Target-specific arrest of mRNA translation by antisense 2'-O-alkyloligoribonucleotides.

We describe a novel experimental approach to investigate mRNA translation. Antisense 2'-O-allyl oligoribonucleotides (oligos) efficiently arrest translation of targeted mRNAs in rabbit reticulocyte lysate and wheat germ extract while displaying minimal non-specific effects on translation. Oligo/mRNA-hybrids positioned anywhere within the 5' UTR or the first approximately 20 nucleotides of the open reading frame block cap-dependent translation initiation with high specificity. The thermodynamic stability of hybrids between 2'-O-alkyl oligos and RNA permits translational inhibition with oligos as short as 10 nucleotides. This inhibition is independent of RNase H cleavage or modifications which render the mRNA untranslatable. We show that 2'-O-alkyl oligos can also be employed to interfere with cap-independent internal initiation of translation and to arrest translation elongation. The latter is accomplished by UV-crosslinking of psoralen-tagged 2'-O-methyloligoribonucleotides to the mRNA within the open reading frame. The utility of 2'-O-alkyloligoribonucleotides to arrest translation from defined positions within an mRNA provides new approaches to investigate mRNA translation.     

Linkage maps of porcine Chromosomes 3, 6, and 9 based on 31 polymorphic markers

Linkage maps of porcine Chromosomes (Chrs) 3, 6, and 9, based on 31 polymorphic markers, are reported. The markers include 14 microsatellites, 12 RFLPs, three protein polymorphisms, and two blood group loci. The genetic interpretations of 11 RFLPs are documented. The markers were scored in a three-generation Wild Boar/Large White pedigree, and genetic maps were constructed on the basis of two-point and multi-point linkage analysis. Altogether the maps span a genetic distance of 216 cM, and previous physical assignments indicate that the linkage groups cover major parts of the three chromosomes. Significant differences in recombination rates between the sexes were observed for all three chromosomes. The recombination rate on the q arm of Chr 6 was markedly low. Sixteen loci are informative with regard to comparative mapping, that is, they have previously been mapped in the human and/or mouse genomes.     

Insulin-like growth factor I enhances the formation of type I collagen in hydrocortisone-treated human osteoblasts

We have studied the effect of insulin-like growth factor I (IGF-I) on the formation of osteocalcin and type I collagen in isolated human osteoblasts. IGF-I at and above 0.1 nM stimulated the formation of type I collagen as measured by the type I procollagen carboxyterminal peptide (PICP), in human osteoblasts, incubated for 72 hrs in serumfree conditions. The secretion of osteocalcin was not affected by IGF-I while 1,25(OH)₂ vitamin D₃ significantly enhanced the formation of osteocalcin. When human osteoblast-like cells were incubated with hydrocortisone (1 M), a significant decrease in the release of both PICP and osteocalcin was seen. Addition of IGF-I to human osteoblasts also treated with hydrocortisone normalized the PICP-formation but did not affect the suppressed osteocalcin-formation. These data indicate that IGF-I reverses selective effects of hydrocortisone on bone.     

Fractionation of erytroblasts with affinitymediated modifications of their electrical properties using counter-current distribution

Enterally administered, heme is a good source of iron in humans and other animals, but the metabolism of heme by enterocytes has not been fully characterized. Caco-2 cells in culture provide a useful model for studying cells that resemble small intestinal epithelium, both morphologically and functionally. In this paper we show that heme oxygenase, the rate-controlling enzyme of heme catabolism, is present in abundance in Caco-2 cells, and that levels of its mRNA and activity can be increased by exposure of the cells to heme or metal ions (cadmium, cobalt). Caco-2 cells also contain biliverdin reductase activity which, in the basal state, is similar to that of heme oxygenase (approximately 40 pmole of product per mg protein per minute); however, when heme oxygenase is induced, biliverdin reductase may become rate-limiting for bilirubin production.Abbreviations BVR biliverdin reductase - DMEM Dulbecco's modified Eagles medium - DMSO dimethyl sulfoxide - HO heme oxygenase - 1xSSC a solution of 0.015 M sodium citrate/0.15 sodium chloride     

Factors controlling the population dynamics of the clonal helophyte Ranunculus lingua

Abstract. Two marginal and two central populations of the pseudo-annual aquatic plant Ranunculus lingua were studied over four years. The main purpose was to quantify potentially influential abiotic and biotic factors and to derive predictions about life-history differences between the populations. Variation in abundance and height of R. lingua ramets at different depths were related to water-level fluctuations, to abundance of other helophyes (emergent macrophytes), and to the occurrence of invertebrate grazing and fungal pathogens. Clear differences between marginal and central populations were shown in the depth distribution of ramet numbers and ramet heights, as well as in the dynamic patterns, where marginal populations had a higher flux of ramets. These patterns and regression analyses indicated that abiotic factors have a greater influence in marginal populations, whereas biotic factors are more important in central populations. It is suggested that marginal habitats for R. lingua would favour life-histories with a high reproductive capacity, whereas a large size of ramet would be the most important life-history feature in central habitats. This was supported by the fact that ramets in marginal populations, in spite of their smaller size, produced higher number of rhizomes than ramets in central populations. Variation in regional abundance was finally related to differences in demographic processes and dispersal potential between the populations.     

Affinity-mediated modification of electrical charge on a cell surface: a new approach to the affinity partitioning of biological particles.

Polylysine has been covalently bound to human transferrin in a 1:1 molar ratio over a disulfide bond that can be easily split by reducing agents such as dithiothreitol. The association constant for the binding of the transferrin-polylysine derivative to transferrin receptors present on rat erythroblasts and the number of binding sites were identical to the corresponding values found for native transferrin. The incubation of the cells with transferrin-polylysine affected the partitioning of erythroblasts in a charge-sensitive aqueous two-phase system containing Dextran and polyethylene glycol. The polylysine part introduced a nonspecific influence on the partitioning that could be eliminated by preincubation of the cells with an excess of sialic acid. The partition ratio, G, of the erythroblasts changed with a factor of 1.9 for each set of 100,000 polylysine chains attached per cell.     

The porcine intestinal receptor for Escherichia coli K88ab,K88ac: regional localization on chromosome 13 and influence of IgG response to the K88 antigen

The loci encoding the porcine intestinal receptors for Escherichia coli K88ab and K88ac (K88abR and K88acR) were firmly assigned to chromosome 13 by linkage analysis using a three-generation pedigree. The linear order of these loci and seven other markers on chromosome 13 was determined by multipoint analyses. The K88abR and K88acR loci were tightly linked with the K88abR locus localized 7·4 cM (sex average) proximal to the transferrin locus. The results, together with previous reports from two other groups, provide an unequivocal assignment of the K88 receptor loci to chromosome 13, and reject a previous assignment to chromosome 4. Pigs possessing the receptor had a slightly higher specific IgG response to the K88 antigen after an intramuscular immunization with an E. coli vaccine.     

Structure of an acidic microcapsular glycan from the reference strain (C.D.C. 866-57) for Serratia marcescens serogroup 01

The structure of the acidic polysaccharide from Serratia marcescens serogroup O1 has been investigated. NMR spectroscopy together with sugar and methylation analysis have been used as well as a uronic acid degradation. The polysaccharide consists of pentasaccharide repeating units having the following structure.

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The polysaccharide also contains one equivalent of O-acetyl groups per repeating unit present on, inter alia, a hydroxymethyl group.     

Process monitoring of acetic acid in Escherichia coli cultivation using electrochemical detection in a flow injection system

A flow-injection system for determination of acetic acid in Escherichia coli cultivations with electrochemical detection based on immobilized acetate kinase (AK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) was developed to cope with the problems related to measurements under process conditions such as interferences from pyruvate, drift of electrode baseline and making the cultivation medium and reagents compatible. The results obtained by flow injection analysis were compared with those obtained with an enzymatic test kit.