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

Carbon sequestration potential for mitigating the carbon footprint of green stormwater infrastructure

Green stormwater infrastructure is a common feature of urban cities which is mostly designed for hydrological and water quality purposes. The last decade has seen a rise in research on the environmental impact assessment of vegetated water sensitive urban design (WSUD) technologies. However, the added ecosystem benefits of these systems, such as carbon sequestration, have received less attention. In this study, the life cycle net carbon footprint of various vegetated WSUD technologies namely green roofs, rain gardens, bioretention basins, vegetated swales and stormwater ponds, have been reviewed and analysed including their carbon sequestration potential. The carbon footprint of each vegetated WSUD technology was evaluated through the four phases of the life cycle assessment (LCA): material production, construction, operation and maintenance and end-of-life phases. The results of this study show that the initial embodied carbon associated with production, transportation and construction phases is the major contributor to the carbon footprint for most of the vegetated WSUD technologies. Rain gardens are shown to provide the highest carbon sequestration potential which offsets its carbon footprint. Carbon sequestration of bioretention basins, green roofs, vegetated swales and stormwater ponds can mitigate approximately 70%, 68%, 45% and 8% of their carbon footprint respectively. This study demonstrates the significant role of carbon sequestration in mitigating the carbon footprint from the assigned life time of the vegetated WSUD technologies. The results presented in this study will allow designers and policymakers to include the carbon implication in their WSUD strategies.Griffith Sciences, School of Engineering and Built EnvironmentNo Full Tex

Bioclimatic analysis of disjunct populations of the giant burrowing frog, Heleioporus australiacus

Aim A bioclimatic analysis of the giant burrowing frog was conducted to determine if the northern and southern populations have distinct climatic profiles and to determine if the disjunction in the species records is a result of a climatically unsuitable area. Location The study utilized records throughout the species range in south-eastern Australia. Methods The bioclim package was used to examine the climatic envelope of the species, as well as envelopes for the southern and northern populations. Principal components analysis (PCA) was used in an attempt to refine the model. Results The package predicted the observed gap between the populations as climatically suitable in all of the models. The northern populations were found in warmer and wetter sites than the southern populations. River valleys and coastal lowlands were generally unsuitable climatically for the species. Main conclusions The area of the observed disjunction is climatically suitable for both the northern and southern populations. Large river valleys appear to have played a significant role in determining the distribution of the species. PCA was used successfully to alter the model, however further research is needed to determine which is the most accurate approach

Interspecific variation in the phenology of advertisement calling in a temperate A

Spatial and temporal partitioning of resources underlies the coexistence of species with similar niches. In communities of frogs and toads, the phenology of advertisement calling provides insights into temporal partitioning of reproductive effort and its implications for community dynamics. This study assessed the phenology of advertisement calling in an anuran community from Melbourne, in southern Australia. We collated data from 1432 surveys of 253 sites and used logistic regression to quantify seasonality in the nightly probability of calling and the influence of meteorological variables on this probability for six species of frogs. We found limited overlap in the predicted seasonal peaks of calling among these species. Those shown to have overlapping calling peaks are unlikely to be in direct competition, due to differences in larval ecology (Crinia signifera and Litoria ewingii) or differences in calling behavior and acoustics (Limnodynastes dumerilii and Litoria raniformis). In contrast, closely related and ecologically similar species (Crinia signfera and Crinia parinsignifera; Litoria ewingii and Litoria verreauxii) appear to have staggered seasonal peaks of calling. In combination with interspecific variation in the meteorological correlates of calling, these results may be indicative of temporal partitioning of reproductive activity to facilitate coexistence, as has been reported for tropical and temperate anurans from other parts of the globe