The distribution of interspersed repetitive DNA sequences in the human genome.

The distribution of interspersed repetitive DNA sequences in the human genome has been investigated, using a combination of biochemical, cytological, computational, and recombinant DNA approaches. "Low-resolution" biochemical experiments indicate that the general distribution of repetitive sequences in human DNA can be adequately described by models that assume a random spacing, with an average distance of 3 kb. A detailed "high-resolution" map of the repetitive sequence organization along 400 kb of cloned human DNA, including 150 kb of DNA fragments isolated for this study, is consistent with this general distribution pattern.

The GenBank genetic sequence databank.

The GenBank Genetic Sequence Data Bank contains over 5700 entries for DNA and RNA sequences that have been reported since 1967. This paper briefly describes the contents of the database, the forms in which the database is distributed, and the services we offer to scientists who use the GenBank database.

The GenBank nucleic acid sequence database.

The GenBank nucleic acid sequence database is a computer-based collection of all published DNA and RNA sequences; it contains over five million bases in close to six thousand sequence entries drawn from four thousand five hundred published articles. Each sequence is accompanied by relevant biological annotation. The database is available either on magnetic tape, on floppy diskettes, on-line or in hardcopy form.

A relational database system for the maintenance and verification of the Los Alamos sequence library.

The nucleic acid sequence databases of Los Alamos National Laboratory, European Molecular Biology Laboratory, and others are organized in a single relational database. This organization with a suitable relational database management program facilitates the tasks of reporting statistics, making cross-references, and double-checking of the original databases.

Short communication: skeletal maturation of children with sex chromosome abnormalities.

Skeletal maturity, or "bone age," is one of the several criteria used to determine developmental or physiologic age as opposed to chronologic age. The purpose of this study of skeletal maturation of children with sex chromosome abnormalities (45,X, 47,XXX, 47,XXY, X-chromosomal mosaics) and controls is 2c-fold: (1) to investigate if children with sex chromosome aneuploidy ascertained in an unbiased fashion differ in skeletal maturation from their siblings and other normal healthy children born in Denver, Colorado, and (2) to assess if the skeletal age standards currently in use (Greulich-Pyle; Tanner- Whitehouse) are applicable to Denver children when evaluating radiographs for skeletal maturation. Mean chronologic and skeletal age were measured.

Pattern recognition in nucleic acid sequences. I. A general method for finding local homologies and symmetries.

We present an algorithm--a generalization of the Needleman-Wunsch-Sellers algorithm--which finds within longer sequences all subsequences that resemble one another locally. The probability that so close a resemblance would occur by chance alone is calculated and used to classify these local homologies according to statistical significance. Repeats and inverted repeats may also be found.

Pattern recognition in nucleic acid sequences. II. An efficient method for finding locally stable secondary structures.

We present a method for calculating all possible single hairpin loop secondary structures in a nucleic acid sequence by the order of N2 operations where N is the total number of bases. Each structure may contain any number of bulges and internal loops. Most natural sequences are found to be indistinguishable from random sequences in the potential of forming secondary structures, which is defined by the frequency of possible secondary structures calculated by the method.

Synthesis and pharmacological activity of thiohexital enantiomers.

(S)-(+)- and (R)-(-)-5-Allyl-5-(1-methyl-2-pentynyl)-2-thiobarbituric acid (1, thiohexital) were prepared. The anesthetic activity (loss of righting reflex) and acute toxicity of the optically pure enantiomers of 1 were compared to the racemic isomer in mice. The S(+) isomer was found to be more potent as an anesthetic agent than the R(-) or RS(+/-) isomers.

Motion of polymorphonuclear leukocytes: theory of receptor redistribution and the frictional force on a moving cell.

As a cell moves over a surface, the distribution of membrane proteins that adhere to the surface will be changed relative to the distribution of these molecules on a static cell. Observations of this redistribution offer, in principle, evidence as to the mechanisms of membrane dynamics during cell locomotion. Toward extracting such information we present and analyze a mathematical model of receptor transport in the membrane by diffusion and convection, as affected by the making and breaking of the bonds between the receptors and the surface as the cell moves.

Degradation of nucleic acid in aqueous solution by ionizing radiation. III. The correlation of radiation damage with change in melting transition--model experiments.

The melting behavior of polydeoxynucleotide double helices of known structure is analyzed in terms of the thermodynamics of helix stability, taking into account separately those contributions to the transition free energy that are proportional to the numbers of polymer molecules and those that are proportional to the numbers of base pairs formed. From the analysis of the melting transitions of helices having an alternating (d-)A.T, G.

Incidence of aneuploidy in a human population.

A population of 40,371 individuals consisting of every baby delivered at two Denver hospitals from 1964 to 1974 has been screened from aneuploidy of the sex chromosomes and chromosome 21. The pattern in time with which aneuploidy occurs suggests an epidemic component of the incidence superimposed on an approximately equal constant frequency. The epidemic incidence is most likely to be high for births from May to October, to persist for several consecutive years, and then to be absent for several consecutive years.

Bimodal sedimenting zones due to ligand-mediated interactions.

Ligand-mediated association-dissociation reactions can give rise to band sedimentation patterns showing bimodal bands despite instantaneous establishment of equilibrium. Weaker interactions result in unimodal bands whose sedimentation coefficients decrease with time of sedimentation and in characteristic patterns of total ligand. The implications of these results for fundamental investigations of protein interactions and for conventional analytical applications of zone sedimentation and molecular sieve chromatography are considered.