Cell Cycle Arrest and Induction of Apoptosis in Colon Adenocarcinoma Cells by a DNA Intercalative Quinoline Derivative, 4-Morpholinopyrimido [4′,5′:4,5] Selenolo (2,3-b) Quinoline

Circular dichroism, topological studies, molecular docking, absorbance, and fluorescence spectral titrations were employed to study the interaction of 4-morpholinopyrimido [4′,5′:4,5] selenolo (2,3-b) quinoline (MPSQ) with DNA. The association constants of MPSQ–DNA interactions were of the order of 10⁴ M^?1. Melting temperature, topological, and docking studies confirmed that the mode of interaction was by intercalation with preference to d(GpC)–d(CpG) site of DNA. Cytotoxicity studies showed the MPSQ-induced dose-dependent inhibitory effect on the proliferation of different cancer cells. Colon adenocarcinoma (COLO 205) cells are more sensitive among the cell lines tested, with an IC₅₀ value of 15 μM. Flow cytometry revealed that MPSQ affects the cell cycle progression by arresting at G2M phase. Further, Annexin V staining, mitochondrial membrane potential assay, and caspase-3 activity assay confirmed that MPSQ leads to mitochondria-mediated apoptotic cell death in COLO 205 cells.     

Action of growth regulators on the cotyledonary stomata ofCucumis sativus L.: Structure and ontogeny

Anomocytic stomata and stomata with single subsidiary cells are commonly observed Sometimes a stoma appears anisocytic. Double cytoplasmic connections between nearby stomata and division of guard cells with persistent or degenerating nuclei are seen in GA. One or more divisions of guard cells, displaced guard cells and single guard cells with or without pore are noticed in SUC. Formation of single guard cells is a common feature in TIBA. Paracytic stomata, one and a half stomata and persistent stomatal initials are seen in SUL. COUM seems to be not inhibitory inCucumis sativus. In COL stomata with unequal guard cells, unequal stomatal cells with thickening in between but without intervening pore, stoma with double pores, persistent stomatal initials which may be solitary or in groups with varying shapes and with one or two nuclei of different shapes are noticed. The growth regulators affect the frequency of stomata, epidermal cells; stomatal index; size of guard and epidermal cells.     

Studies in the secretory glands of Hiptage sericea (Malpighiaceae)

Hiptage sericea is shown to possess both lipophilic glands and extrafloral nectaries. Both types of glands develop from a group of initials and show similarities in organisation of tissue systems and secretion. The nature of the secretory substances is however different. The occurrence and function of the glands are discussed.     

Exquisite specificity of mitogenic lectin from <Emphasis Type="Italic">Cephalosporium curvulum</Emphasis> to core fucosylated N-glycans

Lectins are carbohydrate binding proteins that are gaining attention as important tools for the identification of specific glycan markers expressed during different stages of the cancer. We earlier reported the purification of a mitogenic lectin from human pathogenic fungus Cephalosporium curvulum (CSL) that has complex sugar specificity when analysed by hapten inhibition assay. In the present study, we report the fine sugar specificity of CSL as determined by glycan array analysis. The results revealed that CSL has exquisite specificity towards core fucosylated N-glycans. Fucosylated trimannosyl core is the basic structure required for the binding of CSL. The presence of fucose in the side chain further enhances the avidity of CSL towards such glycans. The affinity of CSL is drastically reduced towards the non-core fucosylated glycans, in spite of their side chain fucosylation. CSL showed no binding to the tested O-glycans and monosaccharides. These observations suggest the unique specificity of CSL towards core fucosylated N-glycans, which was further validated by binding of CSL to human colon cancer epithelial and hepatocarcinoma cell lines namely HT29 and HepG2, respectively, that are known to express core fucosylated N-glycans, using AOL and LCA as positive controls. LCA and AOL are fucose specific lectins that are currently being used clinically for the diagnosis of hepatocellular carcinomas. Most of the gastrointestinal markers express core fucosylated N-glycans. The high affinity and exclusive specificity of CSL towards α1-6 linkage of core fucosylated glycans compared to other fucose specific lectins, makes it a promising molecule that needs to be further explored for its application in the diagnosis of gastrointestinal cancer.     

Spectroscopic investigation of alloyed quantum dot‐based FRET to cresyl violet dye

Quantum dots (QDs), bright luminescent semiconductor nanoparticles, have found numerous applications ranging from optoelectronics to bioimaging. Here, we present a systematic investigation of fluorescence resonance energy transfer (FRET) from hydrophilic ternary alloyed quantum dots (CdSeS/ZnS) to cresyl violet dye with a view to explore the effect of composition of QD donors on FRET efficiency. Fluorescence emission of QD is controlled by varying the composition of QD without altering the particle size. The results show that quantum yield of the QDs increases with increase in the emission wavelength. The FRET parameters such as spectral overlap J(λ), Förster distance R₀, intermolecular distance (r) , rate of energy transfer k_T (r), and transfer efficiency (E) are determined by employing both steady‐state and time‐resolved fluorescence spectroscopy. Additionally, dynamic quenching is noticed to occur in the present FRET system. Stern–Volmer (K_D) and bimolecular quenching constants (k_q) are determined from the Stern–Volmer plot. It is observed that the transfer efficiency follows a linear dependence on the spectral overlap and the quantum yield of the donor as predicted by the Förster theory upon changing the composition of the QD. Copyright © 2015 John Wiley & Sons, Ltd.