Life history of Japanese Stypocaulon durum (Sphacelariales, Phaeophyceae)

Phenology, morphology, life history and responses to different temperature and photoperiod conditions were studied in Japanese Stypocaulon durum (Ruprecht) Okamura. Erect thalli of the species were collected year-round, but the mature thalli forming either uniloc-ular sporangia or two different types of plurilocular structures (evidently gametangia) on separate thalli were found only in winter. ln culture, an isomorphic life history is suggested for the species, alternating between a sporophyte forming unilocular sporangia and gam-etophytes forming plurilocular macro- (female) and micro- (male) gametangia. Contents of unilocular sporangia were not released, but germinated in situ, developing into erect thalli forming plurilocular gametangia. Macrogametangia released aplanogametes (oospores), but male gametangia appeared to be non-functional, although flagellated cells were once formed in the loc-uli. This is the first report of plurilocular gametangia in the species. Although the species grew well and matured under considerably lower temperature conditions than European Stypocaulon scoparium (L.) Sauvageau, its temperature requirements showed similarity to northwestern Atlantic Stypocaulon species. This supports the notion that northwestern Atlantic Stypocaulon is conspecific with S. durum.     

Human bone marrow stromal cells express an osteoblastic phenotype in culture

Summary This study reports the selection and characterization of osteogenic precursors from human bone marrow which were isolated by two “clonings” and successive subculturing. These cell lines express alkaline phosphatase activity. Gel electrophoresis of [³H]-proline labeled cultures showed that the cloned cells produce only type I collagen. They synthetize osteocalcin and osteonectin. They respond to 1,25 dihydroxy vitamin D₃ by increasing osteocalcin synthesis and secretion, and to parathyroid hormone by increasing cyclic AMP synthesis. After the third subculture in the absence of β-glycerophosphate, these cell lines formed lots of clusters which exhibit high alkaline phosphatase activity and positive von Kossa staining. X-ray energy spectrum shows that these cells are surrounded by “budding” structures containing calcium and phosphorus with a ratio Ca:P identical to those of pure hydroxyapatite. This process was associated with⁴⁵Ca uptake into the cells. All these data support the selection of osteogenic cells which may be of considerable clinical importance.     

Deep-water macroalgae from the Canary Islands: new records and biogeographical relationships

Due to the geographical location and paleobiogeography of the Canary Islands, the seaweed flora contains macroalgae with different distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae recently collected around the Canarian archipelago are discussed. These areBryopsidella neglecta (Berthold) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck,Hincksia onslowensis (Amsler et Kapraun) P. C. Silva,Syringoderma floridana Henry,Peyssonnelia harveyana J. Agardh,Cryptonemia seminervis (C. Agardh) J. Agardh,Botryocladia wynnei Ballantine,Gloiocladia blomquistii (Searles) R. E. Norris,Halichrysis peltata (W. R. Taylor) P. Huvé et H. Huvé,Leptofauchea brasiliensis Joly, andSarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae, support the strong affinity of the Canary Islands seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western Atlantic regions.     

Spatial organization and dynamics of the association of Rec102 and Rec104 with meiotic chromosomes

Meiotic double-strand breaks (DSBs) are formed by Spo11 in conjunction with at least nine other proteins whose roles are not well understood. We find that two of these proteins, Rec102 and Rec104, interact physically, are mutually dependent for proper subcellular localization, and share a requirement for Spo11 and Ski8 for their recruitment to meiotic chromosomes, suggesting that they work together as a functional unit. Rec102 associated extensively with chromatin loops during leptotene and zygotene and showed preferential binding in the vicinity at least of most DSB sites, consistent with a direct role in DSB formation. However, Rec102 was associated with both DSB-hot and DSB-cold regions, ruling out a simple model in which sites of DSB formation are dictated by where Rec102/104 complexes load. Both proteins persisted on chromatin until pachytene before abruptly disappearing, indicating that they remain on chromosomes well after DSB formation. These studies reveal unexpected behaviors for Rec102 and Rec104, and point to distinct roles and subcomplexes among the DSB proteins.     

Structure of the acidic microcapsular glycan from the reference strain (C.D.C. 6320-58) for Serratia marcescens serotype O14:K12

The acidic polysaccharide from Serratia marcescens serogroup O14:K12 was analyzed by means of chemical studies and NMR spectroscopy and its repeating unit structure found to be carbohydrate sequence [see text] O-Acetyl groups are proposed to be present in non-stoichiometric amounts on O-6 on one of the hexose residues in the main chain.     

Syndecan-4 Is a Major Syndecan in Primary Human Endothelial Cells In Vitro,Modulated by Inflammatory Stimuli and Involved in Wound Healing

Syndecans are important cell surface proteoglycans with many functions; yet, they have not been studied to a very large extent in primary human endothelial cells. The purpose of this study was to investigate syndecan-4 expression in cultured human umbilical vein endothelial cells (HUVECs) and assess its role in inflammatory reactions and experimental wound healing. qRT-PCR analysis revealed that syndecan-3 and syndecan-4 were highly expressed in HUVECs, whereas the expression of syndecan-1 and -2 was low. HUVECs were cultured with the inflammatory mediators lipopolysaccharide (LPS) and interleukin 1β (IL-1β). As a result, syndecan-4 expression showed a rapid and strong increase. Syndecan-1 and -2 expressions decreased, whereas syndecan-3 was unaffected. Knockdown of syndecan-4 using siRNA resulted in changes in cellular morphology and focal adhesion sites, delayed wound healing and tube formation, and increased secretion of the pro-inflammatory and angiogenic chemokine, CXCL8. These data suggest functions for syndecan-4 in inflammatory reactions, wound healing and angiogenesis in primary human endothelial cells.     

The role of vascular actors in two dimensional dialogue of human bone marrow stromal cell and endothelial cell for inducing self-assembled network

Angiogenesis is very important for vascularized tissue engineering. In this study, we found that a two-dimensional co-culture of human bone marrow stromal cell (HBMSC) and human umbical vein endothelial cell (HUVEC) is able to stimulate the migration of co-cultured HUVEC and induce self-assembled network formation. During this process, expression of vascular endothelial growth factor (VEGF₁₆₅) was upregulated in co-cultured HBMSC. Meanwhile, VEGF₁₆₅-receptor2 (KDR) and urokinase-type plasminogen activator (uPA) were upregulated in co-cultured HUVEC. Functional studies show that neutralization of VEGF₁₆₅ blocked the migration and the rearrangement of the cells and downregulated the expression of uPA and its receptor. Blocking of vascular endothelial-cadherin (VE-cad) did not affect the migration of co-cultured HUVEC but suppressed the self-assembled network formation. In conclusion, co-cultures upregulated the expression of VEGF₁₆₅ in co-cultured HBMSC; VEGF₁₆₅ then activated uPA in co-cultured HUVEC, which might be responsible for initiating the migration and the self-assembled network formation with the participation of VE-cad. All of these results indicated that only the direct contact of HBMSC and HUVEC and their respective dialogue are sufficient to stimulate secretion of soluble factors and to activate molecules that are critical for self-assembled network formation which show a great application potential for vascularization in tissue engineering.