The peptide bond between E292-A293 of Escherichia coli leucyl-tRNA synthetase is essential for its activity

Escherichia coli leucyl-tRNA synthetase (LeuRS) is a class I aminoacyl-tRNA synthetase that contains a large connecting polypeptide (CP1) inserted into its nucleotide binding fold, or active site. In this study, purified leucyl-tRNA synthetase was found to be cleaved between E292 and A293 in its CP1 domain. SDS-PAGE analysis showed peptides of 63 and 34 kDa in addition to the native 97.3 kDa synthetase. By internal complementation, the two peptides could form a 97.3 kDa complex similar to the native LeuRS. This complex could support the ATP approximately PP(i) exchange activity of LeuRS, but could not complement for aminoacylation. To study the function of the region around the bond of E292 and A293, four pairs of peptides resulting from different cleavage sites in CP1 were reconstituted in vivo. With the exception of the enzyme assembled from the E292-A293 cleavage site, all the reassembled LeuRSs catalyzed the aminoacylation of tRNA(Leu). Although the E292-A293-cleaved LeuRS could not catalyze aminoacylation, fluorescence titration revealed that its tRNA binding ability was almost identical to that of wild-type LeuRS. These results suggest that the region around E292-A293 may be responsible for maintaining the proper conformation of LeuRS required for the tRNA charging activity.

Quantitative trait Loci mapping of resistance to sugarcane mosaic virus in maize

ABSTRACT Sugarcane mosaic virus (SCMV) is an important virus disease of maize (Zea mays) in Europe. In this study, we mapped and characterized quantitative trait loci (QTL) affecting resistance to SCMV in a maize population consisting of 219 F(3) or immortalized F(2) families from the cross of two European maize inbreds, D32 (resistant) x D145 (susceptible). Resistance was evaluated in replicated field trials across two environments under artificial inoculation. The method of composite interval mapping was employed for QTL detection with a linkage map based on 87 restriction fragment length polymorphism and 7 mapped microsatellite markers. Genotypic and genotype x environment interaction variances for SCMV resistance were highly significant in the population. Heritabilities ranged from 0.77 to 0.94 for disease scores recorded on seven consecutive dates. Five QTL for SCMV resistance were identified on chromosomes 1, 3, 5, 6, and 10 in the joint analyses. Two major QTL on chromosomes 3 and 6 were detected consistently in both environments. Significant epistatic effects were found among some of these QTL. A simultaneous fit with all QTL in the joint analyses explained between 70 and 77% of the phenotypic variance observed at various stages of plant development. Resistance to SCMV was correlated with plant height and days to anthesis.

Response of Djun and Dfos mRNA abundance to signal transduction pathways in cultured cells of Drosophila melanogaster

The mammalian proto-oncogenes c-jun and c-fos are situated at the end of multiple signal transduction pathways and activation of their products Jun and Fos, components of the transcription factor AP-1, are able to regulate gene transcription in response to extracellular stimuli. Djun and Dfos, the products of the Drosophila proto-oncongenes Djun and Dfos, are similar in size and sequence to their mammalian counterparts c-Jun and c-Fos and are related to their mammalian counterparts by their antigenic properties. However, very little is known about how they are regulated through signal transduction pathways. This paper has investigated the response of their mRNA abundance levels to three signal transduction pathways in Drosophila cultured cells. Various agonists and antagonists that stimulate and inhibit specific enzymes in the pathways have been tested. The results suggest that Djun and Dfos mRNA are continuously expressed and their abundance levels are transiently regulated by multiple signaling pathways, the peak response coming at 1-2 hours after perturbation. Dfos is more highly regulated than Djun which is only modulated. The receptor tyrosine kinase pathways positively regulate Dfos and Djun. The cAMP-mediated pathway positively regulates Dfos but negatively regulates Djun. The protein kinase C-activated pathway does not affect Djun whereas it negatively regulates Dfos.

Multiple forms of p55PIK, a regulatory subunit of phosphoinositide 3-kinase, are generated by alternative initiation of translation

A cDNA encoding p55PIK, one of the regulatory subunits of phosphoinositide (phosphatidylinositol) 3-kinase, was cloned from a cDNA library derived from the mouse mammary epithelial cell line C57MG. The cDNA coding for full-length p55PIK was transiently expressed in COS-7 cells. Western blot analysis of p55PIK expression using a specific antibody against p55PIK revealed that multiple protein products with different molecular masses were detected in COS-7 cell extracts. Experiments presented here demonstrate that multiple forms of p55PIK detected in COS-7 cells were produced by alternative initiation of translation. We also show that at least two in-frame start codons (AUG#2 and AUG#5) in p55PIK mRNA are used in COS-7 cells for the initiation of translation of p55PIK into proteins of 54 kDa and 50 kDa respectively. p55PIK mRNA was also alternatively translated into two proteins in PC cells, a mouse teratoma cell line, indicating that the alternative initiation of translation of p55PIK is not restricted to COS-7 cells. Results from immunoprecipitation and Western blot analysis showed that two forms (54 kDa and 50 kDa protein species) of p55PIK were detected in C57MG cells. Interestingly, when C57MG cells were treated with insulin, only p55PIK, but not p50PIK, bound to insulin receptor substrate-1 protein, providing evidence that different forms of p55PIKs may have specific distinct roles in signal transduction pathways.

A unified and quantitative receptor model for the microtubule binding of paclitaxel and epothilone

[formula: see text] Paclitaxel and epothilone represent the two major classes of antimicrotubule agents that promote tubulin polymerization and, presumably, mitotic arrest during cell division. A common minireceptor binding site model at beta-tubulin has been constructed for these structurally divergent compounds. Utilizing 20 amino acids identified in photoaffinity labeling experiments, the 3-D model correlates measured and predicted Ki's with r = 0.99 and rms(delta Gcalc-delta Gexp) = 0.2 kcal/mol. In addition, the model predicts the affinity of compounds not used in the training set and explains much of the SAR for the paclitaxel and epothilone families.

[Simultaneous determination of tungsten, molybdenum and titanium by k-factor dual-wavelength standard addition method]

In this paper, a new method for simultaneous spectropthotometric determination of tungsten, molybdenum and titanium is proposed. The method is based on the difference of absorption spectra of the three elements forming coloured complexes with PF in acidic medium and in the presence of nonionic surfactant Tween-80. The absorbance of sample was measured at wavelengths of 503, 530 and 560 nm, and the data were treated by the principle of the k coefficients and dual-wavelength standard addition method. The method has been applied to the determination of tungsten, molybdenum and titanium in steels, and satisfactory results were obtained.

[Cephalometric analysis of the craniofacial bony structures in patients with obstructive sleep apnea]

OBJECTIVE

To explore the craniofacial bony structure abnormalities and their possible contributions to the apneic severity in patients with obstructive sleep apnea (OSA).

METHODS

One-night polysomnographic examination and a lateral cephalogram were performed in 102 male OSA patients and 37 healthy men. Sixteen variables representing craniofacial angle, distances and areas were measured by a computer software (NIH Image).

RESULTS

Compared with normal subjects, OSA patients presented with: a shortened cranial base (71 +/- 4) mm: (74 +/- 3) mm, (P < 0.001), maxillum (52 +/- 5) mm: (55 +/- 4) mm, (P < 0.01), mandible (74 +/- 5) mm: (77 +/- 6) mm, (P < 0.05) and bony nasopharygeal airway dimensions, a more inferiorly and anteriorly placed hyoid bone, and retrognathia deformity. Multiple stepwise regression analysis disclosed that maxilla deficiency, retrognathia and hyoid bone misposition were important contributing factors to the apneic severity (R2 = 0.447, F = 15.471, P < 0.0001).

CONCLUSIONS

OSA patients had certain craniofacial bony structure defects and cephalometric analysis of these defects is useful both in the investigation of the pathogenesis and the selection of an optimel treatment modality for each OSA patients.

[Retreatment after excimer laser photorefractive keratectomy]

OBJECTIVE

To evaluate the efficacy and safety of reoperation of residual myopia because of regression, undercorrection with or without coexisting severe corneal haze after excimer laser photorefractive keratectomy (PRK).

METHODS

A VISK 20/20 excimer laser was used to treat myopia of -1.00 to -16.50 diopters (spherical equivalent) at corneal plane. 35 patients (51 eyes) who had residual myopia because of regression, undercorrection with or without coexisting severe corneal haze after initial PRK were retreated by using PRK and phototherapeutic keratectomy.

RESULTS

At 12 months after retreatment, the rates of uncorrected visual acuity more than or equal to 10/20 or 20/20 were 82.6% and 39.1% respectively, 100.0% and 50.0% in myopia up to -6.00 D, 73.3% and 33.3% in myopia of -6.25 to -16.50 D respectively. 86.3% of eyes were within +/- 1.00 diopters of desired emmetropia. Corneal haze after retreatment was not greater than that observed after initial procedures.

CONCLUSIONS

The residual myopia because of regression, undercorrection with or without severe corneal haze after initial PRK can be successfully retreated. Although the therapeutic result of retreatment of PRK is less successful than that of the initial procedure, retreatment appears to enhance it.

[Clinical analysis of 96 cases with pulmonary disease caused by nontuberculous mycobacteria]

OBJECTIVE

To study the clinical characteristics of nontuberculous mycobacteria (NTM) pulmonary disease.

METHODS

Ninety-six out of 173 cases with NTM pulmonary disease diagnosed through identification of mycobacterium strains isolated from 5,592 sputum acid-fast staining positive cases from 1981-1996 were selected, and a retrospective analysis was made.

RESULTS

According to Runyon classification, there were 14 cases with M. kansasii and 1 with M. marinum in type I, 4 with M. scrofulsceum in type II, 23 with M. intracellulare or M. avium in type III, 24 with M. chelonae and 30 with M. fortuitumin in type IV. Cases whose courses of disease were more than 10 years accounted for 31%. Main clinical symptoms included cough (78%), expectoration (71%), haemoptysis (58%) and fever (26%). Fifty-seven percent cases in X-ray chest film were seen lesions bilaterally, 42% in one side, 27% in the right and 15% in the left. One percent showed no obvious lesion in X-ray chest film. Excluding one case with incomplete data, the total resistance rate of NTM was 96% in other 95 cases, 93% in type I, 50%, 100% and 100% in type II, III, IV respectively. After antituberculous chemotherapy, sputum negative conversion was seen in 14 of 15 cases with type I NTM, 6 of 23 with type III and 14 of 54 with type IV, while definite data in 4 cases with type II were not available.

CONCLUSIONS

NTM pulmonary disease is characterized by long course of disease, nonspecific symptoms, high resistance rate and unsatisfactory therapeutic efficacy.

[Photorefractive keratectomy to correct myopic astigmatism]

The VISX 20/20 excimer laser was used to treat 260 eyes with myopia and myopic astigmatism of 166 patients. All patients were followed up for one year. The diopter of preoperative astigmatism was from -0.25-(- 4.00 D (-1.00 +/- 0.62 D). The diopter was lowered to -0.07 +/- 0.40 D at 6 months postoperatively (P < 0.05) and -0.06 +/- 0.39 D at 12 months postoperatively (P < 0.01). Photorefractive keratectomy (PRK) is effective and safe for myopic astigmatism.

[One-year-result of excimer laser for photorefractive keratectomy in very high myopia]

We corrected 53 cases (84 eyes) of very high myopia using photorefractive keratectomy (PRK) with VISX 20/20 excimer laser, and followed up the cases more than one year. The rates of visual acuity more than or equal to 0.5 or 1.0 were 81.0% and 23.9%, 75.0% eyes were within +/- 2.00 diopter of the desired emmetropia. Grade 2 or more severe corneal haze were presented in 13.1% eyes. PRK with VISX 20/20 excimer laser may be an effective method to correct very high myopia from -10.00 to -16.00 diopters.

[A clinical study on vaccine of Mycobacterium vaccae in treating pulmonary tuberculosis]

OBJECTIVE

To study the effect of vaccine of Mycobacterium vaccae on cell-mediated immunity and on treating patients with pulmonary tuberculosis.

METHODS

Seventy cases of pulmonary tuberculosis with smear positive and initial treatment were classified randomly into group I (35 cases) and group II (35 cases), receiving 2HRZS/4HR and 2HRZS/4HR plus vaccine of Mycobacterium vaccae regimens respectively. Thirty-one multi-drug resistant pulmonary tuberculosis cases were classified into group III, receiving 4 - 6 sensitive antituberculous drugs and vaccine of Mycobacterium vaccae. Improvement of clinical symptoms, resolution of pulmonary lesions, negative conversion of sputum and changes of immunological functions were observed.

RESULTS

No significant difference in improvement of symptoms was found in group I and group II (P > 0.05), and the improvement rate of clinical symptoms in group III was found more than 50%. X-ray resolution rates in 4th month were 83% and 89%, and cavity reducing rates 40% and 50% respectively in group I and group II, and no significant differences were found (P > 0.05). X-ray resolution rate was 29%, cavity reducing rate 7% and no deteriorated case was found in group III. Sputum negative conversion rates in 1st, 2nd, 3rd and 4th month were 23%, 51%, 83% and 97% respectively in group I, while 31%, 77%, 89% and 100% in group II, and 3%, 16%, 29% and 32% in group III. Significant difference was found between group I and group II in sputum negative conversion rate in 2nd month after treatment (P < 0.05). After treatment, values of lymphocyte transformation test (LTT), CD(3), CD(4) and CD(4)/CD(8) of the above 3 groups were all higher than that before the treatment (P < 0.05), level of tumor necrosis factor decreased in group II and IL-2, IL-6 increased in group III.

CONCLUSIONS

Vaccine of Mycobacterium vaccae is a good immunotherapy preparation, which promotes sputum negative conversion and activation of cell-mediated immunity.

[Immunophenotype and P-glycoprotein expression in CD7 positive adult acute myeloid leukemia]

OBJECTIVE

To study the immunophenotype and P-glycoprotein expression in CD7 positive adult acute myeloid leukemia (CD7+ AML).

METHODS

Morphology, P-glycoprotein, cytogenetics and immunophenotype were examined in 30 previously untreated CD7+ AML patients.

RESULTS

The CD7 positive rate was 11.4% in 262 AML patients. CD7+ AML patients had a significantly higher incidence of peripheral leukocytosis and blasts and FAB M1 subtype and were associated with CD34 and P-glycoprotein expression. 42.3% of CD7+ AML achieved complete remission with a median remission duration of 4 months, and a median time to CR of 48 days.

CONCLUSION

Patients with CD7+ AML are usually CD34 and P-glycoprotein positive. These patients had a lower CR rate and a shorter remission duration.

[The clinical and biological significance of megakaryocytic antigen expression in acute myeloid leukemia]

OBJECTIVE

To explore megakaryocytic (MK) antigen expression in previously untreated adult acute myeloid leukemia (AML) and its relation to the clinical and biological characteristics.

METHODS

Two hundred and eleven cases of AML were detected with flow cytometric immunofluorescence assay.

RESULTS

Twenty-seven cases (12.8%) were MK antigen positive with the higher positive rates in hybrid acute leukemia (45.5%) and acute monoblastic leukemia (24.1%). MK antigen expression was significantly correlated with CD34 antigen expression, high white cell count, high P-glycoprotein positivity and had no correlation with chromosome aberration. 33.3% of MK positive AML patients achieved complete remission which was significantly lower than that (71.9%) in MK negative cases.

CONCLUSION

MK antigen positive AML might derived from malignant transformation of hemotopoietic stem cell at earlier stage and the detection of MK expression was of values in predicting treatment effect and prognosis for adult AML.

Protein structure prediction in a 210-type lattice model: parameter optimization in the genetic algorithm using orthogonal array

We have applied the orthogonal array method to optimize the parameters in the genetic algorithm of the protein folding problem. Our study employed a 210-type lattice model to describe proteins, where the orientation of a residue relative to its neighboring residue is described by two angles. The statistical analysis and graphic representation show that the two angles characterize protein conformations effectively. Our energy function includes a repulsive energy, an energy for the secondary structure preference, and a pairwise contact potential. We used orthogonal array to optimize the parameters of the population, mating factor, mutation factor, and selection factor in the genetic algorithm. By designing an orthogonal set of trials with representative combinations of these parameters, we efficiently determined the optimal set of parameters through a hierarchical search. The optimal parameters were obtained from the protein crambin and applied to the structure prediction of cytochrome B562. The results indicate that the genetic algorithm with the optimal parameters reduces the computing time to reach a converged energy compared to nonoptimal parameters. It also has less chance to be trapped in a local energy minimum, and predicts a protein structure which is closer to the experimental one. Our method may also be applicable to many other optimization problems in computational biology.

Inhibition of adipose differentiation by phosphatidylinositol 3-kinase inhibitors

Phosphatidylinositol (PI) 3-kinase plays an important role in various cellular signaling mechanisms in several cell systems. The role of PI 3-kinase in adipose differentiation was investigated. For this purpose, we examined the effect of specific inhibitors of PI 3-kinase on the differentiation of two adipogenic cell lines, 1246 and 3T3-L1. The results show that two structurally different inhibitors of PI 3-kinase, i.e., LY294002 and wortmannin, blocked adipose differentiation in a time and dose-dependent fashion. The results from time- course studies indicated that PI 3-kinase activity is most important in the early phase (day 4 to day 6) of the differentiation program. The effect of PI 3-kinase inhibitor on the expression of the peroxisome proliferator-activated receptor (PPAR) gamma, a master regulator in adipogenesis induced during the differentiation process, was also examined. LY294002 significantly inhibited the induction of PPARgamma mRNA expression. During the initiation phase of adipogenesis (day 4 to day 6), the expression of PPARgamma was induced and LY294002 blocked the increase of expression of PPARgamma mRNA. The inhibition of expression of PPARgamma may provide a molecular mechanism for the action of PI 3-kinase inhibitors on adipose differentiation.

[Multiple factors analysis of formation of corneal haze after photorefractive keratectomy]

VISX 20/20 excimer laser was used to correct myopia from 1.00 to 16.00 diopters on 529 myopia eyes in 306 patients. All the patients were followed up for 3 to 12 months (8.1 +/- 3.1 months). At the 12th postoperative month, 0.5-3 grade corneal haze occurred in 62.1% of eyes in high myopia eyes, and only 8.8% in low and moderate myopia eyes (P < 0.01). The factors of formation of the corneal haze were the central corneal thickness, methods of removing epithelium and the number of laser pulses. The results suggest that the photorefractive keratectomy is regarded safe in correction of low and moderate myopia, but not in high myopia.

[The clinical effect after locally using mitomycin C during trabeculectomy in glaucoma]

To improve the function of filtering blebs after trabeculectomy, we divided randomly 44 patients (60 eyes) with moderate or late glaucoma into mitomycin C and control groups (30 eyes per group). Two small surgical sponges were soaked with 0.2 mg.ml-1 mitomycin C solution. One sponge was put on the top of the superficial scleral flap, the other was placed underneath the scleral flap and contacted with the bed of the scleral flap. After 5 minutes the wound was then irrigated with normal saline. All patients were followed up from 1 to 12 months (7.9 +/- 4.0 months). We found that: (1) functional filtering blebs were 92.9% in the mitomycin C group and 55.2% in the control group (P < 0.01), (2) the decreasing percentage of intraocular pressure (IOP) in the mitomycin C group was much more than that in the control group (P < 0.05), (3) the successful rates of the operation in MMC group were higher than that of the control group, and the visual field was effectively maintained in MMC group.

[Mitomycin C concentrations in rabbit ocular tissues after topical administration during glaucoma filtration surgery]

Using high-performance liquid chromatography, we measured Mitomycin C (MMC) concentrations in conjunctiva, sclera and aqueous of 22 rabbit eyes after single topical administration of 0.2 mg.ml-1 MMC during glaucoma filtration surgery. The peaks of MMC concentrations in conjunctiva, sclera, aqueous were 2.01 micrograms.g-1, 2.95 micrograms.g-1 and 0.16 microgram.ml-1 with half life of 0.63, 0.35 and 0.84 hours respectively. Irrigating the ocular surface with 20 ml of normal saline after MMC application reduced the peak drug concentration to 1/8 in conjunctiva, to 1/5 in sclera and to 1/3 in aqueous. The results showed that the MMC concentrations in conjunctiva and sclera were well above the ID50 of rabbit subconjunctival fibroblast (0.1 microgram.ml-1), and the concentration in aqueous was well below the level known to cause endothelium toxicity (approximately 0.2 mg.ml-1) and retinal toxicity (> 1.3 micrograms.ml-1). Therefore, 0.2 mg.ml-1 MMC can inhibit subconjunctival fibroblast effectively and has no side effect on visual function.

A gas chromatographic method for the sugar analysis of 3,6-anhydrogalactose-containing algal galactans

This paper describes a new gas chromatographic method for the compositional analysis of algal galactans containing 3,6-anhydrogalactose, which is readily destroyed in usual acid hydrolysis and methanolysis. Mercaptolysis of galactans was carried out under an anhydrous condition using the newly developed solvent system, an ethanethiolic HCl solution which had been prepared by blowing dry HCl gas into ethanethiol. By heating galactans in 0.5 N HCl/ethanethiol at 60 degrees C for 12 h, component sugars including 3,6-anhydrogalactose were released quantitatively as their diethyl mercaptals. The monosaccharide diethyl mercaptals were trimethylsilylated and analyzed by gas-liquid chromatography. Each component monosaccharide was detected as a single peak since neither anomeric nor structural isomers can be produced by mercaptolysis. Furthermore, the solvent system was improved by the addition of methanol in a ratio (2/1, v/v) of ethanethiol to methanol. Heating of galactans at 60 degrees C in 0.5 N HCl/[ethanethiol:methanol (2/1, v/v)] released more rapidly and quantitatively monosaccharide diethyl mercaptals without any formation of monosaccharide methyl glycosides. The present method was applicable to not only algal galactans but also algal powders.

What amino acid properties affect protein evolution?

We studied 10 protein-coding mitochondrial genes from 19 mammalian species to evaluate the effects of 10 amino acid properties on the evolution of the genetic code, the amino acid composition of proteins, and the pattern of nonsynonymous substitutions. The 10 amino acid properties studied are the chemical composition of the side chain, two polarity measures, hydropathy, isoelectric point, volume, aromaticity, aliphaticity, hydrogenation, and hydroxythiolation. The genetic code appears to have evolved toward minimizing polarity and hydropathy but not the other seven properties. This can be explained by our finding that the presumably primitive amino acids differed much only in polarity and hydropathy, but little in the other properties. Only the chemical composition (C) and isoelectric point (IE) appear to have affected the amino acid composition of the proteins studied, that is, these proteins tend to have more amino acids with typical C and IE values, so that nonsynonymous mutations tend to result in small differences in C and IE. All properties, except for hydroxythiolation, affect the rate of nonsynonymous substitution, with the observed amino acid changes having only small differences in these properties, relative to the spectrum of all possible nonsynonymous mutations.

[Internalization and replication of Edwardsiella tarda in HEp-2 cells]

It is demonstrated that Edwardsiella tarda possesses the ability to invade cultured epithelial HEp-2 cells by both lysis-counting assay and thin-section electron microscopy. Among fifteen strains of E. tarda, 6 strains internalized into HEp-2 cells and located mainly in vesicles. After internalization, the bacteria replicated in the host cells and then released into medium. Pretreatment of the HEp-2 cells with various concentration of cytochalasin D (0.1-5.0 micrograms/ml) or cytochalasin B (2.5-10.0 micrograms/ml) significantly reduced the amount of internalized bacteria in a dose-dependent manner. While pretreatment of HEp-2 cells with 0.25-100 mumol/L colchicine did not show any effect on the invasiveness of E. tarda. This strongly indicates that microfilaments are required for the internalization of E. tarda into HEp-2 cells and that microtubules are not involved in the entrance of E. tarda into HEp-2 cells.

Regulation of mouse colony-stimulating factor-1 gene promoter activity by AP1 and cellular nucleic acid-binding protein

Macrophage colony-stimulating factor (M-CSF; CSF-1) is a member of a complex network of cytokines that regulate monocytic cell development and activity. It is produced in nearly all organs by cell types commonly found in connective tissue, including fibroblasts and monocytes. Whether different cell types share common or have divergent mechanisms for regulating CSF-1 gene expression is not known. To address this question, the identity of cis-acting elements and cognate trans-acting factors was characterized in a region of the CSF-1 promoter known to be more active in monocytes than in fibroblasts. The results of DNase I protection assays performed with fibroblast- or monocyte-derived nuclear extracts revealed a difference in the pattern of DNA-binding proteins. One protected region, common to both fibroblasts and monocytes, spans a putative phorbol ester-responsive element (TRE), and binding to the TRE by AP1 was verified with antibodies directed against c-fos and c-jun family members. Mutational analysis revealed that the TRE is required for CSF-1 gene expression in proliferating fibroblasts and monocytes. Binding of a second putative trans-acting factor, preferentially expressed in fibroblasts, to the region immediately upstream of the TRE was also detected. Screening a mouse expression library with oligonucleotides spanning the putative cis-acting element identified cellular nucleic acid-binding protein (CNBP) as the cognate binding activity, and antiserum to CNBP disrupted the electromobility shift assay complex. Mutational analysis revealed that loss of CNBP binding leads to a decrease in CSF-1 promoter activity in fibroblasts but has no effect on CSF-1 promoter activity in monocytes. Our results demonstrate that control of CSF-1 gene expression in monocytes and fibroblasts is mediated by common and cell type-specific trans-acting factors.

[Effects of polysaccharide of Polygala aureocauda on the immunnity functions of normal mouse]

The effects of polysaccharide of polygala aureocauda on the immunity functions of the normal mouse were researched by the tests of clearing away carbon granules, hemolysin antibodies production and lymphocyte transformation. The results showed that the polysaccharide of polygala aureocauda Dunn. (PADTP) could strengthen the phagocytosis of the single nucleus phagocytes, promote the production of the antibodies, and raise the transformable rate of the lympocytes. That proved the PADTP could strengthen immunity function of the normal mouse.

[Investigation on the epidemiology of Histoplasma capsulatum infection in Nanjing district]

Two hundred and ninety-two permanent or temporary residents in Nanjing district were tested with histoplasmin (Histolyn-CYL, ALK/Berkeley Laboratories, USA) and PPD. Forty-nine (16.78%) subjects reacted to histoplasmin with 5.0-23.0 (9.5 +/- 4.2) mm induration. Positive reaction rate among people without pulmonary diseases (normal group) was 15.10% comparing to 17.74% to patients with pulmonary diseases. Positive reaction to PPD with 5-50 (14.2 +/- 4.7) mm induration was 56.16%, with 59.43% in normal group and 54.30% in patients with pulmonary diseases while 8.90% subjects reacted to both histoplasmin and PPD, 7.88% of the research subjects reacted to histoplasmin but not to PPD. Result suggested that there was herd infection of Histoplasma capsulatum in Nanjing district.

[Appllcation of PYGC and the hierarchical clustering analysis to recognization of viruses]

The pyrolysis gas chromatography of 29 strains nuclear polyhedrosis viruses, 11 strains cytoplasmic polyhedrosis viruses and 16 strains granulosis viruses were performed on a shimadzu GV-9A capillary gas chromatography equipped with a pyrolyser model PYR-2A. The differences among the inclusion bodies of NPV, CPV and GV could clearly be distinguished and also beidentified through analysis of fingerprinting the hierarchical clustering analysis of GC, This procedure has provided a usefel method for the classification and identification of viruses.

Pea polyubiquitin genes: (I) structure and genomic organization

Four polyubiquitin genes, PUB1, PUB2, PUB3 and PUB4, were isolated from a pea (Pisum sativum L. cv Alaska) genomic library and completely sequenced. They represent all of the four polyubiquitin genes of the ubiquitin gene family in pea. The coding regions of the genes contain five or six coding units arranged as tandem repeats. The different coding repeats of the four genes share homologies between 75 and 97%, encoding the same protein of 76 amino acids identical to those from other higher plants. The open reading frames of PUB1, PUB2 and PUB4 terminate in the additional amino acid, phenylalanine (F), and PUB3 terminates in isoleucine (I). The polyubiquitin genes all contain intron sequences ranging from 584 to 1114 bp immediately 5' to the ATG initiation codon of the first coding sequence. Of the four genes, three are associated with long AT-rich (85.4-89.4% A+T) sequences ranging from about 331 to 478 bp at their 5' or 3' ends. The PUB4 gene was found to be linked to a moderate to highly repetitive DNA at its 5' flanking sequence. The greater sequence homology between different genes than among individual repeating units of a gene suggests that the polyubiquitin genes may have arisen by gene duplication of a single gene sequence.

[Prognostic significance of P-glycoprotein expression in acute leukemia in adults]

OBJECTIVE

To explore the prognostic significance of P-glycoprotein (P-gp) expression in previously untreated acute leukemia in adults.

METHODS

P-gp expression in 151 acute myeloblastic leukemia (AML) and 47 acute lymphoblastic leukemia (ALL) was determined by monoclonal antibody UIC2 and flow cytometry.

RESULTS

The rate of complete remission (CR) differed between P-gp+ and P-gp- AML (20.5% vs 78.5%, P < 0.001), but the CR rate did not significantly differ between P-gp+ and P-gp- ALL(66.7% vs 80%, P > 0.05). The six-month relapse rate was significantly higher in P-gp+ group than that of P-gp- group (AML: 66.7% vs 8.7%, P < 0.001; ALL: 50% vs 9.5%, P < 0.05). The median disease-free survival time was shorter in P-gp+ group than in P-gp- group (AML: 5 months vs 13 months; ALL: 4 months vs 13 months).

CONCLUSION

Overexpression of P-gp is a poor prognostic factor in adult acute leukemia and P-gp detection is useful for the prediction of treatment response and early relapse.

[Effect of AHMED valve implantation surgery for the treatment of neovascular glaucoma]

PURPOSE

To evaluate the efficacy of the valve implantation for the treatment of neovascular glaucoma.

METHODS

15 cases (15 eyes) neovascular glaucoma were treated with AHMED valve implantation surgery, and followed up for 6 to 42 months.

RESULTS

The IOP of the cases is lowered from 6.01 +/- 1.28 kPa (1 kPa = 7.5 mmHg) preoperatively to 1.96 +/- 0.68 kPa postoperatively. The success rate was 80.0% (The criteria of success is 0.80 kPa < or = IOP < or = 2.80 kPa and without severe complication that influence the visual acuity). The common postoperative complications included hyphema, shallow anterior chamber.

CONCLUSION

The AHMED valve implantation surgery can lower the IOP, increase the operative success rate and preserve the visual function effectively. It is regarded to be an effective, safe method to treat neovascular glaucoma.

How optimized is the translational machinery in Escherichia coli, Salmonella typhimurium and Saccharomyces cerevisiae?

The optimization of the translational machinery in cells requires the mutual adaptation of codon usage and tRNA concentration, and the adaptation of tRNA concentration to amino acid usage. Two predictions were derived based on a simple deterministic model of translation which assumes that elongation of the peptide chain is rate-limiting. The highest translational efficiency is achieved when the codon recognized by the most abundant tRNA reaches the maximum frequency. For each codon family, the tRNA concentration is optimally adapted to codon usage when the concentration of different tRNA species matches the square-root of the frequency of their corresponding synonymous codons. When tRNA concentration and codon usage are well adapted to each other, the optimal content of all tRNA species carrying the same amino acid should match the square-root of the frequency of the amino acid. These predictions are examined against empirical data from Escherichia coli, Salmonella typhimurium, and Saccharomyces cerevisiae.

[Clinical study on acute respiratory infection caused by chlamydia pneumoniae]

OBJECTIVE

To find out the infected rate and the clinical features of patients with acute respiratory infection caused by chlamydia pneumonia(C. pneumoniae).

METHOD

A prospective study for chlamydia pneumoniae infection was conducted in 110 patients with respiratory tract infection from January to December 1995 in Nanjing. Sputum and throat swab specimens were taken and C. pneumoniae DNA were detected by polymerase chain reaction (PCR) with the HM-1-HR-1 primer pair. At the same time, serum samples were taken and immunoglobulins G and M (IgG and IgM) fractions of antibodies to C. pneumoniae were studied by microimmunofluorescence test.

RESULT

Prevalence of specific IgG was 70% in patients with respiratory tract infection. Seventeen patients (16%) were serologically diagnosed as having recent C. pneumoniae infection and 12 patients (11%) had the positive PCR in sputum and/or swab specimens. The total positive rate was 23% (25/110) combining PCR with serology. Acute infection of C. pneumoniae was common in the patients with asthma (57%), pneumonia (35%), COPD (26%) and bronchitis (25%). The clinical feature between C. pneumonia infection (n = 5) and non-C. pneumonia infection (n = 85) was not significanty different.

CONCLUSION

Data suggest that Chlamydia pneumonia is an important pathogen that causes infections of the human respiratory tract and attention should be drawn to this special illness.

[Cytotoxic effect of mitomycin C on the nonpigmented epithelium of ciliary body in rabbit eyes]

OBJECTIVE

To observe pathomorphological changes of nonpigmented epithelial cells (NECs) of ciliary body after local single application of mitomycin C (MMC) during sclerectomy in rabbit eyes, and to explore cytotoxic effect of MMC on ciliary body.

METHODS

A single five minutes intraoperative exposure to the agent MMC (0.2 mg/ml, 0.1 ml) was used during sclerectomy in rabbit eyes. The treated area was rinsed with 20 ml normal saline. The NECs of ciliary body at the operated area were observed under light microscope and transmission electron microscope on the 7th and 28th day postoperatively.

RESULTS

On the 7th day postoperatively, the NECs were swollen, and the intracellular abundant mitochondria were swollen and vacuolized. String pearls-like membrane-encapsulated vacuoles were present in the intervals of beta-cell membrane of the NECs. On the 28th day postoperatively, these damages were gradually recovered.

CONCLUSIONS

These findings suggest a toxic effect of MMC on the NECs of ciliary body, possibly that can decrease the aqueous production and intraocular pressure, even causing persistent hypotony.

Identification of cell surface binding sites for PC-cell-derived growth factor, PCDGF, (epithelin/granulin precursor) on epithelial cells and fibroblasts

PC cell derived growth factor (PCDGF) is an 88-kDa glycoprotein purified from the culture medium of the highly tumorigenic mouse teratoma-derived cell line PC. PCDGF was shown to stimulate the proliferation of 3T3 fibroblasts and PC cells. Amino acid sequencing of PCDGF indicated its identity to the precursor for the 6-kDa polypeptides epithelins and granulins. In this paper, we investigated the binding of PCDGF to the mink lung epithelial cell line CCL64. Scatchard analysis indicates that 125I-PCDGF binding to CCL64 cells is curvilinear, corresponding to the existence of two classes of binding sites: high affinity binding sites (560 +/- 170 sites/cell) with a Kd1 of 43 +/- 15 pM and low affinity binding sites (16,350 +/- 5900 sites/cell) with a Kd2 of 3.9 +/- 1.9 nM. 125I-PCDGF was chemically crosslinked to cell surface receptors on CCL64 cells with disuccinimidyl suberate. A major crosslinked band of about 190 kDa with radiolabeled PCDGF was detected after SDS-PAGE, suggesting the presence of PCDGF binding sites with molecular weight of about 120 kDa. 125I. PCDGF crosslinking studies indicate the presence of PCDGF binding sites with a molecular weight similar to those of binding sites on CCL64 cells on the surface of two other PCDGF-responsive cell lines, 3T3 fibroblasts and PC cells. These data suggest that the receptors for PCDGF are widely distributed on cells of distinct embryonic origin.

[Detection of oncogenic mutations in sputum and its diagnostic value of lung cancer]

OBJECTIVE

To find a new method to molecular biological detection of lung cancer.

METHOD

The sputum specimens from 96 cases of lung cancer and other lung patients were detected for K-ras and p53 mutations by using polymerase chain reaction(PCR) and restriction fragment length polymorphism and and immunohistochemistry (IHC) techniques.

RESULT

38 out of 62 sputum specimens of lung cancer patients were positive for cytology: Sensitivity was 61%. NPV (negative predictive value) was 59%; p53 was overexpressed in 48 cases: Sensitivity was 77%. NPV was 66%; k-ras was positive in 21 cases: Sensitivity was 34%, NPV 42%; The combination of conventional cytology and molecular screening(k-ras + p53) produced a sensitivity value of 92%(P < 0.05) with an NPV of 84%(P < 0.05); In 24 cases of patients whose cytology of sputum was false negative, 17 were found either p53 or k-ras positive of which 7 patients were identified to be lung cancer in the follow-up study.

CONCLUSION

These results suggest that detection of oncogene mutation in sputum enhanced and added to the diagnostic value of conventional cytology. It is a promising approach to early lung cancer detection and massive screening in terms of its rapidity, economy and simplicity.

The rate heterogeneity of nonsynonymous substitutions in mammalian mitochondrial genes

Substitution rates at the three codon positions (r1, r2, and r3) of mammalian mitochondrial genes are in the order of r3 > r1 > r2, and the rate heterogeneity at the three positions, as measured by the shape parameter of the gamma distribution (alpha 1, alpha 2, and alpha 3), is in the order of alpha 3 > alpha 1 > alpha 2. The causes for the rate heterogeneity at the three codon positions remain unclear and, in particular, there has been no satisfactory explanation for the observation of alpha 1 > alpha 2. I attempted to dissect the causes of rate heterogeneity by studying the pattern of nonsynonymous substitutions with respect to codon positions in 10 mitochondrial genes from 19 mammalian species. Nonsynonymous substitutions involve more different amino acid replacements at the second than at the first codon position, which results in r1 > r2. The difference between r1 and r2 increases with the intensity of purifying selection, and so does the rate heterogeneity in nonsynonymous substitutions among sites at the same codon position. All mitochondrial genes appear to have functionally important and unimportant codons, with the latter having all three codon positions prone to nonsynonymous substitutions. Within the functionally important codons, the second codon position is much more conservative than the codon position. This explains why alpha 1 > alpha 2. The result suggests that overweighting of the second codon position in phylogenetic analysis may be a misguided practice.

Clinical and biological relevance of flow cytometric determination of P-glycoprotein expression in acute non-lymphocytic leukemia

OBJECTIVE

To evaluate the characteristics of P-glycoprotein (P-gp) expression of acute non-lymphocytic leukemia (ANLL) at different status and the prognostic and biological features in ANLL at diagnosis.

METHODS

Monoclonal antibody UIC2 and indirect immunofluorescence assay by flow cytometry were used to determine P-gp expression of 169 patients with ANLL, including 152 previously untreated, 7 refractory and 10 at remission.

RESULTS

P-gp was expressed in 28.9% of the previously untreated ANLL cases and P-gp was lower than that in 71.4% of the refractory cases (P < 0.05). No P-gp expression was found in the patients at remission. For previously untreated AN-LL, P-gp was highly expressed in hybrid acute leukemia (66.7%) and acute monoblastic leukemia (47.4%). P-gp expression was highly associated with surface markers [cluster of differentiation (CD) 34, CD7, CD14, CD42b and CD61] and unfavorable cytogenetic abnormalities. About 23% of P-gp-ANLL obtained complete remission, which was significantly lower than that (76%) in P-gp-cases.

CONCLUSIONS

P-gp expression is higher in refractory ANLL cases than that in cases at diagnosis or at remission. P-gp is an index of poor prognosis in adults with ANLL. P-gp+ ANLL cases have unique clinical and biological characteristics.

Identification of quantitative trait loci controlling levels of radiation-induced thymocyte apoptosis in mice

Thymocyte apoptosis levels are higher in C57BL/6J mice than in C3Hf/Kam mice. Low-dose irradiation increases the numbers of thymocytes undergoing apoptosis, but the strain difference persists. We mapped three loci controlling radiation-induced thymocyte apoptosis levels in F2 intercross progeny of these strains. The strongest association of a genomic region with an apoptosis level occurred in a region of chromosome 11 known to harbor a locus (or loci) important in the pathogenesis of several rodent models of autoimmune disease. Additional loci influencing radiation-induced thymocyte apoptosis were identified on chromosomes 9 and 16. The genetic polymorphisms underlying these loci may have an evolutionary role in fine-tuning the apoptotic response in T cells and may be important in the etiology of lymphoproliferative disorders and autoimmunity.

A novel case of unilateral blepharophimosis syndrome and mental retardation associated with de novo trisomy for chromosome 3q

We have evaluated a 3 2/12 year old girl who presented with unilateral blepharophimosis, ptosis of the eyelid, and mental retardation. Additional dysmorphic features include microcephaly, high, narrow forehead, short stubby fingers, and adduction of the right first toe. Cytogenetic analysis showed an unbalanced karyotype consisting of 46,XX,add(7)(q+) that was de novo in origin. Fluorescence in situ hybridisation (FISH) using microdissected library probe pools from chromosomes 1,2,3,7, and 3q26-qter showed that the additional material on 7q was derived from the distal end of the long arm of chromosome 3. Our results indicate that the patient had an unbalanced translocation, 46,XX,der(7)t(3;7)(q26-qter;q+) which resulted in trisomy for distal 3q. All currently reported cases of BPES (blepharophimosis-ptosis-epicanthus inversus syndrome) with associated cytogenetic abnormalities show interstitial deletions or balanced translocations involving 3q22-q23 or 3p25.3. Our patient shares similar features to BPES, except for the unilateral ptosis and absence of epicanthus inversus. It is possible that our patient has a contiguous gene defect including at least one locus for a type of blepharophimosis, further suggesting that multiple loci exist for eyelid development.

Glutathione S-transferase expression in hepatitis B virus-associated human hepatocellular carcinogenesis

Hepatitis B virus (HBV) and aflatoxin B1 represent the main risk factors for the development of hepatocellular carcinoma (HCC) in areas endemic for liver cancer. The glutathione S-transferases (GSTs) are a family of Phase II detoxification enzymes that catalyze the conjugation of a wide variety of endogenous and exogenous toxins, including aflatoxin B1, with glutathione. This study characterizes the GST isoenzyme composition (alpha, mu, and pi) of both HBV-infected normal hepatic tissues and HCCs. Analysis of matched pairs of hepatic tissue (normal and tumor) from 32 HCC patients indicated that total GST activity was significantly higher in normal tissues than in tumor tissues, although the percentage of samples expressing GST alpha and pi was equivalent. GST mu was detected by Western blot in the normal tissue from 87.5% of the subjects possessing the GST M1 gene but only 28.6% of the corresponding tumor tissues. The GST activity of normal tissue from GST M1 null patients was significantly decreased as compared to that of subjects possessing the GST M1 gene (264.6 and 422.2 nmol/min/mg, respectively; P = 0.005). GST pi appeared to be overexpressed in the normal tissue of GST M1 null patients, a potential compensatory effect. Patients positive for HBV DNA had significantly lower GST activity than those who were HBV negative (302.1 versus 450.0 nmol/min/mg, respectively; P = 0.02). These results suggest that cellular protection within the human liver is compromised by HBV infection and further decreased during hepatocellular tumorigenesis.

[Mutiple factors analysis of the effects of excimer laser photorefractive keratectomy]

PURPOSE

To observe the effect of excimer laser photorefractive keratectomy (PRK) correcting myopia and astigmatism, and to study the related factors.

METHOD

PRK was performed with the aim to correct myopia errors from 1.00 to 16.00 diopters on 529 myopia eyes (306 patients). All eyes were divided into two groups: Group I: -1.00-6.00 D(294 eyes); group II: -6.25-16.00 D(235 eyes). All the patients were followed up for 3 to 12 months.

RESULTS

At postoperative 12 months the rates of uncorrected visual acuity more than or equal to 10/20 or 20/20 were 97.5%, 77.5% in group I, and 80.3%, 32.8% in group II respectively; 92.5% of eyes were within +/- 1.00 diopter of the desired emmetropia in group I, but 42.6% in group II; The influential factors of changes of postoperative diopters was the severity of corneal haze, methods of removing corneal epithelium, intraocular pressure, the central corneal thickness.

CONCLUSION

The excimer laser PRK is regarded to be a very predictable, safe, stable, and effective method to correct myopia up to -6.00 D. Prior to operation, the plan would be disigned according to diopters, ages, corneal thickness intraocular pressure. During operation, the corneal epithelium bad better to be removed by laser.

[The clinical and biological significance of P-glycoprotein expression in acute nonlymphocytic leukemia]

To evaluate the clinical and biological significance of P-glycoprotein (P-gp) expression in adult acute nonlymphocytic leukemia (ANLL), P-gp was detected in 169 patients including 152 previously untreated cases, 7 refractory cases, and 10 cases at remission by using monoclonal antibody UIC2 and flow cytometry. P-gp was expressed in 29% of previously untreated cases, being less than in 71% of the refractory cases. P-gp expression was not found in patients at remission. Morphologically, P-gp expression was high in hybrid acute leukemia (67%) and acute monoblastic leukemia (47%) subtypes. Immunologically, P-gp expression was significantly associated with CD34, CD7, CD14 or CD42b/CD61. Cytogenetically, P-gp expression was highly associated with poor prognosis abnormalities (54%), which was significantly higher than 7% of P-gp expression in good prognosis abnormalities. 23% of P-gp positive previously untreated ANLL (not including M3) achieved complete remission; this was significantly lower than 76% in P-gp negative cases. These suggested that P-gp expression is an index of poor prognosis in adult ANLL and P-gp positive ANLL has unique clinical and biological features.

[Chromosomal abnormalities and their clinical significance in acute lymphoblastic leukemia in adults]

To determine the chromosomal abnormalities and their clinical significance in adult acute lymphoblastic leukemia, karyotypic analyses with R- and/or G-banding were performed in 101 newly diagnosed ALL patients. The results showed that 69 (68.32%) cases had clonal chromosomal abnormalities and specific abnormalities including Philadelphia chromosome (32.67%), t(4;11) (2.97%), t(11;14) (3.96%), abnormalities of 8q24 (2.97%), 6q- (4.96%). Patients with Ph chromosome showed higher leukocyte counts and more frequent hepatosplenomegaly and most of them were L2 and B lineage subtypes. They had lower complete remission (CR) rate, needed longer time to achieve CR and relapsed earlier as compared with patients without Ph chromosome. These suggested that chromosomal abnormalities are very frequent and some specific abnormalities had specific clinical features.

Mutation in the mitochondrial 12S rRNA gene in two families from Mongolia with matrilineal aminoglycoside ototoxicity

Irreversible hearing loss is a catastrophic complication of treatment with aminoglycoside antibiotics such as streptomycin, gentamycin, and kanamycin. Many kindreds showing a matrilineal pattern of inheritance of this trait have been described in China where the widespread use of aminoglycoside antibiotics accounts for approximately 25% of profound deafness in some districts. Because of the characteristic inheritance pattern, mitochondrial DNA (mtDNA) mutations were postulated to be the cause of the deafness in these pedigrees. In 1993 it was shown that an A to G substitution at base pair 1555 of the mitochondrial 12S ribosomal RNA gene was the only mutation common to all the families with aminoglycoside ototoxicity. We ascertained three Mongolian pedigrees from the School for the Deaf and Blind in Ulaanbaatar, all of which contained multiple affected subjects with streptomycin induced deafness in a pattern consistent with matrilineal transmission. Amplified mtDNA, obtained from transformed lymphoblastoid cell lines using previously described primers, showed the A to G point mutation in the 12S rRNA gene in two of the three families by restriction analysis as well as direct sequencing. No other example of this substitution was found among 400 control samples from Mongolians with normal hearing. We have thus confirmed the clinical relevance of the 1555 A to G mitochondrial mutation in the 12S rRNA gene by identifying it in affected subjects with familial aminoglycoside ototoxicity in another ethnic group. In countries where aminoglycosides are widely used, genetic counselling and screening of high risk families before the use of these drugs could have a dramatic effect on the incidence of deafness.

A Case of Malignant Histiocytosis having Polyploid Clones Characterized by an Isochromosome of the Long Arm of Chromosome 17 [i(17q)] and t(9;22) Translocation

We report an interesting case of Malignant Histiocytosis (MH) with polyploid clones characterized by i(17q) and t(9; 22) translocation. A 47-year-old man had lymphadenopthy, splenomegaly and leukopenia at presentation. Bone marrow (BM) cytology showed 10.5% abnormal histiocytes. Karyotypic analyses with R- and G-banding techniques on BM cells revealed complex abnormalities: 88, XXYY, add(2) (p25), -4, -8, -11, i(17q), -21[4]/89, idem, t(9; 22) (q34; q11), +22[26]/46, XY [47], of which, t(9; 22) was confirmed by fluorescence in situ hybridization using a chromosome 22 paint wcp 22+. This patient was treated with interferon-alpha and COP regimen. 10 months later he achieved a complete hematologic and cytogenetic remission (CR). However, relapse occurred one year after achieving CR. At that time, cytogenetic examination showed a new polyploid clone characterized by add(1) (p36), add(2) (p25), -4, -8, t(9; 22), -11, i(17q), -21, +22 in addition to the other two polyploid clones observed previously. RT-PCR indicated that the BCR/ABL transcript (165bp) observed in classic chronic myeloid leukemia, was present, MH with t(9; 22) has not previously been described in the literature. This case may be the first one of MH with t(9; 22), and is likely a secondary event.

[Analysis of season variation of methyleugenol and safrole in Asarum heterotropoides by gas chromatography]

We established a method for quantitative analysis of methyleugenol and safrole in Asarum heterotropoides by GC to study their season variation. The results showed that the content of methyleugenol in the essential oil of the subterranean part of different seasons was 21%-39%, and that for safrole was 17%-33%. In the upterranean part, methyleugenol was 1.4%-9.6%, and safrole was 0.36%-2.1%. It is clear that methyleugenol and safrole are provided mainly by the subterranean part. The quantity of methyleugenol is the richest in the period of sprouting and after-fruiting, and for the safrole content the richest periods are that of sprouting, blooming and after-fruiting. In the case of upterranean part, the richest time is blooming period both for methyleugenol and safrole, and after blooming they decrease gradually.

Maximizing transcription efficiency causes codon usage bias

The rate of protein synthesis depends on both the rate of initiation of translation and the rate of elongation of the peptide chain. The rate of initiation depends on the encountering rate between ribosomes and mRNA; this rate in turn depends on the concentration of ribosomes and mRNA. Thus, patterns of codon usage that increase transcriptional efficiency should increase mRNA concentration, which in turn would increase the initiation rate and the rate of protein synthesis. An optimality model of the transcriptional process is presented with the prediction that the most frequently used ribonucleotide at the third codon sites in mRNA molecules should be the same as the most abundant ribonucleotide at the third codon sites in mRNA molecules should be the same as the most abundant ribonucleotide in the cellular matrix where mRNA is transcribed. This prediction is supported by four kinds of evidence. First, A-ending codons are the most frequently used synonymous codons in mitochondria, where ATP is much more abundant than that of the three other ribonucleotides. Second, A-ending codons are more frequently used in mitochondrial genes than in nuclear genes. Third, protein genes from organisms with a high metabolic rate use more A-ending codons and have higher A content in their introns than those from organisms with a low metabolic rate.

On transition bias in mitochondrial genes of pocket gophers

The relative contribution of mutation and purifying selection to transition bias has not been quantitatively assessed in mitochondrial protein genes. The observed transition/transversion (s/v) ratio is (micros Ps)/(microv Pv), where micros and microv denote mutation rate of transitions and transversions, respectively, and Ps and Pv denote fixation probabilities of transitions and transversions, respectively. Because selection against synonymous transitions can be assumed to be roughly equal to that against synonymous transversions, Ps/Pv approximately 1 at fourfold degenerate sites, so that the s/v ratio at fourfold degenerate sites is approximately micros/microv, which is a measure of mutational contribution to transition bias. Similarly, the s/v ratio at nondegenerate sites is also an estimate of micros/microv if we assume that selection against nonsynonymous transitions is roughly equal to that against nonsynonymous transversions. In two mitochondrial genes, cytochrome oxidase subunit I (COI) and cytochrome b (cyt-b) in pocket gophers, the s/v ratio is about two at nondegenerate and fourfold degenerate sites for both the COI and the cyt-b genes. This implies that mutation contribution to transition bias is relatively small. In contrast, the s/v ratio is much greater at twofold degenerate sites, being 48 for COI and 40 for cyt-b. Given that the micros/microv ratio is about 2, the Ps/Pv ratio at twofold degenerate sites must be on the order of 20 or greater. This suggests a great effect of purifying selection on transition bias in mitochondrial protein genes because transitions are synonymous and transversions are nonsynonymous at twofold degenerate sites in mammalian mitochondrial genes. We also found that nonsynonymous mutations at twofold degenerate sites are more neutral than nonsynonymous mutations at nondegenerate sites, and that the COI gene is subject to stronger purifying selection than is the cyt-b gene. A model is presented to integrate the effect of purifying selection, codon bias, DNA repair and GC content on s/v ratio of protein-coding genes.

[The effect of mitomycin C on activities of carbonic anhydrase and ATPase of the ciliary body epithelium in rabbit]

PURPOSE

Enzymohistochemical methods were performed to observe the effect of mitomycin C(MMC) on the activities of carbonic anhydrase (CA) and ATPase of the ciliary body epithelium in rabbits after using 0.2mg/ml mitomycin C during sclerectomy for the further study on the mechanism of the decrease of intraocular pressure postoperatively.

METHODS

0.2mg/ml mitomycin C was topically applicated during the sclerectomy in rabbit eyes. 7 days postoperatively, Hasson's method and plumbum nitrate's method were used to stain the CA and ATPase of the ciliary body epithelium. The grey value of the enzymes was quantitated by Image Analysor.

RESULTS

MMC inhibited the activities of CA and ATPase of the ciliary body epithelium underlying the site of MMC application, but the difference of enzymatic activities of the region 90 degree apart from the surgical site and that of surgical site in normal saline control group was not statistically obvious (P < 0.05).

CONCLUSIONS

MMC could inhibit the activities of CA and ATPase of ciliary body epithelium, thus leading to the decreased secretion of humor aqueous and the lowerdown of intraocular pressure even persistent hypotony.