Megumi Sumitani

Megumi Sumitani
National Agriculture and Food Research Organization (NARO) · Institute of Agrobiological Sciences

PhD

About

57
Publications
3,530
Reads
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568
Citations
Additional affiliations
October 2018 - November 2019
National Agriculture and Food Research Organization (NARO)
Position
  • Principal Investigator
April 2016 - present
National Agriculture and Food Research Organization
Position
  • Researcher
March 2013 - March 2016
National Institute of Agrobiological Sciences
Position
  • Researcher

Publications

Publications (57)
Article
We have identified a novel mitochondrial protein, termed M19, by proteomic analysis of mitochondrial membrane proteins from HeLa cells. M19 is highly conserved among vertebrates, and possesses no homologous domains with other known proteins. By northern and western blotting, mouse M19 was shown to be expressed in various tissues, and to be especial...
Article
We have previously developed a robust salivary gland-specific expression system in transgenic Anopheles stephensi mosquitoes. To establish transgenic mosquito lines refractory to Plasmodium falciparum using this system, we generated a transgenic mosquito harbouring the gene encoding an anti-P. falciparum circumsporozoite protein (PfCSP) single-chai...
Article
The induction of apoptosis in vivo is a useful tool for investigating the functions and importance of particular tissues. B-cell leukaemia/lymphoma 2-associated X protein (Bax) functions as a pro-apoptotic factor and induces apoptosis in several organisms. The Bax-mediated apoptotic system is widely conserved from Caenorhabditis elegans to humans....
Article
Transcription activator-like effector nucleases (TALENs) are efficient tools for targeted genome editing and have been utilized in a number of insects. Here, we demonstrate the gene disruption (knockout) caused by TALENs targeting a transgene, 3xP3-driven enhanced green fluorescence protein (EGFP), that is integrated in the genome of two species, t...
Article
The pupae of lepidopterans contain high concentrations of endogenous d-serine. In the silkworm Bombyx mori, d-serine is negligible during the larval stage but increases markedly during the pupal stage, reaching 50% of the total free serine. However, the physiological function of d-serine and the enzyme responsible for its production are unknown. He...
Article
Full-text available
The doublesex (dsx) gene, which encodes a transcription factor, regulates sexual differentiation in insects. Sex-specific splicing of dsx occurs to yield male- and female-specific isoforms, which promote male and female development, respectively. Thus, functional disruption of dsx leads to an intersexual phenotype in both sexes. We previously ident...
Article
Autoimmune orchitis is a condition related to cellular immunity. A disease model involving transfer of T lymphocytes activated by known antigens would be useful for defining pathogenical molecules. Since no method for activating rat T cells using specific antigens is available, we started the study to develop the method. T cells were collected from...
Article
Full-text available
Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promot...
Preprint
Full-text available
Background Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promotes...
Preprint
Full-text available
Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promote...
Preprint
Full-text available
Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promote...
Preprint
Full-text available
Background: Masculinizer (Masc) plays a pivotal role in male sex determination in the silkworm, Bombyx mori. Masc is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. The male isoform of Bmdsx (BmdsxM) induces male differentiation in somatic cells, while females express the female isoform of Bmdsx (BmdsxF), which promote...
Article
Full-text available
The tremendous diversity of Hymenoptera is commonly attributed to the evolution of parasitoidism in the last common ancestor of parasitoid sawflies (Orussidae) and wasp-waisted Hymenoptera (Apocrita). However, Apocrita and Orussidae differ dramatically in their species richness, indicating that the diversification of Apocrita was promoted by additi...
Article
Full-text available
Abstract Conditional cell death systems are useful for various aspects of basic science with a wide range of applications, including genetic pest control. We recently demonstrated that expression of the mammalian pro-apoptotic factor, B-cell leukaemia/lymphoma 2-associated X protein (Bax), can induce apoptosis in specific tissues by using tissue sp...
Article
Full-text available
Anopheline mosquitoes are major vectors of malaria parasites. When the gametocytes of the malaria parasite are transferred from a vertebrate to mosquitoes, they differentiate into gametes, and are fertilized in the midguts of mosquitoes. Xanthurenic acid (XA), a waste product of the ommochrome synthesis pathway, has been shown to induce exflagellat...
Article
We have been constructing a platform for the development of pharmaceutical and medical applications using the domesticated silkworm, Bombyx mori, as a new animal model for drug development and evaluation. Because silkworm larvae originally have the capacity to synthesize up to 0.5 g of silk proteins, genetically modified silkworms (transgenic silkw...
Article
In the present study, we initially cloned and characterized a mitochondrial transcription factor A (Tfam) homologue in the silkworm, Bombyx mori. Bombyx mori TFAM (BmTFAM) localized to mitochondria in cultured silkworm and human cells, and co-localized with mtDNA nucleoids in human HeLa cells. In an immunoprecipitation analysis, BmTFAM was found to...
Article
Full-text available
Malaria is an important global public health challenge, and is transmitted by anopheline mosquitoes during blood feeding. Mosquito vector control is one of the most effective methods to control malaria, and population replacement with genetically engineered mosquitoes to block its transmission is expected to become a new vector control strategy. Th...
Data
Analysis of salivary glands of female wild-type mosquitoes. (A) Salivary glands of blood-fed wild-type mosquitoes. Salivary glands dissected from unfed female wild-type mosquitoes (WT) and blood-fed female wild-type mosquitoes (post-blood feeding: PBF) (7-day-old mosquitoes) were shown. The salivary glands of blood-fed female mosquitoes were dissec...
Data
Analysis of salivary glands of AAPP-mBax line 3 females. (A) Abnormal salivary gland with aberrant distal-lateral lobes in a 7-day-old adult female. Scale bar = 100 ?m. (B) Detection of the mBax protein in the salivary glands of females by immunoblotting with anti-T7 and anti-alpha-tubulin antibodies. Homogenate samples of the salivary glands were...
Data
Measurements of probing times by wild-type and AAPP-mBax mosquitoes. Experiments were performed using separate generations of mosquitoes from the sample in Fig 4. Each dot corresponds to one female mosquito. The number and ratio of blood-fed mosquitoes within 420 seconds are indicated below (n = 46, ***: P < 0.0001, calculated by the Mann-Whitney U...
Data
Comparison of the P. berghei load in midguts of wild-type (WT) and AAPP-mBax (line 1) mosquitoes after blood feeding by a quantitative PCR analysis. Relative abundances are shown, with the average value of wild-type mosquitoes being 1. The abundance of the P. berghei 18S rRNA (Pb18S) gene was normalized using the abundance of An. stephensi GAPDH. T...
Data
Exflagellation-inducing activities of salivary glands of AAPP-mBax and wild-type mosquitoes. The homogenate of the salivary glands with PBS (pH 7.2) was mixed with P. berghei-infected blood. The homogenate of the salivary glands and blood from mice with other parasitemia differed from the sample in Fig 7. The number of exflagellation bodies per 4 f...
Data
Midguts of the AAPP-mBax mosquito. (A, B) Midguts of 7-day-old adult female wild-type and AAPP-mBax mosquitoes. (C, D) Midguts of 7-day-old adult female wild-type and AAPP-mBax mosquitoes were stained with trypan blue. (TIF)
Data
Comparison of the number of eggs laid between wild-type and AAPP-mBax mosquitoes. (PDF)
Data
Comparison of survival rates between AAPP-mBax (line 1) and wild-type mosquitoes. (A) Analysis under the sugar feeding only condition. The same number of mosquitoes (n = 30) immediately after eclosion was used in analyses. The survival curves of the groups were estimated by Kaplan-Meier methods. No significant difference was observed in females or...
Data
Relative expression levels of the aapp gene in 1-day-old adult female salivary glands in wild-type (WT) and AAPP-mBax (lines 1 and 3) mosquitoes by a quantitative RT-PCR analysis. Relative expression levels are shown and the value of wild-type mosquitoes was 1. The expression levels of aapp were normalized using the expression levels of GAPDH. (n =...
Data
The infection status of individual mice fed on by wild-type and AAPP-mBax mosquitoes. (PDF)
Article
Full-text available
In Bombyx mori (B. mori), Fem piRNA originates from the W chromosome and is responsible for femaleness. The Fem piRNA-PIWI complex targets and cleaves mRNAs transcribed from the Masc gene. Masc encodes a novel CCCH type zinc-finger protein and is required for male-specific splicing of B. mori doublesex (Bmdsx) transcripts. In the present study, sev...
Data
PCR-based genotyping of the Sumi13-3 females. (A) Schematic diagram of the primer locations used in the PCR-based genotyping. Red arrows indicate primers. (B) PCR products were separated by 1% agarose gel electrophoresis. The upper panel (TG-) indicates amplified products with Sumi13-3F and Sumi13-3R primers that specifically annealed to the region...
Data
Sequences of primers used for qRT-PCR. (DOCX)
Data
Expression of the DsRed and EGFP genes at the embryonic stage. R/+ (DsRed-positive); G/+ (EGFP-positive) animals possessed both BmA3-GAL4 and UAS-Masc-R transgenes. R/+ and G/+ animals carried either BmA3-GAL4 or UAS-Masc-R, respectively. +/+ animals had no transgenes. (TIF)
Data
Primer sequences and PCR conditions utilized in this study. (DOCX)
Data
Morphological abnormalities observed in the ovary of females with mutations of BmdsxF by somatic TALEN mutagenesis. Knockout silkworms were generated using transcription activator-like effector nuclease (TALENs), as described previously [60, 61]. mRNAs encoding a transcription activator-like effector nuclease (TALEN) that targeted Bmdsx were inject...
Data
Expression patterns of Bmdsx and expression level of Masc-R in Masc-R-expressing females. (A) Expression patterns of Bmdsx were analyzed by RT-PCR. Amplified products were separated by 1% agarose gel electrophoresis. The panel indicates the female- and male-specific splice variants of Bmdsx (BmdsxF1 and BmdsxM, respectively). cDNAs prepared from la...
Data
Expression patterns of Masc-R, Bmdsx, and ImpM were analyzed by RT-PCR. Amplified products were separated by 1% agarose gel electrophoresis. The top panel indicates the Masc-R expression. The second panel from the top indicates the female- and male-specific splice variants of Bmdsx (BmdsxF1, BmdsxF2, and BmdsxM, respectively). The third panel shows...
Data
Quantification of expression levels of Bmgn015522, Bmgn012518 and Bmgn012517 genes. qRT-PCR was performed to quantify mRNA levels of Bmgn015522, Bmgn012518, and Bmgn012517 genes at L1D1. EF2 was used as an internal standard. Error bar: SD. (TIF)
Article
Mosquitoes inject saliva into a vertebrate host during blood feeding. The analysis of mosquito saliva in host skin is important for the elucidation of the inflammatory responses to mosquito bites, the development of antithrombotic drugs, and the transmission-blocking of vector-borne diseases. We produced transgenic Anopheles stephensi mosquitoes ex...
Article
The segregation of mitochondrial DNA (mtDNA) is important for the maintenance and transmission of the genome between generations. Recently, we clarified that human mitochondrial transcription factor A (TFAM) is required for equal distribution and symmetric segregation of mtDNA in cultured cells; however, the molecular mechanism involved is largely...
Article
We produced a transgenic mosquito expressing a rodent malaria vaccine candidate antigen in the salivary gland. Three tandemly repeated amino acid units from the repeat region of circumsporozoite protein of Plasmodium berghei (PbCS3R) fused to red fluorescent protein (monomeric DsRed) was chosen as a vaccine candidate antigen. Immunoblot and fluores...
Article
Full-text available
Caenorhabditis elegans HMG-5, which is encoded by F45E4.9, contains two high mobility group (HMG) box domains and shows sequence similarity with mammalian mitochondrial transcription factor A (TFAM). In this study, using soaking RNA interference, we found that knockdown of HMG-5 reduced the amount of mtDNA in P0 hermaphrodites, suggesting it as fun...
Article
The segregation and transmission of the mitochondrial genome in humans are complicated processes but are particularly important for understanding the inheritance and clinical abnormalities of mitochondrial disorders. However, the molecular mechanism of the segregation of mitochondrial DNA (mtDNA) is largely unclear. In this study, we demonstrated t...
Article
Extensive survey of meiotic metaphase II arrest during oocyte maturation in vertebrates revealed that the mitogen-activated protein kinase (MAPK) pathway regulated by the c-mos proto-oncogene product, Mos, has an essential role in cytostatic activity, termed cytostatic factor (CSF). In contrast, little is known in invertebrates in which meiotic arr...
Article
Mitochondrial prohibitin (PHB) proteins have diverse functions, such as the regulation of apoptosis and the maintenance of mitochondrial morphology. In this study, we clarified a novel mitochondrial function of PHB1 that regulates the organization and maintenance of mitochondrial DNA (mtDNA). In PHB1-knockdown cells, we found that mtDNA is not stai...
Article
We isolated and characterized the white gene orthologue of the sawfly, Athalia rosae (Hymenoptera). The A. rosae white (Ar white) cDNA cloned was 2058-bp long encoding 685 amino acids in a single open reading frame (ORF). Comparison of the cDNA sequence with the genomic DNA sequence revealed that the ORF was derived from 11 exons. Ar white was a si...
Article
Germline transformation using a piggyBac-derived vector is feasible in the sawfly, Athalia rosae. A previously generated transgenic line carrying green fluorescence protein (GFP) genes as reporters was successfully maintained and preserved without consecutive rearing. Sperm taken from males that were frozen directly in liquid nitrogen and stored at...
Article
The cDNA of a decapentaplegic (dpp) orthologue from the sawfly, Athalia rosae (Hymenoptera), was cloned and characterized. The clone (Ar dpp) was 2,566 bp long and encoded 395 amino acids in a single open reading frame. Genomic Southern blotting showed that Ar dpp is a single copy gene. The deduced amino acid sequence can be aligned along its entir...
Article
A piggyBac construct carrying two green fluorescent protein (GFP)-coding sequences one driven by Bombyx mori actin gene promoter and the other by Drosophila melanogaster heat-shock protein 70 (hsp70) promoter were injected together with a nonautonomous helper plasmid containing an active piggyBac transposase gene into the posterior end of mature un...
Article
A mariner-like element was cloned from the genome of the Asiatic honey bee, Apis cerana japonica (Hymenoptera, Apocrita). The (composite) clone, named Acmar1, was 1,378 bp long, and encoded 336 amino acids corresponding to a transposase-like putative polypeptide in a single open reading frame. The D,D(34)D motif, the catalytic domain of the mariner...
Article
Mitotic metaphase chromosomes of Athalia rosae (Hymenoptera) haploid males were subjected to fluorescence in situ hybridization (FISH) analysis using an rDNA probe and two vitellogenin (Vg) cDNA probes (one representing the 5' half and the other the 3' half of the gene, each about 3 kb long, and together covering the entire coding region). The rDNA...
Article
A linkage map was constructed for the sawfly, Athalia rosae (Hymenoptera), based on the segregation of random amplified polymorphic DNA (RAPD) markers and a visible mutation, yellow fat body (yfb). Forty haploid male progeny (20 yfb and 20+) from a single diploid female parent (yfb/+) were examined. Sixty-one of the 180 arbitrary primers tested by...

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Project (1)
Project
We hypothesize from our several findings that sexual fate of germ line cells was determined independently of their genetic sex. Studies are now in progress to proof this hypothesis.