种间竞争是生物普遍存在的一种生命现象,可以利用来调控生物的生长和数量变化,进行有害生物的防治。藻类植物间也存在明显的竞争现象。Holm[8]报道了硅藻和微囊藻种间的相互作用。Hegarty[9]研究了光强和N、P比对棕囊藻和5种硅藻间竞争的影响。Kuwata[10]研究了铵盐对绿藻和蓝藻间竞争作用的影响。Davis[11]研究了海藻和海草间的竞争。Piazzi[12]研究了两种海洋绿藻生长的竞争情况。刘世枚[1]研究了两种绿藻种群间的相互作用。陈德辉等[2]对微囊藻和栅藻共培养进行了研究并计算了竞争参数。。绿色巴夫藻(Pavlovaviridis)是一种可作为中国对虾幼体和海湾扇贝幼虫饵料的海洋微藻[3]四列藻 Tetraselmiste-trethele)也是一种常用作对虾、蟹育苗期饵料的海洋微藻[4]。通过和四列藻共培养试验,深入分析其竞争机制,能为虾蟹育苗期人们选择饵料藻种、培养和调控微藻生长提供理论依据

四列藻在营养限制胁迫下培养l0d后,在恢复营养进行培养的初期(l～5d),表现出较强的超补偿生长能力。与持续正常营养培养的对照组比较,两者间的生长表现出显著差异(P<0.05)。四列藻超补偿生长的主要特征表现是在恢复营养进行培养的初期,处理组的藻细胞比对照组平均相对生长率提高,细胞数增多,叶绿素a含量和生物量增高,细胞数净增率最高达68.2%～121.1%,生物量净增率最高达21.8%～95.3%。随着培养时间的推移,由于环境容量的限制,处理组与对照组之间的差异逐渐减小。到了培养的后期,处理组和对照组的各生长参数都趋于一致。同时发现,在受到营养限制胁迫后,藻细胞内蛋白质、细胞内糖和蛋白质/糖(P/C)的比值发生了变化,但是在恢复营养进行培养lOd后,均基本上恢复至处理前的水平。藻类中存在的这种超补偿生长特性有可能是引起藻华和赤潮的一个生物内在因素。

The perennial chenopod sub-shrub Artemisia halodendron Turcz. ex Bess. is endemic to the semi-xed and mobile sand dunes in Inner Mongolia of northern China and is an important sand-stabilizing plant. A. halodendron can persist through either sexual reproduction (seed- ling recruitment) or vegetative propagation. However, it is not known if there are differences in patterns of reproductive allocation in A. halodendron inhabiting semi-xed and mobile habitats. To characterize this, a test of eld measurements was conducted on two typical semi-xed and mobile sand dune habitats. In each habitat, 120 individual A. halodendron plants were randomly sampled at the time of seed production to examine changes in some reproductive characters including the number of owering shoots, dry weight of owering shoots, dry weight per owering shoot, dry weight of seed, and reproductive effort (RE = seed dry weight/total above-ground dry weight) between habitats. Although total above-ground dry weight and dry weight of vegetative biomass were similar between habitats, plants inhabiting the less eroded semi-xed habitat produced more owering shoots, greater dry weight of owering shoots, dry weight of seed and RE than those inhabiting the more eroded mobile habitat. This suggests that sexual reproduction is relatively favored by plants from the semi-xed habitat, whereas vegetative propagation is favored by plants from the mobile habitat. The allocation of resources to reproduction was size-dependent and specic to habitats sampled. Reproductive biomass and the number of owering shoots per plant increased with increasing vegetative biomass, with plants in the semi-xed habitat producing more owering shoots and greater reproductive biomass than plants in the mobile habitat. Plant size did not inuence RE, indicating that allocation of resources to reproduction appeared to be a constant proportion across all plant sizes sampled.

The single-chain insulin (PIP) can spontaneously fold into native structure through preferred kinetic inter-mediates. During refolding, pairing of the first disulfide A20–B19 is highly specific, whereas pairing of the second disulfide is likely random because two two-disulfide intermediates have been trapped. To get more details of pairing property of the second disulfide, four model peptides of possible folding intermediates with two disulfides were prepared by protein engineering, and their properties were analyzed. The four model peptides were named [A20–B19, A7–B7]PIP, [A20–B19, A6–B7]PIP, [A20–B19, A6–A11]PIP, and [A20– B19, A7–A11]PIP according to their remaining disulfides. The four model peptides all adopt partially folded structure with moderate conformational differences. In redox buffer, the disulfides of the model peptides are more easily reduced than those of the wild-type PIP. During in vitro refolding, the reduced model peptides share similar relative folding rates but different folding yields: The refolding efficiency of the reduced [A20–B19, A7–A11]PIP is about threefold lower than that of the other three peptides. The present results indicate that the folding intermediates corresponding to the present model peptides all adopt partially folded conformation, and can be formed during PIP refolding, but the chance of forming the intermediate with disulfide [A20–B19, A7–A11] is much lower than that of forming the other three intermediates.

以绿色巴夫藻（Pavlova viridis）为实验材料,设置了18、36、54、65、86和108J．m-2 6个UV-B辐射剂量处理组,以无紫外辐射为对照,解除胁迫后,处理组和对照组在相同接种密度和相同条件下培养12d,测定了生长过程中的吸光值、生物量、叶绿素a、类胡萝素、可溶性蛋白质和胞内多糖含量,结果表明,在UV-B胁迫下,绿色巴夫藻细胞生长受到显著抑制,6个处理组细胞的相对增长率比对照下降了16.15%-60.00%(P<0.05)．但在胁迫解除后,各胁迫处理的藻细胞生长指标均显著高于对照(P<0.05),证明绿色巴夫藻在胁迫后的恢复生长中出现超补偿生长现象,恢复培养第12天,最大吸光值、生物量、叶绿素a、类胡萝素、可溶性蛋白质和胞内多糖含量分别比对照提高了22. 38%、15.00%、26.15%、23.81%、11.63%和27.58%．藻类中存在超补偿生长特性为微藻生物活性物质的开发提供了有效途径,