Exploring Newer Biosynthetic Gene Clusters in Marine Microbial Prospecting

Marine Biotechnology - Marine microbes genetically evolved to survive varying salinity, temperature, pH, and other stress factors by producing different bioactive metabolites. These microbial...     

Induction of p53‐independent growth inhibition in lung carcinoma cell A549 by gypenosides

The objectives of this study are to investigate antiproliferative effect and mechanisms of bioactive compounds from Gynostemma pentaphyllum (G. pentaphyllum) on lung carcinoma cell A549. Saponins, carotenoids and chlorophylls were extracted and fractionated by column chromatography, and were subjected to high‐performance liquid chromatography‐mass spectrometry analyses. The saponin fraction, which consisted mainly of gypenoside (Gyp) XXII and XXIII, rather than the carotenoid and chlorophyll ones, was effective in inhibiting A549 cell growth in a concentration‐ and a time‐dependent manner as evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. The estimated half maximal inhibitory concentration (IC₅₀) of Gyp on A549 cells was 30.6 μg/ml. Gyp was further demonstrated to induce an apparent arrest of the A549 cell cycle at both the S phase and the G2/M phase, accompanied by a concentration‐ and a time‐dependent increase in the proportions of both the early and late apoptotic cells. Furthermore, Gyp down‐regulated cellular expression of cyclin A and B as well as BCL‐2, while up‐regulated the expression of BAX, DNA degradation factor 35 KD, poly [ADP‐ribose] polymerase 1, p53, p21 and caspase‐3. Nevertheless, both the treatment of a p53 inhibitor, pifithrin‐α, and the small hairpin RNA‐mediated p53 knockdown in the A549 cells did not alter the growth inhibition effect induced by Gyp. As a result, the cell cycle arrest and apoptosis of A549 cells induced by Gyp would most likely proceed through p53‐independent pathway(s).     

Gene delivery using microinjection of agrobacterium to embryonic shoot apical meristem of elite indica rice cultivars

A method of gene transfer to elite indica rice cultivars (BPT5204, IW-Ponni and CR1009) by microinjecting the embryonic shoot apical meristem (ESAM) of seeds with Agrobacterium is described. The ESAM microinjected with Agrobacterium cells containing binary plasmid was incubated in co-cultivation media at 28°C for 3?days in the dark and subsequently transferred to selection medium with appropriate supplements and antibiotic. The frequency of gene transfer under various concentrations of Agrobacterium and acetosyringone used were analyzed by staining for the presence of the marker enzyme ??-glucuronidase (GUS) carried as part of the binary plasmid and growth in the presence of antibiotic hygromycin. Results of this investigation show that the maximum efficiency of gene transfer took place when Agrobacterium was used at an OD₆₀₀ of 0.3 and grown in the presence of 20?mg?1^?1 acetosyringone.     

Micellar oleic and eicosapentaenoic acid but not linoleic acid influences the β-carotene uptake and its cleavage into retinol in rats

Improving the bioavailability of β-carotene is vital to manage vitamin A deficiency. The influence of micellar oleic (OA), linoleic (LA) and eicosapentaenoic (EPA) acids on plasma β-carotene response and its conversion to retinol has been studied in rats employing single (9 h time course) and repeated (10 days) dose administrations. After a single dose, the levels (area under the curve) of plasma β-carotene and retinyl palmitate in OA and EPA groups were higher (p < 0.05) by 13, 7 and 11, 6 folds than LA group. The liver β-carotene level in OA and EPA groups were higher (p < 0.05) by 3 and 1.2 folds than LA group. After repeated dose, the plasma β-carotene and retinyl palmitate levels in OA (6.2%, 51.7%) and EPA (25.4%, 17.23%) groups were higher (p < 0.05) than LA group. The liver β-carotene level in OA (21.2%) and EPA (17.6%) groups were higher (p < 0.05) than LA group. In both the experiments, the activity of β-carotene 15,15′-dioxygenase in the intestinal mucosa and plasma triglyceride levels were also higher in OA and EPA groups than LA group. β-Carotene excreted through urine and feces of OA and EPA groups was lower than the LA group. These results demonstrate an improved absorption and metabolism of β-carotene when fed mixed micelles with OA or EPA compared with LA. Although the mechanism involved in selective absorption of fatty acids needs further studies, intestinal β-carotene uptake and its conversion to vitamin A can be modulated using specific fatty acids.     

2-Aminobenzimidazoles as potent Aurora kinase inhibitors

This Letter describes the discovery and key structure–activity relationship (SAR) of a series of 2-aminobenzimidazoles as potent Aurora kinase inhibitors. 2-Aminobenzimidazole serves as a bioisostere of the biaryl urea residue of SNS-314 (1c), which is a potent Aurora kinase inhibitor and entered clinical testing in patients with solid tumors. Compared to SNS-314, this series of compounds offers better aqueous solubility while retaining comparable in vitro potency in biochemical and cell-based assays; in particular, 6m has also demonstrated a comparable mouse iv PK profile to SNS-314.     

Chemical shift optimization in multidimensional NMR spectra by AUREMOL-SHIFTOPT

A problem often encountered in multidimensional NMR-spectroscopy is that an existing chemical shift list of a protein has to be used to assign an experimental spectrum but does not fit sufficiently well for a safe assignment. A similar problem occurs when temperature or pressure series of n-dimensional spectra are to be evaluated automatically. We have developed two different algorithms, AUREMOL-SHIFTOPT1 and AUREMOL-SHIFTOPT2 that fulfill this task. In the present contribution their performance is analyzed employing a set of simulated and experimental two-dimensional and three-dimensional spectra obtained from three different proteins. A new z-score based on atom and amino acid specific chemical shift distributions is introduced to weight the chemical shift contributions in different dimensions properly.     

Inorganic Polyphosphate Modulates TRPM8 Channels

Polyphosphate (polyP) is an inorganic polymer built of tens to hundreds of phosphates, linked by high-energy phosphoanhydride bonds. PolyP forms complexes and modulates activities of many proteins including ion channels. Here we investigated the role of polyP in the function of the transient receptor potential melastatin 8 (TRPM8) channel. Using whole-cell patch-clamp and fluorescent calcium measurements we demonstrate that enzymatic breakdown of polyP by exopolyphosphatase (scPPX1) inhibits channel activity in human embryonic kidney and F-11 neuronal cells expressing TRPM8. We demonstrate that the TRPM8 channel protein is associated with polyP. Furthermore, addition of scPPX1 altered the voltage-dependence and blocked the activity of the purified TRPM8 channels reconstituted into planar lipid bilayers, where the activity of the channel was initiated by cold and menthol in the presence of phosphatidylinositol 4,5-biphosphate (PtdIns(4,5)P₂). The biochemical analysis of the TRPM8 protein also uncovered the presence of poly-(R)-3-hydroxybutyrate (PHB), which is frequently associated with polyP. We conclude that the TRPM8 protein forms a stable complex with polyP and its presence is essential for normal channel activity.     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration of <Emphasis Type="Italic">Melothria maderaspatana</Emphasis> via indirect organogenesis

An effective protocol was developed for in vitro regeneration of the Melothria maderaspatana via indirect organogenesis in liquid and solid culture systems. Organogenesis was achieved from liquid culture calluses derived from leaf and petiole explants of mature plants. Organogenic calluses (98.2?±?0.36 and 94.8?±?0.71%) were induced from both leaf and petiole explants on Murashige and Skoog (MS) liquid medium containing 6.0 µM 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 µM thidiazuron (TDZ); and 6.0 µM 2,4-D and 1.0 µM benzyladenine (BA) combinations, respectively. Adventitious shoot regeneration (68.2?±?0.06 shoots per explant) was achieved on MS medium supplemented with 2.0 µM BA, 4.0 µM TDZ, 10% v/v coconut water and 0.06 mM glutamine from leaf-derived calluses. Petiole-derived calluses produced adventitious shoots (45.4?±?0.09 shoots per explant) on MS medium fortified with 2.0 µM BA, 4.0 µM TDZ, 10% v/v coconut water, and 0.08 mM glutamine. Elongation of shoots occurred in MS medium with 2.0 µM gibberellic acid (GA₃). Regenerated shoots (2–3 cm in length) rooted (74.2?±?0.38%) and hardened (85?±?1.24%) when they were transferred to 1/2-MS medium supplemented with 3.0 µM indole-3-butyric acid (IBA) followed by garden soil, vermiculate, and sand (2:1:1 ratio) mixture. The elongated shoots (4–5 cm in length) were exposed simultaneously for rooting as well as hardening (100%) in moistened [(1/8-MS basal salt solution with 5 µM IBA and 100 mg l^?1 Bavistin® (BVN)] garden soil, vermiculate, and sand (2:1:1 ratio) mixture. Subsequently, the plants were successfully established in the field. The survival percentage differed with seasonal variations.