We studied the host specificity, interactions with plant immune systems, and virulence factors of the phytopathogenic Type III secretion system-carrying bacterium Pseudomonas syringae. In studying host specificity, we ran growth and pod assays using seventeen pathovars of P. syringae on kidney bean hosts. We tracked bacterial growth numbers over six days and compared pathovar growth patterns. To study immune interactions with host plants, we performed effector-triggered immunity induction and suppression assays with individual effectors in Arabidopsis thaliana to determine whether effector evolutionary age was related to resultant plant immune responses. No correlations were observed. To generate candidate virulence effectors, we sequenced mRNA from seven P. syringae pathovars grown in inducing media and pulled out hits to virulence-related genes.

We studied the host specificity, interactions with plant immune systems, and virulence factors of the phytopathogenic Type III secretion system-carrying bacterium Pseudomonas syringae. In studying host specificity, we ran growth and pod assays using seventeen pathovars of P. syringae on kidney bean hosts. We tracked bacterial growth numbers over six days and compared pathovar growth patterns. To study immune interactions with host plants, we performed effector-triggered immunity induction and suppression assays with individual effectors in Arabidopsis thaliana to determine whether effector evolutionary age was related to resultant plant immune responses. No correlations were observed. To generate candidate virulence effectors, we sequenced mRNA from seven P. syringae pathovars grown in inducing media and pulled out hits to virulence-related genes.

Orientador: Daniel Júnior de Andrade / Resumo: O ácaro-da-ferrugem-dos-citros Phyllocoptruta oleivora é uma das principais pragas dos citros no Brasil. Os problemas atribuídos a P. oleivora têm se intensificado e suspeita-se que os danos estejam relacionados a uma nova espécie de eriofiídeo descrita recentemente, o ácaro-marrom-dos-citros Tegolophus brunneus. No entanto, não há estudos com essa espécie e informações sobre sua distribuição, características bioecológicas, danos, suscetibilidade a acaricidas e inimigos naturais associados são ausentes. O objetivo principal do projeto foi estudar a distribuição de T. brunneus na principal região citrícola brasileira e sobre as principais espécies e variedades cítricas. Além disso, estudou-se a biologia de T. brunneus em laboratório, determinou-se a suscetibilidade desse ácaro aos principais acaricidas, caracterizando seus danos em plantas cítricas, bem como o potencial de predação das principais espécies de predadores associadas ao ácaro e seu potencial para o uso no controle biológico. As coletas realizadas em vários municípios do estado São Paulo e Triângulo Mineiro demonstraram que T. brunneus infestou apenas lima ácida ‘Tahiti’, enquanto P. oleivora infestou todas as outras espécies e variedades cítricas. O ácaro completa o desenvolvimento em 7 dias, com período de incubação de 3 dias, duração de larva de 2,1 dias e de ninfa 2,8 dias e as fêmeas apresentam fecundidade de 8,5 ovos a 25°C. Os danos da espécie caracterizam-se pelo prateamento dos frutos e formação de manchas... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Dicyemid mesozoans are endoparasites inhabited in benthic cephalopod molluscs. Previous studies of dicyemids were mostly concentrated on their taxonomy. The life cycle remains a mystery since Cavolini observed this animal in 1787. The purpose of this study is to investigate further on the dicyemid life cycle building on the limited knowledge from previous studies, and investigate the infection of dicyemid in octopuses in tropical waters, using the area in the southwestern Taiwan as a model. A total of 324 octopus hosts was collected¡Aincluding 3 genera and 13 species from DungGang Fish Market from 2001 to 2002. There were 9 host species detected with dicyemid mesozoans including 14 species within 2 genera. Moreover, there is no dicyemid species overlap among the octopus species indicating high host-specificity. There is large range of the dicyemid infection prevalence among octopod hosts. Cistopis indicus has the highest prevalence (91%) and Octopus luteus the lowest (20%) in this study. In C. indicus, the infected mechanism correlated with season. The infusoriform larvae of dicyemid mesozoan dispersal from the host to sea water in the autumn and winter, then entering host in the spring and summer. The change of dicyemid life cycle stage in the C. indicus kidney correlates with the sharp decrease of infection intensity. However, the dicyemid infection in Octopus marginatus correlates with body size, not with season. Besides, there is significant difference of dicyemid development between two kidneys of the same individual, both in the analysis of C. indicus and O. marginatus. It indicates the separated way of dicyemid infection into two sides of kidneys.

No description available.

Kudoid parasites are common in marine fish and their affects range from relatively benign to pathogenic. They are notorious in the seafood industry for spoiling fish meat, either by muscle liquefaction or by producing unsightly macroscopic cysts. Kudoids also infect several other tissues such as brain, heart, gills, connective tissue, intestinal smooth muscle, and epithelia. Since the revised classification of the Kudoidae in 2004, kudoid myxospores have a range of shapes, but with two main characteristics: they have four or more spore valves with the equivalent number of polar capsules. With relatively few morphological traits to base kudoid species descriptions, DNA has proven to be increasingly useful to specifically diagnose infections. However, to properly utilise genetic information, there is a need to understand how genetics relates to the biological characteristics of species. This will ensure the genetic markers used are appropriate for species characterisation. This project aimed to develop an understanding of how biological characteristics including morphology, tissue tropism, host specificity, and geographic distribution correlate with genetic relatedness of kudoid species, and how this information could be employed to facilitate diagnosis and characterisation of species. A taxonomic investigation of kudoid isolates, mostly from the east coast of Queensland, Australia, was conducted using information on host identity, locality, infection status, tissue of infection and histological response to infection. Together with spore morphology and DNA relationships, comparisons were made with existing data from literature. Forty-three small subunit and 68 large subunit ribosomal DNA sequences were generated from kudoid isolates for this project. The two gene regions showed similar relationships amongst the kudoids, however the genetic variability between closely related species was less conserved in the large subunit, and showed superior species resolution that correlated with subtle morphological differences of spores. Broadly speaking, genetic relatedness of kudoids is closest for species infecting the same type of tissue with similar spore morphology. Within these tissue/morphology groups, some relationships were emerging from genetic correlations with pathology, however there are weaknesses in utilising this characteristic since pathology may change with host species or host age. Similar relationships to pathology were seen from geographic locality; however, the limited number of areas that genetic data originates from may have introduced some bias. Lastly, there were very few genetic relationships that correlated with host relatedness. The taxonomic affinities of the new kudoid isolates lead to the characterisation of six novel kudoid species and four additional host-parasite combinations. The investigation into these new species highlighted the broad host ranges and geographic distribution of some kudoid species. Genetic mixing of kudoid species populations from the east coast of Queensland, Australia with Japan was noted. For example, Kudoa amamiensis was discovered from carangid and pomacentrid fish from Queensland, increasing the host range from eight (seven from Japan, one from north Queensland) to 11 host species. Also, geographic distribution was extended to Heron Island on the south Great Barrier Reef (Queensland). The distribution did not extend to rocky temperate reefs further south. Another example is Kudoa yasunagai which was previously recorded from four fish species in Japan and one from the Philippines. Now the distribution has been extended to North Stradbroke Island in Southern Queensland from three additional host species. The connection was made between these host isolates with the assistance of DNA and a novel way of analysing morphological data in species that have variable morphotypes i.e. different numbers of polar capsules in the spores. It was confirmed that the dominant morphotype can vary between different hosts and even host samples of the one species. Genetic data has also proven useful in the determination of host range. An analysis of kudoid host specificity showed just over two thirds of the described kudoid species have been recorded from a single host; the remainder have been recorded from two to 38 host species. By using DNA data, 17 new hosts were recorded for K. thalassomi (total 18 hosts). The new hosts came from six different host families, but these fish shared the same habitat on the Great Barrier Reef. Other high host range kudoid species may be disproportionately broad as similar morphological species may have been misidentified from some hosts. For example, the host range of K. thyrsites (38) is likely to represent a species complex that may be split pending further genetic analyses. From this study, it has been reinforced that a holistic approach to species definition is important. Genetic analysis has become a particularly valuable tool; however, in conjunction with biological data such as spore morphology, pathology, host range, and geographic distribution, our understanding of kudoid parasites becomes more robust and provides important knowledge for diagnostics and aquaculture management. In the future, significant improvements in kudoid understanding will coincide with the solving of kudoid life cycles and transmission patterns.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21602号 / 理博第4509号 / 新制||理||1647(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 曽田 貞滋, 准教授 渡辺 勝敏, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

No description available.

The twisted-wing parasites (Strepsiptera) are entomophagous insect order with cosmopolitan distribution. There are about 600 known species up to date. In spite of this, they have very broad host spectrum. Strepsiptera parasites in seven insect groups (Thysanura, Blattodea, Mantodea, Orthoptera, Hemiptera, Diptera, Hymenoptera). The mutual relationship between genera or even between species are not known, except for the species list and the host specification. Moreover, there is an anambiguous use of their species concept. Some authors consider Strepsiptera as the specialists and they match almost every host species with one separate strepsipteran parasite. The opposite concept is to consider strepsiptera as the generalists. The presence of the crypctic species also affect our understanding of the diversity of Strepsiptera. Therefore, the knowledge of Strepsiptera phylogeny provide us the important information about species diversity of studied group as well as about their coevolution with their hosts. On the basis of molecular analyses of three genes constructed the phylogeny genus Stylops. This genus has the wider spetrum of the host species from other strepsipterans of Stylopidae, It is obvious, that strepsipterans of genus Stylops are mainly specialised on their host subgenus. There was detected two...

<p>Koi and goldfish have been released into rivers in South Africa since the 1800&rsquo / s for food and sport fish and have since spread extensively. These fish are present in most of the river systems in South Africa and pose an additional threat the indigenous cyprinids in the Western Cape. Monogenean parasites of the genus Gyrodactylus are of particular concern, as their unique biology renders them a possible threat. Gyrodactylus kherulensis and G. kobayashii were identified from koi and goldfish respectively imported from Asia, Europe and locally bred fish. Morphometrics and the use of statistical classifiers, which includes univariate (ANOVA and Kruskal-Wallis), bivariate (Pearson&rsquo / s correlation) and multivariate (Principal Component Analysis) placed the two species within their respective groups. There was some intraspecific variation among the different populations collected from the various locations, especially in the hamulus and ventral bar features, but the marginal hooklets, however, remained static for both helminth species.</p>