Cd2+和Pb2+对花翅摇蚊(Chironomus kiiensis)幼虫生长发育的影响及富集效应

河流、湖泊等水生环境中普遍存在的重金属污染破坏水生生态系统并间接威胁人类健康。为探究重金属胁迫下水生昆虫花翅摇蚊（Chironomus kiiensis）生态毒理,测定了重金属Cd²⁺和Pb²⁺胁迫对花翅摇蚊化蛹率和羽化率的影响,检测了摇蚊的口器致畸与富集效应。研究结果表明,Cd²⁺和Pb²⁺影响摇蚊幼虫化蛹和羽化过程,单一重金属离子处理14 d Pb²⁺处理组的化蛹率和羽化率分别为22.22%和8.89%,低于Cd²⁺的化蛹率（25.56%）和羽化率（11.11%）,表现出更强的抑制效应。混合离子1：2和2：1配比处理组化蛹率和羽化率均为11.11%和4.44%,显著低于单一重金属离子胁迫下的化蛹率和羽化率。单一重金属离子及混合离子处理均能导致花翅摇蚊幼虫口器致畸,表现为上颚前齿断裂,中齿和基齿磨损、缺失,下唇板齿部不规则,下唇板边缘齿与中央齿磨损、断裂、增生、缺失。不同重金属离子处理下幼虫口器致畸率不同,并与暴露时间呈正相关,其中1：2配比处理14 d致畸率达到40.61%。重金属离子在摇蚊幼虫体内产生生物富集效应,单一重金属离子处理下的Pb²⁺富集含量7 d至14 d由11.46 mg/kg上升至31.32 mg/kg,不同配比混合离子处理下Pb²⁺富集含量均呈增加趋势,其中1：2配比处理组由15.48 mg/kg上升至42.50 mg/kg,而Cd²⁺在单一重金属与1：1混合离子处理组7 d至14 d的富集含量无显著性变化,2：1配比处理组由14.20 mg/kg下降至9.52 mg/kg,1：2配比由5.85 mg/kg上升至20.99 mg/kg。这些研究结果表明Cd²⁺和Pb²⁺胁迫影响花翅摇蚊幼虫生长发育且口器出现畸型,与重金属在幼虫体内的富集密切相关,为研究重金属对水生生态系统多重效应提供了理论依据。     

Peptide probes containing a non-hydrolyzable phosphotyrosine-mimetic residue for enrichment of protein tyrosine phosphatases

We developed peptide probes containing a non-hydrolyzable phosphotyrosine mimetic, 4-[difluoro(phosphono)methyl]-L-phenylalanine (F₂Pmp) for the enrichment of protein tyrosine phosphatases (PTPs). We found that different F₂Pmp probes can enrich different PTPs, depending on the probe sequence. Furthermore, proteins containing a Src homology 2 (SH2) domain were enriched together. Importantly, probes containing phosphotyrosine instead of F₂Pmp failed to enrich PTPs due to dephosphorylation during the pulldown step. This enrichment approach using peptides containing F₂Pmp could be a generic tool for tyrosine phosphatome analysis without the use of antibodies.     

Anoxybacillus sp. SO B1–Immobilized Amberlite XAD-16 for Solid-Phase Preconcentration of Cu(II) and Pb(II) and Their Determinations by Flame Atomic Absorption Spectrometry

A new method for the determination of Cu(II) and Pb(II) by flame atomic absorption spectrometry (FAAS) after preconcentrating on a column containing Anoxybacillus sp. SO B1–immobilized Amberlite XAD-16 was developed. The functional groups of Anoxybacillus sp. SO B1 immobilized on Amberlite XAD-16 were characterized in KBr tablets by Fourier transform infrared (FT-IR) spectrometry. Various parameters such as pH, amount of the adsorbent, eluent type and volume, and flow rate of the sample solution were studied. The optimum pH values of quantitative sorption for Cu(II) and Pb(II) were found to be pH 7.0 and 5.0 and Cu(II) and Pb(II) ions could be quantitatively eluted with 5.0 ml of 1.0 mol L^?1 HCI and 10.0 ml of 0.25 mol L^?1 HNO₃, respectively. Recoveries of Cu(II) and Pb(II) were found to be 100.9 ± 1.57% and 100.3 ± 0.49% (N = 5), the limits of detection of Cu(II) and Pb(II) in the determination by FAAS (3 s, N = 10) were found to be 0.8 and 1.6 μg L^?1, respectively. The proposed enrichment method was applied for metal ion determination from water samples such as two parts of Tigris River water in Diyarbak?r and Elaz??, Lake of Hazar in Elaz??, and tap water in Diyarbak?r. Furthermore, the accuracy of the proposed method was verified by studying the analytical recovery and by analyzing certified reference material (NCS-DC 73350 leaves of poplar).     

Canopy warming caused photosynthetic acclimation and reduced seed yield in maize grown at ambient and elevated [CO2]

Rising atmospheric CO₂ concentration ([CO₂]) and attendant increases in growing season temperature are expected to be the most important global change factors impacting production agriculture. Although maize is the most highly produced crop worldwide, few studies have evaluated the interactive effects of elevated [CO₂] and temperature on its photosynthetic physiology, agronomic traits or biomass, and seed yield under open field conditions. This study investigates the effects of rising [CO₂] and warmer temperature, independently and in combination, on maize grown in the field throughout a full growing season. Free‐air CO₂ enrichment (FACE) technology was used to target atmospheric [CO₂] to 200 μmol mol^?1 above ambient [CO₂] and infrared heaters to target a plant canopy increase of 3.5 °C, with actual season mean heating of ~2.7 °C, mimicking conditions predicted by the second half of this century. Photosynthetic gas‐exchange parameters, leaf nitrogen and carbon content, leaf water potential components, and developmental measurements were collected throughout the season, and biomass and yield were measured at the end of the growing season. As predicted for a C₄ plant, elevated [CO₂] did not stimulate photosynthesis, biomass, or yield. Canopy warming caused a large shift in aboveground allocation by stimulating season‐long vegetative biomass and decreasing reproductive biomass accumulation at both CO₂ concentrations, resulting in decreased harvest index. Warming caused a reduction in photosynthesis due to down‐regulation of photosynthetic biochemical parameters and the decrease in the electron transport rate. The reduction in seed yield with warming was driven by reduced photosynthetic capacity and by a shift in aboveground carbon allocation away from reproduction. This field study portends that future warming will reduce yield in maize, and this will not be mitigated by higher atmospheric [CO₂] unless appropriate adaptation traits can be introduced into future cultivars.     

Editor's choice: Highly sensitive targeted methylome sequencing by post-bisulfite adaptor tagging

The current gold standard method for methylome analysis is whole-genome bisulfite sequencing (WGBS), but its cost is substantial, especially for the purpose of multi-sample comparison of large methylomes. Shotgun bisulfite sequencing of target-enriched DNA, or targeted methylome sequencing (TMS), can be a flexible, cost-effective alternative to WGBS. However, the current TMS protocol requires a considerable amount of input DNA and hence is hardly applicable to samples of limited quantity. Here we report a method to overcome this limitation by using post-bisulfite adaptor tagging (PBAT), in which adaptor tagging is conducted after bisulfite treatment to circumvent bisulfite-induced loss of intact sequencing templates, thereby enabling TMS of a 100-fold smaller amount of input DNA with far fewer cycles of polymerase chain reaction than in the current protocol. We thus expect that the PBAT-mediated TMS will serve as an invaluable method in epigenomics.     

Phosphorus application and elevated CO2 enhance drought tolerance in field pea grown in a phosphorus-deficient vertisol

Background and Aims Benefits to crop productivity arising from increasing CO₂ fertilization may be offset by detrimental effects of global climate change, such as an increasing frequency of drought. Phosphorus (P) nutrition plays an important role in crop responses to water stress, but how elevated CO₂ (eCO₂) and P nutrition interact, especially in legumes, is unclear. This study aimed to elucidate whether P supply improves plant drought tolerance under eCO₂.Methods A soil-column experiment was conducted in a free air CO₂ enrichment (SoilFACE) system. Field pea (Pisum sativum) was grown in a P-deficient vertisol, supplied with 15 mg P kg⁻¹ (deficient) or 60 mg P kg⁻¹ (adequate for crop growth) and exposed to ambient CO₂ (aCO₂; 380–400 ppm) or eCO₂ (550–580 ppm). Drought treatments commenced at flowering. Measurements were taken of soil and leaf water content, photosynthesis, stomatal conductance, total soluble sugars and inorganic P content (Pi).Key Results Water-use efficiency was greatest under eCO₂ when the plants were supplied with adequate P compared with other treatments irrespective of drought treatment. Elevated CO₂ decreased stomatal conductance and transpiration rate, and increased the concentration of soluble sugars and relative water contents in leaves. Adequate P supply increased concentrations of soluble sugars and Pi in drought-stressed plants. Adequate P supply but not eCO₂ increased root length distribution in deeper soil layers.Conclusions Phosphorus application and eCO₂ interactively enhanced periodic drought tolerance in field pea as a result of decreased stomatal conductance, deeper rooting and high Pi availability for carbon assimilation in leaves.     

Assessing the suitability of five benthic indices for environmental health assessment in a large subtropical South American estuary

Despite the increased and widespread usage of benthic indices for environmental health assessment, some methodological ambiguities remain to be solved. We tested the congruence and consistency of the benthic indices ITI, BO2A, BENTIX, AMBI and M-AMBI in a subtropical estuary (Paranaguá Bay, Brazil). Indices were applied to non-vegetated tidal flats increasingly contaminated by sewage to test: (i) correlations with molecular biomarkers of sewage (consistency); and (ii) evaluate the overall agreement/similarity of responses (congruence). The responses of the benthic indexes ITI, AMBI and BO2A were congruent among themselves and consistent with molecular biomarkers values. BENTIX and M-AMBI were less consistent and congruent and possibly need a readjustment of boundaries for subtropical habitats. The indices seemed robust to natural background yearly variations not related to contamination. Faecal sterols associated to nutrient contents suitably supported the validation of indices and could integrate reference conditions for sewage impacted coastal habitats. Benthic indices can successfully integrate management guidelines, but their suitable application demands further research on tolerance shifts of key indicator species.     

开放条件下高聚β-羟基丁酸酯含量的甲烷氧化混合菌群的富集

目的:在开放条件下以甲烷为底物富集高聚β-羟基丁酸酯(PHB)含量的甲烷氧化菌群,获得能够利用低成本碳源高产PHB的菌种。方法:采用丰盛-饥饿模式间歇供料,以甲烷为底物,好氧开放式培养甲烷氧化混合菌群,利用苏丹黑染色法动态检测丰盛和饥饿阶段胞内PHB含量的变化,以此为基础考察丰盛-饥饿期比例对富集高PHB含量的甲烷氧化菌群的影响。结果:丰盛-饥饿期比例为1∶3时,微生物PHB含量从17.7%增加到35.5%,且开放培养过程中菌群结构稳定。结论:通过丰盛-饥饿模式间歇供料开放式培养所得的高PHB含量的稳定的甲烷氧化菌群,具有工业生产PHB的应用价值。     

Growth, senescence and water use efficiency of spring oilseed rape (Brassica napus L. cv. Mozart) grown in a factorial combination of nitrogen supply and elevated CO2

Atmospheric CO₂ enrichment is expected to affect the resource use efficiency of C3 plants with respect to water, nutrients and light in an interactive manner. The responses of oilseed rape (OSR) to elevated CO₂ have not much been addressed. Since the crop has low nitrogen use efficiency, the interactive effects of CO₂ enrichment and nitrogen supply deserve particular attention.Spring OSR was grown in climate chambers simulating the seasonal increments of day length and temperature in South-Western Germany. Three levels of N fertilisation representing 75, 150 and 225 kg ha⁻¹ and two CO₂ concentrations (380 and 550 μmol mol⁻¹) were used to investigate changes in source-sink relationships, plant development and senescence, water use efficiency of the dry matter production (WUE_prod.), allocation patterns to different fractions, growth, yield and seed oil contents. Seven harvests were performed between 72 and 142 days after sowing (DAS).Overall, plant performance in the chambers was comparable to the development under field conditions. While CO₂ responses were small in the plants receiving lowest N-levels, several significant N × CO₂ interactions were observed in the other treatments. Increasing the N availability resulted in longer flowering windows, which were furthermore extended at elevated CO₂ concentrations. Nevertheless, significantly less biomass was allocated to reproductive structures under elevated CO₂, while the vegetative C-storing organs continued to grow. At the final harvest shoot mass of the CO₂ exposed plants had increased by 9, 8 and 15% in the low, medium and high N treatments. Root growth was increased even more by 17, 43 and 33%, respectively and WUE_prod. increased by 23, 42 and 35%. At the same time, seed oil contents were significantly reduced by CO₂ enrichment in the treatments with ample N supply.Obviously, under high N-supply, the CO₂ fertilisation induced exaggerated growth of vegetative tissues at the expense of reproductive structures. The interruption of source-sink relationships stimulated the formation of side shoots and flowers (branching out). While direct effects of elevated CO₂ on flowering can be excluded, we assume that the increased growth under high N and CO₂ supply created nutrient imbalances which hence affected flowering and seed set.Nevertheless, the final seed macronutrient concentrations were slightly increased by elevated CO₂, indicating that remobilisation of nutrients from the sources (leaves) to the sinks (seeds) remained effective. These findings were supported by the lower nitrogen concentrations in senescing leaves and probably increased N remobilisation to other plant parts under elevated concentrations of CO₂. All the same, CO₂ enrichment caused a decline in seed oil contents, which may translate into a reduced crop quality.