Calcium responses of circadian pacemaker neurons of the cockroach Rhyparobia maderae to acetylcholine and histamine

The accessory medulla (aMe) is the pacemaker that controls circadian activity rhythms in the cockroach Rhyparobia maderae. Not much is known about the classical neurotransmitters of input pathways to the cockroach circadian system. The circadian pacemaker center receives photic input from the compound eye, via unknown excitatory and GABAergic inhibitory entrainment pathways. In addition, neuropeptidergic inputs couple both pacemaker centers. A histamine-immunoreactive centrifugal neuron connects the ventral aMe with projection areas in the lateral protocerebrum and may provide non-photic inputs. To identify neurotransmitters of input pathways to the circadian clock with Fura-2-dependent Ca²⁺ imaging, primary cell cultures of the adult aMe were stimulated with acetylcholine (ACh), as the most prominent excitatory, and histamine, as common inhibitory neurotransmitter. In most of aMe neurons, ACh application caused dose-dependent increases in intracellular Ca²⁺ levels via ionotropic nicotinic ACh receptors. These ACh-dependent rises in Ca²⁺ were mediated by mibefradil-sensitive voltage-activated Ca²⁺ channels. In contrast, histamine application decreased intracellular Ca²⁺ levels in only a subpopulation of aMe cells via H2-type histamine receptor chloride channels. Thus, our data suggest that ACh is part of the light entrainment pathway while histamine is involved in a non-photic input pathway to the ventral circadian clock of the Madeira cockroach.     

Multiple FtsZ2 isoforms involved in chloroplast division and biogenesis are developmentally associated with thylakoid membranes in Arabidopsis

Seed plants and algae have two distinct FtsZ protein families, FtsZ1 and FtsZ2, involved in plastid division. Distinctively, seed plants and mosses contain two FtsZ2 family members (FtsZ2-1 and FtsZ2-2) thus raising the question of the role of these FtsZ2 paralogs in plants. We show that both FtsZ2 paralogs, in addition to being present in the stroma, are associated with the thylakoid membranes and that association is developmentally regulated. We also show that several FtsZ2-1 isoforms are present with distinct intra-plastidial localization. Mutant analyses show that FtsZ2-1 is essential for chloroplast division and that FtsZ2-2 plays a specific role in chloroplast morphology and internal organisation in addition to participating in chloroplast partition.     

Chemopreventive activity of selenocysteine prodrugs against tobacco-derived nitrosamine (NNK) induced lung tumors in the A/J mouse

Prodrugs of L-selenocysteine have potential utility in cancer chemoprevention. This study reports the efficacy of three selenazolidine-4(R)-carboxylic acids, (2-unsubstituted, 2-oxo, and 2-methyl derivatives; SCA, OSCA, and MSCA, respectively) against tobacco-related lung tumorigenesis in a mouse model. Seven days after initiation of an AIN-76A diet supplemented with sodium selenite (5 ppm Se), L-selenomethionine (3.75 ppm Se), Se-methyl-L-selenocysteine (3 ppm Se), L-selenocystine (15 ppm Se), SCA (15 ppm Se), OSCA (15 ppm Se), or MSCA (15 ppm Se), mice received 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK; 10 micromol, i.p.). After an additional 16 weeks on the diets, two compounds, OSCA and selenocystine, significantly reduced lung adenoma multiplicity from 7.2 tumors per mouse in the NNK group to 4.5 and 4.6 tumors per mouse, respectively. Neither selenium concentration nor glutathione peroxidase activity in either RBCs or liver served as surrogate indicators of tumor reduction. Hepatic selenium levels were significantly elevated by all selenium-containing compounds except Se-methyl-L-selenocysteine and SCA; RBC selenium levels by all except sodium selenite and MSCA. With the exception of L-selenomethionine, RBC glutathione peroxidase activity was increased along with the elevated selenium levels. Hepatic glutathione peroxidase activity was elevated by all Se-compounds except SCA. The two compounds showing significant tumor reduction (OSCA and selenocystine) were the only two compounds that showed ubiquity of changes, elevating both selenium levels and GPx activity in both liver and RBC.     

Testosterone,gonadotropins and androgen receptor during spermatogenesis of Biomphalaria alexandrina snails (Pulmonata: Basommatophora)

Endocrine regulation of reproductive processes of the snail Biomphalaria alexandrina is poorly recognized. Thus, the aims of the study were: (1) to acquire histological images of the ovotestis; (2) to determine the hemolymph concentrations of testosterone (T) and gonadotropic hormones (luteinizing hormone: LH and follicle stimulating hormone: FSH), (3) to demonstrate androgen receptor (AR) immunolocalization in the ovotestis, and (4) to show LH and FSH protein expression in cerebral ganglia of small (diameter shell: 4–6 mm), medium (7–11 mm) and large (12–16 mm) B. alexandrina snails. These three groups represented different reproductive stages of the snail. The AR immunoexpression was found in the periphery and inside the acini of small (immature) snails as well as in spermatocytes, spermatids, Sertoli cells, the interstitial cells and the acinus lining epithelium of medium (mature) snails. Low AR immunoexpression was demonstrated in the interstitial cells of large (aged) snails. The neurons at the periphery of the cerebral ganglia and connective sheath of the ganglia showed a positive FSH and LH immunostaining. T concentration in the hemolymph was higher in medium snails than in small and large snails. In contrast, LH concentration was higher in medium snails than in small and large snails. These data suggests that gonadotropins and T play a role in the gonadal development in B. alexandrina.     

Production of dextransucrase and dextran by Leuconostoc mesenteroides immobilized in calcium-alginate beads: II. Semicontinuous fed-batch fermentations

Cells of Leuconostoc mesenteroides immobilized in calcium alginate beads were used to produce dextransucrase (DS) in three sequential cycles of semicontinuous fed-batch fermentations. Each cycle consisted of a fed-batch DS production period of 24 h followed by a batch dextran production period for another 24 h. Free, suspended cells were used in only one cycle of fed-batch DS production followed by a dextran production period. It was impractically tedious to separate and reuse free cells. Increasing sucrose feed rate from 5 to 10 g/L h led to increases of the total enzymatic activity by about 88% with immobilized cells and by about 100% with free cells. In DS fed-batch semicontinuous fermentation, total enzymatic activity produced by immobilized cells was 1.35 and 1.56 times greater than that produced by free cells with respective sucrose feeding rates of 10 and 5 g/L h. These increases in enzyme productivity with immobilized cells, however, required total overall operating times three times longer (three cycles) than with free cells (one cycle). Growing the microorganism at optimum conditions for DS production also increased the dextran yield and shortened the time of conversion of sucrose to dextran, regardless of whether the cells were free or immobilized. Moreover, during three cycles of semicontinuous operation (144 h) immobilized cells produced more than three times as much dextran as free cells during one cycle (24 h).     

CD spectrum of bacteriorhodopsin: Best evidence against exciton model

We summarize the predictions of the exciton model that was originally proposed to explain the observed biphasic band shape of its CD spectrum in the visible region of bacteriorhodopsin (bR). It is shown that to reconcile these predictions with the observed results on the linear dichroism, the retinal isomerization time and, the retinal-retinal distance, the biphasic nature of the observed CD spectrum of bR becomes itself an evidence against the exciton model because of the uncertainty principle.

Reduced bR (RbR), which retains its hexagonal structure, shows a monophasic CD spectrum with relatively small rotational strength as compared to bR. This is shown to disagree with predictions made by the exciton model. The results could best be explained in terms of retinal-protein heterogeneity leading to two or more types of bR in which their retinals suffer opposite sense of intramolecular rotational distortion along their retinal long axis. Such a retinal-protein heterogeneity disappears in reduced bR which is known to have a planar (nondistorted) retinal conjugated system, resulting in a monophasic CD with reduced rotational strength, as observed.

     

Use of mycorrhizal fungi and phosphorus fertilization to improve the yield of onion (Allium cepa L.) plant

Improving the economical yield of commonly cultivated crops is one of the most pressing social and scientific issues in modern agriculture. This paper was conducted to investigate the bio-efficacy of arbuscular mycorrhizal fungi (AMF) in improving phosphorous (P) utilization and increasing the yield of onion plant grown in sandy soil under a drip irrigation system. The obtained results showed that AMF inoculation of onion and application of 120 kg P fertilizer ha⁻¹ significantly increased the fresh and dry weights, chlorophyll content of onion as well as P concentration in the root, shoot, and bulb during two growing seasons. Moreover, AMF increased the bioavailability of P in the rhizosphere and significantly enhanced the N-utilization by the inoculated plant. The economic yield of the onion plant inoculated by AMF and fertilized by different doses of P fertilizer was much higher than that obtained by the control (without AMF). These findings indicated that inoculating the onion plant in the field with AMF could be very effective in increasing the yield of the onion plant. Additionally, this study suggests AMF as a low-cost and promising candidate for the sustainable production of the onion crop using reclaimed sandy soils and a drip irrigation system.Keyword: Onion, Mycorrhizal Fungi, Economic yield, P fertilization, N utilization, ¹⁵N     

Synthesis and In Vitro Antitumor Activity of New Substituted Thiopyrimidine Acyclic Nucleosides and Their Thioglycoside Analogs

Some new thiopyrimidine acyclic nucleosides and thioglycoside derivatives 3a-c, 4a-c, 6a,b, and 7a,b were synthesized. The cytotoxicity and antitumor evaluation of all prepared compounds have been tested in vitro against Ehrlich's ascites carcinoma cell line and their activity against glutathione peroxidase and catalase were reported. The role of the prepared compounds as free radical regulators and the therapeutic antitumor effect of a balanced generation of free radicals are discussed. Compounds 2, 3b, 3c, 4a, and 4c inhibited significantly in a dose dependent manner the growth of Ehrlich ascites carcinoma cells while the other compounds did not show any antitumor activity even at higher concentrations.     

Micellar-emphasized simultaneous determination of ivabradine hydrochloride and felodipine using synchronous spectrofluorimetry

A sensitive and green micellar spectrofluorimetric approach was applied for the simultaneous estimation of ivabradine hydrochloride (IVB) and felodipine (FLD) in the ng/ml concentration range. The approach depended on measuring the first derivative synchronous peak amplitude (¹D) of both drugs at ∆λ = 60 nm in a Tween-80 micellar system. The method was rectilinear alongside the concentration ranges 0.02–0.4 μg/ml and 0.05–1.0 μg/ml at 269.5 nm and 378.5 nm for IVB and FLD, respectively. The proposed method was validated by following the International Council for Harmonization guidelines. The method was successfully applied without interference for laboratory-prepared synthetic mixtures, single pharmaceutical preparations, and within spiked biological fluids with acceptable percentage recoveries. A comparison of the performance of the suggested method with other methods, showed no discrepancy. The method’s ecofriendly property evaluated using three different tools, confirming an excellent green method.     

Dipeptidyl alpha-fluorovinyl Michael acceptors: synthesis and activity against cysteine proteases

The synthesis of novel dipeptidyl alpha-fluorovinyl sulfones using a Horner-Wadsworth-Emmons approach on N-Boc-l-phenylalaninal is described. Inhibitory assays against a Leishmania mexicana cysteine protease (CPB2.8DeltaCTE) revealed low biological activity. Relative rates of Michael additions of 2'-(phenethyl)thiol with vinyl sulfone and alpha-fluorovinyl sulfone were determined, and ab initio calculations on several Michael acceptor model structures were performed; both were in agreement with the biological testing results.