Human nutrition, the gut microbiome and the immune system

Marked changes in socio-economic status, cultural traditions, population growth and agriculture are affecting diets worldwide. Understanding how our diet and nutritional status influence the composition and dynamic operations of our gut microbial communities, and the innate and adaptive arms of our immune system, represents an area of scientific need, opportunity and challenge. The insights gleaned should help to address several pressing global health problems.     

有机物对沙幼虫麻醉活性的构效关系研究

应用量子化学HF/6-31G**从头算法得到了20种有机化合物的优势构象,在此基础上结合分子图形学技术,获得相应优化构象的电子结构参数和几何结构参数,并将这些参数与有机物对沙幼虫的麻醉活性参数相关联.结果表明:有机物对沙幼虫的麻醉活性与分子连接性拓扑指数(1Xv)、氢原子所带的最高正电荷(QH)和最负原子的静电荷(Q-)相关性较好,成功地建立了20种有机物对沙幼虫麻醉活性的构效关系式,找出了影响有机物对沙幼虫麻醉活性的主要结构因素.     

有机物对沙癙幼虫麻醉活性的构效关系研究

应用量子化学HF／6-31G＊＊从头算法得到了20种有机化合物的优势构象，在此基础上结合分子图形学技术，获得相应优化构象的电子结构参数和几何结构参数，并将这些参数与有机物对沙蜗幼虫的麻醉活性参数相关联．结果表明：有机物对沙蠋幼虫的麻醉活性与分子连接性拓扑指数（^1X^n）、氢原子所带的最高正电荷（QH）和最负原子的静电荷（Q^-）相关性较好，成功地建立了20种有机物对沙蠋幼虫麻醉活性的构效关系式，找出了影响有机物对沙蠋幼虫麻醉活性的主要结构因素．     

白骨壤植物多糖的提取工艺优化

报导了白骨壤水溶性多糖的水提醇沉工艺。以多糖提取率为评价指标,采用单因素试验和L(9 34)正交设计正交试验设计,研究了浸提时间、浸提温度、浸提次数和料水比对白骨壤水溶性多糖提取的影响。结果表明,影响多糖得率的主次因素为浸提次数、浸提温度、浸提时间及料水比,白骨壤水溶性多糖最佳提取工艺条件为:浸提时间2 h,浸提温度100℃,浸提次数2次,料水比1:40。在此最佳工艺条件下,多糖的提取率为3.89%。     

红树植物白骨壤对盐度的某些生理反应

红树植物白骨壤叶片的泌盐作用随着盐度的增加而增强，２０‰和４０‰盐度处理白骨壤叶片的泌盐作用比对照处理分别增加了２．７倍和４．７倍．叶片蒸腾作用和气孔导度则不同，当盐度由对照升高到４０‰时，蒸腾作用和气孔导度分别下降了５５％和４８％．叶和茎的膜脂质过氧化作用在盐度存在下都有所升高，根却有所降低．对超氧化物歧化酶的测定显示：在根中，超氧化物歧化酶较好地抑制了膜脂质过氧化作用的发生，而在叶和茎中，超氧化物歧化酶对脂质过氧化作用的抑制并不明显，两者之间可能存在更为复杂的相互关系．     

Enterotypes of the human gut microbiome

Our knowledge of species and functional composition of the human gut microbiome is rapidly increasing, but it is still based on very few cohorts and little is known about variation across the world. By combining 22 newly sequenced faecal metagenomes of individuals from four countries with previously published data sets, here we identify three robust clusters (referred to as enterotypes hereafter) that are not nation or continent specific. We also confirmed the enterotypes in two published, larger cohorts, indicating that intestinal microbiota variation is generally stratified, not continuous. This indicates further the existence of a limited number of well-balanced host-microbial symbiotic states that might respond differently to diet and drug intake. The enterotypes are mostly driven by species composition, but abundant molecular functions are not necessarily provided by abundant species, highlighting the importance of a functional analysis to understand microbial communities. Although individual host properties such as body mass index, age, or gender cannot explain the observed enterotypes, data-driven marker genes or functional modules can be identified for each of these host properties. For example, twelve genes significantly correlate with age and three functional modules with the body mass index, hinting at a diagnostic potential of microbial markers.     

海带提取物的安全性评价

目的　通过毒性实验 ,对海带提取物进行安全性评价。方法　采用昆明小鼠进行急性经口毒性实验、蓄积毒性实验、Ames实验以及骨髓嗜多染红细胞微核实验。结果　 (1)小鼠经口给予海带提取物LD50 >15 0 0mg/kg;在动物体内亦无蓄积毒性作用。 (2 )Ames实验为阴性。 (3)实验组小鼠骨髓细胞微核率与正常对照组相比无显著性差异 (P >0 0 5 )。结论　海带提取物属无毒物质 ,不具致突变作用     

On the growth and form of the gut

The developing vertebrate gut tube forms a reproducible looped pattern as it grows into the body cavity. Here we use developmental experiments to eliminate alternative models and show that gut looping morphogenesis is driven by the homogeneous and isotropic forces that arise from the relative growth between the gut tube and the anchoring dorsal mesenteric sheet, tissues that grow at different rates. A simple physical mimic, using a differentially strained composite of a pliable rubber tube and a soft latex sheet is consistent with this mechanism and produces similar patterns. We devise a mathematical theory and a computational model for the number, size and shape of intestinal loops based solely on the measurable geometry, elasticity and relative growth of the tissues. The predictions of our theory are quantitatively consistent with observations of intestinal loops at different stages of development in the chick embryo. Our model also accounts for the qualitative and quantitative variation in the distinct gut looping patterns seen in a variety of species including quail, finch and mouse, illuminating how the simple macroscopic mechanics of differential growth drives the morphology of the developing gut.     

广西北海海岸沙生白骨壤种群分布格局研究

采用方差 /均值比率法、游程法和点到点距离比率法测定广西北海海岸沙生白骨壤种群的分布格局类型 ,同时对该种群的平均拥挤度进行刀切法估计。结果表明 ,白骨壤种群的分布格局主要受自身的生物学特征和微地形影响 ,呈随机或集群分布。 3种方法都适用于白骨壤种群分布格局的研究 ,刀切法是一种比较有效的估测种群平均拥挤度的方法     

白骨壤种群不同年龄级的遗传多样性和遗传分化

采用垂直板型聚丙烯酰胺凝胶电泳测定了白骨壤（Avicennia marina)种群不同年龄级的遗传多样性和遗传分化。白骨壤种群在不同年龄级维持有较高的遗传多样性,观察杂合度为0．300,期望杂合度为0．180,化非常低,遗传分化系数为0．024,表明总的遗传变异中有2．4％来自不同年龄级的白骨壤。遗传距离和遗传一致度均值分别为0．005和0．995,基因流流畅,Nm=10.39,白骨壤种群不同年龄级的遗传分化远小于空间动态上的白骨壤的遗传分化。     

基于外磁场耦合的血泵驱动系统

基于横向旋转磁场的耦合原理,提出轴流式血泵外磁场驱动系统方案,设计一种泵机分离的结构。采用等效电流法建立了永磁体等效物理模型,计算血泵驱动系统的主动轮和从动轮之间的距离、相对转角以及磁极对数对血泵传动扭矩的影响。研究结果表明：在生理范围内,即主动轮与从动轮的安装距离小于60mm,设计的永磁体输出的扭矩大于血泵需要的扭矩（6.4N-mm）,能够满足血泵的驱动要求。主动轮与从动轮的磁极对数是影响血泵系统性能的关键参数,主动轮与从动轮磁极对数越少,传动扭矩越大,但是扭矩波动也大;主动轮的磁极对数大于从动轮的磁极对数,驱动系统传动平稳,对控制有利。