Population Growth of Zooplankton (Rotifers and Cladocerans) Fed Chlorella vulgaris and Scenedesmus acutus in Different Proportions

In the present work we tested the effect of Chlorella vulgaris and Scenedesmus acutus in different proportions on the population growth of Brachionus calyciflorus, Brachionus patulus, Ceriodaphnia dubia, and Moina macrocopa. In general, both rotifer species grew well on either type of algae. Regardless of algal mixture, B. calyciflorus had a shorter initial phase, while B. patulus needed more than a week to begin the exponential phase of growth. Both the rotifer species showed consistently better population growth with Chlorella than on Scenedesmus, or the mixture. At any given algal combination, B. patulus had higher peak values than B. calyciflorus. The rate of population increase (r) for both the rotifers varied from 0.18 to 0.48 d^—1 depending on the algal type and combination. Regardless of algal type and combination, B. calyciflorus had a much higher value of r than B. patulus. Both C. dubia and M. macrocopa grew on the algal types, whether offered separately or in mixture. Regardless of the treatment type, C. dubia needed a longer period (about 2 weeks) than M. macrocopa to reach peak abundances. Thus, our study did not support the view that Scenedesmus is consistently superior to Chlorella as a basic diet to the tested species of zooplankton.     

角突网纹溞在太湖微囊藻群体形成中的作用

将太湖微囊藻水华中3种优势微囊藻包括水华微囊藻1028、惠氏微囊藻929、铜绿微囊藻469和铜绿微囊藻905培养在改良后的BG-11培养基(TN=10mg/L,TP=0.4mg/L)中,然后加入角突网纹搔,以研究3种优势微囊藻对浮游动物摄食压力的形态反应.整个实验共进行了12d.除了水华微囊藻1028以外,在惠氏微囊藻929、铜绿微囊藻469和铜绿微囊藻905中没有观察到有大群体(大于10个细胞)的出现.在水华微囊藻中,处理组大群体细胞所占总细胞的比例与对照组显著不同,其中对照组占22%,而试验组占53%.水华微囊藻对照组和处理组中单细胞、2细胞、小群体(3-10个细胞)和大群体(大于10个细胞)细胞密度存在显著的不同.实验第6-12d,水华微囊藻对照组和试验组单位大群体细胞数量存在显著差异.研究结果表明,角突网纹潘的摄食压力不能促使惠氏微囊藻929、铜绿微囊藻469和铜绿微囊藻905形成大群体.角突网纹溞的摄食促使水华微囊藻形成更大的群体.     

一种基于干扰肌动蛋白基因导致方形网纹溞(Ceriodaphnia quadrangula)死亡的RNA干扰(RNAi)模型构建

方形网纹溞(Ceriodaphnia quadrangula)可作为研究水生动物生物学的良好模式动物。为探索细菌介导表达的双链RNA(dsRNA)对方形网纹溞进行RNA干扰(RNAi)技术是否可行,本研究构建了方形网纹溞肌动蛋白(actin)基因的干扰载体Actin-L4440,并将其转入大肠杆菌HT115。此宿主菌经异丙基-β-D-硫代吡喃半乳糖苷(IPTG)诱导后能表达actin基因部分片段的dsRNA。将此宿主菌投喂方形网纹溞,能抑制其体内actin基因的表达,并导致方形网纹溞死亡率明显提高。本研究成功构建了方形网纹溞的RNAi模型,为以后的研究提供了一定的参考。