牛磺酸对幼刺参生长、抗氧化和代谢酶活性的影响

【目的】研究饲料牛磺酸添加水平对刺参(Apostichopus japonicus)生长、体组成、抗氧化能力以及消化代谢的影响,以探究幼刺参的牛磺酸合成能力及对牛磺酸的需求量。【方法】选用初始体质量为(11.40±0.04)g的刺参为研究对象,在基础饲料中分别添加0(对照)、0.30%、0.60%、0.90%、1.20%和1.50%的包被牛磺酸以及0.60%半胱氨酸和0.60%磺基丙氨酸(均以质量分数计,下同),形成8组等氮等脂的实验饲料,在养殖桶(400 L)内进行喂养实验。每种饲料投喂3桶幼参(每桶30头),日投喂1次,实验周期56 d,测定刺参生长性能、抗氧化、代谢酶活性指标。【结果】添加0.30%~1.50%的牛磺酸显著提高了幼参末质量、增重率和特定生长率(P<0.05),而添加0.60%~1.50%的牛磺酸显著提高了刺参的粪便产生率(P<0.05)。与对照组相比,饲料中添加0.60%~1.20%牛磺酸显著提高了全参粗蛋白含量,添加1.20%和1.50%牛磺酸显著提高全参灰分含量(P<0.05)。随饲料中牛磺酸添加量的梯度升高,全参苏氨酸、缬氨酸、蛋氨酸以及半胱氨酸等氨基酸含量呈现上升趋势而组氨酸含量则呈现下降趋势,亮氨酸则呈现先上升后降低的趋势,添加量0.90%时平均值最高,显著高于对照组(P<0.05)。与对照组相比,添加0.60%~1.50%牛磺酸显著提高体壁和呼吸树中牛磺酸含量,添加0.30%~1.50%牛磺酸显著提高肠道牛磺酸(P<0.05)。磺基丙氨酸添加组肠道牛磺酸含量显著高于对照组,但是显著低于1.20%~1.50%牛磺酸添加组(P<0.05)。随饲料中牛磺酸添加量升高,刺参肠道脂肪酶、淀粉酶和丙酮酸激酶等活性呈先升高后下降趋势,且均在0.90%牛磺酸添加组达到最大值;所有牛磺酸添加组刺参肠道的葡萄糖激酶、碱性磷酸酶等酶活性均高于对照组(P<0.05)。半胱亚磺酸脱羧酶和半胱氨酸双加氧酶活性呈逐渐下降的趋势,且饲料中添加0.60%~1.50%牛磺酸显著降低了肠道半胱亚磺酸脱羧酶活性(P<0.05)。肠道过氧化氢酶和超氧化物歧化酶活性随牛磺酸添加量的增加均呈先升高后下降的趋势,分别在0.90%和1.20%牛磺酸添加量时达到最大值,肠道丙二醛含量变化则呈现相反趋势,0.90%~1.50%牛磺酸添加组刺参肠道丙二醛含量显著低于对照组(P<0.05)。【结论】以特定生长率、粪便产生率、呼吸树和肠道牛磺酸蓄积水平为评价指标经折线回归分析,并结合消化酶、抗氧化能力等指标,推导出刺参幼参对饲料中牛磺酸的最适需求量为0.47%~0.51%。

Photosynthetic response of floating Ulva prolifera to diurnal changes of in-situ environments on the sea surface

During yellow sea green tide outbreak, the thalli of Ulva prolifera drifted more than 350 km on the sea surface from off shore of Jiangsu Province to Qingdao city, where they were exposed to complex changes of local environments. The purpose of this study is to investigate the response of the thalli to diurnal changes of environments on the sea surface, and a sea surface environment simulator (SSES) was designed to simulate the natural environment of floating U . prolifera mat. A control experiment is designed in the laboratory, which was processed under suitable conditions (20°C for temperature, 72 μmol photons/(m 2 ·s) for light intensity and 30 for salinity), and an in-situ research was conducted to study the photosynthetic responses of floating U . prolifera to diurnal changes of environments. The results show that the photosynthetic efficiency of the thalli decreased gradually with time, and decreased rapidly after 14:00 local time (LT). After exposed to the environment on the sea surface for 6 h, the photosynthetic activity of the thalli decreased significantly. Furthermore, physiological-level and molecular-level experiments revealed that non-photochemical quenching (NPQ), cyclic electron flow (CEF) and energy redistribution between PSI and PSII all played an important role in the strong photosynthetic plasticity of U . prolifera . NPQ is the most important photoprotective responses to environmental changes before 12:00 LT. The results also confirmed that the CEF and energy redistribution between PSI and PSII are the main synergistic eff ects for the thalli to adapt to the environmental changes when the process NPQ cannot work. And the result can further reveal the reason why U . prolifera can adapt to the living condition of long distance drift on the sea surface. The findings of this research could provide a theoretical basis for explaining outbreaks of the green tide and instructing the management of the problem.

光照强度和营养盐对海带幼苗释放溶解有机碳的影响

为了探究光照与营养盐对海带(Saccharina japonica)幼苗释放溶解有机碳(DOC)的影响,测定了不同光强[0、83、165和250μmol photons/(m^(2)·s)]和不同营养条件下(氮加富、磷加富、氮磷加富和自然海水)海带幼苗DOC的释放速率。结果显示,自然海水条件下,海带幼苗DOC释放速率与光照呈正相关性(P<0.05),光照250μmol photons/(m^(2)·s)时达到最高,为(24.31±5.84)μmol/(g·h),约为黑暗条件的4倍左右。单一氮加富、磷加富对海带幼苗释放DOC无显著影响,其释放速率分别为(23.04±4.23)和(18.18±4.59)μmol/(g·h)。氮磷共同加富显著提升了海带幼苗DOC释放速率,其释放速率为(37.15±6.77)μmol/(g·h),约为自然海水条件下的3倍。海带幼苗释放DOC很可能同时受“溢出”与“扩散”两种调节机制影响。在寡营养条件下,“溢出”机制占主导,表现为与光照正相关,释放物质相对分子量较高;在富营养条件下,“扩散”机制占主导,表现为受氮、磷营养盐整体水平调节,释放物质相对分子量较低。

中国海水农业发展现状及前景

海水灌溉农业正在世界范围内兴起,给土地与淡水资源奇缺的滨海滩涂与盐碱地区的农业生产和生态修复带来了希望,必将引领第三次农业革命。海水农业生态效益和经济效益突出,不但节约淡水和土地资源,而且种植盐生作物还能持续松化土壤板结,实现“上菜下渔”式滩涂生态系统的良性循环。通过分析国内外海水农业的发展现状,包括海洋渔业和海水灌溉农业,指出现阶段中国在这一领域发展中存在起步晚、技术水平不高以及近海海域、滩涂环境受到破坏等问题。未来中国在海水农业方面的技术水平会不断提高、发展模式将更加成熟,而海水农业必将成为中国建设海洋强国的重要支撑。基于此,提出了适于中国滩涂和盐碱地区的多营养层次综合种养模式(IMTPA)。

Effects of elevated pCO2 on physiological performance of marine microalgae Dunaliella salina (Chlorophyta, Chlorophyceae)

The present study was conducted to determine the ef fects of elevated pCO_2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga D unaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO_2 levels(390 μatm, p HN BS : 8.10), predicted year 2100 CO_2 levels(1 000 μatm, p HN BS : 7.78) and predicted year 2300 CO_2 levels(2 000 μatm, p H NBS : 7.49). Elevated pCO_2 significantly enhanced photosynthesis(in terms of gross photosynthetic O_2 evolution, ef fective quantum yield(ΔF/F' m), photosynthetic efficiency( α), maximum relative electron transport rate(r ETRm ax) and ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco) activity) and dark respiration of D. salina, but had insignificant effects on growth. The photosynthetic O_2 evolution of D. salina was significantly inhibited by the inhibitors acetazolamide(AZ), ethoxyzolamide(EZ) and 4,4'-diisothiocyanostilbene-2,2′-disulfonate(DIDS), indicating that D. salina is capable of acquiring HCO ˉ 3 via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO_2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO_2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be af fected by the increased pCO_2/low p H conditions predicted for the future, but that the responses of D. salina to high pCO_2/low p H might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive eff ects of pCO_2, temperature, light and nutrients on marine microalgae.

黄河三角洲白蜡雌雄株叶际微生物群落结构分析

目的:探究白蜡雌雄株叶际微生物组成结构特征。方法:采用高通量测序技术,分析白蜡雌雄株叶际微生物的组成,比较雌雄叶际微生物的共性与差异。结果:雌雄白蜡叶际优势菌门为蓝藻菌门和变形菌门,但菌门的组成比例在雌雄白蜡中存在差异,白蜡雌雄株叶际细菌在属水平上有差异,杀雄菌属仅在白蜡雌株中存在。结论:白蜡雌雄株叶际核心菌群一致,但在属水平存在一定的差异。

不同盐度和氮磷浓度条件下海马齿对水体氮磷的吸收效果及其生长响应

耐盐植物在海水养殖尾水处理和海水农业中具有重要作用。为了探究海马齿的耐盐能力和氮磷净化能力,本研究开展了海马齿盐度和氮磷处理的室内水培实验。盐度实验分别在盐度为0、10、20、30和35的霍格兰营养液中进行,氮磷实验分别在N:0(P:0.5)mg/L、N:1(P:0.1)mg/L、N:5(P:0.5)mg/L、N:20(P:2)mg/L和N:50(P:5)mg/L的人工海水中培养,周期为20 d。结果显示:1)在中、低盐度(0~20)条件下,海马齿对氮、磷的吸收效果明显,而在高盐度(30~35)条件下,其对氮磷的吸收作用明显弱于中低盐度组(P<0.05)。2)海马齿Na^(+)含量随盐度的升高而不断增加,而K^(+)含量则随着盐度的增加呈现下降的趋势;氮磷浓度对海马齿Na^(+)、K^(+)含量的影响不明显。3)在氮磷实验浓度范围内,海马齿都能正常生长并显示了较高的氮磷吸收能力,明显降低了水体中的氮磷浓度。表明海马齿有较强的耐盐能力,并能有效净化富营养化水体,可用于海水养殖尾水净化,改善养殖环境。

无机砷在海带中的富集及氧化胁迫效应

本研究采用海带孢子体幼苗为实验材料,分别用不同浓度的As(Ⅲ)和As(Ⅴ)(0.2、0.4、0.8、1.6μmol/L)培养液进行循环水养殖,以研究不同价态无机砷在海带中的积累以及对其抗氧化防御系统的影响。结果表明,高浓度砷暴露组中海带总砷含量较高,As(Ⅲ)暴露下海带中总砷含量随时间增加,在28 d时达到最大值;As(V)暴露下海带中总砷含量则呈先升高后下降的趋势,但28 d时除最高浓度组外均显著高于初始值(P<0.05)。实验结束时As(V)暴露组海带中总砷含量显著低于As(Ⅲ),说明无机砷暴露下海带孢子体幼苗对亚砷酸盐的积累大于砷酸盐。无机砷暴露下海带中过氧化氢(H_(2)O_(2))和丙二醛(MDA)含量随时间的延长分别呈先降低后升高和先降低后升高再降低的趋势,但所有处理组海带中H_(2)O_(2)和MDA含量均显著高于对照组(P<0.05),且随浓度的升高而升高。细胞中过氧化氢酶(CAT)活性在砷暴露下升高,但随暴露时间的延长,无机砷对酶活性产生了一定程度的抑制作用,酶活性降低。超氧化物歧化酶(SOD)活性在第1天时显著高于其他取样时间酶活性,随暴露时间的延长,砷影响减弱,SOD酶活性处于相对稳定状态,均显著高于对照组。海带能够积累海水中无机砷,且对As(Ⅲ)的积累能力较强,砷作用下虽然会对海带抗氧化防御系统产生一定的损伤,但其通过自我调节降低了砷的毒害作用。