| First Author | West JD | Year | 1994 |
| Journal | Mouse Genome | Volume | 92 |
| Issue | 4 | Pages | 666-668 |
| Mgi Jnum | J:90004 | Mgi Id | MGI:3042236 |
| Citation | West JD, et al. (1994) Transgenic Nomenclature (Correction Mouse Genome 1995;93(1):145). Mouse Genome 92(4):666-668 |
| abstractText | Full text of Mouse Genome contribution: Changes in Holdings: Transgenic Strain: TgR(ROSA26)26Sor. Homozygous transgenic TgR(ROSA26)26Sor mice were kindly provided to us by Dr Nick Allen (AFRC Institute, Babraham) in November 1993. This transgenic strain was produced by Friedrich and Soriano (Genes & Development, 5 1513-1523, 1991). We have made the original stock homozygous for Gpi-lsb and are also backcrossing it to BALB/c/Eumm. (John D. West) Two New Partially Congenic Transgenic Strains. The transgenic strain of mice commonly known as "strain 83" or "Beta83" was produced by Lo (J. Cell Sci, 81 143-162, 1986) by pronuclear injection of the cloned Beta-major globin gene, Hbbb1 (Tilghman et al, Proc. Natl. Acad Sci USA, 74, 4406-4410, 1977) and was imported into the U.K. by Whittingham (Mouse Genome 86, 243, 1990). The original strain was generated on a C57BL/6J x SJL/J genetic background and the mice imported by Whittingham were on a B63H x CD1 background. The transgene consists of approximately 1000 tandem repeats of plasmid pMBeta-Delta2 (comprising plasmid pBR322 and a 7kb insert of Hbbb1 DNA) located near the telomere of chromosome 3 (Lo, Diaz & Kirby, Mouse Genome 90, 684-6, 1992; Everett, Keighren & West, below). Using the nomenclature specified in Mouse Genome 92(2), xxi, 1994 and with the approval of Dr Lo, we are using the provisional standardised name TgN(Hbb-bl)83Lo. The laboratory registration code "Lo" (for Dr. C. Lo) is unofficial and the gene symbol Hbb-bl has been used in preference to the plasmid symbol pMBeta-Delta2. We obtained this strain from Dr Roger Gosden (Dept of Physiology, University of Edinburgh) in 1989 and have made several new stocks including two partially congenic strains, which we provisionally designate C57BL/Ws-TgN(Hbb-bl)83Lo/Ws (abbreviated stock name "GLB") and LT/SvKau-TgN(Hbb-bl)83Lo/Ws (abbreviated stock name "TRIP") respectively. These strains were produced by backcrossing hemizygous animals to C57BL/Ws or LT/SvKau for 8 generations and intercrossing until homozygous for the transgene (2 signals per nucleus after in situ hybridization to leukocytes). Status in February 1994: "GLB", N8F6; "TRIP", N8F3 (poor breeding performance). We also currently maintain three homozygous transgenic outbred stocks that are homozygous for different alleles at the albino and Gpi-1s loci and are better breeders. Abbreviated stock name: "TGA"; Genotype: C/C Gpi-1sa/Gpi-1sa. Abbreviated stock name: "TGB"; Genotype: C/C Gpi-1sb/Gpi-lsb. Abbreviated stock name: "CMA"; Genotype: c/c Gpi-lsa/Gpi-1sa. (Margaret Keighren & John D. West) Restricted distribution of tetraploid cells in postimplantation tetraploid <---> diploid chimaeras. Tetraploid mouse embryos were produced by electrofusion at the 2-cell stage, cultured overnight and aggregated with normal diploid embryos to produce tetraploid<--->diploid (4n<--->2n) chimaeric conceptuses. At 7 1/2 days the 4 n <---> 2n chimaeras were usually smaller and developmentally retarded compared to control diploid<--->diploid chimaeras. At 12 1/2 days the 4 n <---> 2n chimaeras had heavier placentas but there was no significant difference in fetal size. Tetraploid cells showed a restricted tissue distribution at both developmental stages studied: 4n cells were commonly present in both the primitive endoderm and trophectoderm lineages but they rarely contributed to the primitive ectoderm lineage. The overall similarity in the distribution of tetraploid cells at 7 1/2 and 12 1/2 days implies that whatever causes the restricted tissue distribution operates largely before 7 l/2 days. There was no evidence for excessive embryonic losses of 4 n <---> 2n chimaeras. So, if the restricted distribution of 4n cells was a result of cell selection, the mechanism is more likely to involve loss of 4n cells from the primitive ectoderm early in development rather than selective death of conceptuses with tetraploid cells in this lineage. Alternatively, 4n cells may be preferentially allocated to the trophectoderm and primitive endoderm rather than the primitive ectoderm layer at the blastocyst stage. (Roberta M James, Anke HEM Klerkx, Margaret Keighren, Jean H Flockhart & John D West) Non-random distribution of tetraploid cells in tetraploid<--->diploid chimaeric blastocysts. The distribution pattern of tetraploid cells in 7 1/2 and 12 1/2 day tetraploid<--->diploid (4n<--->2n) aggregation chimaeras has revealed the limited developmental potential of these cells, as discussed above (James, Klerkx, Keighren, Flockhart & West). Several explanations have been offered to account for this pattern of distribution. It is possible that selective pressures act which cause the 4n cells of the primitive ectoderm to die prior to 7.5 days. Alternatively 4n cells may be preferentially allocated to the trophectoderm and primitive endoderm lineages at the blastocyst stage. In an attempt to clarify the situation, 4n<---> 2n mouse chimaeras were produced and the distribution of 4n cells was assessed at the early blastocyst stage (90hr P.c.). 4n cells were hemizygous for the reiterated Beta-globin transgene TgN(Hbb-bl)83Lo (abbreviated to Tg). The transgenic 4n cells (Tg/Tg/-/-) were distinguished from non-transgenic (-/-) diploid cells by DNA-DNA in situ hybridisation. Serial sections of 4n<--->2n and 2n<---> 2n blastocysts were scored. Analysis of the distribution of 4n cells in the 4n<--->2n chimaeric blastocysts revealed an over-representation of cells carrying the transgene in the trophectoderm (P<0.01) rather than the inner cell mass. Further analysis revealed this difference to be due to significantly greater numbers of tetraploid cells in the mural trophectoderm (P<0.001) than in the other areas of the blastocyst. Such a pattern was not evident in the 2n<--->2n (Tg/-<--->-/-) controls. It would appear, therefore, that 4n cells are preferentially allocated to the mural trophectoderm by this early stage (90hr p.c.) of development. Further work is in progress to determine the cause of this non-random distribution in the blastocyst and how this affects the contribution of 4n cells to various tissues later in development. (Clare A. Everett & John D. West) New Transgenic Robertsonian Strain. The transgenic strain of mice, originally known as "strain 83" or "Beta83" was produced by Dr. C. Lo (Lo, J. Cell Sci, 81 143-162, 1986) and contains approximately 1000 tandem repeats of the Beta-major globin gene, Hbbbl. We have suggested the provisional standardised name TgN(Hbb-bl)83Lo (see Keighren and West, above). In situ hybridization to metaphase spreads showed that the transgene (hereafter abbreviated to Tg) was located near the telomere of chromosome 3 (Lo, Diaz & Kirby, Mouse Genome 90, 684-6, 1992). We have now transferred Tg to the 1.3 Robertsonian chromosome of mice homozygous for the "tobacco mouse" metacentric Rb(1.3)Bnrl (obtained from the MRC Radiobiology Unit via Prof. M.H. Kaufman, Anatomy Dept., University of Edinburgh). Rb(1.3)lBnr homozygotes were mated to homozygous Tg/Tg transgenic animals and the hemizygous offspring were backcrossed to Rb(1.3)lBnr. Backcrossing was continued for 6 generations and Tg/- hemizygotes were identified by in situ hybridization to leukocytes. A recombinant, Tg/- hemizygous N6 generation male was identified after C-banding and in situ hybridization of metaphase spreads from air-dried bone marrow preparations. This male had two Robertsonian chromosomes one of which carried the transgene near the distal end of one arm, consistent with the reported location on chromosome 3. Offspring of the recombinant male are being intercrossed to produce a homozygous transgenic, Robertsonian strain which we provisionally designate Rb(1.3) lBnr-TgN(Hbb-bl)83Lo/Ws (abbreviated stock name "RBT"). (Clare A. Everett, Margaret Keighren & John D. West) Research News: A maternal genetic effect on the composition of aggregation chimaeras. Four series of 12 1/2 day mouse chimaeric conceptuses were produced by aggregating (C57BL x CBA)F2 strain preimplantation embryos with embryos that differed at the Gpi-1s locus that encodes glucose phosphate isomerase, GPI-1. The composition of individual tissues was evaluated by quantitative electrophoresis to estimate the % GPI-1A in the chimaeric tissue containing GPI-1A and GPI-1B. The results for the chimaeric fetuses are shown below and were typical of the other tissues studied (amnion, yolk sac mesoderm, yolk sac endoderm, parietal endoderm, trophoblast overlying Reichert's membrane and placenta). Strains of embryos aggregated: Embryo "A": Female: (BC x BALB/c)F1 x Male: (BC x BALB/c)F1; <--->: Embryo "B": BF1 x BF1; Mean %GPI-1A in Fetus +/-SE (N): 49.5 +/- 3.7 (33). Strains of embryos aggregated: Embryo "A": Female: (BC x BALB/c)F1 x Male: BALB/c; <--->: Embryo "B": BF1 x BF1; Mean %GPI-1A in Fetus +/-SE (N): 47.4 +/- 5.9 (32). Strains of embryos aggregated: Embryo "A": Female: BALB/c x Male: (BC x BALB/c)F1; <--->: Embryo "B": BF1 x BF1; Mean %GPI-1A in Fetus +/-SE (N): 33.6 +/- 4.9 (29). Strains of embryos aggregated: Embryo "A": Female: BALB/c x Male: BALB/c; <--->: Embryo "B": BF1 x BF1; Mean %GPI-1A in Fetus +/-SE (N): 15.1 +/- 3.9 (38). BC is the partially congenic strain C57BL/Ola.AKR-Gpi-lsa, c/Ws BALB/c is BALB/c/Eumm BF1 is (C57BL/Ola x CBA/Ca)F1 The results imply that embryos from BALB/c mothers contributed less to the tissues of chimaeric conceptuses than embryos from (BC x BALB/c)Fl mothers. We, therefore, conclude that a maternal genetic effect is responsible for some of the differences in composition among the four groups of chimaeras. This maternal effect must act before the 8-cell stage but it is not yet known whether it is mediated via cytoplasmic inheritance, genomic imprinting or by the reproductive tract. (John D. West & Jean H. Flockhart) CORRECTION: Mouse Genome 1995; 93(1):145. Changes in Holdings: Corrections to Transgenic Nomenclature In Mouse Genome 92(4), 666-668 (1994) we gave details of several new transgenic stocks that were derived from Dr. Cecelia Lo's transgenic strain of mice commonly known as "strain 83" or "Beta83" (Lo, J. Cell Sci. 81, 143-162, 1986). With the approval of Dr Lo, we used the provisional standardised name TgN(Hbb-bl)83Lo but the laboratory registration code "Lo" (for Dr. C. Lo) was provisional. The laboratory registration code "Clo" has now been assigned, so the standardised name for this transgene should be TgN(Hbb-bl)83Clo. The new stocks that we reported should now be designated as follows: Two New Partially Congenic Transgenic Strains: C57BL/Ws-TgN(Hbb-bl)83Clo/Ws (abbreviated stock name "GLB") LT/SvKau-TgN(Hbb-bl)83Clo/Ws (abbreviated stock name "TRIP") New Transgenic Robertsonian Strain: Rb(1.3)lBnr-TgN(Hbb-b1)83Clo/Ws (abbreviated stock name "RBT"). (John D. West, Clare A. Everett & Margaret Keighren) |
