Some Seismic Profiles near the Western End of the Puerto Rico Trench

A cooperative program of seismic refraction profiling was completed in the vicinity of the Puerto Rico Trench by Hudson Laboratories, Woods Hole, Lamont, and Texas A. & M. Profiles completed near the western end of the Trench were analyzed at Hudson Laboratories. Five seismic layers are indicated below the water layer. The thickness/velocity relationships are as follows: 5.1 km of 1.5 km/sec. (water); 1 km of 1.7 km/sec. (sediment); 1.5 km of 3 km/sec. (metamorphics?); 2 km of 5.5 km/sec. (basement); and 2 km of 7.1 km/sec. (high speed basement). Below these, typical Moho velocities of 8.1 km/sec. were measured. Total depth to Moho ranges from 9 to 12 km below sea level, the greatest variation occurring in the basement layers. The least depth was measured 65 miles north of the Puerto Rico Trench.     

Calculations of intrinsic isotope effects and the detection of tunneling in enzyme-catalyzed reactions

The equation of Northrop [1975, Biochemistry, 14, 2644] for calculating intrinsic isotope effects from observed deuterium and tritium isotope effects of V/K, in which hydrogen is the reference isotope, has been extended to experimental designs using either deuterium or tritium as a reference. Partial derivatives of the intrinsic equations allow calculation of the relative precision of the three referenced isotope effects and these favor the order deuterium > tritium > hydrogen. In comparisons of observed and calculated isotope effects when hydrogen tunneling is present, both the precision and the magnitude of the difference was greater for intrinsic calculations than for exponentiations based upon a breakdown in the Swain-Schaad relationship.     

Optimizing Human Synovial Fluid Preparation for Two-Dimensional Gel Electrophoresis

Background

Prenatal screening for Down Syndrome (DS) would benefit from an increased number of biomarkers to improve sensitivity and specificity. Improving sensitivity and specificity would decrease the need for potentially risky invasive diagnostic procedures.

Results

We have performed an in depth two-dimensional difference gel electrophoresis (2D DIGE) study to identify potential biomarkers. We have used maternal plasma samples obtained from first and second trimesters from mothers carrying DS affected fetuses compared with mothers carrying normal fetuses. Plasma samples were albumin/IgG depleted and expanded pH ranges of pH 4.5 - 5.5, pH 5.3 - 6.5 and pH 6 - 9 were used for two-dimensional gel electrophoresis (2DE). We found no differentially expressed proteins in the first trimester between the two groups. Significant up-regulation of ceruloplasmin, inter-alpha-trypsin inhibitor heavy chain H4, complement proteins C1s subcomponent, C4-A, C5, and C9 and kininogen 1 were detected in the second trimester in maternal plasma samples where a DS affected fetus was being carried. However, ceruloplasmin could not be confirmed as being consistently up-regulated in DS affected pregnancies by Western blotting.

Conclusions

Despite the in depth 2DE approach used in this study the results underline the deficiencies of gel-based proteomics for detection of plasma biomarkers. Gel-free approaches may be more productive to increase the number of plasma biomarkers for DS for non-invasive prenatal screening and diagnosis.     

Factors Controlling the Production of Lysogenic Cultures of B. megatherium

(1) The proportion of infected B. megatherium cells which develop lysogenic colonies depends on the number and kind of infecting virus particles and on the culture medium in which the cells are growing. (2) Cells infected with 100 or more T virus particles (from megatherium 899) in yeast extract peptone disintegrate, produce very few virus particles, and less than one lysogenic colony per 10⁷ infected cells. Cells infected with one or a few particles produce 500 to 1000 virus particles each and about 30 lysogenic colonies per 10⁷ infected colonies. (3) T phage obtained from lysogenic magatherium KM cultures produces many more lysogenic cells than does the original megatherium 899 virus. (4) Cells infected with megatherium 899 T virus in peptone medium and then transferred to asparagine medium give rise to 10⁶ lysogenic colonies per 10⁷ infected cells and this transformation will occur even after the infected cells have been in peptone for 60 to 90 minutes and are beginning to produce virus particles. (5) Continued growth of KM strain with either C or T virus from megatherium 899 for several hundred generations in the steady state apparatus results in a lysogenic strain which produces several different types of virus.     

The low availability of dietary choline for the nutrition of the sheep.

1. Choline, which is present in the diet of the sheep either in the non-esterified form or combined in phospholipids, is rapidly degraded in the rumen. The ultimate product formed from the N-methyl groups is methane. 2. Analysis of the non-esterified choline and the phosphatidylcholine in ruminal and abomasal digesta indicate that the phospholipid is the main vehicle for the passage of choline to the lower digestive tract. 3. The concentration of phosphatidylcholine in abomasal digesta is lower than that of ruminal digesta, which is in line with a selective retention of protozoa in the rumen as observed by others. 4. On defaunation of the rumen to remove ciliated protozoa the concentration of phosphatidylcholine in ruminal digesta falls markedly and becomes lower than that in abomasal digesta. 5. Calculation shows that the adult sheep obtains at most only about 20--25 mg of effective choline per day from its diet (0.002--0.0025% of dietary total dry-weight intake). This is some fifty times less than the minimum required to avoid pathological lesions and death in other species investigated (0.1%+ of dietary dry-weight intake). 6. Sheep liver can synthesize choline from [14C]ethanolamine both in vitro and in vivo, but the synthesis of choline per kg body weight is many times less than it is in the rat. 7. The intact sheep oxidizes an injected dose of [1,2-14C]choline to CO2 at a rate that is several times less than that observed for the rat. This could help to explain the apparent minimal requirement of sheep for dietary choline.     

THE SWELLING AND OSMOTIC PRESSURE OF GELATIN IN SALT SOLUTIONS

1. The swelling and the osmotic pressure of gelatin at pH 4.7 have been measured in the presence of a number of salts. 2. The effect of the salts on the swelling is closely paralleled by the effect on the osmotic pressure, and the bulk modulus of the gelatin particles calculated from these figures is constant up to an increase in volume of about 800 per cent. As soon as any of the salts increase the swelling beyond this point, the bulk. modulus decreases. This is interpreted as showing that the elastic limit has been exceeded. 3. Gelatin swollen in acid returns to its original volume after removal of the acid, while gelatin swollen in salt solution does not do so. This is the expected result if, as stated above, the elastic limit had been exceeded in the salt solution. 4. The modulus of elasticity of gelatin swollen in salt solutions varies in the same way as the bulk modulus calculated from the osmotic pressure and the swelling. 5. The increase in osmotic pressure caused by the salt is reversible on removal of the salt. 6. The observed osmotic pressure is much greater than the osmotic pressure calculated from the Donnan equilibrium except in the case of AlCl₃, where the calculated and observed pressures agree quite closely. 7. The increase in swelling in salt solutions is due to an increase in osmotic pressure. This increase is probably due to a change in the osmotic pressure of the gelatin itself rather than to a difference in ion concentration.     

Plasminogen activator and collagenase production by cultured capillary endothelial cells

Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.