Biomedical subjects

Youji Sakagami

Publications and source records attributed to Youji Sakagami.

26 records · Page 2Linked to original sources

PubMed2003

Phytosulfokine stimulates somatic embryogenesis in Cryptomeria japonica.

Phytosulfokine (PSK), which has been identified as a plant growth factor, had a dramatic stimulatory effect on the formation of somatic embryos of sugi (Cryptomeria japonica) in the presence of polyethylene glycol. The resultant somatic embryos germinated with synchronous sprouting of cotyledons, hypocotyls and roots, and most of the seedlings grew normally. A cDNA clone for the precursor to the PSK peptide of C. japonica was identified in an expressed sequence tags database. Our results support the existence of a PSK signaling pathway in C. japonica.

Amino Acid Sequence↗

PubMed2003

Three new cytotoxic acylspermidines from the soft coral, Sinularia sp.

Three new acylated spermidines and two known related compounds were isolated from the Okinawan soft coral, Sinularia sp. These compounds were N',N",N"-trimethylspermidines that are acylated by a methyl-branched unsaturated fatty acid. These acylspermidines showed potent cytotoxicity against human tumor cell lines at an IC(50) value of 17 ng/ml and the induction of apoptotic phenomena.

Acylation↗

PubMed2003

Structural studies and antifungal activity of unique polyene amides, clathrynamide A and three new derivatives, from a marine sponge, Psammoclemma sp.

Known polyene amide, clathrynamide A, and three novel related metabolites, debromoclathrynamide A, (4E,6E)-debromoclathrynamide A and (6E)-clathrynamide A, were isolated from an Okinawan marine sponge, Psammoclemma sp. The absolute stereochemistry of clathrynamide A was determined to be 3R,12R by the modified Mosher method. The structures of the three new compounds were elucidated by spectroscopic analyses as debromo derivatives and geometrical isomers. Their antifungal activities were also evaluated with a phytopathogenic fungus, indicating that both the bromine atom and double-bond geometry affected the activity.

Amides↗

PubMed2003

Biosynthetic studies on a myxobacterial antibiotic, cystothiazole A: biosynthetic precursors of the carbon skeleton.

Biosynthetic studies on cystothiazole A (1), a beta-methoxyacrylate-type antifungal compound from a myxobacterium, were performed by feeding the producing organism, Cystobacter fuscus, with stable-isotope-labeled compounds including [2-(13)C]acetate, [1,2-(13)C2]acetate, [1-(13)C]propionate, L-[1-(13)C]serine, L-[methyl-(13)C]methionine, and DL-valine-d8. The polyketide moiety of 1 was found to be derived from acetate and propionate, the bithiazole moiety from L-serine, the O-methyl groups from the S-methyl group of L-methionine, and the isopropyl moiety from L-valine, which should be the metabolic precursor of isobutyryl-CoA.

Carbon Isotopes↗

PubMed2003

New haliangicin isomers, potent antifungal metabolites produced by a marine myxobacterium.

Haliangicin is a beta-methoxyacrylate-type polyene antibiotic isolated from the unique marine myxobacterium Haliangium ochraceum. A further investigation of the extract of this microorganism has resulted in the isolation of haliangicin as well as its geometrical isomers. The configuration of the epoxide in haliangicin, which was unknown previously, was determined in this study. The planar structures with partial stereochemistry of these isomers were elucidated by spectroscopic analyses. The major isomer, cis-haliangicin, is a cis isomer of the epoxide portion of haliangicin. Haliangicins B approximately D are geometrical isomers of the polyene moiety, and present as an inseparable mixture of cis and trans epoxide isomers. Their antifungal activities were also evaluated in comparison with haliangicin.

Antifungal Agents↗

PubMed2002

An LRR receptor kinase involved in perception of a peptide plant hormone, phytosulfokine.

The sulfated peptide phytosulfokine (PSK) is an intercellular signal that plays a key role in cellular dedifferentiation and proliferation in plants. Using ligand-based affinity chromatography, we purified a 120-kilodalton membrane protein, specifically interacting with PSK, from carrot microsomal fractions. The corresponding complementary DNA encodes a 1021-amino acid receptor kinase that contains extracellular leucine-rich repeats, a single transmembrane domain, and a cytoplasmic kinase domain. Overexpression of this receptor kinase in carrot cells caused enhanced callus growth in response to PSK and a substantial increase in the number of tritium-labeled PSK binding sites, suggesting that PSK and this receptor kinase act as a ligand-receptor pair.

Amino Acid Sequence↗

PubMed2002

Linckosides A and B, two new neuritogenic steroid glycosides from the Okinawan starfish Linckia laevigata.

Two new steroid glycosides, named linckosides A and B, were isolated from the Okinawan starfish Linckia laevigata, and their stereostructures were elucidated by spectroscopic methods and chemical derivatization. Each of them possesses two monosaccharide units at C-3 and C-29 of a polyhydroxylated steroid aglycon. These steroid glycosides showed not only notable neuritogenic activity against PC12 cells but also significant synergistic effects on the NGF-induced neuronal differentiation of PC12 cells. Linckoside B showed higher activities than those of linckoside A, though the structural difference is only the kind of a sugar.

Animals↗

PubMed2002

Peptide signalling in plants.

Peptide signals play crucial roles in all aspects of the plant life cycle. An understanding of peptide signal production and reception mechanisms is beginning to emerge. Studies on the signal-transduction cascades that follow the reception of peptide signals are just beginning.

Arabidopsis Proteins↗