Nitellopsis Research Articles

Electrical signalling in Nitellopsis obtusa: potential biomarkers of biologically active compounds.

The Nitellopsis obtusa (N.A.Desvaux) J.Groves cell provides a model system for complex investigation of instantaneous effects of various biologically active compounds (BC) on the generation of plant bioelectrical signals in vivo. Experimental evidence using multiple electrical signals as biomarkers of the effects of BC (acetylcholine, asparagine, glutamate, nicotine, aluminium, nickel and cadmium ions) is provided. The effect of BC on membrane transport systems involved in the cell excitability were tested by current clamp, voltage clamp and patch clamp methods. Membrane potential (MP) alterations and action potential (AP) patterns in response to BC were shown to represent the cell state. High discretisation frequency allows precise, high time resolution analysis of real-time processes measuring changes in excitation threshold, AP amplitude and velocity of repolarisation values after application of BC indicating the effect on ion channels involved in AP generation. Application of voltage clamp revealed that changes in AP peak value were caused not only by increment in averaged maximum amplitude of the Cl- current, but in prolonged Cl- channels' opening time also. The cytoplasmic droplet can serve as a model system in which the effects of BC on single tonoplast ion channel can be studied by patch clamping. Investigation of electrical cell-to-cell communication revealed evidence on the electrical signal transduction through plasmodesmata.

Impacts of the cryptic macroalgal invader, Nitellopsis obtusa, on macrophyte communities

AbstractEarly detection of aquatic invasive species, such as Nitellopsis obtusa, is often critical to reduce their long-term negative effects. This macroalga resembles native taxa and can invade deep locations in littoral zones of lakes in North America. Studies in which effects of Nitellopsis on macrophyte communities were quantified are rare. We surveyed 4 lakes in central New York where Nitellopsis is present to document whether macrophyte communities are negatively affected by this invasive macroalgae and to test whether Nitellopsis was found more frequently in deeper- than in shallow-water habitats. We found lower macrophyte species richness when Nitellopsis was abundant. This pattern was consistent at 3 water depths (shallow [>1 m], intermediate [1–2 m], and deep [>2 m]). Macrophyte biomasses (total, including native and other nonnative species, and only native species) were significantly lower in quadrats with greater abundance of Nitellopsis. Nitellopsis biomass exceeded the combined biomass of ma...

Overwintering and gyrogonite formation by the rare and endangered indicative macroalga Lychnothamnus barbatus (Meyen) Leonh. in eutrophic conditions

Lychnothamnus barbatus (Meyen) Leonhardi is a rare, endangered charophyte species considered to be a reliable indicator of low water fertility, with its fossilized gyrogonites (calcified oospores) being applied as a biomarker of past oligotrophic conditions. This paper presents a case study from a lake in which L. barbatus occurs abundantly under eutrophic conditions (Lake Kuźnickie, central-western Poland). The species overwinters in this lake in the form of extensive meadows along a wide depth gradient and, in addition, produces fully developed gyrogonites.The occurrence of L. barbatus in Lake Kuźnickie was investigated at 1m depth intervals at nine permanent transects in November 2015 and in April 2016. Spring thalli were observed microscopically to determine whether L. barbatus overwintered (with new outgrowths on old thalli) or grew anew in spring (from oospores). The species occurred at almost 50% of the surveyed sites in both sampling periods. At most sites L. barbatus formed compact carpets in which it was the only species or co-occurred with the charophyte Nitellopsis obtusa or the angiosperm Ceratophyllum demersum. L. barbatus occurred along a wide depth gradient: 1.5–6.5m deep in autumn and 2–6.5m after the winter period. The species coverages in April 2016 were comparable to those observed in November 2015 (Mann-Whitney U-test, P>0.05). The thalli collected in April were well preserved after the winter, with numerous spring outgrowths. In addition, fully developed gyrogonites were found in April 2016. This study indicates wider fertility tolerance of L. barbatus and its ability to overwinter under eutrophic conditions.

Nitellopsis obtusa (Desv.) J. Groves, 1919 (Charophyta: Characeae): new records from southern Michigan, USA with notes on environmental parameters known to influence its distribution

Nitellopsis obtusa (Desv.) J. Groves, 1919 (Charophyta: Characeae): new records from southern Michigan, USA with notes on environmental parameters known to influence its distribution

Accumulation of copper in the cell compartments of charophyte Nitellopsis obtusa after its exposure to copper oxide nanoparticle suspension.

Cu accumulation in the internodal cell of charophyte Nitellopsis obtusa or its compartments was investigated after 3-h-exposure to lethal effective concentrations (8-day LC50) of CuO nanoparticle (nCuO) suspension or CuSO4 solution, i.e. 100mg/L nCuO or 3.18mg Cu/L as CuSO4. In both cases, the major part of Cu accumulated in the cell walls. The presence of CuO NPs in the cell wall and within the cell was visualized by scanning electron microscope images as well as confirmed by energy dispersive X-ray spectrum data. Although a threefold higher intracellular concentration of Cu was found after treatment with nCuO suspension, 3.18mg Cu/L as CuSO4 induced fast and substantial depolarization of cell membrane potential contrary to that of 100mg/L nCuO. A delayed effect of nCuO on the survival of the cells was also observed. This suggests that internally accumulated Cu was far less active and further supports the hypothesis of delayed toxicity of internalized nCuO NPs to charophyte cells.

Realized niche shift associated with the Eurasian charophyte Nitellopsis obtusa becoming invasive in North America.

Nitellopsis obtusa (starry stonewort) is a dioecious green alga native to Europe and Asia that has emerged as an aquatic invasive species in North America. Nitellopsis obtusa is rare across large portions of its native range, but has spread rapidly in northern-tier lakes in the United States, where it can interfere with recreation and may displace native species. Little is known about the invasion ecology of N. obtusa, making it difficult to forecast future expansion. Using ecological niche modeling we investigated environmental variables associated with invasion risk. We used species records, climate data, and remotely sensed environmental variables to characterize the species’ multidimensional distribution. We found that N. obtusa is exploiting novel ecological niche space in its introduced range, which may help explain its invasiveness. While the fundamental niche of N. obtusa may be stable, there appears to have been a shift in its realized niche associated with invasion in North America. Large portions of the United States are predicted to constitute highly suitable habitat for N. obtusa. Our results can inform early detection and rapid response efforts targeting N. obtusa and provide testable estimates of the physiological tolerances of this species as a baseline for future empirical research.

The effects of Ni(2+) on electrical signaling of Nitellopsis obtusa cells.

The effect of nickel (Ni) on the generation of plant bioelectrical signals was evaluated in Nitellopsis obtusa, a Characean model organism. Conventional glass-microelectrode technique and K(+)-anaesthesia method in current-clamp and voltage-clamp modes were used for the measurement and analysis of electrical parameters. Ni(2+) treatment rapidly influenced the action potential (AP) parameters namely, excitation threshold, AP peak and duration, membrane potential at various voltages and dynamics of ion currents. We conclude that altered electrical signaling pathway in the test organism constituted the early target for Ni toxicity imposition. The observed Ni interference could be ascribed to disturbed [Ca(2+)]cyt content, impaired Cl(-) and K(+) channels activity resulting in decreased excitability and repolarization rate in generated AP.

Environmental factors associated with the distribution of non-native starry stonewort (Nitellopsis obtusa) in a Lake Ontario coastal wetland

Abstract Starry stonewort ( Nitellopsis obtusa ) was likely introduced to the Laurentian Great Lakes via ballast water in the late 1970s. Since its introduction, little research has been conducted to determine the extent of its spread throughout the Great Lakes basin or to explore the environmental variables associated with its distribution. This is partly because, outside of its native range, N. obtusa is not often differentiated from other native Characeae. Here, we document the spatial distribution of N. obtusa in Presqu'ile Bay, Lake Ontario and identify physical and chemical environmental factors that predict the presence of N. obtusa . In Presqu'ile Bay, N. obtusa was primarily clustered along the north-shore and tended to be at locations with higher conductivity, water hardness, and nitrate–nitrite and lower exposure to wind and wave action. The best predictors of N. obtusa presence, based on a boosted regression tree model, included high density of docks within a 1 km radius, high conductivity, short distance to the nearest marina, and low fetch. These results support the notion that N. obtusa can be transported via boating activity, and the findings can be used by management agencies to focus search efforts when attempting to determine N. obtusa presence. Given the paucity of knowledge regarding both the distribution of N. obtusa in the Great Lakes and how its introduction has influenced native flora and fauna, it is hoped that this study will spur future research.

Latent Cell Mortality After Short-Term Exposure Of Nitellopsis Obtusa Cells To Copper Oxide Nanoparticles

Abstract The effects of 5 s–24 h exposure to CuO nanosuspension (nCuO) and CuSO4 on mortality of Nitellopsis obtusa cells within 48 days were investigated. Based on LED50 kinetics, a toxicological endpoint of lethal exposure duration that induces 50% cell mortality, it was shown that mortality response of 10-min treated cells (by 3.2 and 24–79.9 mg Cu/l, respectively CuSO4 and nCuO) did not differ after 12th day rewash in control medium. Larger amount of total Cu (in mg/g cell DM) was measured in charophyte cells exposed to nCuO (79.9 mg Cu/l) than to ionic Cu (3.2 mg Cu/l). The lower nCuO-induced mortality than that of Cu2+ during earlier rewash period could be related to the sorption of nanoparticles on the cell wall, which was confirmed by scanning electron microscope images and energy dispersive X-ray spectrum data. Effect threshold, the shortest exposure duration that induces cell mortality significantly different from the control during a post-exposure period, comprised 30 s in 24 mg Cu/l of nCuO, however, it could not be identified and was less than 5 s in 79.9 mg Cu/l of nCuO.

UNVEILING ALGAL BIODIVERSITY OF EL-FARAFRA OASIS (WESTERN DESERT, EGYPT) AND POTENTIAL RELEVANCE OF ITS USE IN WATER BIO-ASSESSMENT: SPECIAL INTEREST ON SPRINGS AND DRILLED WELLS

For the first time, comprehensive phycological screening on El-Farafra Oasis (Western Desert, Egypt) had been implemented for unveiling and characterization of its cryptic algal diversification, with special interest on springs and drilled wells. Overall during summer 2011 and winter 2012, 82 different algal taxa have been found in all studied habitats as naturally-grown and culture-induced propagations. Of these, different 14 algal strains have been recorded only using water-culturing techniques on different four algal media (Kolkwitz's solution, Chu #10, BBM and modified BG-11 media). Culturing techniques not only permitted to discover the cryptic algal taxa present in the viable spores state, but also allowed to follow and confirm the complete life cycle of the rare stigonematalean true T-branched cyanoprokaryote Westiellopsis prolifica. This inventory enriched the freshwater Egyptian algal flora with 6 new algal taxa for the first time namely Symploca dubia, Westiellopsis prolifica, Euastrum insulare, Penium margaritaceum, Zygnemopsis sp. and Nitellopsis obtusa. In this study, some recorded taxa are considered to be crenophilous, e.g. Geitlerinema jasorvense and Phormidium carboniciphilum, to be crenoxenic e.g. Jaaginema subtilissimum, Phormidium corium, Westiellopsis prolifica and Zygnemopsis sp. Only, Oscillatoria tenuis had the highest-grade constancy of occurrence throughout the whole investigation period. This species shows a strong α-mesosaprobic indication for water eutrophication in this oasis. In general, El-Farafra Oasis wells and springs are considered isolated and azonal habitats still bearing partially near-natural conditions with some agricultural, pastures and humans impacts, and have freshwater type with slight seasonal variations in their mineralization contents as a kind of ecotones-characteristic features. Finally, these hyper-arid-desert-dwelling water systems are just about excellent potable water resources in the context of water quality guidelines of Egyptian Higher Committee for Water (EHCW) and World Health Organization (WHO), but they substantially still need special governmental efforts in the future to mainly eliminate the relatively high contents of Fe, Mn and Zn.

Distribution of Nitellopsis obtusa (Characeae) in New York, U.S.A.

The charophytic green alga Nitellopsis obtusa was first reported in the New World in the St. Lawrence River in 1978. Since that time, N. obtusa has been reported from inland lakes throughout Michigan, northern Indiana, and western New York and has been listed as an aggressive invasive species by the United States Geological Survey. This study addresses the distribution of N. obtusa by surveying 390 waterbodies throughout New York. Previous reports are confirmed and new localities are presented, including new reports from five counties (Franklin, Ontario, Seneca, Wayne, and Yates). In total, N. obtusa was found in 17 counties at 31 sites, including 16 inland lakes, seven sites in the St. Lawrence River, and eight sites in Lake Ontario.

Early Pleistocene (Calabrian) Ostracoda assemblage and paleoenvironmental characteristics of the Fevzipasa Formation,Western Anatolia

The study area is located about 40km west ofAydin city in western Turkey and includesNeogene to Quaternary sediments of the Fevzipasa Formation, which unconformably overlies the Miocene rock units. The Fevzipasa Formation is composed of conglomerates, sandstones, mudstones, marls, limestones and tuff layers and is unconformably overlain by recent deposits of the Söke-Milet Basin. The lower part of the Fevzipasa Formation is represented by coarse clastics and lacustrine carbonates followed by fine to coarse-grained sandstones bearing mollusc shells. Prominent tuff layers (lower and upper tuff layers) of this dominantly sandstone succession were radiometrically dated between roughly 2 and 1Ma. Based on small mammal fauna the age of the upper part of the formation is Early to Late Pleistocene. To investigate the paleoenvironmental evolution of the succession, forty-two samples were collected along two stratigraphic sections. Ostracoda assemblages together with Chara flora, Gastropoda and Pelecypoda and fish remains were recovered from only twenty-nine samples. Ostracoda assemblages include Candona neglecta, Cyclocypris ovum, Ilyocypris gibba, I. bradyi, Heterocypris salina and Scottia cf. S. pseudobrowniana. Additionally, fish remains belonging to the Cyprinidae family (Tinca sp., Leuciscus sp. and Leuciscus etilius) and Characeae gyrogonites referable to Nitellopsis obtusa, Chara sp., C. aspera, C. globularis, C. hispida, C. vulgaris, Lychnothamnus sp. and Sphaerochara sp. occurred in the samples. The ostracod, fish, and gyrogonite records all indicate that the Fevzipasa Formation was deposited in a paleoenvironmental setting characterized by permanent and shallow water bodies. According to the identified Ostracoda assemblages and combining all available stratigraphic data, the age of middle part of the Fevzipasa Formation is suggested as Early Pleistocene (Calabrian).

Ionic relations and electrophysiology of single cells of Characeae. Part I. Investigations on electric potentials and resistance in cells of Nitellopsis obtusa

Ionic relations and electrophysiology of single cells of Characeae. Part I. Investigations on electric potentials and resistance in cells of Nitellopsis obtusa

Comparing the Effect of Phytoplankton and a Charophyte on Calcite Precipitation in Lake Water: Experimental Approach

Primary producers are able to strongly affect calcium budget in hardwater lakes. The relative contribution of phytoplankton and charophytes to water decalcification (by precipitation of calcium carbonate) is, however, unclear. In this study we checked the effect of natural phytoplankton community and a charophyte (Nitellopsis obtusa) on the decline of calcium concentration in experimental outdoor conditions. The experiment was carried out in original lake water and two variants of enrichment with inorganic nitrogen and phosphorus to test the changing efficiency in decalcification by both primary producers. At low nutrient concentrations, N. obtusa was responsible for calcium decline in original lake water by 12 mg Ca 2 dm-3 during 20 days of experiment. In these conditions the effect of phytoplankton was negligible. In lake water enriched with nutrients, the exponential growth of phytoplankton led to the decrease of calcium concentration from initial 35 mg Ca 2 dm-3 to 9 mg Ca 2 dm-3 in the same time period. The maximum effect of N. obtusa was the same as in original lake water but manifested itself earlier to decline in the end of experiment. Supersaturation of water with calcium carbonate was always more than threefold and saturation index reached 27 in mixed cultures of phytoplankton and N. obtusa in lake water enriched with nutrients. In this context we hypothesise on a possible role of charophytes as nucleation sites necessary for calcite precipitation. Based on our own and literature data we also discuss expected immobilisation of phosphate incorporated in calcite precipitated by the growth of phytoplankton and N. obtusa.

Some Morphological Observations of Charophytes (Characeae) from Bangladesh

Morphologically interesting charophytes were found from Chapai-Nawabgonj and Rajshahi districts in Bangladesh. These are: swollen branchlet of Lamprothamnium papulosum (Wallr.) J. Groves, long stalked gametangia and twin antheridia of Nitella hyalina (DC.) Agardh, bifid bract cells of Chara flaccida A. Braun and bifid end cell of Nitellopsis obtusa (Desv.) J. Groves. DOI: http://dx.doi.org/10.3329/jles.v7i0.20124 J. Life Earth Sci., Vol. 7: 71-77, 2012

Ecotoxicity effects triggered in aquatic organisms by invasive Acer negundo and native Alnus glutinosa leaf leachates obtained in the process of aerobic decomposition

The replacement of autochthonous tree species by invasive ones in coastal zones of freshwater bodies induces additional alteration of hydrochemical and microbiological characteristics due to decomposition of fallen leaves of non-indigenous species, which can lead to ecotoxic response of the littoral biota. Leaves of invasive to Lithuania boxelder maple (Acer negundo) and autochthonous black alder (Alnus glutinosa) lost more than half of biomass and released stable amount of DOC (60–70mg/L) throughout 90-day mesocosm experiment under aerobic conditions. This, along with the relatively small BOD7 values detected after some variation within the first month confirms effective biodegradation by fungi and bacteria. The ambient water was more enriched with different forms of N and P by decomposing boxelder maple than by alder leaves. During the first month, both leachates were more toxic to charophyte (Nitellopsis obtusa) at mortality and membrane depolarization levels, while later to two crustacean species. Biomarker response, H+-ATPase activity in membrane preparations from N. obtusa, was stronger for A. negundo. Generally, boxelder maple leaf leachates were more toxic to tested hydrobionts and this coincides with previous study on leaves of the same pair of tree species conducted under microaerobic conditions (Krevš et al., 2013).

Investigation of membrane potential changes in Nitellopsis obtusa cells induced by blue and red light stimulation

Light controls multiple physiological processes in plants. Membrane potential is widely used to report the early events as­sociated with changes in ion permeability, thus the effect of monochromatic light on bioelectrical parameters of Nitellopsis ob­tusa cells was examined. In this study blue, red and far-red light-induced membrane potential changes, light-induced photoelectrical reaction and membrane excitability were investigated using K’-anaesthesia method. All investigated lights cause the same bioelectrical events in Nitellopsis obtusa cells. It can be concluded that all photoreception systems exert their effects by first altering the permeability of the plasma membrane to ions and later ion channels perform signal-transducing functions in the complex array of mechanisms that determine plant physiology.

Biogeographic history of two Eurasian Cenozoic charophyte lineages

The long-term biogeographic history of charophytes is a highly relevant, although little-studied topic to understand the distribution of extant species. Two contrasting biogeographic histories of Eurasian charophyte lineages are documented and the reasons for such wide distributions are explored. Nitellopsis (Tectochara) merianii–Nitellopsis obtusa is a charophyte lineage ranging from the latest Eocene to the present and displaying Eurasian distribution since the Late Oligocene. Lychnothamnus stockmansii–Lychnothamnus major lineage is defined here as an Eurasian charophyte lineage ranging from the Late Eocene to the Early Oligocene. Both lineages are well documented in the fossil record owing to their applications in stratigraphic dating. The historical biogeography of these lineages displays two opposite patterns. The lineage L. stockmansii–L. major displays an Eurasian distribution from its first occurrence in the Late Eocene, whilst the lineage N. (T.) merianii–N. obtusa underwent a long period of European provincialism ranging from the Late Eocene to the end of the Early Oligocene (an interval of 10 million years, Ma), to begin later, during the Late Oligocene and Miocene, an eastwards expansion until reaching its present Eurasian distribution. These two different biogeographic patterns appear to be related to the contrasting mechanisms of dispersal in monoecious vs dioecious charophytes, well known in extant Chara, and allow us to identify the time needed by characeans to reach supra-continental distributions.

Charophyte electrogenesis as a biomarker for assessing the risk from low-dose ionizing radiation to a single plant cell

The impact of low-dose ionizing radiation on the electrical signalling pattern and membrane properties of the characea Nitellopsis obtusa was examined using conventional glass-microelectrode and voltage-clamp techniques. The giant cell was exposed to a ubiquitous radionuclide of high biological importance – tritium – for low-dose irradiation. Tritium was applied as tritiated water with an activity concentration of 15 kBq L−1 (an external dose rate that is approximately 0.05 μGy h−1 above the background radiation level); experiments indicated that this was the lowest effective concentration. Investigating the dynamics of electrical excitation of the plasma membrane (action potential) showed that exposing Characeae to tritium for half an hour prolonged the repolarization phase of the action potential by approximately 35%: the repolarization rate decreased from 39.2 ± 3.1 mV s−1 to 25.5 ± 1,8 mV s−1 due to tritium. Voltage-clamp measurements showed that the tritium exposure decreased the Cl– efflux and Ca2+ influx involved in generating an action potential by approximately 27% (Δ = 12.4 ± 1.1 μA cm−2) and 64% (Δ = −5.3 ± 0.4 μA cm−2), respectively. The measured alterations in the action potential dynamics and in the chloride and calcium ion transport due to the exogenous low-dose tritium exposure provide the basis for predicting possible further impairments of plasma membrane regulatory functions, which subsequently disturb essential physiological processes of the plant cell.

Influence of some new aminophosphonates on electrical properties and stability of plasma membranes of plant cells

The effect of new aminophosphonates, synthesized for potential agricultural application, on membrane potential and electrical conductance of internodal cells of <em>Nitellopsis obtusa</em> and their efficiency in modifying the properties of cucumber (<em>Cucumis sativus</em> cv "Wisconsin") cotyledon membranes was studied. They differed in substituents at the carbon and phosphorus atoms. It was found that the organophosphorous compounds caused depolarization of the membrane resting potential and increased electrical conductance of alga membranes. They also influenced chlorophyll content and efflux of electrolytes from cucumber cotyledons. The most significant effects were observed for the compound with iso-propyl substituents at the P atom. In contrast, the weakest modifier of the studied compounds was the one having phenolic substituents at that atom. The observed changes are most probably the result of direct interaction of aminophosphonates with the lipid phase of the plasma membrane and the induced structural changes in it.