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1.
Ying Yong Sheng Tai Xue Bao ; 35(3): 622-630, 2024 Mar 18.
Article in English | MEDLINE | ID: mdl-38646749

ABSTRACT

Soil nitrogen and phosphorus are two key elements limiting tree growth in subtropical areas. Understanding the regulation of soil microorganisms on nitrogen and phosphorus nutrition is beneficial to reveal maintenance mechanism of soil fertility in plantations. We analyzed the characteristics of soil nitrogen and phosphorus fractions, soil microbial community composition and function, and their relationship across three stands of two-layered Cunninghumia lanceolata + Phoebe bournei with different ages (4, 7 and 11 a) and the pure C. lanceolata plantation. The results showed that the contents of most soil phosphorus fractions increased with increasing two-layered stand age. The increase in active phosphorus fractions with increasing stand age was dominated by the inorganic phosphorus (9.9%-159.0%), while the stable phosphorus was dominated by the organic phosphorus (7.1%-328.4%). The content of soil inorganic and organic nitrogen also increased with increasing two-layered stand age, with NH4+-N and acid hydrolyzed ammonium N contents showing the strongest enhancement, by 152.9% and 80.2%, respectively. With the increase of stand age, the composition and functional groups of bacterial and fungal communities were significantly different, and the relative abundance of some dominant microbial genera (such as Acidothermus, Saitozyma and Mortierella) increased. The relative abundance of phosphorus solubilization and mineralization function genes, nitrogen nitrification function and aerobic ammonia oxidation function genes tended to increase. The functional taxa of fungi explained 48.9% variation of different phosphorus fractions. The conversion of pure plantations to two-layered mixed plantation affected soil phosphorus fractions transformation via changing the functional groups of saprophytes (litter saprophytes and soil saprophytes). Changes in fungal community composition explained 45.0% variation of different nitrogen fractions. Some key genera (e.g., Saitozyma and Mortierella) play a key role in promoting soil nitrogen transformation and accumulation. Therefore, the conversion of pure C. lanceolata plantation to two-layered C. lanceolata + P. bournei plantation was conducive to improving soil nitrogen and phosphorus availability. Bacteria and fungi played important roles in the transformation process of soil nitrogen and phosphorus forms, with greater contribution of soil fungi.


Subject(s)
Nitrogen , Phosphorus , Soil Microbiology , Soil , Phosphorus/analysis , Nitrogen/analysis , Nitrogen/metabolism , Soil/chemistry , Cunninghamia/growth & development , China , Bacteria/classification , Bacteria/growth & development , Bacteria/metabolism
2.
J Hazard Mater ; 469: 134035, 2024 May 05.
Article in English | MEDLINE | ID: mdl-38490147

ABSTRACT

The trophodynamic of organophosphate esters (OPEs) has not been known well despite their widespread occurrence in the aquatic environments. In this study, ten species of crustacean, seven species of mollusk, and 22 species of fish were collected in the Laizhou Bay (LZB) to examine the occurrence, bioaccumulation, and trophic transfer, and health risk of eight traditional OPEs and three emerging oligomeric OPEs. The results showed that total concentration of OPEs was 2.04 to 28.6 ng g-1 ww in the muscle of crustacean, mollusk, and fish and 2.62 to 60.6 ng g-1 ww in the fish gill. Chlorinated OPEs averagely contributed to over 85% of total OPEs while oligomeric OPEs averagely accounted for approximate 4%. The average log apparent bioaccumulation factor (ABAF) ranged from - 0.4 L kg-1 ww for triethyl phosphate to 2.4 L kg-1 ww for resorcinol-bis (diphenyl) phosphate. Apparent trophic magnification factors (ATMF) of individual OPE were generally less than 1, demonstrating the biodilution effect of the OPEs in the organism web of LZB. Additionally, the log ABAF and ATMF of OPEs were significantly positively correlated to their log Kow but negatively correlated to their biotransformation rate constant (BRC). Therefore, the OPEs with high Kow and low BRC tend to more accumulate in the marine organisms. The health risks associated with OPEs through the consumption of the seafood from the bay were low, even at high exposure scenario.


Subject(s)
Water Pollutants, Chemical , Animals , Bays , Bioaccumulation , Biota , China , Environmental Monitoring/methods , Fishes/metabolism , Organophosphates/analysis , Water Pollutants, Chemical/analysis
3.
Science ; 381(6663): 1163, 2023 09 15.
Article in English | MEDLINE | ID: mdl-37708257
4.
Mar Pollut Bull ; 183: 114052, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35998525

ABSTRACT

In this study, surface seawater, bottom seawater and surface sediments were collected from the Yellow River Estuary Area (YREA) and the Laizhou Bay (LB) to investigate the occurrence, spatial distribution and geochemical control factors for total mercury (THg) and methylmercury (MeHg) in different phases. The geochemical characteristics of seawater and sediments suggested significant variances in the YREA and the LB. The high contamination of Hg in the YREA showed the discharge of the Yellow River (YR) contributed significantly to the Hg contamination in the LB. The partial least squares regression (PLSR) model was utilized to explore the complicated interactions between geochemical controls and methylation potentials in different phases. Although the ecological risk (ER) of Hg was not significant in this study area, the higher values of ER in the YREA suggested that the YR was the primary Hg contributor to LB. Therefore, the potential Hg risk should not be ignored.


Subject(s)
Mercury , Methylmercury Compounds , Water Pollutants, Chemical , Ecosystem , Environmental Monitoring , Estuaries , Geologic Sediments , Mercury/analysis , Methylmercury Compounds/analysis , Water Pollutants, Chemical/analysis
5.
Mitochondrial DNA B Resour ; 7(2): 348-349, 2022.
Article in English | MEDLINE | ID: mdl-35174286

ABSTRACT

The complete mitochondrial genome of Sydaphera spengleriana was characterized for the first time. The total length of the mitogenome was 16,336 bp including a standard set of 13 protein-coding (PCGs), 22 transfer RNA (tRNA), and 2 ribosomal RNA (rRNA) genes. The overall nucleotides base composition of the heavy strand is A (26.44%), G (19.89%), C (13.25%), and T (40.41%), with an A + T bias (66.85%). With the exception of eight tRNA genes, all other mitochondrial genes are encoded on the heavy strand. The mitogenomic phylogenetic relationships indicated that S. spengleriana was clustered with Bivetiella cancellata within the family Cancellariidae clade with a high bootstrap value.

6.
Environ Sci Pollut Res Int ; 29(18): 26922-26935, 2022 Apr.
Article in English | MEDLINE | ID: mdl-34860345

ABSTRACT

Herein, we conducted a study of the Zhangsanxi karst groundwater system in Zhangjiajie, Hunan Province, China, and used the results to develop a method for identifying the aquifer medium and its structural characteristics. To begin, rainfall, underground river flow dynamics, and groundwater level dynamics in the Zhangsanxi karst groundwater system were subjected to high-resolution monitoring to elucidate the groundwater system's rainfall-hydrological response characteristics under varying rainfall amounts and intensities. Next, an exponential attenuation curve was employed to analyze how the law of attenuation applies to underground river discharge and groundwater level during a typical rainfall event. Finally, we determined the degree of karst development at different depths, so the data can serve as a reference for local decision makers regarding karst water disaster prevention and water resource utilization. The results show that the flow response lag time in the karst groundwater system depicts good correlation with the rainfall amount but is also affected by the rainfall intensity. Thus, under conditions of identical rainfall, increasing rainfall intensity corresponds to a progressively shorter underground river flow lag time. The area's rainfall can be divided into four types, based on its concentration and intensity characteristics. The underground river flow generally has no evident response to type I rainfall, while the flow response lag time to types II III and IV rainfall is approximately 110, 60, and 40 h, respectively. Furthermore, the Zhangsanxi karst system's water-bearing medium is dominated by karst fissures and pores, which account for about 2/3 of its open space. Large karst conduits and caves account for the remaining 1/3. The degree of karst development in this system depicts evident depth variation but, overall, tends to increase as a function of burial depth.Responsible editor: Xianliang Yi.


Subject(s)
Groundwater , Rain , China , Environmental Monitoring/methods , Groundwater/chemistry , Hydrology , Water
7.
J Hazard Mater ; 424(Pt B): 127482, 2022 02 15.
Article in English | MEDLINE | ID: mdl-34655879

ABSTRACT

Heavy metal (HM) pollution in coastal ecosystems have posed threats to organisms and human worldwide. This study comprehensively investigated the concentrations, sources, trophodynamics, contamination, and risks of six HMs in the coastal ecosystem of Jiaozhou Bay, northern China, by stable isotope analysis, positive matrix factorization (PMF), and Monte Carlo simulation. Overall, Co, Cu, Ni, Pb, and Zn were significantly bio-diluted in the food web, while Cr was significantly biomagnified with a trophic magnification factor of 1.23. In addition, trophodynamics of the six HMs was different among fish, mollusk, and crustacean. Furthermore, detailed transfer pathways of six HMs in the food web including eight trophic levels were different from one another. Bioaccumulation order of the six HMs was Cu > Zn > Co, Cr, Ni, and Pb. Zinc concentrations were the highest in seawater, sediments, and organisms. Anthropogenic sources contributed to 71% for Zn, 31% for Cu and Pb, and 27% for Co, Cr, and Ni in the sediment, which was moderately contaminated with moderate ecological risk. However, the human health risk of HMs from eating seafood was relatively low. To protect the Jiaozhou Bay ecosystem, HM contamination should be further controlled in future.


Subject(s)
Metals, Heavy , Water Pollutants, Chemical , Animals , China , Ecosystem , Environmental Monitoring , Geologic Sediments , Humans , Metals, Heavy/analysis , Metals, Heavy/toxicity , Monte Carlo Method , Risk Assessment , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicity
8.
Mar Pollut Bull ; 171: 112781, 2021 Oct.
Article in English | MEDLINE | ID: mdl-34340146

ABSTRACT

To understand the current community structure and diversity of macrobenthos in Jiaozhou Bay, a survey was conducted at eight sampling stations in April, July, and October 2018, as well as January 2019. Eighty-two macrobenthos species were collected, including 30 of Annelida, 21 of Mollusca, 20 of Crustacea, 8 of Echinodermata, and 3 classified as "Others". Ruditapes philippinarum was a common dominant species in summer, autumn, and winter. The annual average abundance and biomass were 280 ind./m2 and 446.45 g/m2, respectively. Shannon-Wiener diversity varied from 0.09 to 2.45 with an average value of 1.14. Margalef richness was 0.17-2.32 with an average value of 0.89. Pielou evenness was 0.14-1.00 with an average value of 0.71. The seasonal variation patterns of all tested indices were largely the same, with the highest in spring, next highest in winter, and lower in summer and autumn. The diversity at different survey stations varies greatly.


Subject(s)
Bays , Bivalvia , Animals , China , Crustacea , Ecosystem , Seasons
9.
Article in English | MEDLINE | ID: mdl-34072196

ABSTRACT

It is a challenge to describe the hydrogeological characteristics of karst aquifers due to the complex structure with extremely high heterogeneity. As the response of karst aquifers to rainfall events, spring discharge variations after precipitation can be used to identify the internal structure of karst systems. In this study, responses of spring discharge to different kinds of precipitations are investigated by continuously monitoring precipitation and karst spring flow at a single-conduit karst aquifer in western Hunan province, China. Recession curves were used to analyze hydrodynamic behaviors and separate recession stages. The results show that the shape of the recession curve was changed under different rainfall conditions. Recession processes can be divided in to three recession stages under heavy rain conditions due to water drainage mainly from conduits, fracture, and matrix at each stage, but only one recession stage representing drainage mainly from matrix in the case of light rain. With the change in amount and intensity of precipitation, the calculated recession coefficient at each stage changes in an order of magnitude. The influence of precipitation on the recharge coefficient and the discharge composition at each recession are discussed, and then the conceptual model diagram of water filling and releasing in the single-conduit karst aquifers is concluded. The findings provide more insight understand on hydraulic behaviors of karst spring under different types of rainfall events and provide support for water resource management in karst regions.


Subject(s)
Groundwater , Water Movements , China , Models, Theoretical , Rain
10.
Chemosphere ; 281: 130836, 2021 Oct.
Article in English | MEDLINE | ID: mdl-33991905

ABSTRACT

In this study, 26 surface seawater samples, 26 surface sediment samples and 114 organisms were collected to study the trophic transfer and dietary exposure risk of mercury (Hg) in organisms from the Jiaozhou Bay, which is a typical semi-enclosed urbanized bay. The total mercury (THg) and methylmercury (MeHg) concentrations did not exceed the threshold limits and performed as: fish > crustaceans > mollusks. The trophic level values (TLs) were less than 3 in all the groups, indicating simple structure of food chain. With the increasing δ15N value, THg and MeHg were significantly biomagnified in the mollusks and fish but not in the crustaceans. In addition, the bioaccumulation and biomagnification of MeHg were higher than inorganic mercury (IHg) in the aquatic food chain. Target hazard quotient (THQ) and provisional tolerable weekly intake (PTWI) indicated that Hg exposure via consumption of seafood from the Jiaozhou Bay did not pose significant health risks for general population. Consuming fish will face the higher health risk than crustaceans and mollusks, especially in urban regions. Moreover, the risk of MeHg caused by intaking seafood deserved more attention. Trophic transfer function (TTF) explicated the transfer of Hg in the ecosystem and higher trophic transfer efficiency of MeHg than IHg. TTF interpreted the terrestrial input of Hg should be controlled to ensure the safety of consuming seafood from the Jiaozhou Bay.


Subject(s)
Mercury , Methylmercury Compounds , Water Pollutants, Chemical , Animals , Aquatic Organisms , Dietary Exposure , Ecosystem , Environmental Monitoring , Fishes , Food Chain , Humans , Mercury/analysis , Water Pollutants, Chemical/analysis
11.
Sci Total Environ ; 774: 145016, 2021 Jun 20.
Article in English | MEDLINE | ID: mdl-33607433

ABSTRACT

Million tons of cadmium (Cd) are annually discharged into China's coastal regions, creating a persistent hazard to marine organisms and human health. This study assessed Cd residues in the Yellow Sea's semi-enclosed Jiaozhou Bay (JZB), finding concentrations of 0.05-0.94 µg/L in seawater and 0.03-0.18 mg/kg in sediment. For marine organisms, mollusks had the highest Cd concentration (0.44 ± 0.09 mg/kg), followed by crustaceans (0.26 ± 0.08 mg/kg) and fish (0.10 ± 0.02 mg/kg). Cd was clearly accumulated by mollusks, with biota-sediment accumulation factor (BSAF) values >1 and biota-water accumulation factor (BWAF) values >1000. Stable nitrogen isotope (δ15N) analysis showed that Cd underwent biomagnification in mollusks, but was significantly bio-diluted with increasing trophic level among other marine organisms. In general, Cd contamination levels were low in the JZB's seawater and sediment, and fish was estimated to be certainly polluted due to strict safety limitations on seafood in China. Current Cd residues mean that few aquatic species (<< 5%) would be affected by acute exposure, and ~ 10% of the species would be affected by chronic exposure. Based on target hazard quotients (THQ) and estimated weekly intakes (EWIs), urban residents around the JZB would experience higher health risks in comparison with rural residents due to higher seafood consumption rates, especially from mollusk consumption. Therefore, urban households in the area should increase their fish consumption rate and reduce that of mollusks.


Subject(s)
Cadmium , Water Pollutants, Chemical , Animals , Bays , Cadmium/analysis , China , Environmental Monitoring , Humans , Risk Assessment , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicity
12.
Water Res ; 184: 116186, 2020 Oct 01.
Article in English | MEDLINE | ID: mdl-32711223

ABSTRACT

China has been the major fishery producer in the Northwest Pacific Ocean for decades and the seafood safety deserves continuous concern. In this study, 188 organism and 27 sediment samples were collected from the Jiaozhou Bay, a typical semi-enclosed bay adjacent to the Northwest Pacific Ocean, to study the arsenic (As) pollution level and trophodynamics in the coastal regions of China combined with a meta-analysis. Results showed that arsenic was the most abundant in crustaceans with the average of 28.84 ± 4.95 mg/kg in dry weight, in comparison with molluscs (18.68 ± 2.51 mg/kg) and fish (9.31 ± 1.45 mg/kg). Additionally, based on a meta-analysis, arsenic in coastal organisms generally decreased from north to south in China. With increasing values of δ15N, arsenic was significantly biomagnified in the molluscs but bio-diluted in the groups of crustaceans and fish. When all the species were taken into consideration, overall bio-dilution of As was observed through the simplified food chain in the Jiaozhou Bay. Based on the target hazard quotient (THQ), the health risk of consuming seafood from the Jiaozhou Bay was not significant except for several kinds of crustaceans. The smaller THQs indicated lower health risk of eating molluscs and fish than crustaceans. Besides, urban households tended to undertake much higher risk than rural households. Based on our results, it is recommended for urban citizens to reduce the frequency of consuming crustaceans and give preference to fish when choosing seafood.


Subject(s)
Arsenic , Water Pollutants, Chemical , Animals , Arsenic/analysis , China , Environmental Monitoring , Fishes , Pacific Ocean , Risk Assessment , Water Pollutants, Chemical/analysis
13.
Mar Genomics ; 53: 100752, 2020 Oct.
Article in English | MEDLINE | ID: mdl-32014385

ABSTRACT

To clarify evolutionary characteristics, phylogenetic relationships as well as species identification of C. okamurae, we determined the cpDNA sequence of Caulerpa okamurae using de novo sequencing in the present study. The cpDNA of C. okamurae was 148,274 bp in length, and it lacked the inverted repeat commonly found in vascular green plants. The cpDNA of C. okamurae was highly compact with a gene density of 71.7%. Moreover, it was an AT-rich genome (65.5%) consisting 76 protein-coding genes (PCGs), 27 transfer RNA (tRNA) genes, three ribosomal RNA (rRNA) genes, 32 putative open reading frames (ORFs) and six introns. Additionally, the six introns were annotated in six genes as follows: psbA, rpoB, ftsH, psbD, atpF and cysA. The overall base composition of its cpDNA was 65.46% for AT. A total of 56 genes were encoded on the light strand, while all the other 50 chloroplast genes were encoded on the heavy strand. All of the PCGs had ATG as their start codon and employed TAA, TGA or TAG as their termination codon. Phylogenetic analyses suggested that the complete cpDNA sequence of C. okamurae fell in the Chlorophyta, Ulvophyceae, Bryopsidales, and Caulerpaceae and more resembled the cpDNAs of C. racemosa, C. cliftonii voucher and Tydemania expeditionis. Taken together, our data offered useful information for the studies of C.okamurae on evolutionary characteristics, phylogenetic relationships as well as species identification.


Subject(s)
Caulerpa/genetics , DNA, Algal/analysis , DNA, Chloroplast/analysis , Genome, Chloroplast , Caulerpa/classification , Phylogeny
14.
Mar Pollut Bull ; 150: 110737, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31791595

ABSTRACT

The distribution characteristics, correlation, and bioavailability of 14 trace elements in different fishes and corals collected from the coral-reef systems of the Xisha Islands, China were systematic studied for the first time. All detected elements were measured using inductively coupled plasma mass spectrometry after pretreatment by microwave digestion. The fishes had slight differences in element enrichment selectivity and bioavailability with average levels as follows: V, 0.100 mg·kg-1; Cr, 0.683 mg·kg-1; Mn, 1.178 mg·kg-1; Fe, 51.806 mg·kg-1; Co, 0.072 mg·kg-1; Ni, 1.286 mg·kg-1; Cu, 1.428 mg·kg-1; Zn, 10.384 mg·kg-1; As, 6.437 mg·kg-1; Se, 0.830 mg·kg-1; Mo, 0.101 mg·kg-1; Cd, 0.051 mg·kg-1; Pb, 0.308 mg·kg-1; and U, 0.008 mg·kg-1. Trace element contents in corals were higher than those in fishes. The distribution characteristics of trace elements in fishes and corals presented a significant correlation in North Reef and Yongle Atoll, thereby indicating an evident effect on living areas compared with trace elements in fishes from the Spratly Islands. Cluster analysis of fishes and corals based on trace elements showed that they had different selectivities and bioavailabilities to trace elements. The EDI and THQ ratios of Cu, As, Cd, Cr, and Pb demonstrated that fishes were unlikely to experience serious adverse effects, except for As in Chaetodon auriga, Myripristis kuntee, Gnathodentex aureolineatus, and Hemigymnus melapterus in Xisha Islands.


Subject(s)
Anthozoa , Coral Reefs , Environmental Monitoring , Trace Elements/analysis , Animals , China , Islands
15.
Mar Pollut Bull ; 145: 278-286, 2019 Aug.
Article in English | MEDLINE | ID: mdl-31590788

ABSTRACT

Microplastics have emerged as new pollutants in oceans. Nevertheless, information of the long-term variations in the composition of plastic-associated microbial communities in coastal waters remains limited. This study applied high-throughput sequencing to investigate the successional stages of microbial communities attached to polypropylene and polyvinyl chloride microplastics exposed for one year in the coastal seawater of China. The composition of plastisphere microbial communities varied remarkably across geographical locations and exposure times. The dominant bacteria in the plastisphere were affiliated with the Alphaproteobacteria class, particularly Rhodobacteraceae, followed by the Gammaproteobacteria class. Scanning electron microscopy analysis revealed that the microplastics showed signs of degradation. Microbial communities showed adaptations to plastisphere including more diverse microbial community and greater "xenobiotics biodegradation and metabolism" in metabolic pathway analysis. The findings elucidate the long-term changes in the community composition of microorganisms that colonize microplastics and expand the understanding of plastisphere microbial communities present in the marine environment.


Subject(s)
Microbiota/physiology , Plastics , Water Pollutants, Chemical , Adaptation, Biological , Bacteria/isolation & purification , Biodegradation, Environmental , China , Polypropylenes , Polyvinyl Chloride , Seawater/microbiology , Spatio-Temporal Analysis , Water Microbiology
16.
Environ Sci Technol ; 53(14): 8036-8046, 2019 Jul 16.
Article in English | MEDLINE | ID: mdl-31204475

ABSTRACT

The impacts of microplastics on coral reefs are gaining attention due to findings that microplastics affect coral health. This work investigated the distribution and characteristics of microplastics in the seawater, fish, and corals in 3 atolls from the Xisha Islands of South China Sea. In the seawater samples, microplastics were detected in the outer reef slopes, reef flats, and lagoons with abundances ranging from 0.2 to 11.2, 1.0 to 12.2, and 1.0 to 45.2 items L-1, respectively. Microplastic abundance was 0-12.0 items individual-1 (0-4.7 items g-1) in fish and 1.0-44.0 items individual-1(0.02-1.3 items g-1) in coral. The predominant shape and polymer of microplastics in seawater, fish, and coral were fibrous rayon and polyethylene terephthalate (PET). Microplastic sizes primarily ranged from 20-330 µm in both the seawater and fish, while there were relatively more 1-5 mm microplastics in the corals. The shape, size, color, and polymer type distribution patterns of microplastics in seawater more closely resembled those in fish gills than those in fish gastrointestinal tracts or coral samples. This study shows that microplastics are abundant in these coral reef systems and they are captured by fish or "trapped" by corals.


Subject(s)
Coral Reefs , Water Pollutants, Chemical , Animals , China , Environmental Monitoring , Islands , Plastics
17.
Mitochondrial DNA B Resour ; 4(2): 4116-4117, 2019 Nov 20.
Article in English | MEDLINE | ID: mdl-33366344

ABSTRACT

In this study, the complete mitochondrial genome of the Aphrodita australis was sequenced. The complete mitochondrial genome was circular and 15,288 bp in length, consisted of a typical set of 13 protein-coding genes (PCGs), 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and 1 non-coding control region. All these genes are in the heavy strand. The non-coding control region is 672 bp in length, and located between tRNA-Ser and tRNA-Leu. The overall nucleotides base composition of the heavy strand is 31.02% for A, 22.76% for C, 12.49% for G, and 33.73% for T, with a slight A + T-rich feature (64.75%). All of the PCGs begin with ATG as their start codon and the cox 3, cytb and nad 3 are terminated with TAA, atp8, nad4, nad 4l, and nad 6 are terminated with TAG, while others are terminated by incomplete codon T. Seen from the phylogenetic tree, A. australis has a more close relationship with Goniada japonica than other species.

18.
Gene ; 673: 225-238, 2018 Oct 05.
Article in English | MEDLINE | ID: mdl-29933020

ABSTRACT

The complete mitochondrial genome is greatly important for studies on genetic structure and phylogenetic relationship at various taxonomic levels. To obtain information about the evolutionary trends of mtDNA in the Ulvophyceae and also to gain insights into the phylogenetic relationships between ulvophytes and other chlorophytes, we determined the mtDNA sequence of Caulerpa lentillifera (sea grape) using de novo mitochondrial genome sequencing. The complete genomic DNA of C. lentillifera was circular and 209,034 bp in length, and it was the largest green-algal mitochondrial genome sequenced to date, with a low gene density of 65.2%, which is reminiscent of the "expanded" pattern of evolution exhibited by embryophyte mtDNAs. The C. lentillifera mtDNA consisted of a typical set of 17 protein-coding genes (PCGs), 20 transfer RNA (tRNA) genes, three ribosomal RNA (rRNA) genes, 42 putative open reading frames (ORFs) and 29 introns, which had homologs in green-algal mtDNAs displaying an "ancestral" or a "reduced-derived" pattern of evolution. The overall base composition of its mitochondrial genome was 24.19% for A, 24.94% for T, 25.80% for G, 25.07% for C and 50.87% for GC. The mitochondrial genome of C. lentillifera was characterized by numerous small intergenic regions and introns, which was clearly different from other green algae. With the exception of the NADH dehydrogenase subunit 6 (ND6), ND1, ATP and three tRNA genes (tRNA-His, tRNA-Thr and tRNA-Ala), all other mitochondrial genes were encoded on the heavy strand. All of the PCGs had ATG as their start codon and employed TAA, TGA or TAG as their termination codon. To gain insights into the evolutionary trends of mtDNA in the Ulvophyceae, we inferred the complete mtDNA sequence of C. lentillifera, an ulvophyte belonging to a distinct, early-diverging lineage. Taken together, our data offered useful information for the studies on phylogenetic hypotheses and phylogenetic relationships of C. lentillifera within the Chlorophyta.


Subject(s)
Caulerpa/genetics , DNA, Mitochondrial/genetics , Genome, Mitochondrial , DNA, Algal/genetics , Evolution, Molecular , Gene Library , Genome , Introns , Nucleic Acid Conformation , Open Reading Frames , Phylogeny , RNA, Ribosomal/genetics , RNA, Transfer/genetics
19.
Harmful Algae ; 68: 240-247, 2017 09.
Article in English | MEDLINE | ID: mdl-28962984

ABSTRACT

In recent decades, the frequency and intensity of harmful algal blooms (HABs), as well as a profusion of toxic phytoplankton species, have significantly increased in coastal regions of China. Researchers attribute this to environmental changes such as rising atmospheric CO2 levels. Such addition of carbon into the ocean ecosystem can lead to increased growth, enhanced metabolism, and altered toxicity of toxic phytoplankton communities resulting in serious human health concerns. In this study, the effects of elevated partial pressure of CO2 (pCO2) on the growth and toxicity of a strain of Alexandrium tamarense (ATDH) widespread in the East and South China Seas were investigated. Results of these studies showed a higher specific growth rate (0.31±0.05day-1) when exposed to 1000µatm CO2, (experimental), with a corresponding density of (2.02±0.19)×107cellsL-1, that was significantly larger than cells under 395µatm CO2(control). These data also revealed that elevated pCO2 primarily affected the photosynthetic properties of cells in the exponential growth phase. Interestingly, measurement of the total toxin content per cell was reduced by half under elevated CO2 conditions. The following individual toxins were measured in this study: C1, C2, GTX1, GTX2, GTX3, GTX4, GTX5, STX, dcGTX2, dcGTX3, and dcSTX. Cells grown in 1000µatm CO2 showed an overall decrease in the cellular concentrations of C1, C2, GTX2, GTX3, GTX5, STX, dcGTX2, dcGTX3, and dcSTX, but an increase in GTX1 and GTX4. Total cellular toxicity per cell was measured revealing an increase of nearly 60% toxicity in the presence of elevated CO2 compared to controls. This unusual result was attributed to a significant increase in the cellular concentrations of the more toxic derivatives, GTX1 and GTX4.Taken together; these findings indicate that the A. tamarense strain ATDH isolated from the East China Sea significantly increased in growth and cellular toxicity under elevated pCO2 levels. These data may provide vital information regarding future HABs and the corresponding harmful effects as a result of increasing atmospheric CO2.


Subject(s)
Carbon Dioxide/pharmacology , Dinoflagellida/growth & development , Marine Toxins/biosynthesis , Marine Toxins/toxicity , Oceans and Seas , Paralysis/parasitology , Shellfish Poisoning/parasitology , Cell Count , Cell Size , Electron Transport , Photosynthesis , Photosystem II Protein Complex/metabolism , Seawater/chemistry
20.
Lab Chip ; 13(15): 2879-82, 2013 Aug 07.
Article in English | MEDLINE | ID: mdl-23743667

ABSTRACT

We fabricated a microfluidic device consisting of ciliated micropillars, forming a porous silicon nanowire-on-micropillar structure. We demonstrated that the prototype device can preferentially trap exosome-like lipid vesicles, while simultaneously filtering out proteins and cell debris. Trapped lipid vesicles can be recovered intact by dissolving the porous nanowires in PBS buffer.


Subject(s)
Lipids/isolation & purification , Microfluidic Analytical Techniques/instrumentation , Equipment Design , Filtration/instrumentation , Nanowires/chemistry , Porosity , Silicon/chemistry
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