• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 2
  • 1
  • Tagged with
  • 17
  • 17
  • 5
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Three New Species and One New Record of the Genus Doryphoribius Pilato, 1969 (Tardigrada: Eutardigrada: Hypsibiidae) from the Great Smoky Mountains National Park (Tennessee, USA)

Bartels, P., Nelson, D. R., Kaczmarek,, Michalczyk, 01 December 2008 (has links)
Three new eutardigrades, Doryphoribius longistipes sp. nov., Doryphoribius minimus sp. nov. and Doryphoribius tergumrudis sp. nov., are described from stream periphyton, rock lichen and cave soil and leaf litter samples collected in the limestone-based Cades Cove area of the Great Smoky Mountains National Park in eastern Tennessee, USA. Doryphoribius longistipes sp. nov. differs from other species mainly by the higher ratio of the secondary to the primary claw branches. Doryphoribius minimus sp. nov. differs from D. gibber, D. mariae and D. vietnamensis mainly by its smaller body size and different arrangement of dorsal gibbosities. Doryphoribius tergumrudis sp. nov. differs from D. evelinae by the absence of gibbosities and tubercles on legs I-III, the presence of lunulae and the absence of eyes. Additionally the three new species differ from other congeners by some other morphological and morphometric characters. Another species, Doryphoribius doryphorus Binda and Pilato, 1969, is a new record for Tennessee.
2

Taxonomía y epidemiología del género aeromonas

Alperi Vega, Anabel 31 July 2009 (has links)
Durante la presente tesis doctoral se ha establecido la presencia de variabilidad interoperónica en el gen ARNr 16S de Aeromonas y observado que ésta afectaba a la taxonomía del género, limitando la identificación de A. caviae, A. media y A. veronii. La secuenciación del gen rpoD permitió identificar las cepas con variabilidad interoperónica a nivel de especie y reconocer 5 nuevas especies del género: A. fluvialis, A. taiwanensis, A. sanarelii, A. piscicola y A. rivuli. En colaboración con diversos hospitales españoles se han descrito los primeros aislados de A. aquariorum de origen extraintestinal, el segundo caso en adultos de síndrome urémico hemolítico (SUH) asociado a Aeromonas y se ha podido demostrar la presencia en este género del gen stx2 asociado al SUH. Se han revisado las características clínicas y microbiológicas de las infecciones de herida quirúrgicas relacionadas con Aeromonas. Finalmente, se ha descrito el primer caso de inducción in vivo de resistencia al imipenem en una cepa de A. veronii. Los resultados de esta tesis han dado lugar o contribuido a la publicación de 13 artículos científicos en revistas internacionales. / During this thesis has established the presence of inter-operon variability in 16S rRNA gene of Aeromonas and observed that it affected the taxonomy of the genus, limiting the identification of A. caviae, A. media and A. veronii. The rpoD gene sequences identified strains with variability at the species level and recognize 5 new Aeromonas species: A. fluvialis, A. taiwanensis, A. sanarelii, A. piscicola and A. rivuli. In collaboration with various Spanish hospitals have described the first isolation of A. aquariorum from extraintestinal origin, the second adult case of hemolytic uremic syndrome (HUS) associated with Aeromonas and demonstrated the presence of stx2 gene associated with HUS in Aeromonas. We reviewed the clinical and microbiological characteristics of surgical wound infections associated with Aeromonas. Finally, we described the first case of in vivo induction of resistance to imipenem in a strain of A. veronii. The results of this thesis have led or contributed to the publication of 13 scientific papers in international journals.
3

Actinobactérias da Antártica produtoras de compostos anticâncer / Antarctic actinobacteria producing anticancer compounds

Leonardo José da Silva 20 August 2018 (has links)
A utilização de produtos naturais para a terapêutica do câncer foi iniciada com a actinomycina D, obtida a partir de culturas de Streptomyces e desde então, a busca por compostos bioativos de origem natural constitui uma importante linha de pesquisa. Estima-se que aproximadamente 60% dos agentes antineoplásicos, introduzidos para a terapia do câncer nas últimas décadas, tem origem vegetal ou microbiana. Dentre os micro-organismos proeminentes para produção de compostos ativos, as actinobactérias se destacam pela versatilidade metabólica, praticidade para cultivo in vitro e eficiência para produção de compostos com atividade anticâncer. Em seu último relatório, a Organização Mundial da Saúde reportou 8,8 milhões de mortes em decorrência de câncer, no ano de 2017. O índice representa um em cada seis óbitos em todo o mundo, sendo mais expressivo em países de média e baixa renda. Vale ressaltar que avanços significativos foram alcançados nos últimos anos para o tratamento de leucemia aguda infantil e tumores derivados de células germinais. Contudo, tumores sólidos de pulmão, próstata, mama e cólon ainda representam altos índices de mortalidade. Frente a isso, torna-se evidente a necessidade de identificar e desenvolver estratégias para o tratamento da doença. Com intuito de acessar novos recursos microbianos com potencial biotecnológico, a prospecção avança para áreas pouco exploradas, como por exemplo, o Continente Antártico. A Antártica foi o último dos continentes a ser acessado pelo homem e apresenta características edafoclimáticas favoráveis ao endemismo. Em vista da problemática e da potencialidade do Continente Antártico, os recursos microbiológicos associados à rizosfera de Deschampsia antarctica Desv. foram acessados e avaliados para a produção de compostos com propriedade antitumoral. Em resultado foram obtidos 42.528 clones metagenômicos e 72 linhagens de actinobactérias, dentre as quais Streptomyces sp. CMAA 1527, que apresentou pronunciada atividade antiproliferativa in vitro, para tumores de mama, pulmão, rim e sistema nervoso central, através da produção de cinerubina B. A análise taxonômica das actinobactérias isoladas revelou a presença de linhagens com baixo índice de similaridade, com as linhagens tipo conhecidas, o que pode significar a presença de novas espécies para os gêneros Nocardia, Rhodococcus e Streptomyces, reconhecidos pela capacidade de produzir metabólitos ativos e enzimas de interesse biotecnológico. A análise taxonômica polifásica da linhagem CMAA 1533 possibilitou a descrição da espécie Rhodococcus psychrotolerans sp. nov. (TaxoNumber TA00191; NRRL B-65465T = DSM 104532T), grupo bacteriano promissor como agente de biorremediação e produção de compostos bioativos. Com isso, o Continente Antártico foi considerado um ambiente promissor para a busca de novos micro-organismos, dentre eles actinobactérias, eficientes na produção de compostos antitumorais e outras substâncias com potencial biotecnológico. / The use of natural products for cancer therapy was initiated with the actinomycin D, obtained from Streptomyces. Since then, the search of bioactive from natural sources represent an essential line of research. It is estimated that approximately 60% of the antineoplasic agents inserted for the cancer therapy in recent decades have vegetal and microbial origin. Among the prominent microorganisms used to produce active compounds, actinobacterias are known by their metabolical versatility, convenience related to in vitro culture, and efficiency on the production of anticancer compounds. The Health World Organization, on its last review, reported 8.8 million of deaths in 2017, caused by cancer. Those numbers represent one out of six deaths worldwide, being more expressive in middle and low income countries. It is worth pointing out that meaningful advances were established in recent years for the treatment of childhood acute leukemia and germ cell-derived tumors. However, solid tumors of the lung, prostate, breast and colon still represent high mortality rates. For this reason, it is necessary to identify and develop strategies for the treatment of the disease. With the aim of accessing new microbial resources that contain biological potential, the prospection advance to areas barely explored, such as the Antarctic Continent. Antarctica was the last of the continents to be accessed by man and presents edaphoclimatic characteristics favorable to endemism. In light of the problematic and the potentiality of the Antarctic Continent, the microbiological resources associated with the rhizosphere of Deschampsia antarctica Desv. were accessed and evaluated for the production of compounds with antitumor properties. The results obtained had shown 42,528 metagenomic clones and 72 strains of actinobacteria, among them Streptomyces sp. CMAA 1527, which had presented anti-proliferative activity in vitro to breast, lung, kidney and central nervous system tumors, through the production of cinerubin B. The taxonomic analysis of the actinobacteria isolated revealed the presence of strains with low rate of similarity, with known type strains, which may mean the presence of new species for the genera Nocardia, Rhodococcus and Streptomyces, recognized for the ability to produce active metabolites and enzymes of biotechnological interest. The polyphasic approach of the CMAA 1533 strain made possible the description of the species Rhodococcus psychrotolerans sp. nov. (TaxoNumber TA00191; NRRL B-65465T = DSM 104532T), promising bacterial group as a bioremediation agent and production of bioactive compounds. As a result, the Antarctic Continent was considered a promising environment to search new microorganisms, among them, the actinobacteria, which is efficient on the production of antitumor compounds and other substances with biotechnological potential.
4

Actinobactérias da Antártica produtoras de compostos anticâncer / Antarctic actinobacteria producing anticancer compounds

Silva, Leonardo José da 20 August 2018 (has links)
A utilização de produtos naturais para a terapêutica do câncer foi iniciada com a actinomycina D, obtida a partir de culturas de Streptomyces e desde então, a busca por compostos bioativos de origem natural constitui uma importante linha de pesquisa. Estima-se que aproximadamente 60% dos agentes antineoplásicos, introduzidos para a terapia do câncer nas últimas décadas, tem origem vegetal ou microbiana. Dentre os micro-organismos proeminentes para produção de compostos ativos, as actinobactérias se destacam pela versatilidade metabólica, praticidade para cultivo in vitro e eficiência para produção de compostos com atividade anticâncer. Em seu último relatório, a Organização Mundial da Saúde reportou 8,8 milhões de mortes em decorrência de câncer, no ano de 2017. O índice representa um em cada seis óbitos em todo o mundo, sendo mais expressivo em países de média e baixa renda. Vale ressaltar que avanços significativos foram alcançados nos últimos anos para o tratamento de leucemia aguda infantil e tumores derivados de células germinais. Contudo, tumores sólidos de pulmão, próstata, mama e cólon ainda representam altos índices de mortalidade. Frente a isso, torna-se evidente a necessidade de identificar e desenvolver estratégias para o tratamento da doença. Com intuito de acessar novos recursos microbianos com potencial biotecnológico, a prospecção avança para áreas pouco exploradas, como por exemplo, o Continente Antártico. A Antártica foi o último dos continentes a ser acessado pelo homem e apresenta características edafoclimáticas favoráveis ao endemismo. Em vista da problemática e da potencialidade do Continente Antártico, os recursos microbiológicos associados à rizosfera de Deschampsia antarctica Desv. foram acessados e avaliados para a produção de compostos com propriedade antitumoral. Em resultado foram obtidos 42.528 clones metagenômicos e 72 linhagens de actinobactérias, dentre as quais Streptomyces sp. CMAA 1527, que apresentou pronunciada atividade antiproliferativa in vitro, para tumores de mama, pulmão, rim e sistema nervoso central, através da produção de cinerubina B. A análise taxonômica das actinobactérias isoladas revelou a presença de linhagens com baixo índice de similaridade, com as linhagens tipo conhecidas, o que pode significar a presença de novas espécies para os gêneros Nocardia, Rhodococcus e Streptomyces, reconhecidos pela capacidade de produzir metabólitos ativos e enzimas de interesse biotecnológico. A análise taxonômica polifásica da linhagem CMAA 1533 possibilitou a descrição da espécie Rhodococcus psychrotolerans sp. nov. (TaxoNumber TA00191; NRRL B-65465T = DSM 104532T), grupo bacteriano promissor como agente de biorremediação e produção de compostos bioativos. Com isso, o Continente Antártico foi considerado um ambiente promissor para a busca de novos micro-organismos, dentre eles actinobactérias, eficientes na produção de compostos antitumorais e outras substâncias com potencial biotecnológico. / The use of natural products for cancer therapy was initiated with the actinomycin D, obtained from Streptomyces. Since then, the search of bioactive from natural sources represent an essential line of research. It is estimated that approximately 60% of the antineoplasic agents inserted for the cancer therapy in recent decades have vegetal and microbial origin. Among the prominent microorganisms used to produce active compounds, actinobacterias are known by their metabolical versatility, convenience related to in vitro culture, and efficiency on the production of anticancer compounds. The Health World Organization, on its last review, reported 8.8 million of deaths in 2017, caused by cancer. Those numbers represent one out of six deaths worldwide, being more expressive in middle and low income countries. It is worth pointing out that meaningful advances were established in recent years for the treatment of childhood acute leukemia and germ cell-derived tumors. However, solid tumors of the lung, prostate, breast and colon still represent high mortality rates. For this reason, it is necessary to identify and develop strategies for the treatment of the disease. With the aim of accessing new microbial resources that contain biological potential, the prospection advance to areas barely explored, such as the Antarctic Continent. Antarctica was the last of the continents to be accessed by man and presents edaphoclimatic characteristics favorable to endemism. In light of the problematic and the potentiality of the Antarctic Continent, the microbiological resources associated with the rhizosphere of Deschampsia antarctica Desv. were accessed and evaluated for the production of compounds with antitumor properties. The results obtained had shown 42,528 metagenomic clones and 72 strains of actinobacteria, among them Streptomyces sp. CMAA 1527, which had presented anti-proliferative activity in vitro to breast, lung, kidney and central nervous system tumors, through the production of cinerubin B. The taxonomic analysis of the actinobacteria isolated revealed the presence of strains with low rate of similarity, with known type strains, which may mean the presence of new species for the genera Nocardia, Rhodococcus and Streptomyces, recognized for the ability to produce active metabolites and enzymes of biotechnological interest. The polyphasic approach of the CMAA 1533 strain made possible the description of the species Rhodococcus psychrotolerans sp. nov. (TaxoNumber TA00191; NRRL B-65465T = DSM 104532T), promising bacterial group as a bioremediation agent and production of bioactive compounds. As a result, the Antarctic Continent was considered a promising environment to search new microorganisms, among them, the actinobacteria, which is efficient on the production of antitumor compounds and other substances with biotechnological potential.
5

Marine Tardigrades of the Bahamas With the Description of Two New Species and Updated Keys to the Species of Anisonyches and Archechiniscus

Bartels, Paul J., Fontoura, Paulo, Nelson, Diane R. 20 May 2018 (has links)
This is the first survey of subtidal marine tardigrades from the Bahamas, and we compare our results with earlier studies of Bahamian intertidal habitats. In 2011 and 2014 we collected 60 subtidal sand samples from Bimini, the Berry Islands, New Providence, Eleuthera, and the Exumas. We found 11 species only one of which, Dipodarctus subterraneus (Renaud- Debyser, 1959), had been found in the previous intertidal Bahamian collections. Thus, 10 species are new records for the Bahamas, and four of these are new to science. We describe two of the new species (Archechiniscus bahamensis sp. nov. and Anisonyches eleutherensis sp. nov.). Additional material is needed for a conclusive identification of the undescribed species of Batillipes and Florarctus. Based on examination of the holotype of Anisonyches diakidius Pollock, 1975, we redescribe this species and give an emended diagnosis of the genus and the species. We also provide new keys to the spe-cies in the genera Archechiniscus and Anisonyches. A Chao2 species richness estimate indicated that our sampling effort was extensive and probably recovered most common species. Correlations of abundance and diversity indices with regard to depth, distance to nearest shore, and sediment grain size were not significant.
6

Sinomenium Macrocarpum sp. nov. (Menispermaceae) From the Miocene-Pliocene Transition of Gray, Northeast Tennessee, USA

Liu, Yu Sheng C., Jacques, Frédéric M. 01 February 2010 (has links)
The present study documents the first confirmed fossil record of Sinomenium in Menispermaceae, Sinomenium macrocarpum sp. nov., from the recently discovered Gray Fossil Site in Tennessee, southeastern USA. The fossil species is represented by more than 120 endocarps, all of which are characterized by their horseshoe-shaped form and occurrence of highly ornamented protuberances on both dorsal and lateral crests. A combination of their relatively large size and highly developed of protuberances on the surface of endocarp warrants the new species. The new species is justified through a detailed comparison with the related and published extant and fossil species. The discovery of the genus in North America appears to support that the Gray site in southern Appalachian region represented a forest refugium during the late Neogene when the global cooling was intensified and grasslands were globally expanded.
7

Macrobiotus (Eutardigrada, Macrobiotidae) from the Great Smoky Mountains National Park, Tennessee/North Carolina, USA (North America): Two new species and six new records

Bartels, Paul J., Pilato, Giovanni, Lisi, Oscar, Nelson, Diane R. 27 February 2009 (has links)
As part of the All Taxa Biodiversity Inventory (http://www.dlia.org), we are conducting a large-scale multihabitat inventory of tardigrades in the Great Smoky Mountains National Park (GSMNP) in Tennessee and North Carolina, USA. Here we report our findings for the genus Macrobiotus (Eutardigrada, Macrobiotidae). Two new species, Macrobiotus martini sp. nov. and Macrobiotus halei sp. nov., are described from moss, lichen, soil and leaf litter samples. Macrobiotus martini sp. nov. differs from all other species of the Macrobiotus hufelandi group by having a very simple buccal armature without bands of teeth, very large elliptical cuticular pores, unique characteristics of the egg, and other morphometric characters. Macrobiotus halei sp. nov. differs from other species in the Macrobiotus richtersi group by having very small cuticular tubercles, well-developed macroplacoids, unique characteristics of the egg, and other morphometric characters. Seven additional Macrobiotus species have been identified in the GSMNP: M. harmsworthi Murray, 1907, M. hufelandi Schultze, 1834, M. islandicus Richters, 1904, M, montanus Murray, 1910, M. pallarii Maucci, 1954, M. recens Cuénot, 1932, and M. tonollii Ramazzotti, 1956. All of these except M. harmsworthi are new records for the national park. In addition, M. pallarii is a new record for North Carolina, M. islandicus is a new record for North Carolina and Tennessee, M. montanus is a new record for the eastern USA, and M. recens is a new record for the USA.
8

Detection and Characterization of Rickettsiae in Western Australia

h.owen@uq.edu.au, Helen Clare Owen January 2007 (has links)
The aim of this study was to address the shortfall in current, in-depth knowledge of Western Australian rickettsiae investigating in particular, the role of native and feral animals as reservoir hosts. Two novel species of rickettsiae were detected in ticks collected from native and feral animals and humans, these were characterised using molecular methods. A preliminary investigation into the pathogenic potential of one of the isolates was also undertaken. To facilitate investigation, ectoparasites (principally ticks) were opportunistically collected from across the State, with an emphasis on native and feral animals and people. All ectoparasites were screened for rickettsial infection using a polymerase chain reaction incorporating Rickettsia-specific citrate synthase gene (gltA) primers. Preliminary sequencing was performed on representative PCR-positive samples from each geographical location, vertebrate host and ectoparasite in order to identify and characterize the infecting rickettsia. Isolation in cell culture and further genotypic characterization was then performed. Finally, a serosurvey and questionnaire were implemented in one of the study areas to determine whether people were being infected with a Rickettsia spp. and whether infection was associated with clinical signs. Ectoparasite collection produced three genera of ticks (Ixodes, Amblyomma and Haemaphysalis) from native animals, feral pigs and people, primarily from the southwest of Western Australia and Barrow Island in the Pilbara region. Ticks from a number of sources were shown to be infected with rickettsiae by the PCR, including feral pigs, people, bobtail lizards, kangaroos, bandicoots, burrowing bettongs, common brushtail possums and yellow-footed antechinus. Genotypic characterization of positive amplicons from ticks revealed the presence of two novel spotted fever group rickettsiae. Rickettsia gravesii sp. nov., named in honour of Dr Stephen Graves, was identified extensively throughout the southwest of the State and on Barrow Island in Ixodes, Amblyomma and Haemaphysalis spp. ticks from multiple hosts. Candidatus “Rickettsia antechini” was detected in Ixodes spp. only from yellow-footed antechinus in Dwellingup. In addition, a novel Bartonella spp. (Bartonella sp. strain Mu1) was also detected from Acanthopsylla jordani fleas collected from yellow-footed antechinus in Dwellingup. Rickettsia gravesii sp. nov. is most closely related to the Rickettsia massiliae subgroup of the spotted fever group and to R. rhipicephali in particular. Sequence similarities between this novel species and the subgroup were 99.7%, 98.4%, 95.8% and 97.4% based on its 16S rRNA, gltA, ompA and ompB genes respectively. Candidatus “Rickettsia antechini” also demonstrated a close relationship to the R. massiliae subgroup (99.4%, 94.8% and 97.1% sequence similarity based on its gltA, ompA and ompB genes respectively). The two novel Western Australian species demonstrated 98.4%, 96.3% and 96.7% sequence similarity to each other based on gltA, ompA and ompB genes respectively indicating separate species. The novel Bartonella spp. (Bartonella sp. strain Mu1) detected in fleas collected from yellow-footed antechinus in Dwellingup demonstrated greatest gltA gene sequence similarity to Bartonella strain 40 at 86.1%. Results from the serosurvey and questionnaire-based investigation into the zoonotic importance of R. gravesii sp. nov. on Barrow Island supported the results of the tick study and suggested that a tick-borne rickettsia(e) was infecting people on the island. However, a significant association between seroconversion and a history of symptoms consistent with a rickettsiosis was not found, and it is possible therefore, that R. gravesii sp. nov. produces only asymptomatic infections. Future work on rickettsiae in Western Australia will involve phenotypic characterization of the novel species, further investigation of their epidemiology and pathogenicity and an ongoing search for additional undiscovered species.
9

Aquatic tardigrades in the Great Smoky Mountains National Park, North Carolina and Tennessee, U.S.A., with the description of a new species of Thulinius (Tardigrada, Isohypsibiidae)

Bertolani, Roberto, Bartels, Paul J., Guidetti, Roberto, Cesari, Michele, Nelson, Diane R. 13 February 2014 (has links)
As part of the All Taxa Biodiversity Inventory (http://www.dlia.org), an extensive survey of tardigrades has been conducted in the Great Smoky Mountains National Park (GSMNP) in Tennessee and North Carolina, U.S.A., by Bartels and Nelson. Freshwater tardigrades include three species in the aquatic genus Thulinius (Eutardigrada, Isohypsibiidae). A new species, Thulinius romanoi, described from stream sediment, is distinguished from all other congeners by having a sculptured cuticle. In addition, the presence of Thulinius augusti (Murray, 1907) was verified by combined morphological and molecular analysis, and nine specimens of a third species, Thulinius cf. saltursus, were also found. Thulinius augusti is a new record for the United States. Thulinius saltursus (Schuster, Toftner & Grigarick, 1978) was previously recorded in California and Ohio, but our specimens vary slightly in morphology. The list of tardigrades from streams in the GSMNP was updated to a total of 44 species, 22 of which were predominantly or exclusively aquatic.
10

Tertiary Ginkgo Ovulate Organs With Associated Leaves From North Dakota, U.S.A., and Their Evolutionary Significance

Zhou, Zhiyan, Quan, Cheng, Liu, Christopher Yu Sheng 01 January 2012 (has links)
The evolutionary history of Ginkgo is poorly understood for the Cenozoic Era because of the rarity of fossil reproductive organs. We here describe a new species, Ginkgo cranei sp. nov., on the basis of well-preserved ovulate organs and associated leaves from the Upper Paleocene Sentinel Butte Formation of North Dakota, USA. The ovulate organ is of the modern type, which lacks a pedicel supporting each of the two ovules. The ovules are seated in separate collars directly attached to the peduncle, but only one of them is mature. Stomatal complexes are mostly amphicyclic, with deeply sunken guard cells and slightly raised subsidiary cells. They are sparsely distributed among epidermal cells characterized by domelike, strongly bulging periclinal walls and developed anticlinal wall flanges in integument and collar cuticles. The associated leaves are generally similar to the ovulate organ in cuticular structure. Ginkgo cranei is the only Tertiary species of the genus described in which the ovulate organs are studied in some detail. The study further corroborates the hypothesis that modern Ginkgo evolved from its ancestors by reduction and is helpful to classify Cenozoic ginkgos in a natural system.

Page generated in 0.0493 seconds