Histological alterations in gills of shrimp Litopenaeus vannamei in low‐salinity waters under different stocking densities: Potential relationship with nitrogen compounds

Two experimental modules with different stocking densities (M1 = 70 and M2 = 120 shrimp /m²) were examined weekly over a culture cycle in tanks with low‐salinity water (1.9 g/L) and zero water exchange. Results showed survival rates of 87.7 and 11.9% in M1 and M2, respectively. Water temperature, pH, dissolved oxygen, electrical conductivity and chlorophyll a were not significantly (p > .05) different between modules. In contrast, the concentrations of nitrogen compounds were significantly (p < .05) different between modules, except nitrite‐N (M2 were 2.31 ± 1.38 mg/L N‐TAN, 0.18 ± 0.49 mg/L N‐NO₂^? and 6.83 ± 6.52 mg/L N‐NO₃^?; in M1: 0.97 ± 0.73 mg/L N‐TAN, 0.05 ± 0.21 mg/L N‐NO₂^? and 0.63 ± 0.70 mg/L N‐NO₃^?). When waters of both modules reached higher levels of ammonia and nitrite, histological alterations were observed in gills. The histological alterations index (HAI) was higher in M2 (5‐112) than in M1 (2‐22).     

Pathological effects of Cichlidogyrus philander Douëllou, 1993 (Monogenea,Ancyrocephalidae) on the gills of Pseudocrenilabrus philander (Weber, 1897) (Cichlidae)

Histopathological changes of Cichlidogyrus philander Douëllou, 1993 on the gills of Pseudocrenilabrus philander (Weber, 1897) were studied using light and scanning electron microscopy. Observations revealed that C. philander attaches to its host by alternating the prohaptor (for temporary attachment or feeding) or haptor (using haptoral parts for firm and secured attachment). The sharp terminal ends of the anchors are inserted basally into the gill lamella, between two adjacent secondary gill lamellae and the marginal hooklets assist by superficially penetrating, holding and lifting epithelial tissue in the proximal region of the secondary gill lamella. The attachment of C. philander resulted in compression, rupturing of the interlamellar epithelium, change in the organization of epithelial cells in both primary and secondary gill lamella, displacement of the extracellular cartilaginous matrix, occasional rupturing of blood vessels and erythrocytes and some cells becoming ill-defined. At the site of attachment, the host response comprises of hyperplasia, increase in the number of mucous cells and infiltration with neutrophils. It was concluded that the effect of C. philander is mild in natural conditions.     

热胁迫对白梭吻鲈鳃组织结构及抗氧化指标的影响

温度是导致鱼类生理变化的最重要的环境因素之一。热应激导致氧化应激，破坏抗氧化防御系统，并导致脂质和组织病理学的损害。白梭吻鲈(Sander lucioperca)属于亚冷水性鱼类，最适生长水温20～24℃。近年来，由于夏季气温极高，中国池塘出现了大量的白梭吻鲈死亡，白梭吻鲈的水产养殖业一直面临着高温的严峻挑战。鱼鳃参与鱼类许多重要功能，如呼吸，渗透调节和排泄，与外部环境保持密切接触，对水质变化特别敏感。为探究热胁迫对白梭吻鲈鳃组织结构及抗氧化指标的影响，将100尾鱼暴露于28℃，31℃，34℃，36℃热应激2h，以23℃作为对照组。收集鳃用于石蜡切片制备，并将苏木精伊红（HE）染色用于一般组织学观察。测定超氧化歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPX）活性和丙二醛（MDA）等抗氧化指标。结果显示，28 ℃组鳃小片发生充血，31 ℃组部分鳃小片末端卷曲变形、上皮细胞水肿，34 ℃组鳃小片变形加重，且有少量融合，上皮细胞水肿加重、明显隆起，鳃小片之间粘液细胞肥大、增生，36 ℃组相邻鳃小片大量融合且严重变形，卷曲混乱排列，大量上皮细胞坏死、脱落，鳃丝粘液细胞增生、肥大；随着胁迫温度升高，鳃中SOD、CAT、GPX、MDA均整体呈现先升高、后降低的变化趋势，且在36℃时显著下降。这表明在热应激后，鱼体内ROS增加，脂质过氧化增加。由于体内产生大量的ROS和H2O2，机体也增加了GPX和CAT的合成。当暴露在36℃时，胁迫强度超过白梭吻鲈的适应能力，抗氧化系统功能无法正常进行。表明热胁迫对白梭吻鲈鳃组织有损伤，且随着热胁迫温度的升高，其鳃受损情况越发严重。     

Swimming performance,whole body ions,and gill Al accumulation during acclimation to sublethal aluminium in juvenile rainbow trout (Oncorhynchus mykiss)

Juvenile rainbow trout (2–5 g) were chronically exposed (for 22 days) to acidified softwater (Ca²⁺ = 25 Eq/l, pH 5.2) in the presence or absence sublethal Al (30 g/l). Al-exposed fish (5.2/Al group) suffered 20% whole body Na⁺ and Cl^– losses and a 30% reduction in the maximum sustainable swimming speed (U_crit) over the initial 7 days. These disturbances were approximately 2 fold greater than those observed in the fish exposed to low pH alone (5.2/0 group). However, whole body ion levels were completely restored in the 5.2/Al fish by day 22, whereas they merely stabilized at a new reduced level in the 5.2/0 group. Increased resistance to acutely lethal Al (200 g/l at pH 5.2) was observed from day 17 onwards in the 5.2/Al fish. Despite this acclimation and recovery of whole body ions, U_crit remained significantly lower than in the 5.2/0 group throughout. Growth on a restricted diet of 1% body wt. /day was normal in the 5.2/0 group compared with controls maintained in pH 6.5 softwater, whereas 5.2/Al fish suffered a 50% reduction in growth rate on the same diet. The 5.2/Al fish accumulated large amounts of Al on the gills, reaching an initial peak after 4 days, followed by a decline at 7 days, and a secondary rise thereafter. Therefore acclimation and recovery of whole body ionic status was not associated with a reduction in the gill Al burden. Some of the metabolic costs of acclimation to Al, namely a continued impairment of swimming speed and growth, are discussed in light of the physiological and structural changes reported to occur at the gills.     

Oxygen uptake in the Antarctic teleost Pagothenia borchgrevinki. Limitations imposed by X-cell gill disease

Fish in a population of Pagothenia borchgrevinki in McMurdo Sound, Antarctica, are affected by a gill disease (X-cell disease) which causes tissue hyperplasia that results in a decreased gill surface area and an increased water/blood diffusion distance. P. borchgrevinki acquires 95% of its oxygen via the gills, but damage to the gills by X-cell disease did not affect this function. There was no compensatory shift to cutaneous respiration. X-cell disease reduced the ability for oxygen uptake at low ambient P_{O 2} and the decreased uptake was related to the extent of the disease. _{O 2} max was greatly reduced in X-cell affected fish and substantially reduced their aerobic potential. This effect may impair the ability of diseased fish to catch prey and avoid predators.     

姬松茸菌褶、担孢子及菌丝体微观形态观察

姬松茸（Agaricus brasiliensis）不仅营养丰富还具有很高的药用价值,是一种名贵的食药用菌,其产业发展前景广阔。但由于姬松茸种质资源匮乏,对姬松茸的遗传背景认识不足,阻碍了其杂交育种技术的发展,现有的种质资源难以满足实际生产需要。本研究以姬松茸J1菌株为实验材料,通过对姬松茸生殖相关结构进行微观形态观察,探究姬松茸相关的生物学特性。利用扫描电子显微镜和荧光显微镜观察姬松茸不同生长发育时期菌褶、担孢子和菌丝体微观形态特征。结果表明：桑葚期菌褶和菌髓处于发育阶段,菌褶片状物不明显;珊瑚期后能明显观察到菌褶片状物,相互平行排列,由菌髓和其两侧的子实层组成,排列紧密,厚度均匀,且着生少量担子,但菌髓呈不规则排列;成形期菌褶更为清晰、排列规整,内菌幕未破裂,菌褶间隙包含表面凸起排列的担孢子和杂乱的导管状细胞,导管状细胞紧密关联;成形期菌褶担子较为饱满,有褶皱,担子上着生有3个孢子梗或4个孢子梗,各担孢子之间有细小的连接丝。通过DAPI对担孢子核数进行染色观察,发现姬松茸大多数担孢子属于双核孢子,少量属于单核和无核孢子;通过DAPI对菌丝体细胞核进行染色观察,发现姬松茸菌丝体属于多核,有隔膜,但未见锁状联合。本研究明确了姬松茸不同生长发育时期的菌褶、担子、担孢子以及菌丝体的微观形态特征,丰富了姬松茸的生物学研究和生活史过程认识,为姬松茸杂交育种、担孢子交配型、遗传转化体系等研究奠定了基础。     

三唑磷对斑节对虾肝胰腺和鳃的氧化胁迫效应

采用半静态毒性实验方法测定了三唑磷（Triazophos,OP）对斑节对虾（Penaeusmonodon）的96hLC卯值,同时研究了低（0．3μg·L^-1）、中（0．5μg·L^-1）、高（1μg·L^-1）浓度OP胁迫1、3、7、14d和清水恢复7d后斑节对虾肝胰腺和鳃中超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GPx）、丙二醛（MDA）含量和总抗氧化能力（T—AOC）的变化趋势。结果表明：在胁迫期间SOD、GPx活性都受到了显著的诱导和抑制,呈一定的变化规律;MDA含量随胁迫时间延长显著升高。肝胰腺T—AOC在低浓度OP胁迫下呈升高-下降-升高的变化趋势,高浓度则显著下降;鳃T—AOC显著升高,而随胁迫时间延长,T—AOC显著降低。经清水恢复7d后,各浓度组肝胰腺SOD活性仍然显著低于空白组,MDA含量和T-AOC显著高于空白组。低浓度组鳃SOD、T—AOC显著高于空白组,MDA含量和中、高浓度SOD能恢复到正常水平,T—AOC则显著低于空白组。肝胰腺和鳃GPx活性变化情况相同,均为低、中浓度显著升高,高浓度显著下降。上述结果显示,0P对斑节对虾的抗氧化系统有显著的影响,且具有组织特异性,肝胰腺对OP较为敏感。斑节对虾对一定浓度OP所带来的氧化损伤具有一定的自我修复能力,但在短期内无法完全修复。     

丁香酚对鲤的麻醉作用

为测定丁香酚对鲤Cyprinus carpio Linnaeus的麻醉作用效果,将丁香酚溶于水配制成不同浓度溶液进行试验研究.结果表明,丁香酚对鲤有较强的麻醉作用,麻醉浓度比最常用的MS-222低,麻醉的最佳浓度为20mg·L-1、40mg·L-1,随丁香酚浓度从10～160mg·L-1逐渐升高,麻醉开始时间从18.25min逐渐缩短至0.21min,苏醒时间从0.52min延长至13.8min;鲤的鳃动次数从(44.5±1.54)次·min-1降至(8.4±0.60)次·min-1;空气中苏醒时间从2.06min延长至9.74min;耗氧量从(0.58±0.19)mg逐渐降低至(0.094±0.012)mg.     

亚慢性铜暴露对背角无齿蚌鳃抗氧化系统的影响

为探究淡水环境中铜(Copper, Cu)污染对背角无齿蚌(Anodonta woodiana)鳃抗氧化系统的影响,检测了Cu~(2+)(0.137、0.548、2.192 mg·L~(-1))暴露于背角无齿蚌7、14、21、28 d后,其鳃中超氧化物歧化酶(Superoxide dismutase,SOD)、过氧化氢酶(Catalase,CAT)、谷胱甘肽过氧化物酶(Glutathione peroxidase,GPx)和谷胱甘肽转硫酶(Glutathione-S-transferase,GST)的活性,还原型谷胱甘肽(Reduced glutathione,GSH)和丙二醛(Malondialdehyde,MDA)的含量及总抗氧化能力(Total antioxidant capacity,TAOC)的变化。结果显示:随着Cu~(2+)浓度的增加和暴露时间的延长,MDA含量逐渐上升,表现出明显的"剂量-效应"和"时间-效应"关系;抗氧化酶SOD、GPx和GST活性均被显著诱导(P0.05), CAT活性被显著抑制(P0.05),抗氧化剂GSH含量显著降低(P0.05);Cu~(2+)暴露14、21、28 d,T-AOC与对照组相比均显著升高(P0.05)。总体而言,背角无齿蚌鳃抗氧化系统在Cu~(2+)暴露下被激活,但是鳃组织器官仍然受到了氧化损伤。GPx、GST和GSH对Cu~(2+)暴露响应最为灵敏。     

Bacterial Populations of African Catfish,Clarias gariepinus (Burchell 1822) Cultured in Earthen Ponds

The aim of this study was to investigate the load and distribution patterns of the aerobic bacterial flora associated with pond water, sediments, gills, and intestines of healthy African catfish, Clarias gariepinus, cultured in Saudi Arabia. Counts of viable bacteria ranged from 7.9 ± 4.4 10³ to 4.3 ± 5.7 10⁴ colony forming units (cfu)/mL in water; 1.3 ± 2.7 10⁸ to 7.4 ± 4.6 10⁹ cfu/g in sediments; 8.7 ± 1.8 10⁶ to 6.6 ± 5.8 10⁷ cfu/g in gill filaments; and 8.8 ± 6.2 10⁸ to 4.3 ± 2.8 10¹⁰ cfu/g in intestines. The bacterial flora was predominantly comprised of gram-negative rods, accounting for 75% of the total isolated strains. Altogether, 11 bacterial species of 8 genera were identified: Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Staphylococcus sp., Corynebacterium urealyticum, and Vibrio vulnificus were the most common with the first three dominating (prevalence > 14%) in every population studied.