Pyrethroid insecticides: esterase cleavage in relation to selective toxicity

The ester group of primary alcohol chrysanthemates is cleaved by mouse hepatic microsomal esterases, more rapidly for the (+)-trans than for the (+)-cis isomers. Substrate-specificity and inhibition studies in vivo establish that these pyrethroid-hydrolyzing esterases probably contribute to the low mammalian toxicity of bioresmethrin and other (+)-trans chrysanthemate insecticide chemicals derived from primary alcohols.     

Selenium and sulfur in a greenland ice sheet: relation to fossil fuel combustion

In the combustion of fossil fuels, selenium is mobilized in the atmosphere to a much lesser extent than is sulfur. This difference is ascribed to the chemical behavior of their respective tetravalent oxides. The ratio of selenium to sulfur in glacial ice is characteristic of terrestrial matter, and these elements may find their way to ice sheets by the formation of volatile compounds in biochemical processes.     

Neurons containing NADPH-diaphorase are selectively resistant to quinolinate toxicity

Exposure of cultures of cortical cells from mouse to either of the endogenous excitatory neurotoxins quinolinate or glutamate resulted in widespread neuronal destruction; but only in the cultures exposed to quinolinate, an N-methyl-D-aspartate agonist, was there a striking preservation of the subpopulation of neurons containing the enzyme nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d). Further investigation revealed that neurons containing NADPH-d were also resistant to the toxicity of N-methyl-D-aspartate itself but were selectively vulnerable to the toxicity of either kainate or quisqualate. Thus, neurons containing NADPH-d may have an unusual distribution of receptors for excitatory amino acids, with a relative lack of N-methyl-D-aspartate receptors and a relative preponderance of kainate or quisqualate receptors. Since selective sparing of neurons containing NADPH-d is a hallmark of Huntington's disease, the results support the hypothesis that the disease may be caused by excess exposure to quinolinate or some other endogenous N-methyl-D-aspartate agonist.     

维生素A、D、E添加水平对产蛋鸡健康和生产性能的影响

将240只海兰褐壳品种17周龄末育成鸡分成4组 (每组4个重复,各15只鸡)进行33周试验,研究了4个维生素A、D、E添加水平组合 (VA 4 000、6 000、8 000、10 000 IU/kg,VD 920、1 380、1 840、2 300 IU/kg,VE 6.4、9.6、12.8、16 IU/kg) 的效果。结果表明：各水平组的耗料量、产蛋量、料蛋比、破 (软) 蛋率、死淘率间差异均不显著(P>0.10);蛋壳品质均良好,其中2组的蛋壳强度显著大于其它组 (P<0.10);胫、趾骨矿化度正常,组间差异均不显著 (P>0.10);试验期间未出现维生素临床缺乏症状,50周龄末试鸡食道和泄殖腔上皮无典型缺乏VA病理变化。可看出水平1 (VA 4 000、VD 920、VE 6.4 IU/kg) 能满足需要,水平2 (VA 6 000、VD 1 380、VE 9.6 IU/kg) 比较理想;在不利条件下,采用水平3 (VA 8 000、VD 1 840、VE 12.8 IU/kg) 似乎更为适宜。     

双低优质油菜应用硒矿粉对富硒效果的影响

对中油杂2号、中双9号两个双低优质油菜品种施用3种不同含硒量的富硒矿粉,结果表明:①应用富硒矿粉能够提高双低优质油菜的植株含硒量,3种硒矿粉处理的油菜植株含硒量为0.1137～0.1352mg·kg-1,比对照增加0.0600～0.0815mg·kg-1,平均增128.68%;②高含硒量富硒矿粉的效果优于低含硒量的矿粉,但施用含量为1494mg·kg-1矿粉的油菜植株含硒量仅比含量为104mg·kg-1矿粉高18.91%,这说明较低含量的矿粉同样具有应用价值;③油菜不同时期的含硒量不同,苗期最少、后期较高,这说明硒元素在油菜中也存在着一个积累过程;④不同遗传基础油菜品种的聚硒效果不同,中油杂2号富硒效果优于中双9号,两者在苗期的差别较大,花期、成熟期的差别较小。     

富硒水溶肥对猕猴桃增硒及增产的效果

为探索硒肥对猕猴桃的增硒及增产效果,于2016年选用"康熙宝"富硒水溶肥在湘西自治州凤凰县"红心猕猴桃"品种上进行了叶面喷施试验。结果表明,喷施康熙宝富硒水溶肥(幼果期和壮果期2次喷施,每次用水溶肥100 m L对水100 kg/667m~2)的处理比对照(只喷等量清水和不喷硒肥及清水)平均增硒0.026 mg/kg,含糖量降低0.4~0.5个百分点,含酸量比对照下降0.03个百分点,糖酸比提高了0.8~1.0,可溶性固形物提高0.9%;平均增产6.8%~8.6%,增产效果达到极显著水平。经农业部检测,猕猴桃含硒量达到湖南省地方标准《富硒产品硒含量标准》。说明施用康熙宝富硒水溶肥对红心猕猴桃的增硒和增产效果显著,可大面积推广应用。     

作物施硒研究进展

硒是环境中的重要生命元素，对人畜的健康有重要影响，作物施硒可以提高食物链硒水平，改善作物品质，增强作物抗逆性和提高作物产量，但其有效性受硒形态，硒与其它元素间的相互作用，施硒方式及环境条件等多种因素影响，展望了今后硒应用的研究方向。     

不同高粱品种对硒的响应

为明确不同高粱品种富硒能力的差异,筛选富硒能力较强的优质高粱品种,以山西省主栽的7个高粱品种为材料,在田间试验条件下,在高粱开花期通过叶面喷施硒肥,研究不同施硒量对高粱籽粒产量和富硒能力的影响。结果表明,开花期叶面喷施外源硒能够显著提高各高粱品种籽粒硒含量,且随着喷施硒剂量的增大高粱籽粒硒含量增加;无论喷硒与否,各高粱品种籽粒硒含量均存在显著性差异,其中,不喷硒条件下,7个高粱品种中以晋糯3号、晋杂22号籽粒硒含量较高,分别为0.160,0.142 mg/kg;在摄入硒的安全范围内,开花期亚硒酸钠喷施剂量以80 mg/kg最适宜,品种中晋糯3号富硒效果最好,籽粒硒含量达0.296 mg/kg,晋杂22号次之,籽粒硒含量达0.277 mg/kg,晋糯3号和晋杂2号籽粒硒含量约为对照的2倍,均达到谷物富硒标准。高粱开花期叶面喷施亚硒酸钠对各品种产量及其构成因子影响不大。因此,建议在山西省的土壤和气候条件下,选择晋糯3号和晋杂22号进行富硒高粱的生产。     

Polychlorinated biphenyls: toxicity to certain phytoplankters

The growth rates of two species of marine diatoms were reduced by polychlorinated biphenyls (PCB's), widespread pollutants of the marine environment, at concentrations as low as 10 to 25 parts per billion. In contrast, a marine green alga and two species of freshwater algae were not inhibited at these or higher concentrations. The sensitivity of these species to PCB's paralleled their sensitivity to DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane].     

解硒菌9906-5B解硒率的响应面分析

筛选得到一种解硒菌9906-5B,利用含单质硒的煤矸石生产亚硒酸钠,以便有效防止化学法提取硒造成的环境污染。在培养基中加入单质硒,利用解硒菌9906-5B,根据单因素结果设计它的响应面试验。运用SAS软件对解硒因素参数进行统计分析,探讨单因素条件下9906-5B的解硒效果。结果表明,解硒菌9906-5B在pH 6.0温度30℃解硒菌发酵28 h条件下,解硒率达到79.10%。     

Metacontrast: its relation to evoked potentials

Electrophysiological correlates of metacontrast were studied by means of averaged evoked potentials recorded from the scalp in man. Under conditions in which the brightness of the first of two successive stimuli appears diminished there is no accompanying attenuation of the evoked potentials to that stimulus. The results suggest that the amplitude and latency of evoked potentials correlate with stimulus intensity but not with brightness.     

Speech: relation of nonfluency to information value

In spontaneous speech and oral reading of stutterers, likelihood of nonfluency occurring on any word is not related to the amount of information carried by that word. The same is true for spontaneous speech of normal speakers. Previous contrary findings can be accounted for by the relationship between information value and word length.     

不同水平甜菜碱和蛋氨酸对肉鸡生产性能的影响

研究了肉鸡日粮中含不同水平甜菜碱和蛋氨酸组合对肉鸡采食量、增重和胴体性状的影响。试验选用AA肉仔鸡504只,采用单因子试验设计,随机分为7组,每组72只,试验4次重复。分别饲喂对照日粮、不同蛋氨酸和甜菜碱水平组合处理日粮。试验结果未发现甜菜碱对蛋氨酸有替代作用,但不加蛋氨酸或仅加0．05％的甜菜碱导致单位增重的耗料量增高。甜菜碱对蛋氨酸的替代作用可能会受到饲养条件、日粮背景和动物对象等因素影响。     

土壤不同硒含量对小麦主要产量相关性状和硒吸收利用的影响

为探究不同土壤硒含量对小麦主要产量相关性状和硒吸收利用的影响,以‘普冰151’‘西农黑大穗’‘周黑麦1号’为试验材料,紫阳高硒矿粉为硒源,采用盆栽试验,设置5种不同土壤硒含量,S0(0添加硒矿粉),S1、S2、S3、S4(土壤硒含量分别为4 mg·kg~(-1)、8 mg·kg~(-1)、12 mg·kg~(-1)和16 mg·kg~(-1))。结果表明:土壤中施加高硒矿粉对小麦分蘖数和穗长无显著影响;但在土壤硒含量S2和S3水平下‘西农黑大穗’的株高显著提高。土壤硒含量增加可显著提高小麦穗粒数、千粒质量和产量。随土壤硒含量的增加,小麦旗叶叶绿素含量与净光合速率较S0均显著增加,呈先升高后降低的趋势。土壤中施加高硒矿粉显著提高小麦籽粒粗蛋白含量,S2、S3和S4水平之间无显著差异,但显著高于S1水平。在土壤硒含量S1和S2水平下,3个小麦材料籽粒有机硒含量均达到富硒小麦标准(GB13105-1991),S2水平为最适宜种植富硒小麦的土壤硒含量。3个小麦材料的籽粒有机硒含量在S2水平下分别为0.258mg·kg~(-1)、0.288 mg·kg~(-1)和0.273mg·kg~(-1),籽粒硒转化率分别为82.958%、84.457%和82.979%,‘西农黑大穗’在3个材料中表现最高。表明土壤中施加一定量硒能有效提高小麦产量、籽粒粗蛋白含量和硒含量。     

Obesity: evidence of decreased secretion of glucagon

The increase in concentration of glucagon in plasma caused by infusion of alanine was reduced in obese subjects as compared to that in nonobese control subjects. This was true when the subjects were in the postabsorptive state as well as after an 84-hour fast, at which time the basal glucagon concentration had risen in the nonobese subjects, but remained unaltered in the obese group.     

Catastrophic volcanic collapse: relation to hydrothermal processes

Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.     

Moonquakes: mechanisms and relation to tidal stresses

Observed features of moonquakes are combined with theoretical calculations of the tidal stresses to interpret the moonquake mechanisms. Tidal stresses, together with a postulated ambient tectonic stress, are sufficient to explain the depth, periodicity, and polarity reversal of moonquakes. Both of these stresses are small (on the order of 1 bar) and consistent with the small magnitudes of moonquakes.     

Copper: relation to penicillamine-induced defect in collagen

When rats were depleted of copper by administration of a copperdeficient diet, no abnormalities developed in dermal collagen. In contrast, marked changes were produced by penicillamine although the degree of copperdeficiency induced by the drug was less. Large additions of copper to the diet failed to prevent the penicillamine-induced collagen defect when the drug was given parenterally. The effect of penicillamine on soft-tissue collagen appears to be unrelated to its copper-chelating properties.     

硒钴配施对番茄产量、番茄红素及硒、钴含量的影响

采用盆栽试验研究了硒钴配施对番茄产量、番茄红素、番茄果实中硒、钴含量以及土壤中有效硒、钴含量的影响,结果表明,单施硒对番茄产量无明显影响;单一施钴处理时,番茄产量随施钴量的增加而增加;Co2(16 mg/kg)与Se2(0.6 mg/kg)或Se3(3 mg/kg)配施可显著提高番茄的产量,与对照相比,分别提高了14.1%和15.9%。单一施硒和单一施钴以及硒钴配施条件下均可提高番茄中番茄红素的含量。单一施硒和硒钴配施均可明显地提高番茄中硒和土壤中有效硒的含量。单一施钴以及硒钴配施可明显提高番茄中和土壤中有效钴的含量。     

Optomotor responses to monocular stimulation: relation to visual system organization

Results of tests on 4 mammalian, 19 reptilian, and 17 avian species confirmed the prediction that lack of optomotor response to monocular optokinetic stimulation in one of the two horizontal directions would correlate with afoveate retinal organization, whereas consistent optomotor responses to monocular stimulation in either horizontal direction would correlate with foveate organization.