A new procedure has been developed to concentrate the phosphofructokinase from muscle of Ascaris suum with minimum loss of activity. By utilizing this method, 50 ml fraction was concentrated to a final volume of 3 ml in about 1.5 h without loss in enzyme activity. The concentrated enzyme had a specific activity of 64 units per mg. Ascaris muscle-cuticle was incubated in 50 1M solutions of either acetylcholine, serotonin, y-aminobutyric acid, levamisole, or saline alone. Phosphate analysis of the isolated phosphofructokinase from each incubation revealed that the enzyme contained the following moles of phosphate per subunit: 2.9 (acetylcholine), 2.2 (serotonin), 2.0 (y-aminobutyric acid), 1.5 (levamisole), and 3.4 (salne alone). The present study did not establish a direct correlation between degree of phosphorylation and phosphofructokinase activity. Phosphofructokinase from muscle of Ascaris suum appears to contain several phosphorylation sites, and one of these sites is required to be phosphorylated in order for the enzyme to exhibit maximum activity under physiological conditions.

Teladorsagia circumcincta is a common parasitic nematode of the sheep abomasum, causing reduced growth in young lambs. The widespread development of anthelmintic resistant parasites has driven the need for alternative control strategies. Resistant immunity is acquired through repeated exposure to the parasite. The immune response and clinical outcome vary greatly between animals, but resistance is heritable. The aims of this project were: 1) understand how sheep respond to nematode infection; 2) understand and identify genes associated with the response; 3) identify variation within those genes which may contribute to resistance. Using an artificially infected animal model, transcriptomic analysis in resistant and susceptible lambs identified genes involved in T helper cell polarization as integral to disease outcome. T helper cell (Th)1 and Th17 activation was associated with susceptibility (low antibody, high worm numbers) while a Th2 response was associated with resistance (high antibody levels and clearance of infection). The Th cell transcription factors (GATA3, TBX21, RORC2 and RORA) were sequenced with splice variants and SNPs identified. Analysis of gene expression in the abomasal lymph node identified RORAv2 as associated with susceptibility and RORAv5 as associated with resistance. In the abomasal mucosa, GATA3 expression was linked to resistance. Expression analysis of cytokine receptors expressed by Th cells identified IL17RB and IL17RBv2 as associated with resistance in the abomasal mucosa. Analysis of the SNPs within these genes in 3 naturally infected populations identified a significant association between SNPs in IL23R with weight and FEC. This project has provided an in-depth analysis of the ovine transcriptome and identified several genes associated with the development of resistance to nematodes.

Population dynamics of potato cyst nematodes Globodera rostochiensis (Woll.) Skarbilovich and G. pallida (Stone) and their interactions with potato plants are not sufficiently described to explain changes in population dynamics and yield reduction among seasons and locations. This thesis describes experiments to clarify the mechanisms of PCN population increase and associated damage to potato primarily in relation to temperature. The research was undertaken in controlled environments and in the field to examine the impact of temperature and mixed populations on the life cycle and population dynamics of potato cyst nematodes. The data will be used to develop a model that relates the PCN life cycle with temperature. Soil temperature data were also obtained from different UK locations within potato drills during the growing season to provide a context for the model. Results from this thesis indicate that both species of PCN, Globodera rostochiensis and G. pallida, are likely to increase more rapidly and in greater numbers with susceptible cultivars if soil temperatures increase in the future and regions of the UK with relatively higher soil temperatures are more likely to have higher and faster population multiplication of PCN.

Orientador: Ricardo Velludo Gomes de Soutello Soutello / Resumo: Os parasitos influenciam de maneira significativa a bovinocultura no Brasil, sendo a aplicação de endectocidas da família das lactonas macrocíclicas umas das formas mais utilizadas para o controle, porém podem proporcionar contaminação ao ambiente, visto que sua eliminação é principalmente via fezes e urina. Com isto, este trabalho objetivou verificar o desenvolvimento de microrganismos edáficos e a decomposição das fezes de bovinos ao longo do tempo após o tratamento com diferentes lactonas macrocíclicas. Foram avaliadas as fezes de doze animais, divididos em quatro grupos homogêneos, sendo o G1- controle (sem a administração de endectocida), G2-Ivermectina 1%, G3-Ivermectina 3,15% e G4- Moxidectina 1%. As colheitas das fezes dos animais foram realizadas nos dias 0, 7, 14, 21, 28,42 e 56 pós tratamento, e submetidas a três ambientes de decomposição, sendo ambiente controlado (BOD), Natural (NAT): exposto as condições climáticas naturais e enterradas no solo (Solo). Nos dias das cada colheitas e 112 dias após cada colheita, foi realizada a avaliação matéria orgânica. As avaliações da microbiota das fezes foram realizadas nos dias das colheitas e 7 após cada colheita. Observou-se que as ivermectinas em suas duas concentrações (1 e 3,15%) interferiram no desenvolvimento da população microbiana, já a moxidectina 1% não alterou a dinâmica populacional das bactérias, que também não foi influenciada pelo ambiente exposto em nenhum dos tratamento. A decomposição não foi afetada pela... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Thesis (M. Sc. (Biochemistry)) -- University of Limpopo, 2003 / Refer to document / National Research Foundation (NRF)

Orientador: Pedro Luiz Martins Soares / Coorientador: Kátia Cristina Kupper / Resumo: O Brasil, segundo maior produtor e também maior exportador de soja, tem grande parte da produção comprometida devido aos danos causados por nematoides. Para tanto, vários estudos têm relatado a eficiência de bactérias promotoras de crescimento no controle de nematoides nas mais diversas culturas. Diante do exposto, o objetivo desse trabalho foi selecionar isolados de três espécies de Bacillus eficientes no controle dos nematoides, Heterodera glycines, Meloidogyne incognita e M. javanica, e também, na promoção de crescimento da soja, sob diferentes formas de aplicação. Foram testados 19 isolados de Bacillus subtilis, B. velezensis (syn. B. amyloliquefaciens) e B. methylotrophicus, aplicados via Tratamento de sementes (TS) e Sulco de semeadura (SS), mais testemunhas (com e sem nematoides) e comercias [Bacillus subtilis UFPEDA 764 (TS); B. subtilis UFPEDA 764 (SS); Abamectina (TS); Cadusafós (SS)]. Avaliou-se a emergência das plântulas, altura da planta, massa fresca e seca das partes aéreas, massa fresca das raízes, número de vagens, índice de clorofila, nematoide total, nematoide por grama de raízes e fator de reprodução. Devido a existência de uma estrutura de dependência contida nas variáveis originais, realizou-se análise exploratória dos dados, via Análise de Componentes Principais (ACP), as variáveis independentes foram testadas via análise de Modelo Linear Geral (GLM). Os resultados mostraram que para as três espécies de nematoides, o método de aplicação via SS favoreceu... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

No description available.

Bibliography: leaves 363-381.

Meiofauna are an ecologically significant component of marine benthic communities worldwide. Nematodes, in particular, are arguably the most abundant metazoans on Earth and often form highly diverse communities in marine sediments. The study of meiofauna, however, often lags behind that of macrofauna, probably due to the small size of meiofaunal organisms and the paucity of suitably-trained taxonomists or para-taxonomists. Our understanding of basic ecological questions, such as the role of meiofauna in the energetics of benthic communities, as well as the nature and extent of possible relationships between meiofauna and macrofauna in detritus-based communities, is still limited. The present study aimed to address these questions in the context of intertidal seagrass (Zostera muelleri) meadows and adjoining unvegetated sediments in Papanui Inlet, Otago Peninsula. The near absence of taxonomical and ecological studies on free-living marine nematode species in New Zealand also prompted the description of several new species and as well as a comparison of species assemblages from the study sites. Meiofaunal abundance (range: 1325-4979 ind. 10cm�) in the top 5cm of sediments was not significantly different inside and outside the seagrass meadow. Meiofaunal biomass and production estimates were small relative to macrofauna (approx. 1 and 5% of macrofaunal values, respectively), with little variation in both meiofaunal and macrofaunal values between vegetated and unvegetated habitats. Analysis of the isotopic and fatty acid composition of primary producers, sediment organic matter, and consumers at the study sites suggest that a significant proportion of secondary productivity in seagrass meadows is fuelled by macrophyte detritus. These data suggest that secondary productivity in the seagrass meadow was limited by the low palatability of macrophyte detritus compared with microalgal food sources, resulting in lower trophic transfer efficiency in vegetated sediments. These results contrast with previous findings showing a large contribution of meiofauna to the secondary productivity of vegetated sediments, as well as greater secondary productivity inside than outside seagrass meadows. The nature of the sediments (coarse particle size with low organic matter content) is likely to have led to low meiofauna biomass whilst favouring large suspension feeders. The low availability of high quality food sources (i.e. seston, benthic microalgae, and epiphytes) in vegetated sediments may have contributed to the lower than expected secondary productivity inside the seagrass meadow. Most of the dominant nematode species found at the study sites were new to science, and 6 new species were described. Significant differences were found in the nematode assemblages between sites and sediment depths. There was a trend of greater nematode diversity and abundance in vegetated sediments, but this was restricted to the uppermost 2cm of sediments. The effect of seagrass on nematode assemblages is likely to be mediated by the effect of blades on sediment characteristics and the presence of roots. The present study suggests that the presence of Zostera muelleri results in greater biodiversity of sheltered soft-shore communities on a local scale. The addition of ��C-labelled macroalgal detritus (Enteromorpha) to microcosms in a feeding experiment resulted in minimal labelling of harpacticoid copepods and nematodes. Lack of change in the fatty acid composition of the latter also suggests limited assimilation of detritus during the experiment. It is likely that consumers choose benthic microalgae over detritus when both food sources are available in the field. High content of highly unsaturated fatty acids (HUFAs) in nematodes from the field suggests, for the first time, that they are a high quality food source to higher trophic levels. A feeding experiment investigating the effect of bacterivorous nematodes on detritus assimilation rates by amphipods did not support the hypothesis that nematodes increase the trophic transfer efficiency between detritus and macrofaunal detritivores. It is unclear whether amphipods preferentially fed on detritus or whether nematodes escaped predation by burrowing deeper in the sediment. Data obtained in the present study, however, shows that marine bacterivorous nematodes can biosynthesise/accumulate HUFAs in high concentrations despite their low concentrations in their diet. Nematodes could, therefore, provide an important source of these essential nutrients to bulk deposit feeders living in otherwise HUFA-poor sediments.

Bibliography: leaves 363-381. / ix, 381 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences, 2002