南水北调中线工程水源区和受水区的降水时空变化特征及丰枯遭遇

[目的]基于1950—2022年时间序列ERA5再分析降水数据,探究南水北调中线工程水源区和受水区降水量时空变化特征,旨在保障跨流域调水的可行性和持续性,为南水北调中线工程水资源调度和运行管理提供科学参考。[方法]采用Mann-Kendall检验、小波分析、云模型以及Copula函数等方法,分析水源区和受水区降水变化趋势以及丰枯遭遇特征。[结果](1)1950—2022年南水北调工程水源区和受水区分别按照年降水量34.75和39.35 mm/(10 a)幅度减少,水源区年降水量存在43 a的主周期,受水区年降水量存在55 a的主周期。(2)云模型隶属云图夏季降水量分布不均且离散程度较高,而冬季分布均匀且较集中。(3)调水不利的组合汛期和非汛期遭遇频率分别为23.15%和25.92%。[结论]水源区和受水区年降水量均呈现明显减少趋势,水源区丰枯交替变化显著;南北丰枯异步概率大于丰枯同步,同枯频率不高,有利于调水工程的安全性和可靠性。研究结果可为制定南水北调中线工程相关政策和技术指导提供理论依据,有助于工程的规划和管理,提高水资源利用效率和可持续性。     

Establishing a zebrafish transgenic line expressing tilapia lysozyme with enhanced antibacterial activity

In recent years, infectious disease caused by Streptococcus agalactiae has increased in aquaculture, threatening the healthy development of tilapia and resulting in substantial economic losses. Cultivating disease‐resistant tilapia by transgenic technology is one strategy that has been developed to address this issue. Here, we used a transposon system to investigate gene expression and tissue lytic activity in transgenic zebrafish expressing the tilapia lysozyme. The transpose vector contained the Tgf2 transposon skeleton, tilapia heat shock protein 70 promoter (Hsp70) and two target genes (tilapia C‐type lysozyme 3 [lysozyme‐C3] and green fluorescent protein [GFP]). The transgenic zebrafish F₀ generation was obtained by microinjecting the donor vector and transposase mRNA into fertilized zebrafish eggs. There was 45% green fluorescence in the zebrafish F₀ generation, which was spread over the entire body based on microscope observation. The F₀ generation was reared to sexual maturity, at which point individuals were mated with wild‐type zebrafish to produce the F₁ generation. Tilapia lysozyme‐C3 expression was detected in the liver of F₁ generation by RT‐PCR and western blotting, but was not detected in the skin, intestine, or muscle. Significantly higher liver bacteriolysis activity was detected in transgenic zebrafish compared with wild‐type zebrafish. Therefore, transgenic zebrafish may have an increased potential for bacterial resistance.     

Effects of intensive mariculture on the sediment environment as revealed by phytoplankton pigments in a semi‐enclosed bay,South China Sea

Phytoplankton pigment concentrations in the surface sediments of a fish and oyster farm in Dapeng Cove, South China Sea, were measured monthly to investigate the effects of mariculture on the environment from December 2011 to December 2012. The highest contents of the identified phytopigments, sulphides and total organic carbon in the surface sediments were all found at the fish farm, followed by the oyster farm; the lowest contents were detected at the control site. Fucoxanthin in the surface sediments was the most abundant carotenoid and was significantly correlated with chlorophyll a (Chl a; r = 0.922, P < 0.01). This finding suggested that the deposited diatoms could be the main source of the Chl a concentration. Besides a differential sedimentation of phytoplankton (i.e. higher downflux at fish and oyster site than that at control site), we assume that the extent of pigment diminution from the fish site to control site was also controlled by the chemical conditions of the surface sediments. The fish farm provided the most optimum preservation conditions for the phytopigments and was a good sink for phytodetritus among the three sites because of its anoxic and reductive characteristics. Phytoplankton pigments could be useful biomarkers to evaluate the influence of mariculture on sediment environment.     

铜胁迫对滇水金凤花部发育及生理生化特性的影响

为了解滇水金凤花器官对铜(Cu)的反应,以其幼苗为材料,采用1/2 Hoagland营养液水培法进行试验,测定不同浓度铜胁迫下花部形态、相对含水量、抗氧化酶活性、膜渗透性和金属含量相关指标参数.结果表明:随铜浓度增加,各花部器官逐渐变小,相对含水量不断下降,与对照差异显著;Na+和Fe3+呈先降低后增加趋势;MDA含量...     

轻、中和重稀土元素对球等鞭金藻的促生长作用

轻、中和重稀土元素对球等鞭金藻的生长有相同程度的促进作用,但其有益浓度范围不同,镧为７．２８～８７．４０μｍｏｌ／Ｌ,钆为６．３６～５７．２３μｍｏｌ／Ｌ,镱为５．７８～１７．３４μｍｏｌ／Ｌ。这３种稀土元素对球等鞭金藻的最佳浓度分别为：３６．４２～６５．５５,１９．０８～５７．２３和５．７８～１７．３４μｍｏｌ／Ｌ。可分别提高单胞藻数量２１．８％～２４．３％,１０．４％～１７．２％和１７．９％～２３．０％;叶绿素含量较对照组分别提高了２９．３％～４１．２％,２５．６％～３８．１％和３６．５％～４０．３％。     

禽源空肠弯曲杆菌耐药性与致病性研究

为了解不同环节禽源空肠弯曲杆菌携带状况及其耐药性与致病性,从肉鸡养殖环节和屠宰环节采集600份样品并分离到241株空肠弯曲杆菌,采用微量肉汤稀释法和PCR方法对分离菌株进行耐药性和毒力基因检测.结果显示:分离菌株对环丙沙星、萘啶酸、四环素的耐药情况尤为严重,耐药率分别为97.75％、96.78％、95.18％;养殖环节...     

黄海北部沿岸水域营养水平及有机污染状况分析

主要根据１９９７的６月和８月对黄海北部沿岸对虾增殖放流调查,从营养水平和有机污染的角度,分析了黄海北部沿岸水域营养水平及有机污染状况。结果表明,营养盐含量具有明显的季节变化,并呈沿岸河口水域高于其他水域分布趋势。６月的营养盐含量水平接海水一类标准,富营养化程度和有机污染不明显,基本属正常水平。而８月的营养盐含量大部分测站均有不同程度地超过海水一,二类标准值,由计算的富营养化判断值,和有机污染指数,     

饲用酶制剂在水产养殖中的应用

饲用酶能提高饲料转化率,促进动物的生长,降低粪便污染和动物的死亡率,综合提高动物的生产性能,在动物饲料中应用越来越普遍,被认为是一种无残留、无污染、无公害的环保型添加剂。1　饲用酶制剂的作用机制目前,在水生动物饲料中应用的酶制剂主要包括:纤维素酶、β-葡聚糖酶、木聚糖酶、淀粉酶、蛋白酶和植酸酶等。饲料中添加外源性酶制剂的目的主要是提高动物对营养物质的消化率和分解饲料中的抗营养因子,从而促进动物的生长。幼年的水生动物,自身消化系统发育得不完善,内源消化酶分泌不足,在饲料中添加外源性消化酶,可以促进水生动物对…     

菊酯类农药对水田生物影响研究进展

拟除虫菊酯类农药是一个重要的杀虫剂类别,对有害昆虫具有良好的触杀作用.但是,在中国一直被禁止应用于水田害虫防治.本文综述了菊酯类农药对各种水田生物的急性和慢性作用机制、影响因子,提出拟除虫菊酯类农药能否在水田应用需要进行深入系统的研究论证.     

Formulation of a rational dosage regimen of ceftiofur hydrochloride oily suspension by pharmacokinetic-pharmacodynamic (PK-PD) model for treatment of swine Streptococcus suis infection

BackgroundOur previously prepared ceftiofur (CEF) hydrochloride oily suspension shows potential wide applications for controlling swine Streptococcus suis infections, while the irrational dose has not been formulated.ObjectivesThe rational dose regimens of CEF oily suspension against S. suis were systematically studied using a pharmacokinetic-pharmacodynamic model method.MethodsThe healthy and infected pigs were intramuscularly administered CEF hydrochloride oily suspension at a single dose of 5 mg/kg, and then the plasma and pulmonary epithelial lining fluid (PELF) were collected at different times. The minimum inhibitory concentration (MIC), minimal bactericidal concentration, mutant prevention concentration (MPC), post-antibiotic effect (PAE), and time-killing curves were determined. Subsequently, the area under the curve by the MIC (AUC_0–24h/MIC) values of desfuroylceftiofur (DFC) in the PELF was obtained by integrating in vivo pharmacokinetic data of the infected pigs and ex vivo pharmacodynamic data using the sigmoid E_max (Hill) equation. The dose was calculated based on the AUC_0–24h/MIC values for bacteriostatic action, bactericidal action, and bacterial elimination.ResultsThe peak concentration, the area under the concentration-time curve, and the time to peak for PELF''s DFC were 24.76 ± 0.92 µg/mL, 811.99 ± 54.70 μg·h/mL, and 8.00 h in healthy pigs, and 33.04 ± 0.99 µg/mL, 735.85 ± 26.20 μg·h/mL, and 8.00 h in infected pigs, respectively. The MIC of PELF''s DFC against S. suis strain was 0.25 µg/mL. There was strong concentration-dependent activity as determined by MPC, PAE, and the time-killing curves. The AUC_0–24h/MIC values of PELF''s DFC for bacteriostatic activity, bactericidal activity, and virtual eradication of bacteria were 6.54 h, 9.69 h, and 11.49 h, respectively. Thus, a dosage regimen of 1.94 mg/kg every 72 h could be sufficient to reach bactericidal activity.ConclusionsA rational dosage regimen was recommended, and it could assist in increasing the treatment effectiveness of CEF hydrochloride oily suspension against S. Suis infections.