Aminoalkoxybiphenylnitriles as histamine-3 receptor ligands

Biaryl nitrile amines were prepared and found to have high affinity and selectivity for human and rat histamine H(3) receptors.     

Crystal structure of CHP2 complexed with NHE1-cytosolic region and an implication for pH regulation

The plasma membrane Na+/H+ exchangers (NHE) require calcineurin B homologous protein (CHP) as an obligatory binding partner for ion transport. Here, we report the first crystal structure of CHP (CHP2 isoform) in complex with its binding domain in NHE1. We show that the cytoplasmic alpha-helix of NHE1 is inserted into the hydrophobic cleft formed by N- and C-lobes of CHP2 and that the size and shape of this crevice together with hydrogen bond formation at multiple positions assure a high degree of specificity for interaction with NHE members. Structure-based mutagenesis revealed the importance of hydrophobic interactions between CHP/NHE1 for the function of NHE1. Furthermore, the crystal structure shows the existence of a protruding CHP-unique region, and deletion of this region in CHP2 inhibited the NHE1 activity by inducing the acidic shift of intracellular pH dependence, while preserving interaction with NHE1. These findings suggest that CHP serves as an obligatory subunit that is required both for supporting the basic activity and regulating the pH-sensing of NHE1 via interactions between distinct parts of these proteins.     

Production of monoclonal antibodies specific for Eimeria tenella microgametocytes

A panel of 4 monoclonal antibodies specific for Eimeria tenella, the causative agent of cecal coccidiosis of birds in the genus Gallus, was produced by standard techniques. The indirect fluorescent antibody (IFA) test demonstrated specificity of these 4 antibodies for the microgametocytes. Hybridoma TIA3B9 secreted a monoclonal antibody of subisotype IgG2b that was used throughout the course of this study. Immunologic potency of this antibody was demonstrated by in vitro experiments that revealed a greater than 50% reduction in oocyst production, indicating an apparent inhibition of fertilization.     

The fine structure of the developmental stages of the microsporidian Nosema apis Zander

Schizonts, sporonts and sporoblasts of Nosema apis from honey bees collected in the summer and winter were studied with the electron microscope. The nuclei usually had a diplokaryon arrangement. Intranuclear spindles with polar vesicles were associated with division. Schizonts had a single limiting unit membrane, whereas sporonts had a two-layered wall. Sporonts from summer bees had only a thin single limiting membrane in some areas and evidence of endocytosis was sometimes seen in these. Sporonts from winter bees had branched tubular outpocketings from the wall. In sporoblasts, the development of the polar filament was closely associated with a network of dense structures interwoven with a system of tubules evidently of ER derivation; the Golgi complex was associated with this network.     

Studies on the rhizosphere mycoflora of broad bean and cotton

Summary The fungal flora of the rhizosphere of three varieties of broad bean and cotton was studied by the dilution-plate technique. The numbers of fungi were higher in the rhizosphere than in the non-rhizosphere soil. Plant type and age, and soil type have a significant influence of the nature and numbers of fungal flora associated with plant roots.Cladosporium was relatively more abundant in the rhizosphere of broad bean varieties, whilePenicillium was found to constitute a high percentage of fungi found in the rhizosphere of cotton varieties. Plant variety has no influence on the nature of such fungal flora.     

Energy-transducing nicotinamide nucleotide transhydrogenase: Nucleotide sequences of the genes and predicted amino acid sequences of the subunits of the enzyme fromRhodospirillum rubrum

Based on the amino acid sequence of the N-terminus of the soluble subunit of theRhodospirillum rubrum nicotinamide nucleotide transhydrogenase, two oligonucleotide primers were synthesized and used to amplify the corresponding DNA segment (110 base pairs) by the polymerase chain reaction. Using this PCR product as a probe, one clone with the insert of 6.4kbp was isolated from a genomic library ofR. rubrum and sequenced. This sequence contained three open reading frames, constituting the genesnntA1, nntA2, andnntB of theR. rubrum transhydrogenase operon. The polypeptides encoded by these genes were designated 1, 2, and , respectively, and are considered to be the subunits of theR. rubrum transhydrogenase. The predicted amino acid sequence of the 1 subunit (384 residues; molecular weight 40276) has considerable sequence similarity to the subunit of theEscherichia coli and the N-terminal 43-kDa segment of the bovine transhydrogenases. Like the latter, it has a fold in the corresponding region, and the purified, soluble 1 subunit cross-reacts with antibody to the bovine N-terminal 43-kDa fragment. The predicted amino acid sequence of the subunit of theR. rubrum transhydrogenase (464 residues; molecular weight 47808) has extensive sequence identity with the subunit of theE. coli and the corresponding C-terminal sequence of the bovine transhydrogenases. The chromatophores ofR. rubrum contain a 48-kDa polypeptide, which cross-reacts with antibody to the C-terminal 20-kDa fragment of the bovine transhydrogenase. The predicted amino acid sequence of the 2 subunit of theR. rubrum enzyme (139 residues; molecular weight 14888) has considerable sequence identity in its C-terminal half to the corresponding segments of the bovine and the subunit of theE. coli transhydrogenases.     

Natural endophytic association between Rhizobium leguminosarum bv. trifolii and rice roots and assessment of its potential to promote rice growth

For over 7 centuries, production of rice (Oryza sativa L.) in Egypt has benefited from rotation with Egyptian berseem clover (Trifolium alexandrinum). The nitrogen supplied by this rotation replaces 25- 33% of the recommended rate of fertilizer-N application for rice production. This benefit to the rice cannot be explained solely by an increased availability of fixed N through mineralization of N- rich clover crop residues. Since rice normally supports a diverse microbial community of internal root colonists, we have examined the possibility that the clover symbiont, Rhizobium leguminosarum bv. trifolii colonizes rice roots endophytically in fields where these crops are rotated, and if so, whether this novel plant-microbe association benefits rice growth. MPN plant infection studies were performed on macerates of surface-sterilized rice roots inoculated on T. alexandrinum as the legume trap host. The results indicated that the root interior of rice grown in fields rotated with clover in the Nile Delta contained 10⁶ clover-nodulating rhizobial endophytes g fresh weight of root. Plant tests plus microscopical, cultural, biochemical, and molecular structure studies indicated that the numerically dominant isolates of clover-nodulating rice endophytes represent 3 – 4 authentic strains of R. leguminosarum bv. trifolii that were Nod Fix on berseem clover. Pure cultures of selected strains were able to colonize the interior of rice roots grown under gnotobiotic conditions. These rice endophytes were reisolated from surface-sterilized roots and shown by molecular methods to be the same as the original inoculant strains, thus verifying Koch's postulates. Two endophytic strains of R. leguminosarum bv. trifolii significantly increased shoot and root growth of rice in growth chamber experiments, and grain yield plus agronomic fertilizer N-use efficiency of Giza-175 hybrid rice in a field inoculation experiment conducted in the Nile Delta. Thus, fields where rice has been grown in rotation with clover since antiquity contain Fix strains of R. leguminosarum bv. trifolii that naturally colonize the rice root interior, and these true rhizobial endophytes have the potential to promote rice growth and productivity under laboratory and field conditions.