INFECTIOUS DISEASES IN MACRO-ALGAE: THE EFFECT ON HOST FITNESS

The understanding of infectious diseases of algae has improved significantly in recent years, particularly in the area of recognition and signaling, key processes that determine the success or failure of host invasion by the pathogen. Ecological studies have also contributed to better understanding the role of diseases in wild stands of the affected hosts. An aspect that has received only limited attention is the effect of the infections on host fitness, and in this context, we report a first attempt to quantifying the effects of Pleurocapsa sp. (Cyanophyta) on the reproductive potential of its host Mazzaella laminarioides (Rhodophyta). Infections by Pleurocapsa trigger the development of tumors that can result in major changes in frond morphology and texture. Two populations of the host were considered in the study. Our results indicate that infections do not cause a significant effect on the density or quality of the reproductive structures (i.e. cystocarps and tetrasporangia). However, the number of spores, settlement rates, germination success and offspring survival, were all affected negatively by the endophytic infections. The reported information and field-collected data, strengthen the notion that pathogens of algae may exert strong effects on their hosts at several levels, including reproduction. These effects can vary from host death during infections by highly pathogenic organisms to more subtle effects like those observed in the studied pathosystem. Infections by less aggressive pathogens, however, still may determine important effects at the population level by inducing differential mortality and reproductive success in infected individuals.     

0.1%西吡氯铵漱口液的体外抗菌试验

目的：测定0．1％西吡氯铵（CPC）漱口液对龋病、牙龈炎、牙周炎和颌面外科术后感染常见病原菌的抗菌活性。方法：采用经典的琼脂稀释法药物敏感试验,测定检测药品及对照药品对细菌的MIC50和MIC90。结果：0．1％漱口液对204株厌氧菌均有明显的抗菌作用,其MIC50和MIC90则均为3.1mg/L、6.2mg/L和3.1mg/L、3.1-6.2mg/L,对革兰阴性厌氧杆菌的MIC50和MIC90则均为3．1mg/L 和3．1－6．2mg/L,对致龋菌变形链球菌的MIC50和MIC90为6．2mg/L和12．5mg/L,对金黄色葡萄球菌、表皮葡萄球菌的MIC50和MIC90分别为6．2、6．2、12．5、6．2mg/L,对铜绿假单胞菌的MIC50和MIC90均≥1000mg/L。另外,接种细菌的浓度对0．1％CPC漱 口液的MIC值略有影响,随着细菌浓度升高,MIC值略升高;随着细菌浓度减小,MIC值略减小。结论：除铜绿假单胞菌外,0．1％CPC漱口液对其余259株实验菌均有明显的抗菌作用,因此0．1％漱口液可作为口腔感染的有效抗菌剂。