Efficient and stable transformation of Dunaliella pseudosalina by 3 strains of Agrobacterium tumefaciens

Dunaliella salina as a Potential Biofactory for Antigens and Vehicle for Mucosal Application

The demand for effective, low-cost vaccines increases research in next-generation biomanufacturing platforms and the study of new vaccine delivery systems (e.g., mucosal vaccines). Applied biotechnology in antigen production guides research toward developing genetic modification techniques in different biological models to achieve the expression of heterologous proteins. These studies are based on various transformation protocols, applied in prokaryotic systems such as Escherichia coli to eukaryotic models such as yeasts, insect cell cultures, animals, and plants, including a particular type of photosynthetic organisms: microalgae, demonstrating the feasibility of recombinant protein expression in these biological models. Microalgae are one of the recombinant protein expression models with the most significant potential and studies in the last decade. Unicellular photosynthetic organisms are widely diverse with biological and growth-specific characteristics. Some examples of the species with commercial interest are Chlamydomonas, Botryococcus, Chlorella, Dunaliella, Haematococcus, and Spirulina. The production of microalgae species at an industrial level through specialized equipment for this purpose allows for proposing microalgae as a basis for producing recombinant proteins at a commercial level. A specie with a particular interest in biotechnology application due to growth characteristics, composition, and protein production capacity is D. salina, which can be cultivated under industrial standards to obtain βcarotene of high interest to humans. D saline currently has advantages over other microalgae species, such as its growth in culture media with a high salt concentration which reduces the risk of contamination, rapid growth, generally considered safe (GRAS), recombinant protein biofactory, and a possible delivery vehicle for mucosal application. This review discusses the status of microalgae D. salina as a platform of expression of recombinant production for its potential mucosal application as a vaccine delivery system, taking an advance on the technology for its production and cultivation at an industrial level.

Transformation of Dunaliella salina by Agrobacterium tumefaciens for the Expression of the Hemagglutinin of Avian Influenza Virus H5

Avian influenza (AI) is one of the main threats to the poultry industry worldwide. Vaccination efforts are based on inactivated, live attenuated, and recombinant vaccines, where the virus hemagglutinin (HA) is the main component of any vaccine formulation. This study uses Dunaliella salina to express the AIV HA protein of an H5 virus. D. salina offers a system of feasible culture properties, generally recognized as safe for humans (GRAS), with N-glycosylation and nuclear transformation by Agrobacterium tumefaciens. The cloning and transformation of D. salina cells with the H5HA gene was confirmed by polymerase chain reaction (PCR). SDS-PAGE and Western blot confirmed HA5r protein expression, and the correct expression and biological activity of the HA5r protein were confirmed by a hemagglutination assay (HA). This study proves the feasibility of using a different biological system for expressing complex antigens from viruses. These findings suggest that a complex protein such as HA5r from AIV (H5N2) can be successfully expressed in D. salina.

Designing a new generation of expression toolkits for engineering of green microalgae; robust production of human interleukin-2

Introduction: Attributable to some critical features especially the similarity of the protein synthesis machinery between humans and microalgae, these microorganisms can be utilized for the expression of many recombinant proteins. However, low and unstable gene expression levels prevent the further development of microalgae biotechnology towards protein production.

Methods: Here, we designed a novel "Gained Agrobacterium -2A plasmid for microalgae expression" (named GAME plasmid) for the production of the human interleukin-2 using three model microalgae, including Chlamydomonas reinhardtii, Chlorella vulgaris , and Dunaliella salina . The GAME plasmid harbors a native chimeric hsp70/Int-1/rbcS2 promoter, the microalgae specific Kozak sequence, a novel hybrid 2A peptide, and Int-1 and Int-3 of the rbcS2 gene in its expression cassette.

Results: The obtained data confirmed that the GAME plasmid can transform the microalgae with high transformation frequency. Molecular and proteomic analyses revealed the stable and robust production of the hIL-2 by the GAME plasmid in the microalgae. According to the densimetric analysis, the microalgae can accumulate the produced protein about 0.94% of the total soluble protein content. The ELISA data confirmed that the produced hIL-2 possesses the same conformation pattern with the acceptable biological activity found naturally in humans.

Conclusion: Most therapeutic proteins need post-translational modifications for their correct conformation, biological function, and half-life. Accordingly, microalgae could be considered as a cost-effective and more powerful platform for the production of a wide range of recombinant proteins such as antibodies, enzymes, hormones, and vaccines.

Iron oxide nanoparticles: a novel elicitor to enhance anticancer flavonoid production and gene expression in Dracocephalum kotschyi hairy-root cultures

BACKGROUND

Dracocephalum kotschyi Boiss. is a valuable source of rosmarinic acid (RA) and methoxylated hydroxyflavones (such as xanthomicrol and cirsimaritin) with antioxidative and antiplatelet effects and with antiproliferative potential against various cancer cells. The extensive application of nanotechnology in hairy root cultures is a new sustainable production platform for producing these active constituents. In the present study, hairy roots derived from 4-week-old leaves and Agrobacterium rhizogenes strain ATCC15834 were used to investigate the impact of various concentrations of iron oxide nanoparticles (Fe NPs) in two elicitation time exposures (24 and 48 h) on growth, antioxidant enzyme activity, total phenolic and flavonoid content (TPC and TFC), and some polyphenols. Gene expression levels of phenylalanine ammonia-lyase (pal) and rosmarinic acid synthase (ras) were also analyzed.

RESULTS

Iron nanoparticles enhanced biomass accumulation in hairy roots. The treatment time and Fe NP dosage largely improved the activity of antioxidant enzymes, TPC and TFC. The highest RA (1194 μg g^-1 FW) content (9.7-fold), compared to controls, was detected with 24 h of exposure to 75 mg L^-1 Fe NP, which was consistent with the expression of pal and ras genes under the influence of elicitation. The xanthomicrol, cirsimaritin, and isokaempferide content was increased 11.87, 3.85, and 2.27-fold, respectively.

CONCLUSION

Stimulation of D. kotschyi hairy roots by Fe NPs led to a significant increase in the induction and production of important pharmaceutical compounds such as rosmarinic acid and xanthomicrol. © 2019 Society of Chemical Industry.

Lactobacillus plantarum induces apoptosis in gastric cancer cells via modulation of signaling pathways in Helicobacter pylori

Introduction: Gastric cancer is considered the second prevalent cause of death around the world. This type of cancer is generally induced by Helicobacter pylori which could colonize within the gastric mucosa of the infected cases. To date, triple antibiotic therapy has routinely been utilized for controlling the H. pylori- induced infection. However, this strategy has been unsuccessful, in large part because of issues such as occurring point mutations in the H. pylori genome that can induce resistance to the antibiotics administered. Recently, it has been shown that different probiotics may have strong anti-cancer effects, in which they are capable of inhibiting H. pylori by both immunological and non-immunological mechanisms. Here, we aimed at finding possible anti-cancer impacts of the probiotic bacterium Lactobacillus plantarum on gastric cancer, AGS cells. Methods: The anti-cancer effects of the conditioned media of the locally isolated L. plantarum on the AGS cells were evaluated by different analyses such as flow cytometry, DNA ladder assay, DAPI staining, and RT-PCR. Results: Our findings showed that the conditioned media of L. plantarum can inhibit both H. pylori and AGS cells through up-/down-regulation of PTEN, Bax, TLR4, and AKT genes. The exudates of the probiotic L. plantarum bacteria can increase the expression of PTEN, Bax, and TLR4, and also decrease the expression of AKT gene. Conclusion: In agreement with different reports, our results proved the anti-cancer effects of the locally isolated L. plantarum through some immunological cell signaling pathways. Accordingly, it seems the probiotics could be considered as at least a complementary treatment for different types of malignancies.

Pathogenicity of Helicobacter pylori in cancer development and impacts of vaccination

Helicobacter pylori affect around 50% of the population worldwide. More importantly, the gastric infection induced by this bacterium is deemed to be associated with the progression of distal gastric carcinoma and gastric mucosal lymphoma in the human. H. pylori infection and its prevalent genotype significantly differ across various geographical regions. Based on numerous virulence factors, H. pylori can target different cellular proteins to modulate the variety of inflammatory responses and initiate numerous "hits" on the gastric mucosa. Such reactions lead to serious complications, including gastritis and peptic ulceration, gastric cancer and gastric mucosa-associated lymphoid structure lymphoma. Therefore, H. pylori have been considered as the type I carcinogen by the Global Firm for Research on Cancer. During the two past decades, different reports revealed that H. pylori possess oncogenic potentials in the gastric mucosa through a complicated interplay between the bacterial factors, various facets, and the environmental factors. Accordingly, numerous signaling pathways could be triggered in the development of gastrointestinal diseases (e.g., gastric cancer). Therefore, the main strategy for the treatment of gastric cancer is controlling the disease far before its onset using preventive/curative vaccination. Increasing the efficiency of vaccines may be achieved by new trials of vaccine modalities, which is used to optimize the cellular immunity. Taken all, H. pylori infection may impose severe complications, for resolving of which extensive researches are essential in terms of immune responses to H. pylori. We envision that H. pylori-mediated diseases can be controlled by advanced vaccines and immunotherapies.

Stable transformation of Spirulina (Arthrospira) platensis: a promising microalga for production of edible vaccines

The planktonic blue-green microalga Spirulina (Arthrospira) platensis possesses important features (e.g., high protein and vital lipids contents as well as essential vitamins) and can be consumed by humans and animals. Accordingly, this microalga gained growing attention as a new platform for producing edible-based pharmaceutical proteins. However, there are limited successful strategies for the transformation of S. platensis, in part because of an efficient expression of strong endonucleases in its cytoplasm. In the current work, as a pilot step for the expression of therapeutic proteins, an Agrobacterium-based system was established to transfer gfp:gus and hygromycin resistance (hyg^r) genes into the genome of S. platensis. The presence of acetosyringone in the transfection medium significantly reduced the transformation efficiency. The PCR and real-time RT-PCR data confirmed the successful integration and transcription of the genes. Flow cytometry and β-glucuronidase (GUS) activity experiments confirmed the successful production of GFP and the enzyme. Moreover, the western blot analysis showed a ~ 90 kDa band in the transformed cells, indicating the successful production of the GFP:GUS protein. Three months after the transformation, the gene expression stability was validated by histochemical, flow cytometry, and hygromycin B resistance analyses.