The Influence of Fucoxanthin Immobilized on Porous Aluminum-Silicon Carrier Surface on the Functional Activities of Immunocytes in Mice

Fucoxanthin is a natural carotenoid obtained from seaweed which exhibits antioxidant properties. This research aimed to assess whether fucoxanthin, immobilized on aluminum-silicon carrier particles, has a toxic effect on immune cells. The viability, proliferation, nitric oxide production and myeloperoxidase activity of thymocytes and splenocytes of mice in vitro were studied. It was shown that fucoxanthin, immobilized on aluminum-silicon carrier particles, increased the survival rate and proliferation of mature immunocytes (splenocytes) after 24 hours exposure and increased the survival rate of naïve immunocytes (thymocytes) when exposed for 120 hours. In terms of myeloperoxidase, the activity of the immune cells was not affected by fucoxanthin immobilized on the carrier particles. The obtained results indicated that fucoxanthin, immobilized on particles of an aluminum-silicon carrier, did not have a toxic effect on mouse immunocytes. Keywords: Cylindrotheca closterium, fucoxanthin, γ-aluminum oxide, polydimethylsiloxane, thymocytes, splenocytes, viability, proliferation, nitric oxide, myeloperoxidase activity

Интенсивная культура Cylindrotheca closterium (Ehrenberg) Reimann et Lewin на питательной среде с гидрокарбонатом натрия

Экспериментально показана возможность использования гидрокарбоната натрия в питательной среде для обеспечения культуры C. closterium углеродом в условиях интенсивного культивирования без подачи CO2 в суспензию. После адаптации C. closterium к питательной среде с гидрокарбонатом натрия с концентрацией 1,2 г·л−1 наблюдался активный рост с максимальной продуктивностью 0,6–0,7 г·(л·сут)−1 сухой массы. В клетки диатомовых водорослей углерод проникает как в форме углекислого газа, так и в форме гидрокарбонат-ионов. Однако все питательные среды для искусственного культивирования диатомей по-прежнему предполагают применение CO2 из атмосферы или баллона. Цель работы — оценить возможность использования гидрокарбоната натрия для обеспечения C. closterium углеродом в условиях интенсивного культивирования без подачи CO2 в суспензию. Культуру выращивали в режиме накопительного культивирования в колбе объёмом 1 л на питательной среде RS, приготовленной на стерильной черноморской воде, следующего состава (г·л−1): NaNO3 — 0,775; NaH2PO4·2H2O — 0,0641; Na2SiO3·9H2O — 0,386; Na2EDTA — 0,0872; FeSO4·7H2O — 0,045; CuSO4·5H2O — 0,2·10−3; ZnSO4·7H2O — 0,44·10−3; CoCl2·6H2O — 0,2·10−3; MnCl2·4H2O — 0,36·10−3; NaMoO4·H2O — 0,12·10−3. Предварительно в ней растворили 1,2 г·л−1 гидрокарбоната натрия. Суспензию клеток перемешивали посредством магнитной мешалки (250 оборотов в минуту). На 4-й день эксперимента в культуру добавили 1 г NaHCO3 и 2 мл 0,1 н соляной кислоты, чтобы снизить pH до 8,6. Со 2-го дня эксперимента зарегистрирован активный рост с максимальной продуктивностью 0,6 г·(л·сут)−1. После добавления в активно растущую культуру 1 г·л−1 гидрокарбоната натрия и снижения pH до 8,6 наблюдали снижение скорости роста практически до нуля, однако, судя по скорости повышения pH среды́ за время адаптации, культура активно поглощала гидрокарбонат-ионы. Экспериментально показана возможность культивирования бентосной диатомовой водоросли C. closterium на питательной среде с высоким содержанием гидрокарбоната натрия. Установлено, что на питательной среде RS с добавлением 1,2 г·л−1 гидрокарбоната натрия в условиях интенсивного культивирования максимальная продуктивность C. closterium достигает 0,7 г·(л·сут)−1, при этом отмечено существенное повышение pH среды́. По нашим данным, оптимальное значение pH среды́ для роста C. closterium находится в диапазоне 8,4–9,4. При pH > 9,4 рост диатомовых водорослей замедляется, а при достижении в питательной среде значения pH 9,9 культура переходит в фазу отмирания.

Phytoplankton Response to Changes in Water Quality and a Flood Event in Hervey Bay, Queensland

Dynamic, integrated and complex processes dominate nearshore marine ecosystems. Industrial, agricultural and population growth delivers pollution and excess nutrient and sediment loads to nearshore marine zones. Climate change also poses serious threats to the delicate balance that exists between and within marine ecosystem processes. Methods to monitor, characterise and model nearshore marine systems have been developed to predict responses to changes in the physical, chemical and biological parameters that constitute elements of a model. Such models are useful to management authorities as they provide a tool to mitigate adverse impacts to marine ecosystems. Phytoplankton community structure provides a sensitive early warning for change to marine ecosystems. It is also a vital component of models derived to determine light attenuation and requirements for healthy seagrass and coral habitats. The multifactorial physicochemical drivers of change to marine microalgae abundance and community structure were investigated in Hervey Bay following two floods, a cyclone and destruction of 1000 km2 of seagrass. A water quality gradient from point sources to offshore sites was identified. Correlations between chlorophyll a (Chl a) and both soluble reactive phosphate (SRP) and total suspended solids was revealed. Diatoms dominated the phytoplankton community structure with seasonal and site differences detected amongst 150 phytoplankton species. Chl a, Secchi depth, SRP and pH maximised the rank correlation with phytoplankton assemblage structure (ρ = 0.63) to best ‘explain’ the link between water quality and phytoplankton (BIOENV). Indicator species include Cylindrotheca closterium for the nearshore degraded sites and Rhizosolenia sp. and Guinardia sp. (G. flaccida and G. striatula) for the offshore more pristine habitats. Following the flood in February 1995, Cylindrotheca closterium, Pseudonitzschia sp. and Skeletonema costatum bloomed at Pulgul Creek (a treated sewage effluent site), and Thalassionema frauenfeldii, Cerataulina bicornis and dinoflagellates bloomed at the mouth of the Mary River (agricultural runoff). Discharge-driven flood impact and trigger values were analysed to assist management authorities in their decision making around potential seafood biotoxin problems associated with harmful algal blooms (HAB’s). Results highlight the importance of species determination rather than Chl a assessment when evaluating the health of an ecosystem. Spring blooms of Trichodesium sp. indicate an additional nutrient source during high traffic of commercial whale watching vessels. Flood impacts highlight the need to schedule dredging, construction and other land management and development activities outside of flood periods. Commercial fishing and swimming should be avoided following a flood due to the health risks associated with toxic phytoplankton species (HAB’s) and for the health and safety of swimmers, consumers and other aquatic species. Future research to replicate this study in Hervey Bay and in other estuaries holds much value to further explore the phytoplankton species identified as bio-indicators of ecosystem health in the present study. Research yet to be published, addresses the links between water quality and seagrass epiphytes, light attenuation and the habitat requirements of seagrass in Hervey Bay.

Effects of light qualities on growth, lipid contents and fatty acids profiles of Cylindrotheca closterium

Background Marine diatoms were considered as a promising alternative to microbial resources for the development of biofuels, food additives, medicines and chemical materials. Light of wavelength is a principal element that can easily be controlled in microalgal scale-culture and influence the growth, pigment composition, and lipids accumulation of algal cells. With the increasing implementation of light-emitting diodes (LEDs) in microalgal production systems (photobioreactors), a measure of light quality controlled by LED could be suitable to improve microalgal yields. Results In this study, Cylindrotheca Closterium, a widely used diatom, influenced by five light quality (white, red, blue, green and yellow light) was tested for its effects of growth rates, chlorophylls contents, total lipids contents and fatty acids compositions. The growth and chlorophyll experiments also showed that the green and yellow light significantly improve the growth rates and chlorophylls contents than other groups (P < 0.05). The group white light showed the greatest increases in total lipid contents of C. closterium (P < 0.05). The group blue light had the highest polyunsaturated fatty acids (PUFAs) proportion (P < 0.05), while the group white showed the lowest PUFAs and the highest saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) proportions (P < 0.05). The proportions of SFAs and MUFAs were negatively correlated with growth, chlorophylls, and lipids. And the proportion of PUFAs and n-3 PUFA was positively correlated with growth chlorophylls, and lipids. Principal component analysis showed that the fatty acid composition differed among light quality groups. Conclusion In summary, green light and yellow light were conductive to boosting the growth and chlorophylls accumulation of C. closterium. White light increased total lipid yields, while blue light was superior in increasing the production of unsaturated fatty acids, especially on the timnodonic acid (EPA). The application of two-step methods to increase the production of biomass and fatty acids is an effective measure for the cultivation of C. closterium; green light is used to increase the growth, followed by white light cultivation to improve total lipids or blue light to enhance the proportion of PUFAs of C. closterium.

Photosynthetic and Antioxidant Activities in Extremophile Microalgae Dunaliella Salina, Cylindrotheca Closterium and Phormidium Versicolor According to NaCl Concentration and Irradiance

Dunaliella salina (Chlorophyceae), Phormidium versicolor (Cyanophyceae) and Cylindrotheca closterium (Bacillariophyceae) were isolated from three ponds in the solar saltern of Sfax (Tunisia) having an average salinity of 350, 100 and 90 respectively. Growth, pigment contents, photosynthetic and antioxidant enzyme activities were measured under controlled conditions: three light levels (300, 500 and 1000 µmol photons m-2 s-1) and three NaCl concentrations (40, 80 and 140 g L-1). The highest salinity reduced the growth of D. salina and P. versicolor, and strongly inhibited that of C. closterium. These results are in accordance with the species distibution in the salt marshes. Irradiance rise only induced a significant increase of net photosynthesis in C. closterium probably due to the efficient nonphotochemical quenching and antioxidative enzyme activities. According to □PSII values, the photosynthetic apparatus of P. versicolor was stimulated by increasing salinity whereas that of D. salina and C. closterium was decreased by irradiance rise. The production of carotenoids in D. salina and P. versicolor was stimulated when salinity and irradiance increased whereas it decreased in the diatom. Antioxidant activity of carotenoids could compensate the low antioxidant enzyme activity measured in D. salina.

Pheromone Mediated Sexual Reproduction of Pennate Diatom Cylindrotheca closterium

Benthic diatoms dominate primary production in marine subtidal and intertidal environments. Their extraordinary species diversity and ecological success is thought to be linked with their predominantly heterothallic sexual reproduction. Little is known about pheromone involvement during mating of pennate diatoms. Here we describe pheromone guided mating in the coastal raphid diatom Cylindrotheca closterium. We show that the two mating types (mt+ and mt−) have distinct functions. Similar to other benthic diatoms, mt+ cells are searching for the mt− cells to pair. To enhance mating efficiency mt− exudes an attraction pheromone which we proved by establishing a novel capillary assay. Further, two more pheromones produced by mt− promote the sexual events. One arrests the cell cycle progression of mt+ while the other induces gametogenesis of mt+. We suggest that C. closterium shares a functionally similar pheromone system with other pennate diatoms like Seminavis robusta and Pseudostaurosira trainorii which synchronize sexual events and mate attraction. Remarkably, we found no evidence of mt+ producing pheromones, which differentiates C. closterium from other pennates and suggests a less complex pheromone system in C. closterium.

Pheromone Mediated Sexual Reproduction of Pennate Diatom Cylindrotheca Closterium

Benthic diatoms dominate primary production in marine subtidal and intertidal environments. Their extraordinary species diversity and ecological success is thought to be linked with their motility and predominantly heterothallic sexual reproduction. Little is known about pheromone involvement during mating of pennate diatoms. Here we describe pheromone guided mating in the coastal raphid diatom Cylindrotheca closterium. We show that the two mating types (mt+ and mt¯) have distinct functions. Similar to other benthic diatoms, mt+ cells are searching for the mt¯ cells to pair. To enhance mating efficiency mt¯ exudes an attraction pheromone, which we proved by establishing a novel capillary assay. Further, two more pheromones produced by mt¯ promote the sexual events. One arrests the cell cycle progression of mt+ while the other induces gametogenesis of mt+. We suggest that C. closterium shares a functionally similar pheromone system with other pennate diatoms like Seminavis robusta and Pseudostaurosira trainorii which synchronize sexual events and mate attraction. Remarkably, we found no evidence of mt+ producing pheromones, which differentiates C. closterium from other pennates and suggests a less complex pheromone system in C. closterium.

The biochemical composition of Cylindrotheca closterium (Ehrenb.) Rayman net Levin, as a source of biologically active substances in cumulative cultivation

In this work, we studied the biochemical characteristics of the diatom Cylindrotheca closterium in the cumulative mode of cultivation in different phases of growth. According to our data, in the exponential growth phase, C. closterium biomass is characterized by a minimum lipid content of 3% of dry biomass and a maximum carbohydrates content of 23% of dry weight. During the transition of C. closterium culture to the stationary growth phase, as in the case of a representative of diatoms, a rather high accumulation of total lipids is observed – to 28% dry weight, while the carbohydrates content decreases to 7%. At the end of the stationary phase (21st day of cultivation), the content of fatty acids is 50% of total lipids or 12.5% of dry weight. A certain relationship between the concentrations of fucoxanthin, total lipids and polyunsaturated fatty acids (PUFA) in the biomass of C. сlosterium diatom was recorded. During active growth in the exponential phase, the concentration of fucoxanthin was 0.5–1 mg∙g-1 dry weight. During the tranition of the culture to the stationary phase of growth, the concentration of fucoxanthin reached 7±0.2 mg∙g-1 dry biomass. At the end of the stationary phase, the concentration of fucoxanthin reached its maximum value of 20 mg∙g-1 dry weight.