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  • 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

Sexual compatibility and construction of molecular linkage maps in olives (Olea europaea L.) / Shubiao Wu.

Wu, Shubiao January 2002 (has links)
"September 2002" / Bibliography: leaves 142-159. / viii, 159, [17] leaves : ill. (some col.), plates, photograph ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates self- and cross-compatibility using 5 common commercial cultivars of olive. Frantoio is found to b a good general polliniser for the other cultivars. The sex ratio of flowers, pollen viability, and male sterility were also examined Another objective was the construction of a molecular linkage map for olives, using a cross between Frantoio and Kalamata and microsatellite markers using the pseudo-testcross strategy. Approximately 45% of the genome was mapped. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 2002
22

CHARACTERIZATION OF <em>WOLBACHIA</em> AND ITS INTERACTION IN HOST MOSQUITOES

Suh, Eunho 01 January 2011 (has links)
Wolbachia are maternally inherited, obligate, intracellular bacteria inducing a form of sterility known as cytoplasmic incompatibility. Wolbachia based strategies have been proposed for the control of disease vectors. One example is to use a population replacement strategy to drive into natural population a novel Wolbachia that modifies the age structure of a vector population, reducing disease transmission. In this research, the effects of a life-shortening stain of Wolbachia (popcorn Wolbachia) are transferred into the mosquitoes Aedes albopictus (Chapter Two and Three) and A. aegypti (Chapter Four and Five). In Chapter Two, the Wolbachia symbiosis significantly reduced fecundity and egg hatches in A. albopictus, with Wolbachia being highly pathogenic in this mosquito species. In Chapter Three, the relationship between popcorn Wolbachia and its host (in a triple-infected mosquito strain) varied with the mosquito diet. Feeding on mouse blood was associated with the loss of infection, whereas the infection was maintained in human blood-fed mosquito lines. Egg viability of triple infected mosquito was reduced only with mouse blood. In Chapter Four, the reduced competitiveness (e.g., low survival and increased developmental time) of infected A. aegypti immatures was associated with popcorn Wolbachia, relative to uninfected individuals in low food condition. In Chapter Five, the decreased survival of immature A. aegypti was associated with popcorn Wolbachia in the presence of potential predators (i.e., older A. aegypti or A. albopictus larvae). Using a novel behavioral assay, a delayed larval reaction to light avoidance was observed to be associated with the infection, suggesting Wolbachia effects on immature host behaviors. In Chapter Six, popcorn Wolbachia and wAlbB infected A. aegypti showed similar reproduction potential. No reduced level of CI or mating competitiveness was observed in wAlbB infected males. The results suggest the wAlbB infection in A. aegypti can be an additional agent for Wolbachia-based control strategies. In Chapter Seven, a filtering system using commercially available sieves was able to separate immature mosquitoes from water, preventing escape of mosquitoes. In Chapter Eight, an inexpensive artificial blood feeding was designed for feeding multiple mosquito cages. The results support the use of these tools to facilitate mass rearing of mosquitoes.
23

Veiksnnių, įtakojančių naujagimių hiperbilirubinemiją, esant ABO antigeniniam netapatumui, vertinimas / The Assessment of Factors Influencing Neonatal Hyperbilirubinemia in ABO Incompatibility

Stonienė, Dalia 09 September 2010 (has links)
Tyrimo tikslas – įvertinti veiksnius, turinčius įtakos bilirubino koncentracijai naujagimio kraujyje, ir nustatyti kriterijų, kuriuo remiantis galima prognozuoti naujagimių hiperbilirubinemiją esant ABO antigeniniam netapatumui. Tyrimo uždaviniai: įvertinti motinos ir naujagimio veiksnius, turinčius įtakos naujagimio bilirubino koncentracijai kraujo serume 6 gyvenimo valandą; ištirti veiksnius, turinčius įtakos bilirubino koncentracijos naujagimio kraujo serume pokyčiui pirmą–trečią gyvenimo parą bei pokyčio prognozinę vertę; nustatyti bilirubino koncentracijos kraujo serume, hematokrito, retikulocitų, sferocitų kiekių ir tiesioginės Kumbso reakcijos vertę prognozuojant naujagimių hiperbilirubinemiją, esant ABO antigenininiam netapatumui; palyginti invazinį ir neinvazinį bilirubino koncentracijos nustatymo metodus esant ABO antigeniniam netapatumui; įvertinti perkutaninės bilirubinometrijos vertę diagnozuojant naujagimių hiperbilirubinemiją esant ABO antigeniniam netapatumui. / The aim of the study was to assess the factors influencing neonatal bilirubin level and to establish predictive criteria of neonatal hyperbilirubinemia in ABO antigenic incompatibility. The tasks to be carried out were as follows: to establish maternal and neonatal factors influencing neonatal total serum bilirubin at the age of 6 hoursTo establish the factors influencing the change of neonatal total serum bilirubin on days 1-3 of life and to identify the predictive value of this change. To establish the value of total serum bilirubin, hematocrit, reticulocyte, spherocyte and direct Coomb’s test in prognosing neonatal hyperbilirubinemia in ABO incompatibility, to compare non-invasive and invasive methods of total serum bilirubin assessment in the case of ABO incompatibility.
24

Evolution of Wolbachia-Drosophila interactions and implications for Wolbachia-based biocontrol

Carrington, Lauren Bree January 2010 (has links)
Wolbachia is a maternally inherited α-proteobacteria that lives an obligate intracellular lifestyle in its eukaryotic hosts. Wolbachia pipientis was first identified in the 1920’s in the mosquito Culex pipiens; Wolbachia has since been detected in a broad range of hosts. Wolbachia induces a number of diverse reproductive manipulations in many of its hosts, implicating Wolbachia in control strategies for target species. However, changes in host bacterial interactions can evolve toward mutualism, and this requires investigation in target systems. / This first part of this work examines changes in the Drosophila simulans-Wolbachia Riverside system in California. This system, studied for a period of more than two decades, provides a rare example in nature of a symbiotic relationship shifting from parasitism to mutualism. In my study, no changes in overall estimates of infection frequency, maternal transmission or cytoplasmic incompatibility were found, however there appears to be heterogeneity in maternal transmission rates and the ability of males to induce cytoplasmic incompatibility (CI). The source of CI variation in one isofemale line was subsequently investigated through reciprocal backcrossing with an old Wolbachia-infected strain, Riv88, and the variation was attributed to the Wolbachia genome. Further investigations are required to determine the extent of CI variation in the wild. These findings significant implications for the many applied projects that intend to exploit Wolbachia for its ability to manipulate host reproductive systems. / The second part of this work investigates the extent to which evolution of a host-bacterial symbiosis can influence the effectiveness of control strategies using Wolbachia. A particular strain of Wolbachia, named popcorn (wMelPop), has been isolated for its ability to reduce host longevity. This bacterium has the capacity to alter the age structure of the target host populations. As many vector-borne diseases (eg: Dengue Fever, Malaria) require an incubation period within the vector prior to transmission to the final host, a reduction in the lifespan of vector populations has the potential to lower transmission levels. The long term stability of this bacterial strain has been investigated in its native host (Drosophila melanogaster), and a novel host (D. simulans). The longevity-shortening phenotype and several life-history traits that might influence the effectiveness of control strategies have been examined. Host genetic background and the indirect selection on the longevity phenotype (via early or late fecundity selection) were found to influence multiple life-history traits in these species. The source of this variation in D. melanogaster is attributed primarily to the host, but can also be influenced by Wolbachia. Strong host background effects were noted in D. simulans, which highlights the importance of testing multiple backgrounds for suitability of use in applied projects. / This work has allowed for greater understanding of the potential for evolution within host-symbiont systems, and can be used to provide a framework for undertaking projects that will use Wolbachia as biological control agents. Future projects should consider the potential for evolution in detail under laboratory conditions before control strategies are implemented in the wild.
25

Evolution of Wolbachia-Drosophila interactions and implications for Wolbachia-based biocontrol

Carrington, Lauren Bree January 2010 (has links)
Wolbachia is a maternally inherited α-proteobacteria that lives an obligate intracellular lifestyle in its eukaryotic hosts. Wolbachia pipientis was first identified in the 1920’s in the mosquito Culex pipiens; Wolbachia has since been detected in a broad range of hosts. Wolbachia induces a number of diverse reproductive manipulations in many of its hosts, implicating Wolbachia in control strategies for target species. However, changes in host bacterial interactions can evolve toward mutualism, and this requires investigation in target systems. / This first part of this work examines changes in the Drosophila simulans-Wolbachia Riverside system in California. This system, studied for a period of more than two decades, provides a rare example in nature of a symbiotic relationship shifting from parasitism to mutualism. In my study, no changes in overall estimates of infection frequency, maternal transmission or cytoplasmic incompatibility were found, however there appears to be heterogeneity in maternal transmission rates and the ability of males to induce cytoplasmic incompatibility (CI). The source of CI variation in one isofemale line was subsequently investigated through reciprocal backcrossing with an old Wolbachia-infected strain, Riv88, and the variation was attributed to the Wolbachia genome. Further investigations are required to determine the extent of CI variation in the wild. These findings significant implications for the many applied projects that intend to exploit Wolbachia for its ability to manipulate host reproductive systems. / The second part of this work investigates the extent to which evolution of a host-bacterial symbiosis can influence the effectiveness of control strategies using Wolbachia. A particular strain of Wolbachia, named popcorn (wMelPop), has been isolated for its ability to reduce host longevity. This bacterium has the capacity to alter the age structure of the target host populations. As many vector-borne diseases (eg: Dengue Fever, Malaria) require an incubation period within the vector prior to transmission to the final host, a reduction in the lifespan of vector populations has the potential to lower transmission levels. The long term stability of this bacterial strain has been investigated in its native host (Drosophila melanogaster), and a novel host (D. simulans). The longevity-shortening phenotype and several life-history traits that might influence the effectiveness of control strategies have been examined. Host genetic background and the indirect selection on the longevity phenotype (via early or late fecundity selection) were found to influence multiple life-history traits in these species. The source of this variation in D. melanogaster is attributed primarily to the host, but can also be influenced by Wolbachia. Strong host background effects were noted in D. simulans, which highlights the importance of testing multiple backgrounds for suitability of use in applied projects. / This work has allowed for greater understanding of the potential for evolution within host-symbiont systems, and can be used to provide a framework for undertaking projects that will use Wolbachia as biological control agents. Future projects should consider the potential for evolution in detail under laboratory conditions before control strategies are implemented in the wild.
26

Expression of recombinant S-locus F-box-S2 protein and computational modeling of protein interaction at the self-incompatibility locus of Rosaceae

Ashkani, Jahanshah January 2012 (has links)
Philosophiae Doctor - PhD / Self-incompatibility (SI) is a major mechanism that prevents inbreeding in ow-ering plants, which was identi ed in Rosaceae, Solanaceae and Scrophulariace. In these families, SI is gametophytic and retains inter-speci c genetic variations by out-crossing promotion. Self-incompatibility is genetically controlled by an S- locus where both male (pollen) and female (pistil) S-determinants are encoded. The female determinant (SRNase) has been extensively studied, whereas its male counterpart (SLF/SFB) has only recently been characterized as a pollen-expressed protein, which encodes for an F-box domain. However, the exact mechanism of in- teraction between SLF/SFB and SRNase is still largely unclear in Rosaceae. This study takes a closer look at the mechanism of self-incompatibility to gain a clearer understanding of the ligand-receptor binding mechanism of SI using molecular evolutionary analysis, structure prediction and binding speci city characteriza- tion, the outcome of which, will translate into a guideline for future studies. The major aims of this study were to derive an evolutionary pattern for GSI in Rosaceae subfamilies and to further assess the collaborative non-self recognition in Malus domestica Borkh.. The evolutionary analysis suggests a di erence in the evolution- ary pattern of Prunoideae and Maloideae S-genes, hence proposing a di erence in their GSI systems. Furthermore, sites responsible for this divergence are identi ed as critical amino acids in GSI function. To maintain GSI it is expected that the S-genes must be linked and co-evolve as a genetic unit. The results of this study show that these genes have co-existed, while SRNase have experienced a higher rate of evolution compared to SLF, thus rejecting the co-evolution of these genes in Maloideae. Furthermore, positively selected sites of S-locus pistil and pollen genes were identi ed that are likely to be responsible for speci city determination. Di erent numbers of these sites are found for both S-genes, while SRNase holds a larger number of positively selected sites. Additionally a model of speci city is introduced that supports the collaborative non-self recognition in Malus GSI, while critical sites responsible for such speci city are proposed and mapped to the predicted ancestral tertiary structure of SRNase and SLF/SFB. The identi cation of regions determining pollen pistil speci city as well as proposing a Collaborative Non-self Recognition model for Malus domestica Borkh. provide greater in-sight into how pollen-pistil communication system works in Maloideae (Rosaceae subfamily).
27

An Investigation of Postzygotic Reproductive Isolation and Phenotypic Divergence in the Bark Beetle Dendroctonus Ponderosae

Bracewell, Ryan R. 01 May 2009 (has links)
Understanding reproductive isolation and divergence is the focus of speciation research. Recent evidence suggested that some Dendroctonus ponderosae populations produced hybrids with reproductive incompatibilities, a reproductive boundary undetected by phylogeographic analyses using molecular markers. Additionally, the unique bifurcated distribution of D. ponderosae and the proposed isolation-by-distance gene flow pattern around the Great Basin Desert provided a unique opportunity to investigate the evolution of postmating (postyzygotic) isolation while also understanding phenotypic divergence along latitudinal (climatic) gradients. First, I characterized the strength, biological pattern, and geographic pattern of postzygotic isolation in D. ponderosae by crossing increasingly divergent populations in a common garden environment. There was little evidence of hybrid inviability in these crosses, yet geographically distant crosses produced sterile males, consistent with expectations under Haldane's rule. Hybrid male sterility appeared at a threshold among increasingly divergent populations, was bidirectional (reciprocal crosses were affected), and less geographically distant crosses did not show significant gender-specific decreases in fitness. Second, a separate investigation of two critical phenotypic traits (body size and development time) was conducted on intrapopulation F2 generation offspring from a common garden experiment. Genetic differences contributing to phenotypic variance were interpreted within the context of the previously described reproductive incompatibilities, gene flow patterns, and latitudinal gradients. Genetic differences in development time were striking between faster developing and more synchronized northern populations and slower developing, less synchronized southern populations. Differences in development time were not detected between populations at similar latitudes. Body size, although more variable than developmental time, generally conformed to expectations, with northern populations being smaller than southern populations. Average adult size was found to be quite different between many populations and did vary between populations at similar latitudes, yet relative sexual size dimorphism was rather consistent. There was no evidence of correspondence between phenotypic traits (body size and development time) and either reproductive boundaries or gene flow patterns. The results suggest that latitudinally imposed climatic differences are likely driving phenotypic divergence between populations.
28

Self-Incompatibility in African Lycium (Solanaceae)

Feliciano, Natalie M 01 January 2008 (has links) (PDF)
Chapter one of my thesis has been published in the May 2008 issue of the journal Evolution under the title “A TALE OF TWO CONTINENTS: BAKER’S RULE AND THE MAINTENANCE OF SELF-INCOMPATIBILITY IN LYCIUM (SOLANACEAE).” This chapter was co-authored by Dr. Jill S. Miller and Dr. Rachel Levin.
29

Population genetics and breeding ecology of the rare clonal shrub, Spiraea virginiana (Rosaceae)

Brzyski, Jessica R. 20 September 2011 (has links)
No description available.
30

Biogeography and biosystematics of plum curculio, Conotrachelus nenuphar (Herbst)/Wolbachia interactions

Zhang, Xing 06 February 2007 (has links)
This research focused on the reproductive incompatibility and genetic differences between the two strains of plum curculio, Conotrachelus nenuphar (Herbst). Two molecular markers served as the basis for the strain distribution analysis of plum curculio and Wolbachia symbiont. One marker is the partial mitochondrial cytochrome oxidase gene subunit I (mtCOI) of plum curculio. Another marker is the Wolbachia Surface Protein (wsp) gene of Wolbachia associated with plum curculio. First, the reproductive compatibility of cross-populations mating in plum curculio was studied during the summers of 2004 and 2006. The results confirmed the reproductive incompatibility among plum curculio geographic populations. A unidirectional incompatibility was revealed in an approximate north and south transect of the range of plum curculio (4 x 4 two factorial design: NY, VA, FL, and WV): there was a significant low fertility in WV males mated with NY (40%) and VA (29%) females. The Florida population showed a different pattern: FL males have a significantly lower fertility with VA (46%) and WV (37%) females while FL females were compatible with all males from the four populations. The results of experiment 2 indicated that within the northern geographic area populations (3 x 3 two factorial design: NY, MA, and NJ) were compatible with each other. An opposite unidirectional reproductive incompatibility was revealed in the combination of NJ males with FL females, which showed a significant low fertility (47%). A bi-directional incompatibility occurred between FL and WV reciprocal cross mating. FL males mated with WV females (26%) and WV males mated with FL females (21%) both have the significant low fertility compared to fertility of within their population matings. The genetic diversity among plum curculio populations from different geographic locations was investigated using the partial mtCOI gene. A total of 50 samples from 10 populations were sequenced. PCR products were 863 bp in length. A total of 23 unique sequence haplotypes were found in the 50 samples tested. Haplotype G (n = 5), L (n = 12) and T (n = 13) comprised 60% of 50 samples. The nucleotide distances between those haplotypes ranged from 0.12% to 4.87%. Genetic distances between northern and southern group plum curculios range from 4.17% to 4.87%. Two distinct major clades were found, using three different phylogenetic analyses: 1) neighbor joining (NJ), 2) maximum-parsimony (MP), and 3) maximum-likelihood (ML). 100% bootstraps support the northern clade and the southern clade was strongly supported (100/100/86, NJ/MP/ML) as well. The mid-southern subclade within the southern clade was also strongly supported (70/82/71, NJ/MP/ML) and the far-southern subclade was supported in NJ tree (81%) but was not resovled in MP and ML trees. The mid-southern subclade included haplotypes from two NJ, Washington, VA (Ra), Blacksburg, VA (BL) and 50% of WV populations and the far-southern subclade included haplotypes from FL, GA, Whitethorne, VA (Ke), Troutville, VA (Bo) and another 50% of WV populations. The results suggested that the northern and the southern clade could correspond with the northern and southern strains, respectively, of plum curculio. In this study, the mtCOI sequence was highly informative as a molecular marker in that it was useful to distinguish C. nenuphar from northern and from southern geographic locations in the eastern United States. However, the number of generations per year of several geographic populations within the southern clade still needs to be determined. The distribution of Wolbachia infection associated with plum curculio strains was investigated. 91 of 93 samples were infected by Wolbachia. Three unique Wolbachia strains were identified. The strains wCne1 and wCne2 (593 bp) were 97% identical, and their sequences were both 84% identical with wCne3 (590 bp). The wsp sequence of wCne1 was 99% identical to Wolbachia sequenced from the neotropical beetle, Chelymorpha alternans Boheman (Keller et al. 2004). The wCne2 sequence was 98.5% identical to the flower bug, Orius nagaii Yasunaga (Miura and Tagami, unpublished). The wCne3 sequence was 100% identical to Wolbachia sequenced from the tephritid fruit fly, Dacus destillatoria (Jamnongluk et al. 2000) and the ant, Formica exsecta (Reuter and Keller 2003). PCR - Restriction Fragment Length Polymorphism (RFLP) was used for superinfection detection. Of 93 samples, 15 (16.1%), 21 (22.6%), 19 (20.4%), 36 (38.7%) samples were infected by wCne1, wCne2, wCne1 plus wCne2, and wCne3, respectively. Only two (2.2%) samples had no infection. The wCne3 strain was always present as a single infection. Therefore, current results suggest that Wolbachia strains approximate the distribution of plum curculio strains: the northern strain is infected with wCne1 and wCne2 strains in supergroup B, the southern strain is infected with wCne3 strain in supergroup A and the mid-Atlantic region is the convergence area. Compared with the haplotype distribution of plum curculio mtCOI gene, there was a closer relation of the mid-southern PC clade to the far-southern clade than to the northern clade. However, Wolbachia symbionts in mid-southern PC are more closely related to those in northern PC than to those in far-southern PC. The relationship of Wolabchia infection with reproductive incompatibility between plum curculio populations is also discussed. / Ph. D.

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