The use of transgenic mice in the investigation of transmissible spongiform encephalopathies.
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Animals↗
Biomedical subjects
T Rülicke
Publications and source records attributed to T Rülicke.
The role of PrP in pathogenesis of experimental scrapie.
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Animals↗
Production and analysis of transgenic mice with ectopic expression of parvalbumin.
Transgenic mice expressing rat parvalbumin under the control of the human metallothionein IIA (MTII A), SV-40 early, and neuron-specific enolase (NSE) promoters were produced. Ectopic expression was analyzed by RNA polymerase chain reaction and RNase protection in combination with immunohistochemistry. From a total of 25 transgenic lines 18 were found to express the transgene. Expression strength and tissue specificity were dependent upon the promoter used and varied considerably among animal lines produced with the same construct. Highest constitutive MT IIA-driven expression was found in lung, liver, heart, and kidney, as well as in brain, and lower amounts of transgene expression were found in spleen, testis, and muscle. Immunohistochemistry of tissue sections of metallothionein-parvalbumin transgenic strain 29 in the non-induced state revealed that ectopic PV mRNA is translated into protein. Short-term induction of the MT IIA promoter by CdSO4 or CdCl2 leads to a shift in tissue specificity and does not increase ectopic expression in tissues where the transgene is active in the noninduced state. As expected the NSE promoter showed highest activity in brain. However, NSE-driven expression could also be detected to various degrees in all investigated tissues. SV-40-dependent PV expression showed no tissue preference and varied considerably among different strains. Except for the observation that the SV-40-PV construct showed lower yields in transgenic production and reduced numbers of positive offspring no obvious impairment of growth or behavior as a consequence of transgenic PV expression could be detected.
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Role of T helper cell precursor frequency on vesicular stomatitis virus neutralizing antibody responses in a T cell receptor beta chain transgenic mouse.
During most immune responses, T cells help antigen-specific B cells to make antibodies against the antigen. One of the contributions of T cells to antibody production is the induction of isotype switching from IgM to IgG, which is the most abundant isotype in blood serum during recall responses. Other features of memory responses are faster kinetics and higher titers of antibody in the serum. What causes a primary immune response to be different from a secondary is not yet very clear and, particularly, the influence of precursor frequencies of T and B cells on memory responses still remains to be answered. To address this issue, a transgenic (tg) mouse line (ADA) was developed; it expresses the beta chain (V beta 2) of a major histocompatibility complex class II-restricted T cell receptor (TcR) specific for the glycoprotein (G) of vesicular stomatitis virus (VSV) serotype Indiana (VSV-IND). These mice exhibit an increased precursor frequency of VSV-specific CD4+ T cells that leads to enhanced neutralizing IgG production against VSV in vivo in unprimed mice. The data indicate that increased frequency of naive specific helper T cells alone may account for features of a memory phenotype such as high titer of antibodies and isotype switching.
Amino Acid Sequence↗
Tissue-specific expression of a FMR1/beta-galactosidase fusion gene in transgenic mice.
Fragile X syndrome is one of the most common genetic causes of mental retardation, yet the mechanisms controlling expression of the fragile X mental retardation gene FMR1 are poorly understood. To identify sequences regulating FMR1 transcription, transgenic mouse lines were established using a fusion gene consisting of an E.coli beta-galactosidase reporter gene (lacZ) linked to a 2.8 kb fragment spanning the 5'-region of FMR1. Five transgenic mouse lines showed lacZ expression in brain, in particular in neurons of the hippocampus and the granular layer of the cerebellum. Expression of the reporter gene was also detected in Leydig cells and spermatogonia in the testis, in many epithelia of adult mice, and in the two other steroidogenic cell types, adrenal cortex cells and ovarian follicle cells. Embryonic tissues which showed strong activity of the reporter gene included the telencephalon, the genital ridge, and the notochord. This expression pattern closely resembles the endogenous one, indicating that the 5' FMR1 gene promoter region used in this study contains most cis-acting elements regulating FMR1 transcription.
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Potential of two-cell mouse embryos to develop to term despite partial damage after cryopreservation.
Approximately 18% of cryopreserved 2-cell mouse embryos of 26 different batches showed various degrees of morphological damage after the freeze-thaw process. Normal and damaged morphology were assessed by light microscopy and the ability of an embryo to develop in vitro to a blastocyst, or to develop to term, after transfer to foster mothers. Using vital stains such as Fluorescein-diacetate (FDA) and 4', 6-Diamidino-2-Phenylindole (DAPI) it was found that in approximately 82% of the cases, both of the 2 blastomeres of the cryopreserved embryos survived the freeze-thaw process; in 10% only one cell survived the process; and in 8% none survived. Normally, only intact 2-cell embryos are considered for transfer. Here it was shown that over 60% of the partially damaged embryos developed in vitro to the blastocyst stage and, of those, 26% developed to term after transfer to suitable foster mothers. Although the inner cell mass (ICM) appeared to remain smaller during culture after the transfer of partially damaged 2-cell stage embryos, no difference during gestation period was found compared with intact embryos.
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Behavioral and anatomical deficits in mice homozygous for a modified beta-amyloid precursor protein gene.
The beta-amyloid precursor protein (beta APP) gene of the mouse was disrupted by inserting into exon 2 a cassette containing a neomycin resistance gene and a putative transcription termination sequence. Contrary to expectation, brain and other tissues from mice homozygous for the insertion still contained beta APP-specific RNA, albeit at a level 5- to 10-fold lower than wild type and lacking the disrupted exon, which had been spliced out. The brain contained shortened beta APP-specific protein at a low level. Mutant mice were severely impaired in spatial learning and exploratory behavior and showed increased incidence of agenesis of the corpus callosum.
Amyloid beta-Protein Precursor↗
Differences in biodistribution of the anti-(carcinoembryonic antigen) murine monoclonal antibody CE-25, its F(ab')2 fragment and its intact mainly human chimeric form CE 4-8-13. Dependence on tumour size and amount of antibody injected.
The effect of the size of the tumour and the amount of antibody injected on the biodistribution of a family of radioiodinated antibodies was studied. The intact mouse anti-(carcinoembryonic antigen) (anti-CEA) monoclonal antibody CE-25, its F(ab')2 fragment and the intact human-mouse chimeric from CE 4-8-13 were evaluated in a model system using the human CEA-producing colon xenograft T 380 grown in nude mice. The relative retention (the percentage of the injected dose per gram of tissue), of mouse mAb and F(ab')2 in tumour and most normal tissues 1 day after injection was independent of the antibody dose; after 4 days the mAb values increased with increasing antibody dose. The relative retention of chimeric mAb increased with increasing antibody dose 1 day after injection and also slightly after 4 days. The relative retention in tumour tissue was lower in bigger xenografts for all antibodies. The relative retention of mouse mAb in small tumours increased from day 1 to day 4; for chimeric mAb this value decreased. In normal tissues the relative retention of mouse mAb decreased from day 1 to day 4, but the relative retention of chimeric mAb in normal tissue dropped rapidly and changed little afterwards. Thus the biokinetics of antibodies is "species"-dependent: foreign, mainly human, chimeric antibody clears faster from normal mouse tissue than mouse antibody and reaches lower concentrations.
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Engagement of the T-cell receptor during positive selection in the thymus down-regulates RAG-1 expression.
We have examined the expression of the recombination activating gene RAG-1 by in situ hybridization to thymi from mice bearing transgenes for the T-cell receptor (TCR) alpha chain, TCR beta chain, or both TCR alpha and beta chains. RAG-1 transcription was found in the thymic cortex of transgenic mice carrying a single TCR alpha- or TCR beta-chain transgene, comparable to normal mice. However, RAG-1 transcription was strikingly reduced in the thymic cortex from transgenic mice carrying both TCR alpha- and beta-chain genes and expressing major histocompatibility complex (MHC) class I (H-2b) molecules necessary for positive selection of the transgenic TCR. In contrast, thymi of transgenic mice also carrying both TCR alpha- and beta-chain genes but expressing MHC molecules (H-2d) that did not positively select the transgenic TCR displayed high levels of RAG-1 transcription. The low thymic RAG-1 expression coincided with high transgenic TCR alpha-chain surface expression and with inhibition of endogenous TCR alpha-chain rearrangement. Our findings suggest that binding of the TCR to self MHC molecules during positive selection down-regulates RAG-1 transcription in cortical thymocytes and thereby prevents further TCR alpha-chain rearrangements.
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Developmental capacities of two-cell mouse embryos frozen by three methods.
The following three methods were evaluated in order to obtain a most efficient freezing protocol for the preservation of two-cell mouse embryos: (a) slow cooling and slow thawing in 1.5 M dimethyl sulfoxide, (b) slow cooling and fast thawing in 1.5 M propanediol (PROH), and (c) ultrarapid freezing and fast thawing in either 3.5 M DMSO or 3.0 M PROH. In the slow-cooling procedures (a and b) ice nucleation (seeding) was induced manually or automatically. With method a, only a slight difference, 51.8% for manual and 58.9% for automatic seeding, was observed in survival rates, while the development to blastocysts was significantly affected: 35.4% with manual and less than 10% with automatic induction (P less than 0.001). Method b gave high survival (86.2%) and developmental rates (69.0%) with manual seeding compared with automatic seeding (20.7 and 9.8%, respectively; P less than 0.001). Using protocol c, higher survival and developmental rates were obtained with DMSO (84.8 and 55.9%) than with PROH (39.8 and 19.4%, P less than 0.001). These results demonstrate that inducing nucleation manually is superior to the use of a highly sophisticated autoseeding system and that method b with manual seeding is most effective in preserving the developmental capacity of two-cell mouse embryos after freezing and thawing. There is evidence that this is also true of human embryo cryopreservation.
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The elimination of mouse hepatitis virus by temporary transplantation of human tumors from infected athymic nude mice into athymic nude rats (rnuN/rnuN).
A nude mouse colony held in an isolation unit was found to harbor MHV despite the fact that all hygienic precautions were taken. The virus spread rapidly causing a high mortality rate predominantly in experimental animals. Moreover, we observed a high percentage of tumor regression in our tumor transplanted mice. Attempts to eliminate the MHV by repeated tumor transplantation into virus-free nude mice were unsuccessful. Since MHV has a limited host range, we transplanted, in parallel, four different lines of embryonic renal tumors (three triphasic nephroblastomas and one malignant rhabdoid tumor of the kidney) from athymic mice into athymic rats and fragments of the same tumors into "fresh" nude mice. All manipulations were performed in isolators. Detection of MHV was done twice by serological examination of six-week-old sentinels. The results showed transmission of MHV infection in the control mice under gnotobiotic conditions as previously found in the normal animal room. On the other hand, there was no evidence of infection, neither in the transplanted nude rats nor after retransplantation of tumors into nude mice. We hypothesize that the virus is harbored in the stromal cells of the murine host but not of the rat host nor in the human tumor cells. Histological comparison showed no alteration of specific tumor morphology in the different hosts.
Animals↗