UNDERSTANDING THAT INFORMED CONSENT forms are provided to be read and comprehended, this study compares the research assistant's perception of comprehension with the actual time potential participants spend reading their consent form. After providing information verbally to two samples of women, research assistants observed as the women reviewed and signed the consent form recording the time spent reading and the assistant's impression of reading behavior. Over half of the women "read" their consent forms in thirty seconds or less before signing. Despite the brief time participants actually read, research assistants reported that 38%-74% (depending on the sample) appeared to have completely read the forms. Research to determine if timing aids will improve research assistants' assessment of participant reading behaviors should be considered.
When unmodified phage Ti infects restricting host cells at high multiplicities of infection, there is an increase in recombination frequency in all regions of the Ti map compared to the level of recombination in standard crosses when short distances are examined. The enhancement of recombination frequency is not uniform for all regions but is greatest for markers near the center of the map and not so great for markers near the ends. Crosses between markers at the extremities of the map show that there is no increase in recombination frequency under restriction conditions. An examination of phage Ti he'terozygotes suggests that an increase of ends created by the process of P1 restriction increases recombination. When Ti crosses are done in the absence of host restriction, recombination defects in the host have no effect on phage recombination and we conclude that phage Ti codes for its own recombination genes. Host recombination functions are also dispensable for the recombination occurring during infection ofrestricting host cells by unmodified phage at high multiplicities of infection.
Revertants of the cyc1-512 transcription termination mutant of the yeast Saccharomyces cerevisiae were isolated and subjected to a detailed genetic analysis. The cyc1-512 mutation previously was shown to be a 38-base pair deletion that causes only 10% of the normal steady-state levels of CYC1 mRNA and of the CYC1 gene product, iso-1-cytochrome c. Forty-one cyc1-512 revertants were classified by their content of iso-1-cytochrome c and by their genetic properties in meiotic crosses. Many of the revertants contain local genetic changes that either partially or completely restore the level of iso-1-cytochrome c. One revertant was shown to contain an unlinked extragenic suppressor, designated sut1, that causes partial suppression of the transcription termination defect. Four revertants of cyc1-512 contain chromosomal rearrangements with breakpoints that are tightly linked to the CYC1 locus; these include one duplication, one possible inversion, and two reciprocal translocations. Detailed genetic mapping demonstrated that one of the reciprocal translocations is between the right arms of chromosomes X and XII, with a breakpoint mapping 3′ to the CYC1 locus. These results indicate that the defect in transcription termination in cyc1-512 can be restored in a variety of ways, including the translocation of different chromosomal regions to the 3′ end of the CYC1 locus, local changes presumably at or near the original defect, and by mutation at another locus distinct from CYC1.
At high multiplicities of infection, a substantial fraction of restricting cells (P1 lysogens) could be productively infected by unmodified coliphage Ti (Tl.O) provided that protein synthesis was uninhibited during the first 5 min of infection. Successful infection under restricting conditions was accompanied by more genetic recombination than was seen under nonrestricting conditions. When protein synthesis was inhibited during early infection of a restricting host, the recombination frequency declined for markers on Tl.O genomes; no effect was seen on recombination between markers on modified (T1.P) genomes. This suggested that recombination between unmodified genomes may be essential for their survival under conditions of host restriction. In a restricting host, genetic markers on TL.O could recombine with T1.P even when the rescuing phage was added 6 min after T1.O infection. However, even marker rescue recombination was diminished when protein synthesis was inhibited during early infection. Since DNA restriction is an early event, protein synthesis may be required soon after infection of a restricting host by TL.O in order to preserve restriction-damaged DNA in a form that can participate in recombination. Experiments are also described that rule out some possibilities for the role of such a protein(s).
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