SAIN Invasive Plant Pests Resource Collection for Egeria densa
Common name: Brazilian eloda
| Title: The respiratory burst and electrolyte leakage induced by sulfhydryl blockers in Egeria densa leaves are associated with H2O2 production and are dependent on Ca2+ influx. |
| Author: Marre-Maria-Teresa {a}; Amicucci-Enrica; Zingarelli-Luisa; Albergoni-Francesco; Marre-Erasmo. |
| Source: Plant-Physiology-Rockville. Dec., 1998; 118 (4) 1379-1387. |
| Source Type: Journal |
| Publication Date: 1998 |
| Abstract: In leaves of Egeria densa Planchon, N-ethylmaleimide (NEM) and other sulfhydryl-binding reagents induce a temporary increase in nonmitochondrial respiration (DELTAQO2) that is inhibited by diphenylene iodonium and quinacrine, two known inhibitors of the plasma membrane NADPH oxidase, and are associated with a relevant increase in electrolyte leakage (M. Bellando, S. Sacco, F. Albergoni, P. Rocco, M.T. Marre (1997) Bot Acta 110: 388-394). In this paper we report data indicating further analogies between the oxidative burst induced by sulfhydryl blockers in E. densa and that induced by pathogen-derived elicitors in animal and plant cells: (a) NEM- and Ag+-induced DELTAQO2 was associated with H2O2 production and both effects depended on the presence of external Ca2+; (b) Ca2+ influx was markedly increased by treatment with NEM; (c) the Ca2+ channel blocker LaCl3 inhibited DELTAQO2, electrolyte release, and membrane depolarization induced by the sulfhydryl reagents; and (d) LaCl3 also inhibited electrolyte leakage induced by the direct infiltration of the leaves with H2O2. These results suggest a model in which the interaction of sulfhydryl blockers with sulfhydryl groups of cell components would primarily induce an increase in the Ca2+ cytosolic concentration, followed by membrane depolarization and activation of a plasma membrane NADPH oxidase. This latter effect, producing active oxygen species, might further influence plasma membrane permeability, leading to the massive release of electrolytes from the tissue. |
| Title: Fusicoccin counteracts the n-ethylmaleimide and silver-induced stimulation of oxygen uptake in Egeria densa leaves. |
| Author: Marre-Maria-Teresa {a}; Albergoni-Francesco. |
| Source: Plant-Physiology-Rockville. Feb., 1998; 116 (2) 681-686. |
| Source Type: Journal |
| Publication Date: 1998 |
| Abstract: It was previously shown that a number of sulfhydryl (SH) group reagents (N-ethylmaleimide (NEM), iodoacetate, Ag+, HgCl2, etc.) can induce a marked, transitory stimulation of O2 uptake (QO2) in Egeria densa leaves, insensitive to CN- and salicylhydroxamic acid and inhibited by diphenylene iodonium and quinacrine. The phytotoxin fusicoccin (FC) also induces a marked increase in O2 consumption in E. densa leaves, apparently independent of the recognized stimulating action on the H+-ATPase. In this investigation we compared the FC-induced increase in O2 consumption with those induced by NEM and Ag+, and we tested for a possible interaction between FC and the two SH blockers in the activation of QO2. The results show (a) the different nature of the FC- and NEM- or Ag+-induced increases of QO2; (b) that FC counteracts the NEM- (and Ag+)-induced respiratory burst; and (c) that FC strongly reduces the damaging effects on plasma membrane permeability observed in E. densa leaves treated with the two SH reagents. Two alternative models of interpretation of the action of FC, in activating a CN-sensitive respiratory pathway and in suppressing the SH blocker-induced respiratory burst, are proposed. |
| Title: Oxidative burst and electrolyte leakage induced by sulfhydryl blockers and by membrane permeabilizing reagents in different organs of Egeria densa. |
| Author: Amicucci-E; Albergoni-F; Manzoni-M; Zingarelli-L; Marre-M-T. |
| Source: Protoplasma-. 1998; 205 (1-4) 93-100. |
| Source Type: Journal |
| Publication Date: 1998 |
| Abstract: Sulfhydryl blockers, such as N-ethylmaleimide, iodoacetate and heavy metals induce a transitory stimulation of O2 consumption and H2O2 production (oxidative burst) and a rapid release of electrolytes in leaves of various aquatic plants. The correlation between these two responses to N-ethylmaleimide or to Ag+ in separate organs and stages of leaf development was investigated in Egeria densa. Only adult leaves were able to respond to the sulfhydryl blockers with an oxidative burst, whereas this response was absent in immature growing leaves and in stem and root segments. In N-ethylmaleimide- as well as in Ag+-treated adult leaves the oxidative burst was constantly associated with a relevant electrolyte leakage. These data are consistent with a model in which the SH reagent would first interact with a plasmalemma protein, leading to an increase in passive permeability to ions and to the activation of an oxidative enzyme of the type of the superoxide synthase described for granulocytes. In its turn, active-oxygen species produced by the activated oxidase might further damage the plasma membrane, increasing its passive permeability. Digitonin and nystatin, two reagents known to cause a permeabilization of lipid membranes, induced in adult E. densa leaves a transient increase in the rate of O2 consumption and H2O2 production and an electrolyte leakage very similar to those induced by sulfhydryl blockers. These effects, however, were not influenced by the flavin analogues diphenylene iodonium and quinacrine, and were partially inhibited by the presence of CN- and salicylhydroxamic acid, thus suggesting the involvement of a different oxidase in the oxidative burst elicited by these reagents. |
| Title: Ammonium and methylammonium transport in Egeria densa leaves in conditions of different H+ pump activity. |
| Author: Venegoni-A {a}; Moroni-A; Gazzarrini-S; Marre-Maria-Teresa. |
| Source: Botanica-Acta. Oct., 1997; 110 (5) 369-377. |
| Source Type: Journal |
| Publication Date: 1997 |
| Abstract: Previous data in Egeria densa leaves demonstrated a strong inhibitory effect of Cs+ on passive K+ influx and on K+-induced. ATP-dependent electrogenic proton extrusion. In this paper we analyzed, using the same material, the effects of Cs+ on ammonium (NH4+) and methylammonium (CH3NH3+) transport in order to elucidate whether a common transport system for K+ and NH4+ could be demonstrated. The effects of Cs+ on NH4+-and CH3NH3+-induced titratable H+ extrusion (-DELTAH+) and on transmembrane electrical potential difference (Em) in E. densa leaves were analyzed in parallel. All experiments were run either in the absence or presence of fusicoccin, corresponding to low or high H+-ATPase activity and membrane hyperpolarization and leading, in this material, to respectively active or passive transport of K+. The results suggest the presence in E. densa leaves of two distinct pathways for NH4+ uptake: one in common with NH4+ and (with lower affinity) CH3NH3+, insensitive to Cs+, and a second system, operating at higher H+-ATPase activity and Em hyperpolarization, strongly inhibited by Cs+ and impermeable to CH3NH3+. In agreement with this hypothesis, Xenopus laevis oocytes injected with the KAT1 RNA of Arabidopsis thaliana were permeable to K+ and NH4+, but not to CH3NH3+. |
| Title: Genetic uniformity of two aquatic plants, Egeria densa PLANCH. and Elodea nuttallii (PLANCH.) St. John, introduced in Japan. |
| Author: Kadono,-Y.; Nakamura,-T.; Suzuki,-T. |
| Source: JAP.-J.-LIMNOL. 1997 vol. 58, no. 2, pp. 197-203. |
| Source Type: Journal |
| Publication Date: 1997 |
| Abstract: Genetic variation in two plants introduced into Japan, Egeria densa and Elodea nuttallii, was investigated by enzyme electrophoresis. As a result, no polymorphism in allozyme patterns was found among 44 and 26 populations, respectively, of Egeria densa and Elodea nuttalii naturalized in Japan. This result suggests that the populations of the two species are rametes of the same clone which have spread by vegetative means from a single source, though the possibility of multiple introduction is not excluded. The ecological implication of genetic uniformity was briefly discussed in relation to the cause of decline in the population after the peak of abundance. |
| Title: Transient stimulation of oxygen uptake induced by sulfhydryl reagents in Egeria densa and Potamogeton crispus leaves. |
| Author: Bellando-M; Sacco-S; Albergoni-F; Rocco-P; Marre-Maria-Teresa. |
| Source: Botanica-Acta. Oct., 1997; 110 (5) 388-394. |
| Source Type: Journal |
| Publication Date: 1997 |
| Abstract: A vigorous and transient increase of O2 uptake associated with a simultaneous release of CO2 was elicited in Egeria densa and in Potamogeton crispus leaves by treatment with N-ethylmaleimide (NEM) and by other -SH group reagents (iodoacetate, p-(chloromercuri)benzenesulfonate (p-CMBS), Ag+, Hg2+, Cu2+). The NEM-induced respiratory burst was apparent even in the absence of photosynthesis (darkness, or presence of DCMU) as well as in the presence of the respiration inhibitors cyanide and propyl gallate or SHAM, separate or in combination. In contrast, a complete suppression of the respiratory burst was induced by diphenylene iodonium and by quinacrine, inhibitors of the plasma membrane NADPH oxidase activated in the pathogen-elicited oxidative burst in granulocytes and in plants. The respiratory burst induced by NEM and by the uncoupler CCCP were additive. The intensity of the respiratory burst was markedly decreased by increasing the pH of the medium from 5 to 8, and partially decreased by the presence of K+ in the medium. Azide inhibited the burst (as well as basal respiration) at pH 6.5 but not at pH 5. The stimulation of QO2 by SH reagents was associated with an early, pronounced membrane depolarization together with a rapid increase of the release into the medium of K+ and other electrolytes, and with a rapid decrease of the intracellular ATP, ADP and G6P contents. The possible relationships between this SH reagent-induced respiratory burst and the associated effects on Em and electrolyte leakage are discussed. |
| Title: Lack of correlation between transplasmalemma electron transport rate and depolarisation in Egeria densa leaf cells. |
| Author: Kuschel-Lioba; Dahse-Ingo {a}; Mueller-Eberhard. |
| Source: Journal-of-Plant-Physiology. 1996; 147 (6) 675-684. |
| Source Type: Journal |
| Publication Date: 1996 |
| Abstract: Transplasmalemma electron transport induced by the impermeable electron acceptors, Na-3(Fe(CN)-6), K-3(Fe(CN)-6), K-2(IrCl-6) and K-2(IrBr-6), was investigated by means of microelectrode technique, pH-stat and colorimetric experiments using the waterweed, Egeria densa. No fix stoichiometry between protons and electrons exported was observed during acceptor reduction. The H+/e- ratio changed during the experiments with time and depended on a number of factors such as light conditions, preincubation and incubation medium. Application of ion channel blockers (BaCl-2, tetraethylammonium, charybdotoxin), inhibitors (erythrosin B, NaCN + salicylhydroxamic acid) and stimulators of proton transport (ethanol, fusicoccin) showed that ions including protons are transported in order to compensate for the electron acceptor-induced charge imbalance. Electrically, acceptor reduction was accompanied by depolarization of the plasmalemma at acid and neutral pH. Both, reduction and depolarization displayed saturation kinetics under these conditions. Surprisingly, the depolarization disappeared at alkaline pH, whereas the acceptor reduction continued. A different mechanism of charge compensation is proposed. The natural electron acceptor, nitrate, did not competitively inhibit ferricyanide reduction, by contrast, it enhanced the reduction rate. Furthermore, in the presence of nitrate no nitrite was produced in the medium. Nitrate did not depolarize the plasmalemma notwithstanding the required charge compensation. Nitrate uptake is accompanied by alkalinization of the medium and acidification of the cytosol. Hence, nitrate is not a substrate of the plasmalemma redox system and it is taken up by an apparent 1:1H+/NO-3- cotransport. The results demonstrate that the plasmalemma redox system of Egeria leaf cells is neither a proton pump nor a nitrate carrier or reductase. |
| Title: Factors influencing biomass and nutrient content of the submersed macrophyte Egeria densa Planch. in a pampasic stream. |
| Author: Feijoo,-C.S.; Momo,-F.R.; Bonetto,-C.A.; Tur,-N.M. |
| Source: HYDROBIOLOGIA 1996 vol. 341, no. 1, pp. 21-26. |
| Source Type: Journal |
| Publication Date: 1996 |
| Abstract: We identified factors influencing biomass and nutrient content in Egeria densa in an enriched pampean stream of Argentina. Physical (current velocity, temperature), chemical (pH, conductivity, dissolved oxygen, nutrient content in water and sediments), and biological variables (biomass and nutrient content of E. densa, biomass of periphyton and other macrophytes) were estimated at each sampling occasion, and mean monthly values estimated. Biomass and nutrient content in E. densa were correlated with these physical-chemical and biological variables. Biomass was positively correlated with ammonium in stream water (P<0.05) and sediment total nitrogen (P<0.01). Nitrogen showed a positive relationship with ammonium (P<0.01), and a negative one with nitrate and periphyton biomass (P<0.05). Phosphorus was positively correlated with soluble reactive phosphorus (P<0.01). The growth of other macrophyte species in the stream seemed to influence E. densa biomass, probably through competition for light. Current velocity was low and not significantly related with E. densa biomass; however, a flood at the beginning of the study washed the macrophyte stand downstream. |
| Title: Modeling plasmalemma ion transport of the aquatic plant Egeria densa. |
| Author: Buschmann-P {a}; Sack-H; Koehler-A-E; Dahse-I. |
| Source: Journal-of-Membrane-Biology. 1996; 154 (2) 109-118. |
| Source Type: Journal |
| Publication Date: 1996 |
| Abstract: Fresh-water plants generate extraordinarily high electric potential differences at the plasma membrane. For a deeper understanding of the underlying transport processes a mathematical model of the electrogenic plasmalemma ion transport was developed based on experimental data mainly obtained from Egeria densa. The model uses a general nonlinear network approach and assumes coupling of the transporters via membrane potential. A proton pump, an outward-rectifying K+ channel, an inward-rectifying K+ channel, a Cl- channel and a (2H-Cl)+ symporter are considered to be elements of the system. The model takes into consideration the effects of light, external pH and ionic content of the bath medium on ion transport. As a result it does not only satisfactorily describe the membrane potential as a function of these external physiological factors but also succeeds in simulating the effects of specific inhibitors as well as I-V-curves obtained with the patch-clamp technique in the whole cell mode. The quality of the model was checked by stability and sensitivity analyses. |
| Title: Mechanical properties of the lacunar gas in Egeria densa Planch. shoots. |
| Author: Sorrell-B-K {a}; Dromgoole-F-I. |
| Source: Aquatic-Botany. 1996; 53 (1-2) 47-60. |
| Source Type: Journal |
| Publication Date: 1996 |
| Abstract: The effects of varying internal and external pressures on the lacunar gas system were examined for the submerged macrophyte Egeria densa Planch. Application of 30 kPa to cut shoots caused gas flow in accordance with the Poiseuille equation, once the meniscus formed by surface tension and hydrostatic pressure was broken. Surface tension averaged 1.85 kPa for the internodal canals and 41.10 kPa for the pores of the nodal diaphragms. According to calculations based on hydrostatic pressure effects, broken shoots will not release gas in water deeper than 2.4 m in the light, and water could infiltrate internodal canals at 2.9 m and nodal pores at 6.8 m. In the dark, when internal suction assists infiltration, the meniscus would break and the internodal canals flood at the surface, and at 4.4 m depth for the diaphragm pores. Yet the nodal diaphragms were remarkably resistant to flooding. Water applied at 50 kPa failed to penetrate them, owing to their high resistance to water flow (130 000 MPa s-1 m-3, cf. 540 MPa s-1 m-3 for the internodal canals) and hydrophobic lining at the pores. Infiltration through broken surfaces is therefore unlikely to cause extensive natural infiltration in Egeria; this probably results from condensation from the surrounding cells. External pressures slightly compressed the lacunae; the lacunar system lost 2.3% of its initial volume at 50 kPa applied pressure. The elastic modulus of the shoots was only 1845 kPa, suggesting that the lacunae are well protected from external pressures by the turgor pressure and wall resistance of the surrounding tissues. The lacunar system did not expand when it was internally pressurized, so lacunar pressurization does not add buoyancy or mechanical strength in this species. |
| Title: Egeria densa planchon (Hydrocharitaceae), naturalized in Spain and Ludwigia natans Elliot (Onagraceae), a xenophyte new to Europe flora. |
| Author: Cirujano-Santos {a}; Medina-Leopoldo {a}; Stubing-Gerardo; Peris-Juan-Bautista. |
| Source: Anales-del-Jardin-Botanico-de-Madrid. 1995; 53 (1) 140-141. |
| Source Type: Journal |
| Publication Date: 1995 |
| Abstract: NA |
| Title: Light-induced changes in cytosolic pH in leaf cells of Egeria densa: Measurements with pH-sensitive microelectrodes. |
| Author: Okazaki-Yoshiji {a}; Tazawa-Masashi; Iwasaki-Naohiko. |
| Source: Plant-and-Cell-Physiology. 1994; 35 (6) 943-950. |
| Source Type: Journal |
| Publication Date: 1994 |
| Abstract: Light-induced changes of cytosolic pH (pH-c) and the plasmalemma Potential (E-m) in dark-adapted leaf cells of the aquatic plant, Egeria densa were measured simultaneously with double-barreled pH-sensitive microelectrodes. Upon illumination, pH-c increased transiently and then decreased to a level that was lower than the original value, while the plasmalemma was greatly hyperpolarized after an initial small depolarization. DCMU inhibited the light-induced changes in both pH-c and E-m. DCMU acted without directly inhibiting the electrogenic proton pump in the plasmalemma since a decrease in pH-c caused by treatment with butyrate (H+-loading) hyperpolarized the plasmalemma in DCMU-pretreated cells. N,N'-Dicyclohexylcarbodiimide (DCCD) also inhibited the light-induced changes in both pH-c and E-m. This result may be explained by direct inhibition of the proton pump in the plasmalemma by DCCD since the decrease in pH-c caused by butyrate did not induce membrane hyperpolarization in DCCD-treated leaf cells. Fusicoccin induced membrane hyperpolarization and slight acidification of the cytosol. DCCD inhibited the fusicoccin-induced changes in both pH-c and E-m. The mechanism of the light-induced changes in pH-c is discussed in relation to activities of the proton pump in the plasmalemma and photosynthesis. |
| Title: Relationship between fusaric acid uptake and its binding to cell structures by leaves of Egeria densa and its toxic effects on membrane permeability and respiration. |
| Author: Marre,-M.T.; Vergani,-P.; Albergoni,-F.G. |
| Source: PHYSIOL.-MOL.-PLANT-PATHOL. 1993 vol. 42, no. 2, pp. 141-157. |
| Source Type: Journal |
| Publication Date: 1993 |
| Abstract: NA |
| Title: Effects of suspended solids on the establishment and growth of Egeria densa. |
| Author: Tanner-Chris-C {a}; Clayton-John-S; Wells-Rohan-D-S. |
| Source: Aquatic-Botany. 1993; 45 (4) 299-310. |
| Source Type: Journal |
| Publication Date: 1993 |
| Abstract: To identify levels of suspended solids (SS) in Lake Waahi (Huntly, New Zealand) favorable for the reestablishment of Egeria densa Planchon, shoots were grown in 2 m deep tanks filled with water transported from the lake and maintained at selected SS loadings between 5 and 40 gm-3 (predominantly comprised kaolinitic clays). Plant growth was measured over periods of 44-47 days in spring, summer and autumn. Highest relative growth rates (RGR) were recorded in summer (maximum 40 mg g-1 day -1). Egeria propagules growing from a depth of 1.85 m showed positive growth responses at SS levels up to approximately 25 g m-3 (K-d apprxeq 1.75) in spring and autumn, and approximately 35 g m-3 (K-d apprxeq 1.95) in summer. At SS levels up to 15 g m-3 (K-d=1.5 m-1), growth was little affected during summer, while during spring and autumn biomass accumulation was reduced to about 60% and RGR values to about 70% of the maximum seasonal values recorded. Egeria shoots showed maximum elongation at about 10-20gm-3 SS (K-d=1.3-1.65). Plant architecture became less branched with increasing SS and the number of roots produced decreased. Implications for the establishment of Egeria in turbid waters are discussed. |
| Title: Effects of suspended solids on the establishment and growth of Egeria densa . |
| Author: Tanner,-C.C.; Clayton,-J.S.; Wells,-R.D.S. |
| Source: AQUAT.-BOT. 1993. vol. 45, no. 4, pp. 299-310. |
| Source Type: Journal |
| Publication Date: 1993 |
| Abstract: To identify levels of suspended solids (SS) in Lake Waahi (Huntly, New Zealand) favourable for the re-establishment of Egeria densa Planchon, shoots were grown in 2 m deep tanks filled with water transported from the lake and maintained at selected SS loadings between 5 and 40 g m super(-3) (predominantly comprised kaolinitic clays). Plant growth was measured over periods of 44-47 days in spring, summer and autumn. Highest relative growth rates (RGR) were recorded in summer (maximum 40 mg/g/day). Egeria propagules growing from a depth of 1.85 m showed positive growth responses at SS levels up to approximately 25 g m super(-3) (K sub(d) approximately equals 1.75) in spring and autumn, and approximately 35 g m super(-3) (K sub(d) approximately equals 1.95) in summer. At SS levels up to 15 g m super(-3) (K sub(d) = 1.5/m), growth was little affected during summer, while during spring and autumn biomass accumulation was reduced to about 60% and RGR values to about 70% of the maximum seasonal values recorded. Egeria) shoots showed maximum elongation at about 10-20 g m super(-3) (K sub(d) = 1.3-1.65). Plant architecture became less branched with increasing SS and the number of roots produced decreased. Implications for the establishment of Egeria) in turbid waters are discussed. |
| Title: Photosynthetic strategies in leaves and stems of Egeria densa . |
| Author: Rascio,-N.; Mariani,-P.; Tommasini,-E.; Bodner,-M.; Larcher,-W. |
| Source: PLANTA. 1991. vol. 185, no. 3, pp. 297-303. |
| Source Type: Journal |
| Publication Date: 1991 |
| Abstract: Photosynthetic mechanisms have been compared in leaves and, separately, in stems of Egeria densa Planch. In order to correlate the structural and functional characteristics of the two organs the ultrastructural features of leaves and stems have been studied and their photosynthetic activity has been evaluated by measuring in vivo both oxygen evolution and the kinetics of chlorophyll fluorescence. The results confirm the aquatic behaviour of the leaf which is able to utilize inorganic C supplied both as CO sub(2) and HCO sub(3)@)u-. |
| Title: Submerged vegetation and spread of Egeria densa Planchon in Lake Rotorua, central North Island, New Zealand. |
| Author: Wells,-R.D.S.; Clayton,-J.S. |
| Source: N.Z.-J.-MAR.-FRESHWAT.-RES. 1991. vol. 25, no. 1, pp. 63-70. |
| Source Type: Journal |
| Publication Date: 1991 |
| Abstract: Scuba records on the distribution and abundance of macrophytes in Lake Rotorua show marked changes between 1980 and 1988. Extensive weed beds of Lagarosiphon major , present since the mid-1950s, disappeared from the lake by 1982. The loss of the L. major weed beds coincided with marked reductions in water clarity in the early 1980s and with a storm in April 1982. Egeria densa spread rapidly from a small infestation in July 1983 to become the most abundant macrophyte in the lake by December 1988, equivalent to the historic L. major weed beds. The authors predict that E. densa well be dispersed to become a major problem weed in other Rotorua lakes in the future. |
| Title: Cytoplasmic alkalization and cytoplasmic streaming induced by light and histidine in leaf cells of Egeria densa : In vivo super(31)P-NMR study. |
| Author: Tominaga,-Y.; Kuchitsu,-K.; Katsuhara,-M.; Tazawa,-M.; Miyachi,-S. |
| Source: PLANT-CELL-PHYSIOL. 1991. vol. 32, no. 2, pp. 261-268. |
| Source Type: Journal |
| Publication Date: 1991 |
| Abstract: Rotational streaming of the cytoplasm including chloroplasts was induced by L-histidine, as well as by light, on the anticlinal face of leaf cells of Egeria densa . In the case of treatment with L-histidine some of the chloroplasts remained stationary on the periclinal face of cells after rotational cytoplasmic streaming was initiated. However, these chloroplasts were easily dislodged and translocated to the centrifugal end of the histidine-treated cells by application of a centrifugal force that barely affected the location of chloroplasts in cells incubated in the dark without L-histidine. This result indicates that the anchoring of chloroplasts was weakened by L-histidine. Thus only the release of chloroplasts from anchoring was not enough for initiation of their streaming. |
| Title: Transient pressure gradients in the lacunar system of the submerged macrophyte Egeria densa Planch. Int. Meet. on Aquatic Macrophytes, Aarhus (Denmark), 29 Aug-2 Sep 1988. |
| Author: Sorrell,-B.K. |
| Source: AQUAT.-BOT. 1991. vol. 39, no. 1-2, pp. 99-108. |
| Source Type: Journal |
| Publication Date: 1991 |
| Abstract: Pressure gradients in the lacunar system of Egeria densa were measured by attaching constant-volume manometers to cut surfaces of the shoot system. Upon illumination, the total pressure of the lacunar gas increased up to 30 kPa above the initial pressure, due to the increase in the internal oxygen pressure in the lacunae. The rate of pressurisation was not constant throughout the lacunar system because the more active regions of the shoots pressurised more rapidly than older shoot portions with lower chlorophyll contents. It can be proven mathematically that the resulting pressure gradients ( similar to 2 kPa) within shoots during the pressurisation phase could not generate a flow-through ventilation of the type found in some emergent macrophytes, but that a small gas displacement down the stem would occur. The total pressure reached its maximum within 1 h of illumination; at this time, the pressure had equilibrated throughout the shoot lacunae and mass flow was completed. Such pressure gradients are, therefore, of little importance to steady-state aeration, but may relate to the need to rapidly establish a constant partial pressure gradient within a plant with long non-photosynthetic stems. |
| Title: Induction of cytoplasmic streaming and movement of chloroplast induced by L-histidine and its derivatives in leaves of Egeria densa. |
| Author: Tazawa,-M.; Kurosawa,-S.; Amino,-Shin-Ichi; Tominaga,-Y.; Sakano,-K.; Matsumoto,-T. |
| Source: PLANT-CELL-PHYSIOL. 1991. vol. 32, no. 2, pp. 253-260. |
| Source Type: Journal |
| Publication Date: 1991 |
| Abstract: Rotational cytoplasmic streaming in leaves of Egeria densa was induced by light as well as by L-histidine (L-His). During both treatment with light and with L-His, chloroplasts on the periclinal face were dislodged and moved to the anticlinal face where rotational cytoplasmic streaming occurred. The effective concentration of L-His was about 0.01 mM and the effect was almost saturated at 0.1 mM. A derivative of L-His, 3-methyl-L-histidine, was slightly less effective than L-His. By contrast, 1-methyl-L-histidine was almost ineffective for induction of streaming, not only in Egeria but also in Vallisneria . Our results are in marked contrast to Fitting's result (1936) that 1-M-L-His is more effective than L-His. In Egeria , 1-methyl-L-His counteracted the stimulative effect of L-His. |
| Title: Submerged-vegetation changes in Lake Rotoroa (Hamilton, New Zealand) related to herbicide treatment and invasion by Egeria densa . |
| Author: Tanner,-C.C.; Clayton,-J.S.; Coffey,-B.T. |
| Source: N.Z.-J.-MAR.-FRESHWAT.-RES. 1990. vol. 24, no. 1, pp. 45-57. |
| Source Type: Journal |
| Publication Date: 1990 |
| Abstract: Lake Rotoroa is a small (54 ha), shallow (maximum depth 6 m), urban lake which has been subject to repeated chemical weed control since 1957. The distribution and abundance of aquatic macrophytes in the lake were studied in six SCUBA surveys between 1977 and 1986. During this period three applications of diquat herbicide resulted in periodic decreases in submerged vascular plant growths in the lake. Macrophytes were present over c. 80% of the lake bed to a maximum depth of 5-5.5 m during the period of study. Emergent macrophytes, were recorded around c. 50% of the lakeshore. In 1977 the most abundant submerged vascular plants were Lagarosiphon major and Elodea canadensis which were both recorded at all sampling sites. Egeria densa , which was first recorded in the lake in 1977, spread at the expense of these species to become the dominant vascular plant in the lake by 1986. |
| Title: Compartmentation of fluorescent tracers injected into the epidermal cells of Egeria densa leaves. |
| Author: Goodwin,-P.B.; Shepherd,-V.; Erwee,-M.G. |
| Source: PLANTA. 1990. vol. 181, no. 1, pp. 129-136. |
| Source Type: Journal |
| Publication Date: 1990 |
| Abstract: We have compared the movement of a series of fluorescent tracers of increasing molecular weight injected into the cytoplasm in the epidermal cells of leaves of Egeria densa Planch. In general, the tracers showed major movement into three cellular compartments: first, to the cytoplasm of adjacent cells; secondly, from the cytoplasm, to the vacuole (irreversible); and thirdly, from the cytoplasm to the nucleus (reversible). Thus, the differences in cell-to-cell movement of these tracers are based upon their differing ability to cross the intercellular walls, not upon differences in their intracellular compartmentation. |
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