Cytoplasmic “Petite” Induction in Recombination-Deficient Mutants of Saccharomyces cerevisiae

As compared to the original wild type, the induction of the cytoplasmic "petite" mutation by ultraviolet light and by the intercalating dye, ethidium bromide, is reduced in two mutants (rec4 and rec5) of Saccharomyces cerevisiae. These mutants are blocked in X rays or ultraviolet light-induced intragenic recombination. It then appears that the products of nuclear genes necessary for the completion of nuclear intragenic recombination events are also involved in steps of the metabolic chain which leads to the mitochondrial mutation, rho(-).     

Localization of Two Functions of the Phosphoribosyl Anthranilate Transferase of Escherichia coli to Distinct Regions of the Polypeptide Chain

The trpD gene specifies a polypeptide which has both glutamine amidotransferase and phosphoribosyl anthranilate (PRA) transferase activities. Deletions fusing segments of trpD to the gene preceding it in the operon, trpE, were selected in strains carrying various trpD point mutations. The selection procedure required both that a deletion enter trpE and that it restore the PRA transferase activity which the parent trpD point mutant lacked. Deletion mutants were found which had PRA transferase activity although the first third of trpD was deleted. The existence of the mutants proves that a terminal segment of trpD is sufficient to specify a polypeptide having PRA transferase activity. The location of the deletion end points on the genetic map of trpD defines the extent of the trpD segment required for PRA transferase activity. This segment did not overlap the initial region of trpD required to specify the glutamine amidotransferase function of the trpD polypeptide. These results support the hypothesis (M. Grieshaber and R. Bauerle, 1972; H. Zalkin and L. H. Hwang, 1971) that the bifunctional trpD polypeptide might have evolved by fusion of a gene specifying a glutamine amidotransferase with a gene directing PRA transferase synthesis.     

Behavior Change Pathways to Voluntary Medical Male Circumcision: Narrative Interviews with Circumcision Clients in Zambia

As an HIV prevention strategy, the scale-up of voluntary medical male circumcision (VMMC) is underway in 14 countries in Africa. For prevention impact, these countries must perform millions of circumcisions in adolescent and adult men before 2015. Although acceptability of VMMC in the region is well documented and service delivery efforts have proven successful, countries remain behind in meeting circumcision targets. A better understanding of men''s VMMC-seeking behaviors and experiences is needed to improve communication and interventions to accelerate uptake. To this end, we conducted semi-structured interviews with 40 clients waiting for surgical circumcision at clinics in Zambia. Based on Stages of Change behavioral theory, men were asked to recount how they learned about adult circumcision, why they decided it was right for them, what they feared most, how they overcame their fears, and the steps they took to make it to the clinic that day. Thematic analysis across all cases allowed us to identify key behavior change triggers while within-case analysis elucidated variants of one predominant behavior change pattern. Major stages included: awareness and critical belief adjustment, norming pressures and personalization of advantages, a period of fear management and finally VMMC-seeking. Qualitative comparative analysis of ever-married and never-married men revealed important similarities and differences between the two groups. Unprompted, 17 of the men described one to four failed prior attempts to become circumcised. Experienced more frequently by older men, failed VMMC attempts were often due to service-side barriers. Findings highlight intervention opportunities to increase VMMC uptake. Reaching uncircumcised men via close male friends and female sex partners and tailoring messages to stage-specific concerns and needs would help accelerate men''s movement through the behavior change process. Expanding service access is also needed to meet current demand. Improving clinic efficiencies and introducing time-saving procedures and advance scheduling options should be considered.     

A yeast protein analogous to Escherichia coli RecA protein whose cellular level is enhanced after UV irradiation

Summary In Saccharomyces cerevisiae, a protein was recognized by polyclonal antibodies raised against homogeneous Escherichia coli K12 RecA protein. The cellular level of the yeast protein called RecAsc (molecular weight 44 kDa, pI 6.3), was transiently enhanced after UV irradiation. Protease inhibitors were required to minimize degradation of the RecAsc protein during cell lysis. The RecAsc protein exhibited similar basal levels and similar kinetics of increase after UV irradiation in DNA-repair proficient (RAD ⁺) strains carrying mitochondrial DNA or not (rho ⁰). This was also true for the following DNA-repair deficient (rad ^-) strains: rad2-6 rad6-1 rad52-1, a triple mutant blocked in three major repair pathways; rad6-, a mutant containing an integrative deletion in a gene playing a central role in mutagenesis; pso2-1, a mutant that exhibits a reduced rate of mutagenesis and recombination after exposure to DNA cross-linking agents.     

Additional Restriction Endonuclease Cleavage Sites on the Bacteriophage P22 Genome

We present complete restriction endonuclease cleavage site maps of the bacteriophage P22 chromosome for 16 enzymes with six base recognition sequences, thereby positioning 116 new sites on the chromosome. Twenty-four such restriction maps for P22 DNA, containing 162 sites, have now been completed, and three enzymes were found that did not cut P22 DNA. Our results are consistent with the ideas that ClaI does not cleave the methylated recognition sequence ATCGA(me)T or A(me)TCGAT and StuI does not cleave the methylated recognition sequence AGGCC(me)T.