[Analysis of peptide fragment insertions in the basic proteins of the bacteriophage M13, f1, and fd envelopes. Interconnection of structural characteristics of the envelope protein and viability of mutant phages]. / Analiz vstroek peptidnykh fragmentov v osnovnoi belok obolochki bakteriofagov M13, f1, i fd. Vzaimosviaz' strukturnykh kharakteristik belka obolochki i zhiznesposobnosti mutantnykh fagov.

An analysis of 12 peptide fragment insertions into the major coat protein (protein pVIII) of bacteriophages M13, f1 and fd has been done. To elucidate the relations between protein structural characteristics and viability of mutant phages, we used the program Pro-Anal. Correlations were found between phage viability and different physicochemical and structural characteristics of protein N-termini. Thus peptide insertions in nonviable phages have high indexes of alpha-helicity, volumes, and polarity as well as high moments (alpha-helical and beta-structural) of isoelectric point. On the other hand, high beta-turn indexes are correlated with viability. The most important factor which determines phage viability is the lack of positively charged amino acid residues on the C-terminal ends of peptide insertions. The correlations found hold for the pVIII proteins of four related phages-M13, IKe, If1 and I2-2. Based on these results, the rule of obtaining viable mutant phages with insertions in the major coat protein is suggested. A new site is described for peptide insertions--upstream of the first amino acid residue of the mature protein sequence.

[Effect of amniotic fluid on the "spontaneous" transformation of embryonic cells of rats]. / Vliianie amnioticheskoi zhidkosti na "spontannuiu" transformatsiiu embrional'nykh kletok krys.

While applying amniotic fluid of cow embryos, as one of the components of nutrition medium, the tumor-producing ability of cells is manifested in later period of cultivation. Less malignancy of the transformed cultures was noted, that is supported by a more slow tumor development, by nearly complete absence of metastases, and longer survival of tumor-bearing animals. On the other hand, amniotic fluid renders a somewhat accelerating (2--3 times greater than in the control) effect on the impairment of cultures diploidy. Heteroploidization of the cultures proceeds largely on account of chromosome number shifts from diploid to near-tetraploid amount. Thus, amniotic liquor inhibits the process of "spontaneous" malignant transformation of embryonal cells in prolonged cultivation, simultaneously accelerating the impairment of culture diploidy.