Phenotypic plasticity and longevity in plants and animals: cause and effect?

Immobile plants and immobile modular animals outlive unitary animals. This paper discusses competing but not necessarily mutually exclusive theories to explain this extreme longevity, especially from the perspective of phenotypic plasticity. Stem cell immortality, vascular autonomy, and epicormic branching are some important features of the phenotypic plasticity of plants that contribute to their longevity. Monocarpy versus polycarpy can also influence the kind of senescent processes experienced by plants. How density-dependent phenomena affecting the establishment of juveniles in these immobile organisms can influence the evolution of senescence, and consequently longevity, is reviewed and discussed. Whether climate change scenarios will favour long-lived or short-lived organisms, with their attendant levels of plasticity, is also presented.

Facile preparation and some applications of an affinity matrix with a cleavable connector arm containing a disulfide bond

A versatile affinity matrix in which the ligand of interest is linked to the matrix through a connector arm containing a disulfide bond is described. It can be synthesized from any amino-substituted matrix by successive reaction with 2-imino-thio-lane, 5, 5'-dithiobis(2-nitrobenzoic acid), and a thiol derivative of the ligand of choice. The repertoire of ligands can be significantly increased by the appropriate use of avidin-biotin bridges. After adsorption of the material to be fractionated, elution can be effected by reducing the disulfide bond in the connector arm with dithiothreitol. Examples of the preparation and use of various affinity matrices based on amino-substituted Sepharose 6MB are given. One involves the immobilization of the Fab' fragment of a monoclonal antibody against Aspergillus oryzae β-galactosidase and the specific binding of that enzyme to the resulting immunoaffinity matrix. Another involves the immobilization of N-biotinyl-2-thioethylamine followed by complex formation with avidin. The resulting avidin-substituted matrix was used for the selective adsorption and subsequent recovery of mouse hybridoma cells producing anti-avidin antibodies. By further complexing the avidin-substituted matrix with appropriate biotinylated antigens, it should be possible to fractionate cells producing antibodies against a variety of antigens.

AB2 + A Type Copolymerization Approach for the Preparation of Thermosensitive PEGylated Hyperbranched Polymers

Hyperbranched polyethers having poly(ethylene glycol) (PEG) segments at their molecular periphery were prepared by a simple procedure wherein an AB2 type monomer was melt-polycondensed with an A-type monomer, namely, heptaethylene glycol monomethyl ether. The presence of a large number of PEG units at the termini rendered a lower critical solution temperature (LCST) to these copolymers, above which they precipitated out of an aqueous solution. In an effort to understand the effect of various molecular structural parameters on their LCST, the length of the hydrophobic spacer segment within the hyperbranched core and the extent of PEGylation were varied. Additionally, linear analogues that incorporates pendant PEG segments were also prepared and comparison of their LCST with that of the hyperbranched analogue clearly revealed that hyperbranched topology leads to a substantial increase in the LCST, highlighting the importance of the peripheral placement of the PEG units.

Fish stupefying plants used by the Gond tribal of Mendha village of Central India

Fish stupefying plants and their methods of use by the Gond people of Mendha village of the Gadchiroli district in Maharashtra state have been documented. For the purpose of validation, literature survey revels that many fish stupefying plants being used since long time by local people are recently well tested by many workers and are found to have many important medicinal properties. It was also observed that herbal fish stupefying agents are excellent means of fishing, which do not kill whole fish stock like chemicals.

The Use of Liquid-Liquid Interface (Biphasic) for the Preparation of Benzenetricarboxylate Complexes of Cobalt and Nickel

New metal-organic frameworks (MOFs) [Ni(C12N2H10)(H2O)][C6H3(COO)2(COOH)] (I), [Co2(H2O)6][C6H3(COO)3]2·(C4N2H12)(H2O)2 (II), [Ni2(H2O)6][C6H3(COO)3]2·(C4N2H12)(H2O)2 (III), [Ni(C13N2H14)(H2O)][C6H3(COO)2(COOH)] (IV), [Ni3(H2O)8][C6H3(COO)3] (V) and [Co(C4N2H4)(H2O)][C6H3(COO)3] (VI) {C6H3(COOH)3 = trimesic acid, C12N2H10 = 1,10-phenanthroline, C4N2H12 = piperazine dication, C13N2H14 = 1,3-bis(4-pyridyl)propane and C4N2H4 = pyrazine} have been synthesized by using an interface between two immiscible solvents, water and cyclohexanol. The compounds are constructed from the connectivity between the octahedral M2+ (M = Ni, Co) ions coordinated by oxygen atoms of carboxylate groups and water molecules and/or by nitrogen atoms of the ligand amines and the carboxylate units to form a variety of structures of different dimensionality. Strong hydrogen bonds of the type O-H···O are present in all the compounds, which give rise to supramolecularly organized higher-dimensional structures. In some cases ··· interactions are also observed. Magnetic studies indicate weak ferromagnetic interactions in I, IV and V and weak antiferromagnetic interactions in the other compounds (II, III and VI). All the compounds have been characterized by a variety of techniques.

Preparation, characterization and electrical conductivity studies of MWCNT/ZnO nanoparticles hybrid

Multiwall carbon nanotubes (MWCNTs) were decorated with crystalline zinc oxide nanoparticles (ZnO NPs) by wet chemical route to form MWCNT/ZnO NPs hybrid. The hybrid sample was characterized by scanning and transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Electrical conductivity of the hybrid can be tuned by varying the ZnO NPs content in the hybrid. In order to investigate the effect of nanoparticles loading on the conduction of MWCNTs network, electrical conductivity studies have been carried out in the wide temperature range 1.5-300K. The electrical conductivity of the hybrid below 100K is explained with the combination of variable range hopping conduction and thermal fluctuation induced tunnelling model. (C) 2009 Elsevier B.V. All rights reserved.

Preparation and Characterization of Glycolipid-Bearing Multilamellar and Unilamellar Liposomes

The carbohydrate residues of glycosphingolipids were implicated in many biologic processes such as cell-to-cell interactions; and as receptors for some viruses, bacterial and plant toxins, hormones, and so forth, and invariably for all the lectins (1). However, their receptor functions remained poorly defined for a long time as they form micelles even at very low concentrations in aqueous medium. In micelles, the oligosaccharide chains are not expected to have a well defined orientation suitable for recognition by macromolecular ligands. This problem was overcome by incorporating them in model membranes, namely, the liposomes. The demonstration of lectin-glycolipid interaction using liposomal model membranes was a crucial development that established glycolipids as biological receptors. Moreover, glycolipid-bearing liposomes provide a convenient system for investigating the role of glycolipid density, orientation, and exposure of their oligosaccharide chains at the membrane interface relevant to their receptor function (2–4).

Nucleotidases in plants *1, , *2: III. Effect of metabolites on the enzyme hydrolyzing flavine adenine dinucleotide (FAD) from Phaseolus radiatus

The highly purified enzyme from mung bean seedlings hydrolyzing FAD at pH 9.4 and temperature 49 °, functioned with an initial fast rate followed by a second slower rate. The activity was linear with enzyme concentration over a small range of concentration and was dependent on the time of incubation. Inhibition of enzyme activity with increasing concentrations of AMP was sigmoid;concentrations less than 1 × 10−6 M were without effect, concentrations between 1 × 10−6 and 8 × 10−5 M inhibited by 20% and concentrations beyond 8 × 10−5 Image caused progressive inhibition. Concentrations beyond 1 × 10−3 Image inhibited the activity completely. Preincubation of the enzyme with PCMB or NEM, or aging, or reversible denaturation with urea abolished the inhibitory effect of AMP at concentrations lower than 8 × 10−6 Image . The aged enzyme could be reactivated by ADP.

Preparation, characterization and thermal decomposition of praseodymium, terbium and neodymium carbonates

The preparation of three different types of carbonates of praseodymium, neodymium and terbium has been described. The carbonates have been characterized by potentiometry, chemical analysis, X-ray crystallography, infra-red spectroscopy and by their thermal behaviour. The thermal decomposition of several carbonates has been studied exhaustively under a variety of conditions and the stoicheiometry, thermodynamics and energetics of the reactions at various stages of decomposition have been examined. The stoicheiometry of the oxides obtained as final products of decomposition has been examined.

Nucleotidases in plants : I. Partial purification and properties of the enzyme hydrolyzing flavine adenine dinucleotide from mung bean seedlings (Phaseolus radiatus)

The occurrence of an enzyme hydrolyzing flavine adenine dinucleotide (FAD) was demonstrated in a number of seed extracts. The enzyme from Phaseolus radiatus was purified 104-fold by fractionation with ammonium sulfate and ethanol and by negative adsorption on alumina Cγ gel. The enzyme cleaves the POP bond of FAD to yield flavine mononucleotide and adenosine monophosphate. When reduced glutathione is added to the enzyme, it cleaves FAD at the COP bond to yield riboflavine, adenosine, and pyrophosphate, Both the activities are optimal at a pH of 7.2 and at a temperature of 37 . The Km for both the activities is 1.65 × 10−5 M. The stoichiometry and the identity of the products of both the treated and untreated enzyme were established. The untreated enzyme was not inhibited by pCMB or arsenite, but the treated enzyme was sensitive to both these inhibitors. The inhibition by pCMB could be reversed by monothiols and the inhibition by arsenite by dithiols.

Preparation of lithium amalgam

Lithium amalgam is useful in effecting Wurtz type intramolecular and intermolecular coupling reactions.

Biosynthesis of valine and isoleucine in plants II. Dihydroxyacid dehydratase from Phaseolus radiatus

1. 1. An enzyme catalysing the conversion of α,β-dihydroxyisovalerate and α,β-dihydroxy-β-methylvalerate to α-ketoisovalerate and α-keto-β-methylvalerate has been partially purified from green gram (Phaseolus radiatus), and its characteristics studied. 2. 2. A natural inhibitor, heat stable and inorganic in nature, was observed in the crude extracts. 3. 3. The observed Km values for α-β-dihydroxyisovalerate and α,β-dihydroxy-β-methylvalerate were 2.4 · 10-3 M and 9 · 10-4 M, respectively. 4. 4. The enzyme required the presence of a divalent metal ion (Mg2+, Mn2+ or Fe2+) for maximal activity. Heavy metals like Ag+ and Hg2+ were inhibitory. 5. 5. The optimal activity was around pH 8.0 and the optimum temperature at 52°. The activation energy is found to be 12 600 cal/mole. 6. 6. The enzyme was inhibited by p-hydroxymercuribenzoate, N-ethylmaleimide and sulphydryl compounds like cysteine, glutathione, 2-mercaptoethanol and 2,3-dimercaptopropanol. The inhibition by p-hydroxymercuribenzoate could not be reversed by any of the sulfhydryl compounds tested.

Hydrolysis of riboflavin in plants

The enzymic hydrolysis of riboflavin to lumichrome and ribitol by extracts of Crinum longifolium bulbs has been demonstrated. The enzyme was purified 48-fold by ZnSO4 treatment and ethanol fractionation, and concentrated by using Sephadex G-25. After establishing the stoichiometry of the reaction, the general properties of the purified enzyme were studied. The enzyme showed maximal activity at pH 7·5, and it had a requirement for reduced glutathione which could be replaced by cysteine or ascorbic acid. Mg2+ and Li+ activated the enzyme. The reaction was highly specific to riboflavin and was competitively inhibited by riboflavin 5′-phosphate.

Biosynthesis of valine and isoleucine in plants I. Formation of α-acetolactate in Phaseolus radiatus

1. 1. The presence of an enzyme system in plants catalyzing the formation of α-acetolactate from pyruvate has been demonstrated; the system in green gram (Phaseolus radiatus) has been partially purified and its characteristics have been studied.2. Free acetaldehyde is formed as a product of the reaction and so the reaction is mainly diverted towards the formation of acetoin. 3. The system requires thiamine pyrophosphate and a divalent metal ion (Mn2+ or Mg2+) for maximum activity. The optimum pH is around 6.0 and the optimum temperature is 60°. 4. The system is very labile in absence of pyruvate, Mn2+ and DPT. 5. The Km values for pyruvate, Mn2+, Mg2+ and DPT are 3·10−2 M. 5·10−5 M, 2·10−5 M, and e·10−6 M respectively. The activation energy is 3540 cal/mole. 6. The enzyme is strongly inhibited by p-chloromercuribenzoate and the inhibition can be reversed partially by 2-mercaptoethanol, BAL or cysteine. Heavy metals, such as Hg2+ and Ag+, are inhibitory but l-valine does not inhibit the reaction.