Antioxidant effect of dietary tocopherol and ascorbic acid on growth and survival of Litopenaeus vannamei postlarvae

The nutritional effect of vitamin E in dietsfor Litopenaeus vannamei postlarve (PL19)was investigated. Four formulated diets withdifferent combinations of -tocopherylacetate (-TA), ascorbic acid (AA) andhighly unsaturated fatty acids (HUFA) weretested, using four replicates.No significant differences in survival wereobserved among treatments after 34 days offeeding. However, shrimp fed with a dietcontaining 2% fish oil (low n-3 HUFA content),200 mg.kg^–1 -TA and100 mg.kg^–1 AA (diet H/E/C) showedsignificantly better growth than those fed adiet supplemented with 5% fish oil (high n-3HUFA content), 200 mg.kg^–1 -TA and100 mg.kg^–1 AA (diet H+/E/C). Shrimp fedwith a diet containing 5% fish oil,900 mg.kg^–1 -TA and100 mg.kg^–1 AA (diet H+/E+/C) showed a significantly higher tissue level of n-6 PUFAthan postlarvae fed diet H+/E/C. No definiteconclusion could be drawn about a possibleinteraction between -TA and AA, since acomparison of the diet containing 5% fish oil,200 mg.kg^–1 -TA and700 mg.kg^–1 AA (H+/E+/C+) and the dietH+/E/C did not show any significant differencesin any of the measured parameters. Theantioxidative status of the shrimp tissue(measured by means of the thiobarbituric acid(TBA) assay and expressed as nM malonaldehyde(MA) per gramme dry weight) was equal for alltreatments. Nevertheless, there was a slightlylower MA value with the diet H+/E/C+,indicating that AA may be an effectiveantioxidant in the aqueous phase and at thewater/lipid interface of the tissue. The tissuelevels of -T and AA were highlydependent on the amounts in diets and nocorrelation between -T and AAincorporation could be observed.     

Synthesis and regulation of 17α-hydroxy-20β-dihydroprogesterone in immature males of Oncorhynchus mykiss

Three experimental approaches were chosen to study the question if the progestin 17-hydroxy-20-dihydroprogesterone (1720OHP) is synthesised in testes of young Oncorhynchus mykiss, in which the absence of spermatozoa was verified histologically: first, in order to detect 20-hydroxysteroid dehydrogenase activity (20HSD), testes homogenates were incubated with ³H-labeled 17OHP.Metabolites were analysed by TLC, HPLC, and repeated crystallization to constant isotope ratios. One of the metabolites was identified as 1720OHP-³H, indicating that already immature testes contain 20HSD activity and are able to produce 20-reduced steroids. Second, 1720OHP was quantified by radioimmunoassay in incubates of testes fragments. The sensitivity of the gonads to gonadotropin II (GtH II) became evident when comparing incubations in the absence and presence of GtH II. Third, plasma levels of 1720OHP were significantly higher in animals injected with partially purified salmon gonadotropin, compared to controls. Thus, for the first time, it could be shown that 20HSD is present in testicular cells other than spermatozoa. Furthermore, 1720OHP is indeed secreted at a very early stage of testicular development; 1720OHP secretion is also responsive to GtH II. Future studies will have to show if the functions of this progestin include the stimulation of spermatogenesis.     

Catalytic activity and immunochemical quantification of hepatic cytochrome P-450 in β-naphthoflavone and isosafrol treated rainbow trout (Oncorhynchus mykiss)

In addition to catalytical assays, immunochemical techniques have recently been employed to measure induction of the cytochrome P-450 (P450) monooxygenase system in fish with polyaromatic hydrocarbons (PAH). In the present study, polyclonal antibodies were raised against rainbow trout P450IA1. Levels of rainbow trout P450IA1 determined using protein blotting- and ELISA procedures were compared with levels of 7-ethoxyresorufin-O-deethylase (7-EROD) activity in liver microsomes from rainbow trout. These comparisons showed that values of P450A1 were positively correlated (r=0.99 and r=0.97) with 7-EROD activities. In addition, the effects of isosafrol (ISF) or -naphthoflavone (NF) treatments on P450 levels in rainbow trout liver were investigated using immunochemical and catalytical methods. ISF treatment induced 7-EROD activity as well as 7-methoxycoumarin-O-demethylase-, 7-ethoxycoumarin-O-deethylase-, 7-propoxy-coumarin-O-depropylase and 7-butoxycoumarin-O-debutylase activities, although to a lesser extent, compared with the NF treatment. In contrast, immunochemical quantification of rainbow trout P450IA1 protein revealed a slightly different pattern. ISF appeared to be a weak inducer of P450IA1 in rainbow trout compared with NF. In addition, the degree of inhibition of 7-alkoxycoumarin-O-dealkylase activities in ISF microsomes differed from that measured in control- and NF microsomes. The discrepancies between catalytic and immunochemical estimates of rainbow trout P450IA1 in ISF treated fish in addition to differencs between specific inhibitory pattern by specific polyclonal antibodies raised against rainbow trout P450IA1, indicate that important differences exists between the responses induced by NF- and ISF treatments in the rainbow trout liver.Part of this work was presented at the 6th International Conference on Biochemistry and Biophysics of Cytochrome P-450, Vienna, Austria, July 3–8, 1988.     

风送式喷雾机喷筒结构优化数值模拟与试验

采用动参考系模型,将可动风机的转速作为仿真的初始值,分段划分喷筒内计算区域中的网格,利用数值及正交试验的方法,对风送式喷雾机的喷筒结构进行了优化设计,仿真计算喷筒出口处的风速。为验证模型的正确性,在对应风机转速下,实测了喷筒出口各采样点的风速,并将实测值与仿真结果进行了覆盖率统计及χ2检验。结果表明:影响喷筒压力损失及喷筒出口风速的因素依次为:出风口直径、柱形喷筒长度、锥形喷筒长度;在喷筒出口采样点上,仿真计算出的风速区间覆盖实测风速的概率为95%;χ2检验表明在水平0.05下,喷筒出风口风速的仿真值均服从其实际测量值的分布;因此,利用动参考系方法,以风机转速为初始条件,对喷筒出风口速度的数值模拟是可信的。     

一株链霉菌发酵液对小菜蛾的杀虫作用研究

为了合理开发和利用链霉菌发酵液,通过测定链霉菌菌株HNll8发酵液对小菜蛾卵和不同龄期幼虫的杀虫活性,研究其杀虫作用。结果表明：链霉菌菌株HNlt8发酵液对小菜蛾卵无作用,对2龄和3龄小菜蛾幼虫防效较好,校正死亡率平均值达到70％以上,可以确定该菌株具有一定的杀虫活性。     

Decomposition of Alder,Ash, and Poplar Litter in a Mediterranean Riverine Area

Abstract

Litter decomposition dynamics of three Mediterranean riverine species [Alnus glutinosa (L.) Gaertn, Fraxinus angustifolia Vahl., and Populus x hybrida] was studied in a 2‐year experiment in the province of Guadalajara (Spain) using the litterbag technique. Decay rates of the litter were estimated by fitting a single exponential model to the litter decomposition data. At the end of the experiment (after 485 days), the remaining litter necromass varied in the following order: Populus x hybrida>Alnus glutinosa>Fraxinus angustifolia. Litter of the three species was fast degraded; ash litter was almost totally degraded at the end of the experiment. Alder had the highest concentrations of total nitrogen and ammonium in litter, and its pattern of degradation and release to the system was different to the other two litters. This could influence the soil nutrient contents in each system as was indicated by the soil nutrient values.     

Salinity effects on annual bedding plants in a peat‐perlite medium and solution culture

Annual vinca (Catharanthus roseus (L.) G. Don ‘Pink Carpet'), geranium (Pelargonium x hortorum L. H. Bailey ‘Jackpot'), and marigold (Tagetes erecta L. ‘First Lady') were grown in a sphagnum peat moss and perlite medium. Plants were irrigated with solutions of different salinity by the addition of 0.0, 1.0, 2.0, 4.0, and 8.0 g/1 of a NaCl and CaCl₂ mixture resulting in solution electrical conductivity (EC) values of about 1.3, 3.0, 4.5, 7.9, and 13.9 ds/m, respectively. In another experiment marigold and geranium were grown in solution culture containing the same salt mixture at 0.0, 1.0, 4.0, and 8.0 g/1 with EC values of 1.4, 3.0, 7.4, and 12.5 ds/m, respectively. All species showed some salinity tolerance up to 2.0 g/1 in peat‐perlite and 1.0 g/1 in solution culture as growth reductions were below 10% and no foliar injury occurred. Foliar injury occurred on marigold and geranium, but not annual vinca, at 4.0 and 8.0 g/1 in both growing media. On a concentration basis, recently mature leaves sampled from marigold grown in peat‐perlite contained more chloride (Cl) but less sodium (Na) than geranium and annual vinca. However results of the solution culture experiment showed that, with the exception of 1.0 g/1 treatment, geranium and marigold plants absorbed the same amount of Cl and Na when content was expressed on a mg/g dry weight basis. The low Na concentration in marigold leaves was a reflection of restricted translocation of Na from the roots to the shoots.     

刺葡萄愈伤组织UFGT基因克隆及表达分析

为从细胞水平上揭示刺葡萄3-O-类黄酮葡萄糖基转移酶(UFGT)基因调控花青素合成的功能,以刺葡萄愈伤组织为试验材料,根据刺葡萄愈伤组织转录组UFGT序列片段,利用RT-PCR结合RACE技术克隆得到VdUFGT基因,并对其进行生物信息学和表达特性分析。结果表明,VdUFGT基因cDNA和DNA开放阅读框(ORF)分别为1 371 bp和1 448 bp,包含2个外显子和1个内含子,编码456个氨基酸,为带负电荷的不稳定的亲水性蛋白,具有一个UDPGT结构域,是UDPGT超家族成员,包含UDP-黄酮糖基转移酶特征区域。由UFGT同源基因编码蛋白所构建的系统发育树,与植物进化的关系相一致,6个葡萄属植物聚为一支。RT-qPCR分析表明,刺葡萄红色愈伤组织VdUFGT转录水平极显著高于白色愈伤组织,培养25 d的2个细胞培养物差异可达79倍;在刺葡萄愈伤组织连续培养过程中,红色愈伤组织中VdUFGT转录水平变化幅度较大,在愈伤组织快速生长中期和衰老初期分别出现峰值,而刺葡萄白色愈伤组织VdUFGT转录水平与红色愈伤组织相比变化幅度不大,且始终维持在一个较低的水平。说明VdUFGT对刺葡萄红色愈伤组织细胞培养物中的花青素生物合成有重要的调控作用,这种调控作用主要发生在刺葡萄愈伤组织细胞快速生长中期和细胞衰老初期。本研究结果为进一步阐明VdUFGT调控刺葡萄细胞花青素合成的机制奠定了理论基础。     

钾对刺葡萄光合作用的影响

以刺葡萄为材料,设不同施钾量(0、135、270、540 g/株)研究其光合作用。结果表明:当施钾量为270 g/株时,各时期刺葡萄叶片的净光合速率均较高,着色期时达最大,为8.91μmol/(m~2·s);当施钾量为540 g/株时,各时期刺葡萄叶片的气孔导度均较高;当施钾量为270 g/株时,刺葡萄叶片的蒸腾速率在膨大期较高,为5.33mmol/(m~2·s);当施钾量为270 g/株时,除开花期之外,各时期刺葡萄叶片的胞间CO2浓度均处于较低水平;钾与净光合速率、蒸腾速率、气孔导度呈极显著正相关关系;在不同时期刺葡萄叶片的光合日变化均呈双峰曲线,在10:00和16:00时出现峰值,10:00时,膨大期、着色期和落叶期均以施钾量540 g/株时的净光合速率最大,分别为6.05、7.63和4.75μmol/(m~2·s),施钾量为270 g/株时的净光合速率次之,而开花期和成熟期分别以施钾量135、270 g/株时的净光合速率最大,分别为5.31和5.61μmol/(m~2·s);16:00时,除开花期以施钾量540 g/株时的净光合速率最大之外,其他时期均以施钾量270 g/株时净光合速率达最大值,分别为4.26、3.61、2.87、2.30μmol/(m~2·s)。综合本研究结果,施钾量为270 g/株时较有利于刺葡萄光合作用。     

外源激素对杂交兰组培快繁的效应

[目的]探讨杂交兰（Cymbidium hybridum×faberi）组培快繁技术,为杂交兰的工厂化生产提供技术支撑.[方法]以杂交兰茎尖和腋芽为外植体,调查不同激素与活性炭（AC）组合对原球茎诱导、增殖分化和生根培养的影响.[结果]6-BA是影响原球茎诱导的主要因素,IBA是影响原球茎增殖和分化的主要因素.原球茎诱导和增殖最适培养基为MS＋6-BA 1.0 mg/L＋IBA 0.5 mg/L＋AC 3.0 g/L＋3％蔗糖;MS＋6-BA 0.5 mg/L＋IBA 0.5 mg/L＋AC 3.0 g/L＋3％蔗糖最适于原球茎分化成苗;壮苗生根培养基为1/2MS＋ IBA 0.5 mg/L＋AC 1.0 g/L＋3％蔗糖＋0.5％琼脂.[结论]在MS基本培养基中,低量的6-BA、IBA对杂交兰原球茎诱导、增殖与分化、生根和移栽成活均有明显促进效应,原球茎不同生长阶段对AC的需求量不同.