低氧及酸化胁迫对大黄鱼幼鱼离子调节与鳃组织结构的影响

为探讨大黄鱼幼鱼在低氧及酸化胁迫下机体离子调节情况,本研究探讨了低氧(溶解氧量DO 3.5 mg·L^-1,pH 8.1)、酸化(DO 7.0 mg·L^-1,pH 7.35)以及低氧酸化协同胁迫(DO 3.5 mg·L^-1,pH 7.35)对大黄鱼幼鱼鳃组织结构以及离子调节相关生理指标的影响。结果表明: 低氧胁迫下,大黄鱼幼鱼鳃Na⁺/K⁺-ATP酶活力、血清Na⁺、Ca²⁺及Cl^-含量随胁迫时间的延长呈先递减后递增的趋势。酸化胁迫下,大黄鱼幼鱼鳃Ca²⁺-ATP酶活力、血清Na⁺及Ca²⁺含量呈先递增后递减的趋势。低氧酸化协同胁迫下,Na⁺/K⁺-ATP酶活力及Na⁺、K⁺、Ca²⁺含量呈先递增后递减的趋势,Ca²⁺-ATP酶活力、Cl^-含量则呈先递减后递增的趋势。鳃组织学结果表明,低氧、酸化胁迫均导致鳃小片上皮细胞出现脱离现象,低氧酸化协同胁迫导致鳃小片上皮细胞出现增生、肥大、隆起现象。综合分析表明,低氧及酸化胁迫影响了大黄鱼幼鱼主要离子调节酶活力并对鳃组织造成了不同程度的损伤,最终导致了大黄鱼幼鱼体内离子调节失衡。     

盐胁迫下外源褪黑素和Ca2+对甜瓜幼苗的缓解效应

以甜瓜品种‘羊角酥瓜’为试材,利用人工气候室控制环境条件(昼/夜25/18 ℃),研究盐胁迫条件下外源褪黑素(MT)和Ca²⁺对甜瓜幼苗根系和叶片中Cl^-、Na⁺、K⁺、Mg²⁺、Ca²⁺离子含量,Na⁺/K⁺、 Na⁺/Ca²⁺、Na⁺/Mg²⁺值,以及H⁺-ATP酶活性、渗透调节物质积累和细胞膜质过氧化的影响.结果表明: 与对照相比,盐胁迫处理显著抑制甜瓜幼苗生长,增加根系和叶片中Cl^-、Na⁺含量,降低K⁺、Mg²⁺、Ca²⁺含量.盐胁迫下,喷施外源MT或Ca²⁺处理均可以显著降低甜瓜根系和叶片中Cl^-、Na⁺含量,提高K⁺、Mg²⁺、Ca²⁺含量,植株体内Na⁺/K⁺、Na⁺/Ca²⁺和 Na⁺/Mg²⁺值下降;同时也提高了根系和叶片H⁺-ATP酶活性及叶片渗透调节物质的含量,降低盐胁迫对细胞膜的伤害,表现在甜瓜叶片相对电导率和丙二醛含量降低.总之,在盐胁迫条件下,外源MT、Ca²⁺单独和复配处理均可通过提高H⁺-ATP酶活性来降低盐害离子的含量,改善甜瓜幼苗中的离子平衡,同时增加渗透调节物质的含量,降低膜质过氧化水平,从而增强其对盐胁迫的适应性,其中MT和Ca²⁺复配处理时的效果更好.复配外施 MT 和Ca²⁺在诱导甜瓜幼苗提高耐盐方面具有协同增效作用.     

盐胁迫下外源褪黑素和Ca2+对甜瓜幼苗的缓解效应

以甜瓜品种‘羊角酥瓜’为试材,利用人工气候室控制环境条件(昼/夜25/18 ℃),研究盐胁迫条件下外源褪黑素(MT)和Ca²⁺对甜瓜幼苗根系和叶片中Cl^-、Na⁺、K⁺、Mg²⁺、Ca²⁺离子含量,Na⁺/K⁺、 Na⁺/Ca²⁺、Na⁺/Mg²⁺值,以及H⁺-ATP酶活性、渗透调节物质积累和细胞膜质过氧化的影响.结果表明: 与对照相比,盐胁迫处理显著抑制甜瓜幼苗生长,增加根系和叶片中Cl^-、Na⁺含量,降低K⁺、Mg²⁺、Ca²⁺含量.盐胁迫下,喷施外源MT或Ca²⁺处理均可以显著降低甜瓜根系和叶片中Cl^-、Na⁺含量,提高K⁺、Mg²⁺、Ca²⁺含量,植株体内Na⁺/K⁺、Na⁺/Ca²⁺和 Na⁺/Mg²⁺值下降;同时也提高了根系和叶片H⁺-ATP酶活性及叶片渗透调节物质的含量,降低盐胁迫对细胞膜的伤害,表现在甜瓜叶片相对电导率和丙二醛含量降低.总之,在盐胁迫条件下,外源MT、Ca²⁺单独和复配处理均可通过提高H⁺-ATP酶活性来降低盐害离子的含量,改善甜瓜幼苗中的离子平衡,同时增加渗透调节物质的含量,降低膜质过氧化水平,从而增强其对盐胁迫的适应性,其中MT和Ca²⁺复配处理时的效果更好.复配外施 MT 和Ca²⁺在诱导甜瓜幼苗提高耐盐方面具有协同增效作用.     

不同生境下胡杨树体离子平衡及其与土壤因子关系

为探讨胡杨适应盐渍环境的离子分布规律,揭示胡杨的耐盐生理机制,以高盐和低盐两种不同生境中的胡杨(Populus euphratica)为对象,测定其根、树干、老枝、幼枝、叶片等不同器官中Na⁺、K⁺、Ca²⁺、Cl^-的含量,并分析各离子吸收、运输和分配特征的差异及其与土壤因子的关系。结果表明：(1)胡杨叶片中Na⁺、Cl^-含量在高盐生境下显著低于低盐生境,K⁺含量在高盐生境下显著高于低盐生境,其他器官的各离子含量变化均不显著;胡杨老枝、幼枝、叶片的K⁺/Na⁺在高盐生境下均显著高于低盐环境、Ca²⁺/Na⁺增幅不明显;在高盐生境下,根系选择吸收K⁺能力显著低于低盐环境,但吸收Ca²⁺能力较强,且各器官对Ca²⁺、K⁺选择向上运输的能力更强。(2)在低盐环境中Na...     

NaCl胁迫下沙芥的渗透调节作用

本文系统分析了荒漠资源植物沙芥在不同浓度NaCl下的渗透调节作用。结果表明,随外加NaCl浓度从25 mmol·L^-1升高至200 mmol·L^-1,Na⁺、Cl^-、脯氨酸和总无机离子的含量及其对叶渗透势的贡献不断升高,K⁺和可溶性糖的含量及其贡献先降低后升高,SO₄^2-和PO₄^3-的含量不断升高但其贡献变化不大;Na⁺、Cl^-和K⁺对叶渗透势的贡献交替位列前三,可溶性糖位居第四。由上可知,沙芥主要通过积累无机离子特别是Na⁺和Cl^-进行渗透调节以抵御外加NaCl的渗透胁迫。     

滨海滩涂地带乌哺鸡竹和淡竹离子含量变化及其与生长及光合作用的关系

在沿海滩涂防护林带低盐区(0.1%)、中盐区(0.2%)和重盐区(0.4%) 3个盐分梯度下,研究了栽植10年的乌哺鸡竹和淡竹Na⁺、K⁺、Ca²⁺、Mg²⁺含量变化及其与生长和光合作用的相关关系.结果表明: 从低盐区到重盐区,乌哺鸡竹的立竹密度和地径分别下降30.4%和28.8%,降幅低于淡竹的44.1%和31.2%;两竹种单株生物量下降,地上器官生物量降幅均显著高于地下器官;乌哺鸡竹和淡竹净光合速率(P_n)和PSⅡ最大光化学效率(F_v/F_m)分别下降57.6%和67.7%、6.1%和7.4%,乌哺鸡竹耐盐能力比淡竹强.随着土壤含盐量的增大,乌哺鸡竹和淡竹各器官Na⁺含量逐渐增加,K⁺、Ca²⁺、Mg²⁺含量逐渐降低.两竹种根Na⁺积累较多,而地上部分K⁺含量较高.盐胁迫环境导致乌哺鸡竹根Ca²⁺含量与淡竹叶片Mg²⁺含量明显下降.两竹种的生物量、P_n、F_v/F_m与Na⁺含量呈显著负相关,与K⁺、Ca²⁺含量呈显著正相关.     

磁化微咸水灌溉对欧美杨I-107离子稳态的影响

为探究微咸水磁化处理条件下植株的离子稳态特征,以欧美杨I-107一年生扦插苗为试材,于生长季节分别采用Hoagland营养液和4.0 g·L^-1 NaCl微咸水,经磁化处理后连续灌溉30 d.采用原子吸收分光光度法对叶片和根系中K⁺、Na⁺、Ca²⁺和Mg²⁺含量进行测定,分析离子平衡系数(K)和根-叶之间的离子选择性运输系数(S_Xi,Na).结果表明: 与非盐分胁迫处理相比,盐分胁迫处理根系和叶片中Na⁺和Ca²⁺含量及S_K,Na、S_Mg,Na升高,K⁺和Mg²⁺含量、K⁺/Na⁺及S_Ca,Na降低.与非磁化微咸水灌溉处理相比,磁化微咸水灌溉处理的根系和叶片中Na⁺含量降低、K⁺含量及K⁺/Na⁺提高;根系和叶片中Ca²⁺含量降低、Mg²⁺含量提高;磁化微咸水灌溉处理中K提高,且叶片中K值显著高于根系;S_K,Na和S_Mg,Na较非磁化微咸水灌溉提高,S_Ca,Na较其降低.磁化微咸水灌溉中根系和叶片Na⁺积累量减少,K⁺、Ca²⁺和Mg²⁺含量增加,且维持了较高水平的K⁺/Na⁺,这有利于植株整株水平生理代谢的调控.因此,盐分胁迫下磁化作用可通过调节离子的选择性吸收和运输来维持植株体内的离子平衡.     

高盐胁迫对罗布麻生长及离子平衡的影响

采用网室盆栽试验,研究了不同浓度NaCl（100～400 mmol·L^-1）胁迫30 d对罗布麻植株生物量积累、生长速率、根系活力、盐分和矿质离子吸收、分布等的影响.结果表明：100 mmol·L^-1 NaCl处理30 d,罗布麻植株鲜质量和生长速率显著下降,但对其干质量没有影响;随着盐度的增加,罗布麻植株干质量、鲜质量和生长速率均显著降低.100～200 mmol·L^-1 NaCl胁迫下,罗布麻根系活力明显高于对照;300～400 mmol·L^-1 NaCl盐胁迫下,其活力显著降低.随着盐浓度的增加,罗布麻根、茎和叶片Na⁺含量逐渐增加、K⁺含量缓慢降低;叶片Ca²⁺、Mg²⁺含量明显降低,茎部Ca²⁺和根部Mg²⁺含量有不同程度的增加.盐胁迫明显降低了罗布麻根、茎和叶片K⁺/Na⁺、Ca²⁺/Na⁺和Mg²⁺/Na⁺的比率,植株选择性吸收和运输K⁺、Ca²⁺的能力显著提高.罗布麻植株很强的拒盐能力,以及对K⁺、Ca²⁺的选择性吸收和运输是其具有高盐适应性的主要原因.     

海水处理下菊芋幼苗生理生化特性及磷效应的研究

种植抗盐耐海水植物是合理利用和开发海涂资源的有效措施之一。该试验研究了海水处理下菊芋(Helianthus tuberosus)幼苗生长发育、渗透物质积累、保护性酶活性、膜透性和离子吸收分布情况及磷素对其影响。结果表明:1)10%海水对菊芋幼苗生长发育没有抑制作用,甚至有一定的促进作用,25%海水胁迫对菊芋幼苗形态发育上具有一定抑制作用,增加磷素浓度后,能显著缓解其抑制作用;2)10%和25%海水处理下,脯氨酸和可溶性糖含量较对照显著增加,随着时间的延长,先增加后降低,增加磷素浓度后,能显著增加菊芋幼苗叶片脯氨酸和可溶性糖含量;3)海水处理下菊芋幼苗叶片SOD、POD和CAT活性都显著增加,增加磷素浓度后,能显著增强菊芋幼苗叶片SOD、POD和CAT活性;4)10%海水处理菊芋幼苗叶片MDA含量与对照差异不大,甚至小于对照,25%海水处理能显著增加MDA含量及膜透性,增加磷素浓度后,均降低了MDA含量和膜透性;5)随着海水浓度增加和时间延长,菊芋幼苗地上部和根部Na⁺和Cl^-含量显著增加,增加磷素浓度后,均能降低地上部和根部Na⁺和Cl^-含量,而地上部和根部K⁺、Ca²⁺和Mg²⁺含量较对照增加,增加磷素浓度后,均能增加K⁺、Ca²⁺和Mg²⁺含量。由此可见,磷素能够改善菊芋幼苗的营养状况,同时能够增强其抗盐性。     

温度和摄食对溪红点鲑幼鱼呼吸代谢的影响

在不同水温［(5.5±0.5) ℃、(8.5±0.5) ℃、(11.5±0.5) ℃、(14.5±0.5) ℃、(17.5±0.) ℃］条件下,分别测定了饱食和空腹状态下溪红点鲑幼鱼的耗氧率和排 氨率,分析了温度和摄食对溪红点鲑幼鱼呼吸代谢的影响.结果表明：饱食后,5个温度梯度组溪红点鲑幼鱼的耗氧率和排氨率均迅速上升,达最大值后缓慢下降,并逐渐恢复到初始水平;饱食状态下,溪红点鲑幼鱼耗氧率（OR）和排氨率（NR）与温度（t）的回归方程分别为OR=-0.0601t⁴+2.5542t³-39.256t²+276.26t-598.75(n=650,R²=1,4.5 ℃4+0.0826t³-1.2318t²+8.6186t-18.838(n=650,R²=1,4.5 ℃0.9738(n=650,R²=0.9974,4.5 ℃1.0896( n=650,R²=0.9977,4.5 ℃相似文献   

盐度对大麻哈鱼幼鱼存活率、鳃ATP酶活力及其组织结构的影响

为研究不同盐度对大麻哈鱼幼鱼存活率、鳃ATP酶活力及其组织结构的影响, 试验共设置4个盐度组(S0、S8、S16、S24), 试验周期42d, 解剖取鱼鳃测定ATP酶活力, 并运用组织切片及扫描电镜技术观察其鳃组织结构的变化。结果显示: S8和S16组大麻哈鱼幼鱼存活率最高, 均达到98.89%, S0组存活率为94.45%, 而S24组存活率最低, 为83.34%。随着盐度的升高, 大麻哈鱼幼鱼鳃组织Na+/K+-ATP和Ca2+/Mg2+-ATP酶活力均呈现出先升高后下降的趋势且酶活力最高的均为S8组、最低的为S24组。鳃丝宽度随盐度升高逐渐增大且各组之间呈现出显著性差异(P<0.05), 而鳃小片长度和宽度均随盐度升高逐渐减小。扫描电镜结果表明随着盐度的升高线粒体丰富细胞数量逐渐增多、顶膜变小且微绒毛消失; 同S0组相比, S8组和S16组鳃丝表面扁平上皮细胞之间的轮廓更加清楚且环形微脊条纹清晰, 而S24组鳃丝表面扁平上皮细胞之间界限模糊, 环形微脊间有融合或间断情况; 鳃小片底部扁平上皮细胞表层结构由清晰逐渐变得混乱、气孔数量逐渐减少且孔径变小。因此推测大麻哈鱼幼鱼在降海阶段适宜的盐度生存范围可能介于8‰—16‰, 具体有待进一步研究。     

Salinity effects on oxygen consumption, gill Na+, K+-ATPase and ion regulation in juvenile coho salmon

The metabolic response of juvenile coho salmon Oncorhynchus kisutch to different salinities was examined, using whole-animal oxygen consumption rates and gill Na⁺, K⁺-ATPase activities as indicators of osmoregulatory energetics. Coho salmon smolts were acclimated to fresh water (FW), isosmotic salinity (ISO, 10‰) and sea water (SW, 28‰) and were sampled for up to 6 weeks for plasma levels of cortisol, glucose and ions (Na⁺, K⁺, Cl⁻), gill Na⁺, K⁺-ATPase activity and oxygen consumption rates. Following an initial adjustment period, plasma constituents in SW fish returned to near-FW values, indicating that the fish were acclimated to SW by day 21. Gill Na⁺, K⁺-ATPase activities on days 21 and 42 were lowest in ISO, higher in FW and highest in SW. This result is consistent with the idea that less energy would be required to maintain ion balance in an isosmotic environment, where the ionic gradients between extracellular fluid and water would be minimal. Oxygen consumption rates of swimming fish (1 body length s⁻¹), however, did not differ significantly between the three test salinities after 6 weeks. The results of this study suggest that the metabolic response of juvenile salmonids to changes in salinity is dependent on life-history stage (e.g. fry v . smolt), and that oxygen consumption rates do not necessarily reflect osmoregulatory costs.     

Functional response of juvenile pink and chum salmon: effects of consumer size and two types of zooplankton prey

Feeding rate experiments were conducted for pink salmon Oncorhynchus gorbuscha fry [mean fork length ( L _F) 39 mm], juveniles (103–104 mm L _F) and juvenile chum salmon Oncorhynchus keta (106–107 mm L _F). Fishes were presented with small copepod ( Tisbi sp.) or larger mysid shrimp ( Mysidopsis bahia ) prey at varying densities ranging from 1 to 235 prey l⁻¹ in feeding rate experiments conducted at water temperatures ranging from 10·5 to 12·0° C under high light levels and low turbidity conditions. Juvenile pink and chum salmon demonstrated a type II functional response to mysid and copepod prey. Mysid prey was readily selected by both species whereas the smaller bodied copepod prey was not. When offered copepods, pink salmon fry fed at a higher maximum consumption rate (2·5 copepods min⁻¹) than larger juvenile pink salmon (0·4 copepods min⁻¹), whereas larger juvenile chum salmon exhibited the highest feeding rate (3·8 copepods min⁻¹). When feeding on mysids, the maximum feeding rate for larger juvenile pink (12·3 mysids min⁻¹) and chum (11·5 mysids min⁻¹) salmon were similar in magnitude, and higher than feeding rates on copepods. Functional response models parameterized for specific sizes of juvenile salmon and zooplankton prey provide an important tool for linking feeding rates to ambient foraging conditions in marine environments, and can enable mechanistic predictions for how feeding and growth should respond to spatial-temporal variability in biological and physical conditions during early marine life stages.     

Formation of the enveloping layer of the chum salmon egg in isotonic salt solutions

After stimulation in a hypotonic solution (9.4 mOsm kg⁻¹), inseminated eggs of the chum salmon Oncorhynchus keta initiate cleavages in isotonic salmon Ringer's solution (267.3 mOsm kg⁻¹) containing 3.2 mM Ca²⁺ ions. Blastomeres of these eggs, however, separate from each other and the enveloping layer is not observed at the blastula stage. An increase in external divalent cations rescues the separation; the concentration of CaCl₂ in the external medium should be 25 mM or more to induce close contact of blastomeres and the formation of an enveloping layer in isotonic salt solutions. The effectiveness of Ca²⁺ ions can be substituted by Mg²⁺, Sr²⁺ and Zn²⁺ ions; the same results are obtained in isotonic MgCl₂ and SrCl₂ solutions (100 mM) or in isotonic salmon Ringer's solution containing Zn ions (6.2 mM). The close contact of blastomeres and the formation of an enveloping layer are also observed in a low Ca²⁺ concentration (< 0.1 mM) in a hypotonic salt solution (9.4 mOsm kg⁻¹). The Ca²⁺ level in the external medium to induce the enveloping layer formation seems to be correlated with the salinity of the incubation medium. It is suggested that adhesion molecules on the surface of blastomeres in the chum salmon eggs are different in properties from those found in sea urchin and other fish species.     

Seagrass-salinity interactions: Physiological mechanisms used by submersed marine angiosperms for a life at sea

Due to the nature of coastal and estuarine systems, seagrasses must be able to tolerate short-term salinity fluctuations including both hyposaline and hypersaline conditions. Salt tolerance can be achieved, in part, through vacuolar ion sequestering (mostly Na⁺, K⁺, and Cl⁻) and cytosolic osmolyte accumulation (K⁺ and organic osmolytes), with differences in cellular ion levels attributed to selective ion flux and ion partitioning between the cytoplasm and vacuole (with lower cytoplasmic-to-vacuolar ratios favoring higher cellular Na⁺ concentrations). The hydrophilic nature of organic compounds such as organic acids, soluble carbohydrates, and free amino acids allow them to serve as osmoprotectants and low-molecular-weight chaperones which diminishes the inhibitory effects of potentially harmful ions on metabolic processes. Nevertheless, some carbohydrate studies on seagrasses have shown decreased soluble sugar content with increased salinities. During salt stress, carbohydrates are likely converted to other organic compounds that would better facilitate osmotic adjustment in these plants. This is further supported by observed decreases in sucrose-P synthase (a key enzyme involved in sucrose synthesis) activities in seagrass exposed to higher salinities. While modifications in ion flux and organic solute levels often follow changes in environmental salinities, these adjustments are relatively slow (hours to days). Therefore, the initial response to sudden salinity change will include rapid alterations in turgor pressure driven by water flux in the direction of the osmotic gradient. The rate of water movement depends largely on the hydraulic conductivity of the plasmalemma and the elastic properties of the cell wall (bulk elastic modulus; Є). Observations on cell wall elasticity indicate that some seagrasses maintain fairly rigid walls (high Є values), thereby limiting the amount of water influx during hypoosmotic stress. Although high Є would be beneficial to open-water coastal plants living in relatively stable saline environments, in estuaries where salinities fluctuate considerably over shorter intervals, high Є could promote flaccid cells with no turgor pressure during hyperosmotic conditions. Hypo- and hyperosmotic conditions also inhibit photosynthesis in seagrasses. Decreases in photosynthesis have been attributed to declines in chlorophyll content, changes in chloroplast ultrastructure, disruptions of electron flow through photosystems, and inhibitions of key photosynthetic enzymes. The uptake of nutrients can also be strongly influenced by salinity. High affinity Na⁺-dependent nutrient transport systems (for NO₃⁻, H₂PO₄⁻, and HPO₄⁻²) which benefit from the inwardly driving force for Na⁺ have been observed in seagrasses. Nitrate reductase, the key enzyme involved in nitrate reduction/ assimilation, also has elevated activities at higher salinities which would agree with Na⁺-dependent NO₃⁻ transport. While our basic understanding of how seagrasses survive in saline environments is increasing, it still lags well behind marine algae and terrestrial halophytes. It is likely that further investigations will reveal unique physiological adaptations that have not been observed in other plants.     

外源Sr2+在大麻哈鱼胚胎耳石上的沉积

为探明外源Sr²⁺在大麻哈鱼耳石上的沉积状况,本研究利用电子显微探针技术(EPMA)对大麻哈鱼发眼卵后期胚胎进行50、100、200、400 mg·L^-1Sr²⁺ 48 h浸染试验,经12和100 d暂养后检测其在耳石上的沉积.结果表明:不同浓度Sr^2+均在大麻哈鱼耳石上产生明显的深红色标记环.同一剂量组锶峰区均值和极值不稳定,但最小锶峰极值也能达到对照组水平的35.1倍,整体上锶峰随浸染浓度增加而增大.经100 d暂养后,锶峰没有减弱迹象.检测结果还表明,锶在大麻哈鱼耳石上的沉积是逐渐进行的,有明显的滞后现象,高峰后能恢复到正常水平.这些特点符合对放流标记技术的要求,表明可以利用外源Sr^2+对大麻哈鱼耳石进行标记.     

外源Sr2+在大麻哈鱼胚胎耳石上的沉积

为探明外源Sr²⁺在大麻哈鱼耳石上的沉积状况,本研究利用电子显微探针技术(EPMA)对大麻哈鱼发眼卵后期胚胎进行50、100、200、400 mg·L^-1Sr²⁺ 48 h浸染试验,经12和100 d暂养后检测其在耳石上的沉积.结果表明:不同浓度Sr^2+均在大麻哈鱼耳石上产生明显的深红色标记环.同一剂量组锶峰区均值和极值不稳定,但最小锶峰极值也能达到对照组水平的35.1倍,整体上锶峰随浸染浓度增加而增大.经100 d暂养后,锶峰没有减弱迹象.检测结果还表明,锶在大麻哈鱼耳石上的沉积是逐渐进行的,有明显的滞后现象,高峰后能恢复到正常水平.这些特点符合对放流标记技术的要求,表明可以利用外源Sr^2+对大麻哈鱼耳石进行标记.