Changes in haemolymph parameters and insect ability to respond to immune challenge during overwintering

Overwintering is a challenging period in the life of temperate insects. A limited energy budget characteristic of this period can result in reduced investment in immune system. Here, we investigated selected physiological and immunological parameters in laboratory‐reared and field‐collected harlequin ladybirds (Harmonia axyridis). For laboratory‐reared beetles, we focused on the effects of winter temperature regime (cold, average, or warm winter) on total haemocyte concentration aiming to investigate potential effects of ongoing climate change on immune system in overwintering insects. We recorded strong reduction in haemocyte concentration during winter; however, there were only limited effects of winter temperature regime on changes in haemocyte concentration in the course of overwintering. For field‐collected beetles, we measured additional parameters, specifically: total protein concentration, antimicrobial activity against Escherichia coli, and haemocyte concentration before and after overwintering. The field experiment did not investigate effects of winter temperature, but focused on changes in inducibility of insect immune system during overwintering, that is, measured parameters were compared between naïve beetles and those challenged by Escherichia coli. Haemocyte concentration decreased during overwintering, but only in individuals challenged by Escherichia coli. Prior to overwintering, the challenged beetles had a significantly higher haemocyte concentration compared to naïve beetles, whereas no difference was observed after overwintering. A similar pattern was observed also for antimicrobial activity against Escherichia coli as challenged beetles outperformed naïve beetles before overwintering, but not after winter. In both sexes, total protein concentration increased in the course of overwintering, but females had a significantly higher total protein concentration in their hemolymph compared to males. In general, our results revealed that insect’s ability to respond to an immune challenge is significantly reduced in the course of overwintering.     

An electrostatic basis for the stability of thermophilic proteins

Two factors provide key contributions to the stability of thermophilic proteins relative to their mesophilic homologues: electrostatic interactions of charged residues in the folded state and the dielectric response of the folded protein. The dielectric response for proteins in a "thermophilic series" globally modulates the thermal stability of its members, with the calculated dielectric constant for the protein increasing from mesophiles to hyperthermophiles. This variability results from differences in the distribution of charged residues on the surface of the protein, in agreement with structural and genetic observations. Furthermore, the contribution of electrostatic interactions to the stability of the folded state is more favorable for thermophilic proteins than for their mesophilic homologues. This leads to the conclusion that electrostatic interactions play an important role in determining the stability of proteins at high temperatures. The interplay between electrostatic interactions and dielectric response also provides further rationalization for the enhanced stability of thermophilic proteins with respect to cold-denaturation. Taken together, the distribution of charged residues and their fluctuations have been shown to be factors in modulating protein stability over the entire range of biologically relevant temperatures.     

区域气候背景对城市热岛效应的影响规律

城市热岛效应受到区域气候背景的影响而具有显著的时空差异性,尚缺少大尺度对比研究。利用1991-2019年的月均气象数据,量化了我国69个典型城市的大气城市热岛效应强度,从热带、干带、暖温带、冷温带和极地带五个气候带,分析城市热岛效应的时空特征规律。结果表明：（1）区域差异：干带热岛效应明显高于其他气候带,极地带最弱,且表现为较强的冷岛效应,热带、暖温带、冷温带热岛效应较弱,而冷温带的京津冀地区由于城市化程度较高,表现出较强的热岛效应,温暖带中西南地区较为明显;（2）季节性差异：不同季节城市热岛效应的强弱关系在不同气候带有所不同,秋季热岛效应较为稳定,热岛和冷岛效应均主要处于弱强度范围,春、冬热岛效应较为波动,易出现强热岛、强冷岛效应的极端现象,夏季热岛效应发生率最高;（3）时间演变规律：城市热岛效应的多年演变规律在相同气候带较为一致,2010年前后是各气候带各季节城市热岛效应的变化拐点,2010年后,干带、冷温带、暖温带热岛效应均有所下降,热带、极地带有所上升。     

自交对白菜型冬油菜生理生化特性及抗寒性的影响

为了解自交对白菜型冬油菜后代生理生化特性及抗寒性的影响,以6份白菜型冬油菜为材料,研究了在越冬降温前与降温后,自交和开放授粉后代植株叶片生理生化指标及越冬率的变化。结果表明:(1)除MDA含量外,无论是降温前还是降温后,白菜型冬油菜自交后代植株叶片中的SOD、CAT、POD的活性以及可溶性蛋白和游离脯氨酸含量都较开放授粉表现出不同程度的降低,其幼苗越冬率也较开放授粉植株显著降低。(2)与降温前相比,降温后所有测定指标在两种授粉方式后代中都表现为上升的趋势,其中以CAT活性变化最为显著。研究认为,自交会使白菜型冬油菜后代植株叶片中保护酶活性及可溶性蛋白和游离脯氨酸含量明显降低,MDA含量升高,导致幼苗的越冬率显著下降,进而引起其植株抗寒性减弱。     

甘肃省麻疹减毒活疫苗强化免疫疑似接种异常反应分析

目的分析甘肃省2010年和2011年麻疹减毒活疫苗(Measles vaccine,live MV)强化免疫活动中疑似预防接种异常反应(Adverse events following immunization,AEFI)发生特征,评价AEFI监测工作。方法收集2010年和2011年甘肃省AEFI监测系统报告数据,采用描述性流行病学方法对相关数据进行分析。结果甘肃省2010年和2011年MV强化免疫活动共报告AEFI病例346例,报告发生率为14.17/100万,男性略多于女性。一般反应报告发生率为12.82/100万,异常反应报告发生率为1.19/100万,异常反应主要以过敏性皮疹为主。接种MV后,发生AEFI的时间多在1 d之内,占总报告病例数的76.41%,并呈现随着年龄增大发生率逐渐降低的趋势。结论两次MV强化免疫活动AEFI报告发生率较低,接种MV后的1 d之内需要重点监测,加强主动监测,提高AEFI的预防和处理水平。     

Purification and characterization of antifreeze proteins from larvae of the beetle Dendroides canadensis

Summary Four antifreeze proteins (AFPs) were purified from larvae of the beetle Dendroides canadensis. The AFPs are similar in amino acid compositions, having high contents of hydrophilic amino acids (45–55 mol%) and cysteine (16 mol% Cys). Approximately half of the Cys residues form disulfide bridges, and both the disulfide bridges and free sulfhydryls are essential for activity. The N-terminals of the AFPs are blocked. The pH optimum of the AFPs is 7.8, but major loss of activity occurred only at very high pH (12.0). The detergents SDS and Triton X-100 did not inactivate the AFPs. Circular dichroism spectra indicate the presence of both and secondary structures in the AFPs, in addition to a large random structure component.Abbreviations AFP antifreeze protein - CD circular dichroism - DTT dithiothreitol - HPLC high pressure liquid chromatography - PAGE polyacrylamide gel electrophoresis - PAS periodic acid Schiff - SDS sodium dodecyl sulfate - TFA trifluoroacetic acid     

Mechanisms underlying insect freeze tolerance

Freeze tolerance – the ability to survive internal ice formation – has evolved repeatedly in insects, facilitating survival in environments with low temperatures and/or high risk of freezing. Surviving internal ice formation poses several challenges because freezing can cause cellular dehydration and mechanical damage, and restricts the opportunity to metabolise and respond to environmental challenges. While freeze‐tolerant insects accumulate many potentially protective molecules, there is no apparent ‘magic bullet’ – a molecule or class of molecules that appears to be necessary or sufficient to support this cold‐tolerance strategy. In addition, the mechanisms underlying freeze tolerance have been minimally explored. Herein, we frame freeze tolerance as the ability to survive a process: freeze‐tolerant insects must withstand the challenges associated with cooling (low temperatures), freezing (internal ice formation), and thawing. To do so, we hypothesise that freeze‐tolerant insects control the quality and quantity of ice, prevent or repair damage to cells and macromolecules, manage biochemical processes while frozen/thawing, and restore physiological processes post‐thaw. Many of the molecules that can facilitate freeze tolerance are also accumulated by other cold‐ and desiccation‐tolerant insects. We suggest that, when freezing offered a physiological advantage, freeze tolerance evolved in insects that were already adapted to low temperatures or desiccation, or in insects that could withstand small amounts of internal ice formation. Although freeze tolerance is a complex cold‐tolerance strategy that has evolved multiple times, we suggest that a process‐focused approach (in combination with appropriate techniques and model organisms) will facilitate hypothesis‐driven research to understand better how insects survive internal ice formation.     

植物抗寒基因表达调控研究进展

低温胁迫是植物生长过程中的主要非生物胁迫因子之一,也是影响农作物生产的主要因素之一。研究表明,在植物体内存在着一个复杂的对低温胁迫信号感知及传导的网络系统,该系统中大量的相关基因已有报道,这些基因不仅仅涉及植物激素的应答,还涉及到植物基因的转录调控及转录后的修饰与调控等各个方面。该文就近年来国内外有关植物抗寒基因表达调控的研究进展进行综述。