Antagonism between coral pathogen Vibrio coralliilyticus and other bacteria in the gastric cavity of scleractinian coral Galaxea fascicularis

Scleractinian corals host numerous microbial symbionts with different types of interactions. The gastric cavity of scleractinian coral, as a semiclosed subenvironment with distinct chemical characteristics(e.g., dissolved O2, pH, alkalinity, and nutrients), harbors a distinct microbial community and a diverse array of bacteria that can be pathogenic or beneficial. Galaxea fascicularis is one of the dominant massive scleractinian coral species on inshore fringing reefs in the northern South China Sea.Although the abundance of coral-associated bacteria has been investigated in G. fascicularis, less is known about the microorganisms in the gastric cavity. In this study, we specially isolated cultivable bacterial strains from the gastric cavity of G.fascicularis collected from Hainan Island using a noninvasive sampling approach. Among the 101 representative bacterial strains, one Vibrio coralliilyticus strain, SCSIO 43001, was found to be a temperature-dependent opportunistic pathogen of G.fascicularis. The antagonistic activity between the 100 strains and V. coralliilyticus SCSIO 43001 was tested using a modified Burkholder diffusion assay. Our results showed that V. coralliilyticus SCSIO 43001 inhibits the growth of Erythrobacter flavus and Sphingomonas yabuuchiae. Additionally, we found that three Pseudoalteromonas strains showed moderate to high antibacterial activity against V. coralliilyticus SCSIO 43001 and several other coral-associated Gram-negative bacterial strains.These results suggest that competition between the coral pathogen and other bacteria also occurs in the gastric cavity of coral, and Pseudoalteromonas strains in the gastric cavity of G. fascicularis may provide a protective role in the defense against coinhabiting coral pathogens at elevated temperature.     

升温对丛生盔形珊瑚两种形态型代谢和共生藻光合生理的影响

文章研究了温度升高对一种造礁石珊瑚——丛生盔形珊瑚(Galaxea fascicularis)的两种形态型(H和S型)代谢和共生藻光合生理的影响。研究显示H型和S型对升温的生理响应差异明显:在虫黄藻水平上, H型丢失了大量的虫黄藻,减轻了共生体呼吸代谢的负荷; S型中虫黄藻数目尚可维持共生体呼吸代谢的需求,同时提高叶绿素b含量增强光的吸收。在宿主水平上,H型充分利用虫黄藻输送的营养物质,并通过异养摄食补偿能量消耗;S型宿主所储存的营养物质可以协助共生体适应热环境。结果表明,丛生盔形珊瑚两种形态型通过不同的能量利用方式适应环境的变化, H型倾向于维持共生体的代谢平衡,而S型倾向于提高共生藻的能量分配。     

Biosorption and desorption of Cd^2＋ from wastewater by dehydrated shreds of Cladophorafascicularis

The adsorption and desorption of algae Cladophora fascicularis and their relation with initial Cd^2＋ concentration, initial pH, and co-existing ions were studied. Adsorption equilibrium and biosorption kinetics were established from batch experiments. The adsorption equilibrium was adequately described by the Langmuir isotherm, and biosorption kinetics was in pseudo-second order model. The experiment on co-existing ions showed that the biosorption capacity of biomass decreased with an increasing concentration of competing ions. Desorption experiments indicated that EDTA was efficient desorbent for recovery from Cd^2＋. With high capacities of metal biosorption and desorption, the biomass of Cladophora fascicularis is promising as a cost-effective biosorbent for the removal of Cd^2＋ from wastewater.     

黄海西部细弱刚毛藻（刚毛藻目，绿藻门）的表型可塑性与分类——暗示基因序列作为DNA条形码的可行性

由于广泛的形态可塑性,导致刚毛藻属物种的分类仍存在不确定性。作为分布较广的物种之一,细弱刚毛藻已报道了许多变异类型,这为对其鉴定造成了困难。针对这个问题,本研究通过采集于黄海西部相似于细弱刚毛藻的9个样品,分析了它们的形态多样性。一些样品具有明显的可变鉴定特征,难于利用形态分类准确鉴定。因此,采用18S rDNA和 ITS序列对它们进行了分子鉴定。其中,样品的18S rDNA序列相似度为99.6%-100%,而ITS的为98.7% -100%。分子数据强烈地支持了形态可变的样品可准确定位为细弱刚毛藻。通过对样品分类特征的比较分析发现,作为分类标准的分枝方式和密度、藻体颜色、藻体高度和质地受环境影响和藻体成熟度而发生较大变化。此外,作为相对稳定的特征,细胞大小在种内水平上也常发生变化。18S rDNA和ITS序列在本种鉴定上的成功应用,表明以DNA条形码为基础的基因序列分析可作为传统形态分类学强有力的辅助方法。     

Preliminary diagnoses of four new littoral species of Marine Crustacea isopoda (family sphaeromatidae)

Preliminary diagnoses are given for four new species belonging to Exosphaeroma, Dynamenella, Dynamenopsis and Amphoroidea.