Carbohydrate-containing endothelial cells lining the bulbus arteriosus of teleosts and the conus arteriosus of elasmobranchs (Pisces)

The study is a survey of the shape and carbohydrate histochemistry of the endothelial cells lining the conus arteriosus of 10 species of elasmobranchs and the bulbus arteriosus of 80 species of teleosts. Intensely PAS-positive cells that were often tall, were found in many teleosts and were typical of phylogenetically advanced species. They were not seen in any elasmobranch. Most of the teleosts with strongly PAS-positive cells were marine fish or euryhaline animals that were caught in freshwater. Beyond this, it is difficult to generalize on their life-style or habitat, for they included small fish, large fish, fast swimmers, bottom-living forms, deep-water fish, littoral species and Antarctic "bloodless" forms. It is likely that the PAS-positivity of the endothelial cells can be attributed to the moderately-dense granules revealed by E.M., but as yet the significance of these is unclear.     

Suppressor cells in tolerance to HGG: kinetics and cross-suppression in high dose tolerance--absence in low dose tolerance.

Spleen cells from mice made tolerant with high doses of human gamma-globulin (HGG) specifically suppress the immune response of normal, syngeneic, spleen cells. These suppressor cells were found to be cross-reactive in that they would suppress the immune response of normal spleen cells to bovine gamma-globulin (BGG) as well as to HGG. In contrast, suppressor cells could not be demonstrated in spleens of mice made tolerant with low doses of HGG (i.e., T-cell tolerance), nor could they be found in high dose tolerant mice following a second injection of DHGG at a time when the initial suppressor activity had waned. The role of suppressor cells in the induction, maintenance, and loss of tolerance is discussed.     

Neonatally induced tolerance to HGG: duration in B cells and absence of specific suppressor cells.

A specific, long lasting, tolerant state to human gamma-globulin (HCG) was established in neonatal A/J mice. These suckling mice received the tolerogen in the colostrum of their mother who had been injected with DHGG. The tolerant state could not be accounted for by "factors" other than HGG in the colostrum. The duration of this tolerance in the intact animal and in the B cell population was 16 to 18 weeks. Naturally occuring nonspecific suppressor cells were evident but specific suppressor cells could not be demonstrated. These results are discussed in relation to possible mechanisms of the induction of tolerance to self.     

Resonance raman spectroscopy of chemically modified and isotopically labelled purple membranes. II. Kinetic studies

Kinetic resonance Raman spectra of native and isotopically labelled purple membranes are compared. Using these data and the assignments of the previous paper in this sequence, we have confirmed that the Schiff base is deprotonated at times that are short in comparison to M₄₁₂ evolution. In addition, by monitoring the kinetic resonance Raman spectra in ²H₂O with 488.0 nm excitation we have been able to characterize in more detail the vibrational features associated with this unprotonated intermediate that precedes M₄₁₂. Furthermore, the kinetic spectra of fully deuterated purple membranes in H₂O have allowed us to assign the 1465 cm⁻¹ band in these spectra to the C=C stretching frequency of BR₅₇₀ and the 1512 cm⁻¹ band to the C=C stretching frequency of M₄₁₂. These spectra have also provided an indication of a Raman spectral feature associated with O₆₄₀ and, finally, our kinetic spectra have provided evidence that there is a significant alteration in the rate constants for the evolution of the various intermediates when the non-exchangeable protons on the membrane are replaced by deuterons.     

Expression of alien histocompatibility antigens on SJL/J tumors detected by cell-mediated and serological analyses

Summary Reticulum cell sarcoma (RCS) cells of SJL/J (H-2^s) mice have been shown to express antigens that are cross-reactive with allogeneic cells of the H-2^d and H-2^b haplotypes by cell-mediated cytotoxicity, antibody-mediated cytotoxicity, immunofluorescence, and quantitative absorption assays. These alien antigens have been detected on both spontaneous and in vivo- and in vitro-passaged RCS cells to varying degrees.The in vitro cell lines were able to stimulate a syngeneic cytotoxic T cell response detected in a 4-h ⁵¹Cr release assay. The cytotoxic cells reacted with in vitro RCS tumor targets but not with in vivo or spontaneous RCS tumors. Furthermore, the cytotoxic cells lysed H-2^d and to a lesser extent H-2^b target cells, but not H-2^k, H-2^p, or H-2^r cells. The cross-reactivity was also observed with SJL/J anti-BALB/c cytotoxic cells, which can lyse in vitro RCS targets effectively. The in vivo tumors were not stimulatory in cytotoxic responses and did not serve as targets.H-2^d specificities were also detected in cultured RCS tumor cells by cytotoxic antibody. Both allogeneic SJL/J anti-BALB/c, C57B1/6 anti-BALB/c sera reacted with RCS tumor cells and not normal SJL/J cells. Furthermore, monospecific D^d sera were also cytotoxic against RCS lines. The cytotoxic activity could be absorbed by BALB/c cells and RCS cells but not with normal SJL/J cells. The H-2^d specificities were also detected on the in vivo lines by indirect immunofluorescence. The majority (60%) of spontaneously arising tumors expressed either H-2^d or H-2^b allospecificities in the immunofluorescence assays. Although these antigens may not be inappropriate for the SJL/J strain, their differential expression on tumor cells may be significant in the etiology of the tumor.     

Ly-m19: The Lyb-2 region of mouse chromosome 4 controls a new surface alloantigen

Spleen cells from an SJL mouse immunized with 70'/3 cells, an established pre-B cell line, were fused with cells of the nonsecretor myeloma line NS.1. One established hybridoma cell line (clone K10.6) continuously secreted antibody that recognized a new antigenic specificity tentatively named Ly-m19. This newly found antigen is detectable on both T and B cells. Cytotoxicity assays reveal that 75 percent of the spleen and lymph-node cells, 35 percent of bone-marrow cells, and 15 percent of thymus cells reacted with antibody of clone K10.6. Strains expressing the specificity Ly-m19.1 are characterized by negative reactions and include the strains AKR, CE/J, RF/J, GR/A, SJL, P/J, BDP/J, and LG/J. All other strains so far tested are Ly-m19.2. This strain distribution pattern distinguishes Ly-m19 from any known murine lymphocyte alloantigen, but it parallels the Lyb-2 ^c haplotype. Linkage test of a set of AKXL recombinant inbred strains revealed close linkage of Ly-m19 and Lyb-2 loci on mouse chromosome 4.Abbreviations used in this paper LPS lipopolysaccharide - B6 C57BL/6 - Con-A concanavalin A - MLC mixed-lymphocyte culture The prefix m (monoclonal) is used following a suggestion by Klein and co-workers (1979).     

Evidence for an essential arginine residue at the active site of ATP citrate lyase from rat liver.

Rat liver ATP citrate lyase was inactivated by 2, 3-butanedione and phenylglyoxal. Phenylglyoxal caused the most rapid and complete inactivation of enzyme activity in 4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid buffer, pH 8. Inactivation by both butanedione and phenylglyoxal was concentration-dependent and followed pseudo- first-order kinetics. Phenylglyoxal also decreased autophosphorylation (catalytic phosphate) of ATP citrate lyase. Inactivation by phenylglyoxal and butanedione was due to the modification of enzyme arginine residues: the modified enzyme failed to bind to CoA-agarose. The V declined as a function of inactivation, but the Km values were unaltered. The substrates, CoASH and CoASH plus citrate, protected the enzyme significantly against inactivation, but ATP provided little protection. Inactivation with excess reagent modified about eight arginine residues per monomer of enzyme. Citrate, CoASH and ATP protected two to three arginine residues from modification by phenylglyoxal. Analysis of the data by statistical methods suggested that the inactivation was due to modification of one essential arginine residue per monomer of lyase, which was modified 1.5 times more rapidly than were the other arginine residues. Our results suggest that this essential arginine residue is at the CoASH binding site.     

Role of silicon in diatom metabolism

Levels of the cyclic nucleotides, cAMP and cGMP, were determined in four species of pennate diatoms; changes in their levels and ratios were monitored in silicon-starved and light-dark synchronized cultures of Cylindrotheca fusiformis. Content of both cAMP and cGMP changed during the cell cycles: when silicate was added to starved cultures, cAMP, cGMP and DNA levels rose rapidly; cAMP and cGMP declined before DNA synthesis was complete and continued to fall during the events leading to cell separation. In unstarved synchronies, net synthesis of DNA continued until cell separation; 1 h before cell separation cAMP levels fell while those of cGMP rose. The results support the proposal that cAMP and cGMP may play a part in the process of cell division in the diatom, possibly involving silicon.     

Location ofMls locus on mouse chromosome 1

Linkage between theMls locus and the chromosome 1 markersDip-1 andald was detected using two sets of recombinant inbred strains. Linkage betweenMls andDip-1 was confirmed in the fifth and sixth backcross generations of an incipient congenic strain. The AKXL data indicate that the gene order isDip-1-ald-Mls. The recombination frequency betweenald andMls is estimated to be 0.07 ±0.05, based on the AKXL data. The recombination frequency betweenDip-1 andMls is estimated to be 0.18 ±0.04, based on all the available data.