Interspecies competition for nutrients between Prorocentrum donghaiense Lu and Skeletonema costatum(Grev.) Cleve in mesocosm experiments

Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms（HABs）.The results showed that there was interspecies competition between P.donghaiense and Skeletonema costatum（Grev.） Cleve.The cell number of P.donghaiense and S.costatum accounted for about 85% and 11% of the total cell number of phytoplankton respectively at the beginning of the experiment in May 1998.In May 2002,at the beginning of the experiment,the cell number of P.donghaiense accounted for 55%-66% of the total and S.costatum accounted for 32%-42%.The density of P.donghaiense and S.costatum was over 95% and 1%-5% respectively in May 2003.The results of these three mesocosm experiments showed that the dominant species in this specific community varied with different nutrient availability.Under low-phosphate conditions,the dominant species was P.donghaiense,while S.costatum became dominant in phosphate-replete cases.The average growth rate（1.08 d-1） of S.costatum in exponential growth phase was higher than that（0.39 d-1） of P.donghaiense.In the mesocosm,S.costatum predominated in the mesocosm by its rapid growth.When phosphorus was depleted,the cell number of S.costatum dropped rapidly,while P.donghaiense Lu decreased more slowly.The results from mesocosm experiment may explain why：（1） P.donghaiense bloom usually occurs in May,when phosphate concentration is low;（2） the bloom of S.costatum appears in early spring and summer time,when nutrients increase with increasing Changjiang River（Yangtze River） runoff;（3） the bloom of S.costatum is short and that of P.donghaiense Lu can last more than a month in the East China Sea.

The expression characteristics of vitellogenin(VTG) in response to B(a)p exposure in polychaete Perinereis aibuhitensis

In order to investigate the endocrine toxicity of B(a)p to marine polychaete P erinereis aibuhitensis, vitellogenin(VTG) cDNA from the P. aibuhitensis was isolated, recombinated and expressed for the first time. The full length P. aibuhitensis vitellogenin gene(PaVTG) was 5 325 bp, and encoded 1 692 amino acids. It contained the vitellogenin_N domain of unknown function(DUF1943), a von Willebrand factor type D domain, as well as a conserved KALGNAG motif. The expression of VTG gene and protein were mainly up-regulated after exposed to B(a)p at transcriptional and translational levels. PaVTG gene expression did not change significantly at day 4. At day 7 PaVTG expression was up-regulated in 0.5 μg/L and 5 μg/L B(a)p group. At day 14 PaVTG was significantly up-regulated in 0.5–10 μg/L B(a)p. The protein expression of PaVTG in 0.5 μg/L and 10 μg/L B(a)p group was up-regulated with time prolonging, but the expression in 5 μg/L and 50 μg/L B(a)p group exhibited first increased and then decreased trend. With the increasing of B(a)p concentration PaVTG mRNA and protein expression both firstly increased then decreased. In contrast to B(a)p exposure, estradiol did not induce PaVTG gene and protein expression, until late times of exposure(14 d). Overall, the results in this study indicate that PaVTG could be used as a potential indicator of the effects environmental estrogenic compounds.

A selective N,N-dithenoyl-rhodamine based fluorescent probe for Fe3+ detection in aqueous and living cells

A novel N,N-dithenoyl-rhodamine based fluorescent and colorimetric Fe3+probe 1 was designed and synthesized by only one step from Rhodamine B hydrazide and 2-thiophenecarbonyl chloride.The structure of probe 1 was characterized by 1 H NMR/13C NMR spectroscopy,IR spectroscopy,and HRMS spectrometry.Accompanying with significant changes in visual color and fluorescent spectrum,probe 1 displayed good sensitivity for Fe3+with an abroad pH span.The detection limit(3.76μmol/L,0.2 mg/L)for Fe3+was lower than WHO recommended value(0.3 mg/L)for drinking water.Using two thiophene carbonyl groups as coordinating functional recognition group,probe 1 showed excellent selectivity towards Fe3+over diverse coexistent metal ions and anions.The sensing mechanism between dithenoyl-substituted probe 1 and Fe3+was further confirmed by 1 H NMR and IR titration experiments,binding constants study,and Job’s plot analysis.Furthermore,probe 1 also exhibited good cell membrane permeability and could be used as an efficient Fe3+probe in living human cells.

耐盐碱解磷菌Bacillus sp.DYS211对土壤磷溶解和植物生长的促进作用

土壤全磷含量高而速效磷含量不足严重制约盐碱地区磷的高效利用。虽然耐盐碱解磷菌可以溶解不溶性磷,但很少有研究关注其在植物生长中的应用。我们从盐碱地区鸟粪中分离到一株解磷菌,鉴定命名为Bacillus sp.DYS211,并对其生长特性和耐盐碱能力进行了测定。为研究解磷菌对植物种子萌发和生长的影响,在盐地碱蓬中进行解磷菌添加的盆栽试验。该解磷菌菌株在培养前12 h生长迅速,48 h时溶磷量最大,达到258.22 mg L^(−1)。耐盐碱性和解磷能力试验表明,DYS211倾向于溶解无机磷,为嗜盐菌,在1%–8%盐度条件下具有良好的解磷效果(有效磷含量>150 mg L^(−1))。在葡萄糖和蔗糖(C源)以及硫酸铵、硝酸铵和酵母浸膏粉(N源)中均表现出较好的解磷能力。在促生长试验中,该解磷菌对种子萌发有促进作用,特别是在高盐胁迫下,促进率为8.33%。在盐碱条件下,解磷菌均能显著提高盐地碱蓬的株高和生物量(最高可达3倍),且高盐胁迫下茎粗增加。该菌株表现出在盐碱地区植被恢复中的潜力。