Brassinosteroid-dependent phosphorylation of PHOSPHATE STARVATION RESPONSE2 reduces its DNA-binding ability in rice.

Brassinosteroids (BRs) are widely used as plant growth regulators in modern agriculture. Understanding how BRs regulate nutrient signaling is crucial for reducing fertilizer usage. Here we elucidate that the central BR signaling inhibitor GSK3/SHAGGY-LIKE KINASE2 (GSK2) interacts directly with and phosphorylates PHOSPHATE STARVATION RESPONSE2 (OsPHR2), the key regulator of phosphate (Pi) signaling, to suppress its transcription factor activity in rice (Oryza sativa). We identify a critical phosphorylation site at serine residue S269 of OsPHR2 and demonstrate that phosphorylation by GSK2 or phosphor-mimic mutation of S269 substantially impairs the DNA-binding activity of OsPHR2, and thus diminishes expression of OsPHR2-induced genes and reduces Pi levels. Like BRs, Pi starvation noticeably induces GSK2 instability. We further show that this site-specific phosphorylation event is conserved in Arabidopsis (Arabidopsis thaliana), but varies among the PHR-family members, being present only in most land plants. These results unveil a distinctive post-transcriptional regulatory mechanism in Pi signaling by which BRs promote Pi acquisition, with a potential contribution to the environmental adaptability of plants during their evolution.

Interplay of ferroptosis, cuproptosis, and PANoptosis in cancer treatment-induced cardiotoxicity: Mechanisms and therapeutic implications.

With the prolonged survival of individuals with cancer, the emergence of cardiovascular diseases (CVD) induced by cancer treatment has become a significant concern, ranking as the second leading cause of death among cancer survivors. This review explores three distinct types of programmed cell death (PCD): ferroptosis, cuproptosis, and PANoptosis, focusing on their roles in chemotherapy-induced cardiotoxicity. While ferroptosis and cuproptosis are triggered by excess iron and copper (Cu), PANoptosis is an inflammatory PCD with features of pyroptosis, apoptosis, and necroptosis. Recent studies reveal intricate connections among these PCD types, emphasizing the interplay between cuproptosis and ferroptosis. Notably, the role of intracellular Cu in promoting ferroptosis through GPX4 is highlighted. Additionally, ROS-induced PANoptosis is influenced by ferroptosis and cuproptosis, suggesting a complex interrelationship. This review provides insights into the molecular mechanisms of these PCD modalities and their distinct contributions to chemotherapy-induced cardiotoxicity. Furthermore, we discuss the potential application of cardioprotective drugs in managing these PCD types. This comprehensive analysis aims to advance the understanding, diagnosis, and therapeutic strategies for cardiotoxicity associated with cancer treatment.

A novel Bacillus aerolatus CX253 attenuates inflammation induced by Streptococcus pneumoniae in childhood and pregnant rats by regulating gut microbiome.

Streptococcus pneumoniae (Spn) is the predominant pathogen responsible for community-acquired pneumonia (CAP) in children under five years old, and it can induce over 17% of pregnant women. However, no more effective measures exist to prevent infection induced by Spn in these two special populations. The beneficial microbes can antagonize Spn and provide new targets for preventing pneumococcal infections. This study used 16S rRNA gene sequencing and targeted metabolomics to evaluate the role of the Bacillus aerolatus CX253 (CX253) in alleviating Spn infection. Additionally, the colonization of CX253 was observed in nose, trachea, and lung by using confocal laser scanning microscopy and fluorescent labeling techniques. Compared with the model group, the expression level of interleukin-1ß was dropped 1.81-fold and 2.22-fold, and interleukin-6 was decreased 2.39-fold and 1.84-fold. The express of tumor necrosis factor-α was down 2.30-fold and 3.84-fold in prevention group of childhood and pregnant rats, respectively. The 16S rRNA sequencing results showed that CX253 administration alone significantly increased the abundance of Lactobacillus, Limosilactobacillus, and Prevotella in the gut of childhood and pregnant rats. Furthermore, the CX253 increased propionate in the gut of childhood rats and increased propionate and butyrate in the gut of pregnant rats to inhibit pulmonary inflammation. In summary, CX253 attenuated Spn-induced inflammation by regulating the gut microbiota and SCFAs. The research provides valuable information for the prevention of pneumonia.

ARGONAUTE2 Enhances Grain Length and Salt Tolerance by Activating BIG GRAIN3 to Modulate Cytokinin Distribution in Rice.

Maintaining stable, high yields under fluctuating environmental conditions is a long-standing goal of crop improvement but is challenging due to internal trade-off mechanisms, which are poorly understood. Here, we identify ARGONAUTE2 (AGO2) as a candidate target for achieving this goal in rice (Oryza sativa). Overexpressing AGO2 led to a simultaneous increase in salt tolerance and grain length. These benefits were achieved via the activation of BIG GRAIN3 (BG3), encoding a purine permease potentially involved in cytokinin transport. AGO2 can become enriched on the BG3 locus and alter its histone methylation level, thus promoting BG3 expression. Cytokinin levels decreased in shoots but increased in roots of AGO2-overexpressing plants. While bg3 knockout mutants were hypersensitive to salt stress, plants overexpressing BG3 showed strong salt tolerance and large grains. The knockout of BG3 significantly reduced grain length and salt tolerance in AGO2-overexpressing plants. Both genes were transcriptionally suppressed by salt treatment. Salt treatment markedly increased cytokinin levels in roots but decreased them in shoots, resulting in a hormone distribution pattern similar to that in AGO2-overexpressing plants. These findings highlight the critical roles of the spatial distribution of cytokinins in both stress responses and grain development. Therefore, optimizing cytokinin distribution represents a promising strategy for improving both grain yield and stress tolerance in rice.

Novel Signal Enhancement Strategy for Laser-Induced Breakdown Spectroscopy via Miniaturized Atmospheric Pressure Glow Discharge.

Herein, a sensitivity enhancement technique for laser-induced breakdown spectroscopy (LIBS) by atmospheric pressure glow discharge was proposed, while cylindrical confinement was used for further improvement. A comprehensive parameters evaluation of the proposed technique was carried out (at the laser energy of 30 mJ), with the emission intensities of Ti, Ni, Cu, Y, Ba, La, Eu, Yb, and Lu in soil samples enhanced by 17.8, 5.7, 5.2, 10.5, 7.4, 6.1, 8.7, 7.8, and 8.7 times, respectively. The limits of detection (LODs) of Ti, Ni, Cu, Y, Ba, La, Eu, Yb, and Lu were significantly decreased from 246, 356, 133, 158, 10, 175, 102, 105, and 262 mg kg-1 to 43, 67, 31, 20, 2, 35, 21, 18, and 49 mg kg-1, respectively. In addition, the possible signal enhancement mechanism was preliminarily explained by studying the plasma electron temperature and density with and without the proposed sensitization strategy.

Diversification of plant agronomic traits by genome editing of brassinosteroid signaling family genes in rice.

Brassinosteroids (BRs) regulate various agronomic traits such as plant height, leaf angle, and grain size in rice (Oryza sativa L.); thus, BR signaling components are promising targets for molecular rational design. However, genetic materials for BR-signaling genes or family members remain limited in rice. Here, by genome editing using clustered regularly interspaced short palindromic repeats (CRSPR)/Cas9 tools, we generated a panel of single, double, triple, or quadruple mutants within three BR signaling gene families, including GSK3/SHAGGY-LIKE KINASE1 (GSK1)-GSK4, BRASSINAZOLE-RESISTANT1 (OsBZR1)-OsBZR4, and protein phosphatases with kelch-like (PPKL)1-PPKL3, under the same background (Zhonghua11, japonica). The high-order mutants were produced by either simultaneously targeting multiple sites on different genes of one family (GSKs and PPKLs) or targeting the overlapping sequences of family members (OsBZRs). The mutants exhibited a diversity of plant height, leaf angle, and grain morphology. Comparison analysis of the phenotypes together with BR sensitivity tests suggested the existence of functional redundancy, differentiation, or dominancy among the members within each family. In addition, we generated a set of transgenic plants overexpressing GSK2, OsBZR1/2, and PPKL2, respectively, in wild-type or activated forms with fusion of different tags, and also verified the protein response to BR application. Collectively, these plants greatly enriched the diversity of important agronomic traits in rice. We propose that editing of BR-related family genes could be a feasible approach for screening of desired plants to meet different requirements. Release of these materials as well as the related information also provides valuable resources for further BR research and utilization.

The disruption on gut microbiome of Decabromodiphenyl ethane exposure in the simulator of the human intestinal microbial ecosystem (SHIME).

The health risks of Decabromodiphenyl ethane (DBDPE) with its cardiovascular toxicity, liver toxicity and cytotoxicity had been generally acknowledged. However, the influence on gut microbiome and short-chain fatty acids (SCFAs) metabolism caused by DBDPE exposure remained unknown. In this study, three exposure groups (5, 50, 500 mg/L) and control group were used to investigate the effect of DBDPE by using simulator of the human intestinal microbial ecosystem (SHIME). 16S rRNA gene high-throughput sequencing illustrated that high dose DBDPE exposure increased the α-diversity of gut microbiota, while reduced the abundance of Firmicutes and Proteobacteria. In addition, the low dose (5 mg/L) DBDPE inhibited the increasing of SCFAs, but the medium and high dose (50 and 500 mg/L) DBDPE promoted the advancement, especially in ascending colon. Notably, DBDPE exposure lead a similar changing of acetic acid and butyric acid contents in different sections of the colon. This study confirmed the alternation of composition and metabolic function in gut microbial community due to DBDPE exposure, indicating an intestinal damage and appealing for more attention concentrated on the health effects of DBDPE exposure.

Microcella aerolata sp. nov., isolated from electronic waste-associated bioaerosols.

A Gram-positive, non-motile, non-spore-forming and short rod-shaped actinomycete strain, designated GA224T, was isolated from electronic waste-associated bioaerosols. The optimal growth conditions for this isolate, a facultatively anaerobic bacterium, were 37 °C and pH 8.0. The cell-wall peptidoglycan type was B2γ, with 2,4-diaminobutyric acid (DAB) as the diamino acids, while the major menaquinone was MK-12. The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, unidentified glycolipids and an unidentified lipid. The major cellular fatty acids were anteiso-C15:0 and iso-C16:0. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GA224T fell within the genus Microcella. The draft genome of strain GA224T comprised 2,495,189 bp with a G + C content of 72.2 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain GA224T and the type strain of the type species of Microcella species were lower than 95% and 70%, respectively. Based on the phenotypic, chemotaxonomic and genomic data, strain GA224T represents a novel species, for which the name Microcella aerolata sp. nov. is proposed, with GA224T as the type strain (= GDMCC 1.2165 T = JCM 34462 T).

Relevance of mitochondrial oxidative stress to arrhythmias: Innovative concepts to target treatments.

Cardiac arrhythmia occurs frequently worldwide, and in severe cases can be fatal. Mitochondria are the power plants of cardiomyocytes. In recent studies, mitochondria under certain stimuli produced excessive reactive oxygen species (ROS), which affect the normal function of cardiomyocytes through ion channels and related proteins. Mitochondrial oxidative stress (MOS) plays a key role in diseases with multifactorial etiopathogenesis, such as arrhythmia; MOS can lead to arrhythmias such as atrial fibrillation and ventricular tachycardia. This review discusses the mechanisms of arrhythmias caused by MOS, particularly of ROS produced by mitochondria. MOS can cause arrhythmias by affecting the activities of Ca2+-related proteins, the mitochondrial permeability transition pore protein, connexin 43, hyperpolarization-activated cyclic nucleotide-gated potassium channel 4, and ion channels. Based on these mechanisms, we discuss possible new treatments for arrhythmia. Targeted treatments focusing on mitochondria may reduce the progression of arrhythmias, as well as the occurrence of severe arrhythmias, and may be effective for personalized disease prevention.

Roseicella aerolata sp. nov., isolated from bioaerosols of electronic waste.

A novel Gram-stain-negative, non-motile, spherical-shaped and facultatively anaerobic bacterial strain, designated as GB24T was isolated from bioaerosols of an E-waste dismantling site in Guiyu, Guangdong Province, South PR China. Growth occurred at 15-40 °C (optimum 37 °C), pH 5.5-9.5 (optimum 7.0), and up to 0.5 % NaCl (w/v) under aerobic conditions, GB24T was characterized taxonomically and phylogenetically. The sole isoprenoid quinone detected was ubiquinone-10 (Q-10). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, three unidentified glycolipids, one unidentified phospholipid, and one unidentified aminolipid. Carotenoid pigments were produced. The major cellular fatty acids (> 10 % of total fatty acids) were C17 : 1ω6c (51.5 %) and summed feature 8 (13.5 %, comprising C18 : 1ω7c and/or C18 : 1ω6c). Phylogenetic analysis based on 16S rRNA gene sequence and draft genome grouped strain GB24T into the genus Roseicella. GB24T was most closely related to Roseicella frigidaeris DB1506T with 97.5 % 16S rRNA gene sequence similarity. The draft genome of GB24T comprised 6 153 170 bp with a DNA G+C content of 71.5 %. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between GB24T and DB1506T were 83.2 % (Ortho ANI), 83.3 % [ANI by blast (ANIb)] and 27.0 %, respectively. Further genomic analysis of GB24T revealed the secondary metabolite clusters of terpene and phosphonate, which indicate the capacity for malleobactin (14 %) and phosphinothricin (6 %) tripeptide production. On the basis of the genotypic, chemotaxonomic and phenotypic results, GB24T represents a novel species, for which the name Roseicella aerolata sp. nov. is proposed. The type strain of Roseicella aerolata is GB24T (= GDMCC 1.2169T = JCM 34449T).

The divergence of brassinosteroid sensitivity between rice subspecies involves natural variation conferring altered internal auto-binding of OsBSK2.

Japonica/geng and indica/xian are two major rice (Oryza sativa) subspecies with multiple divergent traits, but how these traits are related and interact within each subspecies remains elusive. Brassinosteroids (BRs) are a class of steroid phytohormones that modulate many important agronomic traits in rice. Here, using different physiological assays, we revealed that japonica rice exhibits an overall lower BR sensitivity than indica. Extensive screening of BR signaling genes led to the identification of a set of genes distributed throughout the primary BR signaling pathway with divergent polymorphisms. Among these, we demonstrate that the C38/T variant in BR Signaling Kinase2 (OsBSK2), causing the amino acid change P13L, plays a central role in mediating differential BR signaling in japonica and indica rice. OsBSK2L13 in indica plays a greater role in BR signaling than OsBSK2P13 in japonica by affecting the auto-binding and protein accumulation of OsBSK2. Finally, we determined that OsBSK2 is involved in a number of divergent traits in japonica relative to indica rice, including grain shape, tiller number, cold adaptation, and nitrogen-use efficiency. Our study suggests that the natural variation in OsBSK2 plays a key role in the divergence of BR signaling, which underlies multiple divergent traits between japonica and indica.

Brucella Outer Membrane Lipoproteins 19 and 16 Differentially Induce Interleukin-18 Response or Pyroptosis in Human Monocytic Cells.

BACKGROUND: Brucella species are Gram-negative intracellular bacteria that causes severe inflammatory diseases in animals and humans. Two major lipoproteins (L19 and L16) of Brucella outer membrane proteins were studied to explore the association with inflammatory response of human monocytes (THP-1). METHODS: Activated THP-1 cells induced with recombinant L19 and L16 were analyzed in comparison with unlipidated forms (U19 and U16) and lipopolysaccharide (LPS) of Brucella melitensis, respectively. RESULTS: Secretion of inflammatory factors tumor necrosis factor-α, interleukin (IL)-6, and IL-1ß was significantly increased from L19, L16, or both stimulated THP-1 cells. High secretion of IL-18 was detected only from L19-induced cells. Signaling of those cytokine responses was identified mainly through the P38-mitogen-activated protein kinase pathway, and signaling of L19-induced IL-1ß response partly occurred via necrosis factor-κB. While exploring different forms of IL-18, we found that L19-induced production of active IL-18 (18 kD) occurred through upregulating NLRP3 and activating caspase-1, whereas L16-induced production of inactive IL-18 fragments (15 kD and 16 kD) occurred through activating caspase-8/3. We also found that L19 upregulated phosphorylation of XIAP for inhibiting caspase-3 activity to cleave IL-18, whereas L16 activated caspase-3 for producing GSDME-N and leading to pyroptosis of THP-1 cells. CONCLUSIONS: Brucella L19 and L16 differentially induce IL-18 response or pyroptosis in THP-1 cells, respectively.

GSK2 stabilizes OFP3 to suppress brassinosteroid responses in rice.

Brassinosteroids (BRs) are a class of phytohormones that modulate several important agronomic traits in rice (Oryza sativa). GSK2 is one of the critical suppressors of BR signalling and targets transcription factors such as OsBZR1 and DLT to regulate BR responses. Here, we identified OFP3 (OVATE FAMILY PROTEIN 3) as an interactor of both GSK2 and DLT by yeast-two-hybrid screening and demonstrated that OFP3 plays a distinctly negative role in BR responses. While knockout of OFP3 promoted rice seedling growth, overexpression of OFP3 led to strong BR insensitivity, which resulted in reduced plant height, leaf angle, and grain size. Interestingly, both BR biosynthetic and signalling genes had decreased expression in the overexpression plants. OFP3 overexpression also enhanced the phenotypes of BR-deficient mutants, but largely suppressed those of BR-enhanced plants. Moreover, treatment with either BR or bikinin, a GSK3-like kinase inhibitor, induced OFP3 depletion, whereas GSK2 or brassinazole, a BR synthesis inhibitor, promoted OFP3 accumulation. Furthermore, OFP3 exhibited transcription repressor activity and was able to interact with itself as well as additional BR-related components, including OFP1, OSH1, OSH15, OsBZR1, and GF14c. Importantly, GSK2 can phosphorylate OFP3 and enhance these interactions. We propose that OFP3, as a suppressor of both BR synthesis and signalling but stabilized by GSK2, incorporates into a transcription factor complex to facilitate BR signalling control, which is critical for the proper development of various tissues.

DNA damage of human derived liver cell line HL-7702 induced by organic extracts from surface water in Pearl River Delta, China.

Many organic pollutants attract public health concern due to their genotoxicity. To investigate the genotoxicity of organic matter in surface water of the Pearl River Delta (PRD). Organic substances of 24 samples (dry and wet season) from North River, West River and East River were extracted from 60 L source water by XAD-2 macroporous resin. DNA damage effect of organic extracts was tested in human derived liver cells (HL-7702), using single cell gel electrophoresis (SCGE) assay. The results showed that 100% organic extracts (24/24) could induce DNA damage in HL-7702 cells when the concentration was above 1.0 L surface water/ml culture, no significant difference of DNA damage between dry and wet seasons was observed. The organic substance-induced DNA damage in HL-7702 cells was significantly (P < 0.05) correlated with the contents of Dissolved Organic Carbon in both seasons and Total Suspended Solids in dry season. In conclusion, organic extracts induced genetic damage in HL-7702 cells, indicating potential genotoxicity of organic pollutants of surface water from PRD, South China.

Bacillus aerolatus sp. nov., a novel member of the genus Bacillus, isolated from bioaerosols in a school playground.

A Gram-positive, endospore-forming, rod-shaped bacterium with a single flagellum, and a motile strain, designated CX253, was isolated from bioaerosols. The isolate is facultatively anaerobic, is able to grow at 25-45 â„ƒ (optimum 37 â„ƒ) and pH 6.5-10.0 (optimum 7.5), and can tolerate up to 5.0% NaCl (w/v) under aerobic conditions. The diagnostic diamino acid in the cell wall of strain CX253T is meso-diaminopimelic acid, while major isoprenoid quinone is menaquinone 6 (MK-6) along with a smaller amount of MK-7 (20%). The polar lipid profile is composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipids and glycolipids. The major cellular fatty acid is iso-C15:0 and anteiso-C15:0. Phylogenetic analysis based on 16S rRNA gene and genome sequence grouped strain CX253T into the genus Bacillus. The strain was most closely related to Bacillus thermotolerans CCTCC AB 2012108 T by comparison of 16S rRNA gene sequence (97.2% similarity) and to Bacillus wudalianchiensis CCTCC AB 2015266 T by comparison of gyrB gene sequence (80.1% similarity). The draft genome of strain CX253T comprised 3,929,195 bp with a G + C content of 43.3 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain CX253T and phylogenetically related Bacillus species were lower than 95% and 70%, respectively. Thus, the polyphasic evidence generated through phenotypic, chemotaxonomic and genomic methods confirmed that strain CX253T (= GDMCC 1.1608 T = KACC 21318 T) was a novel species of the genus Bacillus, for which the name Bacillus aerolatus sp. nov. is proposed.

Big Grain3, encoding a purine permease, regulates grain size via modulating cytokinin transport in rice.

Grain size is an important agronomic trait affecting grain yield, but the underlying molecular mechanisms remain to be elucidated. Here, we isolated a dominant mutant, big grain3 (bg3-D), which exhibits a remarkable increase of grain size caused by activation of the PURINE PERMEASE gene, OsPUP4. BG3/OsPUP4 is predominantly expressed in vascular tissues and is specifically suppressed by exogenous cytokinin application. Hormone profiling revealed that the distribution of different cytokinin forms, in roots and shoots of the bg3-D mutant, is altered. Quantitative reverse transcription-PCR (qRT-PCR) analysis indicated that expression of rice cytokinin type-A RESPONSE REGULATOR (OsRR) genes is enhanced in the roots of the bg3-D mutant. These results suggest that OsPUP4 might contribute to the long-distance transport of cytokinin, by reinforcing cytokinin loading into vascular bundle cells. Furthermore, plants overexpressing OsPUP7, the closest homolog of OsPUP4, also exhibited a similar phenotype to the bg3-D mutant. Interestingly, subcellular localization demonstrated that OsPUP4 was localized on the plasma membrane, whereas OsPUP7 was localized to the endoplasmic reticulum. Based on these findings, we propose that OsPUP4 and OsPUP7 function in a linear pathway to direct cytokinin cell-to-cell transport, affecting both its long-distance movement and local allocation.

Different network pharmacology mechanisms of Danshen-based Fangjis in the treatment of stable angina.

Danshen (Salvia miltiorrhiza) preparations such as Danhong injection, Danshen injection, Salvianolate injection, compound Danshen injection and Sodium Tanshinone IIA Sulfonate (STS) injection are widely used in China to treat stable angina (angina pectoris) caused by coronary heart disease. In this study we compared the network pharmacological mechanisms of the 5 Danshen preparations. Following a literature search performed in PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI) database, China Biology Medicine (CBM) database, China Conference Paper Database, Wanfang Database, VIP Database and Conference Proceedings Citation Index (through January 2015), 444 randomized controlled trial publications detailing the use of the 5 Danshen-based injections for treating stable angina were identified, and their combined data were analyzed using a network meta-analysis. All of the 5 Danshen-based preparations were effective in treating stable angina with clinical improvement rates of 72.4%-91.6% and electrocardiogram (ECG) improvement rates of 54.5%-71.6%. According to both clinical improvement and ECG improvement, the 5 Danshen-based preparations were ranked as follows: Danhong injection > Salvianolate injection > STS injection > compound Danshen injection > Danshen injection. There were no significant differences among the safety profiles of the 5 Danshen preparations. The meta-analysis results were further examined using a network pharmacology approach and functional enrichment analysis, which revealed that Danshen and Danhong injections affected 4 and 15 signaling pathways, respectively, and that the 4 signaling pathways affected by Danshen were a subset of those influenced by Danhong. Therefore, Danhong injection affected some unique signaling pathways that might regulate lipoprotein metabolism, oxidation, and inflammation, and protect vascular endothelia, reflecting the multi-component and multi-target characteristics of this traditional formula and its strengths in treating complex diseases.

Successive transitory distribution of Thaumarchaeota and partitioned distribution of Bathyarchaeota from the Pearl River estuary to the northern South China Sea.

Thaumarchaeota and Bathyarchaeota (formerly named Miscellaneous Crenarchaeotal Group, MCG) are globally occurring archaea playing potential roles in nitrogen and carbon cycling, especially in marine benthic biogeochemical cycle. Information on their distributional and compositional patterns could provide critical clues to further delineate their physiological and biochemical characteristics. Profiles of thaumarchaeotal and the total archaeal community in the northern South China Sea surface sediments revealed a successively transitional pattern of Thaumarchaeota composition using MiSeq sequencing. Shallow-sea sediment enriched phylotypes decreased gradually along the slope from estuarine and coastal marine region to the deep-sea, while deep-sea sediment enriched phylotypes showed a trend of increasing. Proportion of Thaumarchaeota within the total archaea increased with seawater depth. Phylotypes enriched in shallow- and deep-sea sediments were affiliated to OTUs originated from similar niches, suggesting that physiological adaption not geographical distance shaped the distribution of Thaumarchaeota lineages. Quantitative PCR also depicted a successive decrease of thaumarchaeotal 16S rRNA gene abundance from the highest at shallow-sea sites E708S and E709S (2.57 × 106 and 2.73 × 106 gene copies/g of dry sediment) to the lowest at deep-sea sites E525S and E407S (1.97 × 106 and 2.14 × 106 gene copies/g of dry sediment). Both of the abundance fractions of Bathyarchaeota subgroups (including subgroups 1, 6, 8, 10, 13, 15, 17, and ungrouped Bathyarchaeota) and the total Bathyarchaeota in the total archaea showed a negative distribution to seawater depth. Partitioned distribution of Bathyarchaeota fraction in the total archaea is documented for the first time in this study, and the shallow- and deep-sea Bathyarchaeota could account for 17.8 and 0.8%, respectively, on average. Subgroups 6 and 8, enriched subgroups in shallow-sea sediments, largely explained this partitioned distribution pattern according to seawater depth. Their prevalence in shallow-sea and suboxic estuarine sediments rather than deep-sea sediments hints that their metabolic properties of carbon metabolism are adapted to carbon substrates in these environments.

Flow Injection Photochemical Vapor Generation Coupled with Miniaturized Solution-Cathode Glow Discharge Atomic Emission Spectrometry for Determination and Speciation Analysis of Mercury.

A novel, compact, and green method was developed for the determination and speciation analysis of mercury, based on flow injection photochemical vapor generation (PVG) coupled with miniaturized solution cathode glow discharge-atomic emission spectroscopy (SCGD-AES). The SCGD was generated between a miniature hollow titanium tube and a solution emerging from a glass capillary. Cold mercury vapor (Hg(0)) was generated by PVG and subsequently delivered to the SCGD for excitation, and finally the emission signals were recorded by a miniaturized spectrograph. The detection limits (DLs) of Hg(II) and methylmercury (MeHg) were both determined to be 0.2 µg L-1. Moreover, mercury speciation analysis could also be performed by using different wavelengths and powers from the UV lamp and irradiation times. Both Hg(II) and MeHg can be converted to Hg(0) for the determination of total mercury (T-Hg) with 8 W/254 nm UV lamp and 60 s irradiation time; while only Hg(II) can be reduced to Hg(0) and determined selectively with 4 W/365 nm UV lamp and 20 s irradiation time. Then, the concentration of MeHg can be calculated by subtracting the Hg(II) from the T-Hg. Because of its similar sensitivity and DL at 8 W/254 nm, the simpler and less toxic Hg(II) was used successfully as a primary standard for the quantification of T-Hg. The novel PVG-SCGD-AES system provides not only a 365-fold improvement in the DL for Hg(II) but also a nonchromatographic method for the speciation analysis of mercury. After validating its accuracy, this method was successfully used for mercury speciation analysis of water and biological samples.