Brucella abortus is the causative agent for brucellosis in cattle and man. Development of a single diagnostic test for the differentiation of vaccinated from infected animals and the development of a nonviable 'subunit' vaccine are top priorities of the brucellosis research program in the United States. Preliminary evidence previously showed that a purified 31-kDa protein (thought to be localized at or near the bacterial cell surface) protects against experimental brucellosis in rodents. The gene for this 31-kDa protein has now been cloned in Escherichia coli. The protein is expressed well, apparently from its native promoter, when placed in several different E. coli plasmids. The nucleotide sequence of the flanking and encoding sequences has been determined, and comparison with the N-terminal amino acid (aa) sequence of the mature protein indicates the presence of a putative 28-aa signal sequence. The availability of the 31-kDa protein free of Brucella contaminants now allows rigorous study of the immunological properties of this protein.

Allophenic mice are chimeras which are produced from the aggregation of two genotypically distinct embryos. In this study, embryos from the C57BL/6J and A/J strains were used to produce C57BL/6J ↔ A/J allophenic mice. These strains were chosen because of their markedly different lifespans, their different glucose phosphate isomerase (GPI) isozymes, and their different H-2 haplotypes [C57BL/6J: long-lived, Gpi-1b, H-2b; A/J: short-lived, Gpi-1a, H-2a. The mice were bled at two month intervals and the composition of their peripheral blood lymphocytes determined at each point from analysis of GPI isozymes and H-2 antigens. It was founr that the proportion of long-lived (C57BL/6J) lymphocytes tended to increase with age. Moreover, the total lifespan of the allophenic mice was directly related to the percentage of long-lived lymphocytes in their peripheral blood.

In a comparative study of A/J (Gpi-1a) and C57BL/6J (Gpi-1b) mice, we observed that erythrocytes of A/J mice exhibited significantly higher glucose phosphate isomerase (GPI) activity compared to erythrocytes of C57BL/6J mice on a per cell, per gram of protein, or per gram of hemoglobin basis. Higher GPI activity per cell was detected for peripheral blood lymphocytes of A/J compared to C57BL/6J mice. (A/J × C57BL/6J)F1 mice expressed erythrocyte and peripheral blood lymphocyte GPI activities intermediate to those of the parental mouse strains. The GPI activities of spleen lymphocytes from A/J, C57BL/6J, or (A/J × C57BL/6J)F1 mice were not significantly different from each other. The higher activity in the A/J mice could be due to GPI of a higher catalytic rate or to the presence of more GPI molecules. In order to distinguish these two possibilities, GPI was purified to homogeneity from both strains of mice. The specific activities (activity per milligram of protein) of the purified enzymes from the two strains were found to be similar, indicating that GPI from the A/J strain was not a more active enzyme. Antibody to the purified enzymes was prepared and used in an enzyme-linked immunosorbent assay (ELISA) to compare the relative amounts of enzyme molecules in cells of A/J and C57BL/6J mice. Results of the ELISA tests on peripheral blood lymphocytes indicated that A/J mice contain more molecules of GPI per cell and, therefore, have a higher GPI activity than C57BL/6J mice.

Glucose phosphate isomerase (GPI) enzyme activity was measured in two strains of mice, A/HeNNial (Gpi-1a) and C57BL/6NNia1 (Gpi-1b). Seven solid tissues (muscle, brain, heart, kidney, liver, lung, spleen) and three cell types (peripheral blood lymphocytes, spleen lymphocytes, erythrocytes) were analyzed for GPI activity in mice from 6 to 36 months of age. No major changes in enzyme activity with age were found. The most striking observation was that A/HeNNial mice showed a significantly higher GPI activity than C57BL/6NNia1 mice in four of the solid tissues (muscle, heart, kidney, spleen) and two of the cell types (peripheral blood lymphocytes, erythrocytes) analyzed.

Analysis of C57BL/6J in equilibrium A/J allophenic mice for their lymphocyte composition, using H-2 antigens as external markers, and glucose phosphate isomerase (GPI) isozymes as internal markers, has led to the discovery of two unusual mice. Both mice showed heterodimers of GPI isozymes upon electrophoresis of the lymphocyte lysate. Specific anti-H-2 antisera confirmed that the cells of the mice were of C57BL/6J and A/J origin, as expected, but that the "A/J" cells seemed to behave as F1 hybrids containing the Gpi-1a and Gpi-1b alleles. Possible origins of the Gpi-1b allele in the "A/J" cells are discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetic properties of human erythrocyte glucose 6-phosphate dehydrogenaseSteven J. Soldin and Doris. BalinskyCite this: Biochemistry 1968, 7, 3, 1077–1082Publication Date (Print):March 1, 1968Publication History Published online1 May 2002Published inissue 1 March 1968https://pubs.acs.org/doi/10.1021/bi00843a027https://doi.org/10.1021/bi00843a027research-articleACS PublicationsRequest reuse permissionsArticle Views154Altmetric-Citations50LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts