Groundwater contribution to the nutrient budget of Tomales Bay,California

Tomales Bay, a graben structure along the San Andreas Fault, was selected for modeling ecosystem nutrient dynamics because of its linear, one-dimensional morphology and relatively pristine state. Groundwater is a potentially important term in the nutrient budget. The geologic complexities created by the San Anreas Fault, however, complicate the hydrogeology and require the area to be subdivided into three regions: granite to the west, Franciscan Formation to the east, and alluvial fill in the trough. Nutrient concentrations in the groundwater were determined through extensive well sampling; groundwater discharge was estimated using both Darcy's Law calculations and a soil moisture budget. Results indicate that groundwater discharge is of the same order of magnitude as summer streamflow into the Bay, while being significantly less than other freshwater inputs in winter. Dissolved nutrient (phosphate, nitrate + nitrite, ammonium, silica and DIC) concentrations in groundwater were consistently higher (by as much as an order of magnitude) than in surface water discharges. During the summer months, groundwater flow contributes about as much nutrient load to the bay as does streamflow. During the winter, the groundwater contribution to nutrient loading is about 20% of the streamflow contribution. Our findings indicate that groundwater is a significant component of terrestrial nutrient and freshwater loading to Tomales Bay, particularly so during the summer months. However, neither groundwater nor streamflow nutrient fluxes are large in comparison to the mixing flux at the bay mouth or the flux of N₂ gas across the air-water interface.     

Responsiveness of fetal and adult CD4-, CD8- thymocytes to T cell activation

Day-14 fetal CD4-, CD8- thymocytes showed a greater proliferative response to PMA + IL-4 than did adult double-negative thymocytes. In contrast, adult double-negative thymocytes were more responsive to PMA + IL-1 + IL-2 or to IL-1 + IL-2 alone. The adult double-negative thymocytes showed significantly greater proliferation than fetal thymocytes after stimulation via anti-CD3 or anti-Thy-1 in the presence or absence of interleukins (IL-1 + IL-2 or IL-4). Adult CD4-, CD8- thymocytes also exhibited greater calcium mobilization following anti-CD3 stimulation IL-2-dependent activation with anti-Thy-1 or IL-1 + IL-2 in the absence of PMA resulted in marked expansion of CD 3+, F23.1+, CD4-, CD8- thymocytes, a population absent in fetal thymocytes but constituting 4% of pre-cultured CD4-, CD8- adult thymocytes. IL-4 + PMA failed to expand this CD 3+ population. It is hypothesized that before expression of functional TCR, T cell development may be more dependent on activation pathways not using IL-2; after TCR expression, IL-2-dependent pathways, including Thy-1-mediated stimulation, become functional.     

SOME BIOCHEMICAL PROPERTIES OF CHINESE HAMSTER CELLS SENSITIVE AND RESISTANT TO ACTINOMYCIN D

A graded series of drug-resistant Chinese hamster sublines has been examined for biochemical changes accompanying resistance to actinomycin D. The most highly resistant subline, DC-3F/AD X, is maintained at 10 µg/ml of the antibiotic. It was shown that over 250 times more actinomycin D is required to inhibit RNA synthesis in this subline than in the parental DC-3F line. The DC-3F/AD X subline was also shown to have a somewhat reduced capacity to transport uridine as compared to parental cells. Sensitive cells took up over 50 times more tritiated antibiotic than the most resistant cells, as determined in a 1-h assay. Uptake of actinomycin D was shown to be temperature-dependent in both resistant and sensitive cells and was not influenced by various metabolic inhibitors. Resistance could not be explained by a rapid uptake and release of the antibiotic, as demonstrated in efflux experiments, or by its metabolism. In addition, highly resistant cells which are cross-resistant to puromycin were shown to have a reduced capacity to take up labeled puromycin. These studies provide further evidence indicating that the mechanism of resistance to actinomycin D is reduced permeability to drug and suggesting that cell membrane alteration accounts for resistance to both actinomycin D and puromycin.     

Design,synthesis and biological evaluation of (2S,3R,4R,5S,6R)-5-fluoro-6-(hydroxymethyl)-2-aryltetrahydro-2H-pyran-3,4-diols as potent and orally active SGLT dual inhibitors

A new series of (2S,3R,4R,5S,6R)-5-fluoro-6-(hydroxymethyl)-2-aryltetrahydro-2H-pyran-3,4-diols as dual inhibitors of sodium glucose co-transporter proteins (SGLTs) were disclosed. Two methods were developed to efficiently synthesize C₅-fluoro-lactones 3 and 4, which are key intermediates to the C₅-fluoro-hexose based C-aryl glucosides. Compound 2b demonstrated potent hSGLT1 and hSGLT2 inhibition (IC₅₀?=?43?nM for SGLT1 and IC₅₀?=?9?nM for SGLT2). It showed robust inhibition of blood glucose excursion in oral glucose tolerance test (OGTT) in Sprague Dawley (SD) rats and exerted pronounced antihyperglycemic effects in db/db mice and high-fat diet-fed ZDF rats when dosed orally at 10?mg/kg.     

Discovery of a novel potent GPR40 full agonist

Compound 12 is a GPR40 agonist that realizes the full magnitude of efficacy possible via GPR40 receptor agonism. In vitro and in vivo studies demonstrated superior glucose lowering by 12 compared to fasiglifam (TAK-875), in a glucose dependent manner. The enhanced efficacy observed with the full agonist 12 was associated with both direct and indirect stimulation of insulin secretion.     

C-3 glucosiduronates of metabolites of adrenal steroids

On treatment with methyl 2,3,4-tri-O-acetyl-l-bromo-l-deoxy-α-D-glucuronate and silver carbonate, tetrahydrocortisone 21-acetate gave the corresponding 3-glucosiduronate triacetyl methyl ester. This product was converted into the 20-semicarbazone which, by treatment with alkali to hydrolyze the ester functions and acid to hydrolyse the semicarbazone moiety, gave tetrahydrocortisone 3-glucosiduronic acid. The acid was converted into the crystalline barium salt and into the methyl ester. An analogous series of reactions was carried out on tetrahydrocortexolone 21-acetate. Treatment of the 20-semicarbazone of tetrahydrocortisone 3-glucosiduronic acid with potassium borohydride reduced the 11-oxo function to an 11β hydroxyl group; acid-catalyzed removal of the semicarbazone group produced tetrahydrocortisol 3-glucosiduronic acid which also was obtained as the barium salt and the methyl ester.     

Synthesis of α-<Emphasis Type="SmallCaps">D</Emphasis>-Glucose 1,6-Diphosphate in Potentially Prebiotic Conditions

A NOVEL method for the phosphorylation of sugars by orthophosphate in the presence of cyanogen in dilute aqueous neutral or slightly alkaline solutions has been described, suggesting a plausible model of the prebiotic phosphorylation of sugars^1–3. This reaction has now been applied to the synthesis of glucose 1,6-diphosphate, starting either from α-D-glucose 1-phosphate or from D-glucose 6-phosphate. The formation of α-D-glucose 1,6-diphosphate from α-D-glucose 1-phosphate would indicate a possible route for the synthesis of this compound on the primitive Earth. It is known that α-D-glucose 1,6-diphosphate is the coenzyme in the inter-conversion of α-D-glucose 1-phosphate with glucose 6-phosphate catalysed by phosphoglucomutase*. The formation of α-D-glucose 1,6-diphosphate seems to be interesting in view of our model for the chemical evolution of the metabolism of sugars⁵, as it may connect α-D-glucose 1-phosphate with the glycolytic pathway.     

Extraction of steroidal glucosiduronic acids from aqueous solutions by anionic liquid ion-exchangers

A pilot study on the extraction of three steroidal glucosiduronic acids from water into organic solutions of liquid ion-exchangers is reported. A single extraction of a 0.5mm aqueous solution of either 11-deoxycorticosterone 21-glucosiduronic acid or cortisone 21-glucosiduronic acid with 0.1m-tetraheptylammonium chloride in chloroform took more than 99% of the conjugate into the organic phase; under the same conditions, the very polar conjugate, beta-cortol 3-glucosiduronic acid, was extracted to the extent of 43%. The presence of a small amount of chloride, acetate, or sulphate ion in the aqueous phase inhibited extraction, but making the aqueous phase 4.0m with ammonium sulphate promoted extraction strongly. An increase in the concentration of ion-exchanger in the organic phase also promoted extraction. The amount of cortisone 21-glucosiduronic acid extracted by tetraheptylammonium chloride over the pH range of 3.9 to 10.7 was essentially constant. Chloroform solutions of a tertiary, a secondary, or a primary amine hydrochloride also will extract cortisone 21-glucosiduronic acid from water. The various liquid ion exchangers will extract steroidal glucosiduronic acid methyl esters from water into chloroform, although less completely than the corresponding free acids. The extraction of the glucosiduronic acids from water by tetraheptylammonium chloride occurs by an ion-exchange process; extraction of the esters does not involve ion exchange.     

Laboratory Identification of Rothia dentocariosa and Its Occurrence in Human Clinical Materials

Fifty isolates of Rothia dentocariosa from diverse clinical sources were characterized by 28 separate tests. An attempt was made to select practical tests that could be completed in a minimal length of time. Rothia is also compared with Actinomyces and Nocardia with which it is often confused. Of the isolates 100% were positive in the following reactions: catalase production, nitrate and nitrite reduction, esculin hydrolysis, and acid production from glucose, sucrose, maltose, salicin, and glycerol. The importance of recognizing this organism is based on the fact that it is frequently isolated from human clinical materials and must be differentiated from morphologically similar organisms of the genera Actinomyces and Nocardia, which contain pathogenic members.     

The accumulation of bacteriochlorophyll precursors by mutant and wild-type strains of Rhodopseudomonas spheroides

1. Two mutant strains of Rhodopseudomonas spheroides, which are blocked in the synthesis of bacteriochlorophyll, accumulate pigments. These have been tentatively identified as magnesium 2,4-divinylphaeoporphyrin a₅ monomethyl ester and the magnesium derivative of 2-devinyl-2-hydroxyethyl-phaeophorbid a, formed by mutant 2/73 and 2/21 respectively. 2. Maximum extracellular production of these pigments occurs when suspensions of the organisms are incubated with low aeration in a growth medium containing iron and supplemented with glycine, succinate, methionine and Tween 80. 3. Concomitant protein synthesis is required for pigment production by the mutants from glycine and succinate but this requirement is less marked when δ-aminolaevulic acid is the substrate. 4. In the absence of Tween 80, a considerable proportion of the total pigment is retained within the cells and appears in the particulate fraction of cell-free extracts. 5. Suspensions of the parent strain containing δ-aminolaevulic acid can be made to accumulate extracellular pigments which are tentatively identified as magnesium protoporphyrin monomethyl ester and the magnesium derivative of 2-devinyl-2-hydroxyethyl-phaeophorbid a. 6. Maximum production occurs with cells incubated photosynthetically after a period of oxygen repression of bacteriochlorophyll synthesis. Formation of the phaeophorbid derivative is enhanced by 8-azaguanine or 5-fluorouracil, or by adenine deficiency in a nutritional mutant; Tween 80 is also needed and iron is essential. 7. Synthesis of bacteriochlorophyll might possibly involve the participation of lipoprotein-bound intermediates, which may be formed at the initial stage of condensation between glycine and succinyl-CoA to give δ-aminolaevulic acid.