肠道微生物群加重黑腹果蝇盐胁迫反应

【背景】高盐饮食目前引起普遍关注,肠道微生物与盐胁迫的相互作用正成为研究热点之一。【目的】以黑腹果蝇为宿主模型,探讨肠道微生物对果蝇盐胁迫反应的影响与潜在机理。【方法】利用平板计数法和定量PCR法检测果蝇肠道载菌量;利用存活率和运动能力测定装置测定果蝇适合度;用化学试剂和抗生素处理建立无菌果蝇,测定肠道菌对果蝇盐胁迫反应的影响;利用亮蓝食用色素染料渗透性实验检测果蝇肠道屏障的完整性;应用实时定量PCR检测先天免疫系统的活性。【结果】高盐处理引起果蝇肠道菌群失调,导致其肠道载菌量显著增加。此外,高盐饮食(high salt diet,HSD)降低了黑腹果蝇成虫的存活率和运动能力。经0.75 mol/L NaCl处理,雌性GF (germ-free)果蝇存活率比对照组升高了11%,同时混合抗生素有效地提高了高盐处理后果蝇的存活率。肠道微生物加剧了肠道屏障功能损伤,雌性GF果蝇出现染料渗透性实验现象的百分率比对照组降低了8%。在分子水平上,盐胁迫下雌性GF果蝇体内Attacin-C、Duox基因表达水平分别是CR(conventionally reared)果蝇的2.5倍和1.7倍。【结论】肠道微生物加重果蝇盐胁迫反应,引发高盐诱导的肠屏障功能紊乱,并且抑制高盐诱导的先天免疫活性。

Intestinal microbiota aggravates the salt stress response in Drosophila melanogaster

Background] High salt in diet is currently a major issue in life, and the interaction between intestinal microbes and salt stress has become one of the research hotspots. Objective] To explore the effect and the underlying mechanism of intestinal microbiota on the salt stress response using D. melanogaster model. Methods] To evaluate intestinal bacterial load with plate counting and qPCR. To examine the fitness of Drosophila with survival rate and locomotion. To investigate roles of intestinal bacteria in salt stress by generating germ free flies with chemical reagents and antibiotic cocktails. To detect the integrity of the intestinal barrier using dye permeability test. To assess the expression levels of genes utilizing RT-PCR. Results] High salt induced the dysbiosis of intestinal microbiota in D. melanogaster, leading to a significant increase in intestinal bacterial load. High salt compromised the survival rate and locomotion of D. melanogaster adults. Treated with 0.75 mol/L NaCl, the survival rate of GF female flies was 11% higher than that of counterparts. Additionally, bacterial depletion using antibiotics efficiently improved the survival rate of females challenged with high salt. Intestinal dysbiosis exacerbated high salt-induced intestinal barrier dysfunction with a 8% decrease in Smurf than that in control fly. At the molecular level, the expression levels of Attacin-C and Duox in GF female flies in the case of salt stress were 2.5- and 1.7-fold higher than that of CR flies, respectively. Conclusion] Intestinal microbiota aggravate the salt stress response in D. melanogaster, resulted in intestinal barrier dysfunction and suppressed innate immune activity in the presence of salt stress.