Cloning of the cDNA encoding mouse PP5/TFPI-2 and mapping of the gene to chromosome 6

Placental protein 5 (PP5)/tissue factor pathway inhibitor-2 (TFPI-2) is a new homologue of TFPI, which contains three tandemly repeated Kunitz-type proteinase inhibitory (KPI) domains and potently inhibits the extrinsic blood coagulation cascade. In this study, mouse PP5/TFPI-2 cDNA was cloned using a human PP5/TFPI2 cDNA fragment as a probe. The characteristic three KPI domains with short spacer sequences and a basic amino acid stretch in the carboxyl-terminal region present in human PP5/TFPI-2 were well conserved in mouse PP5/TFPI-2. In general, the P1 reactive site residues of active KPI domains are basic amino acids. However, the putative P1 residues of the first, second, and third KPI domains were glutamine, aspartic acid, and serine, respectively. Mouse PP5/TFPI-2 mRNA was highly expressed in developing placenta as in humans. Adult liver and kidney also contained a significant amount of its transcripts. The mouse PP5/TFPI-2 gene was found to be located in the R-positive A2 band by the direct R-banding FISH and identified at 2.7 cM proximal to D6Mit 1 by interspecific backcross analysis.

Expression of the recombinase-activating gene (RAG-1) in murine early embryogenesis

The recombinase activation genes, RAG-1 and RAG-2, are expressed together in immature T or B lymphocytes and possess activity to induce V(D)J rearrangement in T cell receptor (TCR) and Ig genes. In vertebrates, only Ig and TCR molecules are reported to have recombination in their development using multiple V, D, J component gene segments. Thus, expression of RAG genes are localized only in lymphoid organs and sites of extrathymic T cell differentiation. In this study, we have used RAG-1 and RAG-2 genes as markers of possible genetic recombination in developing murine preimplantation embryos, using the highly sensitive reverse transcriptase polymerase chain reaction (RT-PCR) technique and in situ hybridization. From 40 preimplantation embryos of various developmental stages we extracted RNA, reverse-transcribed it into cDNA and used it in RT-PCR studies. A PCR of 35 cycles disclosed expression of RAG-1 but not RAG-2 in morulae and blastocysts. Southern blot hybridization using a specific synthetic oligonucleotide probe for RAG-1 and RT-PCR with another primer pair identified RAG-1 expression in developing embryos. In situ hybridization using a cooled CCD camera also revealed localization of RAG-1 mRNA in blastocysts. We propose possible genetic recombination during late preimplantation murine embryogenesis which may contribute to the loss of totipotency and differentiation of inner cell mass and trophoectoderm.

Morphological studies on the kidney of the spontaneous nephrotic (ICGN) mice in the late stage

Spontaneous nephrotic (ICGN) mice develop proteinuria, hypoproteinemia and hypercholesterolemia. These symptoms steadily progress to chronic renal failure. Details of the changes of the kidney, in the late stage (more than 5 months old) were investigated by both light and electron microscopy. The kidney exhibited a slightly whitish, granular surface and the cortex became thinner and contained fibrous lesions, in which clusters of unaffected and occluded renal tubules were randomly scattered. In the juxtamedullary and outer medullary zone, there were highly dilated renal tubules, which sometimes contained urinary casts. The glomerulus exhibited basement membrane thickening in the capillary loops and the capillary lumen was narrowed in size and sometimes occluded. No detachment of the podocyte from the basement membrane was observed and the podocyte foot-processes were extensively fused, causing their characteristic slits to be lost. The thickened basement membranes were found both in the glomerulus and around the occluded renal tubules, while the basement membrane in the dilated renal tubule appeared normal. Therefore, the basement membranes of the glomerulus and renal tubules appear to react differently in the pathogenesis of the condition. In conclusion, ICGN mice are a good model for not only the nephrotic syndrome but also for chronic renal failure.

Mouse and human chromosomal assignments of mortalin, a novel member of the murine hsp70 family of proteins

Mortalin has been shown to exhibit differential distributions in cells with mortal and immortal phenotypes. In the present study, we report mot-2 cDNA cloning from RS-4 cells--an immortal clone from CD1-ICR mouse embryonic fibroblasts--and the chromosomal assignments of mortalin related genes to mouse chromosomes 18 and X by fluorescence in situ hybridization. Similar analysis assigned the gene to chromosome 5q31.1 in human.

Increased incidence of unpartnered single chromatids in metaphase II oocytes in 39,X(XO) mice

Since rare cases of sex chromosome anomalies such as XXX and XXY were observed in the offspring of our XO breeder mice, we performed a cytogenetic analysis of metaphase II oocytes of XO mice to determine whether any changes in chromosomal configurations occur. We found a significantly increased incidence of unpartnered single chromatids in metaphase II oocytes of XO mice. Such single chromatids may contribute to embryonic aneuploidy. In addition, the tendency of the X-chromosome to segregate non-randomly to the oocyte rather than to the polar body was confirmed.

Chromosomal mapping of mouse 5S rRNA genes by direct R-banding fluorescence in situ hybridization

The mouse 5S rRNA gene was mapped by direct R-banding fluorescence in situ hybridization (FISH) with biotinylated probes. Two genomic fragments amplified by PCR from total genomic DNA of BALB/c mice and Mus spretus, a 0.16-kb fragment that included the 121-bp 5S rRNA gene and a 1.6-kb fragment that included the whole spacer region, were used for chromosomal mapping of the 5S rRNA gene. Both fragments hybridized to a single locus on a pair of autosomal chromosomes of BALB/c mice. The major cluster of mouse 5S rRNA genes was assigned to the most terminal R-negative to R-positive bands of the E region of mouse Chromosome 8, which is homologous to the linkage of the 5S rRNA gene on the long arm of human chromosome 1. The location of the 5S rRNA gene was mapped in five laboratory strains, in wild mice of six Mus musculus subspecies (domesticus, brevirostris, musculus, bactrianus, castaneus, and molossinus) derived from 10 separate localities, and in four different Mus species (spretus, hortulanus, spicilegus, and caroli), using FISH. The 5S rRNA cluster mapped to the same position on the chromosomes of all mouse species and subspecies studied. These results suggest that the location of the mouse 5S rRNA gene on the distal telomeric region of Chromosome 8 is evolutionarily conserved. In comparison, the chromosomal assignments of centromeric 18S-28S rRNA genes are highly variable among the different M. musculus subspecies and Mus species.

Spontaneous immortalization of mouse fibroblasts involves structural changes in senescence inducing protein, mortalin

Mortalin, a novel member of mouse heat shock protein 70 (hsp70) family, is seen to distinguish the cellular mortal and immortal phenotypes by virtue of its cytosolic and perinuclear distribution, respectively. We report here that the cytosolic and perinuclear forms of mortalin from CD1-ICR mouse embryonic fibroblasts and NIH 3T3 cells, respectively, differ by two amino acids, can be distinguished on two-dimensional SDS-polyacrylamide gel. The perinuclear mortalins from RS-4 and Balb/c 3T3 cells harbor the same two amino acids as that of NIH 3T3 cells. However, these when analyzed with C-MEF mortalin did not exhibit the mobility shift equivalent to C-MEF and NIH 3T3 mortalins. The data indicate that the perinuclear mortalin from different immortal fibroblasts are not identical and implicate the possibility of additional structural changes in mortalin during immortalization. Such differences may also contribute to the differential in vitro growth characteristics of these immortal cells.

Murine Cdx-4 bears striking similarities to the Drosophila caudal gene in its homeodomain sequence and early expression pattern

A third member of the murine caudal-like gene family, Cdx-4, has been isolated. In situ hybridization and immunohistochemistry have been used to study the localization of mRNA and protein during murine embryogenesis. Cdx-4 is expressed transiently from 7.0 d.p.c. (days post coitum) until 10 d.p.c., starting at the beginning of gastrulation (7.0-7.5 d.p.c.) in the allantois and posterior tip of the primitive streak. At the mid-streak stage, Cdx-4 expression moves rostrally, and protein and mRNA are detected in all cells over the posterior half of the primitive streak. As development proceeds, Cdx-4 gene products continue to be restricted to the posterior of the embryo, including the remnants of the primitive streak. Cdx-4 is expressed in neurectoderm, presomitic and lateral plate mesoderm, and hindgut endoderm, but the anterior boundary in the paraxial mesoderm is staggered with respect to the other germ layers. At all stages analyzed, Cdx-4 exhibits a graded expression pattern with a posterior maximum, a distribution highly reminiscent of the Drosophila caudal gene. These data add to the recently described distributions of other vertebrate caudal-like genes, and further support the idea that members of this homeobox gene subfamily have regulatory roles in the specification of anteroposterior axial polarity in early embryos.

Cloning and functional expression of a cDNA encoding the mouse beta 2 subunit of the kainate-selective glutamate receptor channel

The primary structure of the mouse glutamate receptor beta 2 subunit has been deduced by cloning and sequencing cDNA. The beta 2 subunit has structural characteristics common to the subunits of glutamate-gated ion channels. Expression of the cloned cDNA in Xenopus oocytes yields functional glutamate receptor channels selective for kainate.

Susceptibility of newly established mouse strain MPS to Mycoplasma pneumoniae infection

A newly established mouse strain, MPS, which is more sensitive to Mycoplasma pulmonis than ICR, ddY and other mouse strains was examined for its susceptibility to Mycoplasma pneumoniae. In experimental infections with M. pneumoniae, it was observed that M. pneumoniae attached to tracheas of MPS mice, and M. pneumoniae cells were isolated from tracheas and lungs of MPS mice even after four weeks of infection, while no mycoplasmas were isolated from ICR and ddY mice after one week of infection. Specific antibodies against M. pneumoniae were also observed by the Western blotting in the sera of MPS mice infected with M. pneumoniae. Although any lung lesion could not be observed in this work, this newly established mouse strain MPS may be useful for experiments of M. pneumoniae infection, especially for the analysis of strain differences in susceptibility to M. pneumoniae infection.

Effect of heterosis on performance of mice across three environments

Performance of six genetic groups of mice was studied in three different environments in order to determine the effect of heterosis on consistency of performance in varied environments. Designed as a 3 x 6 factorial, data were analyzed using least squares analyses of variance. Genetic group effects, environmental effects, genetic group x environment interaction, and heterosis were examined for 42-d weight, age and weight at vaginal opening, age and weight at puberty, ovulation rate (determined by total corpora lutea), number of implantations, and number of fetuses at 10 d of gestation. Weight at vaginal opening, ovulation rate, implantation rate and total number of fetuses exhibited significant heterosis. Regression of these traits against an environmental index (mean performance of all genetic groups over environments) provided an estimate of stability of performance. In general, genetic groups exhibiting heterosis expressed more consistent performance across environments than pure lines did. We conclude that a stability model could be used to aid in identification of lines with consistent performance for production traits in variable environments.

Selection of mouse strains showing high and low incidences of alloxan-induced diabetes

To produce an experimental model of diabetes in animals, ICR mice were inbred until the 20th generation by two-way selection toward the high- and low-incidences of alloxan-induced diabetes. Changes in successive generations in the incidence of such diabetes, in blood glucose levels, growth patterns and reproductive performance were studied. The incidence of alloxan-induced diabetes was 41.1% in the basal population; in the high-incidence strain, it was 98.7% in F13, ranging between 90 and 99% in later generations; and in the low-incidence strain, it reached 0% in F7, remaining near that level in later generations. The heritability of the incidence of alloxan-induced diabetes determined at the beginning of selection was 50-60%. The blood glucose level was 251 +/- 19 mg/dl in the basal population; in the high-incidence strain, it was 423 +/- 11 mg/dl in F13, ranging thereafter between 340 and 455 mg/dl; and in the low-incidence strain, it was 128 +/- 4 mg/dl in F7, then varying from 120 to 140 mg/dl in following generations. The heritability of the blood glucose level determined at the beginning of selection was 40-60%. No marked decrease in growth or reproductive performance accompanied successive selections. Successive generations of the high-incidence mice, however, tended to become heavier than the low-incidence animals. The high- and low-incidence strains, established in the 20th generation, were named the ALS (alloxan-induced diabetes-susceptible) and ALR (alloxan-induced diabetes-resistant) strains, respectively.

Genetic control of survival of frozen mouse embryos

Lines of mice selected for increased litter size (L+), increased body weight (W+), or randomly (K) were used to study genetic variation in embryo cryosurvival in response to standard cryopreservation protocols. A total of 60528-cell embryos from 400 females were used in two studies. In Study 1, embryos from L+, W+, and K were frozen by slow-cool and ultrarapid (direct-plunge) methods to evaluate effects of selection on cryosurvival and genotype X freezing method interaction. Post-thaw survival (PTS) was measured as percentage of recovered embryos developing in vitro to blastocyst per donor female. Nonfrozen control embryos developed similarly for each line. Within slow-cool freezing, lines differed (W+ greater than K, W+ = L+, L+ = K; p less than 0.05); no differences were observed within the ultrarapid freezing. However, line X method interaction effects on PTS were not significant. In Study 2, reciprocal crosses were made between L+ and K and between W+ and K. Hybrid and pure line embryos were frozen by slow-cooling. Control embryos developed similarly for all genotypes. Selection lines did not differ for overall PTS. However, hybrid embryos from L+ dams were superior to those from K dams (84 vs. 61%; p less than .001). No overall embryo heterosis was observed. Differences were not significant among embryo genotypes or treatments for cell number or in vivo survival. These results demonstrate significant correlated responses in embryo post-thaw cryosurvival due to selection, and implicate both maternal and embryonic genomes as controlling mouse embryo cryosurvival.

A single recessive non-MHC diabetogenic gene determines the development of insulitis in the presence of an MHC-linked diabetogenic gene in NOD mice

To study the genetic control of insulitis in non-obese diabetic (NOD) mice, we performed breeding studies in crosses of NOD with non-diabetic strains, ICR-L-line Ishibe (ILI), non-obese non-diabetic (NON) and C3H/He mice. The ILI mouse serologically shared the same MHC Class I and Class II as the NOD mouse. Insulitis was defined as islets invaded by lymphoid cells. Periductular, perivascular and peri-insular lymphoid cell infiltrations were often observed in NOD mice and appear to be the initial lesion leading to insulitis. Such lesions, however, were found in 1-year-old ICR, ILI, NON and Cataract Shionogi (CTS) mice of the NOD's sister strain. The lymphoid cells did not invade the islets in ICR, ILI, NON and CTS mice. The incidence of insulitis was 0% in F1 generations and 40% in female backcrosses (BC) [(ILI x NOD)F1 x NOD] at 9 weeks of age, 48 and 50% in BC[(NON x NOD)F1 x NOD] and BC[(C3H/He x NOD)F1 x NOD] at 1 year of age, respectively. Backcross animals were typed for the MHC to investigate correlation between the development of insulitis and MHC haplotypes. Among the backcross females with insulitis, approximately half the animals were heterozygous for MHC(non/nod) in BC[(NON x NOD)F1 x NOD] and MHC(k/nod) in BC[(C3H x NOD)F1 x NOD]. Among the backcross females with no insulitis, approximately half the animals were homozygous for MHC(nod/nod) in BC[(NON x NOD)F1 x NOD] and in BC[(C3H x NOD)F1 x NOD]. The results suggest that a single recessive non-MHC diabetogenic gene determines the development of insulitis regardless of NOD MHC homozygosity or heterozygosity.

Lethal burn-induced bacterial translocation: role of genetic resistance

Since genetic factors may influence outcome after trauma or during infection, the current experiments were performed to examine the resistance of three genetically different mouse strains to burn-induced bacterial translocation. Outbred ICR, inbred Balb/c, and inbred C57/B1 mice, with a normal or disrupted (monoassociated with Escherichia coli C25) GI tract microflora, were subjected to sham or actual 25% body burns. In Balb/c, but not ICR mice, replacing the normal intestinal microflora with E. coli C25 converted the thermal injury from a nonlethal (0% mortality) to a lethal (68% mortality) injury. The increased mortality of the burned Balb/c mice monoassociated with E. coli C25 was associated with a higher incidence (p less than 0.05) and magnitude (p less than 0.05) of E. coli C25 translocation from the GI tract. The C57/B1 mice were intermediate between the Balb/c and ICR strains, in that C57/B1 mice monoassociated with E. coli C25 had a higher mortality and greater E. coli C25 translocation than mice with a normal microflora after thermal injury. Thus the composition of the intestinal microflora as well as the genetic background of the host influence the susceptibility of the host to burn-induced bacterial translocation and survival.

Genetic analysis of the cause of exencephaly in the SELH/Bc mouse stock

A new mouse stock, SELH/Bc, having a high liability to exencephaly has been developed. About 17% of SELH fetuses are exencephalic. The genetic cause of this exencephaly was investigated in a cross to a normal related ICR/Bc strain and in subsequent classical genetic crosses (F2, first and second backcrosses). The data were compared with a number of genetic models, including that of a single recessive mutation with 17% penetrance. The data did not fit single-locus inheritance. The expectations from the multifactorial threshold model based on an underlying quantitative liability trait with additive inheritance were found to fit the data very well. The number of loci involved was estimated to be about two or three. About 70% of exencephalic SELH fetuses are female, and there is no overall deficiency of males. The relatively higher risk in females was constant across the genetic backgrounds in the experiment. In summary, the liability to exencephaly in SELH mice appears to be a multifactorial threshold trait, and it therefore resembles human neural tube defects in type of genetic etiology. SELH therefore may be a valuable animal model in the study of neural tube defects.

Rodent common fragile sites: are they conserved? Evidence from mouse and rat

Nineteen fragile sites induced by aphidicolin in lymphocyte cultures from the laboratory mouse are documented. These sites are compared with previously described fragile sites induced in mouse fibroblast systems, and then with those reported on chromosomes which have been evolutionarily conserved between the mouse and the laboratory rat. Of a total of 38 fragile sites thus far identified in mouse fibroblasts and lymphocytes, only 4 sites are common to the two cell types; 34 sites show no correspondence of loci. The reason for this discrepancy is unclear, but it is possible that these data may indicate some degree of tissue specificity of fragile site expression in the mouse. Eight autosomes in the mouse and rat retain straightforward and nearly complete banding homology. To test the hypothesis that fragile sites are conserved between the two species, we compared these eight autosomes with regard to number and distribution of fragile site loci. A total of 30 fragile sites is distributed over the conserved chromosomes. Only 4 (possibly 5) are common to both species; 18 are found in the rat but not the mouse, and 4 are found in the mouse but not the rat. Of the 4 shared sites, notable differences in frequency of expression exist. Our comparisons show that: (1) a small number of fragile sites is conserved; (2) a large number of fragile sites is not conserved, and (3) some sites which are conserved are quite different in the frequency at which they are expressed in the two species, indicating that the sites themselves may have undergone evolutionary change.(ABSTRACT TRUNCATED AT 250 WORDS)

A developmental-genetic analysis of aggressive behavior in mice (Mus musculus): III. Behavioral mediation by heightened reactivity or immobility?

This research was designed to investigate development and behavioral mediation in lines of ICR mice that have been selectively bred for aggressive behavior. General behavioral reactivity and behavioral immobility have been implicated as potential mediators by prior analyses of preattack interactions. To evaluate the separate roles of these dispositions, the emergence of attacks in genetically selected lines was tracked for 11 years by three levels of analysis: over successive generations, over development, and over dyadic interactions. Convergent outcomes were observed in all three levels with respect to two findings: (a) Robust line differences were obtained in attack behaviors, and (b) strong associations were found between line differences in attacks and line differences in behavioral immobility. Conversely, all three levels of analysis indicated a weak and inconsistent association between line differences in attacks and measures of social and nonsocial reactivity.

Strain differences in early mouse embryo development in vitro: role of the nucleus

Mouse embryos of many strains are blocked in development at the two-cell stage when placed in culture at the one-cell stage. If, however, they are placed in culture at the two-cell stage, they develop to blastocysts at a high rate. We investigated the transcriptional and translational systems in blocked embryos by assaying enzymatic activity of the protein product of an injected gene and found these systems to be functioning normally. The role of the nucleus was investigated by reciprocal nuclear transplants between blocked and nonblocked embryos. The results indicate that the source of the nucleus was of equal importance to that of the cytoplasm for the successful development of embryos cultured from the one-cell stage. When cultured from the two-cell stage, however, the nucleus was solely responsible for strain differences in culture rates.

Cloning and characterization of a cDNA coding for mouse placental alkaline phosphatase

Mouse alkaline phosphatase [ALP; orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] was partially purified from placenta. Data obtained by immunoblotting analysis suggested that the primary structure of this enzyme has a much greater homology to that of human and bovine liver ALPs than to the human placental isozyme. Therefore, a full-length cDNA encoding human liver-type ALP was used as a probe to isolate the mouse placental ALP cDNA. The cloned mouse cDNA is 2459 base pairs long and is composed of an open reading frame encoding a 524-amino acid polypeptide that contains a putative signal peptide of 17 amino acids. Homology at the amino acid level of the mouse placental ALP is 90% to the human liver isozyme but only 55% to the human placental counterpart. RNA blot hybridization results indicate that the mouse placental ALP is encoded by a gene identical to the gene expressed in mouse liver, kidney, and teratocarcinoma stem cells. This gene is therefore evolutionarily highly conserved in mouse and human.

Rejection of bone marrow allografts by mice with severe combined immune deficiency (SCID). Evidence that natural killer cells can mediate the specificity of marrow graft rejection

C.B-17 scid (H-2d) mice are homozygous for the gene that causes severe combined immune deficiency (SCID). These mice have no T or B cell function, yet display normal natural killer (NK) activity. Irradiated SCID mice were challenged with marrow grafts to determine if antibodies are necessary for marrow allograft rejection. SCID mice rejected H-2/Hh-1 allogeneic marrow grafts. Moreover, this rejection capability could be adoptively transferred using SCID marrow as a source of NK progenitors infused into irradiated B6 (H-2b) hosts. We conclude that NK cells can mediate marrow allograft reactivity in the absence of immunoglobulin. It follows that NK cells probably have specific receptors for Hh antigens.