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Structural organization of the mouse and human GALR1 galanin receptor genes (Galnr and GALNR) and chromosomal localization of the mouse gene.

The neuropeptide galanin elicits a range of biological effects by interaction with specific G-protein-coupled receptors. Human and rat GALR1 galanin receptor cDNA clones have previously been isolated using expression cloning. We have used the human GALR1 cDNA in hybridization screening to isolate the gene encoding GALR1 in both human (GALNR) and mouse (Galnr). The gene spans approximately 15-20 kb in both species; its structural organization is conserved and is unique among G-protein-coupled receptors. The coding sequence is contained on three exons, with exon 1 encoding the N-terminal end of the receptor and the first five transmembrane domains. Exon 2 encodes the third intracellular loop, while exon 3 encodes the remainder of the receptor, from transmembrane domain 6 to the C-terminus of the receptor protein. The mouse and human GALR1 receptor proteins are 348 and 349 amino acids long, respectively, and display 93% identity at the amino acid level. The mouse Galnr gene has been localized to Chromosome 18E4, homoeologous with the previously reported localization of the human GALNR gene to 18q23 in the same syntenic group as the genes encoding nuclear factor of activated T-cells, cytoplasmic 1, and myelin basic protein.

Amino Acid Sequence↗

An integrated genetic and man-mouse comparative map of the DXHXS674-Pdha1 region of the mouse X chromosome.

The genes for ocular albinisim type 1 (OA1) and the Xenopus laevis-like apical protein (APXL) map between amelogenin (AMELX) and the pseudoautosomal boundary in the distal region of the human X chromosome short arm. The mouse homologues, Oa1 and Apxl, have recently been shown to lie proximal to their expected locations on the mouse X chromosome, but their positions with respect to critical gene loci in the vicinity have not been defined. By analyzing recombination events from (Mus musculus x Mus spretus) x M. musculus backcrosses, we have constructed a detailed mouse genetic map that encompasses Oa1, five other genes, and 13 microsatellite loci. The order of genes and evolutionary breakpoints (EB) is defined as centromere-(EB)-(DXHXS674, DXHXS679)-Smcx-(EB)-Oa1-(EB)-Phex (3'-->5')-Pdha1-telomere. Thus Oa1 lies in a region between two previously characterized conserved segments.

Animals↗

Coding sequence and expression patterns of mouse chordin and mapping of the cognate mouse chrd and human CHRD genes.

Chordin is a key developmental protein that dorsalizes early vertebrate embryonic tissues by binding to ventralizing TGF-beta-like bone morphogenetic proteins and sequestering them in latent complexes. Here we report the first characterization of mammalian chordin. The full-length cDNA sequence for mouse chordin is given, and RNA blot analysis shows the murine chordin gene Chrd to be expressed at relatively high levels in 7-day postcoitum mouse embryos and at much decreased levels at later developmental times and in adult tissues. These results imply a major role for chordin during gastrulation of the mammalian embryo. Nevertheless, both murine and human chordin genes are shown to be expressed at readily detectable levels in several fetal and adult tissues, most notably liver and cerebellum, suggesting additional roles in organogenesis and homeostasis. Chrd was mapped to mouse chromosome 16 using interspecific crosses, and the cognate human gene CHRD was localized to human chromosome 3q27 by radiation hybrid mapping.

Amino Acid Sequence↗

Molecular cloning of mouse Lrp7(Lr3) cDNA and chromosomal mapping of orthologous genes in mouse and human.

LRP7 (the HGMW-approved gene symbol for LR3) is a novel member of the low-density lipoprotein receptor (LDLR) family. The unique modular features in both its extracellular and its intracellular regions and functional analysis suggest it to be a multifunctional protein with mitogenic activity and potential ligand-induced signal transduction capability. We describe here the cloning of Lrp7, the orthologue of the human LRP7 gene, from a mouse liver cDNA library and its expression profile in mouse tissues and developmental stages. Lrp7 is highly homologous to the human sequence, with 95% identity at the amino acid level and a perfect conservation of all the recognizable functional domains. A 6-kb mRNA transcript could be detected in all the tissues examined, with the highest expression levels in liver, heart, and lung and the lowest levels in brain and spleen. A similar expression level of a smaller transcript (4.5 kb) was seen at the four embryonic stages examined. We mapped the Lrp 7 gene to mouse chromosome 19B and the LRP7 gene to human chromosome 11q13.4. The LRP7 gene was also localized by radiation hybrid mapping between markers D11S24270 and D11S1975.

3T3 Cells↗

Recognition of HLA-B27 by mouse cytotoxic T-cell clones: a transgenic mouse model.

As a basis for the characterization of mouse T cells involved in the recognition of xenogeneic HLA molecules, a panel of HLA-B27-reactive cytotoxic T-cell clones was generated upon stimulation by cells from HLA-B27-transgenic mice. The HLA-B27-induced T-cell response was found to comprise two categories of clones: some recognizing HLA-B27 independent of H-2 molecules expressed by the target cells (unrestricted clones), others recognizing HLA-B27 in an H-2-restricted manner. The unrestricted clones exhibited diverse specificities, as judged from their various cross-reactivities with other xenogeneic (HLA) or allogeneic (H-2) molecules. In addition, although most of the unrestricted clones were able to react with both mouse and human HLA-B27-transgenic mice. The HLA-B27-induced T-cell which reacted only with HLA-B27-positive mouse, and not human cells. These findings illustrate that both H-2-restricted and unrestricted T cells with diverse specificities contribute to HLA-B27-xenorecognition.

Animals↗

Expression of cholinergic markers in transplants of immature mouse neocortex into adult mouse parietal cortex.

Cerebral cortex of embryonic and newborn mouse was removed and transplanted into adult mouse neocortex to investigate whether the development of cholinergic markers would proceed normally after transplantation. It is shown that both AChE and muscarinic receptors developed in transplanted mouse neocortex. However, while muscarinic receptor binding increased to adult levels in transplants from both pre- and postnatal donors AChE staining intensity only achieved adult levels in tissue from postnatal donors. These results are in accordance with the normal developmental time course of the two different cholinergic markers, since muscarinic receptors appear prenatally in cortex while AChE becomes histochemically detectable after birth. These data suggest that the prenatal donor tissue, unlike the postnatal transplants, lacks an environmental signal for the appearance of AChE stained elements, that is, presumably host AChE fiber ingrowth. Transplantation of immature donor CNS tissue into adult host thus appears to be a useful paradigm to study the regulation of differentiation processes.

Animals↗

In vitro propagation of the scrapie agent. I. Transformation of mouse glia and neuroblastoma cells after infection with the mouse-adapted scrapie strain c-506.

Seven cell lines including glia cells from mouse brains and mouse neuroblastoma cells were infected with the mouse-adapted scrapie strain c-506. During the early in vitro passages, a stimulation of growth was already observed but cellular morphology and differentiation did not alter. Later on, after 12-16 passages, six of the seven infected lines displayed cell proliferation and morphological alterations, suggesting an in vitro morphological transformation. At this stage, differentiation was no longer observed in the scrapie-infected neuroblastoma cells and all the scrapie-infected cells formed two to four times more colonies in liquid medium than the controls, and developed large tridimensional colonies in agar. The part played by the scrapie agent in these changes is discussed.

Animals↗

Toxicodynamics of tumour promoters of mouse skin. II. Binding to protein kinase C of some new diterpene esters and induction of luminol-enhanced chemoluminescence in mouse peritoneal neutrophils.

In binding competition assays using a protein kinase C preparation from mouse brain (particulate fraction) 3H-labelled 12-O-tetradecanoylphorbol-13-acetate (TPA), for a series of new diterpene esters (DTE) the relative binding affinity [rba = Kia(TPA)/Kia(DTE)] in relation to TPA was determined. A wide range of values was noticed, some of the DTE binding more strongly than TPA (rba greater than 1), others binding less strongly than TPA (rba less than 1) In comparative terms, competition for specific binding sites appears to correlate better with irritant than with promoting activity of the DTE. Using mouse peritoneal neutrophils, binding of [3H]-TPA was determined by a modification of the "cold-acetone filter assay"; saturation of high-affinity sites (Kda = 0.2 nM) was obtained at concentrations less than or equal to 1 nM, but there was also evidence for specific binding at "low-affinity" sites (Kda = 26 nM). Induction of chemoluminescence in the presence of luminol in mouse peritoneal neutrophils with a set of DTE usually elecited two peaks; at concentrations greater than or equal to 10 nM DTE a short-lived, "spike-like" response lasting only from 0 to about 5 min (phase A) its followed by a "plateau" response from about 5-120 min (phase B). This latter phase of chemoluminescence stimulation with luminol correlated well with the irritant potential of the DTE used. The sequence of the two phases can be inverted partially by using first TPA at 2,5 nM followed by a quick concentration increase to 100 nM; this indicates two different concentration-dependent events. As regards the intensity of the chemoluminescent response, quantitative but not qualitative differences between DTE were observed, which show some correlation with strong and weak tumour-promoting activity. Inhibition studies suggest the involvement of the myeloperoxidase/H2O2/Cl- system in the luminogenic response; it is suggested that the release of hypochlorite or a closely related oxidant may be instrumental in tumour promotion.

Animals↗

A retrovirus-producing transformed mouse cell line derived from a human breast adenocarcinoma transplanted in a nude mouse.

A transplantable tumor was established in NIH/Swiss/Nu mice from tissue derived from a human breast adenocarcinoma metastatic to the brain. Cultivation of dispersed cells from the third transplant generation of the tumor produced a rapidly growing, high-density culture of fibroblastlike cells. Chromosome and isozyme assays showed these cells to be of mouse origin. The cells behaved as an established line from initial culture. Cells of the tissue culture line, designated NM-1, produced rapidly growing fibrohistiocytomas in nude mice. Electron microscopy revealed that the cells produced large numbers of type C virus particles. Serological, biochemical, and infectivity assays indicated that the retrovirus produced by NM-1 cells is an ecotropic, infective, murine retrovirus antigenically related to, but distinguishable from, Gross and Moloney viruses. The virus did not transform mouse fibroblasts. The data support the conclusion that mouse stromal cells within the transplanted human tumor had undergone malignant transformation and induction to virus replication. The role of the virus in the malignant transformation remains to be clarified.

Adenocarcinoma↗

Phytohemagglutinin-enhanced hybrid colony formation by cells from aged mice: expression of TH 4Mod-1 mouse locus in human-mouse hybrids.

Cells from a continuous human line and freshly isolated cells from old adult mice heterozygous at the Mod-1 locus were fused in the presence of polyethylene glycol (PEG). The production of hybrid cells, as a function of PEG concentration in the presence and absence of phytohemagglutinin (PHA), was measured by cell survival and proliferation on selective medium. The incorporation of PHA into the fusion mixture allowed cell fusion to take place at nontoxic concentrations of PEG. PHA increased the frequency of cell fusion and increased the production of viable hybrid cells from 138- to over 2800-fold depending on cell type. The results suggest that the procedure may have broad application in promoting the fusion of cells sensitive to PEG. Clones were analyzed for isozymes of malic enzyme and glucose-6-phosphate dehydrogenase. The expression of the gene encoding X-linked mouse glucose-6-phosphate dehydrogenase confirmed that the cells were hybrids. These cells lost other mouse isozymes rapidly. In those clones in which the mouse malic enzyme gene was expressed, the product of Mod-1a was detected significantly more frequently than that of Mod-1b.

Aging↗

Suppression of hepatocyte apoptosis and induction of DNA synthesis by the rat and mouse hepatocarcinogen diethylhexylphlathate (DEHP) and the mouse hepatocarcinogen 1,4-dichlorobenzene (DCB).

Nongenotoxic rodent hepatocarcinogens do not damage DNA but cause liver tumours in the rat and mouse, associated with the induction of hepatic DNA synthesis. Previously, we have demonstrated that nongenotoxic hepatocarcinogens such as phenobarbitone and the peroxisome proliferator (PP), nafenopin, also suppress rat hepatocyte apoptosis. The nongenotoxic chemicals 1,4-dichlorobenzene (DCB) and the PP, diethylhexyl phthalate (DEHP), both induce high levels of DNA synthesis in rat liver in vivo, but only DEHP is hepatocarcinogenic in this species. Here, we investigate whether the difference in rat carcinogenicity of these two hepatic mitogens may be due to differences in their ability to suppress hepatocyte apoptosis. In rat hepatocytes in vitro, MEHP (the active metabolite of DEHP) induced DNA synthesis 2.5-fold (P = 0.001) and suppressed 10- and 4-fold, respectively both spontaneous (P = 0.0008) and transforming growth factor beta1 (TGFbeta1)-induced (P = 0.0001) apoptosis. DCB gave a small (1.7-fold) increase in DNA synthesis (P = 0.03) and a small (1.7- to 2-fold) suppression of both spontaneous (P = 0.022) and TGFbeta1-induced (P = 0.015) apoptosis. We next analysed the induction of DNA synthesis and the suppression of apoptosis in rat liver in vivo. Both DEHP and DCB were able to induce DNA synthesis although, as seen in vitro, the induction by DCB (4.2-fold; P = 0.023) was less marked than that with DEHP (13.4-fold; P = 0.007). Similarly, DEHP and DCB were both able to suppress rat hepatocyte apoptosis in vivo but the magnitude of the suppression was comparable; apoptosis was reduced to undetectable levels in four out of five animals with DCB and three out of five with DEHP. Since both chemicals suppressed apoptosis and induced DNA synthesis in rat liver but, overall, DCB was less potent, the disparate hepatocarcinogenic potential of these two chemicals could arise from differences in the magnitude of growth perturbation. To test this hypothesis, we repeated the studies in mouse, a species where both DCB and DEHP are hepatocarcinogenic. Both in vitro and in vivo, DCB and DEHP/MEHP were able to suppress apoptosis and induce hepatocyte DNA synthesis in the mouse with comparable potencies. The data support the hypothesis that the carcinogenicity of nongenotoxic hepatocarcinogens is associated strongly with the ability to perturb hepatocyte growth regulation. However, the ability to effect such changes is not unique to nongenotoxic carcinogens and is common to some noncarcinogenic chemicals, such as DCB, suggesting that the growth perturbation may need to exceed a threshold for carcinogenesis.

Animals↗

Rapid blood clearance of mouse IgG2a and human IgG1 in many nude and nu/+ mouse strains is due to low IgG2a serum concentrations.

We reported previously that the blood clearance of injected mouse IgG2a was extremely rapid in many strains of nude and nu/+ mice. In an attempt to determine the cause of this phenomenon, the levels of endogenous IgG2a in the blood of these mice was assayed. It was found that the serum level of IgG2a was extremely low in many of these mice, below 50 microg/ml, which is 20-100 times lower than the expected normal value. Great heterogeneity between individual mice was observed in their blood level of IgG2a, and there was an excellent correlation between low blood IgG2a levels and rapid clearance of injected IgG2a. Thus, the blood IgG2a levels are so low that a novel, previously undescribed effect occurs, namely the rapid clearance of small amounts of injected IgG2a. The clearance is due primarily to binding sites in the spleen and liver. The low level of endogenous IgG2a is not due to the lack of a thymus, since it occurs in nu/+ as well as nude mice, but can probably be attributed to the very clean environment in which these mice are raised. In assays of sera from approximately 50 mouse strains, low IgG2a levels were found in all nude colonies and also in some normal mouse strains. Some nude mice displayed relatively normal IgG2a clearance rates despite having low levels of endogenous IgG2a. In repeated bleedings of individual mice, IgG2a levels were found to fluctuate greatly. A similar clearance effect was observed with a human IgG1 Ab injected into mice. This rapid clearance of injected IgG, of certain subclasses, represents a practical problem for many experiments in which antibodies are used for diagnosis or therapy, and several methods of circumventing the problem are discussed.

Animals↗

Localisation of centromeric proteins to a fraction of mouse minor satellite DNA on a mini-chromosome in human, mouse and chicken cells.

Centromeres are required for faithful segregation of chromosomes in cell division. It is not clear how centromere sites are specified on chromosomes in vertebrates. We have previously introduced a mini-chromosome, named ST1, into a variety of cell lines including human HT1080, mouse LA9 and chicken DT40. This mini-chromosome, segregating faithfully in these cells, contains mouse minor and major, and human Y alpha-satellite DNA repeats. In this study, after determining the organisation of the satellite repeats, we investigated the location of the centromere on the mini-chromosome by combined immunocytochemistry and fluorescence in situ hybridisation analysis. Centromeric proteins were consistently co-localised with the minor satellite repeats in all three cell lines. When chromatin fibres were highly stretched, centromeric proteins were only seen on a small portion of the minor satellite repeats. These results indicate that a fraction of the minor satellite repeats is competent in centromere function not only in mouse but also in human and chicken cells.

Animals↗

Specific interaction between mouse liver non-histone chromosomal proteins and mouse DNA demonstrated by a sequential DNA-protein binding procedure.

The binding of mouse liver chromosomal proteins to DNA has been investigated using the nitrocellulose filter binding technique. Careful purification of the DNA involving nuclease S1 digestion and prefiltration through a nitrocellulose filter is used to reduce background binding in the absence of protein to less than 1%. Procedures involving direct binding of protein to labeled DNA, competition of binding of labeled DNA by unlabeled DNA, and dissociation of DNA . protein complexes with time do not indicate significant preference for binding to mouse DNA relative to Escherichia coli DNA. This specificity is demonstrated much more clearly by a novel type of procedure, which we call a sequential binding procedure. In this procedure non-specific binding proteins are sequestered by incubation with an excess of unlabeled E. coli DNA prior to addition of labeled DNA. Under these conditions, labeled mouse DNA is bound to filters to a 3- to 4-fold greater extent than labeled E. coli DNA.

Animals↗

Binding of low-density lipoproteins from chicken egg yolk to mouse anti-phospholipid B cells which include B cells against bromelain-treated mouse erythrocytes.

Low-density lipoproteins from chicken egg yolk (EyLDL), which are reactive with mouse antibodies against bromelain-treated mouse erythrocytes (BrMRBC), were conjugated with fluorescein isothiocyanate (FITC). FITC-EyLDL could bind specifically to mouse anti-phospholipid B cells, which comprised all the BrMRBC-rosette-forming cells and anti-BrMRBC lipopolysaccharide-reactive B cells, C3H/He mice at 12 weeks of age had, approximately, 7 x 10(5) EyLDL-binding cells in the peritoneal cavity, 3 x 10(5) EyLDL-binding cells in the pleural cavity, and 3 x 10(5) EyLDL-binding cells in the spleen. In ontogeny, the numbers of EyLDL-binding cells in the peritoneal cavity expanded greatly by 4 weeks. Other normal strains of mice and C3H/HeJ mice at 12 weeks of age had 4-7 x 10(5) EyLDL-binding cells in the peritoneal cavity; the numbers were large (19 x 10(5] in NZB mice, rather small (2 x 10(5] in MRL/lpr mice, and very small (0.1 x 10(5] in CBA/N mice. In some of various strains of mice at 12 months of age, more than 20% of peritoneal cells were EyLDL-binding cells; in particular, all of five older NZB mice examined had more than 10(7) EyLDL-binding cells in the peritoneal cavity.

Age Factors↗

Rat (and mouse) monoclonal antibodies. VIII. ELISA measurement of Ig production in mouse hybridoma culture supernatants.

We describe a rat monoclonal antibody (MAb)-based solid-phase immunoenzymometric assay for the quantification of mouse hybridoma culture supernatant immunoglobulins (Igs). This assay involves the use of two rat MAbs, LO-MK-1 and LO-MK-2, which bind distinct mouse kappa light chain epitopes expressed by all murine kappa Igs. The assay permits reliable measurement of all murine kappa IgG subclasses in the 2-120 ng/ml range and murine kappa IgM class in the 2-30 ng/ml range. The intra- and interassay coefficients of variation in the measurement of Ig in mouse hybridoma culture supernatants averaged 7.5% and 5% respectively. The assay is simple, reproducible, rapid and does not require specific equipment. It is of potential value to all laboratories engaged in hybridoma technology.

Animals↗

DNA-repair kinetics and the sensitivity of cells to X-ray-induced chromosome aberrations: a mouse myeloid leukemia cell line and normal mouse bone marrow cells.

The frequency of X-ray-induced chromosome aberrations in G1 ML-1 mouse myeloid leukemia cells and normal mouse bone marrow cells increased with post-irradiation incubation with the DNA-repair resynthesis inhibitor 1-beta-D-arabinofuranosylcytosine (araC), but the frequency of aberrations in the leukemic cells increased with quite a different time response compared to the normal cells. Irradiated normal mouse bone marrow cells had a rapid increase in the frequency of chromosome exchanges and deletions with increasing araC incubation time, for example, an increase was observed with 0.5 h araC incubation. In contrast, the ML-1 cells did not have a significant increase in aberrations until 1-2 h post-irradiation incubation with araC. These results suggest that the ML-1 cells, per unit time, initially undergo less repair of the X-ray-induced DNA damage that can be converted into chromosome aberrations. We previously showed that the ML-1 cells have a higher frequency of X-ray-induced chromosome aberrations compared to normal cells and the results presented here indicate that a slower rate of repair resynthesis is contributing to the increased sensitivity of the ML-1 cells.

Animals↗

Activity of iPMS and nPMS in mouse bone marrow micronucleus assays: comparison with mouse dominant lethal assay data.

isoPropyl methanesulphonate (iPMS) and its n-propyl analogue (nPMS) are shown to be active in mouse bone marrow micronucleus assays using male CBA, male and female (C3H/El X 102/E1)Fl and male and female Muta Mouse mice. iPMS was significantly more active than nPMS. No significant strain or gender differences were observed. These findings reflect the differences reported earlier for these two chemicals in mouse dominant lethal mutation assays. The earlier described dominant lethal assay data are represented schematically and discussed.

Alkylating Agents↗