Lamprothamnium Succinctum Research Articles

New distributional records, taxonomy, morphology, and genetic variations of the endangered brackish-water species Lamprothamnium succinctum (Charales: Charophyceae) in Japan

Members of the brackish-water species Lamprothamnium succinctum (Charales, Charophyceae) are widely distributed from tropical to temperate regions, including East Asia. In Japan, L. succinctum is listed as an endangered species and is protected by the government, because it was recorded only at two localities, Lake Hachiro-gata (Akita Prefecture) and Oo-ike pond (Deba-jima Island, Tokushima prefecture), and has become extinct in the former. In this study, we identified five new localities of this species in Japan. The morphological characteristics of their thalli agreed with those provided in the original description of this species, with distinctive reproductive characteristics. Moreover, the oospores of Japanese specimens of L. succinctum were examined for the first time using scanning electron microscopy. The oospores of Japanese specimens exhibited granulate fossa wall patterns, which were consistent with those described in previous studies. Our genetic analyses based on the DNA sequences of two chloroplast DNA markers, including both the coding and non-coding regions, revealed that the sample from Oo-ike pond is distinguishable from those from other Japanese specimens, although they are genetically very similar.

The Characeae (Charales, Charophyceae) of Sardinia (Italy): habitats, distribution and conservation

The charophyte flora of Italy is insufficiently known. This paper reports the results of a survey of the historical and recent distribution of Characeae in Sardinia, in order to fill current knowledge gaps. Information about the study area and the database is presented. The study focused on brackish water bodies with a special emphasis on lagoons and temporary brackish pools as well as on freshwater habitats. Between 1988 and 2018 more than 500 water bodies have been investigated. Characeae were recorded in 212 sites. In total, the occurrence of 26 Characean species was verified. They belong to four genera: Chara (13 taxa), Nitella (seven), Tolypella (four) and Lamprothamnium (two). The abundance of the species is discussed and information about their habitats and distribution is given. Distribution maps for selected taxa are presented. During this study Lamprothamnium succinctum was recorded for the first time in Europe. Tolypella salina and Chara baltica were verified as new species for Italy. Moreover, Nitella confervacea and Chara connivens, neither of them recently reported, are confirmed for Italy. A new sexual population of Chara canescens was discovered. As a result of the present study the total number of Characean species known for Sardinia has been increased from 15 to 26. Many taxa, especially nine species closely linked to brackish habitats, are currently very rare throughout Italy. Threats and pressures on Characeae and their habitats in Sardinia are discussed and appropriate actions for their conservation are proposed.

Diversity and Distribution of Characeae in the Maghreb (Algeria, Morocco, Tunisia)

Characeae are macroscopic green algae present in the Maghreb (Morocco, Algeria, Tunisia) that are known since the 19th century works of Desfontaines (1800) and Braun (1868). Feldmann (1946) published the first regional synthesis, and this study provides a new Maghreb-wide synthesis of all collections made since 1784 (570 observations distributed over 464 sites). Each of the 31 reported species is described in detail with its diagnostic features, ecology and distribution in the three Maghrebian countries. Distribution maps distinguish between the three collection periods: 1780–1939, 1940–1979, and 1980–2016. An illustrated key is provided to help botanists working in the Maghreb to identify the taxa. From a biogeographical perspective, the Characean flora of the Maghreb is dominated by elements originating from northern (European) countries (61.3%) that include regionally very rare species such as Chara strigosa and C. tomentosa. The Mediterranean-Atlantic element is also well represented (32.3%), with some Mediterranean endemics (Chara imperfecta, C. oedophylla, C. vulgaris var. gymnophylla). Finally, two taxa that have an affinity for tropical conditions (Chara zeylanica and Lamprothamnium succinctum) extend to the southern Sahara. In North Africa, 14 species (7 Chara, 2 Lamprothamnium, 4 Nitella and 1 Sphaerochara) are threatened and raise issues about their conservation; three of these are particularly endangered: Chara imperfecta, C. oedophylla and Lamprothamnium papulosum.

Quaternary and extant euryhaline Lamprothamnium Groves (Charales) from Australia: Gyrogonite morphology and paleolimnological significance

Charophytes are very common in Australian modern and Quaternary waterbodies, and are quite commonly incorrectly reported as “Chara” sp. or Lamprothamnium papulosum (Wallroth) Groves. This paper is the first attempt at the identification of the widespread euryhaline genus Lamprothamnium in Australia, and its use as a paleoenvironmental indicator. Lamprothamnium is distributed worldwide in all continents, except north and central America. The Australian environment, characterized by increasing aridity during the last 500 ka, has an abundance of saline lakes. We sampled 30 modern lakes and identified extant Lamprothamnium macropogon (A. Braun) Ophel and Lamprothamnium succinctum (A. Braun in Ascherson) Wood. Fossil gyrogonites, from lacustrine sediments ∼65 ka old from Madigan Gulf, Lake Eyre, were identified as Lamprothamnium williamsii sp. nov. We applied statistical analysis (analysis of variance, ANOVA) to the morphometry of the gyrogonites from one fossil and three living Lamprothamnium populations. The ANOVA test suggests all the populations are different, including two separate populations of extant L. macropogon, interpreted in this case as the expression of ecophenotypic variability. Lamprothamnium is a useful paleoenvironmental indicator because it indicates a non-marine environment with varying salinity ranging from fresh (usually 2–3 g l−1) to 70 g l−1, and water bodies holding water for at least 70 consecutive days. Collectively, these parameters provide important information in the study of ephemeral habitats.

Temporal relationship between cytosolic free Ca(2+) and membrane potential during hypotonic turgor regulation in a brackish water Charophyte Lamprothamnium succinctum.

Internodal cells of a brackish water charophyte, Lamprothamnium succinctum, regulate turgor pressure in response to changes in external osmotic pressure by modifying vacuolar concentrations of KCl. An increase in cytosolic concentration of free Ca(2+) ([Ca(2+)](c)) is necessary for the progress of turgor regulation induced by hypotonic treatment. Initial changes in membrane potential and [Ca(2+)](c) upon hypotonic treatment were measured to examine the temporal relationship between the two parameters. Fura-dextran (potassium salt, M(r) 10,000, anionic) that had been injected into the cytosol was used to measure [Ca(2+)](c). Membrane potential and membrane conductance under a current-clamp condition were also measured. Decrease in external osmotic pressure by 0.16 Osm induced a simultaneous increase in [Ca(2+)](c) with both depolarization of the membrane and increase in the membrane conductance. Decrease in external osmotic pressure by 0.05 Osm induced a simultaneous increase in [Ca(2+)](c) with membrane depolarization but the increase in membrane conductance started later than the other two processes. There was a close temporal relationship between the increase in [Ca(2+)](c) and membrane depolarization on the initial response of turgor regulation induced by hypotonic treatment.

The charophyte Lamprothamnium succinctum as an environmental indicator: a Holocene example from Tom Thumbs Lagoon, eastern Australia

The palaeobiota from a middle to late Holocene succession in Tom Thumbs Lagoon, N.S.W., Australia, reflects a range of environmental conditions caused by sea-level changes and active estuarine sedimentation. At the base of the succession (∼ −0.4 m AHD) a thin bed, containing molluscs dated at 6.7 ka B.P. by radiocarbon and amino acid racemisation, and foraminifers is indicative of open estuarine conditions. From +0.35 m AHD towards the top of the sequence the charophyte Lamprothamnium succinctum occurs in subrecent deposits. This species is characterised here by statistical measurements, and new characters are described and illustrated. The charophytes record a drop in sea level and the establishment of a lower salinity artificial wetland. The investigation has also established that decalcification in charophytes can be related to acidification produced by the release of organic acids, aggravated after 1928 by anthropogenic pollution.

Quaternary charophytes from Salina del Bebedero, Argentina: their relation with extant taxa and palaeolimnological significance

Charophyte (Charales, green macroscopic algae) assemblages found in Quaternary shoreline sediments from Salina del Bebedero, Argentina, are described in detail, illustrated, and statistically analysed. Fossil gyrogonites, Late Pleistocene and Holocene in age, of Chara cf. hispida var. major (Hartman) Wood, Chara halina Garcia, Chara hornemannii Wallmann, Chara bulbillifera (Donterberg) Garcia, Lamprothamnium haesseliae Donterberg and Lamprothamnium succinctum (Braun ex Ascherson) Wood were identified. A comparison with extant charophyte species of similar ecological requirements allowed for an accurate systematical determination and provided useful data for complementary palaeoecological and palaeobiogeographical approaches. On this basis, a reconstruction of palaeo-salinities for the Salina del Bebedero lake, represented by eleven palaeo-beaches, is proposed. Also the associations of charophytes with the ostracods Cyprideis sp., Limnocythere sp., Pampacythere sp., Cypridopsis sp., Darwinula sp., Ilyocypris gibba (Randohr) Brady and Norman, and the foraminifers Ammonia sp., Elphidium gunteri Cole, Quinqueloculina sp., and one species of Discorbacea are analysed, since they are present in both the fossil and modern environments.

Turgor regulation in a brackish water charophyte,Lamprothamnium succinctum

Internodal cells of a brackish water charophyte,Lamprothamnium succinctum (A. Br. in Ash.) R.D.W. regulate the turgor pressure in response to changes in both the cellular and the external osmotic pressures. During turgor regulation upon hypotonic treatment, net effluxes of K+ and Cl− from the vacuole, membrane depolarization, a transient increase in the electrical membrane conductance and a transient increase in concentration of cytoplasmic Ca2+ are induced. Activation of the plasmalemma Ca2+ channels and the Ca2+-controlled passive effluxes of K+ and Cl− through the plasmalemma ion channels are postulated.

Net efflux of Cl− during hypotonic turgor regulation in a brackish water alga Lamprothamnium*

Abstract. Net efflux of Cl− was measured potentiometrically (Ag/AgCl electrode) during turgor regulation which was induced by hypotonic treatment (hypotonic turgor regulation) in the alga Lamprothamnium succinctum. The efflux of Cl− reached the peak value (11 μmol m −2s−1) several minutes after the hypotonic treatment was started and then declined. The efflux of Cl− and inhibition of the cytoplasmic streaming [reflection of an increase in cytoplasmic concentration of free Ca2+([Ca2+]c)] were blocked under a low external concentration of Ca2+ ([Ca2+]e) (0·01 mol m−3) and resumed after raising [Ca2+]e to the normal value (3·9 mol m−3). The decrease in cell‐osmotic pressure upon hypotonic treatment was inhibited by lowering either turgor pressure or [Ca2h]e. The inhibition was reflected in decreases of both the efflux of Cl− and the membrane conductance. Recovery of the cytoplasmic streaming from the inhibition was also accelerated by the same treatments. It is concluded that an increase in turgor pressure is continuously sensed by the cells and that continuous presence of external Ca2+ is necessary for the hypotonic turgor regulation.

Patch-Clamp Study on a Ca2+-Regulated K+ Channel in the Tonoplast of the Brackish Characeae Lamprothamnium succinctum

Patch-Clamp Study on a Ca2+-Regulated K+ Channel in the Tonoplast of the Brackish Characeae Lamprothamnium succinctum

The mechanism of turgor regulation in plant cells.

Regulation of turor pressure is indispensable to plant cells. In algal cells, turgor pressure is regulated by changing intracellular osmotic pressure via transport of inorganic ions between vacuole and external medium. The brackish water alga, Lamprothamnium succinctum regulate turgor pressure upon hypotonic treatment by releasing K+ and Cl-. We have found that an increase in cytoplasmic free Ca2+ concentration ([Ca2+]c) occurs upon hypotonic treatment. The signal of an increase in turgor pressure may be transduced into this signal, an increase in [Ca2+]c', which would control channel-mediated ion transport from vacuole to extenal medium.

Increase in cytoplasmic calcium content in internodal cells of Lamprothamnium upon hypotonic treatment

Abstract Internodal cells of Lamprothamnium succinctum, a brackish water Characeae, regulate turgor pressure in response to changes in external osmotic pressure (turgor regulation). When internodal cells were transferred to a hypotonic medium containing 3.9 mol m−3 Ca2+, the cell osmotic pressure decreased and the original turgor pressure was recovered. During turgor regulation Ca content of the cytoplasm increased significantly. Lowering the external Ca2+ concentration from 3.9 to 0.01 mol m−3 inhibited this increase in cytoplasmic calcium content. In a hypotonic medium containing 0.01 mol m−3 Ca2+, turgor regulation was inhibited as previously reported (Okazaki & Tazawa, 1986a). Thus transient increase in cytoplasmic Ca, probably in the ionized form, induced by hypotonic treatment may play an important role in turgor regulation.

Turgor Regulation in a Brackish Water Charophyte, <italic>Lamprothamnium succinctum</italic> III. Changes in Cytoplasmic Free Amino Acids and Sucrose Contents during Turgor Regulation

Turgor Regulation in a Brackish Water Charophyte, <italic>Lamprothamnium succinctum</italic> III. Changes in Cytoplasmic Free Amino Acids and Sucrose Contents during Turgor Regulation

Bulbils of some charophytes

The structure and development of the bulbils ofChara hornemannii, Chara aspera, Lamprothamnium papulosum, Lamprothamnium succinctum andNitellopsis obtusa have been studied.

Effect of calcium ion on cytoplasmic streaming during turgor regulation in a brackish water charophyte Lamprothamnium

Abstract The brackish water charophyte Lamprothamnium succinctum regulates its turgor pressure against changes in the external osmotic pressure. Upon hypotonic treatment, the rate of cytoplasmic streaming in the internodal cells fell to almost zero, and then recovered to the original value within 20 min. The decrease could be inhibited by lowering the external Ca2+ concentration in the hypotonic medium. Also, cytoplasmic streaming in tonoplast‐free cells of L. succintum was sensitive to Ca2+ like freshwater charophyte. Thus, the concentration of free Ca2+ in the cytoplasm seems to increase transiently upon hypotonic treatment.

Involvement of calcium ion in turgor regulation upon hypotonic treatment in Lamprothamnium succinctum

Abstract When internodal cells of Lamprothamnium succinetum were exposed to a hypotonic medium containing more than 1 mol m−3 Ca2+, the elevated turgor pressure decreased and reached a steady state within 30–60 min. The hypotonic treatment caused the membrane potential to depolarize, with a time lag of ca. 1 min. The membrane conductance increased transiently with the same time lag and reached a peak value within 2–3 min. When the external Ca2+ concentration was lowered to 0.01 mol m−3, both turgor regulation and change in the membrane conductance were strongly inhibited, although the membrane depolarization was not affected. When the Ca2+ level was returned to the normal level, the cells recovered their ability for turgor regulation and the membrane conductance attained a peak value after ca. 15–30 s. This response time is definitely shorter than that needed for the conductance change in cells exposed to a hypotonic medium having a normal level of Ca2+ from the beginning. We thus conclude that at least two sequential processes are involved in turgor regulation: a Ca2+ ‐independent process, followed by a Ca2+‐dependent process.

Motile protoplasmic fibtils in cells of theCharaceae

1. In order to further elucidate the mechanism of protoplasmic streaming, the structure and behaviour of motile protoplasmic fibrils were studied in living characean cells ofNitella flexilis, Lamprothamnium succinctum, andCbara australis on the light microscopic level. 2. Motile fibrils similar to those described in cytoplasmic drops isolatedin vitro from Characeae cells, are also foundin vivo in the endoplasm in centrifuged cells. The intracellular, freely-moving fibrils appear mostly in the form of polygons. 3. The modes of movement of the fibrillar loops are classified into two categories,i.e., 1) undulatory type and 2) rotatory type. Generally the fibrils belonging to the undulatory type have many small cytoplasmic particles associated with them while those classified as rotatory type are nearly free of particles and the fibrilsper se are observable. The width of the naked fibril is estimated to be in the range 0.1–0.2μ. It was shown that the speed of the fibrils of the rotatory type approximates the rate of normal protoplasmic streaming (70–80 μ/sec at 23° C). 4. A thin (ca. 0.2μ), linear, stationary fibrillar structure is found at zoneD (cf., Fig. 1) of the centrifuged internode ofNitella. The characteristics of the linear structure anchored to the cortex are quite similar to those of the motile fibrillar loops of the rotatory type. Transition from the linear fibril to the rotating loop was observed. It was shown that there is a close relation between the linear fibrillar structure and protoplasmic streaming. 5. The thin, linear, stationary fibrillar structures are also found in the rhizoid and both etiolated and intact internodes ofNitella flexilis and in normal internodal cells of bothLamprothamnium succinctum andChara australis. The fibrils in question seem to be the morphological entity responsible for protoplasmic streaming.