Secret History: Return of the Black Death Channel 4, 7-8pm In 1348 the Black Death swept through London, killing people within days of the appearance of their first symptoms. Exactly how many died, and why, has long been a mystery. This Secret History documentary follows experts as they pick through the evidence and reveal why the plague killed on such a scale. And they ask, what might be coming next?

Medscape

Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. o...

https://www.tandfonline.com/doi/pdf/10.4161/psb.6.11.17613

Influence of abiotic stress signals on secondary metabolites in plants

The origin of plant cell and tissue culture can be found in a treatise published during the mid-18th century, entitled La Physique des Arbes, that describes the formation of callus tissue following the for mation of a ring of cortex from elm trees. Over the next two centuries, the discovery of plant growth hormones, in particular auxins and cytokinins, and detailed analyses on the nutritional requirements of plants, led to the formulation of media that could maintain actively dividing cultures derived from gymnosperms, and both dicotyledon ous and monocotyledonous angiosperms. However, much of the prog ress and technological development in the in vitro propagation of plant cells, tissues, and organs has occurred during the last 25 years. Recently, plant tissue culture techniques have been used as basic tools in the rapidly expanding field of plant biotechnology for the development and clonal propagation of new and/or improved plant varieties. Plant tissue culture is used for the micropropagation of commercially valuable cultivars that include ornamentals, oil palm, Glycyrrhiza, Pyrethrum, pine, Eucalyptus, sugar cane, and potatoes. Cultured plant tissue is also used for the selection of cells and, ul timately, the regeneration of plants that are tolerant to physical stresses such as pathogens, drought, and temperature extremes, and to chemical stress agents such as salinity, herbicides, proteins, and pyrethrins. In addition, new plants have been produced by the fusion of protoplasts prepared from cultured cells of different species in cluding sunflower and french bean, tomato and potato, and various cultivars of Datura. Finally, bacterial vectors and various mechanical methods have been used to introduce foreign genes into cultured plant tissues. Genetic transformation can result in profound changes in the phenotype and/or biochemical profile of the regenerated trans genic plants that are not characteristic of the wild type. An impressive variety of technologies in tissue culture, genetic manipulation, and molecular biology have been developed for nu merous plant species. Many of these techniques, sometimes referred to as plant biotechnology, have been extensively summarized and compiled in a well-balanced collection of easy-to-follow protocols presented in three separate, but complimentary, volumes. Plant Cell, Tissue and Organ Culture consists of 22 chapters (with 86 figures) and 5 appendices. The chapters cover critical aspects of (a) the es sential requirements for the operation of a plant tissue culture lab oratory; (b) the basic procedures of micropropagation, regeneration, and somatic embryogenesis; (c) some specific applications of organ culture systems such as embryo rescue and culture, and anther and microspore culture for haploid and double haploid production; (d) elementary transformation technology; and (e) useful microtechnique and analytical protocols specifically adapted to cultured tissues and cells. The appendices provide a convenient summary of media for mulations and commercial suppliers for the materials described in the text.

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Plant Cell, Tissue and Organ Culture

Plant cell and tissue cultures can be established routinely under sterile conditions from explants, such as plant leaves, stems, roots, meristems etc for both the ways for multiplication and extraction of secondary metabolites. Strain improvement, methods for the selection of high-producing cell lines, and medium optimizations can lead to an enhancement in secondary metabolite production. However, most often trials with plant cell cultures fail to produce the desired products. In such cases, strategies to improve the production of secondary metabolites must be considered. One of the main problems encountered is the lack of basic knowledge of the biosynthetic routes, and mechanisms responsible for the production of plant metabolites. Where the productivity of the desired metabolites is limited by the lack of particular precursors, biotransformation using an exogenous supply of biosynthetic precursors, genetic manipulation and metabolic engineering may improve the accumulation of compounds. Feedback inhibition of metabolic enzymes as well as inhibition of membrane transport can be eliminated by the accumulation of synthesized products in a second phase introduced into the aqueous medium. Organ cultures and in vitro biomass production often have sites of synthesis and storage of secondary metabolites in separate compartments. Elicitors, compounds triggering the formation of secondary metabolites, can be abiotic or biotic. Natural elicitors include polysaccharides such as pectin and chitosan, which are also used in the immobilization and permeabilization of plant cells. Immobilization with suitable bioreactor system provides several advantages, such as continuous process operation, but for the development of an immobilized plant cell culture process, natural or artifically induced secretion of the accumulated product into the surrounding medium is necessary. The present review highlights the nature, applications, perspective and scale up methods for the production of valuable secondary metabolites in vitro.

	 

	Key words: Plant cell cultures, secondary metabolites, biotransformation, biosynthetic pathways, elicitation, immobilization, bioreactors.

/pdf/a-review-on-trends-in-production-of-secondary-metabolites-1i9vvpbtmc.pdf

A review on trends in production of secondary metabolites from higher plants by in vitro tissue, organ and cell cultures.

A review on chitosan-based adsorptive membranes.

Chitosan, a natural biopolymer composed of a linear polysaccharide of α (1–4)-linked 2-amino 2-deoxy β-d glucopyranose was synthesized by deacetylation of chitin, which is one of the major structural elements, that forms the exoskeleton of crustacean shrimps. The present study was undertaken to prepare chitosan from shrimp shell waste. The physiochemical properties like degree of deacetylation (74.82 %), ash content (2.28 %), and yield (17 %) of prepared chitosan indicated that that shrimp shell waste is a good source of chitosan. Functional property like water-binding capacity (1,136 %) and fat-binding capacity (772 %) of prepared chitosan are in total concurrence with commercially available chitosan. Fourier Transform Infra Red spectrum shows characteristic peaks of amide at 1,629.85 cm−1 and hydroxyl at 3,450.65 cm−1. X-ray diffraction pattern was employed to characterize the crystallinity of prepared chitosan and it indicated two characteristic peaks at 10° and 20° at (2θ). Scanning electron microscopy analysis was performed to determine the surface morphology. Heavy metal removal efficiency of prepared chitosan was determined using atomic absorption spectrophotometer. Chitosan was found to be effective in removing metal ions Cu(II), Zn(II), Fe(II) and Cr(IV) from industrial effluent. Antibacterial activity of the prepared chitosan was also determined against Xanthomonas sp. isolated from leaves affected with citrus canker.

/pdf/studies-on-heavy-metal-removal-efficiency-and-antibacterial-39dyjmngju.pdf

Studies on heavy metal removal efficiency and antibacterial activity of chitosan prepared from shrimp shell waste

The main aim of the current study is to explore the bioactive potential of Streptomyces sp. VITJS8 isolated from the marine saltern. The cultural, biochemical, and morphological studies were performed to acquire the characteristic features of the potent isolate VITJS8. The 16Sr DNA sequencing was performed to investigate the phylogenetic relationship between the Streptomyces genera. The structure of the compound was elucidated by gas chromatography-mass spectrometry (GC-MS), infra-red (IR), and ultra-violet (UV) spectroscopic data analysis. The GC-MS showed the retention time at 22.39 with a single peak indicating the purity of the active compound, and the molecular formula was established as C14H9ONCl2 based on the peak at m/z 277 [M](+). Furthermore, separated by high-performance liquid chromatography (HPLC), their retention time (t r) 2.761 was observed with the absorption maxima at 310 nm. The active compound showed effective inhibitory potential against four clinical pathogens at 500 μg/mL. The antioxidant activity was found effective at the IC50 value of 500 μg/mL with 90 % inhibition. The 3-(4,5-dimethylthiazol-2-yl)-2,5-ditetrazolium bromide (MTT) assay revealed the cytotoxicity against HepG2 cells at IC50 of 250 μg/mL. The progression of apoptosis was evidenced by morphological changes by nuclear staining. The DNA fragmentation pattern was observed at 250 μg/mL concentration. Based on flow cytometric analysis, it was evident that the compound was effective in inhibiting the sub-G0/G1 phase of cell cycle. The in vitro findings were also supported by the binding mode molecular docking studies. The active compound revealed minimum binding energy of -7.84 and showed good affinity towards the active region of topoisomerase-2α that could be considered as a suitable inhibitor. Lastly, we performed 30 ns molecular dynamic simulation analysis using GROMACS to aid in better designing of anticancer drugs. Simulation result of root mean square deviation (RMSD) analysis showed that protein-ligand complex reaches equilibration state around 10 ns that illustrates the docked complex is stable. We propose the possible mechanism of sesquiterpenes to play a significant role in antitumor cascade. Hence, our studies open up a new facet for a potent drug as an anticancer agent.

Binding and molecular dynamic studies of sesquiterpenes (2R-acetoxymethyl-1,3,3-trimethyl-4t-(3-methyl-2-buten-1-yl)-1t-cyclohexanol) derived from marine Streptomyces sp. VITJS8 as potential anticancer agent

β-Galactosidase from Lactobacillus plantarum HF571129 was immobilized on zinc oxide nanoparticles (ZnO NPs) using adsorption and cross-linking technique. Immobilized β-galactosidase showed broad-spectrum pH optima at pH 5–7.5 and temperature 50–60 °C. Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) showed that β-galactosidase successfully immobilized onto supports. Due to the limited diffusion of high molecular weight substrate, K
 m of immobilized enzyme slightly increased from 6.64 to 10.22 mM, while V
 max increased from 147.5 to 192.4 µmol min−1 mg−1 as compared to the soluble enzyme. The cross-linked adsorbed enzyme retained 90 % activity after 1-month storage, while the native enzyme showed only 74 % activity under similar incubation conditions. The cross-linked β-galactosidase showed activity until the seventh cycle and maintained 88.02 % activity even after the third cycle. The activation energy of thermal deactivation from immobilized biocatalyst was 24.33 kcal/mol with a half-life of 130.78 min at 35 °C. The rate of lactose hydrolysis for batch and packed bed was found to be 0.023 and 0.04 min−1.

Immobilization of β -galactosidase from Lactobacillus plantarum HF571129 on ZnO nanoparticles: characterization and lactose hydrolysis

Gymnemic Acid Production in Suspension Cell Cultures of Gymnema sylvestre

The main aim of the study was to evaluate the bioactive properties of ethyl acetate crude extract of Streptomyces parvulus VITJS11 with a view to assess their therapeutic potential. The biological activity of ethyl acetate extract was tested against fungal and bacterial pathogens. The free radical scavenging potential of the crude extract was determined by DPPH assay. The chemo preventive properties of S. parvulus VITJS11 ethyl acetate extract was examined by MTT assay on HepG2 cells. The morphological, physiological and the biochemical properties of the strain S. parvulus VITJS11 was confirmed by conventional methods. Genotypic characterization was done using 16S r-DNA partial gene amplification and sequencing. The authenticity of the crude chemical constitutes were determined by the GC-MS. The ethyl acetate extract of VITJS11 showed maximum antifungal activity against three Aspergillus species and prominent antibacterial activity against two Gram positive and Gram negative bacteria at 20 mg/mL. The antioxidant potential of the crude extract exhibited strong reducing power activity at 5mg/ mL with 85% inhibition and the cytotoxic effect was found with IC50 of 500µg/ mL on HepG2 cell lines. The GC-MS analysis and the chromatogram patterns revealed 16 peaks, indicating the presence of bioactive constituents, which included several important organic compounds, namely 9-(2',2'-dimethylpropanoilhydrazono)-3,6-dichloro-2,7-Bis-[2-(diethylamino)-ethoxy]fluorine (23.1) Dotriacontylpentafluoropropionate,(25.0) Octadecanoic acid, (20.0); Trans-2-methyl-4-n-butylthiane, S, S-dioxide.(19.0). The results showed the benefit of ethyl acetate extract from S. parvulus VITJS11 in treating microbial infections and indicated their broad spectrum of activity with beneficial virtues for therapeutic use.

/pdf/antimicrobial-antioxidant-and-cytotoxic-activity-of-2g9qoefke0.pdf

C. Subathra Devi

Papers

Studies on heavy metal removal efficiency and antibacterial activity of chitosan prepared from shrimp shell waste

Binding and molecular dynamic studies of sesquiterpenes (2R-acetoxymethyl-1,3,3-trimethyl-4t-(3-methyl-2-buten-1-yl)-1t-cyclohexanol) derived from marine Streptomyces sp. VITJS8 as potential anticancer agent

Immobilization of β -galactosidase from Lactobacillus plantarum HF571129 on ZnO nanoparticles: characterization and lactose hydrolysis

Gymnemic Acid Production in Suspension Cell Cultures of Gymnema sylvestre

Antimicrobial, Antioxidant and Cytotoxic Activity of MarineStreptomyces parvulus VITJS11 Crude Extract