Efficient Generation of Germ Line Transmitting Chimeras from C57BL/6N ES Cells by Aggregation with Outbred Host Embryos

Genetically modified mouse strains derived from embryonic stem (ES) cells have become essential tools for functional genomics and biomedical research. Large scale mutagenesis projects are producing libraries of mutant C57BL/6 (B6) ES cells to enable the functional annotation of every gene of the mouse genome. To realize the utility of these resources, efficient and accessible methods of generating mutant mice from these ES cells are necessary. Here, we describe a combination of ICR morula aggregation and a chemically-defined culture medium with widely available and accessible components for the high efficiency generation of germline transmitting chimeras from C57BL/6N ES cells. Together these methods will ease the access of the broader biomedical research community to the publicly available B6 ES cell resources

Using viral vectors as gene transfer tools (Cell Biology and Toxicology Special Issue: ETCS-UK 1 day meeting on genetic manipulation of cells)

In recent years, the development of powerful viral gene transfer techniques has greatly facilitated the study of gene function. This review summarises some of the viral delivery systems routinely used to mediate gene transfer into cell lines, primary cell cultures and in whole animal models. The systems described were originally discussed at a 1-day European Tissue Culture Society (ETCS-UK) workshop that was held at University College London on 1st April 2009. Recombinant-deficient viral vectors (viruses that are no longer able to replicate) are used to transduce dividing and post-mitotic cells, and they have been optimised to mediate regulatable, powerful, long-term and cell-specific expression. Hence, viral systems have become very widely used, especially in the field of neurobiology. This review introduces the main categories of viral vectors, focusing on their initial development and highlighting modifications and improvements made since their introduction. In particular, the use of specific promoters to restrict expression, translational enhancers and regulatory elements to boost expression from a single virion and the development of regulatable systems is described

Exotic fish in exotic plantations: a multi-scale approach to understand amphibian occurrence in the mediterranean region

Globally, amphibian populations are threatened by a diverse range of factors including habitat destruction and alteration. Forestry practices have been linked with low diversity and abundance of amphibians. The effect of exotic Eucalyptus spp. plantations on amphibian communities has been studied in a number of biodiversity hotspots, but little is known of its impact in the Mediterranean region. Here, we identify the environmental factors influencing the presence of six species of amphibians (the Caudata Pleurodeles waltl, Salamandra salamandra, Lissotriton boscai, Triturus marmoratus and the anurans Pelobates cultripes and Hyla arborea/meridionalis) occupying 88 ponds. The study was conducted in a Mediterranean landscape dominated by eucalypt plantations alternated with traditional use (agricultural, montados and native forest) at three different scales: local (pond), intermediate (400 metres radius buffer) and broad (1000 metres radius buffer). Using the Akaike Information Criterion for small samples (AICc), we selected the top-ranked models for estimating the probability of occurrence of each species at each spatial scale separately and across all three spatial scales, using a combination of covariates from the different magnitudes. Models with a combination of covariates at the different spatial scales had a stronger support than those at individual scales. The presence of predatory fish in a pond had a strong effect on Caudata presence. Permanent ponds were selected by Hyla arborea/meridionalis over temporary ponds. Species occurrence was not increased by a higher density of streams, but the density of ponds impacted negatively on Lissotriton boscai. The proximity of ponds occupied by their conspecifics had a positive effect on the occurrence of Lissotriton boscai and Pleurodeles waltl. Eucalypt plantations had a negative effect on the occurrence of the newt Lissotriton boscai and anurans Hyla arborea/meridionalis, but had a positive effect on the presence of Salamandra salamandra, while no effect on any of the other species was detected. In conclusion, eucalypts had limited effects on the amphibian community at the intermediate and broad scales, but predatory fish had a major impact when considering all the scales combined. The over-riding importance of introduced fish as a negative impact suggests that forest managers should prevent new fish introductions and eradicate fish from already-occupied ponds whenever possible

Spatial ecology of the giant burrowing frog (Heleioporus australiacus): implications for conservation prescriptions

Management of threatened anurans requires an understanding of a species’ behaviour and habitat requirements in both the breeding and non-breeding environments. The giant burrowing frog (Heleioporus australiacus) is a threatened species in south-eastern Australia. Little is known about its habitat requirements, creating difficulties in developing management strategies for the species.Weradio-tracked 33 individual H. australiacus in order to determine their habitat use and behaviour. Data from 33 frogs followed for between 5 and 599 days show that individuals spend little time near (\u3c15 m) their breeding sites (mean 4.7 days for males and 6.3 days for females annually). Most time is spent in distinct non-breeding activity areas 20–250m from the breeding sites. Activity areas of females were further from the breeding site (mean 143 m) than those of males (mean 99 m), but were not significantly different in size (overall mean 500m2; males 553m2; females 307m2). Within activity areas, each frog used 1–14 burrows repeatedly, which weterm home burrows. Existing prescriptions are inappropriate for this species and we propose protection of key populations in the landscape as a more appropriate means of protecting this species

Investigating techniques to reduce evaporation from small reservoirs in Australia

Climate change has been posing a great pressure on water resources, particularly in Australia. In South-East Queensland (SEQ), the annual evaporation is expected to rise by about 16 per cent in the next 60 years due to increasing greenhouse gas emissions. As the region relies on a large volume of stored water, the minimisation of evaporation is a key factor in guaranteeing availability of water in the future. This paper analyses the efficiency of some existing techniques in reducing evaporation from small dams within SEQ. The use of suspended covers, destratification systems and windbreaks was investigated using modelling. Of these techniques, suspended covers showed the greatest potential for reducing evaporation (in the order of 88 per cent). The efficiency of windbreaks was around 27 per cent, while the use of destratification system did not change evaporation rates. These results are encouraging, and further research is warranted to determine the cost-effectiveness and environmental impacts of the use of suspended covers and windbreaks to reduce evaporation from small dams.Griffith Sciences, Griffith School of EngineeringNo Full Tex