Exogenous application of urea and a urease inhibitor improves drought stress tolerance in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.)

Drought is believed to cause many metabolic changes which affect plant growth and development. However, it might be mitigated by various inorganic substances, such as nitrogen. Thus, the study was carried out to investigate the effect of foliar-applied urea with or without urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on a maize cultivar under drought stress simulated by 15% (w/v) polyethylene glycol 6000. Foliar-applied urea resulted in a significant increase in plant dry weight, relative water content, and photosynthetic pigments under water stress condition. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD), and hydrogen peroxidase (CAT), were enhanced with all spraying treatments under drought stress, which led to decreases in accumulation of hydrogen peroxide (H₂O₂), superoxide anion (\({\text{O}}_2^{ \cdot - }\)) and malondialdehyde (MDA). The contents of soluble protein and soluble sugar accumulated remarkably with urea-applied under drought stress condition. Moreover, a further enhancement in above metabolites was observed by spraying a mixture of urea and urease inhibitor as compared to urea sprayed only. Taken together, our findings show that foliar application of urea and a urease inhibitor could significantly enhance drought tolerance of maize through protecting photosynthetic apparatus, activating antioxidant defense system and improving osmoregulation.     

Exogenous Glutathione Modulates Salinity Tolerance of Soybean [<Emphasis Type="Italic">Glycine max</Emphasis> (L.) Merrill] at Reproductive Stage

In this study, we evaluated salt stress responses of 11 soybean genotypes and explored the protective roles of exogenous glutathione (GSH) against salt toxicity by assessing various biochemical and yield-attributing parameters. Exposure of the soybean genotypes to salt stress at the reproductive (R1) stage significantly decreased their yields by down-regulating the yield-contributing parameters as compared with unstressed controls. The highest decrease was found in number of seeds plant^?1, yield plant^?1, and number of pods plant^?1, whereas the lowest decrease was recorded in number of seeds pod^?1. Exogenous GSH was found to be effective in improving salinity tolerance, and the highest positive effects of GSH were recorded in terms of yield plant^?1, number of seeds plant^?1 and number of pods plant^?1, whereas its lowest effect was observed with respect to the 100-seed weight. Cluster analysis of the genotypes based on yield-contributing and yield data revealed different levels of salt tolerance. Notably, BINA-01 and -02, and BINA-04 were recognized as the highest and lowest salt-tolerant genotypes, respectively. Furthermore, exogenous GSH alleviated oxidative stress in the representative contrasting genotypes at the vegetative (V3) stage by decreasing salt-induced accumulation of malondialdehyde and hydrogen peroxide. Taken together, our findings revealed that exogenous GSH application can minimize oxidative stress and contribute to the improvement of yield-contributing parameters, leading to improved yield in soybean genotypes under salt stress. Further investigations on molecular aspects will enable us to gain an in-depth understanding of how exogenous GSH can improve salinity tolerance in soybean, particularly at reproductive stage, to discover relevant pathways for biotechnological manipulation.     

Covalent-display of an active chimeric-recombinant tissue plasminogen activator on polyhydroxybutyrate granules surface

Objective

To develop a deliberately engineered expression and purification system for an active chimeric-recombinant tissue plasminogen activator (crtPA) using co-expression with polyhydroxybutyrate (PHB) operon genes.

Results

Fusion of crtPA with PhaC-synthase simplified the purification steps through crtPA sedimentation with PHB particles. Moreover, the covalently immobilized crtPA was biologically active as shown in a chromogenic assay. Upon WELQut-protease activity, the released single-chain crtPA converted to the two-chain form which produced a pattern of bands with approx. MW of 32 and 11 kDa in addition to the full length crtPA.

Conclusion

Fusion of crtPA with PhaC-synthase not only simplifies purification from the bacterial host lysate, but also co-expression of PHB operon genes creates an oxidative environment, thereby reducing the inclusion body formation possibility. The isolated crtPA-PHB granules exhibited crtPA serine protease activity. Thus, fusion with the PhaC protein could be used as a scaffold for covalent displaying of functional disulfide-rich proteins.

     

The evolution of hominoid cranial diversity: A quantitative genetic approach

Hominoid cranial evolution is characterized by substantial phenotypic diversity, yet the cause of this variability has rarely been explored. Quantitative genetic techniques for investigating evolutionary processes underlying morphological divergence are dependent on the availability of good ancestral models, a problem in hominoids where the fossil record is fragmentary and poorly understood. Here, we use a maximum likelihood approach based on a Brownian motion model of evolutionary change to estimate nested hypothetical ancestral forms from 15 extant hominoid taxa. These ancestors were then used to calculate rates of evolution along each branch of a phylogenetic tree using Lande's generalized genetic distance. Our results show that hominoid cranial evolution is characterized by strong stabilizing selection. Only two instances of directional selection were detected; the divergence of Homo from its last common ancestor with Pan, and the divergence of the lesser apes from their last common ancestor with the great apes. In these two cases, selection gradients reconstructed to identify the specific traits undergoing selection indicated that selection on basicranial flexion, cranial vault expansion, and facial retraction characterizes the divergence of Homo, whereas the divergence of the lesser apes was defined by selection on neurocranial size reduction.     

Signal transduction and biotechnology in response to environmental stresses

Providing sufficient food to burgeoning population from the steadily shrinking arable land seems to be very difficult in near future and is one of the foremost challenges for plant scientists. In addition, there are several biotic and abiotic stresses which frequently encounter crop plants during various stages of life cycle, resulting in considerable yield losses. Environmental stresses, including drought, flooding, salinity, temperature (both low and high), high radiation, and xenobiotics induce toxicity, membrane damage, excessive reactive oxygen species (ROS) production, reduced photosynthesis, and altered nutrient acquisition. Several indigenous defence mechanisms (physiological and molecular) are triggered in plants on exposure to environmental cues. Enhancement of resistance of crop plants to environmental stresses has been the topic of prime interest for agriculturalists and plant scientists since long. Development of water and salinity stress-tolerant crops through genetic engineering provides an avenue towards the reclamation of farmlands that have been lost due to salinity and lack of irrigation water/rainfall. Understanding the complexity of stress tolerance mechanisms in orthodox or model plants at the genetic and molecular levels improves feasibility of enhancing tolerance of sensitive crop plants.     

阿克苏市5种常见绿化树种滞尘规律

绿化树种在截留沙尘、降低大气颗粒污染物浓度、改善城市生态环境等方面发挥着不可替代的作用。该文选取新疆南部典型绿洲城市——阿克苏市不同功能区的绿化树种, 用多重比较法对比分析了二球悬铃木(Platanus × acerifolia)、新疆杨(Populus alba var. pyramidalis)、圆冠榆(Ulmus densa)、天山梣(Fraxinus sogdiana)和垂柳(Salix babylonica) 5个树种叶片平均滞尘量随时间变化及不同高度叶片的滞尘能力, 探讨了阿克苏市主要绿化树种的滞尘规律, 得出以下结论: 不同绿化树种单位叶面积滞尘量差异显著, 差距在1.15-2.17倍之间, 绿化树种滞尘量随着时间延长而增加; 同一树种在城市不同功能区的滞尘能力不同: 工业区>交通枢纽区>居民区>清洁区; 不同高度的叶片, 其滞尘量在工业区和交通枢纽区差异显著: 高度1 m的叶片滞尘量>高度2 m的叶片滞尘量>高度4 m的叶片滞尘量。     

Glucose regulation of CDK7, a putative thiol related gene, in experimental diabetic nephropathy

We previously described the identification of the 3'end of an unknown gene CDK7 using differential display which appeared to be up-regulated in diabetic kidneys [R.A. Page, C.A. Morris, J.D. Williams, C.J. von Ruhland, A.N. Malik, Isolation of diabetes-associated kidney genes using differential display, Biochem. Biophys. Res. Commun. 232 (1997) 49-53]. Here we show that CDK7 is a putative thiol related gene which is regulated by glucose in human and rat renal cells. CDK7 mRNA increased by >threefold in cultured human mesangial cells grown in high glucose for 4 days. In the kidneys of the GK rat, a model of type II diabetes, CDK7 showed a steady age-related increase in mRNA, increasing to >sixfold in 40 week GK rats compared to normoglycemic age-matched Wistar rat kidneys, this increase correlates with progressive hyperglycemia. CDK7 mRNA is widely expressed, showing particularly high levels of expression in rat and human liver, and encodes a putative 338 amino acids highly conserved peptide with several conserved domains, including a cys-pro-arg-cys domain conserved in 15 diverse species which is similar to the catalytic centre of thioredoxin, suggesting a role in oxidative stress.