Identifying potential barriers to transplanting modified forms of the CO2-fixing enzyme, Rubisco, into plants. Improving the ability of crops to use water, light and fertiliser more efficiently would have economic benefits and ease the environmental impacts associated with agricultural practices. It is thought that such improvements can be made by enhancing the efficiency of the photosynthetic protein, Rubisco, which fixes most of the CO2 in the biosphere. The research proposed here uses unique ....Identifying potential barriers to transplanting modified forms of the CO2-fixing enzyme, Rubisco, into plants. Improving the ability of crops to use water, light and fertiliser more efficiently would have economic benefits and ease the environmental impacts associated with agricultural practices. It is thought that such improvements can be made by enhancing the efficiency of the photosynthetic protein, Rubisco, which fixes most of the CO2 in the biosphere. The research proposed here uses unique Rubisco transplantation capabilities that I have developed to improve our fundamental understanding of how Rubisco is processed and its activity regulated in plants. This will pave the way for our ongoing efforts to engineer and transplant more efficient Rubisco into crops.Read moreRead less
Can efficient algal variants of the photosynthetic CO2-fixing enzyme, Rubisco, be folded and assembled in functional forms in higher-plant plastids? We have shown that it is possible to alter the photosynthetic phenotype of a plant predictably and profoundly by engineering the plastid genome to replace the plant's CO2-fixing enzyme, Rubisco, with a bacterial homolog. Thus it may be possible to replace the plant enzyme with more efficient algal Rubiscos that would allow plants to grow with less l ....Can efficient algal variants of the photosynthetic CO2-fixing enzyme, Rubisco, be folded and assembled in functional forms in higher-plant plastids? We have shown that it is possible to alter the photosynthetic phenotype of a plant predictably and profoundly by engineering the plastid genome to replace the plant's CO2-fixing enzyme, Rubisco, with a bacterial homolog. Thus it may be possible to replace the plant enzyme with more efficient algal Rubiscos that would allow plants to grow with less light, less water or less fertiliser. Before such desirable changes to the plant phenotype can be realised, some complex issues of modification, folding and assembly of Rubisco subunits need to be resolved. This proposal addresses them.Read moreRead less
Evolution in microsatellite DNA: testing models of mutation in an Australian marsupial. We aim to compare mutational events between microsatellite loci that vary in their exposure to recombination. We are able to do this because of a remarkable finding that Australian brushtail possums have multiple occurrences of a single microsatellite repeat element within the Y-chromosome and among autosomal loci. We will compare variation between the Y-linked and non Y-linked loci within and among individu ....Evolution in microsatellite DNA: testing models of mutation in an Australian marsupial. We aim to compare mutational events between microsatellite loci that vary in their exposure to recombination. We are able to do this because of a remarkable finding that Australian brushtail possums have multiple occurrences of a single microsatellite repeat element within the Y-chromosome and among autosomal loci. We will compare variation between the Y-linked and non Y-linked loci within and among individual possums and use those comparisons to distinguish between recombinant and non- recombinant mutational mechanisms. These data will provide new insights into the mutational mechanisms that drive variation in these most important molecular markers.Read moreRead less
Sex in Dragons: Evolution of sex determination in reptiles. Australia is a leader in sex determination research with major advances in our understanding attributable to Australian researchers and laboratories. This project will contribute to our prestige as a nation capable of contributing cutting edge research directions and stimulating ideas in human sex determination. Moreover, many reptiles have temperature-dependent sex determination, and so would appear appallingly vulnerable to climate ch ....Sex in Dragons: Evolution of sex determination in reptiles. Australia is a leader in sex determination research with major advances in our understanding attributable to Australian researchers and laboratories. This project will contribute to our prestige as a nation capable of contributing cutting edge research directions and stimulating ideas in human sex determination. Moreover, many reptiles have temperature-dependent sex determination, and so would appear appallingly vulnerable to climate change. Our project, will bring improved understanding of sex determination in reptiles, identify evolutionary responses of reptiles to climate change, and assist by informing society on how we might manage this issue into the future conservation of these unique Australian reptiles. Read moreRead less
Sex in Dragons: The molecular basis of genetic and environmental sex determination. How animals determine sex has been debated over decades. Particularly mysterious is that sex is determined by genes in some animals, and by temperature in others. We will study closely related dragon lizards which determine sex via genes (GSD) or temperature (TSD). We will use novel genetic, molecular and cytological aproaches to discover genes and chromosomes that control sex determination in the GSD species, an ....Sex in Dragons: The molecular basis of genetic and environmental sex determination. How animals determine sex has been debated over decades. Particularly mysterious is that sex is determined by genes in some animals, and by temperature in others. We will study closely related dragon lizards which determine sex via genes (GSD) or temperature (TSD). We will use novel genetic, molecular and cytological aproaches to discover genes and chromosomes that control sex determination in the GSD species, and explore their homologues in the TSD species. We expect this study will provide new insights to mechanisms of sex determination in all vertebrates, and demonstrate how genes and the environment interact to control the process.Read moreRead less
Controlling the rate of transcription and translation of Rubisco transgenes effectively in higher-plant plastids. Genetic transformation of the circular genome of the plastids provides a containable means for modifying plant growth by manipulating photosynthesis. Although the transformation mechanism is precise, predicting the level of foreign gene expression is difficult because the amounts of messenger RNA and protein produced by foreign genes in plastids varies widely, even when the protein a ....Controlling the rate of transcription and translation of Rubisco transgenes effectively in higher-plant plastids. Genetic transformation of the circular genome of the plastids provides a containable means for modifying plant growth by manipulating photosynthesis. Although the transformation mechanism is precise, predicting the level of foreign gene expression is difficult because the amounts of messenger RNA and protein produced by foreign genes in plastids varies widely, even when the protein assembles without difficulty. This project will devise strategies for controlling this variability that will facilitate attempts to exploit plastid transformation for transplanting better versions of the photosynthetic CO2-fixing enzyme, Rubisco, into plants to improve their growth efficiency in terms of water, fertiliser and light use.Read moreRead less
Organization, function and evolution of marsupial Y chromosomes. The Y chromosome of humans and other mammals contains only a few genes, most specialized for male sex and reproduction. How the Y chromosome evolved to be so peculiar has been debated for 90 years. It began as an ordinary chromosome, but has degraded until there is almost nothing left, and it is likely to disappear in about 13 million years. Molecular characterization of the Y chromosomes of distantly related mammals could serve to ....Organization, function and evolution of marsupial Y chromosomes. The Y chromosome of humans and other mammals contains only a few genes, most specialized for male sex and reproduction. How the Y chromosome evolved to be so peculiar has been debated for 90 years. It began as an ordinary chromosome, but has degraded until there is almost nothing left, and it is likely to disappear in about 13 million years. Molecular characterization of the Y chromosomes of distantly related mammals could serve to 're-run the evolutionary tape', but the Y chromosome has been left out of whole genome sequencing because it is hard to do efficiently. We developed a novel technique to isolate DNA sequences and genes on the Y chromosome in three species of marsupials, which are especially valuable because they are so different from human and mouse.Read moreRead less
Sex in Dragons: Probing the genotype-phenotype interaction in sex determination. Reptiles have two modes of sex determination: genetic (GSD) and temperature dependent (TSD). We will determine if there is an underlying mechanism of sex determination common to TSD and GSD reptiles by comparing the genomes of two sister species of dragon lizard that differ in their mode of sex determination. This study will provide new insights to the mechanism of sex determination in vertebrates and will test the ....Sex in Dragons: Probing the genotype-phenotype interaction in sex determination. Reptiles have two modes of sex determination: genetic (GSD) and temperature dependent (TSD). We will determine if there is an underlying mechanism of sex determination common to TSD and GSD reptiles by comparing the genomes of two sister species of dragon lizard that differ in their mode of sex determination. This study will provide new insights to the mechanism of sex determination in vertebrates and will test the proposition that sex determination results from the interaction between environmental influences and an underlying genetic component.Read moreRead less
Practical strategies for engineering the CO2-fixing enzyme, Rubisco, whose subunits are encoded in different subcellular compartments. My recent replacement of the plant CO2-fixing enzyme, Rubisco, with a less efficient bacterial version, with a single type of subunit encoded by a single gene, demonstrated the feasibility of replacing Rubisco. This encourages ongoing attempts to replace plant Rubisco with more efficient versions that would allow the plants to grow with less water, fertiliser or ....Practical strategies for engineering the CO2-fixing enzyme, Rubisco, whose subunits are encoded in different subcellular compartments. My recent replacement of the plant CO2-fixing enzyme, Rubisco, with a less efficient bacterial version, with a single type of subunit encoded by a single gene, demonstrated the feasibility of replacing Rubisco. This encourages ongoing attempts to replace plant Rubisco with more efficient versions that would allow the plants to grow with less water, fertiliser or light. The most efficient Rubiscos are more complex, with two different types of subunits which, in plants, are encoded in different subcellular compartments (nucleus and plastid). This proposal addresses the challenges associated with complementary engineering both genomes to substitute foreign Rubiscos into higher-plant chloroplasts.Read moreRead less
Solving the Mysteries of Monotreme Chromosomes. The peculiar chromosomes of Australia's platypus and echidna have been debated for more than 30 years. Classical cytology cannot resolve the puzzling sex chromosome system, or to sort out the bizarre translocation chain (unique in vertebrates) and deduce how it segregates to make viable zyotes. I will microdissect individual chromosomes, and use DNA ?paints? from them (and gene probes isolated by them) to detect homologies between unpaired chromoso ....Solving the Mysteries of Monotreme Chromosomes. The peculiar chromosomes of Australia's platypus and echidna have been debated for more than 30 years. Classical cytology cannot resolve the puzzling sex chromosome system, or to sort out the bizarre translocation chain (unique in vertebrates) and deduce how it segregates to make viable zyotes. I will microdissect individual chromosomes, and use DNA ?paints? from them (and gene probes isolated by them) to detect homologies between unpaired chromosomes at mitosis, meiosis and in sperm. I will use immunohistochemistry to clarify chromosome pairing and recombination at meiosis. This will answer some important general questions about chromosome behaviour and sex chromosome evolution.
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