1
|
The chakragati mouse shows deficits in prepulse inhibition of acoustic startle and latent inhibition. Neurosci Res 2008; 60:281-8. [DOI: 10.1016/j.neures.2007.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Revised: 11/13/2007] [Accepted: 11/16/2007] [Indexed: 01/08/2023]
|
2
|
Dawe GS, Ratty AK. Thechakragati mouse: A mouse model for rapidin vivo screening of antipsychotic drug candidates. Biotechnol J 2007; 2:1344-52. [PMID: 17886239 DOI: 10.1002/biot.200700145] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The chakragati (ckr) mouse is a serendipitously discovered insertional transgenic mutant that exhibits circling and hyperactivity. Studies of social behavior, sensorimotor gating and ventricular anatomy suggest that the ckr mouse models aspects of schizophrenia. The underlying genetic and neurodevelopmental mechanisms remain to be elucidated but appear to result in a hemispheric asymmetry in striatal D(2)-like dopamine receptors. The circling is inhibited by administration of antipsychotic drugs and so lends itself to in vivo prospective screening for novel molecules with antipsychotic-like activity. Using the ckr mouse we have applied an in vivo first approach to screening for antipsychotic drug candidates. This offers the advantage of early indication of central nervous system bioavailability and potential toxicological concerns. Additionally, in vivo first screening in the ckr mouse is not biased by any particular neurotransmitter hypothesis of the disease, and so has the potential to identify compounds modifying the behavioral output by novel mechanisms of interaction with the underlying brain circuitry. Thus, in contrast to the classical strategy of hypothesis-driven in vitro screening for drugs fitting a "receptor model" of the disease, the ckr mouse screen has greater potential to identify lead molecules for a new generation antipsychotics with novel mechanisms of action.
Collapse
Affiliation(s)
- Gavin S Dawe
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | | |
Collapse
|
3
|
Uh M, Khattra J, Devlin RH. Transgene constructs in coho salmon (Oncorhynchus kisutch) are repeated in a head-to-tail fashion and can be integrated adjacent to horizontally-transmitted parasite DNA. Transgenic Res 2006; 15:711-27. [PMID: 16952013 DOI: 10.1007/s11248-006-9016-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2006] [Accepted: 05/19/2006] [Indexed: 11/24/2022]
Abstract
Currently, little information is available regarding the molecular organization of integrated transgenes in genetically-engineered fish. We performed a detailed structural analysis of an inserted transgene in one strain (M77) of transgenic coho salmon (Oncorhynchus kisutch) containing a salmon growth hormone gene construct (OnMTGH1). Microinjected DNA was found to have inserted into a single site in the coho salmon genome, and was organized with four complete internal copies and two partial terminal copies of the OnMTGH1 construct. All construct copies were organized in a direct-tandem (head-to-tail) repeat fashion in strain M77 and five additional strains (one also possessed a second recombinant junction fragment). For strain M77, the junctions between the transgene insert and the insertion point within the wild-type genome were cloned from strain-specific cosmid libraries and sequenced, revealing that the transgene insertion was accompanied by a deletion of 587 bp of wild-type DNA as well as a small insertion (19 bp) of unknown DNA upstream and a 14 bp direct- tandem duplication of sequence downstream. Upstream and downstream wild-type DNA sequence contained several repetitive sequence elements based on Southern blot analysis and homology to repetitive sequences in GenBank. In the downstream flank, a pseudogene sequence was also identified which has high homology to the CA membrane protein gene from Schistosoma japonicum, a parasite closely related to Sanguinicola sp. parasites which infect salmonids. Whether the presence of an inserted transgene and the presence of potentially horizontally-transmitted DNA are indicative of a genomic region with a predisposition for insertion of foreign DNA requires further study. The information derived from this transgene structure provides information useful for comparison to other transgenic organisms and for determination of the mechanism of transgene integration in lower vertebrates.
Collapse
Affiliation(s)
- Mitchell Uh
- Centre for Aquaculture and Environmental Research, Fisheries and Oceans Canada, West Vancouver, BC, Canada
| | | | | |
Collapse
|
4
|
Torres G, Meeder BA, Hallas BH, Spernyak JA, Mazurchuk R, Jones C, Gross KW, Horowitz JM. Ventricular size mapping in a transgenic model of schizophrenia. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2005; 154:35-44. [PMID: 15617753 DOI: 10.1016/j.devbrainres.2004.08.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/03/2004] [Indexed: 12/16/2022]
Abstract
Genetically engineered mice have been generated to model a variety of neurological disorders. The chakragati (ckr) mouse is beginning to provide valuable insights into the structural brain changes underlying certain manifestations of schizophrenia. For instance, these mice show enlargement of the lateral ventricles, an abnormality frequently reported as a structural aberration in the schizophrenic brain. As neither the anatomical pattern nor the timing of this ventricular enlargement is known, we used magnetic resonance imaging (MRI) techniques to non-invasively visualize the development of the ventricular system in 5-, 10- and 30-day-old ckr pups. High-resolution MR images obtained from these mutants showed a progressive enlargement of the lateral ventricles, starting at day 5 of postnatal life. These emerging deficits were associated with abnormalities in mid-saggital corpus callosum area and thickness, particularly in 30-day-old adolescent animals. At this time of development, aberrant behaviors that mimic certain symptoms of schizophrenia also appeared in ckr mice suggesting that structural changes in ventricular size predates the onset of psychotic-like behaviors. These results are viewed as further indication that pre- and peri-natal disturbances of the ventricular system and adjacent neural regions may be important pathogenic factors in schizophrenia. Application of MRI to the ckr mouse is relatively new but has great potential for clarifying the relationship between brain structure changes and genetically induced vulnerabilities to psychoses.
Collapse
Affiliation(s)
- German Torres
- Department of Neuroscience, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, New York 11568, USA
| | | | | | | | | | | | | | | |
Collapse
|
5
|
Torres G, Hallas BH, Vernace VA, Jones C, Gross KW, Horowitz JM. A neurobehavioral screening of the ckr mouse mutant: implications for an animal model of schizophrenia. Brain Res Bull 2004; 62:315-26. [PMID: 14709346 DOI: 10.1016/j.brainresbull.2003.09.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A model of schizophrenia, the chakragati (ckr) mouse was serendipitously created as a result of a transgenic insertional mutation. The apparent loss-of-function of an endogenous gene produced mice that, when homozygous, displayed an abnormal circling behavior phenotype. To determine whether this phenotype could be corrected by atypical antipsychotics, we compared the effects of clozapine and olanzapine on rotational turns and hyperactivity. Both of these drugs successfully ameliorated circling behavior and hyperactivity in homozygous mice. The increased motor activity of these mutant mice was both qualitatively and quantitatively similar to that observed in wild-type animals treated with dizocilpine, an N-methyl-D-aspartate receptor antagonist that produces behaviors resembling positive symptoms of schizophrenia. Mice either homozygous or heterozygous for the mutation also displayed enlargement of the lateral ventricles, which was accompanied only in the homozygous genotype by a loss of individual myelinated axons in the striatum and agenesis of the corpus callosum. These structural brain deficits were selective in that the nigro-striatal dopamine system was normal in these homozygous mice. In addition, two types of interneurons in the neostriatum, namely those producing acetylcholine or nitric-oxide synthase were also devoid of significant structural abnormalities. These results indicate that the ckr mouse mutant could be used as a possible animal model to study the pathophysiology of schizophrenia and suggest possible strategies for treating the behavioral aspects of this brain disease.
Collapse
Affiliation(s)
- German Torres
- Department of Neuroscience, New York College of Osteopathic Medicine of New York Institute of Technology, Old Westbury, NY 11568, USA
| | | | | | | | | | | |
Collapse
|
6
|
Abrahams BS, Chong ACO, Nisha M, Milette D, Brewster DA, Berry ML, Muratkhodjaev F, Mai S, Rajcan-Separovic E, Simpson EM. Metaphase FISHing of transgenic mice recommended: FISH and SKY define BAC-mediated balanced translocation. Genesis 2003; 36:134-41. [PMID: 12872244 DOI: 10.1002/gene.10205] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The evolving trend to use larger transgenes and their associated increased chance of unexpected genetic events mandates more careful characterization of transgenic mice. In characterizing our five new mouse strains transgenic for the BAC, bEMS4, we have identified the highest copy number reported to date: the stable incorporation of approximately 40 copies of a 194-kb expressed transgene in a single insertion site. We caution, however, that standard molecular techniques failed to identify a balanced translocation in another strain, and an inappropriate site of insertion in a third. Molecular cytogenetic analysis using metaphase FISH was the minimum level of characterization needed to reveal these unexpected genetic events. In addition, we combined FISH and SKY to identify the transgene at the breakpoints of the balanced translocation, t(3;9). This is the first description of a BAC-mediated chromosomal rearrangement and the first application of SKY to identify transgene-induced chromosomal rearrangements.
Collapse
Affiliation(s)
- Brett S Abrahams
- Graduate Program in Neuroscience, Department of Medical Genetics, University of Columbia, Vancouver, British Columbia, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Fuji JI, Fukuda R, Imoto F, Ooshima Y. New behavioral mutant rat exhibiting circling behavior (clx) controlled by a sex-linked recessive gene. Congenit Anom (Kyoto) 2002; 42:187-93. [PMID: 12502898 DOI: 10.1111/j.1741-4520.2002.tb00892.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A male rat showing intermittent circling behavior was discovered among the Jcl:Wistar rats in our laboratories, and among its backcross offspring individuals showing the same behavior were found. The abnormalities in these animals were characterized by intermittent circling behavior (walking and/or running in circles) and head tossing with the neck twisted. No abnormalities were observed in fertility, delivery or pup mortality. The results of mating experiments indicated that the circling behavior phenotype is controlled by a single sex-linked recessive gene, and the mutant was named "circling behavior linked to X-chromosome (gene symbol: clx)." This circling behavior mutant is considered to be different from the previously reported mutants, the behavior in all of which has been found to be autosomally inherited. Sib-mating is continuing to produce an inbred strain with this newly discovered circling behavior mutant gene.
Collapse
Affiliation(s)
- Jun-Ichiro Fuji
- Hikari Branch, Drug Safety Research Laboratories, Pharmaceutical Research Division, Takeda Chemical Industries, Ltd., Hikari, Yamaguchi 743-8502, Japan.
| | | | | | | |
Collapse
|
8
|
Smiraglia DJ, Wu C, Ellsworth MK, Ratty AK, Chapman VM, Gross KW. Genetic characterization of the chromosomal rearrangements that accompany the transgene insertion in the chakragati mouse mutant. Genomics 1997; 45:572-9. [PMID: 9367682 DOI: 10.1006/geno.1997.4976] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have previously reported that the circling phenotype of the chakragati mouse segregates with the transgene integration event as an autosomal recessive trait. It was unclear, however, whether the phenotype was linked to the transgene integration point near D16Ros1 or to a potential disruption at D16Ros2, 10 cM away. We report here that animals recombinant between D16Ros1 and D16Ros2, homozygous for the transgene insertion at D16Ros1, but wildtype for D16Ros2, do indeed show the phenotype. We conclude that any potential disruption at the D16Ros2 locus is not responsible for the circling phenotype. We further show that recombination between D16Ros1 and D16Ros2 occurs at a greatly reduced level in the chakragati mouse compared to wildtype strains. Detailed genetic analysis of recombinants indicates that the proximal-most 4.5 cM shows no recombination in over 1400 meioses. We propose that this is due to an inversion in this region, and we genetically define the proposed distal inversion break point to a 1.3-cM region between D16Mit63 and D16Mit169.
Collapse
Affiliation(s)
- D J Smiraglia
- Cell and Molecular Biology Department, Roswell Park Cancer Institute, Buffalo, New York, 14263, USA
| | | | | | | | | | | |
Collapse
|