Antineoplastic and antibacterial activity of some mononuclear Ru(II) complexes

These ligands (L) show a bidentate behavior, forming octahedral ruthenium complexes. The title complexes were subjected to in-vivo anticancer activity tests against a transplantable murine tumor cell line, Ehrlich's Ascitic Carcinoma (EAC) and in-vitro antibacterial activity against several Gram positive and Gram negative bacterial strains. [Ru(bpy)2(ihqs)]Cl2 and [Ru(bpy)2 (hc)]Cl2 (where bpy = 2,2'-bipyridine, ihqs = 7-iodo-8hydroxy quinoline-5-sulphonic acid and hc = 3-hydroxy coumarin) showed promising antitumor activity. Treatment with these complexes prolonged the life span of EAC bearing mice as well as decreased their tumor volume and viable ascitic cell count. All the tested complexes exhibited mild to moderate antibacterial activity.     

FTIR study of ATP-induced changes in Na+/K+-ATPase from duck supraorbital glands

The Na+/K+-ATPase uses energy from the hydrolysis of ATP to pump Na+ ions out of and K+ ions into the cell. ATP-induced conformational changes in the protein have been examined in the Na+/K+-ATPase isolated from duck supraorbital salt glands using Fourier transform infrared spectroscopy. Both standard transmission and attenuated total internal reflection sample geometries have been employed. Under transmission conditions, enzyme at 75 mg/ml was incubated with dimethoxybenzoin-caged ATP. ATP was released by flashing with a UV laser pulse at 355 nm, which resulted in a large change in the amide I band. The absorbance at 1659 cm(-1) decreased with a concomitant increase in the absorbance at 1620 cm(-1). These changes are consistent with a partial conversion of protein secondary structure from alpha-helix to beta-sheet. The changes were approximately 8% of the total absorbance, much larger than those seen with other P-type ATPases. Using attenuated total internal reflection Fourier transform infrared spectroscopy, the decrease in absorbance at approximately 1650 cm(-1) was titrated with ATP, and the titration midpoint K0.5 was determined under different ionic conditions. In the presence of metal ions (Na+, Na+ and K+, or Mg2+), K0.5 was on the order of a few microM. In the absence of these ions, K0.5 was an order of magnitude lower (0.1 microM), indicating a higher apparent affinity. This effect suggests that the equilibrium for the ATP-induced conformational changes is dependent on the presence of metal ions.     

Decreased hemoglobin concentrations,hyperparasitemia, and severe malaria are associated with increased Plasmodium falciparum gametocyte carriage

To determine factors influencing gametocyte carriage, a cross-sectional study was conducted among 512 patients admitted for Plasmodium falciparum malaria. After adjustments for potential confounders, hemoglobin concentrations were lower in gametocyte carriers 10.5 (+/-2.5) than in patients without gametocytes 12.5 (+/-2.3) (P < 0.0001). Hemoglobin concentrations were negatively correlated with peak gametocyte counts (Spearman's p = -0.37, P < 0.0001) and gametocyte carriage durations (Spearman's p = -(0.30, P < 0.0001). Adjustments for the duration of the malaria episode and other potential confounders did not alter the association (P < 0.0001). After adjustment for potential confounders, the median asexual parasitemia was higher in patients with gametocytes than in patients without gametocytes (P = 0.003). Severe malaria cases were more likely to have gametocytes (65%) than malaria with hyperparasitemia (38%) or mild malaria (31%) (P = 0.0001). These findings suggest that events surrounding anemia and tissue hypoxia stimulate Plasmodium falciparum gametocytogenesis.     

Two acyl sucroses from Petunia nyctaginiflora

Two new acyl sucroses were isolated from the epigeal parts of Petunia nyctaginiflora Juss. (Solanaceae). Their structures were determined to be 2, 3, 4-tri (5-methylhexanoyl)-alpha-D-glucopyranosyl-beta-D-fructofuranoside (2) and 2, 3, 4-tri (6-methylheptanoyl)-alpha-D-glucopyranosyl-beta-D-fructofuranoside (4) on the basis of chemical and spectroscopic evidence.     

Characteristics of glycosylated streptokinase secreted from Pichia pastoris: enhanced resistance of SK to proteolysis by glycosylation

Degradation of streptokinase (SK) has been frequently observed during large-scale protein production. An enhanced susceptibility of SK to degradation has been correlated with its existence in a partially unfolded state. The influence of the carbohydrate moiety on the stability and functional characteristics of SK has been examined by obtaining the glycoform of SK following its secretion through the methylotrophic yeast Pichia pastoris. Secretion of the protein product was achieved by replacing the native secretion signal codons of SK with those from α-factor leader peptide and expressing the fusion construct under the control of the methanol-inducible alcohol oxidase (ox) promoter of P. pastoris after its integration into the host chromosome. Western blot and zymographic analysis of proteins secreted from the recombinant P. pastoris indicated that SK was glycosylated by the host cells, which resulted in the appearance of a SK species migrating slowly, corresponding to a 55-kDa protein product as compared to the 47-kDa native SK. The glycosylated SK retained a plasminogen activation capability identical to that of its unglycosylated counterpart. Glycoform SK exhibited an enhanced stability profile at 25 °C and 37 °C and improved resistance towards protease treatment compared to unglycosylated SK secreted through P. pastoris after tunicamycin treatment or that secreted from the recombinant Escherichia coli. The results presented thus illustrate that N-linked glycosylation of SK results in 30–40% enhancement of the protein stability and resistance towards degradation but does not interfere with its fibrinolytic function. Received: 1 March 1999 / Received last revision: 5 October 1999 / Accepted: 10 October 1999     

The Use of Maleic Hydrazide for Effective Hybridization of Setaria viridis

An efficient method for crossing green foxtail (Setaria viridis) is currently lacking. S. viridis is considered to be the new model plant for the study of C4 system in monocots and so an effective crossing protocol is urgently needed. S. viridis is a small grass with C4-NADP (ME) type of photosynthesis and has the advantage of having small genome of about 515 Mb, small plant stature, short life cycle, multiple tillers, and profuse seed set, and hence is an ideal model species for research. The objectives of this project were to develop efficient methods of emasculation and pollination, and to speed up generation advancement. We assessed the response of S. viridis flowers to hot water treatment (48°C) and to different concentrations of gibberellic acid, abscisic acid, maleic hydrazide (MH), and kinetin. We found that 500 μM of MH was effective in the emasculation of S. viridis, whilst still retaining the receptivity of the stigma to pollination. We also report effective ways to accelerate the breeding cycle of S. viridis for research through the germination of mature as well as immature seeds in optimized culture media. We believe these findings will be of great interest to researchers using Setaria.     

Effect of temperature and arsenic on Aeromonas hydrophila growth,a modelling approach

Aeromonas hydrophila is frequently reported from arsenic affected areas. Present study was aimed to determine the effect of arsenic and temperature on growth of A. hydrophila. The bacteria were isolated from naturally infected fish from a water body in Birbhum, West-Bengal, India, which is reported to be an arsenic-free area. Arsenic concentration in natural aquatic reservoirs (e.g., pond, lake or river) varies from 0–6 mg/L. No significant change in bacterial growth was observed within this range of arsenic exposure. However, variation in temperature impacted the growth of A. hydrophila. A single dimension model was constructed using simple logistic equation. Rate parameters of the model were derived from the experimental observations. Comparison of model results and laboratory observations gives a good conformity regarding the effect of variation of arsenic concentration and temperature change on growth of this bacterium. From the analysis of this model we further get the idea that the maximum growth of A. hydrophila is supposed to be at 31.4°C in absence of arsenic, whereas at 477 mg/L arsenic concentration, the growth of the bacteria totally stops at 30°C.     

Cryptochromes: Photochemical and structural insight into magnetoreception

Cryptochromes (CRYs) function as blue light photoreceptors in diverse physiological processes in nearly all kingdoms of life. Over the past several decades, they have emerged as the most likely candidates for light‐dependent magnetoreception in animals, however, a long history of conflicts between in vitro photochemistry and in vivo behavioral data complicate validation of CRYs as a magnetosensor. In this review, we highlight the origins of conflicts regarding CRY photochemistry and signal transduction, and identify recent data that provides clarity on potential mechanisms of signal transduction in magnetoreception. The review primarily focuses on examining differences in photochemistry and signal transduction in plant and animal CRYs, and identifies potential modes of convergent evolution within these independent lineages that may identify conserved signaling pathways.