Cultivation of Microorganisms in the Cultural Medium Made from Squid Internal Organs and Accumulation of Polyunsaturated Fatty Acids in the Cells

The disposal and more efficient utilization of marine wastes is becoming increasingly serious. A culture media for microorganisms has been prepared from squid internal organs that are rich in polyunsaturated fatty acids (PUFAs). Both freshwater and marine bacteria grew well in this medium and some bacteria accumulated PUFAs in their lipids, suggesting uptake of exogenous PUFAs. Higher PUFA accumulations were observed in Escherichia coli mutant cells defective either in unsaturated fatty acid biosynthesis or fatty acid degradation, or both, compared to those without these mutations. Therefore, PUFA accumulation in cells can be improved by genetic modification of fatty acid metabolism in the bacteria. Squid internal organs would be a good source of medium, not only for marine bacteria but also for freshwater bacteria, and that this process may be advantageous to make efficient use of the fishery wastes and to produce PUFA-containing microbial cells and lipids.     

Dehydrolanuginolide,a cytotoxic constituent from the fruits of Michelia doltsopa

A bioassay-directed isolation scheme yielded three known germacranolides (dihydroparthenolide, lanuginolide and 11,13-dehydrolanuginolide) from an ethanol extract of the fruit of the title plant. Dehydrolanuginolide was identified as the plant constituent responsible for 9KB cytotoxicity.     

Molecular basis for the subunit assembly of the primase from an archaeon Pyrococcus horikoshii

Archaeal/eukaryotic primases form a heterodimer consisting of a small catalytic subunit (PriS) and a large subunit (PriL). The heterodimer complex synthesizes primer oligoribonucleotides that are required for chromosomal replication. Here, we describe crystallographic and biochemical studies of the N-terminal domain (NTD) of PriL (PriL(NTD); residues 1-222) that bind to PriS from a hyperthermophilic archaeon, Pyrococcus horikoshii, at 2.9 A resolution. The PriL(NTD) structure consists of two subdomains, the helix-bundle and twisted-strand domains. The latter is structurally flexible, and is expected to contain a PriS interaction site. Pull-down and surface plasmon resonance analyses of structure-based deletion and alanine scanning mutants showed that the conserved hydrophobic Tyr155-Tyr156-Ile157 region near the flexible region is the PriS-binding site, as the Y155A/Y156A/I157A mutation markedly reduces PriS binding, by 1000-fold. These findings and a structural comparison with a previously reported PriL(NTD)-PriS complex suggest that the presented alternative conformations of the twisted-strand domain facilitate the heterodimer assembly.     

Biosynthesis of uridine diphosphate N-acetyl-D-mannosaminuronic acid from uridine diphosphate N-acetyl-D-glucosamine in Escherichia coli: Separation of enzymes responsible for epimerization and dehydrogenation

The biosynthesis of uridine diphosphate N-acetyl-D-mannosaminuronic acid from uridine diphosphate N-acetyl-D-glucosamine occurs in two steps. The enzyme responsible for the first step, the epimerization of uridine diphosphate N-acetyl-D-glucosamine to uridine diphosphate N-acetyl-D-mannosamine, is separated by means of hydroxylapatite chromatography from the enzyme for the second step, the NAD-linked dehydrogenation of uridine diphosphate N-acetyl-D-mannosamine. At equilibrium of the epimerase reaction, the ratio of the glucosamine residue to the mannosamine residue is about 9:1.     

New butenolides from Aspergillus terreus

From the culture filtrate of Aspergillus terreus, seven related yellow substances were isolated and the simplest, C₁₇H₁₂O₅, was proved to be 3-(p-hydroxyphenyl)-4-hydroxy-5-(p-hydroxybenzylidene)-2(5H)-furanone.     

Tissue Binding Patterns and In Vitro Effects of <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> DNA-Binding Protein from Starved Cells

Campylobacter jejuni (C. jejuni) is frequently associated with axonal Guillain-Barré syndrome (GBS). We reported that C. jejuni DNA-binding protein from starved cells (C-Dps) binds to and damages myelinated nerves in vivo. We studied the binding patterns of C-Dps to nervous tissues and its in vitro effects on neural cells. Immunohistochemically, C-Dps labeled the nodes of Ranvier, the outermost parts of internodal myelin and the basement membrane in the peripheral nerves, and neurons and myelin in the central nervous tissues. Its binding was blocked by sulfatide. C-Dps bound to the cell surfaces of nerve growth factor (NGF)-treated PC12 cells leading to dose-dependent LDH release, which was inhibited by either heat-denaturation of C-Dps or coincubation with an anti-C-Dps mAb. However, its binding to the surfaces of cultured NSC34 cells, S16 cells, or dorsal root ganglion cells, did not induce cytotoxicity. These findings suggest a possible involvement of C-Dps in C. jejuni-related GBS.     

A novel pyridoxal 5'-phosphate-dependent amino acid racemase in the Aplysia californica central nervous system

D-aspartate (D-Asp) is found in specific neurons, transported to neuronal terminals and released in a stimulation-dependent manner. Because D-Asp formation is not well understood, determining its function has proved challenging. Significant levels of D-Asp are present in the cerebral ganglion of the F- and C-clusters of the invertebrate Aplysia californica, and D-Asp appears to be involved in cell-cell communication in this system. Here, we describe a novel protein, DAR1, from A. californica that can convert aspartate and serine to their other chiral form in a pyridoxal 5'-phosphate (PLP)-dependent manner. DAR1 has a predicted length of 325 amino acids and is 55% identical to the bivalve aspartate racemase, EC 5.1.1.13, and 41% identical to the mammalian serine racemase, EC 5.1.1.18. However, it is only 14% identical to the recently reported mammalian aspartate racemase, DR, which is closely related to glutamate-oxaloacetate transaminase, EC 2.6.1.1. Using whole-mount immunohistochemistry staining of the A. californica central nervous system, we localized DAR1-like immunoreactivity to the medial region of the cerebral ganglion where the F- and C-clusters are situated. The biochemical and functional similarities between DAR1 and other animal serine and aspartate racemases make it valuable for examining PLP-dependent racemases, promising to increase our knowledge of enzyme regulation and ultimately, D-serine and D-Asp signaling pathways.     

A Molecular Framework for Auxin-Mediated Initiation of Flower Primordia

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Highlights? Auxin-activated MP directly induces key floral regulators LFY, ANT, and AIL6 ? The LFY promoter contains conserved biologically relevant auxin response elements ? LFY, ANT, and AIL6 have redundant roles in flower primordium initiation ? LFY feeds back to the auxin pathway at least in part by directly inducing PID