Growth of Pediococcus soyae nov. sp. in Highly Concentrated Solutions of Inorganic Salts and Sugars

Pediococcus soyae nov. sp., which has an inherited salt tolerant nature, is grown in solutions of high osmotic pressure. When this strain is transferred from 0.5% salted medium to a new medium containing 18% sodium chloride, the viable counts of this organism firstly decrease from about one half to one-third of the inoculated cells, and then normal growth occurs. This indicates the occurrence of physiological adaptation at an early stage of growth.

The growth of this lactic acid bacterium is observed in concentrated solutions of various inorganic salts. The solutions containing Na⁺, K⁺, Cl^?, NO₃^? and SO₄^{– –} ions are not toxic for the organism, and the organism can grow in solutions of 133 atm. osmotic pressure, generally. However, Li⁺, Ca⁺⁺, Mg⁺⁺ and Br⁺ are, toxic for growth.

In concentrated sugar solutions, this organism also propagates well, and growth is observed in the media containing 50% glucose or 60% sucrose, osmotic pressure being 105 and 84 atm., respectively. Therefore, Pediococcus soyae nov. sp. is osmotolerant.     

Modification of foliar solute concentrations by calcium in two species of wheat stressed with sodium chloride and/or potassium chloride

The effects of saline-stresses due to different salts on growth and on foliar solute concentrations in seedlings of two species of wheat that differed in salt tolerance. Triticum aestivum L. cv. Probred and Triticum turgidum L. (Durum group) cv. Aldura, were studied. Triticum aestivum is the more salt tolerant species. The salts used were NaCl, KCI, a 1:1 mixture of NaCI and KCI, and these same monovalent cation salts but mixed with CaCI₂ at a ratio of 2:1 on a molar basis of monovalent to divalent cation salts. Growth inhibition of both species was a function of media osmotic potentials. There was a small additional inhibition of growth if KCI replaced NaCI as the salinizing salt. CaCI₂ had little or no effect on growth inhibition beyond an osmotic effect except at the most severe stress level, i.e. when Ca²⁺ concentrations may be excessive. The amounts of water-soluble Ca²⁺ were about 10 times higher in leaves of plants grown in the presence of CaCI₂ than in its absence, but its concentrations even then were approximately 10% or less of those of the monovalent cations. Including CaCI₂ in growth media resulted in a reduction in the amount of Na⁺ in leaves compared to the amounts in plants grown at the same osmotic potential but in the absence of CaCI₂. Triticum aestivum was a better Na⁺-excluder than T. turgidum. With CaCI₂ in media, (Na⁺+ K⁺) remained relatively constant or increased by small amounts as media osmotic potentials décreased. In the absence of CaCI₂₊ (Na⁺+ K⁺) increased by large amounts when media osmotic potentials were at ?0.6 and ?0.8 MPa. It is concluded that the accumulation system in leaves for monovalent cations was under feed-back control, and that this control mechanism was inhibited by high media concentrations of Na⁺ and/or K⁺. Sucrose was present at a constant amount under all growth conditions. Proline started accumulating when (Na⁺+ K⁺) exceeded a threshold value of 200 μmol (g fresh weight)^?1. Its concentration was 5 to 13% of that portion of (Na⁺+ K⁺) that exceeded the threshold value.     

Changes in growth and water-soluble solute concentrations in Sorghum bicolor stressed with sodium and potassium salts

Sorghum bicolor L. Moench, RS 610, was grown in liquid media salinized with NaCl, KCl, Na₂SO₄, K₂SO₄ or with variable mixtures of either NaCl/KCl or Na₂SO₄/K₂SO₄ at osmotic potentials ranging from 0 to -0.8 MPa. The purpose was to study the effects of different types and degrees of salinity in growth media on growth and solute accumulation. In 14-day-old plants the severity of leaf growth inhibition at any one level of osmotic potential in the medium increased according to the following order: NaCl < Na₂SO₄ < KCl = K₂SO₄. Inhibition of growth by mixtures of Na⁺ and K⁺ salts was the same as by K⁺ salts alone. Roots responded differently. Root growth was not affected by Na⁺ salts in the range of 0 to -0.2 MPa while it was stimulated by K⁺ salts. The major cation of leaves was K⁺ because S. bicolor is a Na⁺-excluder, while Na⁺ was the major cation in roots except at low Na⁺/K⁺ ratios in media. Anions increased in tissues linearly in relation to total monovalent cation, but not with a constant anion/cation ratio. This ratio increased as the cation concentrations in tissues increased. Sucrose in leaf tissue increased 75 fold in Chloride-plants (plants growing in media in which the only anion of the salinizing salts was Cl^?) and 50 fold in Sulphate-plants (the only anion of the salinizing salts was SO₄^2-). Proline increased 60 and 18 fold in Chloride- and Sulphate-plants, respectively, as growth media potentials decreased from 0 to -0.8 MPa. The concentrations of both sucrose and proline were directly proportional to the amount of total monovalent cation in the tissue. Sucrose concentrations began increasing when total monovalent cations exceeded 100 μmol (g fresh weight)^?1 (the monovalent cation level in non-stressed plants), but proline did not start accumulating until monovalent cation concentrations exceeded 200 μmol (g fresh weight)^?1. Therefore, sucrose seemed to be the solute used for osmotic adjustment under mild conditions of saline stress while proline was involved in osmotic adjustment under more severe conditions of stress. Concentrations of inorganic phosphate, glucose, fructose, total amino acids and malic acid fluctuated in both roots and leaves in patterns that could be somewhat correlated with saline stress and, sometimes, with particular salts in growth media. However, the changes measured were too small (at most a 2–3 fold increase) to be of importance in osmotic adjustment.     

Response of sugarcane to different types of salt stress

Summary Due to climatic conditions and prevailing water regime the yield and sucrose recovery in sugarcane are high in South Western India. However, excessive irrigation, poor drainage and luxuriant use of fertilizers have resulted in conversion of large fertile areas into saline lands. The salinity is due to the excess of Na⁺, Ca⁺⁺, Mg⁺⁺, SO₄ ^– and Cl^– ions. Individual salts of NaCl, Na₂SO₄, MgCl₂ and MgSO₄ were employed in culture experiments to study salt stress effect on sugarcane variety Co 740. It was observed that sulphate salinity was more toxic to sugarcane than the chloride one. Sulphate salts caused more inhibition of growth, chlorophyll synthesis, PEPCase activity, decreased the uptake of K⁺ and Ca⁺⁺ ions but stimulated nitrate reductase. The stress did not result in proline accumulation in the sugarcane cultivar Co 740. The degree of toxicity of different ions in decreasing order in sugarcane cultivar Co 740 is SO₄ ^–>Na⁺>Cl^–>Mg⁺⁺.     

Effects of root-zone solutes on Eucalyptus camaldulensis and Eucalyptus bicostata seedlings: Responses to Na+, Mg2+ and Cl-

Specific-ion effects in salt-treated eucalypts were examined with two species known to differ in salt tolerance viz. E. camaldulensis (more tolerant) and E. bicostata (less tolerant). Sand-cultured plants were irrigated with different nutrient solutions designed to impose either osmotic stress (concentrated macronutrients with balanced cations and anions) or specific ion stress from either NaCl or MgCl₂, or from nutrient solutions rich in particular ions viz. Na⁺, Mg²⁺ and Cl^- (balancing counter ions were provided in all cases). Half-strength Hoagland nutrient solution served as control. All treatments were applied at osmotic pressures of approximately 0.52 MPa by appropriate concentrations of each solution. In general, salt-induced growth reductions were greater for E. camaldulensis than for E. bicostata, although E. camaldulensis showed strongest exclusion of Na⁺, Mg²⁺ and Cl^- from shoots. Application of NaCl and concentrated macronutrients resulted in similar growth reductions. E. bicostata seedlings exposed to high Cl^- concentrations in the presence of Mg²⁺ and concentrated cations suffered significantly more shoot and root reduction than those exposed to other salts. Treatment with solution rich in Cl^- resulted in extensive leaf damage, which suggested that Cl^- may have exerted a specific effect. No specific Na⁺ effect was observed for either species, even though shoot Na⁺ concentrations were considerably higher for E. bicostata than for E. camaldulensis. Root growth was considerably less for plants treated with Mg²⁺ salts and this effect was associated with low root Ca²⁺ concentrations.     

Use of the isopiestic method to determine the osmotic pressure of concentrated nutrient solutions for the cultivation of osmophilic microorganisms

The isopiestic method was used to determine the osmotic pressure of sucrose, glucose, ethylene glycol, potassium chloride and sodium sulphate solutions used to raise the osmotic pressure of cultivation media. The method is suitable for determining π of concentrated solutions. In solutions with NaCl concentrations of less than 0.1m, the accuracy of the method fell because of the relatively high water surface tension and the low vapour pressure. The osmophilic character ofCandida utilis yeasts adapted to dense recirculated molasses mashes was studied by cultivation on synthetic medium whose osmotic pressure was raised by adding mineral salts and organic substances.     

INTERFERENCE POTENTIAL OF PLUCHEA LANCEOLATA (ASTERACEAE): GROWTH AND PHYSIOLOGICAL RESPONSES OF ASPARAGUS BEAN,VIGNA UNGUICULATA VAR. SESQUIPEDALIS

The water-soluble compounds synthesized by the weed, Pluchea lanceolata, and released by it into the soil significantly reduced seed germination, number of nodes, internode length, shoot and root lengths, nodule number and weight, and Chl a and b and Chl a/b ratio of asparagus bean plants. The pattern of accumulation of nutrients in shoot and root of asparagus bean was also affected. In contrast, the net photosynthetic rate and stomatal conductance of fully expanded leaves were higher in plants grown with treated soil. The concentrations of Mg⁺⁺, Zn⁺⁺, and PO₄^3- were higher and K⁺ was lower in shoots of plants grown with treated soil as compared to those grown with the control soil. Also, roots of plants grown with treated soil showed greater accumulation of Mg⁺⁺ and NO₃^-. Shoot/root ratio of nutrients in plants grown with control soil were higher for Zn⁺⁺, Na⁺, Ca⁺⁺, and NO₃^-, whereas plants grown with treated soil had higher ratios for PO₄^3-. These results provide evidence for allelopathic interference by P. lanceolata to the growth of asparagus bean.     

Hemolymph osmo-ionic concentrations in terrestrial crabs following desiccation

• 1.1. The hemolymph osmotic, Na⁺ K⁺, Ca⁺⁺ and Mg⁺⁺ concentrations were determined for both sexes in crabs from mangrove Ucides cordatus and Goniopsis cruentata and supralittoral Ocypode quadrala after aerial desiccation, for 10 hr.
• 2.2. There was no difference between sexes in the two mangrove crabs, but in O. quadrata the females were the most significantly affected (P < 0.01).
• 3.3. Hemolymph osmotic Na⁺, Ca⁺⁺ and Mg⁺⁺ concentrations increased significantly in desiccated ghost crabs, while K ⁺ concentration was not significantly changed. In the two mangrove crabs, only hemolymph Ca⁺⁺ concentration increased significantly, after desiccation.
• 4.4. The short time desiccation is suggested to be a device to study the steps of osmo-ionic regulation in terrestrial crabs.

     

Characterization of esophageal desalination in the seawater eel,Anguilla japonica

To characterize mechanisms of esophageal desalination, osmotic water permeability and ion fluxes were measured in the isolated esophagus of the seawater eel. The osmotic permeability coefficient in the seawater eel esophagus was 2·10^-4 cm·s^-1. This value was much lower than those in tight epithelial, although the eel esophagus is a leaky epithelium with a tissue resistance of 77 ohm·cm^-2. When the esophagus was bathed in normal Ringer solutions on both sides no net ion and water fluxes were observed. However, when mucosal NaCl concentration was increased by a factor of 3, Na⁺ und Cl^- ions were transferred from mucosa to serosa (desalination). If only Na⁺ or Cl^- concentration in the mucosal fluid was increased by a factor of 3, net Na⁺ and Cl^- fluxes were reduced to 30–40%, indicating that 60–70% of the net Na⁺ and Cl^- fluxes are coupled mutually. The coupled NaCl transport seems to be effective in desalting the luminal high NaCl. The remaining 30–40% of the total Na⁺ and Cl^- fluxes seems to be due to a simple diffusion, because these components are independent of each other and follow their electrochemical gradients, and also because these fluxes remain even after treatment with NaCN or ouabain. A half of the coupled NaCl transport could be explained by a Na⁺/H⁺–Cl^-/HCO ₃ ^- double exchanger on the apical membrane of the esophageal epithelium, because mucosal amiloride and 4.4-diisothiocyanatostilbene-2,2-disulphonic acid inhibited the net Na⁺ and Cl^- fluxes by approximately 30%. The other half of the coupled NaCl transport, which follows their electrochemical gradients, still remains to be explained.Abbreviations DIDS 4,4-diisothiocyanatostilbene-2,2-disulphonic acid - NMDG N-methyl-d-glucosamine - P _Cl Cl^- permeability coefficient - PD transepithelial potential difference - P _Na Na⁺ permeability coefficient - P _osm osinotic permeability coefficient - TALH thick ascending limb of Henle's loop     

Soybean [Glycine max (L.) merrill] embryogenic cultures: The role of sucrose and total nitrogen content on proliferation

Summary To improve proliferation of soybean cultures in liquid medium, the effects of sucrose; total inorganic nitrogen; content of No₃ ⁻, NH₄ ⁺, Ca²⁺, PO₄ ³⁻, K⁺; NH₄ ⁺/NO₃ ⁻ ratio; and medium osmotic pressure were studied using cv. Jack. Sucrose concentration, osmotic pressure, total nitrogen content, and ammonium to nitrate ratio were found to be the major factors controlling proliferation of soybean embryogenic cultures. Growth decreased linearly as sucrose concentration increased from 29.7 mM to 175.3 mM. A sucrose concentration of 29.2 mM, a nitrogen content of 34.9 mM, at 1 to 4 ammonium to nitrate ratio were found to be optimal for the fastest proliferation of soybean embryogenic cultures. There was no significant effect on proliferation of cultures when concentrations of NH₄ ⁺, Ca²⁺, PO₄ ³⁻, and K⁺ were tested in the range of 3.50 to 10.50, 1.02 to 3.06, 0.68 to 2.04, and 22.30 to 36.70 mM, respectively. The relative proliferation of embryogenic cultures of four soybean genotypes was evaluated in Finer and Nagasawa medium and in the new medium formulation. Despite genotype-specific differences in growth, the genotypes tested showed a biomass increase in the new formulation equal to 278, 269, 170, and 251% for Chapman, F138, Jack, and Williams 82, respectively, relative to their growth on standard FN medium. Due to its lowered sucrose and nitrogen content, we are referring to the new medium as FN Lite.     

Phosphate cycles in energy crop systems with emphasis on the availability of different phosphate fractions in the soil

The growing cells of hydroponic maize roots expand at constant turgor pressure (0.48 MPa) both when grown in low-(0.5 mol m^-3 CaCl₂) or full-nutrient (Hoagland's) solution and also when seedlings are stressed osmotically (0.96 MPa mannitol). Cell osmotic pressure decreases by 0.1–0.2 MPa during expansion. Despite this, total solute influx largely matches the continuously-varying volume expansion-rate of each cell. K⁺ in the non-osmotically stressed roots is a significant exception-its concentration dropping by 50% regardless of the presence or absence of K⁺ in the nutrient medium. This corresponds to the drop in osmotic pressure. Nitrate appears to replace Cl^- in the Hoagland-grown cells.Analogous insensitivity of solute gradients to external solutes is observed in the radial distribution of water and solutes in the cortex 12 mm from the tip. Uniform turgor and osmotic pressures are accompanied by opposite gradients of K⁺ and Cl^-, outwards, and hexoses and amino acids, inwards, for plants grown in either 0.5 mol m^-3 CaCl₂ or Hoagland's solution (with negligible Cl^-). K⁺ and Cl^- levels within both gradients were slightly higher when the ions were available in the medium. The gradients themselves are independent of the direction of solute supply. In CaCl₂ solution all other nutrients must come from the stele, in Hoagland's solution inorganic solutes are available in the medium.24 h after osmotic stress, turgor pressure is recovered at all points in each gradient by osmotic adjustment using organic solutes. Remarkably, K⁺ and Cl^- levels hardly change, despite their ready availability. Hexoses are responsible for some 50% of the adjustment with mannitol for a further 30%. Some 20% of the final osmotic pressure remains to be accounted for. Proline and sucrose are not significantly involved. Under all conditions a standing water potential step of 0.2 MPa between the rhizodermis and its hydroponic medium was found. We suggest that this is due to solute leakage.Abbreviations EDX energy dispersive X-ray microanalysis - water potential - 11-1 cell osmotic pressure - P turgor pressure     

Growth stimulation and inhibition by salt in relation to Na<Superscript>+</Superscript> manipulating genes in xero-halophyte <Emphasis Type="Italic">Atriplex halimus</Emphasis> L.

In the present study, Na⁺ manipulating genes could contribute not only to ion homeostasis but also to growth stimulation with exposing the halophyte Atriplex halimus L. to moderate NaCl concentration. The stimulation of growth was attributed to Na⁺ accumulation inside the vacuole leading to increase leaf cell size as well as accelerate leaf cell division. Increasing the assimilatory surface could result in enhancing the photosynthetic rate. The reduction of A. halimus growth compared to optimum growth at 50 and 200 mM NaCl could be attributed to osmotic effect rather than the ionic one of salt stress. The inhibition of photosynthesis seemed to be resulted from limitation of CO₂ due to the osmotic effect on stomatal conductance rather than the activity loss of photosynthetic machinery. The depletion of starch content along with the increase in sucrose content could imply that photosynthesis may be a limiting for A. halimus growth. The fast coordinate induction of Na⁺ manipulating genes could reveal that the tolerance of A. halimus to high concentrations evolved from its ability to regulate and control Na⁺ influx and efflux. V-H ⁺-PPase may play a vital role in A. halimus tolerance to osmotic and/or ionic stress due to its kinetics of induction. It seemed that H⁺-ATPase plays a pivotal role in A. halimus tolerance to stress due to the increase in its protein level was detected with all NaCl concentrations as well as with PEG treatments. Both of these genes might be useful in improving stress tolerance in transgenic crops.     

Effects of NaCl salinity on growth, morphology, photosynthesis and proline accumulation of Salvinia natans

The effects of NaCl salinity on growth, morphology and photosynthesis of Salvinia natans (L.) All. were investigated by growing plants in a growth chamber at NaCl concentrations of 0, 50, 100 and 150 mM. The relative growth rates were high (ca. 0.3 d⁻¹) at salinities up to 50 mM and decreased to less than 0.2 d⁻¹ at higher salinities, but plants produced smaller and thicker leaves and had shorter stems and roots, probably imposed by the osmotic stress and lowered turgor pressure restricting cell expansion. Na⁺ concentrations in the plant tissue only increased three-fold, but uptake of K⁺ was reduced, resulting in very high Na⁺/K⁺ ratios at high salinities, indicating that S. natans lacks mechanisms to maintain ionic homeostasis in the cells. The contents of proline in the plant tissue increased at high salinity, but concentrations were very low (<0.1 μmol g⁻¹ FW), indicating a limited capacity of S. natans to synthesize proline as a compatible compound. The potential photochemical efficiency of PSII (F_v/F_m) of S. natans remained unchanged at 50 mM NaCl but was reduced at higher salinities, and the photosynthetic capacity (ETR_max) was significantly reduced at 50 mM NaCl and higher. It is concluded that S. natans is a salt-sensitive species lacking physiological measures to cope with exposure to high NaCl salinity. At low salinities salts are taken up and accumulate in old leaves, and high growth rates are maintained because new leaves are produced at a higher rate than for plants not exposed to salt.     

Mineral ion composition and osmotic relations of Atriplex confertifolia and Eurotia lanata

Summary Periodic collections of Atriplex confertifolia and Eurotia lanata leaf tissue throughout the growing season were analyzed for osmotic potential, water content, and concentration of Na⁺, K⁺, soluble Ca⁺⁺, Cl^-, and SO₄ ^-- ions. Ionic concentrations of these two species exhibited marked similarities to corresponding values for European members of the same genera. Atriplex confertifolia, like many other Atriplex species, behaves as an alkali halophyte and accumulates Na⁺, while E. lanata appears to favor accumulation of K⁺ as did its European counterpart, E. ceratoides.The analyses showed a much broader range of tissue moisture contents and osmotic potentials during the season for Atriplex than for Eurotia. The differences in leaf water relations between the two species are possibly related to the greater NaCl accumulation by Atriplex as compared to Eurotia. An apparent advantage exists for Atriplex in prolonging physiological activity and carbon gain in the dry portion of the late summer by NaCl accumulation.     

Photosynthetic limitations of a halophyte sea aster (<Emphasis Type="Italic">Aster tripolium</Emphasis> L) under water stress and NaCl stress

To understand the mechanisms of salt tolerance in a halophyte, sea aster (Aster tripolium L.), we studied the changes of water relation and the factors of photosynthetic limitation under water stress and 300 mM NaCl stress. The contents of Na⁺ and Cl^- were highest in NaCl-stressed leaves. Leaf osmotic potentials (Ψ _s) were decreased by both stress treatments, whereas leaf turgor pressure (Ψ _t) was maintained under NaCl stress. Decrease inΨ _s without any loss ofΨ _t accounted for osmotic adjustment using Na⁺ and Cl^- accumulated under NaCl stress. Stress treatments affected photosynthesis, and stomatal limitation was higher under water stress than under NaCl stress. Additionally, maximum CO₂ fixation rate and O₂ evolution rate decreased only under water stress, indicating irreversible damage to photosynthetic systems, mainly by dehydration. Water stress severely affected the water relation and photosynthetic capacity. On the other hand, turgid leaves under NaCl stress have dehydration tolerance due to maintenance of Ψ _t and photosynthetic activity. These results show that sea aster might not suffer from tissue dehydration in highly salinized environments. We conclude that the adaptation of sea aster to salinity may be accomplished by osmotic adjustment using accumulated Na⁺ and Cl^-, and that this plant has typical halophyte characteristics, but not drought tolerance. Electronic Publication     

The effect of silver and other metal ions on the in vitro growth of root-rotting Phytophthora and other fungal species

A range of metal ions and the oxoanion WO₄^2-were toxic to zoospores of Phytophthora nicotianae parasitica in the order: Ag⁺ > Cu⁺⁺ > WO₄^2-> Ni⁺ > Co⁺⁺ > Zn⁺. The LD₅₀ for Ag⁺, 0.11 μM (11.4 ppb), compared with 1.84 μm (117 ppb) for Cu⁺⁺. Silver was similarly toxic to a range of pathogens including Pythium aphanidermatum, Thielaviopsis basicola and Fusarium oxy-sporum f.spp. Most zoospores of Phytophthora spp. were killed by Ag⁺ in the range 46–460 nM (5–50 ppb), bursting at the higher concentrations. A small sub-population of most propagules exhibited greater tolerance to silver than the whole. In 0.93 μM (100 ppb) Ag⁺ 1.4% of P. nicotianae parasitica zoospores survived but were all killed at 500 ppb. A population of P. cryptogea (1.9%) surviving 0.47 μm (50 ppb) were killed at 0.93 μM (100 ppb). Zoospore cysts and germlings showed the same sensitivity to silver. Oospores were mostly killed over the range 0.23–0.93 μm (25–100 ppb) Ag⁺, some surviving up to the lethal concentration of 9.26 μM (1000 ppb). Mycelium of P. cryptogea was generally less sensitive, with some growth occurring at 9.26 μm (100 ppb). Zoosporangiogenesis was unaffected over the range 0.47–4.65 μm (50–500 ppb). Toxicity increased with increased pH over the range 5.0–6.5. Ionic silver was lost from solution during a microscope slide bioassay by binding to the glass surface. In the presence of chloride ions, colloidal AgCl formed which was equally toxic to P. cryptogea. Silver and AgCl were further lost from solution by colloidal agglomeration - Ostwald ripening - and by AgCl adsorption to glass. Silver, < 90 nM (10 ppb) Ag⁺ as AgNO₃ and particles of silver chloride were both strongly attractive to zoospores of P. cryptogea. Spores burst or failed to germinate on entering lethal concentrations. The results are discussed in the context of the use of silver salts to control Phytophthora root-rot pathogens and the importance of ion availability in in vitro toxicity assays.     

Triple helix formation and disulphide bonding during the biosynthesis of glomerular basement membrane collagen.

White erythrocyte membranes, or ghosts, were monoconcave discocytes when incubated in 50mM N-tris (hydroxymethyl) methyl-2-aminoethane sulfonic acid titrated to pH 7.4 with triethanolamine. If 3mM MgCl₂ was included in the incubation medium, the ghosts were predominantly echinocytes. The echinocytic form could also be induced by Co⁺⁺, Ni⁺⁺, Li⁺, Na⁺, K⁺, $\text{NH}{}_4{}^{\mathrm{+}}$ and tetramethylammonium ion, all as chloride salts. The concentration of cation necessary for 50% of the ghosts to be echinocytes was correlated with the hydrated charge density of the cation with the most highly charged cations being the most effective. The cations Ca⁺⁺, Sr⁺⁺, Ba⁺⁺ and La⁺⁺⁺, (also as chloride salts) did not induce the normal echinocytic form, but at high levels induced a few misshapen forms with some resemblance to echinocytes. Instead Ca⁺⁺, Sr⁺⁺, Ba⁺⁺ and La⁺⁺⁺ suppressed the formation of echinocytes in the presence of Mg⁺⁺ and other ions. This suggests the presence of a specific Ca⁺⁺ binding site important to shape control in the erythrocyte membrane.     

Prolactin regulation in the coho salmon,Oncorhynchus kisutch

Summary Parr and smolt sea water acclimated coho salmon,Oncorhynchus kisutch were subjected to gradual and direct transfers to fresh water. Plasma osmotic pressure, Na⁺, K⁺, Ca⁺⁺ and Mg⁺⁺ were similar in freshwater (FW) fish and seawater (SW) transferred controls for the 24 h following transfer. In spite of the similarity in osmotic pressure and ion levels, plasma cortisol concentrations were significantly increased immediately following salinity change while both pituitary and plasma prolactin decreased indicating enhanced secretion by the pituitary and clearance from the blood. In vitro experiments showed greater incorporation of tritiated leucine into prolactin (PRL) cells immediately after transfer to FW while prolactin injections into intact fish lowered activity in rostral pars distalis (RPD) cells as measured by the same technique, providing evidence of hormonal feedback. These experiments show that the increased synthesis and release of PRL that occurs in coho following movement into FW is not obviously correlated with plasma osmotic pressure, Na⁺ or Ca⁺⁺ concentrations as has been observed in other species of teleosts.Abbreviations FW freshwater - SW seawater - PRL prolactin - RPD rostral pars distalis     

Formation and role of glycine betaine in the moderate halophile Vibrio costicola

The moderate halophile Vibrio costicola, growing on a chemically-defined medium, transformed choline into glycine betaine (betaine) by the membrane-bound enzyme choline dehydrogenase and the cytoplasmic enzyme betainal (betaine aldehyde) dehydrogenase. Choline dehydrogenase was strongly induced and betainal dehydrogenase less strongly induced by choline. The formation of these enzymes was also regulated by the NaCl concentration of the growth medium, increasing with increasing NaCl concentrations. Intracellular betaine concentrations also increased with increasing choline and NaCl concentrations in the medium. This increase was almost completely blocked by chloramphenicol, which does not block the increase in salt-tolerant active transport on transfer from a low to a high salt concentration.Choline dehydrogenase was inhibited by chloride salts of Na⁺, K⁺, and NH _inf4 ^su+ , the inhibition being due to the Cl^- ions. Betainal dehydrogenase was stimulated by 0.5 M salts and could function in up to 2.0 M salts.Cells grew as well in the presence as in the absence of choline in 0.5 M and 1.0 M NaCl, but formed no intracellular betaine. Choline stimulated growth in 2.0 M NaCl and was essential for growth in 3.0 M NaCl. Thus, while betaine is important for some of the adaptations to high salt concentration by V. costicola, it by no means accounts for all of them.Abbreviations CDMM chemically-defined minimal medium - PPT proteose-peptone tryptone medium - SDS sodium dodecyl sulfate Deceased, 1987     

Stimulation of heterotrophic and autotrophic growth ofSphaerotilus discophorus by manganous ions

Growth ofS. discophorus in a casamino acids-mineral salts medium was stimulated 3-fold on addition of 0.05% MnSO₄·H₂O to the medium. Growth was measured by determinations of total nitrogen, protein and DNA on the washed cellular material.Autotrophic growth ofS. discophorus strain 43-R was obtained in an inorganic mineral salts medium supplemented with trace amounts of the essential vitamins, thiamin, biotin and cyanocobalamin and with Mn⁺⁺ as the sole available source of energy. A gas mixture of 5% CO₂-95% air was bubbled continuously through the cultures during incubation. Concomitant with growth, Mn⁺⁺ disappeared from the cultures and MnO₂ was formed.