Cell-free translation of mouse liver mRNA coding for two forms of UDP glucuronosyltransferase

Mouse liver poly(A) RNA, when translated in vitro, produced two forms of UDP glucuronosyltransferase with molecular weights of approximately 50,000 and 54,000 (designated GTm1 and GTm2, respectively). These forms were identified by antibody prepared against GTm1. The mRNA coding for GTm1 was preferentially increased twofold after treatment of mice with 3-methylcholanthrene, while GTm2 mRNA was unaffected. Phenobarbital, however, increased the translatable levels of the mRNAs coding for both proteins approximately twofold. GTm1 was shown to be glycosylated during translation in the presence of dog pancreatic microsomes. This was reflected by a decrease in mobility of the protein in sodium dodecyl sulfate-polyacrylamide gels as compared to GTm1 translated in the absence of microsomes. Further evidence for glycosylation in vivo was demonstrated by an increase in the mobility of GTm1 immunoadsorbed from microsomes treated with endoglycosidase H. In contrast, GTm2 was unmodified. This apparent difference in the state of glycosylation may reflect a difference in the transmembrane distribution of these two enzyme forms, and hence play an important role in determining the type of aglycone glucuronidated and its route of removal from the cell.     

The nucleotide sequence of adenovirus type 5 early region E1: the region between map positions 8.0 (HindIII site) and 11.8 (SmaI site)

The nucleotide sequence of the region between map positions 8.0 (HindIII site) and 11.8 (SmaI site) of adenovirus type 5 (Ad5) has been determined. Together with the sequences reported earlier (Van Ormondt et al., 1978; Maat and Van Ormondt, 1979) it encompasses the entire leftmost early region E1 of Ad5 DNA (4126 base pairs). The total sequence revealed a number of potential regulatory signals (promoter sites, ribosome binding sites, 3'-poly(A)-associated sequences), which confirm that region E1 is divided into subregions, E1a and E1b, and a region coding for semi-late viral protein IX. By taking into account the adenovirus 2 (Ad2) RNA-splicing data of Perricaudet et al. (1979; 1980) and the Ad2 RNA mapping data of Chow et al. (1979) we predict that E1a codes for polypeptides of 32, 26 and ca. 13 kd, and subregion E1b for polypeptides of 67 kd and 20 kd; the expected molecular weight of protein IX is 14.4 kd.     

Purification of microtubule protein from beef brain and comparison of the assembly requirements for neuronal microtubules isolated from beef and hog.

The polymerization of microtubule protein from beef brain is inefficient under the same conditions which are optimal for the assembly of microtubules isolated from hog brain (0.1 m piperazine-N,N′-bis(2-ethanesulfonic acid) buffer at pH 6.94). In examining the conditions required for microtubule polymerization in both beef brain extract and purified microtuble protein, it was determined that the pH optimum was pH 6.62 or 0.3 pH unit lower than the reported optimum for hog. Other assembly requirements (ionic strength, Mg²⁺ and nucleotide concentration, temperature) remained essentially the same as for hog. By separating and recombining fractions of tubulin and nontubulin components prepared from beef and hog microtubule protein, the requirement for the reduction in pH was found to be due to the tubulin and not to the microtubule-associated proteins. It was also determined that the efficiency of beef tubulin assembly, as measured by the yield of microtubule polymer, decreased rapidly after slaughter with a half-time of 19 min. Furthermore, when the overall efficiency of polymerization was reduced, the extent of assembly at each cycle of purification by disassembly and assembly was also observed to be depressed. The variations in the requirements for neuronal tubulin assembly in two closely related mammals suggest that the conditions required for assembly of microtubule protein in other tissues and cell types may also be different.     

Sizes and mass distributions of clathrin-coated vesicles from bovine brain

Clathrin-coated vesicles obtained from bovine brain have been studied by ultracentrifugation and dynamic light scattering techniques to provide information on their sedimentation and mass distributions and their average diffusion coefficients. "Uncoated" vesicles, obtained by removing the protein coat from coated vesicles, have been similarly characterized. For typical preparations, maximal values of approximately 210 and 95 S are observed for the sedimentation coefficients of coated and uncoated vesicles, respectively. Corresponding values for the average molecular weights, determined from values of average sedimentation and diffusion coefficients, are 49 X 10(6) and 13 X 10(6); values obtained by equilibrium sedimentation are 37.2 X 10(6) and 10.6 X 10(6). In order to obtain these results, some minor modifications of sedimentation and light-scattering techniques have been devised which may have application to other studies of size distributions of large particles.     

Induction of monocytic suppression after stimulation of peripheral human mononuclear cells with staphylococcal protein A and Staphylococcus aureus

Staphylococcal protein-A (SPA) and Staphylococcus aureus are known to be polyclonal human B-cell activators. It was noted that they induced plaque-forming-cell (PFC) responses lower than those induced by pokeweed mitogen (PWM) and the possibility of early triggering of a suppressor cell was investigated in the present series of experiments. Peripheral mononuclear cells (MNC) were passed through Sephadex G-10 columns to eliminate monocytes. The PFC responses to SPA and S. aureus were thereby increased. PWM-driven PFC responses are suppressed by the simultaneous presence of SPA in a dose-related way, if present in the early phases of the cultures. MNC precultured with SPA or S. aureus have the ability to suppress the PFC response of autologous MNC to PWM. Interestingly this suppressor cell activity was radiation resistant and could not be abrogated by treatment with anti-T-cell monoclonal antibody plus complement. The above experiments clearly demonstrate that the observed low PFC responses of MNC after stimulation with SPA and S. aureus are due to the induction of suppressor cells by these stimulants. The suppressor cells are apparently of monocytic origin.     

Many monoclonal antibodies with an apparent specificity for certain lung cancers are directed against a sugar sequence found in lacto-N-fucopentaose III

Monoclonal antibodies with an apparent specificity for human small-cell carcinoma, adenocarcinoma, and squamous carcinoma of the lung are produced by some hybridomas obtained from mice and rats immunized with an established line of human small cell lung cancer. Out of 85 of these antibodies produced by independently isolated hybridomas from 15 different fusions, 21 are directed against the sugar sequence which occurs in lacto-N-fucopentaose III ceramide, in several higher glycolipids and in glycoproteins. Specificity was determined by autoradiography of thin-layer chromatograms of glycolipids, by solid-phase radioimmunoassays, and by hapten inhibition studies. All 21 antibodies are of the immunoglobulin M type.     

Phosphorylation of troponin and myosin light chain by cAMP-independent casein kinase-2 from rabbit skeletal muscle

Casein kinase-2 from rabbit skeletal muscle was found to phosphorylate, in addition to glycogen synthase, troponin from skeletal muscle, and myosin light chain from smooth muscle. Troponin T and the 20,000 M_r myosin light chain are phosphorylated by casein kinase-2 at much greater rates than glycogen synthase. The V values for the phosphorylation of troponin and myosin light chain are nearly an order of magnitude greater than that of glycogen synthase; however, the K_m values for these two substrates are greater than that for glycogen synthase. The kinase activities with the various protein substrates are stimulated approximately three- and fivefold by 5 mm spermidine and 3 mm spermine, respectively. Heparin is a potent inhibitor of the kinase when casein, glycogen synthase, or myosin light chain is the substrate. However, with troponin as substrate the kinase is relatively insensitive to inhibition by heparin. The amount of heparin required for 50% inhibition with troponin as substrate is at least 10 times greater than with casein as substrate. The phosphorylation of troponin by casein kinase-2 results in the incorporation of phosphate into two major tryptic peptides, which are different from those phosphorylated by casein kinase-1. The site in myosin light chain phosphorylated by casein kinase-2 is different from that phosphorylated by myosin light chain kinase.     

Macrophages as effector cells of protective immunity in murine schistosomiasis: IV. Coincident induction of macrophage activation for extracellular killing of schistosomula and tumor cells

Peritoneal macrophages from Schistosoma mansoni-infected mice are activated both for nonspecific tumor cytotoxicity and for killing of skin-stage schistosomula in vitro. In the current study, mechanisms for induction of macrophage tumoricidal and schistosomulacidal activity have been compared. Examination of macrophages activated in vivo by BCG infection or C. parvum treatment, or in vitro by exposure to lymphokine prepared from antigen-stimulated BCG-immune spleen cells, showed that these effector functions were closely linked. Indeed, fractionation of lymphokine-rich supernatant fluids by Sephadex G-100 gel filtraction showed that activities responsible for induction of schistomula killing by inflammatory macrophages and for induction of tumoricidal activity cochromatographed as a single peak in the 50,000 MW region. Thus, development of macrophage-mediated cytotoxicity against these two extracellular (tumor cell or helminth) targets was coincident in several cell populations activated in vivo or in vitro. However, activation for tumoricidal and schistosomulacidal capacity appeared to be quantitatively dissociated in macrophages from mice with chronic schistosomiasis; those cells demonstrated low, yet significant, levels of larval killing ($\text{1}\text{3}$ to $\text{1}\text{5}$ those of BCG or lymphokine-activated cells) but maximal levels of tumor cell cytotoxicity. Furthermore, cytotoxicity by peritoneal cells from S. mansoni-infected mice was not increased in vitro by exposure to lymphokine. Identification of this functional alteration in S. mansoni-activated cells may help to clarify the role of macrophages in the partial immunity against challenge infection which is demonstrated by mice with chronic primary S. mansoni infection.     

Effect of crude and purified human chorionic gonadotropin on murine delayed-type hypersensitivity: A role for prostaglandins

In this study we report a significant inhibition of delayed-type hypersensitivity (DTH) reactions in mice pretreated for 5 days with different doses of a crude or a purified preparation of human chorionic gonadotropin (HCG). Purified HCG was found to be more potent than crude HCG in its immunosuppressive capacity, while the HCG subunits and desialylated HCG were without immunosuppressive effect. The inhibition of the DTH reaction was completely reversed by the simultaneous injection of indomethacin or aspirin, two known inhibitors of prostaglandin synthesis. Our findings indicate that HCG itself can suppress the DTH response and that the mechanism involves the release of prostaglandins.