5 research outputs found
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
Appraisal : a journal of constructive and post-critical philosophy and interdisciplinary studies
Spatial models of species distributions are becoming a common tool in wildlife management. Most distributional models are developed from point locality data which may limit the modelling process. Habitat variability within a species environment could be included by modelling areas of occurrence rather than point records. This may be particularly important for rare and cryptic species which often have only a small number of known localities. The giant burrowing frog Heleioporus australiacus is a threatened and cryptic species in south-eastern Australia. Previous attempts at modelling its distribution have been largely unsuccessful due to the extremely small number of known localities. We aimed to improve knowledge of the distribution of this species in south-eastern New South Wales (NSW) by comparing point- and area-based models. Our area-based model used watersheds as the area unit based on population data for this species. Generalized linear models were used to compare the environmental variables at 37 known localities with a set of 1000 random sites. Model performance was compared using the area under the curve from the receiver operating characteristic curve. Both modelling techniques suggest that the species may be more widely distributed than current records indicate. The species is most commonly associated with dry forest environments with high habitat complexity but avoiding large river valleys, high peaks and steep areas. These trends are consistent with an earlier BIOCLIM model for the species distribution adding support to the influence of these features as important to the species