Stoffbildung, CO2-Gaswechsel, Kohlenhydrat- und Stickstoffgehalt von Winterweizen bei erhöhter CO2-Konzentration und Trocken-streß

Dry Matter Production, CO₂ Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO₂ Concentration and Drought Stress
Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO₂ concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO₂ concentration and of drought stress on dry matter production, CO₂ exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO₂ concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO₂ concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO₂ treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO₂ concentration showed a reduced response of net photosynthesis rate to increasing CO₂ concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.     

氯化钾对热应激肉仔鸡生产性能的影响

本试验测定了氯化钾对热应激肉仔鸡生产性能的影响。试验应用２ｌ０只星布罗肉仔鸡，随机分成７组，每组３０只。氯化钾按０％、　０．０６％、０．１２％、０．１８％、０．２４％、０．３０％和０．３６％添加到饮水中，试验温度为３２±１℃，试验期为３５天。结果表明饮水中添加０．２４％、一０．３０％氯化钾能显著提高热应激条件下肉仔鸡的生产性能。     

Growth, stress response and free amino acid levels in Senegalese sole (Solea senegalensis Kaup 1858) chronically exposed to exogenous ammonia

Stressful husbandry conditions are likely to affect growth and amino acid metabolism in fish. In this study, chronic ammonia exposure was used to test the effects of a stressor on growth and amino acid metabolism of Senegalese sole juveniles. The fish were exposed for 52 days to 11.6 mg L⁻¹ [low‐TAN (L‐TAN)] or 23.2 mg L⁻¹ [high‐TAN (H‐TAN)] of total ammonia nitrogen (TAN), or to 0 mg L⁻¹ (Control). Growth in L‐TAN groups was slightly but significantly different from the Control groups [relative growth rate (RGR=0.35±0.13 and 0.52±0.23% day⁻¹ respectively)]. In H‐TAN groups, growth was severely affected (RGR=0.01±0.13% day⁻¹). Stress parameters (plasma cortisol and glucose) showed slight or no significant differences between treatments. Plasma free amino acid (FAA) concentrations were affected after H‐TAN treatment. Increases in glutamine and aspartate concentrations in H‐TAN fish suggest alterations in amino acid metabolism related to nitrogen excretion processes. Some of the changes in FAA concentrations also suggest mobilization to energy supply and synthesis of metabolites related to stress response. Therefore, Senegalese sole seem to adapt to the L‐TAN concentration tested, but the H‐TAN concentration reduced growth and affected amino acid metabolism.     

Alteration of liver and muscle fatty acid composition in gilthead seabream (Sparus aurata) juveniles held at high stocking density and fed an essential fatty acid deficient diet

The aim of the present study was to determine the combined effect of both stress and EFA deficiency on several biological and biochemical parameters. Fish were fed during 15 weeks two isocaloric and isoproteic diets: a control diet based on fish oil and formulated to meet the n-3 HUFA requirements for this species (1.5% of n-3 HUFA) and a deficient diet containing beef tallow and formulated to be deficient in n-3 HUFA. Each experimental diet was evaluated both at high and low stocking densities (10 and 3.2 kg m^–3 of initial density, respectively).High stocking density produced a chronic stress situation with elevation of plasma cortisol levels. It also caused a reduction in hepatosomatic index and liver lipid contents, increasing the oleic acid/n-3 HUFA ratios in the polar lipids. Fish fed the EFA deficient diet at low stocking density showed common deficiency symptoms. High stocking density in fish fed the EFA deficient diet induced a higher degree of EFA deficiency symptoms leading to mortality, liver steatosis, liver lipid deposition, reduced muscle lipid and reduced n-3 HUFA contents, which particularly affected EPA, but not DHA, suggesting a preferential retention of the latter fatty acid, specially in the phosphoglycerides fraction.     

干旱胁迫对杂交鹅掌楸无性系叶片内源激素含量的影响(摘要)(英文)

[目的]研究干旱胁迫对杂交鹅掌楸无性系叶片内源激素含量的影响。[方法]挑选抗旱性强的杂交鹅掌楸无性系NE25、NE78与抗旱性差的无性系NE04、NE23的1年生扦插苗为试验材料,对干旱胁迫下各无性系叶片中脱落酸(ABA)、吲哚乙酸(IAA)、玉米素核苷(ZR)和茉莉酸(JA)4种内源激素的含量变化进行研究。[结果]干旱胁迫下,杂交鹅掌楸各无性系叶片ABA大量积累,抗旱性强的无性系含量变化不明显;IAA含量总体呈下降趋势,且抗旱性强的无性系含量变化较大;ZR含量变化各异,胁迫末期抗旱性强的无性系叶片ZR含量减少;抗性差的无性系叶片JA含量上升,说明抗性差的无性系需要维持较高的JA来抵御干旱胁迫。[结论]该研究结果为杂交鹅掌楸耐旱无性系的筛选、园林栽培及应用提供了科学依据。     

Expression of HSP70 in response to heat-shock and its cDNA cloning from Mediterranean blue mussel

Expression of HSP70 in response to heat-shock was investigated at the protein and mRNA levels in Mediterranean blue mussel. Western and Northern blot analyses revealed that HSP70 was expressed following heat-shock in the mantle at both protein and mRNA levels, suggesting that gene expression of HSP70 is implicated in the cellular response to heat-shock stress in mussel. It was then attempted to clone HSP70 cDNA in order to determine the primary structure of mussel HSP70. As a result, two full-length cDNA encoding HSP70 were isolated from a cDNA library prepared from the heat-shocked mantle. The isolated cDNA consist of single open reading frames of 2067 bp and 1911 bp which encode proteins of 689 amino acids and 637 amino acids, respectively. Both HSP70 cDNA encode an ATPase do main, and a substrate-binding do main in addition to a Glu-Glu-Val-Asp (EEVD) peptide motif that is specific for cytosolic HSP70. These findings suggest that the cDNA clones obtained in the present study encode cytosolic HSP70.     

Reduction of transport stress of ayu by obligated schooling

We investigated stress responses of ayu Plecoglossus altivelis under the hypothesis that overcrowding during transport can be a stressor and the stress predisposes fish to disease by decline in immunocompetence. The extent of stress response was determined under different fish densities. As inferred from the serum concentration of cortisol 1 day after the treatment, the density at more than 23 kg/m³, which was within the range of normal transporting procedures, acutely evoked intense stress responses. To examine a possible way to reduce the stress response of fish under crowding conditions, we compared two fish groups established in water tanks with circulating (whirling) and turbulent currents at the same density. The cortisol levels 1 day after the treatment were 2.5-fold higher in turbulent current than in whirling current. Fish in whirling current formed a school, while those in turbulent current aggregated with each other. Schooling of fish induced by water flow may reduce their stress responses during transport. A transport system with a directional water flow should keep fish in good condition without reducing the number of fish contained.     

Differential HSP90α expression in fish hepatocytes from polluted estuary during summer

The molecular chaperone, heat shock protein 90α (HSP90α), plays an important role in protein folding, degradation of denatured proteins and steroid activation. It is essential for the maintenance of cellular integrity and survival when induced in response to environmental, physical and chemical stresses. In the present investigation the effect of environmental stress on HSP90α expression was examined in grey mullet Mugil cephalus living in either a contaminated (Ennore) or uncontaminated (Kovalam) estuary over two seasons: Hepatocytes were isolated from grey mullet of both estuaries. Oxidative stress was determined along with HSP90α in these fish. Additionally, immunohistochemical changes were studied to confirm the HSP90α expression. Comparison of the results revealed enhanced hepatocyte oxidative stress and HSP90α expressions in fish from Ennore to a significant extent than fish from Kovalam. Also, the results showed significant seasonal variations with maximum expression observed during summer compared to the monsoon season. Overexpression of HSP90α in hepatocytes exposed to chronic environmental stress by pollutants may confer differential effects on cell survival by protecting against oxidative stress induced changes. The results also indicate that seasonal variations have significant effect on the HSP90α expression.     

Water deficit and cold stress on the evening primrose seed quality

Evening primrose is a valuable oilseed crop with pharmaceutical and nutritional supplementation. Due to presence of valuable and rare gamma linolenic fatty acid, research on this plant has been started since 1970s by German and Britain scientists. Information about evening primrose cultivation is going to rise. Following to pervious studies the goal of this experiment was to clarify the effect of water and temperature stresses on seed yield and seed quality. Results showed that seed yield was significantly influenced by low temperature and water deficit. Plants grown under cold stress during rosette stage produced a lower seed yield than controls. The lowest seed yield was observed in the plants grown under permanent stress. Although the oil content of seeds was not influenced by low temperature stress, water stress strongly influenced the oil content and water stress stimulates oil accumulation. Like oil content, the GLA production seems to be increased under water stress conditions.