Influence of calcium chloride and benzyladenine on lipoxygenase of Vigna unguiculata leaf discs during senescence

Cowpea ( Vigna unguiculata L.) leaf discs incubated in the dark in CaCl₂ and benzyladenine maintained higher levels of chlorophyll and protein than controls. The CaCl₂ or benzyladenine treatments reduced lipoxygenase activity, and the effect of these compounds in combination was additive. HPLC analysis of the product profile of lipoxygenase activity with arachidonic acid as a substrate showed a single peak comigrating with standard 15-hydroperoxyeicosatetraenoic acid. There appears to be a strong temporal correlation between the CaCl₂+ benzyladenine delay of senescence and lipoxygenase activity.     

Isolation, macromolecular properties, and combining site of a chito-oligosaccharide-specific lectin from the exudate of ridge gourd (Luffa acutangula)

A lectin specific for chito-oligosaccharides from the exudate of ridge gourd (Luffa acutangula) fruits has been purified to homogeneity by affinity chromatography. The lectin has a molecular weight of 48,000, an S(0)20,w of 4.06 S and a Stokes radius of 2.9 nm. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a single band corresponding to Mr of 24,000 was observed both in the presence and absence of beta-mercaptoethanol. The subunits in this dimeric lectin are, therefore, held together solely by noncovalent interactions. The lectin is not a glycoprotein, and secondary structure analysis by CD measurements showed 31% alpha-helix. The hemagglutinating activity of L. acutangula agglutinin was not inhibited by any of the monosaccharides tested. Among the disaccharides only di-N-acetylchitobiose was inhibitory. The inhibitory potency of chito-oligosaccharides increased dramatically with their size up to penta-N-acetylchitopentaose. The lectin has two binding sites for saccharides. The affinity of chito-oligosaccharides for L. acutangula lectin, as monitored by titrating the changes in the near UV-CD spectra and intrinsic fluorescence, increased strikingly with the number of GlcNAc units in them. The values of delta G, delta H, and delta S for the binding process showed a pronounced dependence on the size of the chito-oligosaccharides, indicating that the binding of higher oligomers is progressively more favored thermodynamically than di-N-acetylchitobiose. The thermodynamic data are consistent with an extended binding site in this lectin, which accommodates a tetrasaccharide.     

A tetracopper(II) complex with N,N′-bis(picolinoyl)hydrazine

Synthesis, physical properties and X-ray structure of a hydrated tetranuclear copper(II) complex [Cu₄(μ-diph)₂(μ-H₂O)₂(O₂CCH₃)₄(H₂O)₂]·4H₂O with N,N′-bis(picolinoyl)hydrazine (H₂diph) are reported. The centrosymmetric complex has two types of copper(II) centres with distorted square-pyramidal N₂O₃ coordination spheres. The dinucleating trans planar diph²⁻ ligands are parallel to each other and act as N₂O-donor to one metal centre and N₂-donor to the other metal centre. The complex has a rectangular {Cu₄(μ-N-N)₂(μ-OH₂)₂} core with Cu···Cu distances as 4.834(1) and 3.762(1) Å. Solid state as well as solution electronic spectra show several transitions in the wavelength range 700-280 nm. The room temperature (298 K) solid state magnetic moment is 3.55 μ_B. The powder EPR spectra at 298 and 130 K are very similar and axial (g_∥ = 2.25 and g_⊥ = 2.08) in character.     

Molecular cloning and expression of bovine nucleoplasmin 2 (NPM2): a maternal effect gene regulated by miR-181a

Background  

Nucleoplasmin 2 (NPM2) is an oocyte-specific nuclear protein essential for nuclear and nucleolar organization and early embryonic development. The aims of this study were to clone the bovine NPM2 gene, determine its temporal expression during oocyte development and early embryogenesis, and evaluate the potential role of miRNA-181a in regulation of its expression.     

Morphological and molecular screening of rice germplasm lines for low soil P tolerance

Phosphorus (P) is an essential macronutrient to all crops including rice and it plays a key role in various plant activities and development. Low availability of P in the soils negatively, influences rice crop growth and causes significant yield loss. In the present study, we characterized a set of 56 germplasm lines for their tolerance to low soil P by screening them at low soil P and optimum soil P levels along with low soil P tolerant and sensitive check varieties. These lines were genotyped for the presence/absence of tolerant allele with respect to the major low soil P tolerance QTL, Pup1, using a set of locus specific PCR-based markers, viz., K46-1, K46-2, K52 and K46CG-1. High genetic variability was observed for various traits associated with low soil P tolerance. The yield parameters from normal and low soil P conditions were used to calculate stress tolerance indices and classify the genotypes according to their tolerance level. Out of the total germplasm lines screened, 15 lines were found to be tolerant to low soil P condition based on the yield reduction in comparison to the tolerant check, but most of them harbored the complete or partial Pup1 locus. Interestingly, two tolerant germplasm lines, IC216831 and IC216903 were observed to be completely devoid of Pup1 and hence they can be explored for new loci underlying low soil P tolerance.

     

Fluorescence studies on the interaction of choline-binding domain B of the major bovine seminal plasma protein,PDC-109 with phospholipid membranes

The microenvironment and accessibility of the tryptophan residues in domain B of PDC-109 (PDC-109/B) in the native state and upon ligand binding have been investigated by fluorescence quenching, time-resolved fluorescence and red-edge excitation shift (REES) studies. The increase in the intrinsic fluorescence emission intensity of PDC-109/B upon binding to lysophosphatidylcholine (Lyso-PC) micelles and dimyristoylphosphatidylcholine (DMPC) membranes was considerably less as compared to that observed with the whole PDC-109 protein. The degree of quenching achieved by different quenchers with PDC-109/B bound to Lyso-PC and DMPC membranes was significantly higher as compared to the full PDC-109 protein, indicating that membrane binding afforded considerably lesser protection to the tryptophan residues of domain B as compared to those in the full PDC-109 protein. Finally, changes in red-edge excitation shift (REES) seen with PDC-109/B upon binding to DMPC membranes and Lyso-PC micelles were smaller that the corresponding changes in the REES values observed for the full PDC-109. These results, taken together suggest that intact PDC-109 penetrates deeper into the hydrophobic parts of the membrane as compared to domain B alone, which could be the reason for the inability of PDC-109/B to induce cholesterol efflux, despite its ability to recognize choline phospholipids at the membrane surface.     

Effect of monocrotophos on mono amine oxidase activity in albino rats.

Monocrotophos inhibited monoamine oxidase (MAO) activity both in vitro and in vivo in liver, kidney and brain areas of albino rats. In vitro effect was more pronounced than the in vivo effect. During in vivo daily treatment with sublethal doses of Monocrotophos, the MAO activity was significantly inhibited after 1h to 7 days of treatments. Later recovery of inhibition was noticed which might be attributed to the enhanced absorption of Monocrotophos to protein and fat bodies or enhanced metabolic dispositional mechanisms. Brain areas exhibit varied responses to Monocrotophos toxicity.