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Techniques for preparation of enzyme extracts from Chlorella pyrenoidosa chick are described which yield a stable system which converts adenosine 5'-phosphosulfate to sulfide and/or cysteine in the absence of added active thiols. Since these thiols (such as dithiothreitol) have been shown to yield sulfite, among other products, from the adenosine-5'-phosphosulfate sulfotransferase reaction, we have studied the adenosine 5'-phosphusulfate reducing system in the presence and absence of dithiothreitol. In all cases dithiothreitol increases the activity of the reducing system forming cysteine from adenosine 5'-phosphosulfate. Mutant Sat-2, which cannot grow on sulfate, is shown to lack thiosulfonate reductase activity but to retain sulfite reductase activity. Extracts from this mutant will form sulfide and cysteine only in the presence of dithiothreitol, while wild-type extracts will form these products in presence or absence of dithiothreitol, the activity with dithiothreitol being higher. Mutants Sat-1,3-6 which are blocked in the adenosine-5'-phosphosulfate sulfotransferase step are blocked in the formation of sulfide and cysteine from adenosine 5'-phosphosulfate. Binding studies with adenosine 5'-phosphosulfate indicate that the sulfonyl group is transferred to a carrier to form carrier-S-SO-3 and the available evidence suggests that this carrier is a prosthetic group of the thiosulfonate reductase. On the basis of this evidence, two pathways in the cell-free extracts are thought to be operating. One, in the absence of active thiols, is a pathway consisting of bound intermediates in which the sulfonyl group of adenosine 5'-phosphosulfate is transferred via adenosine-5'-phosphosulfate sulfotransferase to carrier on the thiosulfonate reductase where it is reduced to the thiol level by ferredoxin; the thiol is then transferred via O-acetyl-L-serine sulfhydrylase to form cysteine. The other, or free intermediate pathway operates in the presence of dithiothreitol which releases free sulfite from the adenosine-5'-phosphosulfate sulfotransferase reaction. This sulfite is then reduced via sulfite reductase to sulfide which forms cysteine via O-acetyl-L-serine sulfhydrylase. Since mutant Sat-2, which cannot grow on sulfate nor reduce it in vivo, lacks thiosulfonate reductase activity but yields sulfite reductase activity in extracts, we conclude that the bound intermediate pathway is the preferred pathway of sulfate reduction in vivo; the free intermediate pathway is probably operative only when free sulfite is available either from occasional side reactions in vivo or when sulfite is fed to cells from outside. [ABSTRACT FROM AUTHOR]

1. Fibroblasts cultured from the skin of patients with Sandhoff disease accumulate excessive amounts of sulfated glycosaminoglycans, probably chondroitin sulfate and dermatan sulfate. In addition, Sandhoff fibroblasts show a lengthened turnover time for these compounds. Only little such abnormality in sulfated glycosaminoglycan metabolism has been found in Tay-Sachs fibroblasts. 2. The impaired catabolism of glycosaminoglycans in Sandhoff fibroblasts can be normalized, i.e. corrected, by addition of β-N-acetylhexosaminidase isozyme A from normal human urine to the culture medium. β-N-Acetylhexosaminidase isozyme B from urine is ineffective because it is not taken up by the cells. However, if homogenates of normal or Tay-Sachs fibroblasts are used as a source of the enzymes, metabolic correction is obtained in both instances. When β-N-acetylhexosaminidase isozymes A and B of normal fibroblasts are separated by isoelectric focusing and tested individually, isozyme A exhibits about five times the corrective activity of isozyme B, when compared on the basis of their activity toward the synthetic substrate, 3. Although β-N-acetylhexosaminidase isozyme B participates in the degradation of sulfated glycosaminoglycans in cultured cells, only fibroblast homogenates containing isozyme A release N-acetylglucosamine from [14C]glucosamine-labelled hyaluronic acid oligosaccharides in vitro. [ABSTRACT FROM AUTHOR]

1. The inhibition of the 5-serine O-sulphate-degrading activity of pig liver has been investigated. Compounds that acted as competitive inhibitors all possessed the basic stereochemistry associated with the L-serine O-sulphate molecule. 2. In general the most efficient competitive inhibitors were those possessing an interproton distance of 0.75 nm, with two electronegative ends or alternatively one electronegative end and the negative end of a dipole. 3. O-Phospho-L-serins is an atypical inhibitor since it obeys non-competitive inhibitor kinetics even though from theoretical considerations it should act as a competitive inhibitor. 4. 3-Chloro-L-alanine methyl ester is a substrate for the enzyme. 5. 4-Iodoacetamidosalicy]Je acid acts as an irreversible inhibitor of the system. 6. The probable topography of the active site and the disposition of the substrate at the active site is discussed. [ABSTRACT FROM AUTHOR]

By incubation with washed mitochondria from guinea pig liver [7α-³H]dehydroepiandrosterone sulfate can be converted into a ³H-labelled lipophile sulfoconjugate. Concerning the overall reaction a Km-value of approximately 6 μM was derived from the substrate concentration curve. Optimal yields of lipophile steroid sulfoconjugates were obtained at a pH of 8.0. Of the various coenzymes tested CTP appeared to be essential for the formation of lipophile sulfoeonjugates. Whereas magnesium ions stimulated the conversion of [7α-³H]dehydroepiandrosterone sulfate, the biosynthesis of lipophile steroid sulfoconjugates was inhibited by sodium fluoride or p-chloromercuribenzoate. [ABSTRACT FROM AUTHOR]

The polar movement of IAA has been examined in 5-mm root segments of Brassica oleracea and Helianthus annuus. The movement was studied partly with IAA-1-14C and partly with IAA-5-³H In both plants a slight acropetal flux of 14C and IAA-³H was found through the segments. The recovered radioactivity in the agar receiver blocks and in the receiver end of the segments increased as a function of time. A large portion of the applied IAA was converted on the cut surfaces and in the tissues of the segments. Chromatographic analysis indicated different destruction products when estimated by scintillation counting and by spraying with indole reagent (DMCA). Chromatograms run in isopropanol : ammonia : water, 8 : 1 : 1, yielded three different substances, one spot near the starting line and one near the front, neither of which has been identified. Finally there was a spot with Rf 0.4-0.6, probably representing IAA.

Gradients of tritiated water, 35S-sulphate and 32P-phosphate, were established in isolated segments of willow stems. Sieve tube exudate was collected as honeydew from the high activity end of the segment. After girdling the stem a few centimeters from the site of sieve tube puncture, the specific activity of 35S and 32P in the honeydew rose, whilst the specific activity of tritium remained constant. These findings indicate that prior to girdling, unlabelled sulphates and phosphates were contributing to the honeydew, whilst there had been no detectable contribution by unlabelled water from the low activity end of the segment. The data support the conclusions drawn from previous experiments by Peel et al. (1969), that water is relatively immobile in sieve tubes of willow when compared to solutes. [ABSTRACT FROM AUTHOR]

The pathological changes in murine runts induced by neonatal thymectomy, the graft-versus-host reaction, neonatal infection with reovirus type 3, treatment with bacterial endotoxin, bacterial vaccine and cortisone acetate are described. It is shown that while each inducer produces its own characteristic features, others are common to all classes of runts. We suggest that these shared attributes result from the action of bacterial endotoxin. This, we believe, plays a more important role in the genesis of all murine runting than autoimmune reactions which act, if at all, during the chronic phase of these syndromes. [ABSTRACT FROM AUTHOR]

Carrageenin prevents the reaction of guinea-pig C′ with sensitized red blood cells, probably by a direct inactivation of the C′1. The anti-complementary effect of carrageenin is antagonized by protamine sulphate. Marked reduction of circulating C′ activity in guinea-pigs resulting from intravenous injection of carrageenin, does not alter their susceptibility to acute or protracted anaphylactic shock. The C′ activities of human, guinea-pig, rabbit, rat and monkey sera are all inhibited in vitro by carrageenin. [ABSTRACT FROM AUTHOR]

The steroids in meconium from normal male and female newborn infants have been studied by gas chromatography-mass spectrometry. Practically all steroids were excreted as mono- and disulphates. The approximate concentrations of steroid mono- and disulphates were 430 and 470 μg per g of meconium. Twenty unsaturated and fourteen saturated steroids were completely identified. Most of the unsaturated steroids had a 3β-hydroxy-Δ5 structure. In addition, seven saturated steroids were tentatively identified. No significant qualitative differences were found in the steroid composition of meconium from male and female newborns. The results are discussed in relation to present knowledge of steroid metabolism in the foeto-placental unit. [ABSTRACT FROM AUTHOR]

Neutral steroid glucuronides and mono- and disulphates in faeces and urine of normal adult males were analysed before and during phthalylsulphathiazole treatment ir order to clarify whether faecal and urinary excretion of C19 and C21 steroids is modified by reduction of the intestinal microflora. For the same purpose, the unconjugated neutral steroids in faeces were analysed, too. During the sulphonamide treatment, the profile of faecal neutral steroid sulphates became very similar to that in bile. The amount of sulphate-conjugated neutral steroids, especially disulphates, was increased and the pattern of the faecal steroids indicated a decrease in the oxidoreducing and epimerising activities of the intestinal contents. No neutral steroid glucuronides were detected in faeces either before or during the sulphonamide treatment. The urinary excretion of neutral steroid conjugates was very little affected by the administration of the drug. However, most of the 16-hydroxylated C19 steroid monosulphates were excreted in urine in larger amounts during the treatment than before it.The resets obtained indicate that in normal adult subjects changes in the composition of the intestinal microflora greatly modify faecal steroid excretion, but seem to be of very little importance for the urinary output of a large number of neutral steroid conjugates. [ABSTRACT FROM AUTHOR]

Copolymers with different contents of adenine and N1-methyl adenine residues have been studied, polyadenylic acid being methylated by sulfate. Thermal stability, circular dichroism and light scattering measurements are in favor of a two-strand structure at neutral pH. Thermal stability of these products is much less sensitive to ionic strength than that of most polynucleotides, and in some cases independent of ionic strength. These copolymers interact or not with poly(U), depending on the percentage of N1-methyl adenine residues. Copolymers with high contents of methyladenine interact with poly(A) at neutral pH. These copolymers do not bind DNA-dependent RNA polymerase. Some results at acid pH are also reported. [ABSTRACT FROM AUTHOR]

The steroids in urine from a pregnant woman have been studied by gas chromatography-mass spectrometry. The major part, 64%, of the steroids identified occurred in the glucuronide fraction, whereas the free, monosulphate and disulphate fractions contained 24%, 5% and 7%, respectively. The compounds had the following general structures: 3-hydroxy-17β-pregnan-20-one, 3α-hydroxy-5β, 17α-pregnan-20-one, 3α-hydroxy-5α-androstan-17-one, preganane-3, 20-diol, 3α, 21-dihydroxy-5β-pregnan-20-one, 3α, 16α-dihydroxy-5β-pregnan-20-one, 3α, 15β-dihydroxy-pregnan-20-one, 5-pregnane-3β, 20α-diol, 5α-pregnane-3, 20α, 21-triol, 5-androstene-3β, 16, 17-triol, oestriol, 15-hydroxyoestriol and pregnane-3, 16, 20, 21-tetrol. In the free and glucuronide fractions the C21O2 steroids mainly has a5β configuration whereas about 90% of the mono- and di-sulphurylated C21O2 steroids had a 5α structure. The results are discussed in relation to what is known about faecal excretion of steroids during pregnancy. [ABSTRACT FROM AUTHOR]

Gas-liquid chromatography, radio-gas chromatography and gas chromatography-mass spectrometry were used to identify steroid metabolites in the monosulphate and disulphate fractions of faeces from germfree female rats and in the monosulphate fraction of faeces from conventional female rats after intraperitoneal administration of [4-14C]pregnenolone and [4-14C]-corticosterone. The germfree rats excreted the following steroids: monosulphate fraction: 3β, 17α-dihydroxy-5α-pregnan-20-one, 5α-pregnane-3α, 16α, 20α-triol, 2α, 3β, 16α-trihydroxy-5α-pregnan-20-one and 3α, 15β, 16α-trihydroxy-5α-pregnan-20-one; disulphate fraction: 3α- and 3β, 11β, 21-trihydroxy-5α-pregnan-20-one. The following steroids were identified in faeces from conventional rats: oestriol, 3α, 15α(and 15β)-dihydroxy-5α, 17α (and 17β)-pregnan-20-one-3α 19-dihydroxy-5α, 17α-pregnan-20-one, 5α-pregnane-3α, 16α, 20-triol, 3β, 11α-dihydroxy-5α-pregnan-20-one, 2α, 3α-dihydroxy-5α, 17α-pregnan-20-one (tentatively identified), and 3α, 17α-dihydroxy-5α-pregnan-20-one. The different steroid patterns in faeces from germfree and conventional rats are explained by the metabolic reactions carried out by the intestinal flora. Radio-gas chromatography showed that 3α- and 3β, 11β, 21-trihydroxy-5α-pregnan-20-one and 3β, 11α-dihydroxy-5α-pregnan-20-one were metabolites of corticosterone. The formation of 3β, 11α-dihydroxy-5α-pregnan-20-one and of the 17α-pregnane derivatives by intestinal microorganisms is discussed. [ABSTRACT FROM AUTHOR]

The steroid glucuronide, and mono- and disulphate fractions were obtained from human bile by chromatography on Sephadex LH-20. The conjugates in the glucuronide fraction were hydrolysed with β-glucuronidase and the mono- and disulphate fractions were solvolysed. The steroids liberated were fractionated on silicic acid and by thin layer chromatography and analysed by gas-liquid chromatography and gas chromatography-mass spectrometry. The following C21O3 and C21O4 steroids were identified: 5α-pregnane-3α,17α,2oα-triol, 5β-pregnane-3α,17α,20αtriol, 5-pregnene-3α,17α,20α-triol, 5-pregnene-3β,17α,20α-triol, 5α-pregnane-3α,16α,20α-triol, 3α,21-dihydroxy-5β-pregnan-20-one, 3α,11β,21-trihydroxy-5α-pregnan-20-one, 3α,11β,21-trihydroxy-5β-pregnan-20-one and 3α,21-dihydroxy-5β-pregnane-11,20-dione. Concentrations of these steroids were measured in fistula or gall-bladder bile samples from five subjects. [ABSTRACT FROM AUTHOR]

Ethanol intake has been shown to cause a rapid increase of the concentration of androst-5-ene-3β,17β-diol 3-sulphate and a simultaneous decrease of the concentration of dehydroepiandrosterone sulphate in plasma. The ratio between the 17β-hydroxysteroid and the 17-ketosteroid increased with the ethanol concentration up to 30-50 mg ethanol/100 ml blood when a 6 to 10-fold increase was obtained. The ratios between the 3-sulphates of 5α-androstane-3α,17β-diol and androsterone and between the monosulphates of 5α-androstane-3β,17β-diol and 3β-hydroxy-5α-androstan-17-one also increased during ethanol metabolism. Deuterium was rapidly incorporated into the D-ring of the three C19 steroid diols, reaching about 20 atom per cent excess 10 to 20 min after oral administration of 0.1 g [1-²H2]ethanol per kg body weight. The concentrations of steroids with a sulphate group at C-17 did not change and deuterium was not incorporated into these steroids or into the 17-ketosteroid sulphates. The ratio between the 3-sulphates of 5-pregnene-3β,20α-diol and pregnenolone increased only slightly and incorporation of deuterium into the side chain of the C21 diol reached a maximum of about 4 atom per cent excess about 1 hour after the ethanol administration. The results indicate that the ratio between 3-sulphates of 17β-hydroxysteroids and the corresponding 17-ketosteroids in plasma is determined by the NADH/NAD+ ratio in the liver cell cytoplasm. They also indicate that the 3-sulphate of 5-pregnene-3β,20α-diol is not formed from pregnenolone sulphate at the same site or with the use of the same coenzyme molecules as the 17β-hydroxysteroids. [ABSTRACT FROM AUTHOR]

The sulphate of 3β-hydroxypregn-5-en-20-one is now reported to be a substrate for crystalline 20β-hydroxysteroid:NAD oxidoreductase prepared from Streptomyces hydrogenans. Utilization of this steroid sulphate was not independent of activity towards pregn-4-ene-3,20-dione or 3β-acetoxypregn-5-en-20-one, but the total rate of reaction for equimolar mixtures of 3β-hydroxypregn-5-en-20-one sulphate and either pregn-4-ene-3,20-dione or 3β-acetoxypregn-5- en-20-one was less than that calculated for the simplest type of mutual competitive inhibition, particularly at low substrate concentrations. The Michaelis constant for NADH was similar (about 5 μM) with each of these compounds as substrate. 3β-Hydroxypregn-5-en-20-one, and its 17α-hydroxy derivative behaved anomalously, and their behaviour is discussed. 3β,17α,21-Trihydroxypregn-5-en-20-one was a good substrate and had kinetic constants similar to those of 17α,21-dihydroxypregn-4-ene-3,20-dione. [ABSTRACT FROM AUTHOR]

When ferric myoglobin reacts with alkyl sulphates, its absorption spectrum changes into one characteristic of a haemichrome or parahaematin. The reaction equilibrium was studied over a range of protein concentrations using dodecyl sulphate and other alkyl sulphates with different chain lengths. The results obtained from spectrophotometric measurements and equilibrium dialysis experiments are not in agreement with those of other authors who. from an anal sis of spectral changes only, supported the hypothesis of an all-or-none type of reaction whereby 18 detergent. anions were bound to one molecule of ferric myoglobin. From the results we conclude that the first stage of the association of dodecyl sulphate to ferric myoglobin at pH 8.0 involves the binding of one molecule of detergent without alteration of the myoglobin absorption characteristics. In the second phase a further 3 or 4 molecules of dodecyl sulphate become associated. This causes the ferric myoglobin to be converted into its ferric myochrome, which exhibits the characteristic haemichrome absorption spectrum. The binding of additional dodecyl sulphate molecules to the myochrome then proceeds in numerous discrete steps, so that a great number of complexes occur simultaneously in the reaction medium. The experimental evidence indicates that the ferric myoglobin retains its native configuration in these complexes, provided the number of bound dodecyl sulphate anions does not exceed 50. The association compounds can be described as low-spin coordination complexes, in which a second imidazole originating from histidine E7, occupies the sixth coordination site of the iron atom. [ABSTRACT FROM AUTHOR]

Presents a study on free and sulphate sulphur contents and Potential of Hydrogen (pH) values in soil profiles from barren flats and mangrove swamps of Keneba in the lower Gambia river basin. Concentrations of soluble sulphate and free sulphur content in layers of soils under vegetation and barren flats; Distribution in depth and range in pH of fresh and air dried mangrove soils; Variations in the levels and pH of water table of a barren flat during the dry season.

1. Lipoamide dehydrogenase binds sodium dodecylsulphate in its dimeric state at 25 °C in two phases. The first phase, 0-0.3 g/g protein, is bound purely to hydrophobic sites; the second binding phase, 0.3-1.4 g/g protein is less well characterized and is influenced by the ionic strength and the dissociation of a protonated group with pK 6.6. The effects can be reversed by cooling to 0 °C. 2. The spectral and kinetic parameters are only affected during the second binding phase, maximal effects are obtained, with the exception of fluorescence parameters, at 1.4 g/g protein. The changes m the absorption spectrum indicate that different parts of the flavin absorption spectrum are influenced by unequal dodecylsulphate concentrations. Fluorescence polarisation shows that FAD becomes less tightly bound. Upon prolonged incubation it dissociates. 3. Binding of dodecylsulphate has a large influence on the hydrodynamic parameters. Viscosity measurements indicate the existence of asymmetrical molecules; the sedimentation constant declines from 5.8 S to 2.6 S after an increase to 8.9 S. The results show that a dimeric dodecylsulphate · enzyme complex can be reactivated by removal of dodecylsulphate at 0 °C, the monomeric dodecylsulphate · protein complex remains reactive. [ABSTRACT FROM AUTHOR]

The article presents a study about the effects of waterlogging on the growth of Molinia caerulea and Eriophorum vaginatum. This paper focuses on an investigation of the yield and root penetration of Eriophorum vaginatum in comparison with the capacity of Molinia caerulea to do the same in various conditions. Chloride added nutrients showed a significant increase in yield for both species. Sulphates in nutrients showed different result. Chemical analysis of plant materials in aqueous extracts of peat conditions are revealed.

The article presents a study regarding the oxidation-reduction potentials in muds, natural waters, and waterlogged soils. The diphenylamine reaction is positive and ferrous iron disappears in muds, and wet soils at above the potential of 350 MV. Below this potential, the ferrous iron is detectable and ammonia manages to replace nitrate and sulphides to sulphates in natural waters. Moreover, potentials estimated with oxidation-reduction indicators correspond with electrode potentials in critical range.

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The aim of the investigation was to identify a readily exchangeable fraction of sulfate in wheat roots and to study the nature of the fraction and its possible connection to the active mechanism for sulfate uptake. The amount of sulfate absorbed during the initial phase of uptake was higher in plants with a low sulfate status (low sulfate plants) than in plants with a high sulfate status (high sulfate plants). By adding selenate to the test solution, the same amount of sulfate belonging to this phase was obtained both in high sulfate plants and in low sulfate plants. The variations between plants of different sulfate status were believed to be due to different capacities for labile binding of sulfate to positive sites in the roots. Selenate replaced sulfate at these sites. By leaching experiments, the positive sites were shown to be located on or outside of a very delicate barrier in the cells. The maintenance of the positive sites was demonstrated to be dependent on concurrent metabolism by adding 2,4-dinitrophenol to the test solution and by varying the root temperature. The amount of sulfate bound to positive sites in labile binding was shown to be dependent on the PH of the test solution. At low sulfate concentrations in the test solutions, there was a quantitative connection between the magnitude of the labile-bound fraction and the rate of active uptake into the symplasm. At higher sulfate concentrations than 0.1 mM, sulfate positive sites of lower affinity to sulfate were believed to disturb the quantitative connection mentioned above. [ABSTRACT FROM AUTHOR]

The action of streptomycin sulfate (SS) on the growth of germinating seeds was investigated. It inhibited root growth more than shoot growth. Chemical analysis of roots indicated that nucleic acids decreased but their elution pattern from a column of methylated albumin kieselghur showed no qualitative differences. SS decreased the number of cells undergoing mitosis per root tip. This number was correlated with root length. One nM N6-benzyladenine reversed the effect of SS on both root length and mitosis. Thus the effect of SS appears specific to cell division. SS failed to affect oxidative phosphorylation in isolated mitochondria so its effect on cell division would not be secondary to the inhibition of energy conservation. It's possible inhibition of enzyme activity is selective since it also failed to affect RNase activity in vitro. [ABSTRACT FROM AUTHOR]

The aim of the investigation was to study the influence of the rate of water uptake on the uptake of sulphate at supernormal rates of water flow. This was achieved by reducing the size of the root system of 42 days old Ricinus plants. The rate of water flow through the root increased 3 times by reducing the root system to 20 per cent. This did not change the retention of sulphate in the roots. The uptake of sulphate was proportional to the size of the root system and thus independent of the rate of water flow while the water uptake (transpiration) was a function of the size of the shoot and the resistance of the root. This was contrary to the conditions at a moderate rate of water flow, when water and sulphate uptake followed each other. The results are discussed in terms of the salt uptake as a series of active and passive processes. [ABSTRACT FROM AUTHOR]

The experiments showed that incorporation of S from the sulphate in the medium into normal cells of Scenedesmus was enhanced by light, relatively most in the case of lipid S and least in the inorganic sulphate fraction. The effects of light were, generally, increased by the presence of CO2 and nitrogen salts. CO2 did not significantly alter the proportions between the fractions, but the presence of nitrogen increased the formation of protein S more than the synthesis of S-containing lipids. - It is suggested that lipid S is formed as a "sink", when a step between sulphite and -SH becomes increasingly rate-limiting in the overall reduction of sulphate. Furthermore, incorporation as SO42- and as lipid S may be regulated by more or less independent processes. [ABSTRACT FROM AUTHOR]

When cells of Chlorella vulgaris take up copper from solutions of copper sulphate, potassium is released in amounts which exceed the number of equivalents of divalent copper entering the cells. This occurs for all concentrations of copper sulphate investigated. More copper was bound when the solution was applied to the cells under anaerobic conditions than was bound under aerobic conditions. The extra uptake was associated with, but not stoichiometrically related to, an increased loss of potassium by the cells. It is considered that potassium is released due to a graded response of a barrier, normally of low permeability, to increasing amounts of bound copper. This increase in the permeability of the cells is considered to be the primary toxic effect of copper, but not necessarily the most important, since it has been shown that cells which have lost a considerable proportion of their normal potassium content are still capable of subsequent growth. Most of the copper taken up by cells is bound in the divalent form. [ABSTRACT FROM AUTHOR]

Incorporation of sulphate S from the medium into the cell fractions of sulphate (excluding the apparent free space), soluble reduced S, lipid S, DNA-S, and protein S was studied with - P cells of Scenedesmus, containing 0.2–0.3 mg P/g fresh weight as compared with 3–5 mg/g for normal cells. In the early stages, uptake of sulphate to all fractions is inhibited by the presence of inorganic phosphate in the medium. Later on phosphate increases incorporation into DNA-S, and protein S; total uptake is, however, decreased during the whole experimental period. Absorption of sulphate is higher in the presence of 5 per cent CO2 in the aeration stream than in air free from CO2, in darkness as well as in light. Illumination gives variable effects, depending upon the way in which CO2 and phosphate are combined, and upon the fraction considered. Production and excretion of sulphite or hydrogen sulphide into the medium did not occur under the conditions used. The data collected are primarily concerned with the influx and incorporation processes. The metabolic chains leading to different sulphur fractions do not seem to compete strongly for any early intermediate(s) of sulphate incorporation. pH is also excluded as the cause of phosphate effects. Four different models are proposed as possible explanations for the inhibiting effects of phosphate on sulphate uptake: (A) permeability effects; (B) competition effects; (C) effects mediated via the anion respiration as envisaged by Lundegärdh; (D) effects on the PAPS producing system. These systems do not exclude each other and may well act together. [ABSTRACT FROM AUTHOR]

The incorporation of radio-sulphate into the sulphate, soluble organic S and protein S fractions bas been studied in isolated leaf pieces. Illumination increases the uptake to proteins in green but not in albina tissues. DNP inhibits accumulation more than organic-S synthesis in Crassula and wheat and to the same extent in Vallisneria, whereas cyanide and selenate in all cases inhibit incorporation into proteins more than accumulation. Increasing the external concentrations of sulphate increases ion accumulation more than the synthesis of organic S compounds but increasing the osmotic values does not influence this relation. — It is pointed out that the sulphur incorporated into proteins is derived from the external solution and not from the vacuolar sulphate and that the sulphate reduction may be coupled directly to photosynthesis. The possibility of several uptake pathways for sulphate is discussed, since the rate-limiting steps must be different for accumulation and S-protein synthesis. [ABSTRACT FROM AUTHOR]

In leaves of Crassula increasing concentrations of an osmotic agent (range investigated: 0-0.8 M mannitol) increase the type of active sulphate uptake related to illumination, whereas the accumulation in darkness is diminished. Also in Thuidium and Vallisneria different actions of a given osmotic pressure can be noted in light and darkness, whereas in wheat no differential response could be detected (only one concentration tried). It is concluded that the light and dark uptakes of sulphate are related to different structural units within the cytoplasm and these units are identified with chloroplasts and mitochondria, -- The possible ecologic significance of the findings with Crassula is pointed out. -- Work with inhibitors corroborates earlier conclusions on the different natures of the uptakes of sulphate in illuminated and non-illuminated green tissues. [ABSTRACT FROM AUTHOR]

The uptake of P32-phosphate and S35-sulphate by excised wheat roots at 1° has been examined over a range of concentrations from 2×10-5 M to 2×10-2 M for periods up to 130 minutes. (1) The results at higher concentrations of both sulphate and phosphate were consistent with an "apparent free space" of 18-20 per cent for normal roots. For phosphate-deficient roots, the "apparent free space" was 36 per cent. (2) Whereas the uptake of labelled sulphate was nearly independent of carrier sulphate concentration over the entire range, the uptake of labelled phosphate was markedly greater with reduction in carrier concentration. 5×10-4 M dinitrophenol reduced hut did not abolish this effect, which was concluded to arise from a complex of mechanism. Further work is required to establish the relative contributions of adsorption exchange and esterification, in particular. [ABSTRACT FROM AUTHOR]

The mutual effects of anions in the process of salt absorption may be synergistic or antagonistic. Synergistic effects commonly appear at low concentrations and may be caused by metabolic interferences. Phosphate and sulphate act positively on the absorption of chloride even at high concentrations. Clear antagonistic effects were observed only at high concentrations of nitrate contra chloride. [ABSTRACT FROM AUTHOR]

Simultaneous measurements have been made of water losses, and net sulphur uptake and transport in wheat plants of different ages from complete nutrient solutions containing 0.05, 0.5, or 5 mM labelled sulphate. The experiments have been arranged so as to give a comparison of conditions at low and high transpiration. — Some experiments on excised roots are also reported. The uptake and transport of sulphur to the aerial parts is due to two different processes, one "passive" dependent upon transpiration and the other "active" connected with bleeding mechanisms. As for the amount translocated, the metabolic process dominates at low external concentrations, whereas the state of things is reversed at high contents of sulphate in the medium. Especially in the case of the youngest plants, the seeds contribute materially to the passive transport mechanism. Sulphate translocated by bleeding apparently does not enter the seeds. When the transpiration stream passes the roots, the nutrient solution loses about 75 per cent of its contents of sulphur. This "sieve effect" is not due to active uptake into the root cells. — For both mechanisms concerned the root passage of ions is mainly through cell walls or cytoplasm, not through the common cell vacuoles. Also for sulphate uptake to roots, a "passive" and an "active" phase can be distinguished. Without loss of the "passive" character of the uptake, the apparent free space is 27.5 per cent in intact roots as against 18.0 per cent in excised ones. Specific binding sites for sulphate have not been found within the outer space of the wheat roots; the apparent "extra" increase of the outer space of intact wheat roots at low sulphate concentrations is probably due to an artifact. — The equilibration between AFS and nutrient solution is complete within 15 minutes. At 21°C the rates of sulphate transport by the bleeding stream as well as of metabolic uptake into the root cells are apparently determined by adsorption to carrier systems of about the same properties. — Contrary to the active uptake in peas, this process is still going on in wheat at temperatures as low as 2°C [ABSTRACT FROM AUTHOR]

A method for the cultivation of Zygnema in quantity on agar plates is described. Axenic filaments were chopped with razor blades, and 4 ml of the suspension of short filaments in nutrient medium were transferred with a syringe to 1% agarized nutrient medium plates. Filamentous growth uniformly covered agar plates in 10 days or less. [ABSTRACT FROM AUTHOR]

The effects of d-amphetamine on punished responding were studied in two experiments. In Experiment I, pigeons responded under a multiple fixed-ratio 30 response fixed-interval 5-min schedule of food presentation with 60-sec limited holds in both components. Each response was punished with electric shock, the intensity of which was varied systematically. In Experiment II, another group of pigeons responded under a multiple fixed-interval 5-min fixed-interval 5-min schedule of food presentation with 40-sec limited holds. Each response was punished with shock during one component, and every thirtieth response was punished in the other component. d-Amphetamine increased overall rates of punished responding only rarely under any of the punishment conditions; however, response rates within the fixed-interval when rates were low were increased by d-amphetamine when the shock intensity was low (Experiment I), or when responses produced shock intermittently (Experiment II). The data suggest that the effects of d-amphetamine on punished responding depend on the control rate of responding, the punishment intensity, the punishment frequency, and the schedule of food presentation.