Prebiotic sugar synthesis: Hexose and hydroxy acid synthesis from glyceraldehyde catalyzed by iron(III) hydroxide oxide

Summary Iron(III) hydroxide oxide [Fe(OH)O] efficiently catalyzed the condensation of 25 MM dl-glyceraldehyde to ketohexoses at 25°C (pH 5–6). At 16 days the yields were sorbose (15.2%), fructose (12.9%), psicose (6.1%), tagatose (5.6%), and dendroketose (2.5%) with 19.6% of triose unreacted. Analysis at 96 days showed no decomposition of hexoses. Under these conditions Fe(OH)O also catalyzed the isomerization and rearrangement of glyceraldehyde to dihydroxyacetone and lactic acid, respectively. In these reactions, about 10% of the glyceraldehyde was oxidized to glyceric acid with concurrent reduction of the iron(III) to iron(II). The partial reduction of Fe(OH)O did not noticeably reduce its ability to catalyze hexose synthesis. The relationship of these results to prebiotic sugar synthesis is discussed.     

Adipogenic cell line TA1: a suitable model to study the effect of beta-adrenergic agonists on lipid metabolism.

The stable adipogenic cell line TA1 was investigated as a potential in vitro system to examine effects of beta-adrenergic agonists on lipid metabolism at the cellular level. Initial experiments were conducted to establish whether dexamethasone, indomethacin, or both in combination induce rapid differentiation of TA1 preadipocytes to adipocytes. Based on activity of fatty acid synthase, dexamethasone and indomethacin, individually and in combination, were observed to induce differentiation in TA1 cells at different rates (dexamethasone/indomethacin greater than indomethacin greater than dexamethasone). Dexamethasone/indomethacin induced complete differentiation in TA1 cells 4 days after confluence, as indicated by increased activity of fatty acid synthase, glycerol-3-phosphate dehydrogenase, and malic enzyme. Finally, mature TA1 adipocytes were treated with various concentrations of isoproterenol and ractopamine to determine the responsiveness of TA1 adipocytes to a beta-adrenergic challenge. Glycerol release was increased and fatty acid synthase activity was decreased in a dose-dependent manner for both isoproterenol and ractopamine. These results indicate that fully differentiated TA1 adipocytes may be useful to study direct cellular effects of lipolytic and lipogenic agents on lipid metabolism.     

Prostaglandin E2 secretion by day-6 to day-9 equine embryos

Prostaglandin E₂ (PGE₂) secreted by Day-6, Day-7, Day-8 and Day-9 equine embryos (ovulation = Day 0) during in vitro incubation was measured by radioimmunoassay. Embryonic PGE₂ secretion (ng/embryo/24 hr) was detectable on Day 6 (0.27±0.39), tended to increase (P <0.1) on Day 7 (0.57±0.88), and increased significantly (P <0.05) on Day 8 (2.23±0.86) and Day 9 (4.13±0.71). Embryo diameter at the start of the incubation period was linearly correlated (P <0.01) to embryonic PGE₂ secretion.     

Liver transplantation for hereditary tyrosinemia: the Quebec experience.

Sixteen tyrosinemic patients were evaluated in our institution for a possible liver transplantation. All patients showed biochemical and/or radiological evidence of liver dysfunction. Renal involvement was found to be more abnormal than expected. Seven patients have been transplanted, with two patients receiving a combined liver-kidney transplant. Hepatocarcinoma was detected in two of eight patients in whom the whole liver was examined. Six (37.5%) of the initial 16 patients have died since evaluation, one of the six dying after combined liver-kidney transplantation. Posttransplantation survival was 86%, with normal liver function, normal growth, and no recurrence of neurological crises on a normal diet.     

Isolation and characterisation of the Xenopus laevis albumin genes: loss of 74K albumin gene sequences by library amplification.

The blood of the frog X.laevis contains 2 albumins of 68,000 and 74,000 daltons which are encoded in the liver by two related mRNAs. When an amplified X.laevis DNA library was screened with cloned albumin cDNA only 68,000 dalton albumin gene sequences were isolated. Hybridisation of the albumin cDNA to Southern-blots of Eco R1 digested X.laevis DNA showed that the sequences present in the recombinants did not account for all the fragments which hybridised on the Southern-blots. This indicated that 74K albumin gene sequences exist but that they are not present in the amplified DNA library. A X.laevis genomic library was therefore constructed and screened for albumin genes without amplification. Both 68K and 74K albumin gene sequences were isolated. Recombinants containing 74K albumin gene sequences grew extremely poorly and this probably explains why the 74K albumin sequences were ot isolated from the amplified library. Characterisation of the cloned DNA indicates that there is one sequence coding for the 68K albumin but two different sequences coding for the 75K albumin.     

F-actin binding and bundling properties of fimbrin, a major cytoskeletal protein of microvillus core filaments

Fimbrin, previously recognized as a major structural protein of the microfilament core bundles of intestinal epithelial cell microvilli, has been purified to homogeneity and characterized. It is a nearly globular monomeric protein of apparent molecular weight 68,000 and has a single calcium binding site (Kd = 9 microM), for which magnesium ions compete. Fimbrin binds to F-actin and this interaction is characterized in detail. Under our optimal binding of conditions, fimbrin induces tightly packed F-actin bundles, similar to the bundles induced by villin, another microvillus structural protein. The formation of mixed fimbrin-villin-actin bundles provides a further step toward the full in vitro reconstitution of microvillus core filaments from its purified individual components. The reconstituted fimbrin-villin-actin bundles do not display the side arms characteristic of isolated microvillus cores. These results are discussed in terms of our current understanding of the organization of the microvillus core filaments and indicate that this structure contains two bundling proteins, villin and fimbrin. The results complement previous studies and now provide a minimal biochemical characterization of all four major actin-associated structural proteins so far identified in core filaments. Three of these (villin, fimbrin, and calmodulin) are calcium-binding proteins, emphasizing the concept of calcium control over submembranous microfilament organization.     

Die Homologie des Perigons der Zingiberaceen Ein Beitrag zur Morphologie und Phylogenie des Monokotylen-Perigons

Nicolaia elatior is used as an example to demonstrate that the mucronate tepals ofZingiberaceae correspond to hypsophylls (bracts) consisting of a leaf sheath and a rudimentary Oberblatt (= leaf petiole + lamina) represented by the mucro. Evidence for this interpretation is furnished by all available criteria: leaf sequence (exhibiting a complete continuum of forms from foliage leaves over cata- and hypsophylls to the tepals), nervature, and ontogeny.The present conception is compared with the well-founded thesis ofLeinfellner that the perigone ofLiliaceae is derived from the androecium. The different morphological status of the perigone in both families is not regarded as the result of different phylogenetic origin, but as a manifestation of morphogenetic transgressions from one phyllome category to an adjacent one: In theLiliaceae the perigone is under a strong morphogenetic influence of the androecium, and therefore displays staminal characters, in theZingiberaceae it is under the dominating influence of the extrafloral region, and thus appears as a hypsophyllous structure. If this assumption of a morphologically oscillating perigone is correct, it will be fundamentally impossible to demonstrate unequivocally the phylogenetic origin of the monocotyledonous perigone.

Im wissenschaftlichen Werk Prof. Dr.Walter Leinfellners steht an erster Stelle die Morphologie der Blütenorgane. Als sein dankbarer Schüler möchte ich ihm aus Anlaß seines 70. Geburtstages die folgende Studie zu einem Thema zueignen, das ihn wie mich gleichermaßen angesprochen hat und schon Gegenstand der Forschungsarbeit des Jubilars war: die Homologie des Monokotylen-Perigons.     

Actin acetylation in Drosophila tissue culture cells

In a permanent cell line derived from Drosophila embryos, cytoplasmic actin is produced as an unstable precursor, which is subsequently converted to a stable form. This conversion results in a reduction in isoelectric point, with no apparent change in molecular weight. The conversion involves an enzymatic acetylation, and results in an insensitivity to aminopeptidase digestion, suggesting N-terminal blockage. Both the acetylated and unacetylated actins can participate in the assembly of F-actin, but with different efficiencies.This work was supported by a grant from the NIH (GM 22866).