Advance in the toxic effects of petroleum water accommodated fraction on marine plankton

Recently, the impact of petroleum pollution on marine plankton has been complemented by a great concern. This review summarizes the reports about toxic effects of oil water accommodated fraction (WAF) on marine phytoplankton, zooplankton and early life stage of animal. For the oil WAF, toxicants are mainly composed of the aromatic hydrocarbons, such as the benzene hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) with 2–5 rings. The oil WAF, especially the PAHs, can be accumulated in plankton due to their great lipophilic abilities, and thus elicites various deleterious effects. Toxicological tests show that marine plankton is very sensitive to the petroleum WAF, as the order of median effective/lethal concentration is merely μg/L or mg/L. There are species and developmental stages differences of plankton tolerance to petroleum WAF, and the toxicity of different oil WAF is various. Generally, its toxicity enhances with increasing carbonic chain length and benzene ring number. Many studies on the acute and sub-acute toxic effects of oil WAF have been done, however few researches on its chronic toxic effects has been carried out till now. Besides, most reports focused on the levels from molecule to individual, though very little work of petroleum toxic effects has ever been performed on the marine plankton population or community levels. Therefore, it is necessary to continue these studies in future.     

Effect of water stress by Polyethylene Glycol 8000 and Sodium Chloride on germination of Ephedra alata Decne seeds

Ephedra alata Decne is a perennial shrub and it is a very effective sand-binder. In Saudi Arabia, the species is associated with sand dunes formation, especially the mobile, non-saline and low moisture content ones. Its geographical distribution in Saudi Arabia includes the Northern, Eastern and Central regions. The aims of this study were to determine the effects of temperature, water potential and Sodium Chloride on germination of E. alata. Seeds were collected from King Khalid Centre of Wildlife Research and Development at Thumama (80 km north east of Riyadh), Saudi Arabia. Seeds were germinated at four alternating temperature regimes (8/22; 9/23; 13/27 and 18/35 °C). Seeds were also germinated under stress of aqueous Polyethylene Glycol (PEG) solutions mixed to create water potentials of 0; −0.3; −0.6; −1.2 and −1.5 MPa. Seed were also germinated in Sodium Chloride solutions of 0, 0.05, 0.1, 0.2 and 0.3 mol l⁻¹. Optimum germination was attained at 13/28 °C that corresponds to temperatures prevailing during spring time. Seeds germinated in Polyethylene Glycol solutions exhibited significantly lower germination than control especially when water potential fell below −0.3 MPa. Germination was also negatively affected by 0.1 mol l⁻¹ Sodium Chloride solution or above. Results indicated that the germination temperature responses of the nondormant seeds synchronize the event of germination with the season when environmental conditions are more favorable for subsequent growth and seedling establishment. Germination was also sensitive to both water potential and salinity.     

Potentiated effect of systemic administration of oxytocin on hypertonic NaCl intake in food-deprived male rats

Subcutaneous administration of oxytocin (OT) increases water intake and sodium/urine excretion in food-deprived male rats. This study analyzes the effect of OT administration (at 0830 and 1430h) on the consumption of water and hypertonic NaCl (1.5%). In the first experiment, injections of OT increased the intake of hypertonic NaCl (but not of water) in food-deprived rats but not in ad lib-fed animals during the second 12 h (2030 to 0830) of the treatment day. The net concentration of the fluid consumed by OT/deprived animals was close to isotonic. In the second experiment, the initial effect of OT administration was an increase in urine volume and urinary sodium excretion and concentration by food-deprived animals during the first 12 h (0830 to 2030). These findings suggest that in food-deprived animals, systemic administration of OT induces NaCl intake as a consequence of previous urine loss and urinary sodium excretion.     

Evidences for a Leaky Scanning Mechanism for the Synthesis of the Shorter M23 Protein Isoform of Aquaporin-4: IMPLICATION IN ORTHOGONAL ARRAY FORMATION AND NEUROMYELITIS OPTICA ANTIBODY INTERACTION*

Aquaporin-4 (AQP4) exists as two major isoforms that differ in the length of the N terminus, the shorter AQP4-M23 and the longer AQP4-M1. Both isoforms form tetramers, which can further aggregate in the plasma membrane to form typical orthogonal arrays of particles (OAPs) whose dimension depends on the ratio of the M1 and M23. In this study, we tested the hypothesis that the M23 isoform can be produced directly by the M1 mRNA. In cells transiently transfected with AQP4-M1 coding sequence we observed besides AQP4-M1 the additional presence of the AQP4-M23 isoform associated with the formation of typical OAPs observable by two-dimensional blue native/SDS-PAGE and total internal reflection microscopy. The mutation of the second in-frame methionine M23 in AQP4-M1 (AQP4-M1^M23I) prevented the expression of the M23 isoform and the formation of OAPs. We propose “leaky scanning” as a translational mechanism for the expression of AQP4-M23 protein isoform and that the formation of OAPs may occur even in the absence of AQP4-M23 mRNA. This mechanism can have important pathophysiological implications for the cell regulation of the M1/M23 ratio and thus OAP size. In this study we also provide evidence that AQP4-M1 is mobile in the plasma membrane, that it is inserted and not excluded into immobile OAPs, and that it is an important determinant of OAP structure and size.     

Identification of Anhydrobiosis-related Genes from an Expressed Sequence Tag Database in the Cryptobiotic Midge Polypedilum vanderplanki (Diptera; Chironomidae)

Some organisms are able to survive the loss of almost all their body water content, entering a latent state known as anhydrobiosis. The sleeping chironomid (Polypedilum vanderplanki) lives in the semi-arid regions of Africa, and its larvae can survive desiccation in an anhydrobiotic form during the dry season. To unveil the molecular mechanisms of this resistance to desiccation, an anhydrobiosis-related Expressed Sequence Tag (EST) database was obtained from the sequences of three cDNA libraries constructed from P. vanderplanki larvae after 0, 12, and 36 h of desiccation. The database contained 15,056 ESTs distributed into 4,807 UniGene clusters. ESTs were classified according to gene ontology categories, and putative expression patterns were deduced for all clusters on the basis of the number of clones in each library; expression patterns were confirmed by real-time PCR for selected genes. Among up-regulated genes, antioxidants, late embryogenesis abundant (LEA) proteins, and heat shock proteins (Hsps) were identified as important groups for anhydrobiosis. Genes related to trehalose metabolism and various transporters were also strongly induced by desiccation. Those results suggest that the oxidative stress response plays a central role in successful anhydrobiosis. Similarly, protein denaturation and aggregation may be prevented by marked up-regulation of Hsps and the anhydrobiosis-specific LEA proteins. A third major feature is the predicted increase in trehalose synthesis and in the expression of various transporter proteins allowing the distribution of trehalose and other solutes to all tissues.     

干藏和淹水对三峡库区21种草本植物种子萌发的影响

研究了三峡库区河岸带21种常见草本植物种子在干藏以及不同淹水深度（0.5、1.0和2.0m）处理下的萌发特性。结果表明：以新采集种子的萌发率作为对照,干藏后8个物种的萌发率增加（占总数的38.1%）,1种萌发率不变（4.8%）,12种萌发率降低（57.1%）。与对照相比,淹水后3个物种的萌发率增加（占总数的14.3%）,2个物种的萌发率不变（9.5%）,16个物种的萌发率下降（76.2%）。水淹处理后,占总数76.2%的物种的萌发率下降,其中11种显著下降;但淹水深度对种子的萌发没有显著影响。干藏后的繁穗苋（Amaranthus paniculatus）、皱果苋（Amaranthus viridis）和红刺果苋（Amaranthus sp.）以及水淹后的鳢肠（Eclipta prostrata）萌发率〉50%,而且能够利用库区退水期完成生活史形成种子,表明这些植物可作为三峡库区消落带植被恢复时优先考虑的物种源。     

微囊藻毒素-LR在罗非鱼(Oreochromis niloticus)体内的动态分布

应用腹腔注射染毒法,研究不同作用时间下微囊藻毒素-LR(MC-LR)在罗非鱼各组织器官的动态分布。结果表明:除罗非鱼肌肉中MC-LR含量低于检出限(用ND表示未检出)外,罗非鱼肝脏、血清、胆囊、鳃、肠道都有MC-LR检出;且各组织器官MC-LR残留量的分布有明显的区别,其中以肝脏中残留量的平均值为最高,其变化区间为0.902～4.938mg·kg-1,血清、胆囊、鳃、肠道的MC-LR残留量变化区间分别为ND～0.390mg·L-1、ND～0.236mg·kg-1、0.0134～0.0369mg·kg-1、0.007～0.016mg·kg-1;染毒后84h,罗非鱼肝脏、鳃、血清、胆囊中的MC-LR残留量都显著降低,且血清和胆囊中的MC-LR含量低于检出限,表明罗非鱼对MC-LR具有很强的解毒机能;染毒后36h,胆囊和肝脏中的MC-LR残留量骤然下降,由此推测胆囊和肝脏可能是罗非鱼对MC-LR的主要解毒器官;试验期间,肌肉中MC-LR含量始终低于检出限,表明低剂量的MC摄入不会在罗非鱼肌肉中造成明显的残留。     

中华倒刺鲤幼鱼的快速启动与逃逸行为

在水温25.0℃条件下,采用高速摄像机记录电刺激后体长(6.9+0.1)cm 相近的23尾中华倒刺(鱼巴)幼鱼的快速启动过程并通过对鱼体质心运动的分析考查3个阶段的相关运动参数.结果显示:实验鱼均表现为"C型"快速启动模式,逃逸方向不确定,但不同逃逸方向的相关参数间无显著差异(P＞0.05);快速启动后鱼体质心的移动距离(d)和线速度(V)均显著递增(P＜0.05),其中线速度在第2阶段末(36 ms)达到最大值,随后相对稳定,线加速度(a)在第2阶段末出现最大值(P＜0.05);而角速度(ω)初始启动即出现最大值,随后显著下降(P＜0.05),进入第3阶段后稳定在较低水平;第1阶段的线速度(V)与相对旋转半径(RTr)之间相关性不显著.研究结果表明:中华倒刺(鱼巴)幼鱼在快速启动过程中更倾向于采取提高运动速度的逃逸策略,这可能与其流线形体型和水流湍急的生境有关.     

养殖密度对银鲳幼鱼生长及组织生化指标的影响

养殖密度是水产养殖过程中不容忽视的关键因子之一,可直接影响到养殖成活率、生长性能、游动行为、健康状况、水质、摄食情况以及养殖产量。较高的养殖密度导致水质恶化、过度拥挤以及不利的群体效应等,从而会引起一系列的应激反应,最终影响到养殖效果。银鲳作为一种新兴的养殖品种,目前国内尚未见有关其养殖生物学方面的研究报道。本文的目的是研究养殖密度对银鲳(Pampusargenteus)幼鱼(5.33±0.07)g生长、组织中糖元与乳酸含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)活性的影响。本试验共设4组放养密度,分别为5、10、15、25尾.m-3,依次编为D1组、D2组、D3组、D4组,试验周期为60d。结果显示,在低于15尾.m-3(D3组)的密度范围内,银鲳的生长与养殖密度呈正相关,但在D4组,银鲳的生长率相对于D3组明显降低;各处理组间肝体指数与成活率并无显著性差异;随着养殖密度的提高,肌肉与肝脏中糖元含量明显降低,但肌肉乳酸含量并未有显著性变化;在D1至D3组密度范围内,养殖密度对肌肉与肝脏中SOD与CAT活性均未有显著性影响,但D4组的SOD活性均显著低于D2和D3组,且D4组肝脏CAT活性显著性低于D3组;然而,养殖密度对肌肉CAT活性以及组织中GSH-PX活性并未造成显著的影响。在试验周期内,本试验所设的养殖密度范围对银鲳并未产生明显的不良胁迫反应。     

Effects of temperature on purification of eutrophic water by floating eco-island system

The effects of temperature on pollutant removal of two plant species (Oenanthe javanica D.C. and Nasturtium officinale) were evaluated using simulated microcosms of the floating eco-island system (FEIS). Both the planted FEIS (P-FEIS) and the non-planted FEIS (NP-FEIS) dramatically decreased NH₄–N concentration in the hypereutrophic water at low (10 °C), medium (22 °C), and high (35 °C) temperatures, and to a greater extent for the P-FEIS and at medium temperature. The NO₂–N concentration was effectively decreased from 0.23 to 0.01 mg/L after 4 d treatment with the P-FEIS at all the three temperatures, but was slightly increased in the NP-FEIS at low temperature. The P-FEIS could decrease NO₃–N concentration in the eutrophic water over 1–3 times depending on temperature, with greater decrease at high temperature. The remove of total P (TP) reached 78%, on average, with the FEIS treatment for 4 d at all temperatures, which was over three times greater than those with the NP-FEIS at low temperature. The removal rates of Chla, COD_Mn, and BOD₅ by the P-FEIS from the hypereutrophic water were, on average, 70%, 85%, 83% at 22 °C and 35 °C, respectively, while over 1–2 times smaller at 10 °C. More effective removals of Chla, COD_Mn, and BOD₅ (over 1–2 times) were noted with the P-FEIS than those with the NP-FEIS. N. officinale showed more efficiency in removing ammonium and TN at low temperature, and BOD₅ at medium and high temperatures, as compared to O. javanica. Whereas O. javanica could more effectively decrease Chla at 22 °C and 35 °C and COD_Mn at 10 °C than N. officinale after 4 d treatment. Higher dissolved oxygen concentration and pH was found in the FEIS with N. officinale than that with O. javanica D.C. The results imply that plant eco-island system had remarkable purification ability to remove pollutants from hypereutrophic water, and mixed planting of O. javanica D.C. with N. officinale on the FEIS may enhance nutrient removal and water quality improvement of eutrophic water bodies, especially at low temperature season.