Use of Metabolic Inhibitors to Estimate Protozooplankton Grazing and Bacterial Production in a Monomictic Eutrophic Lake with an Anaerobic Hypolimnion

Inhibitors of eucaryotes (cycloheximide and amphotericin B) and procaryotes (penicillin and chloramphenicol) were used to estimate bacterivory and bacterial production in a eutrophic lake. Bacterial production appeared to be slightly greater than protozoan grazing in the aerobic waters of Lake Oglethorpe. Use of penicillin and cycloheximide yielded inconsistent results in anaerobic water and in aerobic water when bacterial production was low. Production measured by inhibiting eucaryotes with cycloheximide did not always agree with [³H]thymidine estimates or differential filtration methods. Laboratory experiments showed that several common freshwater protozoans continued to swim and ingest bacterium-size latex beads in the presence of the eucaryote inhibitor. Penicillin also affected grazing rates of some ciliates. We recommend that caution and a corroborating method be used when estimating ecologically important parameters with specific inhibitors.     

Stimulation of tissue plasminogen activator production from epithelial cell lines

The aim of this study was to investigate the possibility of enhancing the yield of tissue plasminogen activator (tPA) from two epithelial cell lines of normal (non-malignant) derivation grown in tissue culture. The three agents used in this investigation were chosen because of their proven enhancing effect on analogous cells or products. The anabolic hormone stanozolol was found to have no significant stimulatory effect on these cell lines. A phorbol acetate (12-O-tetradecanoylphorbol 13-acetate) caused a twofold enhancement in tPA yield but the most significant results were obtained with 5-azacytidine. This agent increased the yield by up to fourfold in small stationary cultures and threefold in large-scale microcarrier cultures. A combination of azacytidine and phorbol acetate did not have an additive effect on total yield but did alter the kinetics of tPA expression with time. Indications were that the maximum yield with these types of potentiating agents was achieved as it could not be increased by using a combination of two different agents.     

Energy from vascular plant wastewater treatment systems

Water hyacinth (Eichhornia crassipes), duckweed (Spirodela sp. andLemna sp.), water pennywort (Hydrocotyle ranunculoides), and kudzu (Pueraria lobata) were anaerobically fermented using an anaerobic filter technique that reduced the total digestion time from 90 d to an average of 23 d and produced 0.14-0.22 m³ CH₄/kg (dry weight) (2.3-3.6 ft³/lb) from mature filters for the 3 aquatic species. Kudzu required an average digestion time of 33 d and produced an average of 0.21 m³ CH₄/kg (dry weight) (3.4 ft³/lb). The anaerobic filter provided a large surface area for the anaerobic bacteria to establish and maintain an optimal balance of facultative, acid-forming, and methane-producing bacteria. Consequently the efficiency of the process was greatly improved over prior batch fermentations.     

Gas-liquid chromatography for the determination of acetylcholinesterase activity

Method has been modified and used for quantitative gas chromatographic determination of microtraces in a large volume of test mixture under study. The method can be applied for the differentiated determination of genuine and false blood cholinesterase by final products of specific substrate hydrolysis.     

Purification of mammalian tumor (L1210) thymidylate synthetase by affinity chromatography on stable biospecific adsorbent. Stabilization of the enzyme with neutral detergents.

Thymidylate synthetase from mouse leukemic L1210 cells was purified to electrophoretic homogeneity with 70% yield as a result of an affinity chromatography procedure based on reversible deoxyuridylate-dependent binding of the enzyme to a stable biospecific adsorbent, 10-formyl-5,8-dideazafolate, immobilized on aminoethyl-Sepharose. The presence of neutral detergents, Triton X-100, or Nonidet P40 stabilized thymidylate synthetase during purification. Analytical electrophoresis of the enzyme treated with an excess of 5-fluorodeoxyuridylate and 5,10-methylenetetrahydrofolate showed the presence of two forms of thymidylate synthetase--5-fluorodeoxyuridylate.5,10-methylenetetrahydrofolate complex, indicating that there are two binding sites for 5-fluorodeoxyuridylate present on the enzyme molecule. Molecular weight of native thymidylate synthetase was found to be 75,000, whereas that for the monomer was 38,500.     

Noni as an anxiolytic and sedative: A mechanism involving its gamma-aminobutyric acidergic effects

Noni (Morinda citrifolia) is increasing in worldwide popularity as a food or dietary supplement with versatile health benefits. The aim of this study was to investigate the effects of Noni fruit on anxiety symptoms in vitro. To this end, a competitive GABAa receptor-binding assay was developed. Our preliminary study indicates that the methanol crude extract of Noni fruit showed significant affinity to the gamma-aminobutyric acid A (GABAa) inhibitory neurotransmitter receptors, and displayed 75% binding inhibition of the agonist radioligand [3H] muscimol at a concentration of 100 microg/ml. Further experiments demonstrated that the MeOH extract, and its BuOH and H2O partitions, exhibited IC50 values of 22.8, 27.2, and 17.1 microg/ml, respectively, in the GABAa-binding assay. Experimental results with Noni fruit indicate the presence of competitive ligand(s), which may bind to the GABAa receptor as an agonist, and thus induce its anxiolytic and sedative effects. The study provides an in vitro rationale for one of Noni's versatile and traditional uses. In addition, an HPLC fingerprint profile of the methanolic extract of Noni fruit has been established for quality control purpose.