Copyright (c) 2009 All rights reserved. http://works.bepress.com/mervyn_shepherd Recent documents in Mervyn Shepherd en-us Wed, 04 Nov 2009 23:18:47 PST 3600 http://works.bepress.com/mervyn_shepherd/179 http://works.bepress.com/mervyn_shepherd/179 Tue, 03 Nov 2009 18:52:43 PST Mervyn Shepherd http://works.bepress.com/mervyn_shepherd/178 http://works.bepress.com/mervyn_shepherd/178 Tue, 03 Nov 2009 18:52:42 PST Mervyn Shepherd http://works.bepress.com/mervyn_shepherd/177 http://works.bepress.com/mervyn_shepherd/177 Tue, 03 Nov 2009 18:52:41 PST Mervyn Shepherd http://works.bepress.com/mervyn_shepherd/176 http://works.bepress.com/mervyn_shepherd/176 Tue, 27 Oct 2009 22:57:32 PDT H S. Saini http://works.bepress.com/mervyn_shepherd/175 http://works.bepress.com/mervyn_shepherd/175 Tue, 27 Oct 2009 22:57:32 PDT Genotyping by direct analysis of DNA has become increasing important in the breeding of plants and animals, for the diagnosis and study of genetic disorders in humans as well as in forensic science. One limitation of the current methodology is the lack of a very rapid test that can be performed in the order of minutes. DNA detection methods which are dependant upon separation or hybridisation such as gel electrophoresis or ELISA are usually lengthy, complex, multi-step processes and are not suited to very rapid assays. The melting profiles of dsDNA have been investigated as an alternative rapid detection method for use in genotyping. Subjecting PCR products to a temperature ramp in the presence of a dsDNA binding dye may generate DNA melting profiles which is characteristic of a particular genotype. A rapid decrease in fluorescence accompanies the conformation change from double to single strands. The plot of fluorescence versus temperature is dependent upon the fragment length; sequence and GC content and may distinguish it from other fragments differing in these properties. Detection is simple and can be performed in around 5 minutes in some cases. Both amplification and detection is possible in a single reaction vessel by the addition of a dye to the PCR reaction mix. We have used this approach to discriminate between admixtures of cereal crops and between cereal varieties. Mervyn Shepherd http://works.bepress.com/mervyn_shepherd/174 http://works.bepress.com/mervyn_shepherd/174 Tue, 27 Oct 2009 22:57:31 PDT Microsatellites or SSR (simple sequence repeats) are usually single locus, highly polymorphic and robust markers. Microsatellites are increasingly the marker of choice for genome analysis, mapping and diversity studies in plants (Gupta et al. 1996, Westman and Kresovicch 1997) and forest trees (for example Bradshaw et al. 1994, Brondani et al. 1998, Devey et al. 1996). The isolation and development of microsatellite markers, however, is often costly and problematic, especially in organisms with large genomes (Fisher and Bachmann 1998), such as conifers. For example, from our own experience, enriched microsatellite libraries for seven angiosperms (Eucalyptus pilularus, E. globulus, E. grandis, E. cloeziana, Grevillia robusta, Corymbia variegata, Toona ciliata) and three gymnosperm (Araucaria cunninghamii, Pinus elliottii, P. caribaea), using the method of Edwards et al. 1996, yielded enrichment of up to 50% in the angiosperm species but below 10% for all the gymnosperm species. Here we outline a library screening method which recovered high levels of microsatellite containing clones from libraries of coniferous species. Leon J. Scott http://works.bepress.com/mervyn_shepherd/173 http://works.bepress.com/mervyn_shepherd/173 Tue, 27 Oct 2009 22:57:30 PDT The ability to select clones of uniform wood properties to meet specific end use requirements is viewed as a key element for increasing profitability of exotic pine plantations in Queensland. A genetic mapping project has been initiated to investigate wood properties assessed in 11 year old F 1s. This will lead to a better understanding of the genetic architecture of wood traits and evaluation of the potential for marker-aided selection in the development of improved planting stock. Microsatellite and AFLP markers as well as wood properties will be mapped using a pseudotestcross strategy. This will allow co-segregation analysis between markers and those loci controlling wood traits which are heterozygous in the pure species parents and is most effective where parents are unselected for wood properties. By analysing half and full sib progeny sharing a common parent it is hoped QTL of good hybridising ability can be identified. Plantings over multiple sites will allow investigation of QTL stability across environments. The strategy and recent progress will be outlined Mervyn Shepherd http://works.bepress.com/mervyn_shepherd/172 http://works.bepress.com/mervyn_shepherd/172 Tue, 27 Oct 2009 22:57:29 PDT Leon J. Scott http://works.bepress.com/mervyn_shepherd/171 http://works.bepress.com/mervyn_shepherd/171 Tue, 27 Oct 2009 22:57:28 PDT In recent times microsatellite analysis has become a favourite tool for a multitude of genetic related projects. However, one of the major drawbacks of this technology is that characterisation of useful loci relies on DNA sequence knowledge. As a result, the amount of resources required does not justify the development of these markers for all species. A potential alternative to taxon specific characterisation, is cross species amplification of microsatellite loci. Initially thought to be less successful in plants than in animals, recent research is increasingly showing otherwise. In this study, we have investigated the transferrability of microsatellite loci in angiosperms, both dicots (Myrtaceae) and monocots (Poaceae), and gymnosperms (Pinus). Thirty five primer pairs developed for tea tree (Melaleuca alternifolia - Myrtaceae), were tested on seven other Myrtaceae including other economically important species such as eucalypts. Success was over 80% within members of the same genus and over 20% for more distant species. Similar studies have been carried out with microsatellites developed for Saccharum spp. and Pinus spp. showing reasonable amounts of cross-transferability. The results suggest that cross-transferability of microsatellites can be a viable alternative to specific characterisation, especially for studies requiring a limited number of hypervariable loci such as population genetics studies. Maurizio Rossetto http://works.bepress.com/mervyn_shepherd/170 http://works.bepress.com/mervyn_shepherd/170 Tue, 27 Oct 2009 22:57:27 PDT Robert J. Henry