Evaluation of antioxidant potential and reducing power of callus induced from leaves of Asystasia gangetica (L.) T.Anderson

Objective: To evaluate the bioactive mols. and antioxidant potential of callus induced from leaves of Asystasia gangetica. Methods: In this report, the leaves of A.gangetica (AG) were incubated with Murashige and Skoog (MS) medium supplemented with combinations of auxins and cytokinins for callus induction. The qual. estn. of bioactive mols. like flavonoids, phenolics, tannins and their antioxidant potential were investigated. The ability of radical scavenging activity and reducing power of methanolic, ethanolic and aq. ext. using DPPH, FRAP and Phopshomlybdate assay were carried out. Results: Callus was induced on MS medium supplemented with various concn. and combination of auxins and cytokinins.Maximum percentage of callusing was seen on media supplemented with 2,​4-​Dichlorophenoxyaceticacid 5mg​/L or combination of Kinetin 2mg​/L and 2mg​/L Naphthaleneaceticacid.The total phenolic content, flavonoids and tannins in callus were estd. in various solvents. Further, the callus showed the FRAP values of 17.67 ± 0.0, 17.30 ± 1.830 and 23.81 ± 0.945 μg AAE / mg ext. for methanolic, ethanolic and aq. ext. resp. Methanolic ext. showed highest DPPH scavenging activity and reducing abilty. Conclusion:A.gangetica callus had substantial amt. of bioactive mols. exhibiting potent antioxidant activity and reducing ability. Development of appropriate strategies for enhancing the bioactive mols. in callus could have far-​reaching implications for isolation of novel antioxidant mols. for human health

Telomere functions in the translocation heterozygote, Rhoeo spathacea

The permanent translocation heterozygote, Rhoeo spathacea shows a characteristic ring of all chromosomes at metaphase-I of male meiosis. Elimination of bivalent formation completely due to extreme heterozygosity poses a special problem for reductional division at meiosis-I where the maternal and the paternal sets need to be separated to different poles. Unlike bivalent meiosis, the functions of SC formation, pairing and recombination required for reductional segregation have to be fulfilled by only telomeres which are the only areas of contact among the chromosomes in the ring. The participation of telomeres in these events assumes significance in view of the balanced lethal gene system imposed by translocation heterozygosity, and the particular requirement that only alternate chromosomes segregated to the same pole results in fertile pollen. This paper throws some light on the telomere functions in R. spathacea in the light of our present understanding of telomere biology. The prospects of using R. spathacea as a model organism to dissect molecular aspects of several telomere related functions are also discussed

Ultrastructural Evidence for the Flawless Transmission of a Dicentric Chromosome in Aloe vera. L.

Electronmicroscopic study has revealed a dicentric chromosome in the root tip cells of diploid Aloe vera, hitherto unreported in somatic cells of plants. The morphological aspects are described and the implications of such structural features of the dicentric are addressed in a functional perspective. It is also proposed that the presence of two functional kinetochores need not invariably lead to chromosome instability and loss

An Efficient and Improved Method of In Planta Transformation in Arachis hypogaea. L

Arachis hypogaea (Peanut) has long been the focus of conventional breeding efforts because of its importance as a source of high quality oil and proteins. Genetically modifying peanut plants by molecular techniques has been an important tool for introduction of agronomical useful genes responsible for improvement of economically important traits. In the present study, an improvised in planta Agrobacterium tumefaciens mediated genetic transformation was carried out in Arachis hypogaea L.cv. TMV-2. Agrobacterium tumefaciens strain LBA4404 harboring the binary vector pCAMBIA 1301 was used for transformation of embryo axes with one of the cotyledon intact. The putative transformed embryos were germinated on MS basal medium supplemented with 40 mg/L hygromycin along with 250 mg/L cefataxime thus allowing direct selection of plants. After germination on MS medium, the putative transgenic plants were moved to sterile soilrite, maintained in greenhouse. The transgenic plants were validated by GUS histochemical assay and integration of transgene into peanut genome was confirmed by genomic DNA PCR. The optimized protocol could be applicable for other plant species for high transformation efficiency

In vitro Regeneration, Antioxidant Potential, and Genetic Fidelity Analysis of Asystasia gangetica (L.) T.Anderson

An effective protocol for the plant regeneration via direct and indirect organogenesis has been developed from leaf explants of Asystasia gangetica (L.), cultured on Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of auxin and cytokinins. Approximately 86% of explants produced direct shoots on MS medium containing 0.5 mg L-1 6-benzyladenine (BA) and 10 μg L-1 Triacontanol (TRIA) with a maximum of 4.82 ± 0.29 shoots per leaf segment. For production of callus-mediated plantlets (indirect), primarily callus was induced on MS medium containing 2 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D), which was then subcultured on medium with 0.1 mg L-1 naphthaleneacetic acid (NAA), 0.5 mg L-1 BA, and 1 to 8 mg L-1 2-isopentenyl adenine (2iP) in order to develop organogenic callus and subsequent shoot induction. A maximum of 6.84 ± 0.05 shoots per callus clump was obtained on MS media supplemented with 4 mg L-1 2iP, 0.5 mg L-1 BA, and 0.1 mg L-1 NAA. The shootlets produced roots when cultured on half-strength MS media supplemented with 2 mg L-1 indole-3-butyric acid (IBA). In vitro propagated plantlets were hardened on soil rite and acclimatized to field condition with 85% survivability. The chlorophyll content of acclimatized plants was comparable with that of the mother plant, while stomatal micromorphology of regenerated plants exhibited no abnormalities. The radical scavenging and antioxidant activity of methanolic extract of leaves were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing ability of plasma (FRAP), and phosphomolybdenum test. In all experiments, regenerated plants exhibited enhanced antioxidant potential indicating micropropagated plants could be exploited for isolation of novel biomolecules. Further, the genetic homogeneity of acclimatized plants was confirmed by PCR-based start codon targeted (SCoT) markers and ycf1b DNA barcoding primers which exhibited monomorphic bands identical to the normal mother plant and no variations were observed

Molecular and functional characterization of RecD, a novel member of the SF1 family of helicases, from Mycobacterium tuberculosis

The annotated whole-genome sequence of Mycobacterium tuberculosis revealed the presence of a putative recD gene; however, the biochemical characteristics of its encoded protein product (MtRecD) remain largely unknown. Here, we show that MtRecD exists in solution as a stable homodimer. Protein-DNA binding assays revealed that MtRecD binds efficiently to single-stranded DNA and linear duplexes containing 5′ overhangs relative to the 3′ overhangs but not to blunt-ended duplex. Furthermore, MtRecD bound more robustly to a variety of Y-shaped DNA structures having ≥18-nucleotide overhangs but not to a similar substrate containing 5-nucleotide overhangs. MtRecD formed more salt-tolerant complexes with Y-shaped structures compared with linear duplex having 3′ overhangs. The intrinsic ATPase activity of MtRecD was stimulated by single-stranded DNA. Site-specific mutagenesis of Lys-179 in motif I abolished the ATPase activity of MtRecD. Interestingly, although MtRecD-catalyzed unwinding showed a markedly higher preference for duplex substrates with 5′ overhangs, it could also catalyze significant unwinding of substrates containing 3′ overhangs. These results support the notion that MtRecD is a bipolar helicase with strong 5′ → 3′ and weak 3′ → 5′ unwinding activities. The extent of unwinding of Y-shaped DNA structures was ∼3-fold lower compared with duplexes with 5′ overhangs. Notably, direct interaction between MtRecD and its cognate RecA led to inhibition of DNA strand exchange promoted by RecA. Altogether, these studies provide the first detailed characterization of MtRecD and present important insights into the type of DNA structure the enzyme is likely to act upon during the processes of DNA repair or homologous recombination

Comparative study of phytochemicals and bioactivities of the leaf extracts of Curcuma amada and Curcuma karnatakensis

Curcuma species are known for their medicinal properties, and it is essential to evaluate under-explored species for their phytocomposition and their practical applications. The present work evaluated the phytochemical, antioxidant, antimitotic, and antiproliferative properties of aqueous methanolic extract from leaves of Curcuma amada and Curcuma karnatakensis. Quantitative phytochemical assays revealed higher amounts of phenols (11.00 ± 0.29 mg GAE / g DW), flavonoids (8.80 ± 0.03 mg QE / g DW), tannins (3.30 ± 0.02 mg CE / g DW) and saponins (53.23 ± 0.02 mg DE / g DW) in C.amada extracts compared to C. karnatakensis. Aqueous methanolic extract of C. amada exhibited higher radical scavenging activity for DPPH (IC50= 127.70 ± 4.05 μg / mL), Ferrous ion chelation (IC50= 287.83 ± 6.38 μg / mL) and CUPRAC antioxidant potential value of 6.33 ± 0.06 mg Trolox equivalent (TE)/g DW. C. karnatakensis exhibited higher ABTS radical scavenging activity with an IC50 value of 96.97 ± 1.58 μg / mL. Further, GC-MS analysis of extracts identified several sesquiterpenoids in both species having significant biological activities. The two extracts exhibited mild antimitotic and antiproliferative properties against Allium root cells and yeast cells. C. amada leaf extract showed higher anti-inflammatory properties than C. karnatakensis. This is the first comprehensive report on leaf phytocomposition, which could be exploited for pharmacological utilization