Showing papers by "Laboratory of Molecular Biology published in 1979"
TL;DR: M1/70 thus defines a differentiation antigen on mononuclear phagocytes and granulocytes, the expression of which is specifically increased during monocyte maturation, the first to be described which recognizes a discrete molecule specific to phagocyte.
Abstract: We have previously described the derivation of M1/70, a hybrid myeloma line secreting monoclonal rat anti-mouse cell surface antibody (Springer, T., Galfre, G., Secher, D. S. and Milstein, C, Eur. J. Immunol. 1978. 8: 539). We have now investigated the cellular distribution of this antigen using a 125I-labeled anti-rat IgG indirect binding assay, the fluorescence-activated cell sorter, autoradiography and precipitation of cell surface molecules. Screening with a tumor cell panel showed strong reactivity with a macrophage-like line but no reactivity with B or T lymphoma lines. In normal tissues, M1/70 antigen was found to be present in small amounts on spleen and exudate granulocytes and a subpopulation of bone marrow cells, in moderate amounts on spleen and blood monocytes and expressed in much larger amounts on spleen histiocytes and peritoneal exudate macrophages. In contrast, M1/70 antigen was found to be absent from erythroid and lymphoid cells. M1/70 antibody precipitated two polypeptides of 190 000 and 105 000 mol. wt. which were present in much greater amounts on peritoneal exudate macrophages than on spleen cells. The expression on phagocytes of two other antigens identified by monoclonal antibodies M1/69 and M1/9.3 was also examined. Monocytes and granulocytes expressed large amounts of M1/69 and low amounts of M1/70 antigen, while in peritoneal exudate macrophages this pattern was dramatically reversed. M1/70 thus defines a differentiation antigen on mononuclear phagocytes and granulocytes, the expression of which is specifically increased during monocyte maturation. This antibody is the first to be described which recognizes a discrete molecule specific to phagocytes.
1,117 citations
TL;DR: These structural results, together with other work, particularly the calculations of Gelin & Karplus and of Warshel, support a description of the haemoglobin mechanism in which the binding of ligand to the deoxy form is accompanied by steric strain, so that the proportion of molecules in the high-affinity form increases as successive ligands bind.
802 citations
TL;DR: The frequency of males among the self progeny of wild-type Caenorhabditis elegans hermaphrodites (5AA; XX) is about one in 500, and fifteen him mutations have been identified that increase this frequency by a factor of ten to 150, as a result of increased X-chromosome nondisjunction.
Abstract: The frequency of males (5AA; XO) among the self progeny of wild-type Caenorhabditis elegans hermaphrodites (5AA; XX) is about one in 500. Fifteen him (for "high incidence of males") mutations have been identified that increase this frequency by a factor of ten to 150, as a result of increased X-chromosome nondisjunction. The mutations define ten complementation groups, which have been mapped: nine are autosomal, and one sex linked. Most of the mutants are superficially wild type in anatomy and behavior; however, him-4 mutants display gonadal abnormalities, and unc-86 mutants, which have a Him phenotype, exhibit a variety of anatomical and behavioral abnormalities. All the mutants segregate fertile 3X hermaphrodite progeny as well as XO male progeny. Some produce large numbers of inviable zygotes. Mutants in all ten genes produce diplo-X and nullo-X exceptional ova, and in the four strains tested, diplo-X and nullo-X exceptional sperm are produced by 2X "transformed" males. It appears likely that most of the mutants have defects in both gamete lines of the hermaphrodite. XO males of him strains other than him-4 and unc-86 are similar to wild-type males in anatomy and behavior, and all produce equal or almost equal numbers of haplo-X and nullo-X sperm, and no diplo-X sperm. Male fertility is reduced to varying extents in all him mutants. In four of the strains, nondisjunction during oogenesis has been shown to occur at a reductional division, and in three of these strains, abnormalities in recombination have been demonstrated. One mutant also exhibits autosomal nondisjunction, but many of the others probably do not. Therefore, the X chromosome of C. elegans may differ from the autosomes in the mechanisms controlling its meiotic behavior.--3X hermaphrodites are shorter and less fertile than 2X hermaphrodites, and they produce many inviable zygotes among their self progeny: these are probably 4X zygotes. Haplo-X and diplo-X ova are produced in 2:1 ratio by 3X hermaphrodites. him mutations are expressed in these animals, increasing the frequency of self-progeny males and 2X hermaphrodites.
785 citations
501 citations
TL;DR: It is suggested that the Chymotrypsin barrel originally evolved from a closely-linked dimer of two intertwined half-domains which became united into one by gene duplication, consistent with the gene duplication hypothesis.
499 citations
TL;DR: Comparison of the human mitochrondrial DNA sequence of the cytochrome oxidase subunit II gene and the sequence of a corresponding beef heart protein shows that UGA is used as a tryptophan codon and not as a termination codon, and suggests that AU A may be a methionine and not an isoleucine codon.
Abstract: Comparison of the human mitochrondrial DNA sequence of the cytochrome oxidase subunit II gene and the sequence of the corresponding beef heart protein shows that UGA is used as a tryptophan codon and not as a termination codon and suggests that AU A may be a methionine and not an isoleucine codon. The cytochrome oxidase II gene is contiguous at its 5′ end with a tRNAAsp gene and there are only 25 bases at its 3′ end before a tRNALys gene. These tRNAs are different from all other known tRNA sequences.
497 citations
TL;DR: The fitting of sequenced peptides to a high-resolution X-ray map of phosphoglycerate kinase has yielded the complete sequence and structure of the horse muscle enzyme.
Abstract: The fitting of sequenced peptides to a high-resolution X-ray map of phosphoglycerate kinase has yielded the complete sequence and structure of the horse muscle enzyme. Metal ADP and ATP substrates are bound to one of the two widely separated domains in an environment that seems unsuitable for phosphoglycerate binding. The most plausible binding site for the phosphoglycerate substrate is on the other domain about 10 A from the ATP, which implies the possibility of a large scale hinge-bending of the domains to bring the two substrates together in a water-free environment for catalysis.
424 citations
TL;DR: The preparation and use of a new clone of a rat myeloma is described, suitable for the derivation of rat × rat hybrid myelomas producing specific rat antibodies.
Abstract: MONOCLONAL antibodies can be produced by cultures of permanent cell lines derived by fusion of suitable myelomas with spleen cells from immunised animals1. So far, mainly two mouse myelomas, X63-Ag8 and NSI/1-Ag4.1, have been used for this purpose1,2. When cells from immunised mice are used in the fusion, the mouse × mouse hybrid myelomas can be grown as tumours in appropriate mouse strains. We describe here the preparation and use of a new clone of a rat myeloma, which is suitable for the derivation of rat × rat hybrid myelomas producing specific rat antibodies. The spent medium of hybrid myeloma cultures usually contains 1–20 μg ml−1 antibody. The serum and ascites of the tumour-bearing mice, with few exceptions, yield 1–20 mg ml−1 of antibody, which is 1,000 times more concentrated and very convenient for larger preparations.
415 citations
TL;DR: The clathrin coat is a labile structure that can be solubilized by nondenaturing treatments, and baskets can be reformed from the extracted material.
404 citations
TL;DR: A uniform system of genetic nomenclature for the nematode Caenorhabditis elegans is described to designate genes, mutations and strains, and to attempt to avoid name duplications.
Abstract: A uniform system of genetic nomenclature for the nematode Caenorhabditis elegans is described. Convenient ways are specified to designate genes, mutations and strains, and to attempt to avoid name duplications.
368 citations
TL;DR: A rationale for this “alternating-B” structure is given which provides an explanation for the effects of chemical modifications of the T residues on the binding of the poly(dA-dT)· poly( dA- dT) to the lac repressor of Escherichia coli.
TL;DR: The histone pairs prepared by this method can regenerate chromatin-like characteristics when combined and reconstituted with DNA.
Abstract: A method to purify histone groups H2A+H2B and H3+H4 using dissociation with NaCl and hydroxylapatite chromatography is presented. The procedure is simple, involves mild solvents, and provides milligram quantities of histones of high purity. The histone pairs prepared by this method can regenerate chromatin-like characteristics when combined and reconstituted with DNA.
TL;DR: This technique is used to provide a correlation between DNA methylation and the activity of the chicken β-globin genes and it is shown that the overall content of 5-methylcytosine in DNA does not vary significantly between different tissues of the same organism.
Abstract: METHYLATION of cytosine is the only post-synthetic modification so far detected in the DNA of higher eukaryotes and thus has been made the basis of several proposed mechanisms of gene activity and cellular differentiation1–3. All evidence indicates, however, that the overall content of 5-methylcytosine in DNA does not vary significantly between different tissues of the same organism and does not change throughout at least some steps of differentiation4–6. As 5-methylcytosine occurs predominantly in the dinucleotide sequence CpG (ref. 7) and as a number of bacterial restriction endonucleases can distinguish whether this sequence is methylated or unmethylated, it is now possible to investigate DNA methylation patterns in the vicinity of single genes8. In this report, we use this technique to provide a correlation between DNA methylation and the activity of the chicken β-globin genes.
TL;DR: The unfolding of several proteins by urea has been followed by electrophoresis of a band of protein through a slab gel of polyacrylamide in which there was a gradient of urea concentration perpendicular to the direction of electrophoreis to confirm the validity of the method.
TL;DR: The possibility that amines and ammonia would block the clustering of α2M and EGF is examined, and it is reported here that these agents are effective in blocking clustering and internalisation.
Abstract: α2-MACROGLOBULIN (α2M), insulin and epidermal growth factor (EGF) have a common mechanism for internalisation1. We have proposed a model for this mechanism1–3 in which the ligands bind to diffusely distributed receptors followed by the collection of the mobile ligand–receptor complexes over coated pits. These coated pits pinch off from the plasma membrane to form endocytic vesicles. The diffuse initial distribution of the α2M receptors has been shown by binding α2M to fixed cells and observing the location of α2M by an electron microscopic immunocytochemical method2. The mobility of the ligand–receptor complexes has been demonstrated using fluorescence photobleaching recovery4, and the clustering of such complexes has been demonstrated by fluorescence microscopy1,3,5. Electron microscopic immunocytochemical localisation has been used to show that the clustering occurs over coated pits which pinch off to form endocytic vesicles2. The mechanism proposed for the endocytosis of α2M, insulin and EGF is similar to that described for the internalisation of low density lipoprotein (LDL), except that unoccupied LDL receptors may cluster in coated pits before binding LDL6. It seems likely that many molecules, including other polypeptide hormones and the lysosomal hydrolases7 which bind to specific receptors on the cell surface, are internalised by a similar mechanism. To determine the role of clustering and internalisation in hormone action it would be useful to have an agent that inhibits these processes. It has been found that the internalisation of lysosomal enzymes is noncompetitively inhibited by some amines and ammonia (E. Neufeld, personal communication). It has also been reported that ammonia prevents the internalisation of diptheria toxin by HeLa cells8. In view of these effects, we examined the possibility that amines and ammonia would block the clustering of α2M and EGF, and we report here that these agents are effective in blocking clustering and internalisation.
TL;DR: It is shown that M13 single-stranded DNA pure enough to be used as a template for sequence determination can be prepared by simple centrifugation of the phage particle and extraction with phenol.
TL;DR: The overall structure matches that of cytochrome oxidase seen in the p22 1 2 1 crystals derived by Triton X100 treatment of mitochondria.
TL;DR: The results appear to rule out fixed cell lineage as a determinative mechanism in ommatidial development.
TL;DR: The allosteric enzyme phosphofructokinase binds its substrate fructose-6-phosphate between two subunits of the tetramer, and allosteri effectors between another pair of subunits, creating ligand bridges between subunits.
Abstract: The allosteric enzyme phosphofructokinase binds its substrate fructose-6-phosphate between two subunits of the tetramer, and allosteric effectors between another pair of subunits. The effector binding site accommodates both the activator and the inhibitor. The substrate cooperativity and allosteric control are mediated by these ligand bridges between subunits.
TL;DR: It is concluded from these results that high levels of fibronectin stimulate events which reduce fusion, whereas the removal of surface fibronECTin during critical times either stimulates or reduces fusion.
TL;DR: The ultrastructure of mitosis was studied in polarized, well-differentiated thyroid epithelial cells in vivo following stimulation with the goitrogen, thiouracil, and attention was focused on changes occurring in cytoplasmic organelles.
TL;DR: It is suggested that decreased fibronectin levels may be required for chondrogenesis to occur normally, and treatment with fibronECTin caused the chondrocytes to assume a fibroblastic morphology and also enhanced other fibroBlastic properties.
TL;DR: It is demonstrated that the partial reduction of a guanine nucleotide, probably relative to some other compound, suffices to initiate sporulation and may always play a decisive role in the initiation of sporulation.
TL;DR: Observations with ribonuclease are qualitatively similar to those made previously in greater detail with pancreatic trypsin inhibitor and suggest a possible general pattern for the kinetic process of protein unfolding and refolding.
TL;DR: The purification of three chymotryptic fragments with apparent molecular weights of 40,000, 160,000 and 205,000 from chicken cellular fibronectin support the idea that the fibronECTin molecule consists of separate structural domains containing different biological characteristics.
TL;DR: Simian virus 40 mutants and deletions between 0.54 and 0.59 map units direct the synthesis of defective 20K t antigens, which transformed actively growing CHL cells nearly as efficently as did wild-type virus, in either the focus formation assay or the growth in soft agar assay.
TL;DR: The average lengths obtained are muliples of about 10.4 bases, significantly different from the value of 10 previously reported, which indicates periodicity in fragment lengths is closely related to the periodicity of the DNA double helix in chromatin.
Abstract: Two methods have been used to measure the single-strand lengths of the DNA fragments produced by deoxyribonuclease I digestion of chromatin. The average lengths obtained are muliples of about 10.4 bases, significantly different from the value of 10 previously reported. This periodicity in fragment lengths is closely related to the periodicity of the DNA double helix in chromatin, but the two values need not be exactly the same.
TL;DR: Experiments are described showing that the heavy chain of HTA1 is associated with a ‘β2m-like’ subunit which is different from β2m both in its mobility in SDS polyacrylamide gel electrophoresis (PAGE) and in its immunological properties.
Abstract: A STRIKING structural feature of several cell surface molecules in warm-blooded vertebrates is the non-covalent association of polypeptide chains (molecular weight (MW) 40–45,000) bearing alloantigenic determinants, with another molecule, β2-microglobulin (β2m) (MW 11–12,000)1–4. A role for β2m has not been established, but a whole family of cell surface proteins with overall structural similarity to major transplantation antigens have β2m as a common invariant subunit. The identification of β2m in these proteins has relied mainly on its characteristically low MW and on the use of heterologous antisera. Human thymus antigen (HTA 1) is a surface antigen found on human thymocytes and certain thymomas like MOLT-4. It has been identified by the monoclonal antibody from hybrid myeloma NA1/34 and has been suggested to represent the human homologue of the murine TL antigen5. We describe here experiments showing that the heavy chain of HTA1 is associated with a ‘β2m-like’ subunit which is different from β2m both in its mobility in SDS polyacrylamide gel electrophoresis (PAGE) and in its immunological properties.
TL;DR: A clonal analysis of wild-type and aristapedia eye-antenna discs has shown that both discs are subdivided into anterior and posterior compartments, however, the spatial order of the anterior and anterior compartments is reversed in the adult, so that the posterior compartment is at the extreme anterior tip of the fly.