Synthesis and Insecticidal Activity of 4-Substituted 1-Indanyl Chrysanthemates

A variety of 4-substituted 1-indanyl chrysanthemates were prepared and their insecticidal activity was tested on American cockroachs. The activity of the chrysanthemates decreased in the following order: CH₂=CHCH₂>CH₃OCH₂?CH₃CH₂?HC≡CCH₂>PhCH₂, which was similar to that of p-substituted benzyl chrysanthemates against houseflies with the exception of the propargyl group. Formulation of the quantative structure-activity relationship by the Hansch’s program indicated that Van der Waals interaction between the chemical substance and the macromolecular in vivo play an important role in the 1-indanyl chrysanthemates.     

Revisiting gap locations in amino acid sequence alignments and a proposal for a method to improve them by introducing solvent accessibility

In comparative modeling, the quality of amino acid sequence alignment still constitutes a major bottleneck in the generation of high quality models of protein three-dimensional (3D) structures. Substantial efforts have been made to improve alignment quality by revising the substitution matrix, introducing multiple sequences, replacing dynamic programming with hidden Markov models, and incorporating 3D structure information. Improvements in the gap penalty have not been a major focus, however, following the development of the affine gap penalty and of the secondary structure dependent gap penalty. We revisited the correlation between protein 3D structure and gap location in a large protein 3D structure data set, and found that the frequency of gap locations approximated to an exponential function of the solvent accessibility of the inserted residues. The nonlinearity of the gap frequency as a function of accessibility corresponded well to the relationship between residue mutation pattern and residue accessibility. By introducing this relationship into the gap penalty calculation for pairwise alignment between template and target amino acid sequences, we were able to obtain a sequence alignment much closer to the structural alignment. The quality of the alignments was substantially improved on a pair of sequences with identity in the "twilight zone" between 20 and 40%. The relocation of gaps by our new method made a significant improvement in comparative modeling, exemplified here by the Bacillus subtilis yitF protein. The method was implemented in a computer program, ALAdeGAP (ALignment with Accessibility dependent GAp Penalty), which is available at http://cib.cf.ocha.ac.jp/target_protein/.     

Effects of sandblasting and salt spray on inland plants transplanted to coastal sand dunes

A transplant experiment was conducted on a sandy beach to elucidate whether salt spray and sandblasting are the major factors inhibiting inland plants from becoming established on coastal sand dunes. Potted inland plants of Miscanthus sinensis and Imperata cylindrica var. koenigii were transplanted in two zones on the beach and in one area far inland from the beach. One zone on the beach (sea side) was located on a front dune that was occupied by native sand-dune plants; the other zone (land side) was located behind the sand dunes, where grassland comprised both sand-dune and inland species. To assess the condition of transplants, we measured changes in the canopy leaf area periodically at all sites. The final dry weight at each site was determined at the end of the experiment. Seasonal changes in sandblasting and salt spray intensities were evaluated periodically at the sites by measurement of the opaqueness of exposed transparent plastic sheets and the amount of sodium trapped in exposed filter papers, respectively. All transplants died in the sea-side zone, where both salt spray and sandblasting were most frequent and intense. The final dry weight was greatest at the inland site, which lacked salt spray and sandblasting. Although salt spray was intense in the land-side zone, the canopy leaf area decreased considerably only in seasons during which salt spray was accompanied by intense sandblasting. We concluded that sandblasting accompanied by salt spray is one of the main factors inhibiting the survival and growth of inland plants on coastal sand dunes.     

The localized melting of mini-F origin by the combined action of the mini-F initiator protein (RepE) and HU and DnaA of Escherichia coli

 Replication of mini-F plasmids requires the initiator protein RepE, which binds specifically to four iterons within the origin (ori2), as well as some host factors that are involved in chromosomal DNA replication. To understand the role of host factors and RepE in the early steps of mini-F DNA replication, we examined the effects of RepE and the Escherichia coli proteins DnaA and HU on the localized melting of ori2 DNA in a purified in vitro system. We found that the binding of RepE to an iteron causes a 50^° bend at or around the site of binding. RepE and HU exhibited synergistic effects on the localized melting within the ori2 region, as detected by sensitivity to the single-strand specific P1 endonuclease. This opening of duplex DNA occurred around the 13mer of ori2, whose sequence closely resembles the set of 13mers found in the chromosomal origin oriC. Further addition of DnaA to the reaction mixture increased the efficiency of melting and appeared to extend melting to the adjacent AT-rich region. Moreover, DNA melting with appreciably higher efficiencies was observed with mutant forms of RepE that were previously shown to be hyperactive both in DNA binding in vitro and in initiator activity in vivo. We propose that the binding of RepE to four iterons of ori2 causes bending at the sites of RepE binding and, with the assistance of HU, induces a localized melting in the 13mer region. The addition of DnaA extends melting to the AT-rich region, which could then serve as the entry site for the DnaB-DnaC complex, much as has been documented for oriC- dependent replication. Received: 15 May 1996/Accepted: 11 July 1996     

Peripheral Tγ lymphocyte population in head and neck cancer

Summary Peripheral T lymphocytes were measured in head and neck cancer patients and controls. The percentage was significantly higher in the 59 cancer patients than in the 46 normal controls (P<0.001). The 12 patients with recurrent disease had elevated percentages of T lymphocytes compared with the untreated group (n=31; P<0.05) and the treated, disease-free group (n=16; P<0.05). Moreover, the percentage of T lymphocytes was significantly higher in the 31 patients with regional lymph node metastasis than in the node-negative group (n=28; P<0.05). In a total of 37 patients with squamous cell carcinoma histologically graded I, II, and III, the absolute counts and percentages of T lymphocytes in the grade I group (n=13) showed significant decreases compared with those in the grade III group (P<0.05; n=6). Moreover, postoperative serial determinations of the percentage of T lymphocytes in the 14 treated, disease-free patients revealed a gradual decrease of T lymphocytes, whereas the five patients with recurrent disease had a tendency to increases in the percentage of T lymphocytes. Abbreviations used in this paper: SMF, sodium metrizoate-Ficoll; PBS, phosphate-buffered saline; SRBC, sheep erythrocytes; FCS, fetal calf serum; Hepes, hydroxyethylpiperazin elthene-sulfonic acid; E, erythrocyte; EAC, erythrocyte-antibody-complement; K, antibody-dependent killer; NK, natural killer     

Control of F plasmid replication by a host gene: evidence for interaction of the mafA gene product of Escherichia coli with the mini-F incC region.

Replication of F (including mini-F) and some related plasmids is known to be specifically inhibited in mafA mutants of Escherichia coli K-12. We have now isolated and characterized mini-F mutants that can overcome the replication inhibition. Such plasmids, designated pom (permissive on maf), were obtained spontaneously or after mutagenesis with hydroxylamine or by transposon (Tn3) insertion. In addition to their ability to replicate in mafA mutant bacteria, the pom mutant plasmids exhibit an increased copy number and resistance to "curing" by acridine dye in the mafA+ host. In agreement with these results, Tn3-induced pom mutants were found to carry Tn3 inserted at the incC region of mini-F DNA, known to be involved in incompatibility, control of copy number, and sensitivity to acridine dye. Furthermore, three of the seven mini-F plasmids tested that carry Tn3 within the tandem repeat sequences of the incC region (previously isolated by other workers) exhibit all the phenotypes of pom plasmids, the ability to replicate in the mafA strain, and high copy number and acridine resistance in the mafA+ strain. The rest of the plasmids that contain Tn3 just outside the tandem repeats remain wild type in all these properties. These results strongly suggest that the putative mafA gene product of host bacteria controls mini-F replication through interaction with the incC region.