In vitro characterization of repair synthesis initiated by T4 endonuclease V on a synthetic DNA substrate.

The size of the repair patch produced by E. coli DNA polymerase (Pol I) following the removal of a pyrimidine dimer from DNA in response to the nicking activity of T4 endonuclease (T4 endo V) was determined. A 48-bp DNA containing a pyrimidine dimer at a defined location was labelled in the damaged strand and incubated with T4 endo V and E. coli endonuclease IV. Subsequently, DNA synthesis by DNA Pol I was carried out in the presence of four dNTPs, ATP and DNA ligase. Analysis of the reaction products on a sequencing gel revealed a ladder of only 4-oligonucleotides, 1-4 nucleotides greater in length than the fragment generated by the combined nicking activities of T4 endo V and E. coli endonuclease IV. Thus we conclude that the in vitro repair patch size of T4 endo V is 4 nucleotides and that in some cases the repaired DNA is not ligated.

Studies on the growth of the phage T4 in cell division mutantsa DV1211 and AD651 of Esachechiria coli AT normal and high temperatures

Os mutantes DV1211 e AD651 da divisäo celular em E. coli apresentam reduçäo na taxa de adsorçäo do fago T4 à sua superfície celular. O crescimento deste fago nos referidos mutantes é normal, porém , a 42 graus C apresenta um considerável retardo na sua liberaçäo por lise celular. O fenômeno parece estar associado à uma alteraçäo termoinduzida no mecanismo de maturaçäo do fago T4

Phage-typing of brucella strains collected in Italy during 1982-83

62 strains of Brucella genus, freshly isolated from man and animals in several geographical aereas in Italy, were tested for sensitivity to the phages: Tb. Wb, Fi. BK2 and R. The strains from human source, all classified like Br. melitensis biotype II. had three sensitivity patterns to phages. Some of the strains from cattle are Br. abortus biotype 1, with the standard sensitivity pattern to the phages, but among cattle strains too, the largest part may be classified as Br. melitensis biotype II, and shows the same phage sensitivity pattern of the human strains. The strains from sheep are Br. melitensis biotype II. with only two phage sensitivity pattern; but it is to emphasize that some strains from goats are Br. abortus for sensitivity to phage Tb. It is also note the strains from buffaloes, which are Br. abortus biotype I with a very high degree of sensitivity to all the testes phages, included the R phage. wich is supposed active on rough strains while these are smooth