苏南地区湖泊群的富营养化状态比较及指标阈值判定分析

借助综合营养状态指数法、箱须图法以及拐点探测分析法,分析了苏南地区11个主要湖泊的富营养化特征以及各湖之间的差异性,并探讨湖泊由轻度富营养化向中度富营养化状态转换的相关指标阈值。结果显示苏南地区各湖泊的营养物水平存在明显的阶梯状特征,不同湖泊所处的富营养化阶段有所不同。典型封闭型湖泊水源地尚湖与傀儡湖水质最好,总体为Ⅱ—Ⅲ类,评价为中营养状态。典型过水性湖泊淀山湖与澄湖水质最差,TN和TP均劣于Ⅴ类,评价为中度富营养状态,其他湖泊属于轻度富营养化状态。基于拐点分析,提出苏南地区湖泊群富营养化状态由轻度向中度转变的指标阈值:COD Mn为4.7mg/L,NH3-N为1.0mg/L,TN为2.3mg/L,TP为0.125mg/L,Chl-a为25μg/L,透明度为50cm;尚湖和傀儡湖处于富营养化最轻的下游区,元荡和阳澄湖目前处于敏感的拐点区域,而淀山湖、澄湖、长荡湖等其他湖泊处于富营养化程度较重的上游区。苏南湖泊群的富营养化状态差异性主要是由不同人为干扰强度和水资源管理模式引起的,实现管理目标由资源利用向资源保护合理转变是解决富营养化问题的关键。     

Molecular Mechanisms of Homologous Chromosome Pairing and Segregation in Plants

In most eukaryotic species, three basic steps of pairing, recombination and synapsis occur during prophase of meiosis I. Homologous chromosomal pairing and recombination are essential for accurate segregation of chromosomes. In contrast to the well-studied processes such as recombination and synapsis, many aspects of chromosome pairing are still obscure. Recent progress in several species indicates that the telomere bouquet formation can facilitate homologous chromosome pairing by bringing chromosome ends into close proximity, but the sole presence of telomere clustering is not sufficient for recognizing homologous pairs. On the other hand, accurate segregation of the genetic material from parent to offspring during meiosis is dependent on the segregation of homologs in the reductional meiotic division （MI） with sister kinetochores exhibiting mono-orientation from the same pole, and the segregation of sister chromatids during the equational meiotic division （MII） with kinetochores showing bi-orientation from the two poles. The underlying mechanism of orientation and segregation is still unclear. Here we focus on recent studies in plants and other species that provide insight into how chromosomes find their partners and mechanisms mediating chromosomal segregation.     

The Anti-Apoptotic and Cardioprotective Effects of Salvianolic Acid A on Rat Cardiomyocytes following Ischemia/Reperfusion by DUSP-Mediated Regulation of the ERK1/2/JNK Pathway

The purpose of this study was to observe the effects of salvianolic acid A (SAA) pretreatment on the myocardium during ischemia/reperfusion (I/R) and to illuminate the interrelationships among dual specificity protein phosphatase (DUSP) 2/4/16, ERK1/2 and JNK pathways during myocardial I/R, with the ultimate goal of elucidating how SAA exerts cardioprotection against I/R injury (IRI). Wistar rats were divided into the following six groups: control group (CON), I/R group, SAA+I/R group, ERK1/2 inhibitor PD098059+I/R group (PD+I/R), PD+SAA+I/R group, and JNK inhibitor SP600125+I/R group (SP+I/R). The cardioprotective effects of SAA on the myocardium during I/R were investigated with a Langendorff device. Heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), maximum rate of ventricular pressure rise and fall (±dp/dt_max), myocardial infarction areas (MIA), lactate dehydrogenase (LDH), and cardiomyocytes apoptosis were monitored. To determine the crosstalk betwee JNK and ERK1/2 via DUSP2/4/16 with SAA pretreatment, siRNA-DUSP2/4/16 were performed. The expression levels of Bcl-2, Bax, caspase 3, p-JNK, p-ERK1/2 and DUSP2/4/16 in cardiomyocytes were assayed by Western blot. Our results showed that LDH, MIA and cell apoptosis were decreased, and various parameters of heart function were improved by SAA pretreatment and SP application. In the I/R group, the expression levels of p-ERK1/2 and DUSP4/16 were not significantly different compared with the CON group, however, the protein expression levels of p-ERK1/2, Bcl-2 and DUSP4/16 were higher, while p-JNK, Bax, caspase 3 and DUSP2 levels were reduced among the SAA+I/R, PD+SAA+I/R and SP+I/R groups. The above indices were not significantly different between the SAA+I/R and SP+I/R groups. Compared with the SAA+I/R group, p-ERK1/2 was increased and p-JNK was decreased in the SAA+si-DUSP2+I/R, however, p-ERK was downregulated and p-JNK was upregulated in SAA+si-DUSP4+I/R group. SAA exerts an anti-apoptotic role against myocardial IRI by inhibiting DUSP2-mediated JNK dephosphorylation and activating DUSP4/16-mediated ERK1/2 phosphorylation.     

The anti-tumor effects of the combination of microwave hyperthermia and lobaplatin against breast cancer cells in vitro and in vivo

Background: Breast cancer is the main lethal disease among females. The combination of lobaplatin and microwave hyperthermia plays a crucial role in several kinds of cancer in the clinic, but its possible mechanism in breast cancer has remained indistinct.Methods: Mouse models were used to detect breast cancer progression. Cell growth was explored with MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphonyl)-2H-tetrazolium) and colony formation assays. Cell migration and invasion were investigated with a transwell assay. Cell apoptosis was probed with flow cytometry. The expression of apoptosis-associated proteins was examined with Western blots.Result: Combination treatment decreased breast cancer cell viability, colony formation, cell invasion and metastasis. In addition, the treatment-induced breast cancer cell apoptosis and autophagy, activated the c-Jun N-terminal kinase (JNK) signaling pathway, suppressed the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway, and down-regulated IAP and Bcl-2 family protein expression.Conclusion: These results indicate that lobaplatin is an effective breast cancer anti-tumor agent. Microwave hyperthermia was a useful adjunctive treatment. Combination treatment was more efficient than any single therapy. The possible mechanism for this effect was mainly associated with activation of the JNK signaling pathway, inactivation of the AKT/mTOR signaling pathway and down-regulation of the Bcl-2 and IAP families.     

黑龙江省2010～2020年猩红热发病与气象因素的关联性研究

分析黑龙江省气象因素与猩红热发病的关系,建立时间序列模型,为今后制定更科学有效的猩红热防控策略提供参考依据。收集黑龙江省2010～2020年猩红热月发病数据以及同期气温、气压等气象资料,应用广义相加模型分析气象因素与猩红热发病之间的关联程度和形式。结果发现: 猩红热全年均有发病而且呈现出较为典型的双峰型特征,在春季的4～5月份和冬季的11～12月份发病数达到高峰;月平均气压、月平均相对湿度、月日照时数和月平均风速的P值均小于0.05,表明具有统计学意义。同时,RR(相对危险度Risk Ratio)值均小于1,即猩红热发病与四个气象因素呈负相关。黑龙江省猩红热发病每年存在两个流行高峰,主要以冬季为主,发病数随着月平均相对湿度、月日照时数、月平均风速与月平均气压的升高而降低。     

RNase H is an exo- and endoribonuclease with asymmetric directionality,depending on the binding mode to the structural variants of RNA:DNA hybrids

RNase H is involved in fundamental cellular processes and is responsible for removing the short stretch of RNA from Okazaki fragments and the long stretch of RNA from R-loops. Defects in RNase H lead to embryo lethality in mice and Aicardi-Goutieres syndrome in humans, suggesting the importance of RNase H. To date, RNase H is known to be a non-sequence-specific endonuclease, but it is not known whether it performs other functions on the structural variants of RNA:DNA hybrids. Here, we used Escherichia coli RNase H as a model, and examined its catalytic mechanism and its substrate recognition modes, using single-molecule FRET. We discovered that RNase H acts as a processive exoribonuclease on the 3′ DNA overhang side but as a distributive non-sequence-specific endonuclease on the 5′ DNA overhang side of RNA:DNA hybrids or on blunt-ended hybrids. The high affinity of previously unidentified double-stranded (ds) and single-stranded (ss) DNA junctions flanking RNA:DNA hybrids may help RNase H find the hybrid substrates in long genomic DNA. Our study provides new insights into the multifunctionality of RNase H, elucidating unprecedented roles of junctions and ssDNA overhang on RNA:DNA hybrids.     

基于投入产出模型的黄河“几字弯”城市群用水特征与节水关键区域

黄河“几字弯”区域是黄河流域的关键节点，是实现中西部崛起的关键区域，也是黄河流域生态环境保护和高质量发展的战略支撑。然而，缺水已经成为制约“几字弯”地区经济社会发展的最大瓶颈。利用投入产出模型，从生产侧的实体水和消费测的虚拟水出发，分析“几字弯”地区18个城市的用水量、结构变化和流入流出特征，结合生产与消费两个方面提出了“几字弯”地区城市群节水的重点区域及产业供水调整的建议。（1）“几字弯”区域虚拟水用量由2007年648.5亿m3增加至2017年778.4 亿m3，增加了20.0%，但实体水用量仅变化了-0.04%，各城市虚拟水增长类型差异较大。（2）18个城市实体水占虚拟水的比例由2007年41.7%下降至2017年34.8%，水资源利用效率逐步提高；实体水的用水大户是农业，虚拟水的用水大户是制造业和农业，服务业实体水和虚拟水用量剧增。（3）区域18个城市虚拟水流入量增长明显，但整体仍呈现出虚拟水净流出的特征。制造业虚拟水流出量均在188.9亿m3以上，流入量均不足108.9亿m3，制造业在区域经济中具有一定的比较优势。（4）巴彦淖尔、中卫、吴忠、石嘴山和白银市是“几字弯”18个城市中重点节水的对象。在这些城市中，农业用水比重较大，产出较低，农业是今后节水的重点。鄂尔多斯、包头、石嘴山、乌海制造业具有比较优势，巴彦淖尔的农业用水系数远远高于18个城市的平均值，需要控制其农业用水。对于鄂尔多斯、包头、石嘴山、乌海、巴彦淖尔5市，需要向当地的优势产业制造业和服务业进行供水倾斜、提高比较优势。     

Investigation on the Optical Transition of Hexagonal Boron Nitride

Plasmonics - We study the relationship between the optical transition of hexagonal boron nitride and the direction of its optical axis. The results show that the optical transition can be tunable...     

Risk assessment and source identification of coastal groundwater nitrate in northern China using dual nitrate isotopes combined with Bayesian mixing model

Due to the intensive and complicated human activities, the identification of nitrate pollution source of coastal aquifer is usually a challenge. This study firstly adopted stable isotope technique and stable isotope analysis in R (SIAR) model to identify the nitrate sources and contribution proportions of different sources in typical coastal groundwater of northern China. The results showed that about 91.5% of the groundwater samples illustrated significantly high nitrate concentrations exceeding the maximum WHO drinking water standard (50 mg/l), reflecting the high risk of groundwater nitrate pollution in the coastal area. A total of 57 sampling sites were classified into three groups according to hierarchical cluster analysis (HCA). The δ¹⁵N-NO₃^? and δ¹⁸O-NO₃^? values of groundwater samples from Group C (including nine samples) were much higher than those from Group A (including 40 samples) and Group B (including 8 samples). SIAR results showed that NH₄⁺ fertilizer was the dominant nitrate source for groundwater samples of Groups A and B while manure and sewage (M&;S) served as dominant source for Group C. This study provided essential information on the high risk and pollution sources of coastal groundwater nitrate of northern China.