Biology subjects

Ikeda, S.

Publications and source records attributed to Ikeda, S..

31 records · Page 2Linked to original sources

bioRxiv2022

More accurate analysis of maternal effect genes by siRNA electroporation into mouse oocytes

Maternal RNAs and proteins accumulate in mouse oocytes and control the initial stages of development. The DNA in sperm combines with protamine, which is exchanged after fertilization with maternal histones, including H3.3, but the effect of H3.3 on post-fertilization development has been unclear. In this study, we established an electroporation method to introduce H3.3 siRNA into germinal vesicle (GV)-stage oocytes without removing cumulus cells. In the traditional microinjection method, cumulus cells attached to oocytes must be removed; however, we confirmed that artificially removing cumulus cells from oocytes reduced fertilization rates, and oocytes originally free of cumulus cells had reduced developmental competence. When H3.3 siRNA was introduced at the GV stage, H3.3 was still present in the maternal pronucleus and second polar body, but not in the paternal pronucleus, resulting in embryonic lethality after fertilization. This indicates that the H3.3 protein was not incorporated into the paternal pronucleus because it was repeatedly translated and degraded in a relatively short time. On the other hand, H3.3 protein incorporated into the maternal genome in the GV stage escaped degradation and remained in the maternal pronucleus after fertilization. This new method of electroporation into GV-stage oocytes without removing cumulus cells is not skill intensive and is essential for the accurate analysis of maternal effect genes. In briefFor analysis of maternal factors contained in the oocyte, suppression of genes within the oocyte is necessary. In this paper, siRNA was introduced into oocytes by electroporation, showing that maternal mRNA was suppressed efficiently.

developmental biology↗

bioRxiv2022

Chimeric PRMT6 protein produced by an endogenous retrovirus promoter regulates cell fate decision in mouse preimplantation embryos

Murine endogenous retrovirus with leucine tRNA primer, also known as MERVL, is expressed during zygotic genome activation in mammalian embryos. Here we show that protein arginine N-methyltransferase 6 (Prmt6) forms a chimeric transcript with MT2B2, one of the long terminal repeat sequences of MERVL, and is translated into an elongated chimeric protein (PRMT6MT2B2) whose function differs from that of the canonical PRMT6 protein (PRMT6CAN) in mouse preimplantation embryos. Overexpression of PRMT6CAN in fibroblast cells increased asymmetric dimethylation of the third arginine residue of both histone H2A (H2AR3me2a) and histone H4 (H4R3me2a), while overexpression of PRMT6MT2B2 increased only H2AR3me2a. In addition, overexpression of PRMT6MT2B2 in one blastomere of mouse two-cell embryos promoted cell proliferation and differentiation of the blastomere into epiblast cells at the blastocyst stage, while overexpression of PRMT6CAN repressed cell proliferation. This is the first report of the translation of a chimeric protein (PRMT6MT2B2) in mouse preimplantation embryos. Our results suggest that analyzing chimeric transcripts with MERVL will provide insight into the relationship between zygotic genome activation and subsequent intra- and extra-cellular lineage determination.

developmental biology↗

bioRxiv2022

The Administration Effect of Lactic Acid Bacteria Reducing Environmental Alkyl and Fatty Acid Hydroperoxides on Piglets in the Absence of Antimicrobial Agents and in the Presence of Iron

A lactic acid bacterium, Lactiplantibacillus plantarum P1-2 (LpP1-2), can reduce environmental fatty acid hydroperoxides. The administration of LpP1-2 to oxygen-sensitive short-lived nematode mutants and iron-overloaded rats reduced the oxidative stress-related index. Since young piglets have a weak defense system against oxidative stress and are vulnerable to environmental stress, antimicrobial agents have been administered in the rearing. Based on these results, we investigated the effect of LpP1-2 administration to prepartum sows and infant piglets until weaning without antimicrobial agents on the growth of young piglets. The group including both sows and piglets that were administrated with lactic acid bacteria containing LpP1-2 (LABLp) until the end of lactation showed the growth-promoting effect of piglet from lactation to early regular rearing, and even in late regular rearing. Blood biochemical markers were in the normal ranges in both LABLp-administrated and non-administrated groups, but various disease-related markers tended to decrease in the administrated group. To investigate the effects of LABLp administration on postpartum piglets, the piglets born from prenatally LABLp-administrated sows were divided into two groups and then administrated with or without LABLp. The piglets in the LABLp-administrated group tended to grow very slightly higher than those in the non-administrated group from lactation to early regular rearing. After that, the growth in both groups was almost the same. These results suggest that LABLp administration to prepartum sows is essential for the growth-promoting effect. The postnatal LABLp-administrated piglets showed a lower serum lipid peroxidation index than the non-administrated piglets, and had higher numbers of lactic acid bacteria and bifidobacteria in feces at the end of LABLp treatment. In fattening performances, the LABLp-administrated group showed a significant improvement in meat quality. We also discuss the growth and physiological effects by LpP1-2 administration with iron on piglets because iron administration is another important issue in piglet farming.

microbiology↗

bioRxiv2022

Relationship of Rickettsia infection rates and population genetic structure of ixodid ticks along an altitudinal gradient

Ixodid ticks, such as Ixodes ovatus and Haemaphysalis flava, are important vectors of tick-borne diseases in Japan, such as Japanese spotted fever caused by Rickettsia japonica. This study describes the population genetic structure and gene flow of I. ovatus and H. flava and their Rickettsia infection rates along an altitudinal gradient. A total of 346 adult I. ovatus and 243 H. flava were analyzed for the presence of Rickettsia by nested PCR targeting the 17kDA, gltA, rOmpA, and rOmpB genes. Population genetic structure was performed using the mitochondrial cytochrome oxidase 1 (cox1) marker. The Rickettsia infection rates were 13.26% in I. ovatus and 6.17% in H. flava. For I. ovatus, the global FST value revealed significant genetic differentiation among the different populations, whereas H. flava showed non-significant genetic differentiation. The cox1 I. ovatus cluster dendrogram showed two cluster groups, while the haplotype network and phylogenetic tree showed three genetic groups. The two cluster groups and the three genetic groups found in I. ovatus showed a significant difference in their Rickettsia infection rates and mean altitude per group. No significant differences were found in the mean altitude or Rickettsia infection rates of H. flava. Our results suggest that low gene flow in the I. ovatus populations has caused spatially heterogenous Rickettsia infection rates along the altitudinal gradient. This information can be used in understanding the relationship between the tick vector, its pathogen, and environmental factors, such as altitude, and for the control of tick-borne diseases in Japan.

ecology↗

bioRxiv2022

Genome-wide profiling of histone H3K4me3 and H3K27me3 modifications in individual blastocysts by CUT&Tag without a solid support (NON-TiE-UP CUT&Tag)

Individual analysis of the epigenome of preimplantation embryos is useful for characterizing each embryo and for investigating the effects of environmental factors on their epigenome. However, it is difficult to analyze genome-wide epigenetic modifications, especially histone modifications, in a large number of single embryos due to the small number of cells and the complexity of the analysis methods. To solve this problem, we further modified the CUT&Tag method, which can analyze histone modifications in a small number of cells, such that the embryo is handled as a cell mass in the reaction solutions in the absence of the solid-phase magnetic beads that are used for antibody and enzyme reactions in the original method (NON-TiE-UP CUT&Tag; NTU-CAT). By using bovine blastocysts as a model, we showed that genome-wide profiles of representative histone modifications, H3K4me3 and H3K27me3, could be obtained by NTU-CAT that are in overall agreement with the conventional chromatin immunoprecipitation-sequencing (ChIP-seq) method, even from single embryos. However, this new approach has limitations that require attention, including false positive peaks and lower resolution for broad modifications. Despite these limitations, we conclude that NTU-CAT is a promising replacement for ChIP-seq with the great advantage of being able to analyze individual embryos.

genomics↗

bioRxiv2021

Predicting behavior through dynamic modes in resting-state fMRI data

Dynamic properties of resting-state functional connectivity (FC) provide rich information on brainbehavior relationships. Dynamic mode decomposition (DMD) has been used as a method to characterize FC dynamics. However, it remains unclear whether dynamic modes (DMs), spatial-temporal coherent patterns computed by DMD, provide information about individual behavioral differences. This study established a methodological approach to predict individual differences in behavior using DMs. Furthermore, we investigated the contribution of DMs within each of seven specific frequency bands (0-0.1,...,0.6-0.7 Hz) for prediction. To validate our approach, we confirmed whether each of 59 behavioral measures could be predicted by performing multivariate pattern analysis on a gram matrix, which was created using subject-specific DMs computed from resting-state functional magnetic resonance imaging (rs-fMRI) data of individuals. The prediction was successful, and DMD outperformed temporal independent component analysis, a conventional data decomposition method for extracting spatial activity patterns. Most of the behavioral measures that showed significant prediction accuracies in a permutation test were cognitive-behavioral measures. Our results suggested that DMs within frequency bands <0.2 Hz primarily contributed to prediction. In addition, we found that DMs <0.2 Hz had spatial structures similar to several common resting-state networks. We demonstrated the effectiveness of DMs, indicating that DMD is a key approach for extracting spatiotemporal features from rs-fMRI data.

neuroscience↗

bioRxiv2020

The alopecia areata phenotype is induced by the water avoidance stress test in cchcr1-deficient mice.

BackgroundWe recently discovered a nonsynonymous variant in the coiled-coil alpha-helical rod protein 1 (CCHCR1) gene within the alopecia areata (AA) risk haplotype; mice engineered to carry the risk allele displayed a hair loss phenotype. ObjectiveTo further investigate the involvement of the CCHCR1 gene in AA pathogenesis. MethodsWe developed an AA model using C57BL/6N cchcr1 gene knockout mice. Mice (6-8 weeks) were divided into two groups: cchcr1 -/- mice and wild-type (WT) mice. Both groups were subjected to a water avoidance stress (WAS) test. ResultsEight weeks after the WAS test, 25% of cchcr1 mice exhibited noninflammatory foci of alopecia on the dorsal skin. The foci resembled human AA in terms of gross morphology, trichoscopic findings and histological findings. ConclusionsOur results strongly suggest that CCHCR1 is associated with AA pathogenesis and that cchcr1-/- mice are a good model for investigating AA. Author summaryAlopecia areata is thought to affect 1-2% of the population. In severe alopecia areata, changes in appearance significantly reduce the patients quality of life, but there is no established treatment. Its pathogenic mechanism is thought to cause an autoimmune disease of the hair bulb of growing hair. Many genes and factors associated with AA onset form a background that easily causes such an immune reaction, and the causative genes related to alopecia areata are being elucidated worldwide. We were able to identify the CCHCR1 gene as one of the causative genes by genome analysis. In this study, we created CCHCR1-deficient mice using Cre/loxP technology and confirmed that 25% of CCHCR1-deficient mice that underwent the WAS test for psychological stimulation developed hair loss similar to that observed in human alopecia areata. This suggests that the CCHCR1 gene is a disease susceptibility gene for alopecia areata.

genetics↗

bioRxiv2020

Comparative analysis of histone H3K4me3 modifications between early embryos and somatic tissues in cattle

Epigenetic changes induced in the early developmental stages by the surrounding environment can have not only short-term but also long-term consequences throughout life. This concept constitutes the "Developmental Origins of Health and Disease" (DOHaD) hypothesis and encompasses the possibility of controlling livestock health and diseases by epigenetic regulation during early development. As a preliminary step for examining changes of epigenetic modifications in early embryos and their long-lasting effects in fully differentiated somatic tissues, we aimed to obtain high-throughput genome-wide histone H3 lysine 4 trimethylation (H3K4me3) profiles of bovine early embryos and to compare these data with those from adult somatic tissues in order to extract common and typical features between these tissues in terms of H3K4me3 modifications. Bovine blastocysts were produced in vitro and subjected to chromatin immunoprecipitation-sequencing analysis of H3K4me3. Comparative analysis of the blastocyst-derived H3K4me3 profile with publicly available data from adult liver and muscle tissues revealed that the blastocyst profile could be used as a "sieve" to extract somatic tissue-specific modifications in genes closely related to tissue-specific functions. Furthermore, principal component analysis of the level of common modifications between blastocysts and somatic tissues in meat production-related and imprinted genes well characterized inter- and intra-tissue differences. The results of this study produced a referential genome-wide H3K4me3 profile of bovine early embryos and revealed its common and typical features in relation to the profiles of adult tissues. Supplementary informationSupplementary data are submitted along with the main manuscript. The ChIP-seq datasets for bovine blastocysts have been deposited in the Gene Expression Omnibus of NCBI with accession number GSE161221.

genomics↗

bioRxiv2019

Comparative population genetic structure of two Ixodidae ticks (Ixodes ovatus and Haemaphysalis flava) in Niigata Prefecture, Japan

Ixodid tick species such as Ixodes ovatus and Haemaphysalis flava are essential vectors of tick-borne diseases in Japan. In this study, we investigated the population genetic structures and gene flow of I. ovatus and H. flava as affected by the tick host mobility. We hypothesized that I. ovatus and H. flava may have differences in their genetic structure due to the low mobility of small rodent hosts of I. ovatus at the immature stage in contrast to the mediated dispersal of avian hosts for immature H. flava. We collected 307 adult I. ovatus and 220 adult H. flava from 29 and 17 locations across Niigata Prefecture, Japan. We investigated the genetic structure at two mitochondrial loci (cox1, 16S rRNA gene). For I. ovatus, pairwise FST and analysis of molecular variance (AMOVA) analyses of cox1 sequences indicated significant genetic variation among populations. Both cox1 and 16S rRNA markers showed non-significant genetic variation among locations for H. flava. The Bayesian tree and haplotype network of cox1 marker for I. ovatus samples in Niigata Prefecture found 3 genetic groups wherein most haplotypes in group 2 were distributed in low altitudinal areas. When we added cox1 sequences of I. ovatus from China to the phylogenetic analysis, three genetic groups (China 1, China 2, and Niigata and Hokkaido, Japan) were formed in the tree suggesting the potential for cryptic species in the genetic group in Japan. Our results support our hypothesis and suggest that the host preference of ticks at the immature stage may influence the genetic structure and gene flow of the ticks. This information is vital in understanding the tick-host interactions in the field to better understand the tick-borne disease transmission and in designing an effective tick control program.

genetics↗

bioRxiv2019

Prior physical synchrony enhances rapport and inter-brain synchronization during subsequent educational communication

Physical synchrony has been suggested to have positive effects on not only concurrent but also subsequent communication, but the underlying neural processes are unclear. Using functional near-infrared spectroscopy (fNIRS) hyperscanning, we tested the effects of preceding physical synchrony on subsequent dyadic teaching-learning communication. Thirty-two pairs of participants performed two experimental sessions. In each session, they underwent a rhythmic arm movement block with synchronous or asynchronous conditions, and then taught/learned unknown words to/from each other according to a given scenario. Neural activities in their medial and left lateral prefrontal cortex (PFC) were measured and inter-brain synchronization (IBS) during the teaching-learning blocks was evaluated. Participants rated their subjective rapport during the teaching-learning blocks, and took a word memory test. The analyses revealed that (1) prior physical synchrony enhanced teacher-learner rapport; (2) prior physical synchrony also enhanced IBS in the lateral PFC; and (3) IBS changes correlated positively with rapport changes. Physical synchrony did however not affect word memory performance. These results suggest that IBS can be useful to measure the effects of social-bonding facilitation activities for educational communication.

neuroscience↗

bioRxiv2018

FoxM1 drives proximal tubule proliferation during repair from acute kidney injury

The proximal tubule has a remarkable capacity for repair after acute injury but the cellular lineage and molecular mechanisms underlying this repair response have been poorly characterized. Here, we developed a Kim-1-GFPCreERt2 knockin mouse line (Kim-1-GCE), performed genetic lineage analysis after injury and measured the cellular transcriptome of proximal tubule during repair. Acutely injured genetically labeled clones co-expressed Kim-1, Vimentin, Sox9 and Ki67, indicating a dedifferentiated and proliferative state. Clonal analysis revealed clonal expansion of Kim-1+ cells, indicating that acutely injured, dedifferentiated proximal tubule cells account for repair rather than a fixed tubular progenitor. Translational profiling during injury and repair revealed signatures of both successful and unsuccessful maladaptive repair. The transcription factor FoxM1 was induced early in injury, was required for epithelial proliferation, and was dependent on epidermal growth factor receptor (EGFR) stimulation. In conclusion, dedifferentiated proximal tubule cells effect proximal tubule repair and we reveal a novel EGFR-FoxM1-dependent signaling pathway that drives proliferative repair after injury.

cell biology↗

bioRxiv2018

Alopecia areata susceptibility variant identified by MHC risk haplotype sequencing reproduces symptomatic patched hair loss in mice

BackgroundAlopecia areata (AA) is a highly heritable multifactorial and complex disease. However, no convincing susceptibility gene has yet been pinpointed in the major histocompatibility complex (MHC), a region in the human genome known to be associated with AA as compared to other regions.\n\nResultsBy sequencing MHC risk haplotypes, we identified a variant (rs142986308, p.Arg587Trp) in the coiled-coil alpha-helical rod protein 1 (CCHCR1) gene as the only non-synonymous variant in the AA risk haplotype. Using CRISPR/Cas9 for allele-specific genome editing, we then phenocopied AA symptomatic patched hair loss in mice engineered to carry the Cchcr1 risk allele. Skin biopsies of these alopecic mice showed strong up-regulation of hair-related genes, including hair keratin and keratin-associated proteins (KRTAPs). Using transcriptomics findings, we further identified CCHCR1 as a novel component of hair shafts and cuticles in areas where the engineered alopecic mice displayed fragile and impaired hair.\n\nConclusionsThese results suggest an alternative mechanism for the aetiology of AA based on aberrant keratinization, in addition to generally well-known autoimmune events.

genomics↗

bioRxiv2017

The Cross-Frequency Mediation Mechanism Of Intracortical Information Transactions

1. AbstractIn a seminal paper by von Stein and Sarnthein (2000), it was hypothesized that \"bottom-up\" information processing of \"content\" elicits local, high frequency (beta-gamma) oscillations, whereas \"top-down\" processing is \"contextual\", characterized by large scale integration spanning distant cortical regions, and implemented by slower frequency (theta-alpha) oscillations. This corresponds to a mechanism of cortical information transactions, where synchronization of beta-gamma oscillations between distant cortical regions is mediated by widespread theta-alpha oscillations. It is the aim of this paper to express this hypothesis quantitatively, in terms of a model that will allow testing this type of information transaction mechanism. The basic methodology used here corresponds to statistical mediation analysis, originally developed by (Baron and Kenny 1986). We generalize the classical mediator model to the case of multivariate complex-valued data, consisting of the discrete Fourier transform coefficients of signals of electric neuronal activity, at different frequencies, and at different cortical locations. The \"mediation effect\" is quantified here in a novel way, as the product of \"dual frequency RV-coupling coefficients\", that were introduced in (Pascual-Marqui et al 2016, http://arxiv.org/abs/1603.05343). Relevant statistical procedures are presented for testing the cross-frequency mediation mechanism in general, and in particular for testing the von Stein & Sarnthein hypothesis.

neuroscience↗