Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-05-20T18:06:29Z No. of bitstreams: 0 / Made available in DSpace on 2015-05-20T18:06:29Z (GMT). No. of bitstreams: 0 / Neste estudo foi proposto um modelo de formação de biofilme fúngico formado por Candida albicans em dois diferentes substratos associado ou não à glicose para o estudo dos efeitos da terapia fotodinâmica (PDT) utilizando o azul de metileno (AM) como fotossensibilizador, avaliando os efeitos de dois comprimentos de onda distintos incluindo a investigação na captação do AM quando sensibilizados previamente com a glicose. Foi avaliada a susceptibilidade da levedura em suspensão de células crescidas por 24 h (início da fase estacionária) com e sem a adição prévia da glicose. Foram investigadas duas linhagens de C. albicans para a padronização do biofilme, ATCC 90028 e ATCC 10231. Com os biofilmes formados, avaliamos a captação de AM para determinarmos a mais eficiente concentração e tempo de pré-irradiação (PIT). Por último, avaliamos sua sensibilidade à PDT em dois comprimentos de onda distintos (λ = 645 nm e λ = 660 nm) em função do tempo de irradiação (potência = 16 mW, taxa de fluência = 127,3 mW/cm2). A linhagem de célula que possibilitou a formação de biofilme foi a ATCC 10231 em discos de hidrogel. A menor concentração que possibilitou uma melhor captação do AM foi de 500 μM com um PIT de 30 min e em contato prévio com a glicose 50 mM por 90 min. O comprimento de onda mais eficiente, que promoveu redução em leveduras e biofilmes foi o de λ = 660 nm, reduzindo melhor no estudo de leveduras quando sensibilizados com glicose. Nos biofilmes, a redução foi iniciada mais precocemente sem a adição de glicose (com 6 min de irradiação e fluência = 46 J/cm2), porém, em 12 min (fluência = 92 J/cm2) o grupo com glicose passou a ter maior eficiência. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted in partial fulfillment for the Degree of Master of Technology: Biotechnology, M. L. Sultan Technikon, 2002. / Fusarium species produce toxic mycotoxins that are known to exert adverse health effects in humans and animals. No attempts have been made to establish mycotoxin-producing capabilities of isolates of Fusarium species from bananas exhibiting symptoms of crown rot. Crown rot is one of the most serious post harvest problems in banana and the disease is caused by different fungal species, principally Fusarium species. Banana, which is of great economic significance in growing countries (i.e. Costa Rica, Cameroon, Ecuador) is seriously affected by crown rot and is a major cause of fruit loss / M

Diagnostic medical mycology has been slow to advance due to a lack of species specific antigens in organisms which cause serious diseases in man. Toward this end, an HPLC analysis was done of the following fungal antigens: histoplasmins HKC-43 and H-42, blastomycin KCB-26, an alkali-soluble, water soluble antigen from Blastomyces dermatitidis (b-ASWS), a coccidioidin prepared from a toluene lysate of the mycelial-arthroconidia phase of Coccidioides immitis, and an alkali-soluble, water-soluble antigen from Coccidioides immitis (c-ASWS). The HPLC survey included size-exclusion chromatography (SEC), ion exchange chromatography (HPIEC), and reversephase chromatography (RP). Resolution was poor with both SEC and HPIEC but was excellent with RP chromatography. The use of RP will allow sufficient separation for further antigenic and structural analysis.

The fungus Diplodia maydis, (synonym Stenocarpella maydis (Berk)) is worldwide one of the most important cob rot pathogens of maize. The isolation of stenocarpin, a metabolite toxic to ducklings, from maize cultures of D. maydis as the 4,6-0-diacetate derivative and its structure elucidation has been reported in the literature. Detailed NMR studies established the structure as either (3S,4R,6R,7R)- or (3R,4R,6R,7R)-spiro[(4,6, 7-trihydroxy-7-methyl-8-oxo-5,6,7,8-tetrahydroisochromane)-3 ,2' -tetrahydrofuran]. The absolute configuration of the C(3) spiroacetal stereogenic center remained unknown. The aim of the synthetic studies described in this dissertation was to develop a synthetic methodology for the spiroacetal moiety present in stenocarpin in order to establish unambiguously the C(3) absolute configuration. Retrosynthetic analysis of stenocarpin identified two model compounds (5S,lOR)- and (5R,lOR)-1,6-dioxaspiro[4.5]dec-8-en-10-o1 as the synthetic target. In turn the retrosynthetic analysis of these model compounds led to commercially available L-arabinose as starting material. Two strategies, which differ in the timing for the formation of the spiroacetal moiety as well as the initial type of protecting groups, were employed in the development of the synthetic route. In the first route the spirocyclisation reaction of a benzyl protected intermediate followed by the syn elimination of the cis-diol group resulted in the formation of only the (5S, lOR) model compound. The use of the acetonide and TBDPS protecting groups from the outset of the synthetic route and once again a spirocyclisation reaction, led to the formation of two spiro compounds epimeric at the C(5) spiro stereogenic centre, which could be separated and transformed by a syn elimination of the cis-diol group to the two model compounds. The configuration of the spiroacetal intermediates formed in the two synthetic routes and the changes in conformation that occurred in each of the steps were deduced from extensive NMR studies and especially the NOE technique. The results established the 3S configuration for stenocarpin and provided a viable synthesis for the (5S,lOR)-l,6-dioxaspiro[4.5]dec-8-en-1O-ol model compound that is to be used in the total synthesis of stenocarpin. In the dissertation the results of the first steps in a total synthesis, a study on the epoxidation of the double bond, is presented. / Dissertation (MSc (Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

Please read the abstract in the section 07back of this document / Dissertation (MSc (Plant Pathology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Please read the abstract (Summary) in the section 00front of this document / Dissertation (MSc (Botany))--University of Pretoria, 2007. / Plant Science / MSc / Unrestricted

The South African commercial forest industry is almost exclusively reliant on plantations of exotic trees, of which Eucalyptus spp. make up almost 50 %. Botryosphaeria spp. are important canker pathogens in these Eucalyptus plantations in South Africa. However, exotic plantations and their pathogens cannot be viewed separately from the related native flora. This study showed the importance of extending our knowledge on pathogens that occur on related native and exotic hosts, and which can pose a threat by cross infection between these host groups. In Chapter 1, a review of the literature concerning Botryosphaeria spp. that occur on Eucalyptus in its native range and exotic plantations is presented. It is clearly shown that Botryosphaeria spp. are important pathogens on Eucalyptus in exotic plantations worldwide, causing various symptoms on this host. Botryosphaeria spp. are also important canker pathogens in Eucalyptus plantations in South Africa. Traditional identification of this group of fungi, based on morphological characteristics, led to much confusion about their identity. However, in recent studies morphological characteristics were combined with DNA sequence data to distinguish and identify these fungi. Based on these data a few revisions have been done and new Botryosphaeria spp. were described on Eucalyptus. Botryosphaeria spp. recognised as pathogens on Eucalyptus in South Africa include B. dothidea, B. parva and B. eucalyptorum. Future studies should be focused on correct identification of Botryosphaeria spp. that occur on Eucalyptus, which is the first step towards preventing the spread of this group of pathogens and developing management strategies to control disease outbreaks. During the study on Botryosphaeria spp. on Syzygium cordatum, isolates of two Botryosphaeria spp. appeared to be undescribed. One of the undescribed species was represented by only one isolate and it was not named. The other species was described as the new Botryosphaeria anamorph within Lasiodiplodia, namely L. gonubiensis. This species grows endophytically on native S. cordatum in South Africa and is the first species in Lasiodiplodia to be found on native trees in the country. Identification of the new species was based on conidial and cultural morphology and DNA sequence data of the rDNA internal transcribed spacers, ITS1 and ITS2. Identification and description of L. gonubiensis is presented and discussed in Chapter 2. In total nine Botryosphaeria spp. were isolated from native Syzygium cordatum in South Africa. These include B. parva, B. ribis, B. lutea, B. australis, B. rhodina, B. dothidea, Fusicoccum mangiferum, Lasiodiplodia gonubiensis and an unknown Botryosphaeria sp. The isolates related to B. ribis, B. parva and F. mangiferum were the most abundant, while only one isolate represented B. dothidea. Species were identified based on morphological characteristics of their anamorphs combined with ITS rDNA sequence data. Some species, such as B. parva and B. ribis, could not be distinguished based on morphology or ITS rDNA data. A PCR-RFLP fingerprinting technique was, therefore, used to distinguish isolates of these two species. Once again this technique has proven useful and reliable in identification of Botryosphaeria isolates, including cryptic species. However, isolates of closely related B. lutea and B. australis could not be distinguished using this technique. It could be of interest to develop PCR-RFLP identification system that could be used in identification of the latter species. Identification and characterization of Botryosphaeria spp. are presented in Chapter 3. Isolates of all Botryosphaeria spp., obtained from native Syzygium cordatum in this study, caused lesions on the stems of Eucalyptus camaldulensis and S. cordatum in trials conducted under greenhouse conditions. Except for Fusicoccum mangiferum, all the other Botryosphaeria spp. were more pathogenic on Eucalyptus than on S. cordatum. The most pathogenic species on Eucalyptus were B. rhodina, B. ribis and B. lutea, whileF. mangiferum and B. ribis were the most pathogenic on S. cordatum. Botryosphaeria dothidea and L. gonubiensis were the least pathogenic on both hosts. The results obtained from this trial clearly show that Botryosphaeria spp. on S. cordatum pose a potential threat to exotic Eucalyptus plantations. Future study should be conducted under field conditions to evaluate data obtained in greenhouse trials. These results were presented and discussed in Chapter 4. The results presented in this study provide the first detailed information on Botryosphaeria spp. on the native Myrtaceae in South Africa. Most of the species isolated from Syzygium cordatum are not known on Eucalyptus in the country. All of the Botryosphaeria spp. obtained in this study are pathogenic to Eucalyptus, and thus pose a threat to this host. Large number of B. ribis, B. parva and F. mangiferum isolates obtained from the native S. cordatum could imply their origin in this region. Further sampling is needed on myrtaceous trees native to the Southern African region, as well as on Eucalyptus. Population studies on the most abundant and most pathogenic Botryosphaeria spp., should provide more information on the movement and origin of these pathogens. The results from this study also highlights the need for quarantine measures to avoid the introduction of new Botryosphaeria spp. or new strains that can be more pathogenic to either native or cultivated plants. Please cite as follows Pavlic, D 2004, Botryosphaeria species on native South African Syzygium cordatum and their potential threat to Eucalyptus , MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-02062006-112938/ > / Dissertation (MSc)--University of Pretoria, 2007. / Microbiology and Plant Pathology / MSc / Unrestricted

Common barley diseases observed in North Dakota include net blotch, spot blotch, leaf and stripe rust, bacterial leaf streak, and Fusarium head blight. The first objective of this research was to determine the effect of variety and fungicide timing on disease development of barley under conventionally tilled systems. Five field trials were performed in 2016-2017 to test the effect of common varieties and fungicide applications on foliar disease of barley. Overall, varietal selection had a greater effect on the level of foliar disease observed than fungicide application. The second objective focused on the efficacy and timing of adepidyn and prothioconazole + tebuconazole on Fusarium head blight. An inoculated greenhouse experiment was performed the fall of 2017 to determine the effectiveness of fungicide timing at half-spike, full-spike, and five days after full-spike. The protectant capabilities of the fungicides were greater than their curative properties.

Leaf diseases are an integral part of banana production. While currently not a cause for major concern in South Africa, many of these diseases van reach epidemic proportions and cause severe crop loss. To determine the present status of leaf diseases in South Africa, a survey was conducted in the five banana-growing regions of the country. The study indicated the following: Yello Sigatoka, caused by Mycosphaerella musicola was the most prevalent disease and occurred in all five the regions. Mycosphaerella speckle and Cordana leaf spot, caused by M. musae and Cornana musae respectively, were present in four regions. Cladosporium speckle, caused by Cladosporium musae, was found only in the Levubu area. Various other fungi, mainly saprobes and endophytes, were also isolated. The most commonly encountered species included Alternaria alternate, Colletrichum gloeosporioides, Nigrospora oryzae, N. sacchari, N. Spaerica, Pestalotiopsis sp., Phoma glomerata, Selenophoma asterina and S. juncea. Following morphological identification of the pathogenic species, monoconidial isolates were established from representative isolates of each and their virulence confirmed in artificial inoculation studies. The identity of M. musciola and Cladosporium musae was verified molecularly by means of species-specific primers and/or sequencing of the ITS region. Validation of the identity of Cladosporium musae constitutes the first report of Cladosporium speckle on banana in South Africa. Sequence data of the ITS region of isolates from Mycospaerella speckle lesions indicated that the symptoms are caused by two species, M. musae and one closely related to M. colombiensis, the latter previously described only from lesions on leaves of Eucalyptus urophylla in Colombia. / Dissertation (MSc (Microbiology))--University of Pretoria, 2002. / Microbiology and Plant Pathology / unrestricted

No description available.