BOOK REVIEWS

Book reviewed in this article:
East African Weeds and their Control. G. W. Ivens.
The Names of Plants. D. Gledhill. vi + 202 pp.
Hardy Orchids. Phillip Cribb and Christopher Bailes
The Genus Dionysia. Christopher Grey-Wilson
The Royal Horticultural Society Gardeners' Encyclopedia of Plants and Flowers. Editor-in-chief, Christopher Brickell
Sarawak. Notes during a residence in that country with H.H. the Rajah Brooke. Hugh Low, with an introduction by R. H. W. Reece
Spring and Winter Flowering Bulbs of the Cape. Barbara Jeppe and Graham Duncan
French Flower Painters of the 19th Century. Elisabeth Hardouin-Fugier and Etienne Grafe (ed. by P. Mitchell)
The Botanic Garden Wellington, a New Zealand History 1840–1987. Winsome Shepherd and Walter Cook
Frank Kindon-Ward. Charles Lyte
Biddulph Grange, Staffordshire - A Victorian garden rediscovered. Peter Hayden
The Medicinal Plants of Mauritius. Malcy de Chazal.
Hellebores. Brian Mathew. 180 pp. including 32 pp. colour plates and photographs
Modern Miniature Daffodils, Species and Hybrids. James S. Wells
The Green Tapestry. Beth Chatto. 192pp., numerous colour photographs. William CollinsSons &Co. Ltd     

Volatile communication between barley plants affects biomass allocation

Patterns of biomass allocation between different plant organs have often been used to explain the response of plants to variations in resource availability. This paper reports how aerial allelopathy (plant-plant communication) affects biomass allocation, that is the trade-off between root, stem and leaves, and also relative growth rate (RGR, increase in biomass per unit biomass per unit of time, mg g-1 d-1) and its components. Based on previous experiments, communication between two barley (Hordeum vulgare L.) cultivars (Alva and Kara) was used for the present study. Kara exposed to volatiles from Alva allocated significantly more biomass to roots compared with Kara exposed to volatiles from Kara or to clean air. There was no significant difference between plants of Kara exposed to volatiles from Kara and those exposed to clean air. Changes in total dry weight (TDW), RGR and unit leaf rate (ULR, increase in biomass per unit time and leaf area, kg m-2 d-1) were not significantly affected by plant-plant communication. However, there was a significant increase in specific leaf area (SLA, leaf area per leaf dry weight, m2 kg-1) in Kara when exposed to volatiles from Alva. The results show that aerial plant-plant communication does not affect total biomass production but does significantly affect biomass allocation in individual plants. There may be differences in the volatile profiles of Kara and Alva that induce increased biomass allocation to roots in the Kara plants exposed to volatiles from Alva.     

Spider mites of sugarcane in Australia: a review of grass-feeding Oligonychus Berlese (Acari: Prostigmata: Tetranychidae)

Abstract In many areas of the world, spider mites are significant pests of sugarcane. Australia is currently fortunate in lacking the most destructive species, and usually suffers only sporadic damage. Herein, we provide a key to the genera of spider mites associated with sugarcane, review the most significant genus, Oligonychus Berlese, and provide a key to the species of grass-feeding Oligonychus in the Australasian region. The species O. araneum Davis, O. digitatus Davis, O. grypus Baker and Pritchard, O. orthius Rimando, and O. oryzae (Hirst) are redescribed, while the Australian O. zanclopes sp. n. Beard and Walter from sugarcane and rice, O. turbelli sp. n. Beard and Walter, O. ephamnus sp. n. Beard and Walter and O. festucolus sp. n. Beard and Walter from other grasses, are newly described. Previous records of O. grypus in Australia appear to be misidentifications of what is described here as the new species O. zanclopes .     

Some effects of salts on staining: Use of the Donnan Equilibrium to describe staining of tissue sections with acid and basic dyes

Summary Using a wide variety of acid and basic dyes, and dyebaths of various pH’s and salt contents, it was shown that various effects of neutral inorganic salts on the staining of tissue sections could be explained by the Donnan Membrane Equilibrium. Thus the simultaneous increases in staining of some tissue components and decreases in staining of others, which occur on adding salt to the dyebaths, are often explicable in terms of the Donnan Equilibrium. The variation in staining intensity with dye charge, seen with a number of acid dyes, also agreed with the predictions of the Donnan Equilibrium. The Donnan Equilibrium was applied to understanding the mode of action of various biological staining methods requiring salt in the dyebaths; namely the Best’s Carmine glycogen stain, the Alcian Blue and Congo Red methods for amyloid, and the salty periodic acid-Schiff procedure for anionic mucosubstances.     

Application of polyelectrolyte limiting laws to virial and asymptotic expansions for the Donnan equilibrium

We have applied a general polyelectrolyte theory to an analysis of the Donnan equilibrium. The polyelectrolyte concentration is measured by a dimensionless parameter x, equal to the ratio of the equivalent polyelectrolyte concentration to the concentration of salt in the external compartment. For small x, virial series - expansions in powers of x - are developed for the Donnan salt-exclusion, osmotic pressure, and electromotive force. For large x, asymptotic expansions for these effects are presented. Polyion-polyion interactions are explicitly neglected, so that the physical significance of the virial series differs from its meaning in neutral polymer chemistry. Numerical results illustrate large deviations from ideal Donnan behavior as well as satisfactory agreement with published data on the salt-exclusion and emf effects. However, results for the Donnan osmotic pressure disagree with the data, except in the case of zero salt concentration in the external compartment, for which agreement is almost exact.     

Predation by Kelp Gulls Larus dominicanus at a mixed-species colony of Royal Terns Sterna maxima and Cayenne Terns Sterna eurygnatha in Patagonia

We studied the predator-prey interaction between Kelp Gulls Larus dominicanus and Royal Terns Sterna maxima and Cayenne Terns Sterna eurygnatha at Punta León, Argentina, from 1990 to 1992. Kelp Gulls were the main predator of tern eggs in all 3 years, accounting for 99% of observed predations (n = 454). A total of 99% of predations occurred on peripheral tern nests. Total predation rate on both tern species was highest in 1990 and varied significantly between years, with between 0.01 and 0.03 cases of predation per hour. Predation rates in all years were significantly higher on Cayenne than on Royal Terns probably because the latter were significantly more aggressive towards gulls than were Cayenne Terns. Royal and Cayenne Terns displayed aggressively towards gulls at least once in 64% and 10% of the observation periods, respectively. Defence behaviour, such as attacking and chasing the predator, was used more frequently by Royal than Cayenne Terns (13.2% v 3.6%). Predation on tern eggs was restricted to only a few Kelp Gulls which nested close to the tern colony periphery, and 50% of the eggs that were stolen were taken by only two pairs during 1991 and 47% by three pairs in 1992. This suggests that the current expansion of the Kelp Gull numbers at Punta León might not necessarily result in a proportional increase in predation rate on both tern species. Stealing eggs from the ground was more successful than from the air (77% v 17%). The nesting strategy shown by Royal and Cayenne Terns at Punta León appears to be an important factor which reduced the impact on their breeding success of high potential predation pressure by gulls.     

Water and electrolyte content of the myofilament phase in the chemically skinned barnacle fiber

Muscle fibers from the giant barnacle, Balanus nubilus, were placed inside the lumen of a porous glass capillary and equilibrated for 48 h in an electrolyte solution containing 2% Tween. The glass capillary prevented the chemically "skinned" fiber from swelling with a water content beyond 80%. Isotope exchange studies using 22Na, 42K, and 36Cl indicated the existence of an intermediate rate constant and compartment which varied with pH. This intermediate rate was attributed to counter-ions and co-ions in the myofilament phase. Analysis of the electrolyte composition of the fiber at pH 8 predicts that the myofilaments contain about 0.3 of the fiber water, and that a -15 mV Donnan potential exists at the myofilament surface. An open-tipped (1- micrometer) microelectrode in the skinned fiber measured a potential (similar in magnitude to the Donnan potential), which decreased and reversed sign as the pH was lowered. The measured cation contents of the fiber between pH 5 and 8 were found to be similar to the cation contents predicted from the measured Donnan potentials. The net negative charge of the myofilaments at pH 7.5 and at ionic strength 0.56 is estimated to be 41 eq per 10(5) g of dry weight.     

Book Reviews

Book reviewed in this article:
The Chambered Tombs of Scotland: Vol. I . A udrey S hore H enshall .
Inventaire des Mégalithes de la France: Vol. I, Indre-et-Loire . G érard C ordier .     

Effect of protein and solution properties on the Donnan effect during the ultrafiltration of proteins

Formulation of protein biopharmaceuticals as highly concentrated liquids can improve the drug substance storage and supply chain, improve the target product profile, and allow greater flexibility in dosing methods. The Donnan effect can cause a large offset in pH from the target value established with the diafiltration buffer during the concentration and diafiltration of charged proteins with ultrafiltration membranes. For neutral formulations, the pH will typically increase above the diafiltration buffer pH for basic monoclonal antibodies and decline below the diafiltration buffer pH for acidic Fc-fusion proteins. In this study, new equations for the Donnan effect during the diafiltration and concentration of proteins in solutions containing monovalent and divalent ions were derived. The new Donnan models obey mass conservation laws, account for the buffering capacity of proteins, and account for protein-ion binding. Data for the pH offsets of an Fc-fusion protein and a monoclonal antibody were predicted in both monovalent and divalent buffers using these equations. To compensate for the pH offset caused by the Donnan effect, diafiltration buffers with pH and excipient values offset from the ultrafiltrate pool specifications can be used. The Donnan offset observed during the concentration of an acidic Fc-fusion protein was mitigated by operating at low temperature. It is important to account for the Donnan effect during preformulation studies. The excipients levels in an ultrafiltration pool may differ from the levels in a protein solution obtained by adding buffers into concentrated protein solutions due to the Donnan effect.     

THE EFFECT OF PURE PROTEIN SOLUTIONS AND OF BLOOD SERUM ON THE DIFFUSIBILITY OF CALCIUM

1. A comparative study has been made of the diffusibility of calcium in solutions of crystalline egg albumin, serum globulin, and human blood serum. 2. In all three of these solutions, at pH 7.4, molal Ca concentrations within the membrane are greater than the calcium concentrations in the outside solutions, quite in accordance with the Donnan theory. 3. At pH 7.4, the ratio of See PDF for Structure varies directly with the protein concentration whether the solution be one of egg albumin, serum globulin, or blood serum. This is also in accordance with the Donnan theory. 4. On the acid side of the isoelectric point of the proteins, the concentration of Ca outside becomes greater than the concentration in the solution of blood serum or pure protein, as is demanded by the Donnan theory. 5. The magnitude of the Ca ratios on the alkaline and acid sides of the isoelectric points is probably the resultant of the Donnan equilibrium and the formation of complex Ca-protein ions. Northrop and Kunitz have shown the probability of the existence of such ions in the case of Zn⁺⁺, K⁺, and Li⁺, where satisfactory electrodes have been developed for E.M.F. measurements.     

Electron Microscope Studies on the Absorption and Localization of Lead in the Leaf Tissue 6Potamogeton pectinatus L.

Electron microscope studies have shown that Potamogeton pectinatusL. accumulates lead in the cell walls where it is probably boundaccording to Donnan equilibria. The plasmalemma acts as a barrierto the influx of lead, though pinocytotic invaginations mayconvey some metal into the protoplast and render it non-toxic.With high, toxic lead treatments, deposits were observed inthe cytoplasm and within the chloroplasts. The accumulationof lead in the cell walls and the pinocytotic inclusions, asa feature of lead-tolerant species, is discussed. The data suggesta rapid penetration of ions through the thin cuticle of submergedangiosperms and absorption into the protoplast.     

Outpatient cleft lip repair

The emphasis on cost reduction and increased efficiency in health care delivery has prompted an increase in outpatient (ambulatory) surgical procedures. A retrospective review of the perioperative management of patients undergoing cleft lip repair at two urban tertiary pediatric hospitals was performed to assess the safety of outpatient cleft lip repair. The hospital database at Childrens Hospital Los Angeles was searched to find all patients who had been operated on for cleft lip repair during calendar years 1999 and 2000. Two groups were identified from Childrens Hospital Los Angeles: the outpatient cleft lip repair group (patients discharged the same day as the operation; n = 91) and the inpatient cleft lip repair group (n = 14). A data set was acquired from the Royal Children's Hospital in Melbourne, Australia, using the same criteria, for fiscal years 1998 to 2000 (n = 50). All patients from Royal Children's Hospital had operations as inpatients. Parameters considered for each group were age, sex, race, ethnicity, length of hospital stay, preexisting medical conditions or diagnoses, complications, and readmissions or presentation to the emergency department within 4 weeks of operation. The Childrens Hospital Los Angeles outpatient group had three readmissions that were considered to be complications of the operation. The Childrens Hospital Los Angeles inpatient group had one readmission attributable to a complication. The Royal Children's Hospital group also had one readmission for a complication. There was no significant difference in the complication rate of the Childrens Hospital Los Angeles outpatient group and the Royal Children's Hospital group (p > 0.05). There was also no significant difference in the complication rate of both of the Childrens Hospital Los Angeles groups compared with the Royal Children's Hospital group (p > 0.05). This study indicates that cleft lip repair performed in an outpatient setting may be a safe alternative to the inpatient operation. Certain preexisting medical conditions, however, may dictate the need for inpatient hospitalization after repair.     

Peroxidase activity in genotypes and genotrophs ofLinum

Summary Peroxidase activity was measured in two sets of experiments with the flax genotypes Royal and Mandarin, and the flax genotrophs NPK and NK produced by NPK and NK fertilizer treatments of Stormont Cirrus.Royal and NPK produced more basal branches than Mandarin and NK. Royal was higher, except in one case, than Mandarin in peroxidase activity, while NK was higher than NPK.Dialysis of the extracts caused a marked rise in peroxidase activity through removal of an inhibitor. Stems contained more peroxidase activity than leaves both before and after dialysis of the two samples.F₁ hybrids between NPK and NK showed no reciprocal differences in peroxidase activity.

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Zusammenfassung Die beiden Leinsorten Royal und Mandarin unterscheiden sich wesentlich in der Intensität der basalen Verzweigung. Ähnliche Unterschiede weisen zwei Genotrophe der Leinsorte Stormont Cirrus auf; sie entstanden durch die über mehrere Generationen anhaltende Wirkung einer NPK- bzw. einer NK-Düngung. Um dem physiologischen Steuerungsmechanismus der unterschiedlichen basalen Verzweigung näherzukommen, wurde die Peroxydaseaktivität in zwei Versuchsreihen gemessen, und zwar an den beiden Genotypen bzw. Sorten Royal und Mandarin und an den beiden Genotrophen NPK und NK der Sorte Stormont Cirrus (Nachkommenschaften behandelter Pflanzen in der dritten Generation).Royal und NPK hatten eine größere Anzahl basaler Zweige als Mandarin und NK. Die Peroxydaseaktivität war, mit einer Ausnahme, bei Royal höher als bei Mandarin, dagegen bei NK höher als bei NPK.Dialyse der Extrakte verursachte ein beträchtliches Ansteigen der Peroxydaseaktivität infolge der Beseitigung eines Inhibitors. Die Stengel hatten eine höhere Peroxydaseaktivität als die Blätter, sowohl vor wie nach der Dialyse der beiden Proben.Auch F₁-Hybriden verschiedener reziproker Kombibinationen wurden auf ihre Peroxydaseaktivität hin untersucht. In einzelnen Fällen ergaben sich signifikante Reziprokenunterschiede, nicht jedoch bei F₁-Hybriden zwischen NPK und NK.Intensivere Untersuchungen sind notwendig, bevor klare Schlüsse hinsichtlich der Ursache unterschiedlicher Verzweigung gezogen werden können.

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With 3 figures

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Contribution No. 50 from the Research Branch, Canada Agriculture, Experimental Farm, Morden, Manitoba, Canada.     

The Donnan effect in tobacco mosaic virus and its components

Osmotic pressure studies were carried on tobacco mosaic virus (TMV) and its components, protein and RNA, as well as on bis(3,3′-aminopropyl)amine, reported to be present in TMV preparations. Solvents were phosphate and barbital buffers at different values of pH and ionic strength. Measurements were made at room temperature. The Donnan effect was exhibited by TMV protein in phosphate buffer of 0.01 ionic strength at pH values ranging between 5.8 and 7.5. The observed values of the Donnan effect at pH 5.8 and 5.97 were in reasonable agreement with theoretical values calculated from the charge obtained by hydrogen ion titration. TMV-RNA in phosphate buffer at pH 7.5 and ionic strength 0.01 did not exhibit more than 1% of the expected Donnan effect. This is explained tentatively as the result of firm binding of metal ions. Negative values of osmotic pressure were observed with bis(3,3′-aminopropyl)amine. Similar anomalous osmosis was sometimes observed with TMV protein and with TMV. In agreement with earlier observations, TMV did not exhibit the Donnan effect in phosphate buffer of 0.01 ionic strength at pH values ranging from 5.5 to 8.0. However, TMV dialysed extensively in the presence of EDTA at pH 8.5 and TMV produced by reconstitution of purified protein and RNA did exhibit the Donnan effect in both phosphate and barbital buffers. The magnitude was of the same order as that calculated from the net charge determined by hydrogen ion titration. When reconstituted TMV, which did exhibit Donnan effect, was treated with calcium ions, the effect was abolished.     

Porin channels in intact cells of Escherichia coli are not affected by Donnan potentials across the outer membrane

Donnan potential (interior negative) across the outer membrane of Escherichia coli was measured by the distribution of [14C]choline in a mutant with a deletion through the genes for the active transport of choline. Calculation showed that the presence of membrane-derived oligosaccharides in the periplasm could quantitatively explain the magnitude of the Donnan potential and the periplasmic volume. By measuring the permeability of porin channels in intact cells suspended in solutions of widely different ionic strengths, it was shown that changing Donnan potential from 5 mV to approximately 100 mV had no effect on the permeability of either OmpF or OmpC porin channel toward a zwitterionic compound, cephaloridine. Thus, the "voltage-dependent gating" of porin channel, previously reported from another laboratory, is likely to be an artifact of in vitro reconstitution. The influx of negatively charged compounds, however, was affected by the Donnan potential as expected from the electrolyte diffusion theory.     

MEMBRANE EQUILIBRIA AND THE ELECTRIC CHARGE OF RED BLOOD CELLS

It has been shown, within the probable limit of error of the methods of measurement employed, that the Donnan equilibrium determines the distribution of H and Cl ions between the cell and the surrounding fluid. This equilibrium is a consequence of the impermeability of the cell membrane to the inorganic cations of the cell. The mechanism responsible for this equilibrium is suggested as that concerned in the secretion of HCl by the cells of the gastric mucosa. If the salt concentration of the medium is low there may result from the Donnan equilibrium a thermodynamic P.D. of considerable magnitude. In the presence of low concentrations of electrolytes, this P.D. is to be regarded as positive in sign at reactions of the medium at which the cataphoretic charge of the cell is negative in sign. The explanation of this discrepancy in sign of charge may lie in the existence at an outer phase-boundary of a second Donnan equilibrium the nature of which is determined by the ionization of the protein of the cell membrane.     

Potential and K+ activity in skinned muscle fibers. Evidence against a simple Donnan equilibrium

It has been suggested that potentials measured with conventional microelectrodes in chemically or mechanically skinned muscle fibers arise from a Donnan equilibrium due to myofilament fixed charges. This hypothesis was tested in mechanically skinned frog (Rana pipiens) semitendinosus fibers by measuring the distribution potential (Ed) between fiber and bath with 3 M KCl-filled microelectrodes and the K+ activity gradient (aik/aok) with K+ ion-selective microelectrodes (KISE). If skinned fibers are a Donnan system, Ed should become more positive as pH is decreased, altering the fixed charge on the myofilaments. Consistent with this expectation, Ed was -4.4, -0.6, and +4.8 mV in ATP-containing solutions and -6.5, -2.2, and +8.4 mV in ATP-free solutions at pH 7, 6, and 5, respectively. Donnan equilibrium also requires that all mobile ionic species be in electrochemical equilibrium. In ATP-containing solutions, this was true for K+ at pH 7. At pH 5, however, KISE indicated that K+ was not in equilibrium; average Ed was 5.9 mV positive to the K+ equilibrium potential, and aik/aok was 1.04, while the Donnan prediction was 0.83. In contrast, KISE measurements in ATP-free solutions indicated that K+ was in equilibrium at all pH studied. Skinned fibers in ATP-containing media are not equilibrium systems because ATPase reactions occur. Under our conditions, frog myofibrils hydrolyze 0.4 and 0.08 mumol ATP/min X mg myofibrillar protein at pH 7 and 5, respectively. It is suggested that in the presence of ATP, Ed is a superposition of Donnan and diffusion potentials, the latter arising from differences in the mobilities of anionic substrate and products that diffuse through the charged myofilament lattice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Donnan potentials from striated muscle liquid crystals. Sarcomere length dependence.

Donnan potentials from A-bands and I-bands were measured as a function of sarcomere length in skinned long-tonic muscle fibers of the crayfish. These measurements were made using standard electrophysiological technique. Simultaneously, the relative cross-sectional area of the fibers was determined. Lattice plane spacings and hence unit-cell volumes were determined by low-angle x-ray diffraction. At a sarcomere length at which the myosin filaments and actin filaments nominally do not overlap, measurements of potential, relative cross-sectional area, and unit-cell volume were used in conjunction with Donnan equilibrium theory to calculate the effective linear charge densities along the myosin filament (6.6 X 10(4) e-/mu) and actin filament (6.8 X 10(3) e-/mu). Using these linear charge densities, unit-cell volumes and Donnan equilibrium theory, an algorithm was developed to predict A-band and I-band potentials at any sarcomere length. Over the range of sarcomere lengths investigated, the predicted values coincide with the experimental data. The ability of the model to predict the data demonstrates the applicability of Donnan equilibrium theory to measurements of electrochemical potential from liquid-crystalline systems.