Coral diseases have become more prevalent and destructive over the past 20 years, possibly due to an increase in stressful environmental factors that may weaken corals defenses against disease. Aspergillosis is a disease caused by the fungus Aspergillus sydowii, which apparently infects only two species of gorgonian corals in the Caribbean Ocean (Gorgonia ventalina and G. flabellum). We hypothesized that the differential resistance to infection is caused by differences in chemical defenses among gorgonians. Freeze-dried gorgonian powders and extracts deterred fungal growth, but potencies varied among gorgonian species and among fungi. Extracts and powders generated from G. ventalina all strongly inhibited fungal growth. Since G. ventalina was predicted to have weak antifungal chemical defenses compared to gorgonians not known to suffer from aspergillosis, we concluded that gorgonian susceptibility to fungal infection is determined by factors other than, or in addition to, chemical defenses. In order to investigate specific gorgonian antifungal strategies, we attempted to use bioassay-guided fractionation to isolate antifungal compounds from four gorgonians: Gorgonia ventalina, Briareum asbestinum, Eunicea succinea, and Pseudopterogorgia americana. We succeeded in isolating two antifungal compounds, diastereomers of 9,11-seco-24-hydroxydinosterol, from the gorgonian Pseudopterogorgia americana. This compound was previously identified by other groups, but this study is the first to establish its antifungal activity. At natural concentration, one diastereomer of 9,11-seco-24-hydroxydinosterol inhibited the growth of three different fungi, suggesting that at least this diastereomer may possess broad-spectrum antifungal activity. The results from our survey of gorgonian chemical defenses indicate that susceptibility to aspergillosis cannot be explained by chemical growth inhibition alone. Further areas of investigation include induction of gorgonian chemical defenses, examination of growth-inhibiting mechanisms of antifungal metabolites, and identification of non-chemical factors affecting gorgonians vulnerability to fungal infection.

No description available.

Major transitions between vertebrate and insect pollination systems have occurred many times during the angiosperm radiation and are associated with evolutionary modifications in floral traits. In the large ancestrally bird-pollinated African genus Protea (Proteaceae), an evolutionary shift from bird to insect pollination in the genus is suggested by the fruity diurnal scent of flowers in a recently evolved clade of grassland species. In this study, I confirm that four of these grassland Protea species have mixed mating systems and are indeed insect pollinated, and furthermore demonstrate the functional significance of their floral presentation and scent chemistry for attraction of pollinators, specifically cetoniine beetles. The study species, Protea caffra, Protea dracomontana, Protea simplex and Protea welwitschii, have colourful bowl-shaped inflorescences that produce copious amounts of pollen and dilute, xylose-rich nectar. Cetoniine beetles were found to be the most suitable pollinators due to their abundance, size, relatively pure Protea pollen loads, and their preference for the fruity scent and low growth form of these scented Protea species, as demonstrated by choice experiments in which inflorescences were offered at either end of a y-maze or at various heights above the ground, respectively. Bagging and hand pollinations revealed that these Protea species are self-compatible and capable of autonomous selfing. Self progeny of P. caffra were as vigorous as cross progeny in terms of germinability and survivorship to two months. Vertebrate-excluded and open-pollinated inflorescences yielded similar seed numbers for all species. Supplemental hand-pollinations, however, failed to increase seed set substantially, an indication of resource limitation. Outcrossing rates estimated using polymorphisms at eight allozyme loci in progeny from vertebrate-excluded and open-pollinated treatments of P. caffra were no different (t=0.59), indicating outcrossing by insects and an equal or insubstantial contribution from bird pollinators. The fruity-sweet scents of these species were more complex, with higher whole flower and mass-specific emission rates, than those in eight bird-pollinated congenerics. The overall floral scent is shown to be a blend of emissions from various plant parts, especially nectar. Electroantennography (EAG) revealed that the generalist pollinator Atrichelaphinis tigrina responds to a variety of volatile compounds found in fruity Protea scents. Field trapping confirmed that this cetoniine beetle is strongly attracted to ß-linalool (up to 60% of scent profile) and methyl benzoate. In conclusion, this study demonstrates the evolution of beetle pollination and mixed mating systems in a grassland clade of Protea. Volatile compounds that make up the unique (within Protea) fruity scent of the study species are shown to attract beetles, and the emission of large amounts of these compounds was probably a key step in the transition from bird to insect pollination in Protea. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Wheat bulb fly (WBF) (Delia coarctata, Fallén, Diptera: Anthomyiidae) is a pest of commercial importance in cereal crops. Control is dependent on organophosphates some of which are restricted in the UK, while current oviposition monitoring techniques are labour intensive and subjective. Eggs are not laid in association with a host-plant, therefore, prompt location of a suitable host is critical to the survival of the newly hatched larvae. Wheat bulb fly larvae have been shown to exhibit a positive chemotactic response to wheat and other host-plant seedlings and their root exudates. The objective of this study was to improve the control and population monitoring methodology associated with WBF, by investigating the ecology and specifically the chemical ecology of the WBF. Bioassays were used to investigate the behavioural response of WBF to known chemical constituents of host-plant exudates. Four secondary metabolites were found to be attractive while CO2 was found to alter the behaviour of larvae. Wheat bulb fly oviposition was assessed in field situations to describe egg laying spatially and through time. Geostatistical and ecological techniques were used to observe the spatial dependence and dispersion of oviposition and construct contour maps or scale-sized dot graphs of oviposition density. The traditional single line transect sampling pattern was compared against a more intensive sampling regime. Oviposition monitoring was conducted over a three year period to ascertain the time of peak egg density of this fly. A molecular based diagnostic test to assess WBF egg populations for damage forecasting was developed. A real time polymerase chain reaction (PCR) protocol was produced to estimate field populations of WBF eggs through the quantification of eggs from field samples. In addition endpoint PCR was used to identify the presence or absence of eggs from samples. This study gives the potential to advance current control methodology by providing the basis for the development of a lure and kill or confusion/disruption strategy, while offering a more accurate sampling system and a molecular diagnostic test, for improvement of the management of WBF.

Alarm substances, released by injured prey, and odours from predators, such as northern pike, are chemical cues associated with increased predation risk in aquatic ecosystems. In laboratory studies, individual prey can respond to the presence of such cues by reducing conspicuous behaviours, such as foraging and by seeking shelter. These responses may reduce growth and reproduction, which could have effects at the population-level. The objective of my study was to determine if alarm substances or pike odour have population-level effects on fathead minnow. In the cattle trough experiment, alarm substances and pike odour had no effect on breeding behaviour and recruitment of young; however, spawning occurred earlier with exposure to alarm substances relative to water controls. In a larger-scale pond experiment, alarm substances had no effect on reproduction or recruitment. Despite individual-level effects in the laboratory, exposure to alarm substances and pike odour had no impact at the population scale. / Ecology

Thesis (Ph.D.)--Victoria University of Wellington, 2008. / Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 1998. / Vita. Includes bibliographical references (p. 169-179).

Thesis (M.S.)--San Jose State University, 1997. / Includes abstract. Includes bibliographical references (leaves 112-122).

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-05-15T19:21:30Z No. of bitstreams: 1 TeseMAT.pdf: 10785085 bytes, checksum: 69ccc2d94ef0cf944d85e6cf91c78d59 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-12T19:55:52Z (GMT) No. of bitstreams: 1 TeseMAT.pdf: 10785085 bytes, checksum: 69ccc2d94ef0cf944d85e6cf91c78d59 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-06-12T19:55:59Z (GMT) No. of bitstreams: 1 TeseMAT.pdf: 10785085 bytes, checksum: 69ccc2d94ef0cf944d85e6cf91c78d59 (MD5) / Made available in DSpace on 2017-06-12T20:03:06Z (GMT). No. of bitstreams: 1 TeseMAT.pdf: 10785085 bytes, checksum: 69ccc2d94ef0cf944d85e6cf91c78d59 (MD5) Previous issue date: 2016-02-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Alternanthera brasiliana is a plant widely used by Brazilian people as a folk medicine for the treatment of numerous diseases, especially due to its antibiotic properties. Using dereplication strategies, we identified antibiotic compounds as modified fatty acids, which are closely related to oxylipins. The biosynthesis of these compounds could be related with the presence of endophytic bacteria. Thus, we established axenic cultures of A. brasiliana and developed methods for detection and quantification of bacterial cells in plant tissues. We also performed initial re-inoculation experiments with endophytic bacteria isolated from A. brasiliana. In addition, method for quantification of phytohormones and oxylipins in plant tissues were developed. The results reinforced the correlation between both the amount of bacteria and oxylipins in A. brasiliana tissues. / Alternanthera brasiliana é uma planta amplamente utilizada na medicina popular brasileira para o tratamento de diversas doenças, principalmente devido a suas propriedades antibióticas. Durante este trabalho, utilizou-se estratégias de desreplicação a fim de se identificar os compostos antibióticos presentes nesta planta. Esses compostos foram identificados como ácidos graxos oxidados pertencentes a classe das oxilipinas. A biossíntese destes compostos esta comumente relacionada a situações de estresse biótico e abiótico em plantas. Dessa forma, nos estabelecemos métodos para a detecção e quantificação de células bacterianas em tecidos vegetais. Também foram realizados experimentos iniciais de re-inoculação de bactérias endofíticas isoladas de A. brasiliana. Além disso, foram desenvolvidos métodos para a quantificação de fitohormônios e oxilipinas em tecidos vegetais. Os resultados obtidos até o momento ressaltam a possibilidade de bactérias endofíticas influenciarem a produção de oxilipinas (compostos antibióticos) na planta A. brasiliana.. / FAPESP: 2007/03771-7 / FAPESP: 2008/07494-0 / FAPESP: 2010/17925-9 / FAPESP: 2012/20932-2

As formigas da tribo Attini são obrigatoriamente dependentes da simbiose que mantêm com fungos cultivados no interior de suas colônias.N as Attini mais derivadas (gêneros Atta e Acromyrmex)esse fungo é cultivado com substratos vegetais frescos cortados pelas formigas, constituindo a única fonte de nutrientes durante os estágios imaturos (larvas e pupas) e fonte parcial de nutrientes durante a fase adulta. N esta fase, as formigas obtêm grande parte de seus nutrientes através da ingestão de seivas foliares durante o corte e o processamento do materiala ser incorporado ao fungo.Assim,dado o duplo destino que os produtos vegetais têm nessa relação simbiótica entre fungos e formigas, os metabólitos secundários contidos nas plantas cortadas pelas formigas são também capazes de atuar nessas duas instâncias.D entre os metabólitos secundários, os glucosinolatos são conhecidos por intermediarem muitas das interações das plantas que os contêm e por possuírem um mecanismo de ação envolvendo a hidrólise pela enzima mirosinase. O presente estudo avaliou os efeitos da sinigrina sobre o crescimento radialdo fungo mutualista de Atta sexdens e sobre a mortalidade das operárias isoladas das colônias.Para isso os fungos foram cultivados in vitro em meio de cultura M EA-LP contendo sinigrina e incubados a 25° C em BO D .A mortalidade dos insetos foi avaliada de duas maneiras:com o oferecimento sinigrina em dietas sólidas ou em solução aquosa.O s resultados mostraram que a sinigrina intacta não apresentou efeitos sobre qualquer um dos dois. Porém, apresentou indícios de que os produtos de hidrólise podem vir a inibir o crescimento do fungo. Também foram analisadas as composições de glucosinolatos em plântulas de 6 variedades de B. oleraceae utilizando-se Cromatagrafia Líquida de Alta Eficiência com detecção em U V (CLAE) e em espectrômetro de massas (CLAE/M S).Dez glucosinolatos foram encontrados,dentre os quais glucoiberina, sinigrina e progoitrina foram os mais abundantes. O s resultados também apontaram que, apesar de se tratarem da mesma espécie, o conteúdo de glucosinolatos é bastante distinto entre as variedades. Entretanto, as amostras da mesma variedade mostraram um padrão relativamente bem estável, apresentando sempre os mesmos glucosinolatos em proporções relativas semelhantes. / vide dissertação