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Molecular characterization, expression and antibacterial function of a macin, HdMac, from <i>Haliotis discus hannai</i>
No full textMacins are a family of antimicrobial peptides, which play multiple roles in the elimination of invading pathogens. In the present study, a macin was cloned and characterized from Pacific abalone Haliotis discus hannai (Designated as HdMac). Analysis of the conserved domain suggested that HdMac was a new member of the macin family. In non-stimulated abalones, HdMac transcripts were constitutively expressed in all five tested tissues, especially in hemocytes. After Vibrio harveyi stimulation, the expression of HdMac mRNA in hemocytes was significantly up-regulated at 12 hr (P < 0.01). RNAi-mediated knockdown of HdMac transcripts affected the survival rates of abalone against V. harveyi. Moreover, recombinant protein of HdMac (rHdMac) exhibited high antibacterial activities against invading bacteria, especially for Vibrio anguillarum. In addition, rHdMac possessed binding activities towards glucan, lipopolysaccharides (LPS), and peptidoglycan (PGN), but not chitin in vitro. Membrane integrity analysis revealed that rHdMac could increase the membrane permeability of bacteria. Meanwhile, both the phagocytosis and chemotaxis ability of hemocytes could be significantly enhanced by rHdMac. Overall, the results showed that HdMac could function as a versatile molecule involved in immune responses of H. discus hannai
Epidermal oxysterols function as alarm substances in zebrafish
No full textAlarm substances signal imminent predation thread and enable anti -predation strategies. In shoaling fish, alarm cues diffuse from injured skins that induce intense fear and anti -predation behaviors in other members. While these "fear substances"are shown to be present in numerous fishes and thought to exist in roughly 8,000 Ostariophysan species, their chemical nature remains largely unknown. We posited that fish alarm cues comprise small compounds and induce specific behaviors characteristic of fish exposed to skin extracts. Using the behaviors as bioassays, we tracked the alarm function of zebrafish skin extract to two compounds, 24-methyl-5 a- cholestane-3 a, 7 a, 12 a, 24,28-pentahydroxy 28 -sulfate, an oxysterol sulfate, and 5 a- cyprinol sulfate. At concentrations of less than one nanomolar, each compound induced antipredator behaviors and increased cortisol levels in zebrafish. Their mixture, at the natural ratio, replicated the skin extract in eliciting the full suite of anti -predator behavior patterns. Our findings reveal a molecular mechanism whereby fish escape predation danger
Environmentally friendly anti-biofouling polymeric membrane potentiometric sensors based on imprinted receptors
No full textPolymeric membrane potentiometric sensors using molecularly imprinted polymer (MIP) receptors are an ideal tool for determination of organic ionic species. However, their applications in complicated samples are very limited because of occurrence of sensor biofouling. Herein, for the first time, we describe a simple but environmentally friendly strategy to improve anti-biofouling performance of MIP-based potentiometric sensors. The non-toxic, environmentally friendly anti-fouling agent is doped into the polymeric membrane. The released organic biocidal agent from the polymeric membrane can kill the microorganisms adhered to the sensing membrane surface, and the formation of biofilms can thus be prevented. As a proof-the-concept experiment, an all-solid-state MIP-based potentiometric ceftiofur sensor is selected as a model. Capsaicin, a naturally occurring alkaloid derived from chillis, is chosen as a non-toxic biocide agent. Another widely used biocide agent 4,5dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) with low toxicity is also used as a comparison. Compared to the undoped electrode, the capsaicin-doped MIP sensor exhibits remarkably improved anti-biofouling abilities in terms of the low survival rates and the low adhesion rates of the bacterial cells and microalgae. Especially, the capsaicin-based electrode displays similar anti-fouling and response properties to the DCOIT-based one. It can be anticipated that such anti-fouling strategy may lay the foundation for development of "green" anti-fouling sensors, which are urgently required in marine monitoring and clinical diagnosis
Morphological, Microstructural, and In Situ Chemical Characteristics of Siderite Produced by Iron-Reducing Bacteria
No full textDissimilatory iron-reducing bacteria (DIRB) oxidize organic matter or hydrogen and reduce ferric iron to form Fe(II)-bearing minerals, such as magnetite and siderite. However, compared with magnetite, which was extensively studied, the mineralization process and mechanisms of siderite remain unclear. Here, with the combination of advanced electron microscopy and synchrotron-based scanning transmission X-ray microscopy (STXM) approaches, we studied in detail the morphological, structural, and chemical features of biogenic siderite via a growth experiment with Shewanella oneidensis MR-4. Results showed that along with the growth of cells, Fe(II) ions were increasingly released into solution and reacted with CO32- to form micrometer-sized siderite minerals with spindle, rod, peanut, dumbbell, and sphere shapes. They are composed of many single-crystal siderite plates that are fanned out from the center of the particles. Additionally, STXM revealed Fh and organic molecules inside siderite. This suggests that the siderite crystals might assemble around a Fh-organic molecule core and then continue to grow radially. This study illustrates the biomineralization and assembly of siderite by a successive multistep growth process induced by DIRB, also provides evidences that the distinctive shapes and the presence of organic molecules inside might be morphological and chemical features for biogenic siderite
Increasing food and feed self-sufficiency and avoiding manure N surplus in eastern regions of China through a spatial crop-livestock optimisation model
No full textCONTEXT: As the largest emerging economy globally, China is facing crop-livestock disconnection, which causes unnecessary synthetic fertiliser use, local food and feed unsatisfied demand, and manure nitrogen (N) surplus. OBJECTIVE: We investigated how crop-livestock regional integration combined with inter-regional transportation of food, feed, and manure, can contribute to food self-sufficiency of easter China (whole and regional level) while avoiding manure N excess. We also investigated how this could increase the local soybean production without harming the self-sufficiency of other food commodities. METHODS: We proposed an optimisation model of integrated crop-livestock production in eastern China, including the production of food, feed, and livestock manure N in each region and the demand for food (according to healthy diet recommendations), feed and manure N. We optimised the supplier cost-benefit balance considering food and feed production, domestic transportation, and foreign trade, taking food and feed demand satisfaction and manure N surplus avoidance as constraints. This optimisation exercise was performed under different scenarios: optimisation without soybean subsidies (scenario O), optimisation with increasing soybean subsidies (scenario OS+). The two scenarios were compared with the baseline scenario B (non-optimised without soybean subsidies) using balance indices (BI, the gap between production and demand divided by demand) of food, feed, and manure N and transportation indices. RESULTS AND CONCLUSIONS: Results showed that, for the whole of eastern China, BI were positive for cereals (1.523), vegetables (2.789), meat (0.002), eggs (0.002), milk (0.102), and maize (0.244), and negative for manure N (-0.016) in scenario O. This indicated that most of the food and feed items except soybean were selfsufficient and manure N surplus was avoided after optimisation. Some regions lowered their self-sufficiency for some commodities. As soybean subsidies increased from 0 Yuan center dot ton-1 to 6000 Yuan center dot ton- 1, the BI of soybeans increased by 66.37%. SIGNIFICANCE: Our results suggested that crop and livestock can be integrated in China for an improved level of food self-sufficiency and manure N surplus avoidance. However, regional self-sufficiency could not be achieved in all regions for all items, and transportation is necessary. In particular, three strategies seem relevant for policymaking: (i) decreasing livestock quantity, for strengthening feed self-sufficiency and avoiding manure N surplus; (ii) increasing soybean production through subsidies; (iii) reducing regional -level self-sufficiency and increasing the transportation for meat and eggs, which would avoid manure N surplus in densely populated regions, while decreasing the maize transportation
<i>Chlorella emersonii</i> Inoculation Improves Pakchoi Yield and Nitrogen Use Efficiency Through Amending the Rhizosphere Microbial Community
No full textAn experiment of pakchoi after conventional fertilization was conducted with Chlorella emersonii inoculation. The yield, nitrogen use efficiency, and rhizosphere microbial community of pakchoi were investigated, and the relationship among them was also determined. The results showed that C. emersonii inoculation with half dose increased the fresh weight and nitrogen use efficiency of pakchoi by 6.5% and 28.1%, respectively. Rhizosphere microbial community structure after C. emersonii inoculation was distinctly affected, which reflected the higher bacterial alpha diversity and lower fungal alpha diversity, and had positive and negative correlations with pakchoi performance characteristics, respectively. The dominant phyla showed that C. emersonii inoculation significantly increased the abundance of Proteobacteria and decreased the abundance of Actinobacteria for bacteria, however, all fungal abundances also decreased. At a higher classification resolution, C. emersonii inoculation enriched the indigenous Sphingomonas and introduced the nonindigenous Pseudofulvimonas involved in the nitrogen cycle, which might be responsible for the improvement of pakchoi yield by enhancing nitrogen use efficiency. The higher bacterial alpha diversity with enriched Sphingomonas and Pseudofulvimonas might provide a driving force for the greater pakchoi yield and nitrogen use efficiency under the half dose of C. emersonii inoculation compared with the total dose. This study suggested that C. emersonii inoculation improved the yield and nitrogen use efficiency of pakchoi through the amendment of beneficial rhizosphere microflora, especially those related to the nitrogen cycle, and confirmed the positive effectiveness of conventional fertilization regimes together with C. emersonii inoculation on fertilization efficiency and agricultural production
Research progress on the biosynthesis, activity and application of natural tetrapyrrole compounds
No full textTetrapyrrole compounds play vital roles in the life processes of animals and plants, such as respiration and photosynthesis, due to their functions in light energy capture and transmission, signal transduction, binding and transport of oxygen, their research originated from the study of heme and chlorophyll chemistry. The special structure of tetrapyrrole determines its various properties, which contribute to its antioxidant, antiinflammatory, antitumoral, antibacterial, neuroprotective and other biological activities. Although many functions of tetrapyrrole compounds have been excavated and utilized, there is a lack of a complete system to summarize them. This review summarizes the biosynthesis, functional evolution, biological activities and optical applications of tetrapyrrole compounds based on existing research on tetrapyrrole compounds
Salinity Acclimation Induces Reduced Energy Metabolism, Osmotic Pressure Regulation and Transcriptional Reprogramming in Hypotrichida Ciliate <i>Gastrostyla setifera</i>
No full textCoastal and estuarine protists are frequently exposed to salinity undulation. While the tolerance and stress responses of microalgae to salinity have been extensively studied, there have been scarce studies on the physiological response of heterotrophic protists to salinity stressing. In this study, we investigated the physiological response of the heterotrophic ciliate Gastrostyla setifera to a salinity of 3, via a transcriptomic approach. The first transcriptome of genus Gastrostyla was obtained utilizing a group of manually isolated ciliate individuals (cells) and RNA-seq technique. The completeness of the transcriptome was verified. Differentially expressed gene (DEG) analysis was performed among the transcriptomes of G setifera acclimated in saline water (salinity 3) and those cultured in fresh water. The results demonstrated a significant alternation in gene transcription, in which the ciliate exhibits a transcripttomic acclimation in responding salinity stressing. The up-regulated DEGs were enriched in the pathways of cytoskeleton proteins, membrane trafficking, protein kinases and protein phosphatases. These may represent enhanced functions of ion transport, stress response and cell protections. Pathways involved in energy metabolism and biosynthesis were markedly down-regulated, reflecting decreased cell activity. Particularly, we detected significantly down-regulated genes involved in several pathways of amino acid catabolism, which may lead to accumulation of amino acids in the ciliate cell. Amino acid could act as compatible solutes in the cytoplasm to maintain the osmotic balance in saline water. Overall, this work is an initial exploration to the molecular basis of the heterotrophic protist responding to salinity stressing. The result sheds light on the mechanisms of enhancement of cell protection, reduction of cell activity, and osmotic pressure regulation in ciliates acclimated to salinity
Sulfides in waters could be converted to pyrites through mineralization with Fe/MgO/Ni(II) promotion
No full textCurrent sulfide removal techniques are generally associated with secondary pollution. In this work, Fe/MgO/Ni (II) system was constructed to remove sulfide from waters thoroughly by transforming it into stable pyrite (FeS2). The transformation could be finished quickly through the promotion of Ni2+ at all pH conditions, and the optimal Ni/Fe molar ratio was 1.0. The FeS2 could be formed in 360 min and the reaction was finished at 600 min when the initial concentration of sulfide and Ni2+ was 181.95 mg/L and 164.52 mg/L, respectively. The highest content of SO42- was merely 2.06 %, while the content of S2O32- /SO32- increased with reaction (56.99 %-67.21 %) in the whole process. The content of sulfide and Ni2+ in the solution were not detected after reaction. The mineralization process was not affected by sodium salt addition, however, it was greatly affected by calcium salt, where the ascensional range of S2O32-/SO32- and SO42- was 50.03 %-70.06 % and 9.84 %-14.76 %, respectively, and the content of sulfide on Fe/MgO was only 14.66 %. Higher temperature would produce more SO42- and H+. The rapid formation mechanism of FeS2 was mainly through Ni2+ substituting Fe in FeS to form Ni-doped FeS precursors that reacted with polysulfide and then promoted the nucleation of FeS2, in the meantime, the reaction to form S2O32-/SO32-, SO42-, Ni(OH)2 and H+ also were generated in this process. This study provides a new insight for the efficient treatment of sulfide containing wastewater
Long-Emission-Wavelength Humic-Like Component (L-HULIS) as a Secondary Source Tracer of Brown Carbon in the Atmosphere
No full textThe optical properties of secondary brown carbon (BrC) aerosols are poorly understood, hampering quantitative assessments of their impact. We propose a new method for estimating secondary source of BrC using excitation-emission matrix (EEM) fluorescence spectroscopy, combined with parallel factor analysis (PARAFAC) and partial least squares regression (PLSR). Experiments were conducted on a collection of PM2.5 samples from urban areas in five Chinese cities during winter and summer. The humic-like component with long-emission wavelengths (L-HULIS) was identified as a secondary source tracer of BrC. This was confirmed by correlating PARAFAC components with secondary organic aerosol tracers and molecular oxidation indices obtained from Fourier transform ion cyclotron resonance mass spectrometry analysis. Using L-HULIS as a secondary tracer of BrC, it was determined that the contribution of secondary sources to water-soluble BrC (WS-BrC) in source emission samples is significantly smaller than in PM2.5 from five Chinese cities, supporting our method. In the five cities, secondary source derived via L-HULIS contributes a dominant potion (80% +/- 3.5%) of WS-BrC at 365 nm during the summer, which is approximately twice as high as during the winter (45% +/- 4.9%). Radiocarbon isotope (14C) analysis provides additional constraints to the sources of L-HULIS-derived secondary WS-BrC in urban PM2.5, suggesting that aged biomass burning is the dominant contributor to secondary WS-BrC in winter, and biogenic emission is dominant during summer. This study is the first report on identification of secondary sources of BrC using the fluorescence technique. It demonstrates the potential of this method in characterizing non-fossil source secondary BrC in the atmosphere.
Brown carbon (BrC) originates from primary combustion emissions and secondary formation, with large source-dependent uncertainties of radiative forcing. Direct measurements to separate the primary and secondary BrC are challenging due to the chemical complexity. Recent online studies have shown that excitation-emission matrix fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis identified some fluorescent components that may be linked to secondary sources. However, there is a knowledge gap on whether PARAFAC components correlate closely with atmospheric secondary chemical components, particularly biogenic and anthropogenic secondary organic aerosol, as their precursors can also form secondary BrC chromophores. We established the correlations between PARAFAC components and secondary organic aerosol tracers and compound oxidations to identify the long-emission-wavelength humic-like component as a secondary source tracer of BrC. Then, we estimated non-fossil source secondary BrC in urban aerosols during the winter and summer. Our studies provide references for quantifying secondary sources of BrC in the atmosphere.
A fluorescence-based method was developed to investigate secondary sources of water-soluble brown carbon in five cities in China The contribution of secondary sources to water-soluble brown carbon in the summer is approximately twice as high as during the winter This secondary water-soluble brown carbon was more associated with aging biomass burning in winter and biogenic emissions in summe