Glycolytic enzymes in non-photosynthetic plastids of pea (Pisum sativum L.) roots

The presence of the glycolytic enzymes from hexokinase to pyruvate kinase in plastids of seedling pea (Pisum sativum L.) roots was investigated. The recoveries, latencies and specific activities of each enzyme in different fractions was compared with those of organelle marker enzymes. Tryptic-digestion experiments were performed on each enzyme to determine whether activities were bound within membranes. The results indicate that hexokinase (EC 2.7.1.2) and phosphoglyceromutase (EC 5.4.2.1) are absent from pea root plastids. The possible function of the remaining enzymes is considered.Abbreviations GADPH glyceraldehyde 3-phosphate dehydrogenase - PFK phosphofructokinase - PFP pyrophosphate: fructose 6-phosphate 1-phosphotransferase Bronwen A. Trimming gratefully acknowledges the award of a studentship from the Science and Engineering Research Council     

Vegetation Changes Following Large-scale Fence Removal Across a Protected Area Network Within the Kruger to Canyons Biosphere Reserve,South Africa

Ecosystems - In the early 1990’s, reserves adjacent to Kruger National Park (KNP) removed their fences to create a continuous landscape within the Kruger to Canyons Biosphere Reserve....     

Phosphorylation of the GABAA receptor by cAMP-dependent protein kinase and by protein kinase C: Analysis of the substrate domain

Previous work has shown that the GABA_A-receptor (GABA_A-R) could be phosphorylated by cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and a receptor associated kinase. However, no clear picture has yet emerged concerning the particular subunit subtypes of the GABA_A-R that were phosphorylated by PKA and PKC. In the present report we show that an antibody raised against a 23 amino acid polypeptide corresponding to a sequence in the putative intracellular loop of the 1 subunit of the receptor blocks the in vitro phosphorylation of the purified receptor by PKA and PKC. Moreover, N-terminal sequence analysis of the principal phosphopeptide fragment obtained after proteolysis of the receptor yielded a sequence that corresponds to the 3 subunit of the receptor. Such data provide additional support for our hypothesis (Browning et al., 1990, Proc. Natl. Acad. Sci. USA 87:1315–1317) that both PKA and PKC phosphorylate the -subunit of the GABA_A-R.Special issue dedicated to Dr. Paul Greengard.     

Inhibition of Bordetella pertussis filamentous hemagglutinin-mediated cell adherence with monoclonal antibodies

Abstract Filamentous hemagglutinin (FHA), a 220-kDa protein located on the surface of Bordetella pertussis , is one of the major cell adhesins of this bacterium. We have produced three hybridoma cell lines that express monoclonal antibodies (mAbs) against FHA: X3C, X3E and X4B. The anti-FHA mAbs X3C and X3E reacted with 220-kDa FHA protein bands on Western blots. The mAb X4B, which reacted with FHA in ELISA, did not bind to FHA in a Western blot assay. All three mAbs seemed to be directed to the same epitope or to epitopes in close proximity as suggested by competition ELISAs. All three mAbs were able to inhibit the adherence of Chinese hamster ovary cells to purified FHA, and they could also inhibit the FHA-mediated agglutination of goose red blood cells. The attachment of B. pertussis to epithelial cell monolayers was inhibited by the mAb X3C. These antibodies are very useful probes to identify the presence of FHA in bordetellae species and in clinical reagents such as pertussis vaccines, and to characterize the functional domains of this important bacterial adhesin.     

Ten-year stability of EEG biofeedback results for a hyperactive boy who failed fourth grade perceptually impaired class

Ten years ago, the first successful application of a clinical,private-practice based, EEG 14-Hz biofeedback training regimen for the treatment of learning disorders was performed by the author. After the 10-year-old boy, with presenting symptomology including a developmental reading disorder, hyperactivity, and an educational classification of perceptually impaired, continued symptom free for a period oftwo years, his case was submitted for publication. Ten years after his termination from successful treatment, his ongoingly normal social and academic functioning is noted and his EEG brainwave signature examined and compared with a population of 24 used-to-be learning disabled, one-half of which had a pretreatment state including the educational classification of perceptually impaired. This 10-year follow-up confirms the long-term stability of the results of this EEG 14-Hz biofeedback regimen. Current findings on recent medical research identifying a major cerebral locus of dysfunction for hyperkinesis and how it supports the electrode placements of this clinical office setting regimen is also discussed.     

Expression of A mating type genes of Coprinus cinereus in a heterologous basidiomycete host

The A mating factor of Coprinus cinereus determines compatibility in mating by regulating part of a developmental sequence that leads to dikaryon formation. The A genes that trigger development encode two different classes of homeodomain proteins, and for a successful mating, a protein of one class, HD 1, must interact with a protein of the other class, HD 2. In this report we show that C. cinereus A genes that encode HD 2 proteins, a2-1 and b2-1, can elicit A-regulated development in the heterologous host C. bilanatus. Transformation rates were very low, suggesting that the genes were poorly transcribed. The fact that the HD 2 genes are functionally expressed implies successful heteromultimeric association of putative DNA-binding proteins coded by the two Coprinus species. This interaction was sufficient to satisfy the need for different A factors in the formation of a fertile C. bilanatus dikaryon, but fertile dikaryons were more readily produced in matings with the a2-1 gene transformants. The C. cinereus A genes, b1-1 and d1-1, which encode HD1 proteins, were either not expressed or their proteins were non-functional in C. bilanatus. These experiments raise some interesting questions regarding HD1–HD2 protein interactions.     

Mouse chromosome 1

Chair of Committee for Mouse Chromosome 1     

Are the spatial patterns of weeds scale-invariant?

In previous empirical and modelling studies of rare species and weeds, evidence of fractal behaviour has been found. We propose that weeds in modern agricultural systems may be managed close to critical population dynamic thresholds, below which their rates of increase will be negative and where scale-invariance may be expected as a consequence. We collected detailed spatial data on five contrasting species over a period of three years in a primarily arable field. Counts in 20×20 cm contiguous quadrats, 225,000 in 1998 and 84,375 thereafter, could be re-structured into a wide range of larger quadrat sizes. These were analysed using three methods based on correlation sum, incidence and conditional incidence. We found non-trivial scale invariance for species occurring at low mean densities and where they were strongly aggregated. The fact that the scale-invariance was not found for widespread species occurring at higher densities suggests that the scaling in agricultural weed populations may, indeed, be related to critical phenomena.