The Hertz Corporation

About: The Hertz Corporation is a based out in . It is known for research contribution in the topics: Population & Soil water. The organization has 9562 authors who have published 11044 publications receiving 447929 citations. The organization is also known as: Hertz Rental Car & Hertz Rent-a-Car.

PCR-identification of a Nicotiana plumbaginifolia cDNA homologous to the high-affinity nitrate transporters of the crnA family

Abstract: A family of high-affinity nitrate transporters has been identified in Aspergillus nidulans and Chlamydomonas reinhardtii, and recently homologues of this family have been cloned from a higher plant (barley). Based on six of the peptide sequences most strongly conserved between the barley and C. reinhardtii polypeptides, a set of degenerate primers was designed to permit amplification of the corresponding genes from other plant species. The utility of these primers was demonstrated by RT-PCR with cDNA made from poly(A)+ RNA from barley, C. reinhardtii and Nicotiana plumbaginifolia. A PCR fragment amplified from N. plumbaginifolia was used as probe to isolate a full-length cDNA clone which encodes a protein, NRT2;1Np, that is closely related to the previously isolated crnA homologue from barley. Genomic Southern blots indicated that there are only 1 or 2 members of the Nrt2 gene family in N. plumbaginifolia. Northern blotting showed that the Nrt2 transcripts are most strongly expressed in roots. The effects of external treatments with different N sources showed that the regulation of the Nrt2 gene(s) is very similar to that reported for nitrate reductase and nitrite reductase genes: their expression was strongly induced by nitrate but was repressed when reduced forms of N were supplied to the roots.

Carbon and nitrogen metabolism in barley (Hordeum vulgare L.) mutants lacking ferredoxin-dependent glutamate synthase

Abstract: Five mutant lines of barley (Hordeum vulgare L.), which are only able to grow at elevated levels of CO2, contain less than 5% of the wild-type activity of ferredoxin-dependent glutamate synthase (EC 1.4.7.1). Two of these lines (RPr 82/1 and RPr 82/9) have been studied in detail. Leaves and roots of both lines contain normal activities of NADH-dependent glutamate synthase (EC 1.4.1.14) and the other enzymes of ammonia assimilation. Under conditions that minimise photorespiration, both mutants fix CO2 at normal rates; on transfer to air, the rates drop rapidly to 15% of the wild-type. Incorporation of (14)CO2 into sugar phosphates and glycollate is increased under such conditions, whilst incorporation of radioactivity into serine, glycine, glycerate and sucrose is decreased; continuous exposure to air leads to an accumulation of (14)C in malate. The concentrations of malate, glutamine, asparagine and ammonia are all high in air, whilst aspartate, alanine, glutamate, glycine and serine are low, by comparison with the wild-type parent line (cv. Maris Mink), under the same conditions. The metabolism of [(14)C]glutamate and [(14)C]glutamine by leaves of the mutants indicates a very much reduced ability to convert glutamine to glutamate. Genetic analysis has shown that the mutation in RPr 82/9 segregates as a single recessive nuclear gene.

Large elastic deformations of isotropic materials X. Reinforcement by inextensible cords

Abstract: The theory of large elastic deformations of incompressible, isotropic materials developed in previous papers of this series is employed to examine some simple deformations of elastic bodies reinforced with cords. The cords are assumed to be thin, flexible and inextensible, and to lie parallel and close together in smooth surfaces in the undeformed body, which is thus divided into sections by boundary surfaces which are inextensible in certain directions. In the simple problems considered, the cords impose relationships upon the parameters which specify the deformation. The following examples are examined from this point of view: (i) the pure homogeneous strain of a thin uniform sheet containing a double layer of cords lying in a plane midway between its major surfaces; (ii) the combined pure homogeneous strain and flexure of a cuboid containing a double layer of cords lying in a plane parallel to a pair of opposite faces, the two sets of cords being unsymmetrically disposed in this plane with respect to the remaining faces of the cuboid, and the symmetrical case being obtained from this by a suitable choice of constants; (iii) the combined extension and flexure of a thin rectangular sheet with two sets of cords placed symmetrically in a plane parallel to its major surfaces, the problem being considered as a limiting case of (ii); (iv) the simultaneous extension, inflation and torsion of a cylindrical tube containing one or two sets of cords lying in helical paths concentric with the axis of the cylinder. In all cases, relations are obtained for the determination of the tensions in the cords in terms of the applied forces and the parameters which define the deformation.