Lenaerts Isabelle, Walker Glenda A, Van Hoorebeke Luc, Gems David, Vanfleteren Jacques R
Department of Biology, Ghent University, Ghent, Belgium.
J Gerontol A Biol Sci Med Sci. 2008 Mar;63(3):242-52. doi: 10.1093/gerona/63.3.242.
In Caenorhabditis elegans, several manipulations that affect nutrition slow development, reduce fecundity, and increase life span. These are viewed as dietary restriction (DR) and include culture in semidefined, nutrient-rich liquid medium that is axenic (i.e., there is no microbial food source). Here we describe convenient ways to exert DR by culture on agar plates containing axenic medium. We used these to explore whether effects of axenic culture really reflect DR. Our results imply that major nutrient components of axenic medium, and overall caloric content, are not limiting for life span. However, adding growth-arrested Escherichia coli as an additional food source rescued the effects of axenic culture. We then sought to identify the component of E. coli that is critical for normal C. elegans nutrition using add-back experiments. Our results suggest that C. elegans has a nutritional requirement for live, metabolically active microbes or, possibly, an unidentified, heat-labile, nonsoluble component present in live microbes.
在秀丽隐杆线虫中，几种影响营养的操作会减缓发育、降低繁殖力并延长寿命。这些被视为饮食限制（DR），包括在无菌的半定义、营养丰富的液体培养基中培养（即没有微生物食物来源）。在这里，我们描述了通过在含有无菌培养基的琼脂平板上培养来施加饮食限制的便捷方法。我们用这些方法来探究无菌培养的效果是否真的反映了饮食限制。我们的结果表明，无菌培养基的主要营养成分和总热量含量对寿命没有限制。然而，添加生长停滞的大肠杆菌作为额外的食物来源挽救了无菌培养的效果。然后，我们试图通过回补实验确定大肠杆菌中对秀丽隐杆线虫正常营养至关重要的成分。我们的结果表明，秀丽隐杆线虫对活的、代谢活跃的微生物有营养需求，或者可能对活微生物中存在的一种未鉴定的、热不稳定的、不溶性成分有营养需求。
