CD44-deficient mice develop normally with changes in subpopulations and recirculation of lymphocyte subsets.

Cell adhesion molecules are considered to be pivotal elements required for proper embryo development. The transmembrane glycoprotein CD44, which is expressed in numerous splice variants on the surface of many different cell types and tissues, has been suggested to be involved in several physiological processes such as cell-cell interactions, signal transduction, and lymphocyte homing and trafficking during embryogenesis and in the adult organism. Some splice variants are thought to play an important role in tumor progression. To investigate the physiological roles of CD44 in vivo, we abolished expression of all isoforms of CD44 in mice by targeted insertion of a lacZ/neo cassette into the reading frame of the leader peptide. CD44-deficient mice are viable without obvious developmental defects and show no overt abnormalities as adults. However, CD44-deficient lymphocytes exhibit impaired entry into the adult thymus, although lymphocyte development is apparently unaltered. Our data indicate that all splice variants of CD44 are dispensable for embryonic development and implicate a critical function for CD44 in lymphocyte recirculation.     

A photoregulated ligand for the nuclear import receptor karyopherin alpha.

The ability to orchestrate the transport of proteins between nucleus and cytoplasm provides cells with a powerful regulatory mechanism. Selective translocation between these compartments is often used to propagate cellular signals, and it is an intimate part of the processes that control cell division, viral replication, and other cellular events. Therefore, precise experimental control over protein localization, through the agency of light, would provide a powerful tool for the study and manipulation of these events. To this end, a prototype photoregulated nuclear localization signal (NLS) was derived from a native NLS. A library of 30 mutants of the bipartite NLS from Xenopus laevis nucleoplasmin containing a novel, photoisomerizable amino acid was prepared by parallel, solid-phase synthesis and screened in vitro for binding to the nuclear import receptor karyopherin alpha, which mediates the nuclear import of cellular proteins. A single peptide was identified in which the cis and trans photoisomers bind the receptor differentially. The strategy used to obtain this peptide is systematic and empirical; therefore, it is potentially applicable to any peptide-receptor system.     

Overall assessment of Monodus subterraneus cultivation and EPA production in outdoor helical and bubble column reactors

The outdoor production of Monodus subterraneus wasstudied in bubble column and helical reactors, mainly analysing the influenceofdilution rate, air flow rate and solar irradiance on growth rate andbiochemicalcomposition. Photoinhibition and photo-oxidation phenomena were also analysed.The cultures were stressed at high solar irradiance and dissolved oxygenconcentrations. A clear relationship between stress of the cultures and thefluorescence from PSII measurements was observed, the Fv/Fm ratio being lowerinthe helical reactor than in the bubble column. Growth rate and biomassproductivity were both a function of the average irradiance and the Fv/Fmratio;maximum values of 0.040 h^–1 and 0.54 gL^–1 d^–1 were measured. The influenceofphotoinhibition and average irradiance was modelled, the model also fitting theexperimental data reported by another author. The chlorophyll contenthyperbolically decreased, whereas the carotenoid content decreased linearlywiththe average irradiance. The higher the dilution rate the higher the protein andcarbohydrate content of the biomass, and the lower the lipid content. Theeicosapentaenoic acid (EPA) content ranged from 2.3 to 3.2% d.wt, the higherthe dilution rate, the lower EPA content, although the higher the EPAproportion. Maximum EPA productivity was only 9 mg L^–1d^–1, due to the stress to which the cultures wereexposed.     

Complement components and terminal complement complex in oesophageal smooth muscle of patients with achalasia.

This study investigates whether patients with achalasia exhibit autoimmune reactions with subsequent complement activation within oesophageal smooth muscle, vessels and neurones. Oesophageal muscular biopsies from 8 patients undergoing surgery for achalasia and from 6 patients operated for oesophageal cancer were investigated by immunofluorescence for the presence of the complement components C1q, C4, C3c, C3d, C9 and the C9 neoantigen of the terminal C5b-C9 complement complex. Tissues were also investigated for the expression of immunoglobulins (G,A,M) and of the antigens of rubella and varicella zoster viruses. In addition, sera of both patient groups were tested for the presence of autoantibodies against Auerbach's plexus. The terminal complement complex C5b-C9 was found within muscle cells from all patients with achalasia but in only one specimen from a patient with cancer. Two patients with achalasia also exhibited the terminal complement complex as well as IgM within ganglion cells. Muscle cells stained positive for the complement component C9 in all five patients with achalasia in whom this test was performed but in none of the control tissues. In addition, sera from four patients with achalasia contained antibodies against Auerbach's plexus. Studies for the complement components C1q, C4, C3c and for antigens of rubella and varicella zoster viruses revealed negative results in all patients and controls. The results of this study suggest that a complement activation is involved in the autoimmune pathogenesis of achalasia. However, the triggering mechanism of this phenomenon remains to be determined.     

The synthesis and hepatoprotective activity of esters of the lupane group triterpenoids

Hemisuccinates, hemiphthalates, acetylsalicylates, cinnamates, andp-methoxycinnamates of lupeol, betulin, and 3-O-acetylbetulin were synthesized via interaction with corresponding acid anhydrides or acid chlorides. A number of betulin esters in position 3 and 28 were shown to exhibit a pronounced hepatoprotective effect similar to that of betulin and silibor. These experimental data were in a good agreement with the computer prediction of their biological activity. Betulin 3,28-bishemiphthalate was more effective than carsil in models of experimental hepatitis caused by carbon tetrachloride, tetracycline, and ethanol.     

Sexual Reproduction and Early Plant Growth of the Wollemi Pine (Wollemia nobilis), a Rare and Threatened Australian Conifer

The two known populations of the recently discovered rare andthreatened Wollemi Pine (Wollemia nobilis Jones, Hill and Allen)consist of a small number of large multi-stemmed adult treesand small seedlings. Female and male cones are produced on adulttrees with pollen release occurring in spring (October–November).Seed cones mature 16–19 months later in late summer andautumn and appear to be produced annually. Approximately 10%of seed produced in two consecutive years was viable, 25% ofwhich was damaged by animals. Glasshouse studies showed thatseed germination at 25 °C (day)/16 °C (night) proceededslowly but steadily at approx. 4% per week until, after 6 months,88% of apparently viable seed had germinated with the remainderof the seed rotting. Growth of potted seedlings in this temperatureregime was continuous (after a lag period of 4–6 months)with the monopodial axis growing 0.05–0.25 m in the firstyear, 0.5–0.6 m in the second year and 0.25–0.35m in the third year, attaining a total height of 0.8–1.2m. Multiple orthotropic shoots developed on some plants at thisstage, some of which outgrew the primary shoot in height. Thediameter of the stem below the cotyledon (just above the soil)grew 3–7 mm in the first year, 10–14 mm in the secondand 15–20 mm in the third at which time it was 25–34mm. The average number of lateral branches produced was five–17in the first year, 25–36 in the second year and 24–30in the third year giving a total of 60–77. The establishmentof Wollemi Pine in the wild does not appear limited by the inherentviability of seed and potential for early growth of seedlings.Copyright 1999 Annals of Botany Company Wollemia nobilis, Wollemi Pine, Araucariaceae, conifer, rare and threatened plant, cone, seed, germination, seedling growth.     

The metalloproteinase ADAM‐12 regulates bronchial epithelial cell proliferation and apoptosis

Abstract. Objectives: The ADAMs (a disintegrin and metalloproteinase) enzymes compose a family of membrane‐bound proteins characterized by their multi‐domain structure and ADAM‐12 expression is elevated in human non‐small cell lung cancers. The aim of this study was to investigate the roles played by ADAM‐12 in critical steps of bronchial cell transformation during carcinogenesis. Materials and methods: To assess the role of ADAM‐12 in tumorigenicity, BEAS‐2B cells were transfected with a plasmid encoding human full‐length ADAM‐12 cDNA, and then the effects of ADAM‐12 overexpression on cell behaviour were explored. Treatment of clones with heparin‐binding epidermal growth factor (EGF)‐like growth factor (HB‐EGF) neutralizing antibodies as well as an EGFR inhibitor allowed the dissection of mechanisms regulating cell proliferation and apoptosis. Results: Overexpression of ADAM‐12 in BEAS‐2B cells promoted cell proliferation. ADAM‐12 overexpressing clones produced higher quantities of HB‐EGF in their culture medium which may rely on membrane‐bound HB‐EGF shedding by ADAM‐12. Targeting HB‐EGF activity with a neutralizing antibody abrogated enhanced cell proliferation in the ADAM‐12 overexpressing clones. In sharp contrast, targeting of amphiregulin, EGF or transforming growth factor‐α failed to influence cell proliferation; moreover, ADAM‐12 transfectants were resistant to etoposide‐induced apoptosis and the use of a neutralizing antibody against HB‐EGF activity restored rates of apoptosis to be similar to controls.Conclusions: ADAM‐12 contributes to enhancing HB‐EGF shedding from plasma membranes leading to increased cell proliferation and reduced apoptosis in this bronchial epithelial cell line.