人体细胞和肠道微生物数量,比例解读.pptx

对人体细胞和微生物数量的改进估计 Ron Sender 1.Origin of prevalent claims in the literature on the number of bacterial cells In humans 为什么大家会普遍认为肠道微生物数量是人体细胞的十倍，本文作者对文献进行了 追溯，结果显示1977年Savage,annu,Rev.Microbiol引用超过一千。而它的计算基础是 胃肠道容积为1L，肠道微生物浓度为1011 /g. 2.Distribution of bacteria in different human organs 不同部位的微生物数量相差很大，由上表可知，人体微生物约90%都集中 在结肠。 所以作者统计了不同文献的结肠微生物浓度，平均值为0.92*1011 /g. 3.Concentration of bacteria in the colon 4.The number of human cells in a “standard” adult male A mass-based order-of-magnitude estimate for this number assumes a 10 2 kg man, which is divided by the mass of a “representative” mammalian, cell 10 -12 -10 -11 kg (assuming cell volumes of 1,000-10,000 μm 3 , spectively), thus arriving at 10 13 - 10 14 cells. One study used a DNA-centered method (Baserga, 1985). The method begins by estimating the number of cells in the body of a 25g mouse by dividing the total amount of DNA (stated to be 20 mg) by the DNA content of one diploid mouse cell(6·10 -12 g DNA per cell) to get ≈3·10 9 cells in a 25 g mouse. Then extrapolate from mouse to human by using the ratio of masses to get ≈10 13 cells in the human body. This method excludes cells that do not contain DNA, such as red blood cells and platelets. Summing over a total of 56 cell categories (Bianconi et al., 2013) resulted in an overall estimate of 3.7·10 13 humancells in the body (SD 0.8·10 13 , i.e. CV of 22%) 5.Updated inventory of human cells in the body We focus on the six cell types that were recently identified (Bianconi et al., 2013) to comprise 97% of the human cell count: red blood cell accounting for 70%), glial cells (8%), endothelial cells (7%), derma fibroblasts (5%), platelets (4%) and bone marrow cells (2%). The other 50 cell types account for the remaining 3%. 5.Updated inventory of human cells in the body Red blood cells: (Boer, 1984; Feldschuh and Enson, 1977; Nadler et al., 1962; Snyder et al., 1975) 4.9L (Ambayya et al., 2014; Dosoo et al.,2012; Nordin et al., 2004; Pekelharing et al.,