Murine liver arylsulfatase B processing influenced by region on chromosome 17

Mapping Genes Is Good for You

I abandoned my original career choice of high school teaching to pursue dentistry and soon abandoned that path for genetics. The latter decision was due to a challenge by a professor that led to me reading Nobel speeches by pioneer geneticists before I had formal exposure to the subject. Even then, I was 15 years into my career before my interest in rodent genomes gave way to mapping cattle genes. Events behind these twists and turns in my career path comprise the first part of this review. The remainder is a review of the development of the field of bovine genomics from my personal perspective. I have had the pleasure of working with outstanding graduate students, postdocs, and colleagues to contribute my small part to a discipline that has evolved from a few individuals mapping an orphan genome to a discipline underlying a revolution in animal breeding.

PFGE mapping and RFLP analysis of the S/D region of the mouse H-2 complex

We have constructed a long range restriction map of the S/D segment of the mouse H-2 complex by pulsed field gel electrophoresis and hybridization with mouse cDNA probes to Bf and Tnfa genes and human cDNA probes to BAT2, BAT3, BAT4, BAT5, and BAT6 genes which have recently been mapped to the human HLA complex between C2 and HLA-B. The distance between the mouse C2 and Tnfa genes was found to be approximately 350 kilobases. The position of the mouse Bat genes in this map were found to be comparable to the position of the BAT genes in the human HLA complex. A panel of recombinant mouse strains was also examined by restriction fragment analysis with probes detecting the Hsp70, Bat5, and Tnfa genes. The results indicate that recombination in this segment is not random. No recombinants were found with crossovers between the C2 and Hsp70 genes and only one recombinant was found with a crossover between Tnfa and H-2D. In contrast, the crossover sites of 16 recombinants were mapped between the Hsp70 and Tnfa genes. Seven of these recombinants were found to have crossovers between Hsp70 and Bat5 and three recombinants were found to have crossover sites between Bat5 and Tnfa.

Arylsulfatase B synthesis and clearance in inbred mouse strains

Arylsulfatase B activity levels were approximately 2-3-fold higher in adult C57BL/6J liver and kidney compared to corresponding tissues from A/J inbred mice. In vivo incorporation of tritiated leucine into C57BL/6J hepatic arylsulfatase B reached a maximum approximately 15 h after injection. The label was cleared from C57BL/6J arylsulfatase B with an apparent half-life of 36 h. The relative rates of synthesis of C57BL/6J and A/J arylsulfatase B were similar; however, the A/J enzyme was cleared more rapidly from liver tissue. C57BL/6J kidney arylsulfatase B appeared to be synthesized at a 2-3-fold higher rate than the corresponding A/J enzyme. These trends suggest genetic regulation of arylsulfatase B is effected through different means in liver and kidney from adult mice of these two inbred strains.

Purification and properties of arylsulfatase B from high- and low-activity mouse strains

Arylsulfatase B (arylsulfate sulfohydrolase; EC 3.1.6.1) activities in C57BL/6J, SWR/J, and A/J mouse liver approximate a 5:3:1 ratio. Each enzyme was purified to apparent homogeneity, and the properties of the three purified enzymes were compared. The purified enzyme behaved as a monomer with an apparent molecular weight of 50,000. The purified enzyme catalyzed the hydrolysis of p-nitrocatechol sulfate (pNCS), 4-methylumbelliferyl sulfate (4MUS), and chondroitin-4-sulfate (C4S) heptasaccharide. Purified SWR/J arylsulfatase B possessed a higher relative electrophoretic mobility at pH 4.0 than the A/J and C57BL/6J isozymes, and the SWR/J enzyme was more thermostable than either the C57BL/6J or the A/J enzyme. No differences were observed among the three enzymes with respect to their Michaelis constants for 4MUS and pNCS, isoelectric points, responses to inhibitors, pH optima, or electrophoretic mobilities at pH 8.3. The relative in vivo rates of synthesis of C57BL/6J, A/J, and SWR/J arylsulfatase B were comparable.

Activation of T lymphocytes results in an increase in H-2-encoded neuraminidase

The endogenous neuraminidase activity of various mouse lymphoid subpopulations and tissue compartments was examined by a sensitive fluorometric assay. These analyses indicated that activated T lymphocytes possessed a significantly higher level of intracellular neuraminidase than activated B or resting T or B lymphocytes. Examination of the level of neuraminidase in bone marrow, thymus, lymph node, and unfractionated spleen indicated that these lymphoid tissues contained significantly less neuraminidase than was detected in stimulated T cells. Kinetic studies revealed that the majority of the increase in neuraminidase activity occurred between 24 and 48 h following stimulation. Analysis of activated T lymphocytes prepared from a panel of inbred mouse strains indicated that cells from mice of the H-2v haplotype, which possess the Neu-1a allele and are deficient in liver neuraminidase, exhibited a level of activity which was significantly lower than that detected in stimulated T cells from other mouse strains. These results indicate that the endogenous neuraminidase activity of T lymphocytes increases upon stimulation, and that the level of this enzyme activity in lymphoid cells is also controlled by the Neu-1 locus, which is located in the H-2 region of the major histocompatibility complex.

Biochemical characterization of arylsulfatases detected in granulomatous inflammation

Arylsulfatases A and B were measured in the liver of mice infected with Schistosoma mansoni. The increase of total arylsulfatases paralleled enlargement of the granulomas. It began at 7 weeks after infection and reached a maximum at 10 to 14 weeks when the enzyme activity became about 2.5 times that of normal liver. The elevated enzyme activity was due to granulomatous tissue, because when granulomas were separated from hepatic cells, the former contained the increased activity but the latter did not. Arylsulfatase A, arylsulfatase B, and arylsulfatase Bv, in both normal liver and granulomas, were separated by anion-exchange column chromatography and differences in net charges of these enzymes were demonstrated by polyacrylamide gel electrophoresis. Biochemical properties were indistinguishable between arylsulfatase B and arylsulfatase Bv while they differed from arylsulfatase A. Granulomas at 8 weeks after infection showed 3.0-, 3.5-, and 5.0-fold increases in activity for arylsulfatase A, B, and Bv, respectively. As the granulomas enlarged, by 12 weeks, arylsulfatases B and Bv activities further increased but the arylsulfatase A value remained the same as that of 8 weeks. The finding suggests that arylsulfatases are involved in granuloma development and arylsulfatases B and Bv activities may reflect functions of macrophages and other cells including fibroblasts.

Gene for neuraminidase activity on mouse chromosome 17 near h-2: pleiotropic effects on multiple hydrolases

The low activity of liver neuraminidase that is characteristic of mouse strain SM/J is inherited as a single gene on chromosome 17, near the major histocompatibility complex. This gene, neuraminidase-1 (Neu-1), is represented by the low activity allele Neu-1s in SM/J and the high activity allele Neu-1b in C57BL/6J and most other strains. Previously described variations in the posttranslational processing of acid phosphatase, alpha-mannosidase, arylsulfatase-B, and alpha-glucosidase are attributed to pleiotropic effects of this gene.