Influence of storage and mixing factors on the biological activity of silver thiosulfate

Silver thiosulfate (STS) complex stability and degradation during formulation and storage were monitored indirectly by determining the effectiveness of treatment solutions in retarding flower petal abscission in geraniums (Pelargonium hortorum Baily). Freshly prepared solutions composed of Ag⁺:S₂O₃^2? ratios from 1:1 to 1:16 at constant silver concentration were all equally effective. There were no differences in effectiveness when a Ag⁺:S₂O₃^2? solution of ratio 1:4 was formulated at 5, 25 or 50°C, when prepared at pH 4.01, 7.0 or 10.0, or when prepared in the presence of 10 mM KCl, Na₂CO₃, Ca(NO₃)₂ or MgSO₄. The ability of solutions to retard abscission was reduced when Ag⁺ was substantially in excess of S₂O₃^2?. Rapid mixing of AgNO₃ and Na₂S₂O₃ solutions yielded effective solutions, independent of mixing order. Complete loss of activity was observed when solutions were stored in contact with either tin or galvanized metal for 5 days, whereas there was no loss in activity after 3 months' storage in plastic or glass at 2°C. These results indicate that currently recommended formulation procedures are unnecessarily stringent, and that long-term cold storage of prepared STS solutions is feasible.     

Cytologic diagnosis of Lawsonia intracellularis proliferative ileitis in a Japanese snow macaque (Macaca fuscata)

Diffuse ileal thickening and ileocecocolic lymphadenomegaly were observed during exploratory laparotomy in a 2-year-old male Japanese snow macaque (Macaca fuscata) that had flu-like signs and diarrhea. Cytologic examination of ileal biopsy imprints revealed many mature, mildly karyolytic neutrophils and fewer well-differentiated lymphocytes, eosinophils, macrophages, and plasma cells in a background containing amorphous, necrotic material. Tightly cohesive sheets of moderately pleomorphic epithelial cells also were seen. The cytologic diagnosis was chronic, active, mixed inflammation with atypical epithelial cells and necrosis. Histologically, the mucosal and crypt epithelium was moderately hyperplastic with a loss of goblet cells, increased mitoses, and frequent crypt abscesses. Within the lamina propria and extending into the submucosa was a marked neutrophilic infiltrate, with low numbers of lymphocytes, histiocytes, plasma cells, and eosinophils. The histologic diagnosis was chronic, diffuse, marked suppurative and lymphocytic ileitis. Warthin-Starry silver staining of the ileal biopsy and imprint specimens demonstrated numerous pleomorphic, curved bacilli consistent with Lawsonia intracellularis. Polymerase chain reaction (PCR) and immunohistochemistry confirmed the identity of the infectious agent. L intracellularis infection may be underdiagnosed because silver stain is required to visualize the organism with light microscopy and because the pathognomonic crypt hyperplasia may be complicated by secondary pathologic changes. Application of silver stain to cytologic specimens should be considered when distal intestinal lesions associated with hyperplastic epithelium, with or without inflammation, hemorrhage, or necrosis, are identified in animals with clinical signs of enteritis, especially in frequently affected species or in stressed or young animals.     

Effects of exposing freesia corms to ethylene or to smoke on dormancy-breaking and flowering

Ethylene (C₂H₄), applied at an early stage of the high-temperature treatment for dormancy breaking, promoted sprouting. Five μl l^?1 of C₂H₄, applied during 2 days, replaced 2 weeks of high temperatures. The promotive effect of C₂H₄ diminished with increasing exposure period and no difference was found between the effects of 5 and 50 μl l^?1. The promotive effect of exposing corms to smoke was slightly lower than that of C₂H₄. Neither had an adverse effect on flowering and both resulted in shorter leaf length and rigid growth, which could be useful for solving the problems of leafiness during winter.     

Involvement of nitric oxide generation in hypersensitive cell death induced by elicitin in tobacco cell suspension culture

Recent studies suggest that nitric oxide (NO), an important signaling and defense molecule in mammals, plays a key role in activating disease resistance in plants. We characterized NO production by tobacco Bright Yellow-2 cells pharmacologically after treatment with INF1, the major elicitin secreted by the late blight pathogen Phytophthora infestans, prepared from Escherichia coli. NO production rapidly occurred within 1h and reached a maximum level 3–6h after the addition of INF1. Carboxy-PTIO, a NO-specific scavenger, abolished INF1-induced NO production in a dose-dependent manner. Pretreatment of protein synthesis inhibitor cycloheximide and protein kinase inhibitor K252a blocked NO production 3–12h after INF1 treatment, indicating that NO production requires de novo protein synthesis and protein phosphorylation. In an investigation of the relations between NO generation and several defense responses induced by INF1, carboxy-PTIO completely suppressed activation of a 41-kDa protein kinase and cell death by INF1. Carboxy-PTIO also suppressed the induction of hypersensitive-related (hsr) genes HSR515 and HSR203J, the expression of which is strongly correlated with the hypersensitive response in plants. The results suggest that NO plays a crucial role in the induction of hypersensitive cell death.     

Influence of temperature on toxicity of propylene oxide at low pressure against<Emphasis Type="Italic">Tribolium castaneum</Emphasis>

Toxicity of propylene oxide (PPO) at low pressure against the most common stored-product insect,Tribolium castaneum (Herbst), over a short exposure time, was tested at three different temperatures (16°, 22° and 30°C). Toxicities of PPO at 100 mm Hg were strongly influenced by ambient temperature. LD₅₀ and LD₉₉ toxicities ranged from 4.7 to 28.9 mgl ⁻¹ and from 10.5 to 72.6 mgl ⁻¹ respectively, showing that susceptibility was positively correlated to the temperature. The LD₉₉ values for all life stages (except the larval stage) were significantly lower at 30° than those at 16° and 22°C. However, the LD₉₉ values for all life stages (except the pupal stage) at 16° were not significantly different from those at 22°C. A concentration × time (Ct) product of 291, 171 and 98 mg h/l was required to obtain complete mortality (99%) ofT. castaneum at 16°, 22° and 30°C, respectively. Thus, the efficacy of PPO at 100 mm Hg to all life stages ofT. castaneum also decreased as the temperature decreased from 30° to 16°C. http://www.phytoparasitica.org posting Sept. 28, 2004.     

Effects of nitrous oxide on IOP and pupillary diameter in dogs anesthetized with varying concentrations of desflurane

Objective The aim of the present study was to evaluate the effects of nitrous oxide on IOP and pupillary diameter (PD) of dogs anesthetized with varying desflurane concentrations. Animals studied Twenty adult Mongrel dogs were used. Methods They were anesthetized with propofol (10 mg/kg, IV) and maintained with varying concentrations of desflurane (1.6, 1.4, and 1.2 MAC) diluted in 100% oxygen (G1) or in 70% nitrous oxide and 30% oxygen (G2) (30 mL/kg/min). IOP was measured by applanation tonometry and horizontal PD was taken with a caliper adjacent to the cornea. Mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), and end‐tidal CO₂ (etCO₂) were also measured. All parameters were measured at T0, T30, T45, and T60 time points. One‐way repeated measures anova and the t‐test were used to assess statistical differences (P < 0.05). Results T30, T45, and T60 IOP measures were within normal limits for both groups and IOP did not differ between groups at any time. There was a significant decrease in PD in G1 between T0 and T30, T45 and T60, and also between T30 and T60. PD did not differ between groups. All vital parameters were within normal limits throughout anesthesia. Conclusions Administration of nitrous oxide with desflurane results in maintenance of normal IOP and prevents a decrease in horizontal PD during anesthesia. Therefore, this may be a suitable protocol in dogs undergoing intraocular surgeries that require mydriasis and maintenance of normal IOP.     

氢氧化锌制备饲料级氧化锌的新工艺研究

采用锌粉法保险粉的副产氢氧化锌为主要原料,和碳酸氢铵一步法合成碱式碳酸锌,850℃热分解碱式碳酸锌制得饲料级氧化锌。通过正交试验,考察了合成碱式碳酸锌的各种影响因素,得出最优工艺条件为:碳酸氢铵与氢氧化锌的摩尔比0.5,反应时间4h,反应温度30℃。同时还对制备的饲料级氧化锌样品与普通产品的性能进行了对比测试。试验结果表明,试验样品能提高饲料级氧化锌的分散性和比表面积,减小堆积密度,产品有助于改善预混合饲料的混合均匀度,在饲料工业上具有实际应用意义。     

NO 介导的 Ca2＋信号在干旱胁迫下紫花苜蓿种子萌发及抗氧化酶中的传导作用研究

本试验以紫花苜蓿种子为试验材料,添加外源一氧化氮供体硝普钠(SNP)、CaCl_2及抑制剂亚甲基蓝(methylene blue,MB)和LaCl_3,对种子进行浸种处理,以研究NO介导的Ca~(2+)信号在干旱胁迫下紫花苜蓿种子萌发及抗氧化酶中的传导作用。结果表明,15%PEG胁迫下紫花苜蓿种子萌发受到明显抑制,当外源添加NO或Ca~(2+)处理后萌发指标均有上升,外施0.1mmol/L SNP或10mmol/L CaCl_2都能有效缓解PEG对紫花苜蓿种子的胁迫伤害。干旱胁迫下NO+Ca~(2+)共处理时效果最为显著,萌发率较SNP处理提高了8.96%,较CaCl_2处理提高了19.67%。共处理时比SNP、CaCl_2处理时提高了种子淀粉酶活性、淀粉含量、可溶性糖、可溶性蛋白及脯氨酸含量,降低了MDA含量和超氧阴离子产生速率,显著提高了SOD,POD,CAT活性。其中淀粉酶活性、淀粉含量、可溶性蛋白、可溶性糖、脯氨酸含量以及POD活性的变化中,均表现出:NO和Ca~(2+)共处理下各指标变化要慢于单一处理。当添加外源NO的同时添加Ca~(2+)通道抑制剂La~(3+),NO的促进效果受到抑制,而添加外源Ca~(2+)的同时添加NO抑制剂亚甲基蓝,Ca~(2+)的促进效果受到抑制,表明NO经由Ca~(2+)信号通路调控干旱胁迫下紫花苜蓿的信号传导。     

不同料水比的湿拌料对育成期银狐采食量、营养物质消化率、氮代谢及体重的影响

本试验旨在探讨不同料水比的湿拌料对育成期银狐采食量、营养物质消化率、氮代谢及体重的影响。试验选用平均体重为(3.44±0.19)kg的12周龄左右的健康银狐30只,随机分为3个组,每组10只,公母各占1/2。3组银狐分别饲喂料水比为1.0∶2.5(Ⅰ组)、1.0∶3.5(Ⅱ组)和1.0∶4.5(Ⅲ组)的湿拌料,试验期48 d。结果表明:1)随着湿拌料添加水分比例的升高,各周龄银狐的干物质平均日采食量均有不同程度的增加,其中Ⅲ组银狐干物质平均日采食量在14、15、17、18、19周龄时极显著高于Ⅰ组和Ⅱ组(P0.01),在16周龄时显著高于Ⅰ组(P0.05);Ⅲ组干物质总采食量极显著高于Ⅰ组和Ⅱ组(P0.01),且Ⅱ组也有高于Ⅰ组的趋势,但差异不显著(P0.05)。2)Ⅰ组干物质消化率显著高于Ⅲ组(P0.05);蛋白质消化率各组间差异不显著(P0.05),但Ⅰ组较Ⅱ组升高4.62%,Ⅱ组较Ⅲ组升高5.42%;脂肪消化率各组间差异不显著(P0.05),但Ⅰ组较Ⅲ组升高4.03%,Ⅱ组较Ⅲ组升高4.46%。3)食入氮表现为Ⅲ组极显著高于Ⅰ组和Ⅱ组(P0.01),Ⅱ组也有高于Ⅰ组的趋势,但差异不显著(P0.05);尿液量随着湿拌料添加水分比例的升高显著或极显著升高(P0.05或P0.01);氮沉积各组间差异不显著(P0.05);粪氮排出量表现为Ⅲ组显著高于Ⅰ组和Ⅱ组(P0.05),Ⅱ组高于Ⅰ组,但差异不显著(P0.05);随着湿拌料添加水分比例的升高,尿氮排出量有升高的趋势,而净蛋白质利用率有降低的趋势,但各组间差异不显著(P0.05);Ⅰ组蛋白质生物学价值显著高于Ⅱ组和Ⅲ组(P0.05)。4)不同料水比的湿拌料对银狐不同周龄平均体重、各阶段平均日增重、总增重均无显著影响(P0.05);对于料重比,Ⅱ组较Ⅲ组降低4.30%,Ⅰ组较Ⅱ组降低1.21%,但各组间差异不显著(P0.05)。综合各项指标,从降低环境污染和饲料成本以及保证银狐体增重的角度出发,育成期银狐湿拌料中料水比以1.0∶2.5为宜。     

Effects of dietary crude protein and tannic acid on nitrogen excretion,urinary nitrogenous composition and urine nitrous oxide emissions in beef cattle

Two consecutive trials were carried out to study the effects of dietary crude protein (CP) and tannic acid (TA) on nitrogen (N) metabolism of beef cattle and consequently, the N₂O emissions from the urine of cattle. In Trial I, eight growing castrated cattle were used as the experimental animals. Two levels of dietary CP (110.6 and 135.7 g/kg dry matter [DM]) and two levels of TA (0 and 16.9 g/kg DM) were allocated in a replicated 2 × 2 crossover design. In Trial II, the N₂O emissions from the urine of cattle collected from Trial I were determined using the static incubation technique. An interaction between dietary CP and TA on the urinary N excretion (p < .05) was found but not on the N₂O‐N emission of cattle urine. Increasing dietary CP level from 110.6 g/kg DM to 135.7 g/kg DM increased the total N excretion (p < .001), the N retention (p < .05) and the ratio of urinary urea‐N/urinary N (p < .01), did not affect the N use efficiency (NUE; p > .05) and shifted the N excretion from faeces to urine. Increasing the dietary CP level increased the N₂O‐N emission of cattle urine. Dietary addition of TA decreased the urinary excretions of urea (p < .001) and shifted the N excretion from urine to faeces, did not affect the NUE of beef cattle (p > .10), and decreased the N₂O‐N emission of cattle urine. Pyrogallol and resorcinol of the TA metabolites were detected in urine with dietary addition of TA. Feeding beef cattle with relatively low CP level and adding TA in rations are effective approaches to mitigate the N₂O‐N emissions from cattle urine.