INVESTIGATION OF SECONDARY STRUCTURES AND MACROMOLECULAR INTERACTIONS IN BACTERIOPHAGE P22 BY LASER RAMAN SPECTROSCOPY

Laser Raman spectra of the DNA bacteriophage P22 and of its precursor particles and related structures have been obtained using 514.5-nm excitation. The spectra show that P22 DNA exists in the B form both inside of the phage head and after extraction from the phage. The major coat protein (gp5) contains a secondary structure composed of 18% α-helix, 20% β-sheet and 62% irregular conformations. The scaffolding protein (gp8) in the phage prohead is substantially richer than gp5 in α-helical content. Among the amino acid residues which give prominent Raman lines, the spectra show that tryptophans are exposed to solvent and most tyrosines are hydrogen bonded to positive donor groups. The above features of phage DNA and protein structures are nearly invariant to changes in temperature up to 80°C, indicating a remarkable thermal stability of the phage head and its encapsulated DNA.     

Ovomucoid intervening sequences specify functional domains and generate protein polymorphism

Two thirds of the natural chicken ovomucoid gene has been sequenced, including all exons and the intron sequences surrounding all fourteen intron/ exon junctions. The junction sequences surrounding four of the introns are redundant; however, the sequences surrounding the other three introns contain no redundancies and thus the splicing sites at either end of these three introns are unambiguous. The splicing in all cases conforms to the GT-AG rule. The ovomucoid gene sequence around intron F can be used to predict the cause of an internal deletion polymorphism in the ovomucoid protein, which is an apparent error in the processing of the ovomucoid pre-mRNA. We also compare the structural organization of the ovomucoid gene with the ovomucoid protein sequence to examine theories of the evolution of ovomucoids as well as the origin of intervening sequences. This analysis suggests that the present ovomucoid gene evolved from a primordial ovomucoid gene by two separate intragenic duplications. Furthermore, sequence analyses suggest that introns were present in the primordial ovomucoid gene before birds and mammals diverged, about 300 million years ago. Finally, the positions of the introns within the ovomucoid gene support the theory that introns separate gene segments that code for functional domains of proteins and provide insight on the manner by which eucaryotic genes were constructed during the process of evolution.     

No adverse prognostic influence of hepatitis B virus infection in acute childhood lymphoblastic leukemia

In the years 1980-1985 72 children with acute lymphoblastic leukemia were diagnosed and treated by intensive combination chemotherapy (BFM protocols 79, 81, 83). Of these children 33 acquired a Hepatitis B-virus-carrier state with 1983 as the peak year of incidence. Both groups of patients, the infected and the uninfected ones, were comparable as to prognostic factors. All except 8 patients are off chemotherapy after a total duration of treatment of 1 1/2 or 2 years. Probability for event-free survival (life table analysis, maximum observation time 82 months, minimum 12 months) is equal (0.77 vs. 0.75) in both groups. With 3 exceptions, all HBV-infected patients still carry the HBs-antigen in the serum; 22 of the 30 living patients in the infected group developed anti-HBc.     

A consideration of the role of cell surface macromolecules in the process of viral transformation.

There is extensive physiological evidence implicating the cell surface as the key organelle which mediates the cell:cell interactions which underlie both normal and neoplastic growth. This information has now been supplemented with biochemical and biophysical data which indicates that surface macromolecules, in particular the heteroglycans of transformed cells, differ from those which lie at the periphery of normal cells. In the case of cells neoplastically transformed by most tumour viruses it is clear that the small virus genome (2-5 x 10(6) daltons) cannot carry the total genetic information to accomodate these various biochemical modifications, if indeed they are encoded in separate genes (1). To examine the part played in transformation by cellular genes coding for surface heteroglycan formation, we have turned to a study of SV-3T3 cells (ts H6-15) which are temperature-sensitive for expression of the transformed cell phenotype (2). The data show that cells grown under conditions permissive and non-permissive for such expression exhibit the same pattern of formation of glycolipids, and the majority of the polypeptides of the plasma membrane. There are, however, significant differences in the synthesis of some glycopeptides. A large molecular weight, trypsin-labile glycopeptide, present at the surface of untransformed fibroblasts but barely measurable in some of their virus-transformed derivatives (3), was detected, essentially at the same level, at the surface of ts H6-15 cells grown at the permissive and non-permissive temperatures. The signficance of these observations is discussed.     

Pituitary and extrapituitary effects of somatostatin in normal man.

The effects of synthetic linear somatostatin on basal circulating levels on several pituitary and pancreatic hormones, and of glucose and free fatty acids (FFA) were studied in 6 normal men after an overnight fast. A priming intravenous infusion of 250 mug of somatostatin in 18 sec was followed by a constant infusion of 500 mug over a period of 60 min. A decrease in plasma values of GH, prolactin, TSH, insulin and glucagon and in blood glucose was observed during somatostatin infusion, while FFA levels increased progressively. Plasma IRI and blood glucose increased rapidly when the somatostatin infusion was stopped, while FFA decreased progressively; GH, prolactin, TSH and glucagon remained low as compared to basal levels for one hour after the end of the infusion, i.e. until the end of the experiment. A slight but significant increase of LH and ACTH was observed after the end of the infusion.     

Nucleic acid derivatives studied by preresonance and resonance Raman spectroscopy in the ultraviolet region

Raman spectra of AMP, UTP, GMP, and CMP, and of their bromo-derivatives (8 Br-ATP, 8-bromo-adenosine, 8-bromo-guanosine, 5-bromo-deoxyuridine, 5-bromo-cytidine), are reported. They are obtained using excitation wavelengths of 457.9 nm (ionized continuous argon laser) and of 300 nm (tunable pulsed dye laser). Comparison of spectra leads to the following observations: (1) preresonances Raman effects on nucleotides spectra at 300 nm; (2) resonance Raman effects on bromoderivatives spectra at 300 nm; (3) in dilute solution (10^?4M), shifts and enhancements of Raman lines of the bromo-derivatives with respect to the corresponding lines of nucleoctides. On the basis of these comparisons, the assignments of the Raman lines are discussed, This provide the necessary background for the understanding of the properties of selected groups in DNA in dilute solution. The new experimental set-up for measurements of Raman spectra using excitation in the uv regions is described. It is specially designed to incorporate the pulsed feature of the excitation laser and for correcting of the instabilities of the sourse.