Population Growth Patterns of Four Species of Aphelenchoides on Fungi

Qualitative and quantitative differences in population growth patterns of Aphelenchoides rutgersi from Florida, A. sacchari from Jamaica, A. dactylocercus from Great Britain, and A. cibolensis from New Mexico were assessed on 28 species of fungi. The patterns of population growth of A. rutgersi and A. sacchari were statistically similar although not identical, and they differed considerably from those of A. dactylocercus and A. cibolensis. It is suggested that A. rutgersi and A. sacchari, from Florida and Jamaica respectively, may be more closely related to each other than to either A. dactylocercus or A. cibolensis.     

Modification of the Oligidic Medium for Axenic Culture of Aphelenchoides rutgersi

Aphelenchoides rutgersi was axenically cultured in modified Soytone, yeast extract, lyophilized chick embryo extract medium (3% ST:2% YE:20% CEE-L, w/v:w/v:v/v). Earlier formulations used 10% CEE, v/v, before the manufacturer changed the preparation. After reestablishing A. rutgersi in medium that permitted continuous subcultivadon and reproduction, a second medium was tested that contained 0.5% sucrose and 0.5% Lipid Concentrate. The commercially available Lipid Concentrate made it possible to incorporate nonaqueous soluble chemicals into the medium. In addition, 0.1% Fast Green #3 was added to both media to visually demonstrate active ingestion of nutriment.     

AMPHOTERIC COLLOIDS : IV. THE INFLUENCE OF THE VALENCY OF CATIONS UPON THE PHYSICAL PROPERTIES OF GELATIN.

1. A method is given by which the amount of equivalents of metal in combination with 1 gm. of a 1 per cent gelatin solution previously treated with an alkali can be ascertained when the excess of alkali is washed away and the pH is determined. The curves of metal equivalent in combination with 1 gm. of gelatin previously treated with different concentrations of LiOH, NaOH, KOH, NH₄OH, Ca(OH)₂, and Ba(OH)₂ were ascertained and plotted as ordinates, with the pH of the solution as abscissæ, and were found to be identical. This proves that twice as many univalent as bivalent cations combine with the same mass of gelatin, as was to be expected. 2. The osmotic pressure of 1 per cent solutions of metal gelatinates with univalent and bivalent cation was measured. The curves for the osmotic pressure of 1 per cent solution of gelatin salts of Li, Na, K, and NH₄ were found to be identical when plotted for pH as abscissæ, tending towards the same maximum of a pressure of about 325 mm. of the gelatin solution (for pH about 7.9). The corresponding curves for Ca and Ba gelatinate were also found to be identical but different from the preceding ones, tending towards a maximum pressure of about 125 mm. for pH about 7.0 or above. The ratio of maxi mal osmotic pressure for the two groups of gelatin salts is therefore about as 1:3 after the necessary corrections have been made. 3. When the conductivities of these solutions are plotted as ordinates against the pH as abscissæ, the curves for the conductivities of Li, Na, Ca, and Ba gelatinate are almost identical (for the same pH), while the curves for the conductivities of K and NH₄ gelatinate are only little higher. 4. The curves for the viscosity and swelling of Ba (or Ca) and Na gelatinate are approximately parallel to those for osmotic pressure. 5. The practical identity or close proximity of the conductivities of metal gelatinates with univalent and bivalent metal excludes the possibility that the differences observed in the osmotic pressure, viscosity, and swelling between metal gelatinates with univalent and bivalent metal are determined by differences in the degree of ionization (and a possible hydratation of the protein ions). 6. Another, as yet tentative, explanation is suggested.     

ION SERIES AND THE PHYSICAL PROPERTIES OF PROTEINS. I

1. This paper contains experiments on the influence of acids and alkalies on the osmotic pressure of solutions of crystalline egg albumin and of gelatin, and on the viscosity of solutions of gelatin. 2. It was found in all cases that there is no difference in the effects of HCl, HBr, HNO₃, acetic, mono-, di-, and trichloracetic, succinic, tartaric, citric, and phosphoric acids upon these physical properties when the solutions of the protein with these different acids have the same pH and the same concentration of originally isoelectric protein. 3. It was possible to show that in all the protein-acid salts named the anion in combination with the protein is monovalent. 4. The strong dibasic acid H₂SO₄ forms protein-acid salts with a divalent anion SO₄ and the solutions of protein sulfate have an osmotic pressure and a viscosity of only half or less than that of a protein chloride solution of the same pH and the same concentration of originally isoelectric protein. Oxalic acid behaves essentially like a weak dibasic acid though it seems that a small part of the acid combines with the protein in the form of divalent anions. 5. It was found that the osmotic pressure and viscosity of solutions of Li, Na, K, and NH₄ salts of a protein are the same at the same pH and the same concentration of originally isoelectric protein. 6. Ca(OH)₂ and Ba(OH)₂ form salts with proteins in which the cation is divalent and the osmotic pressure and viscosity of solutions of these two metal proteinates are only one-half or less than half of that of Na proteinate of the same pH and the same concentration of originally isoelectric gelatin. 7. These results exclude the possibility of expressing the effect of different acids and alkalies on the osmotic pressure of solutions of gelatin and egg albumin and on the viscosity of solutions of gelatin in the form of ion series. The different results of former workers were probably chiefly due to the fact that the effects of acids and alkalies on these proteins were compared for the same quantity of acid and alkali instead of for the same pH.     

The Influence of Environmental Factors on the Respiration of Plant-Parasitic Nematodes

Respiration of selected nematode species was measured relative to CO₂ level, temperature, osmotic pressure, humidity, glucose utilization and high ionic concentrations of sodium and potassium.In general, respiration was stimulated most by the dominant environmental factors at levels near those expected in the nematode''s "natural" habitat. Soil-inhabiting nematodes utilized O₂, most rapidly with high (1-2%) CO₂ whereas a foliar nematode (Aphelenchoides ritzemabosi) did so with 0.03% CO₂, the concentration typically found in air. Temperature optima for respiration corresponded closely to those for other activities. Ditylenchus dipsaci and Pratylenchus penetrans adults and Anguina tritici and A. agrostis second-stage larvae respired within the range of osmotic pressures from 0 to 44.8 arm and respiration of their drought-resistant stages was stimulated by increasing osmotic pressure which accompanies the onset of drought. Rehydration of A. tritici and A. agrostis larvae with RH as low as 5% stimulated measurable respiration. Glucose utilization from liquid medium by A. tritici larvae or A. ritzembosi was not detectable. Supplemental Na⁺ stimulated respiration of Anguina tritici, K⁺ did not.     

Nutrient media for plant-parasitic nematodes. VI. Nucleic acids content and nucleotide synthesis in Aphelenchoides rutgersi

The nucleic acids content of Aphelenchoides rutgersi, Hooper and Myers, was 0.9% DNA and 2.6% RNA dry weight. The DNA contained 29.5% adenine, 29.3% thymine, 22.5% guanine, and 18.8% cytosine, while the RNA was composed of 22.8% adenine, 23.0% uracil, 31.4% guanine, and 22.9% cytosine on a molar basis.The nematodes needed folic acid for reproduction regardless of the presence or absence of nucleic acid supplements in the culture medium. This was shown by including aminopterin, a folic acid antagonist in the culture medium. A 2-hr incubation of nematodes with glycine-¹⁴C (U) and orotic-5-³H acid resulted in the incorporation of ³H-label into both DNA and RNA. Only the RNA fraction contained a significant amount of ¹⁴C-label. When this RNA was fractionated, the adenine and guanine accounted for the ¹⁴C-label, while cytidylic and uridylic acids contained the ³H-label, thereby demonstrating purine and pyrimidine synthesis by A. rutgersi. The incorporation of orotic acid into the pyrimidines was 8 times higher than that of glycine into purines.     

Effect of Temperature on Expression of Resistance to Meloidogyne spp. In Common Bean (Phaseolus vulgaris)

The effect of soil temperature on the expression of resistance in several common bean lines carrying resistance to root-knot nematodes (Meloidogyne spp.) was studied under controlled temperatures in temperature tank and growth chamber conditions. Resistance to M. javanica and M. incognita race 1 in bean lines A315, A328, A445, G1805, and G2618 was stable at 24-30 C. However, there was a significant increase in reproduction of M. javanica on A315, A328, and A445 when temperature was increased from 26 to 30 C. This increase did not reflect a change from a resistant to a susceptible reaction or classification. Resistance in A315 is derived from G1805, whereas resistance in A328 and A445 is derived from G2618. Alabama No. 1, PI 165426, and PI 165435, with resistance to M. incognita race 2, were heat stressed at temperatures above 27 C. Resistance to M. incognita race 2 in Alabama No. 1 and PI 165435 was lost at 30 C, but PI 165426 supported low reproduction of M. incognita race 2 at all temperatures. Poor root development at 30 C may have been responsible, in part, for the poor development of M. incognita race 2 on PI 165426.     

Aphelenchoides rutgersi: Growth requirements for heme and purine nucleotides in crude chick embryo extract

The crude chick embryo extract (CEE) at 20% concentration (v/v) in the basal medium (M-10), enabled the growth, reproduction, and continuous culturing of Aphelenchoides rutgersi Hooper and Myers. No such growth promoting effect was found with chick embryo extract (Ultra filtrate), human gamma globulin and beta lipoprotein (Cohn fraction IV-4) when used either alone or in combination with hemin.The nematode growth factor(s) in the CEE were stable to trypsinization and temperature of 100 C for 5 min but not for 15 min. After acid treatment to pH 3.0 with sulfuric acid, the supernatant retained only partial activity. But, after treatment with perchloric acid to pH 3.0 or with activated charcoal, the CEE was completely ineffective as a growth supplement. The activity of charcoal-treated CEE has been completely recovered by addition of hemin (10 μg/ml M-10).Deletion of nucleic acid supplements from M-10 but not from the CEE did not affect the reproduction of the nematodes at all. However, the reproduction was significantly reduced when the nucleic acids were removed both from the M-10 and the CEE. Selective deletion of deoxyribonucleotides and purine-, and pyrimidinenucleotides of ribose series indicated only limited nutritional requirement for purine compounds.     

Reproduction of Bacillus stearothermophilus as a Function of Temperature and Pressure

The colony-forming ability and the rate of reproduction of Bacillus stearothermophilus were determined as a function of temperature and pressure. Colonies were formed between 39 and 70°C at atmospheric pressure and between 54 and 67°C at 45 MPa. Colonies did not form at 55.9 MPa. The rate of reproduction in broth cultures decreased with increasing pressure at all temperatures. The rate of reproduction diminished rapidly with pressure above 10.4 MPa. Therefore, increased hydrostatic pressure was not sufficient to enable B. stearothermophilus to function beyond the temperature limiting growth and reproduction at atmospheric pressure, and B. stearothermophilus should grow in naturally or artificially warmed regions of the deep sea, where the pressure is less than approximately 50 MPa, although growth rates would be low above 10 MPa.     

Modification of Resistance Expression of Phaseolus vulgaris to Meloidogyne incognita by Elevated Soil Temperatures

The effect of temperature on the reaction of susceptible (Canario Divex) and resistant (A 211) bean pure lines to Meloidogyne incognita was studied with soil temperature tanks housed in a growth chamber at 22 or 24 C. Soil temperature remained constant at 16, 22, 24, 26, 30, or 32 C in several trials. Bean line A 211 was resistant at 16 and 22 C but was susceptible at 24 C and above. Resistance to root-knot nematode reproduction was affected by a lower temperature (24 C) than was resistance to root galling (26 C) in A 211. Incubation of A 211 at 30 C for 3 and 16 days after inoculation with M. incognita resulted in a significant increase in nematode reproduction and root galling, respectively. The resistant reactions of A 211 to nematode reproduction and root galling were retained when inoculated plants were incubated at 21 C for a minimum of 16 and 23 days, respectively, prior to high temperature treatment.     

DONNAN EQUILIBRIUM AND THE PHYSICAL PROPERTIES OF PROTEINS : II. OSMOTIC PRESSURE.

1. It had been shown in previous publications that the osmotic pressure of a 1 per cent solution of a protein-acid salt varies in a characteristic way with the hydrogen ion concentration of the solution, the osmotic pressure having a minimum at the isoelectric point, rising steeply with a decrease in pH until a maximum is reached at pH of 3.4 or 3.5 (in the case of gelatin and crystalline egg albumin), this maximum being followed by a steep drop in the osmotic pressure with a further decrease in the pH of the gelatin or albumin solution. In this paper it is shown that (aside from two minor discrepancies) we can calculate this effect of the pH on the osmotic pressure of a protein-acid salt by assuming that the pH effect is due to that unequal distribution of crystalloidal ions (in particular free acid) on both sides of the membrane which Donnan''s theory of membrane equilibrium demands. 2. It had been shown in preceding papers that only the valency but not the nature of the ion (aside from its valency) with which a protein is in combination has any effect upon the osmotic pressure of the solution of the protein; and that the osmotic pressure of a gelatin-acid salt with a monovalent anion (e.g. Cl, NO₃, acetate, H₂PO₄, HC₂O₄, etc.) is about twice or perhaps a trifle more than twice as high as the osmotic pressure of gelatin sulfate where the anion is bivalent; assuming that the pH and gelatin concentrations of all the solutions are the same. It is shown in this paper that we can calculate with a fair degree of accuracy this valency effect on the assumption that it is due to the influence of the valency of the anion of a gelatin-acid salt on that relative distribution of the free acid on both sides of the membrane which Donnan''s theory of membrane equilibrium demands. 3. The curves of the observed values of the osmotic pressure show two constant minor deviations from the curves of the calculated osmotic pressure. One of these deviations consists in the fact that the values of the ascending branch of the calculated curves are lower than the corresponding values in the curves for the observed osmotic pressure, and the other deviation consists in the fact that the drop in the curves of calculated values occurs at a lower pH than the drop in the curves of the observed values.     

Combined effect of temperature and salinity on the Thermotolerance and osmotic pressure of juvenile white shrimp litopenaeus vannamei (Boone)

Thermotolerance (CTMax) was determined in L. vannamei in three salinities and five acclimation temperatures 20, 23, 26, 29 and 32 °C. In white shrimp, the CTMax was not significantly affected by salinity (P>0.05). A direct relationship was obtained between CTMax and acclimation temperature. The end point of the CTMax in L. vannamei exposed to different combinations of temperature and salinity was defined as the loss of the righting response (LRR). The acclimation response ratio (ARR) for the juveniles of white shrimp ranged from 0.42 to 0.49; values in agreement with other crustaceans from tropical and sub tropical climates. The osmotic pressure of the hemolymph was measured in control organisms and in organisms exposed to CTMax; significant differences were found in organisms maintained in 10 and 40 psu, but there were no significant differences in hemolymph osmotic pressure in those that were acclimated to 26 psu.     

Haemolymph characteristics of a copper-tolerant decapod Orconectes virilis (Hagen) (Astacidae, Crustacea)

The mean haemolymph volume in a copper-tolerant, intermoult (C2-C4) adult (more than a year old) Orconectes virilis, as determined by [14C-carboxylic] inulin dilution method, ranged from 61.17 microliters in females (mean wet body weight = 4.34 g; mean carapace length = 4.43 cm) to 61.79 microliters in males (mean wet weight = 5.73 g; mean carapace length = 4.49 cm). The mean haemolymph volume per cent varied from 14.5 (in females) to 31.1 (in males). Haemolymph from males had an average pH of 7.35, osmotic pressure of 414.1 mmol/kg H2O, and a specific gravity of 1.0603, while that from females averaged a pH of 7.48, osmotic pressure of 433.6 mmol/kg H2O and a specific gravity of 1.0469. Mean total haemocyte counts ranged from 3,434/mm3 (1,000/mm3 halinocytes, 1,125/mm3 hemi-granulocytes and 1,309/mm3 granulocytes) in males to 4,905/mm3 (1,525/mm3 halinocytes. 1,490/mm3 hemi-granulocytes and 1,890/mm3 granulocytes) in females.     

ELECTROKINETIC PHENOMENA : VII. RELATIONSHIP BETWEEN ELECTRIC MOBILITY,CHARGE, TITRATION CURVE,AND OPTICAL ROTATION OF PROTEIN

The specific rotation of egg albumin, gliadin, and gelatin (40°C.) is discussed in connection with available data on (a) mobility, (b) titration curve, and (c) osmotic pressure. It seems likely that the change in specific rotation with pH of protein solutions is proportional to the change in net charge.     

AMPHOTERIC COLLOIDS : V. THE INFLUENCE OF THE VALENCY OF ANIONS UPON THE PHYSICAL PROPERTIES OF GELATIN.

1. When we plot the values of osmotic pressure, swelling, and viscosity of gelatin solutions as ordinates over the pH as abscissæ, practically identical curves are obtained for the effect of monobasic acids (HCl, HBr, HNO₃, and acetic acid) on these properties. 2. The curves obtained for the effect of H₂SO₄ on gelatin are much lower than those obtained for the effect of monobasic acids, the ratio of maximal osmotic pressures of a 1 per cent solution of gelatin sulfate and gelatin bromide being about 3:8. The same ratio had been found for the ratio of maximal osmotic pressures of calcium and sodium gelatinate. 3. The curves representing the influence of other dibasic and tribasic acids, viz. oxalic, tartaric, succinic, citric, and phosphoric, upon gelatin are almost identical with those representing the effect of monobasic acids. 4. The facts mentioned under (2) and (3) permit us to decide between a purely chemical and a colloidal explanation of the influence of acids on the physical properties of gelatin. In the former case we should be able to prove, first, that twice as many molecules of HBr as of H₂SO₄ combine with a given mass of gelatin; and, second, that the same number of molecules of phosphoric, citric, oxalic, tartaric, and succinic acids as of HNO₃ or HCl combine with the same mass of gelatin. It is shown in the present paper that this is actually the case. 5. It is shown that gelatin sulfate and gelatin bromide solutions of the same pH have practically the same conductivity. This disproves the assumption of colloid chemists that the difference in the effect of bromides and sulfates on the physical properties of gelatin is due to a different ionizing and hydratating effect of the two acids upon the protein molecule.     

DONNAN EQUILIBRIUM AND THE PHYSICAL PROPERTIES OF PROTEINS : III. VISCOSITY.

1. Gelatin solutions have a high viscosity which in the case of freshly prepared solutions varies under the influence of the hydrogen ion concentration in a similar way as the swelling, the osmotic pressure, and the electromotive forces. Solutions of crystalline egg albumin have under the same conditions a comparatively low viscosity which is practically independent of the pH (above 1.0). This difference in the viscosities of solutions of the two proteins seems to be connected with the fact that solutions of gelatin have a tendency to set to a Jelly while solutions of crystalline egg albumin show no such tendency at low temperature and pH above 1.0. 2. The formulæ for viscosity demand that the difference in the order of magnitude of the viscosity of the two proteins should correspond to a difference in the relative volume occupied by equal masses of the two proteins in the same volume of solution. It is generally assumed that these variations of volume of dissolved proteins are due to the hydration of the isolated protein ions, but if this view were correct the influence of pH on viscosity should be the same in the case of solutions of gelatin, of amino-acids, and of crystalline egg albumin, which, however, is not true. 3. Suspensions of powdered gelatin in water were prepared and it was found, first, that the viscosity of these suspensions is a little higher than that of gelatin solutions of the same concentration, second, that the pH influences the viscosity of these suspensions similarly as the viscosity of freshly prepared gelatin solutions, and third, that the volume occupied by the gelatin in the suspension varies similarly as the viscosity which agrees with the theories of viscosity. It is shown that this influence of the pH on the volume occupied by the gelatin granules in suspension is due to the existence of a Donnan equilibrium between the granules and the surrounding solution.     

Oxidative phosphorylation in rat liver mitochondria: influence of physical parameters.

Effects of pH, temperature, ionic strength and osmotic pressure on various respiratory states and indices of oxidative phosphorylation in well coupled rat liver mitochondria have been studied. It appears that temperature and osmotic pressure are the most important physical variables, whereas ionic strength and pH were devoid of any significant influence on oxidative phosphorylation. Thus any model for oxidative phosphorylation must critically account for the differential osmotic sensitivity of respiration as well as the curious fact that ADP/O ratio increases as temperature decreases.     

Regulatory characteristics of a fructose bisphosphatase from the blue-green bacterium Anacystis nidulans.

A specific fructose 1,6-bisphosphatase (EC 3.1.3.11) has been partially purified from the obligately autotrophic blue-green bacterium Anacystis nidulans. It was most active at pH 8.0. The K_m for fructose 1,6-bisphosphate was 0.088 mm at pH 8.0 and 0.105 mm at pH 7.0; the K_m for MgCl₂ was 0.95 mm at pH 8.0. Activity at netural pH was particularly sensitive to the MgCl₂ concentration. AMP was an allosteric inhibitor, 50% inhibition being exerted by 0.058 mm AMP at pH 7.0 and 0.085 mm AMP at pH 8.O. The way in which changes in intracellular pH and the concentrations of Mg²⁺ and AMP might influence the activity of the enzyme in the Calvin cycle, the oxidative pentose phosphate pathway and in glycolysis and gluconeogenesis is discussed.     

ION SERIES AND THE PHYSICAL PROPERTIES OF PROTEINS : III. THE ACTION OF SALTS IN LOW CONCENTRATION.

1. Ions with the opposite sign of charge as that of a protein ion diminish the swelling, osmotic pressure, and viscosity of the protein. Ions with the same sign of charge as the protein ion (with the exception of H and OH ions) seem to have no effect on these properties as long as the concentrations of electrolytes used are not too high. 2. The relative depressing effect of different ions on the physical properties of proteins is a function only of the valency and sign of charge of the ion, ions of the same sign of charge and the same valency having practically the same depressing effect on gelatin solutions of the same pH while the depressing effect increases rapidly with an increase in the valency of the ion. 3. The Hofmeister series of ions are the result of an error due to the failure to notice the influence of the addition of a salt upon the hydrogen ion concentration of the protein solution. As a consequence of this failure, effects caused by a variation in the hydrogen ion concentration of the solution were erroneously attributed to differences in the nature of the ions of the salts used. 4. It is not safe to draw conclusions concerning specific effects of ions on the swelling, osmotic pressure, or viscosity of gelatin when the concentration of electrolytes in the solution exceeds M/16, since at that concentration the values of these properties are near the minimum characteristic of the isoelectric point.     

Effect of Soil Temperature and pH on Resistance of Soybean to Heterodera glycines

Soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is a major pest of soybean, Glycine max L. Merr. Soybean cultivars resistant to SCN are commonly grown in nematode-infested fields. The objective of this study was to examine the stability of SCN resistance in soybean genotypes at different soil temperatures and pH levels. Reactions of five SCN-resistant genotypes, Peking, Plant Introduction (PI) 88788, Custer, Bedford, and Forrest, to SCN races 3, 5, and 14 were studied at 20, 26, and 32 C, and at soil pH''s 5.5, 6.5, and 7.5. Soybean cultivar Essex was included as a susceptible check. Temperature, SCN race, soybean genotype, and their interactions significantly affected SCN reproduction. The effect of temperature on reproduction was quadratic with the three races producing significantly greater numbers of cysts at 26 C; however, reproduction on resistant genotypes remained at a low level. Higher numbers of females matured at the soil pH levels of 6.5 and 7.5 than at pH 5.5. Across the ranges of temperature and soil pH studied, resistance to SCN in the soybean genotypes remained stable.