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Gyrodactylus salaris is a freshwater, monogenean ecto-parasite of Atlantic-salmon. Infection of its natural host, the Baltic strain of Atlantic-salmon, is inapparent. G. salaris also can infect rainbow-trout (Oncorhynchus mykiss) permanently, and cause infection of ≤50 days in several other species. It is only on Atlantic stocks of Atlantic-salmon (Salmo salar) that the parasite multiplies unchecked by an immune response, causes death in juveniles and dramatic reductions in wild populations. In Norway, the parasite has been introduced into 45 rivers, resulting in reductions in Atlantic-salmon stocks of up to 98%. It is probably the most-important exotic fish-disease threat to the UK. We used risk analysis to assess the most-important routes of spread for G. salaris between rivers in England and Wales. The movement of live rainbow-trout was identified as the most-important route of transmission; this route is likely to lead rapidly to the wide geographic spread of the parasite. The movement of other species of fish (especially from sites holding rainbow-trout) is also an important risk. Other routes of spread (including mechanical transmission on farm equipment and vehicles, angling equipment, canoes, etc.) might allow limited local spread (mainly to neighbouring rivers). 相似文献
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传统时代南海九江的鱼苗养殖业与桑基鱼塘 总被引:1,自引:0,他引:1
南海九江地区的桑基鱼塘是珠三角基塘农业经营历史最悠久、技术最成熟的区域。清代初年这里的鱼苗养殖已经十分兴盛,已经形成连片的桑基鱼塘。九江位于西江下游,这里的居民长期垄断了西江的鱼苗捕捞和养殖技术。鱼苗养殖是九江地基塘农业经营的重要组成部分,鱼苗养殖的特定技术也促使当地基塘形成了多样化的形态与特定的微环境特征。基塘属于小型的水利工程,九江地区桑基鱼塘与堤围的修建,塑造出适应基塘排灌需要的人工河网。九江地区桑基鱼塘是典型的循环农业,经营中的施行立体化的种养殖模式。 相似文献
125.
应用高压液相色谱技术,对国内外目前疗效较好的几种脑蛋白水解物类药物进行了氨基酸组成及含量的检测分析。检测结果表明,不同品牌的脑蛋白水解物类药物均具有相同的氨基酸组成,但其氨基酸含量存在差异,其中人体必需的9种氨基酸在各品牌药品氨基酸的总量上占有很大比例。人体必需氨基酸在脑蛋白水解物类药物游离氨基酸中占有重要位置,它们的存在及含量上的差别极有可能是影响此类药物疗效的重要原因。 相似文献
126.
We investigated the effects of open- and closed-system temperature changes on the O2 affinity of Atlantic bluefin tuna (Thunnus thynnus) blood using in vitro methods essentially identical to those previously employed on tropical tuna species. Bluefin tuna blood has a general O2 affinity (P
50 = 2.6–3.1 kPa or 19–23 mm Hg at 0.5% CO2) similar to that of skipjack tuna, yellowfin tuna, and kawakawa blood (P
50 = 2.8–3.1 kPa at 0.5% CO2) but significantly above that of bigeye tuna blood (P
50 = 1.6–2.0 kPa at 0.5% CO2). We therefore hypothesize that bluefin tuna are less tolerant of hypoxia than bigeye tuna. Further, we found the P
50 of bluefin tuna blood to be slightly reduced by a 10°C open-system temperature increase (e.g., from 4.83 kPa at 15°C to 3.95 kPa at 25°C) and to be completely unaffected by a 10°C closed-system temperature change. Bluefin tuna blood, therefore, had a significantly reduced Bohr effect when subjected to the inevitable changes in P
CO
2 and plasma pH that accompany closed-system temperature shifts (0.04–0.09 Δlog P50ΔpH−1) compared with the effects of changes in plasma pH accomplished by changing P
CO
2 alone (0.81–0.94 Δlog P50 Δ pH−1). This response is similar to that of skipjack tuna blood, but different from yellowfin or bigeye tuna blood. During closed-system temperature changes at oxygen levels above P
50, however, bluefin tuna blood showed a reversed temperature effect (i.e., P
O
2 decreased in response to an increase in temperature). Unlike in other tuna species, temperature effects on O2 affinity of bluefin tuna whole blood were similar to those previously reported for hemoglobin solutions, suggesting that red cell-mediated ligand changes are not involved. 相似文献
127.
Summary The eyes of 160 Collies were examined for Collie Eye Anomaly, Progressive Retinal Atrophy, and any other eye abnormality present. The incidence of CEA in 160 Collies was 40.6 per cent. There were no cases of PRA. Other abnormalities noted were distichiasis, persistent pupillary membranes, distinct remnants of the hyaloid artery, corneal dystrophy and unilateral cataracts. 相似文献
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为了探讨大海马蛋白质的高效利用方法,本试验将脱脂大海马粉经碱性蛋白酶和胰蛋白酶联合消解后,酶解液(PH)经超滤膜分离为5组分(PH-Ⅰ、PH-Ⅱ、PH-Ⅲ、PH-Ⅳ、PH-Ⅴ),结合各组分的氨基酸组成,回归分析了各组分的自由基清除能力与氨基酸组成间的相关关系。结果表明,酶解液经超滤膜分离的5组分中PH-Ⅴ(<2 500 Da)抗氧化能力较强,清除DPPH自由基能力为34.2%±0.1%,对超氧阴离子的清除能力为29.2%±0.1%,Fe3+还原力为0.28%±0.1%。海马酶解多肽各组成中疏水性氨基酸含量低于亲水性氨基酸,但疏水性氨基酸对自由基的清除能力起着决定性作用,极性氨基酸和非极性氨基酸可通过协同作用来增强海马多肽清除自由基的能力,且每个单位极性氨基酸的抗氧能力是非极性氨基酸的1.2倍,每个单位芳香族氨基酸的抗氧化能力是脂肪族氨基酸的2倍。本研究不仅制备了一类具有开发价值的抗氧化多肽,并且分析了多肽抗氧化能力与氨基酸组成的相关关系,为大海马的高值化利用提供了理论依据。 相似文献