A novel esterase from Bacillus subtilis (RRL 1789): purification and characterization of the enzyme

An esterase (EC 3.1.1.1) produced by an isolated strain of Bacillus subtilis RRL 1789 exhibited moderate to high enantioselectivity in the kinetic resolution of several substrates like aryl carbinols, hydroxy esters, and halo esters. The enzyme named as B. subtilis esterase (BSE), was purified to >95% purity with a specific activity of 944 U/mg protein and 12% overall yield. The purified enzyme is approximately 52 kDa monomer, maximally activity at 37 degrees C and pH 8.0 and fairly stable up to 55 degrees C. The enzyme does not exhibit the phenomenon of interfacial activation with tributyrin and p-nitrophenyl butyrate beyond the saturation concentration. The enzyme showed preference for triacyglycerols and esters of p-nitrophenol with short chain fatty acid. Presence of Ca2+ ions increases the activity of enzyme by approximately 20% but its presence does not have any influence on the thermostability of the enzyme. The enzyme is not a metalloprotein and belongs to the family of serine proteases. The N-terminal amino acid sequence of BSE determined, as Met-Thr-Pro-Glu-Iso-Val-Thr-Thr-Glu-Tyr-Gly- revealed similarity with the N-terminal amino acid sequence of p-nitrobenzylesterase of B. subtilis.     

Sequence-specific 1H, 13C and 15N NMR assignments of Cyclophilin A like protein from Piriformospora indica involved in salt stress tolerance

Cyclophilins are omnipresent proteins found in eukaryotes and prokaryotes, with presence in cytoplasm as well as in nucleus. Primary role of Cyclophilins is of peptidyl-prolyl cis–trans isomerase, a molecular chaperon action. Here, we report sequence-specific ¹H, ¹³C and ¹⁵N resonance assignments for a Cyclophilin A like protein from Piriformospora indica. This protein is up-regulated during salt stress conditions.     

Combat of iron-deprivation through a plant growth promoting fluorescent Pseudomonas strain GRP3A in mung bean (Vigna radiata L. Wilzeck)

Microorganisms and plants sustain themselves under iron-deprived conditions by releasing siderophores. Among others, fluorescent pseudomonads are known to exert extensive biocontrol action against soil and root borne phytopathogens through release of antimicrobials and siderophores. In this study, production and regulation of siderophores by fluorescent Pseudomonas strain GRP3A was studied. Among various media tested, standard succinate medium (SSM) promoted maximum siderophore production of 56.59 mg l(-1). There were low levels of siderophore in complex media like King's B medium, trypticase soya medium and nutrient medium (41.27, 29.86 and 27.63 mg l(-1)), respectively. In defferrated SSM, siderophore level was quantified to be 68.74 mg l(-1). Supplementation with iron (FeCl3) resulted in decreased siderophore levels depending on concentration. Siderophore production was promoted by Zn2+ (78.94 mg l(-1)), Cu2+ (68.80 mg l(-1)) whereas Co2+ (57.33 mg l(-1)) and Fe3+ reduced siderophore production (37.44 mg l(-1) as compared to control (55.97 mg l(-1)). Strain GRP3A showed plant growth promotion under iron limited conditions.     

The influence of water level on macrophyte growth and trophic interactions in eutrophic Mediterranean shallow lakes: a mesocosm experiment with and without fish

1. Water‐level fluctuations are typical of lakes located in the semi‐arid Mediterranean region, which is characterised by warm rainy winters and hot dry summers. Ongoing climate change may exacerbate fluctuations and lead to more severe episodes of drought, so information on the effects of water level on the functioning of lake ecosystems in such regions is crucial. 2. In eutrophic Lake Eymir, Turkey, we conducted a 4‐month (summer) field experiment using cylindrical 0.8‐m‐ (low‐water‐level) and 1.6‐m‐deep (high‐water‐level) mesocosms (kept open to the sediment and atmosphere). Fish (tench, Tinca tinca, and bleak, Alburnus escherichii) were added to half of the mesocosms, while the rest were kept fishless. Ten shoots of Potamogeton pectinatus were transplanted to each mesocosm. 3. Sampling for physicochemical variables, chlorophyll a (chl‐a), zooplankton and per cent plant volume inhabited (PVI%) by macrophytes was conducted weekly during the first 5 weeks, and subsequently biweekly. Macrophytes were harvested on the last sampling date. During the course of the experiment, the water level decreased by 0.41 ± 0.06 m. 4. Throughout the experiment, fish affected zooplankton abundance (?), nutrient concentrations (+), chl‐a (+) and water clarity (?) most strongly in the low‐water‐level mesocosms and the zooplankton community shifted towards dominance of small‐sized forms. The fishless mesocosms had a higher zooplankton/phytoplankton ratio, suggesting higher grazing. 5. Greatest macrophyte growth was observed in the low‐water‐level fishless mesocosms. However, despite high nutrient concentrations and low water clarity, macrophytes were also abundant in the fish mesocosms and particularly increased following a water‐level decrease from midsummer onwards. Macrophyte growth was poor in the high‐water‐level mesocosms, even in the fishless ones with high water clarity. This was ascribed to extensive periphyton development reducing light availability for the macrophytes. 6. Our results indicate that a reduction in water level during summer may help maintain the growth of macrophytes in Mediterranean eutrophic shallow lakes, despite a strong negative effect of fish predation on water clarity. It is therefore probable that an expected negative effect of global climate change on water clarity because of eutrophication and enhanced top‐down control of fish may be, at least partly, counteracted by reduced water level, provided that physical disturbance is not severe.     

The root endophyte fungus Piriformospora indica leads to early flowering,higher biomass and altered secondary metabolites of the medicinal plant,Coleus forskohlii

This study was undertaken to investigate the influence of plant probiotic fungus Piriformospora indica on the medicinal plant C. forskohlii. Interaction of the C. forskohlii with the root endophyte P. indica under field conditions, results in an overall increase in aerial biomass, chlorophyll contents and phosphorus acquisition. The fungus also promoted inflorescence development, consequently the amount of p-cymene in the inflorescence increased. Growth of the root thickness was reduced in P. indica treated plants as they became fibrous, but developed more lateral roots. Because of the smaller root biomass, the content of forskolin was decreased. The symbiotic interaction of C. forskohlii with P. indica under field conditions promoted biomass production of the aerial parts of the plant including flower development. The plant aerial parts are important source of metabolites for medicinal application. Therefore we suggest that the use of the root endophyte fungus P. indica in sustainable agriculture will enhance the medicinally important chemical production.     

Muscling in on PGC-1α for improved quality of life in ALS

Impaired activity of peroxisome proliferator-activated receptor (PPAR)-γ coactivator (PGC)-1α has been implicated in the pathophysiology of several neurodegenerative disorders. In this issue, Da Cruz et al. (2012) show improved muscle function, but not survival, with increased PGC-1α activity in muscle in a mouse model of amyotrophic lateral sclerosis.     

Nifedipine loaded chitosan microspheres prepared by emulsification phase-separation

A high yield of nifedipine-chitosan microspheres could be obtained using an emulsification phase-separation method. A high level of entrapment of nifedipine in the microspheres was achieved. The microspheres exhibited excellent swelling properties. Differential scanning calorimetry, X-ray diffractometry, and scanning electron microscopy confirmed that at 1.84% loading, nifedipine was dispersed molecularly. The microspheres exhibited faster release at low loadings compared to high loadings. Fitting the data to the coupled Fickian/case II equation, showed that at low loadings polymer relaxation coefficients (k₂) were high. As the polymer content increased in the microspheres, the value of n (diffusional exponent characteristic of the release mechanism) approached one, which is indicative of zero order.     

Real time in vitro studies of doxorubicin release from PHEMA nanoparticles

Background  

Many anticancer agents have poor water solubility and therefore the development of novel delivery systems for such molecules has received significant attention. Nanocarriers show great potential in delivering therapeutic agents into the targeted organs or cells and have recently emerged as a promising approach to cancer treatments. The aim of this study was to prepare and use poly-2-hydroxyethyl methacrylate (PHEMA) nanoparticles for the controlled release of the anticancer drug doxorubicin.