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Monique Gillis - One of the best experts on this subject based on the ideXlab platform.
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a new species of devosia that forms a unique nitrogen fixing root nodule symbiosis with the aquatic legume Neptunia natans l f druce
Applied and Environmental Microbiology, 2002Co-Authors: Raul Rivas, Encarna Velázquez, Monique Gillis, Nieves Vizcaino, Nanjappa S Subbarao, Pedro F Mateos, Frank B Dazzo, Eustoquio MartinezmolinaAbstract:Rhizobia are the common bacterial symbionts that form nitrogen-fixing root nodules in legumes. However, recently other bacteria have been shown to nodulate and fix nitrogen symbiotically with these plants. Neptunia natans is an aquatic legume indigenous to tropical and subtropical regions and in African soils is nodulated by Allorhizobium undicola. This legume develops an unusual root-nodule symbiosis on floating stems in aquatic environments through a unique infection process. Here, we analyzed the low-molecular-weight RNA and 16S ribosomal DNA (rDNA) sequence of the same fast-growing isolates from India that were previously used to define the developmental morphology of the unique infection process in this symbiosis with N. natans and found that they are phylogenetically located in the genus Devosia, not Allorhizobium or Rhizobium. The 16S rDNA sequences of these two Neptunia-nodulating Devosia strains differ from the only species currently described in that genus, Devosia riboflavina. From the same isolated colonies, we also located their nodD and nifH genes involved in nodulation and nitrogen fixation on a plasmid of approximately 170 kb. Sequence analysis showed that their nodD and nifH genes are most closely related to nodD and nifH of Rhizobium tropici, suggesting that this newly described Neptunia-nodulating Devosia species may have acquired these symbiotic genes by horizontal transfer.
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allorhizobium undicola gen nov sp nov nitrogen fixing bacteria that efficiently nodulate Neptunia natans in senegal
International Journal of Systematic and Evolutionary Microbiology, 1998Co-Authors: Philippe De Lajudie, Etike Laurentfulele, Urbain Torek, Renata Coopman, Matthew D Collins, Karel Kersters, Bernard Dreyfus, Monique GillisAbstract:A group of nodule isolates from Neptunia natans, an indigenous stemnodulated tropical legume found in waterlogged areas of Senegal, was studied. Polyphasic taxonomy was performed, including SDS-PAGE of total proteins, auxanography using API galleries, host-plant specificity, PCR-RFLP of the internal transcribed spacer region between the 16S and the 23S rRNA coding genes, 16S rRNA gene sequencing and DNA-DNA hybridization. It was demonstrated that this group is phenotypically and phylogenetically separate from the known species of Rhizobium, Sinorhizobium, Mesorhizobium, Agrobacterium, Bradyrhizobium and Azorhizobium. Its closest phylogenetic neighbour, as deduced by 16S rRNA gene sequencing, is Agrobacterium vitis (96·2% sequence homology). The name Allorhizobium undicola gen. nov., sp. nov., is proposed for this group of bacteria, which are capable of efficient nitrogen-fixing symbiosis with Neptunia natans, and the type strain is ORS 992T(= LMG 11875T).
Philippe De Lajudie - One of the best experts on this subject based on the ideXlab platform.
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allorhizobium undicola gen nov sp nov nitrogen fixing bacteria that efficiently nodulate Neptunia natans in senegal
International Journal of Systematic and Evolutionary Microbiology, 1998Co-Authors: Philippe De Lajudie, Etike Laurentfulele, Urbain Torek, Renata Coopman, Matthew D Collins, Karel Kersters, Bernard Dreyfus, Monique GillisAbstract:A group of nodule isolates from Neptunia natans, an indigenous stemnodulated tropical legume found in waterlogged areas of Senegal, was studied. Polyphasic taxonomy was performed, including SDS-PAGE of total proteins, auxanography using API galleries, host-plant specificity, PCR-RFLP of the internal transcribed spacer region between the 16S and the 23S rRNA coding genes, 16S rRNA gene sequencing and DNA-DNA hybridization. It was demonstrated that this group is phenotypically and phylogenetically separate from the known species of Rhizobium, Sinorhizobium, Mesorhizobium, Agrobacterium, Bradyrhizobium and Azorhizobium. Its closest phylogenetic neighbour, as deduced by 16S rRNA gene sequencing, is Agrobacterium vitis (96·2% sequence homology). The name Allorhizobium undicola gen. nov., sp. nov., is proposed for this group of bacteria, which are capable of efficient nitrogen-fixing symbiosis with Neptunia natans, and the type strain is ORS 992T(= LMG 11875T).
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Allorhizobium undicola gen. nov., sp. nov., nitrogen-fixing bacteria that efficiently nodulate Neptunia natans in Senegal
1998Co-Authors: Philippe De Lajudie, Laurent-fulele E., Willems A., Torck U., Coopman R., Kersters K., Dreyfus Bernard, Gillis M.Abstract:A group of nodule isolates form #Neptunia natans$, an indigenous stem-nodulated tropical legume found in waterlogged areas of Senegal, was studied. Polyphasic taxonomy was performed, including SDS-PAGE of total proteins, auxanography using API galleries, host-plant specificity, PCR-RFLP of the internal transcribed spacer region between the 16S and the 23S rRNA coding genes, 16S rRNA gene sequencing and DNA-DNA hybridization. It was demonstrated that this group is phenotypically and phylogenetically separate from the known species of #Rhizobium$, Sinorhizobium$, #Mesorhizobium$, #Agrobacterium$, #Bradyrhizobium$, and #Azorhizobium$. Its closest phylogenetic neighbour, as deduced by 16S rRNA gene sequencing, is #Agrobacterium vitis$ (96.2% sequence homology). The name #Allorhizobium undicola$ gen. nov., sp. nov., is proposed for this group of bacteria, which are capable of efficient nitrogen-fixing symbiosis with #Neptunia natans$, and the type strain is ORS 9925T) (= LMG 11875(T)). (Résumé d'auteur
T Mukai - One of the best experts on this subject based on the ideXlab platform.
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origin and dynamical evolution of neptune trojans i formation and planetary migration
Monthly Notices of the Royal Astronomical Society, 2009Co-Authors: Jonti Horner, Barrie W Jones, T MukaiAbstract:We present the results of detailed dynamical simulations of the effect of the migration of the four giant planets on both the transport of pre-formed Neptune Trojans and the capture of new Trojans from a trans-Neptunian disc. The cloud of pre-formed Trojans consisted of thousands of massless particles placed on dynamically cold orbits around Neptune's L4 and L5 Lagrange points, while the trans-Neptunian disc contained tens of thousands of such particles spread on dynamically cold orbits between the initial and final locations of Neptune. Through the comparison of the results with the previous work on the known Neptunian Trojans, we find that scenarios involving the slow migration of Neptune over a large distance (50 Myr to migrate from 18.1 au to its current location, using an exponential-folding time of τ = 10 Myr) provide the best match to the properties of the known Trojans. Scenarios with faster migration (5 Myr, with τ = 1 Myr), and those in which Neptune migrates from 23.1 au to its current location, fail to adequately reproduce the current-day Trojan population. Scenarios which avoid disruptive perturbation events between Uranus and Neptune fail to yield any significant excitation of pre-formed Trojans (transported with efficiencies between 30 and 98 per cent whilst maintaining the dynamically cold nature of these objects - e < 0.1, i < 5°). Conversely, scenarios with periods of strong Uranus-Neptune perturbation lead to the almost complete loss of such pre-formed objects. In these cases, a small fraction (∼0.15 per cent) of these escaped objects are later recaptured as Trojans prior to the end of migration, with a wide range of eccentricities (<0.35) and inclinations (<40°). In all scenarios (including those with such disruptive interaction between Uranus and Neptune), the capture of objects from the trans-Neptunian disc (through which Neptune migrates) is achieved with efficiencies between ∼0.1 and ∼1 per cent. The captured Trojans display a wide range of inclinations (<40° for slow migration, and <20° for rapid migration) and eccentricities (<0.35), and we conclude that, given the vast amount of material which undoubtedly formed beyond the orbit of Neptune, such captured objects may be sufficient to explain the entire Neptune Trojan population.
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an outer planet beyond pluto and the origin of the trans Neptunian belt architecture
The Astronomical Journal, 2008Co-Authors: Patryk Sofia Lykawka, T MukaiAbstract:Trans-Neptunian objects (TNOs) are remnants of a collisionally and dynamically evolved planetesimal disk in the outer solar system. This complex structure, known as the trans-Neptunian belt (or Edgeworth-Kuiper belt), can reveal important clues about disk properties, planet formation, and other evolutionary processes. In contrast to the predictions of accretion theory, TNOs exhibit surprisingly large eccentricities, e, and inclinations, i, which can be grouped into distinct dynamical classes. Several models have addressed the origin and orbital evolution of TNOs, but none has reproduced detailed observations, e.g., all dynamical classes and peculiar objects, or provided insightful predictions. Based on extensive simulations of planetesimal disks with the presence of the four giant planets and massive planetesimals, we propose that the orbital history of an outer planet with tenths of the Earth's mass can explain the trans-Neptunian belt orbital structure. This massive body was likely scattered by one of the giant planets, which then stirred the primordial planetesimal disk to the levels observed at 40-50 AU and truncated it at about 48 AU before planet migration. The outer planet later acquired an inclined stable orbit (≥100 AU; 20-40°) because of a resonant interaction with Neptune (an r:1 or r:2 resonance possibly coupled with the Kozai mechanism), guaranteeing the stability of the trans-Neptunian belt. Our model consistently reproduces the main features of each dynamical class with unprecedented detail; it also satisfies other constraints such as the current small total mass of the trans-Neptunian belt and Neptune's current orbit at 30.1 AU. We also provide observationally testable predictions.
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an outer planet beyond pluto and origin of the trans Neptunian belt architecture
arXiv: Astrophysics, 2007Co-Authors: Patryk Sofia Lykawka, T MukaiAbstract:Trans-Neptunian objects (TNOs) are remnants of a collisionally and dynamically evolved planetesimal disk in the outer solar system. This complex structure, known as the trans-Neptunian belt (or Edgeworth-Kuiper belt), can reveal important clues about disk properties, planet formation, and other evolutionary processes. In contrast to the predictions of accretion theory, TNOs exhibit surprisingly large eccentricities, e, and inclinations, i, which can be grouped into distinct dynamical classes. Several models have addressed the origin and orbital evolution of TNOs, but none have reproduced detailed observations, e.g., all dynamical classes and peculiar objects, or provided insightful predictions. Based on extensive simulations of planetesimal disks with the presence of the four giant planets and massive planetesimals, we propose that the orbital history of an outer planet with tenths of Earth's mass can explain the trans-Neptunian belt orbital structure. This massive body was likely scattered by one of the giant planets, which then stirred the primordial planetesimal disk to the levels observed at 40-50 AU and truncated it at about 48 AU before planet migration. The outer planet later acquired an inclined stable orbit (>100 AU; 20-40 deg) because of a resonant interaction with Neptune (an r:1 or r:2 resonance possibly coupled with the Kozai mechanism), guaranteeing the stability of the trans-Neptunian belt. Our model consistently reproduces the main features of each dynamical class with unprecedented detail; it also satisfies other constraints such as the current small total mass of the trans-Neptunian belt and Neptune's current orbit at 30.1 AU. We also provide observationally testable predictions.
Jacinto Vílchez, Cinthia Gregoria Jennifer - One of the best experts on this subject based on the ideXlab platform.
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Evaluación Del Control Interno Del Área Operativa De Asistencia Técnica En La Empresa Neptunia S.A – Paita 2017
'Universidad Cesar Vallejo', 2017Co-Authors: Jacinto Vílchez, Cinthia Gregoria JenniferAbstract:La presente investigación denominada: Evaluación del control interno del área operativa de asistencia técnica en la empresa Neptunia s.a – Paita 2017, presenta como objetivo Evaluar la situación actual del Control Interno del área operativa de asistencia técnica de la empresa Neptunia s.a Paita. Para esta investigación se aplicó como instrumento una encuesta, todo referente a los indicadores establecidos en la operacionalización de variables. El tipo de investigación es, descriptivo no correlacional, de nivel cuantitativo, diseño no experimental, la población está conformada por las 80 personas que forman parte de la empresa Neptunia s.a, la muestra es no probabilística intencionado y está conformada por 20 personal del área operativa de asistencia técnica de la empresa. Dentro de las conclusiones tenemos que el 54.5% de los encuestados dieron una respuesta positiva acerca del Control Interno en el área operativa de asistencia técnica, lo que significa que la situación actual va por un buen camino, pero un porcentaje del 44.5%, es indicativo de que se debe seguir mejorando la gestión para obtener mejores resultados en la operatividad del área de asistencia técnica de la empresa Neptunia s.a
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Evaluación Del Control Interno Del Área Operativa De Asistencia Técnica En La Empresa Neptunia S.A – Paita 2017
'Universidad Cesar Vallejo', 2017Co-Authors: Jacinto Vílchez, Cinthia Gregoria JenniferAbstract:TesisPiuraEscuela Académico Profesional de ContabilidadAuditoríaLa presente investigación denominada: Evaluación del control interno del área operativa de asistencia técnica en la empresa Neptunia s.a – Paita 2017, presenta como objetivo Evaluar la situación actual del Control Interno del área operativa de asistencia técnica de la empresa Neptunia s.a Paita. Para esta investigación se aplicó como instrumento una encuesta, todo referente a los indicadores establecidos en la operacionalización de variables. El tipo de investigación es, descriptivo no correlacional, de nivel cuantitativo, diseño no experimental, la población está conformada por las 80 personas que forman parte de la empresa Neptunia s.a, la muestra es no probabilística intencionado y está conformada por 20 personal del área operativa de asistencia técnica de la empresa. Dentro de las conclusiones tenemos que el 54.5% de los encuestados dieron una respuesta positiva acerca del Control Interno en el área operativa de asistencia técnica, lo que significa que la situación actual va por un buen camino, pero un porcentaje del 44.5%, es indicativo de que se debe seguir mejorando la gestión para obtener mejores resultados en la operatividad del área de asistencia técnica de la empresa Neptunia s.a
Juliette C Becker - One of the best experts on this subject based on the ideXlab platform.
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reprint of evidence for color dichotomy in the primordial Neptunian trojan population
Icarus, 2019Co-Authors: Hsing Wen Lin, D W Gerdes, S Hamilton, Fred C Adams, G M Bernstein, M Sako, Pedro Bernadinelli, D L Tucker, Sahar S Allam, Juliette C BeckerAbstract:Abstract In the current model of early Solar System evolution, the stable members of the Jovian and Neptunian Trojan populations were captured into resonance from the leftover reservoir of planetesimals during the outward migration of the giant planets. As a result, both Jovian and Neptunian Trojans share a common origin with the primordial disk population, whose other surviving members constitute today’s trans-Neptunian object (TNO) populations. The cold (low inclination and small eccentricity) classical TNOs are ultra-red, while the dynamically excited “hot” (high inclination and larger eccentricity) population of TNOs contains a mixture of ultra-red and blue objects. In contrast, Jovian and Neptunian Trojans are observed to be blue. While the absence of ultra-red Jovian Trojans can be readily explained by the sublimation of volatile material from their surfaces due to the high flux of solar radiation at 5 AU, the lack of ultra-red Neptunian Trojans presents both a puzzle and a challenge to formation models. In this work we report the discovery by the Dark Energy Survey (DES) of two new dynamically stable L4 Neptunian Trojans, 2013 VX30 and 2014 UU240, both with inclinations i > 30°, making them the highest-inclination known stable Neptunian Trojans. We have measured the colors of these and three other dynamically stable Neptunian Trojans previously observed by DES, and find that 2013 VX30 is ultra-red, the first such Neptunian Trojan in its class. As such, 2013 VX30 may be a “missing link” between the Trojan and TNO populations. Using a simulation of the DES TNO detection efficiency, we find that there are 162 ± 73 Trojans with Hr
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evidence for color dichotomy in the primordial Neptunian trojan population
Icarus, 2019Co-Authors: Hsing Wen Lin, D W Gerdes, S Hamilton, Fred C Adams, G M Bernstein, M Sako, Pedro Bernadinelli, D L Tucker, Sahar S Allam, Juliette C BeckerAbstract:Abstract In the current model of early Solar System evolution, the stable members of the Jovian and Neptunian Trojan populations were captured into resonance from the leftover reservoir of planetesimals during the outward migration of the giant planets. As a result, both Jovian and Neptunian Trojans share a common origin with the primordial disk population, whose other surviving members constitute today’s trans-Neptunian object (TNO) populations. The cold (low inclination and small eccentricity) classical TNOs are ultra-red, while the dynamically excited “hot” (high inclination and larger eccentricity) population of TNOs contains a mixture of ultra-red and blue objects. In contrast, Jovian and Neptunian Trojans are observed to be blue. While the absence of ultra-red Jovian Trojans can be readily explained by the sublimation of volatile material from their surfaces due to the high flux of solar radiation at 5 AU, the lack of ultra-red Neptunian Trojans presents both a puzzle and a challenge to formation models. In this work we report the discovery by the Dark Energy Survey (DES) of two new dynamically stable L4 Neptunian Trojans, 2013 VX30 and 2014 UU240, both with inclinations i > 30°, making them the highest-inclination known stable Neptunian Trojans. We have measured the colors of these and three other dynamically stable Neptunian Trojans previously observed by DES, and find that 2013 VX30 is ultra-red, the first such Neptunian Trojan in its class. As such, 2013 VX30 may be a “missing link” between the Trojan and TNO populations. Using a simulation of the DES TNO detection efficiency, we find that there are 162 ± 73 Trojans with Hr