Ac transposition in transgenic tomato plants

Summary As an initial step towards developing a transposon mutagenesis system in tomato, the maize transposable element Ac was transformed into tomato plants via Agrobacterium tumefaciens. Southern analysis of leaf tissue indicated that in nine out of eleven transgenic plants, Ac excised from the T-DNA and reintegrated into new chromosomal locations. The comparison of Ac banding pattern in different leaves of the same primary transformant provided evidnece for transposition during later stages of transgenic plant development. There was no evidence of Ds mobilization in tomato transformants.     

Salicyloylaspartate as an endogenous component in the leaves of Phaseolus vulgaris

An amide conjugate of o-methoxybenzoic acid and aspartic acid has been isolated from bean leaves. After extraction and methylation of plant material, this compound was isolated as two isomeric monoethyl monomethyl esters. The ethylation of the aspartyl carboxyl groups was shown to be a likely result of an extraction procedure utilising acidified ethanol, the methylation of the aromatic hydroxy of the methoxy group to be due to the derivatisation procedure. Studies with pentafluorobenzylation confirmed that the endogenous compound is o-hydroxybenzoylaspartate.     

Transient expression of wild type and mutant human apolipoprotein AI in COS cells

A human apolipoprotein AI (apo AI) minigene and two mutants were cloned into the vector pUHD10-1 for expression studies in COS cells under the control of the strong CMV (cytomegalovirus) enhancer and the own apo AI promoter. In the mutated apo AI minigene (mutant M1) the positions of the triplets of Gln(-2)-Gln-1 at the C-terminus of the prosequence were exchanged against Gln(-8)-Ala-7, the recognition site of the signal peptidase of the wild type human apo AI. The prosequence has been deleted in mutant M2 and the presequence linked directly to the N-terminus of the mature apo AI form. We report here on expression studies in COS cells, a cell line, which does not express apo AI. They were transfected by electroporation with pUHD10-1 constructs, which contain a) the wild type apo AI minigene and b) the two mutant apo AI minigenes with mutations described above. The following results were obtained: a) the wild type and mutant apo AI constructs were efficiently transcribed and translated in COS cells, b) the expression of the wild type preproapo AI minigene in COS cells led to the secretion of proapo AI (29 kDa), that of the mutant (M2) gene, devoid of the prosequence of mature apo AI (28.4 kDa), whereas the product of mutant gene M1 (31 kDa) with the recognition site of the signal peptides transposed to the C-terminus of the prosequence remained uncleaved within the COS cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Simultaneous degradation of the herbicides 2,4-dichlorophenoxyacetic acid and 2-(2-methyl-4-chlorophenoxy)propionic acid by mixed bacterial cultures

The simultaneous degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2-methyl-4-chlorophenoxy)propionic acid (mecoprop) was achieved by two mixed cultures in the absence of any additional carbon or energy substrates. Mecoprop was not completely degraded by either of the two cultures, nor did addition of 2,4-D affect the degradation of mecoprop. The cultures completely degraded 2,4-D, and the degradation was uninfluenced by the addition of mecoprop. Nearly complete dechlorination of the mixture of two herbicides was achieved by both cultures, on the basis of the total amount of the two herbicides degraded. During the course of the reaction, however, the expected values of chloride were not met. Cell growth continued after the degradation of the parent substrates ceased. Although the mecoprop degradation did not continue to completion, spectral and growth data indicated that the metabolites which had accumulated during the reaction were degraded upon further incubation.     

The equine protease inhibitory system (Pi): Abnormal expressions of PiF,PiL, and PiS

Three cases of abnormal expression of the equine protease inhibitory alleles, Pi F, L, and S₁, were observed following the examination of 30,000 plasma samples by one-dimensional acid (pH 4.6) polyacrylamide gel electrophoresis. Characterization of the abnormal proteins in terms of isoelectric point, molecular mass, inhibitory spectra, and sialic acid content was performed using one- and two-dimensional electrophoretic techniques. The Pi F and S₁ abnormalities were postulated to be the result of amino acid substitutions causing alterations in the processing of the carbohydrate side chains. No explanation could be offered for the Pi L abnormality other than a charge shift mutation. Abnormal types, F*, L*, and S*₁ behaved as alleles but the distribution of L* in offspring from one stallion (present in only 6 of 83 offspring) differed significantly from expectation.This work was supported by a grant from the Australian Stud Book, Alison Road, Randwick, N.S.W. 2031.     

Cellular systems for the study of the biosynthesis of polyamines and ethylene,as well as of virus multiplication

Leaves of Chinese cabbage from healthy plants or from those infected with turnip yellow mosaic virus yield protoplasts which convert methionine to protein, S-adenosylmethionine, decarboxylated S-adenosylmethionine, spermidine, spermine and 1-aminocyclopropane-1-carboxylate. The enzyme spermidine synthase is entirely cytosolic and has been purified extensively. An inhibitor of this enzyme, dicyclohexylamine, blocks spermidine synthesis in intact protoplasts, and in so doing stimulates spermine synthesis. Aminoethoxyvinylglycine blocks the conversion of S-adenosylmethionine to 1-aminocyclopropane-1-carboxylate, the precursor to ethylene, in protoplasts. This inhibitor markedly stimulates the synthesis of both spermidine and spermine. Essentially all the protoplasts obtained from new leaves of plants infected 7 days earlier are infected. On incubation, such protoplasts convert exogenous methionine to viral protein and viral spermidine whose specific radioactivity is twice that of total cell spermidine. Exogeneous spermidine is also converted to cell putrescine and viral spermidine and spermine. Normal and virus-infected cells are being studied for their content of phenolic acid amides of the polyamines.     

Processing of proapolipoprotein AI requires specific conformation

Apolipoprotein AI of human high-density lipoproteins is secreted by hepatocytes as a proapolipoprotein with a N-terminal hexapeptide sequence (Arg-His-Phe-Trp-Gln-Gln-) which differs from the prosequence of rat apolipoprotein AI (Trp-Asp-Phe-Trp-Gln-Gln). The two proteins have in common the unusual cleavage site -Gln-Gln-Asp-Glu-. It is hydrolysed by a specific serum proteinase with the release of mature apo AI. We synthesized a model substrate for the study of the final processing of pro-apo AI by the serum proteinase. It is an undecapeptide embracing the human pro-hexapeptide sequence and the first five N-terminal residues of apo AI, covalently linked to a hydrophilic resin. The N-terminal arginine residue was 3H-labelled. [formula; see text] This sequence was not cleaved by human serum under the conditions under which rat serum processes the pro-form of apo AI secreted by rat hepatocytes. Pepsin and chymotrypsin fragmented the undecapeptide at sites characteristic for these proteinases. We conclude that the proteolytic cleavage at the specific site (-Gln-Gln-Asp-Glu-) requires the correct conformation in addition to the specific amino-acid sequence.     

Determinants in the perceptions of visual blight

Research on visual blight has been predominantly qualitative and has pointed out salient attributes of blight: that it is durable, visually demeaning, and somehow aesthetically depressing. Data from a national sample (n=3005) are used in this study to measure the effect of demographic variation on the perception of visual blight. The perception of blight shows marked and regular variation with socioeconomic status, marital status, and religiosity.Harris data for this study was purchased with funds from the Shell Foundation. The author wishes to acknowledge Robert Q. Hanham, whose assistance proved invaluable.