A dynamic, architectural plant model simulating resource-dependent growth

BACKGROUND AND AIMS: Physiological and architectural plant models have originally been developed for different purposes and therefore have little in common, thus making combined applications difficult. There is, however, an increasing demand for crop models that simulate the genetic and resource-dependent variability of plant geometry and architecture, because man is increasingly able to transform plant production systems through combined genetic and environmental engineering. MODEL: GREENLAB is presented, a mathematical plant model that simulates interactions between plant structure and function. Dual-scale automaton is used to simulate plant organogenesis from germination to maturity on the basis of organogenetic growth cycles that have constant thermal time. Plant fresh biomass production is computed from transpiration, assuming transpiration efficiency to be constant and atmospheric demand to be the driving force, under non-limiting water supply. The fresh biomass is then distributed among expanding organs according to their relative demand. Demand for organ growth is estimated from allometric relationships (e.g. leaf surface to weight ratios) and kinetics of potential growth rate for each organ type. These are obtained through parameter optimization against empirical, morphological data sets by running the model in inverted mode. Potential growth rates are then used as estimates of relative sink strength in the model. These and other 'hidden' plant parameters are calibrated using the non-linear, least-square method. KEY RESULTS AND CONCLUSIONS: The model reproduced accurately the dynamics of plant growth, architecture and geometry of various annual and woody plants, enabling 3D visualization. It was also able to simulate the variability of leaf size on the plant and compensatory growth following pruning, as a result of internal competition for resources. The potential of the model's underlying concepts to predict the plant's phenotypic plasticity is discussed.     

水稻淀粉胚乳程序性细胞死亡中的去核化

对水稻品种中籼8836淀粉胚乳细胞的去核化发育阶段的细胞超微结构变化和同期籽粒灌浆速率及相关酶活性的动态进行了观察和分析。开花受精后约在第3天胚乳完成细胞化,花后第5天少数淀粉胚乳细胞启动去核发育过程。核消亡是淀粉胚乳细胞程序性细胞死亡(PCD)的第一步。同一籽粒淀粉胚乳细胞的去核进程是不同步的。花后第13天所有淀粉胚乳细胞都已完成去核过程。在去核过程中,胚乳核的形态变化特征既有动植物PCD的共性又有其特殊性。伴随核降解过程,一部分线粒体解体,表明去核化与线粒体解体有一定联系。在去核化发育阶段,与PCD有关的酶类,如超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性非常高;与淀粉合成有关的酶类,如ADPG焦磷酸化酶、可溶性淀粉合成酶(SSS酶)、淀粉分支酶(或Q酶)也表现出很高的活性。去核化发育阶段籽粒灌浆速率最高,籽粒增重亦最快。淀粉胚乳细胞去核之后,细胞并未立即死亡,这些无核的细胞仍维持正常有序的代谢活动,继续进行淀粉和贮藏蛋白的合成与积累,但上述酶类的活性明显降低,灌浆速率也明显趋缓。淀粉胚乳细胞最终被贮藏物质充满时成为死细胞,完成其程序性死亡过程。Evan‘s blue染色鉴定表明淀粉胚乳细胞死亡不同步,细胞死亡在淀粉胚乳组织中是随机发生的。     

A new factor in the Aedes aegypti immune response: CLSP2 modulates melanization

Microbial infections in the mosquito Aedes aegypti activate the newly identified CLSP1 and CLSP2 genes, which encode modular proteins composed of elastase-like serine protease and C-type lectin domains. These genes are predominantly regulated by the immune deficiency pathway, but also by the Toll pathway. Silencing of CLSP2, but not CLSP1, results in the activation of prophenoloxidase (PPO), the terminal enzyme in the melanization cascade, suggesting that CLSP2 is a negative modulator of this reaction. Haemolymph PPO activation is normally inhibited in the presence of Plasmodium parasites, but in CLSP2-depleted mosquitoes, the Plasmodium-induced block of melanization is reverted, and these mosquitoes are refractory to the parasite. Thus, CLSP2 is a new component of the mosquito immune response.     

Upgrading of high-boiling fraction of bio-oil in supercritical methanol

In this work, the upgrading reactions of high-boiling fraction (HBF) of bio-oil were carried out over a series of supported mono- and bi-metallic catalysts under the supercritical methanol condition. During these reactions, esterification and cracking (alcoholysis and hydrocracking) were the two dominant processes. PtNi/MgO exhibited good performance, and gave a high yield (72.4 wt.%) of refined oil. The acid-base properties of the supports have an important effect on the coke deposition on the catalyst surface. The acidic catalysts gave the somewhat lower product yields, but tended to inhibit coking reaction. This would improve the life of the catalysts in the practical applications. The refined oil is believed to be a potential substitute or partial substitute for the fossil transportation fuel.     

甲基苯丙胺中毒大鼠纹状体COX-2、PGE2、EP2受体及小胶质细胞表达的研究

目的：通过研究COX-2、PGE2、EP2受体及小胶质细胞在甲基苯丙胺中毒大鼠纹状体内的表达变化探讨甲基苯丙胺中毒大鼠纹状体中COX-2／PGE2系统与小胶质细胞活化之间的关系。方法：将40只健康成年雄性SD大鼠,随机分成对照组10只和实验组30只（实验组分成三个亚组,分为末次给药后1天组、2天组和3天组,n=10）。实验组给予10mg／kg的MA腹腔注射,对照组给予同样剂量的生理盐水,每天注射两次,注射时间为8：00、20：00,连续注射4天。分别于末次给药后的第1天、第2天、第3天处杀。用免疫组化技术对中毒大鼠纹状体（CPU）中COX-2、EP2受体及Iba1（钙离子接头蛋白,小胶质细胞内一种特异性标记物）的表达进行检测,并进行图像分析。另外,取大鼠的纹状体运用酶联免疫法检测PGE2的含量。结果：COX-2、PGE2、EP2受体及小胶质细胞在各组均有表达。与对照组相比,实验组中：COX-2、PGE2、EP2受体的1天组表达均不同程度下降;2天组中COX-2表达水平大幅度上升,PGE2、EP2受体表达仍低于正常水平;3天组COX-2表达水平继续升高,而PGE2、EP2受体表达趋于正常组水平。而小胶质细胞表达水平则是三个实验组均高于正常组,且3天组高于2天组,2天组高于l天组。对照组与实验组有显著性差异（P〈0．05）。结论：COX-2／PGE2系统与甲基苯丙胺中毒大鼠纹状体内小胶质细胞活化无明显相关性;COX-2与甲基苯丙胺的神经毒性有关。     

Hemodynamic changes in the kidney in a pediatric rat model of sepsis-induced acute kidney injury

Sepsis is a leading cause of acute kidney injury (AKI) and mortality in children. Understanding the development of pediatric sepsis and its effects on the kidney are critical in uncovering new therapies. The goal of this study was to characterize the development of sepsis-induced AKI in the clinically relevant cecal ligation and puncture (CLP) model of peritonitis in rat pups 17-18 days old. CLP produced severe sepsis demonstrated by time-dependent increase in serum cytokines, NO, markers of multiorgan injury, and renal microcirculatory hypoperfusion. Although blood pressure and heart rate remained unchanged after CLP, renal blood flow (RBF) was decreased 61% by 6 h. Renal microcirculatory analysis showed the number of continuously flowing cortical capillaries decreased significantly from 69 to 48% by 6 h with a 66% decrease in red blood cell velocity and a 57% decline in volumetric flow. The progression of renal microcirculatory hypoperfusion was associated with peritubular capillary leakage and reactive nitrogen species generation. Sham adults had higher mean arterial pressure (118 vs. 69 mmHg), RBF (4.2 vs. 1.1 ml·min(-1)·g(-1)), and peritubular capillary velocity (78% continuous flowing capillaries vs. 69%) compared with pups. CLP produced a greater decrease in renal microcirculation in pups, supporting the notion that adult models may not be the most appropriate for studying pediatric sepsis-induced AKI. Lower RBF and reduced peritubular capillary perfusion in the pup suggest the pediatric kidney may be more susceptible to AKI than would be predicted using adults models.     

Effect of ubiquitin carboxy-terminal hydrolase 37 on apoptotic in A549 cells

Proteins destined for degradation by the ubiquitin-proteasome system are labelled with a 76-amino acid peptide, ubiquitin, through a series of conjugation steps by the E1, E2 and E3 enzymes respectively. Ubiquitin carboxy-terminal hydrolase 37 (UCH37) belongs to the UCH proteases family that deubiquitinates ubiquitin-protein conjugates in the ubiquitin-proteasome system. However, it is few reports about the relationship between UCH37 and apoptosis. In order to clarify the role of UCH37 on apoptosis, the A549 cells were chosen for this study. We transfected UCH37 siRNA and pcDNA3.1-UCH37 plasmid into A549 cells, respectively. Using MTT assay, Western blot, Hoechst 33342 staining assay and flow cytometry, we found that silencing of UCH37 in A549 cells induced apoptosis. The ratio of Bax/Bcl-2 was higher in silencing of UCH37 than that in control group after silencing of UCH37 in A549 cells. Meanwhile, experiments with the A549 cell line disclose that silencing of UCH37 could induce efficiently A549 cell apoptosis through activation of caspase-9 and caspase-3. On the other hand, over-expression of UCH37 led to the opposite effect. Hence, UCH37 might play an important role in apoptotic through altering Bax/Bcl-2 ratio and enzymatic activities of caspase-9 and caspase-3.     

Aanlysis of short photo-periodic sensitive genic male sterility and molecular mapping of rpms3(t) gene in rice (Oryza sativa L.) using SSR markers

A research was conducted on the pollen fertility of rice sterile lines D52S and D38S responsive to photoperiod during the sensitive stage under natural and controlled conditions. Bulk segregant analysis (BSA) and recessive class approach were applied to identify DNA markers that co-segregate with gene conferring male-sterility in D52S mutant rice. The results showed that in day-light higher or equal to 14.00 h, D52S and D38S rice pollen were fertile; however, they were sterile when day-length was less than 14.00 h. They were therefore considered to be short photo-periodic sensitive genic male sterile lines(Short PGMS lines). Under short day-light conditions, the pollen fertility segregation of F₂ populations from crosses between D52S/Shuhui527 and D52S/Gui99showed 3:1 ratio of fertile to sterile plants suggestingthat male sterility in D52S was controlled by one recessive gene. Two markers RM244 and RM216 located on chromosome number 10 co-segregated completely with the rpms locus. The locus was mapped to the interval between SSR markers RM2571 (6.6 cM) and RM244 (4.6 cM).     

tPA cDNA在兔乳腺中的表达(英文)

组织型纤维原激活剂（tPA）的作用是激活血纤维蛋白酶原,从而溶解血栓。生物体内tPA的含量很低,远远不能满足临床需要。为了利用转基因动物生产tPA,需要对所用tPA乳腺表达载体pSVL－WAP－tPA2（Fig．1）进行予证。将三种待研究载体分别用脂质体包埋,注入中后期怀孕母兔乳腺。对乳汁、乳腺组织的mRNA和DNA分别进行检测。实验兔分娩后,每4天取乳汁冻存,ELISA检测其中tPA含量（Fig．2）,泌乳期第4天最高可达600ng／ml。又,于乳腺注射第3天,手术切取部分乳腺组织,制备总RNA,以β－Casein启动子下游序列（TACTAG…）为引物Ⅰ,tPA上游序列（TTCCCA…）为引物Ⅱ,做RT－PCR检测,表明：此时已有tPAmRNA转录（Fig．3）。再,于停乳后30天左右,切取部分乳腺制备DNA,以tPAcDNA为探针,做Southern杂交检测,表明：无tPA整合,仅是以附合体形式存在（Fig．4）。上述质粒直接注射技术是予证转基因用载体表达水平的快捷、简便方法。