Vegetation mapping with the aid of low-altitude aerial photography

Abstract. A technique for fine-scale vegetation mapping with the aid of low-altitude aerial photography was developed. The procedure is as follows: 1. The site is divided into a lattice pattern - in case the site is too large to fit into a single photograph with satisfactory resolution. The coordinates of every lattice point are surveyed to be used as control points for geometric correction. A photograph of each block of the lattice is taken using a remote-controlled camera system lifted by a captive helium balloon. 2. The vegetation is classified on the basis of a phytosociological survey. 3. The shapes and locations of vegetation patches appearing in the photographs are entered into a computer, using a digitizer. A geometric correction is carried out through coordinate transformation referring to the coordinates of the control points and subsequently a draft vegetation map is produced. Finally, discrepancies are corrected and the map is coloured to produce the final version of the vegetation map. This technique was applied to vegetation mapping at a bar, 500 m wide and 2 km long, in the river Yoshino in Shikoku, Japan. A fine-scale vegetation map was obtained and used to analyse the influence of plants on geomorphic processes and community-specific hydrogeomorphic conditions on the bar.     

Selection and proliferation of rapid growing cell lines from embryo derived cell cultures of yew tree (Taxus cuspidata Sieb. et Zucc)

Calli were induced from 300,000 embryos isolated from immature to mature stage of seeds collected on late September from 14 elite trees. When the embryos were cultured onto plastic Petri-dish containing 20 mL of modified B5 basal medium supplemented with 3% (w/v) sucrose, 500 mg/L casein hydrolysate, 250 mg/L myo-inositol, 0.5% (w/v) polyvinyl polypyrrolidon (PVPP), 2×MS vitamins, 0.5 mg/L gibberellic acid, and 10 mg/L 2,4-D after 2 weeks of culture, yellowish-white calli were immediately formed on the surfaces of embryos, and subcultured for 4 weeks in same culture medium. Because most of calli maintained for more than 3 months were revealed differences in their colors, surface texture, and growth rate, visual selection was made for first round screening. When the size of visually selected calli larger than 19 mm in their diameter were inoculated, persistent proliferation was observed. Among the plating methods tested for the selection of rapid growing cell lines at single cell and/or small cell aggregate level, 2-layer spread plating revealed as the best for single cell cloning. To enhance cell growth and maintain high rate of viability for long-term culture of yew cells in bioreactor, final cell volume less than 50% in SCV seemed to be the best. Time course study revealed that 30% of inoculum density was suitable for fed batch culture. Among the tested conditional media, the rate of 1∶2 (old medium: fresh medium) was recorded at the best for cell growth.     

Limitations of Chromogranin A in clinical practice

Context: Usefulness of circulating Chromogranin A (CgA) for the diagnosis of neuroendocrine tumors (NEN) is controversial. The aim of the present study was to assess the actual role of this marker as diagnostic tool. Methods: Serum blood samples were obtained from 42 subjects affected with NEN, 120 subjects affected with non-endocrine neoplasias (non-NEN) and 100 non-neoplastic subjects affected with benign nodular goitre (NNG). Determination of CgA was performed by means of immunoradiometric assay. Results: The CgA levels among NEN-patients were not significantly different from NNG and non-NEN subjects. The Receiver operating characteristic (ROC) curves analysis failed to identify a feasible cut-off value for the differential diagnosis between NEN and the other conditions. Conclusion: Serum CgA is not helpful for the first-line diagnosis of NEN.     

Cytoplasm-enriched fragments ofChara: structure and electrophysiology

Summary Cytoplasm-enriched fragments prepared from internodal cells ofChara corallina by centrifugation contain membrane bound vesicles ranging in size from a few m to hundreds of m. If the fragments are incubated in artificial pond water (APW) of pH₀ above 6.5, neutral red stains the inside of many vesicles bright crimson, suggesting the presence of inward proton-pumping. In APW of pH₀ below 6 crimson vesicles are found less frequently. Under such conditions most vesicles remain unstained inside and some develop indistinct pink halos. After a few days most fragments form a central vacuole, which stains red, regardless of the pH₀. The cytoplasmic layer still contains vesicles after vacuole formation.In order to identify the membrane bounding the vesicles various fluorescent probes were applied either by injection into the fragment or directly onto the vesicles released into artificial cytoplasm. Lucifer yellow or 6 COOH-F move readily across the tonoplast in intact cells, but did not enter any vesicles. On the other hand, the fluorescent cationic stain DIOC, which is used to highlight mitochondria and especially endoplasmic reticulum, stained the vesicle membrane. Numerous elliptical or kidney shaped nuclei in the flowing cytoplasm were highlighted with DAPI. In some fragments the nuclei formed large agreggates sometimes filling the width of the fragment.Patch-clamping the vesicles in artificial cytoplasm showed the presence of several kinds of channels, some displaying similar behaviour to the K⁺ channels observed in cytoplasmic droplets.Analogous to the plasmalemma of intact cells, the fragments without vacuoles displayed electrophysiological states dominated by either K⁺ conduction, H⁺ (or OH^–) conduction or the proton pump. On the other hand, excitation transients in fragments were of low amplitude or absent altogether. Detailed comparisons of data from fragments and intact cells are shown. The effect of vacuole formation on fragment electrophysiology was also explored.     

Respiratory Na+ pump and Na+-dependent energetics inVibrio alginolyticus

The marine bacteriumVibrio alginolyticus was found to possess the respiratory Na⁺ pump that generates an electrochemical potential of Na⁺, which plays a central role in bioenergetics ofV. alginolyticus, as a direct result of respiration. Mutants defective in the Na⁺ pump revealed that one of the two kinds of NADH: quinone oxidoreductase requires Na⁺ for activity and functions as the Na⁺ pump. The Na⁺ pump composed of three subunits was purified and reconstituted into liposomes. Generation of membrane potential by the reconstituted proteoliposomes required Na⁺. The respiratory Na⁺ pump coupled to the NADH: quinone oxidoreductase was found in wide varieties of Gramnegative marine bacteria belonging to the generaAlcaligenes, Alteromonas, andVibrio, and showed a striking similarity in the mode of electron transfer and enzymic properties. Na⁺ extrusion seemed to be coupled to a dismutation reaction, which leads to the formation of quinol and quinone from semi-quinone radical.     

Effect of Increased Glucose Levels on Na+/K+-Pump Activity in Cultured Neuroblastoma Cells

Neuroblastoma cells were used to analyze the effect of elevated glucose levels on myo-inositol metabolism and Na+/K+-pump activity. The activity of the Na+/K+ pump in neuroblastoma cells is almost totally sensitive to ouabain inhibition. Culturing neuroblastoma cells in 30 mM glucose caused a significant decrease in Na+/K+-pump activity, myo-inositol metabolism, and myo-inositol content, compared to cells grown in the presence of 30 mM fructose. Glucose supplementation also caused a large intracellular accumulation of sorbitol. The aldose reductase inhibitor sorbinil prevented the abnormalities in myo-inositol metabolism and partially restored Na+/K+-pump activity in neuroblastoma cells cultured in the presence of elevated glucose levels. These results suggest that the accumulation of sorbitol by neuroblastoma cells exposed to elevated concentrations of extracellular glucose causes a decrease in myo-inositol metabolism and these abnormalities are associated with a reduction in Na+/K+-pump activity.     

Voltage dependence of Na/K pump current inXenopus oocytes

Summary Stage V and VI (Dumont, J.N., 1972.J. Morphol. 136:153–180) oocytes ofXenopus laevis were treated with collagenase to remove follicular cells and were placed in K-free solution for 2 to 4 days to elevate internal [Na]. Na/K pump activity was studied by restoring the eggs to normal 3mm K Barth's solution and measuring membrane current-voltage (I–V) relationships before and after the addition of 10 m dihydroouabain (DHO) using a two-microelectrode voltage clamp. Two pulse protocols were used to measure membraneI–V relationships, both allowing membrane currents to be determined twice at each of a series of membrane potentials: (i) a down-up-down sequence of 5 mV, 1-sec stair steps and (ii) a similar sequence of 1-sec voltage pulses but with consecutive pulses separated by 4-sec recovery periods at the holding potential (–40 mV). The resulting membraneI–V relationships determined both before and during exposure to DHO showed significant hysteresis between the first and second current measurements at each voltage. DHO difference curves also usually showed hysteresis indicating that DHO caused a change in a component of current that varied with time. Since, by definition, the steady-state Na/K pumpI–V relationship must be free of hysteresis, the presence of hysteresis in DHO differenceI–V curves can be used as a criterion for excluding such data from consideration as a valid measure of the Na/K pumpI–V relationship. DHO differenceI–V relationships that did not show hysteresis were sigmoid functions of membrane potential when measured in normal (90mm) external Na solution. The Na/K pump current magnitude saturated near 0 mV at a value of 1.0–1.5 A cm^–2, without evidence of negative slope conductance for potentials up to +55 mV. The Na/K pump current magnitude in Na-free external solution was approximately voltage independent. Since these forward-going Na/K pumpI–V relationships do not show a region of negative slope over the voltage range –110 to +55 mV, it is not necessary to postulate the existence of more than one voltage-dependent step in the reaction cycle of the forward-going Na/K pump.     

Calcium mobilizing hormones activate the plasma membrane Ca2+ pump of pancreatic acinar cells

Summary ⁴⁵Ca fluxes and free-cytosolic Ca²⁺ ([Ca²⁺] _i ) measurements were used to study the effect of Ca²⁺-mobilizing hormones on plasma membrane Ca²⁺ permeability and the plasma membrane Ca²⁺ pump of pancreatic acinar cells. We showed before (Pandol, S.J., et al., 1987.J. Biol. Chem. 262:16963–16968) that hormone stimulation of pancreatic acinar cells activated a plasma membrane Ca²⁺ entry pathway, which remains activated for as long as the intracellular stores are not loaded with Ca²⁺. In the present study, we show that activation of this pathway increases the plasma membrane Ca²⁺ permeability by approximately sevenfold. Despite that, the cells reduce [Ca²⁺]i back to near resting levels. To compensate for the increased plasma membrane Ca²⁺ permeability, a plasma membrane Ca²⁺ efflux mechanism is also activated by the hormones. This mechanism is likely to be the plasma membrane Ca²⁺ pump. Activation of the plasma membrane Ca²⁺ pump by the hormones is time dependent and 1.5–2 min of cell stimulation are required for maximal Ca²⁺ pump activation. From the effect of protein kinase inhibitors on hormone-mediated activation of the pump and the effect of the phorbol ester 12-0-tetradecanoyl phorbol, 13-acetate (TPA) on plasma membrane Ca⁺ efflux, it is suggested that stimulation of protein kinase C is required for the hormone-dependent activation of the plasma membrane Ca²⁺ pump.     

Electrogenic behavior of the human red cell Ca2+ pump revealed by disulfonic stilbenes

Summary A systematic study was made of the action of 4-acetamido-4-isothiocyanostilbene-2,2-disulfonic acid (SITS) and 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS) on active Ca²⁺ transport of human erythrocytes. Pumping activity was estimated in inside-out vesicles (IOV's) by means of Ca²⁺-selective electrodes or use of tracer⁴⁵Ca²⁺. The stilbenes exhibited an approximately equal inhibitory potency and their action could be overcome by carbonyl cyanidep-trifluoromethoxyphenylhydrazone (FCCP) at low but not at high stilbene concentrations. In the absence of DIDS. Ca²⁺ transport was not affected upon addition of valinomycin, but it was appreciably reduced when vesicles were preincubated with low DIDS concentrations. Such an effect was strictly dependent on the external K⁺ concentration and it was abolished when valinomycin was added together with FCCP. Similar results were obtained using IOV's prepared from intact cells which had been previously exposed to the stilbene. The findings clearly demonstrate the presence in human red cells of a partially electrogenic Ca²⁺ pump, exchanging one Ca²⁺ ion for one proton.     

Mechanisms of fusicoccin action: A dominant role for secondary transport in a higher-plant cell

Fusicoccin (FC) is commonly thought to promote electrogenic H⁺ extrusion through its action on the H⁺-ATPase of the plant plasma membrane. Nonetheless, essential support from rigorous electrophysiological analysis has remained largely absent. The present investigation surveys the effects of FC on the charge transport properties at the membrane of a higher-plant cell — stomatal guard cells of Vicia faba L. — for which the electrical geometry is defined, and from which the voltage-dependent kinetic characteristic for the pump has been identified. Current-voltage (I-V) relations of the guard cells were determined before and during treatments with FC, and during brief exposures to NaCN plus salicylhydroxamic acid. Responses of the pump and of the ensemble of secondary transport processes were identified in the whole-membrane conductance-voltage relations and in the difference-current-voltage (dI-V) characteristic for the pump. In 0.1 mM K⁺, exposure to 10 M FC shifted guard-cell potentials negative by 29–61 mV. Current-and conductance-voltage profiles indicated limited changes in the pump I-V characteristic, an observation which was confirmed through explicit kinetic analysis of pump dI-V relations. However, the voltage response was accompanied by a 1.5-to 2.6-fold fall in membrane conductance. These results challenge conventional views of fusicoccin action by ascribing the electrical responses to reduced current passage through secondary transport pathways as well as to enhanced electrogenic ion pumping.Abbreviations and symbols Hepes 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - SHAM salicylhydroxamic acid - FC fusicoccin - V _m free-running membrane potential - G _m membrane slope conductance at V _m - (d)I-V (difference) current-voltage (relation) - G-V slope conductance-voltage (relation)