Syntheses, structures and magnetic properties of μ1,5-dicyanamide bridged di- and polynuclear manganese(II) complexes containing neutral N-donor Schiff bases: Control of coordination number and nuclearity by varying denticity

Two hexacoordinated dinuclear compounds [Mn(L1)(dca)]₂(ClO₄/PF₆)₂·CH₃OH (1/2) and two heptacoordinated coordination polymers [Mn(L2)(dca)]_n(ClO₄/PF₆)_n (3/4) [L1 = N,N′-(bis-(pyridin-2-yl)benzylidene)-1,3-propanediamine; L2 = N,N′-(bis-(pyridin-2-yl)benzylidene)diethylenetriamine; dca = dicyanamide] are synthesized and characterized. Structures of 1-3 have been solved by X-ray diffraction measurements. Each manganese(II) center in 1/2 is located in a distorted octahedral environment with an MnN₆ chromophore coordinated by the four N atoms of L1 and two nitrile N atoms of bibridged μ_1,5 dca. Interestingly, the coordination polymer 3 forms a 1D chain through single Mn-(NCNCN)-Mn units in which each manganese(II) center adopts a pentagonal bipyramidal geometry with an MnN₇ chromophore occupied with five N atoms of L2 and two nitrile N atoms of monobridged μ_1,5 dca. Magnetic susceptibility measurements of 1-3 in the 2-300 K temperature range reveal weak antiferromagnetic interactions.     

Determination of nutrient requirements for growth and maintenance of growing pigs under tropical condition

Data from 27 feeding trials conducted on growing pigs from different research institutes across India were subjected to mixed model regression analysis to derive requirements of digestible energy (DE), crude protein (CP) and essential amino acids for maintenance and body weight gains. The ranges of maintenance requirements were determined to be: DE 516 to 702 kJ/kg M^0.75, CP 6.98 to 11.62, lysine 0.431 to 0.664, methionine 0.265 to 0.458, methionine + cystine 0.327 to 0.466, cystine 0.055 to 0.184, threonine 0.205 to 0.511, arginine 0.377 to 1.21, isoleucine 0.241 to 0.775, leucine 0.604 to 1.54, phenylalanine + tyrosine 0.496 to 1.33, tryptophan 0.078 to 0.213, and valine 0.330 to 0.892 g/kg M^0.75, respectively for different body weight ranges. The corresponding requirements for 1 g gain in body weight were: DE 28.6 to 38.6 kJ, CP 0.27 to 0.44 g, lysine 0.0071 to 0.0126 g, methionine 0.0047 to 0.0133 g, methionine + cystine 0.0151 to 0.0261 g, cystine 0.0043 to 0.0094 g, threonine 0.0052 to 0.0165 g, arginine 0.0045 to 0.0301 g, isoleucine 0.0023 to 0.0198 g, leucine 0.0150 to 0.0447 g, phenylalanine + tyrosine 0.0091 to 0.0382 g, tryptophan 0.0005 to 0.0044 g, and valine 0.0061 to 0.0222 g. Regression equations had high R² values (ranging from 0.50 to 0.99 for different estimates), low coefficients of variation, low variance of error estimates and the coefficients were highly significant (P < 0.001). Regressed values were used to develop feeding standards. As the new standards derived in the present study are based on a thorough analysis of a larger database than previous Indian standards, the new feeding standard seems to be more appropriate for India and other tropical countries.     

Ultrastructure and lipid chemistry of specialized epidermal structure of Indian porcupines and hedgehog

Poddar‐Sarkar, M., Raha, P., Bhar, R., Chakraborty, A. and Brahmachary, R.L. 2011. Ultrastructure and lipid chemistry of specialized epidermal structure of Indian porcupines and hedgehog. —Acta Zoologica (Stockholm) 92 : 134–140. In the present study, we investigated the ultrastructural variations of specialized epidermal structure of Indian porcupines (Hystrix indica and Atherurus macrourus) and hedgehog (Hemiechinus collaris) as well as the variation in the fatty acid composition of total lipid fraction. Scanning electron microscope images reveal the usual scaly structure in surface view and network of channels in cross‐section but with different orientation of partition walls. The lipid profile reveals the presence of free sterol, long‐chain alcohol, free fatty acids, wax ester and sterol ester in all the three cases and trace amount of triglyceride, diglyceride and monoglyceride. Gas chromatography–mass spectrometry analysis of fatty acid methyl ester of total lipid fraction indicates the presence of C₈‐C₂₂ fatty acids in Hystrix indica, C₈‐C₁₈ in Atherurus macrourus and C₈‐C₂₀ fatty acids in Hemiechinus collaris. It is interesting to note that the total lipid fraction of hedgehog shows no branched‐chain, unsaturated and odd‐carbon fatty acids. Odd‐carbon fatty acid and branched‐chain fatty acids detected in the adult H. indica but were absent in juvenile H. indica as well as in A. macrourus. With the exception of C_18:1, the other unsaturated fatty acids were also absent in both juvenile H. indica and A. macrourus.     

Syndapin Promotes Formation of a Postsynaptic Membrane System in Drosophila

Syndapins belong to the F-BAR domain protein family whose predicted functions in membrane tubulation remain poorly studied in vivo. At Drosophila neuromuscular junctions, syndapin is associated predominantly with a tubulolamellar postsynaptic membrane system known as the subsynaptic reticulum (SSR). We show that syndapin overexpression greatly expands this postsynaptic membrane system. Syndapin can expand the SSR in the absence of dPAK and Dlg, two known regulators of SSR development. Syndapin's N-terminal F-BAR domain, required for membrane tubulation in cultured cells, is required for SSR expansion. Consistent with a model in which syndapin acts directly on postsynaptic membrane, SSR expansion requires conserved residues essential for membrane binding in vitro. However, syndapin's Src homology (SH) 3 domain, which negatively regulates membrane tubulation in cultured cells, is required for synaptic targeting and strong SSR induction. Our observations advance knowledge of syndapin protein function by 1) demonstrating the in vivo relevance of membrane remodeling mechanisms suggested by previous in vitro and structural analyses, 2) showing that SH3 domains are necessary for membrane expansion observed in vivo, and 3) confirming that F-BAR proteins control complex membrane structures.     

Immobilization of creatininase, creatinase and sarcosine oxidase on iron oxide nanoparticles/chitosan-g-polyaniline modified Pt electrode for detection of creatinine

Commercial enzymes, creatininase (CA) from Pseudomonas sp, creatinase (CI) from Pseudomonas sp, sarcosine oxidase (SO) from Bacillus sp were co-immobilized onto iron oxide nanoparticles/chitosan-graft-polyaniline (Fe(3)O(4)-NPs/CHIT-g-PANI) composite film electrodeposited on surface of Pt electrode through glutaraldehyde coupling. Transmission electron microscopy (TEM) was used for characterization of Fe(3)O(4)-NPs. A creatinine biosensor was fabricated using Enzymes/Fe(3)O(4)-NPs/CHIT-g-PANI/Pt electrode as working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode. The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopic and electrochemical impedance spectroscopy (EIS). The biosensor exhibited an optimum response within 2s at pH 7.5 and 30 °C, when polarized at 0.4V vs Ag/AgCl. The electrocatalytic response showed a linear dependence on creatinine concentration ranging from 1 to 800 μM. The sensitivity of the biosensor was 3.9 μA μM(-1) cm(-2), with a detection limit of 1 μM (S/N=3). Apparent Michaelis-Menton (K(m)) value for creatinine was 0.17 mM. The biosensor showed only 10% loss in its initial response after 120 uses over 200 days, when stored at 4 °C. The biosensor measured creatinine in the serum of apparently healthy persons which correlated well with a standard colorimetric method (r=0.99).     

Ultrastructure of trichome of old world porcupine of Indian subcontinent

The present investigation is based on ultrastructural details of different types of quills of two species of old world porcupine (Hystrix indica and Hystrix brachyura) of Indian subcontinent using environmental scanning electron microscopy (ESEM). In H. indica, four types of quills have been detected – bristlelike spines, stilettolike spines, spikes and mane. The quills of H. brachyura are categorized into four types – broad, slender, hollow tail quill and quills of the anogenital region. The ESEM images of surface characteristic of different types of quills of both the species except the hollow tail quill showed usual scaly features without having any differences. The cross‐sectional images of quills of H. indica and H. brachyura show a narrow cortex and a broad medullary region with a network of anastomosing channels. The cortical layer is comparatively thicker in mane hairs of H. indica and in slender quills of H. brachyura. With extensive exploration of the anatomical structures of the quills by ESEM from both the species of Hystrix, we could not find ‘osmetrichia’ in any forms of quill. In contrast, we hypothesized that the channels and network of medulla are serving the purpose for transportation of pheromonal signalling molecules in old world porcupine.     

Optimization of mycophenolic acid production in solid state fermentation using response surface methodology

Mycophenolic acid (MPA) can be produced in solid state fermentation. An isolate of Penicillium brevi-compactum ATCC 16024 grown on moist wheat bran produced a titre of 425 mg per kg of wheat bran. Central composite rotatable design and response surface methodology were employed to derive a statistical model for media optimization towards production of mycophenolic acid. Five levels with a five factorial design were adopted. The correlation coefficient was 0.82, ensuring a satisfactory adjustment of the model to the experimental values. This statistical design was very effective in improving the titre of mycophenolic acid up to 3286 mg per kg of wheat bran. Received 24 July 1998/ Accepted in revised form 4 December 1998