Cloning of cDNAs for human phosphoribosylpyrophosphate synthetases 1 and 2 and X chromosome localization of PRPS1 and PRPS2 genes

Cloned cDNAs representing the entire, homologous (80%) translated sequences of human phosphoribosylpyrophosphate synthetase (PRS) 1 and PRS 2 cDNAs were utilized as probes to localize the corresponding human PRPS1 and PRPS2 genes, previously reported to be X chromosome linked. PRPS1 and PRPS2 loci mapped to the intervals Xq22-q24 and Xp22.2-p22.3, respectively, using a combination of in situ chromosomal hybridization and human x rodent somatic cell panel genomic DNA hybridization analyses. A PRPS1-related gene or pseudogene (PRPS1L2) was also identified using in situ chromosomal hybridization at 9q33-q34. Human HPRT and PRPS1 loci are not closely linked. Despite marked cDNA and deduced amino acid sequence homology, human PRS 1 and PRS 2 isoforms are encoded by genes widely separated on the X chromosome.     

Adipose-tissue-specific increase in glyceraldehyde-3-phosphate dehydrogenase activity and mRNA amounts in suckling pre-obese Zucker rats. Effect of weaning.

The regulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene expression was studied during the onset of obesity in the genetically obese (fa/fa) rat by determination of GAPDH activity and hybridizable mRNA amounts in adipose tissue and liver from suckling and weanling rats. GADPH activity remained low throughout the suckling period, and a burst of activity occurred after weaning in both lean and obese pups. As early as 7 days of age, adipose tissue from pre-obese rats displayed a significant increase in enzyme activity, whereas no difference could be detected in the liver. In both suckling (16 days of age) and weanling (30 days of age) obese rats a proportionate increase in GAPDH activity and mRNA amounts was observed in adipose tissue, but not in liver. It is concluded that the obese genotype influences GAPDH gene expression at a pretranslational level and in a tissue-specific manner. This phenomenon could partly contribute to the hyperactive fat accretion in the obese rat, since glycolysis is the major metabolic pathway for lipogenic substrates in adipose tissue.     

A group of type I keratin genes on human chromosome 17: characterization and expression.

The human type I keratins K16 and K14 are coexpressed in a number of epithelial tissues, including esophagus, tongue, and hair follicles. We determined that two genes encoding K16 and three genes encoding K14 were clustered in two distinct segments of chromosome 17. The genes within each cluster were tightly linked, and large parts of the genome containing these genes have been recently duplicated. The sequences of the two K16 genes showed striking homology not only within the coding sequences, but also within the intron positions and sequences and extending at least 400 base pairs 5' upstream and 850 base pairs 3' downstream from these genes. Despite the strong homologies between these two genes, only one of the genes encoded a protein which assembled into keratin filaments when introduced into simple epithelial cells. While there were no obvious abnormalities in the sequence of the other gene, its promoter seemed to be significantly weaker, and even a hybrid gene with the other gene's promoter gave rise to a much reduced mRNA level after gene transfection. To demonstrate that the functional K16 gene that we identified was in fact responsible for the K16 expressed in human tissues, we made a polyclonal antiserum which recognized our functional K16 gene product in both denatured and filamentous form and which was specific for bona fide human K16.     

The effect of beta-estradiol, progesterone and testosterone on the production of human leukocyte derived interferons

Sex hormones including estrogens, progesterone and testosterones are known to have adverse effects on the immune system and particularly on the proliferative response. Since cytokine production is known to be dissociable from the proliferation of lymphocytes and since other steroid hormones profoundly affect cytokine production, we felt it would be important to know the effect of sex steroids on the production of interferons (IFN), particularly since the latter are known to be key substances in the immune response. We have shown estradiol can slightly reduce gamma IFN yields with certain inducers (Con A, SEA) but only in pharmacologic concentrations. Similarly, progesterone had a modest effect in the same concentrations but only when Con A was the inducer. Testosterone did not effect IFN titers at any concentration. None of the sex steroids affected alpha IFN production and none of them influenced the bioactivity of either IFN species. In all cases these hormones diminished proliferative responses as has been previously noted.     

Iron kinetics effects of 88 millirads. Partial-versus-total body X-irradiation

Rats were irradiated with one tibia shielded (95% marrow exposure), total body exposed (TBI, 100%), and only one tibia exposed (5%), or they were sham irradiated (SI, 0%). Plasma Fe-59 clearance time (T1/2) and Fe-59 content ratio in the right and left tibia (RT/LT) were assayed to determine the erythroid activity of the overall marrow of the animals and the relative marrow activity in the exposed and shielded tibias, respectively. When a major fraction of the overall marrow was shielded or irradiated, the overall erythroid activity levels were identical to those of the SI and TBI animals, respectively. Interestingly, enhanced normoblastosis was observed in the marrow of the exposed tibia of individual animals exhibiting normal erythroid activity in 95% of the marrow. Conversely, localized marrow with normal erythroid activity was found in a shielded tibia of individual rats, demonstrating an enhanced erythroid activity in a major fraction of the total body. It was concluded that 88 mrad can alter marrow functions in a small isolated skeletal region as effectively as in the whole body, and tandem assays of the Fe-59 T1/2 and Fe-59 RT/LT can facilitate ultra-low-dose X-ray studies involved with partial body exposures.     

Attachment of trivaline changes the specificity of binding of netropsin analogs with DNA

In the present communication, synthesis and DNA binding activities of three analogs of the antibiotic netropsin are reported. Each analog contains two N-propylpyrrolecarboxamide units linked covalently to either Dns-Gly-Val-Val-Val-Gly-Gly- (I), Val-Val-Val-Gly-Gly (II) or Gly-Gly (III). It is shown that analogs I and II can self-associate in aqueous solution and methanol as revealed from the fact that UV absorbance and circular dichroism spectra obtained for these analogs are concentration-dependent. By contrast, analogs III exists as a monomer, even at concentration levels of the order of 1.10(-3) M. Determination of the apparent sizes of intramolecular aggregates by gel-filtration shows that analog I in aqueous solution at concentration levels of the order of 1.10(-3) M forms a series of aggregates containing from 2 to 12 monomers. Analog II exhibits a lower tendency to form intermolecular aggregates as compared with that of analog I. Dimerization constants are determined for analogs I and II in aqueous solution and methanol. The binding of N-propylpyrrolecarboxamide units and peptide fragments of analog I to DNA can be independently monitored by circular dichroism and fluorescence methods. If self-associated species of analog I (or II) are present in solution, the ligand exhibits a markedly different order of base pair sequence preferencies as compared with that of analog III. The results obtained are consistent with the inference that analogs I and II in a beta-associated form recognizes base pair sequences containing two runs of 3 AT pairs separated by two GC pairs.