小球藻紫外线诱变及高产藻株筛选

利用单细胞分离技术和紫外诱变育种技术,筛选高产小球藻株。通过单细胞分离技术获得的藻株Chlorella vul-garisQ7,生长速度和蛋白含量均优于其它藻株。以C.vulgarisQ7为出发株,进行紫外诱变,从120株诱变单克隆中筛选出3个株系:M51,M59,M73。与出发株相比,突变株M51,M59,M73的生长速率分别提高了6.23%,3.8%,5.92%。蛋白含量分别提高了2.5%,3.1%,1.9%。研究了诱变株的最适生长条件,结果表明在140μmol.m-2.s-1,25℃时,诱变株具有最大的生长速率和生物量。探讨了诱变株的遗传稳定性,结果表明诱变株可稳定遗传。     

不同环境下镉对小球藻吸收磷速率的影响

在人工配制的污水中进行静态模拟实验,研究了不同光照强度及不同pH值下,镉对小球藻(Chlorella vulgaris)在悬浮和固定状态下对污水中正磷酸盐的吸收速率的影响。结果表明,镉存在的情况下,在实验所设的各光照强度内,悬浮态小球藻对磷的吸收速率为4~10μg/(h.个),固定化小球藻为12~16μg/(h.个);而相同的镉浓度下,在不同的pH范围中,悬浮态小球藻对磷的吸收速率为1.9~9.4μg/(h.个),固定化小球藻为5.7~12μg/(h.个)。在不同光照强度下,镉总体上降低了小球藻对磷的吸收速率,其中使悬浮藻普遍下降40%~60%,而固定处理使藻受镉的影响较少,至多下降10%~20%,但在个别光照强度下镉反而促进了小球藻对磷的吸收速率。不同pH值时,无论悬浮态还是固定态,镉在大多pH下使小球藻的磷吸收速率下降20%~30%,固定处理并没有减少镉的影响,同样在个别pH下镉促进了对磷的吸收。     

Role of sea surface temperature and rainfall in determining the stock and fishery of the common octopus (Octopus vulgaris,Mollusca, Cephalopoda) in Tunisia

Octopus (Octopus vulgaris, Mollusca, Cephalopoda) is an important and valuable fishery resource on the eastern and southern coasts of Tunisia, but its landings are highly variable. This paper explores the effect of environment on octopus catch per unit effort (CPUE) during a 12‐year period, through correlation analyses and the incorporation into surplus production models of sea surface temperature (SST) and rainfall data collected during cold (January–May) and hot (August–October) seasons. CLIMPROD software was used to select the appropriate model and fit it to the fishery and environment data. In both seasons, SST significantly contributed to CPUE variability; fishery production was influenced positively by cold season SST but negatively by hot season SST. Due to a poor fit with cold season data, the impact of rainfall was analysed only for the hot season, during which it has a positive effect on production. Results are discussed in view of the life‐cycle of octopus and the dynamics of the Tunisian fishery. This first study of octopus variability in Tunisia highlights the necessity to incorporate environmental influence into stock assessment and management advice.     

Genetic diversity analysis with ISSR PCR on green algae Chlorella vulgaris and Chlorella pyrenoidosa

In the present study, genetic polymorphism and diversity in unicellular clones of Chlorella vulgaris Beijerinck and Chlorella pyrenoidosa Chick were studied with Inter Simple Sequence Repeats PCR (ISSR PCR). Samples including four clones of C. vulgaris and three clones of C. pyrenoidosa were purified by single-clone-choice method. For four C. vulgaris unicellular clones, the total number of the bands scored for 18 primers was 298; and the number of the polymorphic bands was 118, of which 39.6% were polymorphic. The size of PCR products ranged from 200 to 2 500 bp. The total number of bands scored for 18 primers, the number of polymorphic bands and the percentage of three C. pyrenoidosa unicellular clones was 194.83 and 30.8%, respectively. POPGENE analysis show that the average Nei genetic diversity (h *) and Shannon index of diversity (I *) in the four C. vulgaris unicellular clones was 0.2181 and 0.3208, respectively, which is slightly higher than those of the three C. pyrenoidosa unicellular clones (0.190 3 and 0.274 8), which agreed with the percentage of polymorphic bands in the mixed samples of the two species. The results suggest that ISSR is a useful method to Chlorella for intra-species genetic analysis.     

毛乌素沙地臭柏、油蒿细根分解过程中养分与能量的变化

应用埋袋法对毛乌素沙地天然分布的优势种臭柏、油蒿细根分解进行研究。对两年的实验数据进行分析,结果显示,臭柏、油蒿细根分解过程中C、P、K、Mg均表现为释放,释放率油蒿＞臭柏,元素重量损失率K＞P＞C＞Mg;N在臭柏分解中表现为积累,在油蒿分解中表现为释放;Ca在臭柏、油蒿细根分解中都表现为积累的趋势,积累率为油蒿＞臭柏;能量在臭柏、油蒿细根分解过程中表现为释放。该研究为沙区土壤库中的能量转化和流动过程提供了理论依据。     

毛乌素沙地臭柏根系分布及根量

毛乌素沙地臭柏(Sabina vulgaris)灌丛根量、根系直径和分布特征的研究结果表明,臭柏根系分布深度可达2.0 m,水平延伸幅度达灌丛边缘以外1.0 m左右处;其根量主要集中在0~60 cm的土层内,占根系总量的60%~70%,呈倒金字塔型分布。根系直径以< 3 mm的细根居多,占剖面总根量的72%左右,集中分布在0~30cm的土层中。> 7 mm的粗根数量很少,占总根数的0%~5%。臭柏根量和直径分布特征依立地条件及土层深度的不同而异。     

川蔓藻在再生水体中对普通小球藻的化感作用

采用川蔓藻植株体与普通小球藻在再生水中共培养和使用再生水种植川蔓藻的种植水纯培养普通小球藻的方法,在实验室条件下研究了在滨海再生水河道中生长的沉水植物川蔓藻对小球藻的化感作用.结果表明,川蔓藻对普通小球藻具有显著的抑制作用.在共培养实验中,96 h的抑制率为88.86%;在种植水纯培养实验中,96 h的抑制率为48.91%.川蔓藻的种植水对普通小球藻的化感作用系数平均为-0.2448.川蔓藻的叶和根的种植水对普通小球藻均有抑制效果,96 h的抑制率为叶34.71%,根14.12%;平均的化感作用系数叶为-0.1317,根为-0.0901;川蔓藻的根和叶均能释放化感物质,但抑制小球藻的化感物质主要通过叶释放.     

小球藻和铜绿微囊藻的高浓度Chl-a高光谱定量模型

本研究将地物高光谱遥感技术应用于室内实验,从而得到小球藻和铜绿微囊藻的高光谱特征.通过多种半经验方法,如单波段、波段比值和微分法,建立了两藻种最优的Chl-a高光谱定量模型,并与室外情况进行了对比.结果表明:小球藻的最优定量模型为Chl-a=174.6 1138292(R703) 2.3(109[(R703)]2(p＜0.01),相应的方法适宜性为:一阶微分法＞单波段法＞波段比值法;铜绿微囊藻的最优定量模型为Chl-a=5299164(R757)1.9773(p＜0.01),相应的方法适宜性为:单波段法＞波段比值法＞一阶微分法;从高光谱特征来看,小球藻在540 nm和700 nm附近存在明显的特征波峰,其位置随Chl-a浓度增大而向长波方向偏离,铜绿微囊藻在530 nm、660 nm和700 nm附近存在3个较强的特征波峰,在610 nm和680 nm附近存在明显的波谷;与以往室外研究不同的是铜绿微囊藻的反射率在400-500 nm之间的R值并不低,是因为没有非藻类颗粒物的影响,总吸收明显降低.