Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 22-23).

Thesis (PhD (Veterinary Science))--University of Pretoria, 2005. / Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:28:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-01Bitstream added on 2014-06-13T18:58:01Z : No. of bitstreams: 1 jesus_am_me_botfca.pdf: 159085 bytes, checksum: 57bda2a2bf183d269a42b6e9b4c596cd (MD5) / A banana (Musa spp.) é uma das frutas mais consumidas no mundo, e cultivada na maioria dos países tropicais. No Brasil, a produtividade média é baixa devido a vários fatores, dentre eles a incidência de pragas e doenças. Entre os problemas fitossanitários encontrados na cultura da bananeira os nematóides se destacam, sendo as espécies de maior importância: Radopholus similis, Meloidogyne spp., Helicotylenchus multicinctus, Pratylenchus coffeae e Rotylenchulus reniformis. O presente trabalho estudou a reação de diferentes genótipos de bananeira a Meloidogyne incognita raça 2, M. javanica e Pratylenchus coffeae. Para cada espécie de Meloidogyne foram estudadas dez genótipos de bananeira. No estudo com M. incognita foram estudados os genótipos Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, FHIA 17, Nanicão Magário, SH 3640, Pacovan e Prata Anã. Para M. javanica os genótipos estudados foram Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, Nanicão Magário, SH 3640, Pacovan, Prata Anã e Maçã. No experimento com P. coffeae foi desenvolvido utilizando nove genótipos PV 0344, SH 3640, Maçã, Thap Maeo, Caipira, Grande Naine, FHIA 1, FHIA 18 e Prata Anã. O delineamento em todos os experimentos foi inteiramente casualisado com quatro repetições para P. coffeae e seis repetições nos estudos com M. incognita e M. javanica. Cada parcela foi constituída de uma muda de bananeira proveniente de cultura de tecido. Estas mudas foram plantadas em recipientes plásticos de 2 litros de capacidade, contendo substrato composto de solo, areia e matéria orgânica na proporção 1:1:1, previamente autoclavado. Após uma semana do transplantio efetuou-se a... . / Banana plant (Musa spp.) is one of the more consumed fruit in the world and cultivated in many tropical countries. In Brazil, the productivity is low due to several factors, among them the incidence of pest and diseases. Among the problems found in the culture of the banana, the nematodes are stand out, being the species of larger importance Radopholus similis, Meloidogyne spp., Helicotylenchus multicinctus, Pratylenchus coffeae and Rotylenchulus reniformis. This research studied the reaction of different genotypes of banana to Meloidogyne incognita race 2, M. javanica and Pratylenchus coffeae. Ten banana genotypes were studied in Meloidogyne spp. experiments. The genotypes studied in M. incognita experiment were: Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, FHIA 17, Nanicão Magário, SH 3640, Pacovan and Prata Anã. In M. javanica experiment the genotypes studied were: Calypso, Buccaneer, Grande Naine, PV 0344, FHIA 2, Nanicão Magário, SH 3640, Pacovan, Prata Anã and Maçã. P. coffeae experiment was developed with nine genotypes, PV 0344, SH 3640, Maçã, Thap Maeo, Caipira, Grande Naine, FHIA 1, FHIA 18 and Prata Anã. Experiments design were completely randomized with four replication for P. coffeae. and six replication in the studies with M. incognita and M. javanica. Each plot was constituted of a plant of banana produced in vitro, planted in pot with 2 liters of capacity, with substratum composed of soil, sand and organic matter in 1:1:1 proportion, previously autoclaved. After a week of the banana plants transplant, the inoculation was made with 5.000 eggs/plant for M. javanica or for M. incognita and 1.000 specimens/plant for P. coffeae. Tomato plants ‘Rutgers’ were used as control of the viability of the nematodes. The evaluation of the experiments with Meloidogyne was accomplished 120 days after the inoculation. The analyzed parameters were: gall number, of the... (Complete abstract, click electronic address below).

The initiation of further development is fundamental to the infectious processes of parasitic nematodes. I have examined early developmental activation of Trichinella spiralis larvae during host invasion, with particular emphasis on gene regulation and the timing of events. Using a novel approach, changes in tissue specific transcriptional activity were observed in live larvae during the infectious process with the fluorescent nucleic acid dyes SYTO12 and acridine orange. Simultaneously, the metabolic switch from anaerobic metabolism, characteristic of the infective stage, to aerobic metabolism, as found in the enteral stages, was tracked by measuring activities of the key regulatory enzymes phosphoenolpyruvate carboxykinase and pyruvate kinase, as well as isocitrate dehydrogenase (NADP) activity, and used as a co-indicator for developmental activation. Both metabolic enzyme activities and transcription patterns were found to change in response to host death, liberation from the nurse cell, and exposure to components of the host stomach environment. The role of amphidial neurones in developmental regulation was examined using FITC based labelling, and at least part of the initial developmental processes were discovered to be under amphidial control. Changes to the surface properties of larvae during the process of infection were monitored using the fluorescent lipid probe PKH26, and gave evidence for temporal regulation of activation-related alterations of larval structure and/ or physiology. Further, RNA fingerprinting was carried out to identify specific genes associated with, or regulating, developmental activation. Some putatively differentially expressed transcripts were identified, but could not be completely characterised to date. The results give a clear indication that the activation processes of T. spiralis infective larvae occur at a much earlier time than previously thought, and are stimulated upon liberation of the larvae from the nurse cell inside the host stomach. Further, regulation of development appears to be under transcriptional control, and tissue specific transcription is initiated early during the infectious process, perhaps immediately after release from the nurse cell.

No description available.

abstract: Aboveground net primary production (ANPP) and belowground net primary production (BNPP) may not be influenced equally by the same factors in arid grasslands. Precipitation is known to affect ANPP and BNPP, while soil fauna such as nematodes affect the BNPP through herbivory and predation. This study on black grama grass (Bouteloua eriopoda) in the Chihuahuan Desert investigates the effects of precipitation and nematode presence or absence on net primary production (NPP) as well as the partitioning between the aboveground and belowground components, in this case, the fraction of total net primary production occurring belowground (fBNPP). I used a factorial experiment to investigate the effects of both precipitation and nematode presence on the components of NPP. I used rainout shelters and an irrigation system to alter precipitation totals, while I used defaunated and re-inoculated soil for the nematode treatments. Precipitation treatment and seasonal soil moisture had no effect on the BNPP and a nonsignificant positive effect on the ANPP. The fBNPP decreased with increasing precipitation and seasonal soil moisture, though without a significant effect. No predator nematodes were found in any of the microcosms at the end of the experiment, though other functional groups of nematodes, including herbivores, were found in the microcosms. Total nematode numbers did not vary significantly between nematode treatments, indicating that the inoculation process did not last for the whole experiment or that nematodes had little plant material to eat and resulted in low population density. Nematode presence did not affect the BNPP, ANPP, or the fBNPP. There were no significant interactions between precipitation and nematode treatment. The results are inconclusive, possibly as a result of ecosystem trends during an unusually high precipitation year, as well as the very low NPP values in the experiment that correlated with low nematode community numbers. / Dissertation/Thesis / Masters Thesis Biology 2018

The Ph.D. thesis enclosed focuses on various implications of scavenging by generalist predators on invertebrate cadavers. Comparison of the retention time for invertebrate cadavers in the field, with the detection period for decaying slug material in the guts of the predators is presented and indicates that PCR-based techniques are not able to distinguish between predated and scavenged food items. Disappearance rates for invertebrate cadavers in the field, together with generealist predator preference for dead prey were estimated and their implication on survival strategies of entomopathogenic and molluscicidal nematodes in the cadavers is discussed. Two different strategies were investigated and are presentd in the thesis.

Trichuriasis, caused by the intestinal nematode Trichuris, is a disease that affects up to a billion people worldwide. To date, most of our knowledge of this disease comes from the mouse model, Trichuris muris, which has been successfully used to dissect the immune-mediated effector mechanisms that elicit the expulsion of the nematode. Numerous studies have shown a temporal association between intestinal nematode expulsion and goblet cell hyperplasia; however their precise role in response to nematode infection remains elusive. Goblet cells found at mucosal surfaces secrete many constituent components of the mucus barrier, including the gel-forming mucins (Muc2 in the intestine); mucins are large multifunctional glycoproteins that provide the structural framework of the barrier. The studies presented in this thesis demonstrate that the mucosal barrier and in particular its mucin components, changes in response to acute and chronic T.muris infection. In animals resistant to chronic T. muris infection, IL-13-mediated increase in Muc2 production and secretion was observed at the site of infection. Critically, expulsion of the nematode was significantly delayed in the absence of Muc2. Further investigation subsequently showed that Muc5ac, a mucin normally expressed in non-intestinal mucosa was, in fact, expressed in the intestine following nematode infection and was associated with nematode expulsion in the resistant mice. Moreover, mice deficient in Muc5ac were susceptible to chronic infection, despite a strong underlying TH2-type immune response which is essential to eliminate the nematodes, suggesting that Muc5ac acts as a critical effector molecule. Several qualitative changes in the mucins were also noted during resistance: mucins were more highly charged and more sulphated during nematode expulsion. Overall, the changes within the mucus barrier during resistance result in altering the rheological properties of the mucus layer making it less porous and mucins were shown to directly 'damage' the nematodes during nematode expulsion as reflected by a significant reduction in ATP levels. Chronic infection was accompanied by decreased levels of low charged and highly sialylated Muc2. Additionally, we demonstrated that the excretory secretory products released by the nematode consist of serine proteases capable of depolymerising the Muc2 mucin network, which may be part of the nematodes regime to improve its niche and/or aid movement through the mucus layer. Overall, this resulted in a porous mucus layer and a favourable environment for the parasite.Data is presented to show that the intestinal mucus barrier and its constituent mucins are an integral part of the co-ordinated expulsion mechanisms that occur in animals resistant to T.muris infection and we identify a mechanism whereby the nematode exerts its effects on the mucin environment to promote its survival within the host.

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