Effect of dietary nickel and iron on the trace element content of rat liver

The level and/or form of dietary iron, dietary nickel, and the interaction between them affected the trace element content of rat liver. Livers were from the offspring of dams fed diets containing 10–16 ng, or 20 μg, of nickel/g. Dietary iron was supplied as ferric chloride (30 μg/g) or ferric sulfate (30 μg, or 60 μg). In nickel-deprived rats fed 60 μg of iron/g of diet as ferric sulfate, at age 35 days, levels of iron and zinc were depressed in liver and the level of copper was elevated. At age 55 days, iron was still depressed, copper was still elevated, but zinc also was elevated. In rats fed 30 μg of iron/g of diet as ferric chloride, liver iron content was higher in nickel-deprived than in nickel-supplemented rats at 30, but not at 50, days of age. Also manganese and zinc were lower in nickel-deprived than in nickel-supplemented rats at age 35 days if their dams had been on experiment for an extended period of time (i.e., since age 21 days). Thus, the levels of copper, iron, manganese, and zinc in liver were affected by nickel deprivation, but the direction and extent of the affects depended upon the iron status of the rat.     

In vitro and in vivo manipulations of bacteriophage Mu DNA: cloning of Mu ends and construction of mini-Mu's carrying selectable markers

Recombinant plasmids carrying one or both ends of the bacteriophage Mu genome were constructed by molecular cloning. Transposable mini-Mu's with selectable markers (ampicillin resistance, kanamycin resistance or the entire lac operon of Escherichia coli) inserted between the Mu ends were also constructed. As a source of lac operon DNA, a pBR322 derivative with a 27 kb insert containing the lac operon was constructed. The plasmids with both ends of Mu (mini-Mu's) conferred full Mu immunity upon the host cells. However, the same mini-Mu's containing kan or lac inserts were defective in immunity. A summary of the construction and physical characterization, including restriction endonuclease cleavage maps and some of the biological properties of the plasmids, is presented.     

Determination of the sequence of an expressible cDNA clone encoding ERp60/calregulin by the use of a novel nested set method

An analysis of the N-terminal sequence of the luminal endoplasmic reticulum protein, ERp60, showed that it was identical to the well-characterized Ca2+-binding protein, calregulin. A full-length, expressible cDNA clone encoding this protein was isolated from a mouse fibroblast cDNA library. A novel nested set strategy for the production of overlapping fragments for DNA sequencing was used to determine the complete nucleotide (nt) sequence of both strands of the ERp60 clone. This method utilizes a series of nonspecific deletion primers in conjunction with a specific site primer to generate the nested set fragments. This procedure possesses several advantages over other nested set techniques, since it does not require (i) the re-cloning of the DNA insert into other vectors, (ii) any prior knowledge of the restriction sites of the nt sequence, or (iii) the transformation and analysis of bacterial subclones. ERp60 has a 17-amino acid (aa) signal sequence and the mature protein contains 399 aa with a calculated M(r) of 46,347.     

Effects of treating seed potatoes with trace elements on sprouting and microbial spoilage during storage under tropical conditions

Attempts were made to extend the storage life of seed potatoes by treating them with trace elements as antimicrobial and antisprouting agents. In tests to measure the growth of Fusarium oxysporum, and Erwinia carotovora pv. carotovora it was found to be decreased more by iron, copper and zinc than by boron, manganese and molybdenum. Dipping seed tubers in aqueous solutions of trace element salts decreased both sprouting and microbial spoilage during storage at ambient conditions. Field testing at the end of storage proved that treating seed potatoes with ferrous sulphate did not decrease the yield of tubers or increase their iron content. It is suggested that trace elements may be used to extend the storage life of seed potato tubers, in tropical conditions.     

Reprogramming of cells following wounding in pea (Pisum sativum L.) roots. II. The effects of caffeine and colchicine on the development of new vascular elements

Summary Interference with the normal progression of the cell cycle by the drugs caffeine and colchicine does not prevent parenchyma cells in the cortex of pea roots from being reprogrammed to become tracheary and sieve elements following severance of the vascular cylinder of the root. The pattern of secondary wall deposition of the newly differentiated tracheary elements is highly aberrant in the presence of colchicine but is of normal appearance in the caffeinetreated roots. In each case, the new sieve elements have sieve plates and lateral sieve areas with callose deposits. Induction and redifferentiation are achieved in the absence of cell division and microtubules in colchicine-treated roots.Bi- and multi-nucleate cells are produced by both drugs. Microtubules are still present in the caffeine-treated roots but cell plate formation is inhibited. The partitioning of the multinucleate cortical cells by the interdigitation of free-growing walls between the nuclei occurs in the presence of caffeine but not colchicine.     

Trace elements extractable by 2-ketogluconic acid from soils and their relationship to plant contents

Summary Trace element levels extractable by 2-ketogluconic acid (2-KG), ammonium acetate, acetic acid, EDTA, and DTPA were determined in three different soils of the Tarves association. The 2-ketogluconic acid was derived from 2-litre batch cultures of a soil bacterium,Erwinia sp. Pasture grasses and clovers growing on these soils were also analysed. At the same pH, 2-KG extracted more Co, Ni and Zn and considerably more Fe, Ti and V than ammonium acetate. The quantities of Cu, Mn, Mo, Ni and Zn extracted by 2-KG from the three soils generally reflected, in a similar way to the other extractants, the contents of these elements in grasses and clovers growing on the soils.     

Escher: A new docking procedure applied to the reconstruction of protein tertiary structure

Evaluation of Surface Complementarity, Hydrogen bonding, and Electrostatic interaction in molecular Recognition (ESCHER) is a new docking procedure consisting of three modules that work in series. The first module evaluates the geometric complementarity and produces a set of rough solutions for the docking problem. The second module identifies molecular collisions within those solutions, and the third evaluates their electrostatic complementarity. We describe the algorithm and its application to the docking of cocrystallized protein domains and unbound components of protein-protein complexes. Furthermore, ESCHER has been applied to the reassociation of secondary and supersecondary structure elements. The possibility of applying a docking method to the problem of protein structure prediction is discussed. Proteins 28:556–567, 1997. © 1997 Wiley-Liss, Inc.