外源溶解性有机质对兽药土霉素在黄壤中吸附-解吸行为的影响

为了探讨外源溶解性有机质对兽药土霉素在黄壤中吸附-解吸行为的影响,采用批量平衡方法,研究了不同浓度的外源溶解性有机质对黄壤中土霉素吸附与解吸的影响及机制。结果表明,线性模型、Freundlich模型和Langmuir模型均可较好地拟合不同浓度外源溶解性有机质对含有土霉素的黄壤的吸附与解吸曲线,决定系数(R2)为0.946 8~0.999 8;无论添加哪种外源溶解性有机物质,黄壤对土霉素的吸附量均随液相中土霉素浓度的升高而增加,并且不存在解吸迟滞行为。     

HPLC法测定中兽药散剂中非法添加土霉素的方法研究

建立了高效液相色谱法检测清肺散、白头翁散、止痢散等中兽药散剂中非法添加土霉素的方法。用十八烷基硅烷键合硅胶色谱柱,以0.05 mol/L草酸铵溶液-二甲基甲酰胺-0.2 mol/L磷酸氢二铵（75∶20∶5）（用氨试液调pH值至8.0±0.2）为流动相,检测波长280 nm,流速1.0mL/min,进样量20μL,柱温35℃。结果显示,土霉素的线性范围为100～300μg/mL,线性方程为Y=4.90×10 X-2.39×103（,r=0.999 6,n=5）,本方法的回收率为80.68%～119.23%,RSD为0.66%～1.85%。结果表明,本方法准确、可靠,适用于中兽药散剂中非法添加土霉素的检测。     

磷和土霉素对小麦和紫花苜蓿幼苗生长和根系发育的影响

采用盆栽试验的方法,研究不同磷添加量(0,20,80 mg/kg)和土霉素添加量(0,40,160 mg/kg)对小麦和紫花苜蓿幼苗生物量及根系发育的影响。结果表明:所有水平土霉素处理中,20,80 mg/kg磷处理的小麦地上部生物量均比不加磷时高,分别高22.7%～34.1%,10.0%～30.0%和9.1%～18.3%。除160 mg/kg土霉素加80 mg/kg磷的处理外,所有处理的苜蓿根生物量均小于不加磷和土霉素的对照。小麦的根长和根表面积随着土霉素添加量的增加总体上呈减少的趋势。总体来看,施磷显著促进了小麦幼苗地上部的生长,但对苜蓿幼苗生长的影响不显著。土霉素对苜蓿幼苗的根系发育有抑制作用。研究结果可为评价土壤中土霉素残留对作物早期生长的影响和指导合理施用磷肥提供理论依据。     

Levels of Vitellogenin in Male Japanese Medaka (Oryzias latipes) Exposed to the Chemotherapeutics: Oxytetracycline,Romet-30®, and Copper Sulfate

ABSTRACT

Japanese medaka (Oryzias latipes) were exposed to oxytetracycline and Romet-30^® at daily doses via feed of 0.06 mg, 0.11 mg, and 0.28 mg per gram body weight for 11 days, and at daily doses of 0.05 mg, 0.10 mg, and 0.15 mg per gram body weight for 5 days, respectively. In addition, fish were exposed to copper sulfate in their aquaria water at 1.85 mg/L for 1 h each day (over a span of 1 day, 7 consecutive days, or 1 day in every 3 to 5 days for a total of seven doses). Vitellogenin levels were measured in fish using a sandwich enzyme-linked immunosorbent assay (ELISA). Vitellogenin levels were not induced from exposure to either oxytetracycline or Romet-30® (P > 0.05); however, copper sulfate for 1 h on 1 day showed a decrease in vitellogenin from the control fish and other treatment groups (P = 0.007). Under these test conditions, oxytetracycline, Romet-30, and copper sulfate were not found to act in medaka as estrogenic compounds by inducing vitellogenin.     

兽药土霉素对水稻幼苗根系及部分生理特性的影响

为了解抗生素对农作物生长的作用机理,选择中国养殖业中普遍使用的土霉素,采用水培试验研究了不同污染水平土霉素对苗期水稻根系生长、根系活力、叶片叶绿素含量和氧化酶活性等的影响。结果表明,土霉素污染对水稻地下部分的影响明显大于地上部分。低浓度（0.5和1 mg·L-1）的土霉素处理能促进水稻根系总长度和根表面积的增加,增强根系活力;但高浓度的土霉素（>5 mg·L-1）可显著降低水稻根系生物量,对根系活力、叶片叶绿素含量和氧化酶活性有明显的限制作用,增加根系相对质膜透性。研究认为,高浓度土霉素可对水稻幼苗产生毒害作用,限制水稻幼苗正常生长。     

土壤中兽用抗生素污染对水稻生长的影响

为了解农田土壤兽用抗生素污染对粮食作物水稻生长的潜在影响,选择我国养殖业中常用的抗生素之一土霉素作为目标化合物,试验研究了不同土霉素浓度水平对水稻苗期、生长期生长与产量的影响,探讨了水稻各器官中土霉素积累与土壤中土霉素浓度水平的关系。结果表明,土壤土霉素污染对水稻生长的影响主要发生在苗期,对地下部分的影响显著大于地上部分;苗期地下部生物量、根系活力、叶片叶绿素含量和氧化酶活性随浓度水平(30 mg·kg~(-1)以上)的升高而显著降低。苗期受到土霉素污染影响的水稻其影响一直可延续至整个生育期,表现在分蘖数降低、产量减少等。土霉素在水稻各器官中的积累量大小顺序:根系叶片茎秆籽粒。水稻对土壤中的土霉素富集能力较小,土霉素由根部向地上部分叶、茎、籽粒的迁移作用也较弱。考虑到当前农田土壤中土霉素污染水平一般较低(多在10 mg·kg~(-1)以下),且在谷物中土霉素积累水平较低,推断在目前农地土壤中土霉素污染水平下,其对水稻生长的直接危害相对较小。     

Bath efficacy of sodium hypochlorite,oxytetracycline dihydrate and chloramphenicol against bacterial black disease in fairy shrimp Branchinella thailandensis

To control black disease infecting fairy shrimp Branchinella thailandensis, the effects of concentrations and exposure time to three effective antimicrobials, which inhibited the pathogens in vitro, were evaluated. Exposure to sodium hypochlorite (NaOCl) caused a great toxicological response in the shrimp, 100% mortality was observed within 30 min–2 h at 5–20 μg mL^?1. For oxytetracycline dihydrate (OTC) and chloramphenicol (CP), short‐term exposure to four high concentrations up to 5 h and long‐term exposure (12 days) to four low concentrations were used to determine an appropriate method for bath efficacy. Long‐term exposure to low concentrations was more toxic than the short‐term. Short‐term exposure to OTC showed the highest survival rate and CP was considered more toxic. The minimum survival rate of the shrimp exposed to both antibiotics at 250 μg mL^?1 for 3 h was 83.3%. For determination of the bath efficacy, a short–term exposure (3 h) to OTC and CP was conducted using artificially infected shrimp. Administration of OTC and CP at 250 and 500 μg mL^?1 resulted in the highest survival rates of 56.7% and 46.7% respectively. This study demonstrated that bath administration with OTC could be an alternative method for the treatment of black disease in fairy shrimp cultivation.     

Oxytetracycline depletion and withdrawal time estimation following intraperitoneal administration in three species from Chilean salmon farming

This study was conducted to evaluate the half‐time (T½) and withdrawal time (WT) of oxytetracycline (OTC) following intraperitoneal (i.p.) administration of OTC (24.8–34.7 mg/kg) in three farmed salmonid species, Coho salmon (Oncorhynchus kisutch), Rainbow trout (Oncorhynchus mikiss) and Atlantic salmon (Salmo salar). A detection technique in fish skin muscle through a high‐performance liquid chromatography (HPLC) with a diode array detector (DAD) was developed and validated. The depletion studies were carried out in controlled conditions (nine studies) and under field conditions (one study). The T½ and WT estimations from the skin muscle after the i.p. administration of OTC in salmonids appear to be longer than studies where the OTC was orally administrated. Furthermore, the OTC maximum concentration in muscle seems to be also higher in the i.p. treatment. Due to the prolonged WT following the i.p. OTC administration, cautions related to the salmon harvest time should be consider in order to prevent OTC traces in the final product.     

The in vitro efficacy of oxytetracycline against re‐isolated pathogenic Aeromonas hydrophila carrying the cytolytic enterotoxin gene through hybrid catfish,Clarias macrocephalus (Günther, 1864) × Clarias gariepinus (Burchell, 1822) in Thailand

Aeromonas hydrophila is a pathogen infecting farmed hybrid catfish, Clarias macrocephalus (Günther, 1864) × Clarias gariepinus (Burchell, 1822) which incurs substantial economic losses in Thailand. The study aimed at a genetic tracking of A. hydrophila infection and the in vitro assessment of the efficacy of antibiotics against its virulent strains. Five clinical strains from catfishes and Nile tilapia were employed. They were 3‐passage re‐isolated through healthy hybrid catfish and the cytolytic enterotoxin gene (AHCYTOEN) of individuals was traced. Each of the re‐isolates at a dose of ~6.67 × 10⁵ CFU/g was intraperitoneally injected into ~15 g‐healthy hybrid catfish and their pathogenicity were observed for 7 days. It was found that AHCYTOEN was carried over whereas typical signs of motile aeromonas septicaemia were found in the specimens. The bacterial strains of Nile tilapia origin did not induce mortality but those of catfish origins (80%–100% rate of mortality). The strains were susceptible to the tetracycline antibiotics, and oxytetracycline produced MIC₅₀ and MBC as low as 0.007–0.031 μg/ml and 1–8 μg/ml respectively. As oxytetracycline specifically inhibited pathogenic A. hydrophila in vitro, it is recommended that an appropriate dosage regimen of the drug should be established.     

土霉素对猪粪污染土壤微生物数量和酶活性的影响研究

研究外源土霉素对受不同养殖污染程度的土壤生物学性质的影响,结果表明:添加土霉素可降低土壤微生物数量,降低比例由低至高依次为:猪粪堆放处土壤、长期施用猪粪农田土壤、不施用畜禽粪农田土壤;添加土霉素对土壤脲酶和中性磷酸酶活性的抑制程度为:不施用畜禽粪农田土壤>长期施用猪粪农田土壤>猪粪堆放处土壤,影响大小随受畜禽养殖污染程度增加而减小。长期受养殖污染的土壤具有较高的土霉素抗性微生物水平,可能与养殖污染促进了土壤环境中抗生素抗性物质形成有关。