A wind tunnel comparison of the rotorod and samplair pollen samplers

Summary The relative sampling efficiency of the Samplair (Allergenco Inc.) and Rotorod samplers (Sampling Technologies Inc.) were compared for different conifer pollen sizes and at different wind speeds. The wind tunnel experiments conducted with the two samplers are valid for the range of wind speeds and conifer pollen types which might be expected in seed orchards in Canada. A Quadratic relationship was established between the two samplers which revealed a decrease in relative efficiency on the part of the Samplair as compared to the Rotorod at wind speeds less than 5 m/s. An apparent increase in the efficiency of the samplair at higher wind speeds resulted from a decrease in the sampling ability of the rotorod.     

两种密码子优化的Cas9编码基因在斑马鱼胚胎中基因敲除效率的比较

为在斑马鱼中获得特异且高效的基因敲除,多个实验室独立人工合成了序列彼此不一的Cas9 cDNA序列,并克隆入不同的体外转录载体。本文选取两种斑马鱼密码子优化的Cas9编码序列(zCas9_bz和zCas9_wc),对斑马鱼胚胎中的7个基因(外源egfp及内源chd、hbegfa、th、eef1a1b、tyr、tcf7l1a)分别进行敲除,通过PCR产物测序、克隆测序和表型分析比较了两种Cas9的敲除效率。结果发现,zCas9_wc在各种情况下都显现出较高的敲除效率,而zCas9_bz的效率相对较低。     

模拟光条件下禾本科植物和藜科植物蒸腾特性与水分利用效率比较

利用人工模拟光源研究了两种 C4 光合途径禾本科植物 (虎尾草、狗尾草 )和两种 C3光合途径藜科植物 (藜、绿藜 )的光合速率 ( Pn)、蒸腾速率 ( Tr)、水分利用率 ( WUE)、气孔导度 ( Gs)、胞间 CO2 浓度 ( Ci)及叶面饱和蒸气压亏缺 ( Vpdl)随模拟光辐射 ( SPR)增强的变化规律及 Gs、Ci、Vpdl对 Tr和 WUE的影响。结果表明 :( 1 ) 4种植物的 Pn和 Tr均随 SPR增强而增大 ,两种藜科植物最大净 Pn和 Tr均高于两种禾本科植物的最大净 Pn和 Tr。 ( 2 ) WUE随 SPR增强先增大后减小 ,两种禾本科植物和两种藜科植物分别在SPR为 40 0、1 2 0 0 μmol/( m2·s)时达到最大值 ,禾本科植物的最大 WUE明显高于藜科植物。 ( 3) 4种植物的 Gs、Ci均随 SPR的增强而减小 ,两种藜科植物的 Gs和 Ci均显著高于两种禾本科植物。4种植物的 Vpdl均随 SPR增强而增大 ,禾本科植物高于藜科植物。实验表明 ,在以水分为限制因素的半干旱草原区 ,禾本科植物具有更好的保水机制和更高的水分利用效率 ,与藜科植物相比 ,在水分生态上具有一定的竞争优势。     

Introducing extra NADPH consumption ability significantly increases the photosynthetic efficiency and biomass production of cyanobacteria

Increasing photosynthetic efficiency is crucial to increasing biomass production to meet the growing demands for food and energy. Previous theoretical arithmetic analysis suggests that the light reactions and dark reactions are imperfectly coupled due to shortage of ATP supply, or accumulation of NADPH. Here we hypothesized that solely increasing NADPH consumption might improve the coupling of light reactions and dark reactions, thereby increasing the photosynthetic efficiency and biomass production. To test this hypothesis, an NADPH consumption pathway was constructed in cyanobacterium Synechocystis sp. PCC 6803. The resulting extra NADPH-consuming mutant grew much faster and achieved a higher biomass concentration. Analyses of photosynthesis characteristics showed the activities of photosystem II and photosystem I and the light saturation point of the NADPH-consuming mutant all significantly increased. Thus, we demonstrated that introducing extra NADPH consumption ability is a promising strategy to increase photosynthetic efficiency and to enable utilization of high-intensity lights.     

Design of an ON/OFF mist duty cycle in mist bioreactors for the growth of hairy roots

In this study, we designed a strategy for selecting the operating conditions of a mist reactor for the growth of hairy roots. This was accomplished by developing a mathematical model to optimize the ON/OFF mist duty cycle for the specified growth of hairy roots. The availability and rate of transport of nutrients to the roots are important parameters in the design and operation of the reactor. The thin liquid film over the root surface, which continuously builds up during the ON cycle, is a major factor that limits mass transfer. The same film also acts as a finite reservoir of nutrients in the absence of any replenishment during the OFF cycle. This reservoir gets depleted as growing roots continue to consume the nutrients. As a result of this depletion the duration of the OFF cycle must be limited such that the nutrient concentration does not go below the critical value required for the specified growth rate. The depleted reservoir is then replenished during the next ON cycle to an extent that depends on feed concentration and duration of the next ON cycle. It was shown that the use of increasing feed concentrations in the fed-batch mode of operation could maintain a specified growth rate in the reactor. Interestingly, this also resulted in the efficient operation of the reactor whereby the reactor operated at slightly above the required concentration and close to the point of minimum mass transfer resistance.     

Physiological foundation for the differences of long-term water use efficiency among Populus deltoides clones

With randomized complete block design, long-term water use efficiency (WUE_L), photosynthetic parameters (net photosynthetic rate Pn, transpiration rate Tr, stomatal conductance Gs, instantaneous water use efficiency WUE_i, maximum photosynthetic rate P max, light saturation pointLSP, carboxylic efficiency Ce), stomatal properties (frequency, size, superior/inferior stoma amount ratio) and root/shoot ratio of twelve Populus deltoids clones were studied under water stress in a greenhouse. Four water treatments were designed, namely, well-watered condition, slight water stress, moderate water stress, and severe water stress. Although the volumes of irrigated water for different treatments were the same, the irrigation intervals were strictly controlled. The results showed that long-term water use efficiency (WUE_L) differences among tested clones were obvious and became greater with the increase in water stress. J₂, J₆, J₇, J₈, and J₉ were excellent clones with high WUE_L. Stomatal frequency, stomatal size, Gs, Tr, Pn, and root/shoot ratio of J₂et al were moderate, whereas the superior/inferior ratio, P_max, LSP, Ce of J2et al were higher than other clones. The interrelations between WUE_L and the physiological parameters were analyzed. The results revealed that the WUE_L differences were induced by a series of physiological parameters, and clones with higher WUE_L always had strong photosynthetic capacity, higher WUE_i, and optimum root/shoot ratio.     

Physiological energetics of the zebra musselDreissena polymorpha in lakes III. Metabolism and net growth efficiency

Oxygen consumption and ammonia excretion of the zebra musselDreissena polymorpha from 3 sites in lakes were estimated regularly over the course of 1 1/2 years at ambient temperature. They showed a pronounced annual cycle, when expressed in absolute terms (at standard shell length) and in weight specific terms (at standard tissue weight). The atomic ratio of oxygen consumed to ammonia-N released (O/N ratio) was lowest in late summer at all sites (10 to 20) and highest during winter and spring (50 to > 100). The mean body weight exponent pooled from these sites was 0.78 (95% confidence interval±0.07) for the oxygen consumption rate and 0.80 (confidence interval±0.10) for the ammonia excretion rate. Both oxygen consumption and ammonia excretion were significantly correlated with the water temperature at the 2 shallow water sites, where temperature variation was most pronounced. Correlation with seston content or gonad volume were insignificant at these sites. The quotient of filtration capacity to oxygen consumption rate was about 3 times higher at the site with the poorest food conditions compared to the other sites. Net growth efficiency was highly variable; its annual average was 35 to 40 per cent and independent of locality and animal size.