Changes in haemolymph ion concentrations of Astacus astacus L. and Pacifastacus leniusculus (Dana) after exposure to low pH and aluminium

During exposure to soft water, acidified to pH 4.0, the haemolymph concentrations of Na⁺, K⁺, and Cl^– decreased whereas the Ca²⁺ concentration fluctuated in Astacus astacus. The haemocyte content of K⁺ decreased from 9% to 2% of the total haemolymph K⁺ content after exposure to pH 3.7 for 3 days. Within 14 days, 250 µg Al³⁺ l^–1, as Al₂(SO₄)₃ at pH 5.0, reduced the haemolymph Na⁺ content in Astacus astacus and Pacifastacus leniusculus, however, the effects were less pronounced than earlier reported for fish. Disturbed ion regulation, mainly depending on low pH, is thought to contribute to the absence of these species in acid waters.     

The nutritional ecology of larvae of Alsophila pometaria and Anisota senatoria feeding on early- and late-season oak foliage

The larvae of Alsophila pometaria (Harr.), feeding on the young foliage of oak, has a higher relative growth rate (RGR) and relative nitrogen accumulation rate (RNAR) than the larvae of Anisota senatoria (J. E. Smith), feeding on the mature foliage of oak. Although the young oak foliage is more efficiently digested by A. pometaria (higher AD's), it is not more efficiently assimilated and used for growth (no difference in ECI's). Thus, the higher growth rate of A. pometaria is due entirely to a higher consumption rate (RCR and RNCR). Young foliage is significantly higher in nitrogen and water than mature foliage, but phenol and tannin levels are comparable in young and old foliage. A. pometaria consumes the foliage of different oak species at the same rate, independent of nitrogen content, while A. senatoria increases its consumption rate in response to decreased nitrogen levels. As a result, the growth rate of A. pometaria is directly related to leaf nitrogen content, while the growth rate of A. senatoria is independent of leaf nitrogen. The two species of insects have digestive systems that are very similar biochemically, and that are well-designed for effective protein digestion. Tannins and phenols do not influence the nutrional indices of either species. We suggest that the major benefit of spring feeding is the availability of succulent, high-nitrogen foliage, and not the avoidance of high-tannin foliage. The spring feeder appears to have a feeding strategy that favors rapid growth at the expense of efficiency, while the late summer feeder has a strategy that favors efficiency over rate.

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Résumé Alimentées sur feuillage jeune de chêne, les chenilles d'Alsophila pometaria avaient un taux relatif de croissance (RGR) et un taux relatif d'accumulation d'azote (RNAR) plus élevés que les chenilles d'Anisota senatoria alimentées sur feuillage mûr de chêne. Bien que le jeune feuillage soit plus efficacement digéré par A. pometaria (AD plus élevé), il n'est pas assimilé et utilisé pour la croissance avec de meilleurs rendements (les ECI ne sont pas différents). Ainsi le taux de croissance plus élevé d'A. pometaria est dû entièrement à un taux de consommation plus important (RCR et RNCR). Le feuillage jeune est significativement plus riche en azote et en eau que le feuillage mûr, mais les niveaux de phénol et de tanins sont les mêmes. A pometaria consomme les feuilles de différentes espèces de chênes au même taux, indépendamment de la teneur en azote, tandis que A. senatoria accroît sa consommation en réponse à une diminution de la teneur en azote. Il en résulte que le taux de croissance d'A. pometaria dépend directement de la teneur en azote des feuilles, tandis que celui d'A. senatoria en est indépendant. Les systèmes digestifs des deux insectes sont biochimiquement semblables et sont efficaces pour la digestion des protéines. Les tanins et les phénols n'influent pas sur les indices nutritionnels de ces deux espèces. Nous estimons que le principal intérêt de l'alimentation printanière est la disponibilité en feuillage succulent, riche en azote, et non l'absence de feuilles à haute teneur en tanin. L'alimentation printanière semble correspondre à une strategie alimentaire qui favorise la croissance aux dépens de l'efficacité tandis que l'alimentation en fin d'été est une stratégie qui favorise l'efficacité sur la rapidité.

     

Cluster-root formation, carboxylate exudation and proton release of Lupinus pilosus Murr. as affected by medium pH and P deficiency

The study examined the interactive effect of pH and P supply on cluster-root formation, carboxylate exudation and proton release by an alkaline-tolerant lupin species (Lupinus pilosus Murr.) in nutrient solution. The plants were exposed to 1 (P₁, deficient) and 50 μM P (P₅₀, adequate) for 34 days in nutrient solution at either pH 5.6 or 7.8. Plant biomass was not influenced by pH at P₁, but at P₅₀ shoot and root dry weights were 23 and 18% higher, respectively, at pH 7.8 than at pH 5.6. There was no significant difference in plant biomass between two P treatments regardless of medium pH. Phosphorus deficiency increased significantly the number of the second-order lateral roots compared with the P₅₀ treatment. Both total root length and specific root length of plants grown at pH 5.6 were higher than those at pH 7.8 regardless of P supply. Cluster roots were formed at P₁, but cluster-root number was 2-fold higher at pH 7.8 than pH 5.6. Roots released 16 and 31% more protons at pH 5.6 and 7.8, respectively, in P₁ than in P₅₀ treatments, and the rate of proton release followed the similar pattern. At pH 5.6, citrate exudation rate was 0.39 μmol g⁻¹ root DW h⁻¹ at P₁, but was under the detection limit at P₅₀; at pH 7.8, it was 2.4-fold higher in P₁ than in P₅₀ plants. High pH significantly increased citrate exudation rate in comparison to pH 5.6. The uptake of anions P and S was inhibited at P₁ and high pH increased cations Na, Mg and Ca uptake. The results suggested that enhanced cluster-root formation, proton release and citrate exudation may account for the mechanism of efficient P acquisition by alkaline-tolerant L. pilosus well adapted to calcareous soils. Cluster-root formation and citrate exudation in L. pilosus can be altered by medium pH and P deficiency. Phosphorus deficiency-induced proton release may be associated with the reduced anion uptake, but high pH-induced proton release may be partly attributed to increased cation uptake.     

Ploidy and strain differences in seed germination of Glycine wightii at different pH levels

Summary Seeds from 27 wild strains (18 tetraploids and 9 diploids) of Glycine weightii were germinated at a pH range of 5 to 8. The differences in germination (%) between all the strains were highly significant but between pH levels they were only nearly significant (P=0.067) with no interaction between pH levels and strains. Mean germination (%) for all tetraploids seems to be slightly higher ( 2%) than that for all diploids, especially at pH's 5, 7 and 8 but this may be due to the significantly longer time ( one day) it took tetraploids to complete germination. The apparent inverse relationship between seed weight and germination (%) was not significant.Mean germination time was highly significant for strains, pH's and their interaction. Increasing mean germination (%) resulted in decreasing mean germination time among strains. Large seeds took less time to germinate especially those from some of the tetraploid strains. This indicates that it is possible to produce a variety with high germination (%), fast germination rate and possibly large seeds. If the marked difference in pH tolerance among strains will prove to be mainly hereditary, then it will be also possible to select for either specific pH tolerance or tolerance at a wide range of pH.     

Optimal conditions for hepatitis B core antigen production in shaked flask fermentation

The effects of various environmental factors such as pH (5, 6, 7, 8 and 9), temperature (30, 37 and 40°C) and rotational speed (150, 200 and 250 rpm) on the growth and the hepatitis B core antigen (HBcAg) production ofEscherichia coli W3110IQ were examined in the present study. The highest growth rate is achieved at PH 7, 37°C and at a rotational speed of 250 rpm which is 0.927 h⁻¹. The effect of pH on cell growth is more substantial compared to other parameters; it recorded a 123% different between the highest growth rate (0.927 h⁻¹) at pH 7 and lowest growth at pH 5. The highest protein yield is achieved at pH 9, rotational speed of 250 rpm and 40°C. The yield of protein at pH 7 is 154% higher compared to the lowest yield achieved at pH 5. There is about 28% different of the protein yield for theE. coli cultivated at 250 rpm compared to that at 150 rpm which has the lowest HBcAg yield. The yield of protein at 40°C is 38% higher compared to the lowest yield achieved, at 30°C.     

Hydrogenase 3 but not hydrogenase 4 is major in hydrogen gas production by Escherichia coli formate hydrogenlyase at acidic pH and in the presence of external formate

Fermenting Escherichia coli is able to produce formate and molecular hydrogen (H₂) when grown on glucose. H₂ formation is possessed by two hydrogenases, 3 (Hyd-3) and 4 (Hyd-4), those, in conjunction with formate dehydrogenase H (Fdh-H), constitute distinct membrane-associated formate hydrogenylases. At slightly alkaline pH (pH 7.5), the production of H₂ was found to be dependent on Hyd-4 and the F₀F₁-adenosine triphosphate (ATPase), whereas external formate increased the activity of Hyd-3. In this study with cells grown without and with external formate H₂ production dependent on pH was investigated. In both types of cells, H₂ production was increased after lowering of pH. At acidic pH (pH 5.5), this production became insensitive either to N,N′-dicyclohexylcarbodiimide or to osmotic shock and it became largely dependent on Fdh-H and Hyd-3 but not Hyd-4 and the F₀F₁-ATPase. The results indicate that Hyd-3 has a major role in H₂ production at acidic pH independently on the F₀F₁-ATPase.     

Influence of yeast population on characteristics of the wine obtained in spontaneous and inoculated fermentations of must from <Emphasis Type="Italic">Vitis vinifera</Emphasis> Lado

This work describes the influence of yeast population on the chemical characteristics of wine obtained by spontaneous and inoculated fermentation of must from Vitis vinifera Lado, a minor white grapevine autochthonous to Galicia (NW Spain). The study was carried out for two consecutive years. The results showed that musts derived from Lado presented a high acidity though the potential alcohol level was acceptable. The genetic diversity of S. cerevisiae strains isolated from spontaneous fermentations was low, probably due to must characteristics, although these did not interfere with the implantation of the commercial strains used. Analyses showed that the wines subsequently produced had high alcoholic levels and very high acidities (pH 3.0) as was expected from must composition. Wines obtained from spontaneous fermentations had a lower alcohol content but higher total acidity than those from inoculated fermentations. Monovarietal wines produced from Lado were poorly evaluated in sensorial tests because of their unbalanced structure and sourness; however, when they were mixed with other autochthonous white varieties with less acidity, the resulting wines were well accepted.     

Protection of photosynthetic O2 evolution against heat inactivation: the role of chloride,pH and coupling status

Heat inactivation of photosynthetic O₂ evolution was studied in isolated thylakoids from spinach (Spinacia oleracea) and mangrove (Avicennia marina) leaves. Different temperatures, salt, pH and uncoupler effects were investigated. From these results and others in the literature it was concluced that chloride loss from the membrane and, more specifically, the oxygen-evolving complex of photosystem II, may be the cause of inhibition of oxygen evolution during heat inactivation.Abbreviations Hepes 4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol - Tricine N-2-hydroxy-1, 1-bis (hydroxymethyl) ethyl glycine - EDTA ethylenediaminetetraacetic acid - FeCN K-ferricyanide     

Major and trace elements in the twig axes of Norway spruce and the relationship between twig axis and needles

Summary The concentrations of 23 elements have been determined by instrumental neutron activation analysis in the needles and axes of 1-year-old spruce twigs from 12 different sites. Although the twigs had been washed with toluene and tetrahydrofuran prior to analysis, it was found that the amounts of eight elements (Al, Cr, Eu, Fe, La, Sc, Th and V) present were predominantly due to aerosol particles still being retained on the surface of the axes. The results of the remaining 15 elements (Ba, Br, Ca, Cl, Co, Cs, Hg, K, Mg, Mn, Na, P, Rb, Sr and Zn) were not or only slightly influenced by this effect and are considered to represent their inherent concentrations within the axes. With most of these latter 15 elements there are highly significant and linear correlations between the concentrations in the needles and in the axis, which testify to the great similarity of needles and axis of a twig. The axis/needles ratios are constant for every element (except K), but the individual elements show considerable differentiation, as evidenced by their ratios, which have values between 0.5 and 2.8. Inter-element correlations in the axes are mainly found within two groups of elements. With Na, Cl and Br these correlations are probably due to different pollution levels of the different sites, whereas with Mn, Co, Rb and Cs they are due to the pH of the soil. The activity of ¹³⁷Cs from the Chernobyl fallout represents independent confirmation of the results obtained with the stable elements. With twigs sprouted before the deposition of the fallout, ¹³⁷Cs acts as a tracer for aerosol particles, whereas it forms a tracer for the stable Cs inherent to the plant with twigs sprouted after the deposition.     

Purification and properties of ATPase inhibitor from rat liver mitochondria

(1) The ATPase inhibitor protein has been isolated from rat liver mitochondria in purified form. The molecular weight determined by sodium dodecyl sulfate gel electrophoresis is approximately 9500, and the isoelectric point is 8.9.

(2) The protein inhibits both the soluble ATPase and the particle-bound ATPase from rat liver mitochondria. It also inhibits ATPase activities of soluble F₁, and inhibitor-depleted submitochondrial particles derived from bovine heart mitochondria.

(3) On particle-bound ATPase the inhibitor has its maximal effect if incubated in the presence of Mg²⁺. ATP at slightly acidic pH.

(4) The inhibitor has a minimal effect on P_i-ATP exchange activity in sonicated submitochondrial particles. However, unexpectedly the inhibitor greatly stimulates P_i-ATP exchange activity in whole mitochondria while the low ATPase activity of the mitochondria is not affected. The possible mechanism of action of the inhibitor on intact mitochondria is offered.