Organic Phosphate Concentrations Research Articles

Chemical Fractionation and Heavy Metal Distribution in Agricultural Soils, North of Jordan Valley

Thirty-nine soil samples were collected on a grid pattern from the north of the Jordan Valley. These samples were subjected to geochemical, mineralogical and textural analyses. The investigated soil is characterized by medium texture and to a less extent moderately coarse and coarse texture. The value of TDS shows a slight increase in the southern part of the study area toward the Dead Sea due to the increase in temperature and decrease of the amount of precipitation. The organic matter content and P 2 O 5 values show significant variations that coincide with agricultural activity and application of fertilizers and pesticides in the investigated area. In the samples collected, CEC values are slightly decreased from north to south parts of the study area where the abundance of organic matter and clay minerals are low. The study found that the enrichment factors of the measured heavy metals Pb, Cd, As and Hg are 2.8, 11.9, 20 and 17 respectively. Accordingly, the soil of the study area can be considered moderately contaminated with respect to As and Hg and uncontaminated to moderately contaminated with respect to Pb and Cd. The distribution of the measured heavy metals are affected by various geochemical factors including pH, clay content, cation exchange capacity, organic matter content and total phosphate content. Sequential extraction procedure was used in order to determine the percentage of the Pb, Cd and As present in five geochemical fractions of the examined soil samples. It was found that Pb and As are mainly associated with the residual phases and are relatively immobile. On the other hand Cd is enriched in the carbonate phase of the analyzed soil samples. Based on the sequential extraction procedure it is possible to suggest the sequence of metal mobility as: Cd > Pb > As.

Development and Application of a Phosphorus Model for a Shallow Oxbow Lake

A three-dimensional numerical model was developed for simulating the phosphorus concentration in shallow lakes. In this model, the computational domain was divided into two parts: the water column and the bed sediment layer. The processes of mineralization, settling, adsorption, desorption, bed release (diffusion), growth, and death of phytoplankton were taken into account, and the concentration of organic phosphorus, phosphate, and related water quality constituents was simulated. The concentrations of adsorbed (particulate) and dissolved phosphate due to adsorption-desorption were calculated using two formulas derived based on the Langmuir equation. The release rate of phosphorus from the bed sediment layer was calculated by considering the effects of the concentration gradient across the water-sediment interface, pH, temperature, dissolved oxygen concentration, and flow conditions. The adsorption and desorption of phosphate from sediment particles, as well as its release from bed sediment, were verified using laboratory experimental data. The model was calibrated and applied to Deep Hollow Lake in the Mississippi alluvial plain. The simulated trends and magnitudes of phosphorus concentration were compared with field observations. The simulation results show that there are strong interactions between sediment-related processes and phosphorus concentration.

Phosphate enrichment in the northern Gulf of Aqaba: Regulation by carbonate sediments and impact on nitrogen elevation

The effect of carbonate sediment in regulating phosphate concentrations in sea water was investigated by laboratory incubation experiments using different sediment types. Incubation experiments were made with two types of sediments: uncontaminated sediment from a marine reserve and contaminated sediment with deposited phosphate powders. Fluxes of inorganic nitrogen and phosphate were estimated from linear regressions of solute concentrations over incubation periods. Ammonium and phosphate fluxes were about twofold higher in the uncontaminated sediment that had significantly lower organic carbon and total phosphate concentrations than in the phosphate-contaminated sediment. To test the effect of dissolved phosphate on increasing nitrogen fixation, additional incubation experiments were carried out using treated carbonate and silicate sediments with added dissolved phosphate (20 μM). Incubations were made under sterile conditions with HgCl2 added to distinguish between biologically enhanced processes and pure physicochemical processes. The adsorption rate of phosphate onto carbonate sediment was about twice that onto silicate sediments. No nitrogen elevation either as ammonium or as nitrate was observed in the soluble phosphate enrichment incubations. In conclusion, this study demonstrates the importance of the regulation of soluble phosphate concentrations in carbonate sediment environments where the carbonate sediment acts as a buffering system keeping soluble phosphate concentrations at certain steady-state levels. The study also demonstrates the lack of evidence on enhancement of nitrogen concentrations due to the increase phosphate concentrations.

Integrating a membrane and a fluidized pellet reactor for removing hardness: effects of NOM and phosphate

A novel treatment process combining a membrane with outside-in flow configuration and a fluidized pellet rector for removing hardness was studied. The effects of influent water quality, e.g., concentrations of natural organic matter (NOM) and phosphate along with the hydrophobicity of NOM, on the hardness removal efficiency of the novel process were investigated. The hardness removal efficiency decreases with increasing NOM concentration. However, the NOM removal efficiency is independent of NOM concentration and is related to the hydrophobicity of NOM samples. Raw water containing phosphate has adverse impact on the hardness removal efficiency, which decreases from 85% for treating water containing no phosphate to only 38% and 14% for water containing 0.33 mg/L and 1.63 mg/L of phosphate, respectively.

Red blood cell pH, the Bohr effect, and other oxygenation‐linked phenomena in blood O2 and CO2 transport

The discovery of the S-shaped O2 equilibrium curve and the Bohr effect in 1904 stimulated a fertile and continued research into respiratory functions of blood and allosteric mechanisms in haemoglobin (Hb). The Bohr effect (influence of pH/CO2 on Hb O2 affinity) and the reciprocal Haldane effect (influence of HbO2 saturation on H+/CO2 binding) originate in the Hb oxy-deoxy conformational change and allosteric interactions between O2 and H+/CO2 binding sites. In steady state, H+ is passively distributed across the vertebrate red blood cell (RBC) membrane, and intracellular pH (pHi) changes are related to changes in extracellular pH, Hb-O2 saturation and RBC organic phosphate content. As the Hb molecule shifts between the oxy and deoxy conformation in arterial-venous gas transport, it delivers O2 and takes up CO2 and H+ in tissue capillaries (elegantly aided by the Bohr effect). Concomitantly, the RBC may sense local O2 demand via the degree of Hb deoxygenation and release vasodilatory agents to match local blood flow with requirements. Three recent hypotheses suggest (1) release of NO from S-nitroso-Hb upon deoxygenation, (2) reduction of nitrite to vasoactive NO by deoxy haems, and (3) release of ATP. Inside RBCs, carbonic anhydrase (CA) provides fast hydration of metabolic CO2 and ensures that the Bohr shift occurs during capillary transit. The formed H+ is bound to Hb (Haldane effect) while HCO3- is shifted to plasma via the anion exchanger (AE1). The magnitude of the oxylabile H+ binding shows characteristic differences among vertebrates. Alternative strategies for CO2 transport include direct HCO3- binding to deoxyHb in crocodilians, and high intracellular free [HCO3-] (due to high pHi) in lampreys. At the RBC membrane, CA, AE1 and other proteins may associate into what appears to be an integrated gas exchange metabolon. Oxygenation-linked binding of Hb to the membrane may regulate glycolysis in mammals and perhaps also oxygen-sensitive ion transport involved in RBC volume and pHi regulation. Blood O2 transport shows several adaptive changes during exposure to environmental hypoxia. The Bohr effect is involved via the respiratory alkalosis induced by hyperventilation, and also via the pHi change that results from modulation of RBC organic phosphate content. In teleost fish, beta-adrenergic activation of Na+/H+ exchange rapidly elevates pHi and O2 affinity, particularly under low O2 conditions.

Environmental Assessment of Water, Sediment and Plants in the Mankyeong River, ROK

This study was carried out to evaluate water quality, sediment and plant vegetation in eight tributaries of the Mankyeong River for enhancement of natural purification. Among the tributaries, the Iksancheon water had the highest concentration of BOD, T-N and NH4-N due to inflow of swine wastes from the livestock district. The Yucheon water had the highest level of electrical conductivity and SO4(2-) due to inflow of mis-treated wastewater from industrial districts. The Tabcheon had generally similar concentrations of nitrogen and phosphate to that of the upstream of the Mankyeong River: agricultural activity along the Tabcheon appeared to have little negative influence to the water quality. Among various sediments, concentration of organic matter, nitrogen and phosphate were high in the Iksancheon and the Yucheon due to the livestock wastes and industrial wastes. There were 282 species of plants during summer with 43 aquatic plants, 57 hydrophytes, 178 waterside plants and 4 terrestrial plants. Some plant resources were recommended due to much absorption of nitrogen and phosphate for enhancement of natural purification. C. demersum and H. verticillata were recommended in the submerged aquatic plants, H. dubia, N. indica and N. subinteperrimum in the floating leaf aquatic plants, P. communis, Z. latifolia and T. orientalis in the emerged aquatic plants, C. scutata and P. distichum in the waterside plants.

The interaction of haemoglobin, magnesium, organic phosphates and band 3 protein in nucleated and anucleated erythrocytes.

The anion influx was measured in order to study the interaction among organic phosphates, magnesium, haemoglobin and the N-terminal of the cytoplasmic domain of band 3 protein in human, chicken and trout erythrocytes. The rate constant for SO(4)(2-) influx in human and trout erythrocytes increased significantly when it was measured with an increased concentration of intracellular Mg(2+). The SO(4)(2-) influx was also measured in human erythrocyte ghosts in the presence and absence of Mg(2+). The smaller activation provoked by Mg(2+) in ghosts could be caused by the presence of a small quantity of haemoglobin which remained inside. The SO(4)(2-) uptake in chicken erythrocytes in the presence and in absence of Mg(2+) was characterized by very similar rate constants. The results suggest that the small increase in intracellular Mg(2+) in the erythrocytes involves an increase in the formation of Mg(2+)-ATP and Mg(2+)-2,3 BPG complexes reducing the affinity of the organic phosphates for Hb. This new situation may influence the functions of the anion transporter with consequent variations of SO(4)(2-) influx throughout the erythrocyte membrane in human and in trout erythrocytes, whereas in chicken RBCs this function cannot occur and, in fact, no increase in sulphate influx was noticeable. The measurement of Hb/O(2) affinity by the use of alternating fixed and variable concentrations of organic phosphates and Mg(2+), confirms the interactions between these elements and their effect on the mechanism of the affinity. When we measured the sulphate influx in the presence of DIDS we found some differences in the three types of cells.

Changes in seawater nutrient concentrations during purse seine fishing for sardine Sardina pilchardus off northern Portugal

Surface water samples were collected before, during and after purse seining for sardine off northern Portugal (12 sets) to test the hypothesis that fishing can lead to changes in local nutrient concentrations. Ammonia, urea, residual organic nitrogen and phosphate concentrations signifi- cantly increased during fishing and the increase was a pulse event associated with the drying-up of the net (when fish density in the net is highest). Concentrations at the end of fishing (on average 40 min after drying-up) were lower than peak values but still significantly higher than the original concentrations. Nitrate and nitrite did not alter during the fishing operation, further suggesting that the observed increase in nitrogen and phosphorus compounds is of biological origin. There was no significant relation between peak concentrations and fish catch, suggesting that the fisheries- associated stimulus does not affect equally all the fish in the net (relative position in the net and fish condition may influence the probability of release). Published data on sardine nitrogen excretion and observations on nutrient concentrations in sardine body parts indicate that enhanced excretion of nitrogenous waste stimulated from stress reactions could account for the observed increase in ammo- nia and urea. Skin mucus release from scale loss (occurring extensively during the drying-up) is the most likely source of phosphorus, while forced evacuation of partly digested food items from the intestine or regurgitation from the stomach (both associated with the mechanical pressure and contact among fish and with the net walls at the end of drying-up) probably also contribute to the increase in residual organic nitrogen.

Increased blood oxygen affinity during digestion in the snake Python molurus.

Many snakes exhibit large increases in metabolic rate during digestion that place extensive demands on efficient oxygen transport. In the present study, we describe blood oxygen affinity following three weeks of fasting and 48 h after feeding in the Burmese python (Python molurus). We also report simultaneous measurements of arterial blood gases and haematological parameters. Arterial blood was obtained from chronically implanted catheters, and blood oxygen-dissociation curves were constructed from oxygen content measurements at known oxygen partial pressure (P(O(2))) values at 2% and 5% CO(2). Arterial pH remained constant at approximately 7.6 after feeding, but digestion was associated with an approximately 6 mmol l(-1) increase in [HCO(3)(-)], while CO(2) partial pressure (P(CO(2))) increased from 2.21+/-0.13 kPa in fasted animals to 2.89+/-0.17 kPa at 48 h after feeding. Blood oxygen affinity in vivo was predicted on the basis of pH in vivo and the blood oxygen-dissociation curves obtained in vitro. The blood oxygen affinity in vivo increased during digestion, with P(50) values decreasing from 4.58+/-0.11 kPa to 3.53+/-0.24 kPa. This increase was associated with a significant decrease in the red blood cell [NTP]/[Hb(4)] ratio (relationship between the concentrations of organic phosphates and total haemoglobin) and a significant decrease in mean cellular haemoglobin content, which is indicative of swelling of the red blood cells. Our data for blood oxygen affinity and arterial oxygen levels, together with previously published values of oxygen uptake and blood flows, allow for a quantitative evaluation of oxygen transport during digestion. This analysis shows that a large part of the increased metabolism during digestion is supported by an increased venous extraction, while arterial P(O(2)) (Pa(O(2))) and haemoglobin saturation do not vary with digestive status. Thus, we predict that venous P(O(2)) (Pv(O(2))) is reduced from a fasting value of 5.2 kPa to 1.6 kPa during digestion.

Organic and inorganic phosphorus as characterized by phosphorus-31 nuclear magnetic resonance in subtropical soils under management systems

The area under no tillage system largely increased in the last decade in southern Brazil. The increase in total phosphorus (P), mainly in the topsoil layer in no-tillage management, is distributed in different inorganic and organic forms. The 31P nuclear magnetic resonance (NMR) technique can improve the understanding of the dynamics of phosphorus by identifying the structure of the major groups of this element in soils. This research determined the organic and inorganic phosphorus groups, identified by NMR and by chemical analysis in three subtropical soils under conventional and no-tillage systems. Samples of two soil layers from three long-term experiments located in the state of Rio Grande do Sul, southern Brazil, were used. The first experiment was set up in 1979, in a very clayey Rhodic Hapludox; the second, in 1983, in a clayey Rhodic Hapludox, and the third, in 1985, in a sandy clay loam Rhodic Paleudult. Total, inorganic, and organic P, biomass-associated and NaHCO3 extracted P were determined by chemical analysis and the NaOH+EDTA extract was submitted to 31P NMR for organic and inorganic determination. There was an overestimation of the organic phosphate content by the ignition method when compared with the NMR in surface-active soils (Hapludoxes). The NMR method allowed a good characterization of organic and inorganic phosphate groups in soils. Inorganic orthophosphate was the dominant P form; the organic P portion was higher in the low surface-active (Paleudult) soil, with a dominance of monoester over diester P, independently of soil type, tillage, or depth. A significant positive correlation was found between diester and microbial biomass P content.

Effects of inorganic and organic phosphate exposure on aspects of reproduction in the common sea urchin Lytechinus variegatus (Echinodermata: Echinoidea).

The common nearshore sea urchin Lytechinus variegatus is capable of surviving exposure to inorganic phosphate concentrations as high as 3.2 mg/l(-1) and organic phosphate concentrations of 1,000 mg/l(-1). However, chronic exposure to low, medium, or high sublethal concentrations of these phosphates inhibits gonadal tissue indices and spawning activity while altering biochemical composition of gonads, reducing size frequencies of oocyte diameters, and changing gonadal volume fractions. Gonad indices declined significantly in individuals maintained in all phosphate concentrations after both one- and two-month exposures, while percentages of ripe individuals (oozing gametes upon dissection) were reduced after a two-month exposure in individuals maintained in medium and high organic phosphate concentrations. Levels of carbohydrates and lipids were lower in gonads of individuals maintained in all concentrations of both phosphates. Size frequency distributions of oocyte diameters revealed a dramatic decrease in oocyte size with increasing concentrations of both phosphates. Gonadal volume fractions of developing male and female gametes decreased with exposure to increasing phosphate levels. Volume fractions of nutritive phagocytes declined in testes of individuals held in the highest concentration of organic phosphate but displayed no significant change in ovaries. Volume fractions of mature gametes also decreased in gonads of individuals exposed to increasing concentrations of inorganic phosphate, but they remained constant in individuals exposed to all concentrations of organic phosphate. These findings indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress that may impair reproductive output, gametogenesis, and spawning in the natural environment.

Influence of hyperosmotic shrinkage and β-adrenergic stimulation on red blood cell volume regulation and oxygen binding properties in rainbow trout and carp

Whole blood from rainbow trout and carp was subjected to hyperosmotic shock and subsequent beta-adrenergic stimulation (isoprenaline) at different oxygen tension ( PO(2)) and carbon dioxide tension ( PCO(2)) levels with the aim to evaluate changes in red blood cell (RBC) volume, pH and ion concentrations and their ultimate effect on blood O(2) transport characteristics. Hyperosmolality (addition of NaCl) induced RBC shrinkage, which was followed by a regulatory volume increase (RVI) that was larger at low than at high PO(2)and more complete in carp than in trout. Carp RBC showed practically full volume recovery within 140 min at low PO(2)and partial recovery at high PO(2), whereas RVI was partial under all PO(2)and PCO(2)conditions in trout. The RVI increased intracellular [Na(+)], water content, and, in carp, also pH (pHi), suggesting activation of Na(+)/H(+) exchange. In trout RBCs, activation of RVI was rapid but succeeded by deactivation. In carp RBCs, activation of Na(+) influx was slower but it continued, allowing full volume recovery. Shrinkage of the RBCs was associated with only minor decreases in blood oxygen saturation and oxygen affinity in both species. Thus, the oxygen affinity decrease expected on the basis of the increased concentration of intracellular haemoglobin and organic phosphates was small, and it appeared to some extent countered during RVI by an oxygen affinity increase via increased pHi. Addition of isoprenaline increased RBC volume and pHi and increased Hb oxygen saturation. The beta-adrenergic response was stronger at low compared to high PO(2) and at high compared to low PCO(2). The PO(2) dependency was largest in carp, whereas the PCO(2) (pH) dependency was more expressed in trout. The adrenergic response of trout RBCs was similar under isoosmotic and hyperosmotic conditions. In carp RBCs, the response was absent at high PO(2) under isoosmotic conditions, but interestingly it could be induced under hyperosmotic conditions. The data suggest that the RBC shrinkage occurring in fish moving from freshwater to seawater has minimal impact on blood O(2) binding properties.

Haemoglobin function in vertebrates: evolutionary changes in cellular regulation in hypoxia

The evolution of erythrocytic hypoxia responses is reviewed by comparing the cellular control of haemoglobin-oxygen affinity in agnathans, teleost fish and terrestrial vertebrates. The most ancient response to hypoxic conditions appears to be an increase in cell volume, which increases the haemoglobin-oxygen affinity in lampreys. In teleost fish, an increase of cell volume in hypoxic conditions is also evident. The volume increase is coupled to an increase in erythrocyte pH. These changes are caused by an adrenergic activation of sodium/proton exchange across the erythrocyte membrane. The mechanism is important in acute hypoxia and is followed by a decrease in cellular adenosine triphosphate (ATP) and guanosine triphosphate (GTP) concentrations in continued hypoxia. In hypoxic bird embryos, the ATP levels are also reduced. The mechanisms by which hypoxia decreases cellular ATP and GTP concentrations remains unknown, although at least in bird embryos cAMP-dependent mechanisms have been implicated. In mammals, hypoxia responses appear to occur mainly via modulation of cellular organic phosphate concentrations. In moderate hypoxia, 2,3-diphosphoglycerate levels are increased as a result of alkalosis caused by increased ventilation.

The effects of organic and inorganic phosphates on fertilization and early development in the sea urchin Lytechinusvariegatus (Echinodermata: Echinoidea)

The embryos of the sea urchin Lytechinus variegatus are capable of surviving chronic exposure to inorganic sodium phosphate and organic triethyl phosphate concentrations as high as 6 and 1000 mg l −1 seawater, respectively. However, chronic exposure to sub-lethal concentrations of these phosphates may cause arrested or abnormal embryonic development. We measured fertilization success and percentages of normal, arrested and abnormal embryos exposed to low, medium and high sub-lethal concentrations of inorganic and organic phosphate. Fertilization success was significantly reduced in all phosphate treatments. After attaining the 4-cell stage, embryos exposed to the highest phosphate concentrations displayed arrested development. Percentages of abnormally developing embryos showed a strong concentration dose–response with a significant increase in abnormal embryonic development with increasing phosphate concentration. Overall, these results indicate that the gametes and embryos of L. variegatus may provide a rapid and sensitive model bioassay for the evaluation of phosphate pollutants in marine systems. Our findings also indicate that shallow-water populations of L. variegatus spawning in areas subjected to inorganic and organic phosphate pollutants may suffer detrimental effects on fertilization and embryonic development.

Effects of inorganic and organic phosphates on feeding, feeding absorption, nutrient allocation, growth and righting responses of the sea urchin Lytechinus variegatus

The sea urchin Lytechinus variegatus is capable of surviving chronic exposure to sodium phosphate (inorganic phosphate) concentrations as high as 3.2 mg l−1, and triethyl phosphate (organic phosphate) concentrations of 1,000 mg l−1. However, chronic exposure to low (0.8 mg l−1 inorganic and 10 mg l−1 organic phosphate), medium (1.6 mg l−1 inorganic and 100 mg l−1 organic phosphate) or high (3.2 mg l−1 inorganic and 1,000 mg l−1 organic phosphate) sublethal concentrations of these phosphates inhibits feeding, fecal production, nutrient absorption and allocation, growth and righting behavior. Food consumption and fecal production declined significantly in individuals exposed to medium and high concentrations of inorganic phosphates and all levels of organic phosphates. Feeding absorption efficiencies for total organics and carbohydrates decreased significantly in individuals held in the highest concentration of organic phosphate. Feeding absorption efficiencies for lipids were significantly reduced in the highest inorganic phosphate concentration only, while they decreased significantly for protein with increasing phosphate exposure. Carbohydrate and lipid levels in gonad and gut tissues decreased significantly with exposure to increasing phosphate concentrations, potentially impairing both gametogenesis and nutrient storage in the gut. Moreover, gonad indices significantly decreased in individuals exposed to the highest concentrations of either phosphate. Growth rates decreased significantly under the influence of all phosphate concentrations, while increasing in seawater alone. Individuals exposed to increasing phosphate concentrations showed reduced righting responses (a measure of stress) and no acclimation in righting times during chronic exposure to phosphates over a 4 week period. These findings indicate that shallow-water populations of L. variegatus subjected to inorganic and organic phosphate pollutants will exhibit stress and be inhibited in their growth and performance due to reductions in feeding, nutrient absorption and allocation of nutrients to key somatic and reproductive tissues.

Solid-state fermentation of phytase from cassava dregs.

Phytases produced by numerous microorganisms and plants degrade phytic acid that has chelated with metal ions in food and feed. It is important to study phytase for the role of metal ions in nutrition of animals and humans as well as in the reduction of organic phosphate content of aqueous environment. This article reports on solid-state fermentation of phytase from a new substrate of cassava dregs. Large quantities of cassava dregs are produced in tropical areas as a byproduct of cassava starch processing. Protein and inorganic salts were found to be low in cassava dregs. Cassava dregs could be employed for phytase synthesis after the addition of a nitrogen source and mineral salts. Ammonium nitrate was the best nitrogen source among the nitrogen sources investigated, including beef extract, yeast extract, urea, ammonium nitrate, sodium nitrate, and ammonium sulfate. Sodium dodecyl sulfate promoted phytase production from cassava dregs. A maximum phytase yield of 6.73 U/g of dry mass was obtained. The obtained phytase was stable at feed-processing temperature, since 70% of initial enzyme activity was maintained after 30 min of treatment at 75 degrees C.

Respiratory responses to short term hypoxia in the snapping turtle, Chelydra serpentina

Among vertebrates, turtles are able to tolerate exceptionally low oxygen tensions. We have investigated the compensatory mechanisms that regulate respiration and blood oxygen transport in snapping turtles during short exposure to hypoxia. Snapping turtles started to hyperventilate when oxygen levels dropped below 10% O 2. Total ventilation increased 1.75-fold, essentially related to an increase in respiration frequency. During normoxia, respiration occurred in bouts of four to five breaths, whereas at 5% O 2, the ventilation pattern was more regular with breathing bouts consisting of a single breath. The increase in the heart rate between breaths during hypoxia suggests that a high pulmonary blood flow may be maintained during non-ventilatory periods to improve arterial blood oxygenation. After 4 days of hypoxia at 5% O 2, hematocrit, hemoglobin concentration and multiplicity and intraerythrocytic organic phosphate concentration remained unaltered. Accordingly, oxygen binding curves at constant P CO 2 showed no changes in oxygen affinity and cooperativity. However, blood pH increased significantly from 7.50±0.05 under normoxia to 7.72±0.03 under hypoxia. The respiratory alkalosis will produce a pronounced in vivo left-shift of the blood oxygen dissociation curve due to the large Bohr effect and this is shown to be critical for arterial oxygen saturation.

IMPACT OF A NET CAGE FISH FARM ON THE DISTRIBUTION OF BENTHIC FORAMINIFERA IN THE NORTHERN GULF OF EILAT (AQABA, RED SEA)

Two sediment transects, at 23 m depth, were sampled below a commercial fish farm at the northern end of the Gulf of Eilat in order to describe the benthic foraminiferal community along an organic enrichment gradient. Sediment organic matter, porewater ammonia and phosphate concentrations reflected the input from the overlying fish cages and there was generally a decrease in these variables with distance from the point source. Rose-bengal stained foraminifera were found at all of the stations sampled below the fish farm, i.e. there were no azoic sediments. Fifty-one species of foraminifera (>45 μm) were found in the sediments around the fish farm but most were rare species. The most abundant (generally > 83% of the foraminifer abundance) species (stained + unstained) found were Amphisorus hemprichii, Amphistegina lessonii, Assilina ammonoides, Borelis schlumbergeri, Challengerella bradyi, Hauerina diversa, and Peneroplis planatus. Five of these foraminifera are algal symbiont bearing forms. The diatom-bearing species, A. lessonii and A. ammonoides, constituted 40 to 50% of the total number of tests. The most abundant stained species were A. ammonoides, B. schlumbergeri, H. diversa and P. planatus. Abundances of foraminifera were highest in the “hypertrophic” zone, adjacent to the fish cages. The most abundant species showed negative correlations between total abundance of tests and organic matter in the upper centimeter of the sediment. Negative correlations were also found between abundances of both total and stained tests of the most abundant species and integrated ammonia concentrations. No clear indicator species of the organically-enriched benthos were identified. Deformed tests (mainly P. planatus ) were observed in the samples and it is not clear whether they formed as a result of adverse conditions related to the fish farm because such variants also occurred at unenriched sites.

Preparation and Characterization of Milk Calcium Salts by using Casein Phosphopeptide

ABSTRACT Milk calcium salt solution was prepared by the following procedures using casein phosphopeptides (CPP). To CPP solution, 1 M citric acid, 1 M CaC12 and 1 M K2HPO4 were added with stirring, while adjusting the pH to 6.7. The prepared solution was left for 12 hr at 25°C and then used for subsequent experiments, or lyophilized. The concentrations of organic phosphate of CPP, calcium, inorganic phosphate, and citrate in the typical milk salt solution were 7, 30, 22, and 10 mM, respectively, which were close to those in bovine milk. The lyophilized sample was easily dissolved in water.

Light‐dependent and Biochemical Properties of Two Different Bands of Bacteriorhodopsin Isolated on Phenyl‐Sepharose CL‐4B

Abstract— We report a detailed description of the light‐dependent and biochemical properties of two different bands of isolated and nearly delipidated bacteriorhodopsin obtained from chromatography on phenyl‐Sepharose CL‐4B. The two bands (BR I and BR II) showed a number of markedly different spectroscopic and biochemical characteristics: different absorption maximums in the dark, different light/dark adaptations, different M decay kinetics, different stabilities, different responses to titration with alkali in the dark and different circular dichroism (CD) spectra. Organic phosphate contents of BR I and BR II were measured; we found that more than 90% of purple membrane organic phosphate was removed in the course of chromatography and that the phospholipid/protein molar ratio was always higher in BR I than in BR II. In many functional aspects (high stability, response to light adaptation, spectral changes in the dark by alkali addition and bilobate CD spectrum) the first band appeared to be similar to the purple membrane. We suggest that the functional differences between the two bands depend on the fact that the first band (BR I) contains mostly bacteriorhodopsin aggregates corresponding to purple membrane trimers, while the second band (BR II) contains only bacteriorhodopsin monomers.