Showing papers by "Laboratory of Molecular Biology published in 1986"
TL;DR: The structure and connectivity of the nervous system of the nematode Caenorhabditis elegans has been deduced from reconstructions of electron micrographs of serial sections as discussed by the authors.
Abstract: The structure and connectivity of the nervous system of the nematode Caenorhabditis elegans has been deduced from reconstructions of electron micrographs of serial sections. The hermaphrodite nervous system has a total complement of 302 neurons, which are arranged in an essentially invariant structure. Neurons with similar morphologies and connectivities have been grouped together into classes; there are 118 such classes. Neurons have simple morphologies with few, if any, branches. Processes from neurons run in defined positions within bundles of parallel processes, synaptic connections being made en passant. Process bundles are arranged longitudinally and circumferentially and are often adjacent to ridges of hypodermis. Neurons are generally highly locally connected, making synaptic connections with many of their neighbours. Muscle cells have arms that run out to process bundles containing motoneuron axons. Here they receive their synaptic input in defined regions along the surface of the bundles, where motoneuron axons reside. Most of the morphologically identifiable synaptic connections in a typical animal are described. These consist of about 5000 chemical synapses, 2000 neuromuscular junctions and 600 gap junctions.
5,491 citations
TL;DR: This work substituted the CDRs from the heavy-chain variable region of mouse antibody B1–8, which binds the hapten NP-cap, for the corresponding CDRs of a human myeloma protein, to determine whether the antigen-binding site could be transplanted from one framework to another by grafting theCDRs.
Abstract: The variable domains of an antibody consist of a beta-sheet framework with hypervariable regions (or complementarity-determining regions--CDRs) which fashion the antigen-binding site. Here we attempted to determine whether the antigen-binding site could be transplanted from one framework to another by grafting the CDRs. We substituted the CDRs from the heavy-chain variable region of mouse antibody B1-8, which binds the hapten NP-cap (4-hydroxy-3-nitrophenacetyl caproic acid; KNP-cap = 1.2 microM), for the corresponding CDRs of a human myeloma protein. We report that in combination with the B1-8 mouse light chain, the new antibody has acquired the hapten affinity of the B1-8 antibody (KNP-cap = 1.9 microM). Such 'CDR replacement' may offer a means of constructing human monoclonal antibodies from the corresponding mouse monoclonal antibodies.
2,685 citations
TL;DR: Results are consistent with a function for P-glycoprotein as an energy-dependent efflux pump responsible for decreased drug accumulation in multidrug-resistant cells.
1,914 citations
1,491 citations
TL;DR: A cDNA clone is characterized that encodes a protein related to the 70 kd heat shock protein, but is expressed in normal rat liver, and it is identical with two previously described proteins: GRP78, whose synthesis is induced by glucose starvation, and BiP, which is found bound to immunoglobulin heavy chains in pre-B cells.
1,401 citations
TL;DR: The rotational positioning of DNA about the histone octamer appears to be determined by certain sequence-dependent modulations of DNA structure, and it is observed that long runs of homopolymer (dA) X (dT) prefer to occupy the ends of core DNA, five to six turns away from the dyad.
899 citations
TL;DR: Eight classes of chemosensory neurons in C. elegans fill with fluorescein when living animals are placed in a dye solution, suggesting that dye contact is the principal factor under selection.
884 citations
TL;DR: A DNA-binding gel electrophoresis assay was used to detect a protein(s) in HeLa cell nuclear extracts that specifically binds to the 5' activating element.
764 citations
TL;DR: A classification of amino acid type is described which is based on a synthesis of physico-chemical and mutation data in the form of a Venn diagram from which sub-sets are derived that include groups of amino acids likely to be conserved for similar structural reasons.
725 citations
TL;DR: In this article, the strength of the very weak high-resolution Fourier components of the image of a two-dimensional crystal was determined using real space correlation analysis, and the amplitude and phase information was extracted from the distortion-corrected image of the crystal.
694 citations
TL;DR: Inhibition by GRGDS was dose-dependent, noncytotoxic, and did not result from an impairment of cellular tumorigenicity, and may function by inhibiting tumor cell retention in the lung since radiolabeled B16-F10 tumor cells injected with the peptide were lost at a substantially greater rate than control cells.
Abstract: Adhesive interactions between cells and the extracellular matrix occur at several stages of metastasis. Such interactions might be inhibited by synthetic peptide probes derived from the cell-binding regions of matrix molecules. Gly-Arg-Gly-Asp-Ser (GRGDS) is a pentapeptide sequence that appears to be critical for cell interaction with fibronectin. Coinjection of GRGDS with B16-F10 murine melanoma cells dramatically inhibited the formation of lung colonies in C57BL/6 mice. Two closely related control peptides, in which specific amino acids within the GRGDS sequence were transposed or substituted, displayed little or no activity. Inhibition by GRGDS was dose-dependent, noncytotoxic, and did not result from an impairment of cellular tumorigenicity. GRGDS may function by inhibiting tumor cell retention in the lung since radiolabeled B16-F10 tumor cells injected with the peptide were lost at a substantially greater rate than control cells.
TL;DR: A technique for digital characterization and comparison of DNA fragments, using restriction enzymes, is described, being applied to fragments from the nematode Caenorhabditis elegans to facilitate cross-indexing of clones emanating from different laboratories and to construct a physical map of the genome.
Abstract: A technique for digital characterization and comparison of DNA fragments, using restriction enzymes, is described. The technique is being applied to fragments from the nematode Caenorhabditis elegans (i) to facilitate cross-indexing of clones emanating from different laboratories and (ii) to construct a physical map of the genome. Eight hundred sixty clusters of clones, from 35 to 350 kilobases long and totaling about 60% of the genome, have been characterized.
TL;DR: Results suggest that increased expression of mdr1 mRNA is a common mechanism for multidrug resistance in human cells and that Activation of the m dr1 gene by mutations or epigenetic changes may precede its amplification during the development of resistance.
Abstract: The development of simultaneous resistance to multiple structurally unrelated drugs is a major impediment to cancer chemotherapy. Multidrug resistance in human KB carcinoma cells selected in colchicine, vinblastine, or Adriamycin is associated with amplification of specific DNA sequences (the multidrug resistance locus, mdr1). During colchicine selection resistance is initially accompanied by elevated expression of a 4.5-kilobase mdr1 messenger RNA (mRNA) without amplification of the corresponding genomic sequences. During selection for increased levels of resistance, expression of this mRNA is increased simultaneously with amplification of mdr1 DNA. Increased expression and amplification of mdr1 sequences were also found in multidrug-resistant sublines of human leukemia and ovarian carcinoma cells. These results suggest that increased expression of mdr1 mRNA is a common mechanism for multidrug resistance in human cells. Activation of the mdr1 gene by mutations or epigenetic changes may precede its amplification during the development of resistance.
TL;DR: It is shown that human KB carcinoma cells which express the mdr1 gene also express P-glycoprotein, and that cDNAs encoding P- glycoprotein cross-hybridize with m dr1 cDN as, Thus, the mDr1 gene codes for P- Glycoprotein.
TL;DR: A technique for introducing exogenous DNA into the chromosomes of the nematode Caenorhabditis elegans and a chimeric gene containing a Drosophila heat shock promoter element fused to coding sequences from the Escherichia coli β‐galactosidase gene functions and is heat inducible in the resulting stably transformed lines.
Abstract: A technique for introducing exogenous DNA into the chromosomes of the nematode Caenorhabditis elegans is presented. A cloned C. elegans amber suppressor tRNA gene, sup-7, is used as a selectable marker. The activity of this amber suppressor is selected for by injecting worms which carry an amber termination mutation in a gene (tra-3) whose function is required for fertility. Transient expression of sup-7 is evidenced by the presence of fertile (rescued) animals in the generation after injection. In a fraction of cases, these fertile animals give rise to stable suppressor lines (eight have been characterized so far). Each of the stable suppressor lines carries injected DNA sequences. The suppressor activities have been mapped to chromosomal loci, indicating that the exogenous DNA has integrated into the genome. This technique has been used to introduce a chimeric gene containing a Drosophila heat shock promoter element fused to coding sequences from the Escherichia coli beta-galactosidase gene. This chimeric gene functions and is heat inducible in the resulting stably transformed lines.
TL;DR: Evidence is provided that the elongation of the body is caused by the outermost layer of embryonic cells, the hypodermis, squeezing the embryo circumferentially and that an extracellular cuticle appears to maintain the body shape after elongation.
TL;DR: The conflicting findings on tetanus and botulinum toxins binding to neuronal membranes are reviewed and discussed in terms of a double receptor formed by both a G 1b ganglioside and a protein component.
TL;DR: It is proposed that the synthesis of uPA and uPA receptor by the same cell may provide a pathway for the activation of the metastatic potential of malignant cells.
TL;DR: The eve gene resembles other pair-rule genes in showing a transient seven stripe zebra pattern during the blastoderm stage, but seven additional stripes arise soon thereafter, which are required for the activation of coincident stripes of engrailed transcripts, leading to the subdivision of the embryo into compartmental and segmental units.
TL;DR: It turns out that the 26-kDa protein gene and the so-called 'IFN-beta 2' gene are identical, however, extensive homology searches indicate that the 25-k da protein does not show statistically significant sequence homology with any known interferon species.
Abstract: When human fibroblast cells were stimulated with poly(I) X poly(C) in the presence of cycloheximide for the production of interferon-beta (IFN-beta), a 26-kDa protein could be immunoprecipitated by antiserum raised against partially purified human IFN-beta [Content, J., De Wit, L., Pierard, D., Derynck, R., De Clercq, E. & Fiers, W. (1982) Proc. Natl Acad. Sci. USA 79, 2768-2772]. In our hands this 26-kDa protein showed no antiviral activity. Other investigators have, however, reported the presence in the same conditions of a second type of IFN, a so-called beta 2 species [Weissenbach, J., Chernajovsky, Y., Zeevi, M., Shulman, L., Soreq, H., Nir, U., Wallach, D., Perricaudet, M., Tiollais, P. & Revel, M. (1980) Proc. Natl Acad. Sci. USA 77, 7152-7156] of which the mRNA structure and protein characteristics strongly suggests identity with the 26-kDa product. In this paper we describe the nucleotide sequence of the 26-kDa cDNA and part of the corresponding genomic clone. The cDNA clones were isolated from a library made with mRNA from induced human fibroblasts. As, however, the information thus obtained was still incomplete, genomic clones were isolated from a total human DNA library. In this way, the entire region coding for the 26-kDa protein was established, as well as the neighbouring sequences including the inducible promoter area. From the deduced polypeptide sequence a number of characteristics of the 26-kDa protein can be explained. It turns out that the 26-kDa protein gene and the so-called 'IFN-beta 2' gene are identical. However, extensive homology searches indicate that the 26-kDa protein does not show statistically significant sequence homology with any known interferon species. Hence, the question of whether the 26-kDa product represents a novel IFN species remains open.
TL;DR: The whole package of sequence analysis software contains a comprehensive suite of programs for managing large shotgun sequencing projects, a program containing 61 functions for analysing single sequences and a program for comparing pairs of sequences for similarity.
Abstract: I describe the current status of our sequence analysis software. The package contains a comprehensive suite of programs for managing large shotgun sequencing projects, a program containing 61 functions for analysing single sequences and a program for comparing pairs of sequences for similarity. The programs that have been described before have been improved by the addition of new functions and by being made very much easier to use. The major interactive programs have 125 pages of online help available from within them. Several new programs are described including screen editing of aligned gel readings for shotgun sequencing projects; a method to highlight errors in aligned gel readings, new methods for searching for putative signals in sequences. We use the programs on a VAX computer but the whole package has been rewritten to make it easy to transport it to other machines. I believe the programs will now run on any machine with a FORTRAN77 compiler and sufficient memory. We are currently putting the programs onto an IBM PC XT/AT and another micro running under UNIX.
TL;DR: In the rat, high levels of NGF mRNA were found in cerebral cortex, hippocampus and thalamus/hypothalamus, medium levels in striatum and brainstem, and low levels in cerebellum and spinal cord as discussed by the authors.
TL;DR: Nine T cell gamma variable (V) gene segments isolated from human DNA show that major rearrangements can be observed that are attributable to the five active V gamma genes, and human cells with the phenotype of helper T cells can undergo productive V gamma-J gamma joining.
TL;DR: The isolation of complementary DNA (cDNA) clones encoding a CD1 antigen reveal a novel family of genes which are MHC-related but are neither equivalent to mouse TL antigens nor linked to the MHC.
Abstract: Thymocyte antigens CD1 [Thy,gp45,12] are thought to be the human counterparts of mouse thymus leukaemia (TL) antigens1,2. Serological and biochemical analyses indicate that at least three subsets exist3–6, the first of which (HTA 1/T6) was initially identified by the monoclonal antibody NA1/34 (refs 7,8). Like TL, CD1 are expressed on cortical thymocytes as well as on some lymphoid neoplasias, and resemble in structure major histocompatabiliry complex (MHC) class I antigens. However HTA 1/T6 is loosely associated with β2-microglobulin9–10 and is also found linked by a disulphide bridge to CD8 (T8)11,12. A molecular genetic approach is needed to investigate the CD1 system, to clarify its relationship to TL antigens and to understand its regulation. We report the isolation of complementary DNA (cDNA) clones encoding a CD1 antigen. These clones reveal a novel family of genes which are MHC-related but are neither equivalent to mouse TL antigens nor linked to the MHC.
TL;DR: A pattern-matching procedure is described, based on fitting templates to the sequence, which allows general structural constraints to be imposed on the patterns identified, which demonstrated the specificity of the templates was demonstrated by their ability to identify the conserved features in known immunoglobulin and immunoglOBulin-related sequences but not in other non-immunoglobulus sequences.
TL;DR: Using pure, recombinant human TNF, its cytotoxic action on several human transformed and non-transformed cell lines is reported and the observation that inhibition of protein synthesis by metabolic drugs remarkably enhances the sensitivity of several target cell lines to cytolysis by TNF is confirmed.
TL;DR: Tropomyosin movement, in response to calcium binding to troponin, is the first structural step in muscular contraction, and is the prerequisite for myosin binding.
TL;DR: The model that best explains the data is that during postembryonic development, posterior-specific patterns of cell differentiation and cell migration are initiated by graded positional information, and that a common step in the different cellular responses to this information is mediated by mab-5 activity.
TL;DR: This chapter discusses various lines of information bearing on the enzymatic mechanisms of topoisomerases, which are enzymes that catalyze changes in the topology of circular DNA.
Abstract: Publisher Summary Topoisomerases are a diverse and important group of enzymes. Although attention has until recently been focused on their ability to interconvert DNA topoisomers, this does not necessarily constitute the primary biological function for all of them. DNA topoisomerases are enzymes that catalyze changes in the topology of circular DNA. With a closed-circular double-stranded DNA, one type of reaction alters the number of times the two strands are wound around each other and thus changes the degree of supercoiling. Supercoiled DNA molecules are prevalent in cells, and enzymes that can modify this property are important in DNA metabolism. Reactions involving other topological isomers of DNA are also known; various topoisomerases can form or resolve knotted or catenated structures in circular duplex DNA, or form knots in single-stranded circular DNA. Some of these reactions also have biological importance; for instance, replication of a circular-duplex DNA often produces two catenated circles, which then have to be separated. Cells of all organisms examined to date have been found to contain DNA topoisomerases; commonly there are several distinct types in a cell. Where a genetic test has been feasible, the presence of at least one topoisomerase has been found to be essential for cell growth. This chapter discusses various lines of information bearing on the enzymatic mechanisms of topoisomerases.
TL;DR: Calcium-binding studies show that endoplasmin is a major calcium-binding protein in cells, suggesting that at least one of its roles might be in the calcium-storage function of the endoplasmic reticulum.
Abstract: The most abundant protein in microsomal membrane preparations from mammalian cells has been identified as a 100 X 10(3) Mr concanavalin A-binding glycoprotein. The glycosyl moiety of the glycoprotein is completely sensitive to endoglycosidase H, suggesting a predominantly endoplasmic reticulum localization in the cell. Using a monospecific antibody it was shown by binding and immunofluorescence studies that the glycoprotein is intracellular. Immunoelectron microscopy showed that the glycoprotein was at least 100 times more concentrated in the endoplasmic reticulum than in any other cellular organelle. It was found to be substantially overexpressed in cells and tissues rich in endoplasmic reticulum. Since it is the major common protein component associated with the endoplasmic reticulum we refer to it as endoplasmin. Calcium-binding studies show that endoplasmin is a major calcium-binding protein in cells, suggesting that at least one of its roles might be in the calcium-storage function of the endoplasmic reticulum. The amino-terminal sequence of endoplasmin is identical to that of a 100 X 10(3) Mr stress-related protein.