HUMAN B CELL DIFFERENTIATION: DEPENDENCE ON INTERACTIONS WITH MONOCYTES AND T LYMPHOCYTES VIA CD40, CD80 (B7.1), AND THE CD2-LIGANDS CD48 AND CD58 (LFA-3)

B cell differentiation depends on cellular interactions with T lymphocytes and monocytes via adhesion molecules (AM). In order to characterize AM which are required for B cell differentiation immunoglobulin production using unseparated peripheral blood mononuclear cells (PBMC) was studied. Unstimulated human PBMC were cultured for 9 days with mAb directed at CD2/CD48, /CD58, CD59, CD5/CD72, CD11a—CD18/CD54, CD28/CD80, CD86, CD40/CD40L, or rat CD2 (control). B cell differentiation was quantified measuring IgM and in some cases IgA, IgG, and IgE production. IgM levels were significantly reduced by mAb against CD40, CD48, CD58 and CD80. The reduction was not due to isotype switching to IgA, IgG or IgE. The role of CD40, CD48, CD58 and CD80 was further investigated after depletion of different cell types. Depletion of monocytes and NK cells resulted in no detectable IgM production irrespective of added mAbs. In contrast, IgM production was still present after depletion of T cells and NK cells. Only mAb against CD80 and CD48 significantly reduced IgM production, the reduction of IgM production by anti-CD40 mAb was less than in the presence of T cells. Importantly, anti-CD58 mAb had no effect on IgM production after T cell and NK cell depletion. Taken together, the AM CD40, CD48, CD58, and CD80 are involved in Ig production of unseparated PBMCs. In this model of B cell differentiation only the AM CD58 depend on the presence of T cells while CD48 and CD80 help was found to be T cell independent.     

Embryo Development in Ripe Seeds of Eranthis hiemalis and its Relation to Gibberellic Acid

The ripe seeds of Eranthis hiemalis (L.) Salisb., the winter aconite, contain undeveloped embryos. At 20–25°C the embryos grow only little, and the seeds do not germinate. Rapid embryo development starts if the seeds, after 3 weeks of “after-ripening” at 20–25°C, are placed at low temperature, 3–4°C; germination then takes place after 2–3 months, Embryo development without germination occurs when the seeds are placed in gibberellic acid solutions at 20–25°C. Embryo development is inhibited at low temperature by the specific inhibitor of gibberellin biosynthesis, 2-chlorethyl cholin chloride, but is restored by the simultaneous addition of gibberellic acid. It is suggested that one early effect of the cold is to bring about a synthesis of gibberellin.     

New birkeniid anaspid from the Lower Devonian of Scotland and its phylogenetic implications

Abstract: A new possible stem gnathostome, Kerreralepis carinata gen. et sp. nov., is described on the basis of a single specimen from the Lower Devonian of the island of Kerrera in the Inner Hebrides, Scotland. It is recognized as an anaspid by the chevron‐like arranged rod‐shaped scales on the trunk, gill openings extending behind the orbits in a slanting row and a series of median dorsal ridge scales. This specimen also has a series of median ventral plates, indicating the presence of a preanal fin‐fold, which in turn has consequences for interpretations of other problematic stem gnathostomes and their phylogenetic context. A cladistic analysis supports a monophyletic Anaspida including the scale‐covered birkeniids but excluding Lasanius as well as anaspid‐like forms such as Euphanerops and Jamoytius. The establishment of a new genus and species increases the diversity of anaspids and allows for a more detailed study of anaspid interrelationships. An ingroup analysis using Lasanius as an outgroup resolves Birkenia as a rather basal anaspid, sister to all other anaspids, alternatively sister to a clade represented by the taxa from Ringerike, Norway, and the closely associated taxon from Saaremaa Island, Estonia. These topologies agree rather well with the present fossil record of anaspids.     

A new genus of Devonian tetrapod from North‐East Greenland,with new information on the lower jaw of Ichthyostega

Abstract: A new genus and species of Devonian tetrapod has been identified from material collected in 1947 from the southern slope of Mt. Celsius, Ymer Ø, North‐East Greenland. The specimen preserves both lower jaws, partial palate, premaxillae and maxillae, with a natural mould of parts of the shoulder girdle. The new taxon, Ymeria denticulata, shows differences in dentition, skull ornament and lateral line expression from both Acanthostega and Ichthyostega, but it shows a closer resemblance to the latter. A cladistic analysis not only suggests that Ymeria lies adjacent to Ichthyostega on the tetrapod stem, but also reveals substantial topological instability. As the third genus and the fifth species of tetrapod identified from North‐East Greenland, it demonstrates the high diversity of Devonian tetrapods in that region.     

The Interaction of Human Serum with the Plant Hormone Indole-3-Acetic Acid

It is well known that human serum inhibits the longitudinal root growth in Lupinus albus L and Triticum sativum Lam. This inhibitory effect has been ascribed to the IAA content in human serum, which unfortunately has never been measured quantitatively. Experiments are presented in which Triticum roots are grown in media with pooled human serum and varying concentrations of IAA. In the presence of 10^?5M p-chlorophenoxy-isobutyric acid (PCIB) and serum, minute IAA additions promoted the growth. This feature hardly could be expected were the serum inhibition in itself an IAA effect. In view of this finding, renewed but unsuccessful attempts were made to demonstrate a similar promotion in media without serum. To explain the observed response curves, it must be further assumed that serum components bind IAA reversibly. In experiments without PCIB in the medium the response curves were similar at a lower level of growth, except that no growth promotion by IAA was discernible. It is concluded, that the inhibiting effect of human serum on the growth of plant roots is not due to free IAA, although IAA in all probability occurs in that fluid.     

PRODUCTION AND WESTERN BLOT CHARACTERIZATION OF MONOCLONAL ANTIBODIES SPECIFIC FOR CAMPYLOBACTER JEJUNI AND CAMPYLOBACTER COLI

Reference strains of the Lior serogroups of Campylobacter jejuni and C. coli most frequently encountered in human infections were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting. Seven components appeared to be common to all strains. Purified components were obtained from one strain by electrophoretic separation and elution from preparative SDS-PAGE gels. The purified components were used to immunize BALB/c mice for monoclonal antibody production and to screen hybridoma tissue culture supernatants for specific antibody by enzyme immunoassay. Antibodies from selected hybridomas were characterized on western blots of C. jejuni, C. coli, C. fetus, Salmonella typhimurium, Proteus vulgaris, Citrobacter diversus and Escherichia coli whole cell lysates. At least nine of the monoclonal antibodies appeared to be specific for C. jejuni and C. coli and thus may be useful in tests for the rapid detection of these organisms in foods and other specimens.     

Morphometric, AFLP and plastid microsatellite variation in populations of Scalesia divisa and S. incisa (Asteraceae) from the Galápagos Islands

Analysis of the stem vasculature of the American climbing palm Desmoncus reveals structural features differing significantly from the Old World rattan genus Calamus . Desmoncus has a more directly continuous vascular system but nevertheless shows a vessel distribution that makes for high hydraulic resistance in the axial xylem. Desmoncus is like Calamus in having a single very wide metaxylem vessel in each central axial bundle and is also without direct vascular contact between protoxylem and metaxylem tracheary elements. However, in Desmoncus the stem vascular bundle system resembles that in tree palms (as has been described in the model palm Rhapis excelsa ) in having a continuing axial bundle that branches from each outgoing leaf trace together with a large number of bridge connections between leaf traces and peripheral axial bundles. Resistance to axial water transport is, however, evident in the narrowness of the continuing metaxylem elements in the peripheral stem vascular region. Desmoncus has scalariform perforation plates with few thickening bars in the metaxylem vessels, unlike the simple perforation plates found in Calamus . Thus, Desmoncus shows only limited convergence in stem vascular architecture toward the extreme modifications found in Calamus . This is not unexpected since it is clear that the climbing habit evolved independently in the two genera.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society, 2003, 142 , 243−254.     

Cultivation of Phytomonas françai Associated with Poor Development of Root System of Cassava1

ABSTRACT. In the state of Espirito Santo, Brazil, a cassava disease was recently described, and subsequently a high density of trypanosomatids was revealed in the latex of unhealthy plants. To better characterize this flagellate, Phytomonas françai, we tried to grow it axenically. Successful results were obtained using a biphasic medium containing rabbit blood in the solid phase and a defined medium as overlay.     

Systematics and Ecology of Protodrilus helgolandicus sp.n., an Interstitial Polychaete (Protodrilidae) from Subtidal Sands off Helgoland, German Bight

Protodrilus helgolandicus sp.n. is described and compared to similar species. Indirect sperm transmission by spermatophores and egg deposition are reported. Some data on life cycle, population dynamics and ecology are given.     

Comparison of iron,manganese, and phosphorus retention in freshwater littoral sediment with growth of Littorella uniflora and benthic microalgae

Sediment columns from an oligotrophic lake were percolatedwith artificial porewater in two 46-day experiments toexamine the effects of Littorella uniflora and benthicmicroalgae on retention of phosphorus (P) by either iron(Fe) or manganese (Mn). Cumulative retention of P, Fe, andMn was 2–5 times higher in sediment with L. uniflora thanin sediment with microalgae, because of higher P uptake andmore efficient Fe and Mn oxidation by L. uniflora than bymicroalgae. Thus 34% and 21%of added P was retained in L. uniflora inhabited sediments asmetal-oxide bound P compared to 11% and2% in microalgae inhabited sediments, inexperiments supplied with Fe and Mn, respectively. Theatomic ratio of Fe/P precipitation was about 1 and forMn/P precipitation it was about 5. These ratios indicateprecipitation of Fe(III)-phosphate (strengite) and metastableMn(IV)-compounds containing phosphate and hydroxide ions invariable amounts. In addition to metal-oxide P precipitation,increased P retention in the vegetated sediment was also causedby the presence of humic acid compounds, which accountedfor about 26% of total retained P.