Clinical importance of extraordinary integration patterns of human T- cell lymphotropic virus type I proviral DNA in adult T-cell leukemia/lymphoma [see comments]

The proviral DNA of human T-cell lymphotrophic virus type I (HTLV-I) is known to be integrated monoclonally in the malignant cells of adult T- cell leukemia/lymphoma (ATL), which is a peripheral T-cell malignancy caused by this virus. We studied the relationship between the integration patterns of HTLV-I and clinical characteristics in 89 patients with ATL. The proviral DNA of HTLV-I was examined by the standard Southern blot analysis using the endonucleases EcoRI and Pst I. One clear band of greater than 9 kb was detected in most of the patients (83 case) when cellular DNA was digested with EcoRI. On the other hand, extraordinary integration patterns of HTLV-I proviral DNA were detected in 6 patients; 3 of them showed two bands, while the other 3 showed one band smaller than 9 kb. When cellular DNA was digested with PstI, the band patterns of these patients were quite different from those of typical patients. The patients with the extraordinary integration patterns had clinical characteristics dissimilar to those of the other 83 patients with the ordinary integration pattern. The patients with two bands by EcoRI digestion always had severe hypoxemia with extremely high levels of serum lactate dehydrogenase at first presentation and showed peculiar organ infiltrations, such as retina and muscle, which were less frequent in the other ordinary 83 patients. They all died within 8 months after the onset. In contrast, the patients with one smaller band by EcoRI digestion always had small and mature T lymphocytes with bilobulated nuclei without lymphadenopathy and showed a favorable clinical course, which was uncommon in the ordinary cases. They were alive 20 to 38 months after diagnosis. Rearranged bands of the T-cell receptor gene were detected in all patients with unusual integration. These findings indicate that the integration patterns of HTLV-I proviral DNA have a clinical implication and may be one of the explanations for heterogeneity in the behavior of this disease.

Clinical importance of extraordinary integration patterns of human T- cell lymphotropic virus type I proviral DNA in adult T-cell leukemia/lymphoma [see comments]

The proviral DNA of human T-cell lymphotrophic virus type I (HTLV-I) is known to be integrated monoclonally in the malignant cells of adult T- cell leukemia/lymphoma (ATL), which is a peripheral T-cell malignancy caused by this virus. We studied the relationship between the integration patterns of HTLV-I and clinical characteristics in 89 patients with ATL. The proviral DNA of HTLV-I was examined by the standard Southern blot analysis using the endonucleases EcoRI and Pst I. One clear band of greater than 9 kb was detected in most of the patients (83 case) when cellular DNA was digested with EcoRI. On the other hand, extraordinary integration patterns of HTLV-I proviral DNA were detected in 6 patients; 3 of them showed two bands, while the other 3 showed one band smaller than 9 kb. When cellular DNA was digested with PstI, the band patterns of these patients were quite different from those of typical patients. The patients with the extraordinary integration patterns had clinical characteristics dissimilar to those of the other 83 patients with the ordinary integration pattern. The patients with two bands by EcoRI digestion always had severe hypoxemia with extremely high levels of serum lactate dehydrogenase at first presentation and showed peculiar organ infiltrations, such as retina and muscle, which were less frequent in the other ordinary 83 patients. They all died within 8 months after the onset. In contrast, the patients with one smaller band by EcoRI digestion always had small and mature T lymphocytes with bilobulated nuclei without lymphadenopathy and showed a favorable clinical course, which was uncommon in the ordinary cases. They were alive 20 to 38 months after diagnosis. Rearranged bands of the T-cell receptor gene were detected in all patients with unusual integration. These findings indicate that the integration patterns of HTLV-I proviral DNA have a clinical implication and may be one of the explanations for heterogeneity in the behavior of this disease.

PATTERNS OF MITOCHONDRIAL DNA VARIATION IN INDIGENOUS MAIZE RACES OF LATIN AMERICA

ABSTRACT Mitochondrial DNAs (mtDNAs) were isolated from 93 diverse races of maize from Latin America. DNAs were examined by agarose gel electrophoresis of undigested DNA and by BamHI and EcoRI cleavage fragment analysis. Eighteen races contained plasmid-like mtDNAs. One race contained the S-1 and S-2 molecules associated with the S cytoplasmic male-sterile, and 17 were found to have the R-1 and R-2 plasmid-like DNAs. BamHI digestion of mtDNAs generated ten distinct electrophoretograms, and EcoRI digestion produced eight different fragment patterns. Races were assigned to one of 18 groups according to EcoRI and BamHI fragment patterns and whether or not they contained plasmid-like DNAs. Eight races produced restriction patterns similar to one of the characterized cytoplasmic male-steriles C, T, or S. Races from Meso-America and some from South America with Meso-American affinities were separated from other South American races. South American races were placed in three general classes of related groups. There was considerable agreement among the groupings here and those based on morphological and cytological affinities.

EFFECT OF RADIATION DOSAGE ON EFFICIENCY OF CHLOROPLAST TRANSFER BY PROTOPLAST FUSION IN NICOTIANA

ABSTRACT Chloroplasts of Nicotiana tabacum SR1 were transferred into Nicotiana plumbaginifolia by protoplast fusion. The protoplasts of the organelle donor were irradiated with different lethal doses using a 60Co source, to facilitate the elimination of their nuclei from the fusion products. After fusion induction, clones derived from fusion products and containing streptomycin-resistant N. tabacum SR1 chloroplasts were selected by their ability to green on a selective medium. When N. tabacum protoplasts were inactivated by iodoacetate instead of irradiation, the proportion of N. plumbaginifolia nuclear segregant clones was low (1-2%). Irradiation markedly increased this value: Using 50, 120, 210 and 300 J kg-1 doses, the frequency of segregant clones was 44, 57, 84 and 70 percent, respectively. Regeneration of resistant N. plumbaginifolia plants with SR1 chloroplasts indicated that plastids can be rescued from the irradiated cells by fusion with untreated protoplasts. Resistant N. plumbaginifolia plants that were regenerated (43 clones studied) had diploid (2n = 2X = 20) or tetraploid chromosome numbers and were identical morphologically to parental plants. The absence of aneuploids suggests that in these clones irradiation resulted in complete elimination of the irradiated N. tabacum nuclei. Resistance is inherited maternally (five clones tested). The demonstration of chloroplast transfer and the presence of N. tabacum plastids in the N. plumbaginifolia plants was confirmed by chloroplast DNA fragmentation patterns after EcoRI digestion.

A partial map of the circular mitochondrial genome of Drosophila melanogaster. Location of EcoRI-sensitive sites and the adenine-thymine-rich region.

The mitochondrial genome of Drosophila melanogaster is a circular DNA molecule of mol wt 12.35 X 10(6) daltons. A single region accounting for approx. 25% of this molecule can be reproducibly differentially denatured presumably because it is rich in adenine and thymine. We have mapped on the circular mitochondrial genome of D. melanogaster the relative positions of this adenine-thymine (A-T) rich region and the sites sensitive to cleavage by the restriction endonuclease EcoRI, using agarose gel electrophoresis and electron microscopy. Digestion of mitochondrial DNA (mtDNA) molecules to completion with EcoRI resulted in the production of four fragments, A, B, C, and D which represent (+/- SD) 58.9 +/- 1.1%, 27.5 +/- 0.8%, 8.9 +/- 0.5%, and 4.5 +/- 0.3%, of the circular genome length, respectively. Fragments produced by EcoRI digestion and circularized by incubation at 2 degrees C also fell into four distinct length groups with means (+/- SD) of 59.1 +/- 0.5%, 27.5 +/- 0.5%, 9.2 +/- 0.3%, and 4.6 +/- 0.2% of the circular genome length. From a consideration of the lengths of fragments resulting from incomplete EcoRI digestion, it was determined that the arrangement of the fragments in the circular genome was A-C-B-D. By electron microscope examination of partially denatured EcoRI fragments, the A-T-rich region was shown to be located in the A fragment closer to one end than to the other. By similar partial-denaturation studies of fragments resulting from incomplete EcoRI digestion, it was determined that, in the circular genome, of the two EcoRI sites which define the limits of the A fragment, the site between the A and D fragment lies nearest to the A-T-rich region.