Area reduction and trace element pollution in Nile Delta wetland ecosystems

The three main Nile Delta wetland ecosystems, Manzala, Burullus and Edku lagoons, are among the most ecologically important and productive habitats in Egypt. We studied the area degradation and the human health risks associated with trace metal accumulation in Tilapia zillii harvested from these lakes. The area of Manzala lagoon has shrunken from about 3035 km² in 1800 to about 288 km² in 2015, the area of Edku has shrunken from about 336 km² in 1824 to about 18 km² in 2014, and the area of Burullus has shrunken from about 1116 km² in 1949 to about 546 km² in 2014. This area degradation is attributed to drying for housing, land reclamation and fish farming. As a result, the concentration of pollutants and nutrients has subsequently increased, and large parts of the lakes have been overgrown with aquatic vegetation, which increased the rate of degradation and land transformation. Metal pollution was detected in water, sediment and edible fish harvested from the lakes. The hazard index, an indicator of human health risks associated with fish consumption, showed adverse health effects of zinc and lead metals for habitual fish consumers. The impact of the high dam on the lakes was discussed.     

Productivity of theEcklonia cava community in a bay of Izu Peninsula on the Pacific Coast of Japan

Net production of theEcklonia cava community was monitored on a monthly basis for a year, and annual net production was estimated. Growth rate of blades reached a maximum of about 13 g dry wt·m^?2·day^?1 in spring and a minimum of about 2 g dry wt·m^?2·day^?1 in late summer. Annual production of blades was calculated to be 2.84 kg dry wt·m^?2·year^?1. If the growth of stipes is taken into account, annual net production is estimated to be about 2.9 kg dry wt·m^?2·year^?1. Standing crop was monitored monthly for two and a half years, and a close negative correlation was found between seasonal change in standing crop and net production. Standing crop reached a maximum of about 3 kg dry wt·m^?2 in summer and a minimum of about 1 kg dry wt·m^?2 in winter. Low productivity in summer at a period of maximum biomass may be explained by the dense canopy and the large area of reproductive portion occupying a blade, which diminish net assimilation.     

Effect of warm acclimation on the cationic concentrations in the extracellular and intracellular body fluid of hibernating Rhagium inquisitor beetles

• 1.1. The effect of warm acclimation on the cationic concentrations of hibernating Rhagium inquisitor beetles was studied.
• 2.2. Following warm acclimation, the extracellular concentration of Mg²⁺ dropped from about 80 to about 50 mM. For Na⁺ and K⁺ the extracellular concentration remained constant at about 40 mM. The estimated intracellular concentration of Mg²⁺ was not affected by the warm acclimation, being about 80 mM in both groups of beetles. The corresponding concentration of Na⁺ increased from about 20 to about 30 mM, whereas for K⁺ there was no change, the concentration being about 140mM in both groups of beetles.
• 3.3. The marked drop in the extracellular concentration of Mg²⁺ might indicate that Mg²⁺ is involved in the regulation of the concentration of glycerol, which was reduced to zero during the warm acclimation.
• 4.4. The estimated equilibrium potentials of the respective ions might indicate that K⁺ is in electrochemical equilibrium across the cell membranes, whereas Na⁺ and to a lesser extent Mg²⁺ are actively transported out of the cells.
• 5.5. For Na⁺ there was a high positive equilibrium potential even in the cold acclimated beetles, indicating that Na⁺ has a high electrochemical potential difference across the cell membranes even at low temperatures. This is in agreement with the observation that hibernating insects are able to perform coorclinated walking immediately after heating to temperatures near zero.

     

The ranging patterns of elephants in Marsabit protected area,Kenya: the use of satellite‐linked GPS collars

We investigated the ranging patterns of elephants in the Marsabit protected area, north eastern Kenya, to ascertain the range of bachelor and female family herds in different seasons, and to identify corridor and noncorridor areas. Data were acquired for five bachelor and four female family herds equipped with satellite‐linked geographical positioning system collars, and monitored from December 2005 to December 2007. Distinct dry (about 260 km²) and wet seasons (about 910 km²) ranges were observed, with connecting corridors (north‐eastern corridor: about 90 km long, about 2‐7 km wide; southern corridors: about 10‐20 km long, about 2‐3 km wide). The dry season range corresponded with Marsabit evergreen forest, while the wet season range matched with dry deciduous lowland shrubs. The ranging elephants moved at speed of about 0.2‐20 kmh^?1. Bachelor herds moved faster than female family herds. Elephants moved fast during the intermediate and wet seasons than during the dry season. The speed of ranging elephants was over 1 kmh^?1 in the corridor areas and about 0.2 to less than 1 kmh^?1 in the non‐corridor areas. Expansion of settlements towards corridor areas needs to be controlled to avoid future blocking of connectivity between wet and dry season elephant ranges.     

Diacetyl fermentation coupled with pervaporation using oleyl alcohol supported liquid membrane

Pervaporation using oleyl alcohol supported liquid membrane was successfully applied to diacetyl fermentation by immobilized lactic acid bacteria. Diacetyl productivity was about 10 g·m⁻³·h⁻¹, while productivity during batch fermentation was about 6 g·m⁻³·h⁻¹. Diacetyl yield from consumed glucose was about 0.04 g·g⁻¹ which was 4 times as large as that of batch fermentation. The pervaporation functioned favorably on actual fermentation broth. The flux of the permeate and the diacetyl separation factor for the pervaporation were about 9 g·m⁻²·h⁻¹ and 36, respectively, and these values were maintained at almost constant levels during fermentation. Diacetyl concentration in the permeate was about 2 kg·m⁻³, which is sufficiently high for commercial use.     

Effects of glucagon and Na+ on the control of extramitochondrial free Ca2+ concentration by mitochondria from liver and heart

Rat liver mitochondria maintain the extramitochondrial free Ca²⁺ concentration at pCa²⁺ of about 6.15. Glucagon pre-treatment of the rats does not alter this value. Rat heart mitochondria maintain free Ca²⁺ at a pCa²⁺ value of about 6.7, addition of 5mM Na⁺ changes this to a value of about 5.85.     

Seasonal changes in composition and biomass of epilithic algal floras of a chalk stream and a soft water stream with estimates of production

Microscopic epilithic algae in the River Itchen at Otterbourne near Southampton and in the Ober Water in the New Forest were studied during 1984 and 1985. The River Itchen rises from chalk springs and has a steady pH near 8.2 and a mean alkalinity of 236 mg HCO₃ 1^–1; at the study site the river is about 16 m wide and 20 cm deep, with a mean flow rate of 0.33 m s^–1 and a discharge ranging through the year between 0.34 and 2.46 m³ s^–1. The Ober Water, which drains sands and gravels, has a pH between 6.9 and 7.2 and a mean alkalinity of about 50 mg HCO₃ 1^–1; at the study site it is about 6 m wide, with a mean flow rate of 0.27 m s^–1 and a discharge ranging through the year between 0.08 and 1.0 m³ s^–1.Epilithic algae removed from the pebbles that form the major part of the beds of both streams show seasonal changes in abundance and composition. Diatoms peaked in April/May and dominate the epilithic flora in both streams, comprising 70–95% of all algal cells; highest numbers of chlorophytes occurred in summer and cyanophytes increased in autumn. The species composition of the epilithic flora in the two streams was different, as was the population density; algal cell numbers ranged between 500 and 7000 cells mm^–2 of stream floor in the River Itchen and between 8 and 320 cells mm^–2 of stream floor in the Ober Water. The chlorophyll a content of epilithic algae in the River Itchen ranged between 115 and 415 mg m^–2 of stream floor, representing an annual mean biomass of about 8 g m^–2, whereas in the Ober Water a chlorophyll a content of 2.2 to 44 mg m^–2 of stream floor was found, representing an annual mean biomass of about 1 g m^–2. Cautious estimates of the annual production of epilithic algae in these streams suggest a value of about 600 g organic dry weight m^–2 in the River Itchen and about 75 g m^–2 in the Ober Water.     

Accumulation of malate in guard cells of Vicia faba during stomatal opening

Summary The level of malate in the epidermis from illuminated leaves of Vicia faba was greater than in that from dark-treated leaves. A difference in the malate level was still detected after the epidermis had been treated by rolling so that only the guard cells remained alive. The results suggest that malate may accumulate in guard cells on illumination. In subsequent experiments, stomatal apertures were measured, and potassium as well as malate was analysed in extracts of epidermis. In illuminated leaves, the potassium content of rolled epidermis increased from about 90 to about 335 picoequivalents mm^-2 of epidermis whele malate increased from about zero to about 71 pmoles mm^-2 and the stomata opened; in dark-treated leaves, the potassium content of rolled epidermis decreased slightly, the malate level remained about zero, and the stomata showed very slight further closure. The measured increase in potassium is likely to represent an increase in potassium concentration in the guard cells of about 0.4 Eq l^-1 with stomatal opening; the increase in malate could correspond to 0.23 Eq l^-1 (with respect to potassium) in the guard cells. Thus, malate accumulating in guard cells could balance about half of the potassium taken up by guard cells when stomata open in the light.     

Further studies on the photosynthesis of carrot tissue cultures

The influence of kinetin and sucrose on the photosynthetic activity of carrot (Daucus carota) tissue cultures in relation to growth was investigated. The results showed that light contributes heavily to the growth of tissue cultures measured in terms of fresh and dry weight and cell division activity. In light, the fresh weight, dry weight, and number of cells per explant were about or more than doubled. This indicated that after the development of chloroplasts, carrot tissue cultures can grow autotrophically at least as far as energy and carbon are concerned. Kinetin was shown to have an important role in developing the photosynthetic apparatus and photosynthetic activity of tissue cultures as manifested by the increase of chlorophyll content (60%), Hill activity (about 3-fold), and ¹⁴C-fixation from NaH¹⁴CO₃ (about 20%). On the other hand, the presence of sucrose in the medium reduced the chlorophyll content by about 30% and ¹⁴C-fixation from NaH¹⁴CO₃ in the soluble fraction by about 60%. A possible correlation between the influence of kinetin on sugar uptake and the effect of kinetin on ¹⁴C-fixation from NaH¹⁴CO₃ was discussed.     

Tritosol: A new scintillation cocktail based on Triton X-100

A scintillation cocktail consisting of 3.0 g PPO, 257 ml Triton X-100, 106 ml ethanol, 37 ml ethylene glycol, and 600 ml xylene is described. A linear relationship between counting efficiency and the external standard ratio could be demonstrated over a wide range of quenching. The counting efficiencies (unquenched) for³H are about 47%, for¹⁴C about 87%, and for⁴⁵Ca about 80%.     

Carbohydrate metabolism in Manduca sexta during late larval development

The carbohydrate metabolism in Manduca sexta underwent significant changes during late larval development. Approximately 10% of fat body glycogen phosphorylase was active during the feeding period of the 5th instar, pharate-pupal development and after the pupal moult; it is concluded that glycogen synthesis prevailed. During the last larval and the pupal moult, as well as the wandering stage the percentage of active phosphorylase was significantly increased indicating that fat body glycogen stores were broken down to supply substrates to meet the demands of carbohydrate metabolism. In the course of the last larval moult and the wandering stage the fat body glycogen content decreased significantly from about 300 to about 200 μg mg⁻¹ dry mass substantiating that carbohydrates were released from the fat body. Prior to phosphorylase activation, the concentrations of total haemolymph sugars decreased significantly from about 12 to about 6 mg trehalose equivalents ml⁻¹ (last larval moult) and from about 18 to about 12 mg ml⁻¹ (wandering stage), and increased again slightly when phosphorylase was activated. The haemolymph glucose concentration decreased significantly from about 1.1 to 0.3 mg ml⁻¹ (last larval moult) and in the course of the 5th-instar feeding period from about 1.1 to 0.2 mg ml⁻¹, and remained at this level until the beginning of adult development. The amount of chitosan present in the cuticle increased steadily during the feeding period of the 5th instar from about 10 to 110 mg. It appears that fat body glycogen might be broken down during the last larval moult and the wandering period to provide substrates for chitin synthesis. A dramatic decrease in the amount of chitosan was observed prior to the pupal moult.     

Buried seed population in the herbaceous lomas on Loma Ancon in the coastal desert of central Peru

Herbaceous lomas in the Peruvian coastal desert, of South America establish in spring, and its habitat is limited to the southern or southwestern slopes along the coast that are affected by thick fog. The time of appearance, the duration and the thickness of the fog vary greatly from year to year, so the lomas can grow only in habitats with enough water to, sustain seed germination and plant growth. This paper studies the species composition and density of the buried seed population, of the herbaceous lomas of Loma Ancon in order to clarify the mechanisms of the lomas' establishment. The mean number of species with viable seeds was about, 12 spp. m⁻² and that of dead seeds was about 22 spp. m⁻². The dominant species wereSolanum tuberiferum, S. pinnatifidum andNolana humifusa, both in viable and dead seeds. Viable seed density was about 5000–8000 seeds m⁻², which is comparable with the seed densities of other herbaceous communities. Dead seed density was about 15000–27000 seeds m⁻², or nearly three times the viable seed density, because the rate of decomposition was slow in the extremely dry conditions. The net increase of viable seeds by seed production was estimated at about 5000 seeds m⁻² in 1980, and the increase in the number of dead seeds was 2200 seeds m⁻².     

Macronuclear development and gene expression in the exconjugants of Paramecium caudatum

Postzygotic nuclei are determined to be macronuclear anlagen immediately after the third division of the fertilization nucleus in Paramecium caudatum. Soon after determination, chromatic aggregates appear in the anlagen. Microspectrophotometry revealed that a marked increase in the DNA content of macronuclear anlage occurred after disintegration of the chromatic aggregates, about 18 hr after nuclear determination. The phenotypic expression of five genes was investigated during the developmental process; +^tnd-1, +^tnd-2, +^cnrA, +^cnrB, and +^cnrD. The phenotypic expression of +^tnd-1 began about 18 hr after nuclear determination and of +^cnrB at about 24 hr at 27°C. However, phenotypic expression of the three other genes began about 40 hr after determination. It can be concluded that some of the genes of macronuclear anlagen begin to be expressed at or before the first measurable increase in the amount of DNA of the anlagen.     

Reconstitution and Characterization of a Calmodulin-Stimulated Ca-Pumping ATPase Purified from Brassica oleracea L

Purification and functional reconstitution of a calmodulin-stimulated Ca²⁺-ATPase from cauliflower (Brassica oleracea L.) is described. Activity was purified about 120-fold from a microsomal fraction using calmodulin-affinity chromatography. The purified fraction showed a polypeptide at 115 kD, which formed a phosphorylated intermediate in the presence of Ca²⁺, together with a few polypeptides with lower molecular masses that were not phosphorylated. The ATPase was reconstituted into liposomes by 3-([cholamidopropyl]-dimethylammonio-)1-propanesulfonate (CHAPS) dialysis. The proteoliposomes showed ATP-dependent Ca²⁺ uptake and ATPase activity, both of which were stimulated about 4-fold by calmodulin. Specific ATPase activity was about 5 μmol min⁻¹ (mg protein)⁻¹, and the Ca²⁺/ATP ratio was 0.1 to 0.5 when the ATPase was reconstituted with entrapped oxalate. The purified, reconstituted Ca²⁺-ATPase was inhibited by vanadate and erythrosin B, but not by cyclopiazonic acid and thapsigargin. Activity was supported by ATP (100%) and GTP (50%) and had a pH optimum of about 7.0. The effect of monovalent and divalent cations (including Ca²⁺) on activity is described. Assay of membranes purified by two-phase partitioning indicated that approximately 95% of the activity was associated with intracellular membranes, but only about 5% with plasma membranes. Sucrose gradient centrifugation suggests that the endoplasmic reticulum is the major cellular location of calmodulin-stimulated Ca²⁺-pumping ATPase in Brassica oleracea inflorescences.     

What' New: More advances in DNA sequencing technology

Since their introduction about ten years ago the rapid methods for sequencing DNA based either on selective chemical degradation¹ or primed enzymatic synthesis² have been subject to a number of modifications and improvements.^{3, 4} Two recently published papers describe further advances in these technologies: a method for obtaining information about DNA sequences directly from uncloned mammalian genomic DNA⁵ and a possible first step towards the automation of DNA sequencing⁶.     

Sodium and Potassium Ion Effluxes from Squid Axons under Voltage Clamp Conditions

Squid giant axons loaded with Na²⁴ were subjected to short duration (0.5 msec.) clamped depolarizations of about 100 mv at frequencies of 20/sec. and 60/sec. while in choline sea water. Under such conditions the early outward current was just about maximal at the time of termination of the clamping pulse. An integration of the early current versus time record gave 1.2 μcoulomb/cm² pulse, while a measurement of the extra Na²⁴ efflux resulting from repetitive pulsing gave a charge transfer of 1.4 μcoulomb/cm² pulse. In sodium-containing sea water and with pulses 50-75 mv more positive than E_Na the Na²⁴ efflux is about 3 times the measured charge transfer. The efflux of K⁴² from a previously loaded axon into normal sea water is only 50 per cent of the measured charge transfer when the membrane is held for about 5 msec. at a potential such that there is no early current, and such pulses are at 10-20/sec. The experiments appear to confirm the suggestion that the early current during bioelectric activity is sodium but provide unsatisfactory support for the identification of the delayed but sustained current solely with potassium ions. Resting Na⁺ efflux is 0.6 pmole/cm² sec. mmole [Na]₁, while the apparent K⁺ efflux is about 250 pmole/cm² sec. and is little affected by hyperpolarization.     

The benthos off King George Island (South Shetland Islands,Antarctica): further evidence for a lack of a latitudinal biomass cline in the Southern Ocean

The benthic fauna off King George Island (South Shetland Islands, Antarctica) was investigated during "Polarstern" expedition ANT XV/3 in March 1998. Samples were taken along two cross-shelf/slope transects both north (Drake Passage) and south of the island (Bransfield Strait, off Potter Cove) at water depths ranging from 130 m to 2,000 m. For a quantitative inventory, a multibox corer was used at nine stations to collect mostly infaunal macrobenthos; at seven stations, seabed photography was employed concomitantly to survey the epibenthic megafauna. Macrofauna abundances ranged from 730 ind. m^–2 at 2,000 m to >14,000 ind. m^–2 at 100 m; biomass values varied between about 50 g wet mass m^–2 (6 g ash-free dry mass m^–2) at 2,000 m and about 950 g wet mass m^–2 (about 90 g ash-free dry mass m^–2) at 200 m. Densities were dominated everywhere by polychaetes, followed by bivalves, crustaceans and ophiuroids; in terms of biomass, krill and holothurians surpassed polychaetes at some stations. No significant differences between the northern and the southern transects in total abundance and biomass were obvious. Megafauna abundances were clearly higher south of King George Island, totalling about 110–150 ind. m^–2 on the shelf (235–330 m) and about 50 ind. m^–2 at the continental slope (750 m), whereas along the northern transect they reached values of only 21–31 ind. m^–2 on the shelf (130–430 m) and decreased at the continental slope (950 m) to about 5 ind. m^–2. A brittle star, Ophionotus victoriae, strongly dominated the southern-shelf epibenthos, with relative abundances of 70–95% and a biomass of about 40–80 g wet mass m^–2 (about 4–7 g ash-free dry mass m^–2), but was numerically less important at the slope (5%) where ammotheid pycnogonids prevailed (80%). Macro- and megabenthos distribution patterns were characterized by a pronounced shelf-slope gradient – in standing stock as well as in faunistic composition – but this resemblance was statistically not significant. This finding indicates that the spatial distributions of macrobenthos and megabenthos are primarily determined by a depth-dependent factor, most probably food supply, but apparently respond differently to secondary driving forces, possibly seabed features. Our results provide further evidence for the notion that there is no distinct latitudinal gradient in benthic abundance and biomass in the Southern Ocean between the South American Magellan region and high-Antarctic waters of the Weddell Sea.     

IAA-induced hyperpolarization of the membrane potential in isolated cells fromMimosa pulvinus

Upon treatment with 10⁻⁴ M IAA the membrane potential of an isolated cell from the main pulvinus, ofMimosa pudica L. depolarized by about 6 mV in 2–5 min, but later it gradually hyperpolarized by about 30 mV. The membrane potential of a motor cell in the main pulvinar tissue hyperpolarized by about 80 mV 1 hr after application of 10⁻⁴ M IAA.     

The second investigation of Lake Puma Yum Co located in the Southern Tibetan Plateau,China

Limnological features of Lake Puma Yum Co, a typical alpine lake located at the altitude of 5030 m in the Tibetan Plateau, China, are described based on the findings of the second expedition in September 2004. The lake surface is about 280km² and maximal depth is 65 m. Total inflow just after the rainy season was estimated to be about 860 000m³ day⁻¹, and the lake water was drained from a newly excavated channel at a rate of 960 000m³ day⁻¹. We may have to expect undesirable lowering of the water level by this new drainage, especially in the dry season. Thermocline developed from 20 to 30 m depth, and the euphotic zone reached the 50 m depth. Dissolved oxygen in surface water was supersaturated as in productive lakes, although there were no large point and nonpoint sources of nutrient in the catchment. Vertical distribution of phytoplankton biomass and primary production suggested the presence of photoinhibition. What should be noted about the flora and fauna is that a Chara zone and a shell zone were distributed at about 30 or 40 m of depth.