Profiling of the Bacterial Microbiota along the Murine Alimentary Tract

Here, the spatial distribution of the bacterial flora along the murine alimentary tract was evaluated using high throughput sequencing in wild-type and Tff3-deficient (Tff3^KO) animals. Loss of Tff3 was linked to increased dextran sodium sulfate-induced colitis. This systematic study shows the results of 13 different regions from the esophagus to the rectum. The number of bacterial species (richness) increased from the esophagus to the rectum, from 50 to 200, respectively. Additionally, the bacterial community structure changed continuously; the highest changes were between the upper/middle and lower gastrointestinal compartments when comparing adjacent regions. Lactobacillus was the major colonizer in the upper/middle gastrointestinal tract, especially in the esophagus and stomach. From the caecum, a drastic diminution of Lactobacillus occurred, while members of Lachnospiraceae significantly increased. A significant change occurred in the bacterial community between the ascending and the transverse colon with Bacteroidetes being the major colonizers with relative constant abundance until the rectum. Interestingly, wild-type and Tff3^KO animals did not show significant differences in their bacterial communities, suggesting that Tff3 is not involved in alterations of intraluminal or adhesive microbiota but is obviously important for mucosal protection, e.g., of the sensitive stem cells in the colonic crypts probably by a mucus plume.     

不同菌种发酵对纳豆激酶活性及黏液成分影响

采用5株不同来源的纳豆菌JLTH-075、JLGZL-018、JLTH-157、JLCC-243、JLLY-214,通过纳豆发酵实验,研究不同菌株对纳豆激酶活力、黏液营养物质的影响,评价其发酵性能,为纳豆工业生产用菌筛选提供借鉴。结果表明,菌株JLGZL-018生产的纳豆激酶活性最高,为4 167 IU/g;其生产的纳豆黏液成分中总蛋白、可溶性总糖含量最高,分别为（17.38±0.54）%、（5.21±0.13）%;水解氨基酸总量适中,为（5.24±0.27） g/100 g,7种必需氨基酸含量最高,为（0.87±0.08） g/100 g;游离氨基酸各成分与其他4株菌无显著差别。菌株JLGZL-018综合发酵性能较好,具有开发应用潜力。     

泥鳅体表粘液多糖诱导SGC—7901细胞凋亡机理研究

探讨泥鳅体表粘液多糖（PML）对人胃癌SGC-7901细胞凋亡作用和机制。采用Sevege法对PML进行分离、纯化,用紫外分光光度法、凝胶色谱法和高效液相色谱法对其鉴定后作用于SGC-7901细胞中。采用MTT法鉴定PML对该细胞的抑制作用,光显下观察细胞形态结构变化,流式细胞术检测细胞周期及凋亡,Western Blot检测Bax、Bcl-2蛋白表达变化。结果表明,用Sevege法提取PML纯度高、成分单一。MTT法,10～270μg/mL PML处理SGC-7901细胞24、48、72h,抑制作用随PML浓度和时间增加而逐渐增强。流式细胞术检测细胞凋亡,凋亡率随PML浓度和作用时间增加而逐渐增高。Western Blot检测,细胞经10～270μg/mL PML处理24、48h后Bcl-2和Bax蛋白表达随浓度和时间增加分别增强和减少,说明PML对SGC-7901细胞凋亡有促进作用,其机理与对Bcl-2与Bax基因的调控有关。     

Investigation of the role of diterpenes produced by marine pulmonatesTrimusculus reticulatus andT. conica

The intertidal pulmonate limpetTrimusculus reticulatus, which is found in caves or crevices along the California coast, was previously reported to contain two novel diterpenoids, 6-isovaleroxylabda-8,13-dien-7,15-diol (1) and 2,7-diacetoxy-6-isovaleroxylabda-8,13-dien-15-ol (2). Dissection of the animals prior to extraction revealed that the diterpenoids were concentrated in the mantle, foot, and mucus, but not in the viscera. The presence ofT. reticulatus or its mucus was toxic to veliger larvae of the sabellariid reef-building tube wormPhragmatopoma californica. The major diterpenoid1 was responsible for the observed larvicidal activity. Protection against overgrowth by settling invertebrate larvae is important for the survival of this sessile filter-feeding pulmonate. A related pulmonate,T. conica, which was found in similar intertidal habitats in New Zealand, contained 6-acetoxy-7-isovaleroxylabda-8,13-dien-15-oic acid (3) and 1,7,12,18-tetraacetoxy-cholest-5-en-3-ol (4). The diterpene3 was also localized in the foot, mantle, and mucus ofT. conica but was not larvicidal toP. californica.     

透明质酸体系与水界面稳定性的分子动力学模拟

为考察仿生黏液透明质酸体系与水相界面行为随时间的变化规律,结合Forcite模块,采用Nose扩展系统控温法、Atom based计算方法和Ewald计算方法,通过分子动力学研究,探讨仿生黏液-水界面的分子之间的变化。以透明质酸的水溶液为代表,模拟生物黏液,从微观层面探讨界面稳定性：从界面张力、界面相互作用能、径向分布函数和均方根位移等方面分析影响界面稳定性的因素。结果表明：仿生黏液在透明质酸高分子多聚体和水分子在质量比为1∶10时的界面张力最小为61.33 mN/m,此时的单位界面能最低为242.67 kJ/(mol·nm²),界面最稳定。根据MSD曲线和RDF(径向分布函数),从水分子和透明质酸分子相互作用的强弱和水分子的移动也间接地表明在质量比为1∶10时,体系界面稳定性最高。模拟结果与实验的稳定性结果一致,从微观层面解释了透明质酸体系和水界面的一些规律。     

洞庭湖鲶鱼体表黏液和肌肉营养组成对比分析

对洞庭湖野生鲶鱼体表黏液及肌肉的营养成分进行分析比较。结果表明:黏液中水分含量极显著高于肌肉(P<0.01),而粗蛋白、粗灰分和粗脂肪含量均极显著低于肌肉(P<0.01)。微量元素含量除Mn外均是黏液显著高于肌肉,Cu、Zn、Fe的比值合理。黏液和肌肉的氨基酸组成基本一致,均含有18种氨基酸,氨基酸总量分别是80.46%和81.65%,呈味氨基酸分别为31.37%和31.35%,必需氨基酸指数(EAAI)分别为59.73、64.53。色氨酸、蛋氨酸和胱氨酸为限制性氨基酸。黏液中二十碳五烯酸(EPA)与二十二碳六烯酸(DHA)的含量极显著高于肌肉(P<0.01),分别为8.79%、13.48%;黏液中花生四烯酸(ARA)的含量为3.21%,而肌肉中未检出。     

Heavy metals in seawater: Effects on limpet pedal mucus production

Toxicological modification of molluscan mucus production has largely been ignored. This is probably due to an underestimation of the r le of mucus in molluscan physiology and its energetic cost. This paper reports that laboratory exposure to episodic doses of waterborne copper and zinc serve to reduce pedal mucus production by the common limpet Patella vulgata L. to about 60% of the unstressed rate. The metals are effective in this respect at concentrations as low as 10 μg l⁻¹, which in the case of zinc is below the current U.K. environmental quality standard. All metal doses reduced mucus production to the same level. This suggests a behavioural response of the limpet, limiting activity. The reduction in mucus production has important consequences both for limpet ecology and for the ways in which biological energy allocation and transformation are assessed.     

Ni-Zn-P镀层在黏液形成菌中的结垢和腐蚀特性

利用化学镀层对换热面常用的碳钢材料进行表面改性,得到晶胞细致的Ni-Zn-P镀层。将得到的Ni-Zn-P试样与碳钢试样、Ni-P试样进行比较。在黏液形成菌菌悬液中进行微生物污垢和腐蚀实验,进而分析3种试样的抗微生物污垢特性和腐蚀特性。利用称重法记录3种试样的污垢沉积变化情况和光电比浊法记录黏液形成菌的生长情况。利用扫描电镜观察试样在污垢静置实验后的表面形貌,分析比较实验前后表面形貌的变化。利用电化学方法研究试样在黏液形成菌菌悬液中的腐蚀情况。实验结果表明,Ni-Zn-P镀层抗微生物污垢特性和耐腐蚀性稍好于Ni-P镀层,Ni-Zn-P镀层表面微生物污垢附着量相较于Ni-P镀层和碳钢分别减小24.1%和67.7%,Ni-Zn-P镀层表面腐蚀失重量相较于Ni-P镀层和碳钢分别减小5%和84.6%。由于Ni-Zn-P镀层的保护,碳钢表面抗微生物污垢特性和耐腐蚀性得到明显提高。