Responses of the biting midge Culicoides impunctatus to acetone, CO2 and 1-octen-3-ol in a wind tunnel

Responses of host-seeking female Culicoides impunctatus (Goetghebuer) (Diptera: Ceratopogonidae) to acetone, carbon dioxide and 1-octen-3-ol were measured in a wind tunnel. Carbon dioxide, presented as a filamentous plume, increased upwind flight in a dose-dependent manner, up to 0.09% concentration. A homogenous CO2 plume elicited similar upwind responses at concentrations up to 0.09%, whereas higher plume concentrations (> 0.1%) induced erratic responses with a suppression of upwind flight. Bovine equivalent concentrations of acetone (1.5 x 10(-6)g/l) and 1-octen-3-ol (1.3 x 10(-8)g/) failed to induce any significant upwind response when tested alone. In the presence of CO2, however, 1-octen-3-ol showed highly significant increases in upwind responses at concentrations of 1.3 x 10(-1) - 10(-8)g/l. Mixtures of CO2+ acetone also enhanced upwind flight at 1.5 x 10(-9)g/l. High tunnel concentrations of both 1-octen-3-ol and acetone inhibited upwind responses. These findings are discussed in relation to host finding by C. impunctatus and known mechanisms by which upwind flight is initiated and arrested at high odour concentrations.     

黄斑卷蛾雄蛾对性信息素的行为反应

分别在风洞中和田间观察了黄斑卷蛾Acleris fimbriana Thunberg et Becklin雄蛾对合成性信息素三种成分（E11,13-14∶Ald, E11,13-14∶Ac和E11-14∶Ac）及其不同组合的行为反应。在风洞中,主要活性成分E11,13-14∶Ald能引起雄蛾完成从兴奋到搜索释放源的行为反应,但雄蛾对单个组分E11,13-14∶Ac 或 E11-14∶Ac不呈现任何行为反应。当释放源为双组分 E11,13-14∶Ald＋E11,13-14∶Ac （6∶4）或三组分E11,13-14∶Ald＋E11,13-14∶Ac＋E11-14∶Ac（6∶4∶1）时,可以明显增加雄蛾定向飞行和到达释放源的数量。三组分 E11,13-14∶Ald＋E11,13-14∶Ac＋E11-14∶Ac的比例为6∶4∶1时,500 μg剂量效果最好。田间试验结果表明,E11,13-14∶Ald单独使用表现出良好的诱蛾活性,其诱蛾量为活雌蛾的1.9倍,而E11,13-14∶Ac和E11-14∶Ac则不具有诱蛾活性。E11,13-14∶Ac对E11,13-14∶Ald有明显的增效作用,三组分E11,13-14∶Ald＋E11,13-14∶Ac＋E11-14∶Ac（6∶4∶1）诱芯的诱蛾效果最好。     

粘虫成虫在气流场中飞行行为的观察研究

通过改进悬吊测飞技术、室内风洞和野外雷达相结合的观测方法,研究了粘虫在气流场中的飞行行为特征及其与气流的关系。直筒风洞自由飞行观测的结果表明,粘虫蛾对气流有明显行为反应,表现为头部迎风起飞和迎风飞行的特性;在3.0～5.5 m/s风速下,有92%～94% 的个体可一次逆风飞行通过2 m长的风洞;当风速≥6.0 m/s时,有71.9%的蛾子沿螺旋状的飞行轨迹逆风通过风洞。环形风洞悬吊飞行测试的结果表明,粘虫可逆风飞行的最大风速为7.2 m/s;在风速≤4 m/s条件下,90%以上个体头部迎风飞行或头部朝向与风向成一定的夹角,侧逆风飞行。 雷达观测发现粘虫在空中迁飞过程中具有成层现象,并有较强的秋季回迁定向行为,其头部总是朝向西南;迁飞的最终位移与风向及风速大小有关,迁飞位移速度是飞行速度与风速的矢量和。     

Environmental conditions terminate reproductive diapause and influence pheromone perception in the long‐lived moth Caloptilia fraxinella

Reproductive diapause enables long‐lived insects to time mating with environmental conditions suitable for offspring development. Plasticity in the perception of pheromones used in sexual communication may enable mate‐finding at the appropriate time of year. The moth Caloptilia fraxinella (Ely) (Lepidoptera: Gracillariidae) undergoes a 9‐month reproductive diapause, during which the male response to pheromone is plastic and is highest during the period of reproductive activity. The mechanisms controlling this pheromone response plasticity are not well‐understood, and the aim of the present study is to determine the main factors involved. In the present study, the impact of temperature, photoperiod, juvenile hormone analogue (JHA) and adult nutrition on diapause termination are tested using electroantennogram (EAG) and behavioural response to pheromone in male C. fraxinella. Eclosion in a state of reproductive diapause occurs in most males; diapause is maintained under short‐day or cool conditions indoors, or under natural conditions outdoors. Exposure to long‐day, warm conditions over a period of 4 weeks causes a small number of males to become behaviourally responsive to pheromone; a larger number of males become behaviourally responsive over a period of 3 months of post‐eclosion. Treatment with a JHA impacts male EAG and the behavioural response to pheromone during the period of reproductive diapause. A carbohydrate food source is not required by reproductively active adult male C. fraxinella to respond to pheromone and express mate location behaviours. The main factors involved in controlling male pheromone response plasticity and the implications of these factors for the C. fraxinella population in its expanded range are discussed.     

Site conditions exert more control than genetic differentiation on modulation of secondary growth and climate sensitivity of Pinus pinaster

The adaptive potential and genetic background of tree species will determine their performance and vitality under changing climate conditions. How environment and genotype influence secondary growth and their climate sensitivity in boreal and temperate conifers has been fairly studied. Provenance studies assessing the genetic variation in plasticity of radial growth, however, are scarce in Mediterranean tree species. We explored the impact of climate on tree-ring growth in Pinus pinaster based on plantation sites and genetic background. We assessed the climate sensitivity, plastic response of growth, and intraspecific genetic differentiation of pines from 10 provenances planted in two trials in south-central Spain. Trees from areas with a climate similar to that of the planting sites showed greater growth rates. Higher within-site than among-site similitude in inter-annual growth variation was evidenced by similar growth patterns in each trial test, irrespective of seed provenance. We found positive growth responses to mild conditions in late winter, and to wet and cloudy conditions in spring and early summer. Greater site-dependent than genetically-driven control was observed on growth sensitivity to climate. Central Spanish seed sources were better able to withstand the combination of stressful environmental conditions in the test sites. Inter-site environmental variation was the factor that explained a higher number of growth responses to climate variation. The significant “genetic × environment” interaction on radial growth suggested that genotypic determinants were strongly modulated by plastic adaptations due to local conditions. The site-dependent relationships of provenance climate responses with the conditions at origin also reflected the prevailing local adaptation to site constraints. Since plastic response of P. pinaster trees to local environment has more influence than its genetic predisposition, assessing the spatio-temporal variation of growth sensitivity to climate becomes increasingly important.     

神经传导测定技术对腕管综合征病情评估的价值

目的:近年来腕管综合征发病率逐年升高,然而其慢性、隐匿性不易引起人们的重视,发现时往往已造成较大的危害。本文探讨腕管综合征的神经传导测定对病情评估的临床价值,旨在为患者腕管综合征早期发现和后续治疗提供进一步的临床参考依据。方法:选取我院124例确诊的腕管综合征患者。其中无大鱼际肌萎缩者有64例,并选取平均年龄相近的64例正常人作为对照(组A);有大鱼际肌畏缩者60例,并选取平均年龄相近的60例正常人作为对照(组B)。A、B组均经行神经电图检查,握力测定和两点辨别觉测定,分析神经传导速度改变与感觉、运动功能减退程度的关系。结果:A、B两组患者均有不同程度的神经传导改变:在A组患者神经传导改变中,运动和感觉传导速度(MCV和SCV)轻度下降,运动和感觉电位波幅(CMAP和SNAP)轻度下降,潜伏期(ML)轻度延长;在B组患者神经传导中,运动和感觉传导速度(MCV和SCV)明显下降,运动和感觉电位波幅(CMAP和SNAP)明显下降,潜伏期明显延长。结论:腕管综合征患者不同的临床表现有不同程度的神经电图表现,因此神经电图对神经传导的测定结果对腕管综合征患者的病情有良好的评估价值,值得临床推广。     

Structural determinants of specificity and catalytic mechanism in mammalian 25-kDa thiamine triphosphatase

Background

Thiamine triphosphate (ThTP) is present in most organisms and might be involved in intracellular signaling. In mammalian cells, the cytosolic ThTP level is controlled by a specific thiamine triphosphatase (ThTPase), belonging to the CYTH superfamily of proteins. CYTH proteins are present in all superkingdoms of life and act on various triphosphorylated substrates.

Methods

Using crystallography, mass spectrometry and mutational analysis, we identified the key structural determinants of the high specificity and catalytic efficiency of mammalian ThTPase.

Results

Triphosphate binding requires three conserved arginines while the catalytic mechanism relies on an unusual lysine–tyrosine dyad. By docking of the ThTP molecule in the active site, we found that Trp-53 should interact with the thiazole part of the substrate molecule, thus playing a key role in substrate recognition and specificity. Sea anemone and zebrafish CYTH proteins, which retain the corresponding Trp residue, are also specific ThTPases. Surprisingly, the whole chromosome region containing the ThTPase gene is lost in birds.

Conclusions

The specificity for ThTP is linked to a stacking interaction between the thiazole heterocycle of thiamine and a tryptophan residue. The latter likely plays a key role in the secondary acquisition of ThTPase activity in early metazoan CYTH enzymes, in the lineage leading from cnidarians to mammals.

General significance

We show that ThTPase activity is not restricted to mammals as previously thought but is an acquisition of early metazoans. This, and the identification of critically important residues, allows us to draw an evolutionary perspective of the CYTH family of proteins.     

New insights into polyurethane biodegradation and realistic prospects for the development of a sustainable waste recycling process

Polyurethanes are polymeric plastics that were first used as substitutes for traditional polymers suspected to release volatile organic hazardous substances. The limitless conformations and formulations of polyurethanes enabled their use in a wide variety of applications. Because approximately 10 Mt of polyurethanes is produced each year, environmental concern over their considerable contribution to landfill waste accumulation appeared in the 1990s. To date, no recycling processes allow for the efficient reuse of polyurethane waste due to their high resistance to (a)biotic disturbances. To find alternatives to systematic accumulation or incineration of polyurethanes, a bibliographic analysis was performed on major scientific advances in the polyurethane (bio)degradation field to identify opportunities for the development of new technologies to recondition this material. Until polymers exhibiting oxo- or hydro-biodegradative traits are generated, conventional polyurethanes that are known to be only slightly biodegradable are of great concern. The research focused on polyurethane biodegradation highlights recent attempts to reprocess conventional industrial polyurethanes via microbial or enzymatic degradation. This review describes several wonderful opportunities for the establishment of new processes for polyurethane recycling. Meeting these new challenges could lead to the development of sustainable management processes involving polymer recycling or reuse as environmentally safe options for industries. The ability to upgrade polyurethane wastes to chemical compounds with a higher added value would be especially attractive.     

Host-locating response by the aphid parasitoid Aphidius ervi to tomato plant volatiles

Abstract

The blend of volatile compounds emitted by tomato plants (Solanum lycopersicum) infested with the potato aphid (Macrosiphum euphorbiae) has been studied comparatively with undamaged plants and aphids themselves. Aphid-infested plants were significantly more attractive towards Aphidius ervi than undamaged plants and aphids themselves. Oriented response towards host-damaged plant, from which aphids were removed just before running the bioassay, did not differ from that recorded for infested plants. Collection of the volatiles and analysis by gas chromatography revealed only quantitative differences between uninfested and aphid-infested plants. Nine compounds, α-pinene, (Z)-3-hexen-1-ol, α-phellandrene, limonene, (E)-β-ocimene, p-cymene, methyl salicylate, (E)-β-caryophyllene and an unknown compound, were emitted at higher levels from aphid-infested plants than from undamaged control plants, whilst no differences were noted for hexanal, 6-methyl-5-hepten-2-one, and humulene (=α-caryophyllene). Synthetic standards of these compounds were tested in wind tunnel bioassays and all elicited a significant increase in oriented flight and landings on the target by the aphid parasitoid Aphidius ervi. (E)-β-caryophyllene resulted the most attractive towards female wasps. These results corroborate the hypothesis that the volatiles produced by the plant in response to aphid attack derive from both jasmonic and salicylic acid pathways, and are exploited by A. ervi as olfactory cues to locate its hosts.