Aloysia triphylla essential oil as food additive for Rhamdia quelen – Stress and antioxidant parameters

We examined the effects of dietary supplementation for 21 days with different levels (0, 0.25 and 2.0 ml/kg) of the Aloysia triphylla essential oil (EOAT) on silver catfish (Rhamdia quelen). Cortisol levels were lower in fish fed EOAT at 2.0 ml/kg diet, and lactate levels were lower in those fed at both doses. Glucose, alanine aminotransferase, aspartate aminotransferase and triglyceride levels did not vary between groups. The biomarkers of oxidative stress, thiobarbituric acid‐reactive substances, lipid hydroperoxide, superoxide dismutase, catalase and non‐protein thiols, were lower in the brain, liver and muscle of fish fed EOAT at 2.0 ml EO/kg diet. Glutathione‐S‐transferase, reduced glutathione, plasma Na⁺, Cl^?, and K⁺, and gill Na⁺/K⁺‐ATPase and H⁺‐ATPase did not vary between groups. Taken together, our results clearly indicate that the addition of EOAT at 2.0 ml/kg diet improves oxidative status and lowers the stress response in silver catfish.     

持续干旱及复水对杜仲幼苗保护酶活性和渗透调节物质的影响

通过盆栽试验,研究了土壤干旱及复水对杜仲幼苗的生理特性。结果表明:杜仲叶片SOD、POD、CAT活性及P ro含量变化一致,随干旱时间的延长呈现先增加后降低的趋势;MDA含量表现出“增加→降低→再增加”的变化过程;可溶性蛋白变化呈“M”曲线;可溶性糖含量则呈现递增趋势。复水后,除可溶性糖外,其他各指标均恢复至较低水平。方差分析结果表明,持续干旱对杜仲、辽东栎的生理指标影响极显著(P<0.01)。经隶属函数法计算得出,杜仲具有一定的抗旱性,但是较辽东栎弱。     

白籽南瓜嫁接对不同盐胁迫下黄瓜幼苗氮代谢和蛋白表达的影响

采用营养液栽培,以白籽南瓜（Cucurbita maximaCucurbita moschata）为砧木,津优3号黄瓜为接穗,研究了白籽南瓜嫁接对等渗Ca(NO3)2和NaCl胁迫下黄瓜幼苗生长、氮代谢、渗透调节物质和蛋白表达的影响。结果表明:白籽南瓜嫁接黄瓜可明显促进Ca(NO3)2和NaCl胁迫下黄瓜嫁接苗生长,提高叶片和根系中硝酸还原酶（NR）活性及NO3--N、可溶性糖、脯氨酸和可溶性蛋白含量,抑制NH4+-N升高;叶片中可溶性蛋白表达量增强,其相对分子质量（103）分别约为188.4、156.1、120.4、54.0、37.3、32.1、30.6、18.9、17.8和17.1,并出现相对分子质量为64.3103的一种新蛋白,而81.0103的蛋白表达量减弱,这12种蛋白可能与白籽南瓜嫁接提高黄瓜耐盐性密切相关。研究还发现:NaCl胁迫下黄瓜自根嫁接和砧木嫁接植株叶片中相对分子质量（103）约为86.1、23.4、18.9和17.8的蛋白表达量大于等渗的Ca(NO3)2,相对分子质量（103）约为188.4、156.1、54.0和17.1 的蛋白表达量小于等渗的Ca(NO3)2;NaCl胁迫9 d后39.1103、35.4103和21.2103三种蛋白在自根嫁接株中消失,这11种蛋白可能与白籽南瓜嫁接株耐Ca(NO3)2胁迫能力强有关。综上,Ca(NO3)2胁迫对黄瓜幼苗造成的伤害程度显著低于等渗的NaCl 胁迫,白籽南瓜砧木嫁接可调节黄瓜植株体内氮素代谢,提高渗调能力,有效地缓解Ca(NO3)2和NaCl胁迫对黄瓜植株的伤害,尤其对Ca(NO3)2胁迫伤害的缓解效果明显,可以作为黄瓜耐盐砧木在生产上应用。     

锌胁迫对长药景天生理特性的影响

[目的]利用低浓度和高浓度的Zn SO4溶液对长药景天的长期胁迫,研究长药景天锌胁迫下的抗性能力。[方法]采用盆栽试验,锌以Zn SO4·7H2O的形式供给,浓度分别为0、160和1 600 mg·kg-1Zn SO4,分别于0、7、14、21、28、35 d采集长势健康,且个体相近的植株,在相同部位选取功能叶片,测定长药景天叶片生理指标的变化。[结果]表明:低浓度(160 mg·kg-1Zn SO4)锌胁迫下,长药景天叶片电导率和MDA含量增加不显著;SOD、POD和CAT等保护酶活性增加,脯氨酸、可溶性糖和可溶性蛋白含量增加,高浓度(1 600 mg·kg-1Zn SO4)下电导率和MDA含量增加,保护酶活性增加,脯氨酸、可溶性糖和可溶性蛋白含量变化较小。[结论]长药景天对锌胁迫表现出较强的抗性,低浓度锌胁迫下调节能力较强,高浓度下主要依赖于保护酶系统的调节作用抵抗锌胁迫。在持续锌胁迫过程中,长药景天生理上能迅速作出相应的适应性调节,对锌胁迫表现出一定的忍耐能力和较强的恢复能力。     

菲对蒿柳生理生化特性的影响

为研究菲对蒿柳生理生化的影响,以蒿柳扦插苗为试验材料,采用水培的方式,测定不同浓度(0.2、0.5、1.0和1.2 mg·L^-1)菲对蒿柳株高及生理的影响,并选取对植物生长有显著抑制作用的最低浓度(1.0 mg·L^-1)菲对蒿柳进行16 d的处理,测定其光合特性及渗透调节物质的变化。结果表明,高浓度菲处理显著抑制了蒿柳的株高和根系活力,使其电导率升高,膜透性增大。1.0 mg·L^-1菲胁迫下,蒿柳的光合作用受到抑制,光化学淬灭系数(qP)显著下降,光反应受到影响;气孔导度(Gs)和胞间CO₂浓度(Ci)下降、Rubisco活性降低,导致CO₂供应和同化减少,暗反应受到抑制。叶片的最大光化学效率(F_v/F_m)和PSⅡ潜在活性(F_v/F₀)无显著变化,说明PSⅡ利用光能的能力和潜在活性未受到影响。渗透调节物质中,脯氨酸和可溶性糖是植物抵御菲胁迫的重要调节物质。本研究结果为揭示多环芳烃(PAHs)对蒿柳产生的毒害机制及加强植物对环境的修复研究提供了依据。     

A dietary modification approach to improve the osmoregulatory capacity of Litopenaeus vannamei cultured in the Arizona desert

A modified diet was formulated for Arizona inland shrimp farming and tested as a method for reducing moult‐associated mortalities presumed due to trace mineral deficiencies. The experimental diet was supplemented with additional dietary magnesium, potassium, phospholipids and cholesterol to a commercial shrimp feed (Rangen 45/10, which was also used as the control diet). The modified diet was tested at Arizona Mariculture Associates (AMA), while the control diet was used at a nearby inland shrimp farm, Desert Sweet Shrimp Farm (DSSF). Both feeds were used throughout the culture season of 2001. Earthen pond‐reared Litopenaeus vannamei at intermoult stages (C‐D₀) and ranging from 7 to 30 g were sampled at intervals for determination of haemolymph osmolality (HO). Results showed that the modified diet had not only resulted in larger size shrimp at harvest, but also improved osmoregulatory capacity (OC). HO of DSSF shrimp decreased as shrimp grew bigger, whereas HO of AMA shrimp was maintained at a stable level, or showed a slightly positive linear relationship with weight. The hyper‐OC of shrimp from AMA (462 mOsm kg^?1) was greater than that from DSSF (398 mOsm kg^?1). Shrimp at AMA fed the experimental diet presented no mass moult‐associated mortalities. To further investigate the iso‐osmotic point of shrimp reared in AMA, a group of six salinity gradients were designed by mixing oceanic salts into the well water to form 5, 8.5, 11.4, 14.4, 17.8, 20.7 p.p.t. medium. HO of subadult shrimp (25 g in average) were then evaluated 48 h after they had been transferred from 5 p.p.t. pond water to the medium. Shrimp HO increased with external salinity, and a plateau formed as salinity reached at 11.4 p.p.t. and higher. The iso‐osmotic point of shrimp was estimated to be 695.5 mOsm kg^?1, equivalent to 26.1 p.p.t. in AMA well water.     

Seasonal variation in osmoregulatory and metabolic parameters in earthen pond-cultured gilthead sea bream Sparus auratus

Seasonal variations in osmoregulatory and metabolic parameters were assessed in juvenile gilthead sea bream ( Sparus auratus ) cultured in earthen ponds under a natural photoperiod and temperature. Specimens were sampled, and the plasma, gill, kidney and liver were collected during winter 2005 and 2006 (January), spring 2005 (April), summer 2005 (July) and autumn 2005 (October). Plasma osmoregulatory parameters showed higher values in summer, while metabolic parameters presented different patterns of variations. Gill Na⁺,K⁺-ATPase activity decreased significantly in winter, while gill metabolite levels showed different patterns of variations among seasons. The enzymatic activities tested did not present a clear pattern of variation [(glutamate dehydrogenase (EC 1.4.1.2) (GDH) and hexokinase (EC 2.7.1.11) (HK)] or significant differences along seasons [glucose 6-phosphate dehydrogenase (EC 1.1.1.49)]. Kidney Na⁺,K⁺-ATPase activity decreased during summer and autumn. Different patterns of variation were observed in kidney metabolite levels while all the enzymatic activities assessed [lactate dehydrogenase-oxidase (EC 1.1.1.27) (LDH-O), HK and GDH] presented the highest values during summer. In the liver, metabolite levels and enzymatic activities did not show significant variations or present clear patterns of variation along different seasons. These results indicated seasonal variations in the osmoregulatory and metabolic parameters of different organs (blood, gill, kidney and liver) in earthen pond-cultured gilthead sea bream ( S. auratus ), which could be mainly attributed to seasonal changes in temperature.     

华北景天叶片有机渗透调节物质对水分胁迫的响应

试验以华北景天为试材,采用人工控水方法,研究了不同水分胁迫强度对华北景天叶片有机渗透调节物质的影响.结果表明:在水分胁迫下,华北景天叶片中游离脯氨酸和可溶性糖含量变化不明显,可溶性蛋白含量变化显著.华北景天可通过可溶性蛋白的渗透调节作用,降低细胞的渗透势,维持细胞膨压,从而保证干旱条件下细胞的正常生长与代谢.所以,可溶性蛋白是水分胁迫条件下华北景天叶片细胞内重要的渗透调节剂.     

多伞阿魏生理特性与土壤水分、养分变化的关系

[目的]以新疆石河子阿魏滩多伞阿魏为研究对象,比较分析不同生长时期土壤条件和多伞阿魏生理特征的变化关系,探讨多伞阿魏的抗逆机理和受迫程度.[方法]运用样品分析法,对多伞阿魏生长过程中土壤含水量、养分等因子的变化,以及多伞阿魏叶片丙二醛(MDA)、可溶性糖、脯氨酸、可溶性蛋白质、叶绿素含量及超氧化物歧化酶(SOD)、过氧化氢酶(POD)、硝酸还原酶(NR)活性等生理指标进行测定分析.[结果]随着多伞阿魏的生长,土壤含水量、养分逐渐降低,其中土壤含水量的变化最为明显,同时叶片MDA、可溶性糖、脯氨酸的含量及SOD活性呈上升趋势,而POD、NR活性和可溶性蛋白质、叶绿素含量却呈下降趋势,且在各生长时期表现出不同的生理响应机制和协调作用;经相关分析得知,土壤含水量与各生理指标相关性最为显著,与叶片MDA、可溶性糖、脯氨酸含量及SOD活性呈负相关,而与可溶性蛋白质、叶绿素含量及POD、NR活性呈一定正相关.[结论]多伞阿魏在生长过程中受到了一定的水分等因素的胁迫,但在一定范围内能通过调节体内抗氧化酶系统活性和渗透调节物含量来积极响应生长环境的变化,以增强自身的适应能力.