高通量测序方法分析两种草食性淡水螺肠道菌群多样性

淡水螺是水生态系统中重要的生物类群,也是多种寄生虫的中间宿主。肠道菌群在动物能量代谢和抵抗病原体方面起着重要作用。本文分析了耳萝卜螺Radix auricularia和三旋卷丽螺Planorbella trivolvis肠道菌群的多样性。结果表明:在门水平上,耳萝卜螺有23个菌门,以变形菌门(Proteobacteria,33.63%)、蓝细菌门(Cyanobateria,15.33%)、绿弯菌门(Chloroflexi,13.95%)和放线菌门(Actinobacteria,12.99%)为主;三旋卷丽螺有13个菌门,以变形菌门(54.88%)、拟杆菌门(Bacteroidetes,28.49%)和放线菌门(7.65%)为主。属水平上,耳萝卜螺有厚皮藻属Pleurocapsa、硫网菌属Thiodictyon、纤毛菌属Leptotrichia及类诺卡氏菌属Nocardioides等445个属;三旋卷丽螺有Cloacibacterium、OM60NOR5_clade、假单胞菌属Pseudomonas及红杆菌属Rhodobacter等238个属。有93个菌属为两种螺的共有核心菌群(所有样本中都存在),其中27个菌属丰度大于0.5%。两种螺肠道菌群结构差异显著(P=0.027)。PICRUSt功能预测分析表明,两种螺肠道菌群KEGG功能组成相似,氨基酸代谢、碳水化合物代谢及膜转运丰度较大。综上,两种草食性淡水螺肠道菌群多样性较高且差异显著,但有数量较多的共有核心菌群。

Resonator fiber optic gyros with light time-division input and multiplexing output in clockwise and counterclockwise directions

A resonator fiber optic gyro with the light time-division input and multiplexing output(TDM-RFOG)in the clockwise(CW)and counterclockwise(CCW)directions is proposed.The light time-division input in the CW and CCW directions can effectively suppress the backscattering induced noise.The TDM-RFOG is implemented with the 2×2 Mach–Zehnder interferometer(MZI)optical switch.The response time of the fiber ring resonator is analyzed,and it is demonstrated by experiments that light time-division input in the CW and CCW directions can reduce the backscattering induced noise.The suppression effectiveness of backscattering induced noise in the TDM-RFOG is determined by the extinction ratio of the optical switch,so a closed loop is designed to adjust the phase shift difference between the two arms of the MZI optical switch to control the extinction ratio.The method using two arms of the MZI optical switch with twin 90°polarization-axis rotated splices is proposed to make the extinction ratio along both slow and fast axes greater than-70 d B.