不同条件下鲤鱼鳃部对高岭土颗粒吸附态铜的吸收

在水相溶解态铜浓度和高岭土吸附态铜浓度保持不变,pH和高岭土粒径不同条件下,研究了鲤鱼鱼鳃对铜的吸收。结果表明在本研究范围内,吸附态铜的存在增加了鱼鳃吸收。鳃对铜的吸收随pH增加而递增,随高岭土粒径减少而递增。利用MINTEQA2软件分析了不同实验条件下鱼鳃微环境中铜的形态分布特征,对吸附态铜可能的生物有效性机制进行了说明。     

pH对鲤鳃部微环境铜形态的影响

利用Playle等设计的装置研究了不同pH条件及不同的铜暴露水平下鲤鳃部微环境pH值和粘液分泌量的变化,在此基础上用化学平衡计算方法探讨鱼鳃微环境中铜形态的变化。结果表明,在特定的pH和铜浓度范围内,鱼鳃微环境平衡pH略低于7,鱼鳃粘液分泌量随铜暴露水平提高而增加,与此同时,虽然CO2分泌量有所增加,没有观察到微环境pH随铜暴露量的变化。pH的升高,导致水相优势的游离态铜让位给羟基络合铜,粘液络合态铜的分额逐渭降低,但不会改变其络合当量与条件稳定络合常数。由于鱼鳃微环境对pH改变的调节作用,铜的形态分布变化幅度低于外部环境。     

鲤鱼鳃部微环境的pH特征及其对吸附态铜的解吸影响

研究了不同pH条件下鲤鱼（Cyprinus carpio)鳃部微环境pH及CO2的变化情况以及鳃部微环境出水对水铝矿吸附态铜的淋洗效率,结果表明,鱼鳃微环境的平衡pH为8.0,出外环境pH低于或高于该值时,鱼鳃生理作用可以起到缓冲作用,造成鳃部微环境于外环境之间高达0.4个pH单位的差别,CO2含量也表现出相似的变化规律,在碱性条件下,鱼鳃微环境出水对吸附态铜的洗脱效应显著高于pH值相对较高的外环境水。     

铜鱼寄生三代虫一新种的记述

本文报道我国长江中游铜鱼鳃部寄生的三代虫一新种,即:铜鱼三代虫(新种)Gyrodactylus coreiusisp.nov.,新种的形态特征及其与相近种之间的差别在文中进行了描述和比较。     

久效磷对美国红鱼鳃Na^＋／K^＋-ATP酶活性和超显微结构的影响

经不同试验浓度的久效磷(0．25、0．5、1．0和2．0mg·L^-1)处理美国红鱼4d后,分别对鱼鳃Na^+／K^+—ATP酶活性和氯细胞密度进行了测定和计数,并观察了鱼鳃组织显微结构和超微结构的变化。结果表明,低浓度久效磷(0．25mg·L^-1)处理可以诱导鱼鳃氯细胞大量增生,Na^+／K^+—ATP酶活性增强,随着试验浓度的增加,久效磷对鳃组织的损伤越来越重,Na^+／K^+—ATP酶活性逐渐降低;久效磷对鱼鳃显微结构的损伤表现为鳃小片上皮细胞水肿、脱离。鳃小片基部粘连。鳃小片上皮细胞角质化;超微结构变化主要为内质网、线粒体、微小管和核膜的水肿及部分溶解,这种损伤表现为由细胞膜到细胞核的动态过程。     

黄颡鱼鳃部寄生单殖吸虫和鳋类的空间分布特点

研究了黄颡鱼Pelteobagrus fulvidraco(Richardson)鳃部的寄生单殖吸虫(Monogeneans)和鳋类(Copepods)的空间分布特点.寄生于黄颡鱼鳃部的单殖吸虫和鳋类在两侧鳃上的感染强度及其差异表明,两种寄生虫对于鳃片的左右位置没有明显的选择性;在黄颡鱼四鳃间的分布存在极显著的差异(PP<0.01);在鳃片的各区均存在选择性;对鳃丝的各分段也均有极显著的选择性.       

镉对黄颡鱼鳃线粒体结构和能量代谢的影响

采用室内模拟方法,研究了重金属镉对黄颡鱼[Pelteobagrus fulvidraco (Richardson)]鳃线粒体结构和能量代谢的影响及其作用机理.结果表明,50 μg·L^-1组黄颡鱼鳃线粒体结构未受损,且各项测定指标与对照组无显著差异(P＞0.05);500 μg·L^-1组黄颡鱼鳃线粒体严重受损,除LD、MDA、ADP、AMP和血浆K⁺含量显著高于对照组外,其余检测指标均显著低于对照组(P＜0.05).高浓度镉短期暴露将降低鱼鳃线粒体SOD活性而导致线粒体氧化损伤,同时抑制PFK和ATP酶活性, 影响鳃的能量供应和利用,最终降低鳃血浆渗透压和离子浓度调节能力可能是其毒性机理之一.     

黄斑篮子鱼和金钱鱼鳃的扫描电镜观察

对两种鲈形目鱼类黄斑篮子鱼(Siganus oramin)和金钱鱼(Scatophagus argus)的鳃结构进行扫描电镜观察。结果表明,黄斑篮子鱼和金钱鱼鳃的表面结构及微细结构与其他硬骨鱼类基本相似,鳃丝表面都具有规则或不规则分布的环形微嵴、沟、坑、孔等结构。黄斑篮子鱼的鳃片中部鳃丝表皮有大量凸起,而端部鳃丝表皮的凹凸程度明显较低,黄斑篮子鱼的鳃小片高度较金钱鱼鳃小片高。黄斑篮子鱼和金钱鱼鳃上皮的扁平上皮细胞、氯细胞和黏液细胞的形态结构及数量分布存在细微的差异。黄斑篮子鱼鳃片鳃丝的端部和中部表面有黏液细胞,金钱鱼鳃丝表面的黏液细胞很难观察到,与大多数淡水鱼类相似。黄斑篮子鱼鳃丝表面分布的氯细胞数量多于金钱鱼,这可能与两种鱼生活环境、生活习性的长期演变相关。     

过量铜对4种外生菌根真菌的生长、碳氮和铜积累的影响

为了了解外生菌根真菌在过量铜胁迫下的生长和物质积累特点,揭示外生菌根真菌对过量铜胁迫的抵抗能力,研究了四种外生菌根真菌—美味牛肝菌(Boletus edulis)、铆钉菇(Gomphidius viscidus)、厚环乳牛肝菌(Suillus grevillei)和红绒盖牛肝(Xerocomus chrysenteron)在过量铜胁迫条件下菌丝中铜积累量、菌丝生长特性以及碳氮积累速率。四种测试菌种菌丝中的铜积累量,随营养液中铜浓度的增加而增加,在46mg/L铜培养基下生长15d,四种菌种菌丝内铜浓度分别是对照的40～60倍。B.edulis和X.chrysenteron菌丝中铜浓度与培养基中铜浓度呈直线相关,S.grevillei和G.viscidus为指数相关。菌丝在铜胁迫下依然呈S曲线增长,但初始生长推迟,指数增长期比对照晚1～2d。菌丝生物量和碳氮积累随铜浓度增加而显著降低。综合所有试验结果显示,四种测试菌种对过量铜的抗性强度为：B.edulis＞G.viscidus＞S.grevillei＞X.chrysenteron。     

Hg2+在中华绒螯蟹幼蟹鳃内的积累及其对组织结构的影响

采用生态学单因子梯度实验,研究不同浓度汞(Hg2 )的水环境中中华绒螯蟹(Eriocheir sinensis)幼蟹鳃内汞积累情况及对鳃组织结构的影响。结果表明,中华绒螯蟹幼蟹的鳃能够从水环境中迅速积累汞,Hg2 浓度为10、50、100μg/L组的水环境中幼蟹鳃内汞含量分别为4.56、25.53、46.51μg/g干重,均显著高于对照组幼蟹鳃内汞含量1.68μg/g干重(P<0.05);水环境Hg2 浓度为200、300μg/L组的幼蟹鳃内汞含量达到了183.75和283.36μg/g干重,对水体Hg2 蓄积倍数达到了910.35和939.60。光镜观察低浓度组汞能够诱导鳃组织结构发生变化,如上皮细胞肿胀、鳃叶厚度增加、端部膨胀等;高浓度组则会导致鳃叶上皮细胞崩解,鳃组织结构完全破坏。以统计学方法分析了鳃内汞含量同水体汞浓度的相关性,结果表明,两者之间存在明显的相关性,并能够在组织形态上有所体现。鳃是中华绒螯蟹最容易接触水体Hg2 的器官,同时也是蓄积汞的主要器官之一,水体高浓度的Hg2 能够对鳃的组织结构造成明显的破坏,严重影响幼蟹存活率。     

Estimation of conditional stability constant for copper binding to fish gill surface with consideration of chemistry of the fish gill microenvironment

Binding-site concentration and conditional stability constants for copper and fish gill surface interactions were calculated based on the data from the literature. Six scenarios were modeled by including or excluding pH and alkalinity differences between the fish gill microenvironment and the bulk solution and the presence of free mucus in the calculation. We demonstrate that changes in pH or alkalinity, or both, for model input had only a slight influence on the calculated results because of the small difference in pH and alkalinity between the gill microenvironment and the bulk solution under the specific experimental conditions. Inclusion of free mucus in the model, however, led to a large change in the final results. For example, with consideration of free mucus and changes in pH and alkalinity in the model, the calculated site concentration and the stability constant were 0.022 micromol/g wet tissue and log K=8.77, respectively, compared to 0.026 micromol/g wet tissue with log K=7.78 without free mucus and pH/alkalinity change.     

Studies on the fish gill microclimate

Summary An isolated and perfused fish gill filament preparation has been developed to facilitate investigations on the fish gill microclimate. Measurements have been made of the concentration of sodium at the lamellar surface and in the mixed-exit water, and of the maximum interlamellar velocity. When the external water has a sodium concentration of 0.10 mmol · 1^-1, water at the gill surface has a mean sodium concentration of 0.146 mmol · 1^-1. Mixed-exit water, 50 m behind the perfused filament, has a mean sodium concentration of 0.118 mmol · 1^-1. When the water flowing over the filament has a maximum velocity of 18 cm · s^-1, the maximum velocity between secondary lamellae is 1.5 cm · s^-1. These measurements have been used to support the development of a velocity-modified diffusion model which describes ion movement in the interlamellar space. The analysis and observations on the preparation suggest that substantial unstirred layers do not exist at the lamellar surfaces in this preparation. Simple diffusion to and from the tissue surfaces, in conjunction with parabolic velocity profiles within the interlamellar spaces adequately explain net sodium movements.     

Sensing and transfer of respiratory gases at the fish gill

The gill is both a site of gas transfer and an important location of chemoreception or gas sensing in fish. While often considered separately, these two processes are clearly intricately related because the gases that are transferred between the ventilatory water and blood at the gill are simultaneously sensed by chemoreceptors on, and within, the gill. Modulation of chemoreceptor discharge in response to changes in O(2) and CO(2) levels, in turn, is believed to initiate a series of coordinated cardiorespiratory reflexes aimed at optimising branchial gas transfer. The past decade has yielded numerous advances in terms of our understanding of gas transfer and gas sensing at the fish gill, particularly concerning the transfer and sensing of carbon dioxide. In addition, recent research has moved from striving to construct a single model that covers all fish species, to recognition of the considerable inter-specific variation that exists with respect to the mechanics of gas transfer and the cardiorespiratory responses of fish to changes in O(2) and CO(2) levels. The following review attempts to integrate gas transfer and gas sensing at the fish gill by exploring recent advances in these areas.     

The effect of acidity on gill variations in the aquatic air-breathing fish,Trichogaster lalius

Climate change affects organisms that inhabit not only in aerial but also in aquatic environments by making water more hypoxic and acidic. In the past, we evaluated morphological and functional variations in the gills of 12 species of aquatic air-breathing fishes. The aim of the present study is to examine the degree of gill modification in the aquatic air-breathing fish, Trichogaster lalius, in response to acidic stress. This provides a link between the ecological and physiological studies. We evaluated the changes in morphology and function of the gills, labyrinth organ, and kidney when the fish were subjected to acidic water and deionized water (DW). In the first experiment, fish were sampled at 1, 2, 4, and 7 days after acidic treatment. Apparent morphological modification was observed on day 4 and recovery was noted on day 7. Protein expression and enzyme activity of vacuolar-type H⁺-ATPase (VHA) and the protein expression of the proliferating cell nuclear antigen (PCNA) of the 1st and 4th gill arches both increased in the 4-day and 7-day acidic groups while the enzyme activity of Na⁺/K⁺-ATPase (NKA) decreased. In the second experiment, fish were tested for changes in the 1st and 4th gill arches and kidney after exposure to DW and acidic water for 4 days. The gill structure of the fish in the DW was not different from that of the control group (fresh water). The protein expression and enzyme activity of the VHA of the 1st and 4th gill arches increased in both the DW and acidic groups for 4 days. We found a decrease in the protein expression of NKA in the kidney and in the enzyme activity of NKA in the 1st and 4th gill arches in the DW and acidic groups. From these results, we suggest that T. lalius exhibited significantly different ionic regulation and acid-base regulatory abilities in the DW and acidic groups in the 1st and 4th gill arches and kidney. The responses of the gills in T. lalius were different from those fish that show apparent morphological variations between the 1st and 4th gill arches.     

Susceptibility of male and female medaka (Oryzias latipes) fish to spontaneous and X-ray induced micronucleus formation in gill cells

The frequency of micronucleated cells (MNCs) was measured in acridine-orange (AO) stained RNA-rich gill cells from male and female medaka (Oryzias latipes) fish of known body weight. Spontaneous MNC frequencies were not significantly correlated with body weight, despite the fact that the heaviest of the 30 fish used outweighed the lightest by a factor of 3. Average MNC frequencies were identical in males and females at 0.8 per thousand. An X-ray dose of 4 Gy increased the frequency of MNCs over the spontaneous level in all 30 of the fish used, reaching a level of 7.2 per thousand on average when assayed 24 h after exposure. In X-ray treated fish, MNC frequency and body weight were not significantly correlated, nor was there any difference between the sexes. These and other results support our primary conclusion that AO-staining is suitable for the medaka micronucleus assay in gill cells, and indicate that male and female medaka fish are similarly and size-independently susceptible to both spontaneous and X-ray induced micronucleus formation in gill cells.     

Intracellular vesicular trafficking in the gill epithelium of urea-excreting fish

Most teleost fish are ammoniotelic, and relatively few are ureotelic, in which the majority of nitrogenous waste is excreted as urea. This study aimed to determine whether the gill ultrastructure of ureotelic fish might have specific, unique characteristics compared with ammoniotelic fish. The gill morphology was studied in three closely related species of the family Batrachoididae: Opsanus beta, the gulf toadfish; Opsanus tau, the oyster toadfish; and Porichthys notatus, the plainfin midshipman, because prior studies have demonstrated that the two former species are ureotelic and excrete urea in unique, short daily pulses, whereas the latter is ammoniotelic. Ultrastructural studies demonstrated significant trafficking of dense-cored vesicles (50-200 nm) between the Golgi apparatus and the apical membrane of epithelial cells surrounding gill filaments and lamellae in these two Opsanus spp. The material constituting the core of these vesicles was intensely stained by lead salt and was unloaded externally when vesicles contacted the apical membrane. Another characteristic of these urea-secreting fish was the presence of numerous large, black-stained lysosomes, which contained cored vesicles, suggesting a second destination for the dense-cored vesicles. As a working hypothesis, the present data suggest that the urea-transporter protein, recently found in toadfish gills, is inserted in the vesicle. Subsequently, it could serve to either sequester cytosolic urea that ultimately is secreted into the water after contact of these vesicles with the pavement cell apical membrane, or it could allow facilitated diffusion of urea across the plasma membrane following insertion into the membrane. As further comparative evidence, the ammoniotelic P. notatus exhibited neither the vesicular trafficking nor the population of lysosomes both found in Opsanus spp.     

Vascular anatomy of the fish gill

The fish gill is the most physiologically diversified vertebrate organ, and its vasculature the most intricate. Application of vascular corrosion techniques that couple high-fidelity resins, such as methyl methacrylate, with scanning electron microscopy yields three-dimensional replicas of the microcirculation that have fostered a better appreciate gill perfusion pathways. This is the focus of the present review. Three vascular networks can be identified within the gill filament. The arterioarterial (respiratory) pathway consists of the lamellae and afferent and efferent segments of the branchial and filamental arteries and lamellar arterioles. The body of the filament contains two post-lamellar pathways: the interlamellar and nutrient. The interlamellar system is an extensive ladder-like network of thin-walled, highly distensible vessels that traverses the filament between, and parallel to, the lamellae and continues around the afferent and efferent borders of the filament. Interlamellar vessels are supplied by short, narrow-bore feeder vessels from the medial wall of the efferent filamental artery. A myriad of narrow-bore, tortuous arterioles arise from the basal efferent filamental artery and efferent branchial artery and anastomose to form the nutrient circulation of the arch and filament. In the filament body, nutrient capillaries and interlamellar vessels are often closely associated, and the former may ultimately drain into the latter. Many of the anatomical characteristics of interlamellar vessels are strikingly similar to those of mammalian lymphatic capillaries, with the exception that interlamellar vessels are directly fed by arteriovenous-like anastomoses. It is likely that gill interlamellar and mammalian lymphatics are physiologically, if not embryologically, equivalent.     

EROD activity in gill filaments of anadromous and marine fish as a biomarker of dioxin-like pollutants

The applicability of a gill filament-based ethoxyresorufin O-deethylase (EROD) assay, originally developed in rainbow trout, was examined in Atlantic salmon (Salmo salar), Arctic charr (Salvelinus alpinus), Atlantic cod (Gadus morhua), saithe (Pollachius virens) and spotted wolffish (Anarhichas minor). All species but spotted wolffish showed strong EROD induction in tip pieces of gill filaments following 48 h of exposure to waterborne beta-naphthoflavone. Atlantic salmon parr, smolts held in freshwater and smolts transferred to seawater showed EROD induction of similar magnitude. Arctic charr, differing 11-fold in body weight, showed similar EROD activities as expressed per gill filament tip. Laboratory exposure of saithe to water and sediments collected at polluted sites, resulted in strong EROD induction. In conclusion, the gill filament assay seems useful for monitoring exposure to aryl hydrocarbon receptor agonists in various species. Furthermore, smoltification status, water salinity and body size proved to have minor influence on gill filament EROD activity. However, the results in spotted wolffish show that some species may be less suitable for monitoring using the gill assay. Assessment of gill filament EROD activity in fish exposed to polluted water and sediments in the laboratory proved to be an easy and cost-effective way to survey pollution with dioxin-like chemicals.     

Studies on the extent of gill surface in a fresh water cat-fish Bagarius bagarius (Ham.).

The total gill area of the fish ranges from 37,537 to 56,551 lamellae. The number of lamellae per mm of the gill filament and area of lamellae knowing the respiratory gill area, the gill area per g of body weight and per cm3 of body volume were calculated to correlate the variation in gill surface area per unit weight and volume of the fish. The fish can survive for quite long out of water as the lamallae are spaced wide apart and do not adhere together.