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Detection of Escherichia coli enterotoxins by using mouse adrenal cell and suckling mouse assays: collaborative study.

The ability of 10 Escherichia coli strains to produce heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT) was determined by 8 analysts in a collaborative study. The suckling mouse model and the mouse adrenal cell line (Y-1) tests were used to detect ST and LT, respectively. Cultures for assay were grown 24 h in casamino acid-yeast extract-trace salts broth at 37 degrees C in a shaker incubator at 250 rpm. Cell-free culture broth prepared by centrifugation and filtration was divided into 2 portions: One was heated for 30 min and used both for ST assay and as a heated control for LT assay; the other was used unheated for LT assay. Results were expressed as positive for ST, positive for LT, positive for ST and LT, or negative for both ST and LT; percent of correct estimates was calculated for each culture for each analyst. At the 95% confidence interval, the overall correct results were 96.3 +/- 2.9 and 95.0 +/- 3.4% for ST and LT, respectively. The test performances thus were satisfactory for detecting ST and LT produced in vitro by E. coli. The method has been adopted official first action.

Adrenal Glands↗

PubMed1984

Purification of a factor inducing differentiation of mouse myeloid leukemic M1 cells from conditioned medium of mouse fibroblast L929 cells.

A procedure is described for purification of a factor (D-factor)-inducing differentiation of mouse myeloid leukemic cells (M1) into macrophages from serum-free mouse L929 cell-conditioned medium. The procedure included ammonium sulfate precipitation, DEAE-cellulose, Sephadex G-200 and phenyl-Sepharose column chromatographies, reverse-phase high-performance liquid chromatography on a C18 hydrophobic support, and high-performance liquid chromatography on a gel-filtration column. The purified factor gave a single band of protein with a molecular weight of 62,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis which coincided with biological activity. Its half-maximal concentration for inducing differentiation of M1 cells into macrophages was 1.7 X 10(-11) M. Even at 2.6 X 10(-9) M, it did not induce colony formation of normal bone marrow cells, suggesting that it was distinct from the growth factor for normal precursors of macrophages and/or granulocytes.

Animals↗

PubMed1983

The extent of self-MHC restriction of cytotoxic T cells in nude mice varies from mouse to mouse.

There are conflicting results as to whether the response of athymic nude mice to TNP-modified self determinants is or is not H-2 restricted. We cultured spleen cells from 29 individual RNC (H-2k) nude mice with TNP-modified self determinants and tested the cultures for their ability to lyse TNP-modified self (RNC-TNP) and TNP-modified allogeneic (BALB/c-TNP) target cells. Each mouse was stimulated by two different protocols: either by the addition of TNP-modified irradiated nu/+ spleen cells or by TNP modification of the nude responder cells without addition of other cells. All mice could lyse RNC-TNP targets and about one-half could also lyse BALB/c-TNP targets, i.e., there was a 50:50 division between restricted and unrestricted responses. The magnitude of the response against RNC-TNP and whether the response was restricted were both independent of the method of stimulation. We conclude that H-2 restriction in these mice is imposed by an as yet unidentified environmental influence that can vary from one nude mouse to the next. The influence appears to act through negative selection because the modified self response is, if anything, higher in mice showing an unrestricted response.

Animals↗

PubMed1984

Effect of mouse interferon on the expression of a porcine major histocompatibility gene introduced into mouse L cells.

Mouse L cells transformed with a swine genomic clone, which encodes a major histocompatibility (MHC) antigen (SLAd), stably express SLAd on their surface. Mouse interferon (IFN) markedly enhances the expression of the heterologous SLAd as well as endogenous H-2k antigens in two independent transformants, as measured by flow microfluorometry. The expression of an unrelated surface antigen, gp70, is not affected. The increased expression of SLAd antigens is the result of an increased pool of SLA mRNA in IFN-treated cells. In vitro nuclear transcription experiments suggest that this increased accumulation of SLA mRNA results largely from an enhanced transcription of the heterologous SLA gene. The effect of IFN is not restricted to the MHC coding sequences; the transcription of two DNA sequence elements flanking the SLA gene, which are constitutively expressed in one L cell transformant, is also enhanced by IFN. In contrast, in another transformant these same flanking sequences are not transcribed and do not respond to IFN. The results suggest that IFN enhances the transcription of MHC coding and the flanking sequences that are expressed in its absence, but it does not appear to induce do novo transcription of the silent flanking genes examined.

Animals↗

PubMed1982

Effects of immunoglobulin structure on Fc receptor binding: a mouse myeloma variant immunoglobulin with a gamma 2b-gamma 2a hybrid heavy chain having a complete gamma 2a Fc region fails to bind to gamma 2a Fc receptors on mouse macrophages.

We report here the primary structure of an immunoglobulin heavy chain synthesized by ICR 16, a variant of the MPC 11 mouse myeloma cell line. The ICR 16 heavy chain is a gamma 2b-gamma 2a hybrid, consisting of the CH1 domain of gamma 2b and the hinge, CH2 and CH3 domains of gamma 2a subclasses. The genetic mechanism by which ICR 16 occurred may be recombination, based on homologies in both coding and intervening sequences in gamma 2b and gamma 2a constant region genes. Although the Fc fragment of ICR 16 is completely gamma 2a-like and has been shown to bind to gamma 2a Fc receptors on mouse macrophages, the intact H2L2 molecules is unable to do so. Such an observation underscores the crucial role that conformation may play in the ability of immunoglobulins to carry out biologic functions.

Amino Acid Sequence↗

PubMed1983

A comparison of the cell kinetics of pre-implantation mouse embryos from two different mouse strains.

The progression of pre-implantation mouse embryos through the first, second and third embryonic cell cycle was investigated cytofluorometrically. In contrast to most of the previous studies, the ova were spontaneously ovulated and the mating period of the ova donors was short (06.00-09.00 hours). The embryonic cells proceeded through the first, second and third cell cycle as a cohort. Thus it was possible to estimate the duration of the cell cycle phases directly from the DNA histograms. The length of the cell cycle phases differed between the embryos of the two different mouse strains. The most pronounced differences were found for the G2 + M phases (first cell cycle: 8 hr for Strain I and 5 hr for Strain II; second cell cycle: 11.5 hr and 14 hr respectively). However, in accordance with previous investigations, common features of the early pre-implantation cell kinetics were also observed: increasing length of the S phases from the first to the second cell cycle and very short G1 phases in the second and third cell cycle. The cell proliferation of the embryos of both strains after the third cell cycle was characterized by exponential growth. The proliferation rate was higher in Strain I embryos than in Strain II embryos (steeper increase of the growth curve). At the end of the pre-implantation development (hatched blastocysts), the growth curves of both strains decreased. The differences concerning the durations of the cell cycle phases and the proliferation rates are considered to be strain specific. It is suggested that the differences in the pre-implantation cell kinetics which have been described generally reflect the strain specificities more than different investigational methods and/or different grades of synchrony of early pre-implantation embryos.

Animals↗

PubMed1982

Uptake of methylmercury and inorganic mercury by mouse glioma and mouse neuroblastoma cells.

Methylmercury was taken up preferentially by mouse glioma and mouse neuroblastoma cells relative to inorganic mercury. Methylmercury uptake was depressed by lowering the cellular ATP level or the incubation temperature, while the uptake of inorganic mercury was not affected by these treatments. When the cells were treated with reagents such as cytochalasin B, colchicine and vinblastine which are known to affect membrane permeability, changes in permeability to methylmercury caused by these reagents were markedly different from those to inorganic mercury. Inorganic mercury above 2 x 10(-5)M caused the release of 2-deoxyglucose trapped in the cells and the amount of inorganic mercury taken up by the cells increased markedly at higher concentrations. Inorganic mercury thus appeared to move into the cells after disrupting the membrane barrier, while methylmercury can penetrate the cells without any noticeable damage to the barrier.

Animals↗

PubMed1982

Effects of conditioned medium from non-differentiating or differentiated mouse myeloid leukemia cells on formation of macrophage-granulocyte colonies of normal mouse bone marrow cells.

The effects of conditioned media (CM) of various clones of mouse myeloid leukemia cells (M1) on colony formation of normal mouse bone marrow cells were examined under various conditions. The CM of sensitive M1 cells, which could be induced to differentiate into macrophage-like and granulocyte-like cells by various factors stimulating the differentiation (D-factor), slightly inhibited colony formation of normal bone marrow cells by colony stimulating factor (GM-CSF). The CM of resistant M1 cells, which were resistant to the induction of differentiation even with high concentrations of the D-factor, significantly inhibited the colony formation of bone marrow cells by GM-CSF. The inhibitory activity of the CM from resistant cells decreased on treatment of the cells with a low concentration of actinomycin D, which could sensitize the resistant cells to induction of differentiation. The CM of differentiated sensitive M1 cells induced by dexamethasone stimulated the colony formation of bone marrow cells without exogenously added GM-CSF. Most of the GM-CSF activity in the CM was separated from the D-factor of M1 cells by Sephadex G-75 gel filtration.

Animals↗

PubMed1981

Effect of tunicamycin on production by mouse fibroblast L929 cells of the factor-stimulating differentiation of mouse myeloid leukemic cells and the colony-stimulating factor.

Mouse myeloid leukemic M1 cells can be induced to differentiate into macrophages and granulocytes in vitro by a factor(s) stimulating differentiation of the cells (D-factor), which is suggested to be a glycoprotein. On the other hand, growth and differentiation of normal precursor cells of macrophages and granulocytes can be stimulated by a glycoprotein termed colony-stimulating factor (CSF). Mouse fibroblast L929 cells were found to produce both the D-factor and CSF. The properties of the D-factor and CSF and the roles of carbohydrates in the molecules of these factors were examined using tunicamycin, a specific inhibitor of asparaginase-linked glycosylation. Although both the D-factor and CSF were produced by L-cells in usual medium containing fetal calf serum, production of D-factor, but not CSF, was reduced by omission of serum from the medium. The activity of the D-factor was slightly decreased by treating the L-cells with tunicamycin (0.5 microgram/ml) in the presence of 2% fetal calf serum, without any decrease in CSF activity. Conditioned medium of L-cells incubated with or without tunicamycin was fractionated by gel filtration on a Sephadex G-200 column. Normal D-factor appeared as a single peak with an apparent molecular weight of 67,000. D-factor produced in the presence of tunicamycin had an apparent molecular weight of 25,000. On the other hand, most of the CSF was eluted in the void volume, even when it was produced in the presence of tunicamycin. The D-factor produced in the presence of tunicamycin was more sensitive than normal D-factor was to trypsin or heat treatment at 70 degrees. The CSF produced in the presence of tunicamycin was resistant to these treatments. These results indicate that the D-factor is distinct from CSF. Furthermore, the results suggest that the D-factor produced by L-cells is also a glycoprotein and that, although carbohydrate is not essential for production or activity of the D-factor, it contributes to stabilizing the protein portion of D-factor.

Animals↗

PubMed1982

Mouse red blood cell rosettes: human B and some T lymphocytes express receptors for mouse erythrocytes in the presence of Ficoll.

Inclusion of 14% Ficoll in the assay of rosette formation of human lymphocytes with mouse red blood cells (RBC) markedly enhances the cellular interaction. Both the strength of the rosettes (number of attached RBC) and the number of reacting lymphocytes are increased significantly, irrespective of the lymphocyte source--blood, lymph node and tonsil. In the presence of Ficoll, most of the sIg-bearing B lymphocytes [expressing receptors for Fc(IgG) and/or C3] and a significant number of the sheep RBC-rosetting T lymphocytes (particularly the nylon wool non-adherent subset from the tonsil), express receptors for the mouse erythrocyte.

Age Factors↗

PubMed1978

Solubilization of the H-2 antigen from hybrid cells of mouse mammary ascites tumor and mouse L cells at high cell concentrations in detergent.

Radioiodinated membrane components of L-FM3ANo.2 cells, which were hybrid cells of C3H/He mouse mammary ascites tumor and mouse L cells, were solubilized with non-ionic detergent Nonidet P-40 and immunoprecipitated with anti-H-2k sera. The immune complexes were reduced and subjected to SDS-polyacrylamide gel electrophoresis. When the cells were lysed at a concentration of 2 X 10(7) cells/ml in 0.5% NP-40 buffer, only H-2 molecules including beta2-microglobulin were precipitated, but when the cells were lysed at a concentration of 8 X 10(7) cells/ml in 0.5% NP-40 buffer, two labeled components corresponding to molecules of 105,000 daltons and 85,000 daltons, respectively, were observed in addition to the characteristic radioactive peaks of the H-2 antigen. Dilution of the latter detergent lysate with phosphate buffered saline exhibited no effect on the detection of the two additional components, while further treatment of the lysate with NP-40 buffer abrogated them to be detected. The results indicate that the H-2 molecules were solubilized as physical complexes with certain membrane components of L-FM3ANo.2 cells when the cells were lysed at high cell concentrations in detergent, and suggest that the H-2 molecules and certain membrane components may be physically associated with each other on the cell surface of L-FM3ANo.2 cells.

Animals↗

PubMed1981

Ultrastructural characterization of a mouse melanoma cell line, a mouse fibroblastic cell line, and hybrids between them.

This report describes a transmission electron microscopic study on hybrids between subhexaploid mouse melanoma cells and subtetraploid mouse fibroblasts. The melanoma cell line was heterogeneous in terms of pigment production, but all cells contained melanosomes, although in different stages of development. Characteristic features of the fibroblasts included the cytoskeleton, endocytic vesicles, and occurrence of dilated cisternae of granular endoplasmic reticulum. Despite the gene dosage in favour of the melanoma parent cell, the hybrids were devoid of melanosomes, and their phenotype was typically fibroblastic in character.

Animals↗

PubMed1978

Studies on cell surface antigens of mouse leukemic and normal lymphocytes. I. Categories of cell surface antigens on mouse leukemia and their serological identification.

Analysis of cell surface antigens is most advanced with mouse tumors, mainly because of the availability of inbred strains with known susceptibility to naturally occuring or induced tumors. The development of serological techniques enables identification of gene products which are expressed on the surface of tumor cells. The naturally occuring and induced leukemias in mice are a particularly suitable model for the studies of surface antigens, because the leukemia cells can be easily obtained in cell suspension, they are highly sensitive to cytotoxic antibodies and they can be compared, because of common origin, with normal thymocytes and lymphocytes. In addition to conventional alloantigens (MHC), differentiation alloantigens (Thy, Tl and Lyt) viral structural (MuLV and occasionally MMTV) also viral related cellular antigens are detectable. Various categories of cell surface antigens and antisera defining their presence on the surface of mouse lymphocyte produced and used for studies carried on in the Department of Tumor Immunology are listed and discussed in the present and following papers (No. I-V).

Animals↗

PubMed1994

Functional expression of a mouse growth hormone receptor cDNA in transfected mouse L cells.

A cDNA encoding a full-length mouse (m) growth hormone receptor (GHR) derived from 3T3 F442A cells was amplified by RT-PCR and cloned into a mammalian expression vector. A mouse L cell line (mGHR1.6), which expresses high levels of full-length mGHR, was established. A mGHR-specific mRNA of approx 2.8 kb was found in these cells. Ligand binding studies showed that mGHR 1.6 cells were capable of binding 125I-hGH with a dissociation constant (Kd) of 2.9 +/- 0.13 nM. Scatchard analysis indicated that mGHR1.6 cells had only a single class of mGHR and possessed approx 128,000 GH specific binding sites per cell. Affinity crosslinking studies showed that the recombinant mGHR possessed an apparent molecular mass of 105 kDa. In addition, mGHR1.6 cells responded to growth hormones (GHs) from several species. Two proteins, pp92 and pp95, were found to be tyrosyl phosphorylated following GH treatment. An hGH antagonist, hGH-G120R, inhibited GH-induced phosphorylation of both pp92 and pp95 in a dose-dependent manner. This cell line may be used as an in vitro model in the studies of GH signal transduction and in the screening of GH analogs for biological activity.

3T3 Cells↗

PubMed1994

Molecular cloning and characterization of the type VII isoform of mammalian adenylyl cyclase expressed widely in mouse tissues and in S49 mouse lymphoma cells.

We have isolated a 5199-nucleotide cDNA from a mouse library containing an open reading frame encoding the 1099-amino acid type VII adenylyl cyclase protein. The type VII protein is most closely related in primary structure to an unpublished human adenylyl cyclase clone (GenBank accession no. D25538) and type II adenylyl cyclase. Northern blot analysis demonstrates that the type VII mRNA is most abundant in mouse heart, spleen, and lung. cAMP content rises rapidly in HEK 293 cells overexpressing type VII adenylyl cyclase following treatment with phorbol ester, peaking by 4 min, while cells expressing the type II adenylyl cyclase reach peak accumulation only after 20 min. Increases in intracellular calcium through treatment of type VII-293 cells with either ATP or A23187 alone failed to increase intracellular cAMP content. Phorbol ester treatment acted synergistically with beta-adrenergic stimulation to increase cAMP content in type VII-transformed cells. Pretreatment of type VII-transformed cells with pertussis toxin fails to prevent phorbol ester potentiation of isoproterenol stimulation. Thus the ability of phorbol ester to increase basal and isoproterenol-stimulated type VII activity appears to be a direct effect on this adenylyl cyclase isoform and not the result of modification of the inhibitory G protein, Gi.

Adenylyl Cyclases↗

PubMed1994

LPS induces selective translocation of protein kinase C-beta in LPS-responsive mouse macrophages, but not in LPS-nonresponsive mouse macrophages.

Translocation of protein kinase C (PKC) after PMA or LPS stimulation has been studied in thioglycolate (TGC)-elicited murine peritoneal macrophages. Among the PKC subtypes we examined (alpha, beta, gamma, delta, and epsilon) by indirect immunostaining and immunoblot analysis, conventional PKC-beta, as well as novel PKC-delta and PKC-epsilon were found to exist in TGC-elicited C3H/HeN mouse macrophages. Translocation of PKC-beta to the Triton-stable cytoskeleton could be seen in macrophages after stimulation by both PMA and LPS. On the other hand, novel PKCs redistributed only after PMA stimulation. Macrophages obtained from LPS-nonresponsive C3H/HeJ mice also exhibited PKC-beta, and the m.w., cellular distribution, and cellular content of this enzyme could not be distinguished from those of C3H/HeN macrophages. These macrophages exhibited PKC-delta and PKC-epsilon, as did the C3H/HeN macrophages. In these macrophages, however, LPS did not induce any remarkable change in the intracellular distribution of PKC-delta and PKC-epsilon or PKC-beta, whereas PMA was able to induce the translocation of PKC-beta to the cytoskeleton. These results suggest that LPS stimulation induces selective redistribution of PKC-beta in LPS-responsive macrophages, whereas a defect related to LPS unresponsiveness exists in C3H/HeJ mouse macrophages before the PKC activation. Translocation of PKC-beta can be understood to be an important event in LPS signaling in macrophages.

Animals↗

PubMed1976

The comparative effectiveness of rabbit anti-mouse thymocyte sera in potentiating the survival of mouse skin or tumour allografts made across the H-2 barrier.

A group of fifteen rabbits were immunized five times, at weekly intervals, by intravenous injection of mouse thymocytes. After an interval of 3 months the rabbits were then re-immunized three times at intervals of 7 days. The rabbits were bled prior to the commencement of immunization to obtain normal rabbit serum (NRS), and 7 days after the first, third, fifth, sixth and eigth immunizations. Thus pulse (P), P1, P3, P5, P6 and P8 rabbit anti-mouse thymocyte serum (RAMTS) was obtained. Further pairs of rabbits were immunized three times, at intervals of 7 days, by injection of thymocytes pre-incubated with NRS, or P3, P6 or P8 RAMTS. Thus RAMT(NRS)S, RAMT(P3)S, RAMT(P6)S and RAMT(P8)S were obtained. The immunosuppressive potency of the antisera were compared by their ability to promote the survival of A-strain skin grafts made to CBA mice and A-strain mammary carcinoma transplants in CBA mice. Administration of P3, P5, P6, P8, RAMT(P3)S and RAMT(P6)S led to progressive tumour growth, but only P3 and P5 prolonged skin graft survival. Pre-incubation of tumour cells in the several RAMTS samples did not enhance their growth in sub-lethally irradiated (350 rad) CBA hosts. It is thus suggested that the preferential survival of tumour allografts was due to their ability to outgrow a degree of host response able to destroy a skin graft.

Animals↗

PubMed1994

Allelic losses and metastatic ability of mouse tumor cell clones derived from a heterozygous mouse.

Some chromosomal or subchromosomal deletions observed in a variety of cancer cells may be related with metastatic properties of the tumor cells. Thus, relationship between allelic losses and metastatic ability is here investigated of ten in vitro clones obtained from 505 cells that are derived from a fibrosarcoma induced in a F1 mouse between C3H and C57BL strains. Allelic loss was examined using 61 microsatellite markers spanning all autosomes and deletions of various loci were observed in all of the clones. One clone showed a metastatic ability higher than the parental 505 cells and the other clones. This particular clone specifically lost a chromosome 16 derived from C57BL, suggesting an association of this chromosome deletion with the metastatic ability. Consistently, examination of metastatic nodules derived from 505 cells and one in vitro clone showed that the cells with deletion of the C57BL chromosome increased in number during metastasis. These results suggest that mouse chromosome 16 may harbor a gene(s) involved in metastasis.

Alleles↗