基于人工嗅觉系统的土壤有机质检测方法研究

为了实现土壤有机质快速、准确的测量,提出了一种基于人工嗅觉的土壤有机质含量检测方法。首先,由不同温度控制的10个气体传感器所构成的阵列对土壤样品气体进行采集;然后,提取每个传感器响应曲线上的7个特征(包括最大值、最小值、平均值、平均微分系数、响应面积、第30秒的瞬态值和第60秒的瞬态值),构建嗅觉特征空间;对特征空间优化后,采用回归算法建立预测模型。为减小不同测定算法、异常样本以及冗余特征对模型预测性能的影响,在应用蒙特卡罗抽样(Monte Carlo sampling,MCS)法剔除异常样本的基础上,采用主成分分析(Principal component analysis,PCA)法对特征空间进行降维处理,评估了包括偏最小二乘法回归(Partial least square regression,PLSR)、支持向量机回归(Support vector machine regression,SVR)和BP神经网络(Back propagation neural network,BPNN)等3种建模方法对土壤有机质含量的预测性能,选用决定系数R2、均方根误差(RMSE)和预测偏差比(RPD)评价各模型的预测性能。测试集验证结果表明,PLSR、SVR和BPNN这3种模型的预测值和样本的观测值之间的R2分别为0. 86、0. 91和0. 85,RMSE分别为2. 49、2. 05、2. 68 g/kg,RPD分别为2. 49、3. 02和2. 32。SVR模型的预测性能高于PLSR模型和BPNN模型,可对土壤有机质含量进行准确预测。     

白星花金龟成虫对10种寄主挥发物的嗅觉行为反应

【目的】筛选出对白星花金龟Potosia brevitarsis Lewis成虫具有引诱活性的挥发物。【方法】使用Y-型嗅觉仪测定了白星花金龟雌、雄成虫对10种寄主挥发物的嗅觉行为反应。【结果】白星花金龟对不同挥发物的嗅觉行为反应具有显著差异,且雌、雄成虫对同种挥发物的嗅觉行为反应存在差异。白星花金龟雌成虫对壬醛、芳樟醇、1-辛烯-3-醇及正己醇具有较强的正趋性;雄成虫则对芳樟醇、1-辛烯-3-醇、正己醇、反-2-己烯醇及正己醛呈现正趋性。【结论】芳樟醇、1-辛烯-3-醇及正己醇可以作为白星花金龟植物源引诱剂的组成部分。     

薇甘菊挥发物对薇甘菊颈盲蝽的引诱作用

从薇甘菊挥发性成分中选取15种含量较多的化合物,通过室内嗅觉测试和野外诱捕试验,验证这些化合物对薇甘菊颈盲蝽成虫行为的影响.室内嗅觉测试表明,当香叶烯含量为0.01%时,能够明显引起薇甘菊颈盲蝽的嗅觉反应,雄成虫和雌成虫的正趋向反应率分别为(63.34±4.15%)和(50.00±5.00%).野外诱捕试验结果表明,含量为0.01%的香叶稀作诱芯诱捕到的虫数为(16.33±4.04)头,显著多于其它试验组.室内嗅觉测试与诱捕试验都表明,存在于薇甘菊挥发物中的香叶烯对薇甘菊颈盲蝽具有显著的引诱作用.     

Characterization of putative steroid receptors in the membrane, cytosol and nuclear fractions from the olfactory tissue of brown and rainbow trout

Specific binding sites for testosterone have been detected in three compartments of olfactory tissue from brown and rainbow trout. Binding of³H-testosterone to the membrane fraction of olfactory tissue is of high affinity (K_d = 0.5–1.9 nM) and limited capacity (N_max = 30–60 fmol mg⁺¹ protein). Binding is reversible, and is eliminated by protease treatment. The membrane binding site exhibits a high degree of ligand specificity; 11β-hydroxytestosterone, 11-ketotestosterone, 17α-hydroxyprogesterone, 17α,20β-dihydroxy-4-pregnen-3-one, cortisol, and estradiol-17β all fail to displace testosterone at 20-fold excess while testosterone itself competes successfully. These attributes are consistent with the presence of specific steroid receptor proteins. Binding of testosterone within the cytosol is of moderate affinity (K_d = 9.0–23.0 nM) and high capacity (N_max = 0.5–2.9 pmol mg⁺¹ protein) and is more readily displaced by a number of steroid competitors than is the case for the membrane site. The rate of association and dissociation of testosterone from the cytosolic binding site is markedly more rapid than the equivalent processes in the membrane fraction. Binding of testosterone to the nuclear extract is of high affinity (K_d ∼3.0 nM) and limited capacity (N_max ∼50 fmol mg⁺¹ protein). There are no substantial differences between species or between sexes in the affinity or capacity of testosterone-binding sites in nuclear extract or membrane fraction. However, cytosolic testosterone-binding sites are three- to four-fold more abundant in rainbow trout than in brown trout, and female rainbow trout have more cytosolic binding sites than male rainbow trout, but a lower affinity for testosterone than male sites. Preliminary evidence supports the involvement of the membrane-associated testosterone-binding site in olfactory processes. Rainbow trout display an EOG response to testosterone at a concentration (≥ 10⁺⁹ M) which is consistent with the equilibrium dissociation constant (K_d) of the membrane-associated testosterone-binding site. Binding of³H-testosterone to the membrane-associated site shows a pH dependency which is comparable to the effects of pH on the EOG response to testosterone in intact fish. The attributes of the intracellular testosterone-binding sites are common to testosterone receptors in other fish tissues which are known androgen target tissues. This suggests that the development and/or function of salmonid olfactory tissue may be susceptible to influence by endogenous testosterone.     

Biotransformation enzyme activities in the olfactory organ of rainbow trout (Oncorhynchus mykiss). Immunocytochemical localization of cytochrome P4501A1 and its induction by β-naphthoflavone

Olfaction is a crucial function in most fish species, but little is known about biotransformation enzymes in the olfactory organ. This study demonstrates that biotransformation enzymes usually found in the rainbow trout liver, are present in the olfactory organ as well. While microsomal cytochrome P450 reductase, p-nitrophenol hydroxylase and cytosolic glutathioneS-transferase presented similar levels in both the olfactory organ and the liver, microsomal 7-ethoxyresorufinO-deethylase (EROD), 7-ethoxycoumarinO-deethylase, and 7-pentoxyresorufinO-deethylase were much lower in the olfactory organ (77-, 35-, 200-times respectively). Furthermore, microsomes from the olfactory organ were able to perform testosterone hydroxylation only in the 16α-position while testosterone was hydroxylated in the 16β-position by liver microsomes. Using polyclonal antibodies raised against perch cytochrome P4501A1, the immunoreactive protein was shown to be strongly expressed in various cellular types forming the nonsensory epithelium. Some immunostaining was also reported in the nonsensory cellular elements constituting the sensory epithelium, while olfactory receptor cells failed to show cytochrome P4501A1-immunoreactivity. Finally, the exposure of rainbow trout to waterborne β-naphthoflavone (0.1 μg ml⁻¹) for 2 or 4 days resulted in a higher induction of EROD activity in the olfactory organ compared to the liver. The presence of biotransformation enzymes in the olfactory organ of rainbow trout addresses the question of their involvement in the detoxication/toxication of pollutants as well as in the olfactory function.     

Olfactory esthesioneuroblastoma treated with orthovoltage radiotherapy in a dog

A 13-year-old neutered female mongrel dog presented with a 1-year history of stertorous respiration. On computed tomography examination, a mass was demonstrated in the nasal cavity. Open biopsy of the mass was performed and a diagnosis of olfactory esthesioneuroblastoma was made on histological examination. The dog was treated with orthovoltage x-ray radiation (total dose; 53 Gy given in 14 fractions over an 8 week period). Computed tomography after the twelfth irradiation revealed that tumour size had decreased. Although clinical signs were absent in the 4 months after irradiation, re-growth of the tumour was detected by radiographic evaluation and histological examination. The dog was again treated with orthovoltage x-ray radiation (total dose; 30 Gy given in three fractions over a 4-week period), however, tumour regrowth was again detected 3 months later. Clinical treatment of this tumour type has not been previously reported.     

棉铃虫嗅觉系统的结构与功能研究进展

棉铃虫Helicoverpa armigera是世界上重要的多食性农业害虫,主要依赖嗅觉寻找寄主、识别配偶以及选择产卵位点,以实现生存和繁衍。研究表明触角和下唇须是棉铃虫重要的外周嗅觉器官,其上分布毛形感器、锥形感器、腔锥形感器、栓锥形感器等重要的嗅觉感器,表达了包括气味结合蛋白、气味受体、离子型受体等上百种气味化学感受蛋白基因。脑内触角叶及与触角叶神经元连接的蕈形体冠、侧角、外侧前脑等为棉铃虫嗅觉中枢系统。通过利用电生理和染色标记技术明确了棉铃虫性信息素和二氧化碳感受相关的受体、嗅觉感受神经元和其他类型的触角叶神经元。这些关于棉铃虫外周和中枢嗅觉系统结构和功能的研究进展为进一步研究棉铃虫嗅觉器官感受寄主植物、有毒食物和天敌等气味分子的功能图谱以及研究不同嗅觉神经元在突触联系水平上对气味信息进行处理和编码的神经机制奠定了重要基础。也为深入研究棉铃虫的嗅觉行为调控机制和开发基于嗅觉行为调控的防治技术提供了重要理论基础。     

Chlorophyll meter predicts nitrogen status of tall fescue

The nitrogen (N) status of a crop can be used to predict yield and supplemental N fertilizer requirements, and rapid techniques for evaluating the N status of crops are needed. A study was conducted to determine the feasibility of using a hand held chlorophyll meter (SPAD 502, Minolta Co. Ltd., Japan) to monitor N status of tall fescue (Festuca arundinacea Schreb.). Four diverse tall fescue genotypes were grown at three locations in Alabama and fertilized at four N‐rates from 0 to 336 kg ha^‐1. A similar experiment was conducted in the greenhouse using soil from the same field sites. Chlorophyll meter readings (SPAD) were taken, and extractable chlorophyll content, tissue N concentration and dry matter yield were determined at harvest. SPAD, extractable chlorophyll content, tissue N concentration, and dry matter yield increased quadratically (0.67 < R² < 0.99) with increasing N fertilization in both experiments. All genotypes responded similarly to applied N, with some differences in magnitude. Relationships between SPAD meter readings and extractable chlorophyll and tissue N concentrations were linear with r² > 0.95. An additional independent variable, the square root of the inverse of SPAD, lowered the residual mean square by 11 and 16%, respectively, for tissue‐N and chlorophyll concentrations, but did not increase the R². This would be preferred for predictive purposes. Tissue N concentrations at higher N‐rates were sufficient for maximum yield which occurred at 290 and 248 kg N ha^‐1 for greenhouse and field, respectively, but were lower than previously reported sufficiency values. The chlorophyll meter is an easy and efficient method of detecting tall fescue N status.