Physiological responses of dietary tryptophan fed Labeo rohita to temperature and salinity stress

Two experiments were conducted to elucidate the possible effects of dietary L‐tryptophan (TRP) in Labeo rohita based on growth performance and physio‐biochemical responses. In the experiment I, a 60‐day feeding trial was carried out to elucidate the effects of dietary TRP enrichment on growth performance and physio‐biochemical responses. In the experiment II, the TRP pre‐fed L. rohita, from experiment I, was exposed to temperature and salinity stress to evaluate stress‐mitigating efficacy of TRP. In L. rohita, dietary supplementation of TRP showed significant effect on weight gain percentage and feed conversion ratio but not on blood glucose. A significant increase in RNA content and RNA/DNA ratio upon TRP supplementation was observed and was positively correlated with growth performance. The results of experiment II indicated that weight gain percentage, serum T3 and T4 levels were significantly reduced in groups that were exposed to temperature and salinity stress and fed diets without TRP supplementation. However, dietary supplementation of TRP significantly augmented weight gain percentage in stress‐exposed groups. Tryptophan supplementation helped in bringing back T3 and T4 levels comparable with control. A significant increase in superoxide dismutase, catalase, Adenosine triphosphatase, blood glucose and serum cortisol was observed in temperature‐ and salinity‐exposed groups fed without TRP‐supplemented diets. However, TRP supplementation was found to be effective in restoring the above parameters. The results of these experiments suggest that dietary TRP supplementation augments growth, lowers energy demand and helps in mitigating thermal and salinity stress in L. rohita.     

盐胁迫下泛菌属内生细菌对杂交狼尾草发芽及生理的影响

内生细菌作为一种宝贵的天然微生物资源,在植物防病、杀虫、促生、耐盐及耐干旱能力等方面具有广阔的应用前景。本研究分析了泛菌属内生细菌(Pantoea sp.)PP04对不同盐浓度胁迫下杂交狼尾草(Pennisetum americanum×P.purpureum)种子萌发及幼苗生长的影响。结果表明,该内生细菌在低(100mmol·L~(-1))、中(200mmol·L~(-1))度盐浓度下,对杂交狼尾草种子的萌发率、发芽指数及胚芽长度都有明显增益作用,增幅分别达10.75%、28.57%和300%。进一步研究发现,在不同浓度的盐胁迫下,内生细菌PP04通过诱导杂交狼尾草不同的抗氧化保护酶活性,从而减少膜脂过氧化作用,降低丙二醛(MDA)的含量。在低、中浓度盐胁迫下,PP04能显著提高杂交狼尾草超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸酶(APX)的活性。其中SOD和POD活性在低盐胁迫下增幅最高,可达64.17%和73.14%;而CAT和APX酶活性在高盐(300 mmol·L~(-1))胁迫下增幅最大,可达160.57%和73.38%。说明该内生细菌菌株可通过缓解氧化胁迫对植物造成的损伤,显著提高植物对盐胁迫的耐受性,具有良好的开发应用前景。     

Flash flood simulation and valve behavior of Mytilus galloprovincialis measured with Hall sensors

Mussels close their shell as a protective strategy and the quantification of this behavioral marker may represent an alarm signal when they are exposed to environmental stressors. In the present study, we investigated the ability of the Mediterranean mussel Mytilus galloprovincialis to recover and then the resilience or inertia of valve activity after a pulsing exposition to diverse levels of salinity (5, 10, 20, and 35 PSU as reference value). The trial simulated an event of drastic and sudden reduction of seawater salinity thus mimicking an event of flash flood from intense rain. Valve gaping and movements were measured in continuous cycle for 10 days using a customized magneto-electric device which uses Hall sensors. Results showed that under normal conditions of salinity (35 PSU), the general pattern of valve movements was a continuously open state with sporadic spikes indicating a closing motion. At salinity of 5, PSU mussels reacted by closing their valves, leading to a 77% mortality on the 4th day. At salinity of 10, PSU animals were observed with closed valves for the entire duration of the exposure and no mortality occurred, they showed a significant reduction in the valve activity once the reference value of salinity was re-established. In contrast, salinity of 20 PSU did not trigger a significant behavioral response. Interestingly, there no define rhythms of valve movements were recorded during salinity challenges.     

Soil salinity and sodicity effects of wastewater irrigation in South East Australia

Although ‘sewage farming’ or wastewater irrigation started in Australia in the latter parts of the 19th century, it was in the late 1960s that a considerable interest was revived in arid and semi-arid parts of the world due to scarcity of alternative water sources and the urgency to increase local food production. The practice has manifold benefits in the form of water conservation, nutrient recycling, surface and ground water pollution prevention. But for arid and semi-arid regions like many parts of Australia, while wastewater irrigation can be an attractive solution to irrigation water problems, it might not be the ideal solution for the common soil types encountered in these regions. Due to characteristic low rainfall, high evaporation and low leaching, these soils tend to have higher salt accumulations. This paper examines the soil salinity and sodicity effects of wastewater irrigation in soil types typical to South Eastern Australia and takes the soils of Western Treatment Plant (WTP) as a case study to highlight these issues.     

盐度变化对军曹鱼稚鱼相关免疫因子及其生长的影响

研究了盐度(5、10、20、30及对照37)对军曹鱼(Rachycentron canadum)稚鱼生长及其血清溶菌酶、碱性磷酸酶(ALP)、旁路途径补体(ACP)溶血活性(ACH50)和总免疫球蛋白(T-Ig)含量等免疫因子的影响。实验周期为14 d。结果表明,在逐渐达到设定盐度后养殖14 d,盐度30组稚鱼特定生长率(SGR)最高(5.77%/d),而盐度5和10组的SGR(分别为4.24%/d和4.38%/d)显著低于其他组(P<0.05)。在低盐度环境中血清溶菌酶活性在第7天各组都有不同程度升高,其中以盐度20组升高最为显著,其次为盐度10和30组,但第14天各组溶菌酶活性又都回落至对照组水平;而稚鱼在低盐度环境中血清ALP活性受到明显抑制,且活性与盐度呈一定正相关;各组间ACP活性在第7天各盐度组间无明显差异,但实验结束时盐度5和10两组出现显著升高;而T-Ig含量在盐度10组中始终明显高于其他组。研究显示,军曹鱼稚鱼在盐度20~37范围内都可正常生长,尽管稚鱼有较强的低盐度耐受能力,但过低盐度明显影响其生长率并导致体色变黑、蛀鳍和应激增强等异常表现。此外,盐度变化还影响稚鱼多种免疫相关因子。[中国水产科学,2007,14(1):120-125]     

生态因子对芋根江蓠的生长及生化组分的影响

芋根江蓠（Gracilaria blodgettii）是江蓠属一种经济海藻,可作为琼胶工业原料和鲍鱼饲料,目前已经在中国南方池塘进行试验栽培。为了探讨适合其栽培的生态条件,文章分别测定了在不同温度（18 ℃、23 ℃、28 ℃、33 ℃和38 ℃）、不同盐度（13、18、23、28、33和38）和不同光照强度（3 000 lx、6 000 lx、9 000 lx和12 000 lx）的培养条件下,芋根江蓠藻体的相对生长速率（RGR）和生化组分的变化。结果表明,芋根江蓠适宜生长温度为23~38 ℃,最适温度为28~33 ℃;适宜盐度为18~38,最适盐度为23~33;适宜光照强度为6 000~9 000 lx,最适宜生长光照强度为9 000 lx。在最适的环境条件下,藻体具有较高的日相对生长速率（RGR）,藻胆蛋白和可溶性蛋白（SP）的质量分数最高,过氧化物酶（POD）的活性及丙二醛（MDA）的质量摩尔浓度最低,受环境的胁迫最小。在生长状态、光合色素和抗氧化等方面,芋根江蓠具有适应高温和中、高盐度环境条件的特性。     

Response to salinity of three grain legumes for potential cultivation in arid areas

Abstract

The material balance of all the chemical species associated with the phosphate sorption reaction by two amorphous clays, silica-alumina gel and synthetic goethite was investigated adjusting the initial pH to 4.0, 5.0, 6.0, and 7.0. Phosphate sorption was found to decrease with increasing initial pH. During phosphate sorption, the equilibrium pH rose, adsorption of Cl^- decreased to a state of negative adsorption, adsorption of Na⁺ increased markedly, silicate was released, and Al in the solution was precipitated. With increasing initial pH, the amount of apparent released OH^- increased, the amount of Na⁺ adsorption increased, and the amount of released silicate decreased. The overall relationship of the material balance is explained in terms of the charge balance associated with phosphate sorption.     

两种盐度下凡纳滨对虾饲料中的最适动植物蛋白比

试验研究了不同盐度下（3和22）,以鱼粉和大豆浓缩蛋白为蛋白源,配制6种不同动植物蛋白比的饲料对凡纳滨对虾生长、成活和肝胰腺可溶性蛋白质含量的影响,饲养试验为期40 d。结果显示：（1）饲料动植物蛋白比可显著影响凡纳滨对虾增重率、成活率、肝体指数、肥满度和肝胰腺中可溶性蛋白质含量。增重率随饲料动植物蛋白比升高而升高,但当饲料中动植物蛋白比升至29∶8时,增重率不再明显升高,其它指标均先随饲料动植物蛋白比升高至一定程度,而后则稍有下降;（2）盐度22组对虾的增重率、成活率和肥满度显著高于盐度3组对虾,肝体指数却显著低于盐度3组,不同的盐度对凡纳滨对虾肝胰腺可溶性蛋白含量的影响不显著;（3）双因素方差分析结果显示,盐度和饲料动植物蛋白比对凡纳滨对虾增重率、成活率和肝体指数存在显著交互作用,最大值分别出现在盐度22下全动物蛋白饲料组、盐度22下全动物蛋白和动植物蛋白为29∶8的饲料组、盐度3下饲料动植物蛋白比为14∶23的饲料组中;（4）Broken-Line分析表明,3‰盐度下凡纳滨对虾最适饲料蛋白比为29.12∶7.79~30.29∶6.71,盐度22时为26.05∶10.95~29.03∶7.44。结果提示,饲料中氨基酸的组成和含量会随配方中动植物蛋白配比而改变,且不同盐度下凡纳滨对虾对饲料中动植物蛋白比的要求有所不同,但配饵中适当的动植物蛋白比可以满足虾对各种氨基酸的适宜需求。因此,在养殖过程中,需结合实际的养殖环境和饲料蛋白源种类,来设计适宜的实用饲料配方,这样才能达到降低生产成本,提高经济效益的目的。     

浙江沿海三疣梭子蟹的养殖模式

为开发三疣梭子蟹低盐耐受性相关甲基化标记,采用甲基化敏感性高分辨率熔解曲线法(methylation sensitive high resolution melting curve, MS-HRM)进行了三疣梭子蟹低盐耐受性相关甲基化位点的筛选和应用。结果显示,从三疣梭子蟹转录组数据库中共开发了8个甲基化标记,其中6个标记与低盐度耐受性显著相关,在低盐度条件下表现出显著的去甲基化或甲基化,这些标记分别位于V-ATP酶(V-type proton ATPase)、CLC型氯离子通道、琥珀酸脱氢酶、NAD(P)转氢酶(NAD(P)、磷酸乙醇酸性磷酸酶、NADH还原酶基因,为三疣梭子蟹耐低盐新品种的分子标记辅助选育提供候选工具。研究表明,“宁象1号”耐低盐能力显著高于野生群体,且选育群体中位点Pt-M1、Pt-M2的去甲基化率达到100%,可能有利于低盐条件下保持体内Na⁺和Cl⁻的平衡。     

Leaf K/Na ratio predicts salinity induced yield loss in irrigated rice

Salinity is a major constraint to irrigated rice production, particularly in semi-arid and arid climates. Irrigated rice is a well suited crop to controlling and even decreasing soil salinity, but rice is a salt-susceptible crop and yield losses due to salinity can be substantial. The objective of this study was to develop a highly predictive screening tool for the vegetative growth stage of rice to estimate salinity-induced yield losses. Twenty-one rice genotypes were grown over seven seasons in a field trials in Ndiaye, Senegal, between 1991 and 1995 and were subjected to irrigation with moderately saline water (3.5 mS cm^-1, electrical conductivity) or irrigation with fresh water. Potassium/sodium ratios of the youngest three leaves (K/Na_Leaves) were determined by flame photometry at the late vegetative stage. Grain yield was determined at maturity. All cultivars showed strong log-linear correlations between K/Na_Leaves and grain yield, but intercept and slope of those correlations differed between seasons for a given genotype and between genotypes. The K/Na_Leaves under salinity was related to grain yield under salinity relative to freshwater controls. There was a highly significant correlation (p < 0.001) between K/Na_Leaves and salinity-induced grain yield reduction: the most susceptible cultivars had lowest K/Na_Leaves and the strongest yield reductions. Although there were major differences in the effects of salinity on crops in both the hot dry season (HDS) and the wet season, the correlation was equally significant across cropping seasons. The earliest possible time to establish the relationship between K/Na_Leaves under salinity and grain yield reduction due to salinity was investigated in an additional trial in the HDS 1998. About 60 days after sowing, salinity-induced yield loss could be predicted through K/Na_Leaves with a high degree of confidence (p < 0.01). A screening system for salinity resistance of rice, particularly in arid and semi-arid climates, is proposed based on the correlation between K/Na_Leaves under salinity and salinity-induced yield losses. This revised version was published online in July 2006 with corrections to the Cover Date.