Treatment of the early life stages of scallop (Pecten maximus) with antimicrobial agents; searching for an alternative to chloramphenicol

High mortality rates are often observed in rearing the early stages of the great scallop, Pecten maximus. The addition of antibacterial agents has been necessary to improve larval survival. However, as one antibacterial agent, chloramphenicol, is banned in Norway and Europe the aim of this study is to investigate alternative antibacterial agents. The therapeutic agents investigated in this study were florfenicol, oxytetracycline, oxolinic acid, neomycin and Pyceze. The mean minimum inhibitory concentration (MIC) values were determined for oxytetracycline, oxolinic acid and Pyceze against bacteria isolated from scallop larvae. Two types of treatment regime were investigated on an intermediate scale (20 L). One regime involved continuous exposure of scallop larvae to the therapeutic agent while the other involved a short exposure lasting two hours. All intermediate scale treatments were performed in parallel to large-scale production (800 L) treatment with chloramphenicol. Of the therapeutants investigated, oxolinic acid was the most effective, although only at high concentrations. The short exposure of two hours was ineffective for all therapeutics.     

D-对羟基苯海因细菌的发酵工艺优化研究

通过筛菌得到一株野生菌 LLV-6,在诱导剂诱导后利用DL-对羟基苯海因（DL-HPH）为底物经D-海因酶（HYD）和N-氨甲酰-D-氨基酸酰胺水解酶（CAB）两酶水解而获得D-对羟基苯甘氨酸。用LB培养基（含磷酸盐缓冲溶液,pH=7.2）接菌量为0.5%（对数期的菌种）,在37℃、200r、pH7.2条件下培养菌种。在培养12h后加入2%的诱导剂并以500μLDMSO作为促溶剂,33h后收集细胞。通过对细胞酶活力的测定,此时酶活力达到最大值,酶活力为0.57U/L,比优化前提高了2.6倍。     

多效唑,缩节胺在秋番茄育苗上的应用

秋番茄育苗,于３片真叶施用５０～１００ｍｇ／Ｌ多效唑液或２５－５０ｍｇ／Ｌ缩节胺液,对防止幼苗徒长,培育壮苗有显著作用;增产效果极显著。     

Analysis of Drought Characteristics and Its Trend Change in Shaanxi Province Based on SPEI and MI

【Objective】 At present, most drought studies were based on historical drought events to analyze the causes and trends. This paper sought to simulate the drought index method when outputting future meteorological data based on CMIP5 model, and explored the characteristics of past and future drought changes in Shaanxi Province, which could provide a basis for the future management of agricultural water resources in Shaanxi Province. 【Method】Based on the historical data of 18 meteorological stations in Shaanxi Province and CMIP5 model, the future meteorological data were output. The reference crop evapotranspiration (ET₀) was simulated by comparing three kinds of models. The standard precipitation evaporation index (SPEI) and relative moisture index (MI) were calculated based on the reference crop ET₀ and precipitation data to reflect the drought degree. The spatial and temporal characteristics of drought in the past (1958-2017) and in the future (2018-2100) were compared.【Result】Multiple linear regression (MLR) simulation could accurately predict the reference crop ET₀ (RMSE=0.457 mm·d ^-1). In the RCP2.6 and RCP8.5 scenarios, the future drought index showed an upward trend. Under the RCP8.5 scenario, there was a sudden change in the drought index in the 1940s. The degree of drought would decrease in the future of Shaanxi Province, and the distribution of drought would be more uneven during the year. In the future, the degree of drought would decrease during summer maize growth season, and the degree of drought would increase during winter wheat growth season.【Conclusion】The characteristics and extent of drought change were different under different RCP scenarios. The changes in drought characteristics reflected by SPEI and MI were basically the same, but there were differences in the changes in some time periods. In order to effectively cope with the negative impact of climate change on dry crop yields, it was necessary to enhance soil water storage and conservation capacity, especially to strengthen drought resistance during the winter wheat growing season.     

Short-term compatibility of furosemide with crystalloid solutions

Parenteral veterinary furosemide is a 50-mg/mL solution with a pH of 8.0-9.3. The purpose of this study was to determine whether a commonly used veterinary formulation of 50 mg/mL of furosemide solution could be diluted in vitro without precipitation. Furosemide 50 mg/mL was diluted to concentrations of 10 and 5 mg/mL with 5% dextrose in water (D5W), 0.9% saline, lactated Ringer solution (LRS), and sterile water. Acidic sterile water and basic sterile water solutions were made by the addition of hydrochloric acid and sodium hydroxide, respectively, for use as controls to assess the effect of pH extremes for each concentration. After furosemide dilution, the final pH of each sample was measured, and samples were grossly and microscopically examined for clarity and crystal formation immediately and 1, 3, 5, and 8 hours after dilution. Gross precipitation and microscopic crystals were immediately observed in the acidic controls. Solutions of 5 mg/mL in LRS and 0.9% saline became slightly cloudy immediately, but no crystals were observed microscopically for 8 hours. Solutions of 10 mg/mL in D5W, 0.9% saline, LRS, and sterile water and solutions of 5 mg/mL in D5W and sterile water and the basic control were grossly clear, and no microscopic crystals were observed for 8 hours. On the basis of the results obtained in this in vitro investigation, this veterinary formulation of furosemide 50 mg/mL can be diluted without precipitation to a concentration of 10 mg/mL with D5W, 0.9% saline, LRS, or sterile water and to 5 mg/mL with D5W or sterile water and held for 8 hours.     

用分光光度计预测小球藻藻液浓度的研究

[目的]为实现小球藻大面积推广生产和产业化发展提供科学、翔实的技术参数。[方法]通过721型分光光度计,对不同浓度的小球藻藻液在不同波段光照下的透光度进行测定,确定测定小球藻的最佳照射波段,得到最佳照射波段时小球藻藻液的浓度。[结果]在不同光照对不同浓度小球藻藻液透射的吸光度进行归一化处理后,得出小球藻的最佳透射波段为670 nm。同时,得出670 nm光照下吸光度与小球藻浓度的回归方程为:y=-1.479 7+0.987x,相关系数为0.991,说明相关性较好。推导了当量浓度(C)与透光度(I)的公式,C=-ln(I/I0)/(LK),式中L为光径长度(比色皿宽度),K为小球藻细胞的平均截面面积。[结论]用分光光度计间接测量小球藻的浓度是可行的。     

环丙沙星对实验性猪支原体性肺炎的药效学研究

测定环丙沙星及对照药物对猪肺炎支原体的最小抑菌浓度，其中环丙沙星的抗支原体活性最强，最小抑菌浓度为0．01μg/ml。通过给18头健康猪气管内接种含有猪肺炎支原体的病肺悬液，复制具有典型症状的猪支原体性肺炎疾病模型，并进行环丙沙星2．5、5．0mg/kg肌注给药对实验性猪支原体性肺炎的疗效实验及血浆药物浓度监测，两组治愈率分别为83．3％（5／6）和100％（6／6）。治疗组多剂量给药期间，第1、3、5、7、9次给药后0．5及6h的血浆药物浓度，在2．5mg/kg剂量组平均为0．41μg/ml和0．17μg/ml,5.0mg/kg剂量组平均为0．71μg/ml和0．28μg/ml。两剂量组环丙沙星均无蓄积作用。     

几种化学物质和温度处理对高羊茅种子发芽的影响

用高羊茅(Festuca arundinacea)种子为试验材料,置入光照培养箱培养,研究化学物质和温度处理对其发芽的影响.结果表明:0.2%的次氯酸钠(NaClO)处理促进高羊茅种子的发芽,浓度梯度设置在0.5%～1.5%时均抑制其发芽,且浓度与发芽率和发芽势均成负相关.不同浓度的硝酸钾(KNO3)处理均促进其发芽,且浓度为2.0%时,发芽率最高,发芽势是先降低后升高.高羊茅最适播种温度为20℃,高于或低于20℃,对种子的发芽均有不同程度的抑制作用.     

CO_2浓度、氮素和水分对春小麦碳素固定的影响

试验设350μmolmol-1和700μmolmol-12种CO2浓度水平,湿润、干旱2种水分处理和施N0、50、100、150和200mgkg-15个水平。结果表明,CO2浓度增加,春小麦地上部碳固定量和碳固定总量均增加,但与氮肥施用水平有关。在中氮和高氮时,CO2浓度增高,地上部碳固定量和碳固定总量明显增加,而不施氮肥和低氮时,增加则不明显。不同水分处理地上部碳固定量和碳固定总量也没有明显差别,这表明,CO2浓度升高对氮素和水分胁迫及对春小麦碳固定并没有补偿作用。     

锰对公鸡乳酸脱氢酶活性和精子密度的影响

本文就日粮锰对公鸡乳酸脱氢酶(LDH)活性及生殖功能的影响进行了研究。结果表明日粮中锰缺乏或过多引起血清、肝脏和睾丸 LDH 活性同步下降。精子数/睾丸Ⅰ组(添加 Mn 0ppm)、Ⅳ组(添加 Mn 300ppm)比Ⅲ组(添加 Mn100ppm)分别降低了35.06%和31.55%,表明精子生成过程对锰的需要量有一定的范围。睾丸 LDH 活性和精子数/睾丸之间 r=0.6791(P<0.05),提示锰缺乏或过多造成睾丸生精功能下降的重要原因之一是由于锰影响了睾丸 LDH 活性。