Purification and characterization of cytoplasmic 14C-arginine rich basic proteins of Ehrlich ascites tumor cells

Summary Arginine rich basic proteins from cytoplasm of Ehrlich ascites tumor cells have been separated and partially characterized. All proteins show a cationic character with the following isoelectric points: 8.45, 8.60, 8.70, 8.90, and possess various amount of arginine. The protein of the highest molecular weight (75000) has the greatest amount of arginine (18.1%), specific radioactivity (19760 cpm/mg, min) and isoelectric point (8.9). The significance of those proteins in the cytoplasm of tumor cells has been discussed briefly.     

Characterization of cytoplasmic arginine-rich basic protein of Guerin epithelioma

Summary Arginine-rich basic protein from cytoplasma of Guerin epitheliomas has been isolated and characterized. It contains five amino acids: arginine, lysine, glycine, alanine and glutamic acid which make together 74 per cent of all amino acid residues. The protein has a cationic character with an isoelectric point of 8.2. No carbohydrate component was found in this protein. The significance of arginine-rich basic protein in the cytoplasma of Guerin epithelioma is discussed briefly.     

Uptake of immune RNA by normal mouse spleen cells

Summary Normal mouse spleen cells take up in vitro radioactively labeled immune RNA. RNA taken up is present in nuclei, polysomes, membranes and cytoplasm. About 20–40% of immune RNA is nonspecifically associated with cell surface. 45% of RNA taken up is degraded and reutilized inside the cells within 2 hours.This work was supported by the Polish Academy of Sciences within the project 09.7.4.1.1.     

The Stability of Trisubstituted Internucleotide Bond in the Presence of the Vicinal 2′-Hydroxyl. Chemical Synthesis of Uridyl(2′-phosphate)-(3′-5′)-uridine

Abstract

The effect of eleven different phosphoryl center protecting groups on the stability of trisubstituted internucleotide bond of the dimers (1a-k), in the presence of the vicinal 2′-hydroxyl, was examined. It has been found that electronic properties of the phosphoryl center protecting groups are essential for the reactivity of the trisubstituted internucleotide bond. Those observations were applied to the chemical synthesis of the uridyl(2′-phosphate)-(3′-5′)-uridine, a useful model for further pre-tRNA splicing studies.     

Oxidative DNA Base Modifications and Polycyclic Aromatic Hydrocarbon DNA Adducts in Squamous Cell Carcinoma of Larynx

Tobacco smoke, recognized as a major etiological factor for cancers of the upper aerodigestive tract, represents an abundant source of reactive oxygen species (ROS), which are believed to play a significant role in mutagenesis and carcinogenesis. An additional source of ROS in tissues exposed to tobacco smoke may be metabolic oxidation of polycyclic aromatic hydrocarbons (PAH). To investigate the relationships between oxidative DNA lesions and aromatic DNA adducts, six modified DNA bases 5-hydroxyuracil, 5-hydroxycytosine, 7,8-dihydro-8-oxoguanine, 7,8-dihydro-8-oxoadenine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine and 4,6-diamino-5-formamidopyrimidine and the total level of PAH-related DNA adducts were measured in cancerous and the surrounding normal larynx tissues (68 subjects), using gas chromatography/isotope-dilution mass spectroscopy with selected ion monitoring and the 32 P-postlabeling-HPLC assay, respectively. The levels of oxidative DNA lesions in cancerous and adjacent tissue were comparable; the differences between the two types of tissue were significant only for 5-hydroxypyrimidines (slightly higher levels were observed in the adjacent tissue). Comparable levels of DNA lesions in cancerous and the surrounding normal tissues observed in the larynx tumors support a field cancerization theory. The surrounding tissues may still be recognized as normal by histological criteria. However, molecular alterations resulting from the chronic tobacco smoke exposure, which equally affects larynx epithelia, may lead to multiple premalignant lesions. Thus, a demonstration of similar levels of DNA damage in cancerous and the adjacent tissue could explain a frequent formation of secondary tumors in the larynx and the frequent recurrence in this type of cancer. A weak, but distinct effect of tumor grading and metastatic status was observed in both kinds of tissue in the case of 5-hydroxyuracil, 5-hydroxycytosine, 7,8-dihydro-8-oxoguanine, 7,8-dihydro-8-oxoadenine. This effect was displayed as a gradual shift in the data distribution toward high values from G1 through G2-G3 and from non-metastatic to metastatic tumors. Since the levels of oxidative DNA base modifications tended to increase with the tumor aggressiveness, we postulate that the oxidative DNA lesions increase genetic instability and thus contribute to tumor progression in laryngeal cancer. No associations between aromatic adduct levels and oxidative DNA lesions were present, suggesting that the metabolism of PAH does not contribute significantly to the oxidative stress in larynx tissues, remaining the tobacco smoke ROS as a major source of oxidative DNA damage in the exposed tissue.     

Synthesis of 5′-O-Dimeth0Xytrityl-4-N-/6-Trifluoroacetamidohexyl/-2′-Deoxycytidine and its Application in the Synthesis of Biotin-Labeled Oligonucleotides

Abstract

5′3′-O-protected 4-N-tosyl-2′-deoxycyt id ine was converted with 1,6-diaminohexane to 4-N-/6-ami nohexyl/-2′-deoxycyt id i ne and then into 5′-0-d imethoxytr i ty 1 -k-N-/(-tr if luoroacetamidohexyl 1–2 ′-deoxycyt id ine, The latter was used to prepare oligonucleotides by the phosphoramidite approach. Deprotected oligomers were labeled with biotin.     

Synthesis of,and Conformational Studies on, 2-Trifluoromethyl,Substituted Benzimidazole Ribofuranosides

Abstract

The 1-β-D-ribofuranosides of several 2-trifluoromethyl benzimidazoles were prepared by the fusion method, and their conformations, particularly about the glycosidic bond, determined by ¹H NMR spectroscopy.     

RESTRICTED PLEIOTROPY FACILITATES MUTATIONAL EROSION OF MAJOR LIFE‐HISTORY TRAITS

Radical shifts to new natural and human made niches can make some functions unneeded and thus exposed to genetic degeneration. Here we ask not about highly specialized and rarely used functions but those relating to major life‐history traits, rate of growth, and resistance to prolonged starvation. We found that in yeast each of the two traits was visibly impaired by at least several hundred individual gene deletions. There were relatively few deletions affecting negatively both traits and likely none harming one but improving the other. Functional profiles of gene deletions affecting either growth or survival were strikingly different: the first related chiefly to synthesis of macromolecules whereas the second to maintenance and recycling of cellular structures. The observed pattern of gene indispensability corresponds to that of gene induction, providing a rather rare example of agreement between the results of deletion and expression studies. We conclude that transitions to new environments in which the ability to grow at possibly fastest rate or survive under very long starvation become practically unnecessary can result in rapid erosion of these vital functions because they are coded by many genes constituting large mutational targets and because restricted pleiotropy is unlikely to constrain this process.