Mouse hybrids

Mouse (Hybrid) Gd 1-18 1 x/d (F) 0.18 9 (significantly reduced early weight gain by pups, increased mortality at ppd 28) Barnett et al. 1980... 

In cases where the cell line is a heterohybrid, that is, a human/mouse hybrid, it may be possible to grow the cell line as a tumor in sublethally irradiated mice and produce ascitic fluid... 

Some cells, such as hybridomas, stem, and hematopoietic cells may require a class of proteins known as interleukins, especially IL-6. This compound can substitute for feeder cells (such as those of the peritoneal exudates or spleen, fibroblasts or timocytes) in the post-fusion stage of hybridoma cultures. IL-6 is secreted by monocytes, T lymphocytes, and endothelial cells and is effective in the stimulation of hybridomas of different species, including lineages that are difficult to cultivate, such as human-mouse and rat-mouse hybrids. IL-6 also presents a synergistic effect with other interleukins to increase antibody production. 

Finally, the Tm of a DNA depends on how well its bases match up. A synthetic DNA double strand made with some mismatched base-pairs has a lower Tm compared to a completely double-stranded DNA. This last property is important in using DNA from one species to detect similar DNA sequences of another species. For example, the DNA coding for an enzyme from human cells can form double helices with mouse DNA sequences coding for the same enzyme however, the mouse-mouse and human-human double strands will both melt at a higher temperature than will the human-mouse hybrid DNA double helices. 

Using mouse-mouse hybrids and Robertsonian translocation markers, Hengart-ner et al. [86] confirmed that the expression of k light chains requires a locus on chromosome 6, whereas the expression of heavy chains required chromosome 12. The formal demonstration that the structural k and Igh loci reside on chromosomes 6 and 12, respectively, was obtained by the analysis of mouse-hamster hybrids using Southern blot hybridization [87,88], A similar approach was used by D Eustachio et al. [89] to assign the A locus to mouse chromosome 16. 

Robertson J, Raju M. 1980. Sudden reversion to normal radiosensitivity to the effects of x-irradiation and plutonium-238 alpha particles by a radioresistant rat-mouse hybrid cell line. Radiat Res 83 197-204. 

The investigations were carried out in vivo with male mouse hybrids of the line C57B1/6DVA/21, which were inoculated intraperitoneally with Ehrlich ascite carcinoma at 6-10 cells per animal. It was shown that the use of Fe304/Na ol./ PEG/CP nanocomposites as the magnetic fluid components increases essentially (by 40%) the therapeutic effect of cytostatic preparation. 

It is possible to establish heterogeneous populations of mitochondria experimentally in the same cell. In human-mouse somatic cell hybrids, the mitochondria from the two parental types can be distinguished by differences in bouyant density of their DNA s (Attardi and Attardi, 1972) or differences in their nucleotide sequences (Coon et al., 1973). In human-mouse hybrid cells, Attardi and Attardi (1972) have failed to find persistence of human mitochondria, but Coon et al. (1973) reported... 

It is well documented that in human x mouse hybrid cells that there is a preferential loss of human chromosomes (27). We, therefore, examined the isozyme pattern and chromosome complement... 

Hybrids between human and mouse cell have also been used in mapping the polio receptor site (52). Hamster-mouse hybrids, and human-mouse hybrids are susceptible to polyoma virus (53) as long as the parental mouse chromosomes (permissive cell line) were... 

The poly(ADP-ribose) polymerase gene (column 2) was detected as 2.3,7.0, 8.0, and 25 kb hybridizing bands (27 positive hybrids) in EcoKl digests of human-rodent somatic cell hybrid DNAs or as a 5.3 kb sequence (column 3) or 6.8 kb band (column 4). Detection of each sequence, or group of sequences, is correlated with the presence or absence of each human chromosome in the somatic cell hybrids. Discordancy indicates the presence of hybridizing sequences in the absence of the chromosome or absence of the hybridizing bands despite the presence of the chromosome the sum of these numbers divided by total hybrids examined (XI00) represents percent discordancy. The human-hamster hybrids consisted of 26 primary clones and 15 subclones and the human-mouse hybrids contained 13 primary hybrids and 42 subclones. The 5.3 kb and 6.8 kb human poly(ADP-ribose) polymerase sequences were detected in 35 and 54 hybrid cell DNAs, respectively. 

H36.12J clonally derived, C57BL/6N-mouse hybrid precursor macrophages were found useful to evaluate the mechanisms by which Be stimulates macrophage cytokine production, and by which T cell derived IFN-y amplifies TNF-a production in granulomatous disease (Sawyer et d. 2000). The response was maximal at 100 jiM BeS04 and did not occur when 12j cells were stimulated with either aluminium sulphate of cobalt sulphate. Beryllium stimulated the production of 725125 pg/ml TNF-a protein by 12j cells as measured by ELISA of culture supernatants after 24 h. As measured by RT-PCR, Be-stimulated 12j cell TNF-a protein production was accompanied by an increased intracellular TNF-a mRNA at 3 and 24 h. The addition of 10 U or 1(X) U of recombinant-Mu-IFN-y to Be-stimulated 12j cells further increased TNF-a production 1.5-4... 

A number of protocols have been described for the generation of mouse hybrid-omas and workers have their own particular protocol. We have used a standard procedure for the fusion of mouse and rat myelomas with considerable success over the last twenty years and this is described in Protocol 7. Basically, 10 lymphocytes are mixed with 2 x 10 mouse myeloma cells or 5 X 10 Y3 cells in a round-bottomed tube and pelleted by centrifugation. Then the ceUs are fused by the addition of 1 ml of 50% PEG 1500 and plated into HAT selection medium to allow the growth of the hybridomas generated. 

Before doing so, we wish to call attention to the fact that the karyotypic and phenotypic characteristics of the interspecific somatic hybrids will be presented in the order in which they were observed accordingly, we will give consideration first to rat X mouse and hamster X mouse hybrids. The implications of the properties of these hybrids will be discussed, and an attempt will be made to evaluate their significance in contributing to a general speculative picture of the coordination of replication processes in mammalian cells. We shall see later (Section IV, E) that, in the light of recent observations on some other interspecific hybrids, some of our conclusions may have to be amended. 

III. PROPERTIES OF RAT X MOUSE AND HAMSTER X MOUSE HYBRIDS A. Viability... 

While this scheme seems to account for the transitory asynchrony of the hamster-species hybrids, its application to the particular case of the hybrids of the 3460 X 2472 series encounters serious diflBculties, as follows (a) In these hybrids the lagging chromosomes are always those of the hamster parent, (b) Fifty percent of the hybrid metaphases appear synchronous, yet clones of viable hybrids are not obtained. Therefore one must assume either that synchrony of some of the first mitoses is purely fortuitous (and due to fusion of cells in the same late phase of preparation for mitosis) and is not maintained in the succeeding divisions or that the inviability of these hybrids is due to causes unrelated to the observed mitotic asynchrony. The possible nature of these causes will be discussed below. Before we do so, we would like to point out that the application of the above hypothesis to the human X mouse hybrids encounters similar difiSculties. Since, on this hypothesis, a certain fraction of hybrids must result from the fusion of cells in the same phase of the life cycle, one should find a fraction of hybrids containing the full complements of mouse and human chromosomes. In fact, however, such a condition of these hybrids appears to be ephemeral. 

While our speculations have been prompted by observations of interspecific somatic hybrids, they apply also to, and could have been based on, earlier observations (some of which will be quoted) of the numerous intraspecific (mouse X mouse) hybrids produced in our laboratories. However, the foreignness of the two genomes of interspecific hybrids presents the problems of coordination of their activities in a particularly acute form and simultaneously offers possibilities for experimental tests of the various hypothetical solutions. 

II. Lactate dehydrogenase and )8-glucuronidase. Genetics 54, 1111-1122. Weiss, M. C., and Green, H. (1967). Human-mouse hybrid cell lines containing partial complements of human chromosomes and functioning human genes. Proc. Natl. Acad. Set. U.S. 58, 1104-1111. 

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