Sliding mode control for a fractional-order non-linear glucose-insulin system.

By providing the generalisation of integration and differentiation, and incorporating the memory and hereditary effects, fractional-order modelling has gotten significant attention in the past few years. One of the extensively studied and utilised models to describe the glucose-insulin system of a human body is Bergman's minimal model. This non-linear model comprises of integer-order differential equations. However, comparison with the experimental data shows that the fractional-order version of Bergman's minimal model is a better representative of the glucose-insulin system than its original integer-order model. To design a control law for an artificial pancreas for a diabetic patient using a fractional-order model, different techniques, including feedback linearisation, have been applied in the literature. The authors' previous work shows that the fractional-order version of Bergman's model describes the glucose-insulin system in a better way than the integer-order model. This study applies the sliding mode control technique and then compares the obtained simulation results with the ones obtained using feedback linearisation.

Cadmium chloride (CdCl2) elicitation improves reserpine and ajmalicine yield in Rauvolfia serpentina as revealed by high-performance thin-layer chromatography (HPTLC).

In vitro cultures play a promising role for production of pharmaceutically important plant secondary metabolites and the use of elicitation can mitigate the low productivity of active compounds. In the present study, the influence of cadmium chloride (CdCl2) elicitation on alkaloid yield was investigated in Rauvolfia serpentina. This heavy metal was employed to enhance the yield of reserpine and ajmalicine in leaf derived callus, leaves, stems and roots of in vitro grown cultures. Different concentrations [0.05 mM (C1), 0.10 mM (C2), 0.15 mM (C3) and 0.20 mM (C4)] of CdCl2 were added to the MS medium. The elicitor's influence on callus biomass, biochemical attributes and the yield of alkaloids was monitored at regular intervals. The amendment of CdCl2 improved growth and maximum callus biomass (1.29 g fresh weight and 0.16 g dry weight) was noted at 0.15 mM (C3) after 6 days of elicitation. The addition of elicitor in medium caused cellular stress and to analyse the role of CdCl2 in plant defence responses various antioxidant enzymes, i.e., superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities were measured in treated and non-treated cultures. The antioxidant enzyme activity increased linearly with elevated levels of CdCl2 in medium; highest APX (0.88 EU min-1 mg-1protein), SOD (5.40 EU min-1 mg-1protein) and CAT (4.21 EU min-1 mg-1protein) activity were observed in leaves of in vitro regenerated plants at C4. The quantitative analyses of reserpine and ajmalicine were conducted in different elicitated tissues using high-performance thin-layer chromatography (HPTLC) method. The study reveals enriched level of reserpine and ajmalicine in cultivated tissues and the enhancement was noted up to C3 (0.15 mM) elicitor level. Reserpine yield was maximum (0.191 mg g-1 DW) in roots of in vitro regenerated plants. The accumulation of ajmalicine was, however, better in leaf derived callus at C3 (0.131 mg g-1 DW). Higher elicitor dose (0.20 mM) inhibited callus biomass growth and subsequent alkaloid accumulation. The present study indicates the use of CdCl2 as a propitious method in enhancing reserpine and ajmalicine yield in R. serpentina.

Essential oil yield estimation by Gas chromatography-mass spectrometry (GC-MS) after Methyl jasmonate (MeJA) elicitation in in vitro cultivated tissues of Coriandrum sativum L.

Coriandrum sativum is an important spice plant known for its unique fragrance. Coriander oil is also one of the major essential oils in world global market. The oil yield varies with different coriander varieties; and the content and quality of oil is governed by several factors. In recent times, a variety of technologies have been exploited to improve phyto-compounds including essential oils. In this present study, Methyl jasmonate (MeJA) was amended in medium and the yield of essential oil was measured and compared in different cultivating tissues. The cultured tissues were nonembryogenic callus and embryogenic tissues (induction, proliferation and maturation stages of embryos). MeJA acts as a signaling molecule in accumulating secondary metabolites. Four different MeJA treatments i.e. T1 = 50, T2 = 100, T3 = 150 and T4 = 200 µM, along with a control (T0) were used and the yield of coriander essential oil was estimated in different in vitro cultivating tissues by using Gas chromatography-mass spectrometry (GC-MS). The addition of MEJA enriched essential oil yield, maximum oil being in maturation stage of embryos at T3 (150 µM). Other added treatments also had varied stimulatory role. The addition of MeJA induced stress as the stress marker enzymes like superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) content were high compared to non treated tissue (T0). In T4, the CAT activity was maximum i.e. 5.83 and 6.28 mg-1 protein min-1 in Co-1 and RS respectively in matured somatic embryos. The SOD activity was also high at maturation stage of embryos at T4 (5.3 mg-1 protein min-1 in RS). The APX activity on the other, was high (3.32 mg-1 protein min-1) in induction stage of embryogenesis at T3. The comparative biochemical (sugar, protein and proline) analyses of tissues were performed and presented that had high and low essential oil. MeJA induced stress may help in accumulating essential oils in C. sativum.

Plant regeneration through somatic embryogenesis and genome size analysis of Coriandrum sativum L.

In the present study, an improved plant regeneration protocol via primary and secondary somatic embryogenesis was established in two Co-1 and Rajendra Swathi (RS) varieties of Coriandrum sativum L. Callus was induced from root explants on 2, 4-D (0.5-2.0 mg/l) supplemented MS. The addition of BA (0.2 mg/l) improved callus induction and proliferation response significantly. The maximum callus induction frequency was on 1.0 mg/l 2, 4-D and 0.2 mg/l BA added MS medium (77.5 % in Co-1 and 72.3 % in RS). The callus transformed into embryogenic callus on 2, 4-D added MS with maximum embryogenic frequency was on 1.0 mg/l. The granular embryogenic callus differentiated into globular embryos on induction medium, which later progressed to heart-, torpedo- and cotyledonary embryos on medium amended with 0.5 mg/l NAA and 0.2 mg/l BA. On an average, 2-3 secondary somatic embryos (SEs) were developed on mature primary SEs, which increased the total embryo numbers in culture. Histology and scanning electron microscopy (SEM) studies are presented for the origin, development of primary and secondary embryos in coriander. Later, these induced embryos converted into plantlets on 1.0 mg/l BA and 0.2 mg/l NAA-amended medium. The regenerated plantlets were cultured on 0.5 mg/l IBA added ½ MS for promotion of roots. The well-rooted plantlets were acclimatized and transferred to soil. The genetic stability of embryo-regenerated plant was analyzed by flow cytometry with optimized Pongamia pinnata as standard. The 2C DNA content of RS coriander variety was estimated to 5.1 pg; the primary and secondary somatic embryo-derived plants had 5.26 and 5.44 pg 2C DNA content, respectively. The regenerated plants were genetically stable, genome size similar to seed-germinated coriander plants.

Somatic embryo mediated mass production of Catharanthus roseus in culture vessel (bioreactor) - A comparative study.

The purpose of this study was to evaluate and compare the use of liquid and solid Murashige and Skoog (MS) medium in different culture vessels for mass production of Catharanthus roseus, an important source of anticancerous compounds, vincristine and vinblastine. Three media conditions i.e. agar-solidified medium (S), liquid medium in agitated conical flask (L) and growtek bioreactor (B) were used. Rapid propagation was achieved through in vitro somatic embryogenesis pathway. The process of embryogenesis has been categorized into induction, proliferation, maturation and germination stages. All in vitro embryogenesis stages were conducted by withdrawing spent liquid medium and by adding fresh MS medium. In optimized 4.52 µM 2,4-D added MS, the callus biomass growth was low in solid (1.65 g) compared to liquid medium in agitated conical flask (1.95 g) and in bioreactor (2.11 g). The number of normal somatic embryos was more in solid medium (99.75/50 mg of callus mass) compared to liquid medium used in conical flask (83.25/callus mass) and growtek bioreactor (84.88/callus mass). The in vitro raised embryos maturated in GA3 (2.60 µM) added medium; and in bioreactor the embryo growth was high, a maximum length of 9.82 mm was observed at the end of four weeks. These embryos germinated into seedlings in BAP (2.22 µM) added medium and the embryo germination ability was more (59.41%) in bioreactor compared to liquid medium in conical flask (55.5%). Shoot length (11.25 mm) was also high in bioreactor compared to agitated conical flask. The liquid medium used in agitated conical flask and bioreactor increased seedling production efficiency, at the same time it also reduced plant recovery time. The embryo generated plants grew normally in outdoor conditions. The exploitation of medium to large culture vessel or bioreactor may make the process more efficient in getting large number of Catharanthus plant as it is the only source of anti-cancerous alkaloids, vincristine and vinblastine.