This study set out to examine, for the first time, both the molluscan intermediate and the teleost definitive hosts of a major assemblage of trematode parasites present on the Great Barrier Reef (GBR). The parasite taxon was the Bucephalidae which occur in piscivorous fishes as sexually reproducing adults and in bivalves as asexually reproducing stages. The goal was to characterise the overall richness of the system and to explore patterns of host-specificity. Because of the size of this fauna it was not possible to incorporate all the taxa found in this study. This thesis reports the results of a survey of bivalves from this region, taxonomic studies on several elements of the fauna of fishes, and efforts to link life-cycles between bivalves and fishes. I surveyed 2256 bivalve individuals (47 species, 17 families) from South-east Queensland, Heron Island (southern GBR) and Lizard Island (northern GBR). Infections of trematode species from three families, Bucephalidae, Gorgoderidae and Monorchiidae, were found. Overall prevalence of infection was 2.3%. The Bucephalidae (11 species) was the most commonly found family. A single gorgoderid infection was found from a venerid, Lioconcha castrensis. This is the first report of a gorgoderid from a marine bivalve and phylogenetic analysis suggests that the species belongs to the Gorgoderinae. Monorchiids (5 species) were found from Tellinidae and Lucinidae. All infections are new host/parasite records. I deduce that this study produced lifecycle information, but no actual identifications, for 10% of the species of trematodes that infect bivalves of Queensland marine waters. Prosorhynchoides apogonis n. sp. is described from the intestine of the apogonid Cheilodipterus macrodon from the southern GBR. This is the first bucephalid to be described from the teleost family Apogonidae. Prosorhynchoides lamprelli n. sp. is described from the intestine of the carangid Caranx papuensis from off Lizard Island, GBR. This is the first bucephalid to be described from Caranx papuensis. A new trematode genus, Grammatorcynicola n. g. (Dolichoenterinae), and two new species, G. brayi n. sp. and G. nolani n. sp., are described from the intestines of the scombrids, Grammatorcynus bicarinatus and Gr. bilineatus respectively. Grammatorcynicola n. g. differs from other dolichoenterine genera in having a simple sucker-like rhynchus, the ovary anterior to the testes and by not having a particularly thick cirrus-sac wall. Six new species of bucephalid trematodes from the prosorhynchine bucephalid genera Prosorhynchus Odhner, 1905 and Neidhartia Nagaty, 1937 are reported from the epinepheline serranid genera Cephalopholis, Cromileptes, Epinephelus and Variola from the GBR. Two species of Prosorhynchus and one Neidhartia are reported from Epinephelus spp., P. jexi n. sp. from E. quoyanus, P. lafii n. sp. from E. fuscoguttatus, and N. epinepheli n. sp. from E. maculatus. The other species are P. robertsthomsoni n. sp. from several species of Cephalopholis, P. conorjonesi n. sp. from Cromileptes altivelis, and P. milleri n. sp. from Variola louti. I examined three species of Plectropomus (Serranidae: Epinephelinae), Pl. laevis, Pl. leopardus and Pl. maculatus from off Heron Island and Lizard Island on the GBR. Nine bucephalid species from the Prosorhynchinae were found, three species of Neidhartia and six species of Prosorhynchus. The three species of Neidhartia, N. haywardi n. sp., N. plectropomi n. sp. and N. tyleri n. sp., are readily distinguishable by morphology. Two of the six species of Prosorhynchus (P. lesteri n. sp. and P. wrightae n. sp.) are easily distinguished from their other congeners by morphology but the other four species (P. adlardi n. sp., P. heronensis n. sp., P. munozae n. sp. and P. plectropomi n. sp.) are highly similar in morphology and were only distinguished convincingly by comparing their ITS2 rDNA sequences. Both P. adlardi n. sp. and P. wrightae n. sp. have also been found once in V. louti at Lizard Island. This is also the first study to identify life-cycle matches of the Bucephalidae using molecular techniques. I found two perfect life-cycle matches (identical sequences). The bivalve host of Prosorhynchoides lamprelli is a tellinid, Exotica clathrata; Rhipidocotyle sp. from the sphyraenid Sphyraena jello also has E. clathrata as its first intermediate host. Bayesian Inference Analysis shows that all seven species from bivalves that were sequenced belong to the Bucephalinae. Perhaps the most striking finding of the study was that one bivalve species, E. clathrata, was shown to harbour four separate species. Matching of ITS2 rDNA sequences between life-cycle stages is highly effective in circumstances of great richness such as the Great Barrier Reef. Based on my data collected, the total bucephalid species in the system is estimated to be 84.

This study set out to examine, for the first time, both the molluscan intermediate and the teleost definitive hosts of a major assemblage of trematode parasites present on the Great Barrier Reef (GBR). The parasite taxon was the Bucephalidae which occur in piscivorous fishes as sexually reproducing adults and in bivalves as asexually reproducing stages. The goal was to characterise the overall richness of the system and to explore patterns of host-specificity. Because of the size of this fauna it was not possible to incorporate all the taxa found in this study. This thesis reports the results of a survey of bivalves from this region, taxonomic studies on several elements of the fauna of fishes, and efforts to link life-cycles between bivalves and fishes. I surveyed 2256 bivalve individuals (47 species, 17 families) from South-east Queensland, Heron Island (southern GBR) and Lizard Island (northern GBR). Infections of trematode species from three families, Bucephalidae, Gorgoderidae and Monorchiidae, were found. Overall prevalence of infection was 2.3%. The Bucephalidae (11 species) was the most commonly found family. A single gorgoderid infection was found from a venerid, Lioconcha castrensis. This is the first report of a gorgoderid from a marine bivalve and phylogenetic analysis suggests that the species belongs to the Gorgoderinae. Monorchiids (5 species) were found from Tellinidae and Lucinidae. All infections are new host/parasite records. I deduce that this study produced lifecycle information, but no actual identifications, for 10% of the species of trematodes that infect bivalves of Queensland marine waters. Prosorhynchoides apogonis n. sp. is described from the intestine of the apogonid Cheilodipterus macrodon from the southern GBR. This is the first bucephalid to be described from the teleost family Apogonidae. Prosorhynchoides lamprelli n. sp. is described from the intestine of the carangid Caranx papuensis from off Lizard Island, GBR. This is the first bucephalid to be described from Caranx papuensis. A new trematode genus, Grammatorcynicola n. g. (Dolichoenterinae), and two new species, G. brayi n. sp. and G. nolani n. sp., are described from the intestines of the scombrids, Grammatorcynus bicarinatus and Gr. bilineatus respectively. Grammatorcynicola n. g. differs from other dolichoenterine genera in having a simple sucker-like rhynchus, the ovary anterior to the testes and by not having a particularly thick cirrus-sac wall. Six new species of bucephalid trematodes from the prosorhynchine bucephalid genera Prosorhynchus Odhner, 1905 and Neidhartia Nagaty, 1937 are reported from the epinepheline serranid genera Cephalopholis, Cromileptes, Epinephelus and Variola from the GBR. Two species of Prosorhynchus and one Neidhartia are reported from Epinephelus spp., P. jexi n. sp. from E. quoyanus, P. lafii n. sp. from E. fuscoguttatus, and N. epinepheli n. sp. from E. maculatus. The other species are P. robertsthomsoni n. sp. from several species of Cephalopholis, P. conorjonesi n. sp. from Cromileptes altivelis, and P. milleri n. sp. from Variola louti. I examined three species of Plectropomus (Serranidae: Epinephelinae), Pl. laevis, Pl. leopardus and Pl. maculatus from off Heron Island and Lizard Island on the GBR. Nine bucephalid species from the Prosorhynchinae were found, three species of Neidhartia and six species of Prosorhynchus. The three species of Neidhartia, N. haywardi n. sp., N. plectropomi n. sp. and N. tyleri n. sp., are readily distinguishable by morphology. Two of the six species of Prosorhynchus (P. lesteri n. sp. and P. wrightae n. sp.) are easily distinguished from their other congeners by morphology but the other four species (P. adlardi n. sp., P. heronensis n. sp., P. munozae n. sp. and P. plectropomi n. sp.) are highly similar in morphology and were only distinguished convincingly by comparing their ITS2 rDNA sequences. Both P. adlardi n. sp. and P. wrightae n. sp. have also been found once in V. louti at Lizard Island. This is also the first study to identify life-cycle matches of the Bucephalidae using molecular techniques. I found two perfect life-cycle matches (identical sequences). The bivalve host of Prosorhynchoides lamprelli is a tellinid, Exotica clathrata; Rhipidocotyle sp. from the sphyraenid Sphyraena jello also has E. clathrata as its first intermediate host. Bayesian Inference Analysis shows that all seven species from bivalves that were sequenced belong to the Bucephalinae. Perhaps the most striking finding of the study was that one bivalve species, E. clathrata, was shown to harbour four separate species. Matching of ITS2 rDNA sequences between life-cycle stages is highly effective in circumstances of great richness such as the Great Barrier Reef. Based on my data collected, the total bucephalid species in the system is estimated to be 84.

The identification of specific and reproducible biomarkers is critical for the early diagnosis of cancer, which has a profound effect the survival rate of patients. Comprehensive laboratory and clinical evidence needs to be collected to confirm the accuracy of the biomarkers prior to their clinical use. Heterogenous nuclear ribonucleoproteins (hnRNPs) A2 and B1 have been suggested as biomarkers for cancer since 1988 when hnRNP A2/B1 overexpression was first linked with the occurrence of lung cancer. Later studies established a correlation between the expression levels of these hnRNPs and other cancers, such as breast, pancreatic, and lymphatic tumours. In this study, the expression of hnRNPs A1, A2, A3, and B1 has been investigated in various cancer cell lines. hnRNPs A1 and A3, in addition to A2 and B1, were found to be overexpressed in some cancer types. However, the overexpression of none of the hnRNP A/B proteins was universal, and their upregulation may be limited to a few cell types, suggesting they may be effective biomarkers for a subset of cancers. The upregulation of hnRNP A/B proteins in tumours and cancer cell lines led to the hypothesis that they are involved in the uncontrolled cell growth in cancer. According to our Western blot analysis, expression of the hnRNP proteins, A1, A2, and B1, is dependent on the cell cycle whereas no significant change was detected for hnRNP A3, implying that the former three are needed during certain cell cycle stages. The results, together with the transcription factor analysis of the promoter regions of the HNRPA1, HNRPA2, and HNRPA3 genes, suggest that hnRNPs A1, A2, and A3 may have distinct regulatory machineries and cellular functions although they have high amino acid sequence identity. However, their mRNA levels were unchanged across the cell cycle, suggesting the cell-cycle-dependent expression of hnRNPs A1, A2, and B1 is modulated at the translational level. Previous studies showed higher expression of hnRNPs A1 and A2 in rapidly proliferating cells than in quiescent cells, suggesting a role of these proteins in cell proliferation. Though interruption of hnRNP A1 expression did not result in significant change in the viability of murine CB3 cells, simultaneous suppression of hnRNPs A1 and A2 caused apoptosis in a few cell lines. Consistent with this, suppression of hnRNP A1 or A3 expression in our study in Colo16 squamous cells using RNA interference did not affect cell proliferation, but simultaneous suppression of both caused slow cell proliferation. By contrast, reduction of the hnRNP A2 level alone slowed the proliferation of Colo16 cells. These results suggest that although hnRNPs A1, A2, and A3 share some roles in cell proliferation, each of them may have distinct tasks. This conclusion is supported by the data from the comparative analysis of the downstream targets of hnRNPs A1, A2, and A3, which has shown that these three proteins share a limited number of common downstream proteins. The observed impact on cell proliferation of suppressing hnRNP A2 subfamily proteins is in accord with our finding that the downstream targets of hnRNP A2 are overrepresented by genes involved in proliferation regulation, as shown in microarray and real-time PCR analysis. These include cyclin-dependent kinase (CDK) inhibitors, p21 and p27, and their regulatory proteins, such as Skp2 and Rpn10. Skp2 controls the ubiquitination of p21 and p27, and Rpn10 links them to the 26S proteasome, the complex that degrades these two CDK inhibitors. hnRNP A2 also regulates the transcription of securin and separin, which are essential for sister chromatid separation during late anaphase. In addition, hnRNP A2 can also influence cell proliferation through cell growth factors, including fibroblast, vascular endothelial, transforming, and insulin growth factors. Our gene array and real-time PCR analysis have shown that hnRNP A2 regulates the expression of these factors, their receptors, or associated proteins such as IGFBP7 and TGFBR2. The data presented in this thesis link the overexpression of hnRNP A/B proteins, in particular the A2/B1 subfamily, in cancer with their regulatory roles in cell division and cell proliferation. Our findings provide mechanistic evidence that these proteins may be a driving force for the uncontrolled cell growth in cancer, suggesting that some of hnRNP A/B proteins may be potential therapeutic targets for cancer. However, further studies are needed to obtain a global view of the roles of these proteins in cancer.

The identification of specific and reproducible biomarkers is critical for the early diagnosis of cancer, which has a profound effect the survival rate of patients. Comprehensive laboratory and clinical evidence needs to be collected to confirm the accuracy of the biomarkers prior to their clinical use. Heterogenous nuclear ribonucleoproteins (hnRNPs) A2 and B1 have been suggested as biomarkers for cancer since 1988 when hnRNP A2/B1 overexpression was first linked with the occurrence of lung cancer. Later studies established a correlation between the expression levels of these hnRNPs and other cancers, such as breast, pancreatic, and lymphatic tumours. In this study, the expression of hnRNPs A1, A2, A3, and B1 has been investigated in various cancer cell lines. hnRNPs A1 and A3, in addition to A2 and B1, were found to be overexpressed in some cancer types. However, the overexpression of none of the hnRNP A/B proteins was universal, and their upregulation may be limited to a few cell types, suggesting they may be effective biomarkers for a subset of cancers. The upregulation of hnRNP A/B proteins in tumours and cancer cell lines led to the hypothesis that they are involved in the uncontrolled cell growth in cancer. According to our Western blot analysis, expression of the hnRNP proteins, A1, A2, and B1, is dependent on the cell cycle whereas no significant change was detected for hnRNP A3, implying that the former three are needed during certain cell cycle stages. The results, together with the transcription factor analysis of the promoter regions of the HNRPA1, HNRPA2, and HNRPA3 genes, suggest that hnRNPs A1, A2, and A3 may have distinct regulatory machineries and cellular functions although they have high amino acid sequence identity. However, their mRNA levels were unchanged across the cell cycle, suggesting the cell-cycle-dependent expression of hnRNPs A1, A2, and B1 is modulated at the translational level. Previous studies showed higher expression of hnRNPs A1 and A2 in rapidly proliferating cells than in quiescent cells, suggesting a role of these proteins in cell proliferation. Though interruption of hnRNP A1 expression did not result in significant change in the viability of murine CB3 cells, simultaneous suppression of hnRNPs A1 and A2 caused apoptosis in a few cell lines. Consistent with this, suppression of hnRNP A1 or A3 expression in our study in Colo16 squamous cells using RNA interference did not affect cell proliferation, but simultaneous suppression of both caused slow cell proliferation. By contrast, reduction of the hnRNP A2 level alone slowed the proliferation of Colo16 cells. These results suggest that although hnRNPs A1, A2, and A3 share some roles in cell proliferation, each of them may have distinct tasks. This conclusion is supported by the data from the comparative analysis of the downstream targets of hnRNPs A1, A2, and A3, which has shown that these three proteins share a limited number of common downstream proteins. The observed impact on cell proliferation of suppressing hnRNP A2 subfamily proteins is in accord with our finding that the downstream targets of hnRNP A2 are overrepresented by genes involved in proliferation regulation, as shown in microarray and real-time PCR analysis. These include cyclin-dependent kinase (CDK) inhibitors, p21 and p27, and their regulatory proteins, such as Skp2 and Rpn10. Skp2 controls the ubiquitination of p21 and p27, and Rpn10 links them to the 26S proteasome, the complex that degrades these two CDK inhibitors. hnRNP A2 also regulates the transcription of securin and separin, which are essential for sister chromatid separation during late anaphase. In addition, hnRNP A2 can also influence cell proliferation through cell growth factors, including fibroblast, vascular endothelial, transforming, and insulin growth factors. Our gene array and real-time PCR analysis have shown that hnRNP A2 regulates the expression of these factors, their receptors, or associated proteins such as IGFBP7 and TGFBR2. The data presented in this thesis link the overexpression of hnRNP A/B proteins, in particular the A2/B1 subfamily, in cancer with their regulatory roles in cell division and cell proliferation. Our findings provide mechanistic evidence that these proteins may be a driving force for the uncontrolled cell growth in cancer, suggesting that some of hnRNP A/B proteins may be potential therapeutic targets for cancer. However, further studies are needed to obtain a global view of the roles of these proteins in cancer.

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No description available.

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No description available.

No description available.