Large-scale analysis of expressed genes from the leaf of oilseed rape (Brassica napus L.)

While the number of leaf-specific expressed genes is estimated to be approximately 6,000, an overview of gene diversity and expression patterns in the leaf of oilseed rape (Brassica napus L.) has not yet been reported. In an effort to understand gene expression patterns and to identify new genes, we generated 754 expressed sequence tags (ESTs) from the leaf of B. napus. By comparing them to public databases, we showed that 204 of the ESTs (27.1%) have sequence homology to known genes, with 52 of them (6.9%) matching to genes not previously studied in B. napus. The most abundant transcripts were found to be involved in photosynthesis and energy metabolism. When compared with maize leaf ESTs and rice leaf ESTs, the pattern of gene expression was different depending on the developmental stages of the leaf.

STF1 is a novel TGACG-binding factor with a zinc-finger motif and a bZIP domain which heterodimerizes with GBF proteins

Two separate nuclear binding activities (B1 and B2) in the soybean apical hypocotyl have been identified that interact with a palindromic C-box sequence (TGACGTCA) and which are developmentally regulated in an inverse manner. The bZIP factors responsible for these two binding activities, B1 and B2, were isolated from a cDNA library and designated STGA1 and STFs (STF1 and STF2), respectively. Sequence analysis shows that the STFs contain both a zinc-finger domain and a bZIP domain. The two zinc finger sequences of Cys4-Cys4 are most related to the RING zinc-finger motif carrying a Cys3-His-Cys4. In addition the bZIP domain of STFs is highly homologous to the HY5 protein of Arabidopsis. DNA binding studies revealed that STF1 binding to the TGACGT sequence requires distinct flanking sequences. Furthermore, STF1 binds to the Hex sequence as a heterodimer with G-box binding factors (GBFs), a feature not observed with STGA1. Since STF1 expression is most prevalent in apical and elongating hypocotyls, it is proposed that STF1 may be a transcription factor involved in the process of hypocotyl elongation.

Synthesis and biological activity of bis(pivaloyloxymethyl) ester of 2'-azido-2'-deoxyuridine 5'-monophosphate

Bis(pivaloyloxymethyl) ester of 2'-azido-2'-deoxyuridine 5'-monophosphate was prepared as a prodrug to generate 2'-azido-2'-deoxyuridine 5'-diphosphate inside the cell. A synthetic route utilizing stannyl phosphate was adopted in the preparation. The prodrug was evaluated for cell growth inhibition against a variety of tumor cell lines along with 2'-azido-2'-deoxyuridine and 2'-azido-2'-deoxycytidine.

A new class II rice chitinase, Rcht2, whose induction by fungal elicitor is abolished by protein phosphatase 1 and 2A inhibitor

Among the four classes of chitinase, a class II chitinase had not yet been reported for rice. We have isolated and characterized a class II acidic chitinase, Rcht2, from rice (Oryza sativa L. cv. Cheongcheongbyeo). The protein consists of a single polypeptide chain of 261 amino acid residues and includes a putative signal sequence of 29 amino acids at its N-terminus. It has a calculated molecular mass of 27,642 Da and an isoelectric point of 5.56. The Rcht2 chitinase lacks the cysteine-rich and hinge domains in the N-terminal region of the protein, which is the criterion for its classification as a class II chitinase. Comparison of the genomic and the cDNA sequence revealed that the coding region of Rcht2 consist of three exons of 301, 112, and 370 bp separated by two introns of 89 and 984 bp. In suspension-cultured rice cells, the transcript level of Rcht2 was dramatically increased by treatment with both glycol chitin and fungal elicitor. The application of protein phosphatase 1 and 2A inhibitors, calyculin A and okadaic acid, effectively abolished the induction of Rcht2 in response to fungal elicitor. In contrast, the activation of Rcht2 transcript was not inhibited by both cycloheximide and protein kinase inhibitors. These results demonstrate that protein dephosphorylation events play a crucial role in the elicitor-mediated induction of Rcht2 in rice cells, while de novo protein synthesis is not required for induction.

Biological activity and phosphorylation of 2'-azido-2'-deoxyuridine and 2'-azido-2'-deoxycytidine

2'-Azido-2'-deoxyuridine and 2'-azido-2'-deoxycytidine were evaluated for their inhibitory activity against ribonucleotide reductase and for subsequent cell growth inhibition. Their mono- and di-phosphates were synthesized and their inhibitory activities against the reductase were also determined in a permeabilized cell system, along with the two nucleosides. The results of the present study identify the first phosphorylation step involved in the conversion of the two azidonucleosides to the corresponding diphosphates to be rate-limiting in the overall activation.

Up-regulation of luciferase gene expression with antisense oligonucleotides: implications and applications in functional assay development

HeLa Tet-Off cells were transfected transiently as well as stably with a recombinant plasmid (pLuc/705) carrying the luciferase gene interrupted by a mutated human beta-globin intron 2 (IVS2-705). The mutation in the intron causes aberrant splicing of luciferase pre-mRNA, preventing translation of luciferase. However, treatment of the cells with a 2'-O-methyl-oligoribonucleotide targeted to the aberrant splice sites induces correct splicing, restoring luciferase activity. The effects are sequence-specific, depend on the concentration of the oligonucleotide, and can be modulated by the pretreatment of the cell line, Luc/705, with tetracycline. Thus, the cell line provides, among others, a novel functional assay system superior to other procedures that are based on protein down-regulation. In particular, the system would be ideal in assessing the cellular delivery efficiency of antisense oligonucleotides.

Use of the Center for Epidemiologic Studies Depression (CES-D) Scale in Korea

We translated the Center for Epidemiologic Studies Depression (CES-D) Scale into Korean, paying careful attention to culturally different modes of expression of depressive feelings and thoughts. The final translated version (CES-D-K) was administered to 164 psychiatric patients and 464 normal subjects residing in the community. Reliability, validity, and the optimal cutoff point of this scale were estimated, including ROC analysis. The CES-D-K was reliable and valid for the Korean population. Two optimal cutoff points were suggested: 24/25, the point which best corresponded to the clinical diagnosis of depression, and 20/21, which most effectively detects and covers depressive symptoms during screening. The higher cutoff points than those in Western countries may be due to different ways of expression affect, especially the suppression of positive affect, in cultures based on Confucian ethics.

Preliminary X-ray crystallographic analysis of a novel maltogenic amylase from Bacillus stearothermophilus ET1

A novel maltogenic amylase from Bacillus stearothermophilus ET1, which has a dual activity of alpha-1,4- and alpha-1,6-glycosidic bond cleavages and alpha-1,6-glycosidic bond formation, was crystallized by using the hanging-drop vapor-diffusion method. The best crystals were obtained by employing a high concentration of protein (56 mg ml-1) and a precipitant containing 22% glycerol, 1.6 M ammonium sulfate in 0.1 M Tris-HCl (pH 8.5). Native diffraction data to 2.66 A resolution have been obtained from crystals flash-frozen at 110 K. The crystals belong to the space group P212121 with unit-cell dimensions of a = 77.62, b = 121.23, c = 244. 29 A, and contain three or four protomers per asymmetric unit. Structure determination by multiple isomorphous replacement is in progress.

Sensitized liposomes as an antigen delivery system for the stimulation of mucosal immunity

This study was designed to exploit the ability of Peyer's patch M cells to recognize antigen-antibody complexes in the targeted delivery of a model antigen for the induction of mucosal immunity. Sensitized liposomes consisted of an entrapped model antigen, ovalbumin (OVA), and coated with unrelated antigen-antibody complexes. Sensitized liposomes were administered intrajejunally to mice either with or without monophosphoryl lipid A (MLA). Humoral immune responses were monitored in saliva, feces, serum, and bile. Mice which received sensitized liposomes showed up to 4-fold amounts of specific IgA in saliva, feces, and bile compared to controls. Transient increases in anti-OVA IgA and IgG were observed in serum. Formulations including MLA generated positive anti-OVA IgG responses in both serum and bile. In separate experiments, cell proliferation studies were performed with Peyer's patch lymphocytes harvested from mice immunized with OVA in either standard or sensitized liposomes. Lymphocytes from test mice receiving only sensitized liposomes proliferated in the presence of OVA, but not an unrelated antigen. Taken together, these results support the potential application of antigen-antibody complexes in the stimulation of mucosal immune responses and that MLA may play an important role in overcoming OVA tolerogenicity.

Comparison of Helicobacter pylori infection between Fukuoka, Japan and Chinju, Korea

BACKGROUND

Helicobacter pylori is the causative agent of type B chronic gastritis, and plays a major role in the pathogenesis of gastroduodenal ulcer and gastric cancer. Because gastric cancer has been the leading cause of cancer mortality in Japan and Korea, we conducted a seroepidemiological study to estimate the prevalence of H. pylori infection in Japan and Korea in order to explain the current change in the gastric cancer incidences between two countries.

MATERIALS AND METHODS

Samples used for this study included 1204 sera from Chinju, Korea and 580 sera from Fukuoka, Japan. Immunoblotting, using a sonicated crude H. pylori antigen and 1:5 dilution of serum, was performed, considering the immunoblot shows reactivity to the 120 Kd antigen of H. pylori as a specific marker of H. pylori infection.

RESULTS

Seroepidemiology data from Fukuoka, Japan showed a prevalence of H. pylori infection of 20% before school age, 40% by teenage years, and over 80% beyond 20 years of age. Seroepidemiology data from Chinju, Korea, showed a 50% infection rate in preschool ages, and over 80% prevalence rate after 7 years of age.

CONCLUSIONS

Lower rates of childhood H. pylori infection in Fukuoka may explain the recent decline and shift in the incidence of stomach cancer in Japan, supporting the hypothesis that H. pylori is a major determinant in the pathogenesis of stomach cancer.

Cloning of the 52-kDa chitinase gene from Serratia marcescens KCTC2172 and its proteolytic cleavage into an active 35-kDa enzyme

A chitinase gene (pCHI52) encoding the 52-kDa chitinase was isolated from a Serratia marcescens KCTC2172 cosmid library. This chitinase gene consists of 2526 bp with an open reading frame that encodes 485 amino acids. Escherichia coli harboring the pCHI52 gene secreted not only a 52-kDa but also a 35-kDa chitinase into the culture supernatant. We purified both 52-kDa and 35-kDa chitinases using a chitin affinity column and Sephacryl-S-300 gel filtration chromatography. We determined that the 17 N-terminal amino acid sequences of the 52-kDa and the 35-kDa chitinase are identical. Furthermore, a protease obtained from S. marcescens KCTC2172 cleaved the 52-kDa chitinase into the 35-kDa protein with chitinase activity. These results suggest that the 35-kDa chitinase derives from the 52-kDa chitinase by post-translational proteolytic modification. The optimal reaction temperature of 45 degrees C and the optimal pH of 5.5 were identical for both enzymes. The specific activities of the 52-kDa and 35-kDa chitinases on natural swollen chitin were 67 mumol min-1 mg-1 and 60 mumol min-1 mg-1, respectively.

A dynamin-like protein in Arabidopsis thaliana is involved in biogenesis of thylakoid membranes

Dynamin, a GTP-binding protein found in rat brain, plays a role in endocytosis. Suborganellar fractionation studies of Arabidopsis leaf tissue revealed that a dynamin-like protein, ADL1, is localized in the thylakoid membranes of chloroplasts. This notion was supported further by in vivo targeting experiments using an ADL1-green fluorescent fusion protein and immunogold labeling with the anti-ADL1 antibody. Transgenic plants harboring various deletion mutant genes of ADL1 had a yellow leaf phenotype where the cells had very few chloroplasts. In addition, the remaining chloroplasts appeared morphologically not fully developed. The detailed structure of the chloroplasts revealed by electron microscopy showed a greatly reduced amount of thylakoid membranes. Also, the level of thylakoid membrane proteins such as the light-harvesting complex II and CP29 was greatly reduced in these transgenic plants. When we examined the expression of the ADL1 deletion mutant genes, these genes were highly expressed at the transcriptional level. However, the mutant ADL1s were not detectable at the protein level by Western blot analysis. Moreover, the endogenous ADL1 protein level was greatly reduced in these transgenic plants, probably due to a post-transcriptional silencing effect of the transgenes. We propose, therefore, that ADLl is involved in the biogenesis of thylakoid membranes.

Two hevein homologs isolated from the seed of Pharbitis nil L. exhibit potent antifungal activity

Two antifungal peptides (Pn-AMP1 and Pn-AMP2) have been purified to homogeneity from seeds of Pharbitis nil. The amino acid sequences of Pn-AMP1 (41 amino acid0 residues) and Pn-AMP2 (40 amino acid residues) were identical except that Pn-AMP1 has an additional serine residue at the carboxyl-terminus. The molecular masses of Pn-AMP1 and Pn-AMP2 were confirmed as 4299.7 and 4213.2 Da, respectively. Both the Pn-AMPs were highly basic (pI 12.02) and had characteristics of cysteine/glycine rich chitin-binding domain. Pn-AMPs exhibited potent antifungal activity against both chitin-containing and non-chitin-containing fungi in the cell wall. Concentrations required for 50% inhibition of fungal growth were ranged from 3 to 26 micrograms/ml for Pn-AMP1 and from 0.6 to 75 micrograms/ml for Pn-AMP2. The Pn-AMPs penetrated very rapidly into fungal hyphae and localized at septum and hyphal tips of fungi, which caused burst of hyphal tips. Burst of hyphae resulted in disruption of the fungal membrane and leakage of the cytoplasmic materials. To our knowledge, Pn-AMPs are the first hevein-like proteins that show similar fungicidal effects as thionins do.

Construction of a Helicobacter pylori-Escherichia coli shuttle vector for gene transfer in Helicobacter pylori

In this study, a Helicobacter pylori-Escherichia coli shuttle vector was constructed for transferring DNA into H. pylori. The smallest cryptic plasmid (1.2 kb), pHP489, among those harbored by 77 H. pylori isolates was selected as a base replicon for constructing vectors. HindIII-digested pHP489 was ligated with a kanamycin resistance gene [aph(3')-III], which originated from Campylobacter jejuni, to produce the recombinant plasmid pHP489K. pHP489K was efficiently transformed into and stably maintained in H. pylori strains. The shuttle vector pBHP489K (3.6 kb) was constructed by the recombination of pHP489, ColE1, and aph(3')-III sequences. pBHP489K was reciprocally transformed into and maintained in both H. pylori and E. coli. Introduction of the shuttle vector clone DNA (pBHP489K/AB; 6.7 kb), containing the ureA and ureB genes of H. pylori, into urease-negative mutants of H. pylori led to the restoration of their urease activity. The transformants were confirmed to contain the incoming plasmid DNA. pBHP489K satisfied the requirements for an H. pylori-E. coli shuttle vector, implying that it might be a useful vector for investigating pathogenicity and restriction-modification systems of H. pylori.

Monoclonal antibodies against Helicobacter pylori cross-react with human tissue

BACKGROUND

H. pylori is a causative agent of chronic gastritis. However, the pathogenic mechanism by which H. pylori induces chronic inflammation and epithelial injuries in the gastric and duodenal mucosa is not well known. Investigators have recently reported that some monoclonal antibodies against H. pylori cross-react with the gastric epithelial cells. So, there exists the possibility that the autoimmune mechanism may be involved in the pathogenesis of chronic gastritis caused by H. pylori. The purpose of his study is to investigate whether the antibodies against H. pylori react with human tissues or not, using a large panel of monoclonal antibodies.

MATERIALS AND METHODS

Two hundred and fourteen monoclonal antibodies against H. pylori were produced. An immunohistochemical staining of human tissues, including H. pylori-infected gastric mucosa, was performed using the antibodies.

RESULTS

Of 214 monoclonal antibodies, 71 antibodies reacted with H. pylori in the gastric mucosa. Of 71 antibodies, 25 antibodies also reacted with gastric epithelial cells, 11 antibodies reacted with ductal cells of the salivary gland, 11 antibodies reacted with renal tubular cells, and 8 antibodies reacted with duodenal epithelial cells. The antibodies which showed cross-reactivity with gastric epithelial cells included those against urease, flagella, lipopolysaccharide, and heat shock protein of H. pylori.

CONCLUSIONS

It is believed that the autoimmune reaction might be involved in the pathogenesis of chronic gastritis due to H. pylori infection, and that the autoimmune reaction induced by H. pylori infection might also be involved in the pathogenesis of various diseases in other organs.

High-resolution crystal structures of delta5-3-ketosteroid isomerase with and without a reaction intermediate analogue

Bacterial Delta5-3-ketosteroid isomerase (KSI) catalyzes a stereospecific isomerization of steroid substrates at an extremely fast rate, overcoming a large disparity of pKa values between a catalytic residue and its target. The crystal structures of KSI from Pseudomonas putida and of the enzyme in complex with equilenin, an analogue of the reaction intermediate, have been determined at 1.9 and 2.5 A resolution, respectively. The structures reveal that the side chains of Tyr14 and Asp99 (a newly identified catalytic residue) form hydrogen bonds directly with the oxyanion of the bound inhibitor in a completely apolar milieu of the active site. No water molecule is found at the active site, and the access of bulk solvent is blocked by a layer of apolar residues. Asp99 is surrounded by six apolar residues, and consequently, its pKa appears to be elevated as high as 9.5 to be consistent with early studies. No interaction was found between the bound inhibitor and the residue 101 (phenylalanine in Pseudomonas testosteroni and methionine in P. putida KSI) which was suggested to contribute significantly to the rate enhancement based on mutational analysis. This observation excludes the residue 101 as a potential catalytic residue and requires that the rate enhancement should be explained solely by Tyr14 and Asp99. Kinetic analyses of Y14F and D99L mutant enzymes demonstrate that Tyr14 contributes much more significantly to the rate enhancement than Asp99. Previous studies and the structural analysis strongly suggest that the low-barrier hydrogen bond of Tyr14 (>7.1 kcal/mol), along with a moderate strength hydrogen bond of Asp99 ( approximately 4 kcal/mol), accounts for the required energy of 11 kcal/mol for the transition-state stabilization.

High-resolution crystal structures of delta5-3-ketosteroid isomerase with and without a reaction intermediate analogue

Bacterial Delta5-3-ketosteroid isomerase (KSI) catalyzes a stereospecific isomerization of steroid substrates at an extremely fast rate, overcoming a large disparity of pKa values between a catalytic residue and its target. The crystal structures of KSI from Pseudomonas putida and of the enzyme in complex with equilenin, an analogue of the reaction intermediate, have been determined at 1.9 and 2.5 A resolution, respectively. The structures reveal that the side chains of Tyr14 and Asp99 (a newly identified catalytic residue) form hydrogen bonds directly with the oxyanion of the bound inhibitor in a completely apolar milieu of the active site. No water molecule is found at the active site, and the access of bulk solvent is blocked by a layer of apolar residues. Asp99 is surrounded by six apolar residues, and consequently, its pKa appears to be elevated as high as 9.5 to be consistent with early studies. No interaction was found between the bound inhibitor and the residue 101 (phenylalanine in Pseudomonas testosteroni and methionine in P. putida KSI) which was suggested to contribute significantly to the rate enhancement based on mutational analysis. This observation excludes the residue 101 as a potential catalytic residue and requires that the rate enhancement should be explained solely by Tyr14 and Asp99. Kinetic analyses of Y14F and D99L mutant enzymes demonstrate that Tyr14 contributes much more significantly to the rate enhancement than Asp99. Previous studies and the structural analysis strongly suggest that the low-barrier hydrogen bond of Tyr14 (>7.1 kcal/mol), along with a moderate strength hydrogen bond of Asp99 ( approximately 4 kcal/mol), accounts for the required energy of 11 kcal/mol for the transition-state stabilization.

Primary non-Hodgkin lymphoma of the large bowel

PURPOSE

To characterize the natural history of primary non-Hodgkin lymphoma of the large bowel and identify prognostic factors.

MATERIALS AND METHODS

Twenty-three patients with primary non-Hodgkin lymphoma according to strict criteria were identified. Seventeen patients underwent resection, and six patients underwent biopsy. Among 19 patients with intermediate- or high-grade lymphoma, 13 had diffuse large cell lymphoma. Ann Arbor stage was I in 15 cases, II in seven cases, and IV in one case. In 15 patients, the International Prognostic Index was available: 0, eight patients; 1, six patients; and 3, one patient. Postoperatively, six patients received combined chemotherapy and radiation therapy, eight patients received chemotherapy, and six patients received radiation therapy. Overall and relapse-free survival were calculated actuarially, and univariate analysis was performed with regard to stage, treatment, extent of surgery, and the International Prognostic Index.

RESULTS

Median follow-up was 144 months. Two patients' disease recurred. Overall and relapse-free survival at 10 years were 61% and 82%, respectively. The International Prognostic Index was the only significant prognostic factor for overall survival (P = .03, log-rank test).

CONCLUSION

The prognosis of primary non-Hodgkin lymphoma appears to be as good as that of low- or intermediate-grade lymphoma. The only significant prognostic factor for overall survival is the International Prognostic Index.

A dynamin-like protein, ADL1, is present in membranes as a high-molecular-mass complex in Arabidopsis thaliana

Dynamin, a GTP-binding protein, is involved in endocytosis in animal cells. We found that a dynamin-like protein, ADL1, is present in multiple forms in Arabidopsis leaf tissue. Subcellular fractionation experiments, together with gel-filtration and nondenaturing-gel electrophoresis revealed that most of ADL1 is present as a high-molecular-mass complex of 400 to 600 kD in the membrane or pellet fraction, whereas ADL1 is present in the soluble fraction as a monomer. The subcellular distribution of ADL1 is affected by various agents such as Ca2+, cyclosporin A, GTP, and ATP. Ca2+ increases the amount of ADL1 present in the membrane fraction, whereas cyclosporin A inhibits the membrane association. Furthermore, Ca2+ and GTP change the migration pattern of ADL1 in nondenaturing polyacrylamide gels, indicating that these chemicals influence either the complex formation and/or the conformation of the ADL1 complex. Our results demonstrate that ADL1 has characteristics that are similar to Dynamin I, which is found in animal cells. Therefore, it is possible that ADL1 is also involved in biological processes that require vesicle formation.

Guanine-nucleotide binding and hydrolyzing kinetics of ORrab2, a rice small GTP-binding protein expressed in Escherichia coli

The ORrab2 gene encodes a GTP-binding protein of 23.169 kDa. The deduced amino acid sequence shows that ORrab2 has the motifs conserved among small GTP-binding proteins in plants and that it shares sequence identity with Atrab2 (93.0%), Hrab2 (85.2%), Hrab4 (51.9%), Hrab1 (46.2%), YPT (40.7%), Hrab3B (40.0%), Hrab3A (38.1%), SEC4 (38.1%), Hrab5 (34.3%) and Hrab6 (32.4%). To analyze the biochemical properties of this protein, an ORrab2 cDNA was overexpressed in Escherichia coli and the protein purified by Ni2+-nitrilotriacetic acid agarose and hydroxyapatite column chromatography. The molecular mass of the protein bearing a His-tag is approximately 28.2 kDa. The guanine-nucleotide binding and hydrolyzing activity of ORrab2 increased with non-ionic C12E10 (polyoxyethylene 10-lauryl ether) and ionic Chaps detergent treatment. ORrab2 bound maximally 1.03 mol of [gamma-35S]GTP[S]/mol of protein with a Kd value of 56.83 nM. The ratios k(off GDP)/k(off GTP) of ORrab2 were 3.63 for the control, 3.7 in the presence of C12E10, and 3.83 with Chaps, indicating that ORrab2 has a higher affinity for GTP than GDP. The rate (k(cat)) of Pi release against [gamma-32P]GTP bound ORrab2 in a steady state and the rate of hydrolysis of [gamma-32P]GTP (kGTPase) were calculated to be 432 x 10(-4) +/- 8 x 10(-4) min(-1) and 172 x 10(-4) +/- 2 x 10(-4) min(-1), respectively, in the presence of 0.1% C12E10 and 1 mM MgSO4.

Carcinoma involving the gallbladder in elderly patients presenting with acute cholecystitis

BACKGROUND

The unexpected intraoperative finding of a cancerous gallbladder has become particularly problematic, because cancer recurs rapidly after laparoscopic cholecystectomy. It would be desirable to identify the patients of greatest risk for gallbladder cancer before operation. After several elderly patients presenting with acute cholecystitis were found to have gallbladder cancer, we performed the following study.

METHODS

Records of patients (60 years of age or older, 1987 to 1995) with an admitting diagnosis of acute cholecystitis and symptoms including right upper quadrant pain, nausea, vomiting, fever, and leukocytosis were reviewed.

RESULTS

Eighty patients were included in the study. Carcinoma involving the gallbladder was found in seven patients; six had primary and one had metastatic carcinoma. The 73 patients without cancer underwent cholecystectomy. The differences between the noncancer and cancer patients included age (68 +/- 7 versus 74 +/- 8 years, p < 0.05), total bilirubin (mg/dl, 1.5 +/- 1.5 versus 3.7 +/- 3.4, p < 0.01), alkaline phosphatase (IU/L, 179 +/- 132 versus 369 +/- 226, p < 0.01), and aspartate aminotransferase (IU/L, 77 +/- 93 versus 158 +/- 157, p < 0.05).

CONCLUSIONS

Additional work-up and open cholecystectomy should be considered in elderly patients presenting with apparent acute cholecystitis, especially when liver functions are abnormal.

Functional features of an ssi signal of plasmid pGKV21 in Escherichia coli

A single-strand initiation (ssi) signal was detected on the Lactococcus lactis plasmid pGKV21 containing the replicon of pWV01 by its ability to complement the poor growth of an M13 phage derivative (M13 delta lac182) lacking the complementary-strand origin in Escherichia coli. This ssi signal was situated at the 229-nucleotide (nt) DdeI-DraI fragment and located within the 109 nt upstream of the nick site of the putative plus origin. SSI activity is orientation specific with respect to the direction of replication. We constructed an ssi signal-deleted plasmid and then examined the effects of the ssi signal on the conversion of the single-stranded replication intermediate to double-stranded plasmid DNA in E. coli. The plasmid lacking an ssi signal accumulated much more plasmid single-stranded DNA than the wild-type plasmid did. Moreover, deletion of this region caused a great reduction in plasmid copy number or plasmid maintenance. These results suggest that in E. coli, this ssi signal directs its lagging-strand synthesis as a minus origin of plasmid pGKV21. Primer RNA synthesis in vitro suggests that E. coli RNA polymerase directly recognizes the 229-nt ssi signal and synthesizes primer RNA dependent on the presence of E. coli single-stranded DNA binding (SSB) protein. This region contains two stem-loop structures, stem-loop I and stem-loop II. Deletion of stem-loop I portion results in loss of priming activity by E. coli RNA polymerase, suggesting that stem-loop I portion is essential for priming by E. coli RNA polymerase on the SSB-coated single-stranded DNA template.

Rapid PCR amplification of chimeric products and its direct application to in vivo [corrected] testing of recombinant DNA construction strategies

This article describes a simple and rapid method for efficient production of chimeric products by polymerase chain reaction (PCR). This protocol is amenable to site-directed mutagenesis strategies and can be done without the time-consuming gel purification step. The PCR products generated can also be directly used for direct gene transfer into plant cells without further subcloning to test construction strategies.

Differential expression of two functional serine/threonine protein kinases from soybean that have an unusual acidic domain at the carboxy terminus

Two soybean cDNA clones, SPK-3 and SPK-4, encoding putative protein kinases were isolated and characterized. Both cDNAs encoded approximately 40-kDa serine/threonine kinases with unusual stretches of acidic amino acids in their carboxy-terminal regions, which are highly homologous to PKABA1 from wheat and ASKs from Arabidopsis. These kinases are encoded by one- or two-copy genes in the soybean genome. Notably, SPK-3 and -4 showed different patterns of expression in various soybean tissues. SPK-3 is highly expressed in dividing and elongating tissues of young seedlings but relatively weakly in tissues of mature plants. In contrast, SPK-4 showed relatively high and constitutive expression in all the tissues examined except for leaf tissues of mature plants. Although various stressors, such as dehydration and high salinity, increased the expression of both genes, the induction kinetics were different. The two genes also differed in their response to abscisic acid (ABA). SPK-3 was induced but SPK-4 was not affected by exogenously supplied abscisic acid. In accordance with these expression data analysis of the activity of a chimeric SPK-3 promoter::beta-glucuronidase (GUS) reporter gene by transient expression in tobacco leaves confirmed the inducibility of SPK-3 by salt and ABA. Polyclonal antibodies raised against a recombinant SPK-4 protein produced in Escherichia coli specifically recognized both recombinant SPK-3 and -4 proteins. Kinase assays using affinity-purified SPK-4/ antibody complexes with crude soybean extracts as substrate identified specific phosphorylation of two 41 and 170 kDa soybean proteins that were phosphorylated on serine residues. Taken together, our results suggest that SPK-3, and/or SPK-4 are functional serine protein kinase(s). Furthermore, SPK-3 and -4 may play different roles in the transduction of various environmental stresses.

Isolation and characterization of the 54-kDa and 22-kDa chitinase genes of Serratia marcescens KCTC2172

A DNA fragment (pCHI5422) containing two genes encoding a 54-kD and a 22-kDa chitinase was isolated from a cosmid DNA library of Serratia marcescens KCTC2172. The complete nucleotide sequence of pCHI5422 consisting of 4581 bp was determined. The nucleotide sequence of the 22-kDa chitinase consists of 681 bp of open reading frame encoding 227 amino acids and is located 1422 bp downstream of the translation termination codon of the 54-kDa chitinase sequence. The 54-kDa chitinase gene consisted of 1497 bp in a single open reading frame encoding 499 amino acids. The genes encoding the 54-kDa and 22-kDa chitinase were separately subcloned in Escherichia coli and the individual chitinases were expressed and purified from the culture broth using chitin affinity chromatography. When chitohexaose was used as substrate, the major product of the enzymatic reaction of both the 54-kDa and 22-kDa chitinases was a (GlcNAc)2 dimer with a minor amount of monomer. The specific activity of the 54-kDa and 22-kDa chitinases were 300 microM (min)-1 mg-1 and 17 microM (min)-1 mg-1 on the natural swollen chitin, respectively.