Effects of supplying silicon nutrient on utilization rate of nitrogen and phosphorus nutrients by rice and its soil ecological mechanism in a hybrid rice double-cropping system.

This study was conducted to reveal the effects of silicon (Si) application on nutrient utilization efficiency by rice and on soil nutrient availability and soil microorganisms in a hybrid rice double-cropping planting system. A series of field experiments were conducted during 2017 and 2018. The results showed that Si nutrient supply improved grain yield and the utilization rates of nitrogen (N) and phosphorus (P) to an appropriate level for both early and late plantings, reaching a maximum at 23.4 kg/ha Si. The same trends were found for the ratios of available N (AN) to total N (TN) and available P (AP) to total P (TP), the soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and the ratios of MBN to TN and MBP to TP, at different levels of Si. Statistical analysis further revealed that Si application enhanced rice growth and increased the utilization rate of fertilizer due to an ecological mechanism, i.e., Si supply significantly increased the total amount of soil microorganisms in paddy soil compared to the control. This promoted the mineralization of soil nutrients and improved the availability and reserves of easily mineralized organic nutrients.

[Impact of Newly Build Lead-Acid Battery Agglomeration Area on the Surrounding Soil Environment: A Study Based on the Spatial Characteristics of Heavy Metals].

To determine whether the newly built lead-acid battery agglomeration area in a town in northern Zhejiang had an impact on the surrounding soil environment after seven years of operation, 76 samples of surface soil around the lead-acid battery concentration area were collected, and the contents of Hg, As, Cu, Zn, Pb, Cd, Ni, and Cr in the soil were determined. Based on the spatial distance of the agglomeration area and 50, 450, and 850 m from the agglomeration area boundary, the soil environmental quality was evaluated using the single factor index, Nemerow comprehensive pollution index, and potential ecological risk index methods. The spatial distribution characteristics of the heavy metals were analyzed using the geostatistical method, and the sources of heavy metals affecting the soil environment were determined by correlation analysis. The results showed that the average contents of Hg, Zn, and Pb in eight heavy metals were higher than their corresponding background values at all spatial scales. The average Cd content in spatial scales other than the agglomeration area was larger than its background value. Only As at 50 m was greater than its background value, whereas the average content of other elements at all spatial distances was lower than their corresponding background values. The spatial variability was high for Hg and Cd but not obvious for other elements. This implies that the influence of regional activities was concentrated mainly on Hg and Cd; the content of both increased with distance from the agglomeration area. Hg and Cd exceeded the risk screening values and were distributed mainly at 450 m and 850 m; 33.33% and 38.89% Hg points and 27.78% and 55.56% Cd points were observed at these distances, respectively. The spatial distribution characteristics of Hg and Cd were consistent with their contents; only Zn and Pb had scattered points that exceeded the risk screening values and generally no obvious spatial distribution characteristics. According to the risk analysis of soil comprehensive pollution caused by the eight heavy metals, Cd was the main source of soil comprehensive pollution risk at a contribution rate of 36.73%, which caused the soil at 850 m to be in a state of alert. Soil ecological risk at a medium level occurred mainly at 450 m and 850 m outside the agglomeration area from Hg and Cd. The contribution rates to the soil quality at these distances were 46.30% and 39.37% for Hg and 38.98% and 49.30% for Cd, respectively. This indicates that regional activities caused Hg and Cd to be the main elements affecting soil quality in the study area. The results of geostatistics and multivariate statistical analysis showed that Hg and Cd were diffused inward from the periphery of the agglomeration area on the axis of the local main wind direction (northeast-southwest), and the main sources of both were coal-burning activities of enterprises in the periphery of the agglomeration area. In summary, the newly build lead-acid battery agglomeration area has not significantly affected the accumulation of heavy metals in the agglomeration area and in the surrounding soil after seven years of operation.

[Potential to Ensure Safe Production from Rice Fields Polluted with Heavy Cadmium by Combining a Rice Variety with Low Cadmium Accumulation, Humic Acid, and Sepiolite].

The study investigated the potential of ensuring safe production of rice from paddy fields affected by heavy cadmium contamination. A paddy soil polluted with heavy cadmium (total Cd content of 2.52 mg·kg-1) surrounding a lead-zinc mining area in Guiyang County of Chenzhou City, Hunan province was selected for analysis. We investigated production using a low cadmium accumulation rice variety (Oryza sativa L. Jia-33) and passivation additives for heavy metal activity (including humic acid and sepiolite). Results showed that:Oryza sativa L. Jia-33 showed good low cadmium accumulation characteristics in rice fields with heavy cadmium pollution. When humic acid and sepiolite were applied (alone or combined), the accumulation of Cd in different organs of the rice declined, and the transport coefficient of Cd for stem to root and polished rice to stem also declined. The rate of decline increased with increased application dosage. The cadmium content in polished rice was lower than the limit established in the National Food Safety Standard (GB 2715-2012), when applying 5.250 t·hm-2 humic acid, 6.750 t·hm-2 sepiolite, or a combination of 1.125 t·hm-2 humic acid and 3.37 5 t·hm-2 sepiolite; Cd content in polished rice was (0.171±0.01), (0.184±0.01), and (0.181±0.01) mg·kg-1, respectively. Single or combined application of humic acid and sepiolite promoted the transformation of soil Cd to residual and Fe Mn oxide bound forms, significantly reducing the content of available Cd and the bioavailability of Cd in soil, and further reducing Cd content in all rice organs. The reduction was more effective with single application of sepiolite or combined application of humic acid and sepiolite. The effects of combined application of humic acid and sepiolite were also more beneficial for soil nutrients, while soil available phosphorus, available potassium, phosphorus, and organic matter content increased with increased application of amendments. Soil nitrogen content did not change. In conclusion, results indicate that joint application of humic acid, sepiolite, and a low Cd accumulation rice variety are best for safe production on heavy cadmium-contaminated soil.

[Effect of Sepiolite Application on the Migration and Redistribution of Pb and Cd in Soil Rice System in Soil with Pb and Cd Combined Contamination].

In order to research the coordination relation between sepiolite application and the contents of available lead(Pb) and cadmium(Cd) in soil or rice absorption and redistribution of Pb and Cd, a pot experiment was conducted by selecting the soil sampled from a area polluted by Pb and Cd combination in Shaoxing City of Zhejiang Province and atypical late Japonica Rice Varieties in Zhejiang Province(Jia 33) with lower accumulation for Pb, Cd. The results showed that:the contents of available Pb and Cd in soil were significantly negatively correlated with the concentration of sepiolite added, the correlation coefficients of contents of available Pb and Cd with the concentration of sepiolite added were -0.940 respectively and -0.952, which reached the significant level(P<0.01).The contents of Pb and Cd in rice roots, stems, leaves and polished rice had different reducing rates with the increase of the concentration of sepiolite. In addition, with the increase of the concentration of sepiolite added, the enrichment coefficients of Pb and Cd in rice roots, stems, leaves and polished rice decreased dramatically. At the same time, Pb and Cd absorbed by roots transferred to the stems decreasingly, Pb and Cd absorbed by stems transferred to the polished rice decreasingly. When the addition of Sepiolite was 9.00 g·kg-1 soil, the contents of Pb and Cd in polished rice of Jia 33 were(0.14±0.02) mg·kg-1 and(0.03±0.01) mg·kg-1 respectively, which were all lower than the national limit index(GB 2762-2012). Compared with the control group, the enrichment coefficients of Pb in roots, stems and leaves and polished rice decreased by 8.83%, 29.96%, 49.20%, 79.41% respectively, and the enrichment coefficients of Cd decreased by 23.08%, 63.22%, 44.00%, 82.35% respectively. In addition, the transportation coefficients of Pb and Cd absorbed by roots transfer to the stems were decreased by 23.18% and 52.19% respectively and the transportation coefficients of stem rice translocation of Pb and Cd absorbed by stems transfer to the polished rice were decreased by 70.83%, 52.00%, respectively. This result means the sepiolite had a good resistance control in the migration and redistribution of Pb and Cd in soil rice system on the soil polluted by lead and cadmium, indicating the combination of rational application of sepiolite and rice varieties with lower accumulation for heavy metals can achieve safe agricultural utilization of the soil with combined contamination by a relatively higher concentration of Pb and Cd.

A water-stable metal-organic framework of a zwitterionic carboxylate with dysprosium: a sensing platform for Ebolavirus RNA sequences.

We herein report a water-stable 3D dysprosium-based metal-organic framework (MOF) that can non-covalently interact with probe ss-DNA. The formed system can serve as an effective fluorescence sensing platform for the detection of complementary Ebolavirus RNA sequences with the detection limit of 160 pM.

[Study on the accumulation of fluoroquinolones in clinical isolates of susceptible and multi-drug-resistant Escherichia coli strains].

OBJECTIVE: To investigate the active efflux of fluoroquinolones in clinical isolated strains of Escherichia coli. METHODS: The accumulation of ciprofloxacin and tosufloxacin for clinical isolates of Escherichia coli and the effect of glucose and Carbonyl cyanide mchlorophenyl hydrazone (CCCP) on the uptake of Escherichia coli were determined by a modified fluorometric assay. RESULTS: The accumulation of ciprofloxacin in sensitive and multi-drug-resistant (MDR) organisms decreased with energy dependence, and the decrease in MDR isolate was prominent. Incubation with CCCP increased the accumulation of ciprofloxacin up to three-fold in MDR isolate but not in sensitive isolate. In contrast, CCCP appeared to have no influence on the uptake of tosufloxacin in Escherichia coli. CONCLUSION: These results indicate that energy-dependent active efflux is one of the mechanisms of hydrophilic fluoroquinolones resistance, but it does not play any role in hydrophobic fluoroquinolones resistance in Escherichia coli.

[Effects of Carthamus tinctorius injection on bcl-2, caspase-3 expression related to neurons apoptosis after local cerebral ischemia].

OBJECTIVE: To investigate the effects of Carthamus tinctorius on bcl-2, caspase-3 expression of apoptosis of neurons. METHOD: SD rats were randomly divided into ischemia control group, large-dose group, middle-dose group and low-dose group. The middle cerebral artery of rats was occluded for 2h by inserting an introluminal molofilament, and reperfusion was then instituted for 4h or 22h. The brains were stained with 2, 3, 5-triphenylte trazolinm chloride for assessment of volume of infarction, and then embedded onto slides with paraffin for morphological assessment and immunohistochemistry was carried out to investigate the changes in bcl-2 and caspase-3. RESULT: All treated groups at different times decreased the volume of infarction (P < 0.05), while large-dose group showed more distinct decrease than other groups (P < 0.05). All treated groups at different times increased bcl-2 and decreased caspase-3 expression as well, while large-dose group showed more distinct effect (P < 0.05). CONCLUSION: C. tinctorius injection can reduce the volume of cerebral infarction, and increased bcl-2 and decreased caspase-3 expression.

Immunocytochemical identification and localization of APUD cells in the gut of seven stomachless teleost fishes.

AIM:To study the cell types, localization, distribution density and morphology of APUD cells in the intestinal mucosa of stomachless teleost fishes.METHOD:By using the peroxidase antiperoxidase complex (PAP) immunocytochemical staining technique the identification, localization and morphology of immunoreactive (IR) endocrine cells seattered in the intestinal mucosa of grass carp (Cyenopharyngodon idellus), black carp ( Mylopharyngodon piceus ) and common carp (Cyprinus carpio) were investigated with 20 kinds of antisera prepared against mammalian peptide hormones of APUD cells, and likewise by using avidin-biotin-peroxidase complex (ABC) method those of silver carp (Hypophthalmichthys molitrix), bighead (Aristichthys nobilis), silver crucian carp (Carassius gibelio) and bluntnose black bream (Megalobrama amblyocephala ) were also studied with 5 different antisera. The replacement of the first antiserum by phosphate buffered saline (PBS) was employed as a control. IR endocrine cells were counted with a square-mesh ocular micrometer from 10 fields selected randomly in every section of each part of the intestine specimen. The average number of IR endocrine cells per mm(2) was counted to quantify their distribution density.RESULT:Gastrin (GAS), Gastric inhibitory peptide (GIP), glucagon (GLU), glucagons like immunorea-ctants (GLI), bovine pancreatic polypeptide (BPP), leucine-enkephalin (ENK) and substance P (SP)-IR endocrine cells were found in the gut of grass carp, black carp and common carp, and somatostatin (SOM) IR endocrine cells were only seen in common carp. GAS, GIP and GLU-IR endocrine cells were found in the intestinal mucosa of silver carp, bighead, silver crucian carp and bluntnose black bream. Most of IR endocrine cells had the higher distribution density in the foregut and midgut, and were longer in shape. They had a long apical cytoplasmic process extended to the gut lumen and a basal process extended to adjacent cells or basement membrane and touched with it. Sometimes, the basal cytoplasmic process formed an enlarged synapse-like structure in the contiguous part with basement membrane. This phenomenon provided new morpho-logical evidence for neuroendocrine and paracrine secretory function of these enteroendocrine cells.CONCLUTION:At least 8 kinds of IR endocrine cells were found in the gut of stomachless teleost species for the first time in China. These IR endocrine cells scattering in the gut mucosa belong to the APUD system. Among them, the hormones secreted by SP-, ENK-, SOM- and GLU-IR endocrine cells belong to the peptides of dual distribution in the brain and gut. This provided new evidence for the concept of brain-gut peptide. According to the cell types, distribution density, morphological characteristics and variety in shape of APUD cells in the gut of stomachless teleost fishes, it is deemed that the digestive tract of fishes is also an endocrine organ of great importance and complexity.

Identification, localization and morphology of APUD cells in gastroenteropancreatic system of stomach-containing teleosts.

AIM:To identify the type localization and morphology of APUD endocrine cells in the gastroenteropancreatic (GEP) system of stomach-containing teleosts, and study APUD endocrine system in the stomach, intestine and pancreas of fish species.METHODS:Two kinds of immunocytochemical (ICC) techniques of the streptavidin biotin-peroxidase complex (SABC) and streptavidin-peroxidase (S-P) method were used. The identification, localization and morphology of APUD endocrine cells scattered in the mucosa of digestive tract, intermuscular nerve plexus and glandular body of northern snakehead (Channa argus), ricefield eel (Monopterus albus), yellow catfish (Pelteobagrus fulvidraco), mandarinfish (Siniperca chuatsi), largemouth bass (Micropterus salmoides),oriental sheatfish (Silurus asotus), freshwater pomfret (Colossoma brachypomum) and nile tilapia (Tilapia nilotica) were investigated with 8 kinds of antisera.RESULTS:The positive reaction of 5-hydroxytryptamine (5-HT) immunoreactive endocrine (IRE) cells was found in the digestive tract and glandular body of 8 fish species in different degree.Only a few gastrin (GAS)-IRE cells were seen in C.argus,M.albusand P.fulvidraco. Glucagon (GLU)IRE cells were not found in the digestive tract and glandular body but existed in pancreatic island of most fish species. The positive reaction of growth hormone (GH)IRE cells was found only in pancreatic island of S. Chuatsi and S. Asotus, no positive reaction in the other 6 fish species. Somatostatin (SOM), calcitonin (CAL), neurofilament (NF) and insulin (INS)-IRE cells in the stomach, intestine and pancreas of 8 kinds of fish were different in distribution and types. The distribution of all 8 APUD cells was the most in gastrointestinal epithelium mucosa and then in digestive glands. The positive reaction of SOM and 5-HT-IRE cells was found in intermuscular nerve plexus of intestine of P.fulvidraco and S.chuatsi. Only GH-IRE cells were densely scattered in the pancreatic islands of S.chuatsi and S. asotus, and odd distribution in the pancreas of S. asotus.SOM-IRE cells were distributed in the pancreatic islands of S. asotus, C. Brachypomumand T. nilotica. There were INS-IRE cells in the pancreatic islands of S. chuatsi and S. asolus. Eight kinds of APUD cells had longer cell body and cytoplasmic process when they were located in the gastrointestinal epithelium, and had shorter cell body and cytoplasmic process in the gastric gland, and irregular shape in the esophagus and pancreatic island.CONCLUSION:Eight kinds of IRE cells were identified in the GEP system of stomach-containing teleosts. These endocrine cells were scattered in gastrointestinal mucosa, intermuscular nerve plexus, gland body, pancreatic gland and islands under APUD system. CAL and GH-IRE cells in the pancreatic islands of fishes showed functional diversity for these two hormones. Their morphological feature provides evidence of endocrine-paracrine and endocrine-exocrine acting mode. This research can morphologically prove that the GEP endocrine system of fish (the lowest vertebrate) is almost the same as of mammal and human.