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Fujikawa, T.

Publications and source records attributed to Fujikawa, T..

11 recordsLinked to original sources
bioRxiv2026

Adrβ2 in skeletal muscle cells is required for exercise-induced Pgc1α but not for metabolic benefits of exercise on diet-induced obesity

{beta}2-Adrenergic receptor (Adr{beta}2) is the most abundant form of adrenergic receptors in skeletal muscle. Our previous studies have shown that the ventromedial hypothalamic nucleus (VMH) regulates metabolic benefits of exercise, potentially by skeletal muscle Adr{beta}2. Although a large body of literature has shown the importance of Adr{beta}2 on skeletal muscle physiology, it remains unexplored whether skeletal muscle Adr{beta}2 contributes to metabolic benefits of exercise, such as prevention of diet-induced obesity (DIO). Here, we generated mice lacking Adr{beta}2 in skeletal muscle cells (SKMAdr{beta}2) and tested whether SKMAdr{beta}2 is required for metabolic benefits of exercise on DIO. Deletion of SKMAdr{beta}2 completely abolished the induction of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1) in skeletal muscle by {beta}2-agonist, which is a potent activator of Pgc-1. Exercise upregulates Pgc-1, which regulates a broad range of skeletal muscle physiology, including hypertrophy and mitochondrial function. Deletion of SKMAdr{beta}2 hampers augmented Pgc-1 in skeletal muscle by a single bout of exercise. Intriguingly, we found that deletion of SKMAdr{beta}2 increased endurance capacity. Further, our data showed that body weight in DIO mice lacking SKMAdr{beta}2 is comparable to that of control DIO mice during exercise training, suggesting that deletion of SKMAdr{beta}2 did not affect the metabolic benefits of exercise in DIO. Collectively, our data indicate that SKMAdr{beta}2 contributes to exercise-induced transcriptional changes and endurance capacity, however, it is not required for exercise benefits on bodyweight in DIO mice.

physiology↗
bioRxiv2025

Bulk sample testing by real-time PCR for detecting Diaporthe destruens-infected seedlings of sweet potatoes

Foot rot disease of sweet potato is a fungal disease that causes serious damage to sweet potato production. It is especially important to check the health of seedlings as there is a risk that if the seed tubers or stem seedlings infected with foot rot pathogen are introduced into the production fields, it will rapidly spread throughout the fields. We have already developed a real-time PCR method to diagnose sweet potatoes contaminated with foot rot pathogen. In this study, to apply this method to the bulk sample testing, we provided examples on estimating the "probability of detection (POD)" for detecting bulk samples, and determining the number of subgroups and the number of samples in each subgroup for the bulk sample testing. Our results indicate that, for tubers, when testing between 100 and 1200 fragments per bulk sample, the lowest detection rate was approximately 81% at 800 fragments. For stems, when testing between 100 and 600 fragments, the lowest detection rate was approximately 83% at 500 fragments. Based on the estimated POD, the required sample size for bulk testing was calculated as follows: for the impermissible threshold proportion of contamination of infected plants (p) of 1%, between 390 and 624 samples are needed, while for p of 0.1%, between 3,840 and 6,228 samples are required. The bulk sample testing method using real-time PCR demonstrated in this study will become a powerful quality testing method for checking the health of sweet potato seedlings, and will make a significant contribution to sweet potato production.

plant biology↗
bioRxiv2025

Evaluation of real-time PCR performance for detecting Diaporthe destruens in sweet potatoes

Sweet potato foot rot disease caused by Diaporthe destruens is a major threat to sweet potato production. Rapid and accurate detection in advance is essential to secure healthy plants or to implement effective control. In this study, we evaluated the detection performance of a real-time PCR method previously developed by our research group. The evaluation was conducted using sweet potato samples collected in the field, including those naturally infected with D. destruens. Based on the real-time PCR results and the actual occurrence of the disease, a receiver operating characteristic (ROC) curve was generated, and the area under the curve (AUC) was calculated. The AUC values ranged from 0.7041571 to 0.9204286, confirming that this real-time PCR method is a well-balanced detection method for both tubers and stems. Furthermore, to minimize the occurrence of false negatives, the cycle threshold (Ct) cutoff was set at 35, and detection performance (sensitivity, specificity, accuracy, etc.) was analyzed. Then, by considering abnormal melting temperature (Tm) values as negative, high accuracy was achieved, with values of 0.871212 for tubers and 0.715447 for stems. This study not only evaluated the detection performance of the real-time PCR for foot rot pathogens but also contributes to providing information on the methodology and significance of performance evaluation in various real-time PCR genetic detection methods.

plant biology↗
bioRxiv2025

Development and Characterization of a Sf-1-Flp Mouse Model

The use of genetically engineered tools, including combinations of Cre-LoxP and Flp-FRT systems, enable the interrogation of complex biology. Steroidogenic factor-1 (SF-1) is expressed in the ventromedial hypothalamic nucleus (VMH). Development of genetic tools, such as mice expressing Flp recombinase (Flp) in SF-1 neurons (Sf-1-Flp), will be useful for future studies that unravel the complex physiology regulated by the VMH. Here, we developed and characterized Sf-1-Flp mice and demonstrated its utility. Flp sequence was inserted into Sf-1 locus with P2A. This insertion did not affect Sf-1 mRNA expression levels and Sf-1-Flp mice do not have any visible phenotypes. They are fertile and metabolically comparable to wild-type littermate mice. Optogenetic stimulation using adeno-associated virus (AAV)-bearing Flp-dependent channelrhodopsin-2 (ChR2) increased blood glucose and skeletal muscle PGC-1 in Sf-1-Flp mice. This was similar to SF-1 neuronal activation using Sf-1-BAC-Cre and AAV-bearing Cre-dependent ChR2. Finally, we generated Sf-1-Flp mice that lack {beta}2-adrenergic receptors (Adr{beta}2) only in skeletal muscle with a combination of Cre/LoxP technology (Sf-1-Flp::SKM{Delta}Adr{beta}2). Optogenetic stimulation of SF-1 neurons failed to increase skeletal muscle PGC-1 in Sf-1-Flp::SKM{Delta}Adr{beta}2 mice, suggesting that Adr{beta}2 in skeletal muscle is required for augmented skeletal muscle PGC-1 by SF-1 neuronal activation. Our data demonstrate that Sf-1-Flp mice are useful for interrogating complex physiology.

neuroscience↗
bioRxiv2024

Investigation of host plant contact with Diaphorina citri (Hemipreta: Psyllidae) by detecting D. citri-derived environmental DNA

Citrus greening (Huanglongbing) disease has serious impacts on citrus production. Field monitoring of the Asian citrus psyllid Diaphorina citri (Hemiptera: Psyllidae), a vector of citrus greening disease, is essential to prevent the invasion and spread of this disease. This study reported a new method for determining the presence of D. citri and traces of contact with host plants by collecting leaves of host plants from the survey area and detecting the environmental DNA (eDNA) derived from D. citri. The results showed that the method can determine the presence of D. citri. As D. citri-derived eDNA is contained in DNA solutions of plants with a history of contact with D. citri, we succeeded in detecting not only genes conserved in D. citri mitochondria but also genes of D. citri symbiont organisms consisting of Wolbachia, Wolbachia phage, Candidatus Carsonella sp., and Candidatus Profftella sp. Diaphorina citri-derived eDNA could be detected in host plants even after only 10 min of contact with D. citri and could still be detected 6 months after contact. This technology has the potential to trace D. citri from their traces without individual detection and is expected to greatly contribute to the early detection and invasion warning of citrus greening disease in the future.

molecular biology↗
bioRxiv2022

VMHdm/cSF-1 Neuronal Circuits Regulate Skeletal Muscle PGC1-α via the Sympathoadrenal Drive

ObjectiveTo adapt to metabolically challenging environments, the central nervous system (CNS) orchestrates metabolism of peripheral organs including skeletal muscle. The organ-communication between the CNS and skeletal muscle has been investigated, yet our understanding of the neuronal pathway from the CNS to skeletal muscle is still limited. Neurons in the dorsomedial and central parts of the ventromedial hypothalamic nucleus (VMHdm/c) expressing steroidogenic factor-1 (VMHdm/cSF-1 neurons) are key for metabolic adaptations to exercise, including increased basal metabolic rate and skeletal muscle mass in mice. However, the mechanisms by which VMHdm/cSF-1 neurons regulate skeletal muscle function remain unclear. Here, we show that VMHdm/cSF-1 neurons increase the sympathoadrenal activity and regulate skeletal muscle peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1) in mice via multiple downstream nodes. MethodsOptogenetics was used to specifically manipulate VMHdm/cSF-1 neurons combined with genetically-engineered mice and surgical manipulation of the sympathoadrenal activity. ResultsOptogenetic activation of VMHdm/cSF-1 neurons dramatically elevates mRNA levels of skeletal muscle Pgc-1, which regulates a spectrum of skeletal muscle function including protein synthesis and metabolism. Mechanistically, the sympathoadrenal drive coupled with {beta}2 adrenergic receptor ({beta}2AdR) is essential for VMHdm/cSF-1 neurons-mediated increases in skeletal muscle PGC1-. Specifically, both adrenalectomy and {beta}2AdR knockout block augmented skeletal muscle PGC1- by VMHdm/cSF-1 neuronal activation. Optogenetic functional mapping reveals that downstream nodes of VMHdm/cSF-1 neurons are functionally redundant to increase circulating epinephrine and skeletal muscle PGC1-. ConclusionsCollectively, we propose that VMHdm/cSF-1 neurons-skeletal muscle pathway, VMHdm/cSF-1 neurons[->]multiple downstream nodes[->]the adrenal gland[->]skeletal muscle {beta}2AdR, underlies augmented skeletal muscle function for metabolic adaptations.

neuroscience↗
bioRxiv2020

Draft Genome Sequences of 10 Strains of Pseudomonas syringae pv. actinidiae Biovar 1: A Major Kiwifruit Bacterial Canker Pathogen in Japan

Several groups (biovars) of the kiwifruit bacterial canker pathogen, Pseudomonas syringae pv. actinidiae, are found in Japan. Here, we sequenced and compared the 10 genomes of biovar 1, the major group in Japan, which is known as the phaseolotoxin producer. The kiwifruit bacterial canker pathogen, Pseudomonas syringae pv. actinidiae (Psa), was first described in Japan in 1989 (1). Subsequently, Psa was found in other kiwifruit-producing countries (2). Based on comparative analyses (2-4), Psa was categorized into several groups (biovars). The first Japanese group was named biovar 1 (Psa1), which was also later found in Italy and Korea. This biovar produces phaseolotoxin (2), a phytotoxin that inhibits arginine biosynthesis in host plants and results in bacterial canker symptom development. On the Psa1 chromosome, a large number of genes involved in phaseolotoxin biosynthesis are accumulated in an approximately 23 kb region (argK-tox cluster), which is contained in an exogenous genomic island (tox island) that Psa1 acquired in the past (2). However, some Psa1 strains found in Ehime Prefecture, Japan (the Ehime isolates) do not produce phaseolotoxin, although they seem to possess the argK-tox cluster (5). On the other hand, several Psa1 strains preserved in the NARO Genebank (https://www.gene.affrc.go.jp/index_en.php) may lack this cluster (2). Here, we selected 10 strains (Table 1) that represent Psa1 diversity and conducted comparative genome analyses. O_TBL View this table: org.highwire.dtl.DTLVardef@f2cdbdorg.highwire.dtl.DTLVardef@a16c33org.highwire.dtl.DTLVardef@1c68baborg.highwire.dtl.DTLVardef@1fbb077org.highwire.dtl.DTLVardef@fe901e_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 1.C_FLOATNO O_TABLECAPTIONGenome data and accession numbers of 10 strains of Pseudomonas syringae pv. actinidiae biovar 1. C_TABLECAPTION C_TBL

genomics↗
bioRxiv2020

Phytotoxin synthesis genes and type III effector genes of Pseudomonas syringae pv. actinidiae biovar 6 are regulated by culture conditions

The kiwifruit bacterial canker (Pseudomonas syringae pv. actinidiae; Psa) causes severe damage to kiwifruit production worldwide. Psa biovar 6 (Psa6), which was isolated in Japan in 2015, produces two types of phytotoxins: coronatine and phaseolotoxin. To date, no other phytopathogenic bacteria are known to produce two phytotoxins. To elucidate the unique virulence of Psa6, we performed transcriptomic analysis of phytotoxin synthesis genes and type III effector genes in in vitro cultivation using various media. The genes related to phytotoxin synthesis and effectors of Psa6 were strictly regulated in the coronatine-inducing mediums (HS and HSC); 14 of 23 effector genes and a hrpL sigma factor gene were induced at 3 h after transferring to the media (early-inducible genes), and phytotoxin synthesis genes such as argD of phaseolotoxin and cfl of coronatine were induced at 6 and 12 h after transferring to the media (late-inducible genes). In contrast, induction of these genes was not observed in the hrp-inducing medium. Next, to examine whether the changes in gene expression in different media is specific to Psa6, we investigated gene expression in other related bacteria. For Psa biovar 1 (Psa1), biovar 3 (Psa3), and P. s. pv. glycinea (Psg), no clear trends were observed in expression behavior across various culture media and incubation times. Therefore, Psa6 seems to exert its virulence efficiently by using two phytotoxins and effectors according to environmental changes. This is not seen in other biovars and pathovars, so it is thought that Psa6 has acquired its own balance of virulence.

microbiology↗
bioRxiv2020

Leptin Receptors in RIP-Cre25Mgn neurons Mediate Anti-Dyslipidemia Effects of Leptin in Insulin-Deficient Male Mice

Leptin is a potent endocrine hormone produced by adipose tissue and regulates a broad range of metabolism including glucose and lipid metabolism, with and without insulin. It is evident that central leptin signaling can lower hyperglycemia in insulin-deficient rodents via multiple mechanisms including restoration of dyslipidemia. However, the specific neurons that regulate these glucose-lowering and anti-dyslipidemia effects of leptin remain unidentified. Here we report that leptin receptors (LEPRs) in neurons expressing Cre recombinase driven by a short fragment of a promoter region of Ins2 gene (RIP-Cre25Mgn neurons) are required for central leptin signaling to reverse hyperglycemia and dyslipidemia in insulin-deficient mice. Ablation of LEPRs in RIP-Cre25Mgn neurons completely blocks glucose-lowering effects of leptin in insulin-deficient mice. Further investigations reveal that insulin-deficient mice lacking LEPRs in RIP-Cre25Mgn neurons (RIP-Cre{Delta}LEPR mice) exhibit greater lipid levels in blood and liver compared to wild-type controls, and that leptin injection into the brain does not suppress dyslipidemia in insulin-deficient RIP-Cre{Delta}LEPR mice. Leptin administration into the brain combined with acipimox, which lowers blood lipids by suppressing triglyceride lipase activity, can restore normal glycemia in insulin-deficient RIP-Cre{Delta}LEPR mice, suggesting that excess circulating lipids are a driving-force of hyperglycemia in insulin-deficient RIP-Cre{Delta}LEPR mice. Collectively, our data demonstrate that LEPRs in RIP-Cre25Mgn neurons significantly contribute to glucose-lowering effects of leptin in an insulin-independent manner by suppression of dyslipidemia.

neuroscience↗