来自中国北方部分地区33株孢子丝菌菌株的表型和基因型鉴定

孢子丝菌病是一种临床常见的真菌感染疾病,近期有研究认为其致病菌是由多个同形种构成的复合体。为明确我国孢子丝菌病致病菌的生理学以及分子生物学方面的特点,对33株分离自我国孢子丝菌病患者组织的病原菌进行了研究,首先检测其在37℃是否生长以及PDA培养基上生长21d的菌落直径,其次检测其糖同化特点,最后对其钙调蛋白(Calmodulin,CAL)基因进行PCR扩增、序列测定以及系统进化分析。结果显示,这些菌株全部为球形孢子丝菌Sporothrix globosa,说明我国孢子丝菌病的病原菌可能以球形孢子丝菌为主。     

棕囊藻北部湾株的18S rDNA分子鉴定

为研究北部湾棕囊藻(Phaeocystis)藻华的成因,采用PCR克隆了棕囊藻北部湾株核糖体18S r DNA序列。结果表明,棕囊藻北部湾株具有游动单细胞与群体结构两种形态;其18S r DNA序列和NCBI基因库中球形棕囊藻(Phaeocystis globosa)的同源性为99%~100%,在系统进化树上与不同海域来源的球形棕囊藻聚在一大分支上,且与球形棕囊藻间的遗传距离均小于其他种。首次从分子生物学上确定棕囊藻北部湾株为球形棕囊藻。     

稻秆浸泡化学组分变化对抑制球形棕囊藻（Phaeocystis globosa）生长的影响

设置涉及灭菌与否、通气与否和光照与否等的8个浸泡条件,考查和比较了不同条件浸泡下获得的浸出液的抑藻作用和化学成分,以明确微生物、光照和通气情况对秸杆抑制藻类生长的影响,揭示秸杆抑藻的化学基础。研究发现,不同条件浸泡后获得的浸出液的抑藻作用存在很大差别,浸出液化学成分也有显著不同。即使浸泡条件相同,随着浸泡时间的延长,抑藻作用和化学成分也会发生很大变化。未灭菌组、通气组和光照组的抑藻作用并不一定强于相应的灭菌组、不通气组和避光组。提示微生物、光照和通气并非一定能够促进秸杆的抑藻作用,秸杆中抑藻物质的释放和产生是多个因素综合作用的结果,单一因素对秸杆抑藻作用的影响要受其他因素的干扰。绝大部分抑藻作用强的浸出液中脂肪酸、酚酸类物质含量比较高,但有些浸出液抑藻作用强,但脂肪酸、酚酸类物质含量并不高;有些浸出液抑藻作用很弱,但脂肪酸、酚酸类物质含量很高。这些结果提示,脂肪酸、酚酸类物质在稻秆抑制藻类生长中扮演重要作用。除了脂肪酸和酚酸类物质外,稻秆自身或稻杆降解过程中还可产生其他可以显著抑制和促进藻类生长的物质。     

Biosorption of cadmium and chromium in duckweed Wolffia globosa

The biosorption of cadmium (Cd) and chromium (Cr) by using dried Wolffia globosa biomass were investigated using batch technique. The effects of concentration and pH solution on the adsorption isotherm were measured by determining the adsorption isotherm at initial metal concentrations from 10 to 400 mg/L and pH 4 to 7 for Cd, and pH 1.5 to 6 for Cr. The adsorption equilibria were found to follow Langmuir models. The maximum adsorption capacity (Xm) at pH 7 in W. globosa-Cd system was estimated to be 80.7 mg/g, while the maximum removal achieved at pH 4, pH 5, and pH 6 were 35.1, 48.8, and 65.4 mg/g, respectively. The Xm at pH 1.5 in W. globosa--Cr system was estimated to be 73.5 mg/g, while the maximum removal achieved at pH 3, pH 5, and pH 6 were 47.4, 33.1, and 12.9 mg/g, respectively. The effects of contact times on Cd and Cr sorption indicated that they were absorbed rapidly and more efficiently at lower concentrations.     

Characterization of the Hemolytic Properties of an Extract from Phaeocystis globosa Scherffel

Phaeocystis globosa Scherffel, an organism that causes harmful algal blooms, is a genus of the family Prymnesiophyta (or Haptophyta) with eurythermal and euryhaline characteristics. P. globosa has been confirmed to produce hemolytic substances, which are a mixture of liposaccharides. In the present study, the hemolytic properties of extract ofP. globosa are analyzed further. The effects of temperature, pH,different divalent cations, and membrane lipids on extract-induced hemolysis are discussed, as is the possible hemolytic mechanism. The results of the present study showed that the hemolytic activity of the extract was approximately 127.1 hemolytic units (HU)/L. The hemolytic reaction became fastest and a 50% decrease in absorbance was induced at 30 min at 37 ℃, and at pH 7.0; Hg2 was the strongest inhibitor of the hemolysis compared with the other divalent cations and many membrane lipids, except for phosphatidic acid, inhibited the hemolytic activity to different degrees. These results suggest that the toxin may make pores in the surface of red blood cells and that Hg2 either combines with the hemolysin or closes the pores,hence inhibiting its further hemolytic reaction. The toxin probably has no specific membrane receptor in the red blood cell membrane.     

Dynamics of transparent exopolymeric particles (TEP) production by Phaeocystis globosa under N- or P-limitation: a controlling factor of the retention/export balance

The concentration of transparent exopolymeric particles (TEP) was monitored during Phaeocystis globosa blooms that developed in mesocosms under different initial N:P ratios (from N- to P-limited conditions). TEP concentration was measured using the microscopic (TEP_micro, ppm) and the colorimetric (TEP_color, Xanthan equiv. L⁻¹) methods. TEP concentrations varied from 5 to >75 ppm and from 60 to >1500 μg Xanthan equiv. L⁻¹, and were relatively low until the mesocosms reached nutrient (either N or P) depletion and then increased abruptly. From the TEP_micro versus TEP_color concentrations comparison and from their relation to chlorophyll a concentrations, two phases for the dynamics of TEP production were identified: (1) production through active release of precursors during the growth phase of P. globosa — defined as TEP₁ — and their integration into the TEP pool through coagulation processes; (2) release of large TEP from the mucilaginous matrix of P. globosa colonies subsequent to disruption caused by nutrient depletion — defined as TEP₂ — and their direct integration into the TEP pool outside the constraint of coagulation. The formation of a multiorigin TEP pool during P. globosa blooms may have implications for the fate of the blooms, due to difference in TEP bioreactivity according to their source and to difference in timing and intensity of TEP₁ versus TEP₂ production according to N- or P-depletion. For P. globosa blooms developing under N-limiting conditions, the transition from the first source (i.e. TEP₁) to the second one (i.e. TEP₂) was a slow and continuous process. In contrast, the P. globosa bloom developing under P-limiting conditions showed the sudden formation of heavy mucous aggregates when P became depleted, that may have been caused by a massive release of TEP₂. Our study suggests that the nutrient regime may control the export vs. retention balance during P. globosa blooms, via production of a multiorigin TEP pool.     

Phytoaccumulation and phytotoxicity of cadmium and chromium in duckweed Wolffia globosa

The phytoaccumulation and phytotoxicity of heavy metals, cadmium (Cd), and chromium (Cr) on a common duckweed, Wolffia globosa, were studied. W. globosa were cultured in 3% Hoagland's nutrient medium, which was supplemented with 1, 2, 4, and 8 mg/L of Cd and Cr and were separately harvested after 3, 6, 9, and 12 days. The accumulation of Cd and Cr in W. globosa showed significant increases when the exposure time and metal concentration were increased. The effects of Cd and Cr on the biomass productivity and total chlorophyll content in W. globosa indicated that there were significant decreases in the biomass productivity and total chlorophyll content when the exposure time and metal concentration were increased.     

红树植物木榄有机溶剂提取物对球形棕囊藻的抑制效应

基于化感作用原理,利用有机溶剂对红树植物木榄(Bruguiera gymnorrhiza)叶片中的活性物质进行连续提取分离,分别得到正己烷相、乙酸乙酯相、正丁醇相和水相提取物。利用这些提取物进行抑藻实验,通过测定球形棕囊藻(Phaeocystis globosa)的细胞密度发现:四种组分提取物对球形棕囊藻均具有显著的化感抑制作用;正己烷相和乙酸乙酯相提取物对球形棕囊藻的抑制效果明显优于正丁醇相和水相提取物的抑制效果。正己烷相提取物和乙酸乙酯相提取物对球形棕囊藻的48hEC₅₀分别为14.90mg/L和12.18mg/L。研究表明,藻细胞初始接种密度影响提取物的抑藻效应,低接种密度时抑制率极高,而随着接种密度的升高抑制率下降;接种密度极高时,提取物不但不会抑制甚至还会促进藻细胞的生长。     

中国顶丝藻科新记录Ⅲ

继续报导中国顶丝藻科新记录6种。渐尖旋体藻Audouinella attenuata,球状旋体藻A.globosa,纤细旋体藻A.gracilis,无柄旋体藻A.hypneae,偏枝旋体藻A.secundata,连续旋体藻A.seriata。