Occurrence and transfer of heavy metals in sediments and plants of Aegiceras corniculatum community in the Qinzhou Bay,southwestern China

Mangrove wetlands can reduce heavy metal pollution by trapping heavy metals.In this study,the concentration,transport and bioaccumulation of Cr,Cd,Cu,Zn and Pb in the sediments and different parts of Aegiceras corniculatum at four different sites in the Qinzhou Bay in southwestern China were investigated.The results showed that although the potential ecological risk of all five heavy metals was slight,the concentration of Cr was at a moderate pollution level due to the emissions of industries and aquaculture waste water.Core sediment records indicated that the concentrations of heavy metals at the depth of 0–20 cm were relatively high,showing an increasing trend of heavy metals over the past 20–30 years.Cr,Cu,Pb and Cd accumulated mainly in the roots of A.corniculatum,while Zn accumulated mainly in the stems.Aegiceras corniculatum showed the strongest transport capacity for Zn and Cu and the strongest bioaccumulation ability for Cd.Compared with other mangrove communities,A.corniculatum can be chosen as a restoration species in tropical and subtropical coastal zones polluted by Zn,Cu and Cd.

Effects of used lubricating oil on two mangroves Aegiceras corniculatum and Avicennia marina

An outdoor experiment was set up to investigate the effects of used lubricating oil （5 L/m^2） on Aegiceras corniculatum Blanco. and Avicennia marina （Forsk） Vierh., two salt-excreting mangroves. A. marina was more sensitive to used lubricating oil than A. corniculatum and canopy-oiling resulted in more direct physical damage and stronger lethal effects than base-oiling. When treated with canopy-oiling, half of A. corniculatum plants survived for the whole treatment time （90 d）; but, for A. marina, high mortality （83%） resulted from canopy-oiling within 3 weeks and no plants survived for 80 d. Base-oiling had no lethal effects on A. corniculatum plants even at the termination of this experiment, but 83% of A. marina plants died 80 d after treatment. Forty days after canopyoiling, 93% ofA. corniculatum leaves fell and no live leaves remained on A. marina plants. By the end of the experiment, base-oiling treatment resulted in about 45% ofA. corniculatum leaves falling, while all A. mar/na leaves and buds were burned to die. Lubricating oil resulted in physiological damage to A. corniculatum leaves, including decreases in chlorophyll and carotenoid contents, nitrate reductase, peroxidase and superoxide dismutase activities, and increases in malonaldehyde contents. For both species, oil pollution significantly reduced leaf, root, and total biomass, but did not significantly affect stem biomass. Oil pollution resulted in damage to the xylem vessels of fine roots but not to those of mediate roots.

A Preliminary Study on Anti-Colorectal Cancer Effect and Molecular Mechanism of Aegiceras Corniculatum Extract

Objective:To study the inhibitory effects on colorectal cancer(CRC)and the underlying mechanism of the petroleum ether extract of Aegiceras corniculatum leaves(PACL).Materials and Methods:The effect of PACL on the proliferation of CRC cell lines DLD-1,HT-29,and SW480was measured by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay and colony-forming assay.And then,a wound-healing assay was used to measure the migration ability of three CRC cells.The cell cycle and apoptosis of three CRC cells were measured by PI/RNase staining and annexin V-FITC/double staining,respectively,and the intrinsic apoptosis pathway was studied by the Western blot.The anti-CRC effect of PACL in vivo was evaluated by HT-29 xenograft zebrafish embryos.Results:PACL inhibited cell viability and proliferation in DLD-1,HT-29,and SW480 cells in a dose-and time-dependent manner.PACL can inhibit cell migration in DLD-1and SW480 cells but not in the less mobile phenotype cell HT-29.PACL treatment resulted in cell cycle arrest of DLD-1 and HT-29 cells in the G2/M phase.Moreover,PACL can induce apoptosis in all three CRC cells,which may be achieved by regulating the intrinsic apoptosis pathway mediated by mitochondria and the endoplasmic reticulum.Interestingly,the tumor sizes were decreased after treatment with PACL and PACL combined with fluorouracil in HT-29 xenograft zebrafish embryos.Conclusions:These findings suggested that PACL may exert its anti-CRC effect by inducing apoptosis through the intrinsic apoptosis pathway and show a significant anti-CRC effect in vitro and in vivo,so it might be potentially developed as an anti-CRC agent.

Dramatic changes in the horizontal structure of mangrove forests in the largest delta of the northern Beibu Gulf, China

The horizontal structure of mangrove forests is an important characteristic that reflects a significant signal for coupling between mangroves and external drivers.While the loss and gain of mangroves has received much attention,little information about how the horizontal structure of mangrove forests develops from the seedling stage to maturity has been presented.Here,remote sensing images taken over approximately 15 years,UVA images,nutrient elements,sediments,and Aegiceras corniculatum vegetation parameters of the ecological quadrats along the Nanliu Delta,the largest delta of the northern Beibu Gulf in China,are analyzed to reveal changes in the horizontal structure of mangroves and their associated driving factors.The results show that both discrete structures and agglomerated structures can often be found in A.corniculatum seedlings and saplings.However,the combination of seedlings growing into maturity and new seedlings filling in available gaps causes the discrete structure of A.corniculatum to gradually vanish and the agglomerate structure to become stable.The aggregated structure of seedlings,compared to the discrete structure,can enhance the elevation beneath mangroves by trapping significantly more sediments,providing available spaces and conditions for seedlings to continue growing.Furthermore,by catching fine sediments with enriched nutrients,the survival rate of A.corniculatum seedlings in the agglomerated structure can be much higher than that in the discrete structure.Our results highlight the significance of the agglomeration of A.corniculatum,which can be beneficial to coastal mangrove restoration and management.

深水滩涂红树林营林技术

为解决深水位这一影响红树林生长的关键因素,选用无瓣海桑(Sonneratia apetala BuchananHamilton)和桐花(Aegiceras corniculatum)两个树种,在粤东沿海前沿深水潮汐困难地带进行了2年的造林试验,并介绍了深水滩涂红树林营林技术。结果表明,桐花和无瓣海桑保存率高、生长快、适应性强,是适宜粤东地区深水滩涂的优良红树林树种。垫高植地是深水滩涂成功营造红树林的关键技术措施,选用大苗、适当密植、围网和加强管护等辅助措施可以提高红树林植物的保存率。