The effects of hypoxia,in vivo,on red blood cell β-adrenoceptors in the rainbow trout,Oncorhynchus mykiss

Rainbow trout, Oncorhynchus mykiss, were exposed to 48h of environmental hypoxia (water partial pressure of oxygen = 8.0 kPa) at either 5 or 15°C. Blood was sampled during hypoxia via a dorsal aorta cannula to measure arterial blood partial pressure of oxygen and plasma catecholamine concentrations. After 48h, the number (B_max) and dissociation constant (K_d) of red blood cell surface -adrenoceptors were determined using a radioligand-displacement binding assay. At 5°C, plasma catecholamine levels were elevated at 24h whereas at 15°C, levels were elevated at 48h. At either temperature, following 48h of hypoxia, there was no change in B_max or K_d of red blood cell surface -adrenoceptors, compared to normoxic control fish. This study demonstrates that chronic exposure to moderate hypoxia does not affect the number or affinity of cell surface -adrenoceptors on trout red blood cells.     

公路对天山马鹿（Cervus elaphus songaricus）种内遗传分化的影响

为研究公路对大型哺乳动物造成的影响,分别采集新疆省道110、203、303公路两侧的天山马鹿粪便样本,采用5个微卫星位点进行个体识别后利用Arlequin3．11进行遗传距离、基因多样性、杂合度等测定分析。结果表明：5个微卫星均具有很好的多态性,5地区中松树塘与寒气沟、白石头马鹿的遗传距离最远,松树塘马鹿的基因杂合度、基因型数量均最低;小西沟与白杨沟马鹿之间遗传距离为负值,其基因杂合度、基因型无显著性差异（P〉0．05）。说明公路对栖息地的分割状态不同,会导致种群的遗传情况改变。当公路仅深入栖息地没有将栖息地割裂时,公路两旁种群无差异;当栖息地被公路完全隔绝,则该栖息地内动物的基因杂合度、基因型数量降低;使用中的公路对临近种群的隔绝效果强于废弃旧公路。     

饲料中添加虾青素对红罗非鱼各组织类胡萝卜素含量和沉积率的影响

通过在饲料中添加不同含量虾青素,测定粉白、红斑、黑斑3种体色红罗非鱼各组织(皮肤、鳍、肌肉、眼球、鳃)类胡萝卜素含量的变化,分析不同虾青素含量对红罗非鱼不同组织类胡萝卜素含量的影响,从而推断类胡萝卜素在不同组织间的表达和沉积方式。结果显示,虾青素添加量为400 mg/kg时,红罗非鱼皮肤、鳍、肌肉、眼球和鳃中的类胡萝卜素含量与对照组相比均明显提高,体色明显改善,其中黑斑红罗非鱼鳃部类胡萝卜素沉积比对照组有显著提高(P0.05)。而当虾青素添加量为800 mg/kg时,粉白红罗非鱼鳍上和鳃部及黑斑红罗非鱼鳃部类胡萝卜素沉积比对照组有显著提高(P0.05),但3种体色红罗非鱼一些组织器官类胡萝卜素含量相对对照组及虾青素添加量为400 mg/kg时有所下降,红罗非鱼体色变化不明显。虾青素含量对红罗非鱼各组织类胡萝卜素总含量有显著影响(P0.01);而红罗非鱼体色对类胡萝卜素总含量影响不显著(P0.05);虾青素和体色交互作用对类胡萝卜素含量有较显著影响(P0.05)。聚类分析表明,类胡萝卜素在红罗非鱼的鳍中沉积率最高,其次为鳃,再次为眼球,皮肤和肌肉沉积率最低。     

Seasonal changes in sperm production and quality in the red porgy Pagrus pagrus (L.)

Cultured red porgy Pagrus pagrus (L.) males (n=6) were sampled every 2 weeks for milt, in order to monitor changes in sperm quality parameters during a whole spawning period. On 11 January 2001, 60% of the fish were spermiating, increasing to 100% in mid‐February and dropping to 30% by mid‐April. Sperm density showed a slight increasing trend, with mean values ranging between 8.6 and 23.7×10⁹ spermatozoa mL^?1. Sperm motility percentage exhibited a significant improvement during the spawning season (analysis of variance (anova ) P=0.0001). The duration of forward motility for the major part of the monitoring period ranged between 2 and 4 min. Red porgy spermatozoa maintained their viability for many days after whole storage of milt at 4°C. During the monitoring period there were significant changes in the mean duration of sperm survival after cold storage, ranging from 5 to 12 days. The total volume of expressible milt was maximal on 28 March, increasing from a mean value of 1.7 mL to 5.3 mL kg^?1. Milt production of captive‐reared red porgy does not appear to be limiting, when compared with the volume of expressible milt produced by other cultured marine fishes.     

Successful storage and transport of eggs of the white-clawed crayfish (Austropotamobius pallipes Lereboullet)

Embryonated eggs of theEuropean native white-clawed crayfish Austropotamobius pallipes Lereboullet weresubjected to three periods of storage usingpolystyrene boxes and, afterwards, artificiallyincubated. At the end of the longest storage(42 days) survival rate was 98.3%, with 65%developed to stage 2 juvenile. Differentstorage periods allowed the staggeredproduction of juvenile batches within a monthperiod. The same containers used for storagewere also suitable for transport.     

An intranuclear bacilliform virus associated with near extirpation of Austropotamobius pallipes Lereboullet from the Nant watershed in Ardéche, France

White-clawed crayfish, Austropotamobius pallipes, were endemic to the Nant watershed, Ardéche, France, until they were extirpated by epizootic mortality at the beginning of the twentieth century. A. pallipes were successfully reintroduced to the Nant watershed in the middle of the twentieth century. However, epizootic mortality was observed in the Nant watershed in the summer of 2000 during which time A. pallipes was extirpated from downstream regions. Dead and moribund crayfish were again detected in several episodes in summer 2001 and by October the range of A. pallipes was reduced to the headwaters of just one of the three streams in the watershed. Water quality for the watershed in summer 2001 was appropriate for crayfish habitation. Bacteriology and mycology on A. pallipes collected during several of the mortality episodes in 2001 failed to reveal a cause. However, histopathology revealed a high occurrence of intranuclear eosinophilic inclusions in hepatopancreatocytes of A. pallipes . The nuclei were hypertrophic and contained bacilliform virions consisting of a cylindrical nucleocapsid surrounded by a trilaminar envelope. Virions in section were approximately 63 × 258 nm and nucleocapsids were approximately 52 × 225 nm. It is unclear whether the intranuclear bacilliform virus was the cause of the mortality episodes or was a contributor to a disease complex involving one or several other undetected pathogens.     

Effects of in vitro exposure to ozone and/or hyperoxia on superoxide dismutase, catalase, glutathione and lipid peroxidation in red blood cells and plasma of rainbow trout, Oncorhynchus mykiss (Walbaum)

In aquaculture, ozone is used as a disinfectant. In its production, extensive amounts of oxygen are formed resulting in hyperoxic conditions in culture units. Both ozone and hyperoxia have the potential to be toxic via pro‐oxidant mechanisms and to activate antioxidant defence systems in cultured species. To eliminate systemic effects, blood of rainbow trout, Oncorhynchus mykiss (Walbaum), was exposed in vitro for 5 min to ozone/hyperoxia or hyperoxia, and changes in antioxidant defences and lipid peroxidation were measured after exposure. Ozone exposure caused severe damage in red blood cells (rbc) detected as increased lipid peroxidation and oxidized glutathione (GSSG) levels in both plasma and rbc. Oxygen exposure alone increased intracellular lipid peroxidation and GSSG levels 10 min after exposure and was not evident in the plasma at any time. Ozone, but not oxygen exposure, decreased reduced glutathione (GSH) levels in plasma, and the changes were negatively correlated with increased lipid peroxidation in rbc, indicating that extracellular GSH has a dynamic role in the protection of rbc from direct oxidation by ozone. Both ozone and hyperoxic conditions increased superoxide dismutase (SOD) activity in rbc 3 and 6 h after exposure. In contrast, catalase activity was only increased 10 min after oxygen exposure, suggesting other catalase activation mechanisms rather than enzyme induction. The recovery of lipid peroxidation and GSSG levels in rbc after hyperoxia, but not ozone exposure, indicated a capacity to defend against hyperoxia‐produced oxidative damage, but an overwhelming of antioxidant defences by ozone in rainbow trout rbc in vitro.     

Digestive enzyme activity of the red porgy (Pagrus pagrus, L.) during larval development under culture conditions

The ontogenic development of the main digestive enzymes (proteases, amylase and lipase) in the red porgy, Pagrus pagrus, larvae was assayed during the larval development. The green water technique was carried out for larval rearing and whole‐body homogenates were used for enzymatic assays in triplicate. Significant alterations in specific activities of all digestive enzymes measured during the period of this study were mostly related to metamorphosis and weaning. Trypsin‐ and chymotrypsin‐specific activities were first detected on day 3, together with opening of the mouth, and slightly increased until 25 days after hatching (DAH). After this period, the specific activities of these enzymes slightly decreased. Pepsin was first detected on day 28, concurrent with stomach formation, and a sharp increase was observed until 30 DAH. A slight decrease was measured from this date until the end of the experiment. Both amylase and lipase were measured for the first time on days 2 and 4 respectively, and the specific activities of these enzymes showed similar patterns during the first week of the study. Then, slight variations were observed until 30 DAH and while lipase‐specific activity declined, an increase in the specific activity of amylase was found until the end of the experiment. It is concluded that the variations observed in the specific activity of digestive enzymes were related to either metamorphosis, such as the formation of the stomach (28 DAH), or to changes in food composition. The profile of the developmental pattern of the main digestive enzymes detected in P. pagrus is similar to that described for other Sparid species.     

Presence and ontogeny of intestinal and pancreatic phospholipase A2-like proteins in the Red Sea bream,Pagrus major. An immunocytochemical study

We have studied the location and the ontogeny of the digestive enzyme, phospholipase A₂ (PLA₂) immunohistochemically in the adult and larvae/juvenile of the red sea breamPagrus major by using an antiserum against theNaja naja venom PLA₂. The antiserum reacts with at least one enzyme among the PLA₂s purified from the fish hepatopancreas or intestine. Although the reactivities were comparatively low, it labelled zymogen granules of the pancreatic acinar cells and secretory materials of certain epithelial cells in the depths of epithelial crypts in the pyloric caeca of the adult. The immunoreactivities of PLA₂s were investigated in the viscera of larvae and juveniles of the 0 to 85^th day after hatch. In the larvae of the 13^th day, accumulation of PLA₂-positive zymogen granules in the pancreatic acinar cells were first recognized by the immunostaining. The intensity of the labelling subsequently became stronger and dramatically increased between the 20^th and 30^th day. This increase appeared to be one of the physiological changes associated with the transition to a new benthic life as juveniles. Lack of PLA₂ in the pancreas before the 13^th day may suggest the possibility that larvae utilized exogenous PLA₂, inherent in their prey, to digest the phospholipids. On the other hand, no reactivity was found in the intestine until the 85^th day.