N-Desmethylmajusculamide B, a lipopeptide isolated from the Okinawan cyanobacterium Okeania hirsuta.

A new lipopeptide, N-desmethylmajusculamide B (1), was isolated from the Okinawan cyanobacterium Okeania hirsuta along with 2 known compounds majusculamide A (2) and majusculamide B (3). The planar structure of (1) was elucidated by a detailed analysis of mass spectrometry and nuclear magnetic resonance spectra. The absolute configurations of the amino acid residues were determined using Marfey's analysis. The configuration of C-16 in the α-methyl-ß-keto-decanoyl moiety was determined unambiguously to be S by conducting a semisynthesis of N-desmethylmajusculamide B from 3. The cytotoxicity against mouse L1210 leukemia cells was evaluated for majusculamides (1-3).

Normal skeletal pattern formation in chick limb bud with a mesenchymal hole is mediated by adjustment of cellular properties along the anterior-posterior axis in the limb bud.

The chick limb bud has plasticity to reconstruct a normal skeletal pattern after a part of mesenchymal mass is excised to make a hole in its early stage of development. To understand the details of hole closure and re-establishment of normal limb axes to reconstruct a normal limb skeleton, we focused on cellular and molecular changes during hole repair and limb restoration. We excised a cube-shaped mass of mesenchymal cells from the medial region of chick hindlimb bud (stage 23) and observed the following morphogenesis. The hole had closed by 15 â€‹h after excision, followed by restoration of the limb bud morphology, and the cartilage pattern was largely restored by 48 â€‹h. Lineage analysis of the mesenchymal cells showed that cells at the anterior and posterior margins of the hole were adjoined at the hole closure site, whereas cells at the proximal and distal margins were not. To investigate cell polarity during hole repair, we analyzed intracellular positioning of the Golgi apparatus relative to the nuclei. We found that the Golgi apparatus tended to be directed toward the hole among cells at the anterior and posterior margins but not among cells at identical positions in normal limb buds or cells at the proximal and distal hole margins. In the manipulated limb buds, the frequency of cell proliferation was maintained compared with the control side. Tbx3 expression, which was usually restricted to anterior and posterior margins of the limb bud, was temporarily expanded medially and then reverted to a normal pattern as limb reconstruction proceeded, with Tbx3 negative cells reappearing in the medial regions of the limb buds. Thus, mesenchymal hole closure and limb reconstruction are mainly mediated by cells at the anterior and posterior hole margins. These results suggest that adjustment of cellular properties along the anteroposterior axis is crucial to restore limb damage and reconstruct normal skeletal patterns.

Okeanic acid-A, a trihydroxy fatty acid from the Okinawan cyanobacterium Okeania hirsuta.

Trihydroxy fatty acids are oxidative metabolites of polyunsaturated fatty acids isolated from plants, bacteria, fungi, and microalgae and have a variety of biological activities. In this study, a new trihydroxy fatty acid, okeanic acid-A (1), was isolated together with malyngic acid (2) and 15,16-dihydromalyngic acid (3) from the cyanobacterium Okeania hirsuta collected in Okinawa, Japan. The planar structure of 1 was elucidated by detailed analyses using high-resolution ESI-MS and 1D and 2D NMR spectroscopy. The absolute configurations of the hydroxy groups in 1 were determined unambiguously by chemical derivatisation and a modified Mosher's method. These cyanobacterial trihydroxy fatty acids (1-3) have identical configurations at their respective trihydroxy parts. Okeanic acid-A (1) showed mild growth-inhibitory activity against the marine diatom Nitzschia amabilis.