No abstract

We report an effort to determine the basis for the altered migration of seven inherited albumin variants detected by one-dimensional electrophoresis in population surveys involving tribal Amerindians and Japanese children. An amino acid substitution has thus far been determined for four of the variants. The randomness in the albumin polypeptide of these and the other sixteen independently ascertained amino acid substitutions of albumin and proalbumin thus far established was analyzed; the clustering of eight of these at two positions in the six-amino acid propeptide sequence seems noteworthy. By comparison with other proteins studied by electrophoresis, albumin exhibits "average" variability. It is a paradox that individuals who, for genetic reasons, lack albumin exhibit no obvious ill effects; yet, electrophoretic variants of albumin are no more numerous than are variants of proteins, the absence of which results in severe disease.

The hemagglutination inhibition antibody titers against the JC and BK polyoma viruses (JCV and BKV, respectively)

A total of 289,868 locus tests, based on 28 different protein phenotypes and using one-dimensional electrophoresis to detect variant proteins, has yielded one probable mutation in the offspring of "proximally exposed" parents, who received an estimated average gonadal exposure of 31 to 39 rem in the atomic bombings of Hiroshima and Nagak. There were no mutations in 208,196 locus tests involving children of "distally exposed" parents, who had essentially no radiation exposure. Studies of the genetic effects of atomic bombs have been in progress in Hiroshima and Nagasaki since 1946 (1-5). The first generation of studies was essentially morphological in nature. More recently, profiting from technological developments, studies have been undertaken at the cytogenetic (6, 7) and biochemical (8) levels. We present here a progress report on the results of the biochemical approach at approximately the midpoint of the study. No statistically significant difference between the children of exposed and control parents can be demonstrated at this time (nor was it expected at this juncture in the study). In addition to the timeliness of a progress report, however, the present publication is dictated by three other considerations. (i) The current intense interest in the genetic effects of low-level ionizing radiation has prompted a complete re-evaluation of 30 years of genetic studies on the effects of the atomic bombs; the present data can be integrated into that treatment. (fi) The control aspects of the data of this study can be combined with similar data from other studies to yield a direct estimate of the rate at which spontaneous mutation results in electrophoretic variants of proteins; this should be useful in planning the feasibility and magnitude of any other genetic studies of this type. (Wi) A wealth of data on biochemical variants in Japanese has accumulated during the past 7 years; this description should clear the way for the presentation of this information.

The continuing efforts to evaluate specific human populations for altered germinal mutation rates would profit from more efficient and more specific approaches than those of the past. To this end, we have explored the potential usefulness oftwo-dimensional electrophoresis ofDNA fragments obtained from restriction-enzyme-digested genomic DNA. This permits the analysis, on a single preparation, of -2000 DNA fragments varying in size from 1.0 to 5.0 kb in the first dimension and from 0.3 to 2.0 kb in the second dimension. To enter into a genetic analysis, these fragments must exhibit positional and quantitative stability. With respect to the latter, if spots that are the product of two homologous DNA fragments are to be distnguished with the requisite accuracy from spots that are the product of only one fragment, the coefficient of variation of spot intensity should be approximately -0.12. At present, 482 of the spots in our preparations meet these standards. In an examination of preparations based on three Japanese mother/father/child trios, 43 of these 482 spots were found to exhibit variation that segregated within families according to Mendelian principles. We have established the feasibility of cloning a variant fragment from such gels and establishing its nucleotide sequence. This technology should be highly efficient in monitoring for mutations resulting in loss/pin/rearrangement events in DNA fragments distributed throughout the genome.Research conducted in recent years has revealed a staggering wealth of genetic variation in the DNA of humans and other animals. Better techniques for the rapid identification and genetic analysis of this variation and for determining the frequency of germinal and somatic mutation, including the alterations in DNA associated with oncogenesis, are highly desirable. The advent of two-dimensional separations of genomic DNA fragments may be an important advance in this context (1)(2)(3)(4)(5). In this communication employing the technique of end-labeled restriction landmarks, we will describe the implementation of an approach for the quantitative analysis of the human DNA fragments visualized in autoradiographs of sheet gels prepared using two-dimensional electrophoresis. Elsewhere, we describe the qualitative variation detected with this technology (R.K., J.A., J.V.N., C.S., and S.M.H., unpublished data). Here, we emphasize the ability to distinguish between the autoradiographic intensity of a spot that is the product of two homologous DNA fragments as contrasted with the intensity of a fragment corresponding to one copy of the same DNA fragment. The ability to make this distinction with high accuracy provides the basis for employing this technique in the study of the frequency of mutation. Finally, we will consider the sources of nongenetic variation in spot density and discuss how the detection of genetic variation in gels of this type might be improved. MATERIALS AND METHODSDNA Samples. The DNA analyzed was obtained from three father/mother/one-child family constellat...