Cloning and characterization of proliferating cell nuclear antigen gene of Alexandrium catenella (Dinoflagellate) with respect to cell growth

Harmful algal blooms (HABs) have been affecting negatively the shellfish and aquaculture industries around the world. Though a lot of efforts have been made to disclose the changes of environmental factors involved and their effects on the HABs events, the molecular mechanism of this process remains unclear. To address this problem, proliferating cell nuclear antigen gene (pcna) was isolated and characterized from Alexandrium catenella. It showed high homology to those of other dinoflagellates (89% and 91% homology to Pfiesteria piscicid and Pyrocystis lunula, respectively), and also 42%-43% homology to those of plant and animals. The expression level of pcna revealed by quantitative real time PCR was the lowest at the late lagging cell growth phase, increased to the highest at the late exponential phase, and then decreased at the stationary phase. Though the cell growth rate was also changing, no positive correlation between pcna expression level and cell growth rate was displayed throughout the whole cell growth stages (r²=0.024 6). However, the pcna expression level had the similar trend with the change of cell growth rate throughout the whole growing process, e.g., from increasing at the earlier cell growth stage to decreasing at the following stages, though slightly lagging to the latter.     

Effects of UVB on the expression of proliferating cell nuclear antigen (PCNA) in dinoflagellate Prorocentrum donghaiense Lu

PCNA has been considered as a useful marker for the estimation of growth rates of marine phytoplankton at the species level. Since dinoflagellates are noted for having many prokaryotic features in that they are the only eukaryotes to have permanently condensed chromosomes as well as lacking histones and a nucleosome, the sensitivity to UVB radiation and the validity of PCNA as a maker of growth rate in dinoflagellate need to be evaluated.Prorocentrum donghaiense Lu was investigated to valuate the UVB sensitivity in relation to cellular and molecular aspects of PCNA as a growth indicator.The effects of UVB radiation on PCNA were studied using the methods of western blots technology and whole-cell immunoflurescence with one mono-antibody. UVB changed the cell morphology, halted the growth and increased the cell size, even caused cell death to a certain extent after treatment with UVB radiation in P. donghaiense. Compared with the control, treating the algal cultures in exponential phases with UVB radiation for 24 h caused chromatin release and increases in protein levels of PCNA.     

Comparison of short-term toxicity of 14 common phycotoxins (alone and in combination) to the survival of brine shrimp Artemia salina

Toxic harmful algal blooms(HABs) can cause deleterious effects in marine organisms, threatening the stability of marine ecosystems. It is well known that different strains, natural populations and growth conditions of the same toxic algal species may lead to different amount of phycotoxin production and the ensuing toxicity. To fully assess the ecological risk of toxic HABs, it is of great importance to investigate the toxic effects of phycotoxins in marine organisms. In this study, the short-te...     

雨生红球藻八氢番茄红素脱氢酶pds基因上游序列的分离和分析

在某些蓝藻、绿藻和高等植物中,八氢番茄红素脱氢酶是β-胡萝卜素合成过程中的一个关键酶之一,应用巢式PCR方法从雨生红球藻中克隆了八氢番茄红素脱氢酶基因约1kb的5’上游序列。通过生物信息学方法进行序列分析,发现pds基因上游序列中包含了一些可能的顺式元件,如ABRE调控元件、C-repeat/DRE调控元件等。同时,构建了由pds-启动子控制报告基因的重组载体,并转化到雨生红球藻细胞中,进行了报告基因瞬间表达的检测。结果表明,克隆的pds启动子区域具有启动子活性,可以驱使报告基因进行瞬间表达。     

针胞藻海洋卡盾藻(Chattonella marina)和硅藻中肋骨条藻(Skeletonema costatum)藻际细菌的分离、鉴定及影响研究

对实验室培养的两株海洋微藻海洋卡盾藻和中肋骨条藻的可培养细菌进行了分离鉴定,分别在海洋卡盾藻和硅藻中肋骨条藻不同生长时期分离得到48株和34株可培养细菌,去除重复序列后得到12株不同的菌株。这些菌株分属α-变形杆菌纲、γ-变形杆菌纲、拟杆菌和放线菌。α-变形杆菌纲在两种藻的藻际环境中占据优势,其中红杆菌科是最为常见的科,中肋骨条藻的藻际细菌比海洋卡盾藻更为多样化。海洋卡盾藻生长后期细菌密度大幅度上升,可能导致了藻细胞的衰亡。中肋骨条藻相关细菌中有一株对旋链角毛藻的生长具有明显抑制作用,而大部分海洋卡盾藻相关细菌对角毛藻的生长具有抑制作用。本研究结果说明海洋卡盾藻的藻际细菌也许对其与硅藻的种间竞争中具有一定作用。     

脂肪营养对封闭循环水养殖道氏虹鳟生长、相关代谢酶及基因表达的影响

为探讨饲料脂肪营养对封闭循环水养殖道氏虹鳟(Oncorhynchus mykiss)生长、脂肪代谢及相关酶基因表达的影响,作者采用单因素设计,即4个脂肪水平——12%、15%、18%、21%(以Ⅰ、Ⅱ、Ⅲ、Ⅳ组表示),共4个处理组,每处理3重复,每重复25尾鱼。试验鱼为初始体质量(333.25±20.71)g的道氏虹鳟幼鱼,试验期77 d。结果表明,与后3组相比,Ⅰ组试验鱼增质量率显著提高17.20%~33.17%,Ⅰ和Ⅱ组饲料系数显著低于Ⅲ和Ⅳ组6.20%~20.56%(P0.05);脂肪合成酶类FAS活力随饲料脂肪水平升高而降低,脂肪分解酶类LPL、HL及L-CPTⅠ活力变化特征与之相反(P0.05)。其中,Ⅰ组FAS活力显著高于Ⅲ、Ⅳ组7.5%、8.7%;L-CPTⅠ活力显著低于后3组13.08%~16.35%;Ⅳ组LPL活力显著或极显著高于前3组18.8%~44.7%(P0.05或P0.01);I组肝脏FAS的mRNA表达量比后3组显著高48.29%~55.15%(P0.05);LPL呈相反特征,Ⅳ组显著高于前3组36.72%~113.59%(P0.05或P0.01);Ⅰ组肌肉FAS mRNA表达量显著高于Ⅳ组66.82%(P0.05);LPL表达丰度随脂肪水平升高先下降后显著上升(P0.05)。该结果特征与肝脏中该两种酶活力变化具有同步性。研究发现,随饲料脂肪水平变化,肌肉FAS mRNA表达量变化比肝脏更明显且规律性更强,而肝脏LPL mRNA表达量变化较肌肉更明显。本试验初步确定,在封闭循环水养殖模式下,330 g左右道氏虹鳟饲料蛋白水平在45%时,脂肪水平以不超过12%为宜。