Gracilaria species (Gracilariaceae, Rhodophyta) from southeastern Australia, including a new species, Gracilaria perplexa sp. nov.: Morphology, molecular relationships and agar content

Select species of the agarophyte Gracilaria were studied from southeastern Australia. The morphology and anatomy of species is described and molecular relations are inferred based on plastid and mitochon‐drial DNA sequence data. Agar yields and qualities are determined for each species. Gracilaria chilensis, found in Tasmania and Victoria, is morphologically and molecularly similar to G. chilensis from New Zealand and Chile and has low agar yields of 11–16%. Gracilaria cliftonii from Victoria, has high crude agar yield (52%) and is molecularly uniform. Gracilaria perplexa sp. nov., known only from Botany Bay, New South Wales, has an agar yield of 39%. The agar of G. perplexa is unusual in requiring the addition of 0.1 mol L^?1 NaCl for alcohol precipitation and is cold‐water (25°C) soluble because of the very high sulfate ester content. Molecular phylogeny shows that G. perplexa is closely related to Gracilaria preissiana from western Australia, but differs from the latter in its reduced branching and narrower more terete axes.     

Differential antibacterial activity of nitric oxide from the immunological isozyme of nitric oxide synthase transduced into endothelial cells.

Primary cultures of endothelial cells, grown on the three-dimensional matrix Gelfoam where they take on the morphology of these cells in vivo, were found to phagocytose Staphylococcus aureus and two strains of Escherichia coli. The phagocytosis was independent of opsonization, although once opsonized, these bacteria were phagocytosed by endothelial cells. As cytochalsin D inhibited the internationalization of S. aureus and E. coli, the phagocytosis by endothelial cells appears to be actin-dependent. Transducing the gene for nitric oxide synthase (NOS) II into endothelial cells allowed us to determine the importance of NO(*) in host immunity against these bacteria. While the growth of S. aureus was impeded by NOS II endothelial cells, two strains of E. coli were killed by an NO(*)-dependent pathway. We conclude that endothelial cells have microbicidal mechanisms that are selective for the type of pathogen encountered.     

Alteration in gene expression at the onset of human Y-79 retinoblastoma cell differentiation

We have tested the hypothesis that differentiation and growth arrest of Y-79 human retinoblastoma cells in culture is associated with a modification of gene expression. We first examined proteins translated from mRNAs isolated from Y-79 cells growing in suspension and in attachment cultures in serum-containing medium and found them to be markedly different. This suggests that membrane-substrate interactions are of major consequence in the biochemical differentiation of these cells. Secondly, we examined the patterns of proteins translated from attached cells which had been induced to morphologically differentiate into neuronal-like and glial-like cells by serum-withdrawal and dibutyryl cAMP treatment respectively. The in vitro translatable proteins of mRNAs isolated from these cultures were found to be markedly different from those of the suspension and attachment cultures. Thirdly, we found that treatment of cells growing in attachment culture in serum-containing medium supplemented with 8-bromo cAMP, butyrate and retinoic acid as well as dibutyryl cAMP resulted in discreet alterations in proteins translated in vitro from extracted mRNAs. Although all these substances inhibit the growth of Y-79 cells, only dibutyryl cAMP and butyrate result in morphological differentiation of cells. Our results suggest that (1) attachment and morphological differentiation of Y-79 cells are both related to specific alterations in gene expression and (2) differentiation and inhibition of cell growth by various agents can be correlated with changes in translatable mRNA species although all agents do not act in the same mode.     

Synthesis and X-ray crystal structure determination of two pseudopolymorphic forms of μ-[1,2-bis(diphenylphosphino)ethane] bis [chlorogold(I)]: a digold(I) DNA binder

An improved synthetic route to the linearly coordinated digold(I) complex, μ-[1,2-bis(diphenylphosphino)ethane]bis[chlorogold(I)], is reported. This complex crystallizes in two pseudopolymorphic forms from a chloroform/methylene chloride solution; the crystal and molecular structures of both are discussed and compared. In both crystal forms the potentially chelating diphenylphosphinoethane (dppe) ligand instead coordinates to two separate gold atoms. The coordination environment of each gold atom is linear in both pseudopolymorphs and the structures display normal goldchloride and goldphosphorus bond distances. On the molecular level, the pseudopolymorphs differ fundamentally by a twist about one of the gold phosphorous bonds with the phosphorous atoms of the dppe ligand adopting a transoid orientation relative to one another in both polymorphs. These conformations thus place the intramolecular gold atoms 6 Å apart and preclude intramolecular AuAu bonding interactions. As has been observed for related gold(I) complexes there are short intermolecular AuAu contacts of the order of 3.2 Å present in both structures. The conformational flexibility of the gold complex relative to its observed biological activity as a DNA binder is discussed.     

THE MORPHOLOGY AND DEVELOPMENT OF SOME PROMINENTLY STALKED SOUTHERN AUSTRALIAN HALYMENIACEAE (CRYPTONEMIALES,RHODOPHYTA). II. THE SPONGE-ASSOCIATED GENERA THAMNOCLONIUM KUETZING AND CODIOPHYLLUM GRAY1

Three members of the red algal family Halymeniaceae (Thamnoclonium dichotomum (J. Ag.) J. Ag., Codiophyllum flabelliforme (Sond.) Schmitz, and C. decipiens (J. Ag.) Schmitz) are investigated. All are endemic to southern and southwestern Australia, possess basal stalks of substantial size and firmness, and are consistently associated with specific sponge taxa. In each case, the sponges are bonded by collagen-like fibrils to the host cuticle without modifying the algal tissue at the ultrastructural level. Secondary cortication and prominent growth rings occur in the stalks of all three species, and in each the pit plugs between cells become wider, more convoluted and less electron dense with increasing distance from the surface. Such pit plugs are apparently a unique attribute of the stalked Halymeniaceae. The three species share pit plug, sponge association and stalk morphological features but are not otherwise closely related, as they actually represent three distinct genera.