Isotope Composition of Nitrogen and Stoichiometric Ratios of Elements in Biomass of Spirogyra in Lake Baikal.

Using stable isotope analysis of nitrogen, for the first time the hypothesis on different sources of inorganic nutrients for two groups of littoral algae in Lake Baikal was confirmed. Strongly attached filamentous algae of genus Ulothrix, which developed in the wave-braking zone at depth 0.5 m, and loosely attached filamentous algae of genus Spirogyra, which developed in deeper layers 3.0-5.0 m in a low-turbulence zone, get inorganic nutrients presumably from surface discharge and groundwater inputs, respectively. Besides, stoichiometric ratios C:N and N:P in biomass of the algae indicated that growth of Spirogyra in Lake Baikal was likely limited by nitrogen, while growth of Ulothrix was limited by phosphorus.

Chemical Composition, Algicidal, Antimicrobial, and Antioxidant Activities of the Essential Oils of Taiwania flousiana Gaussen.

Taiwania flousiana (T. flousiana) Gaussen is a precious wood in the family Taxodiaceae. This study investigated the chemical components of the essential oil from the stem bark of T. flousiana and its algicidal, antifungal, and antioxidant properties. Sixty-nine compounds representing 89.70% of the stem bark essential oil were identified by GC-MS. The essential oil showed strong anti-algae, anti-bacteria, and anti-fungus activities against the tested species, and antioxidant activities. The IC50 values of the essential oil against chlorophyll a, chlorophyll b, and the total chlorophyll of Spirogyra communis (a species of algae), 24-96 h after the treatment, ranged from 31.77 to 84.92 µg/mL, while the IC50 values of butachlor ranged from 40.24 to 58.09 µg/mL. Ultrastructure changes revealed by the transmission electron microscopy indicated that the main algicidal action sites were the chloroplast and cell wall. The essential oil showed antifungal activities on Rhizoctonia solani (EC50 = 287.94 µg/mL) and Colletotrichum gloeosporioiles (EC50 = 378.90 µg/mL). It also showed bactericidal activities on Ralstonia solanacearum and Staphylococcus aureus, with zones of inhibition (ZOIs) being 18.66 and 16.75 mm, respectively at 40 µg/disk. Additionally, the essential oil possessed antioxidant activity estimated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method (IC50 = 33.51 µg/mL; IC50 value of the positive control ascorbic acid was 7.98 µg/mL). Thus, the essential oil of this plant might be used as a possible source of natural bioactive molecules in agrochemical industry as well as in food and cosmetic industries.

Evaluating biochemical response of filamentous algae integrated with different water bodies.

The present study prompted the second attempts to evaluate biochemical responses of filamentous algae under different physico-chemical variables in various water bodies in Turkey. These variables were investigated by use of multivariate approach in the years of 2013 (May and November) and 2014 (May and October). Studied ecoregions had the different geographic position, climate, land-use, and anthropogenic activities, could strongly affect physico-chemical variables of water bodies, which caused to change or regulate in algal biomass composition due to the different response of filamentous species. Besides, biochemical responses of species changed at different sampling times and stations. Multivariate analyses indicated that temperature, heavy metals, and nutrient contents of aquatic systems were found to be major variables driving the spatial and temporal occurrence and biochemical contents of filamentous species. Total protein and pigment production by filamentous algae were high in water bodies having high nutrients, whereas they were low in high heavy metal contents. Amount of malondialdehyde (MDA), H2O2, total thiol group, total phenolic compounds, proline, total carbohydrate, and bioaccumulation of metals by filamentous algae were closely related with heavy metal contents of water bodies, indicated by the multivariate approach. Significant increase in aforementioned biochemical compounds with a distinct range of habitats and sensitive-tolerance to environmental conditions could make them highly valuable indicators.

The effect of bloom of filamentous green algae on the reproduction of yellowfin sculpin Cottocomephorus grewingkii (Dybowski, 1874) (Cottoidae) during ecological crisis in Lake Baikal.

In shallow water areas of open Lake Baikal, filamentous green alga of the genus Spirogyra grows abundantly. Together with alga of the genus Ulothrix, it forms algal mats. According to our observations from 2010 to 2013, the spawning habitat conditions for the yellowfin sculpin Cottocomephorus grewingkii (Dybowski, 1874) (Cottidae) proved to be significantly disturbed in the littoral zone of Listvennichnyi Bay (southern Baikal), which, in turn, reduced the number of egg layings. With a 100% projective cover of the floor and a high density of green filamentous algae, the shallow-water stony substrate becomes completely inaccessible for spawning of the August population.

Algal ancestor of land plants was preadapted for symbiosis.

Colonization of land by plants was a major transition on Earth, but the developmental and genetic innovations required for this transition remain unknown. Physiological studies and the fossil record strongly suggest that the ability of the first land plants to form symbiotic associations with beneficial fungi was one of these critical innovations. In angiosperms, genes required for the perception and transduction of diffusible fungal signals for root colonization and for nutrient exchange have been characterized. However, the origin of these genes and their potential correlation with land colonization remain elusive. A comprehensive phylogenetic analysis of 259 transcriptomes and 10 green algal and basal land plant genomes, coupled with the characterization of the evolutionary path leading to the appearance of a key regulator, a calcium- and calmodulin-dependent protein kinase, showed that the symbiotic signaling pathway predated the first land plants. In contrast, downstream genes required for root colonization and their specific expression pattern probably appeared subsequent to the colonization of land. We conclude that the most recent common ancestor of extant land plants and green algae was preadapted for symbiotic associations. Subsequent improvement of this precursor stage in early land plants through rounds of gene duplication led to the acquisition of additional pathways and the ability to form a fully functional arbuscular mycorrhizal symbiosis.

[Effects of filamentous macroalgae on the methane emission from urban river: a review].

The global warming caused by greenhouse gases emission has raised serious concerns. Recent studies found that the carbon dioxide (CO2) and methane (CH4) emissions from river ecosystem can partly offset the carbon sequestration by terrestrial ecosystem, leading to a rethink of the effects of river ecosystem on the global carbon balance and greenhouse gases emission inventory. As an important primary producer in urban river ecosystem, filamentous macroalgae can deeply affect the carbon cycle process of river system through changing the abiotic and biotic factors in the interface of water-sediment. This paper reviewed the effects of filamentous macroalgae on the CH4 emission from urban river system from the aspects of 1) the effects of urbanization on the river ecosystem and its CH4 emission flux, 2) the effects of filamentous macroalgae on the CH4 generation and emission process in natural river systems, and 3) the effects of filamentous macroalgae on the primary productivity and CH4 emission process in urban river systems. The current problems and future directions in related researches were discussed and prospected.

Proteomic analysis of Spirogyra varians mutant with high starch content and growth rate induced by gamma irradiation.

This study was conducted to develop a high-efficiency strain of Spirogyra varians for the production of biomass by radiation breeding. The characteristics of wild-type and mutant S. varians were analyzed through phenomenological and proteomic observations. The results of our phenomenological observations of the S. varians mutant demonstrated increases in growth rate and content of chlorophyll a, b, and a + b; in particular, a significant threefold increase was observed in starch accumulation. Proteomic analysis to investigate the differences in expression between wild-type and mutant proteins identified 18 proteins with significantly different expressions. From the literature review, it was confirmed that the up-regulated proteins were mainly involved in photosynthesis, carbohydrate biosynthesis, and energy metabolism. These results suggest the possibility of algae development by radiation breeding for the production of biofuel.

Studies on conjugation of Spirogyra using monoclonal culture.

We succeeded in inducing conjugation of Spirogyra castanacea by incubating algal filaments on agar plate. Conjugation could be induced using clone culture. The scalariform conjugation was generally observed, while lateral conjugation was rarely. When two filaments formed scalariform conjugation, all cells of one filament behaved as male and those of other filament did as female. Very rarely, however, zygospores were formed in both of pair filaments. The surface of conjugation tube was stained with fluorescently labeled-lectins, such as Bandeiraea (Griffonia) simplicifolia lectin (BSL-I) and jacalin. BSL-I strongly stained the conjugation tubes, while weakly did the cell surface of female gamete first and then that of male gamete. Jacalin stained mainly the conjugation tubes. Addition of jacalin inhibited the formation of papilla, suggesting some important role of jacalin-binding material at the initial step of formation of the conjugation tubes.

The biosorption of heavy metals from aqueous solution by Spirogyra and Cladophora filamentous macroalgae.

The aim of this research was to develop a low cost adsorbent for wastewater treatment. The prime objective of this study was to search for suitable freshwater filamentous algae that have a high heavy metal ion removal capability. This study evaluated the biosorption capacity from aqueous solutions of the green algae species, Spirogyra and Cladophora, for lead (Pb(II)) and copper (Cu(II)). In comparing the analysis of the Langmuir and Freundlich isotherm models, the adsorption of Pb(II) and Cu(II) by these two types of biosorbents showed a better fit with the Langmuir isotherm model. In the adsorption of heavy metal ions by these two types of biosorbents, chemical and physical adsorption of particle surfaces was perhaps more significant than diffusion and adsorption between particles. Continuous adsorption-desorption experiments discovered that both types of biomass were excellent biosorbents with potential for further development.

[Enclosure experiments about the hydrodynamics effects on the plankton].

To explore the effects of hydrodynamics on plankton, four kinds of surface flow enclosure experiments were done from August, 2007 to July, 2008. The flow velocity were 0.002, 0.10, 0.15 and 0.30 m x s(-1) respectively. Under 0.15 and 0.30 m x s(-1) surface velocity conditions, it was revealed that Spirogyra biomasses were 2.3 times and 31.3 times of the ones under static state respectively. Under 0.10, 0.15 and 0.30 m x s(-1) conditions, Chl-a concentrations were 45%, 54% and 26% of the ones under statistic state while zooplankton biomasses were 38%, 27% and 6% respectively. The mechanism is that a certain flow velocity stimulates Spirogyra growth may be for the shear stress generated by the surface flow can help the vegetative reproduction. Shear stress and turbulence may also bring the phytoplankton to the light limited area by force. Besides, as Spirogyra grows well, it can inhibit the phytoplankton growth by excretion or some symbiotic microorganism. When shear stress or water turbulence exceeds a certain value, crustacean zooplankton successful grazing rate may also be depressed.