异源表达NADH选择性氧化酶提高光滑球拟酵母酵解速率及丙酮酸生产强度

摘要：【目的】为进一步提高光滑球拟酵母(Torulopsis glabrata)葡萄糖代谢速率及丙酮酸生产强度。【方法】将源于荚膜胞浆菌(Histoplasma capsulatum)的编码选择性氧化酶的AOX1基因过量表达于T. glabrata中,获得了一株线粒体内NADH氧化途径发生改变且胞内总NADH 氧化酶活性提高1.8倍的重组菌株AOX。【结果】与出发菌株CON比较,细胞浓度以及发酵周期降低了20.3%和10.7%,而平均比葡萄糖消耗速率和丙酮酸合成速率分别提高了34.7%和54.1%。其原因     

A genotype-specific pollen gene associated with self-incompatibility in Lycopersicon peruvianum

Self-incompatibility is a genetically controlled process used to prevent self-pollination. We report here the characterization of pollen cDNA clones of Lycopersicon peruvianum, and the identification of a genotype-specific pollen factor involved in self-incompatibility. To identify the latter, differential mRNA display RT-PCR was performed on pollen cDNAs from S12Sa and S11Sa genotypes. We isolated four cDNA fragments expressed preferentially in S12Sa pollen, and screened a cDNA library from S12Sa pollen with the four cDNA fragments to isolate the corresponding full length cDNAs. One of the four isolated cDNAs encoded part of an actin depolymerizing factor protein that we named LpADF. LpADF is highly homologous to actin depolymerizing factors of Arabidopsis thaliana, Lilium longiflorum, and Zea mays. RNA blot analysis revealed that LpADF is only expressed in mature pollen of the S12Sa genotype, and is therefore a candidate pollen factor in the gametophyte self-incompatibility system of L. peruvianum.     

Effects of Vascular Endothelial Growth Factor 165 on Bone Tissue Engineering

To study the relationship between vascular endothelial growth factor (VEGF) and formation and repair of engineering bone, second-generation bone marrow stromal cells (BMSCs) of New Zealand white rabbits that were separated in vitro were transfected with VEGF 165 gene vectors by adenovirus to detect gene expressions. Transfected BMSCs and β-tricalcium phosphate material were complexed and implanted at the femoral injury sites of the study group (n = 12), and the control group (n = 12) were implanted with engineering bones that were not transfected with VEGF. Femoral recoveries of the two groups were observed on the 15th, 30th, 45th and 60th days, and their vascularization and ossification statuses were observed by immunohistochemical methods. The BMSCs transfected with VEGF highly expressed VEGF genes and excreted VEGF. The two groups both experienced increased vascularization and bone volume after implantation (t = 7.92, P<0.05), and the increases of the study group were significantly higher than those of the control group (t = 6.92, P<0.05). VEGF is clinically applicable because it can accelerate the formation and repair of engineering bone by promoting vascularization and ossification.     

阿拉善干旱荒漠区不同植被类型土壤种子库研究

[1]兰州大学草地农业科技学院,兰州730020 [2]甘肃草原生态研究所,兰州730020 [3]内蒙古阿拉善盟草原站,巴彦浩特750360     

Physiological acclimation and growth response to partial shading in <Emphasis Type="Italic">Salix matsudana</Emphasis> in the Mu Us Sandland in China

In a controlled experiment, Salix matsudana plants were subjected to uniform nonshading (F-S), partial shading (P-S) and uniform shading (U-S). The shoots of the plants in the F-S and U-S treatments were referred to as H-H and L-L, respectively. The plants in the P-S treatment had two kinds of shoots: (1) shoots under the nonshading treatment that were connected to others under the shading treatment (H-L).(2) Shoots under the shading treatment that were connected to others under the nonshading treatment (L-H). The physiological acclimation and growth response of the species to the partial shading were examined. The partial shading had significant effects on photosynthetic dynamics, transpiration and stomatal conductance, but no effect on instantaneous water use efficiency and maximum quantum yield. Water saturation deficit and coefficient of water loss were significantly smaller in the H-L shoots than in the H-H shoots. Leaf natality, leaf mortality and leaf turnover were greater in the H-L shoots than in the H-H shoots. In contrast, these three parameters were smaller in the L-H shoots than in the L-L shoots. The H-L shoots had significantly larger branching ratio, total branch length and shoot biomass than the H-H shoots. The L-H shoots had smaller branching ratio, total branch length and shoot biomass than the L-L shoots. Total plant biomass in the treatments increased as follows: F-S相似文献   

Roots play a vital role in flood-tolerance of poplar demonstrated by reciprocal grafting

Poplar is one of the most important multipurpose afforestation trees in river floodplains and arable farmland which are subject to frequent flooding. To determine the relative roles that the roots and shoots have in responses to waterlogging, six root-shoot grafting combinations of full-sib poplar clones LS1 (flood-tolerant) and LS2 (flood-susceptible) were compared for waterlogging effects on them, using reciprocal and self-grafts. Plants of the six combinations comprised non-grafted (LS1) and (LS2), self-grafted (LS1/LS1) and (LS2/LS2), LS1 grafted onto LS2 (LS1/LS2), and LS2 grafted onto LS1 (LS2/LS1) experimental plants. The two clones LS1 and LS2 originated from Populus deltoides cv. Lux ex. I-69/55 (flood-tolerant) × P. simonii (flood-susceptible). Growth, morphological and ecophysiological parameters of plants belonging to the six grafting combinations were subjected for 21 days to flooding, followed by a six-day drainage and recovery stage. Results showed that flooding stress affected adversely growth, biomass accumulation, morphological and ecophysiological characteristics in all flooded plants. The more severe influences were found in the plants with LS2 roots (LS1/LS2, LS2/LS2, LS2), whereas plants having roots of LS1 (LS2/LS1, LS1/LS1, LS1) were less negatively affected. At the end of the study, 100%, 100%, 93.3%, 26.7%, 6.7% and 20% survival rates, respectively, were observed in flooded plants of LS1, LS1/LS1, LS2/LS1, LS1/LS2, LS2/LS2 and LS2. In conformity with the results for growth, biomass accumulation and morphology, responses to flooding of gas exchange, chlorophyll fluorescence, relative membrane permeability of leaves, the overall root metabolism parameter dehydrogenase activity (TTC assay), as well as malonaldehyde contents of leaves and roots also indicated that flood injury was significantly more pronounced in plants having LS2 roots than in those with LS1 roots. Plants with roots of LS1 displayed clearly faster recovery after flooding than the plants with LS2 roots. The results indicate that flooding-tolerance of poplar is based more on influences from the rootstock than on those of the scion. It is thus the root genotype that plays the decisive role in flood-tolerance of poplar.     

高山松及其亲本种群在油松生境下的苗期性状

高山松(Pinus densata)是油松(P. tabuliformis)和云南松(P. yunnanensis)的天然二倍体杂交种, 是为数不多的与亲本种没有严格生殖隔离的同倍体杂交种。为了检测3个种在油松生境下的苗期适应性和生长发育特点, 为高山松成种机制提供数据, 选取了代表高山松及其亲本种遗传多样性的25个种群, 在油松生境下对比分析了苗期11个适应性指标和3个生长发育指标。结果表明, 大部分适应性指标和生长发育指标在种间和种内群体间差异显著, 主要变异存在于种间及种内群体间; 出苗率、2011年11月和2012年10月的封顶率、二年生苗在2012年10月的保存率等指标的种间方差分量较大, 种内变异较小, 是体现种间苗期适应性和生长发育状况的重要指标。油松在大部分适应性指标和3个生长发育指标上均表现最好, 总体适合度高于云南松和高山松; 云南松在封顶率和保存率上都居于最低值, 大部分一年生苗木到11月底仍未出现封顶现象且黄苗比例最高, 二年生苗的存活率为0, 表明云南松在油松生境下适合度最低; 高山松除了在紫苗比例上表现出超亲优势外, 大部分性状居于亲本种之间。此外, 位于青藏高原东北部的高山松祖先种群在适应性上表现较好, 具有在油松生境下发展的潜力; 而位于青藏高原西部的高山松种群及东南部的康定种群对油松生境的适应性较差。研究揭示出生态选择在高山松的同倍性杂交物种形成中起到了关键作用。     

Endophytes isolated from Panax notoginseng converted ginsenosides

Endophytes may participate in the conversion of metabolites within medicinal plants, influencing the efficacy of host. However, the distribution of endophytes within medicinal plants P. notoginseng and how it contributes to the conversion of saponins are not well understood. Here, we determined the distribution of saponins and endophytes within P. notoginseng compartments and further confirm the saponin conversion by endophytes. We found metabolites showed compartment specificity within P. notoginseng. Potential saponin biomarkers, such as Rb1, Rg1, Re, Rc and Rd, were obtained. Endophytic diversity, composition and co-occurrence networks also showed compartment specificity, and bacterial alpha diversity values were highest in root compartment, consistently decreased in the stem and leaf compartments, whereas those of fungi showed the opposite trend. Potential bacterial biomarkers, such as Rhizobium, Bacillus, Pseudomonas, Enterobacter, Klebsiella, Pantoea and fungal biomarkers Phoma, Epicoccum, Xylariales, were also obtained. Endophytes related to saponin contents were found by Spearman correlation analysis, and further verification experiments showed that Enterobacter chengduensis could convert ginsenoside Rg1 to F1 at a rate of 13.24%; Trichoderma koningii could convert ginsenoside Rb1 to Rd at a rate of 40.00% and to Rg3 at a rate of 32.31%; Penicillium chermesinum could convert ginsenoside Rb1 to Rd at a rate of 74.24%.     

GTPase activity analysis of eRF3 in Euplotes octocarinatus

In eukaryotes, eRF3 participates translation termination and belongs to the superfamily of GTPase. In this work, dissociation constants for E. octocarinatus eRF3 binding to nucleosides in presence and absence of eRF1a were determined using fluorescence spectra methods. Furthermore, the GTP hydrolyzing assay of Eo-eRF3 was carried out by HPLC methods and the kinetic parameter for GTP hydrolysis by eRF3 was determined. The results showed eRF1a could promote GTP binding to eRF3 and hydrolyzing GTP activity of eRF3. The observation is consistent with the data from human. Whereas E. octocarinatus eRF3 alone can bind GTP in contrast to no GTP binding observed in the absence of eRF1 in human eRF3. The affinity for Eo-eRF3 binding nucleotides is different from that in human. Structure model and amino acids sequence alignment of potential G domains indicated these different may be due to Valine 317 and Glutamate 452 displacing conserved Glycine and Lysine, which were involved in GTP binding.