The Role of Glycerol and Inorganic Ions in Osmoregulatory Responses of the Euryhaline Flagellate Chlamydomonas pulsatilla Wollenweber

The green euryhaline flagellate Chlamydomonas pulsatilla Wollenweber, isolated from a coastal marine environment, was grown exponentially over the salinity range of 10 to 200% artificial seawater (ASW). The cellular volume and aqueous space of the alga, measured by [(14)C] mannitol and (3)H(2)O tracer analyses of centrifuged cell pellets, ranged between 2.3 and 3.1 picoliters and between 1.5 and 2.1 picoliters, respectively. The nonaqueous space determined in those analyses (28-35%) was consistent with the cell composition of the alga. The glycerol content of the alga increased almost linearly with increasing salinity; its contribution to intracellular osmolality at 200% ASW was about 57%. The contribution of amino acids and soluble carbohydrates to the cell osmotic balance was small. Intracellular ion concentrations determined by analyzing centrifuged cell pellets of known [(14)C]mannitol space by atomic absorption spectrophotometry, and by neutron activation analyses of washed cells were similar. At 10% ASW, potassium and magnesium were the major cations, and chloride and phosphate were the major anions. The sodium and chloride content of the alga increased with increasing salinity; at 200% ASW the intracellular concentration of both sodium and chloride was about 400 millimolar. The intracellular osmolality (pi(int)) matched closely the external osmolality (pi(ext)) over the entire salinity range except at 10% ASW where pi(int) exceeded pi(ext) by 120 to 270 milliosmoles per kilogram H(2)O.

Transport and Assimilation of Nitrogen by Stichococcus bacillaris Grown in the Presence of Methionine Sulfoximine

Stichococcus bacillaris Naeg., a green soil alga, can grow in the presence of methionine sulfoximine (MSX), an inhibitor of glutamine synthetase, by maintaining a high level of NADPH-glutamate dehydrogenase activity. MSX-grown cells can utilize both NH(4) (+) and NO(3) (-) as nitrogen source for growth. [(14)C]Methylammonium is not metabolized by S. bacillaris, and is transported by a carrier system that obeys Michaelis Menten kinetics, and is insensitive to MSX.

Nitrogen Metabolism of the Marine Microalga Chlorella autotrophica

The levels of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in Chlorella autotrophica (clone 580) are strongly regulated by the nitrogen source and salt concentration of the medium. GS is present at high levels in NO(3) (-)-grown cells, and at maximum levels in nitrogen-starved cells. However, the levels of GS in these cells are somewhat decreased by increasing salinity. Cells growing on NH(4) (+) have high NADPH-GDH activity, the levels of which increase with increasing NH(4) (+) supply, while GS decreases to a very low level under these conditions. Salinity intensifies the induction of NADPH-GDH activity in NH(4) (+)-grown cells. The levels of NADH-GDH are low in this alga, but present under all growth conditions. Methionine sulfoximine (MSX) has little effect on growth and nitrogen assimilation of the alga in the presence of NH(4) (+).

Osmoregulation in the Extremely Euryhaline Marine Micro-Alga Chlorella autotrophica

Chlorella autotrophica (Clone 580) grows over the external salinity range of 1 to 400% artificial sea water (ASW), can photosynthesize over the range from 1 to 600% ASW, and survives the complete evaporation of seawater. The alga grown at high salinities shows an increase in cell volume and a small decrease in cell water content. Measurements of ion content were made by neutron activation analysis on cells washed in isoosmotic sorbitol solutions which contained a few millimolar of major ions to prevent ion leakage. Cells grown at various ASW concentrations contain large quantities of sodium, potassium, and chloride ions. Measurements of cations associated with cell wall and intracellular macromolecules were made to determine intracellular concentration of free ions. The proline content of cells increases in response to increases in external salinity. Cells in 300% ASW contain 1500 to 1600 millimolar proline.

On-line trace enrichment of difenzoquat in water and its determination by HPLC

A high performance liquid chromatographic method involving an integrated enrichment step is described for the quantitative determination of low levels of difenzoquat residues in water. Difenzoquat is trapped from the flowing water sample by strong adsorption onto the enrichment column. It is then desorbed, separated, and subsequently analyzed in a single step process by reverse phase high performance liquid chromatography using ultraviolet detection at 255 nm. Average recovery of difenzoquat from organic free water at spiking levels of 20, 10 and 5 ppb was 97.0%. The lower detection limit reached was 0.25 ppb difenzoquat in organic free water.

A Revision of the Genus Stenozygum Fieber (Pentatomidae: Strachini) From the Oriental and Australian Regions, With Reference to Zoogeography and Phylogeny

Three new species of the genus Stenozygum Fieber, viz. pakistanensis and woodwardi in the subgenus Stenozygum Fieber and constrictus in Setozygum Ghauri, are described from the Oriental (Pakistan) and the Australian-Melanesian (Fiji) regions, with special reference to their male and female genitalia. The new species are compared with the type-species S.(S.) coloratum (Klug), a Palaearctic and Ethiopian species, and S.(S.) gemmeum (Walker), S.(S.) lepida (Walker) [previously treated as a synonym of gemmeum (Walker) (Kirkaldy, 1909)], S.(S.) pseudospeciosum Ghauri and S.(S.) speciosum (Dallas) from the Oriental region, and S.(S.) meridionale Gross and S.(S.) miniatulum Distant from the Australian region. The last six are redescribed, a key to all these species is given, and their relationships briefly discussed.

Laser flash photolysis studies of electron transfer between semiquinone and fully reduced free flavins and the cytochrome c-cytochrome oxidase complex

Laser flash photolysis has been used to determine the rate constants for the reduction of bovine cytochrome oxidase and the cytochrome c-cytochrome oxidase complex by the semiquinone and fully reduced forms of various flavin analogues (FH. and FH-, respectively). Under the condition used, the reaction of FH. with free cytochrome oxidase is too slow to compete with FH. disproportionation whereas FH- reacts measurably. Both FH. and FH- are effective in reducing the complex. The reduction of heme a in the complex is shown to proceed via cytochrome c, and a limiting first-order rate is observed in the case of FH- at high complex concentrations. The data indicate that the interaction site for electron transfer to cytochrome c is the same in the complex as with the free protein, and although a tight complex exists, at least small reactants like the flavins are not sterically hindered in their access to the bound cytochrome c. Moreover, the results also establish that intramolecular electron transfer between cytochrome c and cytochrome oxidase within the complex occurs with a first-order rate constant of greater than 700 s-1. Thus, the presence of cytochrome c greatly enhances electron transfer from reduced flavins to cytochrome oxidase.

Determination of pyrazon residues in water by reversed phase high performance liquid chromatography

A simple analytical method is described for the quantitative determination of pyrazon residues in water. It involves high performance liquid chromatography with ultraviolet detection at 270 nm. The procedure is used to determine 2 ppb to 1 ppm levels of pyrazon in water. The traditional liquid-liquid extraction method has been replaced by an adsorption-trapping method for the extraction of pyrazon. Average recovery of pyrazon from the laboratory spiked samples was 98.1%. The method can be used for water samples with concentrations as low as 2 ppb.

Laser flash photolysis studies of electron transfer between semiquinone and fully reduced free flavins and horse heart cytochrome c

Laser flash photolysis has been used to determine the second-order rate constants for the reduction of horse heart cytochrome c by the semiquinone and fully reduced forms of various flavin analogs. We find that substitution in the dimethylbenzene ring of the flavin causes appreciable changes in the rate constants, whereas substitutions at the N-10 position do not. Placing a charged phosphate group in the N-10 ribityl side chain leads to only small ionic strength effects on the rate constants, whereas a charged group attached to the dimethylbenzene ring produces a large ionic strength effect. These results can be accounted for by assuming that a productive collision between flavin and cytochrome involves an orientation that positions the aromatic ring--N-5 region of the flavin toward the heme crevice and the N-10--pyrimidine ring region away from it. Our observations have implications for mechanistic understanding of biological electron transfer reactions and are discussed in this context.

Solvent effects of flavin electron transfer reactions

The effects of solvent environment on the rates of several flavin redox reactions have been studied by using laser flash photolysis. These include electron transfer to the flavin triplet state (a measure of oxidized flavin electrophilicity) and the oxidation of flavin semiquinone by oxidized flavin radical, oxidized phenol radical, and quinone. The rate constant for triplet quenching by 2,6-dimethylphenol was found to be proportional to the inverse of solvent viscosity, as would be expected for a diffusional process. The flavin semiquinone yield due to flavin reduction during the quenching reaction was linearly dependent on the solvent dielectric constant. This implies the existence of a polar or charged intermediate along the reaction pathway. A similar effect of solvent dielectric was found for the self-quenching reaction, which produces semiquinone and an oxidized flavin radical. The rate constants for all three of the semiquinone oxidation reactions studied were found to exhibit a biphasic dependence on solvent dielectric, being virtually independent of dielectric at low values and sharply increasing at high values. This is interpreted in terms of a change in mechanism with solvent polarity. Specifically, we propose a neutral transition state and hydrogen atom transfer in low dielectric media and a dipolar transition state and electron transfer in high dielectric media. No specific effects of hydrogen-bonding interaction between flavin and solvent were observed for any of the processes studied. The mechanistic implications of these results for flavoenzyme catalysts are discussed.

Search for newer substituted phenoxyacetylethyleneimines as possible CNS, MAO and anticonvulsant agents

Various substituted phenoxyacetic acids were converted into the acid chlorides, which react with ethyleneimine in pyridine to give the desired product. These compounds were evaluated for central nervous system (CNS) activity. Some of the compounds at a concentration of 1 . 10-3mol/l inhibited rat brain monoamine oxidase (MAO) in vitro and provided protection against pentylenetetrazole-induced convulsions in mice.

Chemical alkylation of lead (II) salts to tetraalkyllead (IV) in aqueous solution

Methylation of lead in the environment would have serious consequences for water quality and for the well being of aquatic biota. As there is strong evidence that tetraalkylleads, the end products of lead alkylation, are considerably more toxic than lead (II) compounds, the elevated levels of inorganic lead now present in inland waterways and sediments as a result of industrial and motor vehicle emissions will pose a serious environmental hazard if mechanisms exist for the conversion to alkyllead (IV) species in aquatic systems. In the belief that the key to biological Pb(II) methylation lies in methyl transfer to Pb(II) from a carbonium ion donor (for example, S-adenosylmethionine), we recently initiated chemical and biological studies on the reactions of CH3+ donors with neutral and anionic Pb(II) compounds. We describe here the unequivocal synthesis of volatile tetramethyllead and other tetraalkylleads from Pb(II) salts and simple chemical reagents in aqueous solution. The known occurrence of methyl iodide in natural waters and our demonstration that Me4Pb is readily synthesized from this reagent and Pb(II) salts in aqueous solution could have far reaching significance not only for the chemical synthesis of toxic organoleads but also for possible mechanisms of microbiological methylation.

The use of medical records by adjudicators in processing Social Security disability insurance benefit claims

The Social Security Administration contracts with state agencies to process disability claims filed under the Social Security Act. These state agencies employ physicians and lay adjudicators who secure medical reports from physicians, hospitals and clinics, and use these reports in awarding or denying disability benefits. This nationwide study showed that well over half of the lay adjudicators are involved in developing and interpreting medical information independently. This suggests that appropriate hiring practices, adequate training and certification procedures should be instituted to ensure that the lay disability adjudicators are able to conduct their job efficiently and correctly.

A convergent route to phthalideisoquinoline alkaloids via directed metalation of tertiary benzamides

Diastereomeric phthalideisoquinolines 8 and 9 have been synthesized by a route involving an amine-induced bromohomophthalic anhydride – phthalide-α-carboxamide rearrangement, 3 + 4 → 6, as the key step. This rearrangement has been applied to the synthesis of the methoxylated phthalide-α-carboxamide 18 which has been converted into the dehydrophthalide 19 thereby achieving a formal synthesis of the phthalideisoquinoline alkaloids cordrastine I (1a) and cordrastine II (1b). The key intermediate in this sequence, 3,4-dimethoxyhomophthalic acid (15), has been efficiently prepared in two steps via directed lithiation of 2,3-dimethoxy-N,N-diethylbenzamide (13).

SORBITOL, A COMPATIBLE OSMOTIC SOLUTE IN PLANTAGO MARITIMA

Plantago maritima grown under saline conditions accumulates large quantities of sodium chloride. Salinity reduces tissue potassium, calcium and magnesium contents. Several enzymes from P. maritima are shown to be salt-sensitive. In contrast to many other higher plant halophytes, P. maritima shows no accumulation of either amino acids or methylated onium compounds. High levels of the polyhydric alcohol sorbitol are however accumulated under saline conditions. The possible role of sorbitol as a compatible cytoplasmic solute is discussed.

Malignant hemangioendothelioma (angiosarcoma) of the salivary gland: an ultrastructural study

A case of malignant hemangioendothelioma (angiosarcoma) of the submaxillary salivary gland is reported and its microscopic and ultrastructural features are described and compared to previous reports of angiosarcoma arising in other locations. These tumors may often contain areas of solid sheets of cells without vascular characteristics and may be confused with poorly differentiated carcinoma or other sarcomas. The ultrastructural features of angiosarcoma are compared to other poorly differentiated tumors. It is concluded that the ultrastructural features of angiosarcoma are distinctive and aid in the diagnosis of this neoplasm.