Glucose Phosphate Isomerase Gene Research Articles

Tentative chromosomal assignment of the glucose phosphate isomerase gene in cattle, sheep and goat by in situ hybridization

Tentative chromosomal assignment of the glucose phosphate isomerase gene in cattle, sheep and goat by in situ hybridization

Tentative chromosomal assignment of the glucose phosphate isomerase gene in cattle, sheep and goat by in situ hybridization

Tentative chromosomal assignment of the glucose phosphate isomerase gene in cattle, sheep and goat by in situ hybridization

Death of mouse embryos that lack a functional gene for glucose phosphate isomerase

A null allele of the Gpi-1s structural gene, that encodes glucose phosphate isomerase (GPI-1; E.C. 5.3.1.9), arose in a mutation experiment and was designated Gpi-1sa-m1H. The viability of homozygotes has been investigated. No offspring homozygous for the null allele were produced by intercrossing two heterozygotes, so the homozygous condition was presumed to be embryonic lethal. Embryos were produced by crossing Gpi-1sa/null heterozygous females and Gpi-1sb/null heterozygous males. Homozygous null embryos were identified at different stages of development by electrophoresis and staining either for GPI-1 alone or GPI-1 plus phosphoglycerate kinase (PGK) activity. At 6 1/2 and 7 1/2 days post coitum homozygous null embryos were present at approximately the expected 25% frequency (37/165; 22.4% overall) although at 7 1/2 days the homozygous null embryos tended to be small. By 8 1/2 days most homozygous null embryos were developmentally retarded and had not developed significantly further than at 7 1/2 days; some were dead or dying. By 9 1/2 days the homozygous null conceptus was characterised by a small implantation site that contained trophoblast and often a small amount of extraembryonic membrane. Surviving trophoblast tissue was also detectable at 10 1/2 days. Previous studies have shown that oocyte-coded GPI-1 persists only until 5 1/2 or 6 1/2 days. Survival of homozygous null embryos to 7 1/2 or 8 1/2 days and survival of certain extraembryonic tissue to 10 1/2 days suggests that the homozygous null condition may not be cell-lethal although it is certainly embryo-lethal. Mutant cells that are deficient in glycolysis may use the pentose phosphate shunt to bypass the block in glycolysis created by the deficiency of glucose phosphate isomerase, and/or might be rescued by the transport, from the maternal blood, of energy sources other than glucose (such as glutamine). Either strategy may only permit slow cell growth that would not be adequate to support normal embryogenesis. Transport of maternal nutrients would be more efficient to the trophoblast and extraembryonic membranes and this may help to explain why these tissues survive for longer than the embryo itself. The morphological similarity between homozygous nulls and androgenetic conceptuses, where the trophoblast also survives better than the embryo, is discussed.

Porcine malignant hyperthermia carrier detection and chromosomal assignment using a linked probe.

In pigs, the gene for glucosephosphate isomerase (GPI) is linked to the halothane (HAL) gene which is responsible for malignant hyperthermia (MH). A single copy DNA probe, designated GPI8R, has been isolated from a pig genomic library using a porcine GPI cDNA probe. This probe detects, as was the case for the cDNA probe, a five allele polymorphism in SacI and PvuII digested pig DNA. Family studies show that this polymorphism is linked to the HAL locus and hence can be used in carrier detection. In situ hybridization with GPI8R assigned the GPI locus to bands p12-q22 of chromosome 6. We conclude that the HAL linkage group resides on chromosome 6.

Onset of paternal and maternal Gpi-1 expression in preimplantation mouse embryos

The initial activation of the glucose phosphate isomerase gene, Gpi-1, was studied in mouse embryos produced by transplanting pronuclei between two strains of mice differing in alleles for this enzyme. Protein isozymes encoded by the embryonic cell nuclei were first detected on Day 4 of embryogenesis, and the maternal and paternal genes are seen to be activated simultaneously. Comparison of isozymes produced by these nuclear-transfer embryos and by F 1 embryos from these two strains suggests the absence of oocyte mRNA for GPI-1 at the time when these genes are first activated. Thus, the GPI-1 present is derived from newly transcribed mRNA contributed by both maternal and paternal genes. The relative proportion of maternal cytoplasmic GPI-1 enzyme declines from Day 3 to Day 6, such that on Day 6, almost no oocyte GPI-1 is detected.

Genetic variation for prolidase (PEP-4) in the mouse maps near the gene for glucosephosphate isomerase (GPI-1) on chromosome 7.

An inherited electrophoretic variant of prolidase (EC 3.4.13.9), also called peptidase 4 (PEP-4), has been discovered among inbred strains of mice. Analysis of progeny from reciprocal backcrosses established that the electrophoretic forms are expressed codominantly and that Pep-4 is located between the genes for glucosephosphate isomerase (Gpi-1) and pink-eyed dilution (p) on chromosome 7. These data define a region of conserved gene linkage between mouse chromosome 7 and human chromosome 19, as originally indicated by somatic cell hybrid studies, and imply that human prolidase (PEPD) is located in the region of human chromosome 19 pter greater than q13.

Spontaneous expression of murine endogenous viruses in hamster X mouse hybrid cells

AbstractThe spontaneous expression patterns of murine leukemia virus (MuLV) from mouse spleen cultures and hamster × mouse spleen hybrid cells were compared. The hybrid cells preferentially segregated mouse while retaining a complete set of hamster chromosomes. Virus expression patterns showed considerable mouse strain differences in both parental and hybrid cells. None of 13 BALB/c spleen cultures expressed virus while 6 of 20 hybrid clones expressed N‐tropic or N‐tropic and X‐tropic viruses. All AKR spleen cultures and 5 of 7 hybrids expressed N‐tropic but not X‐tropic virus. X‐tropic virus expression was detected in all 6 NZB spleen cultures and in 5 of 8 hybrids. Virus expression did not occur in NIH Swiss or NIH Swiss/Nude (nu/nu) spleen or hybrid cultures. A major structural locus (Akv‐1) for N‐tropic virus expression has been assigned to chromosome 7 in AKR mice by recombi‐national genetics and is closely linked to the gene for glucose phosphate isomerase (Gpi‐1). Analysis of AKR hybrids confirmed the requirement of chromosome 7 for initial expression of mouse N‐tropic virus and, in addition, excluded the role of all other mouse chromosomes in this phenomenon. Eighteen of 20 BALB/c clones retained chromosome 7, including 6 virus‐positive clones, suggesting that chromosome 7 may be necessary but is not sufficient for N‐tropic virus expression in this strain. Hybrid clones with examples of asynteny were found for all other chromosomes. Long‐term passage and sub‐cloning studies of AKR and BALB/c virus‐positive hybrids indicated that virus‐positive clones segregated independently of chromosome 7 markers. Spontaneous expression of X‐tropic virus in NZB hybrid clones was syntenic with the gene for‐enylate kinase (Ak‐1) which is assigned to chromosome 2. A relatively small number of NZB hybrid clones were studied and, a firm gene assignment cannot be made, because only one discordant clone each was found for chromosomes 1, 3, 10, 19. Our studies indicate that spontaneous expression of MuLV strains does not require the following MuLV‐related genes: Fv‐1 (chromosome 4), Fv‐2 (chromosome 9), Rec‐1 (replication of ecotropic virus, chromosome 5), Gv‐1 and H‐2 (chromosome 17).

Mannosidosis: assignment of the lysosomal alpha-mannosidase B gene to chromosome 19 in man.

Human alpha-mannosidase activity (alpha-D-mannoside mannohydrolase, EC 3.2.1.24) from tissues and cultured skin fibroblasts was separated by gel electrophoresis into a neutral, cytoplasmic form (alpha-mannosidase A) and two closely related acidic, lysosomal components (alpha-mannosidase B). Human mannosidosis, an inherited glycoprotein storage disorder, has been associated with severe deficiency of both lysosomal alpha-mannosidase B molecular forms. Chromosome assignment of the gene coding for human alpha-mannosidase B (MANB) has been determined in human-mouse and human-Chinese hamster somatic cell hybrids. The human alpha-mannosidase B phenotype showed concordant segregation with the human enzyme glucosephosphate isomerase (GPI) (D-glucose-6-phosphate ketolisomerase, EC 5.3.1.9) but discordant segregation with 30 other enzyme markers representing 20 linkage groups. The glucose-phosphate isomerase gene has been assigned to chromosome 19 in man. This MANB-GPI linkage and confirming chromosome studies demonstrate assignment of the alpha-mannosidase B structural gene to chromosome 19 in man. Since mannosidosis is believed to result from a structural defect in alpha-mannosidase B, these findings suggest that the mannosidosis mutation is located on chromosome 19 in man.