食用菌多糖抗运动疲劳研究进展

采用文献资料法对食用菌多糖抗运动疲劳的研究进展情况进行了研究。结果表明:食用菌多糖提取方法不同而食用菌多糖的提取率也不相同,超声波法+复合酶法及微波法提取食用菌多糖提取率较高,2种方法科学合理的结合提取食用菌多糖以及不同产地、品种和不同部位提取率是未来学者们需要研究的领域;目前,只是对极少部分食用菌多糖抗运动疲劳进行了研究,研究对象(动物)、模型、指标、评价单一而没有确定最佳剂量的时间而没确定的量。为此,提出了未来应加强和重视食用菌多糖抗疲劳运动多食用菌、多对象(尤其是人)、多模型、多指标、多评价、最佳剂量的研究以及量-效、构-效关系的研究建议。     

Dissolved oxygen controls summer habitat of Clear Lake Hitch (Lavinia exilicauda chi), an imperilled potamodromous cyprinid

Clear Lake Hitch is an imperilled minnow endemic to Clear Lake, Lake County, California, United States listed as threatened under the California Endangered Species Act (ESA) and a candidate for listing under the United States ESA. It exhibits a potamodromous life cycle whereby adults, which reach up to 6 + years in age and over 350 mm in length, migrate into Clear Lake's ephemeral tributaries briefly during spring to spawn. Conservation and management of Clear Lake Hitch is inhibited, in part, by a lack of information on the lacustrine habitat of nonbreeding individuals within Clear Lake. To address this problem, we sampled Clear Lake Hitch with gill nets in a stratified random sampling design to determine the distribution and habitat associations in early summer 2017 and 2018. We identified abundance-habitat relationships for juveniles and adults using Bayesian zero-inflated negative binomial generalised linear mixed modelling. Results indicated that dissolved oxygen concentration was the most important habitat feature measured; juveniles and adults were substantially more abundant in normoxic (≥2 mg/l) than in hypoxic (<2 mg/l) habitat. Both also exhibited weak positive relationships with chlorophyll fluorescence, suggesting relatively productive habitats may support higher numbers of Clear Lake Hitch. Spatially, juveniles were most abundant in nearshore habitats while adults were ubiquitous, indicating an ontogenetic habitat expansion that may be associated with a resource availability-predation risk trade-off. Management actions undertaken to improve hypoxia problems in Clear Lake would also improve Clear Lake Hitch habitat.     

Karanj protein isolate prepared from karanj seed cake: Effect on growth,body composition and physiometabolic responses in Labeo rohita fingerlings

A protein isolate was prepared from karanj seed (KPI) with 921.2 g protein/kg seed, which contained a negligible amount of anti‐nutritional factors and a balanced amino acid composition, especially rich in methionine. For 60‐day feeding trial, five isonitrogenous (300 g/kg CP) and isocaloric (15 MJ DE/kg) diets were formulated by replacing soybean protein isolate (SPI) on protein equivalent basis, KPI‐0 (control, 0 g/kg KPI); KPI‐25 (replacing 250 g/kg SPI protein with KPI); KPI‐50 (replacing 500 g/kg SPI protein with KPI); KPI‐75 (replacing 750 g/kg SPI protein with KPI) and KPI‐100 (replacing 1,000 g/kg SPI protein with KPI) for the feeding of L. rohita. The weight gain percentage, specific growth rate, feed conversion ratio and protein efficiency ratio were not significantly (p > .05) varied among the KPI fed and control groups. A significantly higher hepatosomatic index was recorded in the control and KPI‐25 groups compared with other groups. The whole‐body compositions, except ether extract, did not differ significantly (p > .05) among the groups. Digestive (amylase, protease, lipase and alkaline phosphatase) and metabolic enzyme activities (hexokinase, transaminases and lactate dehydrogenase) and glycogen stores were not significantly affected, whereas intestinal alkaline phosphatase differed significantly (p < .05). The RNA–DNA ratio was significantly (p < .05) higher in the KPI‐75 group. Thus, the study revealed that KPI can completely replace SPI protein at 191 g/kg inclusion level in the diets of L. rohita fingerlings.     

Appetite,metabolism and growth regulation in Atlantic salmon (Salmo salar L.) exposed to hypoxia at elevated seawater temperature

High temperature combined with low dissolved oxygen (DO) is one of the most challenging environmental conditions farmed fish experience; thus, understanding their impact on growth regulation is of relevance to cultured and wild populations. This study examines appetite‐ and growth‐regulating mechanisms in Atlantic salmon postsmolt exposed to either high (HO) or low oxygen (LO) at a suboptimally high temperature (17°C). Additionally, the effects of high (HE) and low (LE) dietary energy (DE) were examined. After a month of treatment, analyses of hormones, regulating appetite (ghrelin) and growth (growth hormone receptor ghr1 and insulin‐like growth factor IGF‐1), and free amino acids (FAA) were measured pre‐ and postprandially at ?4, ?2, 0, 2, 4 and 6 h. No preprandial ghrelin peaks were detected despite a significant reduction in feed intake and growth under hypoxia compared to normoxia. LO treatment also had an overall negative effect on survival compared to HO, while nutrient retention efficiency, FCR and plasma FAA concentrations were unaffected (P > 0.05). Feeding HE diet resulted in increased growth (+17%) and improved FCR (?14%) and energy retention efficiency (+26%) independent of DO. Plasma FAA concentrations were unaffected by LO treatment and DE (P > 0.05). Growth regulatory gene expressions possibly reflect an overall lower growth at a high temperature overriding the impacts of DO and DE. This study also indicates that optimal adaptation time to environmental conditions and feeding regime is crucial for establishing a regular hormonal appetite signalling that reflects real feeding anticipation in salmon.     

Survival and respiration of marbled rabbitfish (Siganus rivulatus) fingerlings at various oxygen tensions

Marbled rabbitfish, Siganus rivulatus, is an economically valuable herbivorous fish and a potential candidate for warmwater aquaculture. This study was carried out to: (1) assess the effect of various oxygen concentrations on survival and behaviour of S. rivulatus fingerlings and (2) investigate the response of S. rivulatus to hypoxia and determine its critical oxygen tension (P_crit). In the first experiment, groups of rabbitfish (15 fish per group) were maintained for 1 h in waters of various oxygen concentrations. They were then transferred to well‐aerated tanks and observed for 72 h. Survival was recorded, fish behaviour at low oxygen concentrations observed, and LC₅₀ after 1‐h hypoxia and 72‐h recovery evaluated. In the second experiment, a series of stop‐flow respirometry experiments were performed during which dissolved oxygen was allowed to drop to 0.5 mg L^?1 and respiration rate recorded at various oxygen concentrations. In the first experiment, all fish survived for 1 h at oxygen concentration of 1.44 mg L^?1 and greater, but started dying at oxygen concentrations below 0.65 mg L^?1 (16% survival). The LC₅₀ of S. rivulatus fingerlings was 0.6 mg L^?1. Results of the second experiment showed that S. rivulatus is an oxyregulator until P_crit (1.7 mg L^?1 O₂) is reached, becoming an oxyconformer below this concentration. Findings allow for a better understanding of environmental oxygen tolerances and minimum acceptable oxygen concentration in rabbitfish aquaculture.     

低氧胁迫对河川沙塘鳢抗氧化酶及ATP酶活性的影响

研究了在急性低氧1.5 h、5 h和慢性低氧3 d下,河川沙塘鳢(Odontobutis potamophila)5种组织(心、脑、肝、鳃和肾)的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶(GPX)3种抗氧化酶和ATP酶活性的变化规律。结果显示:在急性低氧暴露1.5 h时,河川沙塘鳢SOD和GPX的活力在各组织中与对照组相比均无显著差异,CAT活力在心、鳃和肝3种组织呈现显著升高(P0.05),ATP酶活力在心和肝组织极显著升高(P0.01);在急性低氧暴露5 h时,除肝组织SOD酶活性显著降低外(P0.05),其它4种组织的CAT、GPX和ATP酶均不同程度显著升高(P0.05);在慢性低氧处理3 d时,心、脑组织的抗氧化酶已基本恢复至与对照组无显著差异的水平,但鳃、肝和肾中酶活力仍较高(P0.05)。研究表明,河川沙塘鳢能通过自身调节抗氧化酶及ATP酶活性,改变代谢底物,提高机体适应低氧环境的能力。     

Effect of sulphide in Pacific white shrimp Penaeus vannamei under varying oxygen and pH levels

Sulphide is one of the known environmental stressors, which potentially binds to cytochrome C oxidase (COX), a key enzyme in the electron transport chain, thereby blocking oxygen transport and ATP production. To ascertain the toxic effects of sulphide on Pacific white shrimp, Penaeus vannamei, two distinct exposure experiments were carried out with varying concentration of sulphide (0–1 mg/L), dissolved oxygen (normoxia and hypoxia) and pH values (8.2, 6 and 5). The activity of enzymes viz COX, superoxide dismutase (SOD), phenoloxidase and lactate accumulation was investigated. Outer membrane integrity and COX monomer separation were also done with the isolated crude mitochondrial preparations. Results indicated a significant reduction (p ≤ .05) in COX enzyme activity in sulphide exposed treatments when compared to control. The reduction was more intense when pH levels were reduced under hypoxia condition. Lactate accumulation as a result of anaerobic metabolism was found to be higher in hypoxic treatments. No significant difference (p ≥ .05) was observed in superoxide dismutase activity between the treatments, whereas phenoloxidase activity significantly decreased at higher concentration sulphide. Separation of mitochondrial proteins resulted in the identification of ~205 kDa of COX monomer, and significant damage was found in outer membrane integrity under hypoxia and pH treatments. From this study, it is evident that at a given concentration, sulphide is toxic to P. vannamei, and in association with hypoxia and low pH, they further intensify sulphide toxicity. Our results indicated that sulphide toxicity should not be considered as a single factor, rather it should be a considered as combination of factors.     

Hypoxia inducible factor 1α expression and effects of its inhibitors in canine lymphoma

Hypoxic conditions in various cancers are believed to relate with their malignancy, and hypoxia inducible factor-1α (HIF-1α) has been shown to be a major regulator of the response to low oxygen. In this study, we examined HIF-1α expression in canine lymphoma using cell lines and clinical samples and found that these cells expressed HIF-1α. Moreover, the HIF-1α inhibitors, echinomycin, YC-1 and 2-methoxyestradiol, suppressed the proliferation of canine lymphoma cell lines. In a xenograft model using NOD/scid mice, echinomycin treatment resulted in a dose-dependent regression of the tumor. Our results suggest that HIF-1α contributes to the proliferation and/or survival of canine lymphoma cells. Therefore, HIF-1α inhibitors may be potential agents to treat canine lymphoma.