Diversity, prevalence, and expression of cyanase genes (cynS) in planktonic marine microorganisms

Cyanate is utilized by many microbes as an organic nitrogen source. The key enzyme for cyanate metabolism is cyanase, converting cyanate to ammonium and carbon dioxide. Although the cyanase gene cynS has been identified in many species, the diversity, prevalence, and expression of cynS in marine microbial communities remains poorly understood. Here, based on the full-length cDNA sequence of a dinoflagellate cynS and 260 homologs across the tree of life, we extend the conserved nature of cyanases by the identification of additional ultra-conserved residues as part of the modeled holoenzyme structure. Our phylogenetic analysis showed that horizontal gene transfer of cynS appears to be more prominent than previously reported for bacteria, archaea, chlorophytes, and metazoans. Quantitative analyses of marine planktonic metagenomes revealed that cynS is as prevalent as ureC (urease subunit alpha), suggesting that cyanate plays an important role in nitrogen metabolism of marine microbes. Highly abundant cynS transcripts from phytoplankton and nitrite-oxidizing bacteria identified in global ocean metatranscriptomes indicate that cyanases potentially occupy a key position in the marine nitrogen cycle by facilitating photosynthetic assimilation of organic N and its remineralisation to NO3 by the activity of nitrifying bacteria

Atmospheric deposition and river runoff stimulate the utilization of dissolved organic phosphorus in coastal seas

In coastal seas, the role of atmospheric deposition and river runoff in dissolved organic phosphorus (DOP) utilization is not well understood. Here, we address this knowledge gap by combining microcosm experiments with a global approach considering the relationship between the activity of alkaline phosphatases and changes in phytoplankton biomass in relation to the concentration of dissolved inorganic phosphorus (DIP). Our results suggest that the addition of aerosols and riverine water stimulate the biological utilization of DOP in coastal seas primarily by depleting DIP due to increasing nitrogen concentrations, which enhances phytoplankton growth. This “Anthropogenic Nitrogen Pump” was therefore identified to make DOP an important source of phosphorus for phytoplankton in coastal seas but only when the ratio of chlorophyll a to DIP [Log10 (Chl a / DIP)] is larger than 1.20. Our study therefore suggests that anthropogenic nitrogen input might contribute to the phosphorus cycle in coastal seas

Polydopamine nanoparticles for treatment of acute inflammation-induced injury

Nanotechnology-mediated anti-inflammatory therapy is emerging as a novel strategy for treatment of inflammation-induced injury. However, one of the main hurdles for these anti-inflammatory nano-drugs is their potential toxic side effects in vivo. Herein, we uncovered that polydopamine (PDA) nanoparticles with structure and chemical properties similar to melanin, a natural bio-polymer, displayed significant anti-inflammation therapeutic effect on acute inflammation-induced injury. PDA with enriched phenol groups functioned as a radical scavenger to eliminate reactive oxygen species (ROS) generated during inflammatory responses. As revealed by in vivo photoacoustic imaging with a H2O2-specific nanoprobe, PDA nanoparticles remarkably reduced intracellular ROS levels in murine macrophages challenged with either H2O2 or lipopolysaccharide (LPS). The anti-inflammatory capacity of PDA nanoparticles was further demonstrated in murine models of both acute peritonitis and acute lung injury (ALI), where diminished ROS generation, reduced proinflammatory cytokines, attenuated neutrophil infiltration, and alleviated lung tissue damage were observed in PDA-treated mice after a single dose of PDA treatment. Our work therefore presents the great promise of PDA nanoparticles as a biocompatible nano-drug for anti-inflammation therapy to treat acute inflammation-induced injury

Transcriptomic Profiling of Genes Related to Cell Division, Metabolism and Toxin Production in the Dinoflagellate “Alexandrium fundyense”

Environmental conditions conducive to the explosive growth and formation of harmful algal blooms generally range from unique ability to efficiently utilize ambient nutrients, acquire light energy, and to defer grazing. In this dissertation, genetic potential for cell division, metabolism, and saxitoxin production in dinoflagellate “Alexandrium fundyense” (Atama Group I /Clade I) were studied by transcriptome profiling using 454 pyrosequencing. Transcriptome data were generated from a cultured strain (CCMP1719) and a natural bloom (in Long Island Sound) of “A. fundyense” collected over a 24 h period. More than 7.7 and 8.2 million dinoflagellate spliced leader-based 5’ expressed sequence tags were obtained for the laboratory culture and natural bloom respectively from four time points in the diel cycle representing G1, S, G2M of cell cycle phases and light/dark transition. Assembly of the reads yielded 87,273 unique genes for the natural bloom samples and 31,451 for the culture samples with ca. 25% of each assigned putative function. ESTs encoding majority of the enzymes involved in carbohydrate metabolism, oxidative stress response and toxin production were identified in “A. fundyense”. A total of 620 unique genes that encode putative membrane transporters were also identified. Transcript abundance quantified by reverse transcriptase quantitative PCR revealed the significant up-regulation of genes related to carbon fixation, saxitoxin production, nitrogen metabolism in the natural bloom with respect to those in the laboratory culture, indicating the nitrogen-depleted condition during the peak of the bloom and the versatility of “A. fundyense” in exploiting all possible sources of nitrogen to maintain the bloom. To further study the cell cycle regulation in this species, the full-length cDNA of a cyclin gene was isolated from “A. fundyense”, named Afcyc. The deduced protein sequence is closest to, and phylogenetically clusters with documented mitotic cyclin from dinoflagellate Lingulodinium polyedrum among cyclin B sequences from various eukaryotes. Afcyc transcript abundance was over 6-fold higher in the G2M phase than in other cell cycle phases, and showed a positive correlation with the percentage of cells in G2M phase, indicative of a mitotic cyclin, which could be a potential growth marker for monitoring the development of “A. fundyense” toxic blooms

Multi-Objective Optimization Design and Multi-Physics Analysis a Double-Stator Permanent-Magnet Doubly Salient Machine

The double-stator permanent-magnet doubly salient (DS-PMDS) machine is an interesting candidate motor for electric vehicle (EV) applications because of its high torque output and flexible working modes. Due to the complexity of the motor structure, optimization of the DS-PMDS for EVs requires more research efforts to meet multiple specifications. Effective multi-objective optimization to increase torque output, reduce torque ripple, and improve PM material utilization and motor efficiency is implemented in this paper. In the design process, a multi-objective comprehensive function is established. By using parametric sensitivity analysis (PSA) and the sequential quadratic programming (NLPQL) method, the influence extent of each size parameter for different performance is effectively evaluated and optimal results are determined. By adopting the finite element method (FEM), the electromagnetic performances of the optimal DS-PMDS motor is investigated. Moreover, a multi-physical field analysis is included to describe stress, deformation of the rotor, and temperature distribution of the proposed motor. The theoretical analysis verified the rationality of the motor investigated and the effectiveness of the proposed optimization method

Reduced Fitness and Elevated Oxidative Stress in the Marine Copepod <i>Tigriopus japonicus</i> Exposed to the Toxic Dinoflagellate <i>Karenia mikimotoi</i>

Blooms of the toxic dinoflagellate Karenia mikimotoi cause devastation to marine life, including declines of fitness and population recruitment. However, little is known about the effects of them on benthic copepods. Here, we assessed the acute and chronic effects of K. mikimotoi on the marine benthic copepod Tigriopus japonicus. Results showed that adult females maintained high survival (>85%) throughout 14-d incubation, but time-dependent reduction of survival was detected in the highest K. mikimotoi concentration, and nauplii and copepodites were more vulnerable compared to adults. Ingestion of K. mikimotoi depressed the grazing of copepods but significantly induced the generation of reactive oxygen species (ROS), total antioxidant capacity, activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), and acetylcholinesterase. Under sublethal concentrations for two generations, K. mikimotoi reduced the fitness of copepods by prolonging development time and decreasing successful development rate, egg production, and the number of clutches. Our findings suggest that the bloom of K. mikimotoi may threaten copepod population recruitment, and its adverse effects are associated with oxidative stress

Polyadenylation of 18S rRNA in algae

National Science Foundation [EF-0626678]; State Key Laboratory of Marine Environmental Science, Xiamen University, ChinaPolyadenylation is best known for occurring to mRNA of eukaryotes transcribed by RNA polymerase II to stabilize mRNA molecules and promote their translation. rRNAs transcribed by RNA polymerase I or III are typically believed not to be polyadenylated. However, there is increasing evidence that polyadenylation occurs to nucleus-encoded rRNAs as part of the RNA degradation pathway. To examine whether the same polyadenylation-assisted degradation pathway occurs in algae, we surveyed representative species of algae including diatoms, chlorophytes, dinoflagellates and pelagophytes using oligo (dT)-primed reversed transcription PCR (RT-PCR). In all the algal species examined, truncated 18S rRNA or its precursor molecules with homo- or hetero-polymeric poly(A) tails were detected. Mining existing algal expressed sequence tag (EST) data revealed polyadenylated truncated 18S rRNA in four additional phyla of algae. rRNA polyadenylation occurred at various internal positions along the 18S rRNA and its precursor sequences. Moreover, putative homologs of noncanonical poly(A) polymerase (ncPAP) Trf4p, which is responsible for polyadenylating nuclear-encoded RNA and targeting it for degradation, were detected from the genomes and transcriptomes of five phyla of algae. Our results suggest that polyadenylation-assisted RNA degradation mechanism widely exists in algae, particularly for the nucleus-encoded rRNA and its precursors