Increase of sialyltransferase activity in the serum and liver of inflamed rates

Induction of inflammation by turpentine injection caused 1.5–2-fold increase of both sialy- and galactosyltransferase activity in liver homogenates. The effect was apparent after 12 h turpentine treatment. Serum sialytransferase activity started to increase in the inflamed rats after 18 h, reaching a maximum of 4-fold at 48 h. In contrast, galactosyltransferase activity in serum showed no significant increase. The coordinated and temporal increase of sialytransferase activity in liver and serum suggest involvement of a specific mechanism for the preferential release of this enzyme into serum.     

Mutant alpha-synuclein-induced degeneration is reduced by parkin in a fly model of Parkinson's disease.

Parkinson's disease (PD) patients show a characteristic loss of motor control caused by the degeneration of dopaminergic neurons. Mutations in the genes that encode alpha-synuclein and parkin have been linked to inherited forms of this disease. The parkin protein functions as a ubiquitin ligase that targets proteins for degradation. Expression of isoforms of human alpha-synuclein in the Drosophila melanogaster nervous system forms the basis of an excellent genetic model that recapitulates phenotypic and behavioural features of PD. Using this model, we analysed the effect of parkin co-expression on the climbing ability of aging flies, their life span, and their retinal degeneration. We have determined that co-expression of parkin can suppress phenotypes caused by expression of mutant alpha-synuclein. In the developing eye, parkin reduces retinal degeneration. When co-expressed in the dopaminergic neurons, the ability to climb is extended over time. If conserved in humans, we suggest that upregulation of parkin may prove a method of suppression for PD induced by mutant forms of alpha-synuclein.     

Modelling Nitrogen Content and Distribution in Cauliflower (Brassica oleracea L.botrytis )

A model of nitrogen uptake and distribution is presented whichdescribes these processes in relation to the amount of availablesoil nitrate and the rate of plant growth. Nitrogen uptake iseither sink or source limited. Sink limitation is based on maximumN-concentrations of plant compartments. The N-uptake model iscombined with a photosynthesis model based on the productivity-nitrogenrelationship at the single-leaf level. The model is parameterizedusing cauliflower as an example crop. Applied to an independentdata set, the combined model was able to predict leaf, stemand inflorescence nitrogen concentrations with correlation coefficientsbetween predicted and simulated values of 0.89, 0.66 and 0.86,respectively. The influence of nitrogen supply and light intensityon leaf nitrate-N could also be predicted with good accuracy(r² = 0.87). Dry matter production based on the productivity-Nrelationship and the partitioning into leaf, stem and inflorescencewas also reproduced satisfactorily (r² = 0.91, 0.93 and 0.92,respectively). Copyright 2000 Annals of Botany Company Brassica oleracea L. botrytis, cauliflower, nitrogen, nitrate, nitrogen supply, nitrogen uptake, nitrogen distribution, model     

Monitoring signal transduction in cancer: cDNA microarray for semiquantitative analysis.

This study targeted the development of a novel microarray tool to allow rapid determination of the expression levels of 58 different tyrosine kinase (tk) genes in small tumor samples. The goals were to define a reference probe for multi-sample comparison and to investigate the variability and reproducibility of the image acquisition and RT-PCR procedures. The small number of tk genes on our arrays enabled us to define a reference probe by artificially mixing all genes on the arrays. Such a probe provided contrast reference for comparative hybridization of control and sample DNA and enabled cross-comparison of more than two samples against one another. Comparison of signals generated from multiple scanning eliminated the concern of photo bleaching and scanner intrinsic noise. Tests performed with breast, thyroid, and prostate cancer samples yielded distinctive patterns and suggest the feasibility of our approach. Repeated experiments indicated reproducibility of such arrays. Up- or downregulated genes identified by this rapid screening are now being investigated with techniques such as in situ hybridization.     

Seasonal abundance and vertical distribution of mesopelagic calycophoran siphonophores in Monterey Bay, CA

The seasonal abundance and vertical distribution patterns ofa group of small calycophoran siphonophores (principally Chuniphyesmultidentata and Lensia conoidea) were investigated using aremotely operated vehicle (ROV) deployed in Monterey Bay, California.Abundance was assessed along 295 horizontal transects coveringa depth range of 100–1000 m over a three and a half yearperiod. The vertical distribution of the study animals changedseasonally, coupled to the onset and cessation of upwellingin the bay. While numerical abundance peaked after upwelling,there was no significant difference between seasons. The siphonophoreswere more broadly distributed over the depth range sampled duringthe upwelling or Shallow Mixed Layer (SML) period, than duringthe non-upwelling or Deep Mixed Layer (DML) period. There wereno significant differences in abundance or distribution patternsbetween years except in 1993, when there were significantlymore siphonophores observed during the SML period than duringthe DML period. This may reflect effects resulting from the1992–1993 El Niño event. The abundance of thesesiphonophores was negatively correlated with that of Nanomiabijuga, a physonect siphonophore of similar size and feedingbehavior found in the bay. The siphonophores studied here appearfrom preliminary data to migrate vertically, possibly with twoseparately migrating groups.     

Glycosylation of the phosphate binding protein, PstS, in Streptomyces coelicolor by a pathway that resembles protein O-mannosylation in eukaryotes

Previously mutations in a putative protein O -mannosyltransferase (SCO3154, Pmt) and a polyprenol phosphate mannose synthase (SCO1423, Ppm1) were found to cause resistance to phage, φC31, in the antibiotic producing bacteria Streptomyces coelicolor A3(2). It was proposed that these two enzymes were part of a protein O-glycosylation pathway that was necessary for synthesis of the phage receptor. Here we provide the evidence that Pmt and Ppm1 are indeed both required for protein O-glycosylation. The phosphate binding protein PstS was found to be glycosylated with a trihexose in the S. coelicolor parent strain, J1929, but not in the pmt ⁻ derivative, DT1025. Ppm1 was necessary for the transfer of mannose to endogenous polyprenol phosphate in membrane preparations of S. coelicolor . A mutation in ppm1 that conferred an E218V substitution in Ppm1 abolished mannose transfer and glycosylation of PstS. Mass spectrometry analysis of extracted lipids showed the presence of a glycosylated polyprenol phosphate (PP) containing nine repeated isoprenyl units (C₄₅-PP). S. coelicolor membranes were also able to catalyse the transfer of mannose to peptides derived from PstS, indicating that these could be targets for Pmt in vivo .