Red Alga Gracilaria Lemaneiformis Research Articles

Several natural products isolated from a red alga Gracilaria lemaneiformis and its evaluation of antialgal activity against six common red tide microalgae.

The ethanol extracts of Gracilaria lemaneiformis that have inhibitory effects on Karenia mikimotoi and Skeletonema costatum were separated by liquid-liquid extraction using different polar solvents into five fractions with antialgal activities (petroleum ether, chloroform, ethyl acetate, n-butanol, and water-soluble fractions). These fractions were chromatographed on silica gel to give, after repeated preparative thin-layer chromatography (PTLC) purification processes, 1-β-D-ribofuranosyluracil (1), 3-hydroxymethyl-pyrrolopiperazine-2,5-dione (2), benzene-1,2-propanoic acid (3), 1-O-palmitoyl-2-O-palmitoleoyl-3-O-β-D-galactopyranosyl glycerol (4), 7-oxabicyclo[4.1.0]-heptan-3-ol (5), linoleic acid (6), 3,4-dimethoxy-6-(methoxymethyl)-tetrahydro-2H-pyran-2,5-diol (7), and 3,7,11,16-tetramethyl -2-heptadecen-1-ol (8). Five of them, natural products 1, 2, 5, 7, and 8, were isolated from Gracilaria lemaneiformis for the first time, and three natural products (3, 5, and 8) were isolated from marine macroalgae for the first time. Among them, natural products (1, 2, 3, 4, and 6) showed the most obvious inhibition activities to the growth of Karenia mikimotoi and Skeletonema costatum at the concentration of 80 μg/mL. Therefore, antialgal activities of these five natural products against Amphidinium carterae, Heterosigma akashiwo, Karenia mikimotoi, Phaeocystis globosa, Prorocentrum donghaiense, and Skeletonema costatum were further tested at different concentrations (0.4, 2, 10, and 50 μg/mL). This was the first report of antialgal activities of five natural products (1, 2, 3, 4, and 6) to these six red tide microalgae. They showed significantly selective antialgal activities against all tested red tide microalgae. At the concentration of 50 μg/mL, the growth of Amphidinium carterae, Heterosigma akashiwo, Karenia mikimotoi, and Phaeocystis globosa was obviously inhibited; for Karenia mikimotoi, natural products 1, 2, and 6 have significant antialgal activities; the growth inhibition of Skeletonema costatum that was exposed to natural products 1, 3, and 4 was remarkable. Furthermore, by analyzing and comparing EC50-96 h values, it has been determined that natural product 3 (natural product 4) showed the superior application potential than potassium dichromate and some reported natural products (such as gossonorol isolated from Porphyra yezoensis, trehalose purified from Ulva pertusa) as a characteristic antialgal agent against Amphidinium carterae (Phaeocystis globosa). In addition, natural products 1 and 3 also showed good superiority than some reported natural products in inhibiting Skeletonema costatum; however, it was a pity that they were inferior to potassium dichromate in the inhibiting this red tide microalgae. Taken together, it is not hard to conclude that Gracilaria lemaneiformis was a good source of natural products with antialgal activities against some red tide microalgae.

Effects of different levels of macroalga Gracilaria lemaneiformis on growth performance and feed utilization on the red sea bream, Pagrosomus major

In the present study, diets prepared to contain 0% (D0), 3% (D3), 6% (D6), 9% (D9), 12% (D12), and 15% (D15) of the red alga Gracilaria lemaneiformis were used to investigate the effects of G. lemaneiformis on the growth, carcass composition, and activities of enzymes related to nutritional metabolism of juvenile red sea bream (Pagrosomus major). The weight gain (WG), specific growth rate (SGR), apparent digestibility coefficients (ADC), feed efficiency (FE), protein efficiency ratio (PER), and protein retention (PR) were significantly higher in D3 than in the other treatment groups (P 0.05) were significantly reduced. Compared to the D0, hepatic glycogen and serum aspartate aminotransferase (AST) activity in the liver as well as serum total cholesterol (TC) of the fish on D3 and D6 were significantly higher (P < 0.05). Significantly higher activity of lipoprotein lipase (LPL) in the abdominal adipose tissues of fish fed on D3 was also observed (P < 0.05). The activities of lipase in anterior intestines appear decreased when the G. lemaneiformis supplementation level was over 12%. These results indicate that incorporate 3% G. lemaneiformis in diet could improve the growth performance and feed utilization of juvenile red sea bream. Incorporation of G. lemaneiformis at 15% level in the diet was also feasible for juvenile red sea bream, as it had no influence on growth performance.

Purification of R-phycoerythrin from Gracilaria lemaneiformis by centrifugal precipitation chromatography

Centrifugal precipitation chromatography (CpC) is a powerful chromatographic technique invented in the year 2000 but so far very little applied. The method combines dialysis, counter-current and salting out processes. The separation rotor consists of two identical spiral channels separated by a dialysis membrane (6–8 K MW cut-off) in which the upper channel is eluted with an ammonium sulfate gradient and the lower channel with water, and the mixtures are separated according to their solubility in ammonium sulfate as a chromatographic technique. In the present study, the method was successfully applied for separation and purification of R-phycoerythrin (R-PE), a protein widely used as a fluorescent probe, from the red alga Gracilaria lemaneiformis. The separation was performed with the elution of ammonium sulfate from 50% to 0% in 21.5 h at a flow rate of 0.5 ml/min, while the lower channel was eluted with water at a flow rate of 0.05 ml/min after sample charge, and the column was rotated at 200 rpm. After a single run, the absorbance ratio A565/A280 (a criterion for the purity of R-PE) was increased from 0.5 of the crude to 6.5. The purified R-PE exhibited a typical “three peaks” spectrum with absorbance maximum at 497, 538 and 565 nm. The Native-PAGE showed one single protein band and 20 kDa (subunits α and β) and 30 kDa (subunit γ) can be observed in SDS-PAGE analysis which were consistent with the (αβ)6γ subunit composition of R-PE. The results indicated that CpC is an efficient method to obtain protein with the high purity from a complex source.

Utilization of different macroalgae by abalone Haliotis discus hannai Ino: Evidence from analyses of fatty acid profiles

The use of different algal species by the abalone Haliotis discus hannai was investigated by using fatty acids (FAs) as trophic markers. Each of six groups of abalones was fed a different diet consisting of powdered algae over an 84-day period. Of the six diets, three consisted of a single algal species, i.e., the brown alga Laminaria japonica (L), the green alga Ulva lactuca (U), and the red alga Gracilaria lemaneiformis (G). The remaining three diets had different 1:1 mixtures of the algal species, i.e., L. japonica and U. lactuca (LU), L. japonica and G. lemaneiformis (LG), and U. lactuca and G. lemaneiformis (UG). The FA profiles of the abalone soft body showed clear changes over the experimental period and differed significantly between the different diet groups. Analyses of variation of specific FAs and multidimensional scaling ordination of overall FA profiles showed that H. discus hannai absorbed L. japonica preferentially over G. lemaneiformis in the dietary group LG and discriminated against U. lactuca in groups LU and UG. Additionally, abalone in group LG had the highest specific growth rate (SGR = 0.73 ± 0.06% d−1), while those in group U had the lowest (0.36 ± 0.07% d−1). Our results for dietary preferences and growth performance suggest that G. lemaneiformis might be used as an alternative to the kelp L. japonica in the diet of farmed H. discus hannai, while U. lactuca may not be suitable.

Evaluation of the red alga Gracilaria lemaneiformis and brown alga Sargassum horneri as ingredients in diets for white spotted snapper Lutjanus stellatus Akazaki juveniles

This study evaluated the red alga Gracilaria lemaneiformis and brown alga Sargassum horneri as ingredients to partially replace fishmeal in diets for white spotted snapper Lutjanus stellatus Akazaki (initial mass 12.0 ± 0.1 g). Nine test diets containing 0 (control), 5, 10, 15, and 20% G. lemaneiformis or S. horneri were prepared; each diet was assigned to triplicate groups of fish in a total of 27 floating sea cages (each cage contained 30 fish). After a 60-day feeding trail, significantly lower final body weight, weight gain, and specific growth ratio were found in fish fed 20% G. lemaneiformis diet (P < 0.05), whereas the poorest fish growth performance was obtained with the 20% S. horneri diet. Lipid content in muscle of fish fed 20% G. lemaneiformis diet was significantly lower than that of other groups (P < 0.05); however, body protein was higher than that in other groups. The lowest lipid and moisture contents in muscle were recorded in fish fed 5 and 15% S. horneri diets, and protein content in whole body of fish fed 20% S. horneri diet was significantly lower than that of control and 5% diets (P < 0.05). Activities of pepsin in the stomach and lipase and amylase in the intestine were significantly suppressed in fish fed 20% G. lemaneiformis diet compared with that of control (P < 0.05). The lowest pepsin activity in stomach and lipase activity in intestine were observed in fish fed 20% S. horneri diet. Based on a quadratic regression model of weight gain, the results suggested that the maximum incorporation of G. lemaneiformis and S. horneri in diets should be 16.44 and 15%, respectively, for juvenile white spotted snapper.

Bioremediation using Gracilaria lemaneiformis to manage the nitrogen and phosphorous balance in an integrated multi-trophic aquaculture system in Yantian Bay, China

To reduce negative environmental impacts from human aquaculture activities, the red alga Gracilaria lemaneiformis was co-cultured with the fish Pseudosciaena crocea in an integrated multi-trophic aquaculture (IMTA) system for 35d in Yantian Bay. The eutrophication index value decreased from 14.5 to 8.4 after seaweeds were co-cultured in cage farming areas, which indicated that the eutrophic water column in Yantian Bay could be mediated by IMTA. Total DIN and DIP of the tidal input and output were 9.23kg, 0.19kg and 11.08kg, and 0.27kg, respectively. Total 5.24kg of dissolved N and 0.81kg of dissolved P were released from IMTA system. These results indicate that G. lemaneiformis co-cultured in IMTA system could not completely remove all excess nutrients. In theory, at least 324.48kg of seaweed seedlings would be required to balance excess nutrients generated from fish cages.

A nanocomposite film fabricated with simultaneously extracted protein-polysaccharide from a marine alga and TiO2nanoparticles

This paper describes an edible nanocomposite packaging film fabricated with simultaneously extracted protein-polysaccharide (biopolymers) from the marine red alga Gracilaria lemaneiformis and TiO2 nanoparticles. Both proteins and polysaccharides were synchronously extracted using the alkali extraction method. Different amounts of TiO2 nanoparticles (TiO2 to biopolymer content ratio of 3.33, 5.00 and 10.0% w/w) were added to prepare the TiO2-protein/polysaccharide nanocomposite film. The addition of TiO2 nanoparticles increased the tensile strength and decreased the water vapor permeability of the film. This was because the uniformly embedded TiO2 nanoparticles interacted strongly with the biopolymers which enhanced the mechanical properties of the film, whereas the particles increased the diffusion pathway distance and lead to lower water permeability. These hypotheses were confirmed by UV spectra, FTIR, and X-ray diffraction studies. Antibacterial measurements against food-borne pathogenic bacteria revealed that the growth of Escherichia coli and Staphylococcus aureus was effectively inhibited by the TiO2-biopolymer nanocomposite film. Additionally, nutrition retention and quality improvement were observed in cherry tomatoes when coated with the TiO2-biopolymer nanocomposite film. These findings suggested that this alga-sourced nanocomposite film could serve as a promising coating material in the food industry.

Isolation and purification of antialgal compounds from the red alga Gracilaria lemaneiformis for activity against common harmful red tide microalgae

Seven antialgal compounds (1-7) were successfully isolated from the red alga Gracilaria lemaneiformis through a combination of silica gel column chromatography and repeated preparative thin-layer chromatography. On the basis of the spectral data, the compounds were identified as gossonorol (1), 7,10-epoxy-ar-bisabol-11-ol (2), glycerol monopalmitate (3), stigmasterol (4), 15-hydroxymethyl-2, 6, 10, 18, 22, 26, 30-heptamethyl-14-methylene-17-hentriacontene (5), 4-hydroxyphenethyl alcohol (6), and margaric acid (7). These seven compounds were isolated from G. lemaneiformis for the first time, while the compounds 4, 6, and 7 were isolated from marine macroalgae for the first time. Furthermore, a quantitative relationship between the inhibition of algal growth and the concentration of each antialgal compound was determined and important parameters for future practical HAB control, e.g., EC50-96h, were also obtained. The results indicated that isolated compounds 1-7 possess selective antialgal activity against the growth of several red tide microalgae (including Amphidinium carterae, Heterosigma akashiwo, Karenia mikimitoi, Phaeocystis globsa, Prorocentrum donghaiense, and Skeletonema costatum). Their antialgal activity against test red tide microalgae has not been previously reported. Furthermore, the EC50-96h of one or more of the compounds towards the tested red microalgae was not only significantly less than 10μg/mL but also was smaller than that of the characteristic antialgal agent potassium dichromate. The study demonstrates that compounds 1-7 possess significant application potential as antialgal agents against several harmful red tide microalgae.

Utilization of different macroalgae by sea cucumber Apostichopus japonicus revealed by carbon stable isotope analysis

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 8:171-178 (2016) - DOI: https://doi.org/10.3354/aei00173 Utilization of different macroalgae by sea cucumber Apostichopus japonicus revealed by carbon stable isotope analysis Bin Wen1,2, Qin-Feng Gao1,2,*, Shuang-Lin Dong1,2, Yi-Ran Hou1,2, Hai-Bo Yu1,2 1Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, Qingdao, Shandong Province 266003, PR China 2Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province 266003, PR China *Corresponding author: qfgao@ouc.edu.cn ABSTRACT: Understanding the feeding habit of sea cucumber Apostichopus japonicus (Selenka) is crucial for improving aquaculture techniques of this commercially important species. In the present study, carbon stable isotopes were used as trophic tracers to investigate the uptake of different macroalgae, including brown alga Sargassum muticum, red alga Gracilaria lemaneiformis and green alga Ulva lactuca by A. japonicus. A 70 d experiment was conducted to examine the carbon isotopic signatures of A. japonicus feeding on 6 different types of diets containing either pure powder of a single alga species or mixtures of 2 algae species. After the feeding trial, carbon isotope ratios (δ13C) of A. japonicus showed significant changes and reflected the isotopic compositions of corresponding diets. An isotope mixing model revealed the dietary preferences of A. japonicus between the 3 species of macroalgae, suggesting that green alga U. lactuca was the preferentially utilized food source of A. japonicus, followed by brown alga S. muticum. A. japonicus tended to reject red alga G. lemaneiformis in the presence of multiple macroalgae choices. Moreover, the specific growth rates of A. japonicus fed on S. muticum and U. lactuca were similar, but were both significantly higher than those fed on G. lemaneiformis, indicating the direct link between the feeding preferences and growth performance of A. japonicus. KEY WORDS: Apostichopus japonicus · Macroalga · Stable isotope · Growth Full text in pdf format PreviousNextCite this article as: Wen B, Gao QF, Dong SL, Hou YR, Yu HB (2016) Utilization of different macroalgae by sea cucumber Apostichopus japonicus revealed by carbon stable isotope analysis. Aquacult Environ Interact 8:171-178. https://doi.org/10.3354/aei00173 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 8. Online publication date: March 30, 2016 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2016 Inter-Research.

Effects of dietary inclusion of benthic matter on feed utilization, digestive and immune enzyme activities of sea cucumber Apostichopus japonicus (Selenka)

A 70-day feeding experiment was conducted to examine the effects of dietary inclusion of benthic matter, which was mainly composed of microalgae, bacteria and clay particles, on the feed utilization, digestive and immune enzyme activities of sea cucumber Apostichopus japonicus. Sea cucumbers were fed with 6 types of diets with the ingredient of either single algae species or mixture of algae and benthic matter, i.e., single brown alga Sargassum muticum, red alga Gracilaria lemaneiformis, green alga Ulva lactuca, mixtures (1:1) of S. muticum and benthic matter, G. lemaneiformis and benthic matter and U. lactuca and benthic matter. After the feeding trial, the feed utilization efficiency, digestive and immune enzyme activities of A. japonicus were remarkably affected by different types of diets. The feed conversion ratio of A. japonicus fed the single G. lemaneiformis was significantly higher than those fed with single S. muticum and those fed on G. lemaneiformis with benthic matter (ANOVA, p<0.05). While the protein efficiency ratios of A. japonicus fed the single algae diets were significantly lower relative to those fed on corresponding mixed diets (ANOVA, p<0.05). The trypsin activity of A. japonicus that fed the single G. lemaneiformis was not only significantly lower than those fed the single S. muticum and single U. lactuca but also significantly lower than those fed on G. lemaneiformis with benthic matter (ANOVA, p<0.05). The amylase and cellulase activities of A. japonicus that fed the single algae diets were significantly lower as compared to the corresponding mixed diet groups (ANOVA, p<0.05). Similarly, the superoxide dismutase and acid phosphatase activities of A. japonicus that fed the single algae diets were significantly lower relative to those fed on corresponding mixed diets (ANOVA, p<0.05). While the alkaline phosphatase activity of A. japonicus fed on G. lemaneiformis with benthic matter was not only significantly higher than those fed the G. lemaneiformis alone but also significantly higher than those fed on S. muticum with benthic matter and U. lactuca with benthic matter (ANOVA, p<0.05). The results of the present study suggested that dietary inclusion of benthic matter might have beneficial effects on the digestive processes, immune responses and growth performance of A. japonicus. Statement of relevanceThe results of the present study can provide the scientific suggestions for optimizing the feed ingredients for farming of sea cucumber A. japonicus.

Effects of different feed ingredients on growth, fatty acid profiles, lipid peroxidation and aminotransferases activities of sea cucumber Apostichopus japonicus (Selenka)

A 70-day experiment was conducted to examine the effects of different feed ingredients on the growth, fatty acid (FA) profiles, lipid peroxidation and aminotransferases activities of sea cucumber Apostichopus japonicus. Sea cucumbers were fed with 6 types of diets with the ingredient of either single algal powder or mixture of algal powder and benthic matter mainly composed of microalgae, bacteria and clay particles, i.e., single brown alga Sargassum muticum (S), red alga Gracilaria lemaneiformis (G), green alga Ulva lactuca (U), mixture (1:1) of S. muticum and benthic matter (SB), mixture (1:1) of G. lemaneiformis and benthic matter (GB) and mixture (1:1) of U. lactuca and benthic matter (UB). After the feeding trial, the specific growth rate (SGR) of A. japonicus in the group GB was significantly higher compared to those in the group G while no significant differences were observed between the SB and S groups or between the UB and U groups. The biochemical compositions and FA profiles in the body tissues of A. japonicus were remarkably affected by the corresponding diets. The crude protein content of A. japonicus in the group UB was significantly higher relative to those in the group U while there were no significant differences between the SB and S groups or between the GB and G groups. A. japonicus fed diets containing benthic matter showed similar or elevated concentrations of n−3 polyunsaturated fatty acids (PUFAs) including eicosapentaenoic acid (20:5n−3, EPA) and docosahexaenoic acid (22:6n−3, DHA) as compared to those cultured with corresponding single algae diets. Moreover, dietary benthic matter improved the antioxidant capacity of A. japonicus to some degree during refrigerated storage at 4°C, and significantly increased the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) except the AST activity of A. japonicus in the group UB. The results of the present study suggested that benthic matter might be used as a suitable substitute for the traditional macroalgae ingredients in A. japonicus feeds. Statement of relevanceThe results of the present experiment provided the scientific foundation for optimizing the ingredients of the artificial feed for the farming of sea cucumber A. japonicus.

Uptake of benthic matter by sea cucumber Apostichopus japonicus (Selenka): Insights from carbon stable isotopes and fatty acid profiles

Carbon stable isotopes combined with fatty acid (FA) profiles were used as trophic markers to investigate the uptake of different food sources, including brown alga Sargassum muticum, red alga Gracilaria lemaneiformis, green alga Ulva lactuca and benthic matter mainly consisted of microalgae, bacteria and fine clay particles by sea cucumber Apostichopus japonicus. A 70-day feeding experiment was conducted to examine the carbon isotopic signatures and FA profiles of A. japonicus feeding on 4 different types of diets with the ingredient of mixture of algal powder and benthic matter, i.e., mixture (1:1) of S. muticum and benthic matter (SB), mixture (1:1) of G. lemaneiformis and benthic matter (GB), mixture (1:1) of U. lactuca and benthic matter (UB) and mixture (1:1:1:1) of S. muticum, G. lemaneiformis, and U. lactuca and benthic matter (SGUB). The carbon isotope compositions and FA profiles of A. japonicus showed obvious changes over the experimental period and were remarkably affected by corresponding diets. Based on the isotope mixing model, the proportional contributions of benthic matter to the diet of A. japonicus fed with SB, GB, UB and SGUB were 35.58%, 67.01%, 31.98% and 17.40%, respectively. FA trophic markers revealed that the contribution of benthic matter was mainly derived from diatoms and bacteria. Results of the present study suggested that green alga U. lactuca and brown alga S. muticum constituted the highly preferred food sources of A. japonicus, followed by autotrophic diatoms and heterotrophic bacteria present in benthic matter. Sea cucumber A. japonicus tended to reject red alga G. lemaneiformis in the presence of multiple food choices.

Absorption of different macroalgae by sea cucumber Apostichopus japonicus (Selenka): Evidence from analyses of fatty acid profiles

Fatty acids (FAs) were used as trophic markers to examine the absorption of different algae species, including brown alga Sargassum muticum (S), red alga Gracilaria lemaneiformis (G) and green alga Ulva lactuca (U) by sea cucumber Apostichopus japonicus. A 56-day feeding experiment was carried out to investigate the FA profile of the A. japonicus feeding on 6 different types of diets with the ingredient of either pure powder of single algae species or mixtures of 3 algae species, i.e., the mixtures (1:1) of S. muticum and G. lemaneiformis (SG), S. muticum and U. lactuca (SU), and G. lemaneiformis and U. lactuca (GU). The FA profile of A. japonicus showed obvious changes over the experimental period and was remarkably affected by the different diets. Analyses of variations in the specific FAs and the multidimensional scaling (MDS) ordination of the overall FA profiles revealed that A. japonicus preferentially absorbed U. lactuca relative to S. muticum in the diet group SU while showed the discrimination against G. lemaneiformis in the diet groups SG and GU. Moreover, A. japonicus fed with U. lactuca displayed a similar or higher specific growth rate (SGR) than those fed on S. muticum or G. lemaneiformis, respectively. The results of the present study suggested that green alga U. lactuca might be used as a suitable substitute for replacing the traditional ingredient brown alga Sargassum thunbergii in the artificial feed for A. japonicus farming. Statement of relevanceThe results of the present study could be used to further optimize the ingredient of A. japonicus artificial feeds.

Cloning and transcription analysis of six members of the calmodulin family in Gracilaria lemaneiformis under heat shock

Calmodulin (CaM) is essential in plants for signal transduction under environmental stress. To determine the function of CaMs in the thermal response of the red alga Gracilaria lemaneiformis, six cams were cloned from three strains, wild type and heat-tolerant cultivar 981 and 07-2. In wild type, w-cam1, w-cam2, and w-cam3 were cloned; in cultivar 981, 981-cam1 and 981-cam2 were obtained; and in cultivar 07-2, only 072-cam1 was identified. The cam1s in the three strains were identical. They contain 832 nucleotides, including four exons and three introns. The ORFs of w-cam2 and 981-cam2 were the same length, having 450 nucleotides without introns, and they shared 78 % similarity in nucleotides and 87 % in amino acids. In addition, w-cam3, a gene of 809 nucleotides, consisting of three exons and two introns, was cloned from the genomic DNA of wild type. The transcription levels of the cams under heat shock were tested by real-time quantitative PCR, except for w-cam2 and w-cam3, because these two cams could not be amplified effectively by RT-qPCR. Among all the cam1s, 981-cam1 expressed more highly under heat shock. Though w-cam1 and 072-cam1 were down-regulated under heat, the suppression level of 072-cam1 was slightly less than the wild type. For 981-cam2, the expression level was lower than that of 981-cam1 at 28 °C, while at 32 °C, the two cams of 981 had similar expression profiles. These results indicate that the cams may play an important role in G. lemaneiformis and that cam1 responds the most to heat shock.

The metabolism of 8-heptadecene in Pyropia (Bangiaceae, Rhodophyta)

The metabolic pathway of 8-heptadecene in red algae was investigated. The results showed that the amounts of 8-heptadecene in the primitive bangiophycidean red algae Pyropia and Bangia were 30–50 % of the volatile compounds, much higher than that in the green alga Ulva pertusa, the brown alga Sargassum thunbergii and the florideophycidean red alga Gracilaria lemaneiformis. Studies on the metabolism of 8-heptadecene in Pyropia found that its enzymatic system has no significant catalytic activity on palmitic acid, oleic acid, linoleic acid, linolenic acid, and arachidonic acid. However, the isolated enzymatic solution showed activity in the presence of eicosapentaenoic acid. This activity produced about four times the amount of 8-heptadecene compared with other substrates and the control, indicating the solution had a specific catalytic function for eicosapentaenoic acid. Furthermore, the enzyme solution was strongly inhibited by NaN3 but not by phenidone and phenanthroline suggesting that the enzyme is structurally related to heme protein. Thus, it is believed that a constant amount of 8-heptadecene is maintained in the primitive red alga Pyropia and the 8-heptadecene is a metabolite of eicosapentaenoic acid and may catalyzed by enzymes including a heme lipoxygenase-like enzyme.

Combined effects of light and nitrate supplies on the growth, photosynthesis and ultraviolet‐absorbing compounds in marine macroalga Gracilaria lemaneiformis (Rhodophyta), with special reference to the effects of solar ultraviolet radiation

SummaryIt is well known that light and nutrients are essential to plants; however, there are few investigations in which these have been studied in combination on macroalgae, especially when solar ultraviolet radiation (UVR) is concerned. We cultured the red alga Gracilaria lemaneiformis (Bory) at different nitrate concentrations and light levels with or without UVR for 24 days. The results showed that nitrate supply markedly enhanced the growth and photosynthesis, increased the absorptivity of UV‐absorbing compounds (UVACs), and decreased photoinhibition in the presence of UVR. The thalli that received photosynthetically active radiation (PAR) treatment exhibited higher growth rates than those that received PAR + UVR at ambient or enhanced nitrate concentrations. However, under PAR + UVR treatment, the absorptivity of UVACs was higher than that of PAR and fluctuated with light levels. UVR was found to reduce the maximal net photosynthetic rate, apparent photosynthetic efficiency and light‐saturating irradiance while increasing the dark respiration rate, and inducing higher inhibition of growth and photosynthesis under high light versus under low light. Ultraviolet B significantly induced the synthesis of UVACs but led to higher inhibition on growth and photosynthesis than ultraviolet A.

Molecular cloning and expression analysis of glutathione peroxidase and glutathione reductase from Gracilaria lemaneiformis under heat stress

Glutathione peroxidase (GPx) and glutathione reductase (GR) are key enzymes in the antioxidant defense systems of living organisms and protect organisms from environmental stresses. To investigate the mechanism of resistance to heat stress in the red alga Gracilaria lemaneiformis, the cDNA sequences encoding glutathione peroxidase and glutathione reductase of two strains (wild type and heat-tolerant cultivar 981) of G. lemaneiformis were successfully cloned using reverse transcription PCR and rapid amplification cDNA ends techniques. cDNA encoding GPx has 930 nucleotides with an open reading frame (ORF) of 750 nucleotides, encoding 249 amino acid residues. cDNA encoding GR was 1,572 nucleotides with a 1,416-nucleotide ORF encoding 471 amino acids. No introns existed in genomic DNA of GPx and GR of G. lemaneiformis. Southern blotting indicated that there was only one copy of GPx and GR in both strains. Under heat stress, bioactivity and mRNA transcription levels of both GPx and GR were upregulated in cultivar 981 compared to those in the wild type. These results indicate that both GPx and GR may play important roles in the ability of G. lemaneiformis to resist high temperatures.

Carbon dioxide fixation by the seaweed Gracilaria lemaneiformis in integrated multi-trophic aquaculture with the scallop Chlamys farreri in Sanggou Bay, China

The red alga Gracilaria lemaneiformis was cultivated with the scallop Chlamys farreri in an integrated multi-trophic aquaculture (IMTA) system for 42 h at Sanggou Bay, located in north China. Variation in inorganic carbon in the IMTA system was determined. The experiment included three treatments each with three replicates and three scallop monoculture systems as controls. Scallop density (399.1 +/- A 7.85 g per microcosm) remained the same in all treatments while seaweed density differed. The seaweed density was set at three levels (treatments 1, 2, 3) with thallus wet weights of 125.3 +/- A 4.72 g, 252.3 +/- A 7.50 g, and 378.7 +/- A 6.51 g per microcosm, respectively. This produced bivalve to seaweed wet weight ratios of 1:0.31, 1:0.63, and 1:0.96 for treatments 1, 2, and 3, respectively. In control groups, continuous dissolution of carbon dioxide (CO2) produced by scallops into the seawater not only caused an ongoing increase in partial pressure of CO2 (pCO(2)), 5.5 times higher than that of natural seawater, but also acidified seawater by 0.8 units after 42 h of culture. However, in all seaweed-scallop groups, the higher the algal density, the more CO2 was absorbed; pCO(2) was lowest in treatment 3. The results suggest that a ratio of bivalve to seaweed less than 1:0.96 may produce an even stronger CO2 sink. Overall, the integrated culture of seaweed and scallop could provide an efficient and environmentally friendly means to reduce CO2 emissions from bivalve mariculture.

Use of UV‐A Energy for Photosynthesis in the Red Macroalga Gracilaria lemaneiformis

UV radiation is known to inhibit photosynthetically active radiation (PAR)-driven photosynthesis; however, moderate levels of UV-A have been shown to enhance photosynthesis and growth rates of some algae. Here, we have shown that UV-A alone could drive photosynthetic utilization of bicarbonate in the red alga Gracilaria lemaneiformis as evidenced in either O(2) evolution or carbon fixation as well as pH drift. Addition of UV-B inhibited the apparent photosynthetic efficiency, raised the photosynthetic compensation point and photosynthesis-saturating irradiance level, but did not significantly affect the maximal rate of photosynthetic O(2) evolution. The electron transport inhibitor, DCMU, inhibited the photosynthesis completely, reflecting that energy of UV-A was transferred in the same way as that of PAR. Inorganic carbon acquisition for photosynthesis under UV alone was inhibited by the inhibitors of carbonic anhydrase. The results provided the evidence that G. lemaneiformis can use UV-A efficiently to drive photosynthesis based on the utilization of bicarbonate, which could contribute significantly to the enhanced photosynthesis in the presence of UV-A observed under reduced levels of solar radiation.

Effects of elevated CO2 and phosphorus supply on growth, photosynthesis and nutrient uptake in the marine macroalga Gracilaria lemaneiformis (Rhodophyta)

Abstract The red alga Gracilaria lemaneiformis was cultured under different CO2 and phosphorus conditions for 16 days, and its growth, photosynthesis and uptake of nitrate and phosphate were examined in order to establish the longer-term impacts of elevated CO2 and phosphorus supplies on this economically important seaweed. Enrichment with either CO2 or phosphorus in culture markedly increased the growth of G. lemaneiformis compared to the control. Light-saturated photosynthetic rate was enhanced significantly by phosphorus enrichment, but hardly affected by the elevation of CO2 when G. lemaneiformis was grown under low phosphorus conditions. High phosphorus stimulated photosynthetic inorganic carbon utilization and nitrogen uptake. Under low phosphorus conditions, the thalli grown at the high level of CO2 had a lower carbon utilization capacity and a higher nitrogen uptake rate compared to those grown under ambient CO2. Reversed results were found when the algae were grown under high phosphorus conditions. Hence, available phosphorus may regulate inorganic carbon utilization of G. lemaneiformis grown at different CO2 levels, and growth reflected a balance between carbon and nutrient metabolism.