[Community Characteristics of Methanogens and Methanogenic Pathways in Salt-tolerant Rice Soil].

It is known that methanogens play a critical role in the carbon cycle in soil, while methanogen community characteristics and their environmental influencing factors in the soil planted with salt-tolerant rice remain unclear. In this study, methanogen abundance, community composition, and relationships with environmental factors in soils planted with the salt-tolerant rice (YC1703) and ordinary rice (Lindao 10) were evaluated in the rice improvement demonstration base of Qingdao Wisdom Agricultural Industry using real-time fluorescence quantitative PCR and Illumina high-throughput sequencing. The results indicated that the abundance and community richness of methanogens in Lindao 10 soil were significantly higher than those in YC1703 soil, and methanogens in YC1703 soil exhibited higher diversity. The combined effects of rice varieties, rice growth period, and environmental factors had impacts on the methanogen community. The hydrogenotrophic methanogens were dominant in the YC1703 and Lindao 10 soils; thus, we speculated that the dominant pathway of methane production in these soils was hydrogenotrophic methanogenesis.

[Differences Between DNA- and RNA-Based Bacterial Communities in Marine Sediments].

Microorganisms in marine sediments play crucial roles in biogeochemical processes. Currently, 16S rRNA gene-based sequencing is popular for studying bacterial communities; however, the DNA used in analysis can include not only that from active microorganisms but also that from inactive microorganisms, while the RNA can represent active microorganisms and more recent activity in the environment; therefore, a study of the difference between the total bacterial community based on the 16S rRNA gene and the active bacterial community based on 16S rRNA will support a better understanding of bacterial community structure and function in marine sediments. In this study, the total and active bacterial community structures in surface sediments from the Bohai Sea and South Yellow Sea were investigated at DNA and RNA level using quantitative real-time polymerase chain reaction and Illumina high-throughput sequencing, respectively. The results show that the 16S rRNA gene abundances of bacterial communities are 1-2 orders of magnitude higher than the transcript abundances. The total bacterial community is more diverse compared to the active bacterial community, and there are distinct differences between them. The bacteria in the sediments take part in active chemoheterotrophy, sulfate reduction, and nitrification. Moreover, 16S rRNA gene-based sequencing misestimates some important functional microbiota when exploring bacterial community functions. The 'rare biosphere' in the total bacterial communities consists of actively transcriptional players, which could play key roles in biogeochemistry cycles. Overall, in the analysis of bacterial communities in marine sediments from a stable sedimentary environment, it is beneficial to use the 16S rRNA sequencing to reflect the true ecological status.

[Effects of salinity on the survival and asexual reproduction of Aurelia coerulea polyps at different temperatures]. / ç›åº¦å¯¹ä¸åŒæ¸©åº¦ä¸‹æµ·æœˆæ°´æ¯èž çŠ¶ä½“å­˜æ´»å’Œæ— æ€§ç¹æ®–çš„å½±å“.

The scyphozoan genus Aurelia is one of the main contributors causing jellyfish blooms in global coastal waters. The population and reproduction of polyps are important factors to the outbreak of jellyfish. In this study, the effects of different salinity on the survival and asexual reproduction of Aurelia coerulea polyps were explored, which were cultured at the high (21 ℃) and low temperature (12 ℃), respectively. The results showed that more than 90% polyps could survive in the salinity range of 15-40 at the high temperature, with a range of salinity for budding being 20-32 and an optimum value of 28. The polyps were able to produce podocysts to tolerate low (≤15) and high (≥36) salinity conditions. At the low temperature, the survival rates of polyps were more than 90% in the salinity range of 20-40. The polyps could produce more buds in the salinity range of 20-32, with an optimum of 28. The salinity range of 20-40 was suitable for strobilation, with an optimum range of 28-32. It is concluded that the polyps of Aurelia coerulea can tolerate wide salinity variations, and that the salinity in a certain range has no significant influence on the asexual reproduction of polyps.

[Analysis of Sulfate-Reducing and Sulfur-Oxidizing Prokaryote Community Structures in Marine Sediments with Different Sequencing Technologies].

Sulfate-reducing prokaryotes (SRP) and sulfur-oxidizing prokaryotes (SOP) play vital roles in the sulfur cycle. The SRP community was used to represent a microbial community with high richness and diversity. The 454 pyrosequencing, Illumina high-throughput sequencing, and traditional clone library methods that target the dissimilatory sulfite reductase ß subunit gene (dsrB), which encodes a key enzyme in the sulfate reduction pathway, were used to compare the differences in SRP community characteristics. Comparative analyses suggested that Illumina high-throughput sequencing was a more appropriate method for SRP (high richness and diversity) community studies. The SOP soxB gene (~750 bp) was used as a representative of the long-sequence segment. The 454 pyrosequencing and Illumina high-throughput sequencing methods were used to compare the differences in SOP community characteristics. The results revealed that 454 pyrosequencing did not reflect its advantage of a longer read length; whereas, the Illumina high-throughput sequencing with more numerous and shorter sequence reads was more suitable when the soxB gene was used to investigate the community composition and diversity of SOP.

[Distribution Characteristics of Anaerobic Ammonia Oxidation Bacteria in Sediments from the Adjacent Seas of Yangtze Estuary].

Marine nitrogen cycle is of great significance to maintain the marine ecological balance. Anaerobic ammonia oxidation (ANAMMOX) process driven by anaerobic ammonia-oxidizing bacteria is an important way of promoting the marine nitrogen removal. In this study, quantitative PCR (qPCR), combining with environmental factors analysis, were used to study the distribution of ANAMMOX bacteria in the sediments from Yangtze River Estuary and its adjacent waters in summer, 2011. The results showed that the spatial abundance distribution of ANAMMOX bacteria was closely related to environmental factors. Total organic carbon, salinity, and concentration of ammonium played vital roles in regulating ANAMMOX bacteria abundances in this area. The abundance distribution of ANAMMOX bacteria was significantly positively correlated with total organic carbon content (P<0.01,r=0.69), reducing along with the increasing concentration of nitrite and DO, while the influence from salinity was complicated.

[Distribution of Aerobic Ammonia-Oxidizing Microorganisms in Sediments from Adjacent Waters of Rushan Bay].

Nitrogen cycle is a key process in material circulation of marine ecosystem, which plays an important role in maintaining ecological balance. The ammonia oxidation process promoted by aerobic ammonia-oxidizing microorganism (AOM) is a rate-limiting step of nitrification. Real-time quantitative polymerase chain reaction (qPCR ), along with the determination of potential nitrification rates (PNR) was carried out in this study to understand the distribution of AOM in sediments of adjacent waters of Rushan Bay in August, 2014. The results indicated that the abundance of total ammonia-oxidizing bacteria (AOB) was always greater than that of total ammonia-oxidizing archaea (AOA) in the three sampling stations; the ratio of active AOB to total AOB was less than 1%, while no active AOA was detected in this study; the PNR significantly decreased after adding ampicillin which could inhibit the activity of AOB (P < 0.05). It was speculated that AOB might play a more important role in the ammonia oxidation in sediments of adjacent waters of Rushan Bay in August, 2014. Dissolved oxygen concentrations, temperature and ammonium concentrations played a significant role in distribution of AOM in sediments of adjacent waters of Rushan Bay.

[Molecular identification and detection of moon jellyfish (Aurelia sp.) based on partial sequencing of mitochondrial 16S rDNA and COI].

Taking the moon jellyfish Aurelia sp. commonly found in our coastal sea areas as test object, its genome DNA was extracted, the partial sequences of mt-16S rDNA (650 bp) and mt-COI (709 bp) were PCR-amplified, and, after purification, cloning, and sequencing, the sequences obtained were BLASTn-analyzed. The sequences of greater difference with those of the other jellyfish were chosen, and eight specific primers for the mt-16S rDNA and mt-COI of Aurelia sp. were designed, respectively. The specificity test indicated that the primer AS3 for the mt-16S rDNA and the primer AC3 for the mt-COI were excellent in rapidly detecting the target jellyfish from Rhopilema esculentum, Nemopilema nomurai, Cyanea nozakii, Acromitus sp., and Aurelia sp., and thus, the techniques for the molecular identification and detection of moon jellyfish were preliminarily established, which could get rid of the limitations in classical morphological identification of Aurelia sp. , being able to find the Aurelia sp. in the samples more quickly and accurately.

[Optimization of real-time quantitative fluorescence PCR system in detecting cytochrome b gene of Prorocentrum donghaiense Lu].

To quantitatively detect the cytochrome b (Cyt b) gene of Prorocentrum donghaiense Lu in the filed samples, a specific primer was designed, and the quantities of the RNA templates added into the reaction system for reverse transcription as well as the reaction conditions of real-time fluorescent quantitative PCR (RFQ-PCR) were optimized. The results illustrated that the designed primer had good specificity, being able to be used to differentiate different algal species effectively. In detecting the filed samples, the suitable qualities of the templates for the 20 microL reverse transcription system were 50-200 ng. 10-fold diluting the templates or adding the bovine serum albumin (BSA) with a final concentration 0.2 microg.microL-1 into the RFQ-PCR system could effectively decrease the inhibitory effect of the inhibitors in the filed samples, and thus, decrease the interferences. The established real-time fluorescent quantitative PCR (RFQ-PCR) assay would facilitate us to study the intrinsic mechanisms of P. donghaiense outbreak and extinction at molecular level.

[Detection of Prorocentrum minimum (Pavillard) Schiller with the electrochemiluminescence-molecular probe].

In this study, the electrochemiluminescence-molecular probe (ECL-MP) was established based on the sandwich hybridization integrated with nuclease protection assay (NPA-SH) improved by electrochemiluminescence (ECL). It can be used for detecting Prorocentrum minimum (Pavillard) Schiller qualitatively and quantitatively. NPA probes of P. minimum were designed based on the NPA-SH. After labeled with Ru (bpy)3(2+) and biotin, they bounded with streptavidin-coupled magnetic beads and generated electrochemiluminescence in an ECL analyzer. The ECL counts per second (CPS) was drawn against the cell number obtained from microscopy to establish a calibration curve of P. minimum. The results showed that the labeled NPA probes had good specificity and practicability, the optimal usage of magnetic beads was 4 microg for detecting 20 microL hybridization mixture, the detection range of P. minimum cell numbers was 6.25 x 10(2) - 4 x 10(4), and there was no significant difference between the data gained from ECL-MP and microscopy with 95% confidence level (t-test) when treated with cultured and mixed samples. ECL-MP was a convenient new tool for rapid assessment of P. minimum in marine environment.

[Construction of electrochemiluminescence system for harmful algae detection].

To develop a new technique, Electrochemiluminescence-Molecular Probe (ECL-MP), for harmful algae detection, a highly sensitive electrochemiluminescence (ECL) detection system was set up based on the principle of ECL and related literature. The optimization tests were carried out, including the impact of voltage and current, the concentration of tripropylamine (TPrA) and the pH of phosphate buffer (PBS). The determination limit of Ru (bpy)3Cl2 x 6H2O was 10(-11) mol x L(-1) and the detection range was from 10(-9) - 10(-5) mol x L(-1) as well as the detection amount of substance was in the range from 0.4 pmol-4 nmol in the optimal reaction conditions with voltage of 1.0 V, current of 1.0 mA, TPrA concentration of 1.5 mol x L(-1) and pH of 7.4. It was proved by facts that this ECL analyzer was stable and highly sensitive, which was helpful in establishment of ECL-MP.

[Research advances in the effects of environmental factors on the growth and development of Aurelia spp].

Aurelia spp. is a cosmopolitan coastal species, and also, one dominant species of large jellyfish in the coastal waters of China. In recent years, Aurelia spp. bloom events occur frequently in the world, causing severe damage to marine ecosystems, coastal economy, and society development. Aurelia spp. has a complicated life history comprising a benthic asexually-reproducing polyp generation and a sexually-reproducing medusa generation, and various vegetative reproduction (budding, strobilation, and podocyst production) and sexual reproduction. Surrounding physical and biological factors affect each growth stage of Aurelia spp., especially the juvenile stage of planktonic-benthic life cycle, which has major effect on the population dynamics of Aurelia spp. This paper reviewed the research advances in the effects of environmental factors on Aurelia spp. at its different growth and development stages, and discussed some problems worthy of further study, aimed to provide useful reference for the research of the key factors controlling the jellyfish blooms in coastal waters of China.

[Effect of the first water-sediment regulation on the variations of dissolved inorganic nutrients' concentrations and fluxes in the lower main channel of the Yellow River].

The variations and fluxes of dissolved inorganic nutrients were studied, based on continuously monitored data in the lower main channel of Yellow River (Lijin) during the period of water-sediment regulation in July 2002. Concentrations rang from 169.3 to 273.2 micromol x dm(-3) for NO3- -N, 0.08 to 0.84 micromol x dm(-3) for NO2- -N, 1.39 to 5.04 micromol x dm(-3) for NH4+ -N, with average of 218.6, 0.16, 2.27 micromol x dm(-3), respectively. Concentrations rang from 0.36 to 0.56 micromol x dm(-3) for PO4(3-) -P, 161.4 to 195.8 micromol x dm(-3) for SiO3(2-) -Si, with average of 0.48, 166.7 micromol x dm(-3), respectively. No significant relationship was found between nitrate, phosphate and water discharge during the period of water-sediment regulation, while silicate correlated well with suspended sediment discharge. Water-sediment regulation has no significant effect on the variation of dissolved inorganic nutrients concentrations during 2002 to 2003. But the fluxes proportion of dissolved inorganic nutrients during water-sediment regulation to the whole year is about 50%.

[Distributions of dissolved inorganic mercury in the lower part of the Three Gorges Reservoir].

One year after the first filling stage of the Three Gorges Reservoir(TGR), dissolved inorganic mercury (Hg(DI)) was measured in August 2004. Concentration of Hg(DI) varied from undetection to 82.6 ng x L(-1) with average of 22.7 ng x L(-1). Stratification of Hg(DI) in the TGR was obviously. Concentrations of Hg(DI) were much higher in the layers above 20 m than in deep waters. Concentration of Hg(DI) in the Xiangxi River varied from undetection to 61.4 ng x L(-1) with average of 18.0 ng x L(-1). The Hg(DI) concentration increased obviously after the filling of the TGR. Large amount of Hg was retented with the deposition of sediment in the TGR. The retention of Hg by the TGR needs the further research.