Use of beta-glucuronidase reporter gene for gene expression analysis in turfgrasses

Protocol development for somatic embryogenesis, SSR markers and genetic modification of Stipagrostis pennata (Trin.) De Winter

BACKGROUND

Stipagrostis pennata (Trin.) De Winter is an important species for fixing sand in shifting and semi-fixed sandy lands, for grazing, and potentially as a source of lignocellulose fibres for pulp and paper industry. The seeds have low viability, which limits uses for revegetation. Somatic embryogenesis offers an alternative method for obtaining large numbers of plants from limited seed sources.

RESULTS

A protocol for plant regeneration from somatic embryos of S. pennata was developed. Somatic embryogenesis was induced on Murashige & Skoog (MS) medium supplemented with 3 mg·L-1 2,4-D subsequently shoots were induced on MS medium and supplemented with 5 mg·L-1 zeatin riboside. The highest shoots induction was obtained when embryogenic callus derived from mature embryos (96%) in combination with MS filter-sterilized medium was used from Khuzestan location. The genetic stability of regenerated plants was analysed using ten simple sequence repeats (SSR) markers from S. pennata which showed no somaclonal variation in regenerated plants from somatic embryos of S. pennata. The regenerated plants of S. pennata showed genetic stability without any somaclonal variation for the four pairs of primers that gave the expected amplicon sizes. This data seems very reliable as three of the PCR products belonged to the coding region of the genome. Furthermore, stable expression of GUS was obtained after Agrobacterium-mediated transformation using a super binary vector carried by a bacterial strain LBA4404.

CONCLUSION

To our knowledge, the current work is the first attempt to develop an in vitro protocol for somatic embryogenesis including the SSR marker analyses of regenerated plants, and Agrobacterium-mediated transformation of S. pennata that can be used for its large-scale production for commercial purposes.

Optical approaches for single-cell and subcellular analysis of GPCR-G protein signaling

G protein-coupled receptors (GPCRs), G proteins, and their signaling associates are major signal transducers that control the majority of cellular signaling and regulate key biological functions including immune, neurological, cardiovascular, and metabolic processes. These pathways are targeted by over one-third of drugs on the market; however, the current understanding of their function is limited and primarily derived from cell-destructive approaches providing an ensemble of static, multi-cell information about the status and composition of molecules. Spatiotemporal behavior of molecules involved is crucial to understanding in vivo cell behaviors both in health and disease, and the advent of genetically encoded fluorescence proteins and small fluorophore-based biosensors has facilitated the mapping of dynamic signaling in cells with subcellular acuity. Since we and others have developed optogenetic methods to regulate GPCR-G protein signaling in single cells and subcellular regions using dedicated wavelengths, the desire to develop and adopt optogenetically amenable assays to measure signaling has motivated us to take a broader look at the available optical tools and approaches compatible with measuring single-cell and subcellular GPCR-G protein signaling. Here we review such key optical approaches enabling the examination of GPCR, G protein, secondary messenger, and downstream molecules such as kinase and lipid signaling in living cells. The methods reviewed employ both fluorescence and bioluminescence detection. We not only further elaborate the underlying principles of these sensors but also discuss the experimental criteria and limitations to be considered during their use in single-cell and subcellular signal mapping.

Synthesis and biological evaluation of novel N-arylidenequinoline-3-carbohydrazides as potent β-glucuronidase inhibitors

Thirty N-arylidenequinoline-3-carbohydrazides (1-30) have been synthesized and evaluated against β-glucuronidase inhibitory potential. Twenty four analogs showed outstanding β-glucuronidase activity having IC50 values ranging between 2.11±0.05 and 46.14±0.95 than standard d-saccharic acid 1,4 lactone (IC50=48.4±1.25μM). Six analogs showed good β-glucuronidase activity having IC50 values ranging between 49.38±0.90 and 80.10±1.80. Structure activity relationship and the interaction of the active compounds and enzyme active site with the help of docking studies were established. Our study identifies novel series of potent β-glucuronidase inhibitors for further investigation.

Evaluación de tres promotores constitutivos para la expresión GUS en arroz (Oryza sativa L., cv. J-104)

<p>Se analizó la expresión constitutiva del gen reportero de la ß-Glucuronidasa (GUS) fusionado a tres promotores: el 35S del virus del mosaico de la coliflor (CaMV), el promotor quimérico A9 que contiene la actina-1 de arroz y el promotor ubiquitina-1 de maíz. La actividad de los promotores fue analizada cualitativa y cuantitativamente en diferentes tejidos y estadíos de crecimiento de plantas de arroz (variedad J-104) transformadas mediante biobalística. Se demostró la expresión constitutiva de GUS bajo los promotores estudiados, con distintos patrones de actividad relativa en hojas, tallos y raíces de plantas in vitro y ex vitro, y en plantas de la progenie T 1. Bajo el promotor quimérico A9 se lograron los mayores niveles de expresión GUS en todos los tejidos y fases de crecimiento de las plantas.</p>

Characterization of the 5' flanking region of lipase gene from Penicillium expansum and its application in molecular breeding

A major challenge for further promotion of lipase productivity in Penicillium expansum PE-12 is to find a suitable promoter that can function efficiently in this industrial strain. In this study, the 5' flanking region of P. expansum lipase (Ppel) containing a putative novel promoter sequence was characterized by fusing to β-glucuronidase (GUS) and subsequently introducing into P. expansum. As a result, all the transformants showed blue color quickly after incubation in GUS detection buffer, suggesting a strong promoter activity of this fragment. Glucose repression was identified for the promoter, whereas olive oil acted as a positive regulator. Facilitated by this novel promoter, P. expansum PE-12 was genetically modified, with an improved lipase yield, via a recombinant plasmid with P. expansum lipase gene (PEL) under the control of Ppel promoter and TtrpC terminator. The highest lipase yield among the modified strains could attain 2,100 U/mL, which is more than twofold of the previous industrial strain (900 U/mL). The engineered strain through molecular breeding method as well as this new promoter has great value in lipase industry.

Development of a thermostable β-glucuronidase-based reporter system for monitoring gene expression in hyperthermophiles

Mesophilic glucuronidases are the most widely used reporters of gene expression in plants, but unsuitable as reporters in (hyper-)thermophiles due their insufficient thermal stability. Here we present the native 66.8 kDa thermostable β-glucuronidase of Sulfolobus solfataricus. The enzyme activity is characterized in a wide temperature range ideal for, but not limited to, in vivo genetic study of hyperthermophiles. As a proof of concept, we demonstrate its use as a reporter of gene expression in Sulfolobus, by monitoring a promoter fusion created with the β-glucuronidase coding gene gusB and a copper-responsive promoter.

Suitability of different β-galactosidases as reporter enzymes in Bacillus subtilis

The suitability of three β-galactosidases as reporter enzymes for promoter expression analyses was investigated in Bacillus subtilis with respect to various temperature conditions during cultivation and assay procedures. Starting from the hypothesis that proteins derived from diverse habitats have different advantages as reporters at different growth temperatures, the beta-galactosidases from the thermophilic organism Bacillus stearothermophilus, from the mesophilic bacterium Escherichia coli and from the psychrophilic organism Pseudoalteromonas haloplanktis TAE79 were analysed under control of the constitutive B. subtilis lepA promoter. Subsequent expression of the β-galactosidase genes and determination of specific activities was performed at different cultivation and assay temperatures using B. subtilis as host. Surprisingly, the obtained results demonstrated that the highest activities over a broad cultivation temperature range were obtained using the β-galactosidase from the mesophilic bacterium E. coli whereas the enzymes from the thermophilic and psychrophilic bacteria revealed a more restricted usability in terms of cultivation temperature.

Gossypium arboreum GHSP26 enhances drought tolerance in Gossypium hirsutum

Heat-shock proteins (HSP) are molecular chaperones for protein molecules. These proteins play an important role in protein-protein interactions such as, folding and assisting in the establishment of proper protein conformation and prevention of unwanted protein aggregation. A small HSP gene GHSP26 present in Gossypium arboreum responds to dehydration. In the present study, an attempt was made to overcome the problem of drought stress in cotton. A cDNA of GHSP26 was isolated from G. arboreum, cloned in plant expression vector, pCAMBIA-1301 driven by the cauliflower mosaic virus 35S promoter and introduced into Gossypium hirsutum. The integration and expression studies of putative transgenic plants were performed through GUS assay; PCR from genomic DNA, and quantitative real-time PCR analysis. Transgenic cotton plants showed an enhanced drought tolerance, suggesting that GHSP26 may play a role in plant responsiveness to drought.

Improved heterologous gene expression in Trichoderma reesei by cellobiohydrolase I gene (cbh1) promoter optimization

To improve heterologous gene expression in Trichoderma reesei, a set of optimal artificial cellobiohydrolase I gene (cbh1) promoters was obtained. The region from -677 to -724 with three potential glucose repressor binding sites was deleted. Then the region from -620 to -820 of the modified cbh1 promoter, including the CCAAT box and the Ace2 binding site, was repeatedly inserted into the modified cbh1 promoter, obtaining promoters with copy numbers 2, 4, and 6. The results showed that the glucose repression effects were abolished and the expression level of the glucuronidase (gus) reporter gene regulated by these multi-copy promoters was markedly enhanced as the copy number increased simultaneously. The data showed the great promise of using the promoter artificial modification strategy to increase heterologous gene expression in filamentous fungi and provided a set of optional high-expression vectors for gene function investigation and strain modification.

A fast and flexible PEG-mediated transient expression system in plants for high level expression of secreted recombinant proteins

Plant expression systems offer a valuable alternative to traditional systems for the production of recombinant biopharmaceuticals. A highly efficient polyethyleneglycol (PEG)-mediated transient expression system for secreted recombinant proteins in plants has been developed. The human vascular endothelial growth factor 121 (rhVEGF) has been successfully expressed and efficiently secreted into the culture medium by transiently transformed moss protoplasts. In order to obtain secretion efficiency data, different expressed signal peptides were analysed and time course studies were performed with expression constructs containing different promoters. The transformation procedure was optimised for high level expression (up to 10 microg/ml) and successfully performed even with a transgenic glyco-engineered strain lacking plant-specific immunogenic sugar residues in N-glycans. The amount of rhVEGF was produced in such quantity that it allowed for the analysis of biological activity, silver-staining and Western blotting, revealing the correct formation and processing of the homodimer. This fast and flexible transient expression system enables feasibility studies and construct optimisation to be concluded within a few days, thus avoiding the time consuming step of having to generate stably transformed lines.