The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
Larry A Gilbertson - One of the best experts on this subject based on the ideXlab platform.
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cre lox Recombination cre ative tools for plant biotechnology
Trends in Biotechnology, 2003Co-Authors: Larry A GilbertsonAbstract:Abstract Targeted insertion and the precise deletion of DNA from transgenic plant chromosomes increase the potential of plant biotechnology for commercial applications and basic research. The Cre– lox Recombination system is one of the best characterized and most widely used systems for these purposes. Cre– lox has many applications, but it is primarily used for the controlled excision of DNA fragments, in particular selectable marker genes, from the nuclear and chloroplast genomes, and for the targeted insertion of DNA into specific sites in the nuclear genome. Recent developments, including regulated expression of cre and the creative use of wild-type and modified lox sites, have improved the potential of these applications. After almost 15 years of research and development in plants, the Cre– lox system continues to provide an efficient and precise tool for plant biotechnologists.
Brian Sauer - One of the best experts on this subject based on the ideXlab platform.
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multiplex cre lox Recombination permits selective site specific dna targeting to both a natural and an engineered site in the yeast genome
Nucleic Acids Research, 1996Co-Authors: Brian SauerAbstract:Variant lox sites having an altered spacer region (heterospecific lox sites) are not proficient for Cre-mediated Recombination with the canonical 34 bp loxP site, but can recombine with each other. By placing different heterospecific lox sites at different genomic locations, Cre can catalyze independent DNA Recombination events at multiple loci in the same cell without concern that unwanted inter-locus Recombination events will be generated. Such heterospecific lox sites also allow Cre to specifically target efficient integration of exogenous DNA to endogenous lox-like sequences that naturally occur in the genome. Specific targeting occurs only with a DNA vector carrying a heterospecific lox site in which the spacer region has been redesigned to match the 'spacer' region of the targeted chromosomal element. Moreover, in cells expressing a catalytically active Cre recombinase, naturally occurring lox-like sequences can exhibit almost 20% mitotic Recombination. Thus, in the same cell, heterospecific lox sites can be used independently at multiple loci for integration, for deletion and for enhanced mitotic Recombination, thereby increasing the repertoire of genomic manipulations catalyzed by the Cre recombinase.
Jeff W Lichtman - One of the best experts on this subject based on the ideXlab platform.
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Transgenic strategies for combinatorial expression of fluorescent proteins in the nervous system
Nature, 2007Co-Authors: J Livet, Tamily A. Weissman, Hyuno Kang, Ryan W. Draft, Robyn A. Bennis, Joshua R. Sanes, Ju Lu, Jeff W LichtmanAbstract:Detailed analysis of neuronal network architecture requires the development of new methods. Here we present strategies to visualize synaptic circuits by genetically labelling neurons with multiple, distinct colours. In Brainbow transgenes, Cre/lox Recombination is used to create a stochastic choice of expression between three or more fluorescent proteins (XFPs). Integration of tandem Brainbow copies in transgenic mice yielded combinatorial XFP expression, and thus many colours, thereby providing a way to distinguish adjacent neurons and visualize other cellular interactions. As a demonstration, we reconstructed hundreds of neighbouring axons and multiple synaptic contacts in one small volume of a cerebellar lobe exhibiting approximately 90 colours. The expression in some lines also allowed us to map glial territories and follow glial cells and neurons over time in vivo. The ability of the Brainbow system to label uniquely many individual cells within a population may facilitate the analysis of neuronal circuitry on a large scale.
Joan C. Marini - One of the best experts on this subject based on the ideXlab platform.
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use of the cre lox Recombination system to develop a non lethal knock in murine model for osteogenesis imperfecta with an alpha1 i g349c substitution variability in phenotype in brtliv mice
Journal of Biological Chemistry, 1999Co-Authors: Antonella Forlino, Forbes D. Porter, Heiner Westphal, Joan C. MariniAbstract:Abstract We utilized the Cre/lox Recombination system to develop the first knock-in murine model for osteogenesis imperfecta (OI). The moderately severe OI phenotype was obtained from an α1(I) Gly349 → Cys substitution in type I collagen, reproducing the mutation in a type IV OI child. We introduced four single nucleotide (nt) changes into murine col1a1 exon 23: the disease causing G→T transversion (nt 1546), an adjacent G→T change (nt 1551) to generate a GUC ribozyme cleavage site, and two transversions (nt 1567 C→A and nt 1569 C→G) to cause a Leu → Met substitution. We also introduced a 3.2-kilobase pair transcription/translation stop cassette in intron 22, flanked by directly repeating loxRecombination sites. After homologous Recombination in ES cells, two male chimeras were obtained. Chimeras were mated with transgenic females expressing Cre recombinase to remove the stop cassette from a portion of the progeny's cells. To generate mice with full expression of the Gly349 → Cys mutation, these offspring were then mated with wild-type females. Skeletal staining and bone histology of the F2 revealed a classical OI phenotype with deformity, fragility, osteoporosis and disorganized trabecular structure. We designate these mice BrtlIV (Brittle IV). BrtlIV mice have phenotypic variability ranging from perinatal lethality to long term survival with reproductive success. The phenotypic variability is not associated with differences in expression levels of the mutant allele in total RNA derived from tissue extracts. Expression of the mutant protein is also equivalent in different phenotypes. Thus, these mice are an excellent model for delineation of the modifying factors postulated to affect human OI phenotypes. In addition, we generated knock-in mice carrying an “intronic” inclusion by mating chimeras with wild-type females. Alternative splicing involving the stop cassette results in retention of non-collagenous sequences. These mice reproduce the lethal phenotype of similar human mutations and are designated BrtlII.
Huizhong W Tao - One of the best experts on this subject based on the ideXlab platform.
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sparse labeling and neural tracing in brain circuits by stars strategy revealing morphological development of type ii spiral ganglion neurons
Cerebral Cortex, 2018Co-Authors: Leena A Ibrahim, Junxiang J Huang, Shengzhi Wang, Young J Kim, Li I Zhang, Huizhong W TaoAbstract:Elucidating axonal and dendritic projection patterns of individual neurons is a key for understanding the cytoarchitecture of neural circuits in the brain. This requires genetic approaches to achieve Golgi-like sparse labeling of desired types of neurons. Here, we explored a novel strategy of stochastic gene activation with regulated sparseness (STARS), in which the stochastic choice between 2 competing Cre-Lox Recombination events is controlled by varying the lox efficiency and cassette length. In a created STARS transgenic mouse crossed with various Cre driver lines, sparse neuronal labeling with a relatively uniform level of sparseness was achieved across different brain regions and cell types in both central and peripheral nervous systems. Tracing of individual type II peripheral auditory fibers revealed for the first time that they undergo experience-dependent developmental refinement, which is impaired by attenuating external sound input. Our results suggest that STARS strategy can be applied for circuit mapping and sparse gene manipulation.