Application of a Mass Spectrometric Approach to Detect the Presence of Fatty Acid Biosynthetic Phosphopeptides

The details of plant lipid metabolism are relatively well known but the regulation of fatty acid production at the protein level is still not understood. Hence this study explores the importance of phosphorylation as a mechanism to control the activity of fatty acid biosynthetic enzymes using low and high oleic acid mesocarps of oil palm fruit (Elaeis guineensis variety of Tenera). Adaptation of neutral loss-triggered tandem mass spectrometry and selected reaction monitoring to detect the neutral loss of phosphoric acid successfully found several phosphoamino acid-containing peptides. These peptides corresponded to the peptides from acetyl-CoA carboxylase and 3-enoyl-acyl carrier protein reductase as identified by their precursor ion masses. These findings suggest that these enzymes were phosphorylated at 20th week after anthesis. Phosphorylation could have reduce their activities towards the end of fatty acid biosynthesis at ripening stage. Implication of phosphorylation in the regulation of fatty acid biosynthesis at protein level has never been reported.     

Complement activation via alternative pathway is critical in the development of laser-induced choroidal neovascularization: role of factor B and factor H

The objective of this study was to explore the role of classical, lectin, and alternative pathways of complement activation in laser-induced choroidal neovascularization (CNV). The classical and alternative pathways were blocked in C57BL/6 mice by small interfering RNAs (siRNA) directed against C1q and factor B, respectively. C4(-/-) mice developed CNV similar to their wild-type controls and inhibition of C1q by siRNA had no effect on the development of CNV. In contrast, CNV was significantly inhibited (p < 0.001) in C5(-/-) mice and C57BL/6 mice treated with factor B siRNA. Inhibition of the alternative pathway by factor B siRNA resulted in decreased levels of membrane attack complex and angiogenic factors-vascular endothelial growth factor and TGF-beta2. Furthermore, factor B was up-regulated in complement sufficient C57BL/6 mice at day 1 postlaser and remained elevated at day 7. Significantly reduced levels of factor H were observed at day 3 in these animals. In conclusion, our results demonstrate that activation of the factor B-dependent alternative pathway, but not the classical or lectin pathways, was essential for the development of CNV in mouse model of laser-induced CNV. Thus, specific blockade of the alternative pathway may represent a therapeutically relevant strategy for the inhibition of CNV.     

Ethylbutyrate,a valproate-like compound,exhibits inositol-depleting effects — A potential mood-stabilizing drug

AimsTo screen for inositol-depleting valproate-like compounds as potential mood stabilizing drugs.Main methodsWe exploited the yeast Saccharomyces cerevisiae, as a model in which inositol de novo synthesis has been extensively characterized, to test the effects of ethyl butyrate (EB), 2-ethyl-butyric acid, sodium butyrate, and n-propyl hexanoate on inositol biosynthesis. Cell growth was followed by measuring the optical density of the cultures (spectrophotometrically), RNA abundance was determined by Northern blot analysis, intracellular inositol was measured by a fluorometric assay, and 1-d-myo-inositol-3-phosphate synthase activity was examined using a chromatographic method.Key findingsOf the tested compounds, only EB exhibited an inositol-depleting effect. The inositol-depleting effect of EB was achieved without significant adverse effect on cell growth, pointing to lesser toxicity compared to valproate.SignificanceThese results indicate that EB is a potential candidate for mood-stabilizing therapy.     

Effects of body configuration on pelvic injury in backward fall simulation using 3D finite element models of pelvis–femur–soft tissue complex

Injuries due to backward fall apart from sideways fall are a major health problem, particularly among the aged populations. The objectives of this study was to evaluate the responses to changing body configurations (angle between the trunk and impacting floor as 0°, 15°, 45° and 80°) during backward fall, based on a previously developed CT-scan-derived 3D non-linear and non-homogeneous finite element (FE) model of pelvis–femur–soft tissue complex with simplified biomechanical representation of the whole body. Under constant impact energy, these FE models evaluated the pelvic injury situations on the basis of peak impact force (7.64–16.74 kN) and peak principal compressive strain (more than 1.5%), consistent with the clinically observed injuries (sacral insufficiency, coccydynia). Also the change in location of peak strain and increase in peak impact force for changing configurations from 0° to 80° indicated the effect of whole body inertia during backward fall. It was also concluded that the inclusion of sacro-iliac and acetabular cartilages in the above FE models will further reduce above findings marginally (9.2% for 15° fall). These quantifications would also be helpful for a better design and development of safety structures such as safety floor for the nursing home or home for the aged persons.     

Synthesis, crystal structure and magnetic characterization of a series of four phenoxo-bridged binuclear manganese(III) Schiff base complexes

A family of four new phenoxo-bridged binuclear manganese(III) complexes of the general formula, [Mn(L)(X)]₂ where L = [N,N′-bis(salicylidene)]propane-1,2-diamine and X = salicylaldehyde anion (sal⁻) (1); NCS⁻ (2); NCO⁻ (3) and [Mn(L′)(N₃)]₂·2C₂H₅OH (4) where L′ = [N,N′-bis(2-hydroxyacetophenylidene)]propane-1,2-diamine has been prepared. The syntheses have been achieved by reacting manganese perchlorate with 1,2-diaminopropane and salicylaldehyde (or 2-hydroxyacetophenone for 4) or along with the respective pseudohalides so that the tetradentate Schiff base H₂L or H₂L′ is obtained in situ to bind the Mn(III) ion. The complexes have been characterized by IR spectroscopy, elemental analysis, crystal structure analysis and variable-temperature magnetic susceptibility measurements. The single crystal X-ray diffraction studies show that the compounds are isostructural containing dimeric Mn(III) units with bridging phenolate oxygen atoms. Low temperature magnetic studies indicate that the complexes 1-3 exhibit intradimer ferromagnetic exchange as well as single-molecule magnet (SMM) behavior while complex 4 is found to undergo an intradimer antiferromagnetic coupling.     

Excited state intramolecular proton transfer in 3-hydroxy flavone and 5-hydroxy flavone: A DFT based comparative study

Potential energy (PE) curves for the intramolecular proton transfer in the ground (GSIPT) and excited (ESIPT) states of 3-hydroxy-flavone (3HF) and 5-hydroxy-flavone (5HF) were studied using DFT/B3LYP (6-31G (d,p)) and TD-DFT/B3LYP (6-31G (d,p)) level of theory respectively. Our calculations suggest the non-viability of ground state intramolecular proton transfer for both the compounds. Calculated PE curves of 3HF for the ground and excited singlet states proton transfer process explain its four state laser diagram. Excited states PE calculations support the ESIPT process to both 5HF and 3HF. The difference in ESIPT emission process of 3HF and 5HF have been explained in terms of HOMO and LUMO electron distribution of the enol and keto tautomer of these two compounds.     

Centromere identity: a challenge to be faced

The centromere is a genetic locus, required for faithful chromosome segregation, where spindle fibers attach to the chromosome through kinetochore. Loss of centromere or formation of multiple centromeres on a single chromosome leads to chromosome missegregation or chromosome breakage, respectively, which are detrimental for fitness and survival of a cell. Therefore, understanding the mechanism of centromere locus determination on the chromosome and perpetuation of such a locus in subsequent generation (known as centromere identity) is very fundamental to combat conditions like aneuploidy, spontaneous abortion, developmental defects, cell lethality and cancer. Recent studies have come up with different models to explain centromere identity. However, the exact mechanism still remains elusive. It has been observed that most eukaryotic centromeres are determined epigenetically rather than by a DNA sequence. The epigenetic marks that are instrumental in determining centromere identity are the histone H3 variant, CENP-A and the specialized posttranslational modification of the core histones. Here we will review the recent studies on the factors responsible for generating unique centromeric chromatin and how it perpetuates during cell division giving the present-day models. We will further focus on the probable mechanism of de novo centromere formation with an example of neocentromere. As a matter of similitude, this review will include marking extrachromosomal chromatin to be served as a partitioning locus by deposition of CENP-A homolog in budding yeast.