Multiplicity of biochemical factors determining quality of growing birch leaves

Due to rapidly changing physical and biochemical characteristics of growing leaves, correlations between traits of foliage biochemistry and the performance indices of flush feeding herbivores may vary considerably following relatively minor changes in experimental conditions. We examined the effects of the seasonal and inter-tree variation of a comprehensive array of biochemical compounds on the success of an early season geometrid, Epirrita autumnata, feeding on maturing foliage of mountain birch, Betula pubescens ssp. czerepanovii. We monitored the concentrations of individual phenolics, sugars, total nitrogen, nitrogen of proteins, and nitrogen of soluble compounds, water and acetone-insoluble residue. Simultaneously we recorded larval consumption, physiological performance, growth, and pupal mass of E. autumnata. We found significant phenological changes in almost all leaf traits measured. In bioassays with half-grown leaves, leaf gallotannin concentrations showed a nonlinear effect: in trees with high foliar gallotannin concentrations (over 10 mg g⁻¹), physiological performance was strongly reduced by high gallotannin concentrations. In trees with lower gallotannin concentrations, on the other hand, larval growth was reduced by soluble proanthocyanidins, not gallotannins. Differences between high and low gallotannin trees largely depended on phenology, i.e., on the age of leaves. However, not all the differences in leaf traits between late (with high gallotannin concentrations at the time of the bioassay) and early flushing trees disappeared with leaf maturation, indicating that there is also phenology-independent variance in the tree population. In the full-grown leaves of all the study trees, low concentrations of water and of nitrogen of proteins (but not nitrogen of soluble compounds) were the main factors reducing pupal masses of E. autumnata, while neither gallotannin nor proanthocyanidins now played a significant role. The observed change in the factors underlying leaf quality (from gallotannins and proanthocyanidins to nitrogen and water) relate to the activity of the shikimate pathway and the formation of cell walls: gallotannins and proanthocyanidins are both produced in the pathway, and these tannins are assumed to contribute – via binding into cell walls – to tough and durable cell walls. Interestingly, low quality of leaves did not automatically translate into low foliar consumption (i.e., benefits to the tree). On the trees with young, high gallotannin leaves, larvae actually increased consumption on low quality foliage. In the group of trees with slightly more developed, low gallotannin leaves, the quality of leaves did not clearly modify amounts consumed. In full-grown leaves, low leaf quality strongly reduced leaf consumption. These results emphasize the strong influence of tree phenology on the relationships between biochemical compounds and the herbivore. Received: 30 November 1998 / Accepted: 1 March 1999     

Post-drainage changes in vegetation composition and carbon balance in Lakkasuo mire,Central Finland

The post-drainage changes in vegetation composition and carbon balance were studied on four site types (from minero- to ombrotrophic conditions) in Lakkasuo mire, central Finland, by directly comparing undrained and drained parts (30 years ago) of the mire. Drainage had drastically changed the species composition of the sites, especially at the minerotrophic sites, where almost all Sphagna had been replaced by forest mosses. On the ombrotrophic sites much of the mire vegetation still remained 30 years after drainage. Drainage had decreased the C stores in ground vegetation on the minerotrophic sites but increased them on the ombrotrophic sites. The changes were, however, very small compared to the changes in the tree stand, where the C stores had increased at all sites (increasing with nutrient level). The change in peat C balance over the 30-year post-drainage period was negative on the most nutrient-rich site, and positive on the others, increasing with lower nutrient levels. The decrease in the peat C balance on the most nutrient-rich site was compensated by the greater increase in the tree stand C stores and the changes in the total C balance (peat+tree stand+ground vegetation) remained positive on all sites. This revised version was published online in June 2006 with corrections to the Cover Date.     

Specificity of monoclonal antibodies to an EBV transformed B-cell line

Monoclonal antibodies were produced against an Epstein Barr virus (EBV) transformed human B-cell line with the following HLA specificities: HLA A2, B27, Cw2, Dr3,2. Antibodies from three clones, Mab B1, Mab B2 and B3 reacted with human Ia-like molecules on peripheral blood B cells, some monocytes, CLL cells, lymphoblastoid B-cell lines and some mixed leukocyte culture (MLC)-activated T cells, but were unreactive with leukoagglutinin (LA) and Concanavalin A (Con A)-activated T blasts and T-cell lines. Antibodies obtained from three other clones (Mab 4, 5 and 6) reacted with a mw 80,000 protein present on peripheral lymphocytes and on most of the lymphoblastoid T-and B-cell lines tested.     

Tissue interactions of Escherichia coli adhesins

Conclusions The E. coli adhesions show a remarkable tissue tropism in the human urinary tract. This obviously relates to the known compartmentation of glycoconjugates in the kidney. To function as a virulence factor in human urinary tract infections, an adhesin must evidently recognize such receptors at uroepithelia that are not excreted in soluble form in urine. This prerequisite is filled by P fimbriae but not by type-1 or S fimbriae. Most of the tissue interactions of E.coli adhesins involve binding to carbohydrate receptors, whereas the binding of the 075X adhesin to type IV collagen appears to rely on protein-protein interactions. Binding of P fimbriae to immobilized fibronectin is independent of the lectin activity of the fimbriae and suggests of an additional function for the fimbrillin in mediating interaction with matrix and basement membrane proteins. Such interaction might be useful after colonization and disruption of epithelial surfaces, when the lectin activity of the fimbriae is not any more important.     

Lysyl hydroxylase 3 is secreted from cells by two pathways

Lysyl hydroxylase 3 (LH3) is a post-translational modification enzyme with lysyl hydroxylase (LH), collagen galactosyltransferase (GT), and glucosyltransferase (GGT) activities. The active sites responsible for LH and GT/GGT activities of LH3 are localized separately in the carboxy- and the amino-terminal parts of the molecule, respectively. LH3 is found both intracellularly in the ER, as well as extracellularly in serum, the extracellular space and on cell surfaces, and is the only secreted LH isoform. In order to determine whether the activities of LH3 play a role in the secretion, we created various LH3 and mutant expression constructs and over-expressed the proteins in COS-7 and HT-1080 cells. Our data indicate that while the LH active site mediates retention of LH3 in the ER, the GGT active site is required for the secretion of LH3 into the extracellular space. Moreover, Brefeldin A treatment and cholesterol depletion of the cells revealed that the secretion of LH3 from the ER to the extracellular space occurs via two secretory pathways, which generate two glycoforms. LH3 molecules found in the cell medium are secreted through the Golgi complex, and the secretion is dependent on LH3 glycosyltransferase activity. LH3 found on the cell surface bypasses the Golgi complex.     

Development of a pharmaceutical apotransferrin product for iron binding therapy.

High-dose chemotherapy of patients with haematological malignancies results in extracellular iron accumulation and appearance of non-transferrin-bound iron, which is thought to predispose the patients to septic infections and contribute to organ toxicity. We describe the development of a human plasma-derived apotransferrin product for iron binding therapy. The product is purified from Cohn fraction IV of human plasma by two ion exchange chromatography steps and ultrafiltration. The process comprises solvent detergent treatment as the main virus inactivation step and 15 nm virus filtration and polyethylene glycol precipitation as removal steps for physico-chemically resistant infectious agents. Product characterization by electrospray and MALDI-TOF mass spectrometry indicated no other chemical modifications than N-linked glycan chains and disulphide bonds, except minor oxidation. The purity of the product was more than 98%, main impurities being IgG, IgA and hemopexin. The product had intact iron binding capacity and native conformation. A stable liquid formulation for the finished product was developed. The product has proved safe and well tolerated in early clinical trials in iron binding therapy.     

Crystal structures of an enantioselective fab-fragment in free and complex forms

Enantioselective antibodies can separate the enantiomers of a chiral compound in a highly specific manner. We have recently reported the cloning and applications of a recombinant Fab-fragment, ENA11His, in the enantioseparation of a drug candidate, finrozole, which contains two chiral centers. Here, the crystal structures of this enantioselective antibody Fab-fragment are determined in the absence of the hapten at a resolution of 2.75 A, and in the presence of the hapten at 2.05 A resolution. The conformation of the protein was found to be similar in both free and complex forms. The hapten molecule was tightly bound in a deep cleft between the light and heavy chains of the Fab-fragment. The complex structure also allowed us to describe the molecular basis for enantioselectivity and to deduce the absolute configurations of all the four different stereoisomers (a-d) of finrozole. The ENA11His antibody fragment selectively binds the SR (a) enantiomer from the racemic mixture of a and d-enantiomers, thus allowing separation from the pharmacologically most active RS enantiomer (d). In particular, Asp95 and Asn35 of the H-chain in the ENA11 His antibody seem to provide this specificity through hydrogen bonding.     

Cervical smears in assessment of the natural history of human papillomavirus infections in prospectively followed women

The value of cervical (Papanicolaou) smears in monitoring the natural history of cervical human papillomavirus (HPV) infections was assessed in a series of 513 women prospectively followed since 1981. On each clinic visit, the patients were subjected to colposcopy accompanied by cervical smears and/or punch biopsies. The latter were analyzed by light microscopy for concomitant cervical intraepithelial neoplasia (CIN) and by transmission electron microscopy (TEM) for HPV particles as well as for HPV structural proteins. The stromal immunocompetent cell (ICC) infiltrates were phenotypically characterized using monoclonal antibodies for T-cell subsets, NK and K cells and Langerhans cells. HPV DNA typing was accomplished by Southern blot, spot and in situ hybridization using probes for HPV 6, 11, 16, 18 and 31. Lesions showing only changes consistent with HPV infection (HPV-NCIN) were associated with less severe atypia in cervical smears than were lesions with coexistent CIN (HPV-CIN). Normal smears were observed, however, in 24.7% of the cases with HPV-NCIN lesions, in 11.5% of cases with HPV-CIN I lesions but only exceptionally in cases with HPV-CIN II and III lesions (2.2% and 3.3%). The percentages of the different ICC phenotypes did not correlate with the atypia in cervical smears, but there was a shift towards the lower values of the T-helper/T-suppressor (OKT4+/OKT8+) cell ratio in parallel with increasing atypia. The possibility of latent HPV infection was suggested by the detection of viral particles, HPV antigens and HPV DNA in lesions shedding normal cells in the smears. The high-risk HPV types 16 and 18 were associated with the highest frequency of severely atypical cells; in the majority of cases, the low-risk types HPV 6 and 11 presented with less severe atypia. The first cervical smear seems to be of value as a predictor of the natural history of HPV lesions, as indicated by the fact that regression was inversely and progression directly related to initial cellular atypia. The present results confirm the intimate association between HPV infections and CIN. Although the biologic potential of the HPV infections seems to be dependent on multiple factors, routine cervical smears, because of their potential value in monitoring the natural history of this infection, should constitute an important means in the prospective follow-up of these patients.