江苏省冬小麦湿渍害的风险区划

选取能较好反映冬小麦春季湿渍害特征的3个气象因子:旬降雨量、旬日照时数和旬雨日,计算了江苏省1960—2008期间历年3—5月这3个因子的逐旬统计值,分析了这些因子与冬小麦气候产量的关系,研究结果表明:(1)春季旬降雨量、旬雨日和旬日照时数对江苏省冬小麦气候产量有显著影响;(2)通径分析显示,旬降雨量和旬日照对气候产量有直接影响,而旬雨日对气候产量有间接影响;(3)构建了一个湿渍害判别指数Q用来判别湿渍害发生年份,并结合江苏省各地湿渍害年发生频率和冬小麦气候减产率,建立了冬小麦湿渍害风险指数模型;(4)利用所建风险指数模型对江苏省冬小麦的湿渍害风险进行了区划和评估,并提出了各风险区的防御对策。     

来源于泗阳鞘氨醇杆菌的聚磷酸激酶的克隆表达及在ATP再生系统中的应用

聚磷酸激酶(polyphosphate kinase,PPK)在体外催化合成ATP的反应中有着重要作用。为寻找能利用短链聚磷酸盐(polyphosphate,polyP)为底物高效合成ATP的聚磷酸激酶,本文以来源于泗阳鞘氨醇杆菌(Sphingobacterium siyangensis)的聚磷酸激酶(PPK2)为研究目标,利用pET-29a构建重组质粒,在大肠杆菌(Escherichia coli)BL21(DE3)中表达,并将其作为ATP再生系统的关键酶与l-氨基酸连接酶(YwfE)联用生产丙谷二肽(Ala-Gln)。ppk2长度为810bp,编码270个氨基酸;SDS-PAGE结果表明PPK2为可溶性表达,分子量为29.7kDa。对PPK2的最适反应条件进行了优化,结果发现其在22–42℃、pH7–10的范围内均可以保持较好活性,且在37℃、pH为7、镁离子(Mg²⁺)浓度为30mmol/L、底物ADP与六偏磷酸钠浓度分别为5mmol/L和10mmol/L时酶活最大,在0.5h时ATP产率可以达到理论值的60%以上。作为模式反应体系,当PPK2与YwfE联用生产Ala-Gln时,达到与直接添加ATP相同的效果。此聚磷酸激酶作为ATP再生系统具有较好的适用性,适用的温度和pH范围广,且能以廉价易得的短链polyP为底物高效合成ATP,为依赖ATP的催化反应体系的能量再生提供了新酶的来源。     

Cyclic biphalin analogues with a novel linker lead to potent agonist activities at mu,delta, and kappa opioid receptors

In an effort to improve biphalin’s potency and efficacy at the µ-(MOR) and δ-opioid receptors (DOR), a series of cyclic biphalin analogues 1–5 with a cystamine or piperazine linker at the C-terminus were designed and synthesized by solution phase synthesis using Boc-chemistry. Interestingly, all of the analogues showed balanced opioid agonist activities at all opioid receptor subtypes due to enhanced κ-opioid receptor (KOR) activity. Our results indicate that C-terminal flexible linkers play an important role in KOR activity compared to that of the other cyclic biphalin analogues with a hydrazine linker. Among them, analogue 5 is a potent (Ki?=?0.27, 0.46, and 0.87?nM; EC₅₀?=?3.47, 1.45, and 13.5?nM at MOR, DOR, and KOR, respectively) opioid agonist with high efficacy. Based on the high potency and efficacy at the three opioid receptor subtypes, the ligand is expected to have a potential synergistic effect on relieving pain and further studies including in vivo tests are worthwhile.     

Contribution of biofilm‐dwelling consumers to pelagic–benthic coupling in a large river

1. Over the course of this 17‐month study, we assessed the potential loss of plankton (bacteria, algae, heterotrophic flagellates) to consumers (ciliates and rotifers) within mature biofilms established on natural substrata exposed to the main current of the River Rhine (Germany). Once a month, in flow cells in a bypass system to the River Rhine, we measured the clearance rates of the biofilm‐associated consumers on the different groups within the natural plankton. 2. Ciliates were the most dominant consumers, among which planktivorous groups, particularly peritrichs and (in spring and summer) heterotrichs dominated. Consumer biomass varied with season, with the highest density occurring directly after the appearance of the phytoplankton spring peak. 3. Clearance rates on plankton ranged from 96 to 565 L m^?2 d^?1 for bacteria and 66–749 L m^?2 d^?1 for algae, with a preference for algae in summer and for bacteria in winter. This pattern coincided with seasonal changes in the structures of the grazer communities. The consumers (both ciliates and rotifers with total standing stocks ranging between 19 and 572 mg C m^?2) imported a substantial amount of organic matter (between 15 and 137 mg C m^?2 d^?1) into the biofilm. 4. These results highlight the potential importance of consumers in the biofilm as a trophic link between the plankton and the benthos, a function that has hitherto mostly been attributed to filter‐feeding bivalves. In contrast to bivalves, the biofilm‐dwelling consumers show a more dynamic response towards the plankton density and composition. Such dynamic components need to be considered when estimating total plankton consumption by the benthos.     

Subjecting the theory of the small‐island effect to Ockham’s razor

Species–area curves from islands and other isolates often differ in shape from sample‐area curves generated from mainlands or sections of isolates (or islands), especially at finer scales. We examine two explanations for this difference: (1) the small‐island effect (SIE), which assumes the species–area curve is composed of two distinctly different curve patterns; and (2) a sigmoid or depressed isolate species–area curve with no break‐points (in arithmetic space). We argue that the application of Ockham’s razor – the principle that the simplest, most economical explanation for a hypothesis should be accepted over less parsimonious alternatives – leads to the conclusion that the latter explanation is preferable. We hold that there is no reason to assume the ecological factors or patterns that affect the shapes of isolate (or island) curves cause two distinctly different patterns. This assumption is not required for the alternative, namely that these factors cause a single (though depressed) isolate species–area curve with no break‐points. We conclude that the theory of the small‐island effect, despite its present standing as an accepted general pattern in nature, should be abandoned.     

昆虫与寄主植物营养关系的DNA分子追踪

农田生态系统中昆虫与寄主植物的食物营养关系错综复杂,利用田间直接观察法、肠道内含物形态学分析、同位素标记等方法都难于全面解析,常造成营养关系的缺失。近年来,DNA分子追踪技术迅速发展,利用一段较短的DNA序列能有效鉴别植食性昆虫取食寄主植物的种类,为这一领域研究提供了新方法。本文全面介绍了3种DNA分子追踪技术——诊断PCR技术、克隆测序技术和下一代测序技术(next generation sequencing,NGS)。其中诊断PCR技术包括单一PCR技术和多重PCR技术,适用于目标昆虫与已知寄主植物之间的营养关系分析;克隆测序技术能够在寄主植物种类未知的前提下,解析目标昆虫完整的寄主植物种类信息;下一代测序技术实现了短时间内对混合样品的测序,加之昆虫与植物DNA条形码序列数据库大量扩增,有效地提高寄主植物的鉴别能力。诊断PCR技术和克隆测序技术已在追踪地下害虫的取食行为、植食性昆虫取食范围及其在寄主植物间的转移与选择习性等方面被广泛应用,且进展明显。综合考虑各种技术的优缺点,本文提出将DNA分子追踪技术与同位素标记等其他方法相结合的研究策略,以便系统解析农田生态系统中昆虫与寄主植物之间的营养关系。     

三叉神经中脑核神经元膜的电学特性

用大鼠脑干脑片,给三叉神经中脑核79个神经元作了细胞内记录,测算了20个神经元膜的电学特性:静息电位-60.3±5.6mV;输入阻抗为10.5±5.4MΩ;时间常数1.3±0.5ms。电刺激可诱发动作电位,测算32个神经元的有关参数:阈电位-50—-55mV;波幅69.5±6.1mV;超射11.9±3.6mV;波宽0.8±0.2ms。TTX(0.3μmol/L)或无钠使之消失。通以长时程矩形波电流可引起200—250Hz的2—15个重复放电,但在通电停止前终止,TEA或4-AP可延长放电。膜电位-60—-55mV时在动作电位之后可看到阈下电位波动,它不受TTX的影响,无钙时消失,TEA或4-AP使波幅增大。静息电位去极化可使45个神经元中的40个发生外向整流作用,并被TEA,4-AP或无钙抑制,超极化则发生内向整流作用,Cs或无钠抑制之。灌流液中加入各种钾通道阻断药时神经元的稳态I-V曲线发生相应变化,提示I_(DR),l_A,I_(K(Ca))及I_Q可能都与静息时的膜电导有关。     

高压蒸汽灭菌器中温度与压力的关系*

应用Clausius-Clapeyron方程、波义耳定律和道尔顿分压定律,分析高压蒸汽灭菌器中混合气体温度和压力的关系。以献数据建立了灭菌器中残留不同量空气时的Antoine方程,导出以压力表读数计算温度的方法。对灭菌时排放空气的必要性给予理论解释。     

Quantitative structure–activity relationship analysis using deep learning based on a novel molecular image input technique

Quantitative structure–activity relationship (QSAR) analysis uses structural, quantum chemical, and physicochemical features calculated from molecular geometry as explanatory variables predicting physiological activity. Recently, deep learning based on advanced artificial neural networks has demonstrated excellent performance in the discipline of QSAR research. While it has properties of feature representation learning that directly calculate feature values from molecular structure, the use of this potential function is limited in QSAR modeling. The present study applied this function of feature representation learning to QSAR analysis by incorporating 360° images of molecular conformations into deep learning. Accordingly, I successfully constructed a highly versatile identification model for chemical compounds that induce mitochondrial membrane potential disruption with the external validation area under the receiver operating characteristic curve of ≥0.9.