Normal Sea Research Articles

Calcium current and calcium‐activated inward current in the oocyte of the starfish Leptasterias hexactis.

1. Inward currents in the immature oocyte of the starfish Leptasterias hexactis were studied with a two-micro-electrode voltage clamp. Experiments investigated the role of Ca2+ in the Na+-dependent plateau of the action potential. 2. Voltage steps more positive than -55 mV produced inward currents in normal sea water that activated and then decayed to a non-zero level with a double-exponential time course. Returning the voltage to the resting potential produced an inward tail current that relaxed slowly to zero with a time course of seconds. 3. Replacing Na+ with choline abolished the slowly decaying component as well as the slow tail current which followed the end of the voltage pulse. This suggested that inward current in Na+-containing sea water consisted of a rapidly decaying component that flowed through Ca2+ channels and a more slowly decaying component carried by Na+. 4. Ca2+ current was isolated in Na+-free sea water. Activation followed a sigmoidal time course that could be described with m2 kinetics. Inactivation during a maintained depolarization followed first-order kinetics and was voltage dependent. 5. When Ba2+ was substituted for Ca2+ as the divalent ion charge carrier, inward currents in Na+-containing sea water decayed along a single-exponential time course. The absence of a slowly decaying Na+ current in Ba2+-containing sea water suggested that Na+ current depended on Ca2+ influx. 6. The effects of altering Ca2+ influx on the time course of Na+ current were investigated. Na+ current decayed more rapidly as the test pulse potential was made more positive, while raising [Ca2+]o slowed the decaying phase without altering its dependence on membrane potential. 7. Tail currents measured after rapidly stepping the membrane potential back to the resting level consisted of a fast component associated with the closing of Ca2+ channels and a slow component that was abolished by removing Na+. 8. The variation of the amplitude of the slow component of tail current with the duration of the voltage-clamp pulse indicated that Na+ current is associated with a time-dependent component of membrane conductance. 9. Possible mechanisms for the slowly decaying Na+ current are considered. The results are discussed in relation to the idea that the conductance change to Na+ follows the time course of Ca2+ accumulation and removal from the cytoplasm.

Oxygen and carbon isotope compositions of Upper Cretaceous chalk from the Danish sub‐basin and the North Sea Central Graben

ABSTRACTThe oxygen and carbon isotopic compositions of Upper Cretaceous chalk have been studied from a large number of outcrops and boreholes in the Danish sub‐basin and the North Sea Central Graben. The carbon isotopic compositions vary from +0.50%o to +3.00%oδ13C which correspond to the expected carbon isotopic composition of carbonate precipitated from normal sea water. The oxygen isotopic compositions of samples from outcrops and near‐surface drilled sections fall in the range from —0.50%o to — 2.00%oδ18O, which is close to the expected values for carbonate produced by coccoliths in the Late Cretaceous sea. A geographic distribution exists in the Danish sub‐basin showing relatively heavy oxygen isotope values in the centre of the basin and slightly more negative values in the eastern part of the basin. Primarily the phenomenon is thought to reflect minor variations in the oceanographic parameters in the Late Cretaceous sea.The deep subsurface sections represent a depth interval of 0–3100 m. Mechanical compaction in the uppermost part of the sequences apparently has no influence on the isotopic composition. Chemical compaction dominates at greater depth, leading to temperature‐induced isotopic re‐equilibration in the water‐rock system. In these sequences the oxygen isotope values range from − 1.50%o to — 7.50%oδ18O and are significantly correlated with depth of burial, cementation and porosity. The data indicate that pressure‐dissolution, recrystallization, reprecipitation and ion‐exchange between solid carbonate phase and pore water, are all actively involved in the oxygen isotope re‐equilibration process. This process is believed to take place in a diagenetically closed system and is tentatively divided into two phases: 1) an early diagenetic phase which takes place at porosities down to approximately 20% in which the chalk possesses a pore‐water controlled isotopic re‐equilibration system and 2) a late diagenetic phase at porosities below 20% in which the re‐equilibration process increasingly becomes influenced by the rock‐introduced isotopic change in the composition of the formation water.

Performance evaluation of three different seawater RO membranes at DROP in Kuwait

Kuwait has realised that in spite of the success which has been achieved in sea water desalination by Reverse Osmosis for normal sea water, still more has to be done in this field for the Arabian Gulf sea water which has different properties of high TDS, Silt Density Index and Temperature. Hence, a joint program in sea water Desalination by Reverse Osmosis between Water Resources Development Centre/Kuwait Institute for Scientific Research of Kuwait and GKSS of Federal Republic of Germany to carry out in Kuwait, under joint management the operation of three independent RO lines employing sea water membranes of Spiral Wound, Hollow Fine Fiber and Plate & Frame Configuration of capacity 1000 Cubic Metre per day each. These three RO lines are operated in parallel. The sea water membranes used in the first stage of three RO lines are: Spiral Wound UOP-1501 (PA), Hollow Fine Fiber DUPONT B-10 (PA) and Plate & Frame membranes of Enro (CA), Schleicher & Schull (RO 112) and Filmtec (FT-30). The membranes used in second stage are Spiral Wound UOP-8600 (PA), Hollow Fine Fiber DUPONT-B9(PA) and Spiral Wound Hydronautics 8040 B(CA) respectively. This paper discusses briefly, the operating parameters, membrane performance and availability of each line.

Induction of the Acrosome Reaction in Starfish: (acrosome reaction/starfish sperm/egg jelly/Ca-channel/ionophore).

In the starfish, Asterias amurensis, at least two distinct components of the egg jelly are required for inducing the acrosome reaction: a sulfated glycoprotein named acrosome reaction-inducing substance (ARIS) and a diffusible organic substance(s) named Co-ARIS. The following evidence suggested that ARIS and Co-ARIS cooperatively activate CA-channels of the sperm plasma membrane and eventually induce dramatic changes in sperm morphology, the acrosome reaction. 1) Pronase digest of ARIS (P-ARIS) and Co-ARIS, either as a pure or a crude preparation (Fraction M8 ), were fully effective in combination for induction of the acrosome reaction in normal sea water, although they were not effective individually. P- ARIS alone induced the acrosome reaction fully in high Ca2+ sea water and markedly at high pHs, whereas Fraction M8 alone did not induce the reaction even in these conditions. The reaction was not induced by increase in either the Ca2+ concentration or the pH of sea water, but was markedly induced in the absence of jelly components by raising both the pH and Ca2+ concentration together. 2) The ionophore A23187 induced the acrosome reaction appreciably when present alone and fully in the presence of monensin or Fraction M8 . Monesin alone was ineffective. 3) The jelly or a combination of ARIS and Fraction M8 caused abrupt Ca2+ -uptake by the sperm. The Ca-channel blockers verapamil and diltiazem inhibited the jelly-induced acrosome reaction.

The Limulus sperm motility-initiating peptide initiates acrosome reactions in sea water lacking potassium.

During fertilization in Limulus, the spermatozoa first attach to the egg and then undergo an acrosomal reaction. In this reaction, the acrosomal vesicle exocytoses, and a long, preformed acrosomal filament is extruded (and subsequently penetrates the egg chorion). The egg surface component that triggers the acrosome reaction has not yet been solubilized; therefore, previous studies have examined either spontaneous acrosome reactions or acrosome reactions that were triggered by eggs (or insoluble egg fragments), elevated extracellular Ca2+, or Ca2+ ionophores. In this study, we report a new method for initiating acrosome reactions in Limulus sperm. When the Limulus sperm motility-initiating peptide (SMI) is added to sperm in K+-free sea water, greater than 90% acrosome reactions are initiated within 5 min. However, less than 5% acrosome reactions occur either in K+-free sea water lacking SMI or when SMI is added to sperm in either normal sea water or K+- and Ca2+-free sea water. Experiments with K+ ionophores (nigericin and valinomycin), a K+ channel blocking agent (tetraethyl ammonium), an Na+ ionophore (monensin), and reagents that increase the intracellular pH (monensin, nigericin, and NH4Cl) indicate that changes in intracellular K+, Na+, or H+ do not mediate SMI-initiated acrosome reactions. The K+/Ca2+ ratio determines whether or not SMI will initiate acrosome reactions, with greater than 50% acrosome reactions being initiated when this ratio is below 0.3. In that K+ movement does not appear to be the critical event, possibly the K+/Ca2+ ratio either determines the rate of Ca2+ entry or controls the conformation of sperm surface molecules to allow SMI to initiate acrosome reactions in low K+.

Analysis of sea urchin egg cortical transformation in the absence of cortical granule exocytosis

A burst of endocytosis accompanying microvillar elongation follows cortical granule exocytosis in normal sea urchin development. By 5 min postfertilization the burst is over and a lower level of endocytosis ensues (constitutive phase). To determine whether microvillar elongation and initiation of endocytosis are necessary concommitants of cortical granule exocytosis we utilized Chases's (1967, Ph.D. thesis, University of Washington, Seattle) high-hydrostatic pressure technique to block the latter and then examined developing eggs for endocytosis and microvillar elongation. To accomplish this, eggs were fertilized, after which hydrostatic pressure was quickly raised to 6000–7000 psi at the start of cortical granule exocytosis and maintained for 5 min. Only the cortical granules immediately surrounding the sperm penetration site were secreted (about 3% or less of the egg's total number of cortical granules). Blockage of major cortical granule exocytosis had the following consequences on surface events during first division: (1) The endocytosis burst normally associated with cortical granule exocytosis was effectively eliminated as was early microvillar elongation and elevation. Both occurred to a limited extent around the sperm penetration site which resulted in a highly localized surface transformation. (2) By 20 min after fertilization endocytosis began over the rest of the egg surface in the absence of any further cortical granule exocytosis. (3) Subsequently, during a 30-min period starting midway between fertilization and first cleavage microvilli more than doubled in length and endocytosis levels increased severalfold. These events brought about a complete surface transformation similar to that which normally occurs in early development but in the absence of cortical granule exocytosis. By first cleavage surfaces and cortices of high-pressure-treated and control eggs were nearly indistinguishable except for the presence of cortical granules in cortices of the former. Pressure-treated eggs cleaved normally and developed to larval forms overnight. The period of late surface transformation in high-pressure-treated Strongylocentrotus purpuratus eggs corresponds in timing and some of its characteristics to second phase microvillar elongation observed in normal development in this species and also in S. droebachiensis development. These observations suggest, therefore, that microvillar elongation and endocytosis are necessary membrane remodelling events which must occur for normal development even in the absence of membrane addition from the cortical granules.

Effects of photoperiod on juvenile growth and smolting of Atlantic salmon and subsequent survival and growth in sea cages

Hatchery-reared Atlantic salmon parr were grown in the laboratory from November to May under two photoperiod (simulated natural and continuous light) and temperature (12-7-12° and 17-6°C) regimes. Growth rates of both photoperiod groups under the 17-6°C regime were greater from November to February but were lower from February to May than those under the 12-7-12°C regime. Accumulated degree days were slightly greater for the 17-6°C groups. Parr from both thermal regimes under continuous light grew much faster from November to February and were larger in May than those under natural photoperiod, but had low tolerance to salinity when challenged at 37.5‰ Most of the natural photoperiod test group survived the high salinity more than 96 h. The fish were acclimated to normal sea water (29–30‰) in May and moved to a sea cage for observations on survival and growth during the summer and autumn under natural thermal and photoperiod conditions. Salmon from the continuous light regime survived only slightly less well than those from the natural photoperiod regime; the former appeared to be healthy and grew reasonably well but by October were only about two-thirds the size of those from the natural photoperiod regime. It was concluded that the fish reared under continuous light, though large and healthy and smolt-like in appearance, were not smolts. These results are discussed in relation to the environmental conditions required to produce smolts and the importance of appropriate photoperiod treatment during juvenile growth in fresh water.

Geology and genesis of manganese oolite, Chiatura, Georgia, U.S.S.R.

The Oligocene stratiform manganese deposits in the Chiatura region (Georgia, Soviet Union) were deposited on stable crystalline basement in a restricted arm of the Paratethys during a transgressive-regressive cycle. Transgression was characterized by, in the early stages, the development of a fining-upward gravel and sand sequence and, with increasing water depth, deposition of organic-rich, fine-grained sediments in waters increasingly depleted in oxygen. Manganese, derived from weathering of recks surrounding the basin, was probably concentrated in these reduced waters to levels well above those of normal sea water. Manganese carbonates were formed in offshore areas subject to reducing conditions; in well-aerated, nearshore parts, manganese oxides were formed. Landward migration of the oxidation/reduction interface during transgression led to further concentration of manganese in nearshore regions and eventually to extensive precipitation and accumulation of manganese oxide ooliths and pisoliths, occasionally in graded units, during peak transgression and early regression when basin waters were reoxygenated. Late regression was characterized by the deposition of sands and spongiolite. Petrographic studies of manganese-oxide ooliths and pisoliths indicate a concentrically laminated structure in which constituent pyrolusite microcrystals show a characteristic radial and, less frequently, random orientation with respect to the grain center. Ooliths and pisoliths, which also exhibit micro-unconformities and entrapped detrital material, are considered to be analogous to some present-day calcite and aragonite ooliths and were probably formed in a low energy, shallow-marine environment. Graded bedding in oolite and pisolite is comparable to similar beds documented in the Cretaceous stratiform manganese deposit at Groote Eylandt in northern Australia. Grading was probably formed as a result of changes in energy and/or oxygen levels during small-scale fluctuations in sea level.

Acceleration of the Cleavage in Sea Urchin Eggs by Treatments with Local Anesthetics (II) Treatments with Some Other Local Anesthetics than Procaine*: (acceleration of cleavage/local anesthetics/caffeine/sea urchin eggs).

Unfertilized sea urchin eggs were exposed to sea water solutions of local anesthetics, such as caffeine, tetracaine and ethyl urethane, and the herbicide, isopropyl N-phenyl carbamate (IPC) for 10min and returned to normal sea water. Then they were inseminated 5min later. When eggs were pre-treated with 1-2 mM caffeine, 0.02-0.05 mM tetracaine, 50-100 mM ethyl urethane and 2% saturated sea water of IPC, respectively, they could cleave and hatch earlier than the control eggs. However, when fertilized eggs were continuously post-treated with solutions of the agents except IPC at the same concentrations as those in the case of the pre-treatments, the fertilized eggs could not cleave or were retarded in development. The possible mechanisms of the cleavage acceleration by pre-treatments with local anesthetics were discussed.

Optimal Cable Configurations for Passive Dynamic Control of Compliant Towers

Whether in storm or normal seas, the ideal offshore cable-stayed compliant tower moves in harmony with the wind and waves. A properly tuned cable configuration is the key to controlled dynamic response. Formulated here are a nonlinear dynamic model involving wind, wave, current, tower, and cable interactions and a cable optimization algorithm. The objective function, the rms tower rotation, is minimized subject to appropriate constraints involving compatible system geometries and loads, as well as bounds on the platform level accelerations needed for human comfort. Tower motion is limited to a plane.

Equatorial sea level response during the 1982–1983 El Niño

During the 1982–83 El Niño/Southern Oscillation event, sea level across the width of the equatorial Pacific adjusted to the reversal of the equatorial trade winds, and by the end of 1982 the normal sea level slope across the Pacific had been eliminated. The transfer of warm upper‐ocean water from the western Pacific to the eastern Pacific was accomplished by a combination of direct wind forcing as the wind anomaly crossed the basin and by mass flux induced by free equatorial waves. The importance of equatorially trapped Kelvin waves of first and second vertical mode during the onset of the 1982–83 El Niño is inferred from the cross‐correlation statistics between central and eastern Pacific sea level stations and between wind variations in the western Pacific and equatorial sea level stations to the east. The different propagation speeds of these two modes appears to be responsible for the observed change inshape of the major sea level signals during the 1982–83 event. Tentative evidence for first baroclinic mode, first meridional‐mode Rossby waves is also presented.

Secretory dynamics of 1 alpha-hydroxycorticosterone in the elasmobranch fish, Scyliorhinus canicula.

Peripheral plasma concentrations, metabolic clearance rates (MCR) and blood production rates (BPR) of 1 alpha-hydroxycorticosterone (1-OH-B) were determined in female dogfish (Scyliorhinus canicula) under varying environmental conditions. The constant-infusion technique, using high specific activity tritiated 1-OH-B, was applied to measure the MCR, and BPR were derived from the product of plasma concentration and MCR at equilibrium. Urea plasma clearances and apparent BPR were assessed in a similar manner. Fish were adapted stepwise to 140, 120, 90, 80, 70, 60 and 50% normal sea water (about 1000 mosmol/l). In all cases 1-OH-B was the major corticosteroid, cortisol and corticosterone were sought but never detected. In environments of reduced osmolarity, plasma osmolarity, sodium, chloride and urea concentrations all declined, alongside increases in plasma concentrations, MCR and BPR of 1-OH-B. In fish held in environments at concentrations greater than normal sea water, plasma osmolarity, sodium, chloride and urea concentrations all increased. Plasma clearance of urea increased in fish held in environments more dilute than sea water, while it decreased in the more hyperosmotic waters. It is tentatively concluded that homeostasis of plasma composition, with particular respect to urea, is in part regulated by 1-OH-B in the dogfish.

Adhesive and migratory behavior of normal and sulfate-deficient sea urchin cells in vitro

Dissociated cells from different stage embryos of the sea urchin Lytechinus pictus were compared in their adhesion to various substrates. Micromeres from 16-cell stage embryos bind to tissue culture and Petri dishes but not to Petri dishes coated with human plasma fibronectin. Other cell types did not adhere to any of the substrates tested. By hatched blastula stage, about 28% of the cells adhered to fibronectin as well as to tissue culture dishes. By the mesenchyme blastula stage, there was a further increase in the proportion of cells adhering to these substrates. At no stage did cells adhere to native rat tail collagen. Primary mesenchymal cells were isolated by their selective adhesion to tissue culture dishes in the presence of horse serum. These cells were then examined for their migratory capacity. Cell spreading and migration followed adhesion and occurred on fibronectin but not on the other substrates tested. Based on analysis of video tapes, greater than 60% of these cells moved faster than 1 μm/min. On the other hand, cells from sulfate-deprived embryos, in which primary mesenchyme migration is blocked in situ, failed to spread and migrated little on the same substratum. This defect was reversed by a 6 h pretreatment of the cells in normal sea water. Thus, the in vitro migratory behavior parallels that observed in vivo. These results support the hypothesis that the primary mesenchymal cells produce a sulfate-dependent component that is required for cell spreading and migration.

EXTREME SEA LEVELS ON THE COAST OF CALIFORNIA

During the winter of 1982-1983, a combination of high tides, higher than normal sea level and storm-induced waves were devastating to the coast of California. Damage estimates for public and private property destruction in the coastal counties of California total over $100,000,000. Much higher than average sea levels played a very important contributory role in the flooding damage. This report describes and examines the oceanographic and meteorological conditions prevailing during winter 1982-1983, and attempts to put them into perspective using historical information at San Diego. Emphasis is placed on the processes and forces that contribute to extreme sea levels in the hope that better understanding of these and more complete information on historical extremes will help the engineer in design and in assessment of risk. The unusually high sea levels were due to a combination of higher than normal mixed layer temperature associated with a strong, 2-year El Nino, storm surge due to low atmospheric pressure and persistent onshore winds, and the cumulative effect of steady, "global" rise in relative sea level. Higher than average high tides coincided to an unusual extent with the peak sea levels reached during the numerous storms between November 1982 and March 1983. Important cyclical variations occur in California's tide regime and the consequences of these on extreme tides have not been considered previously.

Respiration of Sea Urchin Spermatozoa in the Presence of a Synthetic Jelly Coat Peptide and Ionophores: (respiration/sperm/peptide/egg jelly/sea urchin).

Sperm respiration and motility of the sea urchin Hemicentrotus pulcherrimus were studied at pH 6.8 in the presence of a synthetic jelly peptide (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly) and monovalent cationic ionophores. The synthetic peptide stimulated sperm respiration and motility to the level of that found in normal sea water (pH 8.2) with half-maximal stimulation at approximately 100 pM. Monensin and valinomycin also stimulated sperm respiration with half-maximal effects at 7 μM and 0.7 μM, respectively. The stimulation of sperm respiration by the peptide and monensin was dependent on external Na+ , but was not dependent on the osmolarity of the suspending medium. Approximately 50 mM Na+ was required for half-maximal respiratory responses to the peptide and monensin.

Stage Specific Effects of Zn2+ on Sea Urchin Embryogenesis (animalization/EDDA/EDTA-OH/sea urchin embryos/Zn2+ ).

The treatment of sea urchin embryos by Zn2+ followed by culture with Zn2+ -specific chelators such as ethylenediamine-N, N'-diacetic acid and N-hydroxyethylethylenediamine-N, N', N'-triacetic acid, was performed at various developmental stages to find out specific stages for Zn2+ to induce abnormal differentiation. The treatment with 1 mM ZnSO4 at 20°C during a period including two spans of development between 0 and 8 hr and between 14 and 16 hr post fertilization yielded permanent blastulae. Zn2+ -treatment during the former span produced abnormal prisms and plutei with small archenteron. The treatment for a period including only the latter span failed to produce abnormal ones. Zn2+ -treatment during a period including the gastrula stage also produced abnormal spherical embryos. Without the culture with these chelators, abnormal embryos were produced by Zn2+ -treatment performed at any stages before gastrulation. A high zinc amount in the embryos just after the treatment became as low as in normal embryos soon after the culture with these chelators and was maintained during the culture without them. These results indicate that zinc retention occurs in the Zn2+ -treated embryos and causes abnormal differentiation when the treated embryos develop in normal sea water through the Zn2+ -specific periods of development.

Mechanisms regulating intracellular pH in sea urchin eggs

Intracellular pH (pH i) of sea urchin eggs ( Paracentrotus lividus) was determined using DMO (dimethyloxazolidinedione) and a rapid filtration technique ( P. Payan, J. P. Girard, R. Christen and C. Sardet (1981). Exp. Cell Res. 134, 339–344 ). Transfer of unfertilized or fertilized eggs from normal sea water into Na +-free artificial sea water leads to a progressive acidification and fall of intracellular Na + content. A step rise in external Na + to 10 meq causes a rapid but transient Na + entry coupled to an excretion of H +, giving rise to a pH i increase. It is shown that the plasma membrane of unfertilized eggs contains a permanent and reversible Na +/H + exchanger which contributes to the regulation of pH i. This exchange occurs with a 1:1 stoichiometry and is independent of metabolic energy. Proton excretion and sodium entry follow saturable kinetics with respect to external Na + and are completely inhibited by amiloride. At fertilization, pH i increases from 7.38 to 7.64 and is maintained at this level by two separate mechanisms: (1) a Na +/H + exchange with the same characteristics as in unfertilized eggs; (2) a H +-excreting system that is dependent on external Na +, amiloride sensitive, and requiring metabolic energy. The relationship between the permanent Na +/H + exchange involved in pH i regulation and the transient Na +/H + exchange occurring at fertilization is discussed.

CO2 and H+ Excretion By Swimming Coho Salmon, Oncorhynchus Kisutch

ABSTRACT Coho salmon, Oncorhynchus kisutch (Walbaum), were swum at constant speed in a ‘Brett-type’ tunnel respirometer. Blood , and pH as well as total CO2 content and red blood cell pH were unchanged during swim ming. The RE (respiratory exchange ratio) was slightly less than 0·7 when the fish was swimming in normal sea water, indicating that some CO2 is retained by the fish. Lowering seawater bicarbonate concentration increased HCO3− transfer, presumably because of passive bicarbonate loss. A reduc tion in seawater pH from 7 ·95 to 7 ·1 sharply reduced both CO2 and hydrogen ion transfer, resulting in very low RE values of about 0 ·2. Hydrogen ion excretion was elevated during prolonged swimming following high speed swimming activity. It would appear that CO2 and hydrogen ion transfer by fish need not be matched and changing internal and external conditions can have a marked and separate effect on hydrogen ion and CO2 excretion and therefore on the RE value.

Regulation of sodium in the shore crabCarcinus maenas, adapted to environments of constant and changing salinities

The activity of Na-K-ATPase was determined in the posterior gills of the shore crabCarcinus maenas during a period following transfer from 35 to 10 ‰ salinity and vice versa at 15 °C. After transfer from high to low salinity, Na-K-ATPase activity increased from 3.2 to 7.0 μmoles Pi mg protein−1 h−1 within a period of 2 to 3 weeks. Transfer of crabs from low to high salinity resulted in reduction of activity from 7.4 to 4.5 μmoles Pi mg protein−1 h−1 within about the same period. The relatively slow response following salinity change indicates that the amounts of Na-K-ATPase in the gills may play a role in hyperionic Na regulation in relatively constant brackish-water environments. Instant responses to salinity result from activation and inhibition of Na-K-ATPase activity by Na. Gill Na-K-ATPase is activated by the Na concentration of the incubation medium to attain a steep maximum at about 75 mM Na, which corresponds to the lowest environmental Na levels tolerated byC. maenas equivalent to a salinity of ca 6 ‰. Activity greatly decreased towards higher Na levels, equivalent to the salinity of normal sea water, at which hyperregulation no longer occurs. Selective addition of either Na or Cl to brackish water of 9 ‰ S resulted in effective hyperregulation of the non-increased ion, and passive distribution between medium and blood of the increased ion. These data indicate that under appropriate conditions the normally coupled transport of Na and Cl may be uncoupled and take place independently of each other.

Teleconnections and the siege of time

AbstractThe recent surge of interest in climate has resurrected correlation coefficients as tools for identifying ‘significant’ atmospheric teleconnections. Unfortunately, large coefficients may diminish and even change sign with time, suggesting absence of real physical relationships.Some statistical evidence supports the view that higher than normal sea surface temperatures in the central and eastern Pacific ‘cause’ less than normal rainfall in the Indian summer monsoon. However, a study of individual Augusts uncovers major exceptions and at the same time fails to confirm that Indian summer rainfall influences central and eastern Pacific rainfall or that the Southern Oscillation Index can be consistently related to conditions in either region.Around 1963‐1964 the apparent relationship between the Southern Oscillation Index and Indian rainfall reversed. At about the same time other global climatic relationships changed, raising the possibility of identifying and describing a major global climatic singularity separating two distinct statistical populations.