Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK.
BMC Genomics. 2010 Jul 5;11:418. doi: 10.1186/1471-2164-11-418.
The immune response is an energy demanding process, which has effects in many physiological pathways in the body including protein and lipid metabolism. During an inflammatory response the liver is required to produce high levels of acute phase response proteins that attempt to neutralise an invading pathogen. Although this has been extensively studied in both mammals and fish, little is known about how high and low energy reserves modulate the response to an infection in fish which are ectothermic vertebrates. Food withdrawal in fish causes a decrease in metabolic rate so as to preserve protein and lipid energy reserves, which occurs naturally during the life cycle of many salmonids. Here we investigated how the feeding or fasting of Atlantic salmon affected the transcriptional response in the liver to an acute bacterial infection.
Total liver RNA was extracted from four different groups of salmon. Two groups were fed or starved for 28 days. One of each of the fed or starved groups was then exposed to an acute bacterial infection. Twenty four hours later (day 29) the livers were isolated from all fish for RNA extraction. The transcriptional changes were examined by micro array analysis using a 17 K Atlantic salmon cDNA microarray. The expression profiling results showed major changes in gene transcription in each of the groups. Enrichment for particular biological pathways was examined by analysis of gene ontology. Those fish that were starved decreased immune gene transcription and reduced production of plasma protein genes, and upon infection there was a further decrease in genes encoding plasma proteins but a large increase in acute phase response proteins. The latter was greater in magnitude than in the fish that had been fed prior to infection. The expression of several genes that were found altered during microarray analysis was confirmed by real time PCR.
We demonstrate that both starvation and infection have profound effects on transcription in the liver of salmon. There was a significant effect on the transcriptional response to infection depending on the prior feeding regime of the fish. It is likely that the energy demands on protein synthesis for acute phase response proteins are relatively high in the starved fish which have reduced energy reserves. This has implications for dietary control of fish if an immune response is anticipated.
免疫反应是一个耗能过程，它对身体的许多生理途径都有影响，包括蛋白质和脂质代谢。在炎症反应过程中，肝脏需要产生高水平的急性期反应蛋白，以试图中和入侵的病原体。尽管这在哺乳动物和鱼类中都得到了广泛的研究，但对于冷血脊椎动物鱼类在高、低能量储备水平下如何调节对感染的反应知之甚少。鱼类的禁食会导致代谢率降低，从而保存蛋白质和脂质能量储备，这在许多鲑鱼的生命周期中自然发生。在这里，我们研究了大西洋鲑鱼的喂养或禁食如何影响肝脏对急性细菌性感染的转录反应。
从四个不同组别的鲑鱼中提取了总肝 RNA。两组分别进行 28 天的喂养或禁食。每组中的一组进行急性细菌感染暴露。24 小时后（第 29 天），从所有鱼中分离肝脏进行 RNA 提取。使用大西洋鲑鱼 17 K cDNA 微阵列通过微阵列分析检查转录变化。表达谱分析结果显示，各组的基因转录都发生了重大变化。通过基因本体分析，对特定生物途径的富集进行了分析。那些禁食的鱼减少了免疫基因的转录和血浆蛋白基因的产生，在感染后，编码血浆蛋白的基因进一步减少，但急性期反应蛋白的产生大量增加。这种增加的幅度大于感染前喂食的鱼。通过微阵列分析发现的一些基因的表达通过实时 PCR 得到了证实。
我们证明了饥饿和感染对鲑鱼肝脏的转录都有深远的影响。鱼类之前的喂养方式对感染的转录反应有显著影响。在饥饿的鱼中，用于急性反应蛋白的蛋白质合成的能量需求相对较高，因为它们的能量储备减少。如果预期会产生免疫反应，这对鱼类的饮食控制有影响。
