In this Communication, we illustrate the influence of organic ligands on magnetic structure and behavior by employing a mixed-valence Lindqvist-type hexavanadate as a research platform. Through ...covalently attaching to different halogen-containing organic ligands, the derived hybrid materials have different magnetism compared to their parent structure. Single-crystal X-ray analyses show that the introduction of organic ligands can modify the crystal packing manners of the derivatives, leading to further changes of the interaction between magnetic units. This work demonstrates that organic functionalization can remarkably affect the magnetism of polyoxometalates by adjusting the distance and location of the magnetic fractions.
A rhodophyte Gracilariopsis lemaneiformis is widely cultivated for food, carbon sequestration and bioproducts, and commonly experiences changing irradiance levels and nitrogen sources that might ...influence the productivity and biochemical composition of the alga. To explore optimal culture conditions or manipulations to gain best yield of carbohydrates and amino acids of G. lemaneiformis during mariculture, we cultured G. lemaneiformis in four conditions including high irradiance and low irradiance coupled with nitrate and ammonium (denoted as HI-NO3−, LI-NO3−, HI-NH4+ and LI-NH4+). The results showed that irradiance, nitrogen source and their interactions significantly regulated the intracellular carbon and nitrogen metabolism of G. lemaneiformis and the influence of irradiance was greater than of nitrogen source. High irradiance promoted more carbon accumulation of G. lemaneiformis, which was confirmed by higher growth rate, net photosynthesis rates and contents of soluble carbohydrate, carbon and C/N ratios. In contrast, low irradiance is conductive to nitrogen accumulation, as revealed by high contents of nitrogen, phycoerythrin, soluble protein and amino acids. Furthermore, we found nitrate coupled with high irradiance significantly promoted carbon sequestration of G. lemaneiformis, and the ammonium combined with low irradiance significantly promoted nitrogen assimilation and transformation. In addition, arginine exhibited a higher nitrogen storage capacity than phycoerythrin, as evidenced by the higher content of arginine and correspondingly higher nitrogen reserves in G. lemaneiformis under low light coupled with ammonium and nitrogen- enriched environments. Moreover, the content of proline was higher under low irradiance conditions, but its proportion among the eighteen free amino acids was upregulated by high irradiance, indicating its important role in responding to high-light aquaculture environments. These findings demonstrate that irradiance and nitrogen source influence the carbon and nitrogen reallocation of G. lemaneiformis and that the combination of these two variables can induce the production of chemical products for biotechnological, aquaculture, and nutraceutical industry.
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•High irradiance enhanced carbon accumulation while low irradiance increases nitrogen accumulation in G. lemaneiformis.•High irradiance coupled with nitrate promoted carbon sequestration of G. lemaneiformis.•Arginine stored more nitrogen than phycoerythrin especially in nitrogen-rich conditions.
Red algae Pterocladiella capillacea off the coast of China were investigated for genetic diversity. With 176 samples categorized into six populations based on concatenated rbcL and cox1 sequences, ...the results rang warning bells for the genetic diversity of Pterocladiella capillacea along the Chinese coastline: (1) a good diversity of haplotype (Hd > 0.5) in Naozhou and Hui’an populations situated along the southern coast of China, but highest in the former; (2) less nucleotide diversity in each of the six populations (Pi < 0.005); (3) genetic differentiation occurred between the north population in Changdao and the two southern grown populations in Nan’ao, and Naozhou. To identify molecular markers, an MP phylogenetic tree was used to illustrate genetic profiles in detail, with 161 concatenated sequences clustered into four branches: Changdao (north), Nan’ao (south), Naozhou (south), and the remaining regions (middle). The Fst value for each of Changdao, Nan’ao, and Naozhou was greater than 0.5, which denotes that these three populations are genetically different to those growing in the middle coast. Moreover, a 30-haplotype-based median-joining network corroborated this genetic differentiation, though variations between all the investigated populations were not very high due to the relatively smaller values of genetic distance between the six (Dxy < 0.01). Overall, red algae P. capillacea in Chinese coastal seawater showed a higher haplotype diversity and lower nucleotide diversity. Such a genetic profile indicates that both natural random genetic drift and interference from human activities have possibly affected the distribution of gene frequencies in red algae P. capillacea along the Chinese coastline.
Metabarcoding analysis is an effective technique for monitoring the domoic acid-producing Pseudo-nitzschia species in marine environments, uncovering high-levels of molecular diversity. However, such ...efforts may result in the overinterpretation of Pseudo-nitzschia species diversity, as molecular diversity not only encompasses interspecies and intraspecies diversities but also exhibits extensive intragenomic variations (IGVs). In this study, we analyzed the V4 region of the 18S rDNA of 30 strains of Pseudo-nitzschia multistriata collected from the coasts of China. The results showed that each P. multistriata strain harbored about a hundred of unique 18S rDNA V4 sequence varieties, of which each represented by a unique amplicon sequence variant (ASV). This study demonstrated the extensive degree of IGVs in P. multistriata strains, suggesting that IGVs may also present in other Pseudo-nitzschia species and other phytoplankton species. Understanding the scope and levels of IGVs is crucial for accurately interpreting the results of metabarcoding analysis.
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•Molecular diversity consists of genetic diversity and intragenomic variation (IGV).•High levels of IGVs found in P. multistriata through high-throughput sequencing•Molecular diversity found in metabarcoding is dominated by IGVs in P. multistriata.•Genetic diversity may be overestimated in metabarcoding analysis.
Seaweed farming has been proposed as a strategy for adaptation to ocean acidification, but evidence is largely lacking. Changes of pH and carbon system parameters in surface waters of three seaweed ...farms along a latitudinal range in China were compared, on the weeks preceding harvesting, with those of the surrounding seawaters. Results confirmed that seaweed farming is efficient in buffering acidification, with Saccharina japonica showing the highest capacity of 0.10 pH increase within the aquaculture area, followed by Gracilariopsis lemaneiformis (ΔpH = 0.04) and Porphyra haitanensis (ΔpH = 0.03). The ranges of pH variability within seaweed farms spanned 0.14–0.30 unit during the monitoring, showing intense fluctuations which may also help marine organisms adapt to enhanced pH temporal variations in the future ocean. Deficit in pCO2 in waters in seaweed farms relative to control waters averaged 58.7 ± 15.9 μatm, ranging from 27.3 to 113.9 μatm across farms. However, ΔpH did not significantly differ between day and night. Dissolved oxygen and Ωarag were also elevated in surface waters at all seaweed farms, which are benefit for the survival of calcifying organisms. Seaweed farming, which unlike natural seaweed forests, is scalable and is not dependent on suitable substrate or light availability, could serve as a low-cost adaptation strategy to ocean acidification and deoxygenation and provide important refugia from ocean acidification.
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•Seaweed farms were efficient in buffering acidification locally.•Laminaria japonica showed the highest capacity of 0.10 pH increase within aquaculture area.•Deficit in pCO2 in waters in seaweed farms averaged 58.7 ± 15.9 μatm.•Dissolved oxygen and Ωarag were also elevated.
Black corals (BC) have been used for a long time in Chinese medicine, and may have some pharmaceutical functions when used as material for cigarette holders in southeast China. This study is aimed to ...investigate the bioactivities of volatile constituents in BC and to explore the folklore behind the use of BC cigarette holders (BCCHs). We extracted the volatile constituents of BC by supercritical fluid extraction (SFE) with carbon dioxide (CO₂-SFE), then identified and analyzed the constituents by gas chromatography-mass spectrometry (GC-MS). In total, 15 components were reliably identified in BC and found to be biologically active. These included triethyl phosphate, butylated hydroxytoluene, cedrol, n-hexadecanoic acid, squalene, and cholesterol. Meanwhile 13 inorganic elements (P, Ca, Mg, S, B, Si, Fe, Cu, Zn, Ba, etc.) were determined by inductively coupled plasma spectrometer (ICPS). In the bioactivity tests, the BC extract (BCE) showed a scavenging activity of 2,2-diphenyl-1-picrylhydrazyl free radicals and hydroxyl radicals by phenanthroline-Fe (II) oxidation and moderate inhibition of Gram-positive microorganisms. The antioxidant and antimicrobial activities of BC, which are related to the active chemical composition, may explain the perceived benefit for cigarette smokers who use BCCHs.
Gracilariopsis lemaneiformis (Gracilariales, Rhodophyta) is an important economic seaweed in Southern China. Its use as an alternative source of bioenergy, novel source of bioactives and possible ...carbon sink has been investigated. The common economic driver of these applications is biomass productivity, which requires an understanding of the effects of different cultivation densities (mat density; 4, 8 and 12 g per cluster) for offshore ‘floating raft’ cultivation to maximise productivities. In the present study, the relative growth rate (RGR) and irradiance-saturated maximum photosynthetic rates (Pmax) of thalli of G. lemaneiformis grown at high stocking density were lower than those of the algae grown at low stocking density. In three weather types (cloudy, overcast to clear and sunny conditions), the net photosynthetic rates (Pn) of the thalli grown at high stocking density were lower than those of the thalli cultivated at low density. The canopy Pn and increased algal gross biomass of the low-density algal mat were lower than those of the high-density algal mat. The increased canopy Pn of G. lemaneiformis in the high-density algal mat decreased under cloudy conditions. We suggest that efforts should be devoted to achieving an appropriate stocking density to obtain a relatively high growth rate, photosynthetic productivity and gross biomass accumulation during G. lemaneiformis maricultivation.
•Gracilariopsis lemaneiformis cultured at high stocking density lowered relative growth rate and photosynthetic rates;•The canopy net photosynthetic rates and increased algal gross biomass of the low density algae were decreased;•G. lemaneiformis thalli photosynthesis intensity could not fully reflect the photosynthetic capacity of the algal mat and growth.
•Three homogeneous polysaccharides were purified from G. livida.•The chemical characterizations of purified polysaccharides (designated as GLP-1, GLP-2, GLP-3) were performed by HPGPC, GC–MS, FT-IR ...and SEM.•Anticoagulant and antioxidant activities in vitroof sulfated polysaccharides from G. livida were studied and compared.
Purification, preliminary characterization and bioactivity of polysaccharides from Grateloupia livida (GL) were investigated. Three water-soluble sulfated polysaccharide fractions (GLP-1, GLP-2 and GLP-3) were isolated and purified from the edible and medicinal red seaweed, Grateloupia livida (Harv.) Yamada by DEAE Sepharose CL–6B and Sephadex G-100 column chromatography, and chemical characterization was performed by HPGPC, GC–MS, FT-IR and SEM. In addition, anticoagulant activities were determined by activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) using normal human plasma in vitro. The antioxidant activities against DPPH and ABTS+ radicals were evaluated and compared. The molecular weights of GLP-1, GLP-2 and GLP-3 were 39.5, 60.4 and 3.36kDa, respectively. Monosaccharide analysis revealed that three polysaccharide fractions were homopolysaccharides and comprised of galactose only. Anticoagulant assays indicated that crude GLP, and purified GLP-1 and GLP-2 effectively prolonged APTT and TT, but not PT. All polysaccharide fractions exhibited significant in vitro antioxidant activities in a dose-dependent manner. GLP-2 showed consistently better anticoagulant and antioxidant activities compared with GLP, GLP-1 and GLP-3. These results demonstrate that sulfated polysaccharides isolated from Grateloupia livida can serve as readily available alternative natural sources of anticoagulant and antioxidant agents.
Urease-producing bacteria (UPB) provide inorganic nitrogen for primary producers by hydrolyzing urea, and play an important role in marine nitrogen cycle. However, there is still an incomplete ...understanding of UPB and their ecological functions in the cultivation environment of the red macroalgae
Gracilariopsis lemaneiformis
. This study comprehensively analyzed the diversity of culturable UPB and explored their effects on urea uptake by
G. lemaneiformis
. A total of 34 isolates belonging to four main bacterial phyla i.e. (Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria) were identified through 16S rRNA sequencing and were screened for UPB by urea agar chromogenic medium assay and
ureC
gene cloning. Our data revealed that only 8 strains contained urease. All of these UPB exhibited different urease activities, which were determined by the Berthelot reaction colorimetry assay. Additionally, the UPB strain (G13) isolated from
G. lemaneiformis
with higher urease activity was selected for co-culture with
G. lemaneiformis
to explore its role in promoting or inhibiting nitrogen uptake by macroalgae. The results showed a significant increase in urea consumption in the culture medium and the total cellular nitrogen in
G. lemaneiformis
in the UPB-co culture group compared to the sterile group. This suggests that the selected UPB strain positively influences nitrogen uptake by
G. lemaneiformis.
Similarly, isotopic assays revealed that the δ
15
N content of
G. lemaneiformis
was significantly higher in the UPB-co culture than in the control group, where δ
15
N-urea was the only nitrogen source in the culture medium. This indicates that the UPB helped
G. lemaneiformis
to absorb more nitrogen from urea. Moreover, the highest content of δ
15
N was found in
G. lemaneiformis
with epiphytic bacteria compared to sterilized (i.e. control), showing that epiphytic bacteria, along with UPB, have a compound effect in helping
G. lemaneiformis
absorb more nitrogen from urea. Taken together, these results provide unique insight into the ecological role of UPB and suggest that urease from macroalgae environment-associated bacteria might be an important player in marine nitrogen cycling.
Sargassum hemiphyllum
and
Sargassum fusiforme
are important benthic seaweeds that grow along the southeastern coast of China. The content of carotenoids in each population was detected by ultra-high ...performance liquid chromatography (UHPLC). The research results will enrich the theoretical basis and data support concerning the influencing factors of carotenoids in
Sargassum
. The inter-simple sequence repeat (ISSR) technique was used to study the genetic diversity of four
S. hemiphyllum
and two
S. fusiforme
populations, and the results provide a reference for the artificial cultivation of
Sargassum
. The total carotenoid content of
Sargassum
ranged from 161.79 ± 4.22 to 269.47 ± 6.15 μg/g. Among the carotenoids, β-carotene and fucoxanthin accounted for 80%, and levels in
S. hemiphyllum
were generally higher than those in
S. fusiforme
. The carotenoid contents of
S. hemiphyllum
from different areas were significantly different (
P
< 0.05), and the total carotenoids content decreased toward the southern region. The average heterozygosity
H
ranged from 0.29 to 0.49, and the Shannon diversity index
I
ranged from 0.44 to 0.69. The polymorphic loci, genetic diversity, and other indicators of
S. hemiphyllum
populations were higher than those of
S. fusiforme
, and the diversity of cultivated populations was not significantly lower. The results showed that the genetic variation of
Sargassum
is limited, and thus, more sexual reproduction can be attempted in breeding. Considering morphological indicators, genetic diversity indexes, and carotenoid content,
S. hemiphyllum
appears to have a higher commercial development value.
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