An Anti-microbial Peptide Derivative of Flesh Fruit Fly Mimics Secretory Signal Sequence and Inhibits Signal Peptidase-I in the Export Pathway

Combinatorial search of the antimicrobial peptide R⁷SLCLLHCRLK from flesh fruit fly yielded a substantially more active peptide of the sequence KLKL₅KLK-NH₂ that had signal sequence character as revealed by Neural-network survey. Bioinformatics survey of KLKL_nKLK revealed a sigmoidal relationship between SSP and the intervening Leu stretch. Synthetic enantiomeric KLKL_nKLK peptides inhibited Escherichia coli signal peptidase-I, in vitro, in correlation with their SSPs; KLKL₆₍₇₎KLK exterted maximum inhibition. Both (l)-and (d)-forms were bactericidal to Gram-positive and Gram-negative bacteria. However, the protease-resistant (d)-KLKL₆KLK-NH₂ proved more potent than (d)-KLKL₆KLK-NH₂ at inhibiting the bacterial protein secretion prior to inducing bacterial lysis. Kinetic analyses of the interaction of these peptides with the signal peptidase-I revealed competitive inhibition with K_i of 10 μM and 35 μM for the (d)- and (l)-forms, respectively. The left and right-handed helicity of the respective peptides assessed by CD concurs with their probable interaction at the active site of signal peptidase-I. Tasawar Khan is deceased.     

Inhibition of myoblast differentiation by Sfrp1 and Sfrp2

Secreted Frizzled-related proteins (Sfrps) are extracellular regulators of Wnt signalling and play important roles in developmental and oncogenic processes. They are known to be upregulated in regenerating muscle and in myoblast cultures but their function is unknown. Here, we show that the addition of recombinant Sfrp1 or Sfrp2 to C2C12 cell line cultures or to primary cultures of satellite cells results in the inhibition of myotube formation with no significant effect on the cell cycle or apoptosis. Even though at confluence, treated and untreated cultures are identical in appearance, analyses have shown that, for maximum effect, the cells have to be treated while they are proliferating. Furthermore, removal of Sfrp from the culture medium during differentiation restores normal myotube formation. We conclude that Sfrp1 and Sfrp2 act to prevent myoblasts from entering the terminal differentiation process. S. Descamps and J. Levin contributed equally to this work.     

Complexes of vitamin B6, part VII: Ternary complexes of cobalt(II), nickel(II), and copper(II) involving pyridoxamine and some amino acids

The stability constants of the ternary Cu(II), Ni(II), and Co(II) complexes containing pyridoxamine (PM) and as a second ligand (L) glycine, DL-alanine, DL-valine, and β-phenylalnine were determined by pH-metric titration in 0.50 M KNO₃ at 30°C. The corresponding constants of the equilibrium, log X, are greater than would be expected for purely statistical reasons (log X = 0.6), except for few complex cases of Co(II). It has been also concluded that amino acids compete more than pyridoxamine for Ni(II) and Co(II) through the formation of 1:2:1:0 species rather than 2:1:1:0 of PM⁻:L⁻:M²⁺:H⁺.     

5-Aminolevulinic Acid Ameliorates the Growth, Photosynthetic Gas Exchange Capacity, and Ultrastructural Changes Under Cadmium Stress in Brassica napus L.

Heavy-metal toxicity in soil is one of the major constraints for oilseed rape (Brassica napus L.) production. One of the best ways to overcome this constraint is the use of growth regulators to induce plant tolerance. Response to cadmium (Cd) toxicity in combination with a growth regulator, 5-aminolevulinic acid (ALA), was investigated in oilseed rape grown hydroponically in greenhouse conditions under three levels of Cd (0, 100, and 500 μM) and three levels of foliar application of ALA (0, 12.5, and 25 mg l^?1). Cd decreased plant growth and the chlorophyll concentration in leaves. Foliar application of ALA improved plant growth and increased the chlorophyll concentration in the leaves of Cd-stressed plants. Significant reductions in photosynthetic parameters were observed by the addition of Cd alone. Application of ALA improved the net photosynthetic and gas exchange capacity of plants under Cd stress. ALA also reduced the Cd content in shoots and roots, which was elevated by high concentrations of Cd. The microscopic studies of leaf mesophyll cells under different Cd and ALA concentrations showed that foliar application of ALA significantly ameliorated the Cd effect and improved the structure of leaf mesophyll cells. However, the higher Cd concentration (500 μM) could totally damage leaf structure, and at this level the nucleus and intercellular spaces were not established as well; the cell membrane and cell wall were fused to each other. Chloroplasts were totally damaged and contained starch grains. However, foliar application of ALA improved cell structure under Cd stress and the visible cell structure had a nucleus, cell wall, and cell membrane. These results suggest that under 15-day Cd-induced stress, application of ALA helped improve plant growth, chlorophyll content, photosynthetic gas exchange capacity, and ultrastructural changes in leaf mesophyll cells of the rape plant.     

New antiprotozoal agents: Synthesis and biological evaluation of different 4-(7-chloroquinolin-4-yl) piperazin-1-yl)pyrrolidin-2-yl)methanone derivatives

In an endeavor to develop efficacious antiprotozoal agents 4-(7-chloroquinolin-4-yl) piperazin-1-yl)pyrrolidin-2-yl)methanone derivatives (5–14) were synthesized, characterized and biologically evaluated for antiprotozoal activity. The compounds were screened in vitro against the HM1: IMSS strain of Entamoeba histolytica and NF54 chloroquine-sensitive strain of Plasmodium falciparum. Among the synthesized compounds six exhibited promising antiamoebic activity with IC₅₀ values (0.14–1.26 μM) lower than the standard drug metronidazole (IC₅₀ 1.80 μM). All nine compounds exhibited antimalarial activity (IC₅₀ range: 1.42–19.62 μM), while maintaining a favorable safety profile to host red blood cells. All the compounds were less effective as an antimalarial and more toxic (IC₅₀ range: 14.67–81.24 μM) than quinine (IC₅₀: 275.6 ± 16.46 μM) against the human kidney epithelial cells. None of the compounds exhibited any inhibitory effect on the viability of Anopheles arabiensis mosquito larvae.     

Effects of vitamin C on liver enzymes and biochemical parameters in rats anesthetized with halothane

Halothane is an important human and veterinary anesthetic, which produces free radicals during biotransformation. Occasionally, these free radicals may cause hepatic injury, especially in case of multiple halothane exposures over short periods. Vitamin C may protect cellular lipids and lipoproteins against oxidative damage by the free radicals. This study investigated the effects of vitamin C on liver enzymes and other biochemical parameters in rats anesthetized with halothane. One group of rats was used as a control, and saline (0.9% NaCl) was injected intraperitoneally into these animals as a placebo. The second group of rats was used as an anesthesia control group and was only anesthetized by halothane for 2 h. The third group was anesthetized by halothane and injected vitamin C intraperitoneally. Activities of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase enzymes were significantly increased (p < 0.05, p < 0.01, p < 0.05, respectively) by halothane anesthesia, but decreased (p < 0.05, p < 0.05, p < 0.05, respectively) with administration of vitamin C. Concentrations of triglycerides, cholesterol, total bilirubin and creatinine were statistically affected (p < 0.05, p < 0.01, p < 0.05, and p < 0.01, respectively) by injection of vitamin C. Values of erythrocyte counts, packet cell volumes, hemoglobin concentration, leukocyte counts, rates of neutrophils and lymphocytes were significantly affected (p < 0.01, p < 0.05, p < 0.05, p < 0.01, p < 0.001 and p < 0.01, respectively) by halothane anesthesia. The values of erythrocyte counts, leukocyte counts, neutrophil and lymphocyte rates were significantly decreased (p < 0.05, p < 0.05, p < 0.05, p < 0.01 and p < 0.01, respectively) with administration of vitamin C. Based upon these results, vitamin C may play an important role in the prevention of hepatic cellular injury inflicted by halothane anesthesia.     

Photosynthetic Rate, Growth, and Yield of Mustard Plants Sprayed with 28-Homobrassinolide

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10⁻¹⁰, 10⁻⁸, or 10⁻⁶ M aqueous solution of 28-homobrassinolide (HBR). The HBR-treated plants were healthier than those treated with water and yielded more. Maximum increase over control was found in 60-d-old, 10⁻⁸ M-HBR-treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C. 4.2.1.1) activity, and net photosynthetic rate (P _N), at harvest in number of pods per plant and seed yield per plant (the respective values were 25, 30, 34, 69, 24, and 29 %). A further increase in the concentration of HBR (10⁻⁶ M) did not make any additional impact on the growth and yield. Increased CA activity and P _N were correlated with growth and seed yield. This revised version was published online in August 2006 with corrections to the Cover Date.     

Host stage preference and parasitism behaviour of Aenasius bambawalei an encyrtid parasitoid of Phenacoccus solenopsis

In Pakistan, the cotton mealybug, Phenacoccus solenopsis Tinsley (Sternorrhyncha (Homoptera): Pseudococcidae), is a serious pest of many cultivated plants. A parasitoid, Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae), is associated with P. solenopsis. In order to mass rear A. bambawalei for a biological control programme, it is important to investigate the parasitoid’s host stage preference and its parasitism behaviour for P. solenopsis in order to optimise production. The present study showed that under both choice and no-choice conditions, the parasitoid preferred third instar and pre-reproductive host stage mealybugs for parasitism. Parasitoid larva developing inside the host exhibited a greater longevity, shorter developmental period and longer body size in these preferred host stages. Our study also confirmed that A. bambawalei showed no attraction to male mealybugs and no host feeding on any host stage was recorded. The ability of the parasitoid to effectively discriminate between suitable and non-suitable stages means that it is feasible to rear it on a mixed population.     

On Computations for Thermal Radiation in MHD Channel Flow with Heat and Mass Transfer

This study examines the simultaneous effects of heat and mass transfer on the three-dimensional boundary layer flow of viscous fluid between two infinite parallel plates. Magnetohydrodynamic (MHD) and thermal radiation effects are present. The governing problems are first modeled and then solved by homotopy analysis method (HAM). Influence of several embedded parameters on the velocity, concentration and temperature fields are described.     

EGFR-Targeted Granzyme B Expressed in NK Cells Enhances Natural Cytotoxicity and Mediates Specific Killing of Tumor Cells

Natural killer (NK) cells are highly specialized effectors of the innate immune system that hold promise for adoptive cancer immunotherapy. Their cell killing activity is primarily mediated by the pro-apoptotic serine protease granzyme B (GrB), which enters targets cells with the help of the pore-forming protein perforin. We investigated expression of a chimeric GrB fusion protein in NK cells as a means to augment their antitumoral activity. For selective targeting to tumor cells, we fused the epidermal growth factor receptor (EGFR) peptide ligand transforming growth factor α (TGFα) to human pre-pro-GrB. Established human NKL natural killer cells transduced with a lentiviral vector expressed this GrB-TGFα (GrB-T) molecule in amounts comparable to endogenous wildtype GrB. Activation of the genetically modified NK cells by cognate target cells resulted in the release of GrB-T together with endogenous granzymes and perforin, which augmented the effector cells'' natural cytotoxicity against NK-sensitive tumor cells. Likewise, GrB-T was released into the extracellular space upon induction of degranulation with PMA and ionomycin. Secreted GrB-T fusion protein displayed specific binding to EGFR-overexpressing tumor cells, enzymatic activity, and selective target cell killing in the presence of an endosomolytic activity. Our data demonstrate that ectopic expression of a targeted GrB fusion protein in NK cells is feasible and can enhance antitumoral activity of the effector cells.