European populations display low genetic differentiation as the result of long-term blending of their ancient founding ancestries. However, it is unclear how the combination of ancient ancestries related to early foragers, Neolithic farmers, and Bronze Age nomadic pastoralists can explain the distribution of genetic variation across Europe. Populations in natural crossroads like the Italian peninsula are expected to recapitulate the continental diversity, but have been systematically understudied. Here, we characterize the ancestry profiles of Italian populations using a genome-wide dataset representative of modern and ancient samples from across Italy, Europe, and the rest of the world. Italian genomes capture several ancient signatures, including a non–steppe contribution derived ultimately from the Caucasus. Differences in ancestry composition, as the result of migration and admixture, have generated in Italy the largest degree of population structure detected so far in the continent, as well as shaping the amount of Neanderthal DNA in modern-day populations.

The replacement of fetal by adult hemoglobin after birth is not complete, since small amounts of fetal hemoglobin are consistently present in the blood of normal adults (6-9). It is, therefore, of interest to learn how continued synthesis of fetal hemoglobin in the adult is regulated and whether it can be further stimulated. We examined this in vitro, with a bone marrow culture system which permits selective proliferation of erythroid cells (10). We report here data which suggest appearance of increased and clonal synthesis of fetal hemoglobin in the adult erythroid cells, in vitro. METHODS Bone Marrow Cultures. Bone marrow aspirates from healthy volunteers without a hemoglobinopathy and from a patient homozygous for hemoglobin S were used; on a few occasions ribs surgically removed from patients were the source of marrow cells. Cells were washed in medium (Microbiological Associates, Bethesda, Md.) containing 2% (vol/vol) fetal calf serum, penicillin (50 units/ml) and streptomycin (50 ,gg/ml); the buffy coat layers were removed, and resuspended in fresh media. Antibodies and Immunofluorescent Labeling. Antibodies against hemoglobin F (anti-Hb F) or A (anti-Hb A) were raised in rabbits (anti-Hb F) or horses (anti-Hb A) and purified by affinity chromatography. The purification procedure, the conjugation with fluorescein isothiocyanate (FITC), and evidence of specificity of the anti-Hb F antibodies have been described (9). Peripheral blood smears were fixed and labeled with anti-Hb F antibodies conjugated with FITC (anti-Hb F-FITC), as previously described (9); smears prepared from bone marrow cell suspensions were treated similarly. Flattened plasma clots were fixed for 12 min in an acetone-methanol (9:1 vol/vol) solution, rinsed for 2 min in phosphate-buffered saline at pH 7.0 (9), rinsed in distilled water for another 2 min, and dried. They were labeled with anti-Hb F-FITC in the same fashion as the smears, except that the whole area of the clot was covered with the fluorescent antibody. After incubation for 1 hr in a humidified chamber at 370, the slides with clots were rinsed in phosphate-buffered saline, then in water, and then dried. They were mounted with clear serum, and viewed in the fluorescent microscope (Zeiss, Universal fluorescence microscope with reflected light excitation) under 150-times magnification. Freshly thawed antibody solutions were used for each experiment and conditions of fixation, staining, and viewing were kept constant. Evaluation of fluorescent labeling was best when plasma clots contained fewer erythroid colonies: cultures inoculated with 5 X 104 nucleated cells per clot were optimal. The reaction of the fixed plasma clots with the fluorescent antihemoglobin antibodies preserved the morphological characteristics of the cells and permitted identification and quantitative estimates of total erythroid colonies under fluorescent light. Erythroid cells and colonies were classified into categories according to intensity of fluorescent labeling. Fluorescence of moderate to bright intens...

Arabinosylcytosine, a compound that inhibits DNA synthesis in rapidly dividing cells, stimulates fetal hemoglobin in adult baboons and produces significant perturbations in the pools of erythroid progenitors. It appears that changes in the kinetics of erythroid cell differentiation rather than direct action on the gamma genes underlie stimulation of fetal hemoglobin in the adult animals in vivo. These results also suggest that chemotherapeutic agents selected for their low carcinogenic or mutagenic potential could be used for therapeutic induction of fetal hemoglobin in patients with sickle cell anemia.

Specific antibodies to human fetal hemoglobin were prepared and, after conjugation with a fluorescent dye, were used to determine the distribution of Hb F-containing cells in blood smears from normal adults and individuals with hereditary and acquired conditions associated with abnormal levels of Hb F. The mean proportion of F-cells in normal persons was 2.7% +/- 1.4%, with a range of 0.5%-7.0%. Proportions of F-cells were increased in persons with several acquired and inherited disorders that are associated with an increased percentage of Hb F in hemolysates. A strong linear correlation between the amount of Hb F and proportion of F-cells was observed. This technique may prove useful in studies of a variety of disorders associated with Hb F elevations and also in investigations of the mechanisms controlling the transition from fetal to adult hemoglobin during the course of human development.

Sickle cell disease is a hereditary disorder characterized by erythrocyte deformity due to hemoglobin polymerization. We assessed in vivo the potential curative threshold of fetal hemoglobin in the SAD transgenic mouse model of sickle cell disease using mating with mice expressing the human fetal Agamma-globin gene. With increasing levels of HbF, AgammaSAD mice showed considerable improvement in all hematologic parameters, morphopathologic features and life span/survival. We established the direct therapeutic effect of fetal hemoglobin on sickle cell disease and demonstrated correction by increasing fetal hemoglobin to about 9-16% in this mouse model. This in vivo study emphasizes the potential of the SAD mouse models for quantitative analysis of gene therapy approaches.