• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 17
  • 5
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 34
  • 8
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
21

Molecular genetic analysis of regulated secretion in Tetrahymena thermophila /

Chilcoat, Nicholas Doane. January 1999 (has links)
Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, June 1999. / Includes bibliographical references. Also available in the Internet.
22

Immune responses of sheep to rumen ciliates and the survival and activity of antibodies in the rumen fluid : thesis submitted fo the degree of Doctor of Philosophy / by Gnanapragasam Gnanasampanthan. / Videorecording has title: Effect of antibodies on the motility of rumen ciliates [videorecording]

Gnanasampanthan, Gnanapragasam January 1993 (has links)
Includes bibliographical references (leaves 197-259). / xv, 261, [9] leaves, [17] leaves of plates : ill. (some col.) ; 30 cm. + 1 videocassette (6 min. (VHS) : sd., col. ; 1/2 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Consists of a review of rumen ciliates, their implications in ruminant nutrition and a description of the research methods, the results and the conclusions drawn with regard to the prospects of establishing an immunological basis for the manipulation of rumen ciliates. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1994
23

Evaluation of Fabrea salina and other ciliates as alternative live foods for first-feeding red snapper, Lutjanus campechanus, larvae

Rhodes, Melanie Anne, January 2005 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.
24

Restrições hídrica e nutricional afetam aspectos fisiológicos e crescimento de mudas de cedro-australiano (Toona ciliata M. Roem. var. australis (F. Muell.) Bahadur) / Water and nutritional restrictions affect physiological aspects and growth in australian red cedar seedlings (Toona ciliata M. Roem. var. australis (F. Muell.) Bahadur)

Santos, Lauana Lopes dos 21 October 2016 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2017-08-16T17:22:07Z No. of bitstreams: 1 texto completo.pdf: 790580 bytes, checksum: 292f57963a127022984af0e9038158d5 (MD5) / Made available in DSpace on 2017-08-16T17:22:07Z (GMT). No. of bitstreams: 1 texto completo.pdf: 790580 bytes, checksum: 292f57963a127022984af0e9038158d5 (MD5) Previous issue date: 2016-10-21 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / O crescimento de Toona ciliata M.Roemer var. australis (F. Muell.) Bahadur (família Meliaceae) em regiões sujeitas a déficit hídrico e solos com baixa disponibilidade de nutrientes, como predomina no Brasil, requer várias adaptações morfológicas e fisiológicas. Com intuito de compreender essas adaptações que favorecem o crescimento, a composição isotópica do carbono (δ 13 C), características fisiológicas (trocas gasosas, fluorescência da clorofila a e teores de pigmentos) e, ainda, verificar se a adubação poderia mitigar os efeitos do déficit hídrico, foi conduzido um estudo em casa de vegetação com mudas de dois clones (BV1110 e BV1120) de T. ciliata por 126 dias. Após 90 dias de aclimatação as mudas receberam ou não adubação e foram submetidas a ciclos de restrição hídrica seguidos de reidratação. Após 8 dias da adubação, a restrição hídrica foi imposta por 5 dias, seguido de reidratação por 15 dias, e mais 8 dias de restrição hídrica até o fim do experimento. A restrição hídrica e, ou, nutricional reduziu a taxa de crescimento em altura (H), diâmetro do coleto (D), número de folíolos (NF), área foliar (AF), comprimento da raiz (L) e produção de biomassa total (Bt) e promoveu o crescimento das raízes, com conseqüente aumento da razão massa raiz/parte aérea (MSR/MSPA). As mudas de T. ciliata exibiram fortes respostas à adubação quando submetidas ao déficit hídrico seguido de reidratação, mas as respostas foram baixas em condição irrigada e sem adubação. Além disso, a adubação combinada com déficit hídrico aumentou a composição isotópica de carbono (δ 13 C) e a eficiência do uso da água (EUA). A falta de adubação, independente do fornecimento de água, diminuiu a taxa de crescimento, as trocas gasosas, as características de florescência da clorofila a (Chl a) e os toeres dos pigmentos fotossintéticos nos dois clones. As restrições hídricas e nutricionais reduziram ainda a eficiência quântica efetiva da conversão fotoquímica de energia no fotossistema II (PSII) e aumentou a dissipação de energia não fotoquímica, no entanto, não afetou a eficiência quântica máxima do PSII (Fv/Fm) ao ponto de causar fotoinibição. O teor de pigmentos fotossintéticos foi reduzido pelo déficit hídrico ou pela interação déficit hídrico e nutricional, e o efeito de tolerância cruzada foi observado. Ou seja, folhas de plantas com restrição combinando, restrição hídrica e nutricional, apresentaram, mais pigmentos em sua composição que as de plantas com apenas a restrição nutricional. Após a reidratação foi verificada recuperação de todas as características avaliadas, indicando plasticidade fisiológica dos clones em estudo. Diante disso, ficou claro que o suprimento adequado de adubação seria recomendável para estimular o crescimento, melhorar a EUA, aumentar a taxa fotossintética por meio do aumento dos teores de pigmentos fotossintéticos, além de aliviar os danos no PSII causados durante o déficit hídrico nos clones de cedro-australiano. O clone BV1110 apresentou menor NF, AF e Bt e maior L, H, MSR/MSPA, δ 13 C e EUA, com melhor recuperação dos aparatos fotossintéticos e maior taxa fotossintética sob déficit hídrico. Por outro lado, o clone BV1120 apresentou menor biomassa e comprimento de raízes e maior Bt e AF, maior discriminação isotópica e menor taxa fotossintética. O clone BV1120 foi classificado como menos tolerante e o clone BV1110 como mais tolerante ao déficit hídrico. Os resultados deste trabalho forneceram importantes informações no que concerne às diferentes respostas dos clones de T. ciliata ao déficit hídrico, somado ou não ao suprimento nutricional via adubação, contribuindo para o entendimento dos mecanismos utilizados pelas plantas de cedro-australiano para manter um alto grau de resiliência em caso de restrição hídrica e, ou, nutricional. / The planting of Toona ciliata M. Roemer var. australis (F. Muell.) Bahadur (Meliaceae family) in areas subject to water deficit and soil with low nutrient availability, as prevail in Brazil, requires several plant morphological and physiological adaptations. In order to understand these adaptations in growth, carbon isotopic composition (δ 13 C), and physiological variables (gas exchange, fluorescence of chlorophyll pigment content) and also understand if fertilization could mitigate the effects of water deficit, a study was conducted in a greenhouse with seedlings of two T. ciliata clones (BV1110 and BV1120) for 126 days. After 90 days of acclimatization the seedlings with or without the fertilization were subjected to water restriction cycles followed by rewatering. After 8 days of fertilization, water restriction was imposed for 5 days, followed by rewatering for 15 days, and more 8 days of water restriction by the end of the experiment. Water restriction and or nutritional reduced the rate of growth in height (H), diameter (D), number of folioles, leaf area, root length (L) and biomass production and promoted root growth, resulting in increased ratio of root mass/shoot (MSR/MSPA). The T. ciliata seedlings exhibited strong response to fertilization when subjected to water deficit followed by rewatering, but the responses were low in irrigated condition and without fertilization. In addition, fertilization combined with drought stress increased the δ 13 C, and efficiency of water use (WUE). The lack of fertilization independent water supplies, decreased growth rate, gas exchange, blooming characteristics Chl a and photosynthetic pigments in both clones. The water restriction and or nutritional also reduced the effective quantum efficiency of photochemical energy conversion in photosystem II (PSII) and increased non-photochemical energy dissipation, however, did not affect the maximum quantum efficiency of the PSII level to cause photoinhibition. The content of photosynthetic pigments was reduced by water deficit or by the interaction water and nutritional water deficit, and cross-tolerance effect was observed. Plants with combined restriction, water restrictionand nutritional show higher pigments contents in their composition than plants with only one restriction, nutritional. After rewatering, all the evaluated characteristics were recovered, indicating the physiological plasticity of the clones under study.Thus, an adequate supply of fertilizer would be recommended to stimulate growth, improve the WUE, increase the photosynthetic rate by increasing the photosynthetic pigments content, and alleviate the damage to the PSII caused during water deficit in the clones. Clone BV1110 showed lower number of folioles, leaf area and total biomass (Bt) and longer roots (L), height (H), MSR/MSPA, δ 13 C and WUE, with better recovery of photosynthesis indicators and higher photosynthetic rate under water deficit. In contrast, clone BV1120 showed lower root biomass and L and greater Bt and AF, the higher and lower isotopic photosynthetic rate discrimination, respectively. Despite clone BV1120 could probably withstand water deficit, it was classified as less tolerant than BV1110 to water deficit. These results provided important information regarding the responses of different clones T. ciliata water deficit, and nutrient supply, contributing to the understanding of the mechanisms activate by the australian red cedar plants to maintain a high degree resilience to water restriction and or nutritional.
25

Untersuchungen zur Ökophysiologie anaerober Protozoen /

Wagener, Stefan, January 1989 (has links)
Thesis (doctoral)--Universität Konstanz, 1989. / Appended are reprints of two articles, in English, "Electromigration, a tool for studies on anaerobic ciliates," by Stefan Wagener, Claudius K. Stumm, and Godfried D. Vogels, and "Monoxenic culture of the anaerobic ciliate Trimyema compressum Lackey," by S. Wagener and N. Pfennig. Includes bibliographical references.
26

Influência de fatores abióticos na produção do copépode Bestiolina similis e do protozoário ciliado Euplotes sp.

Annunciação, Wesley Freitas da January 2016 (has links)
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Aquicultura, Florianópolis, 2016. / Made available in DSpace on 2016-09-20T04:06:59Z (GMT). No. of bitstreams: 1 341113.pdf: 2905263 bytes, checksum: 2091519799e99de8cf9d62d8fe0232a7 (MD5) Previous issue date: 2016 / A aquicultura é a área com maior crescimento em nível mundial para produção de proteína animal, sendo que a piscicultura marinha é responsável por cerca de 9% da produção gerada pela maricultura. Porém, os alimentos vivos tradicionalmente utilizados na larvicultura de peixes marinhos, os rotíferos e artêmia, não são capazes de suportar o desenvolvimento adequado de larvas de diversas espécies de peixes, limitando assim a atividade. Alimentos vivos alternativos vêm sendo estudados ao longo das últimas décadas, porém ainda se faz necessário o desenvolvimento de tecnologias e de protocolos de produção. O objetivo do presente trabalho foi de avaliar o efeito dos fatores abióticos, temperatura, fotoperíodo e salinidade, e também da concentração de alimento na produtividade do copépode Bestiolina similis e do protozoário Euplotes sp., para se determinar uma faixa adequada para produção desses organismos. No primeiro estudo foi possível verificar que a temperatura afetou o crescimento e a reprodução de B. similis, sendo que a faixa entre 24 e 32 °C é adequada para produção da espécie, proporcionando elevada taxa de crescimento e fecundidade. Ao avaliarmos o efeito do fotoperíodo, observamos que a privação de luz provocou um efeito negativo sobre diversos parâmetros produtivos do copépode e que ciclos luminosos acima de 12 horas de luz podem ser utilizados para maximizar a produtividade. No terceiro estudo foi observado que o copépode B. similis é uma espécie que se adapta bem à ampla faixa de salinidade, sendo que os animais mantidos na faixa entre 25 e 35 g . L-1 apresentaram elevada fecundidade e rápido desenvolvimento. Foi possível observar também que o ciliado Euplotes sp. apresentou características favoráveis à produção massiva, como elevada taxa de crescimento; se adapta bem em diferentes condições de salinidade e temperatura e é resistente às condições adversas, como elevadas concentrações de amônia tóxica e baixos níveis de oxigênio dissolvido. Foram determinadas como faixas mais adequadas para a produção do ciliado Euplotes sp. a temperatura entre 26 e 32°C; salinidade entre 20 e 35 g . L-1, concentração de alimento de 250 mg de Protein Selco® . 10-6 ciliados; fotoperíodo entre 0 e 16 h de luz e baixos níveis ou ausência de aeração.<br> / Abstract : Aquaculture is the fastest growing area in worldwide for the production of animal protein, and marine fish farming accounts for about 9% of mariculture production. However, the live feeds traditionally used in marine fish larviculture, rotifers and artemia, are not able to support the proper development of several species fish larvae, thereby limiting the activity. Alternative live feeds have been studied over the past decades, but the development of technologies and protocols still is required. The objective of this study was to evaluate the effect of abiotic factors, temperature, photoperiod and salinity, in the productivity of copepod Bestiolina similis and the protozoa Euplotes sp., to determine an appropriate range for production of these organisms. In the first study, we found that the temperature affected the growth and reproduction of B. similis and the range between 24 and 32 ° C is suitable for producing this species, providing high growth rates and fecundity. To evaluate the effect of photoperiod, we found that the light deprivation had a negative effect on various production parameters of the copepod and the cycles above 12 hours of light can be used to maximize productivity. In the third study was observed that the copepod B. similis is able to adapts well to the wide range of salinity, and the animals kept between 20 and 30 g. L-1 had a high fertility and fast development. We also conclude that the ciliate Euplotes sp. showed characteristics favorable to mass production for aquaculture, as resistance to adverse conditions, including high concentrations of total ammonia and low oxygen levels; they present high growth rate; accepted sources of food as inert diet; and adapts well to different conditions of salinity and temperature. Was possible observe the proper range for the production of the ciliated the temperature between 26 and 32 ° C; salinity between 20 and 35 g. L-1, feed concentration of 250 mg . Protein Selco® . 10-6 cells; photoperiod between 0 and 16 light hours and should be kept at low levels or absence of aeration.
27

Comparative analysis of nuclear proteomes and strain-specific chromosomes in Oxytricha trifallax

Lu, Michael January 2023 (has links)
Ciliates are important model organisms that have been used to study many aspects of cellular biology, including telomeres, histone modifications, and ribozymes. These unicellular eukaryotes house both a germline genome and a somatic genome in distinct nuclear structures within a single cell. One of their most unique features is their ability to undergo complex programmed genome rearrangements, during which their germline genome is fragmented and rearranged to form a new somatic genome. This rearrangement process results in a highly specialized somatic genome with many polyploid short chromosomes that are rich with genes. While all ciliates can undergo this developmental process, Oxytricha trifallax experiences particularly complex rearrangements that result in a more radically unconventional structure in its somatic genome. Much of the previous work studying Oxytricha has been focused on the complex rearrangements that it undergoes during sexual development and the mechanisms that allow it to perform these genome rearrangements events at the level of accuracy required for proper somatic function afterwards. Due to this particular focus on Oxytricha sexual development, the rest of Oxytricha’s unique biology has not been studied to the same degree. For my thesis I examined two aspects of Oxytricha biology that have not been well understood. In Chapter 1 I report the results of a proteomic survey of both types of nuclei found within the vegetative cell, the somatic macronucleus and the germline micronucleus. We performed mass spectrometry on enriched samples of both nuclear types and analyzed the enrichment of proteins between the two. Despite some mitochondrial contamination, we found that many categories of functional proteins were enriched in one of the two nuclei. We validated the appropriate nuclear localization of specific proteins from each subcategory through imaging Our results confirmed many previously predicted aspects of the two nuclei and provide a valuable resource for further studies on nuclear proteins in Oxytricha. In Chapter 2 I describe various features of a comparative analysis between the somatic genomes of multiple strains of Oxytricha trifallax. Previous work from the lab has focused primarily on the reference strains JRB310 and JRB510, which are most commonly used due to their ability to mate. We generated four new draft assemblies of the somatic genomes of strains JRB27, JRB39, SLC89, and SLC92. Many metrics demonstrate that these new assemblies are largely complete. Our analyses of these new strains revealed that there are numerous strain-specific chromosomes in Oxytricha that can encode genes. While they do not seem to encode core genes that would be missing otherwise, they are prime candidates for further examination to identify mating type-related genes.
28

Les Cyrtophorida Ciliés thigmotactiques des parois immergées /

Deroux, Gilbert. January 1978 (has links)
Thesis (Ph. D.) - L'Université de Clermont II (U.E.R. Sciences exactes et naturelles à dominante recherche), 1978. / At head of title: Série : E ; No. d'ordre : 260.
29

Widespread 3D genome reorganization precedes programmed DNA rearrangement in Oxytricha trifallax

Villano, Danylo Julian January 2023 (has links)
3D genome organization recapitulates genome function, typically at the level of transcriptional state or chromatin state. Ciliates like Oxytricha trifallax possess highly specialized germline genomes, which play a role in sexual development but are largely transcriptionally silent. During Oxytricha development, the germline undergoes genome-wide rearrangement, transforming into a structurally distinct, transcriptionally active somatic genome. This wholesale rearrangement is programmed by transgenerational RNA copies of the somatic genome, which guide the retention of a small portion of the germline. Retained and eliminated sequences must be distinguished from each other and processed separately, but how this dichotomy is effected spatially or by chromatin organization is unknown. The breadth of Oxytricha genome dynamics presents the possibility of a complex relationship between chromatin architecture and genome function. We present new tools for studying the Oxytricha germline and apply them to map the 3D organization of the genome’s vegetative and developmental states using Hi-C. We find that the vegetative conformation primes the germline for development, while a massive spatial reorganization of the genome during development differentiates between retained and eliminated regions and precedes rearrangement of DNA. Further experiments suggest a role for RNA-DNA interactions and chromatin remodeling in this reorganization. This evidence supports a critical role for 3D architecture in programmed genome rearrangement.
30

Investigating the ecological role of cell signaling in free-living marine heterotrophic protists /

Hartz, Aaron J. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2011. / Printout. Includes bibliographical references (leaves 71-79). Also available on the World Wide Web.

Page generated in 0.0282 seconds