In this grant we aim to study the moecular basis of cancer. The promoter regions of tumour suppressor genes are often modified in cancer by a chemical process called methylation. Methylation of DNA is associated with gene silencing. Therefore DNA methylation is commonly regarded as causing the silencing of genes in cancer. In this grant, we aim to determine if methylation is causal in triggering gene silencing in cancer, or if methylation is a consequence of gene silencing. This is a critical di ....In this grant we aim to study the moecular basis of cancer. The promoter regions of tumour suppressor genes are often modified in cancer by a chemical process called methylation. Methylation of DNA is associated with gene silencing. Therefore DNA methylation is commonly regarded as causing the silencing of genes in cancer. In this grant, we aim to determine if methylation is causal in triggering gene silencing in cancer, or if methylation is a consequence of gene silencing. This is a critical distinction in understanding the role of methylation in cancer development.Read moreRead less
A New Window into Transgene Silencing in Plants: mechanisms of copy-number independent, 5' sequence dependent, post-transcriptional silencing in a complex polyploid. Silencing of introduced genes is a major problem limiting plant molecular improvement. Sugarcane, a complex polyploid, shows the most efficient transgene silencing ever observed in plants. Silencing operates on the RNA, depends on the upstream sequence of the gene, and is independent of copy number. Other plant species develop endop ....A New Window into Transgene Silencing in Plants: mechanisms of copy-number independent, 5' sequence dependent, post-transcriptional silencing in a complex polyploid. Silencing of introduced genes is a major problem limiting plant molecular improvement. Sugarcane, a complex polyploid, shows the most efficient transgene silencing ever observed in plants. Silencing operates on the RNA, depends on the upstream sequence of the gene, and is independent of copy number. Other plant species develop endopolyploidy with age, and show unpredictable or patchy silencing. We speculate that differential silencing is a natural control mechanism in the exploitation of polyploidy in plants. The sugarcane system provides an exceptional opportunity to identify the sequences that trigger and protect from silencing, and to develop approaches to avoid the problem.Read moreRead less
Expression and characterisation of nutrient transporters from the intracellular malaria parasite, Plasmodium falciparum. The malaria parasite invades the red blood cells of its host and this provides it with a safe haven in which to grow and replicate. Within the red blood cell, the parasite takes up nutrients and excretes metabolic wastes via specialised membrane transport proteins which are, as yet, very poorly understood. The sequencing of the malaria parasite genome has enabled us to ident ....Expression and characterisation of nutrient transporters from the intracellular malaria parasite, Plasmodium falciparum. The malaria parasite invades the red blood cells of its host and this provides it with a safe haven in which to grow and replicate. Within the red blood cell, the parasite takes up nutrients and excretes metabolic wastes via specialised membrane transport proteins which are, as yet, very poorly understood. The sequencing of the malaria parasite genome has enabled us to identify candidates for a wide variety of these proteins. The aim of this project is to establish systems in which the functional properties of these transporter proteins may be characterised in detail.Read moreRead less
A Random Mutagenesis Screen To Identify Modifiers Of Epigenetic Phenomena In The Mouse.
Funder
National Health and Medical Research Council
Funding Amount
$680,750.00
Summary
In recent months, both the human and mouse genome projects have been completed. The main focus now for mammalian geneticists is to discover the function of the genes sequenced in these initiatives. One way to achieve this goal is by random mutagenesis followed by screening of mice for novel phenotypes. In the mouse, ethylnitosourea (ENU) is a chemical that can be used to perform the mutagenesis. ENU causes mutations in sperm. We are using ENU mutagenesis to search for genes that modify epigeneti ....In recent months, both the human and mouse genome projects have been completed. The main focus now for mammalian geneticists is to discover the function of the genes sequenced in these initiatives. One way to achieve this goal is by random mutagenesis followed by screening of mice for novel phenotypes. In the mouse, ethylnitosourea (ENU) is a chemical that can be used to perform the mutagenesis. ENU causes mutations in sperm. We are using ENU mutagenesis to search for genes that modify epigenetic states. Epigenetic modifications are alterations in the genome that do not change the DNA sequence, yet silence the expression of genes. Silencing occurs on a cell-by-cell basis within a tissue resulting in mosaic expression. Silencing can also occur between individuals of the same genetic makeup. For example, identical twins are occasionally found that have distinctly different characteristics, such as eye colour or severity of genetic disease. These differences may be the result of variable epigenetic modifications. However, very little is known about how these variable epigenetic modifications are controlled. We wish to find the proteins involved in establishing and maintaining epigenetic states. It is likely that these processes play a fundamental role in the determination of phenotype, both in normal development and disease.Read moreRead less
Plant transformation: exploiting anti-apoptosis genes for very high efficiency transformation. Crop improvement through genetic modification depends on the ability to transform target species. The most desirable method is Agrobacterium mediated transformation. However, plant species and cultivars differ significantly in their ability to be efficiently transformed by Agrobacterium. This is particularly true for the economically important cereals. We have discovered that anti-apoptosis genes, whic ....Plant transformation: exploiting anti-apoptosis genes for very high efficiency transformation. Crop improvement through genetic modification depends on the ability to transform target species. The most desirable method is Agrobacterium mediated transformation. However, plant species and cultivars differ significantly in their ability to be efficiently transformed by Agrobacterium. This is particularly true for the economically important cereals. We have discovered that anti-apoptosis genes, which inhibit programmed cell death, dramatically increase the Agrobacterium transformation efficiency in bananas and sugarcane. We will utilise this information and develop the use of these genes to increase the efficiency of transformation in those crops and cultivars that are difficult to transform using Agrobacterium.Read moreRead less
Inherited disorders of the blood, such as sickle-cell anaemia and thalassaemia, result from mutations in the genes that produce haemoglobin. Current treatments can partially alleviate some of the debilitating symptoms of these diseases but these treatments have significant side effects, and despite the best efforts of clinicians, many patients succumb to their conditions at an early age. It has been observed that certain individuals exhibit a milder form of the disease, as a consequence of the r ....Inherited disorders of the blood, such as sickle-cell anaemia and thalassaemia, result from mutations in the genes that produce haemoglobin. Current treatments can partially alleviate some of the debilitating symptoms of these diseases but these treatments have significant side effects, and despite the best efforts of clinicians, many patients succumb to their conditions at an early age. It has been observed that certain individuals exhibit a milder form of the disease, as a consequence of the reactivation of their foetal haemoglobin genes, (a distinct set of genes that would have been active in utero but are normally silenced around the time of birth). It is widely accepted that if pharmaceutical means can be found for reactivating the foetal haemoglobin genes then many patients would benefit. The regulation of the foetal globin genes, like most human genes, is complicated and there are few obvious means of increasing their activity. Nevertheless, it is believed that by investigating the molecular mechanisms by which they are controlled it will be possible to devise therapeutic agents that mimic these mechanisms or to develop agents that prevent the shutdown of the foetal genes around birth. To this end we have been working on the molecules that regulate the activity of the haemoglobin genes. We have recently cloned a number of DNA-binding proteins, and their co-factors, that appear to be involved in silencing foetal globin gene expression. This grant proposal is concerned with learning how these new molecules operate to silence gene expression as a first step towards designing agents that will prevent the silencing.Read moreRead less
Epigenetic Inheritance Through Meiosis At The Agouti Locus In Mice
Funder
National Health and Medical Research Council
Funding Amount
$182,699.00
Summary
The manifestations of many genetic traits do not conform to the rules of Mendelian inheritance. In humans, some alleles give a completely predictable phenotype, while others display a wide range of phenotypes, described as differences in penetrance and expressivity. As the phenotype associated with a particular gene in humans may be modified by the genotype at unlinked modifying loci and by environmental factors, it is difficult to determine to what extent any single factor is responsible for va ....The manifestations of many genetic traits do not conform to the rules of Mendelian inheritance. In humans, some alleles give a completely predictable phenotype, while others display a wide range of phenotypes, described as differences in penetrance and expressivity. As the phenotype associated with a particular gene in humans may be modified by the genotype at unlinked modifying loci and by environmental factors, it is difficult to determine to what extent any single factor is responsible for variability. In mice, however, a number of examples of variable expressivity have been reported in conditions where genetic background and environment have been controlled. For example, the phenotypes of mice with mutations at the agouti locus can vary substantially between genotypically identical littermates. Epigenetic modifications such as DNA methylation are known to be involved. Furthermore, the phenotypes of the offspring are related to the phenotype of the mother and recent experiments carried out in our laboratory suggest that this is the result of inheritance of the epigenetic state of the allele through the female germline. This is the first report of epigenetic inheritance at an endogenous gene in mammals. The experiments described in this project should help to clarify the mechanisms involved in variable expressivity and epigenetic inheritance. Variable expressivity in combination with epigenetic inheritance may be viewed as an alternative method of inheritance of genetic traits which does not involve DNA mutation, but which can be carried from generation to generation in a semipermanent way. Understanding the mechanisms underlying these phenomena is a challenge for contemporary genetics.Read moreRead less
Discovery of novel microRNA biogenesis and functional components. Discovery of novel microRNA components will provide new strategies for confronting a diverse array of challenges Australia faces, such as the increasing rates of certain cancers in our population, to stresses on our crop plants faced with environmental changes. The biological mechanisms underlying these disparate problems are unified by microRNA involvement in many instances. By finding microRNA controlling factors common to all h ....Discovery of novel microRNA biogenesis and functional components. Discovery of novel microRNA components will provide new strategies for confronting a diverse array of challenges Australia faces, such as the increasing rates of certain cancers in our population, to stresses on our crop plants faced with environmental changes. The biological mechanisms underlying these disparate problems are unified by microRNA involvement in many instances. By finding microRNA controlling factors common to all higher organisms, we expect our community will benefit from the increased knowledge base that will help our researchers adopt new strategies in fighting diseases and improving our agricultural industry.Read moreRead less