A potential DNA replication complex isolated from sea urchin embryos by renografin gradient centrifugation.

A complex containing deoxyribonucleic acid, protein and lipid has been isolated from the nuclei of the sea urchin Stronglocentrotus pupuratus by gentle lysis of nuclei and centrifugation of the lysate in a renografin gradient. The complex is similar in several respects to DNA-membrane complexes isolated by the sarkosyl M-band technique [1]. These include the following: 1, most of the cellular DNA is present in the complex but the bulk of the DNA may be removed by sonication or nuclease treatment; 2, nascent DNA is preferentially found in the complex; and 3, destruction of membrane/protein components removes DNA found in the complex.

Persistent cytoplasmic location of a DNA polymerase beta in sea urchins during development.

A subcellular localization study of a low molecular weight DNA polymerase beta indicates that this enzyme, as well as a high molecular weight DNA polymerase alpha, is found in large quantities in the cytoplasm of Strongylocentrotus purpuratus eggs. The two enzyme activities are distinguished by DEAE-sievorptive chromatography and by their differential activities with activated DNA and oligo(dT)10 . poly(dA)200 primer-templates.

Primary structure of a human IgA1 immunoglobulin. V. Amino acid sequence of a human IgA lambda light chain (Bur).

The sequence of the lambda light chain of the Bur IgA1 molecule has been determined. It comprises 214 amino acid residues with a blocked NH2 terminus and lacks carbohydrate. The V-region sequence is of the VlambdaII subgroup and contains the coupled interchanges Arg-7 and Cys-87.

A low molecular weight DNA polymerase beta in the sea urchin Strongylocentrotus purpurantus. Partial purification, properties, and changes in development.

A low molecular weight DNA polymerase which sediments at 3.3 S on sucrose gradients has been purified from total cell homogenates of rapidly dividing embryos of the sea urchin Strongylocentrotus purpuratus. In the presence of 2 mM N-ethylmaleimide, it is the major polymerase activity in whole cell homogenates when assayed with an oligo(dT)10.

Arsenic in the drinking water of the city of Antofagasta: epidemiological and clinical study before and after the installation of a treatment plant.

This is a second report of epidemiological and clinical investigation, related to the arsenic health problem, unique in the world, occurring in the city of Antofagasta, Chile. The arsenic problem originates in the chronic contamination of water supply in the city during 12 years. This phenomena, investigated clinically and epidemiologically and first reported in 1971, prompted the installation of a water treatment plant.

Cytoplasmic nonpolysomal ribonucleoprotein particles in sea urchin embryos and their relationship to protein synthesis.

We have examined the relationship between the newly synthesized mRNA that enters polysomes in sea urchin embryos and the messengerlike RNA that enters the pool of ribosome-free ribonucleoprotein particles (free RNPs or informosomes). Although the RNA in the free RNPs turns over 25% more rapidly than in the polysomes, labeling kinetics indicate that the RNA containing poly(A) [poly(A)(+)RNA] and the RNA not containing poly(A) [poly(A)(-)RNA] within each cytoplasmic compartment have very similar half-lives. The poly(A)(+)RNA from both free RNPs and polysomes binds ribosomes almost equally well in a reticulocyte lysate, and this binding is sensitive to inhibitors of initiation.

A nuclear membrane-associated DNA complex in cultured mammalian cells capable of synthesizing DNA in vitro.

A DNA-nuclear membrane complex has been isolated by two different methods from the nuclei of cultured mouse fibroblast (3T3) cells. One method, utilizing the detergent sarkosyl (sodium lauroyl sarkosinate), yields a DNA-nuclear membrane complex (the M band), which contains virtually all of the DNA in the nuclei. However, treatment of the M band by sonication, vortexing, or freeze-thaw reduces the amount of DNA in the complex by approximately 50-80%, depending upon the phase of the cell cycle from which the complex was extracted.

Complete covalent structure of a human IgA1 immunoglobulin.

The complete covalent structure has been determined for a human myeloma IgA1 immunoglobulin. This protein has unique features in the amino acid sequence and disulfide bridge structure of the variable (V) and constant (C) regions of both the alpha heavy and the lambda light chains, and in the number and loci of oligosaccharides. Whereas C region domains of heavy chains have evolved independently over eons, recent isotypic variations have occured in lambda light chains and possibly in alpha heavy chains.

Pressure-induced dissociation of sedimenting ribosomes: effect on sedimentation patterns.

Anomalous sedimentation patterns arise when free ribosomes from sea urchin eggs are centrifuged at high speeds. Pressure-induced dissociation of the ribosomes during sedimentation can explain the peculiar behavior; the assumption of such dissociation also yields estimates of the equilibrium constant (as a function of KCl concentration) and the change in molecular volume (500 +/- 100 ml/mol) in the reaction: subunits right arrow over left arrow ribosome. Such dissociation during centrifugation may explain many experiments in which apparent reduced sedimentation coefficients for ribosomes, and increased coefficients for the subunits, have been ascribed to conformational changes.