Transformation of Erwinia chrysanthemi by Escherichia coli plasmids DNA

We have demonstrated in this study that CaCl2-MnCl2 treatment is effective in the preparation of competent cells of Erwinia chrysanthemi for transformation. Plasmids pMB9 and pBR322, which are of Escherichia coli origins, were transformed into E. chrysanthemi at frequencies of 1.5 X 10(-7) and 4.5 X 10(-7) per recipient, respectively. The frequencies were 60- to 80-fold lower than those in the well established rec- E. coli; however, the procedure is practically useful in transformation experiments. The plasmids were maintained rather stable in the cells if antibiotics were included in the media. When transformed by pECl and pEC6, which were chimeric plasmids consisting of pBR322 and an E. chrysanthemi chromosomal DNA fragment of 2.4 and 3.5 Mdal, respectively, the transformation frequencies of E. chrysanthemi were at the same range of that by pBR322. Neither colony morphology nor the polypectate degradation ability was changed after transformation by the plasmids. In conclusion, we have established a system of molecular cloning in E. chrysanthemi SR120A exploiting pBR322 as a vector.

Estimation of human body composition by electrical impedance methods: a comparative study

This study 1) further validated the relationship between total body electrical conductivity (TOBEC) and densitometrically determined lean body mass (LBMd) and 2) compared with existing body composition techniques (densitometry, total body water, total body potassium, and anthropometry) two new electrical methods for the estimation of LBM: TOBEC, a uniform current induction method, and bioelectrical impedance analysis (BIA), a localized current injection method. In a sample of 75 male and female subjects ranging from 4.9 to 54.9% body fat the correlation between LBMd and LBM predicted from TOBEC by use of a previously developed regression equation was extremely strong (r = 0.962), thus confirming the validity of the TOBEC method. LBM predicted from BIA by use of prediction equations provided with the instrument also correlated with LBMd (r = 0.912) but overestimated LBM compared with LBMd in obese subjects. However, no such systematic error was apparent when new prediction equations derived from this heterogeneous sample of subjects were applied. Thus the TOBEC and BIA methods, which are based on the differing electrical properties of lean tissue and fat and which are convenient, rapid, and safe, correlate well with more cumbersome human body composition techniques.

The Cancellation of Magnetic Flux. I. On the Quiet Sun

We studied the disappearance of magnetic flux in an area of the quiet Sun from digital and photographic magnetograms recorded at 2�5 min intervals for many hours on 9 July 1984 at the Big Bear Solar Observatory. We limited the quantitative part of the analyses to features which had a total of 1017 Mx (1 Mx "'" 10-8 Wb) or greater and at least a 20 G (1 G"", 10-4 T) contour, and which changed by more than 10% of the maximum measured flux during the 5�5 hours of most consistent image quality during the observing day. Sixteen examples of flux disappearance and three ephemeral regions met these criteria. The disappearance of flux in these examples occurred only in closely spaced features of opposite polarity. The mutual disappearance of magnetic flux in closely spaced features of opposite polarity is herein defined as 'cancellation'. The 16 examples of cancellation were observed in combinations of network features, intranetwork features, and ephemeral regions. In two of the three ephemeral regions, an imbalance of magnetic flux between the two poles within each of the ephemeral regions was created, at least in part, by the cancellation of one pole with an adjacent feature of opposite polarity. Many smaller cancellation are clearly recognized below the threshold that we established for our initial measurements. We conclude that cancellation is the dominant way in which magnetic flux is observed to disappear on the quiet Sun.

The Cancellation of Magnetic Flux. II. In a Decaying Active Region

An active region was studied in detail during its period of decay from 3 to 8 August 1984 using Ha filtergrams and videomagnetograms acquired at the Big Bear Solar Observatory. The decay was initiated by a process of fragmentation in which very small knots of magnetic flux separated from larger concentrations of flux. The fragmentation was observed at discrete locations around the periphery of both the dominant areas of negative and positive field, but possibly occurred more frequently in the main polarity inversion zone. The fragmentation and migration of knots of magnetic flux were common predecessors to the disappearance of flux.

Mycoplasma pneumoniae-induced hydrocephalus in hamsters

Hydrocephalus was induced in neonatal hamsters after intracerebral inoculation of Mycoplasma pneumoniae. Examination of the ependyma from affected animals by electron microscopy did not reveal mycoplasma. However, in an ependymal organ culture system, M. pneumoniae cytadsorbed to ependymal cells.

Toxic effects of the antifertility agent gossypol in male rats

In the present investigation the influence of gossypol on the male sex function and toxicology in the rat have been studied. Gossypol was injected daily for 5 weeks to adult male rats of the Sprague-Dawley strain with 1 or 10 mg/kg body wt. The low dose of gossypol (1 mg/kg body wt.) did not have any effect on the following parameters: plasma testosterone concentrations, body growth, kidney weights, sex organ weights (ventral prostate, seminal vesicle, epididymis), testicular weights, blood flow to testes, epididymides and ventral prostate as measured with the microsphere technique, intraarterial blood pressure and morphology of testis and epididymis. The plasma testosterone response to acute LH-injection was not significantly different in gossypol-treated rats when compared to control rats. The high dose of gossypol (10 mg/kg body wt) caused signs of tubular degeneration, retarded body growth, markedly reduced testosterone concentrations, involutions of the ventral prostate and seminal vesicles and gastrointestinal disturbances. After 5 weeks of treatment the mortality rate was 13%. It is concluded that gossypol is a very toxic substance in rats, since only a 10-fold increase of a non-effective dose caused serious side effects in addition to its antifertility effects.

Biologic functions of the OKT1 T cell surface antigen. I. The T1 molecule is involved in helper function

The OKT1 (Leu-1) monoclonal antibody reacts with a 69 KD glycoprotein that is present on only a fraction of functionally mature thymocytes but is maintained on most peripheral T cells. In the study presented, we examined the role of this surface molecule in T cell function. We found that addition of the OKT1 antibody to B cells and autologous T4+ cells markedly enhances B cell differentiation. This enhancement was apparent when nonirradiated or irradiated T4+ cells but not T8+ cells were used. Moreover, the OKT1 antibody as well as the OKT1 F(ab')2 fragment enhanced B cell differentiation in a dose-dependent fashion. It is important to note that perturbation of the T1 molecule with OKT1 in the presence of autologous E- cells causes the rapid release of molecules that trigger B cells to proliferate and differentiate into Ig-secreting cells. These data when considered together suggest that OKT1 reacts with a T cell membrane determinant or a complex that is intimately involved in the execution of helper function on OKT4+ cells.

Biologic functions of the OKT1 T cell surface antigen. I. The T1 molecule is involved in helper function

The OKT1 (Leu-1) monoclonal antibody reacts with a 69 KD glycoprotein that is present on only a fraction of functionally mature thymocytes but is maintained on most peripheral T cells. In the study presented, we examined the role of this surface molecule in T cell function. We found that addition of the OKT1 antibody to B cells and autologous T4+ cells markedly enhances B cell differentiation. This enhancement was apparent when nonirradiated or irradiated T4+ cells but not T8+ cells were used. Moreover, the OKT1 antibody as well as the OKT1 F(ab')2 fragment enhanced B cell differentiation in a dose-dependent fashion. It is important to note that perturbation of the T1 molecule with OKT1 in the presence of autologous E- cells causes the rapid release of molecules that trigger B cells to proliferate and differentiate into Ig-secreting cells. These data when considered together suggest that OKT1 reacts with a T cell membrane determinant or a complex that is intimately involved in the execution of helper function on OKT4+ cells.

The T4 surface antigen is involved in the induction of helper function

The OKT4 monoclonal antibody reacts with a 62K m.w. glycoprotein present on a subset of human T cells with the capacity to help or induce B cell differentiation. The present studies were undertaken to determine whether the T4 molecule itself plays any role in the helper function mediated by T4+ cells. Using a series of monoclonal antibodies (OKT4, OKT4A-E), which react with distinct noncompeting epitopes of the T4 molecule, we found that OKT4A and OKT4E, but not OKT4, antibodies inhibited the induction of B cell differentiation by T4+ cells. This inhibition was apparent when using nonirradiated or irradiated T4+ cells, and was noted over a wide range of concentrations. Importantly, inhibition occurred only if the antibody was present during the first 24 hr of cell culture, and the presence of antibody did not alter the kinetics of induction of B cell differentiation. Thus, these data suggest that the T4 molecule plays an early, critical role in cellular interactions required for helper cell function.

Body potassium by four-pi 40K counting: an anthropometric correction

Four-pi whole body counting for the 1.46 meV photon of 40K has apparent advantages over single-crystal or two-pi counters in efficiency and in subject geometry independence. However, our studies of obese populations have disclosed a systematic undermeasurement of 40K, suggesting that nonhomogeneous K distribution results in systematic undercounting of 40K. In the current study 42K, emitting a 1.52 meV photon, was used in 109 volunteers ranging from 50 to 181 kg, and multiregression covariance analysis was applied to develop correction formulas based on anthropometrics. These corrections quantitatively account for the unappreciated loss of 40K and 42K photons in annular adipose tissue that surrounds the lean body, in which most K+ is concentrated. The correction ranges from 1 to 28% and is a linear (although different) function of weight in both sexes. Thus corrected, body potassium measurements, taken in conjunction with exchangeable sodium and water measurements, provide estimates for whole body osmolality that match measured serum values. Such a quantitative accounting for previously "lost" cation in 58 subjects provides independent evidence for the appropriateness and accuracy of the correction. With this correction, body potassium was recalculated in the 1,492 adult members of a previously reported group of 3,083 subjects.

The T4 surface antigen is involved in the induction of helper function

The OKT4 monoclonal antibody reacts with a 62K m.w. glycoprotein present on a subset of human T cells with the capacity to help or induce B cell differentiation. The present studies were undertaken to determine whether the T4 molecule itself plays any role in the helper function mediated by T4+ cells. Using a series of monoclonal antibodies (OKT4, OKT4A-E), which react with distinct noncompeting epitopes of the T4 molecule, we found that OKT4A and OKT4E, but not OKT4, antibodies inhibited the induction of B cell differentiation by T4+ cells. This inhibition was apparent when using nonirradiated or irradiated T4+ cells, and was noted over a wide range of concentrations. Importantly, inhibition occurred only if the antibody was present during the first 24 hr of cell culture, and the presence of antibody did not alter the kinetics of induction of B cell differentiation. Thus, these data suggest that the T4 molecule plays an early, critical role in cellular interactions required for helper cell function.

Changes in testicular blood flow and testosterone production during aspermatogenesis after irradiation

Exposure of the testes of anaesthetized adult rats to 527 rads of gamma-irradiation caused testis weight to fall slowly at first and then more rapidly from 21 days afterwards, reaching a minimum at 52 days, when spermatogenesis was severely disrupted. The weights of the accessory organs and the concentrations of testosterone in peripheral blood were slightly reduced; the concentrations in blood from the testicular veins were lower than control at shorter intervals after irradiation, but at later times tended to be similar or greater than control. Testicular blood flow per testis followed testis weight closely, and as a result the production of testosterone by the smaller testes (calculated as the product of plasma flow and the veno-arterial difference in testosterone concentration) was markedly reduced especially when the rats had been stimulated with human chorionic gonadotrophin (hCG). Serum FSH and LH rose appreciably as testis weight fell but there was a proportionately greater rise in FSH than LH, in comparison with surgically castrated animals. Increased amounts of extratubular, extracellular fluid were found in the aspermatogenic testes, but injection of hCG still caused increases in capillary permeability and the amount of fluid in the testis. These results indicate that during aspermatogenesis following irradiation (as with heat and efferent duct ligation) the capacity of the testes to secrete testosterone is severely limited by decreased testicular blood flow, not by the ability of the Leydig cells to release testosterone into their immediate environment.

Measurement of total body electrical conductivity: a new method for estimation of body composition

A new method for the estimation of body composition in human subjects is described which entails the measurement of total body electrical conductivity. The method is based on the principle that the electrical conductivity of lean tissue is far greater than that of fat. Comparative studies in 19 adults of widely varying fatness have demonstrated excellent correlations between the total electrical conductivity of the subjects and both their total body water (r = 0.87) and total body potassium (r = 0.86). This noninvasive method, which is safe, simple, rapid, and convenient, should prove useful in the nutritional assessment of individuals and populations.

Prediction of the resting metabolic rate in obese patients

Resting metabolic rate (RMR) was measured in 154 women and 48 men before the beginning of a weight reduction program. In both sexes there were significant univariate correlations between RMR and fat-free mass, body fat, weight, fat cell weight, and fat cell number (from total body water). Women also showed significant correlations between RMR and fat cell number (from total body potassium), free triiodothyronine index, and fasting and postglucose insulin levels. Multiple regression analysis showed that both fat-free mass and fat cell weight and number were significant predictors of RMR. The contribution of fat-free mass was three to five times greater per kg than that of body fat. There was no significant contribution of thyroid hormones or insulin to the prediction of RMR. Fat cell number and fat cell weight were significant predictors of RMR, whether determined from body water, body potassium, or a formula using both water and potassium. There was no significant difference in regression coefficients between men and women. Thus the difference in RMR between the sexes is probably caused by the higher proportion of fat-free mass in men. The effect of age was small and not statistically significant.

X-ray diffraction study of the zinc(II) binding sites in yeast phenylalanine transfer RNA. Preferential binding of zinc to guanines in purine-purine sequences

An X-ray diffraction study of a zinc(II) complex of tRNAPhe from yeast reveals the present of five zinc-binding sites on the tRNA molecule. Two of the cooperatively bound Mg2+ in the native tRNA structure are replaced by Zn2+. The remaining sites involve direct coordination of zinc to the N7 position of tRNA guanine bases, G15, G43 and HG45. Thus, zinc displays a high specificity for binding to guanine bases in purine-purine sequences.

Triplet anisotropy decay measurements of DNA internal motion

Triplet anisotropy decay techniques have been used to measure the internal flexibility and overall rotational motions of DNA over a time range of 15 ns to 200 microseconds. Nearly monodisperse DNA fragments with lengths varying from 65 to 600 base pairs were studied using the intercalating dye methylene blue as a triplet probe. The slow end-over-end tumbling of short DNA fragments (less than 165 base pairs) is as predicted for a rigid rod. As expected, a longer DNA fragment (600 base pairs) experiences slow segmental motions of its helix axis. At the earliest times, anisotropy decays more rapidly than expected for a rigid rod, suggesting that, when it is bound, methylene blue monitors fast internal motions of the helix. Since the rod-like end-over-end tumbling rules out fast bending motions (for short DNA fragments), the fast components of DNA anisotropy decay must be due to twisting motions of the helix, occurring with a time constant near 50 ns. The same techniques were used to measure the conformational flexibility of DNA in the nucleosome. It is concluded that, when the DNA helix is wrapped to form a nucleosome, it experiences substantial internal flexibility, occurring with a time constant near 30 ns. The amplitude and time-scale of this motion appear to be similar to that seen in the uncomplexed DNA helix.

DNA motions in the nucleosome core particle

We have used time-resolved triplet state anisotropy decay techniques to measure the conformational flexibility of DNA in the nucleosome. From these measurements we conclude that, in a nucleosome, the DNA helix experiences substantial internal flexibility, which occurs with a time constant near 30 nsec. We find that our data can be fit well by a modified version of the Barkley-Zimm model for DNA motion, allowing only DNA twisting motions and the overall tumbling of the nucleosome. That fit yields a calculated torsional rigidity equal to 1.8 X 10(-19) erg X cm, a value equal to that measured for uncomplexed DNA. We conclude from such similarity that large, fast twisting motions of the DNA helix persist, nearly unaltered, when DNA is wrapped to form a nucleosome.

Isolation and properties of L-amino acid oxidase from Ophiophagus hannah venom

This paper reports the isolation and some properties of L-amino acid oxidase from Ophiophagus hannah venom. The differences between L-amino acid oxidase from Ophiophagus hannah and that from other sources in specific activity, properties and the spectrum of isozymes are noticeable. The result of electrophoresis on polyacrylamide gel shows that this purified enzyme is homogenous. The molecular weight determined by gradient polyacrylamide gel slab (4--30%) is around 15 X 10(4) dalton. The molecular weight of the subunit determined by SDS gradient gel electrophoresis (4--30%) is around 7.3 X 10(4) dalton. Therefore, this enzyme is composed of two subunits. The absorption spectrum reveals that there are two FADs in each molecule. The optimum pH of enzymic reaction is around 8.7--9.0 when L-leucine is used as substrate. The inhibition of the products is noticeable when substrate concentration goes beyond 3mM. This enzyme is heat stable and its activity would not decrease obviously after heating at 55 degrees C for 40 min. A linear relationship between enzyme concentration and reaction rate was noticed when enzyme concentration was below 5.7 micrograms/ml.

Molecular motion of DNA as measured by triplet anisotropy decay

We have used triplet anisotropy decay techniques to measure the internal flexibility and overall rotational motion of DNA, covering a time range from 15 ns to 200 mus. Nearly monodisperse DNA fragments 65--600 base pairs long were studied by using the intercalating dye methylene blue as a triplet probe. We found that the slow end-over-end tumbling of short DNA fragments (less than or equal to 165 base pairs) is as predicted for a rigid rod. As expected, a longer DNA fragment (600 base pairs) experiences slow segmental motion of its helix axis. We found that, at the earliest times, anisotropy decays more rapidly than expected for a rigid rod, suggesting that, when bound, methylene blue monitors fast internal motion of the helix. Since the rod-like end-over-end tumbling of short fragments rules out fast bending motions, we conclude that the fast components of DNA anisotropy decay are due to twisting motion of the helix, occurring with a time constant near 50 ns.

Body composition in affective disorder before, during, and after lithium carbonate therapy

The body composition of three unipolar and 17 bipolar patients, studied during the depressive state, was compared with that of 48 controls. The ratio of extracellular to intracellular water content was significantly less in male patients than in male controls: the difference between female patients and female controls was not statistically significant. In patients of both sexes, residual sodium concentration was greater in patients than in controls. The intracellular content of potassium was the same in patients as in controls. In six patients, body composition was studied prior to lithium carbonate therapy, after 17 days of treatment, and 17 days after discontinuing administration of the drug. The significant changes were a decrease in body weight during therapy, and a decrease in body water content and an increase in residual sodium concentration after drug treatment was discontinued.

Body composition measurements in normal man: the potassium, sodium, sulfate and tritium spaces in 58 adults

The aqueous phase of total body composition varies with sex, and changes with age, necessitating age, sex and method-specific normal values. Consensus has developed for the methods most suited to clinical studies. 3H20 for water, 35SO4 for ECW, 24Na for NAc, and 40K for body potassium were used in 58 normal volunteers aged 19-80, 30 men and 28 women. This report shows significant age regressions in both sexes for total body water and intracellular water, and for both Na and K when referenced to body water. Combination of these findings with the highly age related decrease in total body potassium confirms previous studies that body cell mass decreases with age. Intracellular K+ and Na+ at the zero age intercept are 130 and 14.5 for males, and 124 and 24mEq/1 for females respectively. Secular decrease in K+ and increase in Na+ concentrations in the average cell are suggested although not established. Values for normal body composition, in subjects healthy by all available criteria are in some instances age and sex dependent, but in all parameters except fat show wide normal range (SD = 7% of mean) which derive more from biological variation than from limitations of measurement precision. However, use of body water rather than weight succeeds in narrowing this wide range, and is a more logical denominator which is readily subject to accurate measurement. In serial studies of the same subject, significant changes can be measured which are well within the normal range.