleave the C-ring of 9-oxo-1,2,3,4,5,6,10,19-octanor-13,17-secoandrost-8(14)-ene-7,17-dioic acid-CoA ester, the key intermediate compound in the degradation of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid (3a-H-4 [3'-propionic acid]-7a{beta}-methylhexahydro-1,5-indanedione; HIP)-CoA ester in the previous study; however, this study suggested that ScdL1L2 is the isomerase of the derivative with a hydroxyl group at C-14 which cleaves C ring. The subsequent ring-cleaved product was indicated to be converted to 4-methyl-5-oxo-octane-1,8-dioic acid-CoA ester mainly by ORF33-encoded CoA-transferase (named ScdJ), followed by dehydrogenation by ORF21 and 22-encoded acyl-CoA dehydrogenase (named ScdM1M2). Then a water molecule is added by ScdN for further degradation by {beta}-oxidation. ScdN is considered to catalyze the last reaction in C,D-ring degradation by the enzymes encoded in the steroid degradation gene cluster tesB to tesR. IMPORTANCEStudies on bacterial steroid degradation were initiated more than 50 years ago primarily to obtain materials for steroid drugs. Steroid-degrading bacteria are globally distributed, and the role of bacterial steroid degradation in the environment as well as in human is attracting attention. The overall degradation of steroidal four rings is proposed, however there are still much to be revealed to understand the complete degradation pathway. This study aims to uncover the whole steroid degradation process in C. testosteroni, which is one of the most studied representative steroid degrading bacteria and is suitable for exploring the degradation pathway because the involvement of degradation-related genes can be determined by gene disruption.

microbiology↗

bioRxiv2021

Bi-phasic effect of gelatin in myogenesis and skeletal muscle regeneration

Skeletal muscle regeneration requires extracellular matrix (ECM) remodeling including an acute and transient breakdown of collagen that produces gelatin. However, the physiological function of such a remodeling process on muscle tissue repair is unclear. Here we elaborate on a bi-phasic effect of gelatin in skeletal muscle regeneration, mediated by hormetic effects of reactive oxygen species (ROS). Low-dose gelatin stimulates ROS production from NADPH oxidase 2 (NOX2) and simultaneously upregulates antioxidant system for cellular defense, reminiscent of the adaptive compensatory process during mild stress. This response triggers the release of myokine IL-6 which stimulates myogenesis and facilitates muscle regeneration. By contrast, high-dose gelatin stimulates ROS overproduction from NOX2 and mitochondrial chain complex, and ROS accumulation by suppressing antioxidant system, triggering release of TNF, which inhibits myogenesis and regeneration. Our findings reveal gelatin-ROS-IL-6/TNF signaling cascades underlying a hormetic response of myogenic cells to gelatin.

physiology↗

bioRxiv2021

The 3' end of the human norovirus antigenomic sequence is required for its genomic RNA synthesis by RNA-dependent RNA polymerase

Norovirus genome is a single-stranded positive-strand RNA. To reveal the mechanism underlying the initiation of the norovirus genomic RNA synthesis by its RNA-dependent RNA polymerase (RdRp), we used an in vitro assay to detect the complementary RNA synthesis activity. Results showed that the purified recombinant RdRp synthesized the complementary positive-sense RNA from the 100 nt template corresponding to the 3' end region of the viral antisense genome sequence, but that RdRp did not synthesize the antisense genomic RNA from the 100 nt template, corresponding to the 5' end region of the positive-sense genome sequence. The 31 nt region at the 3' end of the RNA antisense template was then predicted to form the stem-loop structure. Its deletion resulted in the loss of complementary RNA synthesis by RdRp. The connection of the 31 nt to the 3' end of the positive-sense RNA template allowed to be recognized by the RdRp. Similarly, an electrophoretic mobility shift assay further revealed that RdRp bound to the antisense RNA specifically, but the 31 nt deletion at the 3' end lost the binding to RdRp. Therefore, combining this observation with further deletion and mutation analysis, we concluded that the predicted stem-loop structure in the 31 nt and region close to the antisense viral genomic stem sequences are important for initiating the positive-sense human norovirus genomic RNA synthesis by its RdRp.

microbiology↗

bioRxiv2021

Identification of essential β-oxidation genes and corresponding metabolites for estrogen degradation by actinobacteria

Steroidal estrogens (C18) are contaminants receiving increasing attention due to their endocrine-disrupting activities at sub-nanomolar concentrations. Although estrogens can be eliminated through photodegradation, microbial function is critical for removing estrogens from ecosystems devoid of sunlight exposure including activated sludge, soils, and aquatic sediments. Actinobacteria were found to be key estrogen degraders in manure-contaminated soils and estuarine sediments. Previously, we used the actinobacterium Rhodococcus sp. strain B50 as a model microorganism to identify two oxygenase genes, aedA and aedB, involved in the activation and subsequent cleavage of the estrogenic A-ring, respectively. However, genes responsible for the downstream degradation of estrogen A/B-rings remained completely unknown. In this study, we employed tiered comparative transcriptomics, gene disruption experiments, and mass spectrometry-based metabolite profile analysis to identify estrogen catabolic genes. We observed the up-regulation of thiolase-encoding aedF and aedK in the transcriptome of strain B50 grown with estrone. Consistently, two downstream estrogenic metabolites, 5-oxo-4-norestrogenic acid (C17) and 2,3,4-trinorestrogenic acid (C15), were accumulated in aedF- and aedK-disrupted strain B50 cultures. Disruption of fadD3 [3a-H-4(3-propanoate)-7a{beta}-methylhexahydro-1,5-indanedione (HIP)-coenzyme A ligase gene] in strain B50 resulted in apparent HIP accumulation in estrone-fed cultures, indicating the essential role of fadD3 in actinobacterial estrogen degradation. In addition, we detected a unique meta-cleavage product, 4,5-seco-estrogenic acid (C18), during actinobacterial estrogen degradation. Differentiating the estrogenic metabolite profile and degradation genes of actinobacteria and proteobacteria enables the cost-effective and time-saving identification of potential estrogen degraders in various ecosystems through liquid chromatography-mass spectrometry analysis and polymerase chain reaction-based functional assays.

microbiology↗

bioRxiv2021

Insights into the acquisition of the pks island and production of colibactin in the Escherichia coli population

The pks island codes for the enzymes necessary for synthesis of the genotoxin colibactin, which contributes to the virulence of Escherichia coli strains and is suspected of promoting colorectal cancer. From a collection of 785 human and bovine E. coli isolates, we identified 109 strains carrying a highly conserved pks island, mostly from the phylogroup B2, but also from phylogroups A, B1 and D. Different scenarios of pks acquisition were deduced from whole genome sequence and phylogenetic analysis. In the main scenario, pks was introduced and stabilized into certain sequence types (ST) of the B2 phylogroup, such as ST73 and ST95, at the asnW tRNA locus located in the vicinity of the yersiniabactin-encoding High Pathogenicity Island (HPI). In a few B2 strains, pks inserted at the asnU or asnV tRNA loci close to the HPI and occasionally was located next to the remnant of an integrative and conjugative element. In a last scenario specific to B1/A strains, pks was acquired, independently of the HPI, at a non-tRNA locus. All the pks-positive strains except 18 produced colibactin. Sixteen strains contained mutations in clbB or clbD, or a fusion of clbJ and clbK and were no longer genotoxic but most of them still produced low amount of potentially active metabolites associated with the pks island. One strain was fully metabolically inactive without pks alteration, but colibactin production was restored by overexpressing the ClbR regulator. In conclusion, the pks island is not restricted to human pathogenic B2 strains and is more widely distributed in the E. coli population, while preserving its functionality. IMPACT STATEMENTColibactin, a genotoxin associated with the carcinogenicity of certain strains of E. coli, is encoded by a pathogenicity island called pks. We took advantage of a large collection of non-clinical E. coli strains originating from human and bovine hosts to explore the distribution, conservation and functionality of the pks island. We found that the pks island was not only present in the phylogroup B2 (and more specifically to certain B2 sublineages), but also in other genetic phylogroups, highlighting its capacity to disseminate though horizontal gene transfer. We identified various genetic pks configurations indicative of an introduction of the pks island into E. coli on multiple independent occasions. Despite the existence of various acquisition scenarios, we found that the pks sequences were highly conserved and pks-carrying strains were overwhelmingly capable of producing colibactin, suggesting that the pks island is under selective pressure, through the production of colibactin or other secondary metabolites. Future implications include the identification of such metabolites and their biological activities that could be advantageous to E. coli and enable its adaptation to various ecological niches. DATA SUMMARYAll sequence data of the 785 E. coli used in this study are freely available from the NCBI BioProject database (https://www.ncbi.nlm.nih.gov/bioproject/) under the accession number PRJDB5579. This database was updated to include the sequence data obtained using ONT MinION for the E. coli reference strain SP15 and for E. coli strains ECSC054, JML285, KS-NP019, NS-NP030 and SI-NP020. The sequence data of E. coli strain UPEC129 obtained using PacBio instrument were deposited in the NCBI BioProject database and are available at https://www.ncbi.nlm.nih.gov/Traces/study/ under the accession number PRJNA669570. Hybrid MinION-Illumina and PacBio-Illumina assemblies are available at the NCBI nucleotide database. The genome sequences of 36 other E. coli reference strains and 7 non-E. coli strains were retrieved from NCBI.

microbiology↗

bioRxiv2021

Naming-related spectral responses predict neuropsychological outcome after epilepsy surgery

This prospective study determined the utility of intracranially-recorded spectral responses during naming tasks in predicting neuropsychological performance following epilepsy surgery. We recruited 65 patients with drug-resistant focal epilepsy who underwent preoperative neuropsychological assessment and intracranial EEG (iEEG) recording. The Clinical Evaluation of Language Fundamentals (CELF) evaluated the baseline and postoperative language function. During extraoperative iEEG recording, we assigned patients to undergo auditory and picture naming tasks. Time-frequency analysis determined the spatiotemporal characteristics of naming-related amplitude modulations, including high gamma augmentation (HGA) at 70-110 Hz. We surgically removed the presumed epileptogenic zone based on the extent of iEEG and MRI abnormalities while maximally preserving the eloquent areas defined by electrical stimulation mapping (ESM). The multivariate regression model incorporating auditory naming-related HGA predicted the postoperative changes in Core Language Score (CLS) on CELF with r2 of 0.37 (p = 0.015) and in Expressive Language Index (ELI) with r2 of 0.32 (p = 0.047). Independently of the effects of epilepsy and neuroimaging profiles, higher HGA at the resected language-dominant hemispheric area predicted a more severe postoperative decline in CLS (p = 0.004) and ELI (p = 0.012). Conversely, the model incorporating picture naming-related HGA predicted the change in Receptive Language Index (RLI) with r2 of 0.50 (p < 0.001). Higher HGA independently predicted a more severe postoperative decline in RLI (p = 0.03). Ancillary regression analysis indicated that naming-related low gamma augmentation as well as alpha/beta attenuation likewise independently predicted a more severe CLS decline. The machine learning-based prediction model, referred to as the boosted tree ensemble model, suggested that naming-related HGA, among all spectral responses utilized as predictors, most strongly contributed to the improved prediction of patients showing a >5-point CLS decline (reflecting the lower 25 percentile among patients). We generated the model-based atlas visualizing sites, which, if resected, would lead to such a CLS decline. The auditory naming-based model predicted patients who developed the CLS decline with an accuracy of 0.80. The model indicated that virtual resection of an ESM-defined language site would have increased the relative risk of the CLS decline by 5.28 (95%CI: 3.47 to 8.02). Especially, that of an ESM-defined receptive language site would have maximized it to 15.90 (95%CI: 9.59-26.33). In summary, naming-related spectral responses predict objectively-measured neuropsychological outcome after epilepsy surgery. We have provided our prediction model as an open-source material, which will indicate the postoperative language function of future patients and facilitate external validation at tertiary epilepsy centers.

neuroscience↗

bioRxiv2021

Codependency and mutual exclusivity for gene community detection from sparse single-cell transcriptome data

Single-cell RNA-seq (scRNA-seq) can be used to characterize cellular heterogeneity in thousands of cells. The reconstruction of a gene network based on coexpression patterns is a fundamental task in scRNA-seq analyses, and the mutual exclusivity of gene expression can be critical for understanding such heterogeneity. Here, we propose an approach for detecting communities from a genetic network constructed on the basis of coexpression properties. The community-based comparison of multiple coexpression networks enables the identification of functionally related gene clusters that cannot be fully captured through differential gene expression-based analysis. We also developed a novel metric referred to as the exclusively expressed index (EEI) that identifies mutually exclusive gene pairs from sparse scRNA-seq data. EEI quantifies and ranks the exclusive expression levels of all gene pairs from binary expression patterns while maintaining robustness against a low sequencing depth. We applied our methods to glioblastoma scRNA-seq data and found that gene communities were partially conserved after serum stimulation despite a considerable number of differentially expressed genes. We also demonstrate that the identification of mutually exclusive gene sets with EEI can improve the sensitivity of capturing cellular heterogeneity. Our methods complement existing approaches and provide new biological insights, even for a large, sparse dataset, in the single-cell analysis field.

bioinformatics↗

bioRxiv2021

Genome-wide association study of gastric cancer- and duodenal ulcer-derived Helicobacter pylori strains reveals discriminatory amino acid differences and novel oncoprotein candidates

Genome-wide association studies (GWASs) can reveal genetic variations associated with a phenotype in the absence of any hypothesis of candidate genes. The problem of false-positive sites linked with the responsible site might be bypassed in bacteria with a high homologous recombination rate, such as Helicobacter pylori, which causes gastric cancer (GC). We conducted a GWAS followed by regression-based prediction of GC and duodenal ulcer H. pylori strains. We identified 14 single nucleotide polymorphisms (11 amino acid changes) that, combined, allowed effective disease discrimination. They were often informative of the underlying molecular mechanisms, such as electric charge alteration at the ligand-binding pocket, alteration in subunit interaction, and mode-switching of DNA methylation. We also identified three novel virulence factors/oncoprotein candidates. These results provide both defined targets for further informatic and experimental analyses to gain insights into GC pathogenesis and a basis for identifying a set of biomarkers for application in clinical settings.

physiology↗

bioRxiv2021

SIPA1L1/SPAR1 is a non-PSD protein involved in GPCR signaling

SIPA1L1 (also known as SPAR1) has been proposed to regulate synaptic functions that are important in maintaining normal neuronal activities, such as regulating spine growth and synaptic scaling, as a component of the postsynaptic density (PSD)-95/N-methyl-D-aspartate receptor (NMDA-R)-complex. However, contrary to this view, our super-resolution and immunoelectron microscopic analyses demonstrate that SIPA1L1 is mainly localized to general submembranous and cytoplasmic regions in neurons, but scarcely to PSD. Our screening for native interactors of SIPA1L1 identified spinophilin and neurabin-1, regulators of G protein-coupled receptor (GPCR) signaling, but rejected PSD-95/NMDA-R-complex components. Furthermore, Sipa1l1-/- mice showed normal spine size distribution and NMDA-R-dependent synaptic plasticity. Nevertheless, Sipa1l1-/- mice showed aberrant responses to 2-adrenergic receptor (a spinophilin target) or adenosine A1 receptor (a neurabin-1 target) agonist stimulation and striking behavioral anomalies, such as hyperactivity, enhanced anxiety, learning impairments, social interaction deficits, and enhanced epileptic seizure susceptibility. Our findings revealed unexpected properties of SIPA1L1, suggesting a possible association of SIPA1L1 deficiency with neuropsychiatric disorders related to dysregulated GPCR signaling, such as epilepsy, attention deficit hyperactivity disorder (ADHD), autism, or fragile X syndrome.

neuroscience↗

bioRxiv2020

Effect of RBD mutation (Y453F) in spike glycoprotein of SARS-CoV-2 on neutralizing antibody affinity

Natural selection "adaptation" in the coronavirus can occur during coronavirus amplification in vivo in farmed minks. Natural selection in such viruses is observed by introduction of mutations in SARS- CoV-2 that are not observed during the growth process in humans. Infection with a mutant (Y453F) of SARS-CoV-2 from farmed minks is known to widely spread among humans. We investigated the virological characteristics of this SARS-CoV-2 mutant (Y453F) using three-dimensional protein structural analysis. Our experimental study suggests that virus variants with the Y453F mutation partially escaped detection by four neutralizing monoclonal antibodies. The spread of SARS-CoV-2 variants mediated by millions of infected farmed minks is uncontrolled; consequently, raising a concern that infection of SARS-CoV-2 mutants that cause serious symptoms in humans may spread globally.

microbiology↗

bioRxiv2020

Impact of COVID-19: Decrease in the Number of Fledging Barn Swallow Chicks in Tokyo

Barn swallows that have crossed the sea from Southeast Asia usually appear in the Kyushu Region of Japan around March after passing through Okinawa Prefecture. When the climate becomes warmer, these birds then move further north, nesting and raising their chicks in various parts of Japan. It is worth noting that barn swallows typically nest on man-made objects, for example, the roofs of houses and barns. It is believed that this is because barn swallows protect their eggs and chicks from foreign enemies such as sparrows and crows so they build their nests in populated areas. The barn swallows behavior of using the presence of people to keep foreign enemies away shows that barn swallows are quite wise. However, it has been reported that from the spring to summer of 2020, barn swallows, nesting and raising their chicks, which were seen every year, were not found in various parts of Japan. Therefore, we investigated the relationship between peoples self-restraint from going out and the fledging of barn swallow chicks in Tokyo metropolitan during the corona virus disease 2019 (COVID-19) era. The results of the survey showed a link between peoples refraining from going out and the fledging of barn swallow chicks. Next spring of 2021, the termination of COVID-19 is an important environment for swallow chick fledging.

ecology↗