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Nurcan Özkan - One of the best experts on this subject based on the ideXlab platform.

Kenji Toyota - One of the best experts on this subject based on the ideXlab platform.

  • metabolomics reveals an involvement of pantothenate for male production responding to the short day stimulus in the water flea daphnia Pulex
    Scientific Reports, 2016
    Co-Authors: Kenji Toyota, Shinichi Miyagawa, Alex Gavin, Mark R Viant, Taisen Iguchi
    Abstract:

    Under favorable conditions, the micro-crustacean Daphnia Pulex produces female offspring by parthenogenesis, whereas under unfavorable conditions, they produce male offspring to induce sexual reproduction (environmental sex determination: ESD). We recently established a suitable system for ESD studies using D. Pulex WTN6 strain, in which the sex of the offspring can be regulated by alterations in day-length; long-day and short-day conditions can induce female and male offspring, respectively. Taking advantage of this system, we have already demonstrated that methyl farnesoate (MF) synthesis is necessary for male offspring production, and identified ionotropic glutamate receptors as an upstream regulator of MF signaling. Despite these findings, the molecular mechanisms associated with MF signaling have not yet been well elucidated. In this study, we analyzed the whole metabolic profiles of mother daphnids reared under long-day (female-producing) and short-day (male-producing) conditions, and discovered that pantothenate (vitamin B5), a known precursor to coenzyme A, was significantly accumulated in response to the short-day condition. To confirm the innate role of pantothenate in D. Pulex, this metabolite was administered to mother daphnids resulting in a significantly increased proportion of male offspring producing mothers. This study provides novel insights of the metabolic mechanisms of the ESD system in D. Pulex.

  • methyl farnesoate synthesis is necessary for the environmental sex determination in the water flea daphnia Pulex
    Journal of Insect Physiology, 2015
    Co-Authors: Kenji Toyota, Hitoshi Miyakawa, Chizue Hiruta, Kenjiro Furuta, Yukiko Ogino, Tetsuro Shinoda, Joseph R Shaw
    Abstract:

    Sex-determination systems can be divided into two groups: genotypic sex determination (GSD) and environmental sex determination (ESD). ESD is an adaptive life-history strategy that allows control of sex in response to environmental cues in order to optimize fitness. However, the molecular basis of ESD remains largely unknown. The micro crustacean Daphnia Pulex exhibits ESD in response to various external stimuli. Although methyl farnesoate (MF: putative juvenile hormone, JH, in daphnids) has been reported to induce male production in daphnids, the role of MF as a sex-determining factor remains elusive due to the lack of a suitable model system for its study. Here, we establish such a system for ESD studies in D. Pulex. The WTN6 strain switches from producing females to producing males in response to the shortened day condition, while the MFP strain only produces females, irrespective of day-length. To clarify whether MF has a novel physiological role as a sex-determining factor in D. Pulex, we demonstrate that a MF/JH biosynthesis inhibitor suppressed male production in WTN6 strain reared under the male-inducible condition, shortened day-length. Moreover, we show that juvenile hormone acid O-methyltransferase (JHAMT), a critical enzyme of MF/JH biosynthesis, displays MF-generating activity by catalyzing farnesoic acid. Expression of the JHAMT gene increased significantly just before the MF-sensitive period for male production in the WTN6 strain, but not in the MFP strain, when maintained under male-inducible conditions. These results suggest that MF synthesis regulated by JHAMT is necessary for male offspring production in D. Pulex. Our findings provide novel insights into the genetic underpinnings of ESD and they begin to shed light on the physiological function of MF as a male-fate determiner in D. Pulex.

  • nmda receptor activation upstream of methyl farnesoate signaling for short day induced male offspring production in the water flea daphnia Pulex
    BMC Genomics, 2015
    Co-Authors: Kenji Toyota, Hitoshi Miyakawa, Yukiko Ogino, Katsushi Yamaguchi, Shuji Shigenobu, Norihisa Tatarazako
    Abstract:

    Background The cladoceran crustacean Daphnia Pulex produces female offspring by parthenogenesis under favorable conditions, but in response to various unfavorable external stimuli, it produces male offspring (environmental sex determination: ESD). We recently established an innovative system for ESD studies using D. Pulex WTN6 strain, in which the sex of the offspring can be controlled simply by changes in the photoperiod: the long-day and short-day conditions can induce female and male offspring, respectively. Taking advantage of this system, we demonstrated that de novo methyl farnesoate (MF) synthesis is necessary for male offspring production. These results indicate the key role of innate MF signaling as a conductor between external environmental stimuli and the endogenous male developmental pathway. Despite these findings, the molecular mechanisms underlying up- and downstream signaling of MF have not yet been well elucidated in D. Pulex.

  • targeted gene disruption by use of transcription activator like effector nuclease talen in the water flea daphnia Pulex
    BMC Biotechnology, 2014
    Co-Authors: Chizue Hiruta, Kenji Toyota, Yukiko Ogino, Tetsushi Sakuma, Shinichi Miyagawa, Takashi Yamamoto, Taisen Iguchi
    Abstract:

    Background: The cosmopolitan microcrustacean Daphnia Pulex provides a model system for both human health research and monitoring ecosystem integrity. It is the first crustacean to have its complete genome sequenced, an unprecedented ca. 36% of which has no known homologs with any other species. Moreover, D. Pulex is ideally suited for experimental manipulation because of its short reproductive cycle, large numbers of offspring, synchronization of oocyte maturation, and other life history characteristics. However, existing gene manipulation techniques are insufficient to accurately define gene functions. Although our previous investigations developed an RNA interference (RNAi) system in D. Pulex, the possible time period of functional analysis was limited because the effectiveness of RNAi is transient. Thus, in this study, we developed a genome editing system for D. Pulex by first microinjecting transcription activator-like effector nuclease (TALEN) mRNAs into early embryos and then evaluating TALEN activity and mutation phenotypes. Results: We assembled a TALEN construct specific to the Distal-less gene (Dll), which is a homeobox transcription factor essential for distal limb development in invertebrates and vertebrates, and evaluated its activity in vitro by single-strand annealing assay. Then, we injected TALEN mRNAs into eggs within 1 hour post-ovulation. Injected embryos presented with defects in the second antenna and altered appendage development, and indel mutations were detected in Dll loci, indicating that this technique successfully knocked out the target gene. Conclusions: We succeeded, for the first time in D. Pulex, in targeted mutagenesis by use of Platinum TALENs. This genome editing technique makes it possible to conduct reverse genetic analysis in D. Pulex, making this species an even more appropriate model organism for environmental, evolutionary, and developmental genomics.

  • targeted gene disruption by use of transcription activator like effector nuclease talen in the water flea daphnia Pulex
    BMC Biotechnology, 2014
    Co-Authors: Chizue Hiruta, Kenji Toyota, Yukiko Ogino, Tetsushi Sakuma, Shinichi Miyagawa, Takashi Yamamoto, Taisen Iguchi
    Abstract:

    The cosmopolitan microcrustacean Daphnia Pulex provides a model system for both human health research and monitoring ecosystem integrity. It is the first crustacean to have its complete genome sequenced, an unprecedented ca. 36% of which has no known homologs with any other species. Moreover, D. Pulex is ideally suited for experimental manipulation because of its short reproductive cycle, large numbers of offspring, synchronization of oocyte maturation, and other life history characteristics. However, existing gene manipulation techniques are insufficient to accurately define gene functions. Although our previous investigations developed an RNA interference (RNAi) system in D. Pulex, the possible time period of functional analysis was limited because the effectiveness of RNAi is transient. Thus, in this study, we developed a genome editing system for D. Pulex by first microinjecting transcription activator-like effector nuclease (TALEN) mRNAs into early embryos and then evaluating TALEN activity and mutation phenotypes. We assembled a TALEN construct specific to the Distal-less gene (Dll), which is a homeobox transcription factor essential for distal limb development in invertebrates and vertebrates, and evaluated its activity in vitro by single-strand annealing assay. Then, we injected TALEN mRNAs into eggs within 1 hour post-ovulation. Injected embryos presented with defects in the second antenna and altered appendage development, and indel mutations were detected in Dll loci, indicating that this technique successfully knocked out the target gene. We succeeded, for the first time in D. Pulex, in targeted mutagenesis by use of Platinum TALENs. This genome editing technique makes it possible to conduct reverse genetic analysis in D. Pulex, making this species an even more appropriate model organism for environmental, evolutionary, and developmental genomics.

Murat Ozbek - One of the best experts on this subject based on the ideXlab platform.

Diane K Stoecker - One of the best experts on this subject based on the ideXlab platform.

  • highly divergent ssu rrna genes found in the marine ciliates myrionecta rubra and mesodinium Pulex
    Journal of Eukaryotic Microbiology, 2005
    Co-Authors: Matthew D Johnson, Torstein Tengs, David W Oldach, Charles F Delwiche, Diane K Stoecker
    Abstract:

    Myrionecta rubra and Mesodinium Pulex are among the most commonly encountered planktonic ciliates in coastal marine and estuarine regions throughout the world. Despite their widespread distribution, both ciliates have received little attention by taxonomists. In order to understand the phylogenetic position of these ciliates better, we determined the SSU rRNA gene from cultures of M. rubra and M. Pulex. Partial sequence data were also generated from isolated cells of M. rubra from Chesapeake Bay. The M. rubra and M. Pulex sequences were very divergent from all other ciliates, but shared a branch with 100% bootstrap support. Both species had numerous deletions and substitutions in their SSU rRNA gene, resulting in a long branch for the clade. This made the sequences prone to spurious phylogenetic affiliations when using simple phylogenetic methods. Maximum likelihood analysis placed M. rubra and M. Pulex on the basal ciliate branch, following the removal of ambiguously aligned regions. Fluorescent in situ hybridization probes were used with confocal laser scanning microscopy to confirm that these divergent sequences were both expressed in the cytoplasm and nucleolus of M. rubra and M. Pulex. We found that our sequence data matched several recently discovered unidentified eukaryotes in Genbank from diverse marine habitats, all of which had apparently been misattributed to highly divergent amoeboid organisms.

  • highly divergent ssu rrna genes found in the marine ciliates myrionecta rubra and mesodinium Pulex
    Protist, 2004
    Co-Authors: Matthew D Johnson, Torstein Tengs, David W Oldach, Charles F Delwiche, Diane K Stoecker
    Abstract:

    Summary Myrionecta rubra and Mesodinium Pulex are among the most commonly encountered planktonic ciliates in coastal marine and estuarine regions throughout the world. Despite their widespread distribution, both ciliates have received little attention by taxonomists. In order to better understand the phylogenetic position of these ciliates, we determined the SSU rRNA gene sequence from cultures of M.rubra and M. Pulex. Partial sequence data were also generated from isolated cells of M. rubra from Chesapeake Bay. The M. rubra and M. Pulex sequences were very divergent from all other ciliates, but shared a branch with 100% bootstrap support. Both species had numerous deletions and substitutions in their SSU rRNA gene, resulting in a long branch for the clade. This made the sequences prone to spurious phylogenetic affiliations when using simple phylogenetic methods. Maximum likelihood analysis placed M. rubra and M. Pulex on the basal ciliate branch, following removal of ambiguously aligned regions. Fluorescent in situ hybridization probes were used with confocal laser scanning microscopy to confirm that these divergent sequences were both expressed in the cytoplasm and nucleolus of M. rubra and M. Pulex. We found that our sequence data matched several recently discovered unidentified eukaryotes in Genbank from diverse marine habitats, all of which had apparently been misattributed to highly divergent amoeboid organisms.

Oteo Revuelta, José Antonio - One of the best experts on this subject based on the ideXlab platform.

  • La pulga humana Pulex irritans (Siphonaptera: Pulicidae) en el noroeste argentino, una investigación de Bartonella y Rickettsia spp.
    2020
    Co-Authors: Lareschi Marcela, Venzal, José M., Nava Santiago, Mangold, Atilio José, Portillo Aránzazu, Palomar Urbina, Ana María, Oteo Revuelta, José Antonio
    Abstract:

    Pulex irritans is the only cosmopolitan flea species and the most studied one within the genus Pulex. It has importance in public health since it commonly parasitizes humans causing dermatitis, and it has been also implicated in the transmission of bacterial pathogens. Pulex irritans has been confused with the closely related Pulex simulans species for years. Herein, Pulex specimens collected from a Pampas fox and a Chacoan peccary from northwestern Argentina were identified by comparison with type specimens. In addition, the presence of Bartonella spp. and Rickettsia spp. was investigated using PCR assays. Our results provided characters of diagnostic importance to identify P. irritans, which include the shape of sternite VII in the females, and of the aedeagal sclerite, clasper and crochet in the males. Besides, we report for the first time P. irritans parasitizing a peccary. This finding reinforces the hypothesis of the origin of this flea associated with this mammal, and then colonizing humans and domestic mammals. There was no evidence of Bartonella or Rickettsia DNA in the analyzed fleas. This information even if negative may be considered relevant for P. irritans from Argentina.Pulex irritans es la única especie cosmopolita y la más estudiada dentro del género Pulex. Tiene importancia en la salud pública ya que comúnmente parasita a los seres humanos causando dermatitis y también ha sido implicada en la transmisión de patógenos bacterianos. Pulex irritans se ha confundido con la especie cercana Pulex simulans durante años. En este sentido, se identificaron los especímenes de Pulex recolectados de un zorro pampeano y un pecarí del Chaco del noroeste de la Argentina por comparación con los ejemplares tipo. Además, se investigó la presencia de Bartonella spp. y Rickettsia spp. utilizando ensayos de PCR. Nuestros resultados aportaron caracteres de importancia diagnóstica para identificar a P. irritans, que incluyen la forma del esternito VII en las hembras y del esclerito aedeagal, clasper y crochet en los machos. Además, se reporta por primera vez a P. irritans parasitando un pecarí. Este hallazgo refuerza la hipótesis del origen de esta pulga asociada con este mamífero y luego coloniza humanos y mamíferos domésticos. No hubo evidencia de ADN de Bartonella ni de Rickettsia en las pulgas analizadas. Esta información, si bien negativa, puede ser considerada relevante para P. irritans de Argentina.Centro de Estudios Parasitológicos y de Vectore

  • La pulga humana Pulex irritans (Siphonaptera: Pulicidae) en el noroeste argentino, una investigación de Bartonella y Rickettsia spp.
    'Universidad Nacional Autonoma de Mexico', 2018
    Co-Authors: Lareschi Marcela, Venzal, José M., Nava Santiago, Mangold, Atilio José, Portillo Aránzazu, Palomar Urbina, Ana María, Oteo Revuelta, José Antonio
    Abstract:

    Pulex irritans is the only cosmopolitan flea species and the most studied one within the genus Pulex. It has importance in public health since it commonly parasitizes humans causing dermatitis, and it has been also implicated in the transmission of bacterial pathogens. Pulex irritans has been confused with the closely related Pulex simulans species for years. Herein, Pulex specimens collected from a Pampas fox and a Chacoan peccary from northwestern Argentina were identified by comparison with type specimens. In addition, the presence of Bartonella spp. and Rickettsia spp. was investigated using PCR assays. Our results provided characters of diagnostic importance to identify P. irritans, which include the shape of sternite VII in the females, and of the aedeagal sclerite, clasper and crochet in the males. Besides, we report for the first time P. irritans parasitizing a peccary. This finding reinforces the hypothesis of the origin of this flea associated with this mammal, and then colonizing humans and domestic mammals. There was no evidence of Bartonella or Rickettsia DNA in the analyzed fleas. This information even if negative may be considered relevant for P. irritans from Argentina.Fil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Venzal, José M.. Universidad de la República; UruguayFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Portillo, Aránzazu. Universidad de la República; UruguayFil: Palomar Urbina, Ana María. Centro de Investigación Biomédica de La Rioja; EspañaFil: Oteo Revuelta, José Antonio. Centro de Investigación Biomédica de La Rioja; Españ

  • La pulga humana Pulex irritans (Siphonaptera: Pulicidae) en el noroeste argentino, una investigación de Bartonella y Rickettsia spp.
    'Universidad Nacional Autonoma de Mexico', 2018
    Co-Authors: Lareschi Marcela, Venzal, José M., Nava Santiago, Mangold, Atilio José, Portillo Aránzazu, Palomar Urbina, Ana María, Oteo Revuelta, José Antonio
    Abstract:

    Pulex irritans es la única especie cosmopolita y la más estudiada dentro del género Pulex. Tiene importancia en la salud pública ya que comúnmente parasita a los seres humanos causando dermatitis y también ha sido implicada en la transmisión de patógenos bacterianos. Pulex irritans se ha confundido con la especie cercana Pulex simulans durante años. En este sentido, se identificaron los especímenes de Pulex recolectados de un zorro pampeano y un pecarí del Chaco del noroeste de la Argentina por comparación con los ejemplares tipo. Además, se investigó la presencia de Bartonella spp. y Rickettsia spp. utilizando ensayos de PCR. Nuestros resultados aportaron caracteres de importancia diagnóstica para identificar a P. irritans, que incluyen la forma del esternito VII en las hembras y del esclerito aedeagal, clasper y crochet en los machos. Además, se reporta por primera vez a P. irritans parasitando un pecarí. Este hallazgo refuerza la hipótesis del origen de esta pulga asociada con este mamífero y luego coloniza humanos y mamíferos domésticos. No hubo evidencia de ADN de Bartonella ni de Rickettsia en las pulgas analizadas. Esta información, si bien negativa, puede ser considerada relevante para P. irritans de Argentina.Pulex irritans is the only cosmopolitan flea species and the most studied one within the genus Pulex. It has importance in public health since it commonly parasitizes humans causing dermatitis, and it has been also implicated in the transmission of bacterial pathogens. Pulex irritans has been confused with the closely related Pulex simulans species for years. Herein, Pulex specimens collected from a Pampas fox and a Chacoan peccary from northwestern Argentina were identified by comparison with type specimens. In addition, the presence of Bartonella spp. and Rickettsia spp. was investigated using PCR assays. Our results provided characters of diagnostic importance to identify P. irritans, which include the shape of sternite VII in the females, and of the aedeagal sclerite, clasper and crochet in the males. Besides, we report for the first time P. irritans parasitizing a peccary. This finding reinforces the hypothesis of the origin of this flea associated with this mammal, and then colonizing humans and domestic mammals. There was no evidence of Bartonella or Rickettsia DNA in the analyzed fleas. This information even if negative may be considered relevant for P. irritans from Argentina.Fil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Venzal, José M.. Universidad de la República; UruguayFil: Nava, Santiago. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mangold, Atilio Jose. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Portillo, Aránzazu. Universidad de la República; UruguayFil: Palomar Urbina, Ana María. Centro de Investigación Biomédica de La Rioja; EspañaFil: Oteo Revuelta, José Antonio. Centro de Investigación Biomédica de La Rioja; Españ

  • The human flea Pulex irritans (Siphonaptera: Pulicidae) in northwestern Argentina, with an investigation of Bartonella and Rickettsia spp. = La pulga humana Pulex irritans (Siphonaptera: Pulicidae) en el noroeste argentino, una investigación de Barto
    'Universidad Nacional Autonoma de Mexico', 2018
    Co-Authors: Lareschi Marcela, Nava Santiago, Mangold, Atilio José, Portillo Aránzazu, Palomar Urbina, Ana María, Venzal, José Manuel, Oteo Revuelta, José Antonio
    Abstract:

    Pulex irritans is the only cosmopolitan flea species and the most studied one within the genus Pulex. It has importance in public health since it commonly parasitizes humans causing dermatitis, and it has been also implicated in the transmission of bacterial pathogens. Pulex irritans has been confused with the closely related Pulex simulans species for years. Herein, Pulex specimens collected from a Pampas fox and a Chacoan peccary from northwestern Argentina were identified by comparison with type specimens. In addition, the presence of Bartonella spp. and Rickettsia spp. was investigated using PCR assays. Our results provided characters of diagnostic importance to identify P. irritans, which include the shape of sternite VII in the females, and of the aedeagal sclerite, clasper and crochet in the males. Besides, we report for the first time P. irritans parasitizing a peccary. This finding reinforces the hypothesis of the origin of this flea associated with this mammal, and then colonizing humans and domestic mammals. There was no evidence of Bartonella or Rickettsia DNA in the analyzed fleas. This information even if negative may be considered relevant for P. irritans from Argentina.Pulex irritans es la única especie cosmopolita y la más estudiada dentro del género Pulex. Tiene importancia en la salud pública ya que comúnmente parasita a los seres humanos causando dermatitis y también ha sido implicada en la transmisión de patógenos bacterianos. Pulex irritans se ha confundido con la especie cercana Pulex simulans durante años. En este sentido, se identificaron los especímenes de Pulex recolectados de un zorro pampeano y un pecarí del Chaco del noroeste de la Argentina por comparación con los ejemplares tipo. Además, se investigó la presencia de Bartonella spp. y Rickettsia spp. utilizando ensayos de PCR. Nuestros resultados aportaron caracteres de importancia diagnóstica para identificar a P. irritans, que incluyen la forma del esternito VII en las hembras y del esclerito aedeagal, clasper y crochet en los machos. Además, se reporta por primera vez a P. irritans parasitando un pecarí. Este hallazgo refuerza la hipótesis del origen de esta pulga asociada con este mamífero y luego coloniza humanos y mamíferos domésticos. No hubo evidencia de ADN de Bartonella ni de Rickettsia en las pulgas analizadas. Esta información, si bien negativa, puede ser considerada relevante para P. irritans de ArgentinaEEA RafaelaFil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Estudios Parasitológicos y de Vectores; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Venzal, José Manuel. Universidad de la República. CENUR Litoral Norte-Salto. Facultad de Veterinaria. Laboratorio de Vectores y Enfermedades Transmitidas; UruguayFil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina.Fil: Mangold, Atilio Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Portillo, Aránzazu. Hospital San Pedro- Centro de Investigación Biomédica de La Rioja. Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores; EspañaFil: Palomar-Urbina, Ana María. Hospital San Pedro- Centro de Investigación Biomédica de La Rioja. Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores; EspañaFil: Oteo-Revuelta, José Antonio. Hospital San Pedro- Centro de Investigación Biomédica de La Rioja. Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores; Españ

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