Teaching principles of genetics through SNP analysis

An understanding of inheritance requires comprehension of genetic processes at all levels, from molecules to populations. Frequently genetics courses are separated into molecular and organismal genetics and students may fail to see the relationships between them. This is particularly true with human genetics, because of the difficulties in designing experimental approaches which are consistent with ethical restrictions, student abilities and background knowledge, and available time and materials. During 2005 we used analysis of single nucleotide polymorphisms (SNPs) in two genetic regions to enhance student learning and provide a practical experience in human genetics. Students scanned databases to discover SNPs in a gene of interest, used software to design PCR primers and a restriction enzyme based assay for the alleles, and carried out an analysis of the SNP on anonymous individual and family DNAs. The project occupied eight to ten hours per week for one semester, with some time spent in the laboratory and some spent in database searching, reading and writing the report. In completing their projects, students acquired a knowledge of Mendel’s first law (through looking at inheritance patterns), Mendel’s second law and the exceptions (the concepts of linkage and linkage disequilibrium), DNA structure (primer design and restriction enzyme analysis) and function (SNPs in coding and non-coding regions), population genetics and the statistical analysis of allele frequencies, genomics, bioinformatics and the ethical issues associated with the use of human samples. They also developed skills in presentation of results by publication and conference participation. Deficiencies in their understanding (for example of inheritance patterns, gene structure, statistical approaches and report writing) were detected and guidance given during the project. SNP analysis was found to be a powerful approach to enhance and integrate student understanding of genetic concepts.

Dppa3 is a marker of pluripotency and has a human homologue that is expressed in germ cell tumours

We identified a transcript named 11M2 on the basis of its strong male-specific expression pattern in the developing mouse gonad. 11M2 was found to be expressed by gonad primordial germ cells (PGCs) of both sexes and down-regulated in female PGCs as they enter prophase I of the first meiotic division, similar to the expression of Oct4. Mouse EST analysis revealed expression only in early-stage embryos, embryonic stem cells and pre-meiotic germ cells. 11M2 corresponds to a recently reported gene variously known as PGC7, stella or Dppa3. We have identified the human orthologue of Dppa3 and find by human EST analysis that it is expressed in human testicular germ cell tumours but not in normal human somatic tissues. The expression patterns of mouse and human DPPA3, in undifferentiated embryonic cells, embryonic germ cells and adult germ cell tumours, together suggest a role for this gene in maintaining cell pluripotentiality.

Measuring the success of wildlife rehabilitation: Koalas and Brushtail possums

Native mammal populations in Southeast Queensland are under threat from habitat loss through land development, dog attacks and motor vehicle accidents. Animals that are not killed from these impacts are sometimes rescued, rehabilitated and later released back into the wild, usually in their area of origin. Although the release of these animals is a relatively common practice, little post release monitoring has been carried out and reported to assess the success of the animals in the wild. This paper discusses the results of three recent studies which have monitored the movements and health of rehabilitated and translocated koalas (Phascolarctos ciniereus) and common brushtail possums (Trichosurus vulpecular): one conducted by Wildcare Australia in 1995- 1996, the other two in collaboration with the University of Queensland. The results indicate that the survival and health of the great majority of the released animals were good and that they were usually able to establish new home ranges during the tracking period. Such findings seem to contradict the results of studies conducted in southern Australia which have monitored the release of translocated possums and gliders, and suggest that there are some key factors which may be critical in determining the success of such releases. These factors include the age of admission and the duration of care, and in particular the selection of the release site. With both koalas and brushtail possums, the release site was found to be critical in determining both the survival and dispersal of the released animals. Consequently, while these studies confirm that the reintroduction of koalas and common brushtail possums may be a viable management strategy, the individual characteristics of the animals themselves and of their release areas must be carefully considered. It is recommended that further research of these key release factors be undertaken and that the work be extended for other species which are commonly released following rehabilitation.