One of the obstacles encountered when extracting DNA from a large number of samples is the cumbersome method of deproteinizing cell digests with the hazardous organic solvents phenol and isochloroform. Several other non-toxic extraction procedures have been published, but require either extensive dialysis (1) or the use of filters (2). A rapid, safe and inexpensive method was developed to simplify the deproteinization procedure. This method involves salting out of the cellular proteins by dehydration and precipitation with a saturated NaCl solution.Buffy coats of nucleated cells obtained from anticoagulated blood (ACD or EDTA) were resuspended in 15 ml polypropylene centrifugation tubes with 3 ml of nuclei lysis buffer (10 mM Tris-HCl, 400 mM NaCl and 2 mM Na2EDTA, pH 8.2). The cell lysates were digested overnight at 37°C with 0.2 ml of 10% SDS and 0.5 ml of a protease K solution (1 mg protease K in 1% SDS and 2 mM Na2EDTA). After digestion was complete, 1 ml of saturated NaCl (approximately 6M) was added to each tube and shaken vigorously for 15 seconds, followed by centrifugation at 2500 rpm for 15 minutes. The precipitated protein pellet was left at the bottom of the tube and the supernatant containing the DNA was transferred to another 15 ml polypropylene tube. Exactly 2 volumes of room temperature absolute ethanol was added and the tubes inverted several times until the DNA precipitated. The precipitated DNA strands were removed with a plastic spatula or pipette and transferred to a 1.5 ml microcentrifuge tube containing 100-200 pl TE buffer (10 mM Tris-HCl, 0.2 mM Na2EDTA, pH 7.5). The DNA was allowed to dissolve 2 hours at 37°C before quantitating.The DNA obtained from this simple technique yielded quantities comparable to those obtained from phenol-chloroform extractions. The 260/280 ratios were consistently 1.8-2.0, demonstrating good deproteinization. Restrictions were performed using a number of different enzymes requiring high, medium or low salt concentrations, all resulting in complete restriction. This procedure has been used in our laboratory on several thousand blood samples for parentage, population and forensic studies. This technique is used with our nonisotopic hybridization procedures (3) rendering the entire process of RFLP analysis free of toxic materials.

A white population from the State of Minnesota of primarily German and Scandinavian heritage was subtyped for α₁-antitrypsin variants using isoelectric focusing. The frequencies of the genes PPM1 (0.724), PI*M2 (0.137) and PI*M3 (0.095) were consistent with those for white populations documented in the literature from Northern Europe. Other genes identified in the study were PI*F, PPI, PPP, PPS and PPZ.

Genetic data consisting of 14 red cell antigen groups and 11 serum and erythrocytic protein marker systems from four Eskimo populations of the Norton Sound area of Alaska are reported. The population structure of these four groups in analyzed both separately and within the larger context by comparison to 15 other circumpolar groups. These analyses reveal a good fit between genetic structure, geographic distribution, linguistic affiliation, and the ethnohistory of the region.

In this paper we examine the effects of ethnicity on the gene flow between two groups living in Limón, Costa Rica. Our main interest is to determine if ethnicity has acted as a barrier to the exchange of genes, and if the groups have remained distinct genetically. We report the admixture estimates, F(st) values, and inbreeding coefficients of the two samples. The data consist of blood samples and surnames obtained from 375 individuals. The subjects' two surnames were analyzed to determine the ethnicity of their parents (individuals carry their father's and mother's first surnames). We used the formula of Crow and Mange ([1965] Eugen Q 12:199-203) to compute F(t), F(n), and F(r) with the surnames. Admixture estimates were computed for both groups using the computer program ADMIX.PAS kindly provided by Jeffrey Long. The estimates for the Hispanic-Limonense group are M1 = 0.5866 European, M2 = 0.3383 Amerindian, and M3 = 0.0751 African ancestry. For the Afro-Limonense group, the admixture estimates indicate M1 = 0.1047 European, M2 = 0.1357 Amerindian, and M3 = 0.7595 African ancestry. The F(st) values are F(st) = 0.00558 for the Hispanic group and F(st) = 0.05137 for the Afro-Limonense group. These F(st) values indicate that the Afro-Limonense group has experienced more genetic drift than has the other group, possibly as a result of its long history of isolation in Costa Rica. Indeed, when plotted along a scaled eigenvector R matrix of Caribbean gene frequencies, the two Limonense groups did not cluster with each other. Thus we conclude that the two ethnic groups have remained distinct breeding populations.

This study is one portion of a research program on: (1) the genetic effects of transplantation of Mexican Indian populations into diverse environments; (2) the effect of Spanish colonization on the genetics of Mexico. In 1591, 91 Tlaxcaltecan families were transplanted into northern Mexico to aid in the pacification of the Chichimec Indians. The descendants of these migrants are the residents of the City of Saltillo in the state of Coahuila. Since Saltillo had undergone considerable growth due to industrialization, two adjoining barrios-Chamizal and La Minita-were chosen for this study. Chamizal is an old established barrio where the descendants of the Tlaxcaltecan colonialists resided, while La Minita is a small shantytown made up of squatters from the surrounding areas.Blood specimens were collected by venipuncture from 302 participants and analyzed for 16 blood groups, 13 serum protein and red blood cell enzyme systems. The gene frequency distribution suggests that the Saltillo populations are a triracial hybrid made up of Indian, African and Spanish parental contributions. Admixture estimates and genetic distance measures are both in agreement with the ethnohistory of the transplanted Tlaxcaltecan community.