Modified nucleotides in Bacillus subtilis tRNA(Trp) hyperexpressed in Escherichia coli

In the present study, modified nucleotides in the B. subtilis tRNA(Trp) cloned and hyperexpressed in E. coli have been identified by TLC and HPLC analyses. The modification patterns of the two isoacceptors of cloned B. subtilis tRNA(Trp) have been compared with those of native tRNA(Trp) from B. subtilis and from E. coli. The modifications of the A73 mutant of B. subtilis tRNA(Trp), which is inactive toward its cognate TrpRS, were also investigated. The results indicate the formation of the modified nucleotides S4U8, Gm18, D20, Cm32, i6A/ms2i6A37, T54 and psi 55 on cloned B. subtilis tRNA(Trp). This modification pattern resembles the pattern of E. coli tRNA(Trp), except that m7G is missing from the cloned tRNA(Trp), probably on account of its short extra loop. In contrast, the pattern departs substantially from that of native B. subtilis tRNA(Trp). Therefore, the cloned B. subtilis tRNA(Trp) has taken on largely the modification pattern of E. coli tRNA(Trp) despite the 26% sequence difference between the two species of tRNA, gaining in particular the Cm32 and Gm18 modifications from the E. coli host. A notable difference between the isoacceptors of the cloned tRNA(Trp) was seen in the extent of modification of A37, which occurred as either the hypomodified i6A or the hypermodified ms2i6A form. Surprisingly, base substitution of guanosine by adenosine at position 73 of the cloned tRNA(Trp) has led to the abolition of the 2'-O-methylation modification of the remote G18 residue.

Identity elements of tRNA(Trp). Identification and evolutionary conservation

In this study, the varying reactivities of Bacillus subtilis tryptophanyl-tRNA synthetase toward prokaryotic, eukaryotic, and halophile tRNAs were employed to define the potential identity elements on tRNA(Trp). On this basis mutagenesis was performed to obtain, through in vivo heterologous expression in Escherichia coli and in vitro transcription with T7 RNA polymerase, mutant B. subtilis tRNA(Trp) for comparison with the wild-type. These comparisons served to establish G73 and the anticodon as major identity elements, and A1-U72, G5-C68, and A9 as minor identity elements. While the tryptophanyl-tRNA synthetase from B. subtilis and E. coli require G73 to function, replacement of G73 by A73 favors the enzyme from yeast. This change points to the variation of the identity elements for the same amino acid among different organisms. The similarity in these elements between B. subtilis and E. coli tryptophanyl-tRNA synthetase, however, suggests that identity elements on tRNA, like the active centers on enzymes, undergo evolutionary change at slower rates than less essential portions of the macromolecule.

On the vascular inotropic action of 1,25-(OH)2 vitamin D3

Previous work from our laboratory showed that injection of 1,25-(OH)2 vitamin D3 (1,25-vitD) into the rat over a 3-day period increases force generating capacity of subsequently isolated resistance arteries. To better understand the mechanism of this vascular inotropic action, we examined the time course of its development and Ca(2+)-associated mechanism of action. Mesenteric resistance arteries were isolated from 12-week-old male spontaneously hypertensive rats (SHR) 6 and 24 h after a single injection and 24 h after three and seven consecutive days of injection of 1,25-vitD (20 ng/100 g) or vehicle. Serum 1,25-vitD was increased nearly threefold at 6 h, but not at later times. Serum total and ionized Ca2+ were not affected at any time point. No changes in contractile force generation were detected at 6 and 24 h, but a significant increase in the active stress response to norepinephrine and arginine vasopressin was observed after both 3 and 7 days of 1,25-vitD treatment. No effect on sensitivity to either agonist was observed at any time point. To determine whether the vascular inotropic effects of 1,25-vitD might translate into changes in blood pressure, 11-week-old male Wistar rats were given daily injections of 1,25-vitD (20 ng/100 g) over a 4-week period, and blood pressure and body weight were measured. While body weight did not differ at any time point in the two groups, systolic blood pressure was elevated in the 1,25-vitD group v control by 7 days, and continued to be elevated over the period of observation.(ABSTRACT TRUNCATED AT 250 WORDS)

Crystallization of Bacillus subtilis tryptophanyl-tRNA synthetase

Tryptophanyl-tRNA synthetase from Bacillus subtilis was overexpressed in Escherichia coli and was purified using column chromatography on DEAE-Sephacel and hydroxyapatite columns. Single crystals of the synthetase were grown by vapor diffusion at 4 degrees C from pH 5.5 solutions of polyethylene glycol 8000 containing magnesium ATP and L-tryptophan. The crystals diffracted to about 4.0 A resolution at -150 degrees C and appeared to belong to the orthorhombic space group P2(1)2(1)2 with unit cell dimensions: a = 143.6 A, b = 111.6 A, c = 50.6 A with one dimer in the asymmetric unit.

Purification of hyperexpressed Bacillus subtilis tRNA(Trp) cloned in Escherichia coli

To study the effects of evolutionary sequence changes on the molecular interactions of tRNA inside the cell, the Bacillus subtilis tRNA(Trp) gene has been cloned into Escherichia coli JM109 under the control of the lac promotor. Hyperexpression of the gene in minimal medium upon induction yielded 28% of total tRNA in the form of B. subtilis tRNA(Trp). The tRNA(Trp) gene product was purified by the use of a single Vydac C4 high-performance liquid chromatography (HPLC) matrix. This experimental system provided a valuable system for the hyperexpression and purification of a heterologous tRNA for studies in vitro. Moreover, because HPLC fractionation of the heterologous tRNA(Trp) gene product yielded multiple peaks, the system made possible an analysis of the molecular mechanisms for the transcriptional modifications of the tRNA(Trp) gene product in vivo.

Antiproliferative and endothelium-dependent vasodilator properties of 1,3-dihydro-3-p-chlorophenyl-7-hydroxy-6-methyl-furo-(3,4c) pyridine hydrochloride (cicletanine)

The vasodilator and antiproliferative actions of 1,3-dihydro-3-p-chlorophenyl-7-hydroxy-6-methyl-furo-(3,4c) pyridine hydrochloride (cicletanine) were studied on mesenteric resistance arteries and cultured mesenteric artery myocytes of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. Cicletanine (20-200 microM) induced relaxation of endothelium-intact mesenteric resistance arteries of SHR and WKY precontracted with norepinephrine. No difference in sensitivity was observed (SHR IC50 = 77 +/- 12 microM vs. 83.3 +/- 7.4 microM for WKY, N.S.). Endothelial denudation of WKY vessels significantly attenuated the relaxing action of cicletanine (IC50 + endo = 83 +/- 7.4 microM vs. IC50 - endo = 135 +/- 9.7 microM; P < .001) and had a similar, but nonsignificant effect on SHR (IC50 + endo = 77 +/- 12 microM vs. IC50 - endo = 117 +/- 14.5 microM; P = .065). Preincubation of endothelium-intact vessels with nitro-L-arginine methyl ester significantly attenuated cicletanine-induced relaxation in WKY, but not SHR vessels; 0.1 mM Ba++ had a similar effect. Preincubation with 3 microM indomethacin was without effect on relaxation of vessels of either strain. Cicletanine (100-1000 microM) inhibited proliferation of cultured superior mesenteric artery muscle cells growing in the presence of either 10% (SHR IC50 = 440 +/- 24 microM vs. 517 +/- 12 microM for WKY; P < .05) or 2% fetal bovine serum. This antiproliferative action was fully reversible, partially inhibited by indomethacin in SHR myocytes and was associated with a decrease in [3H]thymidine uptake in both strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Overexpression and amplification of c-myc and c-Ha-ras oncogenes in pleomorphic salivary adenoma

Twenty-seven samples of pleomorphic salivary adenoma (PSA) were examined for expression and structure of c-myc, c-Ha-ras, c-erbB-2, c-sis oncogenes by RNA dot blot, DNA dot blot and Southern blot hybridization. Eighteen of 25 PSA showed 5.02 +/- 4.74 fold overexpression of c-myc oncogene, 6 of 19 PSA had 4.91 +/- 3.87 fold overexpression of c-Ha-ras oncogene. Two of 16 PSA were found to have overexpression of c-erbB-2 oncogene. In addition, 7 of 10 PSA and 1 of 9 PSA were detected to have c-myc and c-erbB-2 oncogene amplification respectively. However, no rearrangement, amplification or overexpression of c-sis gene was found. We also discussed various clinicopathological parameters of PSA, which however, had no significant correlation with expression of c-myc or c-Ha-ras oncogene. Our results indicate that activation of c-myc, c-Ha-ras and their combination may play an important role in the pathogenesis of PSA.

Properties of hemoglobin and dextran-hemoglobin rightshifted by oxidized inositol tetrakisphosphate

Phytate was digested by wheat bran phytase to yield inositol tetrakisphosphate. Periodate-oxidized inositol tetrakisphosphate (oxyIP4) was coupled by means of reductive alkylation to hemoglobin and the covalent dextran-hemoglobin conjugate to yield the rightshifted (rs) compounds rsHb and rsDxHb, respectively. The variations of the oxygen dissociation curves of these molecules with pH and temperature were compared to those of hemoglobin. The variations with pH were found to be less pronounced for these rightshifted forms. An extensive decrease in the half-saturation oxygen tension was observed, however, with both rsHb and rsDxHb, as in the case of unmodified Hb. Modification of hemoglobin by oxyIP4 at the polyphosphate site was suggested by the lack of a further rightshifting effect of phytate on rsHb, and by the similarity between the difference spectrum of rs-methemoglobin and the difference spectrum induced by the addition of phytate.

Mutational identification of an essential tryptophan in tryptophanyl-tRNA synthetase of Bacillus subtilis

The strongly conserved single tryptophan residue, Trp92, in Bacillus subtilis tryptophanyl-tRNA synthetase has been mutagenized via site direction singly into Gln, Ala, and Phe. All three mutant enzymes were inactive toward the catalysis of tRNA tryptophanylation. The Trp92----Phe mutant has been subcloned into the high expression plasmid pKK223-3 to yield the recombinant plasmid pKSW-F92. Growth of bacteria carrying the latter plasmid made possible the purification of the mutant TrpRS-F92 enzyme to homogeneity. This mutant enzyme was deficient in ultraviolet absorbance and fluorescence relative to the wild type enzyme and inactive in the partial reaction of Trp-activation as well as the overall reaction of tRNA tryptophanylation. Furthermore, unlike the wild type B. subtilis trpS gene, the mutant trpS-F92 gene upon transformation into Escherichia coli trpS 10343 failed to complement the temperature sensitive trpS mutation of the host cells. Trp92 therefore represents an essential residue both in vitro and in vivo for the function of the tryptophanyl-tRNA synthetase.

Pulmonary fat embolism in rabbits induced by forced immobilization

In the study reported here, rabbits were used to develop an experimental model for inducing pulmonary fat embolism by forced immobilization. The emboli were quantitated by a computerized system. The activity of lipoprotein lipase in post-heparin plasma (PHP-LPL) and concentrations of free fatty acids (FFA) were measured. Also, blood gases were analyzed and pulmonary morphology and ultrastructure were observed. Forced immobilization for 5 hours was found to induce pulmonary embolism. This was accompanied by elevation of PHP-LPL and FFA levels in the blood, hypocapnia, and a tendency for insufficiency of pulmonary surfactant. The results suggest that the disorder of homeostasis caused by immobilization is strong enough to bring about pulmonary embolism without bone fracture.

[Screening studies on anti-inflammatory function of traditional Chinese herb Gardenia jasminoides Ellis and its possibility in treating soft tissue injuries in animals]

This paper reports the study of six fractions and one chemical constituent isolated from the traditional Chinese herb Gardenia jasminoides. The results showed that two fractions (G5.G6,), alcohol extract (G1) and genipoiside(A) had obvious anti-inflammatory effects and were comparatively effective in treating soft tissue injuries in animals.

Three New Dibenzocyclooctadiene Lignans from Kadsura longipedunculata

Five dibenzocyclooctadiene lignans were isolated from the stems of KADSURA LONGIPEDUNCULATA collected in Guangxi province. Three of them are new compounds, named benzoyl-, isovaleroyl-, and isobutyroylbinankadsurin A. Binankadsurin A was isolated from nature for the first time. The absolute configuration of isovaleroyloxokadsurane, a spirobenzofuranoid lignan from K. COCCINEA, was confirmed by chemical correlation with isovaleroylbinankadsurin A.

1,25 (OH)2 vitamin D3 attenuates the loss of resistance artery contractile function associated with incubation in culture media

Contractile properties of rat mesenteric resistance arteries were studied immediately after isolation or after 48-hr incubation in culture medium [Dulbecco's modified Eagle's/Ham's F-12 (1:1) with insulin, transferrin and antibiotics]. Incubation in culture medium depressed active stress generating capacity, increased sensitivity to norepinephrine and ablated endothelium-dependent relaxation. The decrease in stress generation results from the loss of a releasable pool of intracellular Ca2+; the enhanced sensitivity is associated with decreased neuronal amine pump function. Addition of 300 pg/ml 1,25 (OH)2 vitamin D3 to the culture medium afforded nearly complete protection against the loss of stress generating capacity and partially preserved endothelial function. It is concluded that 1,25 (OH)2 vitamin D3 partially prevents phenotypic modulation of the vascular myocyte induced by culture conditions.

1,25 (OH)2 vitamin D3-induced 45CA uptake in vascular myocytes cultured from spontaneously hypertensive and normotensive rats

The effect of 1,25 (OH)2 vitamin D3 on basal 45Ca uptake was examined in vascular smooth muscle cells cultured from mesenteric arteries of spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) normotensive rats. Basal uptake of 45Ca was significantly greater in myocytes of WKY than SHR at 5, 10, 30 and 60 min incubation with the isotope. Incubation with 1 ng/ml 1,25 (OH)2 vitamin D3 for 48 hr increased basal 45Ca uptake between 1-10 min in SHR and between 5-10 min in WKY. The dose-response relationship indicated that cells from both strains are equally sensitive to the calciotropic effects of 1,25 (OH)2 vitamin D3 with half-maximal stimulation occurring at approximately 0.3-0.4 ng/ml. In cells of both strains maximal stimulation of 45Ca uptake was achieved only after a 12-24 hr period of incubation with hormone and pretreatment with cycloheximide inhibited 1,25 (OH)2 vitamin D3-enhanced 45Ca uptake. Although 45Ca binding by extracellular matrix material was significantly greater in WKY than SHR, 1,25 (OH)2 vitamin D3 had no effect on the amount of matrix 45Ca binding in either strain. These results suggest that 1,25 (OH)2 vitamin D3 induces an increase in intracellular protein synthesis that results in enhanced 45Ca uptake. The similar responses of the two strains indicate that hypertensive smooth muscle is not more sensitive to 1,25 (OH)2 vitamin D3 and the Ca2+ response is a general property of vascular muscle.

[Observation on propagating experiments with Polygala tenuifolia Willd seed]

This paper reports the harvesting and storing of Polygala tenuifolia seed, the operating process and method of seed propagation both in the laboratory and in the field, the relationship between Palygala tenuifolia seed germination, seed treatment and temperature and humidity, and the importance of suitable conditions and climatic factors in the sexual propagation of the seed.

Mesenteric artery contractile properties during dietary calcium manipulation in spontaneously hypertensive and Wistar Kyoto normotensive rats

The hypothesis that elevated Ca2+ intake lowers blood pressure in the spontaneously hypertensive rat (SHR) by altering intrinsic contractile properties of vascular smooth muscle was tested. The effect of 0.5, 1, and 2% Ca2+ in the diet on systolic blood pressure, serum-ionized Ca2+, and contractile properties of mesenteric arteries isolated from SHR and normotensive Wistar-Kyoto (WKY) rats maintained on diets for 6 and 12 weeks was examined. Blood pressure was significantly elevated in SHR on 0.5% Ca2+ diets after both 6 and 12 weeks, as well as in WKY receiving 1% Ca2+. After six weeks on the diets for the SHR and 6 and 12 weeks for the WKY, serum-ionized Ca2+ was a function of the amount of Ca2+ in the diet. When contractile force generation in response tp KCl or norepinephrine was examined, small diet-related differences were detected, but no consistent linear effect associated with the level of Ca2+ in the diet was observed in either strain. When the sensitivity of the vessels to KCl and norepinephrine was examined, no effects of oral Ca2+ intake were detected. The results indicate that oral Ca2+ loading has modest effects on blood pressure at both 12 and 18 weeks of age in the SHR and WKY and in the younger rat, where Ca2+ intake modulates serum ionized Ca2+ levels. At no age does modification of Ca2+ intake have a consistent effect on mesenteric artery sensitivity or force-generating ability in response to KCl or norepinephrine. These findings do not support the hypothesis that oral Ca2+ loading lowers blood pressure in the rat by altering intrinsic contractile properties of vascular smooth muscle.

Persistence of asymmetry in nonaxisymmetric entry flow in a circular cylindrical tube and its relevance to arterial pulse wave diagnosis

In an experiment motivated by the study of arterial blood flow along the lines suggested by the traditional Chinese medicine, the flow in a pipe whose lumen was blocked by a semi-circular plug two tube-diameters long was visualized by suspended particles, recorded by cinematography, and analyzed digitally. The Reynolds number was in the range of 100 to 450 based on the pipe diameter, similar to that of blood flow in the radial artery in the arms of man. The blockage was found to have a profound effect on the velocity profile of the flow in the wake, but it had little influence on the symmetry of the velocity profile upstream of the block, except in its immediate neighborhood. When the end conditions far away from the block were steady, the flow in the wake was steady. The asymmetry of the flow in the wake can be judged by the deviation of the location of the maximum axial velocity from the center line of the pipe as seen in the plane of symmetry of the blockage. Our results show that the deviation can be described as the sum of two components. The first is a strong one which decays exponentially in an entry length which is about twice as long as the classical Boussinesq entry length of axisymmetric flow. The second is a weaker component which is wavy spatially and persists far downstream (many times the entry length). The separated flow and vortex system behind the blockage are sensitive to the flow rate.(ABSTRACT TRUNCATED AT 250 WORDS)

What Nei Jing and Mai Jing say about arterial pulse waves and our attempt to illustrate some of their statements

A rich group of fluid mechanical problems are suggested in the classical Chinese books Nei Jing and Mai Jing. In this article the methods of pulse wave palpation described in these books are briefly explained, and an attempt to understand some of their statements is presented.

Effect of 1,25(OH)2 vitamin D3 and ionized Ca2+ on 45Ca uptake by primary cultures of aortic myocytes of spontaneously hypertensive and Wistar Kyoto normotensive rats

The effect of several regulators of whole animal Ca2+ homeostasis on 45Ca uptake by primary cultures of aortic myocytes isolated from spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats was examined. Exposure of confluent cells to 1.0, 1.25 or 1.50 mM ionized Ca2+ in serum-free medium for seven days resulted in increased 45Ca uptake at the higher concentrations of Ca2+ in cells of the SHR but not the WKY. 1,25 (OH)2 vitamin D3 (1 ng/ml) for 7 days caused enhanced influx in cells from both the SHR and WKY while parathyroid hormone (1-34) (1 ng/ml) was without effect. The data indicate that humoral factors that serve to regulate whole animal Ca2+ homeostasis may also play a role in the regulation of Ca2+ metabolism of the vascular smooth muscle cell.

Induction of contraction in isolated rat aorta by cyclosporine

Cyclosporine (CsA) is a new immunosuppressive agent that has adverse effects of nephrotoxicity and de novo appearance of hypertension. It has been hypothesized that the mechanism of the contrary effects is through an action of CsA on vascular smooth muscle. To test this hypothesis, thoracic aortas were isolated from Wistar Kyoto rats and ring segments prepared for measurement of tension. CsA (5 X 10(-6) M) induced a slow increase in tone of the isolated rings with a response at 3 hr of 0.70 +/- 0.17 N/m2 X 10(4). This contraction was significantly inhibited by the Ca2+ channel blocker verapamil (0.30 +/- 0.08 N/m2 X 10(4) after 3 hr, P less than 0.05) and by the noncompetitive alpha-antagonist phenoxybenzamine (0.06 +/- 0.07 N/m2 X 10(4) after 3 hr, P less than 0.05). The competitive alpha-antagonist phentolamine had mixed effects. CsA does not irreversibly alter vascular smooth muscle contractile ability since a 3 hr exposure to the agent had no effect on either the maximal contractile response or sensitivity to KCl. We conclude that CsA can directly induce contraction in vascular smooth muscle, perhaps by inducing a release of norepinephrine from adrenergic nerve terminals. The data are consistent with the hypothesis that CsA induces nephrotoxicity and de novo hypertension through a contractile effect on vascular smooth muscle.