THE ANATOMY OF THE PISTILLATE INFLORESCENCE AND FLOWER OF CASUARINA VERTICILLATA LAMARCK (CASUARINACEAE)

The pistillate inflorescence of Casuarina verticillata is described as consisting of a primary axis bearing whorls of bracts with a cymule in the axil of each bract of the more central whorls. Each cymule consists of an atepallate, two-carpellate, syncarpous floret and two, lateral, once-lobed bracteoles. A “peripheral intercalary” meristem, in which divisions are primarily periclinal, forms a meshwork beneath the bracts from early development and moves the connate bracts centrifugally around the cymules and extends and binds the bracts, and to some extent the bracteoles, of the fertile part of the inflorescence together. Each bract receives a single trace; each cymule receives two traces. Each bundle extension of a cymule trace supplies: 1) a branch which joins its counterpart to become the anterior common carpellary bundle; 2) a second branch which joins its counterpart to become the posterior common carpellary bundle; and 3) a central branch which supplies a lateral bracteole. Within each floret, each common carpellary bundle provides a dorsal carpellary bundle, two ventral carpellary bundles (fertile anterior carpel) or one common ventral bundle (sterile posterior carpel). The ventral bundle-supplies join and form a single placental bundle which lies in the gynoecial septum, and which, in turn, supplies the two ovules in the anterior carpel. Whether the inflorescence is a simple racemose or a condensed cymose type cannot be determined from this species alone. The function of the sclerenchymatous, enclosing bracteoles and connate bracts is discussed.     

Human interferon omega (omega) binds to the alpha/beta receptor.

It was proposed that human interferon omega (omega) binds to the interferon alpha/beta receptor but not to the interferon gamma receptor. However, since no studies were performed to provide direct evidence for this hypothesis, we carried out cross-linking experiments and saturation binding assays between a 32P-labeled human interferon-alpha (Hu-IFN-alpha) and unlabeled Hu-IFN-alpha A, -beta, -gamma, and -omega. These assays demonstrated that Hu-IFN-alpha A, -beta, and -omega, but not Hu-IFN-gamma, were able to block binding of 32P-labeled Hu-IFN-alpha A to human cells. These results indicate that Hu-IFN-omega binds to the alpha/beta receptor.     

Expression and regulation of UDP-glucuronate: neolactotetraosylceramide glucuronyltransferase in the nervous system

Sulfoglucuronyl glycolipids (SGGLs) are temporally and spatially regulated molecules present in the nervous system during its development. The characteristics of the rat brain enzyme glucuronyltransferase involved in the biosynthesis of SGGLs have been described. The enzyme catalyzes the transfer of glucuronic acid (GlcA) from UDP-GlcA to terminal galactose of the neolacto (type 2) series of glycolipids to form beta 1-3-linked glucuronyl neolacto glycolipids. The enzyme was highly specific for the neolacto series of acceptor glycolipids, neolactotetraosylceramide (nLcOse4Cer), neolactohexaosylceramide (nLcOse6-Cer), and neolactooctaosylceramide (nLcOse8Cer) and was different from the drug-inducible phenol:GlcA transferase. Considerable activity of GlcA transferase was present in the adult rat cerebral cortex, even though SGGLs almost completely disappeared from the cortex by postnatal day 15. In the cerebellum, although levels of SGGLs increased with development, the specific activity of GlcA transferase declined. The results indicated that GlcA transferase was not a regulatory enzyme controlling the expression of SGGLs. Measurements of the levels of nLcOse4Cer and nLcOse6Cer in these neural tissues indicated that the availability of these precursors may regulate the differential expression of SGGLs seen previously. GlcA transferase was significantly reduced in the cerebellar Purkinje cell degenerating murine mutant (pcd/pcd), which is consistent with the loss of SGGLs in the cerebellum of this mutant and specific association of these glycolipids with Purkinje cells.     

Approach to the analysis of diuretics and masking agents by high-performance liquid chromatography—mass spectrometry in doping control

The application of thermospray and plasmaspray high-performance liquid chromatography—mass spectrometry to the analysis of diuretics and probenecid has been investigated. The latter method gave better ionization efficiency than the former, and its response was optimized by altering the solvent composition: best results were obtained with water—methanol—acetonitrile—trifluoroacetic acid. Using different proportions of these solvents, three isocratic systems were developed to separate the compounds under study. The principal characteristic of plasmaspray positive-ion mass spectra was a protonated molecular ion and very little fragmentation was evident. In the negative ionization mode, the plasmaspray method gave mass spectra showing more fragmentation, which resulted in additional structural information. The ability of trifluoroacetic acid to form negative cluster ions precluded its use as a mobile phase component. The minimum detectable amounts determined by the analysis in the positive-ion mode was compound-dependent, but generally ca. 10–150 ng. In many cases the compounds could be detected in urine extracts.     

A monoclonal antibody that detects a specific human neutrophil antigen involved in phorbol myristate acetate- and formyl-methionyl-leucyl-phenylalanine-triggered respiratory burst.

A mouse IgM mAb termed P1E3 was raised against resting human peripheral blood neutrophils and has been shown to recognize a cell-surface Ag with an apparent molecular mass of 155 kDa, as assessed by immunoprecipitation analysis. In addition to the main 155-kDa protein, an additional band of about 210 kDa was also recognized by P1E3 in Western blot analysis. Sequential immunoprecipitation assays showed that the Ag recognized by P1E3 differed from the CD29 and CD45 Ag. However, sequential immunoprecipitation assays carried out with two distinct anti-CD15 mAb and P1E3 showed that P1E3 reacted with CD15 or with a CD15-like Ag. P1E3 stained strongly resting human peripheral blood neutrophils, hardly reacted with peripheral blood monocytes and did not react with PBL and platelets, as assessed by immunofluorescence flow cytometry. P1E3 inhibited the respiratory burst induced by PMA or FMLP, but not the oxidative response induced by Con A or the calcium ionophores A23187 or ionomycin. Furthermore, P1E3 inhibited the activation of the Na+/H+ antiporter in response to PMA or FMLP and the phosphorylation of a protein of about 50 kDa in response to PMA. However, preincubation of neutrophils with P1E3 did not affect the increase in cytosolic free calcium concentration induced by FMLP. These data suggest that the Ag recognized by P1E3 may play a role in modulating the activation of the respiratory burst induced by PMA or FMLP, and that P1E3 seems to affect protein kinase C-mediated signal transduction mechanisms coupled to the induction of the respiratory burst.     

The xylanase introns from Cryptococcus albidus are accurately spliced in transgenic tobacco plants

The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells.     

Differential expression of heat shock proteins in Drosophila embryonic cells following metal ion exposure

Drosophila embryonic cells were exposed to a number of metal ions that have been previously reported to act as teratogens in mammalian systems, including some known to induce heat shock (stress) proteins in a variety of model systems. This study examined the effects of these ions both on differentiation of muscles and neurons and on the induction of heat shock proteins. Metals such as arsenate, cadmium, and mercury all inhibited neuron and/or muscle differentiation in Drosophila embryonic cultures, while they also induced the entire set of heat shock proteins. Two metal ions, nickel and zinc, were shown to induce only the 22-and 23-K proteins, a pattern similar to that seen in “classical” teratogens reported previously. None of the metals tested induced only the 26-and 27-K proteins. These results suggest that there exist different regulatory mechanisms responsible for the heat shock response.     

Three forms of phosphatase type 1 in Swiss 3T3 fibroblasts. Free catalytic subunit appears to mediate s6 dephosphorylation

The major 40 S ribosomal protein S6 phosphatase in Swiss mouse 3T3 fibroblasts is a type 1 enzyme (Olivier, A. R., Ballou, L. M., and Thomas, G. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, 4720-4724). Polyclonal antibodies were raised against a synthetic peptide containing the carboxyl-terminal 14 amino acids of the catalytic subunit of phosphatase 1 (PP-1C). Results from Western blot analysis and immunoprecipitation show that the peptide antiserum specifically recognizes PP-1C in cell extracts. Anion-exchange chromatography of cell extracts and Western blot analysis revealed three peaks of PP-1C termed A, B, and C. Peaks A and C are associated with the major type 1 S6 phosphatase activities, but peak B exhibits little activity. The phosphatase in peak A (Mr 39,000) appears to represent the free catalytic subunit, whereas the enzymes in peaks B and C display sizes of 68,000-140,000. Peak B contains two additional proteins of Mr 26,000 and 48,000 that co-immunoprecipitate with PP-1C, while peak C has a single additional protein of Mr 100,000. Fifteen min after serum withdrawal there is a 2-fold stimulation of S6 phosphatase activity in peak A that can be accounted for by an increase in the amount of PP-1C. The amount of PP-1C in the inactive peak B fraction also increases during this time and this increase is associated with changes in the phosphorylation state of the Mr 26,000 and 48,000 proteins. The results are discussed in relation to regulatory mechanisms which are thought to modulate the activity of type 1 phosphatase.