Interaction of H-2Db with mutant histocompatibility gene H (KH-11) in the mouse

The detectable presence of H (KH-11)b, a mutant non-H-2 histocompatibility gene, was previously shown to depend upon the simultaneous presence, in the skin-graft donor, of both the mutant gene and the H-2b haplotype. The experiments reported here demonstrate that H-2Db is the essential element of H-2b for this interaction. Of two H-2Db histocompatibility mutations, H-2bm13 can replace H-2Db in this interaction, but H-2bm14 cannot.     

Control of protein synthesis in Escherichia coli: Lack of correlation with changes in intracellular pools of ATP,GTP, and ppGpp

Intracellular pools of ATP, GTP, and ppGpp have been measured in Escherichia coli after an energy source shift-down from glucose minimal to succinate-minimal medium. In a Tic⁺ strain (ATCC 10798), which reduces translational initiation after the down-shift, the rate of protein labeling falls to about 30% of its preshift rate within the first minute after shift and reaches a minimum of 17% by 6 min after shift. The ATP pool in this strain remains constant for about 10 min after shift, then declines gradually to about 60% of its initial level. The temporal discrepancy between protein synthesis and the decline in the ATP pool indicates that a decrease in intracellular ATP is not necessary for the control of protein synthesis. In a Tic^? strain (W1), which cannot control translational initiation under these conditions, the decline in the ATP pool is somewhat more rapid and more pronounced (to 40%) than in the Tic⁺ strain, indicating that the decline in the ATP pool is not sufficient to trigger control of translational initiation. The intracellular GTP pool in the Tic⁺ strain remains constant for 2 min after shift, then declines gradually to reach a minimum of 45% of its initial level at 20 min after shift. The pattern is in general similar in the the Tic^? strain, although the ultimate decline in GTP is more pronounced (to 29%). These data indicate that the decline in GTP is not sufficient and probably unnecessary to elicit control of translational initiation. Intracellular levels of ppGpp increase with very similar kinetics in relA⁺Tic⁺ (ATCC 10798) and relA⁺Tic^? (W1) strains, indicating that elevated ppGpp levels are not sufficient to elicit control of translation. In a relA^?Tic⁺ strain (NF162), or in a relA⁺Tic⁺ strain treated with rifampin, the ppGpp pool does not increase significantly after shift-down although translational initiation is reduced. Thus, an increase in the ppGpp pool is not necessary to control of translational initiation.     

Thyroglobulin interactions with thyroid plasma membranes. The existence of specific receptors and their potential role.

Thyroglobulin binds to isolated thyroid plasma membrane preparations. Binding is pH- and temperature-dependent with 10-fold better binding at pH 5.0 and 37 degrees C than at 0 degrees C and pH 6.0 through pH 7.5. Binding is, however, maximal in 90 min at all pH values and temperatures examined. Although salts can inhibit or enhance thyroglobulin binding depending on the temperature or pH, conditions approaching those of the physiological state are not inhibitory; physiological conditions do inhibit thyrotropin binding to the same membrane preparations. 125I-Labeled thyroglobulin binding is poorly reversed by unlabeled thyroglobulin at all pH values and temperatures studied; excess unlabeled thyroglobulin can, however, readily prevent binding. At pH values greater than 6.0 and at 0 degrees C, the iodine content of thyroglobulin can affect binding, and the 27 S thyroid iodoprotein is relatively ineffective in preventing the binding of the 19 S species. At pH 5.0 and 37 degrees C, there is no difference in binding of highly and less iodinated thyroglobulin, and the 27 S thyroglobulin iodoprotein is effective in preventing 19 S thyroglobulin binding. The complex nature of these results is interpreted in the light of additional data which show (i) that the thyroid membrane recognizes asialothyroglobulin and (ii) that at pH 5.0 and 37 degrees C a membrane-associated neuraminidase is activated which removes sialic acid from thyroglobulin. Vibrio cholerae neuraminidase can substitute for the endogenous neuraminidase. The receptor on thyroid membranes for asialothyroglobulin is similar to the asialoglycoprotein receptor on liver membranes (Morell, A.G., Gregoriadis, G., Scheinberg, I.H., Hickman, J., and Ashwell, G. (1971) J. Biol. Chem. 246, 1461-1467) in that sialic acid on the receptor is critical for receptor expression. It is distinct from the liver asialoglycoprotein receptor in its binding specificity and in its sensitivity to different bacterial and mammalian neuraminidase preparations. Relationships between thyroglobulin and thyrotropin receptors on thyroid membranes are explored, and the functional role of the thyroglobulin receptor is discussed.     

Sexual maturation among members of a transported troop of Japanese macaques (Macaca fuscata)

Data on the sexual maturation of a transported natural troop of Japanese macaques were collected during the 1973–74 and 1974–75 breeding seasons. Analysis of the data revealed that the sexual maturation of many monkeys was delayed one to two years. It is suggested that the delay of sexual maturation is related to a failure of the pubescent-aged monkeys to attain appropriate weight levels after transportation. This study was partially supported by a University of Oregon, Department of Anthropology PHS Biomedical Science Grant 50-262-1112.     

Maintenance of adult hamster pancreas cells on fibroblastic cells

Summary The maintenance of primary cultures of adult hamster pancreatic cells on layers of irradiated C3H/10T1/2 cells was studied. Various types of pancreatic cells, acinar, islet and ductular cells could be identified in the cultures by light and electron microscopy. Morphologically the various pancreatic cells retained many differentiated characteristics of their respective in vivo cell types. Insulin production was maintained at near Day 1 levels for the 16 d in culture for which it was measured. Colonies of epithelial cells continued to grow during a 20 d culture period. It is believed that this procedure for maintaining functional and growing pancreas cells in culture may be a useful in vitro model for studying the initiation of pancreatic carcinogenesis. Supported by Grant R01 CA 20022 and Contract N01 CP33278 from the National Cancer Institute, National Institutes of Health, Bethesda, Maryland.     

Strong teratocarcinoma transplantation loci,Gt-1 and Gt-2, Flank H-2

Evidence is presented for the existence of two strong murine teratocarcinoma transplantation antigens (Gt) on the cell line PCC3. It is shown that the loci governing expression of these antigens are linked to the H-2 complex. These loci have been further mapped with respect to the brachyury marker (T) and H-2: Gt-1 lies 5±2 crossover units proximal to H-2 and 12±2 crossover units distal to T, Gt-2 lies 21±4 crossover units distal to H-2. It is possible that these strong transplantation antigens provide an embryonic analogue to the adult major histocompatibility system.     

Reduction and azo coupling of quinones

Summary Cutaneous melanin in formol fixed skin and adrenochrome in dichromate fixed monkey adrenal after adequate bisulfite or dithonite reduction were found to give definite azo coupling reactions. Weaker reactions were obtained on unreduced material, and these disappeared on ferric chloride oxidation. Both cutaneous melanin and adrenochrome appear to exist in a quinhydrone status. Prolongation of dichromate treatment weakens or abolishes azo coupling capacity of adrenochrome. The findings support the concept of quinonization and reduction to prevent and restore azo coupling of enterochromaffin cells and noradrenaline islets of the adrenal.The most effective diazos for melanin werep-nitrodiazobenzene, fast black K and the diazosulfanilic acid, pH 1 pyronin B procedure, for adrenochrome. Diazosafranin and 2-chloro-4-nitrodiazobenzene were also useful. Blue and violet coupling products from toluidine blue and methylene violet RR fail to yield sufficient contrast to be convincing.     

Ribosomal RNA homologies and the evolution of the filamentous blue-green bacteria

Summary Ribosomal RNA (rRNA) sequence homology (as determined by comparisons of T1 oligonucleotide catalogs of³²P-labeled 16S rRNAs) has been used to assess phylogenetic relationships within the filamentous and unicellular blue-green bacteria, and to identify regions of evolutionary conservatism within blue-green bacterial 16S rRNAs.Nostoc andFischerella, representatives of two morphologically distinct and highly differentiated orders, are shown to be as closely related (on the basis of RNA sequence homology) as typical members of the non-blue-green bacterial genusBacillus. They are further shown to be (on the same basis) indistinguishable from typical unicellular members of a subgroup of the unicellular blue-green bacterial order Chroococcales. These results have general implications for studies of the origin of differentiated prokaryotes and of evolutionary change in prokaryotic macromolecules. In particular, they provide indirect evidence that the divergences of contemporary major prokaryotic groups are truly ancient ones.     

Adenine deaminase of a eukaryotic animal cell,Crithidia fasciculata

Adenine deaminase (adenine aminohydrolase, EC 3.5.4.2) has been found to occur in Crithidia fasciculata with a specific activity higher than that of the same enzymes of bacteria and yeasts. It is remarkable for its stability to heat, exhibiting no appreciable loss of activity after 60 min at 55 °C. It occurs in the soluble portion of cell extracts but can be released into the suspending medium by osmotic and/or cold shock.