Metabarcoding reveals a high diversity and complex eukaryotic microalgal community in coastal waters of the northern Beibu Gulf, China.

Beibu Gulf is an important semi-enclosed bay located in the northwestern South China Sea, and is famous for its high bio-productivity and rich bio-diversity. The fast development along the Beibu Gulf Economical Rim has brought pressure to the environment, and algal blooms occurred frequently in the gulf. In this study, surface water samples and micro-plankton samples (20-200 µm) were collected in the northern Beibu Gulf coast. Diversity and distribution of eukaryotic planktonic microalgae were analyzed by both metabarcoding and microscopic analyses. Metabarcoding revealed much higher diversity and species richness of microalgae than morphological observation, especially for dinoflagellates. Metabarcoding detected 144 microalgal genera in 8 phyla, while microscopy only detected 40 genera in 2 phyla. The two methods revealed different microalgal community structures. Dinoflagellates dominated in microalgal community based on metabarcoding due to their high copies of 18 s rRNA gene, and diatoms dominated under microscopy. Altogether 48 algal bloom and/or toxic species were detected in this study, 34 species by metabarcoding and 19 species by microscopy. Our result suggested a high potential risk of HABs in the Beibu Gulf. Microalgal community in the surface water samples demonstrated significantly higher OTU/species richness, alpha diversity, and abundance than those in the micro-plankton samples, although more HAB taxa were detected by microscopic observations in the micro-plankton samples. Furthermore, nano-sized taxa, such as those in chlorophytes, haptophytes, and chrysophyceans, occurred more abundantly in the surface water samples. This study provided a comprehensive morphological and molecular description of microalgal community in the northern Beibu Gulf.

Anticancer potential of grifolin in lung cancer treatment through PI3K/AKT pathway inhibition.

Objective: Grifolin is a natural secondary metabolite isolated from edible fruiting bodies of the mushroom Albatrellus confluens. Grifolin has antitumor activities in several types of cancer. We aimed to determine the effects of grifolin on lung cancer. Methods: We determined the proliferation, migration, invasion, and apoptosis of lung cancer cells using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Ethynyl deoxyuridine, colony formation, wound scratch, transwell, flow cytometry, and xenograft mouse assays. Molecular docking evaluated the binding relation between grifolin and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA). The levels of PIK3CA, AKT, and p-AKT were measured by western blot. Results: Grifolin (10, 20, or 40 µM) inhibited the proliferation, migration, and invasion of lung cancer cells, and induced cell cycle arrest and apoptosis. Grifolin also decreased CDK4, CDK6, and CyclinD1 expression and significantly decreased PIK3CA and p-AKT expression in lung cancer cells. These anticancer effects were abolished by 740Y-P. Conclusions: Grifolin regulates the PI3K/AKT pathway, thus inhibiting lung cancer progression.

Mimicking pneumonia with septic shock: A case report and literature review.

Hydrochlorothiazide (HCTZ) is a commonly used diuretic antihypertensive drug that can cause electrolyte disorders, hyperglycemia and hyperuricemia as well as rare life-threatening adverse drug reactions. These include non-cardiogenic pulmonary edema, interstitial pneumonia, angioedema and aplastic anemia. The present report describes a case of a 59-year-old man who developed a hypersensitivity reaction to HCTZ. Specifically, the patient presented with symptoms of cough, chest tightness and shortness of breath, with pneumonic consolidation on chest CT and elevated levels of white blood cell count, neutrophil percentage, C-reactive protein and procalcitonin. A presumptive diagnosis of severe pneumonia was made initially. However, during the gradual recovery of the patient through treatment, he mistakenly ingested HCTZ containing losartan potassium intended for another patient, which resulted in symptoms similar to those observed upon admission. Upon further inquiry into the medical history, it was revealed that the patient had also taken irbesartan/HCTZ 4 h prior to hospitalization. There was no evidence of a pathogenic infection. Therefore, HCTZ-induced anaphylactic reaction was considered to be the most likely etiology for his severe shock. Treatments including epinephrine, methylprednisolone and respiratory support were administered. After 7 days, the patient was transferred from the Respiratory Intensive Care Unit [The Affiliated Jiangning Hospital of Nanjing Medical University (Nanjing, China)] to a general ward. During the follow-up, 12 months after advising the patient to discontinue HCTZ, there had been no recurrence of the aforementioned symptoms. At the time of publication, the patient is currently alive.

An Intriguing Structural Modification in Neutrophil Migration Across Blood Vessels to Inflammatory Sites: Progress in the Core Mechanisms.

The role and function of neutrophils are well known, but we still have incomplete understanding of the mechanisms by which neutrophils migrate from blood vessels to inflammatory sites. Neutrophil migration is a complex process that involves several distinct steps. To resist the blood flow and maintain their rolling, neutrophils employ tether and sling formation. They also polarize and form pseudopods and uropods, guided by hierarchical chemotactic agents that enable precise directional movement. Meanwhile, chemotactic agents secreted by neutrophils, such as CXCL1, CXCL8, LTB4, and C5a, can recruit more neutrophils and amplify their response. In the context of diapedesis neutrophils traverse the endothelial cells via two pathways: the transmigratory cup and the lateral border recycling department. These structures aid in overcoming the narrow pore size of the endothelial barrier, resulting in more efficient transmembrane migration. Interestingly, neutrophils exhibit a preference for the paracellular pathway over the transcellular pathway, likely due to the former's lower resistance. In this review, we will delve into the intricate process of neutrophil migration by focusing on critical structures that underpins this process.

CircUBR1 knockdown relieves ventilator-induced lung injury through regulating miR-20a-5p/GGPPS1 pathway.

OBJECTIVE: To assess the influences and underlying mechanism of circular RNA UBR1 (circUBR1) in ventilator-induced lung injury (VILI). METHODS: In mice and mouse alveolar epithelial cells, VILI model was established. CircUBR1 and miR-20a-5p expression was assessed via quantitative real time polymerase chain reaction. Western blot and immunohistochemistry were applied to assess geranylgeranyl diphosphate synthase 1 (GGPPS1) protein expression. In lung tissues, the histopathological changes were utilized using hematoxylin and eosin staining. Cell counting kit-8 assay and flow cytometer were applied to detect cell proliferation and apoptosis. The levels of inflammatory cytokines [interleukin (IL)-1ß, IL-18, IL-6, and tumor necrosis factor (TNF)-α] were measured by western blot and enzyme-linked immunosorbent assay. RESULTS: In lung tissues of VILI mice, circUBR1 and GGPPS1 expression were upregulated, while miR-20a-5p expression was downregulated. In vivo, circUBR1 knockdown alleviated lung injury, inhibited cell apoptosis, and decreased the levels of inflammatory cytokines. In cells treated with cyclic stretch (CS), circUBR1 knockdown promoted cell viability, inhibited cell apoptosis, and reduced inflammatory cytokines. CircUBR1 could sponge miR-20a-5p, and GGPPS1 was the target gene of miR-20a-5p. In addition, in cells treated with CS, downregulation of miR-20a-5p or the overexpression of GGPPS1 reversed the promotive effect of circUBR1 knockdown on cell viability and the inhibitive effect of circUBR1 knockdown on cell apoptosis and inflammation production. CONCLUSIONS: In VILI, knockdown of circUBR1 attenuated lung injury and inflammation via regulating the miR-20a-5p/GGPPS1 pathway. Our study may provide a potential therapeutic target for treatment of VILI.

Ceftazidime-assisted synthesis of ultrasmall chitosan nanoparticles for biofilm penetration and eradication of Pseudomonas aeruginosa.

Pseudomonas aeruginosa (P. aeruginosa) infections present a grave threat to immunocompromised individuals, particularly those with cystic fibrosis due to the development of bacterial biofilms. In this study, we engineered self-assembling chitosan-ceftazidime nanoparticles (CSCE) capable of effectively penetrating biofilms and eradicating P. aeruginosa. The CSCE nanoparticles were synthesized through ionic cross-linking, combining negatively charged ceftazidime with positively charged chitosan, resulting in uniform nanoparticles measuring approximately 40 nm in diameter, exhibiting high dispersity and excellent biocompatibility. Remarkably, these nanoparticles exhibited significant inhibition of P. aeruginosa growth, reduced pyocyanin production, and diminished biofilm formation, achieving a maximum inhibition rate of 22.44%. Furthermore, in vivo investigations demonstrated enhanced survival in mice with abdominal P. aeruginosa infection following treatment with CSCE nanoparticles, accompanied by reduced levels of inflammatory cytokines Interleukin-6 (125.79 ± 18.63 pg/mL), Interleukin-17 (125.67 ± 5.94 pg/mL), and Tumor Necrosis Factor-α (135.4 ± 11.77 pg/mL). Critically, mice treated with CSCE nanoparticles showed no presence of bacteria in the bloodstream following intraperitoneal P. aeruginosa infection. Collectively, our findings highlight the potential of these synthesized nanoparticles as effective agents against P. aeruginosa infections.

Extensive Carbon Contribution of Inundated Terrestrial Plants to Zooplankton Biomass in a Eutrophic Lake.

Organic carbon derived from terrestrial plants contributes to aquatic consumers, e.g., zooplankton in lakes. The degree of the contribution depends on the availability of terrestrial organic carbon in lake organic pool and the transfer efficiency of the carbon. Terrestrial organic carbon is poor-quality food for zooplankton with a mismatch of nutrition content and was incorporated to zooplankton with much lower efficiency than phytoplankton. Contributions of terrestrial carbon to zooplankton generally decrease with an increase in phytoplankton production, indicating a preferential incorporation of phytoplankton in previous investigations. However, in eutrophic lakes, the dominating cyanobacteria were of poor quality and incorporated to consumers inefficiently too. In that case, zooplankton in eutrophic wetlands, where cyanobacteria dominate the phytoplankton production and massive terrestrial plants are inundated, may not preferentially incorporate poor food-quality phytoplankton resource to their biomass. Therefore, we hypothesize that carbon contributions of terrestrial vegetation to zooplankton and to lake particulate organic pool should be similar in such aquatic ecosystems. We tested this hypothesis by sampling zooplankton and carbon sources in Ming Lake (Jinan University Campus, southern China) which was overgrown by terrestrial plants after drying and re-flooded. After 60 days of observations at weekly (or biweekly) intervals, applying stable carbon (13C), nitrogen (15 N), and hydrogen (2H) isotopic analysis and a stable isotope mixing model, we estimated the occurrence of extensive carbon contribution (≥ 50%) of flooded terrestrial plants to cladocerans and copepods. Contribution of inundated terrestrial plants to cladocerans was similar to that to lake particulate organic pool. Thus, our study quantified the role of terrestrial carbon in eutrophic wetlands, enhancing our understanding of cross-ecosystem interactions in food webs with an emphasis on the resource quality.

Knockout of GGPPS1 restrains rab37-mediated autophagy in response to ventilator-induced lung injury.

Mechanical ventilation may cause ventilator-induced lung injury (VILI) in patients requiring ventilator support. Inhibition of autophagy is an important approach to ameliorate VILI as it always enhances lung injury after exposure to various stress agents. This study aimed to further reveal the potential mechanisms underlying the effects of geranylgeranyl diphosphate synthase large subunit 1 (GGPPS1) knockout and autophagy in VILI using C57BL/6 mice with lung-specific GGPPS1 knockout that were subjected to mechanical ventilation. The results demonstrate that GGPPS1 knockout mice exhibit significantly attenuated VILI based on the histologic score, the lung wet-to-dry ratio, total protein levels, neutrophils in bronchoalveolar lavage fluid, and reduced levels of inflammatory cytokines. Importantly, the expression levels of autophagy markers were obviously decreased in GGPPS1 knockout mice compared with wild-type mice. The inhibitory effects of GGPPS1 knockout on autophagy were further confirmed by measuring the ultrastructural change of lung tissues under transmission electron microscopy. In addition, knockdown of GGPPS1 in RAW264.7 cells reduced cyclic stretch-induced inflammation and autophagy. The benefits of GGPPS1 knockout for VILI can be partially eliminated through treatment with rapamycin. Further analysis revealed that Rab37 was significantly downregulated in GGPPS1 knockout mice after mechanical ventilation, while it was highly expressed in the control group. Simultaneously, Rab37 overexpression significantly enhances autophagy in cells that are treated with cyclin stretch, including GGPPS1 knockout cells. Collectively, our results indicate that GGPPS1 knockout results in reduced expression of Rab37 proteins, further restraining autophagy and VILI.

Nutrient Regulation of Relative Dominance of Cylindrospermopsin-Producing and Non-cylindrospermopsin-Producing Raphidiopsis raciborskii.

Raphidiopsis raciborskii (previously Cylindrospermopsis raciborskii) can produce cylindrospermopsin (CYN) which is of great concern due to its considerable toxicity to human and animals. Its CYN-producing (toxic) and non-CYN-producing (non-toxic) strains co-exist commonly in natural water bodies, while how their relative dominance is regulated has not been addressed. In this study, we combined field investigation with laboratory experiments to assessed the relationship between toxic and non-toxic R. raciborskii abundances under different nutrient levels. The rpoC1- and cyrJ-based qPCR was applied for quantifying total and toxic R. raciborskii abundances, respectively. The field survey showed that toxic R. raciborskii was detected in 97 of 115 reservoirs where its proportion ranged from 0.3% to 39.7% within the R. raciborskii population. Both total and toxic R. raciborskii abundances increased significantly with trophic level of these reservoirs, consistent with our monoculture and co-culture experiments showing in an increase in R. raciborskii growth with increasing nitrogen (N) or phosphorus (P) concentrations. In the monoculture experiments, growth rates of non-toxic and toxic strains from Australia or China were not significantly different under the same culture conditions. On the other hand, in the co-culture experiments, the toxic strains displayed a significantly faster growth than non-toxic strains under nutrient-replete conditions, resulting in an obvious shift toward the dominance by toxic strains from day 3 to the end of the experiments, regardless of the strain originating from Australia or China. The reverse was found under N- or P-limited conditions. Our results indicated that the toxic strains of R. raciborskii have a competitive advantage relative to the non-toxic strains in a more eutrophic world. In parallel to an increase in dominance, both toxic strains grown in the mixed population significantly increased CYN production under nutrient-replete conditions as compared to nutrient-limited conditions, suggesting that CYN may be of significance for ecological advantage of toxic R. raciborskii. These results highlight the importance of nutrient availability in regulating abundances and strain dominance of two genotypes of R. raciborskii. Our findings demonstrated that elevated nutrients would favor the growth of CYN-producing R. raciborskii and CYN production, leading to more blooms with higher toxicity at global scale.

Filter-feeding fish (Hypophthalmichthys molitrix) mediated phosphorus recycling versus grazing pressure as drivers of the trophic cascade in large enclosures subsidized by allochthonous detritus.

Stocking of filter-feeding fish is a common tool used in (sub)tropical Chinese reservoirs to control phytoplankton. However, field investigations have showed that such stocking would enhance instead of controlling phytoplankton in these reservoirs. Reservoirs generally receive a considerable amount of detritus from their catchments which may constitute an important carbon source to filter-feeding fish. Whether direct consumption of detritus increases the availability of dissolved inorganic phosphorus (P) to phytoplankton and thereby provides resilience against the control of phytoplankton biomass is debated. We conducted an enclosure experiment in a (sub)tropical Chinese reservoir (Liuxihe Reservoir) to assess how a gradient of filter-feeding fish (Silver Carp Hypophthalmichthys molitrix) biomass affected P dynamics and fish grazing and predation when subsidized by allochthonous detritus. Fish had strong effects on the dynamics and fluxes of P. TP concentration in the water column increased over time in all enclosures, but the presence of fish slowed its increase. Thus, TP decreased with increasing fish biomass. Fish were a net sink of P to the water column, because they gained mass during the experiment. Moreover, P sequestered by fish could largely account for the lower TP concentrations observed in enclosures with fish compared to fishless enclosures. Fish presence at high biomass strongly reduced the abundance of large zooplankton species and P excretion by zooplankton. However, the negative effect of fish predation on zooplankton was negligible when fish was present at low biomass. Increasing fish biomass increased the relative role of fish in P cycling but decreased the overall P excretion by fish and zooplankton. Compared to enclosures with high fish biomass, both zooplankton grazing effect on phytoplankton (zooplankton: phytoplankton biomass ratio as a proxy) and the overall P excretion were much higher, whereas fish grazing effect on phytoplankton (fish: phytoplankton biomass ratio as a proxy), chlorophyll a and the yield of chlorophyll a per TP were much lower in enclosures with low fish biomass. This suggested that phytoplankton limitation might shift from one of zooplankton control to one of limitation by P availability with increasing fish biomass. Relative to fish mediated P recycling and fish grazing, zooplankton grazing appeared to be more important as a driver of trophic cascades in systems subsidized by allochthonous detritus. Silver Carp stocked at high biomass would strongly reduce zooplankton grazing pressure and increase the yield of phytoplankton per TP.

Do bigheaded carp act as a phosphorus source for phytoplankton in (sub)tropical Chinese reservoirs?

Stocking of bigheaded carp (mainly Hypophthalmichthys nobilis and H. molitrix) is commonly used in (sub)tropical Chinese reservoirs to control phytoplankton, but with ambiguous results. Whether these carp act as a phosphorus (P) source or sink for phytoplankton is debated. We compared the trophic structures in twenty-three reservoirs with different nutrient concentrations in the flood season (after bigheaded carp introduction) with the dry season (after bigheaded carp harvesting). Fish biomass was positively related to TP, and the slope of the relationship showed no difference between seasons. Bigheaded carp harvesting exceeded the amount introduced, which may explain an observed lower intercept of the relationship and fish biomass to the TP ratio in the dry season. Fish predation pressure on zooplankton (fish: zooplankton biomass ratio as a proxy) was highest in the flood season and increased with TP in both seasons. Accordingly, zooplankton grazing effect on phytoplankton (zooplankton: phytoplankton biomass ratio as a proxy) decreased with fish biomass. Furthermore, both the zooplankton biomass and the zooplankton: phytoplankton biomass ratio were among the lowest reported in the literature for the nutrient range studied. Fish grazing effect on phytoplankton (fish: phytoplankton biomass ratio as a proxy) was also highest in the flood season and decreased with TP in both seasons. Nanoplankton was the dominant phytoplankton group in oligotrophic to mesotrophic reservoirs, while filamentous cyanobacteria dominated in eutrophic reservoirs. Chlorophyll a increased with TP and fish biomass, whereas the yield of chlorophyll a per TP (Chla: TP ratio) increased with fish biomass. Accordingly, both chlorophyll a and the Chla: TP ratio were highest in the flood season. We conclude that bigheaded carp act as P sink at the ecosystem level but as P source for phytoplankton, and enhance the yield of chlorophyll a per TP and thus eutrophication.

Total phosphorus-precipitation and Chlorophyll a-phosphorus relationships of lakes and reservoirs mediated by soil iron at regional scale.

Phosphorus is a critical element determining trophic status and Chlorophyll a (Chl a) level in natural lakes and reservoirs, and total phosphorus (TP) concentrations can be predicted from data on phosphorus loading, hydraulic flushing rate and sedimentation. Due to their interactions with phosphorus, iron (hydr) oxides in suspended particles, originally derived from watershed soil, can strongly influence the phosphorus sedimentation and phosphorus bioavailability in water columns. Thus, the TP-precipitation relationship and the response of Chl a to TP are likely associated with watersheds soil iron. To test this assumption, we built hierarchical linear models for summer observation of natural lakes and reservoirs across a large geographic gradient. The intercepts and slopes of TP-precipitation relationships are higher in natural lakes than those in reservoirs, and these model coefficients exhibit latitudinal variations that are explained by the natural soil iron gradient. Soil iron, operating at a regional level, significantly mediates the effect of precipitation on TP concentration in both natural lakes and reservoirs, and drives the latitudinal variation in the Chl a-TP relationships for reservoirs. Our results imply that the increase in extreme precipitation events anticipated under future climate conditions may substantially mitigate eutrophication in tropical and subtropical reservoirs, but may worsen conditions in temperate lakes.

Daphnia diversity on the Tibetan Plateau measured by DNA taxonomy.

Daphnia on the Tibetan Plateau has been little studied, and information on species diversity and biogeography is lacking. Here, we conducted a 4-year survey using the barcoding fragment of the mitochondrial COI gene to determine the distribution and diversity of Daphnia species found across the Plateau. Our results show that species richness is higher than previously thought, with total described and provisional species number doubling from 5 to 10. Six of the taxonomic units recovered by DNA taxonomy agreed well with morphology, but DNA barcoding distinguished three clades each for the D. longispina (D. galeata, D. dentifera, and D. longispina) and D. pulex (D. pulex, D. cf. tenebrosa, and D. pulicaria) complexes. The sequence divergence between congeneric species varied within a large range, from 9.25% to 30.71%. The endemic D. tibetana was the most common and widespread species, occurring in 12 hyposaline to mesosaline lakes. The lineage of D. longispina is the first confirmed occurrence in west Tibet.

The mitochondrial genome of Atrocalopteryx melli Ris, 1912 (Zygoptera: Calopterygidae) via Ion Torrent PGM NGS sequencing.

The mitochondrial genome of Atrocalopteryx melli was sequenced and assembled via Next-Generation Sequencing (NGS) and iteratively assembly process with a reference seed. This genome is 15,562 bp long and A + T biased (71%), with 37 genes arranged in common order of Odonata. All protein-coding genes are initiated by typical "ATN" codon, and 9 genes are terminated with a complete stop codon, except nad4, nad5, cox2, and cox3, which are terminated with an incomplete codon "T(aa)". The S5 intergenic spacer is absent in this genome, supporting that lacking of S5 as a specific character for damselflies. The A + T rich region of A. melli is 267 bp longer than that of A. atrata. This mitogenome provides new molecular information for understanding of A. melli and Atrocalopteryx.

[Report of Successful Treatment of A Rectal Cancer Patient with Endobronchial 
Metastasis by Bronchial Stent Implantation Combined with Chemotherapy and Apatinib].

The lungs are the most common sites of metastases from non-pulmonary malignancies. On the other hand, endobronchial metastases are rare. Various tumors have been associated with endobronchial metastasis, most commonly renal, breast and colorectal cancer. Advanced rectal cancerwith lung metastasis is common. However, endobronchial metastasis without lung metastasis of rectal cancer is rare, and easily misdiagnosed. We report one case of postoperative rectal cancer with endobronchial, pleuralcavity, pericardial cavitymetastasis, giving the comprehensive treatment of bronchial stentimplantation, chemotherapy, targeted drugs and remission. The process of diagnosis and treatmentis relatively complex, therefore it has a certain clinical reference value.

Responses of trophic structure and zooplankton community to salinity and temperature in Tibetan lakes: Implication for the effect of climate warming.

Warming has pronounced effects on lake ecosystems, either directly by increased temperatures or indirectly by a change in salinity. We investigated the current status of zooplankton communities and trophic structure in 45 Tibetan lakes along a 2300 m altitude and a 76 g/l salinity gradient. Freshwater to hyposaline lakes mainly had three trophic levels: phytoplankton, small zooplankton and fish/Gammarus, while mesosaline to hypersaline lakes only had two: phytoplankton and large zooplankton. Zooplankton species richness declined significantly with salinity, but did not relate with temperature. Furthermore, the decline in species richness with salinity in lakes with two trophic levels was much less abrupt than in lakes with three trophic levels. The structural variation of the zooplankton community depended on the length of the food chain, and was significantly explained by salinity as the critical environmental variable. The zooplankton community shifted from dominance of copepods and small cladoceran species in the lakes with low salinity and three trophic levels to large saline filter-feeding phyllopod species in those lakes with high salinity and two trophic levels. The zooplankton to phytoplankton biomass ratio was positively related with temperature in two-trophic-level systems and vice versa in three-trophic-level systems. As the Tibetan Plateau is warming about three times faster than the global average, our results imply that warming could have a considerable impact on the structure and function of Tibetan lake ecosystems, either via indirect effects of salinization/desalinization on species richness, composition and trophic structure or through direct effects of water temperature on trophic interactions.

The mitochondrial genome of Diaphanosoma dubium with comparison with Daphnia magna.

Diaphanosoma has been called "tropical Daphnia" for its strong ecological role in tropical freshwater as Daphnia in temperate waters. The present study sequenced and annotated the mitochondrial genome (MG) of Diaphanosoma dubium. The MG of Diaphanosoma dubium is 16,362 bp in length, with typical metazoan gene composition. Phylogenetic analysis confirms an earlier finding that Neodiaphanosoma can be separated from Diaphanosoma as a subgenera. One unknown extra CDS region and different arrangement of tRNA were identified when this MG was compared to that of Daphnia magna. This is the first non-daphnia MG of Cladocera, and information on MG sequence and tRNA order provide valuable molecular data in understanding phylogeny of Diaphanosoma and Cladocera.

Stable isotope composition of suspended particulate organic matter in twenty reservoirs from Guangdong, southern China: implications for pelagic carbon and nitrogen cycling.

We studied seasonal variations in the carbon and nitrogen stable isotopes (δ(13)C and δ(15)N) of particulate organic matter (POM) in the surface water of 20 man-made reservoirs in southern China during March, August and December 2010. These reservoirs are located from subtropical to tropical region, varied in trophic states and were influenced by several types of human activities. The geomorphometric and biogeochemical gradients in tropical/subtropical regions are complicated and poorly understood because of low variation in temperature and high variation in hydrological processes. The POM samples were collected from all the reservoirs to assess the seasonal variation patterns of δ(13)CPOM and δ(15)NPOM. Variation in δ(13)CPOM followed seasonal thermal and hydrological cycles. By contrast, δ(15)NPOM did not seasonally differ, which may have been complicated by phytoplankton assimilation of N originating in agricultural waste entering the reservoirs and of atmospheric nitrogen during the wet season as well as an increased relative contribution of animal waste in the reservoirs in the dry season. Within each sampling period, nutrient availability is more important than thermal and solar radiation inputs in the summer, and these physical drivers are more important during the dry and cold winter month in controlling δ(13)CPOM and δ(15)NPOM. On an annual basis, trophic states (total P, total N and chlorophyll a) are the primary drivers for the changes in both δ(13)CPOM and δ(15)NPOM across reservoirs. When the seasonal effect is removed using annual averages from each reservoir, we found that latitude, trophic states, pH, rainfall, water temperature, reservoir age, catchment area to reservoir area (CA:RA) ratio and together explained about 80% of the variance in both δ(13)CPOM and δ(15)NPOM. Our findings also suggest that the trend of δ(15)NPOM is less predictable than δ(13)CPOM. The consistent (15)N depletion and enrichment of POM in different reservoirs point to the importance of different anthropogenic sources of nitrogen in the reservoirs.

[Usage of flocculation in emergent control of algal bloom in drinking water supplying reservoir].

An Anabaena circinalis bloom appeared in a reservoir for supplying drinking water in the south of China, in April 2006. Phytoplankton scums gathered and floated on the surface of the whole reservoir especially on the area of water intake, and the cell density of phytoplankton, cyanobacteria and Anabaena circinalis was as high as 7.3 x 10(7), 7.2 x 10(7), 4.1 x 10(7) cells x L(-1) respectively. To maintain drinking water supplying, an emergency program was initiated to control the cyanobacterial bloom. The zone immediately adjacent to the water intake was divided into two small zones by fishing nets and waterproof curtains to modify the water flow. Iron-based flocculants were then applied to control the algal bloom. As a result, the density of the phytoplankton decreased greatly, and at the first day the cell densities of phytoplankton, cyanobacterial, Anabaena circinalis decreased to 5.3 x 10(6), 4.7 x 10(6), 2 x 10(6) cells x L(-1) respectively, and the removal of them reached up to 93%, 94%, 95% respectively. The average of phytoplankton cell density was 1.2 x 10(7) cells x L(-1) and a highest density was 2.0 x 10(7) cells x L(-1) during the treatment from 22 to 30 April, while Chlorophyta and Bacillariophyta slightly increased. These encouraging results suggest that the flocculants used are efficient at removing Cyanobacteria.

[Response of soil-wheat ecosystem to soil magnetization and related ecological indicators].

By using outdoor pot-culture method combined with biological magnetic effect analysis, this paper studied the effect of soil magnetization on soil-wheat ecosystem health. It was showed that there was an improvement in soil-wheat ecosystem health after soil magnetization, e.g., the germination of wheat seeds promoted, and the seedling height, individuals of leaves and roots, overall and active absorption area of roots and their absorption rates, and biological yield of mature wheat were increased. The ecological indicators of magnetic health effect were also discussed. 200 mT was the best parameter of magnetic treatment for wheat growth.