Supportive and unsupportive responses of others to rape victims: effects on concurrent victim adjustment.

Evaluated the impact that actions of significant others have on adjustment following rape. Significant other behavior is conceptualized as having two dimensions--supportive behavior and unsupportive behavior--and each dimension was measured using multiple items. Unsupportive behavior, but not supportive behavior, was found to bear a significant association to victim adjustment. Implications for those who work with victims are discussed.

Characterization of cold-sensitive secY mutants of Escherichia coli.

Mutations which cause poor growth at a low temperature, which affect aspects of protein secretion, and which map in or around secY (prlA) were characterized. The prlA1012 mutant, previously shown to suppress a secA mutation, proved to have a wild-type secY gene, indicating that this mutation cannot be taken as genetic evidence for the secA-secY interaction. Two cold-sensitive mutants, the secY39 and secY40 mutants, which had been selected by their ability to enhance secA expression, contained single-amino-acid alterations in the same cytoplasmic domain of the SecY protein. Protein export in vivo was partially slowed down by the secY39 mutation at 37 to 39 degrees C, and the retardation was immediately and strikingly enhanced upon exposure to nonpermissive temperatures (15 to 23 degrees C). The rate of posttranslational translocation of the precursor to the OmpA protein (pro-OmpA protein) into wild-type membrane vesicles in vitro was only slightly affected by reaction temperatures ranging from 37 to 15 degrees C, and about 65% of OmpA was eventually sequestered at both temperatures. Membrane vesicles from the secY39 mutant were much less active in supporting pro-OmpA translocation even at 37 degrees C, at which about 20% sequestration was attained. At 15 degrees C, the activity of the mutant membrane decreased further. The rapid temperature response in vivo and the impaired in vitro translocation activity at low temperatures with the secY39 mutant support the notion that SecY, a membrane-embedded secretion factor, participates in protein translocation across the bacterial cytoplasmic membrane.

Genetic studies on the inability of beta-galactosidase to be translocated across the Escherichia coli cytoplasmic membrane.

When a signal sequence is attached to beta-galactosidase, the normally cytoplasmic protein is unable to fully traverse the cytoplasmic membrane. We used a genetic approach to study those features of beta-galactosidase responsible for the block in translocation. By using both in vivo and in vitro techniques, fragments of beta-galactosidase were interposed between a signal sequence and alkaline phosphatase. The alkaline phosphatase acts as a sensor for any blocking effects of beta-galactosidase on export. From these studies, we show that multiple regions of beta-galactosidase contribute to its failure to be translocated. These results are most easily interpreted if the folding of beta-galactosidase or of domains of it is responsible for the block in export. In addition, in certain constructs, positively charged amino acids directly following the signal sequence interfered with export.

The use of extragenic suppressors to define genes involved in protein export in Escherichia coli.

The secA gene codes for a membrane component involved in protein export in E. coli. In order to define other genes whose products play such a role, we have characterized extragenic suppressors of a secA(Ts) mutation. These suppressors fall into at least three genetic loci. One such locus is the prlA gene, previously identified by mutations which suppress signal sequence mutants. Thus, this approach may allow the identification of new genes involved in the export process.

Blue ghosts: a new method for isolating amber mutants defective in essential genes of Escherichia coli.

We describe a technique which permits an easy screening for amber mutants defective in essential genes of Escherichia coli. Using this approach, we have isolated three amber mutants defective in the rho gene. An extension of the technique allows the detection of ochre mutants and transposon insertions in essential genes.

Sites within gene lacZ of Escherichia coli for formation of active hybrid beta-galactosidase molecules.

We describe the genetic analysis of 21 Escherichia coli strains in which the amino-terminal sequence of beta-galactosidase has been removed and replaced by an amino-terminal sequence from one or another of the proteins involved in maltose transport. Genetic mapping of the lacZ end of these fused genes indicates that only those fusions in which fewer than 41 amino acids are removed from the amino-terminal sequence of beta-galactosidase result in enzymatically active molecules. Within the region between amino acid 17 and amino acid 41 there are at least four or five sites where enzymatically active hybrid proteins can be formed.

Structure of the malB region in Escherichia coli K12. II. Genetic map of the malE,F,G operon.

Starting with a strain containing a malK-lacZ fusion, a series of lambda plaque-forming phages which carry varying amounts of the malE,F operon have been isolated. We have used these phages to construct a deletion map of the malE,F operon. The construction of this deletion map has led to the identification of a new gene, malG. The malG gene is located distal to malF. The malG gene product is a protein required for the active transport of maltose and maltodextrins.

Genetic characterization of mutations which affect catabolite-sensitive operons in Escherichia coli, including deletions of the gene for adenyl cyclase.

Sixty-two spontaneous mutations have been characterized which reduce the level of expression of catabolite-sensitive operons. These mutations appear to affect either the crp (catabolite gene activator protein) or cya (adenyl cyclase) loci. No new loci have been discovered. Deletions of the cya gene do not remove an essential function. phi80 transducing phage for the cya gene have been used to do recombination and complementation studies on cya mutants.