Banded krait minor satellite (Bkm) contains sex and species-specific repetitive DNA

A novel class of repetitive DNA was isolated from a Bkm DNA library by exclusion hybridization. This sequence was mapped to the short arm of the W chromosome of banded krait, Bungarus fasciatus. Southern blot hybridization showed that these sequences are sex and species specific. Sequence analysis of a 206 bp long clone, BR87, revealed the presence of a tandem array of two internal repeat units of 18–19 bp alternating with each other with a gap of 1,2 or 3 nucleotides. To our knowledge, this is the first report of an exclusively W chromosome-and species-specific repeat isolated from any reptile. The functional significance of this sequence based on its organisation is discussed.     

Improvement of antagonism and carbendazim tolerance in native Trichoderma isolates through ethyl methane sulfonate (EMS) mutagenesis

Genetic enhancement of TCT₄ and TCT₁₀ was aimed in the present paper. Trichoderma reesei (TCT₁₀/M₁₈) mutant isolate evolved by ethyl methane sulfonate mutations was found to exhibit altered properties compared to its parent isolates. This mutant grew well in the potato dextrose agar (PDA) medium containing carbendazim (50 ppm). RAPD-PCR results suggested the uniqueness of mutants, which was useful in differentiating mutant and wild Trichoderma isolates. These mutants established well in the rhizosphere of rough lemon seedlings. The seedlings treated with carbendazim followed by an application of carbendazim-resistant mutant (TCT₁₀/M₁₈) resulted in a better seedling emergence and a less dry root rot disease caused by Fusarium solani in nursery conditions.     

Exploration of natural compounds as sources of new bifunctional scaffolds targeting cholinesterases and beta amyloid aggregation: The case of chelerythrine

The presented project started by screening a library consisting of natural and natural based compounds for their acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity. Active compounds were chemically clustered into groups and further tested on the human cholinesterases isoforms. The aim of the presented study was to identify compounds that could be used as leads to target two key mechanisms associated with the AD’s pathogenesis simultaneously: cholinergic depletion and beta amyloid (Aβ) aggregation. Berberin, palmatine and chelerythrine, chemically clustered in the so-called isoquinoline group, showed promising cholinesterase inhibitory activity and were therefore further investigated. Moreover, the compounds demonstrated moderate to good inhibition of Aβ aggregation as well as the ability to disaggregate already preformed Aβ aggregates in an experimental set-up using HFIP as promotor of Aβ aggregates. Analysis of the kinetic mechanism of the AChE inhibition revealed chelerythrine as a mixed inhibitor. Using molecular docking studies, it was further proven that chelerythrine binds on both the catalytic site and the peripheral anionic site (PAS) of the AChE. In view of this, we went on to investigate its effect on inhibiting Aβ aggregation stimulated by AChE. Chelerythrine showed inhibition of fibril formation in the same range as propidium iodide. This approach enabled for the first time to identify a cholinesterase inhibitor of natural origin—chelerythrine—acting on AChE and BChE with a dual ability to inhibit Aβ aggregation as well as to disaggregate preformed Aβ aggregates. This compound could be an excellent starting point paving the way to develop more successful anti-AD drugs.     

Nuclear magnetic resonance and thermal studies on the interaction between salicylic acid and model membranes

DSC and (1H and 31P) NMR measurements are used to investigate the perturbation caused by the keratolytic drug, salicylic acid (SA) on the physicochemical properties of the model membranes. Model membranes (in unilamellar vesicular (ULV) form) in the present studies are prepared with the phospholipids, dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylethanolamine (DPPE), dipalmitoyl phosphatidic acid (DPPA) and mixed lipid DPPC-DPPE (with weight ratio, 2.5:2.2). These lipids have the same acyl (dipalmitoyl) chains but differed in the headgroup. The molar ratio of the drug to lipid (lipid mixture), is in the range 0 to 0.4. The DSC and NMR results suggest that the lipid head groups have a pivotal role in controlling (i) the behavior of the membranes and (ii) their interactions with SA. In the presence of SA, the main phase transition temperature of (a) DPPE membrane decreases, (b) DPPA membrane increases and (c) DPPC and DPPC-DPPE membranes are not significantly changed. The drug increases the transition enthalpy (i.e., acyl chain order) in DPPC, DPPA and DPPC-DPPE membranes. However, the presence of the drug in DPPC membrane formed using water (instead of buffer), shows a decrease in the transition temperature and enthalpy. In all the systems studied, the drug molecules seem to be located in the interfacial region neighboring the glycerol backbone or polar headgroup. However, in DPPC-water system, the drug seems to penetrate the acyl chain region also.     

Minimal structural rearrangement of the cytoplasmic pore during activation of the 5-HT3A receptor

Ligand-gated ion channel receptors mediate the response of fast neurotransmitters by opening in less than a millisecond. Here, we investigated the activation mechanism of a serotonin-gated receptor (5-HT(3A)) by systematically introducing cysteine substitutions throughout the pore-lining M1-M2 loop and M2 transmembrane domain. We hypothesized that multiple cysteines in the narrowest region of the pore, which together can form a high affinity binding site for metal cations, would reveal changes in pore structure during gating. Using cadmium (Cd2+) as a probe, two cysteine substitutions in the cytoplasmic selectivity filter, S2'C and, to a lesser extent, G-2'C, showed high affinity inhibition with Cd2+ when applied extracellularly in the open state. Cd2+ inhibition in S2'C was attenuated if applied in the presence of an open-channel inhibitor and showed voltage-dependent recovery, indicating a direct effect of Cd2+ in the pore. When applied intracellularly, Cd2+ appeared to bind S2'C receptors in the closed state. The ability of cysteine side chains at the 2' and -2' positions to coordinate Cd2+ in both the native open and closed states of the channel suggests that the cytoplasmic selectivity filter of 5-HT(3A) receptors maintains a narrow pore during channel gating.     

3-[6-(2-Dimethylamino-1-imidazol-1-yl-butyl)-naphthalen-2-yloxy]-2,2-dimethyl-propionic acid as a highly potent and selective retinoic acid metabolic blocking agent

3-[6-(2-Dimethylamino-1-imidazol-1-yl-butyl)-naphthalen-2-yloxy]-2,2-dimethyl-propionic acid and analogs were designed and synthesized as highly potent and selective CYP26 inhibitors, serving as retinoic acid metabolic blocking agents (RAMBAs), with demonstrated in vivo efficacy to increase the half-life of exogenous atRA.     

Regulation of low density lipoprotein receptor mRNA levels by estradiol 17β and chorionic gonadotropin in human placenta

Inhibition of synthesis of estradiol 17 by the addition of inhibitors of aromatase, a key enzyme in the biosynthesis of estradiol 17, or addition of tamoxifen - an estrogen receptor antagonist, to human placental minces resulted in an increase in the level of LDL-receptor mRNA. This increase could be blocked by the simultaneous addition of estradiol 17. A concentration dependent effect of estradiol 17 on the level of LDL-receptor mRNA was seen both in first trimester, and term placenta. Addition of human chorionic gonadotropin (hCG) to term placental minces also increased the LDL-receptor mRNA levels. When hCG and cycloheximide were added together, an additive effect was observed. The results obtained in this study suggest that the LDL-receptor mRNA levels in the human placenta are regulated by estradiol 17 and hCG.     

Synthesis, biological evaluation and molecular docking studies of stellatin derivatives as cyclooxygenase (COX-1, COX-2) inhibitors and anti-inflammatory agents

Stellatin (4), isolated from Dysophylla stellata is a cyclooxygenase (COX) inhibitor. The present study reports the synthesis and biological evaluation of new stellatin derivatives for COX-1, COX-2 inhibitory and anti-inflammatory activities. Eight derivatives showed more pronounced COX-2 inhibition than stellatin and, 17 and 21 exhibited the highest COX-2 inhibition. They also exhibited the significant anti-inflammatory activity in TPA-induced mouse ear edema assay and their anti-inflammatory effects were more than that of stellatin and indomethacin at 0.5 mg/ear. The derivatives were further evaluated for antioxidant activity wherein 16 and 17 showed potent free radical scavenging activity against DPPH and ABTS radicals. Molecular docking study revealed the binding orientations of stellatin and its derivatives into the active sites of COX-1 and COX-2 and thereby helps to design the potent inhibitors.