Tamara V. Titlyanova

Diurnal and circadian periodicity of mitosis and growth in marine macroalgae. II. The green alga Ulva pseudocurvata

Nuclear division frequency in Ulva pseudocurvata was examined by staining the nuclei with the DNA-localizing fluorochrome DAPI, after separation of the two cell layers of the thallus. Thalli grown in light-dark cycles exhibited division maxima during the dark phase. Growth rate was also coupled to the light-dark cycle, with an increase starting during the dark phase and decrease during the light phase. When thalli were transferred from light-dark cycles to continuous dark, periodicity of nuclear division frequency and growth rate persisted for up to four and six cycles, respectively, with a free-running period of 21 h for growth cycles. In continuous white light, nuclear division oscillated for three or four cycles, while growth rate became immediately arhythmic. The results support the notion that both nuclear division frequency and growth rate in U. pseudocurvata are driven by circadian rhythmicity, with a fast damping of the free-running rhythms in constant light.

Diurnal and circadian periodicity of mitosis and growth in marine macroalgae. III. The red alga Porphyra umbilicalis

In Porphyra umbilicalis, circadian rhythms of nuclear division and growth activity persisted for at least 7 cycles in continuous white fluorescent light, with a period of 21 h for the free-running growth rhythm at 15 µmol m−2 s−1 and 10 °C. Growth rhythmicity was lost at irradiances above 20 µmol m−2 −1. The growth and mitotic rhythms seem to be driven in parallel by circadian rhythmicity, and the details of growth kinetics must be due mainly to the growth behaviour of non-dividing cells. This was inferred from the finding that individual cells continued to grow from one cell division to the next, with generation times of 2–6 days. Transfer from continuous light to 12:12 h light : dark synchronized the free-running growth rhythm, with a high growth peak appearing every 24 h at the start of the light phase and an increase in growth rate during the dark phase. The ascending portion of the free-running growth curve was thus shifted into the night phase of the diurnal regime and the descending portion into th...

Obtaining plantlets from apical meristem of the red alga Gelidium sp.

For the first time, plantlets were obtained from fragments and cell aggregates (CA) of apical meristem of the red alga Gelidium sp. After two months of cultivation, an initial weight of 100 mg of fragments and CA from fresh meristem produced 3 g of plantlets without rhizoids. During the same period of cultivation, 100 mg of meristem fragments and CA isolated from thalli by the freezing-thawing procedure produced more than 20 g of plantlets with rhizoids. It is assumed that our methods for obtaining plantlets from fragments and CA of fresh and frozen-thawed meristem could be used to generate mass planting material for cultivation of algae (plantlets with rhizoids) in the sea and for tank-bubbling cultivation (plantlets without rhizoids). We speculate that meristem cells of frozen-thawed algae might be natural “seedstock” in the Arctic and Antarctic seas.

Circadian rhythm of photosynthesis in Kappaphycus alvarezii (Rhodophyta): independence of the cell cycle and possible photosynthetic clock targets

Various processes in the output pathway of the circadian clock are thought to act as important clock targets resulting in the circadian rhythms of photosynthesis observed in various algae. Examples of such processes are synchronization of the cell cycle, pigmentation, and light or dark reaction of photosynthesis. The newly detected, robust photosynthetic circadian rhythm in the red macroalga Kappaphycus alvarezii was investigated in more detail with respect to rhythmically changing components within the photosynthetic apparatus. The following major results were obtained; (1) The growing tips of Kappaphycus (0–2 cm) were found to exhibit a diurnal and circadian rhythm of nuclear division like many other algal species, (2) The circadian photosynthetic rhythm was apparent in the actively growing and dividing tip portions (0–;2 cm) as well as in older portions (2–4 cm) with little remaining mitotic activity. The Kappaphycus rhythm seems therefore to be independent of the cell cycle, at least in the older portions of the thallus, (3) During real (L:D cycle) or subjective (LL) dark phases, net photosynthetic capacity (Pmax) dropped drastically in young (tip) parts of the thallus, and α, the ‘light affinity’ parameter, decreased likewise. The net result of these two changes was an increase in the light saturation point, Ek. Dark respiration did not change rhythmically from one circadian maximum to the next circadian minimum. ΔF/Fm′ dropped during real and subjective night phases, while non-photochemical quenching (NPQ) increased. Low temperature (77 K) emission spectra with an excitation wavelength of 580 nm exhibited a larger increase of the 720:685 nm as well as the 720:696 nm emission quotients compared with spectra at 440 nm excitation for samples harvested in the middle of the subjective dark phase indicating changes in energy trapping from the phycobilisomes to the photosystems.

Seasonal changes in benthic algal communities of the upper subtidal zone in Sanya Bay ( Hainan Island, China)

A floristic study of the marine plants and algae at Luhuitou reef, Sanya Bay, Hainan Island, China, was conducted during the rainy (October 2008 and November 2010) and dry seasons (April 2009 and February 2012). Specimens were collected in the upper subtidal zone (from 0.5 to 3m depth at low tide). A total of 156 taxa were collected, including 143 macrophyte species (90%), 12 blue-green algal species (10%), and the seagrass, Thalassia hemprichii. The most diverse group was the Rhodophyta (79 taxa or 55%), followed by the Chlorophyta (38 taxa or 25%) and then the Phaeophyceae (26 taxa or 20%). In the upper subtidal zone, macroalgae formed two types of communities: polydominant communities of turf-forming algae and monodominant and bidominant communities of foliose or fleshy algae. Seasonal changes occurred in the dominant species, which appear to be caused by periodic annual events of thalli detachment and subsequent community succession. In spite of heavy pollution from dissolved inorganic nitrogen and phosphorus in Sanya Bay, the subtidal flora has not undergone any dramatic changes in species numbers or composition and is similar to that of unpolluted regions in the Indo-Pacific.

Checklist of marine benthic green algae (Chlorophyta) on Hainan, a subtropical island off the coast of China: comparisons between the 1930s and 1990-2009 reveal environmental changes

Abstract A complete checklist of intertidal to shallow subtidal marine green seaweeds (Chlorophyta) growing on the subtropical island of Hainan (China) is presented here for the first time. It covers data from extensive recent (1990–2009) and historical (1933–1935) collections, and additional published records from various time periods. Data were analyzed by time period. We postulate that environmental changes on Hainan Island documented since the 1980s (e.g., degradation of coral reefs, development of tourism and mariculture farms) are reflected in the green algal species complement and in the dominance or absence of specific algal groups during different time periods. In total, 105 green algal taxa were recorded, including 37 new to Hainan Island, and 18 new records for China. There was a clearly evident change in floristic composition between early and recent collections. In the 1930s, there was a dominance of Caulerpaceae, Codiaceae and Cladophoraceae. By 1990/1992, the numbers of Ulvaceae had increased 1.6-fold and numbers of Cladophoraceae 1.7-fold. Both families contain many opportunistic species that prefer nutrient-enriched or degraded environments. At the same time, species richness of Codiaceae, Caulerpaceae and Udotaceae, families with complex thallus structures, decreased considerably. The floristic differences between the 1990/1992 and 2008/2009 collections were minor.

Stocks and the use of economic marine macrophytes of Vietnam

This review analyzes the literature and original data on the resources, use, and cultivation of useful marine macrophytes in Vietnam. Information is provided about more than 60 species of macroalgae: including 41 species of Rhodophyta, 15 species of Heterokontophyta and 7 species of Chlorophyta. Out of these, more than 50 species are used for food, about 20 species are used in folk medicine, and more than 30 species are important commercial sources of polysaccharides (agar, carrageenan, and alginates); Sargassum, Gracilaria, and Kappaphycus are exported (mainly to China). The wild stocks of useful algae in Vietnam are declining as a result of their uncontrolled export (especially Sargassaceae). Several species of Gracilaria and Kappaphycus are commercially cultivated and also exported.

Distribution of an amino acid-containing phospholipid in brown algae

The phospholipid composition of 30 species of brown algae belonging to eight different orders has been analysed by TLC. A new amino acid-containing phospholipid was detected in members of the orders, Ectocarpales, Chordariales, Dictyotales, Desmarestiales, Scytosiphonales, Laminariales and Fucales. The occurrence of this new amino acid-containing phospholipid has chemotaxonomic value for brown algae.

New records of benthic marine green algae (Chlorophyta) for the island of Hainan (China)

The island of Hainan (China) is located on the northern periphery of the subtropical Pacific Ocean in the South China Sea and possesses one of the most prominent fringing coral reefs of China. The marine algal flora of the island was described for the first time after several early expeditions in the 1930s (and around 1960) mentioning 68 species of marine green algae (Chlorophyta) in total. Sixty years later, the island was revisited in autumn 1990 and spring 1992 within in the framework of two extensive expeditions in order to scrutinise the algal biodiversity of the coral reef habitats. Again 20 years later, three more surveys were performed in 2008, 2009 and 2010 focusing only on the southern shores of Hainan Island near Sanya city. The analysis of this material revealed the existence of 31 new records of marine green algae for Hainan Island, including 17 species which also constitute new records for China. The new records are described and characteristic details are depicted. Collection sites around Hainan Island and world-wide distributions are given. Thirteen newly recorded species were only sampled once and therefore seem to be rare. Thirteen other species are pre-dominantly epiphytic or endophytic. The new records for China are fairly typical for tropical to subtropical locations of south-western to south-eastern Asia, except Chlorochytrium cohnii (distribution hitherto restricted to Europe). Chaetomorpha minima (distribution hitherto restricted to North and Central America, Africa, Indian Ocean islands) and Cladophora perpusilla (distribution hitherto restricted to Central and South America, Australia, New Zealand, Pacific islands). None of the new records are considered to represent an invasive species.

Seasonal changes in the intertidal algal communities of Sanya Bay (Hainan Island, China)

A floristic study of marine macrophytic algae and Cyanobacteria in the splash and intertidal zones at Luhuitou reef, Sanya Bay, Hainan Island, China, was conducted during the rainy and dry seasons of 200822012 utilizing 148 of the most common species. Macrophytic algal diversity increased from the splash zone to the low intertidal zone, while cyanobacterial diversity decreased. In the upper and middle intertidal zones, the dominant species (primarily highly productive ephemerals) changed frequently throughout each year. In the low intertidal zone, the dominant species (mainly annual fleshy, foliose and coriaceous forms) also changed. In the dry season, species numbers were 33% higher than in the rainy season. During the rainy season, Cyanobacteria dominated the splash zone, while green and red algae dominated in increasing numbers from the upper to the low intertidal zones. During the dry season the splash zone was devoid of all macrophytic algae, and only one species of Cyanobacteria survived. In the upper intertidal, Cyanobacteria and red algae prevailed, while in the mid and low zones, red and green algae were the most diverse. In spite of heavy pollution in Sanya Bay, there was no evidence of dramatic changes in species numbers or composition, and the marine flora was similar to that of unpolluted regions in the Indo-Pacific.