cDNA cloning and complete primary structure of the small, active subunit of human carboxypeptidase N (kininase 1)

The human plasma metallo-protease carboxypeptidase N of Mr 280,000 consists of two small, enzymatically active subunits of Mr 50,000 and two large subunits. Only the large subunits are glycosylated. They may have a function in stabilizing the complex in plasma. The N-terminal sequence of the small subunit was determined from the isolated protein and used to specify a unique 59-mer oligonucleotide probe. A cDNA clone of 1.7 kbp containing the entire coding sequence of the small subunit of carboxypeptidase N was isolated from a human-liver cDNA library. The cDNA clone encodes a signal sequence of 20 amino acids and the 438 amino acids of the mature subunit. There is a remarkable primary structure similarity of 49% to bovine carboxypeptidase E (enkephalin convertase). A more distant relationship to the bovine pancreatic, digestive carboxypeptidases A and B or even to the metallo-endopeptidases is based mainly on the occurrence of conserved, mechanistically important residues.     

The distribution of the Hb Constant Spring gene in Southeast Asian populations

Summary The distribution of the hemoglobin Constant Spring (Hb CS) gene in eight populations in Southeast Asia (including Assam) was determined using oligonucleotide hybridization. Hb CS was absent in two Assamese populations with a high prevalence of Hb E. The Hb CS gene frequency was 0.033 in northern Thailand and near 0.01 in central Thailand and Cambodia. High frequencies, between 0.05 and 0.06, were observed in northeastern Thailand. The present data and a similar study in Laotians suggest that the Lao-speaking populations of the Mekong River basin in northeastern Thailand and Laos have the highest frequencies of the Hb CS gene in Southeast Asia.     

Histochemical localization of IGF-I and IGF-II mRNA in the rat between birth and adulthood

We describe the postnatal ontogeny and localization of insulin-like growth factors I and II (IGF-I and -II) in the rat. We have used oligodeoxyribonucleotide probes for in situ hybridization (hybridization histochemistry) and for Northern blotting. IGF-II mRNA is strongly expressed in liver, skeletal muscle, perichondrium, leptomeninges and choroid plexus of the newborn. Demonstrable levels fall dramatically in the liver at 18-20 days postnatally but persist for longer periods in muscle and remain undiminished throughout life in the pia/choroid plexus, indicating that different control mechanisms operate in these tissues. IGF-I mRNA is predominantly found in the liver. Its level in this organ rises well before levels of IGF-II fall. This suggests that distinct factors govern the expression of IGF-I and -II genes.     

DNA haplotypes and frameworks associated with the beta-globin gene in the Kachari population of Assam (India)

DNA haplotypes and frameworks associated with the beta-globin gene were determined in a Tibeto-Burman group, the Kachari, from Upper Assam, India, using restriction analysis at eight restriction sites. Of the total of 59 subjects, 26 were homozygous for HBB*A and 33 homozygous for HBB*E. Complete haplotype determination in 33 subjects revealed a conspicuous difference in haplotype distribution between HBB*A- and HBB*E-bearing chromosomes. The Southeast Asian HBB*E-associated haplotype -+- +- (27-2 in the present terminology) predominated on HBB*E chromosomes. The previously established beta-globin-associated frameworks 1, 2 and 3 were evenly distributed among the HBB*A chromosomes, whereas all HBB*E chromosomes had framework 2. These findings favor a common origin of the HBB*E gene in Southeast Asia and Assam.     

Alpha-thalassemia in northern Thailand. Frequency of deletional types characterized at the DNA level

The frequency of alpha-thalassemias in northern Thailand was estimated using DNA techniques. Among 106 healthy adult Thais from the Chiangmai area, 28 were shown to carry alpha-globin gene anomalies. There were 19 heterozygotes and 1 homozygote for alpha-thalassemia-2. One of the alpha-thalassemia-2 deletions was of the -alpha 4.2 type and the remaining 20 of the -alpha 3.7 type (subtype I). Deletions of both alpha-globin genes on one chromosome (alpha-thalassemia-1) of the Southeast Asian type were observed in 5 cases, and 3 alpha-globin gene triplications were identified. Compared with a previous report on alpha-thalassemia in northern Thailand which was based on the determination of hemoglobin Bart's in cord blood, the present DNA study reveals a similar frequency of alpha-thalassemia-2 but a considerably lower frequency of alpha-thalassemia-1.     

Distribution of adult lactase phenotypes in the Tuareg of Niger.

The adult lactase phenotype, lactose absorber or malabsorber, was determined using the lactose tolerance test with breath hydrogen assay in a group of Tuareg, a traditionally nomadic pastoralist population in the central Sahara. Out of a total of 118 subjects, 103 (87.3%) were lactose absorbers and 15 (12.7%) lactose malabsorbers. The frequency of the "lactase suppression gene" in this population sample was .357 (SD .043). The low frequency of lactase suppression in the Tuareg supports the hypothesis of natural selection in favor of the "lactase persistence gene" in milk-dependent nomadic pastoralist.     

Differential Effect of Phleomycin on the Infectivity of Poliovirus and Poliovirus-Induced Ribonucleic Acids

The infectivity of intact poliovirus was not affected by exposure to the antibiotic phleomycin at concentrations as high as 200 mug/ml, whereas that of the singlestranded poliovirus ribonucleic acid (RNA) was inactivated to 99% by pretreatment of the RNA with phleomycin at a concentration of 2 mug/ml. The infectivity of double and multistranded RNA was 10 times less sensitive than that of singlestranded RNA to the action of this antibiotic. Preincubation of HeLa cells for 30 min with 10 to 50 mug of phleomycin reduced the sensitivity of the cells to infection by viral RNA and intact virus, indicating that phleomycin interferes with cellular functions necessary for virus replication. When phleomycin was added to cells at different times after infection with single- or double-stranded RNA, the highest inactivation of infective centers was observed immediately after infection. With time of incubation at 37 C, the infective centers became more resistant to the action of phleomycin.