A nomenclature for the genes encoding the chlorophylla/b-binding proteins of higher plants

We propose a nomenclature for the genes encoding the chlorophylla/b-binding proteins of the light-harvesting complexes of photosystem I and II. The genes encoding LHC I and LHC II polypeptides are namedLhca1 throughLhca4 andLhcb1 throughLhcb6, respectively. The proposal follows the general format recommended by the Commision on Plant Gene Nomenclature. We also present a table for the conversion of old gene names to the new nomenclature.     

Isolation and characterization of high-mobility-group proteins from maize

Chromosomal nonhistone high-mobility-group (HMG) proteins were purified from nuclei of maize (Zea mays L. cv. A619) endosperm and leaf tissue. Tissuespecific differences were observed in their polypeptide patterns, in in-vitro phosphorylation experiments with a casein-kinase type II, and by Western blot analysis with antisera against different HMG proteins. Gelfiltration chromatography demonstrated that maize HMG proteins occur as monomers. By measuring the capacity of the HMG proteins to bind to the 5 flanking region of a zein gene, the sensitivity of the proteins to different temperatures, salt concentrations and pH values was determined.Abbreviations EMSA electrophoretic-mobility-shift assay - FPLC fast protein liquid chromatography - HMG high-mobility group - kDa kilodaltons - PVDF polyvinylidenedifluoride - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis We would like to thank Mrs. E. Brutzer for excellent technical assistance. We are indebted to Mrs. M. Strecker and Dr. W. Bessler of the Institut für Immunbiologie, Freiburg, FRG, for the preparation of antisera and we gratefully acknowledge helpful discussions with Drs. T. Quayle, R. Grimm and U. Müller of this institute. This work was supported by grants from the Deutsche Forschungsgemeinschaft and the Fond der Chemischen Industrie.     

Extended map for the phaseolin linkage group ofPhaseolus vulgaris L

Summary The linkage relationship of 11 bean (Phaseolus vulgaris) seed proteins (including phaseolin), 9 enzyme loci, and theP locus were analyzed in backcross and F₂ progenies by use of the software package Mapmaker. The progenies were obtained by crossing the breeding line XR-235-1 and the cultivar Calima. Allelic differences for seed protein loci were detected with SDS-PAGE and those for enzyme loci with starch gel electrophoresis and activity stains. The seed coat color of Calima is a red/beige mottled pattern and that of XR-235-1 is white. Segregation at theP locus was followed by recording the phenotype of the BC₁S₁ and F₃ seed. A linkage group comprising ca. 90 cM was detected with the following gene order:Est-2 — 11 —Pha — 8 — (Spe/Spg) — 24 — P — 9 — (Spa/Spv) — 16 —Spba — 22 —Mdh-1. In addition, another linkage group was detected: (Spd/Spf/Sph) — 5 -Spca. Therefore, the seed proteins appear to be organized in clusters in the bean genome.Florida Agricultural Experiment Station, Journal Series No. R-01131     

Differential accumulation of four phaseolin glycoforms in transgenic tobacco

An intron-less phaseolin gene [15] was used to express phaseolin polypeptides in transgenic tobacco plants. The corresponding amounts of phaseolin immunoreactive polypeptides and mRNA were similar to those found in plants transformed with a bean genomic DNA sequence that encodes an identical -phaseolin subunit. These results justified the use of the intron-less gene for engineering of the phaseolin protein by oligonucleotide-directed mutagenesis. Each and both of the two Asn residues that serve as glycan acceptors in wild-type phaseolin were modified to prevent N-linked glycosylation. Wild-type (wt^i–) and mutant phaseolin glycoforms (dgly ₁, dgly ₂ and dgly _1,2) were localized to the protein body matrix by immunogold microscopy. Although quantitative slot-blot hybridization analysis showed similar levels of phaseolin mRNA in transgenic seed derived from all constructs, seed from the dgly ₁ and dgly ₂ mutations contained only 41% and 73% of that expressed from the wild-type control; even less (23%) was present in seed of plants transformed with the phaseolin dgly _1,2 gene. Additionally, the profile of 25–29 kDa processed peptides was different for each of the glycoforms, indicating that processing of the full-length phaseolin polypeptides was modified. Thus, although targeting of phaseolin to the protein body was not eliminated by removal of the glycan side-chains, decreased accumulation and stability of the full-length phaseolin protein in transgenic tobacco seed were evident.Abbreviations bp base pair(s) - DAF days after flowering - GUS -glucuronidase - kb kilobase - kDa kilodalton     

Biological control of Pythium damping‐off by seed‐treatment with pseudomonas putida: Relationship with ethanol production by pea and soybean seeds

The relationship between biocontrol activity of Pseudomonas putida strain N1R against Pythium ultimum on pea and soybean seeds and the reduction in ethanol evolution by imbibed seeds was investigated under different treatment conditions, including temperature and numbers of seed‐applied cells of the bacterium. Treatment with strain N1R increased emergence at all temperatures, except for soybean at 12 °C and reduced ethanol concentration in the spermosphere of imbibed seeds at several temperatures. The concentration of bacterial cells in the seed treatment suspension also significantly affected biocontrol efficiency and reduced ethanol production, especially in pea seeds. In contrast, the duration (0–7 h) of submergence of seeds in bacterial suspension had little effect on biocontrol activity of N1R, although submergence of soybean seeds reduced their emergence even in the absence of the pathogen or biocontrol agent. Competition for seed‐derived compounds, including ethanol, is suggested to be one possible mechanism of biocontrol of Pythium by strain N1R, which is not known to produce antifungal antibiotics.     

The plasma membrane of Entamoeba histolytica: structure and dynamics.

The plasma membrane components of the parasitic protozoan Entamoeba histolytica, the causative agent of human invasive amebiasis, have been biochemically and immunologically characterized during the last decade. In addition, genes coding for certain surface proteins have been cloned. In spite of these advances, a unified characterization of plasma membrane antigenic components of the parasite is still required for badly needed advancements in the design of useful diagnostic, epidemiologic, and immunoprophylactic tools. Here we review current knowledge on this issue and address the problem of the considerable variation in the electrophoretic profiles of plasma membrane proteins obtained by different groups. In addition, the differences in the degree of recognition of reported membrane antigens with human immune sera, and the diverse interpretations concerning the possible functions of the surface molecules characterized are discussed. A comparative analysis of plasma membrane proteins of E histolytica trophozoites using three different isolation methods revealed that it is possible to select for specific membrane proteins, depending on the lysis conditions. In our view, the method of Calderón and Avila preserves more proteins than other methods tested. Using sera from recent cases of invasive amebiasis studied by several laboratories in various geographical areas, a basic antigenic pattern of 11 principal proteins with molecular weights of 220, 170, 150, 125, 97, 80, 60, 45, 20 and 9 kDA was established for the pathogenic E histolytica strain HM1:IMSS, used by most research groups.     

Contractile proteins in podocytes: immunocytochemical localization of actin and alpha-actinin in normal and nephrotic rat kidneys

Actin and alpha-actinin immunoreactive sites have been localized at the electron microscope level by the protein A-gold immunocytochemical technique in podocytes of normal and nephrotic rat renal tissues. In normal renal glomeruli, fibrillar networks located in the core of foot processes or bundles of micro filaments interconnecting them were found to be labelled for these two cytoskeletal proteins. On the other hand, in nephrotic renal glomeruli, concomitant with the loss of podocytic foot processes a reorganization of the podocytic cytoskeleton and a concentration of some of its elements into thick uniform bands was observed. Actin and alpha-actinin were revealed in these bands. Control experiments confirmed the specificity of the labelling obtained. Our results suggest that normal podocytes contain an actin-based contractile system that might contribute to the maintenance of the particular cell shape of these cells and that the rearrangement of the podocytic cyto-skeleton occurring in the nephrotic syndrome might account for the changes in the foot processes and contribute to the alteration in glomerular function. This work was supported by grants from the Medical Research Council of Canada     

Evolutionary aspects of trypanosomes: Analysis of genes

Summary The genes for four glycolytic enzymes ofTrypanosoma brucei have been analyzed. The proteins encoded by these genes show 38–57% identity with their counterparts in other organisms, whether pro- or eukaryotic. These data are consistent with a phylogenetic tree in which trypanosomes diverged very early from the main branch of the eukaryotic lineage. No definite conclusion can be drawn yet about the evolutionary origin of glycosomes, the microbodies of trypanosomes which contain most enzymes of the glycolytic pathway. A bias could be observed in the codon usage of the glycolytic genes and genes for other housekeeping proteins, indicating that trypanosomes may have selected a nucleotide sequence that enables efficient translation. However, the genes for variant surface glycoproteins (VSGs) do not show such a bias. This lack of preference for special codons is explained by the high evolutionary rate that could be observed for VSG genes.Presented at the FEBS Symposium on Genome Organization and Evolution, held in Crete, Greece, September 1–5, 1986     

Microheterogeneity of Micro tubule-Associated τ Proteins Is Due to Differences in Phosphorylation

We have studied the heterogeneity of the microtubule-associated tau proteins using tau-specific antibodies and two-dimensional electrophoresis. Both monoclonal and polyclonal antibodies to tau proteins recognize five bands in cow brain microtubule proteins run on sodium dodecyl sulfate (SDS)-polyacrylamide gels, with apparent molecular weights between 56,000 and 66,000. Immunoblots of cow brain microtubules separated on two-dimensional gels, using nonequilibrium pH gradient electrophoresis in the first dimension and SDS-gel electrophoresis in the second, reveal that greater than 30 isoforms of tau exist. The tau proteins vary in pI from 6.5 to 8.5, with the higher-molecular-weight forms being more acidic. The microheterogeneity of tau is not induced by cycling of microtubules, because two-dimensional immunoblots of tau from total brain are almost identical to those of tau from cycled tubules. Adult rat brain tau, which appears as three doublet bands on SDS gels, also exhibits considerable isoelectric heterogeneity, as does tau from 7-day-old rats, which appears as only one band on SDS gels. After dephosphorylation of cow brain tau with alkaline phosphatase, the highest-molecular-weight band disappears on SDS gels. On two-dimensional gels, the number of tau variants decreases by more than half after dephosphorylation, and the more basic species increase greatly in intensity. Preliminary experiments with tau labeled in vivo with 32PO4 also indicate that the more acidic tau proteins are the more highly phosphorylated forms. Thus, isoelectric heterogeneity of tau proteins exists at all ages and is due, at least in part to differences in the state of phosphorylation of tau isoforms.