[Effects of ultrasound on the physiological characteristics and competitive growth between Microcystis aeruginosa and Chlorella pyrenoidosa]. / è¶ å£°æ³¢å¯¹é“œç»¿å¾®å›Šè—»ä¸Žè›‹ç™½æ ¸å°çƒè—»ç”Ÿç†ç‰¹å¾åŠç«žäº‰ç”Ÿé•¿çš„å½±å“.

Microcystis aeruginosa is a common bloom-forming cyanobacterium, which generally coexists and competes with Chlorella pyrenoidosa in lakes. Sonication can be used for emergency management of algal blooms. Ultrasound influences algal growth and physiological parameters, as well as interspecific competition in algal community. To explore the effects of ultrasonic stress (35 kHz, 0.035 W·cm-3) on physiological characteristics and interspecific competition of algae, M. aeruginosa and C. pyrenoidosa were sonicated in mono- and co-cultures (1:1 mixture, according to cell concentration). Results showed that M. aeruginosa was more sensitive to ultrasonic stress. After the sonication for 600 s, both photosynthetic activity (Fv/Fm) and esterase activity of M. aeruginosa showed significant changes, with Fv/Fm values in mono- and co-cultures being decreased by 51.8% and 64.7%, respectively. In comparison, Fv/Fm values of C. pyrenoidosa changed slightly. M. aeruginosa released more chromophoric dissolved organic matter (CDOM, including tryptophan-, tyrosine-, and fulvic-like substances) than C. pyrenoidosa. The cell concentration of C. pyrenoidosa showed little changes regardless of sonication time, while the cell concentration of M. aeruginosa decreased at different degrees. The cell concentration of M. aeruginosa in co-cultures decreased by 42.6% after sonication for 600 s, which might be responsible for the dominance of C. pyrenoidosa during 8 days after sonication. M. aeruginosa inhibited C. pyrenoidosa in other treatments, but mutual inhibition appeared in the 600 s sonication treatment. After ultrasonic treatment, the activity of M. aeruginosa could recover gradually. The treatment should be conducted again within a week to improve the persistence of algal control.

Expression of XPG protein in the development, progression and prognosis of gastric cancer.

BACKGROUND: Xeroderma pigmentosum group G (XPG) plays a critical role in preventing cells from oxidative DNA damage. This study aimed to investigate XPG protein expression in different gastric tissues and in patients with diverse prognoses, thus providing insights into its role in the development, progression and prognosis of gastric cancer (GC). METHODS: A total of 176 GC, 131 adjacent non-tumour tissues, 53 atrophic gastritis (AG) and 49 superficial gastritis (SG) samples were included. Immunohistochemical staining was used to detect XPG protein expression. RESULTS: XPG expression was significantly higher in GC tissues compared with adjacent non-tumour tissues. In the progressive disease sequence SG→AG→GC, XPG expression was significantly higher in AG and GC compared with SG. Analysis of clinicopathological parameters and survival in GC patients demonstrated a significant association between XPG expression level and depth of tumour invasion, macroscopic type, Lauren's classification, smoking, Helicobacter pylori infection and family history. Cox multivariate survival analysis indicated that patients with positive XPG expression had significantly longer overall survival (P = 0.020, HR = 0.394, 95%CI 0.179-0.866), especially in aged younger than 60 years (P = 0.027, HR = 0.361, 95%CI 0.147-0.888) and male patients (P = 0.002, HR = 0.209, 95%CI 0.077-0.571). CONCLUSIONS: This study demonstrated that XPG protein expression was related to the development, progression and prognosis of GC, and might thus serve as a potential biomarker for its diagnosis and prognosis.

Coastal surface sediment quality assessment in Leizhou Peninsula (South China Sea) based on SEM-AVS analysis.

Surface sediments from the coastal area of the Leizhou Peninsula in the South China Sea were collected and analyzed and the potential ecological risks in the area were assessed based on acid-volatile sulfide (AVS) model. The AVS levels are between 0.109 and 55.6 µmol g(-1), with the average at 4.45 µmol g(-1). The high AVS-concentration zones include the aquaculture areas of Liusha Bay and the densely populated areas of Zhanjiang Bay. The simultaneously extracted metals (SEM) range from 0.026 µmol g(-1) to 8.61 µmol g(-1), with the average at 0.843 µmol g(-1). Most of high SEM-concentration stations were located in ports or aquaculture zones. Most of the coastal surface sediments of the Leizhou Peninsula (90%) had no adverse biological effects according to the criterion proposed by USEPA (2005); while adverse effects were uncertain in some stations (8%); even in 2 stations (2%) adverse biological effects may be expected.

A field study of the relationship between sulfide-bound metals and bioaccumulation by Limnodrilus sp. in a heavily polluted river.

Acid volatile sulfide (AVS) has been regarded as an important factor controlling metal bioavailability in anoxic sediments, but its effect on metal accumulation under natural conditions is poorly understood. Here, a field study of the influence of AVS on metal accumulation by Limnodrilus sp. in a heavily polluted river is provided. Most of the study area was subject to anaerobic and strongly reducing conditions, and the concentration of trace metals in surface sediments was high, as were the concentration of AVS and simultaneously extracted metals (SEM; average AVS = 20.3 µmol g(-1), average ∑SEM5 = 9.42 µmol g(-1); ∑SEM5 refers to the sum of SEMCd, SEMCu, SEMPb, SEMNi, and SEMZn). Only a few species and small quantities of benthic invertebrates were found, and Limnodrilus sp. was dominant. There was no correlation between trace metal accumulation and (SEM-AVS), and in stations where (SEM-AVS) <0, the absolute value of bioaccumulation was high (average ∑BIO5 = 4.07 µmol g(-1); ∑BIO5 refers to the sum of BIOCd, BIOCu, BIOPb, BIONi, and BIOZn), indicating that there was no relationship between (SEM-AVS) and metal accumulation in Limnodrilus sp. This was likely because Limnodrilus sp. ingest sediment particles as their main food source, so pore water metals play a minor role in their bioaccumulation (BIO) of materials. However, ∑BIO5 was significantly correlated with ∑SEM5 (r = 0.795, p < 0.01), revealing that the large number of sulfide-bound metals (SEM) in sediments may play an important role in metal accumulation in Limnodrilus sp., which can assimilate sulfide-associated metals by the help of the digestive fluids in the digestive systems.

Ecological risks assessment and pollution source identification of trace elements in contaminated sediments from the Pearl River Delta, China.

Sediments from 14 stations in the Foshan Waterway, a river crossing the industrial district of Guangdong Province, South China, were sampled and subsequently analyzed. The 14 stations were selected for the pollution discharging features of the river, such as the hydrology, the distribution of pollution sources, and the locations of wastewater outlets. The ecological risks were assessed, and the pollution sources were identified to provide valuable information for environmental impact assessment and pollution control. The spatial variability was high and the range were (in milligrams per kilogram dry weight): Pb, 46.0~382.8; Cu, 33.7~ 482.3; Zn, 62.2~1,568.7; Ni, 28.5~130.7; Cr, 34.7~1,656.1; Cd, 0.50~8.53; Hg, 0.02~8.27; and As, 5.77~66.09. The evaluation results of enrichment factor and potential ecological risk index indicate that the metal pollution in the surface and bottom sediments were severely polluted and could pose serious threat to the ecosystem in most stations. Although the hazard levels of the trace element differed among the stations, Hg was the most serious pollutant in all stations. The results of principal component analysis (PCA) show that the discharge of industrial wastewater is the most important polluting factor whereas domestic sewage, which contains a large amount of organic substances, accelerates metal deposition. And potential pollution sources were identified by the way of integrating the analysis results of PCA and data gained from the local government. Therefore, the conclusion is drawn that Foshan Waterway is seriously polluted with trace elements, both in the surface sediment (0 to 20 cm) and the bottom sediments (21 to 50 cm) are contaminated.

[AVS concentrations in Xinan Creek and the influencing factors].

Sediment and overlying water samples were collected at 10 sampling stations at Xinan Creek, a tidal river in Pearl River Delta, and analyzed for physical and chemical characteristics as well as microbial incicators, in order to reveal the main factors dominating the spatial distribution of acid volatile sulfide (AVS). The effects of Eh, SRB OC and TS on the spatial distribution of AVS were investigated and the impact of AVS on the toxicity of heavy metals in the studied area was evaluated. The results showed that the range of AVS was 0.207-41.453 micromol x g(-1), with an average of 6.684 micromol x g(-1), which is relatively high compared to the results in other studies. The AVS value of the surface layer was higher than the bottom layer in 5 stations. The AVS values in both the surface layer and the bottom layer were highly variable, the coefficients of variation being 93.61% and 153.09% , respectively. The analytical results revealed that TS was the factor with the greatest impact on the spatial distribution of AVS, and the order was TS > OC > Eh > SRB. Potential ecological risk of heavy metals existed in 60% of the smpling stations based on the value of Sigma (SEM5-AVS), however, with the criterion of [Sigma(SEM5-AVS)]/foc, none of them had inacceptable ecological risk. Furthermore, in terms of single species of heavy metals, there was certain risk of toxic effect for all the five heavy metals (Cd, Ni, Cu, Zn and Pb). The above mentioned results will provide valuable data for the in-depth study of the formation mechanism of AVS and helpful reference for environmental impact assessment and scientific rehabilitation of heavy metals in polluted rivers.